JP2004193201A6 - Laser irradiation method - Google Patents

Abstract

An object of the present invention is to provide a method for manufacturing a semiconductor device or a laser irradiation method using a laser crystallization method capable of increasing the efficiency of substrate processing.
An island-shaped semiconductor film (sub-island) including one or more islands is formed by patterning. Next, the crystallinity of the sub-island is enhanced by laser light irradiation, and then the island is formed by patterning the sub-island. Further, the scanning path of the laser light on the substrate is determined from the pattern information of the sub island so that at least the sub island is irradiated with the laser light. That is, in the present invention, the laser beam is scanned so that at least the indispensable part can be crystallized at least, rather than irradiating the entire substrate with the laser beam.
[Selection] Figure 1

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a laser irradiation method in which a semiconductor film is crystallized using laser light or activated after ion implantation, and a method for manufacturing a semiconductor device.
[0002]
[Prior art]
In recent years, a technology for forming a TFT on a substrate has greatly advanced, and application development to an active matrix semiconductor display device has been advanced. In particular, a TFT using a polycrystalline semiconductor film has higher field effect mobility (also referred to as mobility) than a TFT using a conventional amorphous semiconductor film, and thus can operate at high speed. For this reason, it is possible to perform control of a pixel, which has been conventionally performed by a drive circuit provided outside the substrate, with a drive circuit formed on the same substrate as the pixel.
[0003]
By the way, as a substrate used for a semiconductor device, a glass substrate is considered promising rather than a single crystal silicon substrate in terms of cost. A glass substrate is inferior in heat resistance and easily deforms by heat. Therefore, in the case where a polysilicon TFT is formed on a glass substrate, using laser annealing for crystallization of the semiconductor film is very effective for avoiding thermal deformation of the glass substrate.
[0004]
The characteristics of laser annealing are that the processing time can be greatly shortened compared to annealing methods using radiation heating or conduction heating, and the substrate or semiconductor film is selectively and locally heated to cause almost thermal damage to the substrate. Is not given.
[0005]
The laser annealing method here refers to a technique for recrystallizing a damaged layer formed on a semiconductor substrate or a semiconductor film, or a technique for crystallizing a semiconductor film formed on a substrate. Moreover, the technique applied to planarization and surface modification of a semiconductor substrate or a semiconductor film is also included. The laser oscillation device to be applied is a gas laser oscillation device typified by an excimer laser, or a solid-state laser oscillation device typified by a YAG laser, and a semiconductor surface layer is irradiated with laser light for several tens of nano to several tens of microseconds. It is known to be crystallized by heating for a very short time.
[0006]
Lasers are roughly classified into two types, pulse oscillation and continuous oscillation, depending on the oscillation method. Pulsed lasers have a relatively high output energy, so the size of the beam spot should be several cm. ² As described above, mass productivity can be improved. In particular, when the shape of the beam spot is processed using an optical system to form a linear shape having a length of 10 cm or more, the substrate can be efficiently irradiated with laser light, and mass productivity can be further improved. For this reason, it has become the mainstream to use a pulsed laser for crystallization of the semiconductor film.
[0007]
However, in recent years, it has been found that the crystal grain size formed in a semiconductor film is larger when a continuous wave laser is used than when a pulsed laser is used for crystallization of a semiconductor film. As the crystal grain size in the semiconductor film increases, the mobility of TFTs formed using the semiconductor film increases. For this reason, continuous wave lasers are starting to attract attention.
[0008]
However, in general, a continuous wave laser has a smaller maximum output energy than a pulsed laser, and therefore the beam spot size is 10. ^-3 mm ² About small. Therefore, in order to process one large substrate, it is necessary to move the irradiation position of the beam on the substrate vertically and horizontally, and the processing time per substrate becomes long. Therefore, the efficiency of substrate processing is poor, and improvement of the substrate processing speed is an important issue.
[0009]
In addition, the technique which adjusts the length of a beam spot using a slit is conventionally used (for example, refer patent document 1 and patent document 2).
[0010]
[Patent Document 1]
JP 11-354463 A (page 3, FIG. 3)
[0011]
[Patent Document 2]
Japanese Patent Laid-Open No. 9-270393 (page 3-4, FIG. 2)
[0012]
A technique of crystallizing with a continuous wave laser beam after making a semiconductor film into an island shape has been conventionally used (see, for example, Non-Patent Document 1).
[0013]
[Non-Patent Document 1]
Akito Hara, Yasuyoshi Misima, Tatsuya Kakehi, Fumiyo Takeuchi, Michiko Takei, Kenichi Yoshino, Katsyuyuki Sugai. , "High Performance Poly-Si TFTs on a Glass by a Stable Scanning CW Laser Lateral Crystallization", IEDM2001.
[Problems to be solved by the invention]
[0014]
In view of the above-described problems, the present invention can increase the efficiency of substrate processing as compared with the prior art, and can also increase the mobility of a semiconductor film, and a laser irradiation method using a laser crystallization method that uses the same. An object is to provide a method for manufacturing a semiconductor device.
[0015]
[Means for Solving the Problems]
In the present invention, a portion to be an island-shaped semiconductor film (island) is grasped based on the data (pattern information) of the mask shape of the semiconductor film. Then, an island-shaped semiconductor film (sub island) including one or a plurality of the islands is formed by patterning. Next, the crystallinity of the sub-island is enhanced by laser light irradiation, and then the island is formed by patterning the sub-island.
[0016]
Furthermore, in the present invention, the scanning path of the laser beam on the substrate is determined based on the sub-island pattern information so that at least the sub-island is irradiated with the laser beam. That is, in the present invention, the laser beam is scanned so that at least the indispensable part can be crystallized at least, rather than irradiating the entire substrate with the laser beam. With the above configuration, it is possible to save time for laser light irradiation to a portion other than the sub-island, and thus it is possible to shorten the time required for laser light irradiation and improve the processing speed of the substrate. . Further, unnecessary portions can be irradiated with laser light to prevent the substrate from being damaged.
[0017]
In the present invention, a marker may be formed on the substrate by laser light or the like in advance, but a marker may be formed simultaneously with the sub island. By forming a marker at the same time as a sub island, the mask for the marker can be reduced by one, and the marker can be formed at a more accurate position than that formed by laser light, improving the alignment accuracy. Can be made. In the present invention, the position where the laser beam is scanned is determined based on the sub-island pattern information using the marker as a reference.
[0018]
In the present invention, the laser beam is intentionally scanned so that when the beam spot reaches the sub-island, the beam spot and the sub-island contact each other at one point when viewed from the direction perpendicular to the substrate. The scanning direction is determined. For example, when the sub-island has a polygonal shape as viewed from above the substrate, the laser beam is first scanned so that one of the corners of the sub-island is in contact with the beam spot. In addition, even when a part or all of the sub-island is curved when viewed from the substrate, the laser beam is used so that the beam spot and the curved part of the sub-island first contact each other at one contact point. The scanning direction is determined. When laser light irradiation is started from one contact, a crystal having a (100) plane orientation starts growing from the vicinity including the contact. When the laser light is scanned and the irradiation of the laser light to the sub island is completed, the orientation rate of the (100) plane of the entire sub island can be increased.
[0019]
If an island having a high (100) plane orientation ratio is used as the TFT active layer, the mobility of the TFT can be increased. Also, if the orientation ratio of the (100) plane of the active layer is high, the variation in the film quality of the gate insulating film formed thereon can be reduced, and therefore the variation in the threshold voltage of the TFT can be reduced. it can.
[0020]
Further, when the sub island is irradiated with laser light, microcrystals are formed in the vicinity of the edge of the sub island as viewed from above the substrate. This is thought to be because the way of diffusion of heat applied by the laser beam to the substrate differs between the vicinity of the edge and the central portion.
[0021]
Therefore, in the present invention, after crystallization by laser light, a portion having poor crystallinity in the vicinity of the edge is removed by patterning, and an island is formed using the center portion of the sub-island having relatively good crystallinity. Note that the designer can appropriately determine which part of the sub-island is removed by patterning to form the island. In this way, the island crystallinity can be further enhanced by forming the island after crystallizing the sub-island with laser light instead of directly crystallizing the island with laser light.
[0022]
Furthermore, in the present invention, a portion of the beam spot having a low energy density is shielded through the slit. By using the slit, it is possible to irradiate the sub-island with laser light having a relatively uniform energy density, and to perform crystallization uniformly. Further, by providing the slit, the width of the beam spot can be partially changed according to the sub-island pattern information, and the restrictions on the layout of the sub-island and the active layer of the TFT can be reduced. The beam spot width means the length of the beam spot in a direction perpendicular to the scanning direction.
[0023]
The shape of the beam spot used in the present invention includes an ellipse, a quadrangle, a linear shape, and the like.
[0024]
One beam spot obtained by synthesizing laser beams oscillated from a plurality of laser oscillators may be used for laser crystallization. With the above configuration, it is possible to compensate for the weak energy density of each laser beam.
[0025]
In addition, after the semiconductor film is formed or the sub-island is formed, laser light irradiation is performed so as not to be exposed to the atmosphere (for example, a specified gas atmosphere such as a rare gas, nitrogen, oxygen, or a reduced pressure atmosphere). The semiconductor film may be crystallized. With the above configuration, contaminants at the molecular level in the clean room, such as boron contained in a filter for increasing the cleanliness of air, can be prevented from being mixed into the semiconductor film during crystallization by laser light. it can.
[0026]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a laser light irradiation method and a semiconductor device manufacturing method of the present invention will be described with reference to FIGS.
[0027]
First, as shown in FIG. 1A, a semiconductor film 11 is formed over a substrate 10. The substrate 10 may be made of any material that can withstand the processing temperature of the subsequent process. For example, a quartz substrate, a silicon substrate, a glass substrate such as barium borosilicate glass or alumino borosilicate glass, a metal substrate, or a stainless steel substrate is provided with an insulating film. A substrate on which is formed can be used. Further, a plastic substrate having heat resistance enough to withstand the processing temperature may be used.
[0028]
Note that a base film made of an insulating film may be formed between the substrate 10 and the semiconductor film 11 in order to prevent impurities such as alkali metals contained in the substrate 10 from being taken into the semiconductor film 11.
[0029]
The semiconductor film 11 can be formed by a known means (sputtering method, LPCVD method, plasma CVD method, etc.). Note that the semiconductor film may be an amorphous semiconductor film, a microcrystalline semiconductor film, or a crystalline semiconductor film.
[0030]
Next, as shown in FIG. 1B, the semiconductor film 11 is patterned to form a sub-island (before laser crystallization (before LC)) 12 and a marker 18. Note that the shape of the marker is not limited to the shape shown in FIG.
[0031]
Then, as shown in FIG. 1C, the sub-island (before LC) 12 is irradiated with laser light to form a sub-island (after LC) 13 with improved crystallinity. In the present invention, the portion where the energy density of the beam spot is low is shielded by using the slit 17. The slit 17 is preferably formed of a material that can block the laser beam and that is not deformed or damaged by the laser beam. The slit 17 has a variable slit width, and the width of the beam spot can be changed according to the width of the slit.
[0032]
The energy density is determined to be low when the value necessary for obtaining the desired crystal is not satisfied. The designer can appropriately determine whether or not the crystal is desired. Therefore, if the crystallinity desired by the designer is not obtained, it can be determined that the energy density is low.
[0033]
The energy density of the laser beam is low in the vicinity of the edge of the beam spot obtained through the slit. Therefore, the crystal grain is small in the vicinity of the edge, and a portion (ridge) protruding along the crystal grain boundary is present. Appear. Therefore, the edge 15 of the locus of the laser light beam spot 14 is not overlapped with the sub-island (before LC) 12 or an island formed thereafter.
[0034]
The scanning direction of the laser beam is intentional so that when the laser beam is scanned and the beam spot reaches the sub-island, the beam spot and the sub-island touch at a single point when viewed from the direction perpendicular to the substrate. Stipulated in When laser light irradiation is started from one contact point, a crystal having an orientation of (100) plane starts from the vicinity including the contact point. Therefore, when irradiation of the laser light to the sub island is finished, The orientation rate of the (100) plane of the entire island can be increased.
[0035]
In the present invention, a known laser can be used. As the laser, a continuous wave gas laser or solid laser can be used. There are excimer laser, Ar laser, Kr laser, etc. as gas laser, and YAG laser, YVO as solid laser. ₄ Laser, YLF laser, YAlO ₃ Laser, glass laser, ruby laser, alexandride laser, Ti: sapphire laser, Y ₂ O ₃ A laser etc. are mentioned. Solid lasers include YAG, YVO doped with Cr, Nd, Er, Ho, Ce, Co, Ti, Yb or Tm. ₄ , YLF, YAlO ₃ Lasers using crystals such as are applied. The fundamental wave of the laser differs depending on the material to be doped, and laser light having a fundamental wave of around 1 μm can be obtained. The harmonic with respect to the fundamental wave can be obtained by using a nonlinear optical element.
[0036]
Furthermore, after converting infrared laser light emitted from a solid-state laser into green laser light using a nonlinear optical element, ultraviolet laser light obtained by another nonlinear optical element can also be used.
[0037]
The marker 19 may or may not be irradiated with laser light.
[0038]
Next, as shown in FIG. 1D, the island 16 is formed by patterning the sub-island (after LC) 13. It is preferable that the island 16 avoids the vicinity of the edge of the sub-island and uses a portion having relatively excellent crystallinity at the center. In the patterning, the marker 19 is left for alignment of a mask used in a later process.
[0039]
The island 16 produced by the above process has excellent crystallinity and an increased orientation ratio of the (110) plane.
[0040]
Next, the shape of the beam spot synthesized by superimposing a plurality of beam spots will be described.
[0041]
FIG. 4A shows an example of the shape of the beam spot on the object to be processed when the laser light emitted from each of the plurality of laser oscillation devices does not pass through the slit. The beam spot shown in FIG. 4A has an elliptical shape. In the present invention, the shape of the beam spot of the laser light emitted from the laser oscillation device is not limited to an ellipse. The shape of the beam spot varies depending on the type of laser, and can also be shaped by an optical system. The shape of the laser light emitted from the YAG laser is circular if the rod shape is cylindrical, and rectangular if it is slab type. By further shaping such laser light with an optical system, laser light of a desired size can be produced.
[0042]
FIG. 4B shows the energy density distribution of the laser beam in the major axis y direction of the beam spot shown in FIG. The energy density distribution of the laser beam having a beam spot having an elliptical shape becomes higher toward the center O of the ellipse. α corresponds to the width in the major axis y direction where the energy density exceeds the value required to obtain the desired crystal.
[0043]
Next, FIG. 2A shows the shape of the beam spot when the laser beam having the beam spot shown in FIG. 4 is synthesized. Note that FIG. 2A illustrates the case where one linear beam spot is formed by superimposing the beam spots of four laser beams; however, the number of beam spots to be superimposed is not limited thereto.
[0044]
As shown in FIG. 2A, the beam spots of the respective laser beams are synthesized by matching the major axes of the respective ellipses and overlapping a part of the beam spots to form one beam spot 18. Yes. Hereinafter, a straight line obtained by connecting the centers O of the ellipses is referred to as a central axis.
[0045]
FIG. 2B shows the energy density distribution of the laser light in the central axis y direction of the combined beam spot shown in FIG. Note that the beam spot shown in FIG. 2A is 1 / e of the peak value of the energy density in FIG. ² This corresponds to a region satisfying the energy density of. The energy density is added at the portion where the beam spots before synthesis are overlapped. For example, when the energy densities E1 and E2 of the overlapping beams are added as shown in the figure, the energy density peak value E3 is approximately equal, and the energy density is flattened between the centers O of the ellipses.
[0046]
Note that when E1 and E2 are added, it is ideally equal to E3, but in reality, it is not necessarily equal. The allowable range of deviation between the value obtained by adding E1 and E2 and the value of E3 can be appropriately set by the designer.
[0047]
As can be seen from FIG. 2B, by superimposing a plurality of laser beams and complementing each other with a low energy density, the semiconductor film can be used rather than using a plurality of laser beams without overlapping. Crystallinity can be increased efficiently. For example, when a beam spot is used alone, it exceeds the energy density value necessary for obtaining a desired crystal only in the region indicated by the oblique lines in FIG. 1B, and the energy density is desired in other regions. Assume that the value was not met. In this case, each beam spot can obtain a desired crystal only in a hatched region whose width in the central axis direction is indicated by α. However, by superimposing the beam spots as shown in FIG. 2B, a desired crystal can be obtained in a region where the width in the central axis direction is represented by β (β> 4α), and the semiconductor is more efficiently produced. The film can be crystallized.
[0048]
In addition, the distribution of energy density in BB 'and CC' of FIG. 2 (A) calculated | required by calculation is shown in FIG. 3 shows 1 / e of the peak value of the beam spot before synthesis. ² The region that satisfies the energy density is used as a reference. The energy density at BB ′ and CC ′ when the length in the minor axis direction of the beam spot before synthesis is 37 μm, the length in the major axis direction is 410 μm, and the distance between the centers is 192 μm is The distributions are as shown in FIGS. 3 (A) and 3 (B), respectively. Although BB ′ is slightly weaker than CC ′, it can be regarded as almost the same size and is 1 / e of the peak value of the beam spot before synthesis. ² The shape of the combined beam spot in the region satisfying the energy density of can be expressed as a linear shape.
[0049]
Note that there are regions where the energy density does not reach the desired value even when the laser beams are superimposed. In the present invention, the low energy density region of the synthesized beam spot is shielded by the slit 17 so that the semiconductor film 11 is not irradiated. The positional relationship between the synthesized beam spot and the slit will be described with reference to FIG.
[0050]
The slit 17 used in the present invention has a variable slit width, and the width is controlled by a computer. In FIG. 2 (C), 18 indicates the shape of the beam spot 18 obtained by synthesis, and 17 indicates a slit, similar to that shown in FIG. 2 (A).
[0051]
FIG. 2D shows the energy density distribution in the y direction when the central axis AA ′ of the beam spot shown in FIG. Unlike the case shown in FIG. 3B, a region having a low energy density is cut by the slit 17.
[0052]
A semiconductor film irradiated with a region having a low energy density has poor crystallinity. Specifically, the crystal grains are smaller than the region where the energy density is satisfied, or the directions in which the crystal grains grow are different. FIG. 5A shows the shape of the synthesized beam spot on the substrate. A region indicated by 50 indicates a region satisfying a desired energy density, and 51 indicates a region not satisfied. The length of the beam spot in the direction of the central axis is W _TBW And the length in the central axis direction in the region satisfying the energy density is W _BW And the length in the direction perpendicular to the central axis in the region satisfying the energy density is W _C And
[0053]
In FIG. 5B, the length in the central axis direction is set to W by passing the beam spot shown in FIG. _BW The following shows the positional relationship between the scanning path of the beam spot 52 and the sub-island pattern. FIG. 5B shows a state in which the beam spot 52 in which a portion having a low energy density is shielded in the width in the direction perpendicular to the scanning direction is scanned. The beam spot 52 is scanned so as to cover the sub island 53, and the edge of the trajectory of the beam spot does not overlap the sub island 53. Note that the edge of the beam spot trajectory does not necessarily overlap with the sub-island, and it is important that the beam spot does not overlap with the island 54 obtained by patterning the sub-island as a minimum.
[0054]
In the present invention, a region having a low energy density does not exist, or even if it exists, its width is small compared to the case where no slit is used. It will be easier. Therefore, since a region having a low energy density is cut by providing the slit, restrictions on the laser light scanning path and the layout of the sub-islands and islands can be reduced.
[0055]
In addition, the width of the beam spot can be changed while keeping the energy density constant without stopping the output of the laser oscillation device, so that the edge of the laser beam can be prevented from overlapping the island or its channel formation region. . Further, unnecessary portions can be irradiated with laser light to prevent the substrate from being damaged.
[0056]
Although FIG. 5 shows the case where the central axis direction of the beam spot and the scanning direction are kept perpendicular, the central axis of the beam spot and the scanning direction are not necessarily perpendicular to each other. For example, the acute angle θ formed between the central axis of the beam spot and the scanning direction _A May be 45 ° ± 35 °, and more preferably 45 °. When the central axis of the beam spot is perpendicular to the scanning direction, the substrate processing efficiency is most enhanced. On the other hand, by scanning so that the central axis of the combined beam spot and the scanning direction are 45 ° ± 35 °, preferably closer to 45 °, the scanning direction and the center of the beam spot Compared to scanning with the axis perpendicular, the number of crystal grains present in the active layer can be intentionally increased, and the variation in characteristics due to crystal orientation and crystal grains can be reduced. Can do. Further, when the scanning speed is the same, the irradiation time of the laser beam per substrate can be increased as compared with the case where scanning is performed so that the scanning direction and the central axis of the beam spot are perpendicular.
[0057]
Next, the relationship between the shape of the sub islands and islands and the scanning direction of the laser light will be described. FIG. 6A shows a top view of the sub-island 12 shown in FIG. A portion 16 that becomes an island is indicated by a broken line inside the sub-island (before LC) 12. Reference numeral 14 denotes a beam spot, and FIG. 6A shows a state before laser irradiation.
[0058]
The beam spot 14 approaches the sub-island (before LC) 12 as time elapses from the state of FIG. The position of the beam spot is moved by scanning the substrate side.
[0059]
When the beam spot reaches the sub-island (before LC) 12, the beam spot 14 and the sub-island (before LC) 12 touch each other at one point. Therefore, the sub-island is crystallized from the vicinity 20 of the contact point, and as shown in FIG. 6C, the beam spot 14 moves and crystallization proceeds in the direction indicated by the arrow. Since this crystallization proceeds based on the seed crystal formed first in the contact vicinity 17, the orientation rate of the (110) plane increases.
[0060]
When the island is used as the active layer of the TFT, it is desirable to keep the scanning direction of the laser light parallel to the direction in which the carriers in the channel formation region move.
[0061]
Note that the trajectory of the beam spot 14 does not have to completely cover the sub-island 12 but only needs to completely cover the island 16. However, by scanning the laser beam so as to completely cover the sub-island, it is possible to prevent the crystal from growing using a region not irradiated with the laser beam as a seed crystal and to further increase the orientation rate of the (110) plane. it can.
[0062]
FIG. 6D illustrates a relationship between a cross-sectional view taken along line AA ′ in FIG. 6C and a beam spot. The laser beam applied to the substrate through the slit 17 is shielded by the slit and has a width W in the major axis direction. _TDW Is W _BW It is narrowed to. The beam spot of the laser beam on the sub island is W _BW Ideally, it should be the same size as. However, since the slit 17 and the sub island 12 are actually separated from each other, the laser beam has a width W in the major axis direction of the beam spot on the sub island 12. _BW 'Become W _BW '<W _BW Meet. Therefore, it is desirable to set the width of the slit in consideration of diffraction.
[0063]
If you try to irradiate the whole sub island with laser light, W _BW > W _S If the diffraction is taken into account, W _BW '＞ W _S Should be satisfied. Also, if you want to irradiate only the island with the minimum necessary laser light, it is necessary to take diffraction into account. _BW > W _I If the diffraction is taken into account, W _BW '＞ W _I Should be satisfied. W _S Is the longest length of the sub island 12 in the direction perpendicular to the moving direction of the beam spot, and W _I Is the longest length of the island 16 in the direction perpendicular to the moving direction of the beam spot.
[0064]
FIG. 7 shows an example of the relationship between the layout of islands used as the active layer of the TFT and the moving direction of the beam spot. In FIG. 7A, a portion 31 indicated by a broken line inside the sub-island 30 corresponds to a portion that becomes an island. When the island 31 is used as an active layer of a TFT having one channel formation region, impurity regions 33 and 34 serving as a source region or a drain region are provided so as to sandwich the channel formation region 32. Reference numeral 35 denotes the shape of the beam spot. When the sub-island 30 is crystallized, the scanning direction of the laser light is made parallel to the direction in which the carriers in the channel formation region 32 move, as shown by the arrows. Then, the crystal growth proceeds from the seed crystal formed in the contact vicinity 36 in contact with the beam spot 35 at one point, whereby the orientation rate of the (110) plane of the sub island can be increased.
[0065]
FIG. 7B shows an active layer provided with three channel formation regions, and impurity regions 41 and 42 are provided so as to sandwich the channel formation region 40. Impurity regions 42 and 44 are provided so as to sandwich the channel formation region 43, and impurity regions 44 and 46 are provided so as to sandwich the channel formation region 45. The scanning direction of the beam spot is set to be parallel to the direction in which the carriers in the channel forming regions 40, 43, 45 move as indicated by arrows.
[0066]
Next, with reference to FIG. 8A, a laser beam scanning direction in the substrate 500 over which a sub-island is formed in order to manufacture an active matrix semiconductor device will be described. In FIG. 8A, a broken line 501 corresponds to a pixel portion, a broken line 502 corresponds to a signal line driver circuit, and a broken line 503 corresponds to a portion where a scanning line driver circuit is formed.
[0067]
FIG. 8A shows an example in which the laser beam is scanned only once with respect to the substrate 500, the substrate is moved in the direction of the white arrow, and the solid arrow indicates the relative position of the laser beam. The scanning direction is shown. The beam spot may be moved by moving the substrate 500 or using an optical system. FIG. 8B is an enlarged view of a beam spot 507 in a portion 501 where a pixel portion is formed. A sub-island 506 is laid out in the region irradiated with the laser light.
[0068]
In FIG. 8, it is desirable to irradiate the laser beam so that the edge portion of the beam spot does not overlap with the island 508 obtained by patterning the sub-island, more preferably, the sub-island 506. In the present invention, the laser beam scanning portion is determined according to the pattern information of the sub-island mask.
[0069]
Note that the width of the beam spot can be appropriately changed depending on the size of the sub-island or the island. For example, a TFT of a driving circuit in which a relatively large amount of current is desired to flow has a large channel width, and thus the island size tends to be larger than that of the pixel portion. FIG. 9 shows a case where laser light is scanned on sub-islands of two sizes while changing the slit width. 9A shows a case where the sub-island length in the direction perpendicular to the scanning direction is short, and FIG. 9B shows a case where the sub-island length in the direction perpendicular to the scanning direction is long. The relationship between the part and the sub-island is shown.
[0070]
The width of the beam spot in FIG. _BW1 , The width of the beam spot in FIG. _BW2 Then, W _BW1 <W _BW2 It becomes. Of course, the width of the beam spot is not limited to this, and if there is a margin in the interval between the sub-islands in the direction perpendicular to the scanning direction, the width can be freely set.
[0071]
In the present invention, as shown in FIG. 9, the laser beam is scanned so that the sub-island portion can be crystallized at least, rather than irradiating the entire surface of the substrate with the laser beam. Instead of irradiating the entire surface of the substrate, the laser light is irradiated to the minimum necessary part so that the sub-island can be crystallized, so that the processing time for one substrate can be suppressed, and the efficiency of the substrate processing can be reduced. Can be increased
[0072]
Next, the structure of the laser irradiation apparatus used in the present invention will be described with reference to FIG. Reference numeral 101 denotes a laser oscillation device. Although four laser oscillation devices are used in FIG. 10, the number of laser oscillation devices included in the laser irradiation device is not limited to this number.
[0073]
Note that the laser oscillation device 101 may use a chiller 102 to keep the temperature constant. Although the chiller 102 is not necessarily provided, by keeping the temperature of the laser oscillation device 101 constant, it is possible to suppress the energy of the output laser light from varying depending on the temperature.
[0074]
Reference numeral 104 denotes an optical system which can focus the laser beam by changing the optical path output from the laser oscillation device 101 or processing the shape of the beam spot. Furthermore, in the laser irradiation apparatus of FIG. 10, the optical system 104 can synthesize laser beam spots output from the plurality of laser oscillation apparatuses 101 by partially overlapping each other.
[0075]
Note that the AO modulator 103 that changes the traveling direction of the laser light in an extremely short time may be provided in the optical path between the substrate 106 that is an object to be processed and the laser oscillation device 101. Further, an attenuator (light quantity adjustment filter) may be provided instead of the AO modulator to adjust the energy density of the laser light.
[0076]
Further, a means (energy density measuring means) 115 for measuring the energy density of the laser beam output from the laser oscillation device 101 is provided in the optical path between the substrate 106 that is the object to be processed and the laser oscillation device 101, and measurement is performed. The computer 110 may monitor the change in energy density over time. In this case, the output from the laser oscillation device 110 may be increased so as to compensate for the attenuation of the energy density of the laser beam.
[0077]
The combined beam spot is irradiated to the substrate 106 as the object to be processed through the slit 105. The slit 105 is preferably formed of a material that can block the laser beam and that is not deformed or damaged by the laser beam. The slit 105 has a variable slit width, and the width of the beam spot can be changed according to the width of the slit.
[0078]
Note that the shape of the beam spot on the substrate 106 of the laser beam oscillated from the laser oscillation device 101 when not passing through the slit 105 differs depending on the type of laser and can also be formed by an optical system.
[0079]
The substrate 106 is placed on the stage 107. In FIG. 10, position control means 108 and 109 correspond to means for controlling the position of the beam spot on the object to be processed, and the position of the stage 107 is controlled by the position control means 108 and 109.
[0080]
In FIG. 10, the position control means 108 controls the position of the stage 107 in the X direction, and the position control means 109 controls the position of the stage 107 in the Y direction.
[0081]
Further, the laser irradiation apparatus of FIG. 10 has a computer 110 having both a central processing unit and storage means such as a memory. The computer 110 controls the oscillation of the laser oscillation device 101 and controls the position control means 108 and 109 so that the laser beam spot covers an area determined according to the mask pattern information, so that the substrate is placed at a predetermined position. Can be moved.
[0082]
Further, in the present invention, the width of the slit 105 can be controlled by the computer 110, and the width of the beam spot can be changed in accordance with the mask pattern information.
[0083]
Further, the laser irradiation apparatus may include a means for adjusting the temperature of the object to be processed. Further, since the laser light is light having high directivity and energy density, a damper may be provided to prevent the reflected light from being irradiated to an inappropriate place. The damper desirably has a property of absorbing reflected light, and cooling water may be circulated in the damper to prevent the temperature of the partition wall from rising due to absorption of the reflected light. Further, a means for heating the substrate (substrate heating means) may be provided on the stage 107.
[0084]
When the marker is formed by a laser, a marker laser oscillation device may be provided. In this case, the computer 110 may control the oscillation of the marker laser oscillator. Further, in the case where a marker laser oscillation device is provided, an optical system for condensing the laser light output from the marker laser oscillation device is separately provided. The laser used for forming the marker is typically a YAG laser or CO. ₂ A laser or the like can be mentioned, but it is of course possible to form using other lasers.
[0085]
Further, one CCD camera 113 may be provided for positioning using the marker, and in some cases, several CCD cameras 113 may be provided.
[0086]
Note that the sub-island pattern may be recognized by the CCD camera 113 without providing the marker, and the alignment may be performed. In this case, the sub-island pattern information by the mask input to the computer 110 and the actual sub-island pattern information collected by the CCD camera 113 can be collated to grasp the position information of the substrate. In this case, it is not necessary to provide a marker separately.
[0087]
Note that although FIG. 10 shows the configuration of a laser irradiation apparatus provided with a plurality of laser oscillation apparatuses, the number of laser oscillation apparatuses may be one. FIG. 11 shows a configuration of a laser irradiation apparatus having one laser oscillation apparatus. In FIG. 11, 201 is a laser oscillation device, and 202 is a chiller. Reference numeral 215 denotes an energy density measuring device, 203 denotes an AO modulator, 204 denotes an optical system, 205 denotes a slit, and 213 denotes a CCD camera. The substrate 206 is placed on the stage 207, and the position of the stage 207 is controlled by the X direction position control means 208 and the Y direction position control means 209. As in the case shown in FIG. 10, the computer 210 controls the operation of each means included in the laser irradiation apparatus. The difference from FIG. 10 is that there is one laser oscillation apparatus. Further, unlike the case of FIG. 10, the optical system 204 only needs to have a function of condensing one laser beam.
[0088]
Next, a flow of a method for manufacturing a semiconductor device of the present invention will be described.
[0089]
FIG. 12 is a flowchart showing the production flow. First, a semiconductor device is designed using CAD. Specifically, an island mask is first designed, and then a sub-island mask is designed that includes one or more islands. At this time, it is desirable that all the islands included in one sub-island align the direction in which the carriers in the channel formation region move, but the directions may not be intentionally aligned according to the application.
[0090]
At this time, the mask of the sub island may be designed so that the marker is formed together with the sub island.
[0091]
Then, information (pattern information) on the shape of the designed sub-island mask is input to a computer included in the laser irradiation apparatus. In the computer, based on the input sub-island pattern information, the width W of each sub-island in the direction perpendicular to the scanning direction. _S Is calculated. And the width W of each sub island _S Based on the above, the slit width W in the direction perpendicular to the scanning direction _BW Set.
[0092]
And slit width W _BW Based on the above, the scanning path of the laser beam is determined based on the marker position.
[0093]
On the other hand, a semiconductor film is formed on the substrate, and the semiconductor film is patterned using a sub-island mask to form a sub-island. Then, the substrate on which the sub island is formed is placed on the stage of the laser irradiation apparatus.
[0094]
Then, using the marker as a reference, laser light is irradiated along a predetermined scanning path to crystallize the sub-island.
[0095]
Then, after irradiating the laser beam, the sub-island whose crystallinity is enhanced by the laser beam irradiation is patterned to form an island. Thereafter, a process of manufacturing a TFT from the island is performed. A specific manufacturing process of the TFT differs depending on the shape of the TFT, but typically, a gate insulating film is formed and an impurity region is formed in the island. Then, an interlayer insulating film is formed so as to cover the gate insulating film and the gate electrode, a contact hole is formed in the interlayer insulating film, and a part of the impurity region is exposed. Then, a wiring is formed on the interlayer insulating film so as to be in contact with the impurity region through the contact hole.
[0096]
Next, an example in which a substrate and a mask are aligned by a CCD camera without forming a marker will be described.
[0097]
FIG. 13 is a flowchart showing the production flow. First, as in the case of FIG. 12, a semiconductor device is designed using CAD. Specifically, an island mask is first designed, and then a sub-island mask is designed that includes one or more islands.
[0098]
Then, information (pattern information) on the shape of the designed sub-island mask is input to a computer included in the laser irradiation apparatus. In the computer, based on the input sub-island pattern information, the width W of each sub-island in the direction perpendicular to the scanning direction. _S Is calculated. And the width W of each sub island _S Based on the above, the slit width W in the direction perpendicular to the scanning direction _BW Set.
[0099]
On the other hand, a semiconductor film is formed on the substrate, and the semiconductor film is patterned using a sub-island mask to form a sub-island. Then, the substrate on which the sub island is formed is placed on the stage of the laser irradiation apparatus.
[0100]
Then, the sub-island pattern information on the substrate placed on the stage is detected by the CCD camera and input to the computer as information. The computer compares the sub-island pattern information designed by CAD with the sub-island pattern information actually formed on the substrate obtained by the CCD camera, and aligns the substrate and the mask.
[0101]
The width W of the slit _BW The scanning path of the laser light is determined based on the sub-island position information obtained by the CCD camera.
[0102]
Then, laser light is irradiated along a predetermined scanning path, and crystallization is performed aiming at the sub-island.
[0103]
Next, after irradiating the laser beam, the sub-island whose crystallinity is enhanced by the laser beam irradiation is patterned to form an island. Thereafter, a process of manufacturing a TFT from the island is performed. A specific manufacturing process of the TFT differs depending on the shape of the TFT, but typically, a gate insulating film is formed and an impurity region is formed in the island. Then, an interlayer insulating film is formed so as to cover the gate insulating film and the gate electrode, a contact hole is formed in the interlayer insulating film, and a part of the impurity region is exposed. Then, a wiring is formed on the interlayer insulating film so as to be in contact with the impurity region through the contact hole.
[0104]
Next, FIG. 14 is a flowchart showing the flow of the production method when the laser beam is irradiated twice.
[0105]
FIG. 14 is a flowchart showing the production flow. First, a semiconductor device is designed using CAD. Specifically, an island mask is first designed, and then a sub-island mask is designed that includes one or more islands. At this time, the mask of the sub island may be designed so that the marker is formed together with the sub island.
[0106]
Then, information (pattern information) on the shape of the designed sub-island mask is input to a computer included in the laser irradiation apparatus. In the computer, based on the input sub-island pattern information, the width W of each sub-island in the direction perpendicular to each of the two scanning directions. _S Are calculated in two ways. And the width W of each sub island _S The width W of the slit in the direction perpendicular to each of the two scanning directions _BW Are calculated respectively.
[0107]
Then, in each of the two scanning directions, the slit width W determined respectively. _BW Based on the above, the scanning path of the laser beam is determined based on the marker position.
[0108]
On the other hand, a semiconductor film is formed on the substrate, and the semiconductor film is patterned using a sub-island mask to form a sub-island. Then, the substrate on which the sub island is formed is placed on the stage of the laser irradiation apparatus.
[0109]
Then, using the marker as a reference, the first laser beam is irradiated according to the first scanning path out of the two defined scanning paths, and crystallization is performed aiming at the sub-island.
[0110]
Note that the angle between the scanning direction of the first laser beam and the scanning direction of the second laser beam may be stored in advance in a memory or the like, or may be manually input each time. Then, using the marker as a reference, the first laser beam scanning portion is irradiated with the laser beam to crystallize the sub-island.
[0111]
Then, the scanning direction is changed, the second laser beam is irradiated along the second scanning path, and crystallization is aimed at the sub island.
[0112]
Although FIG. 14 shows an example in which laser light is irradiated twice on the same sub-island, it is also possible to change the scanning direction by specifying a place by using an AO modulator or the like. For example, when the scanning direction in the signal line driver circuit is different from the scanning direction in the pixel portion and the scanning line driver circuit, and the AO modulator is used to irradiate the laser light in the portion that becomes the signal line driver circuit, the AO modulator is used. In the case where the laser beam is not irradiated on the pixel portion and the portion serving as the scanning line driving circuit, and the laser beam is irradiated on the portion serving as the pixel portion and the scanning line driving circuit, a signal line driving circuit is used using an AO modulator. It is possible to prevent the laser beam from being irradiated on the portion to be. In this case, the AO modulator is synchronized with the position control means in the computer.
[0113]
Note that, after irradiation with laser light, a sub-island whose crystallinity is enhanced by laser light irradiation is patterned to form an island. Thereafter, a process of manufacturing a TFT from the island is performed. A specific manufacturing process of the TFT differs depending on the shape of the TFT, but typically, a gate insulating film is formed and an impurity region is formed in the island. Then, an interlayer insulating film is formed so as to cover the gate insulating film and the gate electrode, a contact hole is formed in the interlayer insulating film, and a part of the impurity region is exposed. Then, a wiring is formed on the interlayer insulating film so as to be in contact with the impurity region through the contact hole.
[0114]
For comparison, FIG. 15 shows a flow of a conventional semiconductor device production method. As shown in FIG. 15, a semiconductor device mask is designed by CAD. On the other hand, an amorphous semiconductor film is formed on a substrate, and the substrate on which the amorphous semiconductor film is formed is placed in a laser irradiation apparatus. Then, scanning is performed so that the entire amorphous semiconductor film is irradiated with laser light, and the entire amorphous semiconductor film is crystallized. Then, a marker is formed on the polycrystalline semiconductor film obtained by crystallization, and an island is formed by patterning the polycrystalline semiconductor film using the marker as a reference. Then, a TFT is manufactured using the island.
[0115]
Thus, in the present invention, unlike the conventional case as shown in FIG. 15, the marker is formed before the amorphous semiconductor film is crystallized by using laser light. Then, laser light is scanned in accordance with information on the mask for patterning the semiconductor film.
[0116]
With the above structure, it is possible to reduce the time for irradiating the laser light to the portion removed by patterning after crystallization of the semiconductor film, so that the time required for the laser light irradiation can be shortened and the substrate is processed. Speed can be improved.
[0117]
Note that a step of crystallizing the semiconductor film using a catalyst may be included. In the case of using a catalyst element, it is desirable to use the techniques disclosed in Japanese Patent Application Laid-Open Nos. 7-130652 and 8-78329.
[0118]
In the case where the step of crystallizing the semiconductor film using a catalyst is included, the step of crystallizing the amorphous semiconductor film using Ni after the formation of the amorphous semiconductor film (NiSPC) is included. For example, when using the technique disclosed in Japanese Patent Application Laid-Open No. 7-130652, a nickel-containing layer is formed by applying a nickel acetate salt solution containing 10 ppm of nickel on a weight basis to an amorphous semiconductor film. After the 1-hour dehydrogenation step, crystallization is performed by heat treatment at 500 to 650 ° C. for 4 to 12 hours, for example, 550 ° C. for 8 hours. In addition to nickel (Ni), usable catalyst elements include germanium (Ge), iron (Fe), palladium (Pd), tin (Sn), lead (Pb), cobalt (Co), platinum ( Elements such as Pt), copper (Cu), and gold (Au) may be used.
[0119]
Then, the crystallinity of the semiconductor film crystallized by NiSPC is further increased by laser light irradiation. The polycrystalline semiconductor film obtained by laser light irradiation contains a catalytic element, and after the laser light irradiation, a step (gettering) of removing the catalytic element from the crystalline semiconductor film is performed. For the gettering, a technique described in JP-A-10-135468 or JP-A-10-135469 can be used.
[0120]
Specifically, phosphorus is added to part of the polycrystalline semiconductor film obtained after laser irradiation, and heat treatment is performed in a nitrogen atmosphere at 550 to 800 ° C. for 5 to 24 hours, for example, 600 ° C. for 12 hours. Then, the region of the polycrystalline semiconductor film to which phosphorus is added functions as a gettering site, and phosphorus existing in the polycrystalline semiconductor film can be segregated to the region to which nickel is added. Thereafter, the region of the polycrystalline semiconductor film to which phosphorus is added is removed by patterning, so that the concentration of the catalytic element is 1 × 10 6. ¹⁷ atoms / cm ³ Preferably 1 × 10 ¹⁶ atoms / cm ³ An island reduced to a certain extent can be obtained.
[0121]
Next, the positional relationship between the slit and the beam spot when the central axis of the beam spot is maintained at 45 ° with respect to the scanning direction will be described with reference to FIG. Reference numeral 130 denotes a combined beam spot, and reference numeral 105 denotes a slit. The slit 105 does not overlap the beam spot 130. The arrow indicates the scanning direction, and the angle θ with respect to the central axis of the beam spot 130 is maintained at 45 °.
[0122]
FIG. 16B shows a state of the beam spot 131 that is partially blocked by the slit 105 and narrowed. In the present invention, the slit 105 controls the width Q of the beam spot in the direction perpendicular to the scanning direction so that the laser beam is irradiated uniformly.
[0123]
Thus, in the present invention, the laser beam is scanned so that at least the indispensable part can be crystallized at least, instead of scanning and irradiating the entire semiconductor film with the laser beam. With the above structure, it is possible to omit the time for irradiating a portion of the semiconductor film that is removed by patterning after crystallization, and to significantly reduce the processing time per substrate.
[0124]
【Example】
Examples of the present invention will be described below.
[0125]
Example 1
In this embodiment, the optical system of the laser irradiation apparatus used in the present invention and the positional relationship between each optical system and the slit will be described.
[0126]
FIG. 17 illustrates the optical system of the present embodiment. The optical system shown in FIG. 17A has two cylindrical lenses 401 and 402. Then, the laser beam incident from the direction of the arrow is shaped into a beam spot by two cylindrical lenses 401 and 402, and is irradiated to the object 403 through the slit 404. Note that the cylindrical lens 402 closer to the workpiece 403 has a shorter focal length than the cylindrical lens 401. In order to prevent return light and perform uniform irradiation, it is desirable to keep the incident angle of the laser light on the substrate larger than 0 °, preferably 5 to 30 °.
[0127]
The optical system shown in FIG. 17B includes a mirror 405 and a plano-convex spherical lens 406. The laser light incident from the direction of the arrow is reflected by the mirror 405, the shape of the beam spot is shaped by the plano-convex spherical lens 406, and is irradiated to the object 407 through the slit 408. The radius of curvature of the plano-convex spherical lens can be set as appropriate by the designer. In order to prevent return light and perform uniform irradiation, it is desirable to keep the incident angle of the laser light on the substrate larger than 0 °, preferably 5 to 30 °.
[0128]
The optical system illustrated in FIG. 17C includes mirrors 410 and 411 and lenses 412, 413, and 414. Then, the laser beam incident from the direction of the arrow is reflected by the mirrors 410 and 411, the shape of the beam spot is formed by the lenses 412, 413 and 414, and is irradiated to the object 415 through the slit 416. In order to prevent return light and perform uniform irradiation, it is desirable to keep the incident angle of the laser light on the substrate larger than 0 °, preferably 5 to 30 °.
[0129]
FIG. 17D shows an optical system in the case where four beam spots shown in the second embodiment are combined into one beam spot. The optical system illustrated in FIG. 17D includes six cylindrical lenses 417 to 422. The four laser beams incident from the direction of the arrows are incident on the four cylindrical lenses 419 to 422, respectively. The two laser beams shaped by the cylindrical lenses 419 and 421 are shaped again by the cylindrical lens 417 and the shape of the beam spot is shaped, and the object 423 is irradiated through the slit 424. On the other hand, the shape of the beam spot of the two laser beams formed by the cylindrical lenses 420 and 422 is formed again by the cylindrical lens 418, and the object 423 is irradiated through the slit 424.
[0130]
The beam spots of the respective laser beams on the workpiece 423 are combined by overlapping each other to form one beam spot.
[0131]
The focal length and incident angle of each lens can be appropriately set by the designer, but the focal lengths of the cylindrical lenses 417 and 418 closest to the object 423 are smaller than the focal lengths of the cylindrical lenses 419 to 422. To do. For example, the focal lengths of the cylindrical lenses 417 and 418 closest to the object to be processed 423 are set to 20 mm, and the focal lengths of the cylindrical lenses 419 to 422 are set to 150 mm. In this embodiment, the incident angle of laser light from the cylindrical lenses 417 and 418 to the workpiece 400 is 25 °, and the incident angle of laser light from the cylindrical lenses 419 to 422 to the cylindrical lenses 417 and 418 is 10 °. Install each lens as you want. In order to prevent return light and perform uniform irradiation, it is desirable to keep the incident angle of the laser light on the substrate larger than 0 °, preferably 5 to 30 °.
[0132]
FIG. 17D shows an example of synthesizing four beam spots. In this case, four cylindrical lenses respectively corresponding to the four laser oscillation devices, two cylindrical lenses corresponding to the four cylindrical lenses, and have. The number of beam spots to be combined is not limited to this, and the number of beam spots to be combined may be 2 or more and 8 or less. When combining n (n = 2, 4, 6, 8) beam spots, n cylindrical lenses corresponding to the n laser oscillation devices, and n / 2 cylindrical lenses corresponding to the n cylindrical lenses, have. When combining n (n = 3, 5, 7) beam spots, n cylindrical lenses respectively corresponding to the n laser oscillation devices, and (n + 1) / 2 cylindrical lenses corresponding to the n cylindrical lenses, have.
[0133]
Then, when superposing five or more beam spots, it is desirable to irradiate the fifth and subsequent laser beams from the opposite side of the substrate in consideration of the location where the optical system is arranged and interference, etc. It must also be provided on the opposite side. Further, the substrate needs to have transparency.
[0134]
In order to prevent the return light from returning along the original optical path, it is desirable to keep the incident angle with respect to the substrate larger than 0 and smaller than 90 °.
[0135]
Also, in order to realize uniform laser light irradiation, a plane or long side that is a plane perpendicular to the irradiation surface and includes a short side when the shape of each beam before synthesis is regarded as a rectangle is obtained. If any one of the surfaces to be included is defined as an incident surface, the incident angle θ of the laser light is set such that the length of the short side or the long side included in the incident surface is W, and is set on the irradiation surface, and It is desirable that θ ≧ arctan (W / 2d) is satisfied when the thickness of the substrate having translucency with respect to the laser beam is d. This argument needs to hold for each laser beam before synthesis. When the locus of the laser beam is not on the incident surface, the incident angle of the projection of the locus onto the incident surface is defined as θ. If the laser light is incident at this incident angle θ, the reflected light from the surface of the substrate and the reflected light from the back surface of the substrate do not interfere with each other, and uniform laser light irradiation can be performed. In the above discussion, the refractive index of the substrate was considered as 1. Actually, in many cases, the refractive index of the substrate is around 1.5, and if this value is taken into consideration, a calculated value larger than the angle calculated in the above discussion can be obtained. However, since the energy at both ends in the longitudinal direction of the beam spot is attenuated, the influence of interference in this portion is small, and the effect of interference attenuation can be sufficiently obtained with the above calculated value.
[0136]
Note that the optical system included in the laser irradiation apparatus used in the present invention is not limited to the structure shown in this embodiment.
[0137]
(Example 2)
In this embodiment, an example in which the width of a laser beam spot is changed by an AO modulator in the middle of laser light irradiation when a plurality of laser oscillation devices are used will be described.
[0138]
In the present embodiment, the scanning path of the laser beam is grasped by the computer based on the inputted mask information. Furthermore, in this embodiment, an AO modulator is used to change the direction of the laser beam output from any one of the plurality of laser oscillation devices so that the object to be processed is not irradiated with the laser beam. Then, change the beam spot width according to the mask shape. In this case, even if the beam spot width is changed by the AO modulator, it is necessary to shield a region where the energy density of the beam spot is low in the direction perpendicular to the scanning direction. It is necessary to synchronize the shielding of the laser beam by.
[0139]
FIG. 18A shows an example of the relationship between the shape of a mask for patterning a semiconductor film and the width of a beam spot when laser light is irradiated once. Reference numeral 560 denotes the shape of a mask for patterning a semiconductor film. After crystallization by laser irradiation, the semiconductor film is patterned according to the mask.
[0140]
Reference numerals 561 and 562 denote portions irradiated with laser light. Reference numerals 561 and 562 denote scanned portions of beam spots obtained by superimposing and synthesizing laser beams output from four laser oscillation devices. 562 is controlled by a slit so that the width of the beam spot is narrower than that of 561.
[0141]
As in this embodiment, by using an AO modulator, the width of the beam spot can be freely changed without stopping the output of all laser oscillation devices, and the output can be reduced by stopping the output of the laser oscillation device. It can avoid becoming unstable.
[0142]
With the above configuration, the width of the locus of the laser beam can be changed, so that the edge of the locus of the laser beam can be prevented from overlapping with the semiconductor obtained by patterning. Moreover, the damage given to a board | substrate can further be reduced by irradiating a laser beam to an unnecessary part.
[0143]
Next, an example will be described in which laser light is blocked by an AO modulator in the course of laser light irradiation, and laser light is irradiated only on a predetermined portion. In this embodiment, the laser beam is changed by changing the direction of the laser beam by using an AO modulator. As a result, the present invention is not limited to this, and any laser beam can be shielded. Such means may be used.
[0144]
In the present invention, the computer scans the portion of the laser beam that is scanned based on the input mask information. Furthermore, in this embodiment, the laser light is changed by using the AO modulator so that only the portion to be scanned is irradiated with the laser light, thereby blocking the laser light as a result. At this time, the AO modulator is preferably formed of a material that can block the laser beam and that is not deformed or damaged by the laser beam.
[0145]
FIG. 18B shows an example of the relationship between the shape of a mask for patterning a semiconductor film and a portion irradiated with laser light. Reference numeral 570 denotes the shape of a mask for patterning the semiconductor film. After crystallization by laser light irradiation, the semiconductor film is patterned according to the mask.
[0146]
Reference numeral 571 denotes a portion irradiated with laser light. The portion surrounded by the broken line shows the portion where the laser beam is blocked as a result of changing the direction of the laser beam by the AO modulator. In this embodiment, the portion that does not need to be crystallized is shown. Is not irradiated with laser light, or even if it is irradiated, its energy density can be lowered. Therefore, the damage given to the substrate can be further reduced by irradiating unnecessary portions with laser light.
[0147]
Next, in a manufacturing process of a semiconductor display device including a pixel portion, a signal line driver circuit, and a scanning line driver circuit, an AO modulator is used to select the pixel portion, the signal line driver circuit, and the scanning line driver circuit once. A case of irradiating laser light will be described.
[0148]
First, as shown in FIG. 19A, the signal line driver circuit 302 and the pixel portion 301 are scanned in the direction of the arrow and irradiated with laser light. At this time, the laser light is not irradiated on the entire surface of the substrate, but the direction of the laser light is changed by using an AO modulator so that the scanning line driving circuit 303 is not irradiated with the laser light. Block.
[0149]
Next, as shown in FIG. 19B, the scanning line driver circuit 303 is scanned in the direction of the arrow and irradiated with laser light. At this time, the signal line driver circuit 302 and the pixel portion 301 are not irradiated with laser light.
[0150]
Next, another example in which an AO modulator is used to selectively irradiate a pixel portion, a signal line driver circuit, and a scanning line driver circuit once each will be described.
[0151]
First, as shown in FIG. 19C, the scanning line driver circuit 303 and the pixel portion 301 are scanned in the direction of the arrow and irradiated with laser light. At this time, the laser light is not irradiated on the entire surface of the substrate, but the direction of the laser light is changed by using an AO modulator so that the signal line driving circuit 302 is not irradiated with the laser light. Block.
[0152]
Next, as shown in FIG. 19D, the signal line driver circuit 302 is irradiated with laser light by scanning in the direction of the arrow. At this time, the scanning line driving circuit 303 and the pixel portion 301 are not irradiated with laser light.
[0153]
As described above, since the laser beam can be selectively irradiated using the AO modulator, the scanning direction of the laser beam is changed for each circuit in accordance with the layout of the channel formation region of the active layer included in each circuit. be able to. Since the same circuit can be prevented from being irradiated with the laser beam twice, the path of the laser beam to prevent the edge of the second laser beam from overlapping the active layer that has been laid out is avoided. There are no restrictions on the setting and layout of the active layer.
[0154]
Next, an example in which a plurality of panels are manufactured from a large substrate when an AO modulator is used to selectively irradiate a pixel portion, a signal line driver circuit, and a scan line driver circuit once each time will be described. .
[0155]
First, as shown in FIG. 20, the signal line driver circuit 382 and the pixel portion 381 of each panel are scanned in the direction of the arrow and irradiated with laser light. At this time, the laser beam is not irradiated on the entire surface of the substrate, but the direction of the laser beam is changed by using an AO modulator so that the scanning line driving circuit 383 is not irradiated with the laser beam. Block.
[0156]
Next, the scanning drive circuit 383 of each panel is scanned in the direction of the arrow and irradiated with laser light. At this time, the signal line driver circuit 382 and the pixel portion 381 are not irradiated with laser light. Reference numeral 385 denotes a scribe line for the substrate 386.
[0157]
This embodiment can be implemented in combination with the first embodiment.
[0158]
Example 3
In the present embodiment, the relationship between the distance between the centers of the beam spots and the energy density when the beam spots are superimposed will be described.
[0159]
In FIG. 21, the energy density distribution in the central axis direction of each beam spot is indicated by a solid line, and the energy density distribution of the synthesized beam spot is indicated by a broken line. The value of the energy density in the direction of the central axis of the beam spot generally follows a Gaussian distribution.
[0160]
At the beam spot before synthesis, 1 / e of the peak value ² Let X be the distance between each peak when the distance in the central axis direction satisfying the above energy density is 1. Let Y be the percent increment of the peak value after the synthesis and the average value of the valley values. The relationship between X and Y obtained by simulation is shown in FIG. In FIG. 38, Y is expressed as a percentage.
[0161]
In FIG. 38, the energy difference Y is expressed by the approximate expression of Expression 1 below.
[0162]
[Formula 1]
Y = 60-293X + 340X ² (X is the larger of the two solutions)
[0163]
According to Equation 1, for example, when it is desired to make the energy difference about 5%, it can be understood that X≈0.584. Ideally, Y = 0. However, since the length of the beam spot is shortened, it is preferable to determine X in balance with the throughput.
[0164]
Next, the allowable range of Y will be described. FIG. 39 shows YVO with respect to the beam width in the central axis direction when the beam spot has an elliptical shape. ₄ The distribution of laser output (W) is shown. The region indicated by hatching is the range of output energy necessary for obtaining good crystallinity, and it is understood that the output energy of the synthesized laser beam should be within the range of 3.5 to 6 W.
[0165]
When the maximum value and the minimum value of the output energy of the beam spot after synthesis enter the limit of the output energy range necessary for obtaining good crystallinity, the energy difference Y for obtaining good crystallinity is maximized. Therefore, in the case of FIG. 39, the energy difference Y is ± 26.3%, and it can be seen that good crystallinity can be obtained if the energy difference Y is within the above range.
[0166]
Note that the range of output energy required to obtain good crystallinity varies depending on how far the crystallinity is judged to be good, and the distribution of output energy also varies depending on the shape of the beam spot. The allowable range of Y is not necessarily limited to the above value. The designer needs to appropriately determine the range of output energy necessary for obtaining good crystallinity, and set the allowable range of the energy difference Y from the distribution of the output energy of the laser used.
[0167]
This embodiment can be implemented in combination with Embodiment 1 or 2.
[0168]
Example 4
In this embodiment, how to superimpose beam spots will be described. FIG. 22 shows the 1 / e of the beam spot before synthesis. ² X A beam spot in a region satisfying the energy density of the peak value is shown.
[0169]
FIG. 22A shows a case where the centers of the beam spots do not overlap other beam spots when the four beam spots are overlapped.
[0170]
FIG. 22B shows a case where the centers of the beam spots overlap the edges of other beam spots when the four beam spots are overlapped.
[0171]
FIG. 22C shows a case where the centers of the beam spots overlap the edges of two adjacent beam spots when the four beam spots are overlapped.
[0172]
The present invention is not limited to this configuration. The degree of beam spot overlap can be set as appropriate by the designer. This embodiment can be implemented in combination with the first to third embodiments.
[0173]
(Example 5)
In this embodiment, a method for manufacturing an active matrix substrate using the laser crystallization method of the present invention will be described with reference to FIGS. In this specification, a substrate in which a pixel portion having a CMOS circuit, a driver circuit, a pixel TFT, and a storage capacitor is formed over the same substrate is referred to as an active matrix substrate for convenience.
[0174]
First, in this embodiment, a substrate 600 made of glass such as barium borosilicate glass or alumino borosilicate glass is used. Note that as the substrate 600, a quartz substrate, a silicon substrate, a metal substrate, or a stainless steel substrate on which an insulating film is formed may be used. Further, a plastic substrate having heat resistance that can withstand the processing temperature of this embodiment may be used.
[0175]
Next, a base film 601 formed of an insulating film such as a silicon oxide film, a silicon nitride film, or a silicon oxynitride film is formed over the substrate 600 by a known means (a sputtering method, an LPCVD method, a plasma CVD method, or the like). In this embodiment, a base film 601a and a base film 601b are used as the base film 601; however, a single layer film of the insulating film or a structure in which two or more layers are stacked may be used (FIG. 23A). .
[0176]
Next, an amorphous semiconductor film 692 is formed on the base film 601 with a thickness of 25 to 80 nm (preferably 30 to 60 nm) by a known means (sputtering method, LPCVD method, plasma CVD method, or the like) (FIG. 23). (B)). Note that although an amorphous semiconductor film is formed in this embodiment, a microcrystalline semiconductor film or a crystalline semiconductor film may be used. Alternatively, a compound semiconductor film having an amorphous structure such as an amorphous silicon germanium film may be used.
[0177]
Next, the amorphous semiconductor film 692 is patterned and halogen fluoride, for example, ClF, ClF. ₃ , BrF, BrF ₃ , IF, IF ₃ The sub islands 693a, 693b, and 693c are formed by etching using an anisotropic dry etching method in an atmosphere including the like.
[0178]
Next, the sub-islands 693a, 693b, and 693c are crystallized by a laser crystallization method. Laser crystallization is performed using the laser irradiation method of the present invention. Specifically, the sub islands 693a, 693b, and 693c are selectively irradiated with laser light in accordance with mask information input to the computer of the laser irradiation apparatus. Of course, not only the laser crystallization method but also other known crystallization methods (thermal crystallization method using RTA or furnace annealing furnace, thermal crystallization method using metal element for promoting crystallization, etc.) You may go.
[0179]
When the amorphous semiconductor film is crystallized, a crystal having a large grain size can be obtained by using a solid-state laser capable of continuous oscillation and using the second to fourth harmonics of the fundamental wave. Typically, Nd: YVO ₄ It is desirable to use the second harmonic (532 nm) or the third harmonic (355 nm) of a laser (fundamental wave 1064 nm). Specifically, continuous wave YVO ₄ Laser light emitted from the laser is converted into a harmonic by a non-linear optical element to obtain laser light with an output of 10 W. Also, YVO in the resonator ₄ There is also a method of emitting harmonics by inserting a crystal and a nonlinear optical element. Preferably, the laser beam is shaped into a rectangular or elliptical shape on the irradiation surface by an optical system, and the object to be processed is irradiated. The energy density at this time is 0.01 to 100 MW / cm. ² Degree (preferably 0.1-10 MW / cm ² )is required. Then, irradiation is performed by moving the semiconductor film relative to the laser light at a speed of about 10 to 2000 cm / s.
[0180]
For laser irradiation, a continuous wave gas laser or solid laser can be used. There are excimer laser, Ar laser, Kr laser, etc. as gas laser, and YAG laser, YVO as solid laser. ₄ Laser, YLF laser, YAlO ₃ Laser, glass laser, ruby laser, alexandride laser, Ti: sapphire laser, Y ₂ O ₃ A laser etc. are mentioned. Solid lasers include YAG, YVO doped with Cr, Nd, Er, Ho, Ce, Co, Ti, Yb or Tm. ₄ , YLF, YAlO ₃ Lasers using crystals such as can also be used. The fundamental wave of the laser differs depending on the material to be doped, and laser light having a fundamental wave of around 1 μm can be obtained. The harmonic with respect to the fundamental wave can be obtained by using a nonlinear optical element.
[0181]
By the laser crystallization described above, the sub islands 693a, 693b, and 693c are irradiated with laser light, so that the sub islands 694a, 694b, and 694c with improved crystallinity are formed (FIG. 23B).
[0182]
Next, the sub-islands 694a, 694b, and 694c with improved crystallinity are patterned into a desired shape to form crystallized islands 602 to 606 (FIG. 23C).
[0183]
Further, after the islands 602 to 606 are formed, a small amount of impurity element (boron or phosphorus) may be doped in order to control the threshold value of the TFT.
[0184]
Next, a gate insulating film 607 covering the islands 602 to 606 is formed. The gate insulating film 607 is formed of an insulating film containing silicon with a thickness of 40 to 150 nm by a plasma CVD method or a sputtering method. In this embodiment, a silicon oxynitride film (composition ratio: Si = 32%, O = 59%, N = 7%, H = 2%) with a thickness of 110 nm is formed by plasma CVD. Needless to say, the gate insulating film is not limited to the silicon oxynitride film, and another insulating film containing silicon may be used as a single layer or a stacked structure.
[0185]
In the case of using a silicon oxide film, TEOS (Tetraethyl Orthosilicate) and O2 are formed by plasma CVD. ₂ The reaction pressure is 40 Pa, the substrate temperature is 300 to 400 ° C., and the high frequency (13.56 MHz) power density is 0.5 to 0.8 W / cm. ² And can be formed by discharging. The silicon oxide film thus manufactured can obtain good characteristics as a gate insulating film by thermal annealing at 400 to 500 ° C. thereafter.
[0186]
Next, a first conductive film 608 with a thickness of 20 to 100 nm and a second conductive film 609 with a thickness of 100 to 400 nm are stacked over the gate insulating film 607. In this example, a first conductive film 608 made of a TaN film with a thickness of 30 nm and a second conductive film 609 made of a W film with a thickness of 370 nm were stacked. The TaN film is formed by sputtering, and is sputtered in a nitrogen-containing atmosphere using a Ta target. The W film was formed by sputtering using a W target. In addition, tungsten hexafluoride (WF ₆ It can also be formed by a thermal CVD method using In any case, in order to use as a gate electrode, it is necessary to reduce the resistance, and the resistivity of the W film is desirably 20 μΩcm or less. The resistivity of the W film can be reduced by increasing the crystal grains. However, when there are many impurity elements such as oxygen in the W film, the crystallization is hindered and the resistance is increased. Therefore, in this embodiment, a sputtering method using a target of high purity W (purity 99.9999%) is used, and the W film is formed with sufficient consideration so that impurities are not mixed in from the gas phase during film formation. By forming, a resistivity of 9 to 20 μΩcm can be realized.
[0187]
In this embodiment, the first conductive film 608 is TaN and the second conductive film 609 is W. However, there is no particular limitation, and all of them are Ta, W, Ti, Mo, Al, Cu, Cr, Nd. You may form with the element selected from these, or the alloy material or compound material which has the said element as a main component. Alternatively, a semiconductor film typified by a polycrystalline silicon film doped with an impurity element such as phosphorus may be used. Further, an AgPdCu alloy may be used. In addition, the first conductive film is formed using a tantalum (Ta) film, the second conductive film is formed using a W film, the first conductive film is formed using a titanium nitride (TiN) film, and the second conductive film is formed. The first conductive film is formed of tantalum nitride (TaN), the second conductive film is formed of W, the first conductive film is formed of a tantalum nitride (TaN) film, Alternatively, the second conductive film may be a combination of Al films, the first conductive film may be a tantalum nitride (TaN) film, and the second conductive film may be a Cu film.
[0188]
The structure is not limited to the two-layer structure, and for example, a three-layer structure in which a tungsten film, an aluminum-silicon alloy (Al-Si) film, and a titanium nitride film are sequentially stacked may be employed. In the case of a three-layer structure, tungsten nitride may be used instead of tungsten, or an aluminum / titanium alloy film (Al—Ti) is used instead of an aluminum / silicon alloy film (Al—Si) film. Alternatively, a titanium film may be used instead of the titanium nitride film.
[0189]
Note that it is important to select an optimum etching method and etchant type depending on the material of the conductive film.
[0190]
Next, resist masks 610 to 615 are formed by photolithography, and a first etching process for forming electrodes and wirings is performed. The first etching process is performed under the first and second etching conditions. (FIG. 24B) In this embodiment, ICP (Inductively Coupled Plasma) etching is used as the first etching condition, and CF is used as an etching gas. ₄ And Cl ₂ And O ₂ Each gas flow rate ratio is set to 25:25:10 (sccm), and 500 W of RF (13.56 MHz) power is applied to the coil-type electrode at a pressure of 1 Pa to generate plasma and perform etching. . 150 W RF (13.56 MHz) power is also applied to the substrate side (sample stage), and a substantially negative self-bias voltage is applied. The W film is etched under this first etching condition so that the end portion of the first conductive layer is tapered.
[0191]
Thereafter, the resist masks 610 to 615 are not removed and the second etching condition is changed, and the etching gas is changed to CF. ₄ And Cl ₂ Each gas flow rate ratio is set to 30:30 (sccm), 500 W RF (13.56 MHz) power is applied to the coil-type electrode at a pressure of 1 Pa, and plasma is generated for about 30 seconds. Etching was performed. 20 W RF (13.56 MHz) power is also applied to the substrate side (sample stage), and a substantially negative self-bias voltage is applied. CF ₄ And Cl ₂ Under the second etching condition in which is mixed, the W film and the TaN film are etched to the same extent. Note that in order to perform etching without leaving a residue on the gate insulating film, it is preferable to increase the etching time at a rate of about 10 to 20%.
[0192]
In the first etching process, the end of the first conductive layer and the second conductive layer are tapered by the effect of the bias voltage applied to the substrate side by making the shape of the resist mask suitable. It becomes. The angle of this taper portion is 15 to 45 °. Thus, the first shape conductive layers 617 to 622 (the first conductive layers 617 a to 622 a and the second conductive layers 617 b to 622 b) composed of the first conductive layer and the second conductive layer by the first etching treatment. Form. Reference numeral 616 denotes a gate insulating film. A region that is not covered with the first shape conductive layers 617 to 622 is etched by about 20 to 50 nm to form a thinned region.
[0193]
Next, a second etching process is performed without removing the resist mask. (FIG. 24C) Here, CF is used as an etching gas. ₄ And Cl ₂ And O ₂ Then, the W film is selectively etched. At this time, second conductive layers 628b to 633b are formed by a second etching process. On the other hand, the first conductive layers 617a to 622a are hardly etched, and the second shape conductive layers 628 to 633 are formed.
[0194]
Then, a first doping process is performed without removing the resist mask, and an impurity element imparting n-type is added to the island at a low concentration. The doping process may be performed by ion doping or ion implantation. The condition of the ion doping method is a dose of 1 × 10 ¹³ ~ 5x10 ¹⁴ atoms / cm ² The acceleration voltage is 40 to 80 kV. In this embodiment, the dose is 1.5 × 10 ¹³ atoms / cm ² The acceleration voltage is 60 kV. As an impurity element imparting n-type, an element belonging to Group 15, typically phosphorus (P) or arsenic (As), is used here, but phosphorus (P) is used. In this case, the conductive layers 628 to 633 serve as a mask for the impurity element imparting n-type, and the impurity regions 623 to 627 are formed in a self-aligning manner. Impurity regions 623 to 627 have 1 × 10 ¹⁸ ~ 1x10 ²⁰ / Cm ³ An impurity element imparting n-type is added in a concentration range of.
[0195]
After removing the resist mask, new resist masks 634a to 634c are formed, and the second doping process is performed at an acceleration voltage higher than that of the first doping process. The condition of the ion doping method is a dose of 1 × 10 ¹³ ~ 1x10 ¹⁵ atoms / cm ² The acceleration voltage is set to 60 to 120 kV. In the doping treatment, the second conductive layers 628b to 632b are used as masks against the impurity element, and doping is performed so that the impurity element is added to the island below the tapered portion of the first conductive layer. Subsequently, the third doping process is performed by lowering the acceleration voltage than the second doping process to obtain the state of FIG. The condition of the ion doping method is a dose of 1 × 10 ¹⁵ ~ 1x10 ¹⁷ atoms / cm ² And an acceleration voltage of 50 to 100 kV. The low-concentration impurity regions 636, 642, and 648 overlapping with the first conductive layer by the second doping process and the third doping process have 1 × 10 ¹⁸ ~ 5x10 ¹⁹ / Cm ³ An impurity element imparting n-type is added in a concentration range of 1 × 10 in the high-concentration impurity regions 635, 641, 644 and 647. ¹⁹ ~ 5x10 ²¹ / Cm ³ An impurity element imparting n-type is added in a concentration range of.
[0196]
Needless to say, by setting the acceleration voltage to be appropriate, the second and third doping processes can be performed in a single doping process to form the low-concentration impurity region and the high-concentration impurity region.
[0197]
Next, after removing the resist mask, new resist masks 650a to 650c are formed, and a fourth doping process is performed. By this fourth doping treatment, impurity regions 653, 654, 659, and 660 in which an impurity element imparting a conductivity type opposite to the one conductivity type is added to the island that becomes the active layer of the p-channel TFT are formed. . The second conductive layers 628a to 632a are used as masks for the impurity element, and an impurity element imparting p-type is added to form an impurity region in a self-aligning manner. In this embodiment, the impurity regions 653, 654, 659, and 660 are diborane (B ₂ H ₆ ) Using an ion doping method. (FIG. 25B) In the fourth doping process, the islands forming the n-channel TFTs are covered with resist masks 650a to 650c. By the first to third doping treatments, phosphorus is added to the impurity regions 653 and 654 and 659 and 660 at different concentrations. In any of these regions, the concentration of the impurity element imparting p-type is 1 ×. 10 ¹⁹ ~ 5x10 ²¹ atoms / cm ³ By performing the doping treatment so as to become, no problem arises because it functions as the source region and drain region of the p-channel TFT.
[0198]
Through the above steps, impurity regions are formed in each island.
[0199]
Next, the resist masks 650a to 650c are removed, and a first interlayer insulating film 661 is formed. The first interlayer insulating film 661 is formed of an insulating film containing silicon with a thickness of 100 to 200 nm using a plasma CVD method or a sputtering method. In this embodiment, a silicon oxynitride film having a thickness of 150 nm is formed by a plasma CVD method. Needless to say, the first interlayer insulating film 661 is not limited to the silicon oxynitride film, and another insulating film containing silicon may be used as a single layer or a stacked structure.
[0200]
Next, as shown in FIG. 25C, a laser irradiation method is used as the activation treatment. When the laser annealing method is used, it is possible to use a laser used for crystallization. In the case of activation, the moving speed is the same as that of crystallization, and 0.01-100 MW / cm. ² Degree (preferably 0.01 to 10 MW / cm ² ) Energy density is required. Further, a continuous wave laser may be used for crystallization, and a pulsed laser may be used for activation.
[0201]
In addition, an activation process may be performed before forming the first interlayer insulating film.
[0202]
Then, hydrogenation can be performed by heat treatment (heat treatment at 300 to 550 ° C. for 1 to 12 hours). This step is a step of terminating the dangling bonds of the islands with hydrogen contained in the first interlayer insulating film 661. As other means of hydrogenation, plasma hydrogenation (using hydrogen excited by plasma) or heat treatment at 300 to 650 ° C. for 1 to 12 hours in an atmosphere containing 3 to 100% hydrogen good. In this case, the semiconductor layer can be hydrogenated regardless of the presence of the first interlayer insulating film.
[0203]
Next, a second interlayer insulating film 662 made of an inorganic insulating film material or an organic insulating material is formed over the first interlayer insulating film 661. In this example, an acrylic resin film having a thickness of 1.6 μm was formed. Next, after the second interlayer insulating film 662 is formed, a third interlayer insulating film 672 is formed so as to be in contact with the second interlayer insulating film 662.
[0204]
Then, wirings 663 to 668 that are electrically connected to the impurity regions are formed in the driver circuit 686. Note that these wirings are formed by patterning a laminated film of a Ti film having a thickness of 50 nm and an alloy film (alloy film of Al and Ti) having a thickness of 500 nm. Of course, not only a two-layer structure but also a single-layer structure or a laminated structure of three or more layers may be used. Further, the wiring material is not limited to Al and Ti. For example, a wiring may be formed by patterning a laminated film in which Al or Cu is formed on a TaN film and a Ti film is further formed. (Fig. 26)
[0205]
In the pixel portion 687, a pixel electrode 670, a gate wiring 669, and a connection electrode 668 are formed. With this connection electrode 668, the source wiring (stacked layer of 643a and 643b) is electrically connected to the pixel TFT. The gate wiring 669 is electrically connected to the gate electrode of the pixel TFT. In addition, the pixel electrode 670 is electrically connected to the drain region 690 of the pixel TFT, and is further electrically connected to an island 685 that functions as one electrode forming a storage capacitor. In the present application, the pixel electrode and the connection electrode are formed of the same material, but the pixel electrode 670 is made of a highly reflective material such as a film containing Al or Ag as a main component or a laminated film thereof. It is desirable to use it.
[0206]
As described above, the CMOS circuit including the n-channel TFT 681 and the p-channel TFT 682, the driving circuit 686 having the n-channel TFT 683, and the pixel portion 687 having the pixel TFT 684 and the storage capacitor 685 are formed over the same substrate. can do. Thus, the active matrix substrate is completed.
[0207]
The n-channel TFT 681 of the driver circuit 686 includes a channel formation region 637, a low-concentration impurity region 636 (GOLD (Gate Overlapped LDD) region) overlapping with the first conductive layer 628a that forms part of the gate electrode, a source region, or a drain region. A high-concentration impurity region 652 functioning as The p-channel TFT 682, which is connected to the n-channel TFT 681 by the electrode 666 to form a CMOS circuit, includes a channel formation region 640, a high-concentration impurity region 653 functioning as a source region or a drain region, and an impurity element imparting p-type conductivity Has an impurity region 654 into which is introduced. In the n-channel TFT 683, a channel formation region 643, a low-concentration impurity region 642 (GOLD region) that overlaps with the first conductive layer 630a that forms part of the gate electrode, and a high-concentration impurity that functions as a source region or a drain region A region 656 is included.
[0208]
The pixel TFT 684 in the pixel portion includes a channel formation region 646, a low concentration impurity region 645 (LDD region) formed outside the gate electrode, and a high concentration impurity region 658 functioning as a source region or a drain region. Further, an impurity element imparting n-type conductivity and an impurity element imparting p-type conductivity are added to the island that functions as one electrode of the storage capacitor 685. The storage capacitor 685 is formed of an electrode (stack of 632a and 632b) and an island using the insulating film 616 as a dielectric.
[0209]
In the pixel structure of this embodiment, the end portions of the pixel electrodes are arranged and formed so as to overlap the source wiring so that the gap between the pixel electrodes is shielded from light without using a black matrix.
[0210]
This embodiment can be implemented in combination with the first to fourth embodiments.
[0211]
(Example 6)
In this embodiment, a process for manufacturing a reflective liquid crystal display device from the active matrix substrate manufactured in Embodiment 5 will be described below. FIG. 27 is used for the description.
[0212]
First, after obtaining the active matrix substrate in the state of FIG. 26 according to the fifth embodiment, an alignment film 867 is formed on at least the pixel electrode 670 on the active matrix substrate of FIG. In this embodiment, before the alignment film 867 is formed, a columnar spacer 872 for maintaining the distance between the substrates is formed by patterning an organic resin film such as an acrylic resin film. Further, instead of the columnar spacers, spherical spacers may be scattered over the entire surface of the substrate.
[0213]
Next, a counter substrate 869 is prepared. Next, colored layers 870 and 871 and a planarization film 873 are formed over the counter substrate 869. The red colored layer 870 and the blue colored layer 871 are overlapped to form a light shielding portion. Further, the light shielding portion may be formed by partially overlapping the red colored layer and the green colored layer.
[0214]
In this example, the substrate shown in Example 5 is used. Accordingly, at least the gap between the gate wiring 669 and the pixel electrode 670, the gap between the gate wiring 669 and the connection electrode 668, and the gap between the connection electrode 668 and the pixel electrode 670 need to be shielded from light. In this example, the respective colored layers were arranged so that the light-shielding portions formed by the lamination of the colored layers overlapped at the positions where light shielding should be performed, and the counter substrate was bonded.
[0215]
As described above, the number of steps can be reduced by shielding the gap between the pixels with the light shielding portion formed by the lamination of the colored layers without forming a light shielding layer such as a black mask.
[0216]
Next, a counter electrode 876 made of a transparent conductive film was formed over the planarization film 873 at least in the pixel portion, an alignment film 874 was formed over the entire surface of the counter substrate, and a rubbing process was performed.
[0217]
Then, the active matrix substrate on which the pixel portion and the driver circuit are formed and the counter substrate are attached to each other with a sealant 868. A filler is mixed in the sealing material 868, and two substrates are bonded to each other with a uniform interval by the filler and the columnar spacer. Thereafter, a liquid crystal material 875 is injected between both substrates and completely sealed with a sealant (not shown). A known liquid crystal material may be used for the liquid crystal material 875. In this way, the reflection type liquid crystal display device shown in FIG. 27 is completed. If necessary, the active matrix substrate or the counter substrate is divided into a desired shape. Further, a polarizing plate (not shown) was attached only to the counter substrate. And FPC was affixed using the well-known technique.
[0218]
The liquid crystal display device manufactured as described above includes a TFT manufactured using a semiconductor film in which a laser beam having a periodic or uniform energy distribution is irradiated and crystal grains having a large particle size are formed. Therefore, the operation characteristics and reliability of the liquid crystal display device can be sufficient. And such a liquid crystal display device can be used as a display part of various electronic devices.
[0219]
Note that this embodiment can be implemented in combination with the first to fifth embodiments.
[0220]
(Example 7)
In this example, an example of manufacturing a light-emitting device using the manufacturing method of a TFT when manufacturing an active matrix substrate shown in Example 5 will be described below. The light emitting device is a general term for a display panel in which a light emitting element formed on a substrate is sealed between the substrate and a cover material, and a display module in which a TFT or the like is mounted on the display panel. Note that the light-emitting element includes a layer (light-emitting layer) containing an organic compound from which luminescence (Electro Luminescence) generated by applying an electric field is obtained, an anode layer, and a cathode layer. In addition, luminescence in an organic compound includes light emission (fluorescence) when returning from a singlet excited state to a ground state and light emission (phosphorescence) when returning from a triplet excited state to a ground state, one of these, Or both luminescence is included.
[0221]
In the present specification, all layers formed between the anode and the cathode in the light emitting element are defined as organic light emitting layers. Specifically, the organic light emitting layer includes a light emitting layer, a hole injection layer, an electron injection layer, a hole transport layer, an electron transport layer, and the like. Basically, a light emitting element has a structure in which an anode layer, a light emitting layer, and a cathode layer are sequentially laminated. In addition to this structure, an anode layer, a hole injection layer, a light emitting layer, a cathode layer, and an anode layer , A hole injection layer, a light emitting layer, an electron transport layer, a cathode layer and the like may be laminated in this order.
[0222]
Note that the light-emitting element used in this example is formed using a material in which a hole injection layer, an electron injection layer, a hole transport layer, an electron transport layer, or the like is an inorganic compound alone or an organic compound is mixed with an inorganic compound. It can also take the form which is made. These layers may be partially mixed with each other.
[0223]
FIG. 28A is a cross-sectional view of the light-emitting device of this example at the time when the third interlayer insulating film 750 is formed. In FIG. 28A, a switching TFT 733 and a current control TFT 734 provided over a substrate 700 are formed by using the manufacturing method of Embodiment 5. In this embodiment, the switching TFT 733 has a double gate structure in which two channel forming regions are formed, but may have a single gate structure in which one channel forming region is formed or a structure in which three or more channel forming regions are formed. In this embodiment, the current control TFT 734 has a single gate structure in which one channel formation region is formed, but may have a structure in which two or more channel formation regions are formed.
[0224]
The n-channel TFT 731 and the p-channel TFT 732 included in the driver circuit provided over the substrate 700 are formed using the manufacturing method of Embodiment 5. In this embodiment, a single gate structure is used, but a double gate structure or a triple gate structure may be used.
[0225]
In the case of a light emitting device, the third interlayer insulating film 750 is effective for preventing moisture contained in the second interlayer insulating film 751 from entering the organic light emitting layer. In the case where the second interlayer insulating film 751 includes an organic resin material, since the organic resin material contains a large amount of moisture, it is particularly effective to provide the third interlayer insulating film 750.
[0226]
When the process up to the production of the third interlayer insulating film of Example 5 is completed, the pixel electrode 711 is formed on the third interlayer insulating film 750 in this example.
[0227]
Note that the pixel electrode 711 is a pixel electrode (anode of a light emitting element) made of a transparent conductive film. As the transparent conductive film, a compound of indium oxide and tin oxide, a compound of indium oxide and zinc oxide, zinc oxide, tin oxide, or indium oxide can be used. Moreover, you may use what added the gallium to the said transparent conductive film. The pixel electrode 711 is formed on the flat third interlayer insulating film 750 before the wiring is formed. In this embodiment, it is very important to flatten the step due to the TFT using the second interlayer insulating film 751 made of resin. Since the light emitting layer formed later is very thin, the presence of a step may cause a light emission failure. Therefore, it is desirable to planarize the pixel electrode before forming it so that the light emitting layer can be formed as flat as possible.
[0228]
Next, as shown in FIG. 28B, a resin film in which black dye, carbon, black pigment, or the like is dispersed is formed so as to cover the third interlayer insulating film 750, and an opening is formed in a portion serving as a light emitting element. The shielding film 770 is formed by forming the part. Typical examples of the resin include polyimide, polyamide, acrylic, and BCB (benzocyclobutene), but are not limited to the above materials. In addition to the organic resin, for example, silicon, silicon oxide, silicon oxynitride, or the like mixed with a black dye, carbon, or black pigment can be used as a material for the shielding film. The shielding film 770 has an effect of preventing external light reflected by the wirings 701 to 707 from entering the eyes of the observer.
[0229]
Next, after the pixel electrode 711 is formed, contact holes are formed in the gate insulating film 752, the first interlayer insulating film 753, the second interlayer insulating film 751, the third interlayer insulating film 750, and the shielding film 770. Then, a conductive film is formed over the shielding film 770 so as to cover the pixel electrode 711, and the conductive film is etched to form wirings 701 to 707 that are electrically connected to the impurity regions of the TFTs, respectively. Note that these wirings are formed by patterning a laminated film of a Ti film having a thickness of 50 nm and an alloy film (alloy film of Al and Ti) having a thickness of 500 nm. Of course, not only a two-layer structure but also a single-layer structure or a laminated structure of three or more layers may be used. Further, the wiring material is not limited to Al and Ti. For example, a wiring may be formed by patterning a laminated film in which Al or Cu is formed on a TaN film and a Ti film is further formed. (Fig. 28 (A))
[0230]
A wiring 707 is a source wiring (corresponding to a current supply line) of the current control TFT, and 706 is an electrode for electrically connecting the drain region of the current control TFT and the pixel electrode 711.
[0231]
After forming the wirings 701 to 707, a bank 712 made of a resin material is formed. The bank 712 is formed so as to expose a part of the pixel electrode 711 by patterning an acrylic film or a polyimide film having a thickness of 1 to 2 μm.
[0232]
A light emitting layer 713 is formed on the pixel electrode 711. Although only one pixel is shown in FIG. 28B, in this embodiment, light emitting layers corresponding to R (red), G (green), and B (blue) colors are separately formed. In this embodiment, a low molecular weight organic light emitting material is formed by a vapor deposition method. Specifically, a copper phthalocyanine (CuPc) film having a thickness of 20 nm is provided as a hole injection layer, and a tris-8-quinolinolato aluminum complex (Alq) having a thickness of 70 nm is formed thereon as a light emitting layer. ₃ ) A laminated structure provided with a film. Alq ₃ The emission color can be controlled by adding a fluorescent dye such as quinacridone, perylene, or DCM1.
[0233]
However, the above example is an example of an organic light emitting material that can be used as a light emitting layer, and it is not absolutely necessary to limit to this. A light emitting layer (a layer for emitting light and moving carriers therefor) may be formed by freely combining a light emitting layer, a charge transport layer, or a charge injection layer. For example, in this embodiment, an example in which a low molecular weight organic light emitting material is used as the light emitting layer is shown, but a medium molecular weight organic light emitting material or a high molecular weight organic light emitting material may be used. Note that in this specification, an organic light-emitting material that does not have sublimation and has 20 or less molecules or a chain molecule length of 10 μm or less is referred to as a medium molecular organic light-emitting material. As an example of using a polymer organic light emitting material, a 20 nm polythiophene (PEDOT) film is provided by a spin coating method as a hole injection layer, and a paraphenylene vinylene (PPV) film of about 100 nm is provided thereon as a light emitting layer. Alternatively, a laminated structure may be used. If a PPV π-conjugated polymer is used, the emission wavelength can be selected from red to blue. It is also possible to use an inorganic material such as silicon carbide for the charge transport layer or the charge injection layer. Known materials can be used for these organic light emitting materials and inorganic materials.
[0234]
Next, a cathode 714 made of a conductive film is provided on the light emitting layer 713. In this embodiment, an alloy film of aluminum and lithium is used as the conductive film. Of course, a known MgAg film (magnesium and silver alloy film) may be used. As the cathode material, a conductive film made of an element belonging to Group 1 or Group 2 of the periodic table or a conductive film added with these elements may be used.
[0235]
When the cathode 714 is formed, the light emitting element 715 is completed. Note that the light-emitting element 715 here refers to a diode formed of a pixel electrode (anode) 711, a light-emitting layer 713, and a cathode 714.
[0236]
A protective film 754 may be provided so as to completely cover the light-emitting element 715. As the protective film 754, an insulating film including a carbon film, a silicon nitride film, or a silicon nitride oxide film is used, and the insulating film is used as a single layer or a laminated layer.
[0237]
At this time, it is preferable to use a film with good coverage as the protective film 754, and it is effective to use a carbon film, particularly a DLC (diamond-like carbon) film. Since the DLC film can be formed in a temperature range from room temperature to 100 ° C., it can be easily formed over the light-emitting layer 713 having low heat resistance. In addition, the DLC film has a high blocking effect against oxygen and can suppress oxidation of the light-emitting layer 713. Therefore, the problem that the light emitting layer 713 is oxidized during the subsequent sealing process can be prevented.
[0238]
In this embodiment, since the light emitting layer and 713 are all covered with an inorganic insulating film such as a carbon film having high barrier properties, silicon nitride, silicon nitride oxide, aluminum nitride, or aluminum nitride oxide, moisture, oxygen, and the like are emitted from the light emitting layer. It is possible to more effectively prevent the light emitting layer from entering and deteriorating.
[0239]
In particular, when the third insulating film 750, the passivation film 712, and the protective film 754 are formed using a silicon nitride film formed by a sputtering method using silicon as a target, impurities can be prevented from entering the light emitting layer. The film formation conditions may be selected as appropriate, but nitrogen (N ₂ ) Or a mixed gas of nitrogen and argon, and high frequency power is applied to perform sputtering. The substrate temperature is set to room temperature, and the heating means may not be used. After the organic insulating film or the organic compound layer is already formed, it is desirable to form the film without heating the substrate. However, in order to sufficiently remove the adsorbed or occluded water, it is preferable to perform dehydration by heating at about 50 to 100 ° C. for several minutes to several hours in a vacuum.
[0240]
A silicon nitride film formed by sputtering using silicon as a target at room temperature and applying a high frequency power of 13.56 MHz and using only nitrogen gas absorbs N—H bonds and Si—H bonds in its infrared absorption spectrum. It is characteristic that no peak is observed and no absorption peak of Si—O is observed, and it is known that the oxygen concentration and the hydrogen concentration in the film are 1 atomic% or less. This also shows that impurities such as oxygen and moisture can be prevented more effectively.
[0241]
Further, a sealing material 717 is provided to cover the light-emitting element 715, and a cover material 718 is attached. As the sealing material 717, an ultraviolet curable resin may be used, and it is effective to provide a substance having a hygroscopic effect or a substance having an antioxidant effect inside. In this embodiment, the cover material 718 is formed by forming a carbon film (preferably a diamond-like carbon film) on both surfaces of a glass substrate, a quartz substrate, or a plastic substrate (including a plastic film).
[0242]
Thus, a light emitting device having a structure as shown in FIG. 28B is completed. Note that it is effective to continuously process the steps from the formation of the bank 712 to the formation of the protective film without releasing to the atmosphere. Further, it is possible to continuously process the process up to the step of bonding the cover material 718 without releasing to the atmosphere.
[0243]
Thus, n-channel TFTs 731 and 732, a switching TFT (n-channel TFT) 733 and a current control TFT (n-channel TFT) 734 are formed on the substrate 700.
[0244]
In this embodiment, the shielding film 770 is formed between the third interlayer insulating film 750 and the bank 712, but the present invention is not limited to this configuration. It is important to provide the external light reflected by the wirings 701 to 707 at a position where it can be prevented from entering the eyes of the observer. For example, when light emitted from the light emitting element 715 is directed toward the substrate 700 as in this embodiment, a shielding film is provided between the first interlayer insulating film 753 and the second interlayer insulating film 751. Also good. Also in this case, the shielding film has an opening so that light from the light emitting element can pass therethrough.
[0245]
Further, as described with reference to FIG. 28, an n-channel TFT which is resistant to deterioration due to the hot carrier effect can be formed by providing an impurity region overlapping with the gate electrode through an insulating film. Therefore, a highly reliable light emitting device can be realized.
[0246]
Further, in this embodiment, only the configuration of the pixel portion and the drive circuit is shown. However, according to the manufacturing process of this embodiment, other logic circuits such as a signal dividing circuit, a D / A converter, an operational amplifier, and a γ correction circuit are provided. Can be formed on the same insulator, and a memory and a microprocessor can also be formed.
[0247]
The light-emitting device manufactured as described above has a TFT manufactured using a semiconductor film on which large-sized crystal grains are formed by irradiation with laser light having a periodic or uniform energy distribution. The operational characteristics and reliability of the light emitting device can be sufficient. And such a light-emitting device can be used as a display part of various electronic devices.
[0248]
In this embodiment, the light emitted from the light emitting element is directed to the TFT side, but the light emitting element may be directed to the opposite side of the TFT. In this case, a resin in which a black dye, carbon, or black pigment is mixed in the bank can be used. FIG. 33 is a cross-sectional view of a light-emitting device in which light emission from the light-emitting element is directed in the direction opposite to the TFT.
[0249]
In FIG. 33, after forming the third interlayer insulating film 1950, contact holes are formed in the gate insulating film 1952, the first interlayer insulating film 1953, the second interlayer insulating film 1951, and the third interlayer insulating film 1950. . Then, a conductive film is formed over the third interlayer insulating film 1950, and the conductive film is etched to form wirings 1901 to 1907 that are electrically connected to the impurity regions of the TFTs, respectively. These wirings are formed by patterning a 300 nm thick aluminum alloy film (aluminum film containing 1 wt% titanium). Of course, it is not limited to a single layer structure, and may be a laminated structure of two or more layers. Further, the wiring material is not limited to Al and Ti. A part of the wiring 1906 also serves as a pixel electrode.
[0250]
After the wirings 1901 to 1907 are formed, a bank 1912 made of a resin material is formed. The bank 1912 is formed so as to expose a part of the pixel electrode 1906 by patterning a resin mixed with a black dye, carbon, or black pigment having a thickness of 1 to 2 μm. Typical examples of the resin include polyimide, polyamide, acrylic, and BCB (benzocyclobutene), but are not limited to the above materials.
[0251]
A light emitting layer 1913 is formed on the pixel electrode 1906. Then, a counter electrode (an anode of the light emitting element) made of a transparent conductive film is formed so as to cover the light emitting layer 1913. As the transparent conductive film, a compound of indium oxide and tin oxide, a compound of indium oxide and zinc oxide, zinc oxide, tin oxide, or indium oxide can be used. Moreover, you may use what added the gallium to the said transparent conductive film.
[0252]
A light emitting element 1915 is formed by the pixel electrode 906, the light emitting layer 1913, and the counter electrode 1914.
[0253]
The shielding film 1970 has an effect of preventing external light reflected by the wirings 1901 to 1907 from entering the eyes of the observer.
[0254]
In addition, a present Example can be implemented in combination with any one of Example 1- Example 6.
[0255]
(Example 8)
In this embodiment, a structure of a pixel of a light emitting device which is one of semiconductor devices of the present invention will be described. FIG. 29 shows a cross-sectional view of a pixel of the light emitting device of this embodiment.
[0256]
In FIG. 29, reference numeral 911 denotes a substrate, and reference numeral 912 denotes an insulating film serving as a base (hereinafter referred to as a base film). As the substrate 911, a light-transmitting substrate, typically a glass substrate, a quartz substrate, a glass ceramic substrate, or a crystallized glass substrate can be used. However, it must withstand the maximum processing temperature during the fabrication process.
[0257]
Reference numeral 8201 denotes a switching TFT, and 8202 denotes a current control TFT, which are formed of an n-channel TFT and a p-channel TFT, respectively. When the light emitting direction of the organic light emitting layer is the lower surface of the substrate (the surface on which the TFT and the organic light emitting layer are not provided), the above configuration is preferable. However, the switching TFT and the current control TFT may be either an n-channel TFT or a p-channel TFT.
[0258]
The switching TFT 8201 includes an active layer including a source region 913, a drain region 914, LDD regions 915a to 915d, an isolation region 916, and channel formation regions 963 and 964, a gate insulating film 918, gate electrodes 919a and 919b, and a first interlayer. An insulating film 920, a source signal line 921, and a drain wiring 922 are included. Note that the gate insulating film 918 or the first interlayer insulating film 920 may be common to all TFTs on the substrate, or may be different depending on a circuit or an element.
[0259]
A switching TFT 8201 shown in FIG. 29 has a so-called double gate structure in which gate electrodes 917a and 917b are electrically connected. Needless to say, not only a double gate structure but also a so-called multi-gate structure (a structure including an active layer having two or more channel formation regions connected in series) such as a triple gate structure may be used.
[0260]
The multi-gate structure is extremely effective in reducing the off-current. If the off-current of the switching TFT is made sufficiently low, the minimum capacity required for the storage capacitor connected to the gate electrode of the current control TFT 8202 can be reduced. Can be suppressed. That is, since the area of the storage capacitor can be reduced, the multi-gate structure is effective in increasing the effective light emitting area of the light emitting element.
[0261]
Further, in the switching TFT 8201, the LDD regions 915a to 915d are provided so as not to overlap with the gate electrodes 919a and 919b with the gate insulating film 918 interposed therebetween. Such a structure is very effective in reducing off current. The length (width) of the LDD regions 915a to 915d may be set to 0.5 to 3.5 μm, typically 2.0 to 2.5 μm. Note that in the case of a multi-gate structure having two or more gate electrodes, an isolation region 916 (a region to which the same impurity element is added at the same concentration as the source region or the drain region) provided between the channel formation regions is provided. It is effective for reducing the off current.
[0262]
Next, the current control TFT 8202 includes an active layer including a source region 926, a drain region 927, and a channel formation region 905, a gate insulating film 918, a gate electrode 930, a first interlayer insulating film 920, a source signal line 931, and the like. A drain wiring 932 is formed. In this embodiment, the current control TFT 8202 is a p-channel TFT.
[0263]
The drain region 914 of the switching TFT 8201 is connected to the gate 930 of the current control TFT 8202. Although not shown, specifically, the gate electrode 930 of the current control TFT 8202 is electrically connected to the drain region 914 of the switching TFT 8201 via the drain wiring (also referred to as connection wiring) 922. Note that the gate electrode 930 has a single gate structure, but may have a multi-gate structure. The source signal line 931 of the current control TFT 8202 is connected to a power supply line (not shown).
[0264]
Although the above has described the structure of the TFT provided in the pixel, a driving circuit is also formed at this time. FIG. 29 shows a CMOS circuit as a basic unit for forming a driving circuit.
[0265]
In FIG. 29, a TFT having a structure for reducing hot carrier injection while reducing the operating speed as much as possible is used as the n-channel TFT 8204 of the CMOS circuit. Note that the driver circuit here refers to a source signal side driver circuit and a gate signal side driver circuit. Of course, other logic circuits (level shifter, A / D converter, signal dividing circuit, etc.) can be formed.
[0266]
An active layer of the n-channel TFT 8204 in the CMOS circuit includes a source region 935, a drain region 936, an LDD region 937, and a channel formation region 962, and the LDD region 937 overlaps with the gate electrode 939 with a gate insulating film 918 interposed therebetween.
[0267]
The reason why the LDD region 937 is formed only on the drain region 936 side is to prevent the operation speed from being lowered. In addition, the n-channel TFT 8204 does not need to worry about the off-current value so much, and it is better to focus on the operation speed than that. Therefore, it is desirable that the LDD region 937 is completely overlapped with the gate electrode to reduce the resistance component as much as possible. That is, it is better to eliminate the so-called offset.
[0268]
Further, the p-channel TFT 8205 of the CMOS circuit is hardly concerned with deterioration due to hot carrier injection, so that it is not particularly necessary to provide an LDD region. Therefore, the active layer includes a source region 940, a drain region 941, and a channel formation region 961, and a gate insulating film 918 and a gate electrode 943 are provided thereunder. Needless to say, it is possible to provide an LDD region as in the case of the n-channel TFT 8204 and take measures against hot carriers.
[0269]
Note that 942, 938, 917a, 917b, and 929 are masks for forming channel formation regions 961 to 965.
[0270]
Each of the n-channel TFT 8204 and the p-channel TFT 8205 has source signal lines 944 and 945 over the source region with a first interlayer insulating film 920 interposed therebetween. Further, the drain regions of the n-channel TFT 8204 and the p-channel TFT 8205 are electrically connected to each other by the drain wiring 946.
[0271]
The laser irradiation method of the present invention can be used in the process of forming a semiconductor film, crystallization of an active layer, activation, or other laser annealing.
[0272]
FIG. 30 shows a production flow in the case of manufacturing the light emitting device of this example. First, a semiconductor device is designed using CAD. Specifically, an island mask is first designed, and then a sub-island mask is designed that includes one or more islands.
[0273]
Then, information (pattern information) on the shape of the designed sub-island mask is input to a computer included in the laser irradiation apparatus. In the computer, based on the input sub-island pattern information, the width W of each sub-island in the direction perpendicular to the scanning direction. _S Is calculated. And the width W of each sub island _S Based on the above, the slit width W in the direction perpendicular to the scanning direction _BW Set. Next, slit width W _BW Based on the above, the scanning path of the laser beam is determined based on the marker position.
[0274]
On the other hand, a gate electrode is formed according to the marker formed on the substrate. At this time, the gate electrode and the marker may be formed simultaneously. Then, a gate insulating film is formed so as to cover the gate electrode, and a semiconductor film is formed so as to be in contact with the gate insulating film. Then, the semiconductor film is patterned using a sub-island mask to form a sub-island. Then, the substrate on which the sub island is formed is placed on the stage of the laser irradiation apparatus.
[0275]
Next, with the marker as a reference, laser light is irradiated along a predetermined scanning path to crystallize the sub-island.
[0276]
Then, after irradiating the laser beam, the sub-island whose crystallinity is enhanced by the laser beam irradiation is patterned to form an island. Although the following specific manufacturing steps differ depending on the shape of the TFT, typically, an impurity region is formed on the island. Then, an interlayer insulating film is formed so as to cover the island, a contact hole is formed in the interlayer insulating film, and a part of the impurity region is exposed. Then, a wiring is formed on the interlayer insulating film so as to be in contact with the impurity region through the contact hole.
[0277]
In addition, the structure of a present Example can be implemented combining freely with Examples 1-7.
[0278]
Example 9
In this example, a structure of a pixel of a light-emitting device manufactured using the laser irradiation method of the present invention will be described. FIG. 31 is a cross-sectional view of a pixel of the light emitting device of this example.
[0279]
Reference numeral 1751 denotes an n-channel TFT, and reference numeral 1752 denotes a p-channel TFT. The n-channel TFT 1751 includes a semiconductor film 1753, a first insulating film 1770, first electrodes 1754 and 1755, a second insulating film 1771, and second electrodes 1756 and 1757. The semiconductor film 1753 includes a first concentration one-conductivity type impurity region 1758, a second concentration one-conductivity type impurity region 1759, and channel formation regions 1760 and 1761.
[0280]
The first electrodes 1754 and 1755 and the channel formation regions 1760 and 1761 overlap each other with the first insulating film 1770 interposed therebetween. Further, the second electrodes 1756 and 1757 and the channel formation regions 1760 and 1761 overlap with the second insulating film 1771 interposed therebetween.
[0281]
The p-channel TFT 1752 includes a semiconductor film 1780, a first insulating film 1770, a first electrode 1782, a second insulating film 1771, and a second electrode 1781. The semiconductor film 1780 includes a third-conductivity one-conductivity type impurity region 1783 and a channel formation region 1784.
[0282]
The first electrode 1782 and the channel formation region 1784 overlap with each other with the first insulating film 1770 interposed therebetween. The second electrode 1781 and the channel formation overlap with each other with the second insulating film 1771 interposed therebetween.
[0283]
The first electrode 1782 and the second electrode 1781 are electrically connected through a wiring 1790.
[0284]
The laser irradiation method of the present invention can be used in the steps of forming semiconductor films 1753 and 1780, crystallization, activation, or other laser annealing.
[0285]
In this embodiment, a constant voltage is applied to the first electrode of a TFT used as a switching element (in this embodiment, an n-channel TFT 1751). By applying a constant voltage to the first electrode, variation in threshold value can be suppressed as compared with the case where there is one electrode, and off-state current can be suppressed.
[0286]
In addition, a TFT (p-channel TFT 1752 in this embodiment) that flows a larger current than a TFT used as a switching element electrically connects the first electrode and the second electrode. By applying the same voltage to the first electrode and the second electrode, the depletion layer spreads as fast as when the film thickness of the semiconductor film is substantially reduced, so that the subthreshold coefficient can be reduced. The on-current can be increased. Therefore, the driving voltage can be lowered by using the TFT having this structure in the driving circuit. In addition, since the on-current can be increased, the TFT size (especially the channel width) can be reduced. Therefore, the integration density can be improved.
[0287]
FIG. 32 shows a production flow in the case of manufacturing the light-emitting device of this example. First, a semiconductor device is designed using CAD. Specifically, an island mask is first designed, and then a sub-island mask including one or more islands is designed. Then, the designed sub-island pattern information is input to a computer included in the laser irradiation apparatus.
[0288]
In the computer, based on the input sub-island pattern information, the width W of each sub-island in the direction perpendicular to the scanning direction. _S Is calculated. And the width W of each sub island _S Based on the above, the slit width W in the direction perpendicular to the scanning direction _BW Set. Next, slit width W _BW Based on the above, the scanning path of the laser beam is determined based on the marker position.
[0289]
On the other hand, the first electrode is formed according to the marker formed on the substrate. At this time, the first electrode and the marker may be formed at the same time. Then, a first insulating film is formed so as to cover the first electrode, and a semiconductor film is formed so as to be in contact with the first insulating film. Then, the semiconductor film is patterned using a sub-island mask to form a sub-island. Then, the substrate on which the sub island is formed is placed on the stage of the laser irradiation apparatus.
[0290]
Next, with the marker as a reference, laser light is irradiated along a predetermined scanning path to crystallize the sub-island.
[0291]
Then, after irradiating the laser beam, the sub-island whose crystallinity is enhanced by the laser beam irradiation is patterned to form an island. Although the following specific manufacturing steps differ depending on the shape of the TFT, typically, an impurity region is formed on the island. Then, after irradiating the laser light, a second insulating film and a second electrode are sequentially formed so as to cover the island, and an impurity region is formed in the island. Then, an interlayer insulating film is formed so as to cover the second insulating film and the second electrode, a contact hole is formed in the interlayer insulating film, and a part of the impurity region is exposed. Then, a wiring is formed on the interlayer insulating film so as to be in contact with the impurity region through the contact hole.
[0292]
In addition, a present Example can be implemented in combination with any one of Example 1- Example 8.
[0293]
(Example 10)
In this embodiment, a driver circuit (a signal line driver circuit or a scanning line driver circuit) is manufactured using the laser irradiation method of the present invention, and TAB or COG or the like is used for a pixel portion formed using an amorphous semiconductor film. An example of implementation will be described.
[0294]
FIG. 40A illustrates an example in which a driver circuit is mounted on a TAB and the pixel portion is connected to a printed board on which an external controller or the like is formed using the TAB. A pixel portion 5001 is formed on a glass substrate 5000 and connected to a driver circuit 5002 manufactured by the laser irradiation method of the present invention through a TAB 5005. The drive circuit 5002 is connected to the printed circuit board 5003 through a TAB 5005. The printed circuit board 5003 is provided with a terminal 5004 for connecting to an external interface.
[0295]
FIG. 40B illustrates an example in which the driver circuit and the pixel portion are mounted with COG. A pixel portion 5101 is formed on a glass substrate 5100, and a driving circuit 5102 manufactured by the laser irradiation method of the present invention is mounted on the glass substrate. The substrate 5100 is provided with a terminal 5104 for connection to an external interface.
[0296]
As described above, since the TFT manufactured by the laser irradiation method of the present invention has higher crystallinity in the channel formation region, it can operate at high speed and constitutes a driving circuit that requires high-speed operation compared to the pixel portion. More suitable for. In addition, the yield can be increased by separately manufacturing the pixel portion and the driver circuit.
[0297]
In addition, a present Example can be implemented in combination with any one of Example 1- Example 9.
[0298]
(Example 11)
In this example, a method for manufacturing a TFT using the laser irradiation method of the present invention will be described.
[0299]
First, as illustrated in FIG. 34A, an amorphous semiconductor film is formed over an insulating surface, and the amorphous semiconductor film is etched, whereby island-shaped semiconductor films 6001 and 6002 are formed. FIG. 34G is a top view of FIG. 34A, and a cross-sectional view taken along line AA ′ corresponds to FIG. Next, as illustrated in FIG. 34B, an amorphous semiconductor film 6003 is formed so as to cover the island-shaped semiconductor films 6001 and 6002. FIG. 34H is a top view of FIG. 34B, and a cross-sectional view taken along line AA ′ corresponds to FIG.
[0300]
Next, as shown in FIG. 34C, by patterning the amorphous semiconductor film 6003, a sub-island 6004 covering the island-shaped semiconductor films 6001 and 6002 is formed. FIG. 34I is a top view of FIG. 34C, and a cross-sectional view taken along line AA ′ corresponds to FIG. Next, as illustrated in FIG. 34D, the island-shaped semiconductor films 6001 and 6002 and the sub-island 6004 are selectively irradiated with laser light to improve the crystallinity. , 6006 and a sub-island 6007 are formed. At this time, the boundary between the island-shaped semiconductor films 6005 and 6006 with improved crystallinity and the sub-island 6007 may be blurred to some extent depending on the irradiation condition of laser light. For the time being, they are shown separately, but may be regarded as one sub-island. FIG. 34 (J) is a top view of FIG. 34 (D), and a cross-sectional view along AA ′ corresponds to FIG. 34 (D).
[0301]
Next, as illustrated in FIG. 34E, the sub-island 6007 with improved crystallinity is patterned to form an island 6008. FIG. 34K is a top view of FIG. 34E, and a cross-sectional view along AA ′ corresponds to FIG. Then, as shown in FIG. 34F, a TFT is formed using an island 6008. Although the following specific manufacturing steps differ depending on the shape of the TFT, typically, a step of forming the gate insulating film 6009 so as to be in contact with the island 6008, a step of forming the gate electrode 6010 over the gate insulating film, A step of forming impurity regions 6011 and 6012 and a channel formation region 6013 in 6008, a step of forming an interlayer insulating film 6014 covering the gate insulating film 6009, the gate electrode 6010, and the island 6008, and the impurity regions 6011 and 6012 are connected. A step of forming wirings 6015 and 6016 over the interlayer insulating film 6014 is performed. FIG. 34L is a top view of FIG. 34F, and a cross-sectional view taken along line AA ′ corresponds to FIG.
[0302]
Note that the impurity regions 6011 and 6012 are formed using island-shaped semiconductor films 6005 and 6006 and part of the island 6008. Therefore, the impurity regions 6011 and 6012 are thicker than the channel formation region 6013, and the resistance of the impurity regions can be reduced.
[0303]
Note that in FIG. 34, the sub-island is crystallized only by the laser light, but a step of crystallizing the semiconductor film using a catalyst may be included.
[0304]
FIG. 35 illustrates a method for manufacturing an island using both a catalytic element and laser light. In the case of using a catalyst element, it is desirable to use the techniques disclosed in Japanese Patent Application Laid-Open Nos. 7-130652 and 8-78329.
[0305]
First, as illustrated in FIG. 35A, an amorphous semiconductor film is formed over an insulating surface, and the amorphous semiconductor film is etched, whereby island-shaped semiconductor films 6101 and 6102 are formed. Next, as illustrated in FIG. 35B, an amorphous semiconductor film 6103 is formed so as to cover the island-shaped semiconductor films 6101 and 6102. Next, as shown in FIG. 35C, a nickel-containing layer is formed by applying a nickel acetate salt solution containing nickel of 10 ppm by weight on the amorphous semiconductor film 6103 to the amorphous semiconductor film, After the dehydrogenation step at 500 ° C. for 1 hour, the island-shaped semiconductor film 6104 with improved crystallinity is obtained by crystallization by performing heat treatment at 500 to 650 ° C. for 4 to 12 hours, for example, 550 ° C. for 8 hours. , 6105 and the semiconductor film 6106 are formed. In addition to nickel (Ni), usable catalyst elements include germanium (Ge), iron (Fe), palladium (Pd), tin (Sn), lead (Pb), cobalt (Co), platinum (Pt). ), Copper (Cu), gold (Au), or the like may be used.
[0306]
The semiconductor film 6106 and the island-shaped semiconductor films 6104 and 6105 contain a catalytic element, and a step (gettering) of removing the catalytic element from the crystalline semiconductor film is performed. For the gettering, a technique described in JP-A-10-135468 or JP-A-10-135469 can be used. Then, as shown in FIG. 35D, phosphorus is added to portions 6107 and 6108 of the semiconductor film 6106 with increased crystallinity, and is 550 to 800 ° C. for 5 to 24 hours in a nitrogen atmosphere, for example, 600 ° C. Heat treatment is performed for 12 hours. Then, the regions 6107 and 6108 to which phosphorus is added function as gettering sites, and nickel existing in the semiconductor film 6106 and the island-shaped semiconductor films 6104 and 6105 can be segregated to the region to which phosphorus is added. Thereafter, the region of the polycrystalline semiconductor film to which phosphorus is added is removed by patterning, so that the concentration of the catalytic element is 1 × 10 6. ¹⁷ atoms / cm ³ Preferably 1 × 10 ¹⁶ atoms / cm ³ An island reduced to a certain extent can be obtained.
[0307]
Next, as shown in FIG. 35E, the gettered island-shaped semiconductor film is patterned to form a sub-island 6109. Then, as shown in FIG. 35F, the crystallinity of the sub-island 6109 is further increased by selective laser light irradiation. Next, the island 6110 is formed by patterning the sub-island 6109 with increased crystallinity.
[0308]
Next, another manufacturing method for making an island using both a catalytic element and laser light will be described with reference to FIGS.
[0309]
First, as illustrated in FIG. 36A, an amorphous semiconductor film is formed over an insulating surface, and the amorphous semiconductor film is etched, whereby island-shaped semiconductor films 6201 and 6202 are formed. Next, as illustrated in FIG. 36B, an amorphous semiconductor film 6203 is formed so as to cover the island-shaped semiconductor films 6201 and 6202. Next, as shown in FIG. 36C, the amorphous semiconductor film 6203 is patterned to form a sub-island, and a nickel acetate salt solution containing 10 ppm of nickel in terms of weight is applied on the sub-island to form a nickel. By forming the inclusion layer and heating by irradiation with laser light, island-shaped semiconductor films 6204 and 6205 with improved crystallinity and a sub-island 6206 are formed. In addition to nickel (Ni), usable catalyst elements include germanium (Ge), iron (Fe), palladium (Pd), tin (Sn), lead (Pb), cobalt (Co), platinum ( Elements such as Pt), copper (Cu), and gold (Au) may be used.
[0310]
The sub-island 6206 and the island-shaped semiconductor films 6204 and 6205 contain a catalytic element, and a process (gettering) for removing the catalytic element from the crystalline semiconductor film is performed.
[0311]
Next, as shown in FIG. 36D, a barrier layer 6207 containing silicon as a main component is formed over the sub-island 6206. Note that the barrier layer 6207 may be an extremely thin layer, and may be a natural oxide film, or may be an oxide film that is oxidized by generating ozone by irradiation of ultraviolet rays in an atmosphere containing oxygen. The barrier layer 6207 may be an oxide film oxidized with a solution containing ozone used for surface treatment called hydro-cleaning performed for removing carbon, that is, organic substances. This barrier layer 6207 is mainly used as an etching stopper. Further, after this barrier layer 6207 is formed, channel doping may be performed, and then activated by irradiating with strong light.
[0312]
Next, a second semiconductor film 6208 is formed over the barrier layer 6207. The second semiconductor film 6208 may be a semiconductor film having an amorphous structure or a semiconductor film having a crystal structure. The thickness of the second semiconductor film 6208 is 5 to 50 nm, preferably 10 to 20 nm. The second semiconductor film 6208 includes oxygen (concentration of 5 × 10 5 in SIMS analysis). ¹⁸ / Cm ³ Or more, preferably 1 × 10 ¹⁹ / Cm ³ It is desirable to improve the gettering efficiency by containing the above.
[0313]
Next, a third semiconductor film (gettering site) 6209 containing a rare gas element is formed over the second semiconductor film 6208. The third semiconductor film 6209 may be a semiconductor film having an amorphous structure using a plasma CVD method, a low pressure thermal CVD method, or a sputtering method, or may be a semiconductor film having a crystal structure. The third semiconductor film may be a semiconductor film containing a rare gas element in the film formation step, or a rare gas element may be added after the formation of the semiconductor film not containing the rare gas element. In this embodiment, the third semiconductor film 6209 containing a rare gas element is formed in the deposition step, and then the rare gas element is selectively added to form the third semiconductor film 6209. (FIG. 36E) Alternatively, the second semiconductor film and the third semiconductor film may be successively formed without exposure to the air. The sum of the thickness of the second semiconductor film and the thickness of the third semiconductor film may be 30 to 200 nm, for example, 50 nm.
[0314]
In this embodiment, the second semiconductor film 6208 separates the sub-island 6206 and the island-shaped semiconductor films 6204 and 6205 from the third semiconductor film (gettering site) 6209. During gettering, impurity elements such as metals existing in the sub-island 6206 and the island-shaped semiconductor films 6204 and 6205 tend to gather near the boundary of the gettering site. It is preferable that the gettering efficiency is improved by separating the gettering site boundary from the sub-island 6206 and the island-like semiconductor films 6204 and 6205 by the semiconductor film 6208. In addition, the second semiconductor film 6208 also has an effect of blocking impurity elements included in the gettering site from diffusing and reaching the interface of the sub-island 6206 during gettering. In addition, the second semiconductor film 6208 also has an effect of protecting the sub island 6206 from being damaged when a rare gas element is added.
[0315]
Next, gettering is performed. As a step of performing gettering, heat treatment may be performed in a nitrogen atmosphere at 450 to 800 ° C. for 1 to 24 hours, for example, at 550 ° C. for 14 hours. Moreover, you may irradiate strong light instead of heat processing. Moreover, you may irradiate strong light in addition to heat processing. Further, the substrate may be heated by injecting heated gas. In this case, heating may be performed at 600 ° C. to 800 ° C., more preferably 650 ° C. to 750 ° C. for 1 to 60 minutes. Time can be shortened. By this gettering, the impurity element moves in the direction of the arrow in FIG. 36F, and the impurity element contained in the sub-island 6206 and the island-shaped semiconductor films 6204 and 6205 covered with the barrier layer 6207 is removed, or The impurity element concentration is reduced. Here, all impurity elements are moved to the third semiconductor film 6209 so as not to segregate into the sub-island 6206 and the island-shaped semiconductor films 6204 and 6205, and the impurity elements contained in the sub-island 6206 and the island-shaped semiconductor films 6204 and 6205 are transferred. Is almost absent, that is, the impurity element concentration in the film is 1 × 10 ¹⁸ / Cm ³ Below, desirably 1 × 10 ¹⁷ / Cm ³ Getter enough to get:
[0316]
Next, after selectively removing only the semiconductor films 6208 and 6209 using the barrier layer 6207 as an etching stopper, an island 6210 having a desired shape is formed on the sub-island 6206 using a known patterning technique. (Fig. 36 (G))
[0317]
In addition, a present Example can be implemented in combination with any one of Example 1- Example 10.
[0318]
(Example 12)
In this embodiment, a structure of a TFT formed using the laser irradiation method of the present invention will be described.
[0319]
The TFT illustrated in FIG. 37A is formed between a channel formation region 7001, a first impurity region 7002 sandwiching the channel formation region 7001, and the first impurity region 7002 and the channel formation region 7001. The active layer includes the second impurity region 7003. A gate insulating film 7004 in contact with the active layer and a gate electrode 7005 formed on the gate insulating film are provided. A sidewall 7006 is formed so as to be in contact with the side surface of the gate electrode.
[0320]
The sidewall 7006 overlaps with the second impurity region 7003 with the gate insulating film 7004 interposed therebetween, and may be conductive or insulating. In the case where the sidewall 7006 has conductivity, the gate electrode including the sidewall 7006 may be used.
[0321]
The TFT illustrated in FIG. 37B is formed between a channel formation region 7101, a first impurity region 7102 sandwiching the channel formation region 7101, and the first impurity region 7102 and the channel formation region 7101. An active layer including the second impurity region 7103 is included. A gate insulating film 7104 in contact with the active layer and a gate electrode formed of two conductive films 7105 and 7106 stacked on the gate insulating film are provided. A sidewall 7107 is formed so as to be in contact with the upper surface of the conductive film 7105 and the side surface of the conductive film 7106.
[0322]
The sidewall 7107 may have conductivity or insulation. In the case where the sidewall 7107 has conductivity, the gate electrode including the sidewall 7107 may be used.
[0323]
The TFT illustrated in FIG. 37C is formed between the channel formation region 7201, the first impurity region 7202 sandwiching the channel formation region 7201, and the first impurity region 7202 and the channel formation region 7201. An active layer including the second impurity region 7203 is included. Then, the gate insulating film 7204 in contact with the active layer, the conductive film 7205 over the gate insulating film, the conductive film 7206 covering the top and side surfaces of the conductive film 7205, and the side surface of the conductive film 7206 are contacted. Sidewalls 7207 are formed. The conductive film 7205 and the conductive film 7206 function as gate electrodes.
[0324]
The sidewall 7207 may be conductive or insulating. In the case where the sidewall 7207 has conductivity, the gate electrode including the sidewall 7207 may be used.
[0325]
In addition, a present Example can be implemented in combination with any one of Example 1- Example 11.
[0326]
(Example 13)
A structure of a pixel of the light emitting device of the present invention will be described with reference to FIG.
[0327]
In FIG. 41, a base film 6001 is formed over a substrate 6000, and a transistor 6002 is formed over the base film 6001. The transistor 6002 includes an active layer 6003, a gate electrode 6005, and a gate insulating film 6004 sandwiched between the active layer 6003 and the gate electrode 6005.
[0328]
The active layer 6003 is preferably a polycrystalline semiconductor film, and the polycrystalline semiconductor film can be formed using the laser irradiation apparatus of the present invention.
[0329]
The active layer may be made of silicon germanium as well as silicon. When silicon germanium is used, the concentration of germanium is preferably about 0.01 to 4.5 atomic%. Further, silicon to which carbon nitride is added may be used.
[0330]
For the gate insulating film 6004, silicon oxide, silicon nitride, or silicon oxynitride can be used. Also, a film in which they are laminated, such as SiO ₂ A film in which SiN is stacked may be used as the gate insulating film. In addition, SiO2
TEOS (Tetraethyl Orthosilicate) and O in plasma CVD method ₂ And a reaction pressure of 40 Pa, a substrate temperature of 300 to 400 ° C., a high frequency (13.56 MHz), and a power density of 0.5 to 0.8 W / cm. ² Was discharged to form a silicon oxide film. The silicon oxide film thus manufactured can obtain good characteristics as a gate insulating film by subsequent thermal annealing at 400 to 500 ° C. Aluminum nitride can be used as the gate insulating film. Aluminum nitride has a relatively high thermal conductivity and can effectively diffuse the heat generated in the TFT. In addition, after forming silicon oxide or silicon oxynitride which does not contain aluminum, a laminate of aluminum nitride may be used as the gate insulating film. Also, SiO formed by RF sputtering using Si as a target. ₂ May be used as a gate insulating film.
[0331]
The gate electrode 6005 is formed using an element selected from Ta, W, Ti, Mo, Al, and Cu, or an alloy material or a compound material containing the element as a main component. Alternatively, a semiconductor film typified by a polycrystalline silicon film doped with an impurity element such as phosphorus may be used. Further, instead of a single conductive film, a conductive film composed of a plurality of layers may be stacked.
[0332]
For example, a combination of forming the first conductive film with tantalum nitride (TaN) and the second conductive film with W, forming the first conductive film with tantalum nitride (TaN), and forming the second conductive film with Ti A combination in which the first conductive film is formed of tantalum nitride (TaN), the second conductive film is formed of Al, the first conductive film is formed of tantalum nitride (TaN), and the second conductive film is formed. It is preferable to form a combination of Cu. Alternatively, a semiconductor film typified by a polycrystalline silicon film doped with an impurity element such as phosphorus, or an AgPdCu alloy may be used as the first conductive film and the second conductive film.
[0333]
The structure is not limited to the two-layer structure, and for example, a three-layer structure in which a tungsten film, an aluminum-silicon alloy (Al-Si) film, and a titanium nitride film are sequentially stacked may be employed. In the case of a three-layer structure, tungsten nitride may be used instead of tungsten, or an aluminum / titanium alloy film (Al—Ti) is used instead of an aluminum / silicon alloy film (Al—Si) film. Alternatively, a titanium film may be used instead of the titanium nitride film.
[0334]
Note that it is important to select an optimum etching method and etchant type depending on the material of the conductive film.
[0335]
The transistor 6002 is covered with a first interlayer insulating film 6006, and a second interlayer insulating film 6007 and a third interlayer insulating film 6008 are stacked over the first interlayer insulating film 6006. .
[0336]
The first interlayer insulating film 6006 can be formed using a single layer or a stack of silicon oxide, silicon nitride, or silicon oxynitride films by a plasma CVD method or a sputtering method. Alternatively, a film in which a silicon oxynitride film with a higher oxygen molar ratio than nitrogen is stacked over a silicon oxynitride film with a higher nitrogen molar ratio than oxygen may be used as the first interlayer insulating film 6006.
[0337]
Note that after the first interlayer insulating film 6006 is formed, heat treatment (heat treatment at 300 to 550 ° C. for 1 to 12 hours) is performed, whereby the active layer 6003 is formed by hydrogen contained in the first interlayer insulating film 6006. It is possible to terminate (hydrogenate) the dangling bonds of the semiconductor contained in the substrate.
[0338]
The second interlayer insulating film 6007 can be formed using non-photosensitive acrylic.
[0339]
As the third interlayer insulating film 6008, a film that hardly transmits a substance that causes deterioration of the light-emitting element such as moisture or oxygen as compared with other insulating films is used. Typically, it is desirable to use, for example, a DLC film, a carbon nitride film, a silicon nitride film formed by an RF sputtering method, or the like.
[0340]
In FIG. 41, reference numeral 6010 denotes an anode, 6011 denotes an electroluminescent layer, 6012 denotes a cathode, and a portion where the anode 6010, the electroluminescent layer 6011, and the cathode 6012 overlap corresponds to the light emitting element 6013. The transistor 6002 is a driving transistor that controls a current supplied to the light-emitting element 6013, and is connected to the light-emitting element 6013 directly or in series via another circuit element.
[0341]
The electroluminescent layer 6011 has a structure in which a light emitting layer alone or a plurality of layers including a light emitting layer are stacked.
[0342]
The anode 6010 is formed on the third interlayer insulating film 6008. An organic resin film 6014 used as a partition is formed over the third interlayer insulating film 6008. The organic resin film 6014 has an opening 6015, and the light emitting element 6013 is formed by overlapping the anode 6010, the electroluminescent layer 6011, and the cathode 6012 in the opening.
[0343]
A protective film 6016 is formed over the organic resin film 6014 and the cathode 6012. Similar to the third interlayer insulating film 6008, the protective film 6016 is a film that hardly transmits a substance that causes deterioration of the light-emitting element such as moisture or oxygen as compared with other insulating films. Typically, it is desirable to use, for example, a DLC film, a carbon nitride film, a silicon nitride film formed by an RF sputtering method, or the like. In addition, the above-described film that hardly transmits a substance such as moisture or oxygen and a film that easily allows a substance such as moisture or oxygen to pass through can be stacked to be used as a protective film.
[0344]
The organic resin film 6014 is heated in a vacuum atmosphere before the electroluminescent layer 6011 is formed in order to remove adsorbed moisture, oxygen, and the like. Specifically, heat treatment is performed in a vacuum atmosphere at 100 ° C. to 200 ° C. for about 0.5 to 1 hour. Desirably 3x10 ^-7 Less than Torr, 3 × 10 if possible ^-8 Most preferably, it should be less than Torr. And when forming an electroluminescent layer after heat-processing to an organic resin film in a vacuum atmosphere, reliability can be improved more by keeping in a vacuum atmosphere until just before film-forming.
[0345]
Further, the end of the organic resin film 6014 in the opening 6015 is rounded so that the electroluminescent layer 6011 formed partially overlapping on the organic resin film 6014 does not have a hole in the end. Is desirable. Specifically, it is desirable that the radius of curvature of the curve drawn by the cross section of the organic resin film in the opening is about 0.2 to 2 μm.
[0346]
With the above structure, coverage of an electroluminescent layer and a cathode to be formed later can be improved, and a short circuit between the anode 6010 and the cathode 6012 in a hole formed in the electroluminescent layer 6011 can be prevented. Further, by relaxing the stress of the electroluminescent layer 6011, defects called “shrink” in which a light emitting region is reduced can be reduced, and reliability can be improved.
[0347]
Note that FIG. 41 illustrates an example in which a positive photosensitive acrylic resin is used as the organic resin film 6014. The photosensitive organic resin includes a positive type in which a portion exposed to energy rays such as light, electrons, and ions is removed, and a negative type in which the exposed portion remains. In the present invention, a negative organic resin film may be used. Alternatively, the organic resin film 6014 may be formed using photosensitive polyimide.
[0348]
When the organic resin film 6014 is formed using negative acrylic, an end portion of the opening 6015 has an S-shaped cross-sectional shape. At this time, it is desirable that the radius of curvature at the upper end and the lower end of the opening is 0.2 to 2 μm.
[0349]
A transparent conductive film can be used for the anode 6010. In addition to ITO, a transparent conductive film in which indium oxide is mixed with 2 to 20% zinc oxide (ZnO) may be used. In FIG. 41, ITO is used as the anode 6010. The anode 6010 may be polished by a CMP method or a polyvinyl alcohol-based porous material by wiping (Berclin cleaning) so that the surface thereof is planarized. Further, after polishing using the CMP method, the surface of the anode 6010 may be subjected to ultraviolet irradiation, oxygen plasma treatment, or the like.
[0350]
The cathode 6012 can be formed using other known materials as long as the conductive film has a low work function. For example, Ca, Al, CaF, MgAg, AlLi, etc. are desirable.
[0351]
Note that FIG. 41 illustrates a structure in which light emitted from the light-emitting element is emitted to the substrate 6000 side; however, a light-emitting element having a structure in which light is directed to the opposite side of the substrate may be used.
[0352]
In FIG. 41, the transistor 6002 and the anode 6010 of the light-emitting element are connected; however, the present invention is not limited to this structure, and the transistor 6002 and the cathode 6001 of the light-emitting element may be connected. In this case, the cathode is formed on the third interlayer insulating film 6008. And it forms using TiN etc.
[0353]
In actuality, when completed up to FIG. 41, packaging with a protective film (laminate film, ultraviolet curable resin film, etc.) or a translucent cover material that is highly airtight and less degassed so as not to be exposed to the outside air ( (Encapsulation) is preferable. At that time, if the inside of the cover material is made an inert atmosphere or if a hygroscopic material (for example, barium oxide) is arranged inside, the reliability of the OLED is improved.
[0354]
Note that the present invention is not limited to the manufacturing method described above, and can be manufactured using a known method. This embodiment can be freely combined with Embodiments 1 to 13.
[0355]
【The invention's effect】
In the present invention, the entire semiconductor film is not scanned and irradiated with the laser beam, but the laser beam is scanned so that at least an indispensable portion can be crystallized at a minimum. With the above structure, it is possible to omit the time for irradiating a portion of the semiconductor film that is removed by patterning after crystallization, and to significantly reduce the processing time per substrate.
[0356]
Also, by superimposing a plurality of laser beams and complementing each other with low energy density portions, the crystallinity of the semiconductor film can be improved more efficiently than using a plurality of laser beams alone without overlapping. it can
[0357]
In the present invention, the case where laser beams emitted from a plurality of laser oscillation apparatuses are combined and used has been described. However, the present invention is not necessarily limited to this configuration. If the output energy of the laser oscillation device is relatively high and a desired energy density can be obtained without reducing the area of the beam spot, it is possible to use only one laser oscillation device. Even in this case, by using the slit, it is possible to shield a portion where the energy density of the laser light is low, and to control the width of the beam spot according to the pattern information.
[Brief description of the drawings]
FIG. 1 is a diagram showing a laser irradiation method of the present invention.
FIG. 2 is a diagram showing a laser beam shape and energy density distribution.
FIG. 3 is a diagram showing a distribution of energy density of a laser beam.
FIG. 4 is a diagram showing a laser beam shape and energy density distribution.
FIG. 5 is a view showing a shape of a laser beam and a positional relationship with a sub island.
FIG. 6 is a diagram illustrating a positional relationship between a laser light irradiation portion and a mask.
FIG. 7 is a diagram illustrating a positional relationship between a laser light irradiation portion and a mask.
FIG. 8 is a diagram showing a positional relationship between a moving direction of laser light and a mask in an object to be processed.
FIG. 9 is a diagram showing a positional relationship between a laser light irradiation portion and a mask.
FIG. 10 is a diagram of a laser irradiation apparatus.
FIG. 11 is a diagram of a laser irradiation apparatus.
FIG. 12 shows a production flow of the present invention.
FIG. 13 shows a production flow of the present invention.
FIG. 14 is a diagram showing a production flow of the present invention.
FIG. 15 is a diagram showing a conventional production flow.
FIG. 16 is a diagram showing a positional relationship between a slit and a beam spot.
FIG. 17 is a diagram of an optical system of a laser irradiation apparatus.
FIG. 18 is a diagram showing a positional relationship between a laser light irradiation portion and a mask.
FIG. 19 is a diagram showing a direction in which laser light moves in an object to be processed.
FIG. 20 is a diagram showing a direction in which laser light moves in an object to be processed.
FIG. 21 is a diagram showing an energy density distribution in a central axis direction of superimposed beam spots.
FIG. 22 is a diagram showing how to superimpose beam spots.
FIG 23 illustrates a method for manufacturing a semiconductor device using a laser irradiation method of the present invention.
FIGS. 24A to 24C illustrate a method for manufacturing a semiconductor device using a laser irradiation method of the present invention. FIGS.
FIGS. 25A and 25B illustrate a method for manufacturing a semiconductor device using a laser irradiation method of the present invention. FIGS.
FIG 26 illustrates a method for manufacturing a semiconductor device using a laser irradiation method of the present invention.
FIG. 27 is a diagram of a liquid crystal display device manufactured using the laser irradiation method of the present invention.
FIGS. 28A and 28B illustrate a method for manufacturing a light-emitting device using the laser irradiation method of the present invention. FIGS.
FIG. 29 is a cross-sectional view of a light-emitting device using the laser irradiation method of the present invention.
FIG. 30 shows a production flow of the present invention.
FIG. 31 shows a method for manufacturing a light-emitting device using the laser irradiation method of the present invention.
FIG. 32 shows a production flow of the present invention.
FIG. 33 is a cross-sectional view of a light-emitting device using the laser irradiation method of the present invention.
34A to 34C are diagrams illustrating a method for manufacturing a semiconductor device using a laser irradiation method of the present invention.
FIG 35 illustrates a method for manufacturing a semiconductor device using a laser irradiation method of the present invention.
36 is a diagram showing a method for manufacturing a semiconductor device using a laser irradiation method of the present invention. FIG.
FIG 37 is a view showing a method for manufacturing a semiconductor device using a laser irradiation method of the present invention.
FIG. 38 is a diagram showing the relationship between the distance between the centers of beam spots and the energy difference.
FIG. 39 is a diagram showing a distribution of output energy in the direction of the central axis of a beam spot.
FIG. 40 is a diagram in which a driving circuit is mounted on a panel.
41 is a cross-sectional view of a light-emitting device manufactured using the laser device of the present invention. FIG.

Claims (9)

From the sub-island pattern information obtained by patterning the semiconductor film formed on the substrate, a specific region to be irradiated with laser light is determined on the substrate so that the sub-island is included with reference to the marker,
A beam spot of a plurality of laser beams output from a plurality of laser oscillation devices is partially overlapped with each other by an optical system to form one beam spot,
Using a slit, limit the width in the direction perpendicular to the scanning direction of the formed beam spot,
By scanning a beam spot with a limited width in the specific region, the crystallinity of the sub-island is increased,
A laser irradiation method, wherein an island is formed by patterning a sub-island having improved crystallinity. From the sub-island pattern information obtained by patterning the semiconductor film formed on the substrate, a specific region to be irradiated with laser light is determined on the substrate so that the sub-island is included with reference to the marker,
A beam spot of a plurality of laser beams output from a plurality of laser oscillation devices is partially overlapped with each other so that each center draws a straight line by an optical system, thereby forming one beam spot.
Using a slit, limit the width in the direction perpendicular to the scanning direction of the formed beam spot,
By scanning a beam spot with a limited width in the specific region, the crystallinity of the sub-island is increased,
A laser irradiation method, wherein an island is formed by patterning a sub-island having improved crystallinity. In claim 1 or claim 2,
The laser irradiation method, wherein a straight line drawn by each center and a moving direction of the substrate are 10 ° or more and 80 ° or less. In claim 1 or claim 2,
A laser irradiation method, wherein a straight line drawn by each center and a direction in which the substrate moves are substantially perpendicular to each other. In any one of Claims 1 thru | or 4,
A laser irradiation method, wherein the laser beam irradiation is performed under a reduced pressure atmosphere or an inert gas atmosphere. 6. The laser beam according to claim 1, wherein the laser beam is a YAG laser, a YVO ₄ laser, a YLF laser, a YAlO ₃ laser, a glass laser, a ruby laser, an alexandride laser, a Ti: sapphire laser, or Y _2. A laser irradiation method characterized in that the light is output using one or more selected from an O ₃ laser. The laser irradiation method according to claim 1, wherein the laser light is continuous wave. 8. The laser irradiation method according to claim 1, wherein the laser beam is a second harmonic. 9. The laser irradiation method according to claim 1, wherein the laser oscillation device is 2 or more and 8 or less.

Images