JP4651772B2 - Laser irradiation device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention reduces the aberration of an optical system at a low cost by a simple method. By using the present invention for a laser optical system for crystallizing a semiconductor film, uniform crystallization can be performed within the substrate surface. The present invention provides a technique that can be easily applied to an optical system of a linear laser crystallization apparatus using a cylindrical lens.
[0002]
[Prior art]
In recent years, an amorphous semiconductor film or a crystalline semiconductor film (a semiconductor film having crystallinity such as polycrystalline or microcrystalline) that is formed over an insulating substrate such as glass, that is, a non-single-crystal semiconductor film is used. On the other hand, a technique for performing laser annealing to crystallize or improve crystallinity has been widely studied. A silicon film is often used as the semiconductor film.
[0003]
A glass substrate is cheaper and more workable than a quartz substrate that has been frequently used in the past, and has an advantage that a large-area substrate can be easily manufactured. For this reason, the above research has been actively conducted. Lasers are preferred for crystallization because the glass substrate has a low melting point. The laser can give high energy only to the non-single-crystal semiconductor film without significantly changing the temperature of the substrate.
[0004]
Since the crystalline silicon film formed by laser annealing has high mobility, a thin film transistor (TFT) is formed using this crystalline silicon film, for example, on a single glass substrate for pixel driving. It is actively used in monolithic liquid crystal electro-optical devices and the like for producing TFTs for driving circuits. Since the crystalline silicon film is made of many crystal grains, it is called a polycrystalline silicon film or a polycrystalline semiconductor film.
[0005]
In addition, a pulsed laser beam with high output, such as an excimer laser, is processed by an optical system so that a square spot of several cm square or a linear shape with a length of 10 cm or more is formed on the surface to be irradiated. The method of performing laser annealing by scanning the beam (moving the laser beam irradiation position relative to the irradiated surface) is preferred because it is mass-productive and industrially superior. .
[0006]
In particular, when a linear laser beam is used, the surface to be irradiated is scanned only in a direction perpendicular to the linear direction of the linear laser beam, unlike the case of using a spot laser beam that requires scanning in the front, rear, left, and right Since the whole can be irradiated with a laser beam, high productivity can be obtained. The reason for scanning in the direction perpendicular to the line direction is that it is the most efficient scanning direction. Due to this high productivity, it is becoming more common for laser annealing to use a linear laser beam obtained by processing a pulsed excimer laser beam with an appropriate optical system.
[0007]
FIGS. 18 and 19 show a linear laser beam forming optical system that forms an image of a laser beam on a substrate using a cylindrical lens. A cylindrical lens and a cylindrical array lens are used in the optical system. As shown in FIG. 22, the cylindrical lens 1201 has a curved surface in the width direction and does not have a curved surface in the length direction. As a result, the outgoing light 1203 is condensed with respect to the incident light 1202 by the refractive effect of the lens in the width direction, but the light is not refracted in the length direction.
[0008]
As for the size of a commercially available linear laser beam, the length 110 in the short direction is 0.2 to 1.0 mm, and the length 111 in the long direction is 100 to 300 mm. In order to obtain such a linear laser beam, a lens design according to geometric optics may be performed. In particular, in an optical system for forming a linear laser, it is necessary to pay attention to aberrations when light is imaged in the short direction in order to converge on a narrow laser beam.
[0009]
The role of each lens shown in FIGS. 18 and 19 will be described below. FIG. 19 (1) shows the optical system of FIG. 18 viewed from the side, and FIG. 19 (2) shows the optical system viewed from the top.
[0010]
FIG. 19 (1) will be described below. Laser light emitted from the laser irradiation apparatus 101 is divided by the cylindrical array lens 102 in the short direction of the linear laser. Here, since four cylindrical lenses are arranged in an array, they are divided into four beams.
[0011]
The laser divided in the short direction passes through the cylindrical lens 103, but the lens is not refracted in the short direction due to the shape of the cylindrical lens 103. The light is incident on the cylindrical lens 106 provided near the substrate by the cylindrical lens 104 having a relatively long focal length. Then, they are combined into one by the cylindrical lens 106 and irradiated onto the irradiated surface 108. Thereby, the energy in the short direction of the linear laser beam is made uniform, and the length in the short direction is determined. Reference numeral 109 denotes a light beam of the laser beam of the optical system.
[0012]
The following describes FIG. 19 (2). The propagation of light imaged in the longitudinal direction of the linear laser will be described. The laser beam is divided into seven beams in the longitudinal direction by the cylindrical array lens 103.
[0013]
The laser divided in the longitudinal direction of the linear laser passes through the cylindrical lens 104, but the lens is not refracted in the longitudinal direction due to the shape of the cylindrical lens 104. The light is incident on the irradiated surface by the cylindrical lens 105 having a long focal length. A light beam of the laser beam of the optical system is indicated by 112.
[0014]
In order to focus the beam in the short direction of the linear laser as shown in FIG. 19A, two sets of lenses such as the cylindrical lenses 104 and 106 are used. That is, the laser beam is condensed at the focal point 113 of the cylindrical lens 104 and becomes a single line. However, the laser beam condensed at the focal point 113 is a linear beam with a short width in the short direction. After being condensed at the focal point 113, the laser light is further divided into four linear lasers and incident on the cylindrical lens 106. Then, after being condensed by the cylindrical lens 106, it spreads and the laser enters the irradiated surface 108. The laser light on the irradiated surface is longer than the linear laser light imaged at the focal point 113 of the cylindrical lens 104.
[0015]
When the longitudinal direction of the linear laser is lengthened, even a large-area substrate can be irradiated uniformly without a laser irradiation seam. However, in order to increase the longitudinal direction of the linear laser beam and at the same time obtain a sufficient laser energy density to crystallize the non-single crystal semiconductor film, the width of the linear laser beam in the short direction must be reduced. Don't be. Usually, the width of the linear laser in the short direction needs to be 0.2 mm to 1.0 mm in relation to the output of the laser.
[0016]
In FIG. 20, doublet cylindrical lenses 201 and 202 are used instead of the cylindrical lens 106 in the optical systems of FIGS. By using two lenses as a condensing lens in combination, the aberration of the lens is remarkably reduced. FIG. 20 (1) is a side view of the optical system, and the laser beam converges in the short direction of the linear laser. FIG. 20 (2) is a top view of the optical system and converges the laser light in the longitudinal direction of the linear laser. The description of reference numerals 101 to 112 in FIG. 20 is the same as those in FIGS.
[0017]
[Problems to be solved by the invention]
For example, a lens made of an acrylic resin can be molded by heating and aspherical. However, a laser lens having a short wavelength is made of quartz having a high melting point, so that aspherical processing is difficult.
[0018]
In an ideal lens, light incident on the lens forms an image at one point regardless of the incident position. However, an actual lens has some error compared to an ideal lens. The amount of error from this ideal lens is called aberration.
[0019]
One of the aberrations caused by spherical lenses is spherical aberration. The spherical aberration is shown in FIG. The figure is a cross-sectional view showing a light beam passing through a lens. The light 1101 incident near the optical axis of the lens 1104, the light 1102 incident near the optical axis, and the light 1103 incident near the end of the lens have different focal points. As a result, the image formed on the irradiated surface 1105 is not fixed at one point but has a spread.
[0020]
In order to prevent spherical aberration, it is necessary to change the radius of curvature of the lens within the lens, but it is very difficult to produce an aspherical lens for a short wavelength.
[0021]
In the shape of the cylindrical lens 106 of FIGS. 18 and 19 and the arrangement in the laser optical system, the main problem is spherical aberration. Since this is a laser optical system, chromatic aberration is not a big problem even if there is an energy distribution depending on the wavelength of the laser beam.
[0022]
In the optical systems as shown in FIGS. 18 and 19, the cylindrical lens 106 constituted by a single lens is used as a condensing lens in the short direction of the linear laser beam. In this optical system, the energy profile in the short direction of the linear laser beam obtained as shown in FIG. 8a has a Gaussian distribution, that is, a non-uniform distribution. In the graph of FIG. 8, the horizontal axis indicates the short direction of the linear laser, and the vertical axis indicates energy.
[0023]
The reason why the energy profile has a Gaussian distribution is due to the aberration of the cylindrical lens 106 in FIGS. The cylindrical lens 106 plays a role of combining laser beams once divided into a plurality of light beams into one on the irradiated surface. However, due to the aberration of the lens, the divided individual rays do not become completely one on the irradiated surface. Thereby, it has an energy profile having a Gaussian distribution having a spread in the short direction.
[0024]
In the optical system shown in FIGS. 18 and 19, the cylindrical lens 104 has a long focal length, so that the aberration of the lens is small. A problem in the optical system is the aberration of the cylindrical lens 106. The laser beam width is practically in the range of 0.2 to 1.0 mm. In order to keep the laser beam in such a range, it is important to suppress the aberration of the cylindrical lens 106.
[0025]
However, when the configuration of the optical system as shown in FIGS. 18 and 19 is adopted, the energy distribution of the linear laser beam becomes non-uniform. Therefore, when the linear laser beam was irradiated to the silicon film while scanning, the laser energy became uneven within the irradiated surface, and the laser irradiation trace remained as a striped pattern on the silicon film.
[0026]
On the other hand, in the optical system as shown in FIG. 20, a doublet cylindrical lens constituted by two cylindrical lenses 201 and 202 is used as a condensing lens. This is an improvement of the defect of the optical system as shown in FIGS. In the doublet cylindrical lens, the spherical aberration of the condensing lens is significantly reduced by combining two cylindrical lenses.
[0027]
In an optical system using a doublet cylindrical lens, the energy profile in the short direction of the obtained linear laser beam is closer to a rectangular distribution. That is, the distribution is more uniform as shown in FIG. An optical system for forming a linear laser beam that is generally used at present is extremely close to the configuration shown in FIG. When the entire silicon film is crystallized by irradiating the silicon film with the obtained linear laser beam while scanning, the laser irradiation trace is less likely to remain on the silicon film, and the polycrystal is more uniform in the plane. A silicon film is obtained.
[0028]
However, the configuration using the doublet cylindrical lens makes the laser optical system expensive because two sets of cylindrical lenses are used. In order to adjust the optical axis, it is necessary to adjust the height and the elevation angle of the two cylindrical lenses. Therefore, a desired beam can be obtained only after adjustment by a highly skilled worker.
[0029]
As described above, when the cylindrical lens 106 is used for condensing the laser beam as shown in FIGS. 18 and 19, the cylindrical lens is inexpensive, but the energy distribution of the linear laser becomes non-uniform due to lens aberration. When the silicon film was crystallized, the uneven energy distribution appeared to be uneven, and the laser irradiation traces remained on the silicon film as a striped pattern.
[0030]
When the doublet cylindrical lens 201 is used for condensing a laser beam as shown in FIG. 20, the optical system becomes expensive and it is difficult to align the optical axes of the two lenses.
[0031]
[Means for Solving the Problems]
The features of the present invention are shown in FIG. FIG. 5 is a sectional view showing a light beam passing through the lens. The feature of the present invention is that the lens is divided into individual lenses 501 to 503, and the height of each lens from the irradiated surface 507 is changed. Height refers to the distance between the rear surface of the lens, that is, the surface from which light is emitted and the irradiated surface. Incident light is shown at 504-506. Lights 504 to 506 incident on the individual lenses 501 to 503 are condensed before the irradiated surface, and then spread and enter the irradiated surface 507. Compared to the lens 501 near the optical axis, the lenses 502 and 503 farther from the optical axis are closer to the irradiated surface 507. Thereby, the aberration of the spherical lens is reduced, and the spread of the light incident on the lenses 501 to 503 on the irradiated surface is suppressed. The six beams collected on the surface to be irradiated have substantially overlapping edges. The present invention is effective when the divided beams are incident on the lenses 501 to 503.
[0032]
An example in which the lens of the present invention is used in a laser optical system is shown in FIG. The optical system of FIG. 1 is characterized in that a cylindrical lens 106 as a condensing lens is divided into a plurality of planes parallel to the generatrix and parallel to the optical axis. FIG. 1 illustrates an optical system for condensing light in a short direction of a linear laser, and is compared with FIG. 19 (1) of the conventional example. One piece of the divided lens will be referred to as divided cylindrical lenses 203 and 204, respectively. By dividing the cylindrical lens and changing the distance from the irradiated surface, the light that has passed through each cylindrical lens is condensed into an elongated line. If the micrometer is used for the mechanism for moving the lens, the adjustment becomes easy.
[0033]
Since the distance between the laser beams incident on the cylindrical lens 106 of the optical system in FIGS. 18 and 19 is sufficiently large, the lens can be easily divided in consideration of the incident position of the laser beam.
[0034]
For dividing the lens, it is preferable to use a scriber that cuts the glass by rotating a diamond stone or carbide stone wheel on the glass surface.
[0035]
A linear laser beam enters the split cylindrical lens one by one. In the condensing lens shown in FIG. 1, two laser beams are incident on the central lens, but it is understood that this is sufficient in view of the symmetry of the system.
[0036]
When the number of beams to be divided by the cylindrical array lens 102 is an odd number, only one beam is incident on the central lens of the condensing lens.
[0037]
By individually adjusting the divided lenses, the energy profile in the short direction of the obtained linear laser beam can be changed. For example, one of the divided lenses 301 is moved in the direction of the arrow in FIG. The laser beam that has passed through the lens changes its beam width on the surface to be irradiated, and at the same time, its imaging position moves in the beam width direction. By utilizing this property and adjusting the height of each of the divided lenses, the laser beam can be imaged while suppressing the spread, and the profile of the laser beam is as shown in FIG. 8c. be able to.
[0038]
The profile of the laser beam in FIG. 8c has a slight energy distribution in the irradiated surface, and is deviated from an ideal rectangular energy profile. However, the energy homogeneity of the laser beam is improved as compared with that using the cylindrical lens 106 shown in FIGS. However, the energy homogeneity is still poor compared to the energy profile of FIG. 8b in the optical system using the doublet cylindrical lens as shown in FIG.
[0039]
Another embodiment of the present invention that further improves energy homogeneity is shown in FIG. The optical system of FIG. 2 is characterized in that the overlapping of the beams on the irradiated surface is made more consistent by making the focal lengths of the divided condensing lenses different from each other. As a method of obtaining divided lenses having different focal lengths, there is a method of dividing and combining cylindrical lenses having different curvature radii. The focal length of the divided lens is indicated by the focal length of the spherical lens before the division.
[0040]
The divided cylindrical lenses 205, 206, and 207 shown in FIG. 2 have different focal lengths, and the central lens has a larger radius of curvature and a longer focal length. Further, the lens at the end has a shorter radius of curvature and a shorter focal length. The lens with the shorter focal length is closer to the irradiated surface 108. If the micrometer is used for the mechanism for moving the lens, the adjustment becomes easy.
[0041]
Thereby, the homogeneity of the beam is greatly improved. This uniformity is better than the optical system of FIG.
[0042]
The configuration of the present invention is particularly effective for a linear laser beam optical system. Since the distance between the laser beams incident on the cylindrical lens 106 of FIGS. 18 and 19 is sufficiently large, it is possible to easily process the lens in consideration of the incident position of the laser beam. The present invention is easier to apply than an optical system in which light is incident on the entire lens surface.
[0043]
In the present invention, a spherical lens is divided to reduce spherical aberration. The present invention is effective for a lens made of a material having a high melting point, which is difficult to process aspherically. Further, it is effective for an optical system in which individual beams are divided and incident on a lens.
[0044]
The present invention can be applied not only to a cylindrical lens that forms linear light but also to reduce spherical aberration of a lens that forms point light, such as an objective lens of a microscope.
[0045]
This will be described with reference to FIGS. First, as shown in the top view of FIG. 6A, the lens may be cut along planes orthogonal to each other. In FIG. 6, a plano-convex lens 601 made of quartz having a constant curvature radius is divided. The plano-convex lens 601 includes two scribe lines 603 in the vertical direction and two in the horizontal direction.
[0046]
A method for forming a split beam is shown in FIG. Laser light 610 is emitted from the light source 609. Then, a cylindrical array lens 607 in which three cylindrical lenses are arranged in an array and a cylindrical array lens 608 in which three cylindrical lenses are arranged in an array are combined in an orthogonal direction. As a result, the beam is divided into nine laser beams 602 shown in FIG.
[0047]
The plano-convex lens divided as shown in the cross-sectional view of FIG. 6B is arranged at a height closer to the irradiated surface as the incident position of the beam is away from the optical axis of the lens. In FIG. 6 (2), numbers are shown for each lens fragment. However, the closer the position of the laser beam 602 incident to each lens fragment is from the optical axis, the larger the number indicated for the lens fragment. That is, the numbers are relative comparisons of the height 605 from the irradiated surface 604, and the smaller the number, the closer to the irradiated surface. The height here refers to the distance between the rear surface of the lens, that is, the surface from which light is emitted and the irradiated surface.
[0048]
6, the edge of the laser beam incident on the irradiated surface 604 substantially overlaps, and the spread of the laser beam on the irradiated surface can be suppressed.
[0049]
The present invention is effective not only for plano-convex lenses but also for biconvex lenses, convex meniscus lenses, biconcave lenses, plano-concave lenses, and concave meniscus lenses. In any lens, the individual beams need to be split and incident on the lens.
[0050]
The present invention is effective not only for an optical system using a lens but also for an optical system using a reflecting mirror such as a convex mirror and a concave mirror. In either case, the individual beams need to be split and incident on the lens.
[0051]
The divided lens of the present invention may be adjusted not only in the vertical direction but also in the horizontal direction and the diagonal direction so that the aberration is reduced.
[0052]
The present invention is not applied only to a laser optical system. In an optical system in which white light is incident, chromatic aberration occurs due to wavelength dispersion of the refractive index of the lens, but geometric spherical aberration can be reduced. As for chromatic aberration, it is preferable to achromatize by attaching concave and convex lenses having different refractive index dispersions.
[0053]
The present invention can reduce not only spherical aberration but also coma and astigmatism. In this case, the arrangement of the divided individual lenses is asymmetric with respect to the optical axis.
[0054]
DETAILED DESCRIPTION OF THE INVENTION
[Example 1]
In this embodiment, an example of reducing spherical aberration of a spherical lens by dividing and combining cylindrical lenses having different focal lengths is shown. The optical system was based on that shown in FIG.
[0055]
In this example, L3308, XeCl excimer laser device manufactured by Lambda Fujisix was used as the laser irradiation device 300. The specifications of the laser irradiation apparatus are as follows. Pulse laser, maximum oscillation frequency 300Hz, pulse width, 35ns, maximum energy 670mJ / pulse, maximum energy, 200W. The beam size is 12 × 35 mm square at the laser exit.
[0056]
Since the beam size emitted from the laser irradiation apparatus is 12 × 35 mm, it is necessary to design the optical system according to the size.
[0057]
Of the optical system used in this embodiment, FIG. 3a is a diagram showing a schematic diagram of a lens acting in the longitudinal direction of the linear laser beam, and FIG. 3b is a diagram showing a schematic diagram of a lens acting in the short direction of the linear laser beam. It is. There are cylindrical lenses 3061 and 3062 divided near the irradiated surface.
[0058]
The role, arrangement, and size of each lens of the optical system shown in FIG. 3 will be described below. The following lenses are all plano-convex lenses, and all have a curved surface in the laser incident direction except for the cylindrical lens 305. The orientation of these lenses does not have to be as described above. However, if the orientation of the lenses is different from that of the present embodiment, the effects disclosed by the present invention can be obtained unless the distance between the lenses is changed. It may not be possible. The curved surfaces of all lenses are spherical. The definition of the size of the cylindrical lens is unified as shown in FIG. 22, the length of one piece of the cylindrical lens arranged in an array is width (L), the depth direction is length (W), and the thickness of the cylindrical lens ( H). All the lenses are cylindrical lenses, and have a curvature in the width direction.
[0059]
In the cylindrical array lens 301, four cylindrical lenses having a focal length of 300 mm are arranged in an array. Width (L ₁ ) Is 3 mm each. Cylindrical array lens length (W ₁ ) Is 50mm, thickness (H ₁ ) Is 3 mm.
[0060]
In the cylindrical array lens 302, seven cylindrical lenses having a focal length of 72 mm are arranged in an array. Width (L ₂ ) Is 7mm each and length (W ₂ ) Is 50 mm. Lens thickness (H ₂ ) Is 3 mm.
[0061]
In the cylindrical array lens 303, four cylindrical lenses having a focal length of 450 mm are arranged in an array. Width (L _Three ) Is 3mm each and length (W _Three ) Is 50mm, thickness (H _Three ) 3 mm.
[0062]
The cylindrical lens 304 has a focal length of 1680 mm and a width (L _Four ) 50mm, length (W _Four ) 50mm, thickness (H _Four ) 5 mm. By providing a curved surface on the opposite side to the laser incident direction, the light incident on the cylindrical lens 304 spreads in the longitudinal direction of the linear beam.
[0063]
The cylindrical lens 305 has a focal length of 375 mm and a width (L _Five ) 50mm, length (W _Five ) 50mm, thickness (H _Five ) 5 mm. This lens acts in the short direction of the linear beam. By providing a curved surface in the incident direction of the laser, the light incident on the cylindrical lens 304 is collected at the focal point 307 and becomes a single line.
[0064]
As the distance further advances, the light condensed at the focal point 307 is divided into individual linear beams and enters the divided cylindrical lenses 3061 and 3062. Since the divided cylindrical lens is located about 1000 mm away from the focal point of the cylindrical lens 305, the distance between the individual laser beams is widened.
[0065]
The divided cylindrical lens 306 has a focal length of 185 mm and a width (L ₆ ) 15mm, length (W ₆ ) 160mm, thickness (H ₆ ) 20 mm. The lenses 3062 at both ends have a focal length of 173 mm and a width of 20 mm (W ₇ ), 160mm in length (L ₇ ), Thickness (H ₇ ) 20 mm. Further, in the lenses 3062 at both ends, the centers of curvature of the left and right lenses coincide with each other. By providing lenses with different focal lengths at different heights, the divided laser beams are focused and then irradiated linearly, but the spread is suppressed. The height here refers to the distance between the rear surface of the lens, that is, the surface from which light is emitted and the irradiated surface 108. The distance between the rear surface of the central lens 3061 of the divided cylindrical lens 306 and the rear surfaces of the lenses 3062 at both ends of the divided cylindrical lens 306 is 23 mm. The height and focal length of the split cylindrical lens were optimized by calculation.
[0066]
By the action of the divided cylindrical lens 306, an elongated laser beam is formed as compared with the linear laser formed at the focal point 307 of the cylindrical lens 304.
[0067]
The distance between the lens rear surfaces at both ends of the divided cylindrical lens 306 and the irradiated surface 108 is 192.5 mm.
[0068]
The distance between the cylindrical array lens 301 and the cylindrical array lens 302 is 317 mm.
[0069]
The distance between the cylindrical array lens 302 and the cylindrical array lens 303 is 122 mm.
[0070]
The distance between the cylindrical array lens 303 and the cylindrical lens 304 is 1 mm.
[0071]
The distance between the cylindrical lens 304 and the cylindrical lens 305 is 81 mm.
[0072]
The distance between the cylindrical lens 305 and the center lens 3061 of the divided cylindrical lens 306 is 1377 mm.
[0073]
The distance between the lenses described above is the shortest distance between the rear surface of the lens arranged before the optical path and the front surface of the lens arranged behind the optical path. Further, when it is necessary to insert a mirror between the lenses due to the arrangement of the optical system, the lens arrangement may be changed according to geometric optics.
[0074]
In addition, since the above-mentioned distance varies depending on the optical system creation accuracy and disposition, actual optical adjustment may be performed by placing a CCD camera or the like on the irradiated surface 108 and viewing the beam.
[0075]
The linear laser beam processed with the above configuration has very high homogeneity on the irradiated surface. The linear laser beam has a length of 145 mm and a width of 0.6 mm.
[0076]
[Example 2]
In this embodiment, an example in which an amorphous silicon film formed on a glass substrate is crystallized using the linear laser beam of Embodiment 1 will be described.
[0077]
As the substrate, a 1737 substrate manufactured by Corning, Inc. having a 5 inch square is used. On the substrate, SiO 2 is formed by plasma CVD. ₂ A film is formed to 200 nm. Thereafter, an amorphous silicon film is continuously formed to a thickness of 50 nm.
[0078]
Thereafter, the substrate is heated to 500 degrees to reduce hydrogen in the amorphous silicon film. Thereby, the laser resistance of the film can be increased.
[0079]
An apparatus for irradiating the substrate with laser is shown in FIG. Laser light emitted from the laser irradiation apparatus 300 first enters the optical system 401. The optical system 401 includes lenses 301 to 305 shown in FIG. The light emitted from the optical system 401 is bent vertically downward by the mirror 402 and irradiated onto the substrate 403 via the divided cylindrical lens 306.
[0080]
The stage 404 is disposed in parallel to the surface to be irradiated with the linear laser beam, and the substrate 403 can be disposed thereon. The surface of the substrate 403 disposed on the stage 404 is focused on the linear laser beam. The stage 404 is designed to move by a moving mechanism 405 in a direction perpendicular to the length direction of the linear laser beam. There should be adequate friction between the substrate and the stage so that the substrate does not move on the stage while the stage is moving.
[0081]
By adjusting the output of the laser irradiation apparatus 300, the energy density of the laser beam on the irradiated surface is controlled, and the optimum energy for crystallizing the amorphous silicon film is selected.
[0082]
The optimum laser oscillation output of the lambda laser irradiation apparatus used in this embodiment is 15 to 16 keV. However, when the amorphous silicon film is irradiated with a linear laser beam with the above output, the output may be too strong. At that time, for example, a neutral density filter is inserted between the laser irradiation apparatus 101 and the optical system 401 to adjust to an appropriate output.
[0083]
The neutral density filter is preferably one that can continuously change the neutral density. Specifically, a mechanism that changes the angle of the plate by inserting the plate into the laser beam path using a plate whose transmittance varies depending on the incident angle may be provided. The practitioner may determine the dimming rate.
[0084]
In this embodiment, the energy density on the irradiated surface of the linear laser beam is 300 to 450 mJ / cm. ² For example, 400 mJ / cm ² The moving speed of the stage was 1 to 4 mm / sec, for example 1.8 mm / sec. The laser oscillation frequency was 30 Hz. At this time, focusing on one point on the surface of the amorphous silicon film, the laser beam is irradiated 10 times. As described above, it is preferable to irradiate the amorphous silicon film with a multi-pulse laser because fluctuations in the laser output are averaged.
[0085]
[Example 3]
In the present invention, a semiconductor layer is irradiated with a linear laser beam by an optical system using a divided cylindrical lens to crystallize an active layer. A method for manufacturing an active matrix substrate using low-temperature polysilicon as an active layer using the linear laser beam optical system of the present invention will be described below with reference to FIGS. An optical system for forming a linear laser will be described with reference to FIGS.
[0086]
First, as shown in FIG. 9A, a silicon oxide film on a substrate 2001 made of glass such as barium borosilicate glass represented by Corning # 7059 glass or # 1737 glass, or aluminoborosilicate glass, A base film 2002 made of an insulating film such as a silicon nitride film or a silicon oxynitride film is formed. For example, SiH by plasma CVD method _Four , NH _Three , N ₂ A silicon oxynitride film 2002a made of O is formed to 10 to 20 nm (preferably 50 to 100 nm) and similarly SiH _Four , N ₂ A silicon oxynitride film 2002b formed from O is stacked to a thickness of 50 to 20 nm (preferably 100 to 150 nm). Although the base film 2002 is shown as a two-layer structure in this embodiment, it may be formed by a single layer film of the insulating film or a stack of two or more layers.
[0087]
The island-shaped semiconductor layers 2003 to 2006 and 2057 are formed using a crystalline semiconductor film in which a semiconductor film having an amorphous structure is formed using a laser crystallization method or a thermal crystallization method. The island-like semiconductor layers 2003 to 2006 are formed with a thickness of 25 to 80 nm (preferably 30 to 60 nm). There is no limitation on the material of the crystalline semiconductor film, but the crystalline semiconductor film is preferably formed of silicon or a silicon germanium (SiGe) alloy.
[0088]
In order to produce a crystalline semiconductor film by a laser crystallization method, a gas laser represented by a pulse oscillation type or a continuous emission type excimer laser, a YAG laser, a YVO, etc. _Four A solid laser typified by a laser is used. In the case of using these lasers, it is preferable to use a method in which laser light emitted from a laser oscillator is condensed into a linear shape, a rectangular shape, or a rectangular shape by an optical system and irradiated onto a semiconductor film. The conditions for crystallization are appropriately selected by the practitioner. When an excimer laser is used, the pulse oscillation frequency is 30 Hz and the laser energy density is 100 to 400 mJ / cm. ² (Typically 200-300mJ / cm ² ). When a YAG laser is used, the second harmonic is used and the pulse oscillation frequency is 1 to 10 kHz, and the laser energy density is 300 to 600 mJ / cm. ² (Typically 350-500mJ / cm ² ) Then, a laser beam condensed in a linear shape with a width of 100 to 1000 μm is irradiated over the entire surface of the substrate, and the superposition ratio (overlap ratio) of the linear laser light at this time is set to 80 to 98%.
[0089]
In this embodiment, a linear laser is irradiated by the optical system shown in the first and second embodiments. As the laser irradiation conditions, a XeCl excimer laser was used in the same manner as in Example 1. The maximum oscillation frequency is 300 Hz, the pulse width is 35 nsec, the maximum energy is 670 mJ / pulse, and the maximum energy is 200 W.
[0090]
Laser irradiation is performed with the same lens arrangement as that shown in FIG. As a result, the four beams divided by the cylindrical array lens 301 are incident on the divided cylindrical lens 306. When the divided beams reach the irradiated surface, the edges of the beams overlap and the substrate is irradiated with laser light having a uniform energy distribution. With the lens arrangement disclosed in the first embodiment, a laser beam condensed linearly with a width of 600 μm in the short direction can be obtained. As shown in FIG. 4, the substrate 403 is scanned in the short direction of the linear laser, that is, in the direction of the arrow in FIG. When the crystallized substrate is visually observed, a good crystal state in which vertical stripes after laser irradiation are not noticeable can be obtained.
[0091]
The gate insulating film 2007 is formed of an insulating film containing silicon with a thickness of 40 to 150 nm by using a plasma CVD method or a sputtering method. In this embodiment, a silicon oxynitride film is formed with a thickness of 120 nm. Needless to say, the gate insulating film is not limited to such a silicon oxynitride film, and another insulating film containing silicon may be used as a single layer or a stacked structure. For example, when a silicon oxide film is used, TEOS (Tetraethyl Orthosilicate) and O 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 subsequent thermal annealing at 400 to 500 ° C.
[0092]
Then, a first conductive film 2008 and a second conductive film 2009 for forming a gate electrode are formed over the gate insulating film 2007. In this embodiment, the first conductive film 2008 is formed with Ta to a thickness of 50 to 100 nm, and the second conductive film is formed with W to a thickness of 100 to 300 nm.
[0093]
The Ta film is formed by sputtering, and a Ta target is sputtered with Ar. In this case, when an appropriate amount of Xe or Kr is added to Ar, the internal stress of the Ta film can be relieved and peeling of the film can be prevented. The resistivity of the α-phase Ta film is about 20 μΩcm and can be used for the gate electrode, but the resistivity of the β-phase Ta film is about 180 μΩcm and is not suitable for the gate electrode. In order to form an α-phase Ta film, tantalum nitride having a crystal structure close to Ta's α-phase is formed on a Ta base with a thickness of about 10 to 50 nm, so that an α-phase Ta film can be easily obtained. be able to.
[0094]
When forming a W film, it is formed by sputtering using W as a target. In addition, tungsten hexafluoride (WF ₆ It can also be formed by a thermal CVD method using In any case, it is necessary to reduce the resistance in order to use it as a gate electrode, and it is desirable that the resistivity of the W film be 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 W, crystallization is hindered and the resistance is increased. Therefore, in the case of sputtering, the resistivity is obtained by using a W target with a purity of 99.9999% and forming a W film with sufficient consideration so that impurities are not mixed in the gas phase during film formation. 9-20 μΩcm can be realized.
[0095]
Next, as shown in FIG. 9B, resist masks 2010 to 2013 are formed, and a first etching process for forming a gate electrode is performed. Although there is no limitation on the etching method, it is preferable to use ICP (Inductively Coupled Plasma) etching method and CF as the etching gas. _Four And Cl ₂ Are mixed, and 500 W of RF (13.56 MHz) power is applied to the coil-type electrode at a pressure of 0.5 to 2 Pa, preferably 1 Pa, to generate plasma. 100 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 When W is mixed, the W film and the Ta film are etched to the same extent.
[0096]
Under the above etching conditions, by making the shape of the resist mask suitable, the end portions of the first conductive layer and the second conductive layer are tapered due to the effect of the bias voltage applied to the substrate side. The angle of the tapered portion is 15 to 45 °. 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%. Since the selection ratio of the silicon oxynitride film to the W film is 2 to 4 (typically 3), the surface where the silicon oxynitride film is exposed is etched by about 20 to 50 nm by the over-etching process. Thus, the first shape conductive layers 2014 to 2017 (the first conductive layers 2014a to 20017a and the second conductive layers 2014b to 2017b) formed of the first conductive layer and the second conductive layer by the first etching treatment. Form. Reference numeral 2054 denotes a gate insulating film. A region which is not covered with the first shape conductive layers 2014 to 2017 is etched and thinned by about 20 to 50 nm.
[0097]
Then, an impurity element imparting n-type is added by performing a first doping process. The doping method may be an ion doping method or an ion implantation method. The condition of the ion doping method is a dose of 1 × 10 ¹³ ~ 5x10 ¹⁴ atoms / cm ² The acceleration voltage is set to 60 to 100 keV. 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 2014 to 2017 serve as a mask for the impurity element imparting n-type, and the first impurity regions 2018 to 2021 and 2055 are formed in a self-aligning manner. The first impurity regions 2018 to 20021 and 2055 have 1 × 10 ²⁰ ~ 1x10 ^{twenty one} atomic / cm ^Three An impurity element imparting n-type is added in a concentration range of.
[0098]
Next, a second etching process is performed as shown in FIG. Similarly, using the ICP etching method, the etching gas is CF. _Four And Cl ₂ And O ₂ And 500 W of RF power (13.56 MHz) is supplied to the coil-type electrode at a pressure of 1 Pa to generate plasma. 50 W RF (13.56 MHz) power is applied to the substrate side (sample stage), and a lower self-bias voltage is applied than in the first etching process. Under such conditions, the W film is anisotropically etched, and Ta, which is the first conductive layer, is anisotropically etched at a slower etching rate to conduct the second shape conductive layers 2022 to 2025 (first Conductive layers 2022a to 2025a and second conductive layers 2022b to 2025b) are formed. Reference numeral 2026 denotes a gate insulating film, and a region not covered with the second shape conductive layers 2022 to 2025 is further etched by about 20 to 50 nm to form a thinned region.
[0099]
CF of W film and Ta film _Four And Cl ₂ The etching reaction by the mixed gas can be estimated from the generated radicals or ion species and the vapor pressure of the reaction product. Comparing the vapor pressure of fluoride and chloride of W and Ta, WF, which is fluoride of W ₆ Is extremely high, other WCl _Five , TaF _Five , TaCl _Five Are comparable. Therefore, CF _Four And Cl ₂ With this mixed gas, both the W film and the Ta film are etched. However, an appropriate amount of O is added to this mixed gas. ₂ When CF is added _Four And O ₂ Reacts to CO and F, and a large amount of F radicals or F ions are generated. As a result, the etching rate of the W film having a high fluoride vapor pressure is increased. On the other hand, the increase in etching rate of Ta is relatively small even when F increases. Further, since Ta is more easily oxidized than W, O ₂ When Ta is added, the surface of Ta is oxidized. Since the Ta oxide does not react with fluorine or chlorine, the etching rate of the Ta film further decreases. Therefore, it is possible to make a difference in the etching rate between the W film and the Ta film, and the etching rate of the W film can be made larger than that of the Ta film.
[0100]
Then, a second doping process is performed as shown in FIG. In this case, an impurity element which imparts n-type is doped under a condition of a lower acceleration amount and a higher acceleration voltage than in the first doping treatment. For example, the acceleration voltage is 70 to 120 keV and 1 × 10 ¹³ /cm ² A new impurity region is formed inside the first impurity region formed in the island-shaped semiconductor layer in FIG. 9B. Doping is performed using the second shape conductive layers 2022 to 2025 as masks against the impurity elements so that the impurity elements are also added to the lower regions of the second conductive layers 2022a to 2025a. In this manner, third impurity regions 2032 to 2036 overlapping with the second conductive layers 2022a to 2025a and second impurity regions 2027 to 2031 between the first impurity region and the third impurity region are formed. The impurity element imparting n-type conductivity is 1 × 10 6 in the second impurity region. ¹⁷ ~ 1x10 ¹⁹ atoms / cm ^Three 1 × 10 in the third impurity region. ¹⁶ ~ 1x10 ¹⁸ atoms / cm ^Three So that the concentration becomes.
[0101]
Then, as shown in FIG. 10B, fourth impurity regions 2037 to 2039 having a conductivity type opposite to the one conductivity type are formed in the island-shaped semiconductor layer 2004 for forming the p-channel TFT. Using the second conductive layer 2023 as a mask for the impurity element, an impurity region is formed in a self-aligning manner. At this time, the island-like semiconductor layers 2003, 2005, and 2006 forming the n-channel TFT are covered with resist masks 2040 to 2042 over the entire surface. Phosphorus is added to the impurity regions 2037 to 2039 at different concentrations, but diborane (B ₂ H ₆ ) And an impurity concentration of 2 × 10 6 in any region. ²⁰ ~ 2x10 ^{twenty one} atoms / cm ^Three To be.
[0102]
Through the above steps, impurity regions are formed in each island-like semiconductor layer. The first conductive layers 2022 to 2025 function as a gate electrode and a gate wiring.
[0103]
Thus, for the purpose of controlling the conductivity type, a step of activating the impurity element added to each island-like semiconductor layer is performed as shown in FIG. A laser annealing method can be applied to this step.
[0104]
In laser annealing, excimer laser light with a wavelength of 400 nm or less, YAG laser, YVO _Four The second harmonic of the laser (532 nm) is used. The activation conditions are appropriately selected by the practitioner. When an excimer laser is used, the pulse oscillation frequency is 30 Hz and the laser energy density is 100 to 300 mJ / cm. ² And When a YAG laser is used, the second harmonic is used and the pulse oscillation frequency is 1 to 10 kHz, and the laser energy density is 200 to 400 mJ / cm. ² And good. Then, a laser beam condensed linearly with a width of 100 to 1000 μm, for example 600 μm, is irradiated over the entire surface of the substrate, and the superposition ratio (overlap ratio) of the linear laser light at this time is 80 to 98%.
[0105]
When the optical system shown in FIG. 3 is used to form a linear laser, the energy distribution of the linear laser on the irradiated surface 108 when the laser light divided by the cylindrical lens 301 is condensed on the substrate is obtained. Can be uniform. In this embodiment, a linear laser beam is irradiated with the lens arrangement of the optical system shown in the first and second embodiments. As the laser irradiation conditions, a XeCl excimer laser was used in the same manner as in Example 1.
[0106]
As a result, the four beams divided by the cylindrical array lens 301 in FIG. 3 are incident on the divided cylindrical lens 306. With the lens arrangement disclosed in the first embodiment, a laser beam condensed linearly with a width of 600 μm in the short direction can be obtained. As shown in FIG. 4, the substrate 403 is scanned in the short direction of the linear laser, that is, in the direction of the arrow in FIG. Since the energy distribution of the laser is uniform, the activation of impurities can be made uniform.
[0107]
Further, a heat treatment is performed at 300 to 450 ° C. for 1 to 12 hours in an atmosphere containing 3 to 100% hydrogen to perform a step of hydrogenating the island-shaped semiconductor layer. This step is a step of terminating dangling bonds in the semiconductor layer with thermally excited hydrogen. As another means of hydrogenation, plasma hydrogenation (using hydrogen excited by plasma) may be performed.
[0108]
Further, a capacitor electrode 2053 is formed. The capacitor electrode 2053 may be manufactured in the step of FIG. Then, the gate electrode and the capacitor electrode can be manufactured with one mask. As a result, a storage capacitor is formed between the capacitor electrode and the n-type doped active layer 2055.
[0109]
In FIG. 11, the first interlayer insulating film 2043 is formed with a thickness of 100 to 200 nm from a silicon oxynitride film. A second interlayer insulating film 2044 made of an organic insulating material is formed thereon. The second interlayer insulating film 2043 is formed with an average film thickness of 1.0 to 2.0 μm. As the organic insulating material, polyimide, acrylic, polyamide, polyimide amide, BCB (benzocyclobutene), or the like can be used. For example, when using a type of polyimide that is thermally polymerized after being applied to the substrate, it is formed by baking at 300 ° C. in a clean oven. When acrylic is used, a two-component type is used, and after mixing the main material and the curing agent, applying the entire surface of the substrate using a spinner, preheating at 80 ° C. for 60 seconds with a hot plate. It can be formed by baking at 250 ° C. for 60 minutes in a clean oven.
[0110]
Then, source wirings 2045 to 2047 that form contacts with the source region of the island-shaped semiconductor layer and drain wirings 2048 to 2050 that form contacts with the drain region are formed in the driver circuit.
[0111]
In the pixel portion, a source wiring 2051 and a pixel electrode 2052 are formed. The wiring formed on the second interlayer insulating film 552 is formed of, for example, a 50 to 200 nm Ti film and a 100 to 300 nm Al film. The source wirings 2045 to 2047 and 2048, the drain wirings 2048 to 2050, and the pixel electrode 2052 formed in such a configuration are connected to the source or drain region of the TFT through a contact hole formed in the second interlayer insulating film. A contact is formed with a Ti film to prevent Al and the semiconductor from being in direct contact with each other, thereby improving the reliability of the contact portion.
[0112]
As described above, a driver circuit including an n-channel TFT 3001, a p-channel TFT 30002, and an n-channel TFT 3003, and a pixel portion including the pixel TFT 30004 and the storage capacitor 30005 can be formed over the same substrate. In this specification, such a substrate is referred to as an active matrix substrate for convenience.
[0113]
AA ′ in FIG. 12 in the top view of the pixel portion of the active matrix substrate manufactured in this example corresponds to the AA ′ line shown in FIG. In the pixel TFT 3004, the gate electrode 2025 that also serves as a gate wiring intersects the island-like semiconductor layer 2008 below through a gate insulating film (not shown). Although not shown, a source region, a drain region, and an LDD region are formed in the island-shaped semiconductor layer. Reference numeral 5001 denotes a contact portion between the source wiring 2051 and the source region, and reference numeral 5002 denotes a contact portion between the pixel electrode 2052 and the drain region. The storage capacitor 5003 is formed in a region where the capacitor wiring 2053 overlaps with the semiconductor layer extending from the drain region of the pixel TFT 3004 and the gate insulating film.
[0114]
In this embodiment, since the crystallization can be made uniform by the linear laser, the variation in characteristics of the switching elements in the substrate surface due to the unevenness of the laser irradiation can be suppressed. Further, the optical system in which the cylindrical lens is divided and the lens aberration is reduced as in this embodiment is not only for crystallizing the semiconductor layer but also for activating impurity ions doped in the semiconductor layer by a laser annealing method. Can also be used.
[0115]
[Example 4]
In this embodiment, the structure of a reflective liquid crystal display device using the active matrix substrate manufactured in Embodiment 3 will be described with reference to FIG.
[0116]
A method for manufacturing the counter substrate will be described below. In addition to glass substrates such as barium borosilicate glass and aluminoborosilicate glass represented by Corning # 7059 glass and # 1737 glass, the substrate 40001 is made of polyethylene terephthalate (PET), polyethylene naphthalate (PEN), poly A plastic substrate having no optical anisotropy such as ether sulfone (PES) can be used. It is desirable to use a substrate having the same thermal expansion coefficient as that of the substrate 2001 in order to prevent the substrate from being distorted in a hot press process described later.
[0117]
A color filter layer 40002 is formed on the substrate 40001. The color filter layer is also formed under a seal material 40003 described later, and is adjusted so that the gap is uniform between the display region and the seal material formation region.
[0118]
An overcoat material 40004 is formed on the color filter layer 40002. The overcoat material has the role of flattening the overlap of the color filters of each color red, blue, and green. The reflective panel displays the panel using external light. In order not to impair the brightness as much as possible, no light shielding film is provided.
[0119]
An indium tin oxide (ITO) film is formed on the overcoat material 40004 as the transparent conductive film 40005. If there is an indium tin oxide (ITO) film in the drive circuit region, an unnecessary capacitance is formed in the drive circuit and the waveform is distorted. For this reason, the indium tin oxide (ITO) film in the drive circuit region is removed by patterning. Thus, the counter substrate is manufactured.
[0120]
The film formation spacer 40006 is formed on the source wiring 2051 using NN700 manufactured by JSR. In this embodiment, a film formation spacer is formed on the counter substrate.
[0121]
An alignment film 40008 is formed on 60 nm substrates 40001 and 2001. Examples of the alignment film include soluble polyimide and thermosetting polyamic acid.
[0122]
As the sealant 40003, a thermosetting epoxy resin or an ultraviolet curable epoxy resin can be used. A liquid crystal material 40009 is sandwiched between the substrates. The liquid crystal material is appropriately selected according to the alignment mode.
[0123]
[Example 5]
The active matrix substrate manufactured in Embodiment 3 can be directly applied to a reflective liquid crystal display device. On the other hand, in the case of a transmissive liquid crystal display device, a pixel electrode provided in each pixel of the pixel portion may be formed using a transparent electrode. In this embodiment, a method for manufacturing an active matrix substrate corresponding to a transmissive liquid crystal display device will be described with reference to FIGS.
[0124]
The active matrix substrate is manufactured in the same manner as in Example 3. In FIG. 14A, a conductive metal film is formed for the source wiring 2051 and the drain wiring 2052 by a sputtering method or a vacuum evaporation method. This is because a Ti film is formed with a thickness of 50 to 150 nm, a contact is formed with a semiconductor film that forms a source or drain region of an island-like semiconductor layer, and aluminum (Al) 300 to 300 is stacked on the Ti film. The film was formed to a thickness of 400 nm, and a Ti film or a titanium nitride (TiN) film was formed to a thickness of 100 to 200 nm to form a three-layer structure. Thereafter, a transparent conductive film is formed over the entire surface, and a pixel electrode 2056 is formed by patterning processing and etching processing using a photomask. The pixel electrode is formed on the interlayer insulating film, and a portion overlapping with the drain wiring 2052 of the pixel TFT is provided to form a connection structure.
[0125]
In FIG. 14B, a transparent conductive film is first formed over an interlayer insulating film, a pixel electrode is formed by patterning treatment and etching treatment, and then a drain wiring 2052 is formed so as to overlap with the pixel electrode 2056. It is an example. In the drain wiring 2052, a Ti film is formed to a thickness of 50 to 150 nm, a contact is formed with a semiconductor film that forms a source or drain region of the island-like semiconductor layer, and aluminum (Al) 300 is overlaid on the Ti film. It is formed with a thickness of ˜400 nm. With this configuration, the pixel electrode 2056 is in contact with only the Ti film forming the drain wiring 2052. As a result, the reaction between the transparent conductive film material and Al can be prevented. The source wiring 2051 is formed at the same time as the drain wiring 2052.
[0126]
The material of the transparent conductive film is indium oxide (In ₂ O _Three ), An indium tin oxide (ITO) film, or the like can be used by sputtering or vacuum evaporation. Etching treatment of such a material is performed with a hydrochloric acid based solution. However, in particular, etching of ITO is likely to generate a residue, so in order to improve etching processability, an indium oxide-zinc oxide alloy (In ₂ O _Three —ZnO) may also be used. Since the indium oxide-zinc oxide alloy has excellent surface smoothness and excellent thermal stability with respect to ITO, it can prevent the corrosion reaction with Al contacting with the end face of the drain wiring. Similarly, zinc oxide (ZnO) is also a suitable material, and zinc oxide (ZnO: Ga) to which gallium (Ga) is added to further increase the transmittance and conductivity of visible light can be used.
[0127]
In this manner, an active matrix substrate corresponding to a transmissive liquid crystal display device can be completed.
[0128]
[Example 6]
An active matrix substrate, a liquid crystal display device, and an EL display device manufactured by implementing the present invention can be used in various electro-optical devices. The present invention can be applied to all electronic devices in which such an electro-optical device is incorporated as a display medium. Examples of electronic devices include personal computers, digital cameras, video cameras, portable information terminals (mobile computers, mobile phones, electronic books, etc.), navigation systems, and the like. An example of them is shown.
[0129]
FIG. 15A illustrates a mobile phone, which includes a main body 9001, an audio output portion 9002, an audio input portion 9003, a display device 9004, operation switches 9005, and an antenna 9006. The present invention can be applied to a display device 9004 including an audio output unit 9002, an audio input unit 9003, and an active matrix substrate.
[0130]
FIG. 15B illustrates a video camera which includes a main body 9101, a display device 9102, an audio input portion 9103, operation switches 9104, a battery 9105, and an image receiving portion 9106. The present invention can be applied to the audio input portion 9103, the display device 9102 provided with the active matrix substrate, and the image receiving portion 9106.
[0131]
FIG. 15C illustrates a mobile computer or a portable information terminal, which includes a main body 9201, a camera portion 9202, an image receiving portion 9203, operation switches 9204, and a display device 9205. The present invention can be applied to an image receiving portion 9203 and a display device 9205 including an active matrix substrate.
[0132]
FIG. 15D illustrates a head mounted display which includes a main body 9301, a display device 9302, and an arm portion 9303. The present invention can be applied to the display device 9302. Although not shown, it can also be used for other signal control circuits.
[0133]
FIG. 15E illustrates a television set including a main body 9401, a speaker 9402, a display device 9403, a receiving device 9404, an amplifying device 9405, and the like. The liquid crystal display device shown in Embodiment 5 and the EL display device shown in Embodiment 6 or 7 can be applied to the display device 9403.
[0134]
FIG. 15F illustrates a portable book which includes a main body 9501, display devices 9502 and 9503, a storage medium 9504, an operation switch 9505, and an antenna 9506. Data stored in a minidisc (MD) or DVD, The data received by the antenna is displayed. The display devices 9502 and 9503 are direct-view display devices, and the present invention can be applied to them.
[0135]
FIG. 16A illustrates a personal computer which includes a main body 9601, an image input portion 9602, a display device 9603, and a keyboard 9604.
[0136]
FIG. 16B shows a player using a recording medium (hereinafter referred to as a recording medium) in which a program is recorded. The player includes a main body 9701, a display device 9702, a speaker portion 9703, a recording medium 9704, and operation switches 9705. This apparatus uses a DVD (Digital Versatile Disc), CD, or the like as a recording medium, and can perform music appreciation, movie appreciation, games, and the Internet.
[0137]
FIG. 16C illustrates a digital camera which includes a main body 9801, a display device 9802, an eyepiece unit 9803, an operation switch 9804, and an image receiving unit (not shown).
[0138]
FIG. 17A illustrates a front type projector, which includes a display device 9901 and a screen 9902. The present invention can be applied to display devices and other signal control circuits.
[0139]
FIG. 17B shows a rear projector, which includes a main body 10001, a projection device 10002, a mirror 10003, and a screen 10004. The present invention can be applied to display devices and other signal control circuits.
[0140]
Note that FIG. 17C is a diagram illustrating an example of the structure of the projection devices 9901 and 10002 in FIGS. 17A and 17B. The projection devices 9901 and 12002 include a light source optical system 10101, mirrors 10102 and 10104 to 10106, a dichroic mirror 10103, a prism 10107, a liquid crystal display device 10108, a retardation plate 10109, and a projection optical system 10110. The projection optical system 10110 is composed of an optical system including a projection lens. Although the present embodiment shows a three-plate type example, it is not particularly limited, and for example, a single-plate type may be used. In addition, the practitioner may appropriately provide an optical system such as an optical lens, a film having a polarizing function, a film for adjusting a phase difference, or an IR film in the optical path indicated by an arrow in FIG. Good.
[0141]
FIG. 17D illustrates an example of the structure of the light source optical system 10201 in FIG. In this embodiment, the light source optical system 10201 includes a reflector 10211, a light source 10212, lens arrays 10213 and 10214, a polarization conversion element 10215, and a condenser lens 10216. Note that the light source optical system illustrated in FIG. 17D is an example and is not particularly limited. For example, the practitioner may appropriately provide an optical system such as an optical lens, a film having a polarization function, a film for adjusting a phase difference, or an IR film in the light source optical system.
[0142]
【The invention's effect】
The laser irradiation apparatus uses a quartz lens to suppress light absorption at a short wavelength, but it is difficult to process the aspherical surface of the quartz lens. However, the present invention can reduce the aberration of the spherical lens.
[0143]
Since each beam passing through each of the divided condensing lenses, which is a feature of the present invention, can be independently moved on the irradiated surface, more precise optical adjustment is possible.
[0144]
When the present invention is used in a laser irradiation apparatus, a linear laser beam more homogeneous than using it can be obtained without using an expensive optical system such as a doublet cylindrical lens and difficult to optically adjust.
[0145]
[Brief description of the drawings]
FIG. 1 shows an embodiment of the present invention (dividing a cylindrical lens).
FIG. 2 shows an embodiment of the present invention (dividing cylindrical lenses having different focal lengths).
3 shows an optical system of Example 1. FIG.
4 shows an optical system of Example 2. FIG.
FIG. 5 shows an example in which the aberration of a lens is reduced according to the present invention.
FIG. 6 shows an example of condensing light in a spot shape according to the present invention.
FIG. 7 shows an optical system for forming a split beam.
FIG. 8 shows an energy profile by a laser irradiation apparatus.
9 is a cross-sectional view of a manufacturing process of a pixel TFT and a TFT of a driver circuit. FIG.
FIG. 10 is a cross-sectional view of a manufacturing process of a pixel TFT and a TFT of a driver circuit.
FIG. 11 is a cross-sectional view of a manufacturing process of a pixel TFT and a TFT of a driver circuit.
FIG. 12 is a top view of a pixel TFT.
FIG. 13 is a cross-sectional view of an active matrix liquid crystal display device.
14 is a cross-sectional view of a manufacturing process of a pixel TFT and a driver circuit TFT which are applied to a transmissive liquid crystal display device. FIG.
FIG 15 illustrates an example of a semiconductor device.
FIG 16 illustrates an example of a semiconductor device.
FIG. 17 shows a configuration of a projection type liquid crystal display device.
FIG. 18 shows a conventional laser irradiation apparatus.
FIG. 19 shows a conventional laser irradiation apparatus.
FIG. 20 shows a conventional laser irradiation apparatus.
FIG. 21 shows aberration of a conventional lens.
FIG. 22 shows a configuration of a cylindrical lens.

Claims (5)

Having a plurality of lenses on which each of a plurality of linear laser beams divided in a short direction is incident;
The plurality of lenses are obtained by dividing and combining spherical lenses having different radii of curvature, and arranged in a direction intersecting with the traveling direction of the linear laser beam,
In the plurality of lenses, the distance between the lens surface from which the plurality of linear laser beams are emitted and the irradiated surface is shorter as the lens is farther from the optical axis of the plurality of linear laser beams. The lenses are arranged such that the radius of curvature is shorter as the lens is farther from the optical axis of the lens, and the focal length is shorter as the lens is farther from the optical axis of the plurality of linear laser beams,
The laser irradiation apparatus, wherein the plurality of linear laser beams are condensed on the irradiated surface by passing through the plurality of lenses.   The laser irradiation apparatus according to claim 1, wherein the spherical lens is a convex lens.   The laser irradiation apparatus according to claim 1, wherein the spherical lens is a convex cylindrical lens.   The laser irradiation apparatus according to claim 1, wherein the irradiated surface is a surface of a semiconductor film.   The laser irradiation apparatus according to any one of claims 1 to 4, wherein the linear laser beam is a laser beam oscillated from an excimer laser.

Images