JP4337554B2 - Manufacturing method of semiconductor device - Google Patents

Description

  The present invention relates to a semiconductor device manufacturing method and an electronic apparatus.

Conventional thin film electronic devices are based on semiconductor processes, and are based on thin film fabrication techniques using vacuum processes. This vacuum process uses a large amount of energy and materials inefficiency as a compensation for extremely fine processing accuracy. Therefore, a low energy liquid phase process has begun to be reviewed as an alternative to the vacuum process. In addition, since this liquid phase process can form a very flat film, it is possible to develop a higher performance transistor by applying such a liquid phase process to the formation of a gate insulating film or an interlayer insulating film of a transistor, for example. It is expected (see, for example, Patent Document 1).
Republished Patent W000 / 59040

By the way, in the element which has a laminated structure, the performance of an element may be impaired by the structural defect in a layer, or the structural defect of the interface of an interlayer. For example, in a transistor, a bulk structural defect in a gate insulating film or a structural defect at an interface between a gate insulating film and a semiconductor film (MOS interface) affects the electrical characteristics and variation in characteristics of the transistor. In particular, a gate insulating film formed by a liquid phase method (for example, a polysilazane fired film) has more defects (dangling bonds) at the interface with silicon than a film using a thermal oxide film. This is one of the challenges in developing high performance devices. For example, the interface state density (Dit) between the silicon film and the gate insulating film is 10 ⁹ cm ⁻² eV ⁻¹ to 10 ¹⁰ cm ⁻² eV ⁻¹ for the thermal oxide film, whereas the polysilazane fired film is 10 ¹¹ cm ⁻² eV ⁻¹ to 10 ¹³ cm ⁻² eV ⁻¹ .
The present invention has been made in view of such circumstances, and a semiconductor device manufacturing method capable of forming a good interface between an insulating film and a semiconductor film formed by a liquid phase process, and the semiconductor An object is to provide an electronic device including the device.

In order to solve the above problems, a method of manufacturing a semiconductor device according to the present invention includes a step of forming a semiconductor film on a substrate, and an insulating film formed on the semiconductor film by a liquid phase method using a liquid material containing polysilazane. Forming a hydrogen blocking film that promotes decomposition of moisture contained in the insulating film and blocks hydrogen generated by the decomposition; and annealing the insulating film. And a step of performing.
Here, a metal material containing aluminum or a semiconductor material such as silicon can be used as the hydrogen block film.

  In the method for manufacturing a semiconductor device according to the present invention, a large amount of water contained in the insulating film (polysilazane fired film) is decomposed by the catalytic action of these metal materials or semiconductor materials, and hydrogen ions and hydrogen generated by the decomposition are generated. Dangling bonds existing at the interface between the insulating film and the semiconductor film are terminated by chemical species such as radicals. For this reason, according to this method, the interface state can be greatly reduced, and a high-performance semiconductor device can be manufactured.

  In the present invention, the “liquid phase method” is a method of placing a liquid material in contact with a substrate, and includes a spin coating method, a slit coating method, a dip coating method, a spray method, a roll coating method, a curtain coating method, Various methods such as a printing method and a droplet discharge method can be employed. In particular, a film (SOG film) formed by spin coating is excellent in flatness and is advantageous in improving the characteristics of a semiconductor device.

  In the method for manufacturing a semiconductor device of the present invention, the semiconductor film forming step may include a step of crystallizing the semiconductor film. Here, the form of “crystallization” may be any of polycrystallization, microcrystallization, and single crystallization. In particular, when a semiconductor film is polycrystallized or microcrystallized, a large amount of dangling bonds exist in the semiconductor film due to the presence of crystal grain boundaries. A significant improvement in device characteristics can be expected.

  Further, the method for manufacturing a semiconductor device of the present invention can include a step of patterning the hydrogen block film to form a wiring layer. As a result, it is not necessary to separately form a conductive material for wiring, and the process can be simplified. Alternatively, the semiconductor device manufacturing method of the present invention may include a step of removing the hydrogen block film and forming a wiring layer on the insulating film. In this case, it is possible to select an optimal conductive material for the wiring. Note that when the present method is applied to a method for manufacturing a transistor, the wiring layer may include a gate electrode.

  In the method for manufacturing a semiconductor device of the present invention, the annealing can be performed in a hydrogen atmosphere. In this case, hydrogen in the atmosphere is taken into the insulating film, so that a film with better interface characteristics is formed.

  According to another aspect of the present invention, there is provided an electronic apparatus including the semiconductor device manufactured by the above-described method. This makes it possible to provide a high-performance electronic device.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. 1 to 3 are process diagrams for explaining a method of manufacturing a thin film transistor (TFT) which is an example of a semiconductor device of the present invention. In all the drawings below, the film thicknesses and dimensional ratios of the constituent elements are appropriately changed in order to make the drawings easy to see.

(Semiconductor film formation process)
In this example, first, as shown in FIG. 1A, a base protective film 10 a is formed on the substrate 10. As the substrate 10, an insulating substrate such as a quartz substrate, a glass substrate, or a heat-resistant plastic can be used. The base protective film 10a has a function of preventing movable ions such as sodium contained in the substrate from being mixed into a semiconductor film described later. The base protective film 10a is made of an insulating material such as a silicon oxide film, a silicon nitride film, or a silicon oxynitride film.

The base protective film 10a is formed by cleaning the substrate 10 with an organic solvent such as pure water or alcohol, and then forming an atmospheric pressure gas layer growth method (APCVD method), a low pressure chemical vapor deposition method (LPCVD method), plasma chemical vapor on the substrate 10. It can be formed by a CVD method such as a phase deposition method (PECVD method) or a sputtering method. When a silicon oxide film is used as the base protective film 10a, the substrate temperature can be set to about 250 ° C. to about 450 ° C. in the APCVD method, and monosilane (SiH ₄ ) or oxygen can be used as a raw material. In the PECVD method or the sputtering method, the substrate temperature is about room temperature to 400 ° C. The thickness of the base protective film 10a is set to a thickness (for example, about 100 nm) sufficient to prevent the impurity element from diffusing and mixing from the substrate.

  Next, as shown in FIG. 1B, a semiconductor film 11 is formed on the base protective film 10a. The base protective film 10a described above is not indispensable, but when a semiconductor thin film transistor is formed on a glass substrate, impurity control to the semiconductor film 11 is important. Therefore, movable ions such as sodium in the glass substrate 10 are generated by the semiconductor. It is preferable to deposit the semiconductor film 11 after forming the base protective film 10a so as not to be mixed into the film 11.

In this example, the semiconductor film 11 is an amorphous silicon film, but the semiconductor film 11 may be other semiconductor material such as germanium. Alternatively, a semiconductor film of a group 4 element complex such as silicon / germanium, silicon carbide, germanium / carbide, a compound compound semiconductor film of a group 3 element such as gallium / arsenic or indium / antimony and a group 5 element, or A composite compound semiconductor film of a group 2 element such as cadmium or selenium and a group 6 element may be used. Further, a compound compound semiconductor film such as silicon, germanium, gallium, and arsenic, and an N-type semiconductor film obtained by adding a donor element such as phosphorus (P), arsenic (As), or antimony (Sb) to these semiconductor films. Alternatively, a P-type semiconductor film to which an acceptor element such as boron, aluminum (Al), gallium (Ga), or indium (In) is added can be used.
Such a semiconductor film 11 can be formed by a CVD method such as an APCVD method, an LPCVD method, or a PECVD method, or a PVD method such as a sputtering method or an evaporation method.

(Semiconductor film crystallization process)
Next, the deposited semiconductor film 11 is crystallized. Here, the term “crystallization” means that an amorphous semiconductor film is given thermal energy to be transformed into a polycrystalline or monocrystalline semiconductor film, and further a microcrystalline film or a polycrystalline semiconductor film. It is also used to apply thermal energy to the film to improve the quality of the crystal film and to recrystallize by melting and solidifying. In this specification, not only amorphous crystallization but also polycrystalline and microcrystalline crystallization are all referred to as crystallization.

The crystallization process of the semiconductor film 11 can be realized by a so-called laser irradiation method, a rapid heating method (such as a lamp annealing method or a thermal annealing method), a method by solid phase growth, or the like, but is not limited thereto. In this example, the amorphous semiconductor film 11 is crystallized into a polycrystalline semiconductor film by laser annealing. In this case, as the laser light, an excimer laser having a wavelength in the ultraviolet region or the vicinity thereof, an argon ion laser, a second harmonic or a third harmonic of a YAG laser, or the like is preferable. For example, a line beam having a long beam length of 400 mm is used with an excimer laser, and its output intensity is set to 400 mJ / cm ² , for example. As for the line beam, it is preferable to scan the line beam so that a portion corresponding to 90% of the peak value of the laser intensity in the short dimension direction overlaps each region.

(Element isolation process)
Next, element isolation for defining a TFT region is performed. In this example, etching is used for element isolation, but LOCOS method, field shield method, STI method, etc. can also be used as element isolation technology. By this element isolation step, a polycrystalline semiconductor film 11 a having a predetermined shape as shown in FIG. 1C is formed on the substrate 10.

(Gate insulating film formation process)
Next, as shown in FIG. 1D, a gate insulating film 12 of TFT is formed on the entire surface of the substrate so as to cover the semiconductor film 11a by using a liquid phase method. Here, first, a coating solution (a liquid material containing polysilazane) in which polysilazane is mixed with xylene is spin-coated on a substrate, and prebaking is performed at a processing temperature of 100 ° C. for 5 minutes. Thereafter, heat treatment is performed at a treatment temperature of 350 ° C. for 260 minutes in a WET O ₂ atmosphere. By performing the heat treatment in a WET O ₂ atmosphere in this way, the nitrogen component in the insulating film that causes polarization can be reduced. Thus, the gate insulating film 12 made of a silicon oxide film is formed.

Note that a cleaning step can be provided between the semiconductor film formation step and the gate insulating film formation step as needed. Specifically, after the patterning of the semiconductor film 11a is completed, the substrate is irradiated with UV light in an oxygen-containing gas atmosphere to decompose and remove contaminants (such as organic substances) present on the substrate surface. Here, as the UV light to be irradiated, a low-pressure mercury lamp having a peak intensity at a wavelength of 254 nm or an excimer lamp having a peak intensity at a wavelength of 172 nm is used. The light in this wavelength region decomposes oxygen molecules (O ₂ ) into ozone (O ₃ ) and further decomposes the ozone into oxygen radicals (O ^* ). By using oxygen radicals, organic substances attached to the substrate surface can be efficiently removed.

(Hydrogen block film formation process, annealing process)
Next, as shown in FIG. 1E, a hydrogen block film 20 is deposited on the gate insulating film 12. Here, the hydrogen block film 20 is generated by decomposing and decomposing water vapor H ₂ O, oxygen O _{2 and the} like (particularly moisture) contained in the gate insulating film 12 in an annealing process (heat treatment process) described later. It functions to confine hydrogen ions, hydrogen radicals, and the like in the gate insulating film 12. As such a hydrogen block film 20, a chemically active metal material or semiconductor material can be used. As such a metal material, for example, aluminum, magnesium, an alloy of aluminum and magnesium, an alloy containing aluminum or magnesium, or a nitride or oxide of aluminum or magnesium can be used. As the semiconductor material, amorphous silicon, polycrystalline silicon, or the like can be used. In this example, the hydrogen block layer 20 is a metal film such as aluminum.
The combination of the metal film 20 and the later-described annealing makes it possible to reduce structural defects in the gate insulating film 12 and defect levels at the interface between the gate insulating film 12 and the polycrystalline semiconductor film 11a. The reason why the defect level is reduced is that dang existing in the film interface or at the film interface due to various chemical species such as hydrogen radicals, hydroxy radicals, hydrogen ions, and hydroxy anions generated by the catalytic action of the metal film 20. This is probably because the ring bond is terminated.

  The metal film 20 may be formed by any method such as sputtering, vapor deposition, and CVD, but sputtering is effective as a method for depositing metal over a wide area. As described above, it is more preferable to use a relatively active metal such as aluminum or magnesium as the metal species. The use of such a metal species has a more significant effect on the improvement of the gate insulating film 12 than when a chemically stable metal such as gold or platinum is used. Note that a metal that moves in the silicon oxide film 12 such as an alkali metal to become a so-called mobile ion deteriorates the film quality as an insulating film, and thus is not preferably used as the metal described above.

Subsequently, after depositing these appropriate metal films 20, annealing (heat treatment) is performed at a temperature of 300 ° C. to 450 ° C. for 10 minutes or more. The atmosphere during annealing may be any atmosphere. However, when the annealing process is performed, for example, in a hydrogen atmosphere, the effect of improving the interfacial characteristics due to the penetration of hydrogen in the atmosphere into the insulating film 12 can be expected. Therefore, the annealing is performed in a hydrogen atmosphere. Is considered desirable.
By performing the annealing process as described above, the defect level density at the interface between the semiconductor film 11a and the gate insulating film 12 can be reduced while maintaining the good dielectric strength and charge density characteristics of the gate insulating film 12. Can do.

(Metal film removal, wiring layer formation process)
Next, as shown in FIG. 2A, the metal film 20 is removed.
When the removal of the metal film 20 is completed, a gate wiring film 13 is formed on the gate insulating film 12 as shown in FIG. The gate wiring film 13 is formed by selecting or depositing an appropriate metal such as tantalum, aluminum or titanium, metal nitride, polysilicon or the like by selecting an appropriate deposition method such as sputtering, CVD or vapor deposition. By doing.

In this step, the metal layer 20 used in the previous step may be used as the whole or a part of the gate wiring film 13 as it is. Thus, by diverting the metal film 20 formed in the previous step in this step, it is possible to save the trouble of forming a conductive material again and simplify the process. Of course, it is possible to completely remove the metal film 20 and form a new gate wiring film 13. This makes it possible to select an optimal material for the wiring film.
Next, as shown in FIG. 2C, the gate wiring film 13 is patterned to form a gate wiring (wiring layer) 13a including a gate electrode.

(Impurity implantation, activation process)
Next, as shown in FIG. 2D, impurity ions are implanted into the semiconductor film 11a using the gate wiring 13a as a mask to form a source region 11s and a drain region 11d. At this time, since the gate electrode 13a is a mask for ion implantation, the channel region 11a has a self-aligned structure formed only under the gate electrode. Impurity ion implantation is performed by ion doping using a mass non-separation type ion implantation apparatus to implant hydride and hydrogen of an implanted impurity element, and ions for implanting only a desired impurity source line using a mass separation type ion implantation apparatus. Two types of driving methods can be applied. As a source gas for the ion doping method, a hydride of an implanted impurity element such as phosphine (PH ₃ ) or diborane (B ₂ H ₆ ) diluted in hydrogen can be used.

  Subsequently, the impurities are activated. Examples of the activation method include a laser irradiation method, a method of heating in a furnace of 300 ° C. or higher (low temperature heat treatment), a rapid heat treatment method using a lamp, and the like.

(Interlayer insulation film formation process)
Next, as shown in FIG. 2E, an interlayer insulating film 14 is formed on the entire surface of the substrate so as to cover the gate insulating film 12 and the gate wiring 13a. The interlayer insulating film 14 may be formed using either a vacuum deposition method such as a plasma CVD method or a liquid phase method such as a spin coating method. In this example, for example, the interlayer insulating film 14 is formed by a method similar to the method for forming the gate insulating film 12. That is, a coating liquid (a liquid material containing polysilazane) in which polysilazane is mixed with xylene is spin-coated on a substrate, and prebaking is performed at a processing temperature of 100 ° C. for 5 minutes. Thereafter, heat treatment is performed at a treatment temperature of 350 ° C. for 260 minutes in a WET O ₂ atmosphere.

(Contact hole formation process, source wiring layer, drain wiring layer formation process)
Next, as shown in FIG. 3A, contact holes H1 and H2 are formed at positions corresponding to the source and drain portions of the interlayer insulating film 14 and the gate insulating film 12, respectively.

Next, as shown in FIG. 3B, a metal film such as an aluminum film, a chromium film, or a tantalum film is formed by sputtering or PVD so as to cover the inner walls of the contact holes H1 and H2, and patterned. Thus, the source electrode 15s and the drain electrode 15d are formed. Note that a protective film can be formed on the source electrode 15s and the drain electrode 15d by depositing silicon oxide, silicon nitride, PSG, or the like, if necessary.
Thus, the thin film transistor (semiconductor device) 1 is manufactured.

  As described above, in the method for manufacturing a semiconductor device of the present invention, moisture in the gate insulating film is removed using the catalytic action of the metal film or silicon film formed on the polysilazane fired film (gate insulating film 12). The dangling bonds of the semiconductor film are terminated by hydrogen radicals and the like that are decomposed and decomposed here. Therefore, according to this method, it is possible to manufacture a high-performance semiconductor device having a low interface state density. In particular, when the semiconductor film 11a is a polycrystalline silicon film as in the present embodiment, a large amount of dangling bonds exist in the film due to the presence of the crystal grain boundary. By applying, a significant improvement in device characteristics can be expected. At this time, in the method of the present invention, since the gate insulating film is formed of a liquid material containing polysilazane, the gate insulating film contains a larger amount of moisture than a thermal oxide film, a CVD film, etc. It is possible to generate a sufficient amount of radicals to terminate dangling bonds in the semiconductor film.

  In the method for manufacturing a semiconductor device of the present invention, when all the insulating films disposed on the semiconductor film 11a are formed by a liquid phase method, an extremely flat film surface can be obtained. Therefore, there is no possibility of disconnection due to a step when forming the wiring, and a highly reliable transistor can be manufactured with a high yield.

In this embodiment, the order of the steps is as described above. However, for example, element isolation is performed after the gate insulating film 12 is formed, or a resist mask or other metal mask is used before the gate wiring film 12 is formed. Then, the order of steps may be changed as appropriate, such as impurity implantation.
In the case where the metal film 20 immediately after the formation of the gate green film 12 is used as it is as a whole or a part of the gate wiring 13a, there is a process of performing a heat treatment at 300 ° C. or higher in the subsequent process. The annealing process immediately after the formation of the metal layer 20 can be omitted. That is, the annealing after the formation of the metal film 20 described above is performed before or after the patterning of the gate wiring film 12, or until the manufacturing process of the transistor and the manufacturing process of the panel including a plurality of transistors are completed. It may be performed at any appropriate time.

In the above embodiment, the semiconductor film 11a is polycrystallized. However, an amorphous semiconductor film (amorphous silicon film) can be used for the active layer of the transistor.
In the above embodiment, an example in which the method for manufacturing a semiconductor device of the present invention is applied to a method for manufacturing a top gate type transistor has been described. However, the present invention is not limited thereto, and the present invention is not limited to this. It is also possible to apply the method.

(Electronics)
Next, the electronic apparatus of the present invention will be described.
FIG. 4 is a perspective view showing an example of an electronic apparatus according to the present invention. A cellular phone 1300 shown in this figure is provided with a semiconductor device manufactured by using the above-described method inside a housing or in a display portion 1301. In the figure, reference numeral 1302 denotes an operation button 1302, reference numeral 1303 denotes a mouthpiece, and reference numeral 1304 denotes a mouthpiece.
The semiconductor device of each of the above embodiments is not limited to the mobile phone, but is an electronic book, a personal computer, a digital still camera, a liquid crystal television, a viewfinder type or a monitor direct view type video tape recorder, a car navigation device, a pager, and an electronic notebook. It can be applied to various electronic devices such as a calculator, a word processor, a workstation, a video phone, a POS terminal, and a device equipped with a touch panel. In any electronic device, high functionality can be realized by applying the semiconductor device of the present invention.

  The preferred embodiments of the present invention have been described above with reference to the accompanying drawings, but it goes without saying that the present invention is not limited to such examples. Various shapes, combinations, and the like of the constituent members shown in the above-described examples are examples, and various modifications can be made based on design requirements and the like without departing from the gist of the present invention.

FIG. 6 is a process diagram for explaining the method for manufacturing a semiconductor device of the present invention. Process drawing following FIG. Process drawing following FIG. FIG. 14 is a perspective view illustrating an example of an electronic device of the invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Thin film transistor (semiconductor device), 10 ... Substrate, 11a ... Polycrystalline semiconductor film, 12 ... Gate insulating film, 13 ... Gate wiring (wiring layer), 14 ... Interlayer insulation Membrane, 20 ... Hydrogen block membrane, 1300 ... Electronic equipment

Claims (7)

Forming a semiconductor film on the substrate;
Forming a gate insulating film on the semiconductor film by a liquid phase method using a liquid material containing polysilazane;
On the gate insulating film, a step of prompting the decomposition of water contained in the gate insulating film, and blocks the hydrogen produced by the decomposition, to form a hydrogen blocking film made of silicon,
And a step of annealing the gate insulating film. A method of manufacturing a semiconductor device, comprising:   2. The method of manufacturing a semiconductor device according to claim 1, wherein the step of forming the semiconductor film includes a step of crystallizing the semiconductor film. Characterized in that it comprises a step of forming a wiring layer by patterning the hydrogen blocking film, a manufacturing method of a semiconductor device according to claim 1 or 2. Removing the hydrogen blocking film, characterized in that it comprises a step of forming a wiring layer on the insulating film, a method of manufacturing a semiconductor device according to claim 1 or 2. The method for manufacturing a semiconductor device according to claim 3 , wherein the wiring layer includes a gate electrode. And performing the annealing in a hydrogen atmosphere, a method of manufacturing a semiconductor device according to any one of claims 1-5. Characterized in that said gate insulating film is a SOG film, a manufacturing method of a semiconductor device according to any one of claims 1-6.

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