JP2004342840A - Method for manufacturing semiconductor element, electro-optical device and electronic apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide the manufacturing method of a semiconductor element in which crystallinity of a semiconductor film is sufficient, an electric characteristic of the semiconductor element is sufficient, deterioration of the electric characteristic due to photocurrent is less and productivity is high. <P>SOLUTION: A shielding film 212 is formed on a quartz substrate 211, and a base protection film 213 is formed to be thinner than the shielding film 212. The semiconductor film 214 is formed, light 215 is irradiated and the semiconductor film 214 is melted and crystallized. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for manufacturing a semiconductor element, for example, a thin film semiconductor device (TFT). Further, the present invention relates to an electro-optical device and an electronic apparatus.
[0002]
[Prior art]
Active-type liquid crystal display devices, image sensors, light valves used in video projectors, and the like that use these semiconductor elements to drive pixels are used as a configuration utilizing semiconductor elements formed on a substrate having an insulating surface such as quartz. Are known.
Generally, a semiconductor element used for a light valve is a polycrystalline thin film semiconductor element manufactured by using a high temperature process. The high-temperature process is a process that employs a thermally oxidized gate insulating film following the LSI technology, and has the disadvantage of using an expensive quartz substrate that can withstand a process temperature of 1000 ° C. or higher, but has reproducibility and stability. It is a technology having excellent characteristics such as mass productivity.
[0003]
Projection light is incident on a thin film semiconductor element used for a light valve. When the projection light is directly or indirectly incident on a semiconductor film serving as a channel forming region of the thin film semiconductor element, a photoelectric conversion effect is generated in this area. As a result, a photocurrent is generated, and the characteristics of the thin-film semiconductor element deteriorate. Therefore, in a thin-film semiconductor element used for a light valve, in order to prevent this characteristic deterioration, a light-shielding film as shown in JP-A-8-171101 is formed between the substrate and the semiconductor film, and the light projected on the semiconductor film is prevented. The incidence is prevented.
[0004]
In a general high-temperature process, a polycrystalline silicon semiconductor film crystallized by a solid phase growth method (SPC method) is used. However, the polycrystalline silicon film crystallized by the solid phase growth method contains many defects. This defect captures carriers and causes the electrical characteristics of the thin film semiconductor device to deteriorate. Then, as one of the techniques for reducing the defects in the polycrystalline silicon film, there is a melting crystallization of the silicon film by an excimer laser annealing method as disclosed in Japanese Patent Application Laid-Open No. 11-261078. The excimer laser annealing method is generally used for manufacturing a polycrystalline thin film semiconductor device by a low-temperature process, and irradiates a silicon film with xenon / chlorine (XeCl) excimer laser light (wavelength 308 nm) or the like to form a silicon film. In this method, the film is melted once and then crystallized through a cooling and solidification process. Since the polycrystalline silicon film obtained by the excimer laser annealing method has undergone a melting and solidifying process, it has few defects and good crystallinity. If this excimer laser annealing method is applied to a method of manufacturing a polycrystalline thin film semiconductor device by a high temperature process, the film quality of the polycrystalline silicon film is improved, and the electrical characteristics of the thin film semiconductor device are also improved.
[0005]
1 to 3 are process diagrams showing a conventional method for manufacturing a thin-film semiconductor device in which excimer laser annealing is applied to a high-temperature process. Hereinafter, a conventional method for manufacturing a thin-film semiconductor device will be described with reference to FIG.
[0006]
In a method of manufacturing a thin film semiconductor device using a semiconductor film formed on a substrate as an active region of a semiconductor device (semiconductor device active region), a quartz substrate 111 is used as a substrate, and a sputtering method or a chemical A metal silicide film 112 of a refractory metal such as W (tungsten) is formed as a light shielding film by a vapor deposition method (CVD method) or the like. On the quartz substrate 111 and the light-shielding film 112, a silicon oxide film 113 is deposited as a base protective film by a chemical vapor deposition method (CVD method). An amorphous silicon film 114 is deposited on the silicon oxide film 113 serving as a base protective film by a low-pressure chemical vapor deposition (LPCVD) method. Next, the amorphous silicon film 114 is irradiated with a xenon / chlorine (XeCl) excimer laser beam 115 to form a polycrystalline silicon film 114 '. Here, the crystal grain boundary surface 116 of the polycrystalline silicon film 114 'is raised. Next, the polycrystalline silicon film 114 'is patterned by photolithography. The polycrystalline silicon film 114 'is thermally oxidized to form a silicon oxide film 118 as a gate insulating film. Next, a gate electrode 119 is formed over the gate insulating film 118, and impurity ions are implanted into the polycrystalline silicon film 114 'to form a source region 114a, a drain region 114c, and a channel formation region 114b. Next, an interlayer insulating film 120 is formed, a contact hole is opened, and source / drain extraction electrodes 121 and 122 and wiring are formed. Thus, the polycrystalline thin film semiconductor device is completed.
[0007]
[Patent Document 1]
JP-A-8-171101
[Patent Document 2]
JP-A-11-2610078
[Patent Document 3]
JP-A-9-51099
[Patent Document 4]
JP-A-6-342912
[0008]
[Problems to be solved by the invention]
In a thin film semiconductor device manufactured by such a conventional manufacturing method, there is a problem that it is difficult to melt-crystallize a semiconductor film. As described above, a light-shielding film exists under a semiconductor film in a thin-film semiconductor element used for a light valve. The presence of the light-shielding film affects the temperature distribution in the semiconductor film at the time of melt crystallization, and as a result, crystallization of the semiconductor film becomes difficult. The thermal conductivity of the metal silicide film used for the light-shielding film is much higher than that of the silicon oxide film. For example, the thermal conductivity of quartz glass at 0 ° C. is 1.9 W · m ^-1 ・ K ^-1 Where the thermal conductivity of silicon is 168 W · m ^-1 ・ K ^-1 And the thermal conductivity of W (tungsten) is 177 W · m ^-1 ・ K ^-1 It is. Therefore, as shown in FIG. 1B, when the semiconductor film 114 existing on the light-shielding film 112 is laser-annealed, the heat 117 of the semiconductor film 114 raised by the laser annealing escapes to the light-shielding film 112 and is exposed. Becomes difficult to rise, and the crystallization of the semiconductor film 114 becomes insufficient. Therefore, when the semiconductor film on the light-shielding film is crystallized by laser annealing, it is necessary to irradiate a laser beam having a higher energy density than in the case where there is no light-shielding film. In addition, laser light having an optimum energy density cannot be irradiated due to a limitation of an apparatus, and crystallization of a semiconductor film may be insufficient. As a result, the electrical characteristics of the thin film semiconductor device are not much improved. Further, since the light-shielding film has an effect of dissipating heat, the temperature of the semiconductor film immediately above the light-shielding film is different from that of the semiconductor film immediately above the light-shielding film peripheral portion, and the crystallization of the semiconductor film becomes non-uniform.
[0009]
Further, in a thin-film semiconductor element manufactured by a conventional manufacturing method, it is necessary to irradiate the semiconductor film with light having a high energy density. Therefore, an expensive high-output light irradiation device is used, or the light irradiation area is reduced. It had to be narrowed to ensure a high energy density. As a result, there have been problems such as a decrease in productivity and an increase in manufacturing cost.
[0010]
Furthermore, when the polycrystalline silicon film 114 'is thermally oxidized, the light-shielding film is also oxidized, which causes a problem that the light-shielding property of the light-shielding film is reduced.
[0011]
The invention disclosed in this specification provides a means for solving the above-mentioned problem. Specifically, in a method of manufacturing a semiconductor device formed on a substrate, a semiconductor film having good crystallinity, good electric characteristics of the semiconductor device, little deterioration of electric characteristics due to photocurrent, and high productivity. It is an object of the present invention to provide a method for producing the same. Another object is to provide an electro-optical device and an electronic device using the semiconductor element.
[0012]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, a method of manufacturing a semiconductor device according to the present invention includes a step of forming a light-shielding film on a substrate, and forming an insulating film on the substrate and the light-shielding film to a thickness equal to or greater than the thickness of the light-shielding film. A step of forming a semiconductor film on the insulating film, irradiating the semiconductor film with light to melt-crystallize the semiconductor film, and thermally oxidizing the semiconductor film surface. It is characterized by the following.
[0013]
According to the method for manufacturing a semiconductor element described above, the semiconductor film can be sufficiently crystallized. The heat of the semiconductor film at the time of melt crystallization easily escapes to the light shielding film. If the thickness of the light-shielding film is large, a sufficient light-shielding effect can be obtained, but the heat of the semiconductor film at the time of melt crystallization is more easily released to the light-shielding film, and the crystallization of the semiconductor film becomes insufficient. I will. Here, if the insulating film is formed to have a thickness equal to or greater than the thickness of the light-shielding film, the influence of the light-shielding film on the heat of the semiconductor film can be reduced. As a result, the semiconductor film can be sufficiently crystallized. Here, the thickness of the insulating film is more preferably twice or more the thickness of the light-shielding film, and more preferably three times or more and four times or more.
[0014]
When the crystallization of the semiconductor film can be sufficiently performed in this manner, the crystallinity of the polycrystalline semiconductor film is improved and defects in the semiconductor film are reduced, which has an effect of improving the electrical characteristics of the semiconductor element. .
[0015]
Further, in the conventional manufacturing method, since the heat of the semiconductor film at the time of melt crystallization easily escapes to the light-shielding film, it is necessary to irradiate the semiconductor film with light having a high energy density. Therefore, it is necessary to use an expensive high-output light irradiation device or to reduce the light irradiation area to secure a high energy density. As a result, there have been problems such as a decrease in productivity and an increase in manufacturing cost. However, according to the above manufacturing method, the influence of the light-shielding film on the heat of the semiconductor film can be reduced, so that the energy density of light applied to the semiconductor film can be reduced. Therefore, the burden on the light irradiation device is reduced, the frequency of device maintenance is reduced, and productivity is improved.
[0016]
Furthermore, according to the above manufacturing method, the insulating film between the light-shielding film and the semiconductor film is sufficiently thick, so that the light-shielding film hardly deteriorates due to thermal oxidation, and the light-shielding film can maintain sufficient light-shielding properties.
[0017]
As described above, according to the above manufacturing method, it is possible to manufacture a semiconductor element having good crystallinity of a semiconductor film, good electric characteristics of a semiconductor element, little deterioration of electric characteristics due to photocurrent, and high productivity. Having.
[0018]
In the method of manufacturing a semiconductor device according to the present invention, the light shielding film is a metal silicide containing at least one of Ti, Cr, W, Ta, Mo, and Pd.
[0019]
According to the method of manufacturing a semiconductor element described above, since the metal is a high melting point metal having a melting point of 1500 ° C. or higher, it can sufficiently withstand a high-temperature process of about 1000 ° C. Further, when the light-shielding film is made of the above-described metal silicide, the thermal compatibility with the substrate is improved, and even when the light-shielding film and the substrate are placed in a high-temperature environment and a normal-temperature environment, the coefficient of thermal expansion, etc. This has the effect that stress generated due to the difference in physical properties is reduced.
[0020]
In the method for manufacturing a semiconductor device according to the present invention, the thickness of the light shielding film is 100 nm or more and 300 nm or less.
[0021]
If the film thickness is smaller than 100 nm, a sufficient light-shielding effect cannot be obtained. On the other hand, if the thickness is more than 300 nm, thermal stress in a high-temperature environment and a normal-temperature environment in a semiconductor element manufacturing process is large, and distortion and cracks occur in the light-shielding film. In addition, the time and cost for forming the light-shielding film are increased, and the step is increased, which makes the manufacture of the semiconductor element difficult. According to the method for manufacturing a semiconductor element described above, since the thickness of the light-shielding film is 100 nm or more and 300 nm or less, the above-described problem does not occur, and a light-shielding film having good light-shielding properties can be formed. .
[0022]
In the method for manufacturing a semiconductor device according to the present invention, the insulating film is a silicon oxide film.
[0023]
According to the above-described method for manufacturing a semiconductor element, the thermal compatibility with the metal silicide used for the light-shielding film is improved, and even when the semiconductor device is placed in a high-temperature environment and a normal-temperature environment, the heat between the light-shielding film and the insulating film is increased. This has an effect that stress generated due to a difference in physical properties such as an expansion coefficient is reduced. Further, the interface state density with the silicon semiconductor film is reduced, and the electrical characteristics of the semiconductor element are improved. Further, there is an advantage that the manufacturing of the insulating film is easy and the manufacturing cost is reduced.
[0024]
In the method of manufacturing a semiconductor device according to the present invention, the thickness of the insulating film is 200 nm or more and 1000 nm or less.
[0025]
When the thickness of the insulating film is smaller than 200 nm, there is a concern that impurities may be mixed into the semiconductor film. If the thickness of the insulating film is greater than 1000 nm, the space between the light-shielding film and the semiconductor film is widened, and light-shielding properties are deteriorated. Further, the time and cost for forming the insulating film are increased. According to the above-described method for manufacturing a semiconductor element, the above-described problem does not occur because the thickness of the insulating film is 200 nm or more and 1000 nm or less.
[0026]
Further, in the method for manufacturing a semiconductor device according to the present invention, the light is a pulsed laser light.
[0027]
According to the above method for manufacturing a semiconductor element, a semiconductor film can be easily melted by using pulsed laser light, and a polycrystalline semiconductor film having a high-purity and smooth surface can be obtained. On the other hand, in continuous wave laser irradiation, the semiconductor film is in a molten state for a long time of several milliseconds or more. For this reason, impurities are easily mixed into the film from the gas phase, and the surface is easily roughened. In contrast, in the case of pulse oscillation in which the substrate can be moved by an appropriate distance for each laser irradiation, the melting time of the active semiconductor film is several hundred microseconds or less. Therefore, impurities are hardly mixed into the film, and the surface is hardly roughened.
[0028]
Further, in the method for manufacturing a semiconductor device according to the present invention, the wavelength of the light is about 240 nm or more and about 550 nm or less.
[0029]
According to the above-described method for manufacturing a semiconductor element, light of this wavelength is efficiently absorbed by a semiconductor film, particularly a silicon semiconductor film, so that the semiconductor film can be easily melted. As the light to be irradiated, krypton / fluorine (KrF) excimer laser light (wavelength: 248 nm), xenon / chlorine (XeCl) excimer laser light (wavelength: 308 nm), second harmonic of Nd: YAG laser light (wavelength: 532 nm), and the like are used. It is preferable because it is high energy and stable. Here, in the case of a laser beam having a wavelength of about 308 nm, the light absorption coefficient of the silicon film is 0.1 nm. ^-1 As described above, since most of the light is absorbed by the silicon film surface, the light-shielding film below the silicon film is hardly irradiated with the laser light. On the other hand, in the case of laser light having a wavelength of about 532 nm, the light absorption coefficient of the amorphous silicon film is about 0.017 nm. ^-1 And the light absorption coefficient of the polycrystalline silicon film is about 0.004 nm. ^-1 Therefore, part of the light passes through the silicon film. When the transmitted light is applied to the light-shielding film, there arise problems that the light-shielding property of the light-shielding film is deteriorated and the crystallization of the semiconductor film becomes non-uniform. However, in the present invention, since the insulating film between the semiconductor film and the light-shielding film is sufficiently thick, the above-described problem does not occur, the semiconductor film is well crystallized, and the light-shielding film maintains light-shielding properties. Can be.
[0030]
In the method for manufacturing a semiconductor device according to the present invention, the temperature of the thermal oxidation step is 800 ° C. or more and 1100 ° C. or less.
[0031]
According to the above-described method for manufacturing a semiconductor element, the interface between the semiconductor film and the thermal oxide film formed on the surface of the semiconductor film is favorably formed. Therefore, when a semiconductor element is manufactured by using this semiconductor film as a channel formation region and a thermal oxide film as a gate insulating film, the interface state density existing at the interface between the channel formation region and the gate insulating film becomes extremely low, and carriers are transferred to the interface. Since the semiconductor device can move without being captured, a high-performance semiconductor element can be manufactured. Here, the higher the thermal oxidation temperature, the higher the quality of the oxide film formed. However, when the temperature is high, the warpage of the substrate becomes a problem. Conversely, if the thermal oxidation temperature is low, the warpage of the substrate is not a problem, but the quality of the oxide film deteriorates. Therefore, it is more preferable that the thermal oxidation temperature be 900 ° C. or more and 1000 ° C. or less.
[0032]
As a specific example of the semiconductor film, an amorphous silicon semiconductor film can be used. This is because the production of the semiconductor film is easy and the production cost is reduced. Furthermore, since light in a wide wavelength range is easily absorbed, there is an advantage that it is easy to melt and crystallize.
[0033]
As another specific example of the semiconductor film, a polycrystalline silicon semiconductor film obtained by crystallizing an amorphous silicon semiconductor film by a solid phase growth method may be used. The amorphous silicon semiconductor film is crystallized by a solid phase growth method, and becomes a polycrystalline silicon semiconductor film having a large grain size. Therefore, the polycrystalline semiconductor film after the melt crystallization becomes a polycrystalline silicon semiconductor film having a large grain size and few defects, and the electrical characteristics of the semiconductor element are extremely excellent.
[0034]
The thinner the semiconductor film, the easier it is to melt and crystallize. Therefore, when the gate insulating film formed over the semiconductor film has a two-layer structure, the thickness of the semiconductor can be reduced. When a gate insulating film is formed by oxidizing the surface of a semiconductor film, the thickness of the semiconductor film is reduced. Therefore, the thickness of the semiconductor film must be increased in consideration of the reduction in the film thickness. However, if the gate insulating film is formed by oxidizing the surface of the semiconductor film to form a first insulating film and depositing a second insulating film on the first insulating film, Since the thickness can be reduced, the thickness of the semiconductor film can be reduced. In addition, by depositing the second insulating film, the protrusion on the surface of the gate insulating film can be suppressed, so that the reliability of the gate insulating film is improved.
[0035]
The present invention also relates to an electro-optical device including a semiconductor element manufactured by the above method as a pixel driving element. By providing a semiconductor element such as a thin film transistor manufactured by the above method, it is possible to provide an electro-optical device such as a liquid crystal display device and an organic EL display with high operation reliability.
[0036]
Further, the present invention relates to an electronic apparatus including the above-described electro-optical device. With the above-described electro-optical device, an electronic device with high operation reliability can be provided.
[0037]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(Example 1)
4 to 6 are process diagrams illustrating a method for manufacturing a semiconductor device according to an embodiment of the present invention. Hereinafter, a method for manufacturing a semiconductor device according to the first embodiment of the present invention will be described with reference to FIG. 7A, FIG. 7B, FIG. 7C, FIG.
[0038]
(A) Step of FIG.
In a method of manufacturing a thin film semiconductor device using a semiconductor film formed on a substrate as an active region (semiconductor device active region) of a semiconductor device, a quartz substrate 211 having a thickness of 1.2 mm is used as the substrate. A metal silicide film 212 of a high melting point metal such as W (tungsten) is formed as a light-shielding film to a thickness of about 200 nm by a sputtering method, a chemical vapor deposition method (CVD method), or the like. A silicon oxide film 213 having a thickness of about 800 nm is deposited on the quartz substrate 211 and the light shielding film 212 as a base protective film by a chemical vapor deposition method (CVD method). An amorphous silicon film 214 is deposited on the silicon oxide film 213 as a base protective film by a low-pressure chemical vapor deposition (LPCVD) method so as to have a thickness of about 85 nm as a semiconductor film to be a semiconductor element active region later. Monosilane (SiH ₄ ), The deposition temperature is about 500 ° C., and the pressure is about 30 Pa. By depositing under such conditions, an amorphous silicon film with good uniformity can be deposited.
[0039]
(B) Step of FIG. 4 (b)
A semiconductor film 214 which is to be a semiconductor element active region later is melt-crystallized by irradiating a pulsed laser beam 215 as light, so that the semiconductor film 214 becomes a polycrystalline semiconductor film 214 ′ with few defects and high crystallinity. As the pulsed laser light 215, xenon / chlorine (XeCl) excimer laser light (wavelength 308 nm) is used. The irradiation area of the XeCl excimer laser light has a rectangular shape with a length of 200 mm and a width of 0.4 mm, and shows a substantially constant intensity distribution. Irradiation energy density of XeCl excimer laser light is 670 mJ · cm ^-2 Then, the amorphous silicon film 214 as a semiconductor film is completely melted, and the semiconductor film is microcrystallized. In order to increase the crystal grain size of the polycrystalline silicon film, laser light may be irradiated at an irradiation energy density slightly lower than the irradiation energy density at which the semiconductor film is microcrystallized. Therefore, the irradiation energy density is 650 mJ · cm ^-2 Or 660 mJ · cm ^-2 Good to be. In addition, any one point on the semiconductor film is subjected to pulsed laser irradiation 20 to 30 times. Here, the pulse laser light is xenon / chlorine (XeCl) excimer laser light (wavelength 308 nm), but the pulse laser light is krypton / fluorine (KrF) excimer laser light (wavelength 248 nm) and the second harmonic of Nd: YAG laser light. Even when a wave (wavelength: 532 nm) or the like is used, melt crystallization can be favorably performed. When the semiconductor film 214 is melt-crystallized by irradiation with light 215, the surface of the crystal grain boundary portion of the polycrystalline silicon film rises like 216. Here, since the thickness of the light-shielding film 212 is about 200 nm and the thickness of the silicon oxide film 213 is about 800 nm, heat of the semiconductor film 214 during melt crystallization hardly escapes to the light-shielding film, and Crystallization can be sufficiently performed.
[0040]
(C) Step of FIG. 5 (c)
Next, the semiconductor film 214 'is patterned by photolithography.
[0041]
(D) Step of FIG. 5 (d)
Next, thermal oxidation of the semiconductor film 214 'is performed. After inserting the substrate into the heat treatment furnace at a temperature of 800 ° C., nitrogen and a small amount of oxygen are flowed into the heat treatment furnace to change the atmosphere in the heat treatment furnace to an atmosphere in which oxygen in nitrogen is about 10 ppm to 1%. The temperature is increased at a rate of about 20 ° C. from 4 ° C. per minute, and the temperature in the heat treatment furnace is set to 1000 ° C. If the rate of temperature rise is as low as about 4 ° C., the temperature controllability will be improved, but the temperature rise will take a long time, and the productivity will be reduced. On the other hand, if the temperature raising rate is as high as 20 ° C., the temperature controllability is deteriorated, but the productivity is improved because the temperature raising time is shortened. If the above temperature rise process is performed in a 100% nitrogen atmosphere, there is a problem that a hole is formed in the semiconductor film. When the atmosphere in which oxygen in nitrogen is about 10 ppm as described above, an ultrathin oxide film is formed on the semiconductor film, so that a hole in the semiconductor film can be prevented. Here, if the oxygen concentration is too high, about 1% or more, the oxide film thickness becomes too thick. Since this oxide film is formed at a low temperature, the film quality is poor, and when it becomes a gate insulating film, it causes a decrease in the characteristics and reliability of the thin film semiconductor element. Therefore, in the above-described temperature increasing step, the oxygen concentration is set sufficiently low from about 10 ppm to about 1% to prevent a hole from being formed in the semiconductor film and to prevent a gate insulating film having poor film quality from growing more than necessary. There is a need to. After the temperature rises, the atmosphere in the heat treatment furnace is made to contain 2% or more of oxygen in nitrogen or 100% of oxygen, and the polycrystalline silicon film 214 'as a semiconductor film is oxidized to thereby form a silicon oxide film 218 as a gate insulating film. Is formed to a thickness of about 90 nm. At this time, the thickness of the semiconductor film 214 'is about 40 nm.
[0042]
(E) Step of FIG.
A gate electrode 219 is formed over the gate insulating film 218. The gate electrode is made of monosilane (SiH ₄ ) And phosphine (PH ₃ ), A conductive polycrystalline silicon semiconductor film containing phosphorus (P) deposited by low pressure chemical vapor deposition (LPCVD) at a temperature of about 550 ° C. and a pressure of about 120 Pa. After the formation of the gate electrode 219, impurity ions are implanted into the polycrystalline silicon film 214 'to form a source region 214a, a drain region 214c, and a channel formation region 214b. As impurity ions, B ions or BF in the case of an N-type thin film semiconductor element ₂ Ions are implanted, and in the case of a P-type thin film semiconductor device, P ions are implanted.
[0043]
(F) Step of FIG.
Next, an interlayer insulating film 220 is formed, a contact hole is opened, and source / drain extraction electrodes 221 and 222 and wiring are formed. Thus, the semiconductor device is completed.
[0044]
As described above, according to the first embodiment, a semiconductor element having good crystallinity of a semiconductor film, good electric characteristics of a semiconductor element, little deterioration of electric characteristics due to photocurrent, and high productivity can be obtained. Can be manufactured.
[0045]
(Example 2)
In the step (a) of the first embodiment, the deposition pressure of the amorphous silicon film 214 is about 100 Pa. By thus increasing the deposition pressure, generation of crystal nuclei in the amorphous silicon film can be suppressed. After depositing the amorphous silicon film 214, the amorphous silicon film 214 is crystallized by a solid phase growth method. Since the amorphous silicon film 214 has few crystal nuclei, by performing solid phase growth, the amorphous silicon film 214 becomes a polycrystalline silicon film having a large grain size, and the electrical characteristics of the thin film semiconductor element are improved. . In the solid phase growth, the substrate is inserted into a heat treatment furnace at a temperature of 600 to 640 ° C. in a nitrogen atmosphere, and heat treatment is performed for 6 to 24 hours. If the temperature is low, the crystal grain size of the polycrystalline silicon film is large, but the processing time is long, and the productivity is low. On the other hand, when the temperature is high, the crystal grain size of the polycrystalline silicon film is smaller than when the temperature is low, but the processing time is shortened, so that the productivity is improved. Thus, the semiconductor film 214 is changed from an amorphous silicon film to a polycrystalline silicon film having a large grain size.
[0046]
In step (b) of Example 1, the irradiation energy density of the XeCl excimer laser light was set to 660 mJ · cm. ^-2 Or 670 mJ · cm ^-2 And This is because the semiconductor film 214 has already become a polycrystalline silicon film by solid phase growth, and 680 mJ · cm ^-2 This is because the semiconductor film 214 is completely melted.
[0047]
Except for the above, the semiconductor device is completed as in the first embodiment.
[0048]
As described above, according to the second embodiment, the crystallinity of the semiconductor film is good, the crystal grain size of the semiconductor film is large, the electric characteristics of the semiconductor element are good, and the deterioration of the electric characteristics due to photocurrent is small. In addition, a semiconductor device with high productivity can be manufactured.
[0049]
(Example 3)
In the step (a) of the first embodiment, disilane (Si ₂ H ₆ ) To lower the deposition temperature to about 425 ° C. By lowering the deposition temperature in this manner, generation of crystal nuclei in the amorphous silicon film can be suppressed. Next, solid-phase growth of the semiconductor film 214 is performed in the same manner as in the second embodiment, so that the semiconductor film 214 is a polycrystalline silicon film having a large grain size. Further, as in the second embodiment, the semiconductor film 214 is irradiated with a XeCl excimer laser beam.
[0050]
Except for the above, the semiconductor device is completed in the same manner as in the first embodiment.
[0051]
As described above, according to the third embodiment, the semiconductor film has good crystallinity, the crystal grain size of the semiconductor film is large, the electric characteristics of the semiconductor element are good, and the deterioration of the electric characteristics due to photocurrent is small. In addition, a semiconductor device with high productivity can be manufactured.
[0052]
(Example 4)
Referring to FIG. 7A, an amorphous silicon film 314 is deposited as thin as about 55 nm in the same manner as in step (a) of the first embodiment.
[0053]
Next, the semiconductor film 314 is irradiated with XeCl excimer laser light in the same manner as in the step (b) of the first embodiment. Since the semiconductor film 314 is as thin as 55 nm, the laser energy density for sufficiently crystallizing the semiconductor film is low. The irradiation energy density of XeCl excimer laser light at which the semiconductor film 314 is completely melted and microcrystallized is 420 mJ · cm. ^-2 It becomes. Therefore, the irradiation energy density is 400 mJ · cm ^-2 Or 410mJ · cm ^-2 Good to be. As described above, since the irradiation energy density is low, the burden on the light irradiation device is reduced, and the manufacturing cost can be reduced. Further, the semiconductor film can be sufficiently crystallized even with a low-output light irradiation device.
[0054]
Next, the semiconductor film 314 'is patterned in the same manner as in the step (c) of the first embodiment.
[0055]
A silicon oxide film 317 as a first gate insulating film is formed as thin as about 30 nm by oxidizing a polycrystalline silicon film 314 ′ as a semiconductor film by using the same method as in the step (d) of the first embodiment. I do. At this time, the thickness of the semiconductor film 314 'is about 40 nm. Further, a silicon oxide film 318 as a second gate insulating film is deposited to a thickness of about 50 nm on the silicon oxide film 317 as the first gate insulating film by a chemical vapor deposition method (CVD method). The second gate insulating film is formed by a low-pressure chemical vapor deposition (LPCVD) method using monosilane (SiH ₄ ) And nitrous oxide (N ₂ O), the deposition temperature is about 800 ° C. to 850 ° C., and the pressure is about 80 Pa. The protrusion 316 on the surface of the semiconductor film 314 ′ remains on the surface of the first gate insulating film 317. This is because the first gate insulating film 317 is formed by thermally oxidizing the semiconductor film 314 '. However, since the second gate insulating film 318 is deposited by the CVD method, the surface of the second gate insulating film 318 is flattened to some extent. Therefore, the reliability of the gate insulating film is improved.
[0056]
Next, a gate electrode is formed on the second gate insulating film 318 in the same manner as in the step (e) of the first embodiment.
[0057]
Except for the above, the semiconductor device is completed in the same manner as in the first embodiment.
[0058]
As described above, according to the fourth embodiment, the crystallinity of the semiconductor film is good, the electric characteristics of the semiconductor element are good, the reliability of the gate insulating film is high, and the deterioration of the electric characteristics due to photocurrent is small. In addition, a semiconductor device with high productivity can be manufactured.
[0059]
(Application example)
The semiconductor element obtained by the manufacturing method of the present invention can be used as a thin film transistor which is a switching element of a liquid crystal display device or a thin film transistor which is a driving element of an electroluminescence display. FIG. 8 is a circuit configuration diagram of a pixel region of the electro-optical device 10 driven by the active matrix method. C, comprising thin film transistors T1 and T2, which are semiconductor elements manufactured by the manufacturing method of the present invention. From the scanning line driver 20, a selection signal line Vsel is supplied to each pixel. From the data line driver 30, a signal line Vsig and a power supply line Vdd are supplied to each pixel. By controlling the selection signal line Vsel and the signal line Vsig, current programming is performed for each pixel, and light emission by the light emitting unit OLED is controlled.
[0060]
A semiconductor element such as a thin film transistor obtained by the manufacturing method of the present invention can be applied to various electronic apparatuses including an electro-optical device. FIG. 9 illustrates an example of an electronic device to which the electro-optical device can be applied.
[0061]
FIG. 9A shows an example of application to a mobile phone. A mobile phone 930 includes an antenna unit 931, an audio output unit 932, an audio input unit 933, an operation unit 934, and the electro-optical device 10 of the present invention. . As described above, the electro-optical device 10 of the present invention can be used as a display unit of the mobile phone 930.
[0062]
FIG. 9B shows an example of application to a video camera. The video camera 940 includes an image receiving unit 941, an operation unit 942, an audio input unit 943, and the electro-optical device 10 of the present invention. As described above, the electro-optical device according to the invention can be used as a finder or a display unit.
[0063]
FIG. 9C shows an example of application to a portable personal computer. A computer 950 includes a camera unit 951, an operation unit 952, and the electro-optical device 10 of the present invention. As described above, the electro-optical device of the present invention can be used as a display unit.
[0064]
FIG. 14D shows an example of application to a head-mounted display. The head-mounted display 960 includes a band 961, an optical system storage section 962, and the electro-optical device 10 of the present invention. As described above, the electro-optical device of the present invention can be used as an image display source.
[0065]
FIG. 9E shows an example of application to a rear-type projector. A projector 970 includes a housing 971 provided with a light source 972, a synthetic optical system 973, a mirror 974, a mirror 975, a screen 976, and the electro-optical device 10 of the present invention. It has. As described above, the electro-optical device of the present invention can be used as an image display source.
[0066]
FIG. 17F shows an example of application to a front type projector. The projector 980 includes an optical system 981 and an electro-optical device 10 of the present invention in a housing 982, and can display an image on a screen 983. As described above, the electro-optical device of the present invention can be used as an image display source.
[0067]
The electro-optical device 10 of the present invention is not limited to the above example, and can be applied to any electronic apparatus to which an active matrix display device can be applied. For example, the present invention can be applied to a facsimile apparatus having a display function, a viewfinder of a digital camera, a portable TV, a DSP apparatus, a PDA, an electronic organizer, an electronic bulletin board, and a display for publicity announcement.
[0068]
【The invention's effect】
As described above in detail, according to the present invention, a semiconductor element having good crystallinity of a semiconductor film, good electric characteristics of a semiconductor element, little deterioration of electric characteristics due to photocurrent, and high productivity is manufactured. be able to. According to the method for manufacturing a semiconductor device of the present invention, a high-performance semiconductor device can be manufactured easily and stably. Therefore, when the method of manufacturing a semiconductor device according to the present invention is applied to an active matrix liquid crystal display device, a large, high-quality liquid crystal display device can be easily and stably manufactured. Furthermore, when applied to the manufacture of other electronic circuits, a high-quality electronic circuit can be easily and stably manufactured. Furthermore, when applied to the manufacture of other electronic circuits, a high-quality electronic circuit can be easily and stably manufactured.
[Brief description of the drawings]
FIG. 1 is a process chart showing a conventional method for manufacturing a semiconductor device.
FIG. 2 is a process chart showing a conventional method for manufacturing a semiconductor device.
FIG. 3 is a process chart showing a conventional method for manufacturing a semiconductor device.
FIG. 4 is a process diagram illustrating a method of manufacturing a semiconductor device according to an embodiment of the present invention.
FIG. 5 is a process diagram illustrating a method of manufacturing a semiconductor device according to an embodiment of the present invention.
FIG. 6 is a process diagram illustrating a method of manufacturing a semiconductor device according to an embodiment of the present invention.
FIG. 7 is a process chart illustrating a method of manufacturing a semiconductor device according to a fourth embodiment of the present invention.
FIG. 8 is a circuit configuration diagram of a pixel region of the electro-optical device according to the embodiment of the present invention.
FIG. 9 is a schematic diagram showing an example of an electronic device according to an embodiment of the present invention.
[Explanation of symbols]
111, 211, 311 ... quartz substrate
112, 212, 312 ... light shielding film
113, 213, 313: Underlying protective film
114, 214, 314 ... semiconductor film
114 ', 214', 314 '... polycrystalline semiconductor film
114a, 214a ... source area
114b, 214b ... channel forming region
114c, 214c ... drain region
115, 215 ... light (xenon / chlorine excimer laser light)
116, 216, 316 ... bump on the surface of the semiconductor film
117: Heat of the semiconductor film
118, 218 ... gate insulating film
317: First gate insulating film
318: second gate insulating film
119, 219 ... gate electrode
120, 220 ... interlayer insulating film
121, 221 ... source electrode
122, 222 ... drain electrode
10. Electro-optical device
20: Scan line driver
30 ... Data line driver
930… mobile phone
931 ... antenna part
932: audio output unit
933: Voice input unit
934: Operation unit
940 ... Video camera
941 ... image receiving section
942: operation unit
943: voice input unit
950 ... Computer
951 ... Camera part
952 ... Operation unit
960 ... Head mounted display
961 ... Band
962: Optical system storage unit
970 ... to the rear projector
971 ... housing
972 ... light source
973: Synthetic optical system
974 ... Mirror
975 ... Mirror
976 ... Screen
980: Front type projector
981 ... Optical system
982 ... case
983 ... Screen

Claims (10)

In a method for manufacturing a semiconductor element,
Forming a light-shielding film on the substrate;
Forming an insulating film on the substrate and the light-shielding film to a thickness equal to or greater than the thickness of the light-shielding film, and forming a semiconductor film on the insulating film;
Irradiating the semiconductor film with light to melt-crystallize the semiconductor film, and thermally oxidizing the semiconductor film surface;
A method for manufacturing a semiconductor device, comprising: The method for manufacturing a semiconductor device according to claim 1,
The method according to claim 1, wherein the light shielding film is a metal silicide containing at least one of Ti, Cr, W, Ta, Mo, and Pd. The method for manufacturing a semiconductor device according to claim 1 or 2,
A method of manufacturing a semiconductor device, wherein the thickness of the light shielding film is 100 nm or more and 300 nm or less. The method for manufacturing a semiconductor device according to claim 1, wherein
The method for manufacturing a semiconductor device, wherein the insulating film includes a silicon oxide film. The method for manufacturing a semiconductor device according to claim 1, wherein
A method for manufacturing a semiconductor device, wherein the thickness of the insulating film is 200 nm or more and 1000 nm or less. The method for manufacturing a semiconductor device according to claim 1, wherein
A method for manufacturing a semiconductor device, wherein the light is pulsed laser light. The method for manufacturing a semiconductor device according to claim 1, wherein
A method for manufacturing a semiconductor device, wherein the wavelength of the light is about 240 nm or more and about 550 nm or less. The method for manufacturing a semiconductor device according to claim 1, wherein
A method for manufacturing a semiconductor device, wherein the temperature of the thermal oxidation step is 800 ° C. or more and 1100 ° C. or less. An electro-optical device comprising a semiconductor element manufactured by the method according to claim 1 as a pixel driving element. An electronic apparatus comprising the electro-optical device according to claim 9.

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