JPH10163112A - Manufacture of semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a semiconductor device where beams with an optimum energy can be emitted according to the structure of the ground and crystallization can be conducted uniformly all over the film when crystallizing an amorphous semiconductor film. SOLUTION: A gate electrode 11 is formed on a glass substrate 10, and at the same time a transparent aluminum nitride film 12 is formed only at a region where no gate electrode 11 is formed. An amorphous silicon film is formed on the gate electrode 11 and the aluminum nitride film 12 via an insulation film, and an n-type impurity is introduced by plasma or ion doping to form a source region 21a and a drain region 21b. Then, when laser beams 20 are emitted from a substrate surface, the amorphous silicon film is melted, and then the melted region is crystallized to become a polycrystalline silicon film 21 by cooling to room temperature. In this case, since the aluminum nitride film 12 with improved heat conductivity is formed at a region where there is no metal film (the gate electrode 11), the maximum arrival temperature of a film surface becomes nearly uniform to uniformly crystallize the entire film.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a semiconductor device in which a semiconductor film such as an amorphous silicon film is formed by irradiating an energy beam to crystallize the film, and more particularly to a liquid crystal display device (LCD). A thin film transistor (TFT) used for a liquid crystal display, etc.
The present invention relates to a method for manufacturing a semiconductor device having a structure in which the underlayer of a semiconductor film to be crystallized is not uniform as in the case of stor).

[0002]

2. Description of the Related Art A TFT liquid crystal display device uses a thin film transistor (TFT) as an element having a switching function, and the TFT is formed on a glass substrate corresponding to each liquid crystal display pixel. There are two types of TFTs, one made of an amorphous silicon film and the other made of a polycrystalline silicon film. The TFT made of the polycrystalline silicon film is formed by irradiating an amorphous silicon film with an energy beam, particularly an excimer laser. A high-performance glass substrate can be manufactured at a low temperature. Using such a polycrystalline silicon film TFT, a peripheral circuit of a liquid crystal display and a pixel switching element can be manufactured on the same substrate. In recent years, among TFTs made of a polycrystalline silicon film, TFTs having a bottom gate structure have been attracting attention, in particular, since stable characteristics can be obtained.

The bottom gate TFT has a structure as shown in FIG. 14, for example. That is, a gate electrode 101 made of molybdenum tantalum (MoTa) is formed on a glass substrate 100.
An oxide film (Ta ₂ O ₅ ) 102 is formed on 1.
On the glass substrate 100 including the oxide film 102, a silicon nitride (SiNx) film 103 and a silicon dioxide (Si
A gate insulating film made of an O ₂ ) film 104 is formed, and a thin polycrystalline silicon film 105 is formed on the silicon dioxide film 104. This polycrystalline silicon film 105
The source region 105 is formed therein by introducing, for example, an n-type impurity.
a and the drain region 105b are formed respectively. On the polycrystalline silicon film 105, a silicon dioxide film (SiO2) 106 is selectively formed corresponding to the channel region 105c of the polycrystalline silicon film 105.
Polycrystalline silicon film 105 and silicon dioxide film 106
On the n ⁺ -doped polycrystalline silicon film 107, a source electrode 108 is formed on the n ⁺ -doped polycrystalline silicon film 107 so as to face the source region 105a, and a drain electrode 109 is formed on the n ⁺ doped polycrystalline silicon film 107 so as to face the drain region 105b. Have been.

[0004] The TFT having the bottom gate structure can be manufactured by the following method. That is, molybdenum tantalum (MoTa) is formed on the entire surface of the glass substrate 100.
After forming the film, the molybdenum tantalum film is patterned into a predetermined shape by etching to form the gate electrode 101.
To form Thereafter, the gate electrode 101 is anodized to form an oxide film 102 on the surface thereof. Next, PECVD (Plasma Enhanced Chemical Vapor Depo
The silicon nitride film 103, the silicon dioxide film 104, and the amorphous silicon film are continuously formed on the entire surface of the oxide film 102 by the sition) method.

Next, by irradiating the amorphous silicon film with a laser beam by, for example, an excimer laser,
This amorphous silicon film is once melted and then cooled to room temperature to be crystallized. Thus, the amorphous silicon film becomes the polycrystalline silicon film 105. Subsequently, after selectively forming a silicon dioxide film 106 having a shape corresponding to the channel region on the portion of the polycrystalline silicon film 105 to be a channel region, an n-type impurity such as phosphorus (P) or arsenic (As) is formed.
Is formed, and the laser beam is again irradiated with an excimer laser to form the n ⁺ -doped polycrystalline silicon film 107 and the impurities are electrically activated.

Next, argon (A) is used as a sputtering gas.
r), an aluminum (Al) film is formed on the entire surface by a sputtering method, and the aluminum film and the n ⁺ -doped polycrystalline silicon film 107 are patterned into predetermined shapes by etching, respectively.
05a and the source electrode 10 on the drain region 105b.
8 and the drain region 109 are formed. Subsequently, the channel region 105c is hydrogenated by hydrogen radicals and atomic hydrogen that are exposed to hydrogen and pass through the silicon dioxide film 106 to inactivate dangling bonds and the like. Through the above process, the TFT having the bottom gate structure shown in FIG. 14 can be obtained.

[0007]

As described above, in the conventional method, in the step of crystallizing the amorphous silicon film,
The amorphous silicon film is irradiated with an energy beam. At this time, the underlying structure of the amorphous silicon film is not uniform. That is, there is a metal film (gate electrode 101) on the glass substrate 100, and the base of the amorphous silicon film has a structure in which two types of materials, metal and glass, are different from each other. The crystalline silicon film is simultaneously irradiated with an energy beam. In this case, the same energy beam is applied to the glass substrate 1 based on the optimum condition of the crystallization energy of the amorphous silicon film in the channel region on the metal film (gate electrode 101).
Irradiation was also performed on the amorphous silicon film on the substrate No. 00.

However, even for the same amorphous silicon film, the optimum value of the energy for crystallization is different between the region where the base is a metal and the region where the base is a glass because the thermal conductivity is different. Therefore, the metal film (the gate electrode 10)
1) In the conventional method that is adapted to the optimum condition of the amorphous silicon film, the amorphous silicon film on the glass substrate 100 is irradiated with more energy beams than the optimum condition. There has been a problem that film destruction may occur.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to be able to irradiate an amorphous semiconductor film with a beam having an optimum energy according to the structure of a base when crystallizing the same. Another object of the present invention is to provide a method for manufacturing a semiconductor device which can be uniformly crystallized over the entire film and has no fear of film destruction.

[0010]

According to a method of manufacturing a semiconductor device according to the present invention, a step of selectively forming a metal film on a substrate and a step of forming a metal film substantially in a region where the metal film is not formed on the substrate. Forming an insulating film having the same thermal conductivity, forming an amorphous semiconductor film having a uniform thickness on the metal film and the insulating film, and irradiating the amorphous semiconductor film with an energy beam. In order to uniformly polycrystallize the semiconductor film.

In another method for manufacturing a semiconductor device according to the present invention, a step of forming an insulating film on a substrate and a step of selectively forming a metal film having substantially the same thermal conductivity as the insulating film on the insulating film are performed. A step of forming an amorphous semiconductor film having a uniform thickness over the metal film and the insulating film; and irradiating the amorphous semiconductor film with an energy beam to uniformly polycrystallize the semiconductor film. And the step of performing.

[0012] Still another method of manufacturing a semiconductor device according to the present invention includes a step of forming a metal film as a gate electrode of a thin film transistor on a surface of a transparent substrate, and a step of forming a metal film in a region other than the metal film on the transparent substrate. Forming a transparent insulating film having the same thermal conductivity, forming an insulating film on the metal film and the transparent insulating film, and then forming an amorphous semiconductor film having a uniform thickness on the insulating film. Forming a source region and a drain region by selectively introducing impurities into regions other than the region corresponding to the metal film on the semiconductor film; and energizing the semiconductor film on which the source region and the drain region are formed. Irradiating a beam to perform polycrystallization.

Still another method of manufacturing a semiconductor device according to the present invention includes a step of forming a transparent insulating film on a surface of a transparent substrate;
A step of selectively forming a metal film having substantially the same thermal conductivity as the transparent insulating film on the transparent insulating film and serving as a gate electrode of the thin film transistor; and forming an insulating film on the metal film and the transparent insulating film. Thereafter, a step of forming an amorphous semiconductor film having a uniform thickness on the insulating film and a step of selectively introducing impurities into a region other than the region corresponding to the metal film on the semiconductor film to form a source region and a drain region. Forming respective regions;
Irradiating the semiconductor film on which the source region and the drain region are formed with an energy beam to perform polycrystallization.

In the present specification, the expression that the thermal conductivity of a metal film is substantially the same as the thermal conductivity of an insulating film (or a transparent insulating film) means that an amorphous film formed on an upper layer of the metal film and the insulating film. It is intended to include the case where the thermal conductivity is close enough to uniformly crystallize the entire semiconductor film when the energy semiconductor film is irradiated with the energy beam.

In the method of manufacturing a semiconductor device according to the present invention, when an energy beam is irradiated, the amorphous semiconductor film is melted, and then cooled to room temperature to crystallize the molten region to form a polycrystalline film. At this time, since the insulating film having substantially the same thermal conductivity as the metal film is formed in a region adjacent to the metal film (gate electrode) on the substrate or in a base region of the metal film, the maximum temperature of the film surface is reached. Are substantially the same, and are uniformly crystallized throughout the film.

[0016]

Embodiments of the present invention will be described below in detail with reference to the drawings.

Prior to the description of specific embodiments, first, the basic principle of the present invention will be described. As described above, even if the same amorphous silicon film is used, the optimum value of the energy for crystallization is different depending on whether the base is made of metal or glass. In the present invention, an insulating film having a good thermal conductivity is formed in a region where a metal film is not present in an underlayer structure, so that the semiconductor film can be uniformly crystallized over the entire surface of the semiconductor film by the same energy beam irradiation. is there. Hereinafter, the reason will be described.

FIGS. 7A and 7B show examples of substrates in which the underlying structures of the silicon films are different from each other. 7A, a nickel (Ni) film 61 is formed on a glass substrate 60, and a silicon nitride (SiN) film 62, an insulating film (SiO ₂ ) 63, and an amorphous silicon film (a) are formed thereon. -S
i) 64 are formed in this order. On the other hand, FIG.
The structure of (b) is such that silicon nitride (S
An iN) film 62, an insulating film (SiO ₂ ) 63 and an amorphous silicon film 64 are formed.
Has the same structure except that the metal film (nickel film 61) does not exist on the underlayer.

FIG. 9 shows an excimer laser (energy: 360 mJ / cm ² , pulse width: 30 n) as an energy beam for the amorphous silicon film 64 having the structure shown in FIG.
(s, wavelength of 308 nm) when simulating the temperature change of the outermost surface of the amorphous silicon film 64. On the other hand, FIG. 10 shows the result of simulating the temperature change of the outermost surface of the amorphous silicon film 64 when the same excimer laser is irradiated to the amorphous silicon film 64 having the structure of FIG. 7B. It is. FIG. 8 shows the parameters of the material of each film.

As is clear from the results shown in FIGS. 9 and 10, the temperature of the amorphous silicon film 64 rapidly rises to the melting point (a-Si melting point) during the irradiation with the excimer laser, , Where the slope of the rise once becomes gentle due to the latent heat of melting, and then rises rapidly again. Here, when excimer lasers of the same energy are irradiated, the maximum attainable temperature differs depending on the underlying structure of the amorphous silicon film 64. That is, when the metal film (the nickel film 61) exists under the amorphous silicon film 64 (the structure of FIG. 7A), the maximum temperature is about 265.
On the other hand, when the metal film (nickel film 61) does not exist on the underlayer (the structure shown in FIG. 7B), the maximum temperature is about 2940 (K). It depends greatly on. The difference between the highest temperatures is determined by
The smaller the thickness, the larger. After the excimer laser irradiation is completed after the maximum temperature is reached, FIG.
In any of the structures (a) and (b), heat spreads in the direction of the glass substrate 60, and the temperature of the amorphous silicon film 64 gradually decreases. Then, the crystallization temperature of silicon (1
(410 ° C.), latent heat of crystallization is generated, and the temperature becomes constant for a certain time (crystallization time), and then gradually decreases again.

When irradiating an excimer laser to the amorphous silicon film 64 having the respective structures shown in FIGS. 7A and 7B, in order to optimize laser conditions, it is necessary to use the same energy for each amorphous silicon film. It is desirable that the maximum temperature reached on the surface of the silicon film 64 be the same. For this reason, as shown in FIG. 11, the present inventor has made a transparent insulating film having good thermal conductivity, for example, aluminum nitride (Al) on a glass substrate 60 as shown in FIG.
N) By forming the film 65, the temperature conditions are the same as those of the structure of FIG. 7A, so that the temperature of the outermost surface of the silicon film is the same regardless of the underlying structure (the presence or absence of the metal film). In consideration of this, the characteristic diagrams shown in FIGS. 12 and 13 were obtained by experiments.

FIG. 12 shows the maximum temperature at the outermost surface of the silicon film 64 and the crystallization time of silicon when the thickness of the aluminum nitride film 65 is changed in the structure of FIG. That is, FIG. 12 shows the structure of FIG.
The thickness of the silicon film 64 is 30 nm, and the insulating film (SiO ₂ )
63 has a thickness of 100 nm and a silicon nitride (SiN) film 6
2 is fixed to 50 nm, the thickness of the aluminum nitride (AlN) film 65 is changed, and an excimer laser is irradiated at 400 mJ / cm ² , and the silicon film 6 at that time is irradiated.
4 shows the result of simulating the highest temperature of the outermost surface and the crystallization time of silicon. FIG. 13 shows a simulation result of the temperature of the surface of the glass substrate 60 and the crystallization time of silicon when the excimer laser is irradiated at 360 mJ / cm 2 and the other conditions are the same as those of FIG. According to this result, FIG.
In the structure of FIG. 11 and the structure of FIG. 11, in order to optimize the laser condition by making the maximum temperature of the surface of the silicon film 64 by the energy beam irradiation the same, the thickness of the aluminum nitride film 65 of the structure of FIG. It can be seen that setting should be made according to the results of FIG. 12 and FIG.

The present invention utilizes such a result to form an insulating film having good thermal conductivity on the same substrate in a region where there is no metal film, so that the maximum temperature can be kept the same over the entire film. The crystallization is performed in the following manner. Hereinafter, an example in which the present invention is applied to a method for manufacturing a thin film transistor will be described.

[First Embodiment] FIGS. 1 (a) to 1 (c)
2 (a) to 2 (c) and FIGS. 3 (a) and 3 (b)
7A to 7C show a method of manufacturing a thin film transistor according to the embodiment in the order of steps. First, as shown in FIG. 1A, a substrate, for example, a glass substrate 10 is formed by a sputtering method using argon (Ar) as a sputtering gas.
A gate electrode 11 made of a nickel (Ni) film having a thickness of 100 nm is selectively formed thereon. Next, an aluminum nitride film (AlN) 12 having a thickness of 100 nm is formed on the entire surface again by the sputtering method. Subsequently, a photoresist film 13 is formed on the entire surface. Next, back exposure 14 is performed using the gate electrode 11 as a mask, and the photoresist film 13 is patterned as shown in FIG. Next, the photoresist film 13 and the aluminum nitride film 12 on the gate electrode 11 are simultaneously etched and removed, thereby nitriding only the region on the glass substrate 10 where the gate electrode 11 is not formed as shown in FIG. The aluminum film 12 is left.

Next, as shown in FIG. 2A, a silicon nitride (SiNx) layer 15a having a thickness of, for example, 50 nm is formed on the entire surface by, for example, a sputtering method using helium (He) as a sputtering gas. A silicon dioxide (SiO ₂ ) layer 15b of 100 nm is formed to form an insulating film 15 having a laminated structure, and subsequently, a film thickness of, for example, 30 n is formed on the insulating film 15 by, for example, a PECVD method.
m amorphous silicon films 16 are continuously formed. After the amorphous silicon film 16 is formed, a photoresist is applied to the entire surface of the amorphous silicon film 16 as shown in FIG. 2B, and the photoresist is applied to the photoresist from the back side of the glass substrate 10. For example, exposure (backside exposure) 18 by g-line (wavelength 436 nm) is performed. At this time, the gate electrode 11 serves as a mask, and the photoresist film 17 having the same width as the gate electrode 11 is formed.
Are formed in a self-aligned manner. Subsequently, as shown in FIG. 2C, an n-type impurity 19, for example, phosphorus (P) is introduced into the amorphous silicon film 16 by, for example, plasma doping or ion doping using the photoresist film 17 as a mask. As a result, a source region 21a and a drain region 21b are formed as shown in FIG.
Subsequently, a laser beam 20 is irradiated from the substrate surface. The irradiation of the laser beam 20 causes the amorphous silicon film 16
Is melted, and then cooled to room temperature to crystallize the melted region, so that the source region 21 a and the drain region 21
Thus, a polycrystalline silicon film 21 having b is formed. Here, in the present embodiment, since the aluminum nitride film 12 having good thermal conductivity is formed in a region where there is no metal film (gate electrode 11), the maximum temperature reached on the film surface is almost the same as described above. And uniform crystallization can be performed over the entire film.

As the laser beam 20, it is preferable to use a laser beam having a wavelength that is absorbed by the amorphous silicon film 16, particularly a pulse laser beam using an excimer laser. Examples of the excimer laser include a pulse laser beam (wavelength 308 nm) using a XeCl excimer laser, a pulse laser beam (wavelength 248 nm) using a KrF excimer laser, and X
Pulse laser beam (wavelength 3) by eF excimer laser
50 nm).

Next, as shown in FIG. 3B, the source region 21 in the polycrystalline silicon film 21 is formed by a sputtering method using argon (Ar) as a sputtering gas, for example.
Electrodes 22a and 22b made of aluminum (Al) are formed on a and drain region 21b, respectively. Subsequently, the channel region 21c in the polycrystalline silicon film 21 is hydrogenated by performing plasma hydrogenation in hydrogen plasma to inactivate dangling bonds and the like.

As described above, according to the method for manufacturing a thin film transistor according to the present embodiment, when irradiating the laser beam 20 for crystallization, a region having no metal film (gate electrode 11) has good thermal conductivity in advance. Since the aluminum nitride film 12 is formed, crystallization can be uniformly performed over the entire surface of the substrate. Therefore, there is no fear of film destruction, and a large process margin can be obtained.

[Second Embodiment] FIGS. 4 (a) to 4 (c)
9A and 9B show a method of manufacturing a thin film transistor according to a second embodiment of the present invention in the order of steps. In the present embodiment, after a silicon dioxide film is formed on the amorphous silicon film 16 in the first embodiment, a resist film is formed on the silicon dioxide film, and then back exposure is performed. It is. 1 (a) to 1 (c), FIG.
3 (a) to 3 (c) and FIGS. 3 (a) and 3 (b) are denoted by the same reference numerals, and description thereof will be omitted.

That is, first, as shown in FIG. 4A, the steps up to the formation of the amorphous silicon film 16 are the first steps.
This is the same as the embodiment. After the formation of the amorphous silicon film 16, a silicon dioxide (SiO ₂ ) film 30 is formed by, for example, the PECVD method.
A photoresist is applied to the entire surface of the glass substrate 0, and the photoresist is subjected to exposure (backside exposure) 31 by, for example, g-line (wavelength: 436 nm) from the back side of the glass substrate 10. At this time, a photoresist film 32 having the same width as the gate electrode 11 is formed in a self-aligned manner using the gate electrode 11 as a mask. Further, as shown in FIG. 4B, after selectively etching the silicon dioxide film 30 using the patterned photoresist film 32 as a mask, the photoresist film 32 is removed. Then, using the silicon dioxide film 30 as a mask, an n-type impurity 33, for example, phosphorus (P) is introduced into the amorphous silicon film 16 by, for example, plasma doping or ion doping. Thus, a source region 21a and a drain region 21b are formed as shown in FIG. Subsequently, when a laser beam 34 is irradiated from the surface of the substrate, the amorphous silicon film 16 is melted by the irradiation of the laser beam 34, and then cooled to room temperature to crystallize the melted region, and the source region 21a and the drain region Polycrystalline silicon film 21 having 21b is formed. Subsequent steps are the same as in the first embodiment.

As described above, also in the method of manufacturing a thin film transistor according to the present embodiment, when irradiating the laser beam 34 for crystallization, a region having no metal film (gate electrode 11) is previously nitrided with good thermal conductivity. Aluminum film 12
Is formed, the crystallization can be performed uniformly over the entire surface of the substrate, and there is no fear of film destruction. Furthermore,
In the first embodiment, a photoresist is used as a mask for plasma doping or ion doping.
In some cases, the photoresist is altered by the impact of high-energy ions and is difficult to remove. In the present embodiment, since the silicon dioxide film 30 is used as a mask for plasma doping or ion doping, removal is easy.

[Third Embodiment] FIGS. 5 (a) to 5 (c)
FIGS. 6A and 6B show a method of manufacturing a thin film transistor according to the third embodiment of the present invention in the order of steps. In this embodiment mode, a gate electrode is formed over the aluminum nitride film in the first embodiment mode.

First, as shown in FIG. 5A, a film thickness of 100 nm is formed on the entire surface of the glass substrate 40 by, for example, a sputtering method using argon (Ar) as a sputtering gas.
Of the aluminum nitride film 41 is formed. Subsequently, for example, the aluminum nitride film 41 is also formed by the same sputtering method.
A gate electrode 42 made of a nickel (Ni) film having a thickness of 100 nm is selectively formed thereon. Then, for example, also the entire surface of the silicon nitride by a sputtering method using helium (He) as a sputtering gas (SiNx) layer 43a, continues the silicon dioxide (SiO ₂₎ layer 43b
Is formed to form an insulating film 43 having a laminated structure, and subsequently, an amorphous silicon film 44 is continuously formed on the insulating film 43 by, for example, a PECVD method.

After the formation of the amorphous silicon film 44, a photoresist film 45 is formed on the entire surface of the amorphous silicon film 44 by, for example, PECVD as shown in FIG. 5B. Next, the photoresist film 45 is patterned using the gate electrode 42 as a mask (backside exposure 46).
At this time, a photoresist film 45 having the same width as the gate electrode 42 is formed in a self-aligned manner, using the gate electrode 42 as a mask as shown in FIG. Subsequently, as shown in FIG. 5C, an n-type impurity 47, for example, phosphorus (P) is added to the amorphous silicon film 4 by, for example, plasma doping or ion doping using the photoresist film 45 as a mask.
Introduce to 4. As a result, a source region 49a and a drain region 49b are formed as shown in FIG. Subsequently, a laser beam 48 is irradiated from the substrate surface. The irradiation of the laser beam 48 melts the amorphous silicon film 44, and then cools to room temperature to crystallize the melted region, thereby forming a polycrystalline silicon film 49 having a source region 49a and a drain region 49b. .
Here, in this embodiment, since the aluminum nitride film 41 having good thermal conductivity is formed on the entire surface of the glass substrate 40, the maximum temperature reached on the film surface becomes almost the same as described above, and Can be uniformly crystallized.

Next, as shown in FIG. 6B, the source region 49 in the polycrystalline silicon film 49 is formed by a sputtering method using, for example, argon (Ar) as a sputtering gas.
Electrodes 50a and 50b made of aluminum (Al) are formed on a and drain region 49b, respectively. Subsequently, by performing plasma hydrogenation in hydrogen plasma, the channel region 49c in the polycrystalline silicon film 49 is hydrogenated to inactivate dangling bonds and the like.

As described above, also in the method of manufacturing the thin film transistor according to the present embodiment, when the laser beam 48 is irradiated for crystallization, the aluminum nitride film 41 having good thermal conductivity is formed on the entire surface of the glass substrate 40 in advance. As a result, crystallization can be performed uniformly over the entire surface of the substrate, and there is no fear of film destruction.

Although the present invention has been described with reference to the embodiment, the present invention is not limited to the above embodiment.
Various modifications are possible. For example, in the above embodiment, the metal film underlying the silicon film is described as a nickel film, but another metal film may be used. In the above embodiment, an aluminum nitride film is used as a film having good heat conductivity, but other films such as alumina (Al
₂ O ₃ ), titanium dioxide (TiO ₂ ), spinel, magnesium oxide, diamond-like carbon, or the like may be used. Further, in the above embodiment,
Although the description has been made using the silicon film as the amorphous semiconductor film,
Other amorphous films can be applied as long as they can be crystallized by irradiation with an energy beam. Further, in the second embodiment, a silicon nitride film or the like other than the silicon dioxide film may be used as a mask at the time of impurity doping.

[0038]

As described above, according to the method of manufacturing a semiconductor device according to any one of the first to seventh aspects, the metal film is substantially formed in the region adjacent to the metal film on the substrate or in the base region of the metal film. In order to crystallize an amorphous semiconductor film having a uniform film thickness, when irradiating an energy beam to crystallize an amorphous semiconductor film having the same thermal conductivity, the semiconductor film is irradiated with the same energy beam. Crystallization can be uniform over the entire surface. Therefore, there is no fear of film destruction,
This has the effect of increasing the process margin.

According to the method of manufacturing a semiconductor device according to the sixth and seventh aspects, the insulating film having substantially the same thermal conductivity as the metal film on the substrate is used. The heat generated can be efficiently dissipated to the substrate side, and the effect of preventing a temperature rise and maintaining a stable operation can be obtained.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a method of manufacturing a thin film transistor according to a first embodiment of the present invention for each process.

FIG. 2 is a cross-sectional view illustrating a process following the process in FIG.

FIG. 3 is a sectional view illustrating a step following FIG. 2;

FIG. 4 is a sectional view illustrating a method of manufacturing a thin film transistor according to a second embodiment of the present invention for each process.

FIG. 5 is a sectional view illustrating a method of manufacturing a thin film transistor according to a third embodiment of the present invention for each process.

FIG. 6 is a sectional view illustrating a step following FIG. 5;

FIG. 7 is a diagram for explaining a basic principle of the present invention;
(A) is a structure in which a metal film is formed under a silicon film,
(B) is a cross-sectional view showing a structure in which a metal film is not formed on a base of a silicon film.

FIG. 8 is a diagram showing parameters of each material used in a simulation for explaining the principle of FIG. 7;

FIG. 9 is a characteristic diagram for explaining a state of a temperature change of a silicon film when a laser beam is applied to the structure of FIG. 7A.

FIG. 10 is a characteristic diagram for explaining a state of a temperature change of a silicon film when a laser beam is applied to the structure of FIG. 7B.

FIG. 11 is a view for explaining the basic principle of the present invention. FIG. 11 shows a structure in which a metal film is not formed under a silicon film and a transparent insulating film having good thermal conductivity is formed on a substrate. FIG.

12 is a characteristic diagram showing the maximum temperature and crystallization time of a silicon film with respect to the thickness of a transparent insulating film having a good thermal conductivity in the structure of FIG.

13 is a characteristic diagram showing the maximum temperature of a glass substrate and the crystallization time of a silicon film with respect to the thickness of a transparent insulating film having a good thermal conductivity in the structure of FIG.

FIG. 14 is a cross-sectional view illustrating a structure and a manufacturing method of a conventional thin film transistor.

[Explanation of symbols]

10, 40: a glass substrate, 11, 42: a gate electrode,
12, 41 ··· aluminum nitride film, 13, 45 ··· photoresist film, 15, 43 ··· insulating film, 15a, 43a ··· silicon nitride layer, 15b and 43b ··· silicon dioxide layer, 1
6, 44 ... amorphous silicon film, 19, 47 ... n-type impurity, 20, 48 ... laser beam, 21, 49 ... polycrystalline silicon film, 21a, 49a ... source region, 21b, 49
b: drain region, 21c, 49c: channel region

 ──────────────────────────────────────────────────の Continuing from the front page (72) Inventor Setsuo Usui 6-7-35 Kita-Shinagawa, Shinagawa-ku, Tokyo Inside Sony Corporation

Claims (7)

[Claims] A step of selectively forming a metal film on a substrate; and a step of forming an insulating film having substantially the same thermal conductivity as the metal film in a region of the substrate where the metal film is not formed. Forming an amorphous semiconductor film having a uniform thickness on the metal film and the insulating film; and irradiating the amorphous semiconductor film with an energy beam to uniformly form the semiconductor film. A method of manufacturing a semiconductor device, comprising the steps of: A step of forming an insulating film on the substrate; a step of selectively forming a metal film having substantially the same thermal conductivity as the insulating film on the insulating film; Forming an amorphous semiconductor film having a uniform thickness on the film; and irradiating the amorphous semiconductor film with an energy beam to uniformly polycrystallize the semiconductor film. A method for manufacturing a semiconductor device, comprising: 3. The method according to claim 1, wherein the amorphous semiconductor film is a silicon film. 4. The method according to claim 1, wherein the energy beam is a beam generated by an excimer laser. 5. The method according to claim 1, wherein the thickness of the insulating film is determined according to the thickness of the metal film. 6. A step of forming a metal film as a gate electrode of a thin film transistor on a surface of a transparent substrate, and forming a transparent insulating film having substantially the same thermal conductivity as the metal film in a region other than the metal film on the transparent substrate. Forming a film, and after forming an insulating film on the metal film and the transparent insulating film,
Forming an amorphous semiconductor film having a uniform thickness on the insulating film; and selectively introducing impurities into a region other than the region corresponding to the metal film on the semiconductor film to form a source region and a drain. A method for manufacturing a semiconductor device, comprising: a step of forming a region; and a step of irradiating an energy beam to a semiconductor film on which the source region and the drain region are formed to be polycrystallized. 7. A step of forming a transparent insulating film on the surface of a transparent substrate; and forming a metal film having substantially the same thermal conductivity as the transparent insulating film on the transparent insulating film and serving as a gate electrode of the thin film transistor. Selectively forming, and after forming an insulating film on the metal film and the transparent insulating film,
Forming an amorphous semiconductor film having a uniform thickness on the insulating film; and selectively introducing impurities into a region other than the region corresponding to the metal film on the semiconductor film to form a source region and a drain. A method for manufacturing a semiconductor device, comprising: a step of forming a region; and a step of irradiating an energy beam to a semiconductor film on which the source region and the drain region are formed to be polycrystallized.