JP3311522B2 - Method for manufacturing semiconductor device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a semiconductor device .

[0002]

2. Description of the Related Art In recent years, an active matrix type liquid crystal display (LCD) has attracted attention as a high-quality display device. As a pixel driving element (pixel driving transistor) of the active matrix type LCD, a thin film transistor (hereinafter, referred to as a pixel) using a polycrystalline silicon film formed on a transparent insulating substrate as an active layer.
The development of polycrystalline silicon TFT (Thin Film Transistor) is underway.

Polycrystalline silicon TFTs have the advantage of higher mobility and higher driving capability than thin film transistors using amorphous silicon films as active layers (hereinafter referred to as amorphous silicon TFTs). Therefore, the polycrystalline silicon T
By using FT, a high-performance LCD can be realized, and not only a pixel portion (display portion) but also a peripheral driving circuit (driver) can be integrally formed on the same substrate (a driver-integrated LCD and a Called).

Conventional polycrystalline silicon TFTs have been formed using a high-temperature process of about 1000 ° C. (called a high-temperature process). The high-temperature process is based on LSI technology having a long technical accumulation over many years. Therefore, a polycrystalline silicon TFT formed by a high temperature process
(Referred to as a high-temperature polycrystalline silicon TFT) is excellent in element characteristics, reliability, and reproducibility. However, since the high temperature process has a high process temperature, quartz glass must be used for the substrate. Quartz glass becomes significantly more expensive as the size increases, and at the moment the size is limited,
The size of the substrate is limited. Therefore, the panel size of the LCD, which is cost-effective, is 2 or less, and can be used sufficiently for a viewfinder of a video camera or a liquid crystal projector, but cannot be used for direct viewing because the panel size is too small.

On the other hand, since an amorphous silicon TFT can be formed using a low-temperature process of 400 ° C. or less, ordinary glass can be used for the substrate. Normal glass is about 1/10 the price of quartz glass and has no size restrictions. However, high heat resistant glass commercially available for LCD (for example, Corning Inc.
“7059”) has a heat-resistant temperature of only about 600 ° C.

[0006] Therefore, a polycrystalline silicon TFT is mounted on a substrate so that ordinary glass (high heat resistant glass) can be used for the substrate.
It is required to form the substrate by using a low-temperature process of about lower than about ° C. (called a low-temperature process). A polycrystalline silicon TFT formed by a low temperature process is called a low temperature polycrystalline silicon TFT. The problem with low-temperature polycrystalline silicon TFTs is the method of forming a polycrystalline silicon film to be an active layer,
There are a method for forming a gate insulating film, a method for forming source / drain regions, and the like.

There are various methods for forming a silicon thin film (CVD method, vapor deposition method, sputtering method, etc.). In any case, when a silicon thin film is formed on a glass substrate at a low temperature, the film becomes amorphous. Become. As a method for polycrystallizing the amorphous silicon film, there are a solid phase growth method and a melt recrystallization method.

In the solid phase growth method, an amorphous silicon film is formed at 600 ° C.
This is a method in which a polycrystalline silicon film is obtained by performing a long-term heat treatment before and after to polycrystallize a solid. The melt recrystallization method is a method in which only the surface of an amorphous silicon film is melted and the substrate temperature is kept at 600 ° C. or less while recrystallization is performed. The laser annealing method and RTA (Rapid Therma
l Annealing) method. The laser annealing method is a method in which a surface of an amorphous silicon film is irradiated with a laser to be heated and melted. The RTA method is a method in which a surface of an amorphous silicon film is irradiated with lamp light such as a tungsten lamp or a xenon lamp to be heated and melted.

[0009]

The solid-phase growth method has the following problems. 1) Since there is no method for controlling the crystal grain size of polycrystalline silicon, it is difficult to form a polycrystalline silicon film having a uniform crystal grain size over the entire substrate.

[0010] Crystal growth in an amorphous silicon film mainly occurs at the interface between the amorphous silicon film and the substrate, but often occurs in the amorphous silicon film. That is, it is uncertain from which location in the amorphous silicon film the crystal growth will occur. Therefore, the crystal grain size becomes small in the place where the crystal growth occurs densely, and the crystal grain size becomes large in the place where the crystal growth occurs sparsely, so that the uniformity of the crystal grain size decreases.

The polycrystalline silicon film has a higher field effect mobility as the crystal grain size is larger. If a polycrystalline silicon film having a higher field effect mobility is used as an active layer, the polycrystalline silicon T
The element characteristics of the FT are improved. Therefore, the device characteristics of a polycrystalline silicon TFT formed at a place where the crystal grain size is large in the polycrystalline silicon film are excellent, while the device characteristics of a polycrystalline silicon TFT formed at a place where the crystal grain size is small are excellent. Becomes inferior. That is, if the uniformity of the crystal grain size in the polycrystalline silicon film is reduced, the device characteristics of the polycrystalline silicon TFT vary. As a result, LC
A uniform image cannot be displayed over the entire panel of D.

The purpose of employing the low-temperature process is to provide an LCD having a large panel size at a low cost using a normal glass substrate. Since the decrease in the uniformity of the crystal grain size in the polycrystalline silicon film becomes remarkable as the size of the substrate increases, it becomes a problem particularly in an LCD having a large panel size.

2) In order for the amorphous silicon film to be completely polycrystallized (ie, to obtain a crystallization rate of 100%),
Long time heat treatment such as time is required. Therefore, the throughput decreases. Further, even when high heat-resistant glass for LCD is used, heat treatment is performed for a long time near the heat-resistant temperature limit, so that the substrate is easily damaged such as distortion. To shorten the heat treatment time,
The heat treatment may be performed at as high a temperature as possible within the range of the heat resistant temperature of the substrate. However, when the processing temperature is increased, the crystallization speed can be increased, but the crystal grain size is reduced. As a result, the element characteristics of the polycrystalline silicon TFT are deteriorated over the entire surface of the LCD panel, and the image quality is deteriorated. In particular, in a driver-integrated LCD, a polycrystalline silicon TFT used for a peripheral drive circuit is required to have higher element characteristics than a polycrystalline silicon TFT used for a pixel portion. Therefore, when the crystal grain size of the polycrystalline silicon film becomes small, it becomes impossible to realize a driver-integrated LCD.

In the laser annealing method, the heat treatment time is shorter than that in the solid phase growth method, so that the substrate is not damaged and the throughput is not reduced. But,
At present, there is no large-diameter laser device capable of processing a large-sized substrate at a time, and thus it is necessary to scan a laser spot over the entire surface of the substrate. For this reason, a portion where the laser spot is irradiated can overlap, and the amorphous silicon film is irradiated with the laser spot twice and is heated and melted twice. There are places that are only heated and melted. Then, the crystal grain size becomes small in the place where the heating and melting are performed twice, and the crystal grain size becomes large in the place where the heating and melting are performed only once, so that the uniformity of the crystal grain size is reduced. Therefore, also in the laser annealing method, similarly to the solid phase growth method, there is a problem that it is difficult to form a polycrystalline silicon film having a uniform crystal grain size over the entire substrate. Therefore, in the laser annealing method,
By reducing the scanning speed of the laser spot to reduce the overlapping portion as much as possible, or by irradiating the laser spot multiple times and averaging the overlapping portion of the laser spot, a method of improving the uniformity of the crystal grain size has been taken. I have. But,
Still, it is difficult to obtain sufficient uniformity.

Also in the RTA method, the heat treatment time is shorter than that in the solid phase growth method, so that the substrate is not damaged and the throughput is not reduced. In addition, R
In the TA method, since the entire surface of the substrate can be irradiated with the lamp light all at once, the entire amorphous silicon film can be uniformly heated and melted. Therefore, a polycrystalline silicon film having a uniform crystal grain size can be formed over the entire substrate. However, if the irradiation with the lamp light is continued for an excessively long time, the entire substrate is excessively heated and the substrate is damaged. Therefore, the irradiation time with the lamp light needs to be as short as possible. However, when the irradiation time of the lamp light is shortened, the heat treatment time of the amorphous silicon film is also shortened, and the crystal grain size of the polycrystalline silicon film cannot be increased.
That is, although the RTA method can form a polycrystalline silicon film having a uniform crystal grain size over the entire substrate, there is a problem that the crystal grain size cannot be increased.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and is intended to provide a polycrystalline silicon film having a large crystal grain size.
To provide a method for manufacturing a semiconductor device having
I do.

[0017]

[0018]

[0019]

[Means for Solving the Problems]

[0020]

[0021]

According to a first aspect of the present invention, there is provided a step of forming a polycrystalline silicon film by melting and recrystallizing the amorphous silicon film by irradiating the amorphous silicon film with a lamp light a plurality of times by the RTA method. The gist is to have

[0023]

[0024]

According to a second aspect of the present invention, there is provided a light-reflecting film on a substrate, a film made of a material having a lower thermal conductivity than the substrate,
A step of forming at least one of films made of a material that absorbs light, a step of forming an amorphous silicon film on the film, and a method of applying a plurality of lamp lights to the amorphous silicon film by RTA. And forming a polycrystalline silicon film by melting and recrystallizing the amorphous silicon film by irradiating the amorphous silicon film twice.

[0026]

[0027]

[0028]

[0029]

[0030]

[0031]

[Action]

[0032]

[0033]

According to the first aspect of the present invention, since the latent heat in the heated and melted amorphous silicon film is less likely to flow out and the solidification rate is reduced, a polycrystalline silicon film having a large crystal grain size is formed. Can be done .

According to the second aspect of the present invention, the amorphous silicon
In addition to being able to efficiently heat and melt the recon film,
Latent heat in heat-melted amorphous silicon film hardly leaks out
As a result, the solidification rate is reduced, so that a polycrystalline silicon film having a large crystal grain size can be formed.

[0036]

[0037]

[0038]

[0039]

[0040]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A manufacturing method according to an embodiment of the present invention will be described below with reference to FIGS.

Step 1 (see FIG. 1A): A transparent insulating substrate 1 (quartz glass, high heat-resistant glass) is formed on a transparent insulating substrate 1
A film that reflects the lamp light of the device (hereinafter, referred to as a reflection film) 2
To form The reflective film 2 may be made of any material as long as it has a property of reflecting lamp light.
Copper, gold, silver, platinum, etc.), high melting point metal (titanium, tantalum, molybdenum, tungsten, etc.), metal silicide, etc. are used.
Method D is used. Atmospheric pressure CVD method, reduced pressure C
There are a VD method, a plasma CVD method, a photo-excitation CVD method and the like. The PVD method includes a vapor deposition method and EB (Electron Beam).
) Vapor deposition, MBE (Molecular Beam Epitaxy), and sputtering. The film thickness of the reflection film 2 is set to a film thickness necessary and sufficient to sufficiently reflect the lamp light in accordance with the material of the reflection film 2 and the wavelength of the lamp light.

Step 2 (see FIG. 1B): A buffer film 3 is formed on the reflection film 2. The buffer film 3 is made of R
This is provided to prevent the reaction between the reflective film 2 and the polycrystalline silicon film in the TA process. Therefore, RTA
When the reflective film 2 is formed of a material that does not react with the polycrystalline silicon film in the processing, the buffer film 3 may be omitted. As a material of the buffer film 3, a silicon oxide film, a silicon nitride film, a silicon oxynitride film (SiO 2
_{xN y} ) and the like, and a CVD method or a PVD method is used for the formation.

Step 3 (see FIG. 1C); buffer film 3
An amorphous silicon film 4 (thickness: 500 Å) is formed thereon.
The amorphous silicon film 4 is formed by a CVD method or a PVD method, and the following method is generally used.

Method using low-pressure CVD; low-pressure CVD
In order to form a silicon film by the method, monosilane (Si
H ₄ ) or thermal decomposition of disilane (Si ₂ H ₆ ) is used. In this case, when the processing temperature is 550 ° C. or less,
Above ℃, it becomes polycrystalline.

Method using plasma CVD method: In order to form an amorphous silicon film by the plasma CVD method, thermal decomposition of monosilane or disilane in plasma is used.
In this case, the reaction is promoted by adding hydrogen at a treatment temperature of about 300 ° C.

Step 4 (see FIG. 1D): The amorphous silicon film 4 is polycrystallized to form a polycrystalline silicon film 5 by performing an RTA process. FIG. 3 shows a schematic configuration of an RTA apparatus for performing an RTA process. RTA device 1
1 includes a preheating chamber A, a processing chamber B, and a cooling chamber C. A stage 12 is provided across each of the rooms A to C,
The sample (substrate 1) to be subjected to the RTA process moves on the stage 12 at a constant speed. Substrate 1 in preheating chamber A
Is preheated. Inside the processing chamber B, a lamp device 15 composed of a cylindrical lamp body (tungsten lamp or xenon lamp) 13 and a reflector 14 (light collecting optical system)
Are arranged at equal intervals along the moving direction of the substrate 1. The lamp light emitted from the lamp body 13 is reflected by the reflector 14 and is emitted to the surface of the substrate 1 (the surface of the amorphous silicon film 4). The substrate 1 is cooled in the cooling chamber C.

When the lamp light is applied, the surface of the amorphous silicon film 4 is heated and melted, and subsequently, when cooled, solidified and crystallized to form the polycrystalline silicon film 5. Here, since the lamp light is collectively applied to the entire surface of the amorphous silicon film 4, the entire amorphous silicon film 4 can be uniformly heated and melted. Therefore, a polycrystalline silicon film 5 having a uniform crystal grain size over the entire substrate 1 can be formed.

At this time, the amorphous silicon film 4 absorbs only a small part of the lamp light, and most of the lamp light passes through the amorphous silicon film 4. The lamp light transmitted through the amorphous silicon film 4 is reflected by the reflection film 2 and returned into the amorphous silicon film 4 again. Therefore, the use efficiency of the lamp light is increased as compared with the case where the reflective film 2 is not provided, and the heating and melting of the amorphous silicon film 4 can be performed efficiently. For example, when a reflective film 2 made of silver formed by a vapor deposition method is used and a xenon lamp is used for the lamp body 13, the reflective film 2 can reflect 98% or more of the entire wavelength of the xenon arc spectrum. Further, since the lamp light is reflected by the reflection film 2, the substrate 1 can be prevented from being heated by the lamp light transmitted through the amorphous silicon film 4.

When each lamp device 15 emits light sequentially according to the moving speed of the substrate 1, the amorphous silicon film 4
Irradiation of the lamp light is performed a plurality of times. Here, substrate 1
By adjusting the moving speed of the lamp device and the timing of light emission of each lamp device 15, it is possible to irradiate the amorphous silicon film 4 with the lamp light a plurality of times in a very short time. As a result, the latent heat in the heated and melted amorphous silicon film 4 is less likely to flow out to the substrate 1 and the solidification rate is prevented from increasing.

As described above, by providing the reflective film 2, the use efficiency of the lamp light is increased, the amorphous silicon film 4 is efficiently melted, and the lamp light irradiation is performed a plurality of times in a very short time. Thereby, the solidification rate of the amorphous silicon film 4 can be reduced. As a result, the crystal grain size of polycrystalline silicon film 5 can be increased. Further, by performing the irradiation of the lamp light a plurality of times in an extremely short time, the entire substrate 1 is not overheated, and the substrate 1 can be prevented from being damaged such as distortion. Further, since the time required for the RTA treatment is much shorter than the heat treatment time in the solid phase growth method, the throughput does not decrease.

However, regarding the number of times of irradiation of the amorphous silicon film 4 with the lamp light and the irradiation time per one time, the characteristics (wavelength, light intensity, etc.) of the lamp light (the light projected by the lamp device 15) and non- It is necessary to optimize in consideration of the properties (light absorption coefficient) of the crystalline silicon film 4.

As described above, according to this embodiment, a polycrystalline silicon film 5 having a uniform crystal grain size and a large grain size can be obtained in a short time by a low-temperature process. Therefore, not only can the high heat resistant glass be used for the substrate 1, but also the heat resistant temperature can be reduced.

The formation of the amorphous silicon film 4 is performed under reduced pressure CV.
When the method D is used, the quality of the polycrystalline silicon film 5 is improved, but the processing temperature is increased. Therefore, quartz glass must be used for the substrate 1. On the other hand, when the plasma CVD method is used, although the film quality of the polycrystalline silicon film 5 is inferior to that of the low pressure CVD method, the processing temperature is low, so that high heat resistant glass can be used for the substrate 1. Therefore, any method may be selected according to the purpose.

Step 5 (see FIG. 2); polycrystalline silicon film 5
-Type polycrystalline silicon TF using Si as active layer
Form T. First, a gate insulating film 6 (thickness: 1000 °) is formed on the polycrystalline silicon film 5. There are the following methods for forming the gate insulating film 6.

[1] A method of forming a silicon oxide film by using an oxidation method; a high-temperature oxidation method (a dry oxidation method using dry oxygen, a wet oxidation method using wet oxygen, an oxidation method in a steam atmosphere), and a low temperature method. An oxidation method (an oxidation method in a high-pressure steam atmosphere, an oxidation method in an oxygen plasma), an anodic oxidation method, or the like is used.

Among them, a high-temperature oxidation method of about 900 to 1200 ° C. is generally used. [2] Silicon oxide film, silicon nitride film,
A method for forming a silicon oxynitride film; a CVD method or a PVD method is used. There is also a method of combining each film to form a multilayer structure.

For the formation of the silicon oxide film by the CVD method, thermal decomposition of monosilane or disilane, thermal decomposition of organic oxysilane (such as TEOS), hydrolysis of silicon halide, and the like are used. For forming a silicon nitride film by the CVD method, ammonia and dichlorosilane (SiH ₂ C
l ₂ ), thermal decomposition of ammonia and monosilane, nitrogen and monosilane, and the like. The silicon oxynitride film has characteristics of both an oxide film and a nitride film, and can be formed by introducing a small amount of nitrogen oxide (N ₂ O) into a system for forming a silicon nitride film by a CVD method.

The method for forming the gate insulating film 6 includes a high-temperature process and a low-temperature process. In high temperature processes,
Generally, the high temperature oxidation method described above is used. On the other hand, in the low-temperature process, the oxidation method or the deposition method in oxygen plasma described above is generally used, and the processing temperature is suppressed to about 600 ° C. or less.

Next, a gate electrode 7 is formed on the gate insulating film 6 and patterned into a desired shape. Gate electrode 7
As the material of the metal, polycrystalline silicon doped with impurities (doped polysilicon), metal silicide, polycide, a high-melting-point metal simple substance, other metals, and the like are used, and a CVD method or a PVD method is used for the formation thereof. .

Subsequently, source / drain regions 8 are formed in the polycrystalline silicon film 5 using the gate electrode 7 as a mask by a self-alignment technique. The method for forming the source / drain regions 8 also includes a high-temperature process and a low-temperature process. In the high-temperature process, high-temperature heat treatment is performed after ion implantation of impurities to activate the impurities. In the low-temperature process, the ion implantation and the activation are simultaneously performed without providing a special heat treatment step by irradiating an ion shower with a mixed gas of phosphine gas (PH ₃ ) or diborane gas (B ₂ H ₆ ) and hydrogen gas. Do. In the low-temperature process, there is a method of activating the impurities by performing a heat treatment for several hours to several tens of hours at a low temperature of about 600 ° C. or less after ion implantation of the impurities. When high heat-resistant glass is used for the substrate 1, a low-temperature process must be used not only when forming the polycrystalline silicon film 5 but also when forming the gate insulating film 6 and when forming the source / drain regions 8.

Then, an interlayer insulating film 9 is formed on the entire surface of the device. As a material of the interlayer insulating film 9, a silicon oxide film, a silicate glass, a silicon nitride film, or the like is used, and a CVD method or a PVD method is used for the formation thereof.

Thereafter, a contact hole 10 for contacting the source / drain region 8 is formed in the interlayer insulating film 9, and a source / drain electrode 11 is formed, thereby completing a polycrystalline silicon TFT.

As described above, according to this embodiment, since the crystal grain size of the polycrystalline silicon film 5 is uniform and large,
In addition, it is possible to form a polycrystalline silicon TFT having excellent device characteristics without variation in device characteristics over the whole. If such a polycrystalline silicon TFT is used as a pixel driving element of an active matrix LCD, L
A uniform and high-quality image can be displayed on the entire surface of the CD panel. Further, a polycrystalline silicon TFT having excellent element characteristics can be used not only as a pixel driving element but also as a peripheral driving circuit, so that a driver-integrated LCD can be embodied. Further, since the polysilicon film 5 is formed in a short time, the throughput of the polysilicon TFT and the LCD can be improved.

In this embodiment, the gate insulating film 6
If a low-temperature process is used for forming the source / drain regions 8, a large-panel LCD can be provided at low cost by using high heat-resistant glass for the substrate 1.

In an LCD, when light strikes a polycrystalline silicon TFT as a pixel driving element, the element characteristics of the polycrystalline silicon TFT change, which may cause performance degradation or malfunction. In this embodiment, the reflection film 2
Is provided, the light is prevented from shining on the polycrystalline silicon TFT from the substrate 1 side, and the performance degradation and malfunction of the LCD can be prevented.

The above embodiment may be modified as follows, and the same operation and effect can be obtained in such a case. (1) After forming the reflective film 2, unnecessary portions of the reflective film 2 are removed by etching by a photolithography process, and islands are formed only in portions where the reflective film 2 is required.

(2) The reflection film 2 is formed of a light-absorbing film (a film that absorbs light having a wavelength that is not absorbed by the amorphous silicon film 4, or a light that is transmitted without being absorbed by the amorphous silicon film 4). (Hereinafter, referred to as a light-absorbing film). In this case, the lamp light transmitted through the amorphous silicon film 4 is absorbed by the light absorbing film, and heat is stored in the light absorbing film and the amorphous silicon film 4 by heating the light absorbing film. As a result, the outflow of latent heat from the amorphous silicon film 4 is reduced, and the heating and melting of the amorphous silicon film 4 can be performed efficiently. As a material of the light absorbing film, titanium oxide, tantalum oxide, titanium nitride, aluminum oxide, or the like is used, and a CVD method or a PVD method is used for the formation thereof.

Although light in the visible light region and its vicinity is absorbed by many substances including silicon, the amorphous silicon thin film formed on the transparent insulating substrate absorbs only a small part of radiation. Most light is transmitted. Therefore, as a material of the light absorbing film, a silicon-based compound (amorphous silicon, amorphous silicon including microcrystal, polycrystalline silicon, silicon oxide, silicon nitride, silicon oxynitride, silicon carbide, etc.) is used. The CVD method or the PVD method is used for the formation.

(3) The reflective film 2 is replaced with a film made of a material having a lower thermal conductivity than the substrate 1 (hereinafter, referred to as a low thermal conductive film). In this case, the amorphous silicon film 4 is
The amount of latent heat flowing out of the amorphous silicon film 4 is reduced, and the heating and melting of the amorphous silicon film 4 can be performed efficiently. Silicon oxide is used as the material of the low heat conductive film, and the formation thereof is performed by CVD.
Method, PVD method, LPD (liquid phase growth) method, coating method and the like are used.

(4) The reflection film 2, the light absorption film and the low thermal conductivity film are combined respectively. For example, a low heat conductive film is formed on the reflective film 2. Further, a light absorbing film is formed on the reflective film 2. Further, a light absorbing film is formed on the reflective film 2 and a low heat conductive film is formed on the light absorbing film. In these cases, the effects of the present invention can be further enhanced by the synergistic action of each film.

(5) The present invention is applied not to the RTA method but to the laser annealing method. In this case, by irradiating the surface of the amorphous silicon film 4 with a laser spot (laser light) a plurality of times, it becomes difficult for the latent heat in the heated and melted amorphous silicon film 4 to flow out to the substrate 1. The solidification rate is prevented from increasing.

(6) In the manufacturing process of the polycrystalline silicon TFT, after the polycrystalline silicon film 5 is formed, hydrogenation is performed to improve the element characteristics of the polycrystalline silicon TFT. Hydrogenation is a method in which hydrogen atoms are bonded to crystal defect portions of polycrystalline silicon to reduce defects, stabilize the crystal structure, and increase field-effect mobility.

(7) The portion corresponding to the channel region of the polycrystalline silicon film 5 is doped with impurities to control the threshold voltage (Vth) of the polycrystalline silicon TFT. In a polycrystalline silicon TFT formed by the melt recrystallization method, the threshold voltage of an n-channel transistor tends to shift in the depletion direction, and the threshold voltage of a p-channel transistor tends to shift in the enhancement direction. In particular,
When the hydrogenation treatment is performed, the tendency becomes more remarkable. In order to suppress the shift of the threshold voltage, the channel region may be doped with an impurity.

(8) The present invention is applicable not only to a planar type but also to a polycrystalline silicon TFT having any structure such as an inverted planar type, a staggered type and an inverted staggered type. (9) The present invention is applied not only to polycrystalline silicon TFTs but also to insulated gate semiconductor devices in general. In addition, photoelectric conversion elements such as solar cells and optical sensors, bipolar transistors, and static induction transistors (SITs)
The present invention is applied to any semiconductor device using a polycrystalline silicon film such as tor).

(10) The insulating substrate 1 is replaced with an insulating layer such as a ceramic substrate or a silicon oxide film, and is applied to a contact type image sensor or a three-dimensional IC instead of an LCD. (11) The polycrystalline silicon TFT is used for a charge transfer element in a memory cell of a dynamic RAM (DRAM) or a load element in a memory cell of a static RAM (SRAM) instead of an LCD.

Although the embodiments have been described above, the technical ideas other than the claims that can be grasped from the embodiments are described below.
The effects are described below together with those effects .

[0077]

[0078]

(A) forming a polycrystalline silicon film formed by the method for manufacturing a semiconductor device according to claim 1 on a substrate, forming a gate insulating film under the polycrystalline silicon film, Forming a gate electrode under the insulating film.

In this manner, an inverted staggered or inverted planar type polycrystalline silicon TFT can be obtained .

(B) In the method of manufacturing a semiconductor device according to the second aspect , a film reflecting light, a film made of a material having a lower thermal conductivity than the substrate, and absorbing light having a wavelength not absorbed by silicon are formed on the substrate. Manufacturing a semiconductor device in which a step of forming a buffer film is added between a step of forming at least one of films formed of materials to be formed and a step of forming an amorphous silicon film on the film Method.

In this way, when the amorphous silicon film is melt-recrystallized to form a polycrystalline silicon film, it is possible to prevent the film from reacting with the polycrystalline silicon film.

Incidentally, in the present specification, the members according to the constitution of the present invention are defined as follows. (A) The substrate includes not only a substrate made of any insulating material such as quartz glass, high heat-resistant glass, high heat-resistant resin, and ceramics, but also a conductive substrate such as a metal provided with an insulating layer such as a silicon oxide film on the surface. Shall be included.

(B) The thin film transistor includes not only a planar type but also an inverted planar type, a staggered type, an inverted staggered type and the like. (C) As the gate insulating film, not only a silicon oxide film formed by a high temperature process such as a high temperature thermal oxidation method but also a plasma oxidation method, a normal pressure CVD method, a low pressure CVD method, a plasma CVD method, an ECR plasma CVD method , Photo-excited CVD,
It also includes a silicon oxide film, a silicon nitride film, a silicon oxynitride film, and the like formed by a low-temperature process such as an evaporation method or a sputtering method.

[0085]

According to the present invention, a crystal grain having a large crystal grain size is formed.
A method for manufacturing a semiconductor device having a crystalline silicon film can be provided.

[0086]

[0087]

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view for explaining a manufacturing method according to an embodiment.

FIG. 2 is a schematic cross-sectional view for explaining a manufacturing method according to one embodiment.

FIG. 3 is a schematic configuration diagram of an RTA apparatus.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Insulating substrate 3 Reflective film 4 Amorphous silicon film 5 Polycrystalline silicon film 6 Gate insulating film 7 Gate electrode 8 Source region or drain region (source / drain region) 9 Interlayer insulating film 10 Contact hole 11 Source electrode or drain electrode ( Source / drain electrodes)

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI H01L 29/786 (56) References JP-A-5-121350 (JP, A) JP-A-5-218367 (JP, A) JP-A-4-33327 (JP, A) JP-A-2-162772 (JP, A) JP-A-3-181120 (JP, A) JP-A-63-10516 (JP, A) JP-A-62-37922 JP, A) JP-A-61-231714 (JP, A) JP-A-58-206163 (JP, A) JP-A-6-140325 (JP, A) JP-A-6-132219 (JP, A) (58) ) Surveyed field (Int.Cl. ⁷ , DB name) H01L 21/20

Claims (2)

(57) [Claims] 1. A method of manufacturing a semiconductor device, comprising: forming a polycrystalline silicon film by melting and recrystallizing an amorphous silicon film by irradiating an amorphous silicon film with lamp light a plurality of times by an RTA method. Method. 2. A step of forming at least one of a film that reflects light, a film made of a material having lower thermal conductivity than the substrate, and a film made of a material that absorbs light, on the substrate, Forming an amorphous silicon film on the substrate, and irradiating the amorphous silicon film with lamp light a plurality of times by the RTA method to melt and recrystallize the amorphous silicon film to form a polycrystalline silicon film And a method for manufacturing a semiconductor device.