JP2004087583A - Semiconductor device, its manufacturing method and heat treatment method of thin film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a semiconductor device, its manufacturing method and a thin film heat treatment method for suppressing fear that thermal damage may be imposed to a conductive film or a substrate when various kinds of thin films such as a semiconductor thin film are instantaneously annealed by using light of high intensity and capable of improving the characteristics of these thin films. <P>SOLUTION: In an n-channel type polycrystalline silicon TFT 1 of LDD (lightly doped drain) structure, a ground protection film 3, a polycrystalline silicon film 4 and a gate insulating film 5 are successively formed on a glass substrate 2, a gate electrode 6 is formed on a channel area 4a of the polycrystalline silicon film 4 through the gate insulating film 5 and a reflection film 7 consisting of any one of aluminium, aluminium alloy, silver, and silver alloy is formed on a titanium nitride film 6c to be the outermost surface of the gate electrode 6. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a semiconductor device and a method for manufacturing the same and a method for heat-treating a thin film, in particular, when various thin films such as a semiconductor thin film having a conductive film are subjected to instantaneous annealing using high-intensity light, The present invention relates to a semiconductor device that does not cause thermal damage to a conductive film or a substrate and that can improve the characteristics of various thin films, a method of manufacturing the same, and a method of heat treating the thin film.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, as a display device such as a liquid crystal device (LCD) or an electroluminescence (EL) device, in order to drive a large number of pixels arranged in a matrix for each pixel, a thin film transistor (TFT) which is a thin film semiconductor device is provided for each pixel. ) Is known as an active matrix type display device. As a TFT used for such an application, a polycrystalline silicon TFT using a polycrystalline silicon film for a semiconductor layer is widely used. Further, as a manufacturing process of a polycrystalline silicon TFT, a low-temperature process capable of manufacturing an active layer at a relatively low temperature is known.
Examples of the low-temperature process include, for example, JP-A-59-75670 and JP-A-05-335482.
[0003]
Hereinafter, a method for forming an active layer of a polycrystalline silicon TFT employing a low-temperature process will be briefly described.
First, a base protective film (buffer film) made of a silicon oxide film or the like is formed on the entire surface of a glass substrate, and an amorphous silicon film as a semiconductor film is formed on the entire surface of the base protective film. Next, the amorphous silicon film is irradiated with laser light using an excimer laser that emits laser light having a wavelength of 308 nm or 249 nm, and laser annealing is performed. By this laser annealing, the amorphous silicon film is polycrystallized and becomes a polycrystalline silicon film.
[0004]
After patterning the polycrystalline silicon film into a predetermined active layer shape, a gate insulating film made of a silicon oxide film or the like is formed on the entire surface of the glass substrate including the polycrystalline silicon film. A gate electrode (conductive film) of low resistance and high reflectivity such as aluminum or an aluminum alloy is formed thereon. Then, impurities are implanted into the polycrystalline silicon film using the gate electrode as a mask. Then, using the gate electrode as a mask, the polycrystalline silicon film is irradiated with high-intensity light using an excimer laser or a flash lamp that emits high-intensity light equivalent to the excimer laser. Activate impurities in the film. In this case, since most of the light irradiated to the gate electrode is reflected, there is no possibility that the gate electrode is thermally damaged.
As described above, for example, a semiconductor thin film that functions as an active layer at a relatively low temperature of 600 ° C. or less can be obtained, and a high-performance TFT can be obtained while using the same relatively inexpensive glass substrate as an amorphous silicon TFT. it can.
[0005]
[Problems to be solved by the invention]
By the way, in recent years, miniaturization and high quality have been demanded for display devices, and in a low-temperature process, miniaturization of electrodes and low resistance have been required. Therefore, for example, in a wiring such as a gate electrode or a data line, a conductive film having a laminated structure in which a conductive film such as aluminum or an aluminum alloy is sandwiched between thin films such as titanium or titanium nitride has been used to prevent disconnection due to miniaturization. ing.
However, when the conductive film having this laminated structure is used as a gate electrode, impurities in the polycrystalline silicon film are reduced because the outermost surface of the gate electrode is made of a material that absorbs much light such as titanium or titanium nitride. When activated, titanium or titanium nitride absorbs light and becomes high temperature, so that aluminum (melting point: 660 ° C.) which is an electrode material may be melted, and thus the conductive film is thermally damaged. There is a problem that there is a fear.
[0006]
In order to further reduce the resistance of wiring such as a gate electrode and a data line, a conductive film having a single-layer structure using a copper thin film has been used. For example, a technique described in JP-A-59-75670 is known.
However, also in this case, since the gate electrode is made of copper (melting point: 1083 ° C.), which is a material that absorbs much light, when the intensity of light for activating impurities is strong, copper is used. There is a problem that the surface may be melted, and thus the conductive film may be thermally damaged.
[0007]
The present invention has been made in view of the above circumstances, and may cause thermal damage to a conductive film or a substrate even when various thin films such as a semiconductor thin film are subjected to instantaneous annealing using high-intensity light. It is an object of the present invention to provide a semiconductor device which does not have any problems and can improve the characteristics of various thin films such as a semiconductor thin film, a method of manufacturing the same, and a method of heat treating the thin film.
[0008]
[Means for Solving the Problems]
In order to solve the above problems, the present invention employs the following semiconductor device, a method for manufacturing the same, and a heat treatment method for a thin film.
That is, the semiconductor device of the present invention is a semiconductor device including a conductive film at a predetermined position on a semiconductor thin film, wherein a reflective film is formed on the conductive film.
[0009]
In this semiconductor device, the reflection film is formed on the conductive film, so that when the impurity activation process for activating the impurities in the semiconductor thin film by light irradiation is performed, the reflection film reflects the irradiated light. In addition, thermal damage to the conductive film due to light irradiation is prevented. Thereby, the characteristics of the semiconductor thin film are improved, and the reliability as a semiconductor device is improved.
[0010]
The semiconductor thin film is characterized in that impurities in the semiconductor thin film are activated by light irradiation.
The reflective film has an average reflectance to visible light of 50% or more.
[0011]
A method for manufacturing a semiconductor device according to the present invention is a method for manufacturing a semiconductor device comprising a conductive film on a semiconductor thin film, the method comprising: forming a semiconductor thin film; forming a conductive film on a predetermined position on the semiconductor thin film. A conductive film forming step of forming a film, a reflective film forming step of forming a reflective film that reflects light on the conductive film, and irradiating the semiconductor thin film and the reflective film with light to remove impurities in the semiconductor thin film. And an activating step of activating impurities.
[0012]
In this manufacturing method, a reflective film for reflecting light is formed on the conductive film in the reflective film forming step, and the semiconductor thin film and the reflective film are irradiated with light in the impurity activation step to activate impurities in the semiconductor thin film. Become In this case, since the outermost reflective film reflects light to prevent light from entering the conductive film, the conductive film is not thermally damaged. Thus, a semiconductor device with improved characteristics can be easily obtained.
[0013]
The impurity activation step is a step of activating the impurities in the semiconductor thin film by irradiating a laser beam or a lamp beam.
[0014]
Another method for manufacturing a semiconductor device according to the present invention is a method for manufacturing a semiconductor device including a gate electrode on a semiconductor thin film, the method comprising: forming a semiconductor thin film, forming a semiconductor thin film; A gate electrode forming step of forming a gate electrode, a reflective film forming step of forming a reflective film that reflects light on the gate electrode, and irradiating the semiconductor thin film and the reflective film with light; And an impurity activating step of activating the impurity.
[0015]
Still another method for manufacturing a semiconductor device according to the present invention is a method for manufacturing a semiconductor device comprising a gate electrode on a semiconductor thin film, the method comprising: forming a semiconductor thin film on a substrate; A gate insulating film forming step of forming a gate insulating film thereon, a gate electrode forming step of forming a gate electrode at a predetermined position on the gate insulating film, and forming a reflective film for reflecting light on the gate electrode Forming a source / drain region in the semiconductor thin film by ion-implanting an impurity into the semiconductor thin film through the gate insulating film using the gate insulating film as a mask, and Irradiating the semiconductor thin film and the reflection film with light to activate an impurity in the semiconductor thin film.
[0016]
In these manufacturing methods, a reflective film for reflecting light is formed on a gate electrode in a reflective film forming step, and the semiconductor thin film and the reflective film are irradiated with light in an impurity activation step to remove impurities in the semiconductor thin film. Activate. In this case, since the reflection film on the outermost surface reflects light to prevent light from entering the gate electrode, the gate electrode is not thermally damaged. Thus, a semiconductor device with improved characteristics can be easily obtained.
[0017]
The gate electrode forming step is a step of forming the gate electrode having a stacked structure, and the reflecting film forming step is a step of forming the reflecting film on the outermost surface of the gate electrode having the stacked structure. I do.
The gate electrode includes a film containing aluminum or copper as a main component, and the reflection film includes a film containing aluminum or silver as a main component.
[0018]
The heat treatment method for a thin film of the present invention is a heat treatment method for a thin film including a conductive film, and includes a thin film forming step of forming a thin film, and a conductive film forming step of forming a conductive film at a predetermined position on the thin film. A reflective film forming step of forming a reflective film that reflects the light on the conductive film, and a heat treatment step of irradiating the thin film and the reflective film with light and performing a heat treatment on the thin film. I do.
[0019]
In this heat treatment method, a reflective film for reflecting light is formed on a conductive film in a reflective film forming step, and the thin film and the reflective film are irradiated with light in the heat treatment step, and the thin film is subjected to a heat treatment. In this case, the reflective film on the outermost surface reflects light and prevents light from entering the conductive film, so that the conductive film is not thermally damaged. Becomes possible.
[0020]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments according to the present invention will be described in detail. In addition, in each embodiment, although it demonstrates, referring drawings, in each figure, in order to make each layer and each member into the magnitude | size which can be recognized on a drawing, the scale was made different for each layer and each member. is there.
[0021]
[First Embodiment]
FIG. 1 is a cross-sectional view showing an n-channel type polycrystalline silicon TFT (semiconductor device) having an LDD (Lightly Doped Drain) structure according to a first embodiment of the present invention. In the method, a base protective film 3 made of an insulating film such as a silicon oxide film is formed on the entire surface of a glass substrate 2, and a polycrystalline silicon film (semiconductor thin film) 4 is formed on the TFT protective position on the base protective film 3. A gate insulating film 5 made of a silicon oxide film, a silicon nitride film, or the like is formed on the entire surface of the underlying protective film 3 and the polycrystalline silicon film 4.
[0022]
The polycrystalline silicon film 4 has a channel region 4a into which impurity ions are not introduced, a low-concentration source region 4b and a low-concentration drain region 4c formed outside the channel region 4a, and a high-concentration source region formed further outside. 4d and a high-concentration drain region 4e.
A gate electrode (conductive film) 6 is formed on the channel region 4a with a gate insulating film 5 interposed therebetween.
[0023]
The gate electrode 6 is an electrode having a three-layer structure including a titanium film 6a, an aluminum film 6b, and a titanium nitride film 6c. A visible light (300 to 780 nm) is formed on the titanium nitride film 6c which is the outermost surface. The reflective film 7 having an average reflectivity of 50% or more with respect to is formed.
Here, the reason that the average reflectance of the reflective film 7 is limited to 50% or more is that if the average reflectance is less than 50%, the light under the reflective film absorbs the light transmitted through the reflective film, and the conductive film becomes conductive. This is because the body film may be thermally damaged.
[0024]
The reflection film 7 is a thin film made of any of aluminum, aluminum alloy, silver, and silver alloy.
Note that an aluminum alloy film may be used instead of the aluminum film 6b.
[0025]
An interlayer insulating film 8 made of a silicon oxide film or the like is formed so as to cover the gate electrode 6 and the reflective film 7, and a contact is made with a portion of the interlayer insulating film 8 corresponding to the high concentration source region 4d and the high concentration drain region 4e. Holes 11 and 12 are respectively formed, a source electrode 13 connected to the high-concentration source region 4d is formed in the contact hole 11, and a drain electrode 14 connected to the high-concentration drain region 4e is formed in the contact hole 12. ing.
[0026]
Next, a method for manufacturing the polycrystalline silicon TFT 1 will be described with reference to FIGS.
First, as shown in FIG. 2A, a glass substrate 2 cleaned by ultrasonic cleaning or the like is prepared, and the glass substrate 2 is formed by a plasma CVD method or the like under a condition where the substrate temperature is 150 to 450 ° C. A base protective film 3 made of an insulating film such as a silicon oxide film is formed to a thickness of less than 10 μm, for example, about 500 nm on the entire surface of the substrate. As a raw material gas used in this film forming process, a mixed gas of monosilane (SiH ₄ ) and dinitrogen monoxide (N ₂ O), TEOS (tetraethoxysilane: Si (OC ₂ H ₅ ) ₄ ), oxygen and And a mixed gas of disilane (Si ₂ H ₆ ) and ammonia (NH ₃ ).
[0027]
Next, as shown in FIG. 2B, under the condition that the substrate temperature is 150 to 450 ° C., the entire surface of the glass substrate 2 on which the base protective film 3 is formed is formed to a thickness of 20 to 1000 nm by a plasma CVD method or the like. Is formed. As the source gas used in this film forming step, the above-described disilane and monosilane are preferable.
[0028]
Next, as shown in FIG. 2C, the amorphous silicon film 21 is irradiated with a laser beam 22 using a laser device such as a XeCl excimer laser (wavelength: 308 nm) or a KrF excimer laser (wavelength: 249 nm). Then, laser annealing is performed. By this laser annealing, the amorphous silicon film 21 becomes a polycrystalline silicon film 23. The polycrystalline silicon film 23 may be formed by performing laser annealing after patterning the amorphous silicon film 21.
[0029]
Next, as shown in FIG. 2D, the polycrystalline silicon film 23 is patterned into a desired TFT shape by a photolithography method. That is, after applying a photoresist on the polycrystalline silicon film 23, patterning of the polycrystalline silicon film 23 is performed by sequentially performing exposure, development, etching of the polycrystalline silicon film 23, and removal of the photoresist. .
[0030]
Next, as shown in FIG. 3A, a gate insulating film 5 made of a silicon oxide film, a silicon nitride film, or the like is formed on the entire surface of the polycrystalline silicon film 23 and the underlying protective film 3 at a temperature of 350 ° C. or less. The film is formed to a thickness of 50 to 150 nm. As a source gas used in this step, a mixed gas of TEOS and oxygen gas or the like is suitable.
[0031]
Next, as shown in FIG. 3B, a titanium film 24, an aluminum film 25, a titanium nitride film 26, and an aluminum film 27 are sequentially formed on the entire surface of the gate insulating film 5 by a sputtering method or the like, and then photolithography is performed. By patterning by a method, a gate electrode 6 having a thickness of 300 to 1000 nm composed of a titanium film 6a, an aluminum film 6b and a titanium nitride film 6c, and a reflection film 7 composed of an aluminum film 27 having a thickness of 20 nm are formed. That is, after a photoresist is applied on the laminated film of the titanium film 24 to the aluminum film 27, exposure of the photoresist, development, etching of the laminated film, and removal of the photoresist are sequentially performed, so that the laminated film is patterned, The electrode 6 and the reflection film 7 are formed.
[0032]
Then, as shown in FIG. 3C, low concentration impurity ions are implanted at a dose of about 0.1 × 10 ¹³ to about 10 × 10 ¹³ / cm ^{2 using} the reflection film 7 and the gate electrode 6 as a mask. Then, a lightly doped source region 4b and a lightly doped drain region 4c are formed in self-alignment with the gate electrode 6. Here, when manufacturing an n-channel type polycrystalline silicon TFT, a donor-type impurity ion such as phosphorus is used as the impurity ion, and when manufacturing a p-channel type polycrystalline silicon TFT, Acceptor-type impurity ions such as boron are used as the impurity ions. Further, a region located immediately below the gate electrode 6 and in which the impurity ions are not introduced becomes a channel region 4a.
[0033]
Next, as shown in FIG. 3D, a resist mask (not shown) wider than the gate electrode 6 is formed, and high-concentration impurity ions (P ions) are added in a range from about 0.1 × 10 ¹⁵ to about 10 × 10 5. ^A high concentration source region 4d and a high concentration drain region 4e are formed by implantation at a dose of ¹⁵ / cm ² .
[0034]
Instead of forming the source region and the drain region having the LDD structure, a high-concentration impurity (P ion) is implanted while a resist mask wider than the gate electrode 6 is formed without implanting a low-concentration impurity. A source region and a drain region having an offset structure may be formed. Alternatively, a source region and a drain region having a self-aligned structure may be formed by implanting high-concentration impurities using the reflection film 7 and the gate electrode 6 as a mask.
[0035]
Next, as shown in FIG. 4A, instantaneous strong light annealing is performed on the polycrystalline silicon film 4 using the reflective film 7 and the gate electrode 6 as a mask, and the low-concentration source region 4b of the polycrystalline silicon film 4 Activate impurities (P ions) in the drain region 4c, the high concentration source region 4d, and the high concentration drain region 4e.
In the instantaneous strong light annealing, the polycrystalline silicon film 4 is irradiated with high-intensity light 31 using an excimer laser that emits high-intensity laser light or a flash lamp that emits high-intensity light equivalent to this laser light. This is a method of instantaneously raising the temperature of the polycrystalline silicon film 4 and activating impurities (P ions) in the polycrystalline silicon film 4.
[0036]
Since the reflective film 7 on the outermost surface has an average reflectance of 80% or more for the light 31, the light 31 is reflected to prevent the light 31 from entering the gate electrode 6. As a result, the titanium film 6a and the titanium nitride film 6c do not absorb the light 31 and do not become hot, so that the gate electrode 6 does not become hot instantaneously and is not likely to be thermally damaged.
[0037]
Instead of irradiating the polycrystalline silicon film 4 with the high-intensity light 31, the polycrystalline silicon film 4 is instantaneously scanned with a CW laser light emitted from a CW laser or a high-intensity light emitted from a lamp. May be. Also in this method, the impurities (P ions) in the polycrystalline silicon film 4 are activated.
[0038]
Next, as shown in FIG. 4B, an interlayer insulating film 8 made of a silicon oxide film or the like is formed to a thickness of 300 to 800 nm on the surface side of the reflective film 7 and the gate electrode 6 by a CVD method or the like. As a source gas used in the step of forming the interlayer insulating film 8, a mixed gas of TEOS and oxygen gas or the like is suitable.
Next, after a resist mask (not shown) having a predetermined pattern is formed on the interlayer insulating film 8, dry etching is performed on the interlayer insulating film 8 through the resist mask to form a region corresponding to the high-concentration source region 4d. A contact hole 11 is formed in a region corresponding to the high concentration drain region 4e.
[0039]
Next, a conductive material 32 containing a metal such as aluminum, titanium, titanium nitride, tantalum, or molybdenum as a main component is formed on the entire surface of the interlayer insulating film 8 by a sputtering method or the like. The source electrode 13 and the drain electrode 14 having a thickness of 400 to 800 nm are formed by patterning by photolithography. That is, after applying a photoresist (not shown) on the conductive material 32, the photoresist is exposed, developed, etched on the conductive material 32, and the photoresist is removed in order to pattern the conductive material 32. Then, a source electrode 13 and a drain electrode 14 are formed. As described above, an n-channel type polycrystalline silicon TFT (semiconductor device) 1 can be manufactured.
[0040]
According to the present embodiment, the reflective film 7 having an average reflectance of 80% or more with respect to visible light (300 to 780 nm) is formed on the titanium nitride film 6c which is the outermost surface of the gate electrode 6. When the polycrystalline silicon film 4 is subjected to instantaneous intense light annealing using the gate electrode 6 as a mask, the reflecting film 7 reflects the irradiated light 31 to prevent the light 31 from entering the gate electrode 6. it can. Therefore, the gate electrode 6 is not instantaneously heated to a high temperature and is not thermally damaged.
Further, since the glass substrate 2 transmits the light 31 and only the polycrystalline silicon film 4 is annealed at a high temperature, the glass substrate 2 is not thermally damaged.
[0041]
[Second embodiment]
FIG. 5 is a sectional view showing an n-channel type polycrystalline silicon TFT (semiconductor device) having an LDD (Lightly Doped Drain) structure according to a second embodiment of the present invention.
In this polycrystalline silicon TFT (semiconductor device) 41, the gate electrode 6 having a three-layer structure of the first embodiment is used as a gate electrode 42 having a single-layer structure made of a copper thin film, and a reflection film 7 is formed on the gate electrode 42. The other points are exactly the same as those of the polycrystalline silicon TFT 1 of the first embodiment.
[0042]
Also in this embodiment, similarly to the first embodiment, when the instantaneous strong light annealing is performed on the polycrystalline silicon film 4 using the reflection film 7 and the gate electrode 42 as a mask, the light irradiated by the reflection film 7 is reflected. In addition, light can be prevented from entering the gate electrode 42. Therefore, the gate electrode 42 is not instantaneously heated to a high temperature and is not thermally damaged.
[0043]
In each of the above embodiments, the gate electrode of an n-channel TFT has been described as an example. However, the present invention can be similarly applied to not only the gate electrode but also other wiring such as a data line.
In the first embodiment, the gate electrode has a three-layer structure in which the aluminum film is sandwiched between the titanium film and the titanium nitride film. However, the material of each film and the number of films to be laminated are appropriately determined as necessary. The configuration can be changed and is not limited to the configurations of the first and second embodiments.
[0044]
Further, in each of the above embodiments, the case where an n-channel TFT is manufactured has been described as an example, but the present invention can be similarly applied to a case where a p-channel TFT is manufactured.
Further, the manufacturing method of each of the above embodiments can be suitably applied particularly to the case of manufacturing a display device such as an active matrix liquid crystal device or an electroluminescence (EL) device in which a large number of TFTs are formed on a substrate. it can.
[0045]
【The invention's effect】
As described above, according to the semiconductor device of the present invention, since the reflection film is formed on the conductive film, the reflection film is formed when the impurity activation process for activating the impurities in the semiconductor thin film by light irradiation is performed. By reflecting the irradiated light, thermal damage to the conductive film due to the light irradiation can be prevented. Therefore, the characteristics of the semiconductor thin film can be improved, and the reliability as a semiconductor device can be improved.
According to the method for manufacturing a semiconductor device of the present invention, a reflective film forming step of forming a reflective film on a conductive film, and an impurity activation step of irradiating the semiconductor thin film and the reflective film with light to activate impurities in the semiconductor thin film. Since the light-reflecting film reflects light, the intrusion of light into the conductive film can be prevented, and the conductive film can be prevented from being thermally damaged. . Therefore, a semiconductor device with improved characteristics can be easily obtained.
[0047]
According to another method for manufacturing a semiconductor device of the present invention, a reflective film forming step of forming a reflective film that reflects light on a gate electrode, and irradiating the semiconductor thin film and the reflective film with light, Since an impurity activation step of activating impurities is provided, light can be prevented from entering the gate electrode by reflecting light on the outermost reflective film, and the gate electrode is thermally damaged. Can be prevented. Therefore, a semiconductor device with improved characteristics can be easily obtained.
[0048]
According to the heat treatment method for a thin film of the present invention, the method includes a reflective film forming step of forming a reflective film on the conductive film, and a heat treatment step of irradiating the thin film and the reflective film with light and performing a heat treatment on the thin film. Light can be prevented from entering the conductive film, and the conductive film is not likely to be thermally damaged. Therefore, heat treatment can be effectively performed on the thin film.
[Brief description of the drawings]
FIG. 1 is a sectional view showing a polycrystalline silicon TFT according to a first embodiment of the present invention.
FIG. 2 is a process chart showing a method for manufacturing a polycrystalline silicon TFT according to the first embodiment of the present invention.
FIG. 3 is a process chart showing a method for manufacturing a polycrystalline silicon TFT according to the first embodiment of the present invention.
FIG. 4 is a process chart showing a method for manufacturing a polycrystalline silicon TFT according to the first embodiment of the present invention.
FIG. 5 is a sectional view showing a polycrystalline silicon TFT according to a second embodiment of the present invention.
[Explanation of symbols]
1 Polycrystalline silicon TFT
2 Glass substrate 4 Polycrystalline silicon film 6 Gate electrode 7 Reflective film 31 High intensity light 41 Polycrystalline silicon TFT
42 Gate electrode

Claims (10)

A semiconductor device comprising a conductive film at a predetermined position on a semiconductor thin film,
A semiconductor device, wherein a reflective film is formed on the conductive film. The semiconductor device according to claim 1, wherein the semiconductor thin film is activated by irradiating light with impurities in the semiconductor thin film. 3. The semiconductor device according to claim 1, wherein an average reflectance of the reflection film with respect to visible light is 50% or more. A method for manufacturing a semiconductor device comprising a conductive film on a semiconductor thin film,
A semiconductor thin film forming step of forming a semiconductor thin film;
A conductive film forming step of forming a conductive film at a predetermined position on the semiconductor thin film;
A reflective film forming step of forming a reflective film that reflects light on the conductive film,
Irradiating the semiconductor thin film and the reflection film with light to activate an impurity in the semiconductor thin film. The method according to claim 4, wherein the impurity activating step is a step of activating the impurities in the semiconductor thin film by irradiating a laser beam or a lamp beam. A method for manufacturing a semiconductor device comprising a gate electrode on a semiconductor thin film,
A semiconductor thin film forming step of forming a semiconductor thin film;
A gate electrode forming step of forming a gate electrode at a predetermined position on the semiconductor thin film,
A reflective film forming step of forming a reflective film that reflects light on the gate electrode,
Irradiating the semiconductor thin film and the reflection film with light to activate an impurity in the semiconductor thin film. A method for manufacturing a semiconductor device comprising a gate electrode on a semiconductor thin film,
A semiconductor thin film forming step of forming a semiconductor thin film on a substrate,
A gate insulating film forming step of forming a gate insulating film on the semiconductor thin film,
A gate electrode forming step of forming a gate electrode at a predetermined position on the gate insulating film;
A reflective film forming step of forming a reflective film that reflects light on the gate electrode,
Forming a source / drain region in the semiconductor thin film by using the gate insulating film as a mask and ion-implanting impurities into the semiconductor thin film through the gate insulating film;
Irradiating the semiconductor thin film and the reflection film with light to activate an impurity in the semiconductor thin film. The gate electrode forming step is a step of forming the gate electrode having a stacked structure, and the reflecting film forming step is a step of forming the reflecting film on the outermost surface of the gate electrode having the stacked structure. The method for manufacturing a semiconductor device according to claim 6, wherein: 9. The semiconductor according to claim 6, wherein the gate electrode includes a film containing aluminum or copper as a main component, and the reflection film includes a film containing aluminum or silver as a main component. Device manufacturing method. A heat treatment method for a thin film including a conductive film,
A thin film forming step of forming a thin film,
A conductive film forming step of forming a conductive film at a predetermined position on the thin film;
A reflective film forming step of forming a reflective film that reflects the light on the conductive film,
A heat treatment step of irradiating the thin film and the reflective film with light and performing a heat treatment on the thin film.

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