JP2001168348A - Manufacturing method of semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor material, especially a semiconductor material on a film, which is excellent in electrical characteristics. SOLUTION: A semiconductor device which is excellent in electrical characteristics is manufactured by a process for forming an insulating film 102 on a substrate 101, a process for forming a semiconductor film 103 on the insulating film 102, a process for crystallizing the semiconductor film 103 by means of first heating, a process for carrying out second heating treatment at a temperature higher than crystallization, and a process for carrying out third heating treatment in oxygen atmosphere.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a thin film semiconductor device such as a thin film transistor and a thin film diode used for a switching element, an integrated circuit, a liquid crystal display element and the like.

[0002]

2. Description of the Related Art Thin film semiconductor devices, for example, thin film transistors and thin film diodes, have attracted attention as elements that can be formed on an insulating substrate, such as a driving circuit of a liquid crystal display device and an amplifier circuit of an image sensor. Also in the monolithic technology for forming an element thereon, attempts have been made to use a thin film transistor to increase the degree of integration of the element and to achieve a three-dimensional circuit. The thin film semiconductor used at this time may be a polycrystalline material such as polysilicon, an amorphous material such as amorphous silicon, or a material intermediate between the two, and may have characteristics as polycrystal and characteristics as amorphous. A semi-amorphous semiconductor such as semi-amorphous silicon having the above characteristics is used.

[0003] However, the carrier mobility of these thin film semiconductors is several to several times smaller than that of a single crystal semiconductor.
The operating speed of the thin-film semiconductor device using these materials is extremely low because it is extremely small, ie, 1/0. For example, the electron mobility of amorphous silicon was 1 cm ² / Vs or less, and the electron mobility of general polysilicon was 10 to 30 cm ² / Vs. Also,
Even when a special manufacturing method such as laser annealing is used, the limit is 200 cm ² / Vs, which is significantly smaller than the electron mobility of single crystal silicon of 1350 cm ² / Vs. Therefore, thin-film semiconductor devices can be used for relatively low-frequency applications and for single crystal semiconductor
For example, it has only been used as a load resistance element in a static RAM.

It is considered that the reason why the carrier mobility of a thin film semiconductor is low is that, for example, in an amorphous material, carrier scattering is likely to occur due to short crystal periodicity, and thus the mean free path of the carrier is short. Further, in the polycrystalline material, it is considered that the concentration of the foreign element is increased at the crystal grain boundary, a barrier is generated at the crystal grain boundary, and carriers are randomly scattered at the crystal grain boundary. Therefore, it has been attempted to increase the mobility by increasing the size of each crystal to reduce the number of grain boundaries per unit length. Semi-amorphous materials generally have long periodic parts like polycrystalline materials, and there are no clear crystal grain boundaries.
Scattering of carriers at grain boundaries is suppressed, indicating relatively large carrier mobilities. However, it is difficult to obtain a semi-amorphous material having a crystal having a large grain size (a region where long-range order is maintained). Also, it is easy to obtain polysilicon having a large particle size, but if the size of the device and the particle size are about the same, the variation in the characteristics of the device becomes large,
Not practical.

[0005]

SUMMARY OF THE INVENTION The problem to be solved by the present invention is to improve the carrier mobility of a thin film semiconductor and to provide a semiconductor material suitable for use in a thin film semiconductor device.

[0006]

Means for Solving the Problems The present inventors have been studying the cause of obtaining a material having a large mobility by laser annealing. That is, despite the fact that the size of each crystal is the same, which is about several to 10 μm,
In the case of thermal annealing in a normal electric furnace, the obtained electron mobility was 30 cm ² / Vs, while that obtained by laser annealing was 200 cm ² / Vs. One of the causes is that in thermal annealing, annealing takes place for a sufficiently long time, so that many foreign elements precipitate at the crystal grain boundaries, whereas in laser annealing, especially laser annealing using a pulsed laser, foreign elements do not. It was considered that there was no time to move to the grain boundary, and the formation of the barrier at the grain boundary was incomplete.

[0007] In addition, it has been considered that in laser annealing, the stress generated at the time of laser irradiation is preserved as it is and has some influence on grain boundaries. In other words, it was considered that the bonding of the grain boundaries was made closer by laser annealing, and the width of the barriers at the grain boundaries was reduced.

[0008] To prove the hypothesis, FIG.
An experiment as shown in FIG. That is, a film of an insulating material that contracts due to heat, for example, a film of phosphorus glass, boron glass, phosphorus-boron glass, AN glass, quartz glass,
A film of a thin film semiconductor material, for example, a film of polysilicon, amorphous silicon, or semi-amorphous silicon was formed thereon by a plasma CVD method or a sputtering method. Here, it should be noted that thermal contraction is different from thermal expansion. The latter has reversibility in thermal cycling, whereas the former has no reversibility in thermal cycling. That is, it is an irreversible phenomenon. Therefore, in the above laminating step, it is important to maintain the temperature at a sufficiently low temperature at which the heat-shrinkable film does not shrink.

Then, the semiconductor film and the insulating film were patterned to obtain the state shown in FIG. Thereafter, by heating them at an appropriate temperature, the insulating film was shrunk, and thus the semiconductor film thereon was also shrunk. This temperature is determined by the insulating material of the base. In the case of quartz, the optimum temperature is about 600 ° C. At this temperature, the amorphous silicon film is crystallized. In this state, for example, it was maintained for 24 hours.

Thereafter, in order to neutralize the disorder of the crystal due to the annealing, thermal annealing was performed in a hydrogen stream at 200 to 400 ° C., and hydrogen was added to the polysilicon formed by the annealing. Then, a device having a MOS structure was manufactured using this semiconductor, and the electron mobility was measured. As a result, a mobility of 40 to 60 cm ² / Vs was obtained. This value was 30 to 100% larger than that in the case where the base was formed on a material that did not cause thermal shrinkage.

Although this experiment itself does not directly prove that high mobility can be obtained by laser annealing, it is necessary to improve the mobility by applying stress to the upper semiconductor film by using a special material for the base. It was discovered by chance that this was possible. Based on this experiment, the present inventors continued their research, and reached the following invention.

The material used for the substrate is semiconductor or glass.
An insulator such as a material may be used. Also seemingly contradictory
However, a heat-shrinkable insulating film formed in a later step is not sufficient.
When thick, the effect of the substrate can be neglected. But
Therefore, in this case, no matter what the substrate
I do not care. And heat-shrinkable insulation on these substrates
Materials such as phosphorus glass, boron glass, phosphorus boro
Of glass, AN glass, quartz glass
By a photo CVD method, a plasma CVD method, or a sputtering method.
Deposits. In that case, first form a silicon oxide film
After that, phosphorus or boron is ion-implanted.
10¹⁴-10¹⁸cm^-2, Preferably 10 ¹⁶~ 5 × 10
¹⁷cm^-2May be used. these
If the glass material contains 10-30 atomic% of hydrogen,
In this case, it was found that the heat shrinkage was relatively large. Also,
The thickness of these insulating layers is 50 to 1000 nm.
Was suitable. This thickness is the thickness of the overlying semiconductor film.
It is determined by the size of the element. However
If it is extremely thin, it will peel off from the substrate during heat shrinkage.
Do not shrink due to the influence of the substrate.
Or A thickness of at least 50 nm is required
You.

Thereafter, a film of a semiconductor material, for example, amorphous silicon, polysilicon, or semi-amorphous silicon is formed to a thickness of 10 to 500 nm.
These semiconductor films may or may not contain hydrogen. Further, for example, after forming an amorphous silicon film at a low temperature, the film may be converted into polysilicon by laser annealing. This is because laser annealing heats only the vicinity of the surface of the semiconductor film and has no thermal effect on most of the insulating film, especially when visible light is used as the laser light. While a semiconductor layer such as that described above absorbs laser light, the insulating layer is transparent to visible light and therefore has a very small thermal effect. In any case, when forming a semiconductor film,
It is necessary to perform the treatment at a temperature at which the film of the underlying insulating layer does not thermally shrink.

Next, the semiconductor film and the insulating film are patterned. The patterning may be performed by completely removing the insulating film as shown in FIG. 2 (A) or may be removed to a certain depth as shown in FIG. 2 (B). It was found that the selection of the width L of the region to be separated and the depth T from the interface between the semiconductor film and the insulating film to the bottom of the groove formed was important.
We have L / T <1000, preferably L / T <
It was found that it was necessary to be 100. This is because when L is significantly larger than the thickness of the insulating layer that thermally shrinks, the thermal shrinkage proceeds not in the horizontal direction but in the vertical direction. In that case, the semiconductor film formed thereon is hardly affected.

Thereafter, the insulating film is shrunk by a heating step. As the temperature at this time, in the case of silicon oxide, 600 to 1000 ° C. is suitable, but in this step, the semiconductor film is also crystallized at the same time. In particular, when annealing is performed at a high temperature, many crystal nuclei are generated and the size of the crystal is reduced. To avoid that, first 500-700
C, preferably at 550-600 ° C. for 12-70 hours, for example, 580 ° C. for 36 hours to crystallize a silicon-based material such as amorphous silicon, and then at 700-1000 ° C., preferably 750 ° C. ~
12 to 70 hours at 800 ° C, for example 24 at 780 ° C
The insulating layer may be contracted by annealing for a time.
In addition, a non-oxidizing atmosphere such as argon or a reducing atmosphere such as hydrogen was suitable for the atmosphere for the thermal annealing.
When annealing was performed in a vacuum of 0 ^-2 torr or less, remarkable shrinkage occurred particularly when a material containing a large amount of hydrogen was used for the insulating film. This is presumably because hydrogen in the insulating film went to the outside as water. If the annealing temperature is increased, the thermal shrinkage will occur more remarkably. However, if the temperature is too high, the insulating material melts or becomes glassy and exhibits fluidity, which is not appropriate. In particular, when using phosphorus glass, boron glass, or phosphorus boron glass, care must be taken because the vitrification temperature is low.

FIG. 3 shows another method for achieving the present invention. First, a heat-shrinkable insulating film is formed on an insulator or a semiconductor substrate, and is patterned to obtain FIG. 3A. Further, a semiconductor film is formed thereon to obtain FIG. 3 (B). Then, the insulating coating is thermally contracted by thermal annealing. In this case, unlike the case shown in FIGS. 1 and 2, the semiconductor film is not cut, and the semiconductor film directly contacts the substrate. Therefore, when a part of the semiconductor film is used as a wiring, Alternatively, it is effective when a substrate such as a semiconductor substrate needs to make contact with a semiconductor film.

FIG. 4 shows a manufacturing method including both steps for obtaining the present invention shown in FIG. 2 and FIG.
First, a heat-shrinkable insulating material 402 is formed on a substrate 401.
A and B are selectively formed, and a semiconductor film 40 is formed thereon.
Form 3 Then, the coatings 403 and 402A, B are formed by using a known patterning technique such as dry etching.
Is etched to obtain FIG. Thereafter, the insulating films 402a to 402d are contracted by thermal annealing, and stress is applied to the semiconductor films 403a to 403d thereon, thereby exhibiting high mobility.

FIG. 4C shows an example of an element manufactured by this method. This is a complementary MOS (CMOS)
The element is formed using a thin film transistor, and p-type impurity regions 412 a to 412 c are formed on a single crystal semiconductor substrate 411, and a semiconductor gate electrode 413 is formed.
a and b are provided. The semiconductor gate contains phosphorus
Generally, a type semiconductor is used. Then, the heat-shrinkable insulating films 414a and 414b are provided thereon, and a semiconductor film having an n-type semiconductor region is further formed thereon. n
Among the type semiconductor regions, 415b and 415c are in contact with an n-type semiconductor region provided on the substrate. Thus 412b
415b or 412c and 413c are PN
A junction is formed, but when both are sufficiently doped and degenerate semiconductors, there is almost no rectifying action. Semiconductor gates 416a and 416b are provided on the semiconductor region. Further, interlayer insulating films 417a to 417e are formed, and after the hole forming step, the metal electrode is formed of a material such as aluminum, an aluminum-silicon alloy, tungsten, molybdenum, or an alloy thereof with silicon.

Thus, contacting the thin film semiconductor region with the semiconductor substrate facilitates electrode formation. FIG. 4 (d)
Shows a circuit diagram of an element on the left side of the element shown in FIG. In the case of such a multilayer structure, a deep hole must be formed in order to form an electrode, and the area of the hole must be as shown in FIG.
It is necessary to make the area sufficiently large like 418a and f in (C). This is because when the hole is deep, the electrode material adheres to the side surface of the hole when forming the coating for the electrode, and the hole is often closed without forming the coating to the depth of the hole. is there. In this case, contact cannot be reliably established. However, since the hole of the electrode 418b is relatively shallow, the area of the electrode forming portion can be reduced.

In a multi-layered semiconductor device, it is not desirable to form a contact hole up to the semiconductor substrate and make contact with the wiring in or near the uppermost layer. Therefore, in the case of FIG.
Instead of providing a and f, impurity regions 412a and 412d
By designing so as to also serve as a wiring as it is, contact with the impurity region becomes unnecessary, and the area of the element can be made sufficiently smaller than that shown in FIG.

[0021]

[Example 1] Resistivity 10^ThreeΩcm p-type
Utilizes conventional integrated circuit manufacturing technology on crystalline silicon substrate 501
And an n-channel MOSFET as shown in FIG.
Was prepared. That is, 502a to 502c are so-called LO
Formed by COS technology or other similar technology
Isolation region consisting of thick oxide film (field isolation
503a and 503b have a thickness of 10
nm formed on the gate insulating films 504a and 504b.
A 200 nm thick gate electrode with 10^{twenty one}cm
^-3Heavily doped n-type silicon. These gates
The electrodes are L-shaped as shown in FIG. Sa
Further, 505a-d are field insulators and gates.
Using the electrode as a mask, self-aligned (self-aligned
The impurity region formed, and phosphorus and
And arsenic in 3 × 10 ²⁰cm^-3, 1 × 10²⁰c
m^-3Contains. Further, as shown in FIG.
Impurity regions 505a and 505d are formed on a semiconductor substrate.
In addition, it is electrically connected to other elements and a power supply. Get
The width of the electrode was 1 μm. Also, source dray
The length of the impurity region in the channel direction is about 5 μm,
The width was 3 μm.

Next, a silicon oxide film having a thickness of 500 nm was deposited by glow discharge plasma CVD. The manufacturing method at this time will be described briefly. Monosilane gas (SiH ₄ ) and hydrogen gas are used as raw material gas, and high frequency (1
The monosilane was decomposed by the electric discharge (3.56 MHz). The pressure in the chamber during the reaction was 0.1 torr. The substrate temperature was room temperature or cooled with liquid nitrogen. Various measurements have revealed that the amount of hydrogen contained in the silicon oxide film thus obtained is about 30 atomic%. Then, the silicon oxide film is etched by a known dry etching technique to form a silicon oxide region 5.
06a and b were formed. As a raw material gas, disilane gas (Si ₂ H ₆ ) can be used in addition to monosilane.

Next, a thickness of 200
A nm-thick amorphous silicon film 507 was formed thereon.
The substrate temperature is room temperature, and the sputtering target has a purity of 99.9.
The silicon target was 9999% or more. The atmosphere during the sputtering was 100 tons of argon and 0.2 torr. The power used for the sputtering was a high frequency of 200 W at 13.56 MHz. Thus, FIGS. 5B and 5B were obtained.

Then, the silicon film 507 and the silicon oxide films 506a and 506b were selectively removed by a known etching technique. FIG. 6A is a top view of the device obtained by this etching. Portions where the silicon coating is in contact with the underlying substrate or gate electrode to form a contact are shaded portions in the figure. At this time, 200 nm of the silicon oxide film was left as it was. Thereafter, the substrate, ^10-5
Heat to 600 ° C in a torr vacuum and change the state to 7 ° C.
Hold for 0 hours. Further, in this state, the temperature was raised to 800 ° C. over 2 hours, and the state was maintained for 3 hours. This process causes crystallization of amorphous silicon and thermal contraction of the insulating film.

Thereafter, the surface of the silicon film 507 was exposed to a dry and high-temperature oxygen atmosphere to form a thermal oxide film having a thickness of about 10 nm. This oxide film is used later as a gate insulating film. Of this oxide film, 507b in FIG.
Those formed on and d are removed to expose the underlying silicon film. Further, a polycrystalline silicon film was formed thereon by a thermal decomposition method of silane. Phosphorus was added to the polycrystalline silicon in an amount of about 10 ²⁰ to 10 ²¹ cm ⁻³ to obtain good conductivity. Then, this is selectively removed, and the gate electrode 5 is removed.
08a and b were formed. This gate electrode is 507b
And d, in contact with the silicon coatings 507b and d,
Therefore, it comes into contact with the underlying gate electrodes 503a and 503b.

Further, boron ions were implanted at 10 ¹⁴ to 10 ¹⁵ cm ^-2 by ion implantation. Then, the substrate was annealed in vacuum at 1000 degrees for 30 minutes to recrystallize the amorphous region generated by the ion implantation, thereby obtaining p-type impurity regions 509a to 509d. Further, phosphorus-boron glass was formed on the surface, and the surface was flattened using a reflow technique to form an interlayer insulating film 510. Then, aluminum electrodes 511a to 511d were formed by providing electrode forming holes. Through the above steps, a CMOS using a multilayer thin film transistor was manufactured as shown in FIG. The hole mobility of the thin film transistor (P-channel type) obtained in this manner is 50 to 100 cm ² / Vs, and the characteristics are improved about twice as compared with the conventional one.

[Embodiment 2] An n-channel MOSFET as shown in FIG. 5A is formed on a p-type single crystal silicon substrate 501 having a resistivity of 10 Ωcm by using a conventional integrated circuit manufacturing technique.
Was prepared. The size of the details of the element was the same as in Example 1. Next, a silicon oxide film having a thickness of 500 nm was deposited by glow discharge plasma CVD. The fabrication method at this time was almost the same as that of Example 1, but 1000 ppm to 20% of phosphine (P
H ₃ ). Therefore, the obtained film contained phosphorus. Further, the amount of hydrogen contained in the silicon oxide film was 30 atomic% as in Example 1. The silicon oxide film containing phosphorus was etched by a known dry etching technique to form silicon oxide regions 506a and 506b. Next, an amorphous silicon film 507 having a thickness of 200 nm was formed thereon by a sputtering method. The film forming conditions were the same as in Example 1. Thus, FIGS. 5B and 5B were obtained.

Then, the silicon film 507 and the silicon oxide films 506a and 506b were selectively removed by a known etching technique. FIG. 6A is a top view of the device obtained by this etching. The portion where the silicon coating is in contact with the lower substrate or the gate electrode is the hatched portion in the figure. At this time, 20 nm of the silicon oxide film was left as it was. Thereafter, the substrate is placed in a vacuum of 10 ^-6 torr, and excimer laser light (KrF laser, wavelength 24
8 nm, pulse width 30 nsec: 200 mJ / pulse,
50 shots). By this step, the amorphous silicon film was crystallized. Thereafter, it was kept at 700 ° C. for 12 hours in a vacuum. By this step, the insulating film causes heat shrinkage. Further, hydrogen passivation was performed by holding the substrate at 200 to 600 ° C. for 3 hours in a hydrogen atmosphere to improve the electrical characteristics of silicon.

Thereafter, the surface of the silicon film 507 was exposed to a dry and high-temperature oxygen atmosphere to form a thermal oxide film having a thickness of about 10 nm. This oxide film is used later as a gate insulating film. Of this oxide film, 507b in FIG.
Those formed on and d are removed to expose the underlying silicon film. Further, a polycrystalline silicon film having a thickness of 300 nm was formed thereon by a thermal decomposition method of silane. Phosphorus was added to the polycrystalline silicon in an amount of about 10 ²⁰ to 10 ²¹ cm ⁻³ to obtain good conductivity. Then, this was selectively removed to form gate electrodes 508a and 508b. This gate electrode is formed of a silicon film 507b at 507b and d.
And the gate electrode 503 which is in contact with
It comes into contact with a and b.

Further, boron ions were implanted at 10 ¹⁴ to 10 ¹⁵ cm ^-2 by ion implantation. Then, the substrate was annealed in vacuum at 1000 degrees for 30 minutes to recrystallize the amorphous region generated by the ion implantation, thereby obtaining p-type impurity regions 509a to 509d. Further, phosphorus-boron glass was formed on the surface, and the surface was flattened using a reflow technique to form an interlayer insulating film 510. Then, aluminum electrodes 511a to 511d were formed by providing electrode forming holes. Through the above steps, a CMOS using a multilayered thin film transistor as shown in FIG. 6B was manufactured. The thin film transistor (P
Channel mobility) is 150 to ²⁰⁰ cm ² /
Vs, which is more than twice that of the conventional one.

Embodiment 3 An n-channel MOSFET as shown in FIG. 5A is formed on a p-type single crystal silicon substrate 501 having a resistivity of 10 Ωcm by using a conventional integrated circuit manufacturing technique.
Was prepared. The size of the details of the element was the same as in Example 1. Next, a silicon oxide film having a thickness of 500 nm was deposited by glow discharge plasma CVD. The manufacturing method at this time was almost the same as that of Example 1, but 1000 ppm to 20% of phosphine was mixed in the raw material gas. Therefore, the obtained film contained phosphorus. Further, the amount of hydrogen contained in the silicon oxide film was 30 atomic% as in Example 1. The silicon oxide film containing phosphorus was etched by a known dry etching technique to form silicon oxide regions 506a and 506b. Next, an amorphous silicon film 507 having a thickness of 200 nm was formed thereon by a sputtering method. The film forming conditions were the same as in Example 1. Thus, FIGS. 5B and 5B were obtained.

Then, the silicon film 507 and the silicon oxide films 506a and 506b were selectively removed by a known etching technique. FIG. 6A is a top view of the device obtained by this etching. The portion where the silicon coating is in contact with the lower substrate or the gate electrode is the hatched portion in the figure. At this time, 20 nm of the silicon oxide film was left as it was. Thereafter, the substrate is placed in a vacuum of 10 ^-6 torr, and excimer laser light (KrF laser, wavelength 24
8 nm, pulse width 30 nsec, 100 mJ / pulse,
50 shots). By this step, the amorphous silicon film was made semi-amorphous. The semi-amorphous state was determined by Raman spectroscopy. Thereafter, it was kept at 600 ° C. for 72 hours in a vacuum. By this step, the insulating film caused heat shrinkage. Further, the substrate is set at 200 to 400 ° C., for example, 300 ° C.
The gas was maintained in a hydrogen atmosphere, for example, a mixed gas (1 atm) of 20% of hydrogen and 80% of argon at 30 ° C. for 30 minutes to passivate hydrogen, thereby improving the electrical characteristics of semi-amorphous silicon.

Thereafter, a silicon oxide film having a thickness of about 100 nm was formed on the silicon film 507 by a glow discharge method. This oxide film is used later as a gate insulating film. Of this oxide film, those formed on 507b and 507d in FIG. 6A 'are removed to expose the underlying silicon film. Further, a polycrystalline silicon film having a thickness of 300 nm was formed thereon by a thermal decomposition method of silane. Phosphorus was added to the polycrystalline silicon in an amount of about 10 ²⁰ to 10 ²¹ cm ⁻³ to obtain good conductivity. Then, this is selectively removed, and the gate electrode 5 is removed.
08a and b were formed. This gate electrode is 507b
And d, in contact with the silicon coatings 507b and d,
Therefore, it comes into contact with the underlying gate electrodes 503a and 503b.

Further, boron ions were implanted at 10 ¹⁴ to 10 ¹⁵ cm ^-2 by ion implantation. Then, the substrate was annealed in vacuum at 600 degrees for 30 hours to recrystallize the amorphous region generated by the ion implantation, thereby obtaining p-type impurity regions 509a to 509d. Further, phosphorus-boron glass was formed on the surface, and the surface was flattened using a reflow technique to form an interlayer insulating film 510. And
Aluminum electrodes 511a to 511d were formed by providing electrode forming holes. Through the above steps, a CMOS using a thin film transistor as shown in FIG. 6B was manufactured. Thin-film transistor thus obtained (P-channel type)
Has a hole mobility of 130 to 150 cm ² / Vs,
The characteristics were more than doubled as compared with the conventional one.
In addition, the variation in mobility among the elements was small.

[0035]

According to the present invention, the carrier mobility of a thin film semiconductor can be improved. The degree of the improvement was approximately 20 to 100%, but in some cases, a three-fold or more improvement was also observed. In this example, the electron mobility was not particularly described, but the mobility was improved by manufacturing through exactly the same process. In the present embodiment, silicon was mainly used as the semiconductor material, but the same phenomenon was confirmed even with germanium or a compound semiconductor such as a silicon-germanium alloy.

In this embodiment, only a substrate using a semiconductor substrate is shown, but an insulating substrate may be used as described in the text. Further, in this embodiment, only a two-layer element such as a first-layer transistor on a semiconductor substrate and a second-layer thin film transistor thereon is shown. For example, a first-layer transistor on a semiconductor substrate, Forming a first thin film transistor according to the present invention, using the thin film transistor as a second layer transistor, using the thin film transistor or the like as a substrate, forming a heat-shrinkable material thereon, and forming a second thin film transistor thereon. It is also possible to take a three-layer structure of a third-layer transistor, and further form a first thin-film transistor on an insulating substrate and a second thin-film transistor thereon to form a two-layer structure on the insulating substrate. It is also possible to construct structural elements. The former aims to increase the integration density in semiconductor integrated circuits.
The latter can be employed, for example, in a liquid crystal display element for the purpose of reducing the semiconductor element region and increasing the light-transmitting region.

[Brief description of the drawings]

FIG. 1 shows an example of a method for manufacturing a thin film semiconductor material of the present invention.

FIG. 2 shows an example of a method for manufacturing a thin film semiconductor material of the present invention.

FIG. 3 shows an example of a method for manufacturing a thin film semiconductor material of the present invention.

FIG. 4 shows an example of a method for manufacturing a thin film semiconductor material of the present invention and an example of an element using the semiconductor material of the present invention.

FIG. 5 shows an example of a method for manufacturing a thin film semiconductor material of the present invention.

FIG. 6 shows an example of a method for manufacturing a thin film semiconductor material of the present invention.

[Explanation of symbols]

 101: Substrate 102: Heat-shrinkable insulating film 103: Semiconductor film

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[Procedure amendment]

[Submission date] November 15, 2000 (200.11.
15)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claims

[Correction method] Change

[Correction contents]

[Claims]

Claims (5)

[Claims] An insulating film is formed on a substrate, a semiconductor film is formed on the insulating film, and a first heat treatment is performed.
After performing the first heat treatment, a second heat treatment is performed at a temperature higher than the temperature of the first heat treatment, and the second heat treatment is performed.
A third heat treatment is performed in an oxygen atmosphere after the heat treatment, and a gate electrode is formed after the third heat treatment. 2. An insulating film is formed on a substrate, a semiconductor film is formed on the insulating film, and the semiconductor film is heated to 500 ° C. to 700 ° C. to crystallize the semiconductor film. Heating the conductive film and the semiconductor film to 700 ° C. to 1000 ° C., heating to 700 ° C. to 1000 ° C., heating in an oxygen atmosphere, and heating in the oxygen atmosphere to form a gate electrode. Of manufacturing a semiconductor device. 3. After forming an insulating film on the substrate, forming a semiconductor film on the insulating film, performing a first heat treatment to crystallize the semiconductor film, and performing a first heat treatment. Performing a second heat treatment at a temperature higher than the temperature of the first heat treatment, performing the second heat treatment, and then performing a third heat treatment to form a gate insulating film; A method for manufacturing a semiconductor device, comprising forming a gate electrode over the gate insulating film after forming the insulating film. 4. An insulating film is formed on a substrate, a semiconductor film is formed on the insulating film, and the semiconductor film is heated to 500 ° C. to 700 ° C. to crystallize the semiconductor film. After heating the conductive film and the semiconductor film to 700 ° C. to 1000 ° C., and then heating to 700 ° C. to 1000 ° C., a heat treatment is further performed to form a gate insulating film, and after forming the gate insulating film, A method for manufacturing a semiconductor device, comprising forming a gate electrode over a gate insulating film. 5. The method for manufacturing a semiconductor device according to claim 1, wherein after forming the gate electrode, an interlayer insulating film is formed using phosphorus-boron glass.