JPH07183290A - Manufacture of thin film transistor - Google Patents

Abstract

PURPOSE:To improve characteristics of an amorphous silicon thin film transistor for a liquid crystal display element and a throughput by a high speed formed film of amorphous silicon by forming the amorphous silicon film of a boundary to a gate insulating film under conditions of obtaining a film having excellent characteristics at a low speed, and forming the other part at a high speed. CONSTITUTION:The method for manufacturing a thin film transistor comprises the steps of placing glass board 6 on which a source electrode, a drain electrode and wirings are formed on a board holder 9, heating the board 6 to 230 deg.C by a heater, and forming an amorphous silicon film on a surface of the board. The method further comprises the steps of introducing monosilane gas as reaction gas into a film forming reaction chamber 3 via a supply tube 10, and exhausting it via a turbo molecular pump 13. The method further comprises the steps of generating a plasma by applying microwaves, and forming an amorphous silicon film having a thickness of 200nm. The method further comprises the steps of then forming a silicon nitride film of about 200nm thick as a gate insulating film by a microwave plasma CVD method, vapor-depositing aluminum as an upper electrode, and then forming it into a gate electrode pattern, thereby obtaining the transistor.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a thin film transistor, and more particularly to an amorphous silicon thin film transistor used for a liquid crystal display device.

[0002]

2. Description of the Related Art In manufacturing an amorphous silicon thin film transistor, it has been pointed out that the characteristics of an interface between a gate insulating film and an amorphous silicon film are greatly affected, and the interface condition is deteriorated. The cause was explained as damage to the base film by plasma. As one example, as disclosed in Japanese Patent Publication No. 3-45554, a thin film transistor is formed by forming a metal layer as a gate electrode on an insulating substrate and patterning it, forming a gate insulating film, and using amorphous silicon. Forming process, source,
A step of forming a drain electrode, in which glow discharge, arc discharge, or sputtering discharge power when forming amorphous silicon is low at the initial stage of discharge, and the discharge period after that is high. By forming a film by a uniform discharge, amorphous silicon can be formed without damaging the underlying gate insulating film, which has an excellent effect on the uniformity of the threshold voltage of the thin film transistor and the yield. Is supposed to be obtained. However, in such a manufacturing method, due consideration is not given to the characteristics of amorphous silicon, and even if the gate insulating film is prevented from deteriorating even when the initial discharge is set to low discharge power, the effect cannot be obtained. In some cases, the field effect mobility of the thin film transistor is reduced. Especially in high-speed deposition of an amorphous silicon film, lowering the initial discharge power may even worsen the characteristics.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems of the prior art, and particularly in the case of depositing amorphous silicon at a high speed, the interface portion with the gate insulating film is formed. By improving the characteristics, the characteristics of the amorphous silicon thin film transistor for a liquid crystal display element are improved, which contributes to the improvement of the throughput due to the high-speed film formation of amorphous silicon. Furthermore, the purpose is to make it possible to use a film in a strained state due to film stress.

[0004]

When forming amorphous silicon at a high speed, the initial discharge power is lowered so as not to damage the underlying gate insulating film unlike the prior art. However, the characteristics of the amorphous silicon film cannot be improved because the characteristics of the amorphous silicon film cannot be kept in an optimum state. Further, in the case of a top-gate type thin film transistor, although there is no gate insulating film below and there should be no problem of adversely affecting the underlying layer, a product with good characteristics could not be obtained. By the way, in a field effect type amorphous silicon thin film transistor, a voltage is applied from the gate electrode to the amorphous silicon film through the gate insulating film, carriers are induced at the interface with the gate insulating film, and a conductive channel is created to create a conductive state. ing. The current flows only in the channel portion and its thickness is only 1 to 10 nm. That is, it can be said that the characteristics of the amorphous silicon thin film transistor are substantially determined by the characteristics of the amorphous silicon film having a thickness of 1 to 10 nm at the interface with the gate insulating film. Therefore, it suffices to improve the characteristics of the amorphous silicon film in this portion. On the other hand, in forming an amorphous silicon film, on the other hand, the low film forming rate has been a cause of low throughput under the condition that a film having good characteristics is obtained.

Therefore, in order to manufacture a thin film transistor with high throughput and good characteristics, which is an object of the present invention, an amorphous silicon film at the interface with the gate insulating film is formed at a low speed under the condition that a film with good characteristics is obtained. Other parts may be formed at high speed. However, in a staggered thin film transistor, a current flows from the source electrode to the channel portion and from the channel portion to the drain portion in the thickness direction of the film, so it is necessary to secure the film characteristics other than the channel part to some extent. If the film thickness of amorphous silicon is 30 nm or more, it operates as a thin film transistor, but it is necessary to set it to about 200 nm in order to secure a margin of the manufacturing process. The time required for handling the substrate is 20 to 40 seconds, and even if the film formation time is shorter than this, it does not contribute much to the improvement in throughput.
/ S, that is, the film formation time is preferably 20 to 100 seconds.

Therefore, the relationship between the formation conditions of the amorphous silicon film and the characteristics was investigated in detail. Conditions for high-speed film formation are as follows: 1) A device in which the substrate is installed in a bright part of plasma, that is, a part where the electron temperature is 2 to 3 eV or higher and the plasma density is high. 2) The supply of monosilane gas as a raw material is 1 cm.
² ) 0.04 cm ³ / min or more per minute 3) The gas supply is such that the gas is directly blown onto the substrate, and the distance L until the gas flows through the plasma to reach the substrate and the film forming pressure P Relationship

[0007]

## EQU1 ## The function of suppressing the generation of powder by satisfying P (Pa) × L (cm) = 2, heating the entire reaction system including the source gas, or modulating the discharge power by pulse modulation. Be prepared. 1) is a condition for promptly decomposing the raw material gas, and the plasma density n (pieces / cm ³ ) is the pressure P (P
a)

[0008]

[Mathematical formula-see original document] It suffices if n> 3 × 10 ¹⁰ / P. This relationship indicates that the higher the pressure is, the more the probability of collision between the raw material gas and the plasma is increased, so that the amount of the raw material gas activated is increased. Therefore, when the pressure is high, the plasma density may be low. 2) is at least 2n
This indicates that it is necessary to supply more raw material gas in order to achieve the film forming rate of m / s or more. 3) is a condition that does not generate powder. A method to suppress the reaction in the gas phase by shortening the gas flow distance from the mean free process to prevent the generation of powder, and to raise the gas temperature. The method corresponds to a method for lengthening the mean free path and a method for suppressing the growth of higher order silane, which is the nucleus of powder generation, by pulse discharge. In a device satisfying these conditions, the discharge power W that optimizes the characteristics of the amorphous silicon film
Results of detailed investigation of the relationship between (W / cm ² ) and film formation rate D (nm / s)

[0009]

It was found that there is a relation of W = 0.12D.

This relationship suggests that there is an optimum energy value for forming a certain amount of amorphous silicon film. It was also found that the film properties should satisfy this condition and that the film formation rate should be slow. Therefore, in order to manufacture thin film transistors with good characteristics with high productivity, amorphous silicon in the channel part is formed at a low film formation rate within the range that satisfies this condition, and other parts are formed at high speed within the range that adheres to this condition. Just do it.

However, the film formation rate is not a parameter that can be set arbitrarily, but changes depending on the discharge power, pressure, gas supply amount, and the like. Therefore, when changing the film formation rate, for example, it is necessary to find the optimum combination of the gas supply amount and the discharge power and to simultaneously change the discharge power and the raw material gas flow rate so that the optimum combination is always obtained.

A method for simultaneously changing the discharge power and the raw material gas flow rate may be performed manually, but it is preferable to change the discharge power and the raw material gas flow rate while maintaining an optimal combination of the discharge power and the raw material gas flow rate. When the raw material gas flow rate is changed, the pressure inside the film formation reaction chamber is also changed. When the flow rate of the raw material gas is small, the pressure in the reaction chamber decreases and it becomes difficult to discharge. On the contrary, when the flow rate of the raw material gas is large and the pressure in the reaction chamber is high, flakes are easily formed and defects in the film increase. Therefore, it is preferable to control the pressure when changing the raw material gas flow rate.

In addition to the method of changing the conditions during the film formation to increase the film formation rate to improve the throughput, the thickness of the interface between the gate insulating film and the amorphous silicon in which the channel is formed is 10 to 10.
Amorphous silicon with good characteristics is formed only in the 50 nm portion by the conventional high-frequency glow discharge method with a low film forming rate, and the remaining portion is formed by microwave discharge or a high-speed film forming method using disilane as a source gas. As a result, it is possible to improve the throughput of manufacturing products such as thin film transistors.

Further, the internal stress of a film having good electric characteristics is not always small. In many cases, the stress is rather large. In such a case, if the total film thickness is formed under the same conditions, the stress becomes too large and the film peels off or cracks occur.

In order to avoid such a problem, a film having good electric characteristics is formed only in the vicinity of the interface where electric characteristics are required, and a film having good electric characteristics is formed in other portions, but stress is small even if electric characteristics are inferior. A film may be formed.

When the decomposition of the source gas is performed by plasma, the problem of sputtering in the film forming reaction chamber cannot be avoided. In this case, this effect differs depending on the material of the film forming reaction chamber, particularly the material of the portion in contact with the plasma. In general, iron-based materials such as stainless steel are often used, but when iron or chromium is taken into amorphous silicon, it forms deep localized levels and significantly deteriorates the characteristics of the amorphous silicon film. Further, copper is used for the gasket and the like, but when copper is also taken into the amorphous silicon, a deep localized level is formed and the characteristics of the amorphous silicon film are significantly deteriorated. On the other hand, aluminum has the effect of creating a shallow acceptor level and drawing the Fermi level of amorphous silicon toward the valence band. The Fermi level of non-dope amorphous silicon tends to be closer to the conduction band, and it is better to dope a small amount of boron, aluminum or the like to obtain an intrinsic semiconductor. Therefore, when the material of the film formation reaction chamber is aluminum, sputtered aluminum is incorporated into the film, which has the effect of improving the characteristics of the amorphous silicon film.

[0017]

The amorphous silicon film is formed by a glow discharge or an arc discharge in which a monosilane gas, a disilane gas or a silicon tetrafluoride gas is used as a raw material gas and a rare gas or hydrogen gas is added to the raw material gas and introduced into the film forming reaction chamber. A plasma chemical vapor deposition method for decomposing a raw material gas to form a film on a substrate;
A method of forming silicon by sputtering with glow discharge plasma of hydrogen gas and argon gas is known, but the method of plasma chemical vapor deposition is more preferable than amorphous silicon.

In forming an amorphous silicon film by plasma chemical vapor deposition, for example, when amorphous silicon is formed by a chemical vapor deposition method using microwave plasma using monosilane gas as a source gas, the relationship as shown in FIG. 1 is obtained and the mobility is high. The value of the discharge power with which amorphous silicon having good film characteristics can be obtained changes depending on the flow rate of the raw material gas. In the case of using microwave plasma, when the power is small, the microwave intensity is concentrated in the center, so that the film is concentrated in the center. In this case, it is calculated that the discharge power is applied to the part with the film, and the condition of [Equation 3] is satisfied. Also, when amorphous silicon is formed by the chemical vapor deposition method using high frequency glow discharge, there is a relationship as shown in FIG. 2, and the conditions for obtaining amorphous silicon with good characteristics are both the discharge power and the raw material gas flow rate. And satisfies the condition of [Equation 3]. As described above, generally, the optimum value of the discharge power depends on the flow rate of the source gas, and the characteristics of the amorphous silicon when optimized are such that the film forming rate is preferably slow. Therefore, if the channel portion of the thin film transistor is formed at a low speed and the other portions are formed at a high speed, a thin film transistor having excellent characteristics can be manufactured with high productivity.

As a method of automatically controlling the raw material gas flow rate, the discharge power, and the film forming pressure, the raw material gas flow rate, the discharge power, and the opening of the conductance control valve of the gas exhaust system are independently programmed as a function of time. Input the optimal combination data of the control method and the raw material gas flow rate and the discharge power, program one of them as a function of time and run it, and the other will be the optimal combination according to the value at that time. There is a control method. The former requires data of control parameters to be stored in advance, but the device and program are relatively simple, and are suitable when the amount of change is large in a short time.
On the other hand, the latter is relatively slow to change and is suitable when it is necessary to always maintain the relationship between the parameters.

[0020]

EXAMPLES The present invention will be described below with reference to examples.

Example 1 Example 1 shows an example in which the present invention is applied to the case of forming amorphous silicon by a chemical vapor deposition method using microwave plasma. A schematic vertical sectional view of the apparatus used is shown in FIG. A microwave of 2.45 GHz is guided from the microwave generation source 1 to the electromagnetic horn 4 through the microwave waveguide 2.
The opening diameter of the electromagnetic horn is 450 mm. A microwave window 8 made of quartz was provided at the opening of the electromagnetic horn 4, and microwaves were introduced into the film formation reaction chamber 3 through the microwave window 8. The magnetic field was generated by passing an electric current through the electromagnetic coil 5, the maximum point of the magnetic field strength was set in the electromagnetic horn 4, and the electron cyclotron resonance point was set so as to be between the microwave window 8 and the substrate 6. The reaction gas was ejected from the gas blowing hole of the gas supply device 7 installed in the vicinity of the microwave window toward the substrate 6 placed opposite thereto. The exhaust was performed by a turbo molecular pump 13 equipped with an oil rotary pump 14 as an auxiliary pump, and the pressure was adjusted by a conductance adjusting valve 12.

As the substrate 6, a 320 mm × 240 mm glass substrate having a source electrode, a drain electrode, and wiring formed thereon is placed on a substrate holder 9, and the substrate is heated to 230 ° C. by a heater built in the substrate holder. An amorphous silicon film was formed on the surface of the substrate. A monosilane gas as a reaction gas was introduced into the film formation reaction chamber 3 through the gas supply pipe 10 and exhausted by the turbo molecular pump 13. The conductance adjusting valve 12 was fully opened. Microwave was applied to generate plasma, and an amorphous silicon film with a thickness of about 200 nm was formed. After that, a silicon nitride film is formed as a gate insulating film by a microwave plasma CVD method to a film thickness of 200.
A film having a thickness of about 10 nm was formed, aluminum was vapor-deposited as an upper electrode, and then processed into a gate electrode pattern to produce a thin film transistor. The characteristics of this thin film transistor were measured.

Initially, the film formation reaction chamber was made of stainless steel, but the mobility of the thin film transistor was up to 0.3c.
No more than m ² / V · s was obtained. When this amorphous silicon film was examined by secondary ion mass spectrometry, chromium was about 0.04 ppm and iron was about 0.01 p in the film.
pm was detected. Then, when the thin film transistor was manufactured by covering the inner wall of the film forming reaction chamber with aluminum, a mobility of 0.5 cm ² / V · s or more was obtained. When this amorphous silicon film was examined by secondary ion mass spectrometry, about 0.06 ppm of aluminum was detected in the film. As described above, it was found that aluminum is less adversely affected even when it is similarly taken into the amorphous silicon film.

FIG. 1 shows the relationship between the raw material gas and discharge power in the case of forming amorphous silicon by the chemical vapor deposition method using microwave plasma using monosilane gas as the raw material gas, and the mobility measured for the thin film transistor thus formed. Such a thin film transistor having excellent characteristics is obtained when the optimum discharge power is changed depending on the flow rate of the raw material gas, and it is not necessary to simply reduce the discharge power. The maximum mobility of the thin film transistor at each raw material gas flow rate increases as the flow rate decreases, and the discharge power that gives the maximum value increases as the raw material gas flow rate decreases. That is, the mobility of the thin film transistor is higher as the flow rate of the source gas and the discharge power are smaller along the curve shown by the broken line in the figure.

Next, the system shown in FIG. 4 is used to change the discharge power, the flow rate of the raw material gas and the opening of the conductance adjusting valve as shown in FIG.
A thin film transistor was manufactured by changing the film forming conditions along the broken line in FIG. 1 to change the film forming conditions of the last about 30 nm to various values by changing the film forming conditions to 5 cm ² and a discharge power of 600 W to 170 nm. . As a result, it was found that the mobility of the thin film transistor depends on the film forming conditions of the last 30 nm portion and the relationship is the same as in FIG. That is, it was found that the characteristics of the thin film transistor are determined by the characteristics of the amorphous silicon film in the 30 nm portion of the interface portion of the gate insulating film. The film formation rate of amorphous silicon is proportional to the flow rate of the source gas and is 125 sccm (standard cubic).
It was 5 nm / s at centimeters per minutes and 2 nm / s at 50 sccm. Therefore, for example, the film is formed only at the end with the flow rate of the source gas of 50 sccm and the discharge power of 100 W. Until then, if the film is formed with the flow rate of the source gas of 125 sccm and the discharge power of 600 W, the film is formed at the average film formation rate of about 4 nm / s and 2 nm / s. It is possible to obtain a thin film transistor having the same characteristics as described above.

Example 2 Example 2 shows an example in which the present invention is applied to the case of forming amorphous silicon by a chemical vapor deposition method using high frequency plasma. A schematic vertical sectional view of the apparatus used is shown in FIG. 13.56 MH from the high frequency power source 1a through the matching device 2a to the electrode 4a
It is configured to guide the high frequency of z. The electrode diameter is 450 mm. The surface of the electrode 4a is a perforated plate 7a, and the reaction gas is passed through the perforated plate 7a so as to face the substrate 6
It was ejected toward the top of a. Exhaust was performed by a roots pump 13a equipped with an oil rotary pump 14a as an auxiliary pump, and pressure adjustment was performed by a conductance adjustment valve 12a.

As the substrate 6a, a 320 mm × 240 mm glass substrate having a source electrode, a drain electrode and wiring formed thereon is placed on a substrate holder 9a, and the substrate is heated to 250 ° C. by a heater built in the substrate holder. An amorphous silicon film was formed on the surface of the substrate. Disilane gas as a reaction gas was introduced into the film formation reaction chamber 3a through the porous plate 7a provided on the electrode 4a, and exhausted by the roots pump 13a. The conductance adjusting valve 12a was connected to an automatic pressure control system to adjust the pressure to 60 Pa. A high frequency was applied to generate plasma to form an amorphous silicon film having a thickness of about 200 nm. After that, a silicon nitride film was formed to a thickness of 200 nm as a gate insulating film, aluminum was deposited as an upper electrode, and then processed into a gate electrode pattern to manufacture a thin film transistor. The characteristics of this thin film transistor were measured. FIG. 2 shows the relationship between the raw material gas flow rate and the discharge power when the amorphous silicon is formed by the chemical vapor deposition method using high-frequency plasma using disilane gas as the raw material gas, and the measured mobility of the thin film transistor. As described above, a thin film transistor having excellent characteristics even in the case of high frequency plasma is obtained when an optimum discharge power is supplied depending on the flow rate of the raw material gas, and it is not necessary to simply reduce the discharge power. The maximum mobility of the thin film transistor at each raw material gas flow rate increases as the flow rate decreases, and the discharge power that gives the maximum value increases as the raw material gas flow rate decreases.

That is, the mobility of the thin film transistor is higher as the flow rate of the source gas and the discharge power are smaller along the curve shown by the broken line in the figure.

In this case, the internal stress of the amorphous silicon film was large under the condition that both the flow rate of the raw material gas and the discharge power were small, and the film was partially peeled off. Separately, when the stress of the film was measured, the flow rate of disilane was 45 sccm.
It was found that the film formed with 0 W had a tensile stress of 1.5 GPa.

Next, the system shown in FIG. 7 is used to change the set value of the raw material gas flow rate as shown in FIG. 8 and control the high frequency power so that it has the relationship shown in FIG. 9 with respect to the actual raw material gas flow rate. A quality silicon layer was formed. The first 170 nm of the amorphous silicon layer is formed at a source gas flow rate of 100 sccm and a discharge power of 400 W, and then the film forming conditions are changed along the broken line in FIG. The film was changed and the thin film transistor was produced. As a result, it was found that the mobility of the thin film transistor depends on the film forming conditions of the last 30 nm portion, and the relationship is the same as in FIG. That is, also in this case, it was found that the characteristics of the thin film transistor are determined by the characteristics of the amorphous silicon film in the portion having a thickness of about 30 nm near the interface of the gate insulating film. The film formation rate of amorphous silicon was proportional to the flow rate of the source gas, and was 2.5 nm / s at 100 sccm and 1.2 nm / s at 45 sccm. Therefore, for example, only at the end, a film is formed with a source gas flow rate of 50 sccm and a discharge power of 200 W,
Until then, the flow rate of the source gas was 100 sccm and the discharge power was 40.
If the film is formed at 0 W, the average film forming speed is about 2 nm / s and 1.2
It is possible to obtain a thin film transistor having the same characteristics as when a film was formed at nm / s. Further, in this case, since the film having a large stress is only the last 30 nm, the film stress as a whole can be reduced and the film peeling can be prevented.

Example 3 In Example 3, it was revealed from Examples 2 and 3 that the characteristic of the amorphous silicon film having a thickness of about 30 nm in the portion in contact with the gate insulating film was important in the thin film transistor. This portion was formed by a chemical vapor deposition method using high frequency plasma using monosilane gas as a raw material, and the rest was formed at a high speed by a chemical vapor deposition method using high frequency plasma using disilane gas as a raw material. The apparatus used was that used in Example 2.

As a substrate, a 320 mm × 240 mm glass substrate on which a source electrode, a drain electrode, and wiring are formed is placed on a substrate holder, and the substrate is heated to 250 ° C. by a heater built in the substrate holder. Then, an amorphous silicon film was formed. First, disilane gas flow rate 1
Amorphous silicon having a thickness of about 175 nm was deposited at 00 sccm and a high frequency power of 400 W for 70 seconds. After that, monosilane gas 50sccm, high frequency power 40W 10
Amorphous silicon having a thickness of about 30 nm was deposited for 0 seconds.
During film formation, the conductance adjusting valve 12a was connected to an automatic pressure control system to adjust the pressure to 60 Pa. After that, a silicon nitride film was formed to a thickness of 200 nm as a gate insulating film, aluminum was deposited as an upper electrode, and then processed into a gate electrode pattern to manufacture a thin film transistor.

As a result of measuring the characteristics of this thin film transistor, the mobility of this thin film transistor is 0.9 cm ² / V.
・ It was s.

Example 4 In Example 4, the thickness of the portion in contact with the gate insulating film was about 30 nm.
The amorphous silicon film was formed by a chemical vapor deposition method using high-frequency plasma using monosilane gas as a raw material, and the rest was formed at a high speed by a chemical vapor deposition method using microwave plasma. The apparatus is the same as the microwave plasma chamber 32 used in the first embodiment.
And a high-frequency plasma chamber 31 similar to the apparatus used in Example 2.
The substrate transfer chamber 33 is used for the structure. Figure 10
Shows the schematic diagram.

As a substrate, a 320 mm × 240 mm glass substrate having a gate electrode, wiring and a gate insulating film formed thereon is placed on a substrate holder and the heater built into the substrate holder heats the substrate to 240 ° C. Then, an amorphous silicon film was formed. First, the high frequency plasma chamber 3
1, the substrate was placed, and amorphous silicon having a thickness of about 30 nm was formed for 100 seconds with a monosilane gas of 50 sccm and a high frequency power of 40 W. After that, the substrate was transferred to the microwave plasma chamber 32, and the remaining 170 nm was deposited at a source gas flow rate of 125 sccm and a discharge power of 600 W. 40 nm thick n-type amorphous silicon film doped with phosphorus as an impurity
Formed, and aluminum was vapor-deposited as an upper electrode, and then processed into a pattern of a source electrode and a drain electrode.
Using this aluminum electrode pattern as a mask, the n-type amorphous silicon film was etched to produce a thin film transistor. The characteristics of this thin film transistor were measured. As a result, the mobility of this thin film transistor was 0.9 cm ² / V.
・ It was s. Thus, if a high quality film is formed near the interface with the gate insulating film, it is possible to manufacture a thin film transistor having excellent characteristics regardless of the order of forming the film.

[0036]

According to the present invention, a thin film transistor having excellent characteristics can be manufactured at a high speed for forming an amorphous silicon film, the throughput of an active matrix liquid crystal display device is improved, and the number of manufacturing devices is reduced. Therefore, the cost can be reduced.

[Brief description of drawings]

FIG. 1 is a diagram showing the relationship between the mobility of a thin film transistor on which amorphous silicon is formed by microwave plasma chemical vapor deposition, the flow rate of a source gas, and the discharge power.

FIG. 2 is a diagram showing the relationship between the mobility of a thin film transistor in which amorphous silicon is formed by high-frequency plasma chemical vapor deposition using disilane gas as a raw material gas, the flow rate of the raw material gas, and the discharge power.

FIG. 3 is a schematic vertical cross-sectional view of the microwave plasma chemical vapor deposition apparatus of Example 1.

FIG. 4 is a schematic diagram of an automatic control system of the microwave plasma chemical vapor deposition apparatus of Example 1.

5 is a diagram showing control data of the automatic control system of the microwave plasma chemical vapor deposition apparatus in Example 1. FIG.

FIG. 6 is a schematic vertical sectional view of a high frequency plasma chemical vapor deposition apparatus in Example 2.

FIG. 7 is a schematic diagram of an automatic control system of a high frequency plasma chemical vapor deposition apparatus according to a second embodiment.

FIG. 8 is a diagram showing raw material gas control data of the automatic control system of the high frequency plasma chemical vapor deposition apparatus in Example 2.

FIG. 9 is a diagram showing discharge power control data with respect to a raw material gas flow rate in the automatic control system of the high frequency plasma chemical vapor deposition apparatus in Example 2.

FIG. 10 is a schematic vertical sectional view of an apparatus used in Example 4.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Microwave generation source, 2 ... Microwave waveguide, 3 ... Film-forming reaction chamber, 4 ... Electromagnetic horn, 5 ... Electromagnetic coil, 6 ... Substrate, 7 ... Gas feeder, 8 ... Microwave window, 9 ... Substrate Holder, 10 ... Gas supply pipe, 12 ... Conductance adjusting valve, 13 ... Turbo molecular pump, 14 ... Oil rotary pump, 20 ... Control computer, 21 ... DA converter, 22 ... Mass flow controller, 23 ... Raw material gas container, 24 ... High-voltage power supply for microwave generation, 25 ... Conductance adjustment valve drive device, 26 ... Conductance adjustment valve, 1a ... High frequency power supply, 2a ... Matching device, 3a ... Film forming reaction chamber, 4a ... Electrode, 6a ... Substrate, 7a ... Perforated plate, 9a ... Substrate holder, 12a ... Conductance adjusting valve, 13a ... Roots pump, 14a ... Oil rotary pump, 20a ... Control power Calculator, 21a ... DA / AD converter, 22a ... Mass flow controller, 23a ... Raw material gas container, 24a ... High frequency power supply, 25a ... Automatic pressure regulator, 26a ... Conductance adjusting valve, 27a ... Pressure gauge, 31 ... High frequency plasma chamber, 32 ... Microwave plasma chamber, 33 ... Substrate transfer chamber.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical indication location H01L 29/786 (72) Inventor Mifumi Yoritomi 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Hitachi Ltd. (72) Inventor Takao Takano, 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Ltd.

Claims (8)

[Claims] 1. A metal layer processed into a pattern of source and drain electrodes, an amorphous silicon film, a gate insulating film, and a metal layer processed into a pattern of a gate electrode are sequentially laminated on an insulating substrate. In the constructed field effect thin film transistor, a large flow rate of the amorphous silicon layer (deposition area 1c
High speed film formation (2 nm / s or more) under the conditions of a silane flow rate per m ^{2 of} 0.04 cm ³ or more per minute) and a large discharge power (film formation area of 1 cm ² and film formation rate of 0.12 W per 1 nm / s).
Then, in the final portion of the thickness of 10 to 50 nm, a low source gas flow rate (silane flow rate per film forming area of 1 cm ² was 0.02 cm ^{3 /} min.
Below), low discharge power (film formation area 1 cm ² , film formation rate 1 n)
Low speed film formation (1 nm / m / s 0.12 W)
/ S) or less). 2. The raw material gas flow rate according to claim 1, wherein the raw material gas flow rate is continuously changed at the transition from the large raw material gas flow rate and large discharge power conditions to the low raw material gas flow rate and low discharge power conditions. A method of manufacturing a thin film transistor, characterized in that the flow rate of the raw material gas and the discharge power are controlled so that the discharge power can form amorphous silicon having the best characteristics at the flow rate. 3. A metal layer processed into a pattern of source and drain electrodes, an amorphous silicon film, a gate insulating film, and a metal layer processed into a pattern of a gate electrode are sequentially laminated on an insulating substrate. On the constituted field effect thin film transistor or the insulating substrate, the metal layer processed to the pattern of the gate electrode, the gate insulating film, the amorphous silicon film, and the metal layer processed to the pattern of the source and drain electrodes are formed. In a field-effect thin film transistor that is sequentially stacked, at least one of the insulating film near the interface between the gate insulating film and amorphous silicon and / or the amorphous silicon film has large stress and the insulating film other than near the interface and the amorphous film A method of manufacturing a thin film transistor, wherein the silicon film has a small stress. 4. A metal layer processed into a pattern of source and drain electrodes, an amorphous silicon film, a gate insulating film, and a metal layer processed into a pattern of a gate electrode are sequentially laminated on an insulating substrate. A method of manufacturing a thin film transistor, comprising forming a field effect type thin film transistor by changing a composition of a raw material gas during film formation of the amorphous silicon layer. 5. The amorphous silicon having a thickness of 10 to 50 nm at the interface with the gate insulating film is formed at a low speed using monosilane gas as a source gas, and disilane gas is used as a source gas before that. A method of manufacturing a thin film transistor, which comprises forming a film at a high speed. 6. A metal layer processed in a pattern of source and drain electrodes, an amorphous silicon film, a gate insulating film, and a metal layer processed in a pattern of a gate electrode are sequentially laminated on an insulating substrate. A method of manufacturing a thin film transistor, comprising forming a field effect type thin film transistor by forming at least two kinds of amorphous silicon layers. 7. The amorphous silicon according to claim 5, wherein a portion having a thickness of 10 to 50 nm at an interface portion with the gate insulating film is formed by a chemical vapor deposition method by high frequency plasma decomposition of a raw material gas, A method of manufacturing a thin film transistor, characterized in that the film is formed by a chemical vapor deposition method using microwave plasma. 8. A plasma chemical vapor deposition apparatus for forming an amorphous silicon layer used in a field effect thin film transistor and the like, characterized in that at least a portion exposed to plasma is aluminum. Chemical vapor deposition equipment.