JP3201492B2 - Method for manufacturing amorphous silicon film, method for manufacturing amorphous silicon nitride film, method for manufacturing microcrystalline silicon film, and non-single-crystal semiconductor device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing an amorphous film, and more particularly to a method for producing an amorphous silicon film suitably used for a thin film device such as a thin film transistor, a thin film transistor type optical sensor, a solar cell and the like. It relates to a manufacturing method.

[0002] The present invention also relates to a method for manufacturing an amorphous silicon nitride film.
The present invention relates to a method for manufacturing an amorphous silicon nitride film suitably used for an amorphous silicon thin film device such as a thin film transistor type optical sensor.

The present invention also relates to a method for manufacturing a microcrystalline silicon film, and more particularly to a method for manufacturing a microcrystalline silicon film by using a plasma CVD method. Here, microcrystal means a silicon film having a structure including crystal grains in the film, and also includes polysilicon (polycrystal).

[0004] The present invention relates to a non-single crystal semiconductor device, about the particular non-single crystal semiconductor device having a non-single crystal semiconductor layer which is prepared by a plasma CVD method
You.

[0005] Here, a non-single-crystal semiconductor refers to an amorphous semiconductor other than a single-crystal semiconductor, a microcrystalline (including polycrystalline) semiconductor, or the like.

[0006]

2. Description of the Related Art First, a conventional technique relating to a method for manufacturing an amorphous silicon film will be described.

Conventionally, an amorphous silicon thin film (hereinafter referred to as a-Si
As a method for producing a thin film, a monosilane gas (S
There is a plasma CVD method using a silicon compound represented by iH ₄ ) as a source gas. Generally, the plasma CVD method is 1
A high-frequency discharge in an RF band of 3.56 MHz or a microwave band of 2.54 GHz is used.

[0008] In addition, a photo CVD method or an ECR-CV
The D method is known, but among such manufacturing methods,
As a film forming method which satisfies the a-Si thin film quality, large area support, price, etc. in a well-balanced manner, plasma CVD by RF discharge of 13.56 MHz is generally used.
Is the law. This plasma CVD method uses monosilane gas (SiH ₄ ) in many cases, dilutes it with hydrogen gas (H ₂ ) if necessary, decomposes the source gas by 13.56 MHz RF discharge, and reacts with reactive active gas. A seed is formed and an a-Si film is deposited on the substrate. The a-Si thin film manufactured by this type of method is used for a-Si thin film devices such as thin film transistors, thin film transistor type optical sensors, and solar cells.

Next, a conventional technique relating to a method for producing amorphous silicon nitride will be described.

[0010] In recent years, semiconductor devices using non-single-crystal silicon have been actively developed. In particular, the development of photoconductor drums for photovoltaic cells and copiers that can be produced with large area and low cost, the development of thin film transistors for liquid crystal displays,
The development of solid-state imaging devices for facsimile has been active. In particular, an amorphous silicon nitride film is used for a gate insulating film of a thin film transistor and a passivation film of these devices. Conventionally, as a method of depositing an amorphous silicon nitride film used in these semiconductor devices, silane SiH ₄
Or RF plasma C using a mixture of fluorinated silane SiF ₄ and ammonia NH ₃ or nitrogen N ₂ as a film forming gas
The VD method has been used. Another method of manufacturing silicon nitride is a thermal CVD method, but cannot be adopted as a process for the above device using an amorphous silicon semiconductor having a high growth temperature of about 850 ° C. and a low heat resistance of about 400 ° C. In the RF plasma CVD method, the growth temperature can be set to about 300 ° C., so that it can be sufficiently used. Ammonia is more easily decomposed and reaction is more likely to occur when using nitrogen than nitrogen. In many cases, a mixed gas of silane SiH ₄ and ammonia NH ₃ is used, and if necessary, diluted with hydrogen gas to perform the reaction.
A plasma CVD method is used in which plasma is generated at a high frequency of 3.56 MHz, a film forming gas is decomposed by the plasma to generate reactive active species, and an amorphous silicon nitride film is deposited on a substrate. However, ammonia gas is corrosive, difficult to handle, and may not be particularly desirable for production equipment. In that respect, nitrogen gas is easy to handle and advantageous. In addition, nitrogen gas is easier to purify than ammonia gas, and the incorporation of impurities during film formation can be reduced. Impurities in the film are not preferable because they adversely affect the electrical characteristics of the amorphous silicon nitride insulating film. It is known that when a film is formed using an ammonia gas, the hydrogen concentration in the film is increased as compared with the case where a nitrogen gas is used. When the amount of hydrogen in the film increases, the density decreases, and the denseness and heat resistance deteriorate. In addition, since this hydrogen diffuses through the film and causes various instability phenomena,
The less hydrogen in the film, the better. As described above, when the mixed gas of the silane gas and the nitrogen gas is used, there are various advantages. Furthermore, from this viewpoint, it is considered advantageous to use a mixed gas of hydrogen-free fluorinated silane and nitrogen gas.

Further, a conventional technique relating to a method for producing amorphous silicon nitride will be described.

Since the composition of the amorphous silicon nitride thin film changes depending on the manufacturing method and its conditions, it is described as a SiN _x film. The physical properties of the SiN _x film vary greatly depending on the composition, the amount of hydrogen contained, and the like. Typical methods for depositing a SiN _x film include a normal pressure CVD method using a SiH ₄ —NH ₃ mixed gas, a plasma CVD method, an optical CVD method, and the like. Among them, a low-temperature process using a large-area glass substrate, specifically one that can be used at about 400 ° C., is particularly an RF plasma using a discharge frequency of 13.56 MHz of a SiH ₄ —NH ₃ mixed gas. This is a CVD method, and is most widely used because it has an advantage that a reaction easily occurs and its controllability is good.

However, this SiN _x film is a-Si
When using as a gate insulating film of the thin film transistor (hereinafter abbreviated as TFT) using a thin film, characteristics of a-Si thin film TFT provides a change in device characteristics depending on the gate insulating film SiN _X film. In particular, in the case of a change in the threshold voltage, a decrease in the on / off ratio, or a decrease in the response, the yield is reduced, which causes a serious problem. Similarly, in a TFT-type optical sensor, a change in the threshold voltage causes a change in the photocurrent and the dark current, which are the basic characteristics.
It is generally considered that such a problem in device characteristics is caused by the gate insulating film or the interface characteristics between the gate insulating film and the a-Si film.

More specifically, the change in the threshold voltage is caused by injection of electrons and holes from a-Si into SiN _x ,
Because it is trapped in the trap level of N _X
It is considered that a high quality film having a large optical band gap and a small electron spin density of the iN _x film is effective for minimizing the change.

Further, as the content of hydrogen in the SiN _x film increases, the density decreases and the withstand voltage decreases. Further, since this hydrogen diffuses in the film and causes various instability phenomena, it is considered that it is desirable that the amount of hydrogen in the film is small.

Further, it is considered that the TFT characteristics can be improved by setting the stress of the SiN _x film to a slightly compressed side.

That is, until now, the basic physical properties of a SiN _x thin film have been studied from various angles such as film formation conditions and test conditions.
It is presumed that the iN _x thin film desirably has a large optical band gap, a low spin density, a low hydrogen concentration, and a slightly compressive stress.

Next, a conventional technique relating to a method for manufacturing a microcrystalline silicon film will be described.

In recent years, semiconductor devices using microcrystalline silicon or amorphous silicon have been actively developed. In particular, the development of photoconductor drums for solar cells and copiers that can be produced at a large area and at low cost, the development of thin film transistors for liquid crystal displays, and the development of solid-state imaging devices for facsimile devices that are made light and small are active. Conventionally, as a method of depositing a non-single-crystal silicon film used in these semiconductor devices, RF plasma C using silane SiH ₄ or disilane Si ₂ H ₆ as a deposition gas is used.
VD method or Si target in the presence of hydrogen gas
A reactive sputtering method of sputtering in r plasma has been used. Microcrystalline silicon and amorphous silicon obtained by these methods almost contain hydrogen at 10% or more. The most widespread method for depositing such microcrystalline silicon or amorphous silicon is a plasma CVD method, which is silane SiH ₄ or disilane Si ₂ H.
₆ and, if necessary, dilute with hydrogen gas to obtain 13.5.
Plasma is generated at a high frequency of an RF band of 6 MHz, and a film forming gas is decomposed by the plasma to generate reactive active species, and microcrystalline silicon or amorphous silicon is deposited on the substrate. In particular, by mixing a film forming gas with a doping gas such as phosphine PH ₃ , diborane B ₂ H ₆ , and boron fluoride BF ₃ , a microcrystalline silicon film whose n-type or p-type is freely controlled can be formed by forming a film. Can be formed.
These pn-controlled films are important as ohmic layers and blocking layers of semiconductor devices, and pin-type solar cells and photodiodes have been made using these films.

As described above, the method of manufacturing an amorphous silicon film,
Method of manufacturing porous silicon nitride, method of manufacturing microcrystalline silicon film
Prior arts related to the conventional methods have been described. As a method of improving the RF plasma CVD method described in each prior art, examples have been reported in which the frequency has been increased with respect to a high frequency discharge in an RF band up to now. .

That is, in the fall of 1990 and in the spring of 1991, the Lectures on Applied Physics (28p-MF-14, 28p-S-4)
In (1), Oda et al. Of Tokyo Institute of Technology performed discharge at a high frequency of 144 MHz, thereby producing and evaluating amorphous silicon.

However, in this report 13.56M
Hz and 144 MHz only, and considering a large area and production, the frequency in the VHF band has not yet been sufficiently optimized.

Japanese Patent Application Laid-Open No. 3-64466 discloses that as a frequency effect, a spatially uniform discharge can be generated over the film forming surface by increasing the frequency, and a uniform film forming speed can be realized. Have been. However, in the present invention, only uniform film formation is referred to, and no description is given as to how the high frequency in the VHF band has a technical effect on film quality and the like.

Japanese Patent Application Laid-Open No. 22567/1990 describes a frequency of 1 kHz to 100 MHz.
No mention is made of technical effects in the VHF band, and this is merely an extension of the technology in the RF band.

In US Pat. No. 4,933,203, VH
The film is examined using the F-band high frequency, and the relationship between the frequency and the inter-electrode distance is optimized. However, this relationship is insufficient for a problem to be solved by the present invention described later.

[0026]

SUMMARY OF THE INVENTION First, amorphous silicon
Problems relating to the film manufacturing method will be described.

With the recent technological development, a-S is required in all fields such as solar cells, liquid crystal televisions and optical sensors.
Although there is a demand for high quality i-thin films, as in the past,
The a-Si thin film using the 3.56 MHz RF discharge still has the following problems when applied to an a-Si thin film device. (1) With respect to the basic characteristics of a thin film, a thin film transistor has a small carrier mobility, and an optical sensor has an S / N defined by a ratio of photoconductivity to dark conductivity.
For example, the ratio is small, and in a solar cell, the photoconductivity (σ _P ) characteristic is deteriorated by light irradiation, and the photodeterioration is large. (2) With respect to the production yield, in a large-area device, there is a decrease in the yield due to the distribution of device characteristics due to the film thickness / film quality distribution. (3) With respect to the price, a high-quality film that can be used for a thin-film device has a low film-forming rate, so that its production capacity does not increase and it is difficult to reduce the price.

That is, in order to improve the device characteristics of the large-area a-Si thin film, to improve the yield at the same time, and to realize a low price, while improving the basic characteristics of the a-Si thin film, It is necessary to form a film at high speed.

For this purpose, in the 13.56 MHz plasma CVD method, improvement of production conditions such as flow rate, pressure, and input power of raw material gas has been generally attempted. There are an increase in hydrogen in the film, which is presumed to lower the characteristics, and the generation of foreign matter (polysilane) which lowers the yield. For example, as shown in FIG. 65, as the deposition rate increases, the photoconductivity σ _P (S / cm), which is the basic characteristic of the thin film, decreases. The one which can improve the characteristics has not been manufactured yet. As a result, in this method of manufacturing an a-Si thin film, the film formation rate at which device characteristics can be maintained is about 0.2 to 2 ° / sec.

That is, as a feature of the 13.56 MHz RF discharge, there is an advantage that the film can be easily formed in a large area, but the film forming speed is low, and the substrate and the thin film itself are not. It has disadvantages such as large ion damage to the surface. On the other hand, in the case of the microwave discharge of 2.54 GHz, the deposition rate is high and there is no ion damage to the substrate, but there is a disadvantage that it is difficult to increase the area. In addition, the photo-CVD method has a problem not only in the quality of the formed a-Si thin film but also in increasing the area, and is a method under development. Similarly, in the ECR-CVD method, the damage to the substrate can be freely controlled, and the quality of the a-Si thin film can be improved. However, there is a disadvantage that it is difficult to form a large-area film.

As described above, in manufacturing an a-Si thin film device, it is necessary to simultaneously improve the quality of the a-Si thin film and improve the device characteristics, and at the same time, the productivity represented by the film forming speed. There is a drawback that you can not.

Next, problems relating to a method for manufacturing amorphous silicon nitride will be described.

Using the above-mentioned conventional silane gas or a mixed gas of fluorinated silane and nitrogen gas, if necessary, dilute with hydrogen gas to generate plasma at a high frequency of 13.56 MHz, and decompose the film forming gas by the plasma. The method of depositing an amorphous silicon nitride film on a substrate has the following problems.

Since nitrogen gas is harder to decompose than ammonia gas, it is necessary to increase the high frequency power to be supplied. However, when the input power is increased, more gas is released from the chamber wall, more impurities are taken in the film, and plasma damage is increased, thereby deteriorating the characteristics of the film. In addition, since silicon fluoride is chemically more stable than silane, its decomposition efficiency in plasma is low, and when it is used, gas utilization efficiency is poor. Further, the growth rate of the film is reduced.

Next, problems relating to the method for manufacturing amorphous silicon nitride will be described.

In order to satisfy the above-mentioned physical properties of the thin film, the conventional one
Various methods have been attempted in the RF plasma CVD method using 3.56 MHz, but the following problems have been encountered.

First, conventionally, the hydrogen concentration in the film C _H (%)
_Has the highest dependency on the substrate temperature T _S and also greatly depends on the type of source gas. This relationship is shown in FIG. As is clear from the figure, in order to simply reduce the hydrogen concentration, the source gas may be changed from NH ₃ to N ₂ and the temperature may be further increased. However, in actuality, the upper limit is about 400 ° C. in consideration of the use of large plate glass and the like, and the productivity and the structure of the apparatus. Conversely, considering the device characteristics, 2
The lower limit is about 50 ° C. This is because the thin film on the low temperature side has a high spin density, which significantly reduces the reliability of the device characteristics. That is, in the figure, the range of the black plot is considered to be a range that is satisfactory in terms of device characteristics and production.

Here, stress Stress (dyn / cm
FIG. 67 shows the relationship between ² ) and the hydrogen concentration C _H (%). As the hydrogen concentration decreases, the stress shifts from tensile stress to compressive stress. However, in the high-quality SiN _x thin film obtained in the above-mentioned substrate temperature range of 250 ° C. or more and 400 ° C. or less, the stress of the SiN _x film using NH ₃ shows almost tensile stress. In the case of using N ₂ shows a large compression stress. The black plots in the figure indicate that a high-quality SiN _x thin film can be realized, and the shaded areas indicate the controllable hydrogen concentration range and stress range. That is, the stress is considered to have a slight compressive stress, that is, device quality.
SiN _x showing a compressive stress of × 10 ⁹ dyn / cm ² or less
It turns out that a thin film cannot be formed.

Therefore, when NH ₃ is used, the hydrogen concentration in the film can be controlled by changing the NH ₃ / SiH ₄ ratio. FIG. 68 shows the relationship. As can be seen from the figure, when the hydrogen concentration is decreased, N / Si is decreased, and the film quality such as the optical band gap is decreased.
₃ / SiH ₄ can not be lowered ratio. Similarly, when N ₂ is used, the hydrogen concentration is increased to control the stress.
The film quality such as the / Si ratio is deteriorated.

That is, the film forming conditions are set such that the hydrogen concentration is reduced, the stress is slightly compressed, the N / Si ratio at that time is close to the stoichiometric ratio, the optical band gap is large, and the spin density is small. There is a problem that it cannot be obtained.

Next, problems relating to a method for manufacturing a microcrystalline silicon film will be described.

The above-described conventional manufacturing method has the following problems particularly when microcrystalline silicon containing impurities is formed. Using silane gas, if necessary, dilute with hydrogen gas to generate plasma at a high frequency of 13.56 MHz RF band, and decompose the film forming gas by the plasma,
The method of depositing microcrystalline silicon on a substrate generally has a low gas utilization efficiency. Therefore, introduce impurity gas,
When microcrystalline silicon containing impurities is formed, there is a problem that the doping efficiency is low. Further, in the conventional method, conditions for causing microcrystallization in the film are severe, and it has been difficult to form a desired microcrystalline film. Therefore, the doping efficiency could not be easily increased. Consider a case where an n-type microcrystalline silicon film is formed in a conventional parallel plate type film forming apparatus. Silane gas 3 sccm, hydrogen gas 10
Phosphine gas diluted to 0 ppm 150 sccm,
When the film is formed under standard conditions of a pressure of 0.5 Torr and an RF power of 50 mW / cm ² , the doping efficiency is 10
%Met. This means that 90% of the phosphorus atoms in the film do not work as a dopant.

The method of improving the RF plasma CVD method using the above-described VHF band (see the Lectures on Applied Physics in Autumn 1990 and Spring 1991 (28p-MF-14, 2
8p-S-3), Tokyo Tech, Oda, etc., JP-A-3-644.
No. 66, etc.), the conditions were not optimized, and the method for producing an amorphous silicon film,
However, it has not been sufficient to solve the problems relating to the method of manufacturing the silicon film and the method of manufacturing the microcrystalline silicon film .

An object of the present invention is to improve the conventional VHF film forming method and to provide optimum conditions for the problems to be solved by the present inventors.

Another object of the present invention is to increase the decomposition efficiency of nitrogen gas and silicon fluoride gas, increase the utilization efficiency of film forming gas, prevent degassing from the chamber due to the effects of ions in plasma, It is an object of the present invention to provide a manufacturing method capable of reducing damage, reducing manufacturing cost and easily forming a high-quality amorphous silicon nitride film, and obtaining a good semiconductor device.

Another object of the present invention is to reconsider the frequency of 13.56 MHz in the conventional RF plasma CVD method and increase the decomposition efficiency of the source gas by using a high-frequency discharge. As a result, the conventional SiN _x using NH ₃ is used. Reduce the hydrogen concentration in the thin film,
At the same time, it is an object of the present invention to provide a manufacturing method for controlling a stress to obtain a higher quality SiN _x thin film corresponding to a large area device at a lower cost.

Another object of the present invention is to provide a manufacturing method capable of increasing the utilization efficiency of a film forming gas, reducing the manufacturing cost and easily forming a more suitable microcrystalline silicon film, and obtaining a good semiconductor device. To provide.

Another object of the present invention is to provide a high-quality, low-cost non-single-crystal semiconductor device.

[0049]

SUMMARY OF THE INVENTION Amorphous silicon of the present invention
The method for producing the film is such that a film forming pressure P (Torr) is obtained by using at least a silicon compound as a source gas in a plasma CVD method.
r) is set to 0.25 Torr or more and 2.5 Torr or less, and the frequency f (MHz) of the high-frequency power supply is 30 MHz or more and 120 MHz or less, preferably 50 MHz or more and 100 MHz or less.
MHz or less and the input power P _W (W / c
m ² ) is equal to or less than the value specified by the relationship of 10 / f (MHz), and the inter-electrode distance d (cm) is set to a value larger than the value specified by f / 30. It is possible to cope with the increase in the area, improve the film characteristics, perform high-speed film formation, and further improve the interface characteristics that influence the device characteristics .

The method for producing an amorphous silicon nitride film according to the present invention comprises the steps of:
In a manufacturing method for depositing an amorphous silicon nitride film using a mixed gas containing a gas containing nitrogen, and a hydrogen gas, a VHF high frequency having a frequency f of 30 MHz or more is set to a distance d (cm) between electrodes. ) And f / d <30
And a plasma is generated so as to satisfy 30 MHz.
VHF high frequency above, preferably 50MHz to 100M
When the high frequency of Hz is d (cm) and the electrode distance is d (cm), f
/ D <30, the electron density in the plasma is increased, the decomposition efficiency of the hardly decomposed nitrogen gas and silicon fluoride gas is increased, and the amorphous material having a good quality distribution is easily improved. It is intended to provide a silicon nitride film. Furthermore, by utilizing the trapping of ions in the plasma, unnecessary degassing from the chamber is suppressed, contamination of impurities such as oxygen into the film is prevented, and a high-quality film with little ion damage to the film is provided. Things.

Further, the production of the amorphous silicon nitride film of the present invention
In the plasma CVD method, at least a mixed gas containing a silicon compound and ammonia is used as a source gas and the frequency of a high-frequency power source is set to 30 MHz in order to shift the stress slightly to the compression side without lowering the film quality.
Not less than 120 MHz, preferably not less than 50 MHz1
00 MHz or less, and the distance d (cm) between the electrodes is f / 30
And the input power is 30 mW
By setting the ratio to / cm ² or more, it is possible to improve the film characteristics, perform high-speed film formation while coping with an increase in the area, and further improve the device characteristics.

Also, the method for manufacturing the microcrystalline silicon film of the present invention
The method is a manufacturing method of depositing a microcrystalline silicon film using a gas containing Si by a plasma CVD method,
VHF high frequency with applied high frequency f of 30 MHz or more
/ F (W / cm ² ) (f: MHz) or more, and when the distance between the electrodes is d (cm), application is performed so as to satisfy f / d <30, and the emission intensity of hydrogen radical [H ^* ] And the emission intensity of the silane radical [SiH ^* ] is [H ^* ] ≧ [Si
H ^* ], which is a method for producing a microcrystalline silicon film, characterized in that a VHF high frequency of 30 MHz or more, preferably 50 MHz to 100 MHz.
By using high frequency of z, electron density in plasma is increased, gas decomposition efficiency is increased, and high quality doping efficiency and high quality microcrystalline silicon with less ion damage are utilized by utilizing ion trapping in plasma. Providing a membrane.

Further, the non-single-crystal semiconductor device of the present invention
The method of manufacturing an amorphous silicon film according to the present invention, and / or
The method for producing a crystalline silicon nitride film is used for a semiconductor device having an insulated gate transistor structure such as a TFT ,
In this case, it is preferable that the gate insulating layer and / or the ohmic contact layer be formed by a plasma CVD method using a high-frequency discharge of a frequency of 30 MHz or more. If each layer is continuously formed without being released to the atmosphere, the discharge frequency can be appropriately selected in consideration of the quality of each layer.
it can.

[0054]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a detailed description and embodiments of the present invention will be described with reference to the drawings.

The configuration of the non-single-crystal semiconductor device according to the present invention will be described in the following description of the method of manufacturing each amorphous silicon film according to the present invention .

First, a method of manufacturing the amorphous silicon film of the present invention
The method will be described.

Here, first, the film growth process by the plasma CVD method will be outlined, and then the details of the present invention will be described.

In general, the growth process of an a-Si thin film can be categorized into the following processes. Here, SiH ₄ is taken as an example of the source gas. (1) Radical generation process in glow discharge plasma of SiH _{4 In} this process, the energy distribution of electrons in the plasma has a peak at several eV, Maxwell-Boltzma.
nn distribution, such electrons are SiH ₄
Repeats inelastic collisions with molecules to generate various radicals, ions, and atoms. The main precursor for film growth is SiH
₂ , The possibility of SiH ₃ radical is high. (2) Transport process of generated radicals to substrate In this process, neutral radicals generated in the plasma are transported to the substrate surface by diffusion while causing various secondary chemical reactions mainly with SiH ₄ molecules. You. Considering the generation rate of radicals in plasma and the reaction life in the transport process, it is estimated that most of them reaching the substrate surface are SiH ₃ radicals. However, Si, SiH, S
As the arrival density of radicals such as iH ₂ increases, the film quality deteriorates due to the difference in the reaction mode on the surface. (3) Film growth process on the substrate surface In this process, the radicals that have reached the film growth surface are adsorbed on the surface, diffuse the surface, form chemical bonds with stable sites, and form an amorphous network. In the case of a hydrogen-coated surface, SiH ₃ radicals are sufficiently diffused on the surface, chemically bond to stable sites, and a high-quality film can be obtained.

By controlling the external parameters of the plasma in each of the above-described processes so that the SiH ₃ radical mainly reaches the film growth surface and the substrate surface is coated with hydrogen so that the radical is diffused, high quality a -Si thin film can be formed.

The present inventors have recognized that it is important to control radicals in order to form a high-quality a-Si thin film. Were examined using plasma emission analysis. This analysis is important in a silicon compound ^{plasma, Si *, SiH *, H} 2 *, H * emission line can be confirmed, the relationship between the emission intensity of In this and SiH ^* (414nm) H ^* and (656 nm) That is, it became clear that the magnitude of the strength was deeply related to the quality of the a-Si thin film. In particular, the emission intensity ratio [H ^* ] / [SiH ^* ]
(Emission intensity of SiH ^* and H ^*
H ^* ] and [H ^* ] are preferably the minimum values, but the relationship between the emission intensities is [Si
If H ^* ] ≧ [H ^* ], an almost satisfactory a-Si thin film can be obtained.

FIG. 1 shows the emission intensity ratio [H ^* ] / [SiH ^* ].
And the relationship with the hydrogen bonding mode in the thin film, that is, the relationship with the film quality.

Generally, in an infrared absorption analysis of an a-Si thin film, the absorption peak appearing at 2000 cm ^{−1 to} 2100 cm ^{−1 is} determined by the stretching vibration (2000 c ⁻¹⁾ of the Si—H bond.
m ^-1 ) and stretching vibration of Si-H ₂ bond (2100 cm
^-1 ), 2000 cm ^{-1 to} 2100 cm
It can be considered that the median value Rm (cm ^-1 ) of the absorption peak appearing at ^-1 indicates the ratio between the SiH bond and the SiH ₂ bond contained in the thin film. Here, for example, the median Rm is 2
If the shift from 000 cm ^-1 to 2100 cm ^-1 is S
This is an increase in iH ₂ bonds, and a chain bond or a cyclic bond of Si generates defects contained in the film, thereby deteriorating the film quality.

That is, as shown in FIG. 1, the emission intensity ratio [H
^* ] / [SiH ^* ] increases, the median Rm also increases to 21.
In other words, the shift to the 00 cm ^-1 side means that if the emission intensity ratio [H ^* ] / [SiH ^* ] increases, a-S
It can be said that the i-film quality deteriorates. In our opinion, [S
If iH ^* ] ≧ [H ^* ], an almost satisfactory a-Si thin film can be obtained.

Next, the distance between the electrodes, which is the premise of the present invention, will be described.

As shown in FIG. 2, when the frequency is large for a certain distance d between the electrodes, the film thickness distribution in the substrate becomes large. This poses a serious problem for increasing the area. Therefore, the present inventors, for various deposition parameters,
As a result of improvement, it was found that the distance between the electrodes affected the film thickness distribution, and it was further found that the film thickness distribution was reduced by increasing the distance between the electrodes. Under various conditions of the present invention, the film thickness distribution T (%) in the substrate is 10%.
%, The relationship was determined, and d = 2
cm, the distribution is remarkably large, not within the usable range. When d is larger than 3 cm, f (MHz) /
It has been found that if d satisfies d (cm) <30, generally good distribution can be obtained.

FIG. 3 shows the relationship between the distance between the electrodes and the density of defect states in the film under various conditions. It can be seen that when the distance between the electrodes exceeds 4 cm, the density of defects gradually decreases.
It can be seen that when the distance between the electrodes is smaller than 4 cm, the value rapidly increases. It is understood that the distance between the electrodes is preferably 4 cm or more. In this embodiment, the distance between the electrodes is 4c.
The study was performed as m.

Considering the film forming mechanism described above, high quality a
In order to obtain -Si film quality, it is necessary to sufficiently coat the substrate surface with hydrogen. Therefore, a mixed gas obtained by diluting SiH ₄ with H ₂ is introduced into the plasma reaction chamber at a ratio of SiH ₄ : H ₂ = 1: 9, and the input power P _W = 0.07 _W / cm ^{2 at} a frequency f = 80 MHz. Was discharged. FIG. 4 shows the relationship between the pressure P (Torr) at this time and the emission intensity of the SiH ^* and H ^* radicals. In order to obtain satisfactory a-Si film quality, as described above, the relationship between the emission intensities is [Si
The pressure P (Torr) that satisfies H ^* ] ≧ [H ^* ] is P ≧ 0.
Although the area is 25 Torr, when P> 2.5 Torr, foreign substances (polysilane) that lower the yield occur. On the other hand, in the region where the pressure P is P <0.25 Torr,
This leads to a decrease in film quality such as an increase in the amount of hydrogen in the thin film and an increase in SiH ₂ bonds. That is, the pressure P is 0.25 Torr or more.
High-quality a-Si film quality can be obtained at 5 Torr or less. Similarly, frequency f = 13.56, 30, 50, 10
When the relationship with the emission intensities of 0, 120, and 150 is obtained, each emission intensity increases as f increases, but [SiH] /
The [H] ratio did not change significantly.

Next, as an example, the pressure P is set to P = 0.5T.
fixed at orr, the frequency f of the high-frequency power supply = 13.5
At each of 6, 80 and 150 MHz, the input power P
The relationship between _W and the emission intensity of SiH ^* and H ^* radicals is shown in FIG.
As shown in FIG. In the figure, the white circles and white plots indicate [Si
H ^* ] ≧ [H ^* ], and the black circle and black plots are the conditions [SiH ^* ] <[H ^* ]. FIG. 7 shows the relationship between each frequency f and the input power P _W where the relationship of the light emission intensity is [SiH ^* ] ≧ [H ^* ]. According to FIG.
As the conditions for obtaining the i-thin film, the physical meaning is still unknown, but the input power P _W (W / c
m ² ) must be equal to or less than the value defined by the relationship of 10 / f (MHz), and this range is indicated by oblique lines. The white circle plots in the figure are the conditions under which a high-quality a-Si thin film could be obtained, and the black circle plots were the conditions for a low-quality a-Si thin film. In addition, as an optimum condition of a high-quality a-Si thin film, the emission intensity ratio [H ^* ] / [Si
H ^* ] was selected for the input power P _{W at} which the minimum value was obtained, and a film was formed.

FIG. 8 shows the relationship between the power supply frequency f at each deposition pressure of the a-Si thin film and the median value Rm in the infrared absorption analysis. The input power at this time is [H ^* ] / [Si
[H ^* ] ratio is the optimum input power at which the ratio becomes minimum. For example, 80
In MHz and 0.5 Torr, it is 0.04 W / cm ² . In the region where the frequency f is less than 30 MHz, ion damage incident on the substrate is large, the content of SiH ₂ bonds in the film is large, and the film has many defects.
Is higher than 120 MHz, the SiH
The content of _two bonds increases, and the film quality deteriorates. It is presumed that the reason is that Si, SiH, and SiH ₂ radicals, in which SiH ₄ molecules are excessively decomposed, increase and SiH ₃ radicals decrease as the shift to high frequency discharge occurs. Furthermore, this region has a film thickness and
Problems such as the problem of film quality distribution come out.

When the film forming pressure is in the range of 0.25 to 2.5 Torr, a high-quality a-Si film can be obtained as shown in the figure, but a high-quality a-Si film cannot be obtained at other film forming pressures. This is considered to be due to the fact that the damage of the substrate incident ions increases in the range of p <0.25, and the generation of polysilane starts in the range of p> 2.5. Similarly, FIG. 9 shows the relationship between the frequency f and the spin density using each film forming pressure as a parameter.

As an example, FIG. 10 shows the relationship between the frequency f at a pressure of 0.5 Torr and an input power of 0.04 W / cm ² and the film forming rate DR, and the photoconductivity σ _p (S / c
FIG. 11 shows the frequency dependence of the S / N ratio, which is the ratio between m) and the dark conductivity σ _d (S / cm). FIG. 12 summarizes the relationship between the deposition rate and the S / N ratio for each frequency.

According to these results, the frequency is 30 MHz
If the range is not less than 120 MHz and high quality, and
An a-Si thin film having high productivity can be formed.
If the frequency is 0 MHz or more and 100 MHz or less, improvement in photoelectric characteristics can be expected.

Next, pressure P = 0.5 Torr, frequency f
= 80 MHz, input power P _W = 0.04 _W / cm ² , and the residence time τ (sec) was confirmed. here,
The residence time τ (sec) is defined as the time when the source gas Q (sccm) is introduced into the discharge space V (cm ³ ) and the pressure P (Torr).
When r) is controlled to be constant, it is the time during which the source gas stays in the discharge space, and is expressed by the following equation.

Τ = 78.947 × 10 ⁻³ × V × P / Q FIG. 13 shows the relationship between the residence time τ and the emission intensity of SiH ^* and H ^* radicals. As described above, in order to obtain a high-quality a-Si thin film, the relationship between the emission intensities is [SiH ^* ] ≧
[H ^* ], the residence time τ needs to be 2.5 sec or less. In the drawing, the white circles and white plots are conditions where [SiH] ≧ [H], and the black circles and Δ plots are conditions where [SiH] <[H]. FIG. 14 shows the change in the film quality due to the residence time τ at this time represented by the median Rm in the infrared absorption analysis. Residence time τ> 2.5
In the region, it can be confirmed that the ratio of SiH ₂ bonds in the a-Si thin film is increased, and the film quality is deteriorated. Similarly, the photoconductivity σ _p (S / c) shown in FIG.
m) and the dark conductivity σ _d (S / cm), the S / N ratio was also found to decrease when the residence time τ> 2.5 sec.

That is, it can be confirmed that the residence time τ is desirably 2.5 seconds or less.

FIG. 16 shows the relationship between the residence time τ and the film forming rate DR, and FIG. 17 shows the relationship between the in-substrate film thickness distribution _TE (%). Here, assuming that the maximum thickness and the minimum thickness of the thickness distribution in the substrate are T _MAX and T _MIN , respectively, T _E =
(1−T _MIN / T _MAX ) × 100. In addition,
The substrate size is 30 cm square. In FIG. 16, when the residence time τ is less than 0.05 sec, the film forming rate starts to decrease, and similarly, when the residence time τ is 5 sec or more, the film forming rate decreases. This is because when the residence time τ is short, the reactive radicals generated by the discharge are exhausted out of the system before reaching the substrate surface, and when the residence time τ is long, It is considered that the film formation rate is reduced due to the shortage. The same can be said for FIG. When the residence time τ is less than 0.05 sec, a distribution according to the source gas flow occurs, and the residence time τ is 5 s.
When it is larger than ec, distribution occurs from the introduction portion of the source gas. The distribution is preferably 10% or less as a guide.

That is, the residence time τ is τ <0.05 sec.
In the region, the film formation rate decreases and the film thickness distribution increases, so that the residence time τ is 0.0
5 seconds or more.

From these results, the residence time τ (se) is required to manufacture large-area thin-film devices with good yield and uniformity.
It is necessary that c) is not less than 0.05 sec and not more than 2.5 sec. Desirably, if it is not less than 0.1 sec and not more than 2.5 sec, improvement of the photoelectric characteristics can be expected as shown in FIG.

Next, an embodiment of a field-effect transistor using an a-Si thin film manufactured by the film forming method according to the present invention will be described.

FIG. 18 is a sectional view of an inverted stagger type TFT.

A gate electrode 12 is formed on an insulating substrate 11, and an insulating layer 13 and a semiconductor layer 14 are further formed thereon.
Are laminated. Source / drain electrodes 16 are formed on the semiconductor layer 14 via an ohmic contact layer 15. And it is covered with the protective film 17. Next, a method for manufacturing this TFT will be described with reference to FIGS.
This will be described with reference to FIG.

First, as shown in FIG. 19A, a Cr thin film (approximately 1000 °) is formed on a 7059 glass substrate 21 made of Corning by a sputtering device and patterned to form a gate electrode 22.

Then, silicon nitride, SiN _x (about 30
00Å) A thin film is formed, and then, as a semiconductor layer 24,
Non-doped amorphous silicon, i-type a-Si (about 6000
Å) As a thin film, ohmic contact layer 25, phosphorus-doped microcrystalline silicon, n ⁺ -type μc-Si (about 1000
Å) Thin films are sequentially formed by the same apparatus.

Second, as shown in FIG. 19B, an Al thin film (approximately 1 μm) is formed by a sputtering device and patterned to form a source / drain electrode 26. The channel width W and the channel length L were W / L = 100.

Third, as shown in FIG. 19C, unnecessary n ⁺ -type μc-S
The i-layer is etched to form the gap 28.

Fourth, as shown in FIG. 19D, after further unnecessary SiN _x / i-type a-Si / n ⁺ -type μc-Si layers are isolated, a protective film 27 is deposited. Eighteen thin film transistors are created.

Here, a-Si, which is the point of the present invention, is used.
The method for producing a thin film will be described in detail.

As described in the first embodiment, the formation of the a-Si thin film is performed by a parallel plate type plasma CVD apparatus as shown in FIG. The figure shows a film forming chamber for an i-type a-Si thin film, and a mechanism for continuously forming a SiN _x / i-type a-Si / n ⁺ -type μc-Si layer, and other film forming chambers are not shown. It is. In the figure, 300 is a vacuum chamber, 301 is a substrate, 302 is an anode electrode, 303 is a cathode electrode, 304 is a heater for heating a substrate, 305 is a grounding terminal, 306 is a matching box, 307 is a high-frequency power source, and 308 is a high-frequency power supply. Exhaust port, 309 is an exhaust pump, 310
Denotes a material gas inlet, 320, 340, 322, and 342 denote valves, and 321 and 341 denote mass flow controllers.

A substrate is carried in from a not-shown SiN _x film forming chamber in the front chamber, and the chamber is evacuated until the chamber becomes 1 × 10 ⁻⁶ Torr or less. Next, the raw material gases SiH ₄ and H ₂ are supplied to the mass flow controllers 321 and 341 for 2, 1
8 sccm, the pressure was maintained at 0.5 Torr, the substrate heater 304 was set, and the substrate temperature was 200 ° C.
, And a frequency of 80 MHz and a power of 0.04 W / cm ² were applied from the high frequency power supply 307 to obtain i
A type a-Si film is formed at 6000 °. After film formation, the chamber is similarly evacuated to 1 × 10 ⁻⁶ Torr or less. Next, the film is moved to an n ⁺ -type μ-Si film forming chamber in a next chamber (not shown).

In this manner, a thin film transistor can be manufactured. As an embodiment of the present invention, a high-frequency discharge of 80 MHz is taken as an example. However, when the frequency f is changed, the input power P _W (W / cm ² ) is 10 / f (MH).
z) or less, and desirably the input power at which the emission intensity ratio [H ^* ] / [SiH ^* ] becomes the minimum value. FIG. 21 shows the frequency f (MHz) dependence of the electric field mobility μ (cm ² / Vsec) of the TFT using the a-Si thin film formed at each frequency f. In the figure, when the frequency f is 30 MHz or more and 120 MHz or less, the electric field mobility μ is improved, and the maximum value is 0.88 cm ^{2 at} 80 MHz, compared with 0.47 cm ² / Vsec of the conventional 13.56 MHz discharge a-Si thin film. / Vsec and about 2
Doubled. The reason can be considered from the difference between the substrate incident ion energies in the argon (Ar) discharge shown in FIG. In the high frequency discharge at 80 MHz of the present invention, the conventional 13.56 MHz
In comparison with the discharge in the above, the ion energy that reaches the substrate is small and the energy dispersion is small. Therefore, when the a-Si thin film is laminated, the SiN _x thin film which is the gate insulating film is formed. It is considered that the interface characteristics were improved without causing ion damage.

It is also possible to determine the frequency depending on which of the film characteristics, productivity, device characteristics, etc., is emphasized.

Next, an embodiment of a field-effect transistor using an a-Si thin film manufactured by a film forming method according to a reference example of the present invention will be described.

The inverted stagger type TF to be manufactured
The structure of T, its manufacturing process, and the structure of a parallel plate type plasma CVD apparatus used for forming an a-Si thin film are the same as those shown in FIGS. Only the method of manufacturing the Si film will be described below.

The substrate is carried in from a not-shown SiN _x film forming chamber in the front chamber, and the chamber is evacuated until the chamber becomes 1 × 10 ⁻⁶ Torr or less. Next, the raw material gases SiH ₄ and H ₂ are supplied to the mass flow controllers 321 and 341 to obtain SiH ₄ and H _2.
4 : H ₂ = 1: 9, the pressure was maintained at 0.5 Torr, and the flow rate was adjusted so that the residence time τ was 1.0 sec. After setting the substrate heater 304 and keeping the substrate temperature at 200 ° C., a frequency of 80 MHz and a power of 0.04 W / cm ² were applied from the high frequency power supply 307 to form the i-type a-Si film at 6000 ° C. Form a film. After film formation, the chamber is similarly evacuated to 1 × 10 ⁻⁶ Torr or less. Next, the film is moved to an n ⁺ -type μ-Si film forming chamber in a next chamber (not shown).

In this way, a thin film transistor can be manufactured. As an example of the present invention, a high-frequency discharge of 80 MHz was taken as an example. Of course, when the frequency f is changed, it is preferable that the emission intensity ratio [SiH ^* ] ≧ [H ^* ] be satisfied. , Emission intensity ratio [H ^* ] / [SiH
^* ] Is changed to the condition such as the input power at which the minimum value is shown. Residence time τ (sec) and average electric field mobility μ (cm ² ) in the substrate
/ Vsec) is shown in FIG. Considering the characteristic distribution, when the residence time τ (sec) is 0.05 sec or more and 2.5 sec or less, a good electric field mobility μ (cm
² / Vsec).

Next, the production of the amorphous silicon nitride film of the present invention is described.
The fabrication method will be described.

FIG. 24 shows a manufacturing apparatus used in the embodiment of the present invention. The basic structure is the same as that of a conventional parallel plate type plasma CVD apparatus.

In the figure, reference numeral 400 denotes a vacuum chamber,
01 is an anode electrode, 402 is a substrate, and 403 is a cathode electrode. The anode electrode 401 is grounded at 406. 404 is a matching device, and 405 is a high frequency power supply.
407 is a gate valve, 408 is a turbo molecular pump, 4
09 is a rotary pump. 410 and 420 are silane gas line valves, 411 and 421 are hydrogen gas line valves, 412 and 422 are phosphine gas line valves, 413 and 423 are diborane gas line valves,
14, 424 are silicon fluoride gas line valves, 41
5 to 419 are mass flow meters. If attention is paid to how to apply a high frequency and to handling, this embodiment can be applied not only to the parallel plate type as in this embodiment but also to the carousel electrode type used in the manufacture of the photosensitive drum.

First, the principle of the manufacturing method according to the present invention will be described. FIG. 25 shows the applied high frequency f dependence of the emission intensity [SiH ^* ] of the SiH ^* radical (414 nm) and the emission intensity [N ^* ] of the nitrogen radical. FIG. 29 shows the dependency of the deposition rate R on the applied high frequency f. The emission intensity of SiH ^* radicals [SiH ^*] in FIG. 26, the emission intensity of nitrogen radicals [N
^* ] Shows the applied high frequency power Pw dependency. The conditions at this time are SiH ₄ 3 sccm, hydrogen 30 sccm, nitrogen 60
sccm, pressure 0.2 Torr. In FIG. 25, Pw = 10 mW / cm ² , and in FIG. 26, f = 80 MHz.
And

As shown in FIG. 25, when the applied high frequency f is increased, SiH ^* radicals and nitrogen radicals in the plasma
It has increased accordingly. However, f = 80M
It can be seen that it has a maximum value around Hz, and thereafter it tends to decrease. Since the decomposition rate of the silane gas and nitrogen gas depends on the electron density n _e in the plasma, SiH ^* radicals and N ^* radicals generated by the decomposition also depends on the electron density n _e. Therefore the electron density n _e in the plasma indicates an applied high frequency f-dependent, the light emission intensity of the radical accordingly,
This seems to indicate the dependence as shown in FIG.

As shown in FIG. 29, the film formation rate R also increases as the applied high frequency f increases, and has a maximum around f = 100 MHz. However, in the region exceeding 100 MHz, the film thickness distribution on the substrate became large, and polysilane was easily formed, which became dust and pinholes were formed and the cost was reduced. In addition, uniform film properties were not obtained. Therefore, preferably from 30 MHz to 100 MHz
The effect of the present invention can be sufficiently exhibited in the above frequency band. Generally, the film formation rate in silane gas is proportional to [SiH ^* ], and the tendency in FIG. 29 seems to depend on the tendency of [SiH ^* ] in FIG.

From FIG. 26, when the applied high frequency power is increased, [S
Both iH ^* ] and [N ^* ] tend to increase.

The film forming speed can be increased by increasing the applied high frequency. It is also possible to reduce the applied power accordingly. This is particularly effective when the size of the apparatus is increased and a film is formed in a large area. That is, the size of the high-frequency power supply can be reduced for the size of the device, and the cost of the device can be reduced. Also, in terms of the effect on the film properties, if it can be made in a region where the applied power is small, the overall energy of the ions in the plasma will decrease, so reducing the damage caused by ions incident on the film surface And a film having good film properties can be formed. Attention is also paid to the movement of ions in plasma from the viewpoint of reducing ion damage. In general, ions in a high-frequency plasma vibrate in the plasma according to an electric field oscillating by a high frequency in the plasma. This situation can be expressed as follows. Here, A is the oscillation amplitude of the ions.

A ≒ V / w V: Maximum speed in one cycle of high frequency w: Angular frequency of high frequency: f = 2πw The film forming apparatus under consideration is a parallel plate type apparatus, and the distance between the electrodes is d. . Then, if the condition of d> A is satisfied, ions in the plasma will move back and forth in the plasma without reaching the substrate. Such a state is generally referred to as a state captured or trapped in plasma. As is apparent from this relational expression, by increasing the applied high frequency, a trapped state of ions can be created regardless of the size of the device. By doing so, the amount of ions incident on the substrate could be reduced. As a result, ion damage on the film surface and in the film could be reduced.

FIG. 22 described above illustrates this state. A mass spectrometer was installed at the substrate position, and the distribution of the incident energy and incident amount of the ions entering the mass spectrometer was determined. This data was obtained for argon gas to facilitate analysis. The reaction gas of the present invention shows essentially the same tendency. Conventional applied high frequency f
Under the condition of 13.56 MHz and f = 80 MHz according to the present invention, the incident energy and the incident amount of ions incident on the substrate are different. Obviously, under the condition of f = 80 MHz, the average incident energy is lower and the incident amount is reduced.

The above-mentioned effects are applied not only to the substrate but also to the chamber wall, and the number of ions hitting the chamber and the energy can be reduced. Degassing could be reduced. The present invention is intended to actively utilize such a state.

As already described with reference to FIG. 2, if the frequency is large for a certain distance d between the electrodes, the distribution becomes large. This poses a serious problem for increasing the area. Therefore, the present inventors have tried to improve various film forming parameters, and found that the distance between the electrodes has an influence on the film thickness distribution. Was found to be smaller. Under various conditions of the present invention, the relationship was determined under the condition that the film thickness distribution T (%) in the substrate was within 10%. When d = 2 cm, the distribution was remarkably large. Where f / d <30 where d is greater than 3 cm
Then, it was found that a good distribution can be obtained in general.

As shown in FIG. 3 showing the relationship between the distance between the electrodes under various conditions and the density of defect states in the film, when the distance between the electrodes exceeds 4 cm, the density of the defects gradually decreases. It can be seen that when the distance between the electrodes is smaller than 4 cm, the value rapidly increases. The distance between the electrodes is preferably 4
cm or more is desirable. Therefore, in the present embodiment, a study was performed with the distance between the electrodes being 4 cm.

Based on the above experimental facts and considerations, amorphous silicon nitride was produced by the production method of the present invention using a mixed gas of silane gas, hydrogen gas and nitrogen gas.

As shown in FIG. 24, the glass substrate 402 was mounted on the anode electrode 401 in the chamber 400, and was evacuated by the evacuation pump 409 to 10 ^-6 Torr. The substrate temperature was set to 350 ° C., and SiH ₄ gas was
sccm, H ₂ gas at 30 sccm, and nitrogen gas at 6 sccm.
At 0 sccm, the pressure in the chamber was set to 0.2 Torr and maintained for 30 minutes. After that, high-frequency power was applied and the matching device was adjusted to start discharge, and discharge was performed for a necessary time to form a film.

The applied high frequency is f = 13.56 MHz (according to
( Example) and f = 80 MHz (Example 1) . The high frequency power at this time is 30 mW / cm at f = 13.56 MHz.
² and ² mW / cm ² at f = 80 MHz. For comparison of film characteristics, the film forming speed was adjusted to 1 ° / sec.

An aluminum comb electrode was deposited on this film, and the resistivity was measured at room temperature (25 ° C.). The optical band gap E _gopt was also measured using these samples.
It was constant. The amount of impurities in the film was measured by a secondary ion mass spectrometer.

Table 1 shows the resistivity and the optical band gap E _gopt of the film formed under these conditions. The oxygen concentration in the film, the hydrogen concentration, and the spin density in the film are shown.

[0114]

[Table 1] This is because, by increasing the applied high frequency f, ions in the plasma are in a trapped state, and the flux of ions incident on the substrate surface and the chamber wall is reduced. Impurities in the film are surely reduced because there is no impact from the chamber wall. It is considered that the spin density in the film was realized because the impurities in the film were reduced and the ion damage during the film formation was reduced. In the present embodiment, the higher resistivity is due to Si-Si, Si-
This is probably because the bond inconsistency such as N was improved by reducing the ion damage.

Next, the amorphous silicon nitride film under the above conditions was used as a gate insulating film of a thin film transistor and evaluated. FIG. 35 shows a device configuration.

On a glass substrate 131, aluminum was formed in a thickness of 1000 ° by a vacuum evaporation method, and was patterned to form a gate electrode 132.

Next, the glass substrate 131 was mounted on the anode electrode in the chamber 400 shown in FIG. 24, and evacuated to 10 ^-6 Torr by the exhaust pumps 408 and 409. The substrate temperature was set to 350 ° C. and SiH ₄ gas was supplied for 3 seconds.
flushed ccm, H ₂ gas flow 30 sccm, the nitrogen gas flow 60 sccm, and the pressure in the chamber to 0.2 Torr, and maintained for 30 minutes, the substrate temperature is waiting for stability. After that, high-frequency power was applied and the matching device was adjusted to start discharge, and discharge was performed for a necessary time to form a film. At this time, several frequencies were applied around f = 80 MHz. The high-frequency power was set so that the film formation rate was adjusted to 10 ° / sec. After the discharge, the gas is evacuated to 10 ^-6
High vacuum was applied to Torr.

Next, the substrate temperature was set to 250 ° C.
The H ₄ gas was flowed at 3 sccm, the H ₂ gas was flowed at 30 sccm, the chamber internal pressure was set to 0.5 Torr, the temperature was maintained for 30 minutes, and the substrate temperature was stabilized. After that, the normal 13.56 MHz high frequency was changed to 10 mW / cm ^2.
The discharge was started by adjusting the matching device, and the film was formed by discharging for a necessary time. Discharge for 3.5 hours and 5000Å intrinsic amorphous silicon 13
4 was formed. After that, the gas is exhausted and 10 ^-6 Torr
It was evacuated to high vacuum.

Next, the substrate temperature was set to 250 ° C.
H ₄ gas was flowed at 3 sccm, phosphine gas diluted to 100 ppm with H ₂ gas was flowed at 150 sccm, the chamber internal pressure was set to 0.5 Torr, and the temperature was maintained for 30 minutes, and the substrate temperature was stabilized. Thereafter, a normal high frequency of 13.56 MHz was supplied at a power of 30 mW / cm ² , and the matching device was adjusted to start discharging, and the film was formed by discharging for a necessary time. Discharge for 30 minutes and 1500Å
Of n ⁺ type amorphous silicon 135 was formed. Thereafter, the gas was evacuated and a high vacuum was applied to 10 ^-6 Torr.

Next, the substrate is taken out of the film forming apparatus,
Aluminum 136 was formed to a thickness of 1 μm by a vacuum evaporation method.

Thereafter, this aluminum was patterned to form source and drain electrodes. Finally, using this electrode as a mask, the n ⁺ -type amorphous silicon 135 was removed by etching.

FIG. 30A shows the characteristics of a thin film transistor formed of silicon nitride at f = 80 MHz, which is typical of the thin film transistors formed as described above. It shows sufficiently good characteristics. FIG. 31B shows that the ON state is 100.
7 shows a change in the threshold voltage _Vth when maintained for a time. (A) in the figure is data of a conventional device.
Conventionally, the shift was made to the positive side with time, but according to the present embodiment, this shift has been considerably improved. Generally, this _Vth shift is caused by carriers entering the ON operation, in this case, N-channel operation, and electrons enter the insulating film and are captured by trap levels in the film, where fixed charges are formed.
Therefore, according to the manufacturing method of the present invention, it is considered that impurities in the film were reduced, ion damage during the film formation was also reduced, defects in the film were reduced, and this characteristic was improved. FIG. 34A shows the dependency of the V _th shift on the applied high frequency. It can be seen that the above effect appears from around f = 30 MHz.

Next, evaluation was performed using the amorphous silicon nitride film under the same conditions as a passivation film of a thin film transistor. However, the substrate temperature was set to 250 ° C. to avoid adverse effects on the thin film transistor. FIG. 36 shows the configuration of the device.

On a glass substrate 141, aluminum was formed to a thickness of 1000 ° by a vacuum evaporation method, and was patterned to form a gate electrode 142.

Next, the glass substrate 141 was mounted on the anode electrode in the chamber 400 shown in FIG. 24, and evacuated to 10 ^-6 Torr by the exhaust pumps 408 and 409. The substrate temperature was set to 250 ° C., and SiH ₄ gas was
flushed ccm, H ₂ gas flow 30 sccm, the nitrogen gas flow 60 sccm, and the pressure in the chamber to 0.5 Torr, and maintained for 30 minutes, the substrate temperature is waiting for stability. Thereafter, high-frequency power was applied, and the matching device was adjusted to start discharge, and discharge was performed for a necessary time to form the gate insulating film 143. At this time, the frequency is f = 13.5
6 MHz and high frequency power were 30 mW / cm ² . After the discharge, the gas was evacuated and a high vacuum was applied to 10 ^-6 Torr.

Next, the substrate temperature was set to 250 ° C.
The H ₄ gas was flowed at 3 sccm, the H ₂ gas was flowed at 30 sccm, the chamber internal pressure was set to 0.5 Torr, the temperature was maintained for 30 minutes, and the substrate temperature was stabilized. After that, the normal 13.56 MHz high frequency was changed to 10 mW / cm ^2.
The discharge was started by adjusting the matching device, and the film was formed by discharging for a necessary time. Discharge for 3.5 hours, 5000Å intrinsic amorphous silicon 14
4 was formed. After that, the gas is exhausted and 10 ^-6 Torr
It was evacuated to high vacuum.

Next, the substrate temperature was set at 250 ° C.
The H ₄ gas was flowed at 3 sccm, the phosphine gas diluted to 100 ppm with H ₂ gas was flowed at 150 sccm, the chamber internal pressure was set to 0.5 Torr, and the temperature was maintained for 30 minutes to wait for the substrate temperature to stabilize. Thereafter, a normal high frequency of 13.56 MHz was supplied at a power of 30 mW / cm ² , and the matching device was adjusted to start discharging, and the film was formed by discharging for a necessary time. Discharge for 30 minutes and 1500Å
Of n ⁺ type amorphous silicon 145 was formed. Thereafter, the gas was evacuated and a high vacuum was applied to 10 ^-6 Torr.

Next, the substrate is taken out of the film forming apparatus,
Aluminum 146 was formed to a thickness of 1 μm by a vacuum evaporation method. Thereafter, the aluminum was patterned to form source and drain electrodes.

Finally, using this electrode as a mask, the n ⁺ type amorphous silicon 145 was removed by etching. Up to this step, a conventional thin film transistor is formed.

Next, a passivation film 147 was deposited on the substrate completed up to this step by the manufacturing method according to the present invention. First, the substrate was mounted again on the anode electrode in the chamber 400, and exhausted to 10 ^-6 Torr by the exhaust pumps 408 and 409. 200 ° C substrate temperature
, The flow of SiH ₄ gas was 3 sccm, the flow of H ₂ gas was 30 sccm, the flow of nitrogen gas was 60 sccm, the internal pressure of the chamber was 0.2 Torr, the temperature was maintained for 30 minutes, and the substrate temperature was stabilized. After that, high-frequency power is turned on and the matching device is adjusted to start discharging,
The film was formed by discharging for a necessary time. At this time, the frequency is f =
Several points around 80MHz. After the discharge, the gas was evacuated and a high vacuum was applied to 10 ^-6 Torr. On a comparable thin film transistor as a comparative sample, the frequency is f
A sample provided with a passivation film having a frequency of 13.56 MHz and a high-frequency power of 30 mW / cm ² was also prepared. A typical f = 80M of the thin film transistor thus prepared
FIG. 33 shows the characteristics when a passivation film is formed at
It is shown in (c). (B) in the figure is a case where it is created by a conventional method. In the figure, (a) shows initial characteristics without a passivation film. Conventionally, the threshold voltage was shifted more positively than the initial state by attaching a passivation film due to damage by ions in the plasma, but the shift can be considerably reduced with the passivation film of the present invention. . FIG. 34E shows the dependency of the V _th shift on the applied high frequency. It can be seen that the above-mentioned effect appears around f = 30 MHz. From this experimental result, it is considered that, by increasing the applied high frequency from about f = 30 MHz, ions incident on the substrate are reduced, and ion damage during film formation is also reduced .

Next, production of the amorphous silicon nitride film of the present invention
A second embodiment according to the method will be described.

An amorphous silicon nitride film was formed by a manufacturing method according to the present invention using a mixed gas of silicon fluoride, hydrogen gas and nitrogen gas.

First, the state of the plasma at this time will be described. FIG. 27 shows the frequency dependence of the emission intensity of the SiF ^* radical. It can be seen that the emission intensity is increased by increasing the applied high frequency. This is presumably because the electron density in the plasma increased as in the case of silane gas, and the decomposition efficiency increased. FIG. 28 shows the applied power dependence of the emission intensity of the SiF ^* radical. It can be seen that the emission intensity increases as the applied power increases. In this embodiment, the applied high frequency is from 13.56 MHz to 150 MHz.

Samples were prepared under the conditions indicating these plasma states. The glass substrate was attached to the anode electrode in the chamber shown in FIG.
The air was evacuated to 0 ^-6 Torr or less. After setting the substrate temperature at 350 ° C., the valves 414 and 424 were opened to open the silicon fluoride gas at 3 sccm, and the valves 411 and 421 were opened to open H _2.
40 sccm of gas and 120 sccm of nitrogen gas flow,
Hold for 30 minutes. Thereafter, high-frequency power was applied, and a matching device was adjusted to start plasma discharge, thereby forming a film.
The thickness of all samples was about 1 μm.

FIG. 29B shows the applied frequency f of the film forming speed R.
Indicates dependence. As seen from the above plasma emission, the gas was sufficiently decomposed by increasing the applied high frequency, and a higher film formation rate than in the past could be realized.

The film prepared here was used as a gate insulating film of a thin film transistor and evaluated. The properties of the single film at this time are shown in Example 2 of Table 1. Basically, the device forming process is the same as the process in the first embodiment, and a description thereof will be omitted. f =
FIG. 30B shows device characteristics when a silicon nitride film is formed at 80 MHz. FIG. 31C shows a change in the threshold voltage V _th when the ON operation is maintained for 100 hours. FIG. 32C shows a change in the threshold voltage _Vth when the heat treatment is performed. The figure shows data of a conventional device. Good basic characteristics were obtained as in the conventional case. Also, the V _th shift due to the ON operation was reduced. This is because impurities in the film are reduced, defects due to this and defects due to plasma damage at the time of film formation are reduced, carrier trap levels are reduced as a whole, and electrons trapped by this are reduced. I think that the. In the device of this example, the diffusion of hydrogen due to heat was less likely to occur because the hydrogen in the film was suppressed, and the V _th shift to the negative side due to the heat treatment was small. FIG. 34 (b) shows the applied high frequency dependence of the V _th shift due to this ON operation, and FIG. 34 (d) shows the applied high frequency dependence of the V _th shift due to heat. f = 3
It can be seen that the above effects appear from around 0 MHz. From this experimental result, it is considered that, by increasing the applied high frequency from about f = 30 MHz, ions incident on the substrate are reduced, and ion damage during film formation is also reduced.

Next, another amorphous silicon nitride film of the present invention
The manufacturing method will be described.

First, a description will be given of the inter-electrode distance as a premise of the embodiment of the present invention.

As already described with reference to FIG. 2, when the frequency is large for a certain distance d between the electrodes, the distribution becomes large. This poses a serious problem for increasing the area. Therefore, the present inventors have tried to improve various film forming parameters, and found that the distance between the electrodes has an influence on the film thickness distribution. Was found to be smaller. When the film thickness distribution T (%) in the substrate was within 10% under various conditions of the present invention, the relationship was determined. When d = 2 cm, the distribution was remarkably large. Is 3
It has been found that at a location larger than cm, if d satisfies f / d <30, generally good distribution can be obtained.

Further, as shown in FIG. 3 showing the relationship between the distance between the electrodes under various conditions and the density of defect states in the film, when the distance between the electrodes exceeds 4 cm, the density of the defects gradually decreases. It can be seen that when the distance between the electrodes is smaller than 4 cm, the value rapidly increases. The distance between the electrodes is preferably 4
cm or more is desirable. Therefore, in the present embodiment, a study was performed with the distance between the electrodes being 4 cm.

FIG. 37 shows a manufacturing apparatus used in this embodiment. The basic structure is a conventional parallel plate type plasma C
It is the same as the VD device.

As shown in the figure, 500 is a vacuum chamber, 501 is an anode electrode, 502 is a substrate, and 503 is a cathode electrode. The anode electrode 501 is grounded. 504 is a matching device, and 505 is a high frequency power supply. 5
07 is a gate valve, 508 is a turbo molecular pump, 50
9 is a rotary pump.

First, the SiH ₄ —NH ₃ -based mixed gas is diluted with H ₂ as necessary and introduced into the vacuum chamber 500. In this embodiment, SiH ₄ was introduced at 10 sccm, NH ₃ was introduced at 200 sccm, and H ₂ was introduced at 100 sccm using mass flow controllers 515, 516, and 517, and the pressure was maintained at 0.2 Torr. The frequency f of the high frequency power supply was changed from 13.56 MHz to 150 MHz. At this time, the input power for film formation was 10 mW / cm ^2.
The above is sufficient, but in the present embodiment, it was set to 30 mW / cm ² in consideration of distribution and the like.

FIG. 38 shows the relationship between the power supply frequency f and the film forming speed DR. The figure is for a substrate temperature T _{S of} 350 ° C. The deposition rate does not depend on the substrate temperature, but has a peak with respect to the frequency. The reason is that, as the discharge frequency increases, the decomposition of the source gas is promoted, and the film formation rate increases once. However, when the frequency is further increased, the film formation rate decreases because the source gas and the precursor start to be excessively decomposed. It is estimated that it is. Next, showed the power frequency f and intramembranous hydrogen content C _H at each deposition temperature in Figure 39. The relationship between the amount of hydrogen in the film and the stress at each substrate temperature of 350 ° C., 250 ° C., and 150 ° C. is shown in FIGS. From the figure, it can be seen that a slight compressive stress (specifically, in the present invention, the optimal value is 1 × 10 ⁹ dyn / cm ² or more and 4 × 10
⁹ dyn / cm ² or less), the frequency of the high-frequency power supply should be 30 MHz to 120 MHz at a substrate temperature of 250 ° C. or more and 350 ° C. or less for realizing a conventional high quality film.
It can be realized by setting z or less.

Next, the relationship between the frequency and the spin density in the film is shown in FIG. The figure shows the frequency dependence at a substrate temperature of 350 ° C., but the same tendency was observed at a substrate temperature of 150 ° C. or higher. That is, it is estimated that in a low region where the frequency f is lower than 30 MHz, ion damage incident on the substrate is large, and the film has many defects. As described above, FIG. 22 in which a mass spectrometer is installed at the substrate position and the distribution of the incident energy and the incident amount of the ions entering the substrate is obtained is an example of the basis. This uses argon gas to facilitate data analysis. As is clear from this, in the RF discharge at 13.56 MHz, a high energy component is incident on the substrate. If the frequency f is 120
Even in a region exceeding MHz, the film quality is deteriorated. It is presumed that the reason is that the raw material gas and the precursor were excessively decomposed as the shift to the high frequency discharge was performed. Furthermore, when this area is considered to have a large area, problems such as a problem of a film thickness / film quality distribution appear.

From these results, the frequency is 30 MHz
When the frequency is in the range of not less than 120 MHz and the stress is slightly compressed, SiN _{x of} high quality and high productivity is obtained without impairing the N / Si ratio, optical band gap, spin density and the like.
A thin film can be created.

Next, an embodiment of a field effect transistor using a SiN _x thin film manufactured by such a film forming method will be described.

FIG. 44 is a sectional view of an inverted stagger type TFT.

A gate electrode 32 is formed on an insulating substrate 31, and an insulating layer 33 and a semiconductor layer 34 are further formed thereon.
Are laminated. Source / drain electrodes 36 are formed on the semiconductor layer 34 via an ohmic contact layer 35. And it is covered with a protective film 37. Next, a method of manufacturing this TFT will be described with reference to FIGS.
This is described using (d).

First, as shown in FIG. 45A, a Cr thin film (approximately 1000 °) is formed on a Corning 7059 glass substrate 41 by a sputtering device and patterned to form a gate electrode.

Then, silicon nitride, SiN _x (about 30
00Å) A thin film is formed, and then as a semiconductor layer 44,
Non-doped amorphous silicon, i-type a-Si (about 6000
Å) As a thin film, ohmic contact layer 45, phosphorus-doped microcrystalline silicon, n ⁺ -type μc-Si (about 1000
Å) Thin films are sequentially formed by the same apparatus.

[0152] Second, as in FIG. 45 (b), the sputtering apparatus to form an Al thin film (about 1 [mu] m), and patterned to form the source and drain electrodes 46. The channel width W and the channel length L were W / L = 100.

Third, as shown in FIG. 45C, unnecessary n ⁺ -type μc-S
The i-layer is etched to form the gap 48.

Fourth, as shown in FIG. 45D, after further unnecessary SiN _x / i-type a-Si / n ⁺ -type μc-Si layers are isolated, a protective film 47 is deposited. 44 thin film transistors are created.

Here, the point of the present invention, SiN _x
The method for producing a thin film will be described in detail.

As described in the first section, the formation of the a-Si thin film is performed by a parallel plate type plasma CVD apparatus as shown in FIG. This figure shows a film forming chamber for a SiN _x thin film, and a mechanism for continuously forming a SiN _x / i-type a-Si / n ⁺ -type μc-Si layer, and other film forming chambers are not shown. In the figure, 600 is a vacuum chamber,
601 is a substrate, 602 is an anode electrode, 603 is a cathode electrode, 604 is a heater for heating a substrate, 605 is a ground terminal, 606 is a matching box, 607 is a high-frequency power source, 607 is an exhaust port, 608 is an exhaust pump, 609 is an exhaust pump, and 610 is a raw material. Gas inlets, 620, 630, 640, 622, 63
2, 642 indicates a valve, and 621, 631, 641 indicate a mass flow controller.

After being preheated in a load chamber (not shown) in the front chamber, the substrate is carried in, and the chamber is set to 1 × 10 ^-6 To.
Vacuum until rr or less. Next, the raw material gas Si
H ₄ , NH ₃ , H ₂ are supplied to the mass flow controller 62
10,200,100scc according to 1,631,641
m, the pressure is maintained at 0.2 Torr, the substrate heater 604 is set, and the substrate temperature is maintained until the temperature reaches 350 ° C.
Hz and a power of 30 mW / cm ² , and a 3000 nm SiN _x film is formed. After film formation, the same chamber
Vacuum to ^10-6 Torr or less. Next, it moves to the i-type a-Si film formation chamber of the next chamber not shown.

[0158] Thus, a thin film transistor can be manufactured. As an embodiment of the present invention, a high-frequency discharge of 80 MHz is taken as an example. Si deposited at each frequency f
Field mobility of a TFT using a N _X film μ (cm ² / Vs
FIG. 47 summarizes ec) with respect to the stress of the thin film. The electric field mobility μ becomes maximum at the frequency f = 80 MHz as compared with the case where the conventional 13.56 MHz is used, and an improvement of about twice is recognized. Conventional 13.56 MH
The electric field mobilities of the SiN _x thin film prepared by the RF plasma CVD method of z and NH ₃ and N ₂ are represented by black ○ △ plots, respectively.

That is, the frequency is 30 MHz or more and 120
The electric field mobility is improved at MHz or less, preferably at 50 MHz or more and 100 MHz or less.

In addition, the conventional 13.56 MHz and 80 MH
The stability of this TFT made in z was compared. FIG. 48 shows a change in threshold voltage when the ON state is maintained for up to 100 hours. It can be seen that the reliability has also been improved.

Next, a method of manufacturing the microcrystalline silicon film of the present invention
The method will be described.

FIG. 49 shows a manufacturing apparatus used in this embodiment. The basic structure is a conventional parallel plate type plasma C
It is the same as the VD device.

In the figure, reference numeral 700 denotes a vacuum chamber,
701 is an anode electrode, 702 is a substrate, and 703 is a cathode electrode. The anode electrode 701 is grounded at 706. 704 is a matching device, and 705 is a high frequency power supply. 707 is a gate valve, 708 is a turbo molecular pump, and 709 is a rotary pump. Also, 710,
718 is a silane gas line valve, 711 and 719 are hydrogen gas line valves, 712 and 720 are phosphine gas line valves, 713 and 721 are diborane gas line valves, and 714 to 717 are mass flow meters.

If attention is paid to the method of applying high frequency and handling, not only the parallel plate type as in this embodiment but also the carousel electrode type used in the manufacture of the photosensitive drum can be used in this embodiment. Is applicable.

First, the principle of the manufacturing method according to this embodiment will be described. FIG. 50 shows the emission intensity [SiH ^* ] of the SiH ^* radical (414 nm) and the emission intensity [H ^* ] of the hydrogen radical.
(656 nm) of the applied high frequency f. FIG. 51 shows the dependency of the deposition rate R on the applied high frequency f. FIGS. 52, 53
Shows the emission intensity of SiH ^* radicals [SiH ^*], the high frequency power applied Pw dependency of the emission intensity of hydrogen radicals [H ^*] to. The conditions at this time are SiH _{4 3} sccm, hydrogen 15
0 sccm, pressure 0.5 Torr.

As shown in FIG. 50, when the applied high frequency f is increased, the SiH ^* radicals and hydrogen radicals in the plasma start to increase correspondingly from about f = 30 MHz.
However, it has a maximum around f = 80 MHz,
It can be seen that it has been decreasing since then, and when it exceeds 120 MHz, it suddenly starts to decrease. Since the decomposition rate of the silane gas and the hydrogen gas depends on the electron density n _e in the plasma, SiH ^* radicals or H ^* radicals generated by the decomposition also depends on the electron density n _e. Therefore the electron density n _e in the plasma indicates an applied high frequency f-dependent, the light emission intensity of the radical accordingly, is believed to show the dependence as FIG. 50.

As shown in FIG. 51, the film formation rate R also increases as the applied high frequency f increases, and has a maximum around f = 80 MHz. However, in the region exceeding 100 MHz, the film thickness distribution on the substrate became large, and polysilane was easily formed, which became dust and pinholes were formed and the cost was reduced. In addition, uniform film properties were not obtained. Therefore, preferably, the effects of the present invention can be sufficiently exhibited in the frequency band of 30 MHz to 100 MHz. Generally, the film formation rate in silane gas is proportional to [SiH ^* ], and the tendency in FIG. 51 seems to depend on the tendency of [SiH ^* ] in FIG.

As shown in FIGS. 52 and 53, when the applied high frequency power is increased, both [SiH ^* ] and [H ^* ] are increased.
[H ^* ] is more dependent than [SiH ^* ].

In general, there are some conditions for forming microcrystalline silicon. First, the relationship of [H ^* ] / R> a (a is a constant) needs to be established between [H ^* ] in the plasma and the film formation rate R. This indicates that it is difficult to crystallize unless the hydrogen covering the film formation surface exceeds a certain amount.
In the plasma using a silane gas addition, since the film formation rate R is proportional to [SiH ^*], this condition is [H ^*]
/ [SiH ^* ]> a '. Under the actual conditions of the present invention, this value was a '= 1. In a normal system, the dilution ratio of hydrogen gas is increased to achieve this ratio.

However, by doing so, the partial pressure of the silane gas was reduced, and the film forming speed was extremely reduced. Thus, as in the present invention, by increasing the applied high frequency, the gas decomposition efficiency can be increased, and a decrease in the film forming rate can be prevented. Further, a higher film forming speed can be realized, and the film forming time can be shortened. This is the first effect of the present invention.

In FIGS. 52 and 53, [H ^* ] / [SiH]
^* ] = 1, the point P moves to the upper left as the applied high frequency f increases. The applied power Pw and the applied high frequency f at this point are approximately Pw = k / f
(Pw: W / cm ² , f: MHz).
Not only this point but also a point satisfying [H ^* ] / [SiH ^* ] = a 'shows the same change. In other words, in order to achieve a [H ^* ] / [SiH ^* ] ratio of a certain ratio or more at a certain applied high frequency f, there is a change in the applied high-frequency power.

This was determined under various conditions this time.
With the k = 1 curve as shown in FIG. 54 as the lower limit, preferably, the region indicated by oblique lines with k = 10 slightly deviating from the boundary region is a region in which the present invention can be realized. found. This is the second effect of the present invention. That is, by increasing the applied high frequency, a desired film can be obtained in a wider applied high-frequency power range without breaking the conditions for forming microcrystalline silicon. This is particularly effective when the apparatus is made large and a film is formed over a large area. That is, the size of the high-frequency power supply can be reduced for the large size of the device, and the cost of the device can be reduced.
Also, in terms of the effect on the film properties, if it can be made in a region where the applied power is small, the overall energy of the ions in the plasma will decrease, so reducing the damage caused by ions incident on the film surface And a film having good film properties can be formed.

From the viewpoint of reducing ion damage, attention is paid to the movement of ions in the plasma. In general, ions in a high-frequency plasma vibrate in the plasma according to an electric field oscillating by a high frequency in the plasma.
This situation can be expressed as follows. Here, A is the oscillation amplitude of the ions.

A ≒ V / w V: Maximum speed in one cycle of high frequency w: Angular frequency of high frequency: f = 2πw The film forming apparatus under consideration is a parallel plate type apparatus, and the distance between the electrodes is d. . Then, if the condition of d> A is satisfied, ions in the plasma will move back and forth in the plasma without reaching the substrate. Such a state is generally referred to as a state captured or trapped in plasma. As is apparent from this relational expression, by increasing the applied high frequency, a trapped state of ions can be created regardless of the size of the device. By doing so, the amount of ions incident on the substrate could be reduced. Further, as described later, ions are considered to have an adverse effect on the formation of microcrystals, which is effective not only for simple ion damage but also for efficiently producing high-quality microcrystals. The present invention intends to actively utilize such a state.

FIG. 22 described above illustrates this state. A mass spectrometer was installed at the substrate position, and the distribution of the incident energy and incident amount of the ions entering the mass spectrometer was determined. This data was obtained for argon gas to facilitate analysis. The reaction gas of the present invention shows essentially the same tendency. Conventional applied high frequency f
Under the condition of 13.56 MHz and f = 80 MHz according to the present invention, the incident energy and the incident amount of ions incident on the substrate are different. Obviously, under the condition of f = 100 MHz, the average incident energy is lower and the incident amount is reduced.

As shown in FIG. 2, when the frequency is large for a certain distance d between the electrodes, the distribution becomes large. This poses a serious problem for increasing the area. Therefore, the present inventors have tried to improve various film forming parameters, found that the distance between the electrodes has affected the film thickness distribution, and by further increasing the distance between the electrodes,
It has been found that the distribution becomes smaller. When the film thickness distribution T (%) in the substrate was within 10% under various conditions of the present invention, the relationship was determined. When d = 2 cm, the distribution was remarkably large. Is larger than 3 cm, if d satisfies f / d <30,
It has been found that generally good distribution can be obtained.

FIG. 3 shows the relationship between the distance between the electrodes and the density of defect states in the film under various conditions. It can be seen that when the distance between the electrodes exceeds 4 cm, the density of defects gradually decreases.
It can be seen that when the distance between the electrodes is smaller than 4 cm, the value rapidly increases. It is understood that the distance between the electrodes is preferably 4 cm or more. Therefore, in this embodiment, the distance between the electrodes is set to 4
Investigation was performed as cm.

Based on the above experimental facts and considerations, microcrystalline silicon containing no impurities was produced by the manufacturing method of the present invention.

The glass substrate 702 was mounted on the anode electrode in the chamber 700 and evacuated by the exhaust pump 709 to 10 ^-6 Torr. The substrate temperature was set to 250 ° C., SiH ₄ gas was flowed at 3 sccm, and H ₂ gas was
The flow rate was 50 sccm, and the internal pressure of the chamber was set to 0.5 Torr, and was maintained for 30 minutes. After that, high-frequency power was applied and the matching device was adjusted to start discharge, and discharge was performed for a necessary time to form a film.

The applied high frequency was varied from f = 13.56 MHz to f = 150 MHz to prepare a sample. The high frequency power at this time is from 7 mW / cm ² to 0.1
W / cm ² .

When the crystallinity was evaluated by X-ray diffraction, crystallization occurred in all the samples. An aluminum comb electrode was deposited on this film, and the dark conductivity and the activation energy were measured at room temperature (25 ° C.). An optical band gap E _gopt was also made using these samples.

The solid line shown by (a) in FIG. 57 shows the applied high frequency dependence of the dark conductivity of the film formed under this condition. FIG.
FIG. 8A shows the dependence of the activation energy on the applied high frequency. The broken line in the figure indicates that the film has much dust and the reproducibility of the characteristics is not sufficient. If the frequency exceeds 100 MHz, especially 120 MHz, the silane gas is liable to be excessively decomposed and polysilane is easily formed, which is considered to be a cause of dust.

FIGS. 57 and 58 show that as the applied high frequency is increased, the dark conductivity increases and the activation energy decreases. This is a phenomenon that accompanies crystallization of the film. It has been pointed out that the amount of ions incident on the substrate surface should be reduced as a condition for crystallization of the deposited film. As a result, ions in the plasma are trapped,
As described with reference to FIG. 22, it is considered that the crystallization actually proceeded because the number and energy of ions incident on the substrate decreased.

As a further effect of the present invention, there is an improvement in the initial film. Generally, when depositing microcrystalline silicon, 5
It has been found that the initial film of about 00 ° is a region where the growth of microcrystals is insufficient and there are many defects. This is presumably because a negative bias is applied to the insulating substrate in the initial stage of film formation, and accordingly, ions are incident on the substrate, which causes the above-described inconvenience. Microcrystalline silicon is often used as a blocking layer or an ohmic layer of a semiconductor device, and its thickness is at most 100.
In many cases, the thickness is about 0 °, so that about half of the thickness does not have good film quality.

It is known that such an initial film fluctuates due to film forming conditions and process instability, and eventually causes deterioration and instability of device characteristics. In particular, such troubles at the production site are serious.

Therefore, if the manufacturing method of the present invention is used, the amount of ions trapped in the plasma and incident on the substrate can be reduced in the first place. Therefore, it was confirmed that the microcrystalline silicon initial film obtained by the method of the present invention was changed to a good film .

Next, another method of forming an n ⁺ -type microcrystalline silicon film containing impurities by the method of manufacturing a microcrystalline silicon film of the present invention is described .
An example will be described. First, the state of the plasma at this time is shown.
FIG. 55 shows the frequency dependence of the emission intensity of the phosphine radical. FIG. 56 shows the applied power dependency of the phosphine radical. The high frequency power at this time is 3 mW / cm ² to 1
Samples were prepared with the variation between 00 mW / cm ² . The applied high frequency is 13.56 MHz to 150M
Hz.

The glass substrate 702 is mounted on the anode electrode in the chamber 700, and the pumps 708 and 70
According to 9, the gas was exhausted to 10 ^-6 Torr. Next, after setting the substrate temperature to 250 ° C., the valves 710 and 718 are opened to flow SiH ₄ gas at 3 sccm, and the valves 712 and 7
PH ₃ diluted 100ppm with H ₂ gas by opening the 20
Gas flow 150sccm, chamber pressure 0.5T
The pressure was maintained at orr and held for 30 minutes until the substrate temperature was stabilized. After that, high-frequency power was applied and the matching device was adjusted to start discharge, and discharge was performed for a necessary time to form a film. A 1 μm film was formed. Thereafter, the gas was evacuated and a high vacuum was applied to 10 ^-6 Torr.

When the crystallinity was evaluated by X-ray diffraction, crystallization occurred in all the samples. An aluminum comb electrode was deposited on this film, and the dark conductivity and the activation energy were measured at room temperature (25 ° C.).

FIG. 57 (b) shows the applied high frequency dependence of the dark conductivity of the film formed under this condition. (B) in FIG.
Fig. 3 shows the dependence of the activation energy on the applied high frequency. Figure 59
Fig. 6 shows the applied high frequency dependence of the doping efficiency. FIG.
It can be seen from FIG. 58 that the dark conductivity increases and the activation energy decreases as the applied high frequency is increased. As can be seen from the movement of the non-doped film (a) in the figure, the crystallization of the film is promoted by increasing the doping efficiency when the applied high frequency is increased. As a result, the incorporation of phosphorus into the film becomes active. It seems to be done. Moreover, as can be seen from FIG. 59, the doping efficiency also increases as the applied high frequency increases, which is also considered to be due to the improvement in crystallinity.

Next, of the films prepared here, a film having an applied high frequency of 80 MHz was evaluated as an ohmic layer of a photoconductive sensor device using intrinsic amorphous silicon as a photoconductive film. FIG. 60 shows the device configuration.

The glass substrate 702 was mounted on the anode electrode in the chamber 700 shown in FIG. 49, and evacuated to 10 ^-6 Torr by the exhaust pumps 708 and 709. Next, the substrate temperature was set to 250 ° C., SiH ₄ gas was flowed at 3 sccm, H ₂ gas was flowed at 30 sccm, the chamber internal pressure was set to 0.5 Torr, and the temperature was maintained for 30 minutes. waited. Thereafter, a normal high frequency of 13.56 MHz was applied at a power of 10 mW / cm ² , and the matching device was adjusted to start discharge, and the film was formed by discharging for a required time. Discharge for 3.5 hours and 5000
Intrinsic amorphous silicon of Å was deposited. Thereafter, the gas was evacuated and a high vacuum was applied to 10 ^-6 Torr.

Then, n ⁺ -type microcrystalline silicon was deposited on the intrinsic amorphous silicon by the manufacturing method of the present invention. The substrate was held on the anode electrode in the chamber 700, and while the substrate temperature was set at 250 ° C., the SiH ₄
A gas was flowed at 3 sccm, a phosphine gas diluted to 100 ppm with H ₂ gas was flowed at 150 sccm, the chamber internal pressure was set to 0.5 Torr, and the temperature was maintained for 30 minutes, and the substrate temperature was stabilized. Thereafter, a high frequency of 80 MHz was applied, and a matching device was adjusted to start a discharge, and the discharge was carried out for a necessary time to form a film of 1500 ° n ⁺ type amorphous silicon. After that, the gas is exhausted and 10 ^-6 Torr
It was evacuated to high vacuum.

Next, the substrate is taken out of the film forming apparatus,
Aluminum was formed to a thickness of 1 μm by a vacuum deposition method.

Thereafter, this aluminum was patterned to form electrodes.

Finally, using this electrode as a mask, the n ⁺ type amorphous silicon was removed by etching.

FIG. 61B shows the dependence of the dark current on the bias of the device thus manufactured. FIG. 62B shows the bias dependence of the photocurrent under a light source of wavelength 560 (nm) and 200 (lx). (A) in the figure is data of a conventional device. Conventionally, the dark current at the time of low bias has exhibited non-ohmic characteristics. The photocurrent showed slightly similar characteristics. This is thought to be caused by poor bonding between the intrinsic amorphous silicon layer and the n ⁺ microcrystalline silicon layer. However, in the method of the present invention, n
^{+ When the} microcrystalline silicon layer was formed, the above non-ohmic characteristics were improved. By improving the n ⁺ microcrystalline silicon, a good junction was formed, damage to the amorphous silicon layer by ions was reduced, and photoelectric characteristics were also improved.

Next , still another embodiment in which a p ⁺ -type microcrystalline silicon film is formed by the method for manufacturing a microcrystalline silicon film of the present invention will be described.

First, the state of the plasma at this time will be described. FIG. 55 shows the frequency dependence of the emission intensity of boron radicals. Normally, emission of boron radicals, for which emission is invisible, is observed, and it can be seen that the emission intensity increases as the applied high frequency is increased. This is probably because the electron density in the plasma increased as in the case of the silane gas, and the decomposition efficiency increased. FIG. 56 shows the dependence of the emission intensity of boron radicals on the applied power. It can be seen that the emission intensity increases as the applied power increases. The applied high frequency in this embodiment is from 13.56 MHz to 150 MHz.
z. Samples were prepared under the conditions indicating these plasma states.

The glass substrate 702 shown in FIG. 49 was attached to the anode electrode in the chamber, and an exhaust pump 708
At 709, the gas was exhausted to 10 ^-6 Torr or less. Substrate temperature 2
After setting the temperature to 00 ° C., the valves 710 and 718 were opened to flow 3 sccm of silane gas, and the valves 713 and 721 were opened to flow 150 sccm of diborane diluted to 1% with H ₂ gas and held for 30 minutes. After that, I turned on high frequency power,
By adjusting the matching device, plasma discharge was started to form a film. The thickness of all samples was about 1 μm.

When the crystallinity was evaluated by X-ray diffraction, crystallization occurred in all the samples. An aluminum comb electrode was deposited on this film, and the dark conductivity and the activation energy were measured at room temperature (25 ° C.).

FIG. 57 (c) shows the dependence of the dark conductivity of the film applied under these conditions on the applied high frequency. FIG. 58C shows the dependence of the activation energy on the applied high frequency. FIG. 59 shows the applied high frequency dependence of the doping efficiency. FIGS. 57 and 58
As the applied high frequency increases, the dark conductivity increases,
It can be seen that the activation energy has decreased. As can be seen from the movement of the non-doped film in (a), if the doping efficiency is also increased with the applied high frequency, the crystallization of the film is promoted, and along with this, boron is actively incorporated into the film. It seems to be. Moreover, FIG.
As can be seen from (b), the doping efficiency also increases as the applied high frequency increases, and this is also considered to be due to the improvement in crystallinity.

Next, of the films prepared here, a PIN type photodiode was prepared using a film with an applied high frequency of 80 MHz, and device evaluation was performed. FIG. 63 shows the device configuration.

First, the substrate 26 on which the lower electrode 262 is formed
On top of this, n ⁺ -type microcrystalline silicon 263 was deposited. The substrate was held on the anode electrode in the chamber 700 of FIG. 49, and while the substrate temperature was set at 250 ° C., SiH ₄ gas was flowed at 3 sccm, and phosphine gas diluted to 100 ppm with H ₂ gas was flowed at 150 sccm, and the chamber pressure was changed. Was set to 0.5 Torr and held for 30 minutes to wait for the substrate temperature to stabilize. After that, normal 13.56
A high frequency of MHz was applied at a power of 30 mW / cm ² , discharge was started by adjusting the matching device, and the discharge was carried out for a necessary time to form a 1500 ° n ⁺ amorphous silicon film. Thereafter, the gas was evacuated and a high vacuum was applied to 10 ^-6 Torr.

Next, the substrate was held in the chamber, and the SiH ₄ gas was supplied at 3 sc with the substrate temperature set at 250 ° C.
cm, and H ₂ gas at 30 sccm. The internal pressure of the chamber was set to 0.5 Torr, the temperature was maintained for 30 minutes, and the substrate temperature was stabilized. After that, normal 13.5
A high frequency of 6 MHz is applied with a power of 10 mW / cm ² ,
Discharge was started by adjusting the matching device, and the film was formed by discharging for a necessary time. Discharging was performed for 3.5 hours to form 5000 nm intrinsic amorphous silicon 264. Thereafter, the gas was evacuated and a high vacuum was applied to 10 ^-6 Torr.

Next, a p ^- microcrystalline silicon layer 265 is formed on the intrinsic amorphous silicon 264 by the manufacturing method of the present invention.
Was deposited. After setting the substrate temperature to 200 ° C. while the substrate was kept attached to the anode electrode in the chamber, valves 710 and 718 were opened to open silane gas at 3 sccm, and valves 713 and 721 were opened to diborane diluted to 1% with H ₂ gas at 150 sccm. And kept for 30 minutes. Thereafter, high-frequency power was applied at an applied high frequency of 80 MHz, and the matching device was adjusted to start plasma discharge, and a film was formed at 500 °.

Next, the substrate is taken out of the film forming apparatus,
A transparent conductive film 266 was formed by a vacuum evaporation method.

FIG. 64 (b) shows the diode characteristics of this device. (A) in the figure is data when a p ⁺ microcrystalline silicon layer is formed by a conventional manufacturing method. The current at the time of reverse bias was considerably reduced. The rise of the forward current was also improved. This is because the junction between the p ^- microcrystalline silicon layer and the underlying intrinsic amorphous silicon layer was sufficiently formed, and the blocking characteristics were improved.
It is considered that the damage due to ions was reduced.

In these examples, only phosphine and diborane are described. However, similar effects can be obtained by using arsine or the like as a doping gas.

[0210] Each of the embodiments described above corresponds to the present invention.
Method for producing amorphous silicon film, production of amorphous silicon nitride
The manufacturing method and the method for manufacturing a microcrystalline silicon film are examples in which each of the manufacturing methods is performed .
It is also possible to arbitrarily combine the manufacturing methods . For example, the amorphous insulating film of the present invention
Using the manufacturing method of quality silicon nitride, the onset the i-type semiconductor layer
A bright amorphous silicon film manufacturing method can be used. Here, it is needless to say that all the layers (i-type semiconductor layer, n ⁺ semiconductor layer, insulating layer, etc.) are preferably formed by the manufacturing method of the present invention .

The method for manufacturing an amorphous silicon film will now be described.
Method for producing amorphous silicon nitride, production of microcrystalline silicon film
A case where a non-single-crystal semiconductor device is manufactured by combining methods will be described.

As described above, in a field-effect transistor as shown in FIG. 18, a PIN-type semiconductor device, or the like, it is desirable to continuously laminate each functional film.
What is problematic in performing interface control, which is an important factor for the characteristics, is that not all the films have the same film forming rate and the required thicknesses are different. As a result, a rate-determining step occurs during continuous film formation, which is the tact time.

In the above-described device as shown in FIG. 18, the formation of the i-type a-Si layer has conventionally been the rate-determining step. In the present invention, by appropriately selecting the discharge frequency, the rate-limiting step can be eliminated, the throughput can be improved, and the cost can be reduced. Further, the throughput can be increased by increasing the discharge frequency of each layer in consideration of the quality.

Of course, in addition to increasing the throughput, the amorphous silicon nitride film according to the present invention is used as a gate insulating layer, and a non-single-crystal film such as an amorphous silicon film or a microcrystalline silicon film according to the present invention is used. When used as a semiconductor layer, as described above, a TFT with high reliability and excellent characteristics
Can be realized.

That is, in the continuous film formation, each discharge frequency can be determined in consideration of the influence of each of the above-mentioned films on the device characteristics and the cost reduction effect represented by the throughput.

[0216]

As described above, the amorphous silicon of the present invention is
According to the method of manufacturing the capacitor film , in the plasma CVD method, by defining the frequency of the high-frequency power supply, the input power depending on the frequency, the pressure, and the distance between the electrodes,
An a-Si film can be manufactured inexpensively, with high yield, and with high quality even in a large area. In particular, in thin film transistors, thin film transistor type optical sensors, solar cells, etc.
Various characteristics such as electric field mobility and photoelectric characteristics can be improved.
You.

Also, the production of the amorphous silicon nitride film of the present invention
According to the manufacturing method , a sufficient film forming rate can be obtained while suppressing a decrease in the film forming rate. As a result, manufacturing throughput can be increased. In addition, the decomposition efficiency of the deposition gas can be increased, the amount of gas used can be reduced, and the gas utilization efficiency can be greatly increased. As a result, manufacturing costs can be reduced. Further, since a film is formed in a state where ions that deteriorate the characteristics of the film are confined in plasma, generation of defects is suppressed, and a film having excellent characteristics can be provided.
In addition, since plasma damage at the interface can be reduced, a high-quality film can be stably provided. In addition, outgassing from the chamber can be suppressed, impurities are less taken into the film, defects based on the gas can be reduced, and a high-quality film can be provided. In addition, since film formation can be performed with a smaller electric power than a conventional apparatus, it is easy to reduce the size of a power supply apparatus, and it is possible to reduce the apparatus cost especially for a large-scale production apparatus.

Production of amorphous silicon nitride film of the present invention
According to the method , in the plasma CVD method, by specifying the frequency of the high-frequency power supply, the distance between the electrodes, and the input power , the SiN _x thin film can be manufactured inexpensively, with high yield, and with high quality even in a large area. In particular, in a thin film transistor, a thin film transistor type optical sensor, and the like, various characteristics such as electric field mobility, photoelectric characteristics, and the like, and improvement in stability thereof can be achieved.

Further, according to the method for manufacturing a microcrystalline silicon film of the present invention , a sufficient film forming rate can be obtained while suppressing a decrease in the film forming rate. As a result, manufacturing throughput can be increased. In addition, increase the decomposition efficiency of film forming gas,
The amount of gas used can be reduced, and the gas use efficiency can be greatly increased. As a result, manufacturing costs can be reduced. Further, since a film is formed in a state where ions that deteriorate the characteristics of the film are confined in plasma, generation of defects is suppressed, and a film having excellent characteristics can be provided. In addition, since plasma damage at the interface can be reduced, a high-quality film can be stably provided. In addition, the initial film can be improved, and by removing the unstable factors of the interface characteristics,
High quality film can be provided stably. Also, since film formation can be performed with a small electric power compared to a conventional film formation apparatus,
The size of the power supply device can be easily reduced, and the cost of the device can be reduced particularly for a large-sized device for production.

Further , according to the non-single-crystal semiconductor device of the present invention,
Accordingly, it is possible to provide a non-single-crystal semiconductor device capable of coping with an increase in area, improving film characteristics, enabling high-speed film formation, and further improving interface characteristics that affect device characteristics. . Note that the present invention can be used for a semiconductor device having an insulated gate transistor structure such as a TFT. In this case, if a gate insulating layer and / or an ohmic contact layer is formed by a plasma CVD method using a high-frequency discharge of a frequency of 30 MHz or more. In addition, a higher quality non-single-crystal semiconductor device can be provided. Furthermore, by appropriately selecting the discharge frequency in consideration of the quality of each layer, the rate-limiting step of each layer can be eliminated, the throughput can be improved, and the cost can be reduced. In addition, by increasing the discharge frequency of each layer in consideration of quality,
Throughput can be increased .

[Brief description of the drawings]

FIG. 1 is a characteristic diagram showing a relationship between an emission intensity ratio and a hydrogen bonding state.

FIG. 2 is a characteristic diagram showing a relationship between an applied high frequency f and a film thickness distribution.

FIG. 3 is a characteristic diagram showing a relationship between a distance between electrodes and a density of defect states in a film.

FIG. 4 is a characteristic diagram showing a relationship between pressure and emission intensity.

FIG. 5 is a characteristic diagram showing a relationship between power and emission intensity.

FIG. 6 is a characteristic diagram showing a relationship between power and emission intensity.

FIG. 7 is a characteristic diagram showing a relationship between frequency and power.

FIG. 8 is a characteristic diagram showing a relationship between a frequency and a hydrogen bonding state.

FIG. 9 is a characteristic diagram showing a relationship between frequency and spin density.

FIG. 10 is a characteristic diagram showing a relationship between a frequency and a film forming speed.

FIG. 11 is a characteristic diagram showing a relationship between frequency and photoelectric characteristics.

FIG. 12 is a characteristic diagram showing a relationship between a film forming speed and a photoelectric characteristic.

FIG. 13 is a characteristic diagram showing a relationship between residence time and emission intensity.

FIG. 14 is a characteristic diagram showing a relationship between a residence time and a hydrogen bonding state.

FIG. 15 is a characteristic diagram showing a relationship between residence time and photoelectric characteristics.

FIG. 16 is a characteristic diagram showing a relationship between a residence time and a film forming speed.

FIG. 17 is a characteristic diagram showing a relationship between residence time and film thickness distribution.

FIG. 18 is a cross-sectional view of a thin film transistor.

FIG. 19 is a process chart showing a method for manufacturing a thin film transistor.

FIG. 20 is a configuration diagram showing a plasma CVD apparatus.

FIG. 21 shows a TFT using the amorphous silicon thin film of the present invention.
FIG. 3 is a diagram showing initial characteristics of the present invention.

FIG. 22 is a characteristic diagram showing a substrate incident energy depending on a difference in frequency.

FIG. 23 shows a TFT using the amorphous silicon thin film of the present invention.
FIG. 3 is a diagram showing electric field mobility of the present invention.

FIG. 24 is an apparatus for realizing the manufacturing method according to the present invention.

FIG. 25: Emission intensity of SiH ^* radicals [SiH ^* ]
And the applied high frequency f of the emission intensity [N ^* ] of the nitrogen radical
FIG. 4 is a characteristic diagram showing dependence.

FIG. 26: Emission intensity of SiH ^* radicals [SiH ^* ]
FIG. 4 is a characteristic diagram showing the dependence of the emission intensity [N ^* ] of nitrogen radicals on the applied high-frequency power Pw.

FIG. 27: Emission intensity of SiF ^* radicals [SiF ^* ]
And the applied high frequency f of the emission intensity [N ^* ] of the nitrogen radical
FIG. 4 is a characteristic diagram showing dependence.

FIG. 28: Emission intensity of SiF ^* radicals [SiF ^* ]
FIG. 4 is a characteristic diagram showing the dependence of the emission intensity [N ^* ] of nitrogen radicals on the applied high-frequency power Pw.

FIG. 29 is a characteristic diagram showing dependence of a film forming rate R on an applied high frequency f.

FIG. 30 is a characteristic diagram of the thin film transistor of this example.

FIG. 31 is a characteristic diagram showing a V _th shift during an ON operation.

FIG. 32 is a characteristic diagram showing a V _th shift due to heat treatment.

FIG. 33 is a characteristic diagram of the thin film transistor showing the effect of the passivation film according to the present example.

FIG. 34 is a characteristic diagram showing frequency dependence of a V _th shift.

FIG. 35 is a cross-sectional view of a thin film transistor.

FIG. 36 is a cross-sectional view of a thin film transistor provided with a passivation film.

FIG. 37 is a configuration diagram showing a plasma CVD apparatus.

FIG. 38 is a characteristic diagram showing a relationship between a frequency and a film forming speed.

FIG. 39 is a characteristic diagram showing a relationship between frequency and hydrogen amount.

FIG. 40 is a characteristic diagram showing the relationship between the amount of hydrogen and stress.

FIG. 41 is a characteristic diagram showing the relationship between the amount of hydrogen and stress.

FIG. 42 is a characteristic diagram showing the relationship between the amount of hydrogen and stress.

FIG. 43 is a characteristic diagram showing a relationship between frequency and spin density.

FIG. 44 is a cross-sectional view of a thin film transistor.

FIG. 45 is a process view showing the method for manufacturing the thin film transistor.

FIG. 46 is a configuration diagram showing a plasma CVD apparatus.

FIG. 47 is a diagram showing the stress dependence of the electric field mobility of a TFT using the SiN _x thin film of this example.

FIG. 48 is a characteristic diagram showing a change in threshold voltage in the present embodiment.

FIG. 49 is an apparatus for realizing the manufacturing method according to the present invention.

FIG. 50: Emission intensity of SiH ^* radicals [SiH ^* ]
And the applied high frequency f of the emission intensity [H ^* ] of the hydrogen radical
FIG. 4 is a characteristic diagram showing dependence.

FIG. 51 is a characteristic diagram showing dependence of a film forming rate R on an applied high frequency f.

FIG. 52: Emission intensity of SiH ^* radicals [SiH ^* ]
FIG. 4 is a characteristic diagram showing the dependence of the emission intensity [H ^* ] of hydrogen radicals on applied high-frequency power Pw.

FIG. 53 shows emission intensity of SiH ^* radicals [SiH ^* ].
FIG. 4 is a characteristic diagram showing the dependence of the emission intensity [H ^* ] of hydrogen radicals on applied high-frequency power Pw.

FIG. 54 is a characteristic diagram showing a relationship between applied high frequency power Pw and applied high frequency f.

FIG. 55 is a characteristic diagram showing the dependence of a doping gas radical on the applied high frequency f.

FIG. 56: Applied high frequency power P of doping gas radical
FIG. 9 is a characteristic diagram showing w dependence.

FIG. 57 is a characteristic diagram showing dependence of dark conductivity on applied high frequency f.

FIG. 58 is a characteristic diagram showing dependence of activation energy on applied high frequency f.

FIG. 59 is a characteristic diagram showing the dependence of the doping level on the applied high frequency f.

FIG. 60 is a diagram showing a configuration of a photoconductive sensor of the present embodiment.

FIG. 61 is a characteristic diagram showing bias dependence of dark current of the photoconductive sensor.

FIG. 62 is a characteristic diagram showing bias dependence of a photocurrent of the photoconductive sensor.

FIG. 63 is a diagram showing a configuration of a PIN photodiode.

FIG. 64 is a characteristic diagram showing diode characteristics of a PIN photodiode.

FIG. 65 is a characteristic diagram showing a relationship between a film forming speed and photoelectric characteristics.

FIG. 66 is a characteristic diagram showing a relationship between a substrate temperature and a hydrogen amount.

FIG. 67 is a characteristic diagram showing a relationship between substrate temperature and stress.

FIG. 68 is a characteristic diagram showing a relationship between a gas ratio, a composition ratio, and a hydrogen amount.

[Explanation of symbols]

11, 21 Glass substrate 12, 22 Gate electrode 13, 23 Gate insulating layer 14, 24 i-type semiconductor layer 15, 25 n ⁺ type semiconductor layer 16, 26 Source / drain electrode 17, 27 Protective film 300 Vacuum chamber 302 Anode electrode 304 Substrate heating heater 306 Matching box 307 High frequency power supply 309 Exhaust pump 321, 341 Mass flow controller 400 Vacuum chamber 401 Anode electrode 402 Substrate 403 Cathode electrode 404 Matching device 405 High frequency power supply 406 Ground 407 Gate valve 408 Turbo molecular pump 409 Rotary pump 410, 420 Silane gas line valve 411,421 Hydrogen gas line valve 412,422 Phosphine gas line valve 413,423 Diborane gas line valve 414, 424 Silicon fluoride gas line valve 415, 416, 417, 418, 419 Mass flow meter 131 Substrate 132 Gate electrode 133 Amorphous silicon nitride layer 134 Intrinsic amorphous silicon layer 135 n ⁺ type microcrystalline silicon layer 136 Aluminum electrode 141 Substrate 142 Gate electrode 143 Amorphous silicon nitride layer 144 Intrinsic amorphous silicon layer 145 n ⁺ type microcrystalline silicon layer 146 Aluminum electrode 147 Amorphous silicon nitride film for passivation 31, 41 Glass substrate 32, 42 Gate electrode 33 , 43 gate insulating layer 34, 44 i-type semiconductor layer 35, 45 n ⁺ -type semiconductor layer 36 and 46 source and drain electrodes 37 and 47 protective film 600 vacuum chamber 602 anode electrode 604 substrate heater 606 matching ball Box 607 High frequency power supply 609 Exhaust pump 621,641 Mass flow controller 700 Vacuum chamber 701 Anode electrode 702 Substrate 703 Cathode electrode 704 Matching device 705 High frequency power supply 706 Ground 707 Gate valve 708 Turbo molecular pump 709 Rotary pump 710,718 Silane gas line valve 7111, 719 hydrogen gas line valve 712,720 phosphine gas line valve 713,721 diborane gas line valve 714,715,716,717 mass flow meter 231 substrate 232 intrinsic amorphous silicon layer 233 n ⁺ type microcrystalline silicon layer 234 aluminum electrode 261 lower electrode substrate 262 263 n ⁺ -type microcrystalline silicon layer 264 intrinsic amorphous silicon layer 265 p ⁺ -type microcrystalline sintered Silicon layer 266 a transparent conductive film

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Hidemasa Mizutani 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (56) References JP-A-63-197329 (JP, A) JP-A-63 -223178 (JP, A) JP-A-2-38570 (JP, A) JP-A-4-65120 (JP, A) JP-A-3-278481 (JP, A) (58) Fields investigated (Int. . ^7, DB name) H01L 21/205

Claims (12)

(57) [Claims] In a method of manufacturing an amorphous silicon film by a plasma CVD method using a high-frequency discharge, at least a film forming pressure P (T
orr) is set to 0.25 Torr or more and 2.5 Torr or less, and the frequency f (MHz) of the high-frequency power supply is set to 30 MHz.
It is set to not less than 120 MHz and input power Pw (W / c
m ² ) is equal to or less than a value specified by 10 / f (MHz),
A method for manufacturing an amorphous silicon film, wherein a distance d (cm) between electrodes is set to a value larger than a value specified by f / 30. 2. The method according to claim 2 , wherein at least
A gas containing Si or Si and F, a hydrogen gas, and a nitrogen gas.
Mixed gas containing at least Si and F, or at least
A method of depositing an amorphous silicon nitride film using a mixed gas containing a mixed gas containing nitrogen gas and nitrogen gas, wherein a VHF high frequency having a frequency f of 30 MHz or more is set to a distance between electrodes d (cm). A method for producing an amorphous silicon nitride film in which a voltage is applied so as to satisfy f / d <30 and a plasma is generated . 3. A manufacturing method for depositing an amorphous silicon nitride film by a plasma CVD method using a mixed gas containing at least a silicon compound and ammonia as a source gas, wherein the frequency f is 30 MHz to 120 MHz.
When the HF high frequency and the distance between the electrodes are d (cm), f /
It meets d <30, and the input power is 30 mW / cm ² or more
A method for producing an amorphous silicon nitride film, characterized in that plasma is generated by applying a voltage so as to be above . Manufacturing method of claim 4, wherein the amorphous silicon nitride film, a manufacturing method of an amorphous silicon nitride film according to claim 3, characterized in that used in the laminated structure of the amorphous silicon film. 5. The method according to claim 1, wherein the stress of said amorphous silicon nitride film is 1 ×.
5. The method for producing an amorphous silicon nitride film according to claim 4 , wherein the amorphous silicon nitride film exhibits a compressive stress of 10 ⁹ dyn / cm ² or more and 4 × 10 ⁹ dyn / cm ² or less. 6. A manufacturing method for depositing a microcrystalline silicon film by a plasma CVD method using a gas containing Si, wherein a VHF high frequency having a frequency f of 30 MHz or more is
Plasma is generated by applying a power of 1 / f (W / cm ² ) (f: MHz) or more so as to satisfy f / d <30 when the distance between the electrodes is d (cm). Of producing a microcrystalline silicon film. 7. A method for producing a microcrystalline silicon film according to claim 6 for gas containing Si, and characterized by using a gas containing boron, a gas containing phosphorus, the gas containing arsenic as an impurity gas Of producing a microcrystalline silicon film. 8. The method for producing microcrystalline silicon according to claim 6 , wherein the emission intensity of hydrogen radical [H
^* ] And the emission intensity [SiH ^* ] of silane radicals are [H ^* ] / [SiH ^* ] ≧ 1. 9. At least a gate electrode on a substrate,
A gate insulating layer, a non-single-crystal semiconductor layer, a pair of source
2. A non-single-crystal semiconductor device in which a drain electrode is sequentially stacked and an ohmic contact layer is provided between the non-single-crystal semiconductor layer and the source / drain electrodes , wherein the non-single-crystal semiconductor layer is provided. Depending on the manufacturing method
Non-single-crystal semiconductor device as amorphous silicon film formed
Place. 10. The method according to claim 10 , wherein at least a gate electrode is formed on the substrate.
A gate insulating layer, a non-single-crystal semiconductor layer, and a pair of saws.
The non-single-crystal semiconductor
Ohmic capacitor between the layer and the source / drain electrodes.
A non-single-crystal semiconductor device provided with a tact layer,
The heat insulating layer is formed by the manufacturing method according to claim 3.
A non-single-crystal semiconductor device which is an amorphous silicon nitride film. 11. At least a gate electrode on a substrate
A gate insulating layer, a non-single-crystal semiconductor layer, and a pair of saws.
The non-single-crystal semiconductor
Ohmic capacitor between the layer and the source / drain electrodes.
A non-single-crystal semiconductor device provided with a tact layer,
The single crystal semiconductor layer is formed by the manufacturing method according to claim 1.
Amorphous silicon film, wherein the gate insulating layer is
Item 3. An amorphous silicon nitride formed by the manufacturing method according to Item 3.
Non-single-crystal semiconductor device that is a thin film. 12. At least, the gate insulating layer, the non-single-crystal semiconductor layer, the ohmic contact layer without being exposed to the atmosphere, according to claim 11 claim 9, characterized in that it is formed sequentially The non-single-crystal semiconductor device according to any one of the above.