JPH05275346A - Manufacture of amorphous silicon film, and manufacture of amorphous silicon nitride film, and manufacture of crystallite silicon film, and nonsingle crystal semiconductor device - Google Patents

Abstract

PURPOSE:To improve the interface property which affects device property by making this corresponding to the enlargement of area of a nonsingle crystal film such as an a-Si film, etc., and besides, improving the property of a film thereby enabling a high-speed film. CONSTITUTION:In the manufacture of an amorphous silicon film by the plasma CVD method using high-frequency discharge, the film growth pressure P (Torr) is set to not less than 0.25Torr and not more than 2.5Torr, and the frequency f (MHZ) of a high frequency power source is set to not less than 30MHz and not more than 120MHz, and making power Pw (W/cm<2>) is made not more than the value prescribed by 10/f (MHz), the distance d between electrodes (cm) is made more than the value prescribed by f/30.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The first and second inventions of the present application relate to a method for producing an amorphous film, and are particularly suitable for use in thin film devices such as thin film transistors, thin film transistor type photosensors and solar cells. The present invention relates to a method for manufacturing an amorphous silicon film.

The third and fourth inventions of the present application relate to a method for producing an amorphous silicon nitride film, and are particularly suitable for use in amorphous silicon thin film devices such as thin film transistors and thin film transistor type optical sensors. The present invention relates to a method for manufacturing a crystalline silicon nitride film.

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

The sixth invention of the present application relates to a non-single crystal semiconductor device, and more particularly to a non-single crystal semiconductor device having a non-single crystal semiconductor layer formed by a plasma CVD method.

A seventh invention of the present application relates to a non-single crystal semiconductor device, and more particularly to a non-single crystal semiconductor device having a protective layer formed by a plasma CVD method.

Here, the non-single crystal semiconductor refers to an amorphous semiconductor other than a single crystal semiconductor, a microcrystalline (including polycrystal) semiconductor, and the like.

[0007]

2. Description of the Related Art First, a conventional technique according to the first and second inventions of the present application will be described.

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

In addition, the photo CVD method or the ECR-CV method
D method etc. are known, but among such manufacturing methods,
Plasma CVD by RF discharge of 13.56 MHz is widely used as a film forming method that satisfies well-balanced quality, large area, and price of a-Si thin film.
Is the law. This plasma CVD method often uses monosilane gas (SiH ₄ ), dilutes it with hydrogen gas (H ₂ ) if necessary, and decomposes the raw material gas by RF discharge at 13.56 MHz to obtain a reactive activity. A seed is created 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 photosensors, and solar cells.

Next, a conventional technique according to the third invention of the present application will be described.

In recent years, semiconductor devices using non-single crystal silicon have been actively developed. In particular, development of large-area, low-cost solar cells and photoconductor drums for copiers, development of thin-film transistors for liquid crystal displays, lightweight and compact manufacturing,
Development of a solid-state image pickup device for a facsimile is 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 is used.}
Alternatively, 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. Although there is another thermal CVD method as a method for producing silicon nitride, it 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. Since the growth temperature can be set to about 300 ° C. in the RF plasma CVD method, it can be sufficiently used. When ammonia is used rather than nitrogen, the decomposition and the reaction are more likely to occur, so in most cases a mixed gas of silane SiH ₄ and ammonia NH ₃ is used, and if necessary diluted with hydrogen gas.
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, is difficult to handle, and may be particularly unfavorable for production equipment. In that respect, nitrogen gas is easy to handle and advantageous. Further, nitrogen gas is easier to purify than ammonia gas, and the incorporation of impurities during film formation can be reduced. Impurities in the film adversely affect the electrical characteristics of the amorphous silicon nitride insulating film, which is not preferable. It is also known that when a film is formed using ammonia gas, the hydrogen concentration in the film is higher than when nitrogen gas is used. When the amount of hydrogen in the film increases, the density decreases, and the compactness and heat resistance deteriorate. Also, this hydrogen diffuses in the film, causing various unstable phenomena.
The less hydrogen in the film, the better. There are various advantages in using a mixed gas of silane gas and nitrogen gas. From this point of view, it is considered advantageous to use a mixed gas of hydrogen-free fluorinated silane and nitrogen gas.

Next, a conventional technique according to the fourth invention of the present application will be described.

Since the composition of the amorphous silicon nitride thin film changes depending on the manufacturing method and its conditions, it is referred to as a SiN _x film. The physical properties of this SiN _x film largely change depending on the composition, the amount of hydrogen contained, and the like. Typical SiN _x film deposition methods include atmospheric pressure CVD method using SiH ₄ —NH ₃ mixed gas, plasma CVD method, photo 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 especially an RF plasma utilizing a discharge frequency of 13.56 MHz of a SiH ₄ —NH ₃ mixed gas. It is a CVD method and is most widely used because of its advantages of easy reaction and good controllability.

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, when it is said that the threshold voltage fluctuates, the on / off ratio is lowered, and the response is deteriorated, the yield is lowered, which causes a serious problem. Similarly, in a TFT type optical sensor, a change in threshold voltage causes a change in photocurrent and dark current, which are its 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 the injection of electrons and holes from a-Si into SiN _x , or Si
It is because it is trapped in the trap level of N _x , and S
It is considered that a high quality film having a large optical band gap of the iN _x film and a small electron spin density is effective for suppressing the change to a minimum.

When the SiN _x film contains a large amount of hydrogen, the density is lowered and the withstand voltage is lowered. Further, since this hydrogen diffuses in the film and causes various unstable phenomena, it is considered preferable that the amount of hydrogen in the film is small.

Further, it is also considered that the TFT characteristics can be expected to be improved by making the stress of the SiN _x film slightly on the compression side.

That is, until now, the basic physical properties of the SiN _x thin film have been studied from various angles such as film forming conditions and test conditions.
It is estimated that the iN _x thin film preferably has a large optical band gap, a low spin density, a low hydrogen concentration, and a stress on the compression side.

Next, a conventional technique according to the fifth invention of the present application will be described.

In recent years, a semiconductor device using microcrystalline silicon or amorphous silicon has been actively developed. In particular, development of a solar cell and a photoconductor drum of a copying machine that can be produced in a large area at low cost, development of a thin film transistor for a liquid crystal display, and development of a solid-state image pickup device for a facsimile which can be made light and small are active. A conventional non-single-crystal silicon film deposition method used in these semiconductor devices is RF plasma C using silane SiH ₄ or disilane Si ₂ H ₆ as a film forming gas.
A Si target is formed by the VD method or in the presence of hydrogen gas.
A reactive sputtering method of sputtering in r plasma has been used. The microcrystalline silicon and amorphous silicon obtained by these methods almost contain 10% or more of hydrogen. The most popular method for depositing such microcrystalline silicon or amorphous silicon is plasma CVD, which is silane SiH ₄ or disilane Si ₂ H.
_{Using 6} and diluting with hydrogen gas as needed 13.5
Plasma is generated at a high frequency in the RF band of 6 MHz, the 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, a film forming gas is mixed with a doping gas such as phosphine PH ₃ , diborane B ₂ H ₆ , or boron fluoride BF _{3 to} form a film, thereby forming a microcrystalline silicon film in which the n-type or p-type of the film is freely controlled. 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 are produced using these films.

The prior arts according to the first to fifth inventions of the present application have been described above.
As a method of improving the plasma CVD method, R
It has been reported that the high frequency discharge in the F band was studied by increasing the frequency.

That is, at the Joint Lectures on Applied Physics (28p-MF-14, 28p-S-4) in the fall of 1990 and the spring of 1991, Oda et al. Of Tokyo Institute of Technology discharged at a high frequency of 144 MHz, and Crystalline silicon is created and evaluated.

However, in this report, 13.56M
It is a study with only Hz and 144 MHz, and the frequency has not been fully optimized in the VHF band when considering the increase in area and production.

Further, as an effect of frequency, it is disclosed in Japanese Patent Laid-Open No. 3-64466 that by increasing the frequency, it is possible to create a spatially uniform discharge over the film formation surface and to realize a uniform film formation rate. Has been done. However, the present invention only refers to uniform film formation, and does not describe what kind of influence or technical effect the high frequency in the VHF band has on the film quality and the like.

Further, in JP-A-2-225674, there is a description of a frequency of 1 kHz to 100 MHz.
Nothing has been described about technical effects in the VHF band, and this is merely a technical extension in the RF band.

In US Pat. No. 4,933,203, VH
The F-band high frequency is used to study the film to optimize the relationship between the frequency and the distance between the electrodes, but this relationship is insufficient for the problem to be solved by us, which will be described later.

[0027]

First, the problems relating to the first and second inventions of the present application will be described.

With the recent technological development, a-S has been used in all fields such as solar cells, liquid crystal televisions, and optical sensors.
High quality i thin film is required, but
The a-Si thin film using the RF discharge of 3.56 MHz still has the following problems when applied to an a-Si thin film device. (1) Compared 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 and dark conductivity.
The ratio is small, and in a solar cell, photo-deterioration (σ _P ) characteristics are degraded by light irradiation, and photodegradation is large. (2) With respect to the production yield, in a large area device, the yield is reduced 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 in a thin film device has a low film forming rate, and thus the production capacity does not increase and it is difficult to reduce the price.

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

For that purpose, in the plasma CVD method of 13.56 MHz, attempts have generally been made to improve the manufacturing conditions such as the flow rate of the raw material gas, the pressure, and the input power. There is an increase in hydrogen in the film, which is presumed to deteriorate the characteristics, and generation of foreign matter (polysilane) that causes a decrease in yield. For example, as shown in FIG. 65, the photoconductivity σ _P (S / cm), which is a basic characteristic of a thin film, decreases with an increase in the film formation rate, and when a device such as a thin film transistor type optical sensor is formed, The thing which can improve the characteristic is not yet manufactured now. After all, in this a-Si thin film manufacturing method, the film formation rate at which device characteristics can be maintained is approximately 0.2 to 2Å / sec.

That is, the characteristic of the RF discharge of 13.56 MHz is that the film formation on a large area can be easily performed, but the film formation speed is low, and the substrate and further the thin film itself. There is a drawback such as large ion damage to the. On the other hand, with the microwave discharge of 2.54 GHz, the film formation rate is high and there is no ion damage to the substrate, but it is difficult to increase the area. Further, the photo-CVD method is a developing method because it has problems not only in the quality of the formed a-Si thin film but also in increasing the area. Similarly, even in the ECR-CVD method, damage to the substrate can be freely controlled and the quality of the a-Si thin film can be improved, but there is a drawback that it is difficult to form a large area film.

As described above, in manufacturing an a-Si thin film device, the quality of the a-Si thin film is improved, the device characteristics are improved, and the productivity represented by the film forming rate is satisfied at the same time. There is a drawback that you can't.

Next, the problem relating to the third invention of the present application will be described.

Using the above-mentioned conventional silane gas or a mixed gas of fluorinated silane and nitrogen gas, if necessary diluting with hydrogen gas, plasma is generated at a high frequency of 13.56 MHz, and the film forming gas is decomposed by the plasma. Then, the method of depositing the amorphous silicon nitride film on the substrate has the following problems.

Since nitrogen gas is less likely to be decomposed than ammonia gas, it is necessary to increase the high frequency power supplied. However, when the applied power is increased, the amount of gas released from the chamber wall increases, the amount of impurities taken into the film increases, and plasma damage increases, which deteriorates the film characteristics. Further, since silicon fluoride is more chemically stable than silane, it has a low decomposition efficiency in plasma, and when it is used, the gas utilization efficiency is poor. Further, the growth rate of the film becomes slow.

Next, the problem relating to the fourth invention of the present application will be described.

In order to satisfy the above-mentioned physical properties of the thin film, the conventional 1
Various methods have been tried in the RF plasma CVD method using 3.56 MHz, but the following problems occur.

First, conventionally, the hydrogen concentration in the film C _H (%)
_Has the highest dependence on the substrate temperature T _S , and also greatly depends on the source gas species. This relationship is shown in FIG. As is clear from the figure, in order to simply reduce the hydrogen concentration, the source gas should be changed from NH ₃ to N ₂ and the temperature should be further raised. However, in actuality, considering the use of a large glass plate, the structure of the device, and the productivity, the upper limit is about 400 ° C. 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, and the reliability of the device characteristics is significantly reduced. 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, the stress Stress (dyn / cm
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 higher and 400 ° C. or lower, the stress of the SiN _x film using NH ₃ shows approximately tensile stress. Moreover, when N ₂ is used, a large compressive stress is exhibited. The black plot in the figure is the point where a high-quality SiN _x thin film can be realized, and the shaded areas are the hydrogen concentration range and stress range that can be controlled. That is, it is considered that there is some compressive stress, that is, device quality.
SiN _x showing a compressive stress of × 10 ⁹ dyn / cm ² or less
It turns out that thin films cannot be made.

Therefore, when NH ₃ is used, the hydrogen concentration in the film can be controlled by changing the NH ₃ / SiH ₄ ratio. The relationship is shown in FIG. As can be seen from the figure, when the hydrogen concentration is lowered, N / Si is lowered, and the film quality such as the optical band gap is lowered.
_{The 3} / SiH ₄ ratio cannot be lowered. Similarly, when N ₂ is used, if the hydrogen concentration is increased and the stress is controlled, N 2
The film quality such as the / Si ratio is deteriorated.

That is, the hydrogen concentration is lowered to make the stress slightly on the compression side, and the N / Si ratio at that time is close to the stoichiometric ratio, the optical band gap is increased, and the spin density is decreased. There is a problem that you cannot get it.

Next, the problem relating to the fifth aspect of the present invention will be described.

The above-described conventional manufacturing method has the following problems, particularly when microcrystalline silicon containing impurities is formed. Using silane gas, diluting with hydrogen gas as needed, plasma is generated at a high frequency of 13.56 MHz RF band, and the film forming gas is decomposed by the plasma.
The method of depositing microcrystalline silicon on a substrate generally has a poor gas utilization efficiency. Therefore, by introducing impurity gas,
When forming microcrystalline silicon containing impurities, there is a problem that doping efficiency is poor. Further, according to the conventional method, the conditions for causing microcrystallization in the film are strict, and it is difficult to form a desired microcrystalline film. Therefore, it was difficult to improve the doping efficiency. 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
150 sccm of phosphine gas diluted to 0 ppm,
When a 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 phosphorus atoms in the film do not work as a dopant.

A method for improving the RF plasma CVD method by using the above-mentioned VHF band (Autumn 90 Fall, Spring 1991 Lecture on Applied Physics (28p-MF-14, 28p-S-3),
In Tokyo Tech, Oda et al., Japanese Patent Laid-Open No. 3-64466, etc.), the conditions were not optimized, and it was insufficient to solve the problems according to the first to fifth inventions of the present application.

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

The third object of the present invention is to improve the decomposition efficiency of nitrogen gas and silicon fluoride gas, the utilization efficiency of the film forming gas, and prevent the degassing from the chamber due to the effect of ions in plasma. However, it is another object of the present invention to provide a manufacturing method capable of obtaining a good semiconductor device by reducing plasma damage, reducing manufacturing cost, and easily forming a high-quality amorphous silicon nitride film.

A fourth object of the present invention is to provide a conventional RF
The frequency of 13.56 MHz in the plasma CVD method was reviewed, and the decomposition efficiency of the raw material gas was increased by using high frequency discharge. As a result, the hydrogen concentration of the SiN _x thin film using conventional NH ₃ was reduced and at the same time the stress was controlled. Therefore, it is another object of the present invention to provide a manufacturing method for obtaining a higher quality SiN _x thin film corresponding to a large area device at a lower cost.

The fifth object of the present invention is to improve the utilization efficiency of the film forming gas, reduce the manufacturing cost, and easily form a more suitable microcrystalline silicon film, thereby obtaining a good semiconductor device. It is to provide a manufacturing method.

Another object of the sixth and seventh inventions of the present application is to obtain a high quality, low cost non-single crystal semiconductor device.

[0050]

According to a first aspect of the present invention, in a plasma CVD method, at least a silicon compound is used as a source gas and a film forming pressure P (Torr) is 0.25 Tor.
r to 2.5 Torr or less, and the frequency f (MHz) of the high frequency power source is set to 30 MHz to 120 MHz, preferably 50 MHz to 100 MHz,
Moreover, the input power P _W (W / cm ² ) is 10 / f (MH
z) below the value specified by the relationship, and the inter-electrode distance d (c
By setting m) to a value larger than the value defined by f / 30, it is possible to cope with an increase in the area of the a-Si film, and it is possible to improve the film characteristics and achieve high-speed film formation. It is also possible to improve the interface characteristics that influence the temperature.

In the second invention of the present application, in the plasma CVD method, at least a silicon compound gas is used as a source gas, and a film forming pressure P (Torr) is set to 0.25 Torr or more and 2.5 Torr or less, and a frequency of a high frequency power source is set. f
(MHz) is set to 30 MHz or more and 120 MHz or less, preferably 50 MHz or more and 100 MHz or less, the inter-electrode distance d (cm) is set to a value larger than the value defined by f / 30, and the discharge space V (cm ³ ) is set. Source gas Q (scc
m) dwell time τ (sec) is τ = 78.94
When the residence time τ when defined as 7 × 10 ⁻³ × V × P / Q is set to 0.05 sec or more and 2.5 sec or less, preferably 0.1 sec or more and 2.5 sec or less, a-Si It is possible to cope with a large area of the film, improve the film characteristics to enable high-speed film formation, and further improve the interface characteristics that influence the device characteristics.

A third aspect of the present invention is an amorphous silicon nitride film formed by plasma CVD using a mixed gas of Si or a gas containing Si and F and nitrogen gas, and further hydrogen gas. In the manufacturing method of depositing, a VHF high frequency having a frequency f of 30 MHz or more is applied to the interelectrode distance d.
(Cm) is applied so as to satisfy f / d <30, and plasma is generated, which is a method for producing amorphous silicon, and has a VHF high frequency of 30 MHz or higher, preferably 50 MHz to 100 MHz. High frequency,
By applying so as to satisfy f / d <30 when the distance between the electrodes is d (cm), the electron density in the plasma is increased and the decomposition efficiency of nitrogen gas or silicon fluoride gas that is difficult to decompose is increased. It is an object of the present invention to easily provide an improved amorphous silicon nitride film having a good quality distribution. Furthermore, by utilizing the trapping of ions in the plasma, unnecessary degassing from the chamber is suppressed, impurities such as oxygen are prevented from mixing into the film, and a high-quality film with little ion damage to the film is provided. It is a thing.

Further, in the fourth invention of the present application, in order to transfer the stress to the compression side slightly without deteriorating the film quality, in the plasma CVD method, a mixed gas containing at least a silicon compound and ammonia is used as a source gas. The frequency of the high frequency power source is 30 MHz or more and 120 MHz or less, preferably 50 MHz or more and 100 MHz or less, and the inter-electrode distance d (cm) is set to a value larger than the value defined by f / 30, thereby improving the film characteristics, High-speed film formation is possible while supporting a large area, and further, device characteristics can be improved.

The fifth invention of the present application is the plasma CVD.
In a manufacturing method of depositing a microcrystalline silicon film by using a gas containing Si by a method, the applied high frequency f is 30
1 / f (W / cm ² ) for VHF high frequency above MHz
(F: MHz) or more power, the distance between electrodes d (cm)
Then, a plasma is applied so that the emission intensity [H ^* ] of hydrogen radicals and the emission intensity [SiH ^* ] of silane radicals satisfy [H ^* ] ≧ [SiH ^* ]. And a VHF high frequency of 30 MHz or more,
Preferably, a high frequency of 50 MHz to 100 MHz is used to increase the electron density in the plasma, increase the gas decomposition efficiency, and use the trapping of ions in the plasma to achieve high doping efficiency and less ion damage. A high-quality microcrystalline silicon film is provided.

The sixth aspect of the present invention is that the non-single crystal semiconductor layer is formed by the plasma CVD method using high frequency discharge having a frequency of 30 MHz or more and 120 MHz or less,
(EN) A non-single-crystal semiconductor device capable of accommodating a large area, improving film characteristics, enabling high-speed film formation, and improving interface characteristics that influence device characteristics. The sixth invention of the present application can be applied to a semiconductor device having an insulated gate transistor structure such as a TFT. In this case, the gate insulating layer and / or the ohmic contact layer is formed by a plasma CVD method using a high frequency discharge having a frequency of 30 MHz or more. It is desirable to be created. Moreover, if each layer is continuously formed without exposing to the atmosphere,
The discharge frequency can be appropriately selected in consideration of the quality of each layer.

Further, a seventh invention of the present application is that the protective layer is formed by plasma CVD using high frequency discharge having a frequency of 30 MHz or more.
By using the method, it is possible to form a high-quality protective layer with less ion damage.

[0057]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The detailed description and embodiments of the present invention will be described below with reference to the drawings.

The structure of the non-single crystal semiconductor device according to the present application will be described in the following description of the method for producing each amorphous silicon film according to the first to fifth aspects of the present application.

First, the first and second inventions of the present application will be described.

Here, first, a film growth process by the plasma CVD method will be briefly described, and then the present invention will be described in detail.

In general, the growth process of an a-Si thin film can be classified into the following processes. Here, SiH ₄ is used as an example of the source gas. (1) Radical generation process of SiH ₄ in glow discharge plasma In this process, the energy distribution of electrons in the plasma has a peak at several eV, Maxwell-Boltzma.
It has a shape close to the nn distribution, and such electrons are SiH ₄
By repeating inelastic collisions with molecules, various radicals, ions, and atoms are generated. SiH is the main precursor for film growth
₂ , The possibility of SiH ₃ radicals is high. (2) Transport process of generated radicals to the substrate In this process, neutral radicals generated in plasma are transported to the substrate surface by diffusion while causing various secondary chemical reactions mainly with SiH ₄ molecules. It Considering the radical generation rate in plasma and the reaction lifetime in the transport process, it is presumed that most of the particles that reach the substrate surface are SiH ₃ radicals. However, Si, SiH, S
When the arrival density of radicals such as iH ₂ increases, the quality of the film deteriorates due to the difference in the reaction mode on the surface. (3) Film Growth Process on Substrate Surface In this process, radicals reaching the film growth surface are adsorbed on the surface and diffused on the surface to form stable sites and chemical bonds to form an amorphous network. If the surface is covered with hydrogen, SiH ₃ radicals are sufficiently surface-diffused, and chemically bond with stable sites to obtain a high-quality film.

In each of the above processes, the external parameters of the plasma are controlled so that SiH ₃ radicals mainly reach the film growth surface and hydrogen is coated on the substrate surface so that the radicals diffuse. -Si thin film can be prepared.

The present inventors recognize that it is important to control radicals in order to form a high-quality a-Si thin film, and thus, specifically, an important monitoring method in the film forming process. As a result, the investigation was performed 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 has been clarified that the magnitude of the strength is closely related to the quality of the a-Si thin film. In particular, the emission intensity ratio [H ^* ] / [SiH ^* ]
(SiH ^* , H ^* radical emission intensity is [Si
It is desirable to adopt film-forming conditions such that (H ^* ] and [H ^* ] are minimum values, but the relationship of emission intensity 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 hydrogen bonding mode in the thin film, that is, the film quality.

[0065] In general, the absorption peak appearing in 2000cm ^-1 ~2100cm ^-1 in infrared absorption analysis in a-Si thin film, Si-H stretching vibration bond (2000c
m ^-1 ) and stretching vibration of Si-H ₂ bond (2100 cm
^-1 ), 2000 cm ^{-1 to} 2100 cm
The median value Rm (cm ^-1 ) of the absorption peak appearing at ^-1 can be considered to represent the ratio of SiH bond and SiH ₂ bond contained in the thin film. Here, for example, the median value Rm is 2
If it has changed from 000 cm ^-1 to 2100 cm ^-1 , S
This is an increase in iH ₂ bonds, and chain bonds or cyclic bonds of Si generate defects contained in the film, resulting in deterioration of film quality.

That is, as shown in FIG. 1, the emission intensity ratio [H
^* ] / [SiH ^* ] increases, the median value Rm is also 21
In other words, the shift to the 00 cm ⁻¹ side means that if the emission intensity ratio [H ^* ] / [SiH ^* ] increases, then a−S
It can be said that the i film quality is deteriorated. In the view of the present inventors, [S
If iH ^* ] ≧ [H ^* ], a substantially 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 becomes a big problem for increasing the area. Therefore, the inventors of the present invention have
As a result of attempting improvement, it was found that the distance between the electrodes had an influence on the film thickness distribution, and further, 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
When the relation is calculated under the condition that the ratio is within%, d = 2
In cm, the distribution is remarkably large, which is outside the usable range, and when d is larger than 3 cm, f (MHz) /
It was found that if d (cm) <30 is satisfied, a generally good distribution can be obtained.

FIG. 3 shows the relationship between the interelectrode distance and the defect level density in the film under various conditions. It can be seen that the defect density gradually decreases when the distance between the electrodes exceeds 4 cm.
It can be seen that when the distance between the electrodes becomes smaller than 4 cm, it rapidly increases. It can be seen that the distance between the electrodes is preferably 4 cm or more. Therefore, in this embodiment, the distance between the electrodes is 4c.
m was examined.

Considering the film forming mechanism described above, a high quality a
In order to obtain the -Si film quality, it is necessary to sufficiently cover the substrate surface with hydrogen. Therefore, a mixed gas obtained by diluting SiH ₄ with H ₂ was introduced into the plasma reaction chamber at SiH ₄ : H ₂ = 1: 9, the frequency f was set to 80 MHz, and the input power P _{W was} 0.07 _W / cm ^2. It was made to discharge. The relationship between the pressure P (Torr) and the emission intensity of SiH ^* and H ^* radicals at this time is shown in FIG. In order to obtain a satisfactory a-Si film quality, as described above, the relationship of the emission intensity is [Si
The pressure P (Torr) that satisfies H ^* ] ≧ [H ^* ] is P ≧ 0.
Although it is in the region of 25 Torr, when P> 2.5 Torr, foreign matter (polysilane) which reduces the yield occurs. On the other hand, in the region where the pressure P is P <0.25 Torr,
This leads to deterioration of film quality such as an increase in the amount of hydrogen in the thin film and an increase in SiH ₂ bond. That is, the pressure P is 0.25 Torr or more.2.
A high quality a-Si film quality can be obtained at 5 Torr or less. Similarly, the frequency f = 13.56, 30, 50, 10
When the relationship with the emission intensity 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 to orr and the frequency f of the high frequency power supply f = 13.5
Input power P at 6, 80 and 150 MHz respectively
Figure 5 shows the relationship between _W and the emission intensity of SiH ^* and H ^* radicals.
As shown in FIG. In the figure, the white circles and triangles indicate [Si
H ^* ] ≧ [H ^* ], and the black and white plots satisfy [SiH ^* ] <[H ^* ]. FIG. 7 shows the relationship between each frequency f and the input power P _{W for} which the relationship of the emission intensity is [SiH ^* ] ≧ [H ^* ]. From the figure, a-S
Although the physical meaning of the condition for obtaining the i thin film is unknown, the input power P _W (W / c
m ² ) needs to be equal to or less than the value defined by the relationship of 10 / f (MHz), and this range is indicated by diagonal 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 are the conditions for a low-quality a-Si thin film. In addition, as the optimum condition of the high quality a-Si thin film, the emission intensity ratio [H ^* ] / [Si
The film formation was performed by selecting the input power P _{W at} which H ^* ] shows the minimum value.

FIG. 8 shows the relationship between the power supply frequency f and the median value Rm in the infrared absorption analysis at each deposition pressure of the a-Si thin film. The input power at this time is [H ^* ] / [Si
H ^* ] ratio is the optimum input power that minimizes the ratio. For example 80
At MHz and 0.5 Torr, it is 0.04 W / cm ² . In the region where the frequency f is less than 30 MHz, the ion damage to the substrate is large, the SiH ₂ bond content in the film is large, and the film has many defects.
SiH in the film even in the region over 120MHz
The content of ₂ bonds increases and the film quality deteriorates. It is presumed that the reason for this is that Si, SiH, and SiH ₂ radicals in which SiH ₄ molecules are overdecomposed increase with the transition to high-frequency discharge, and conversely, SiH ₃ radicals decrease. In addition, considering the large area,
Problems such as film quality distribution problems will appear.

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. It is considered that this is because damage to the substrate incident ions increases in the range of p <0.25, and 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 with each film forming pressure as a parameter.

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

From these results, the frequency is 30 MHz.
High quality in the range of 120 MHz or more and 120 MHz or less, and
A highly productive a-Si thin film can be formed, and preferably 5
If it is 0 MHz or more and 100 MHz or less, improvement in photoelectric characteristics can be expected.

Next, pressure P = 0.5 Torr and frequency f
= 80 MHz, input power P _W = 0.04 _W / cm ² , and the retention time τ (sec) was confirmed. here,
The residence time τ (sec) means that the source gas Q (sccm) is introduced into the discharge space V (cm ³ ) and the pressure P (Tor
When r) is controlled to be kept constant, this is the time during which the raw material gas stays in the discharge space and is represented by the following equation.

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

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

FIG. 16 shows the relationship between the residence time τ and the film forming rate DR, and FIG. 17 shows the relationship with the in-substrate film thickness distribution T _E (%). Here, when the maximum film thickness and the minimum film thickness distribution in the substrate are T _MAX and T _MIN , respectively, T _E =
It is represented by (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 formation rate begins to decrease, and from 5 sec or more, the film formation rate similarly decreases. This is because when the residence time τ is small, the reactive radicals generated by the discharge are exhausted out of the system before reaching the substrate surface, and conversely, when the residence time τ is large, the raw material is simply It is considered that the film formation rate decreases due to the shortage. The same can be considered in FIG. When the residence time τ is less than 0.05 sec, a distribution according to the raw material gas flow occurs, and the residence time τ is 5 s.
If it is larger than ec, distribution occurs from the introduction part of the source gas. As a guide, the distribution is preferably 10% or less.

That is, the residence time τ is τ <0.05 sec
In the region of, the film formation rate decreases and the film thickness distribution increases. Therefore, considering the large area and productivity, the residence time τ is 0.0
It will be 5 seconds or more.

From these results, the residence time τ (se
It is necessary that c) is 0.05 sec or more and 2.5 sec or less, and preferably 0.1 sec or more and 2.5 sec or less, the improvement of photoelectric characteristics can be expected as shown in FIG.

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

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

The gate electrode 12 is formed on the insulating substrate 11, and the insulating layer 13 and the semiconductor layer 14 are further formed on the gate electrode 12.
Are stacked. Source / drain electrodes 16 are formed on the semiconductor layer 14 via an ohmic contact layer 15. Then, it is covered with the protective film 17. Next, a method for manufacturing this TFT will be described with reference to FIGS.
An explanation will be given using (d).

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

After that, silicon nitride, SiN _x (about 30 nm) is formed as the gate insulating layer 23 by a plasma CVD apparatus.
00 Å) A thin film is formed, and then, as the semiconductor layer 24,
Non-doped amorphous silicon, i-type a-Si (about 6000
Å) Thin film, as ohmic contact layer 25, phosphorus-doped microcrystalline silicon, n ⁺ type μc-Si (approximately 1000
Å) Thin films are sequentially formed using the same equipment.

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

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

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

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

As described in the first section, the formation of the a-Si thin film is carried out by the 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 ⁺ μc-Si layer and other film forming chambers are not shown. 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 supply, and 308 is Exhaust port, 309 is exhaust pump, 310
Is a raw material gas inlet, 320, 340, 322 and 342 are valves, and 321 and 341 are mass flow controllers.

The substrate is loaded from the SiN _x film forming chamber (not shown) in the front chamber, and the chamber is evacuated to 1 × 10 ⁻⁶ Torr or less. Next, the source gases SiH ₄ and H ₂ are fed to the mass flow controllers 321 and 341 for 2, 1
8 sccm is supplied, the pressure is maintained at 0.5 Torr, the substrate heating heater 304 is set, and the substrate temperature is 200 ° C.
Until the frequency reaches 80 MHz, a high frequency power source 307 supplies a frequency of 80 MHz and a power of 0.04 W / cm ² ,
A type a-Si film is formed at 6000Å. After the film formation, the chamber is similarly evacuated to 1 × 10 ⁻⁶ Torr or less. Next, the substrate is moved to an n ⁺ type μ-Si film forming chamber in the next chamber (not shown).

A thin film transistor can be manufactured in this manner. As an example of the present invention, a high frequency discharge of 80 MHz is taken as an example. Of course, when the frequency f is changed, the input power P _W (W / cm ² ) is 10 / f (MH
z) is less than or equal to the value defined by the relationship, and it is desirable to change the input power so that 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 to 0.47 cm ² / Vsec of the conventional a-Si thin film of 13.56 MHz discharge. / Vsec and about 2
Doubled. The reason for this can be considered from the difference between the ion energy incident on the substrate 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
Compared to discharge at a small ion energy reaching incident on the substrate, also is characterized say less energy dispersion, therefore, the case of laminating an a-Si film, the SiN _X film is a gate insulating film It is considered that the interface characteristics were improved without giving ion damage.

It is also possible to determine the frequency by focusing on any of film characteristics, productivity, device characteristics and the like.

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

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

The substrate is loaded from the SiN _x film forming chamber (not shown) in the front chamber, and the chamber is evacuated to 1 × 10 ⁻⁶ Torr or less. Next, the source gases SiH ₄ and H ₂ are converted into SiH by the mass flow controllers 321 and 341.
_{It was} supplied at 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 heating heater 304 and maintaining it until the substrate temperature reaches 200 ° C., a frequency of 80 MHz and power of 0.04 W / cm ² are applied from the high frequency power source 307 to apply an i-type a-Si film of 6000 Å. Form a film. After the film formation, the chamber is similarly evacuated to 1 × 10 ⁻⁶ Torr or less. Next, the substrate is moved to an n ⁺ type μ-Si film forming chamber in the next chamber (not shown).

A thin film transistor can be manufactured in this manner. As an example of the present invention, a high frequency discharge of 80 MHz is taken as an example, but of course, when the frequency f is changed, it is preferable that the emission intensity ratio [SiH ^* ] ≧ [H ^* ] is satisfied within a range satisfying the relationship. , Emission intensity ratio [H ^* ] / [SiH
^* ] Change to conditions such as input power that shows the minimum value. Residence time τ (sec) and average electric field mobility in the substrate μ (cm ²
/ 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, good electric field mobility μ (cm
² / Vsec) can be obtained. Next, the third invention of the present application 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 the conventional parallel plate type plasma CVD apparatus.

In the figure, 400 is a vacuum chamber, 4
Reference numeral 01 is an anode electrode, 402 is a substrate, and 403 is a cathode electrode. The anode electrode 401 is grounded at 406. Reference numeral 404 is a matching unit, and 405 is a high frequency power source.
407 is a gate valve, 408 is a turbo molecular pump, 4
Reference numeral 09 is a rotary pump. Further, 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, 4
14,424 are silicon fluoride gas line valves, 41
5-419 are mass flow meters. This embodiment can be applied not only to the parallel plate type as in the present embodiment but also to the carousel electrode type used in the manufacture of the photoconductor drum, if attention is paid to how to apply a high frequency and handling.

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 SiH ^* radicals (414 nm) and the emission intensity [N ^* ] of nitrogen radicals. FIG. 29 shows the dependency of the deposition rate R on the applied high frequency f. FIG. 26 shows the emission intensity of SiH ^* radicals [SiH ^* ] and the emission intensity of nitrogen radicals [N
^* ] Shows the dependency of the applied high frequency power Pw. The conditions at this time are SiH ₄ 3sccm, hydrogen 30sccm, nitrogen 60
Sccm, pressure 0.2 Torr. Note that Pw = 10 mW / cm ² in FIG. 25 and f = 80 MHz in FIG.
And

From FIG. 25, when the applied high frequency f is increased, SiH ^* radicals and nitrogen radicals in the plasma are
It is increasing accordingly. However, f = 80M
It can be seen that it has a maximum value around Hz and tends to decrease thereafter. 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,
It seems that the dependence shown in FIG. 25 is shown.

From FIG. 29, the film formation rate R also increases as the applied high frequency f increases, and has a maximum value around f = 100 MHz. However, in the region over 100 MHz, the film thickness distribution on the substrate becomes large, and polysilane is easily formed, which becomes dust and pinholes are made cheaper. Further, it was not possible to obtain a film having uniformly good film characteristics. Therefore, preferably 30 MHz to 100 MHz
The effect of the present invention can be sufficiently exerted in the frequency band of. Generally, the film formation rate in silane gas is proportional to [SiH ^* ], and the tendency in FIG. 29 seems to depend on the [SiH ^* ] tendency in FIG.

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

By increasing the applied high frequency, the film formation rate can be increased. It is also possible to reduce the applied power accordingly. This is particularly effective when the apparatus is enlarged and film formation is performed in a large area. That is, the high-frequency power supply can be downsized despite the large size of the device, and the device cost can be reduced. In addition, even if it affects the characteristics of the film, if it can be created in a region where the applied power is small, the total energy of the ions in the plasma will be reduced, so the damage caused by the ions incident on the film surface should be reduced. It is possible to produce a film having good film characteristics. Also, pay attention to the movement of the ions in the plasma from the viewpoint of reducing the damage of the ions. Generally, the ions in the high frequency plasma oscillate in the plasma according to the oscillating electric field due to the high frequency in the plasma. This situation can be expressed in an equation as follows. Here, A is the amplitude of oscillation of the ions.

A≈V / w V: maximum speed in one cycle of high frequency w: angular frequency of high frequency: f = 2πw Let us assume that 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, the ions in the plasma will move back and forth in the plasma without reaching the substrate. Such a state is generally called a state of being trapped or trapped in plasma. As is clear from this relational expression, increasing the applied high frequency makes it possible to create a trapped state of ions regardless of the size of the device. By doing so, the amount of ions incident on the substrate could be reduced. Therefore, ion damage to the film surface and inside the film could be reduced.

This is illustrated in FIG. 22 already described. A mass spectrometer was installed at the substrate position, and the distribution of the incident energy and the incident amount of the ions that jumped in here were 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
= 13.56 MHz and f = 80 MHz according to the present invention, the incident energy and the incident amount of the ions incident on the substrate are different. Obviously, under the condition of f = 80 MHz, the average incident energy becomes lower and the incident amount decreases.

Further, the above effects apply 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, so that the vacuum device can be removed from the chamber wall without any special treatment. It was possible to reduce degassing. The present invention intends to positively utilize such a state.

As already described with reference to FIG. 2, the distribution becomes large when the frequency is large for a certain distance d between the electrodes. This becomes a big problem for increasing the area. Therefore, the inventors of the present invention tried to improve various film forming parameters, found that the inter-electrode distance had an influence on the film thickness distribution, and by further increasing the inter-electrode distance, the distribution It was found that Under various conditions of the present invention, the relationship was obtained under the condition that the film thickness distribution T (%) in the substrate was within 10%. When d = 2 cm, the distribution was remarkably large, and it was not within the usable range. Is larger than 3 cm, d that satisfies f / d <30
Then, it has been found that a generally good distribution can be obtained.

Further, as shown in the relationship diagram between the electrode distance and the defect level density in the film under various conditions in FIG. 3, the defect density gradually decreases when the electrode distance exceeds 4 cm. It can be seen that, when the distance between the electrodes becomes smaller than 4 cm, it rapidly increases. The distance between the electrodes is preferably 4
It can be seen that cm or more is desirable. Therefore, in this example, the distance between the electrodes was set to 4 cm.

Based on the above experimental facts and consideration, amorphous silicon nitride was prepared by the manufacturing 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 exhausted by the exhaust pump 409 to 10 ^-6 Torr. The substrate temperature is set to 350 ° C and SiH ₄ gas is set to 3
sccm flow, H ₂ gas 30 sccm, nitrogen gas 6
The flow rate was 0 sccm, the internal pressure of the chamber was 0.2 Torr, and the pressure 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 required time to form a film.

The applied high frequency is f = 13.56 MHz and f
= 80 MHz. The high frequency power at this time is f = 1
It was 2 mW / cm ² at 30mW / cm ^2, f = 80MHz at 3.56MHz. The film formation rate was set to 1Å / sec for comparison of film characteristics.

Aluminum comb electrodes were vapor-deposited on this film, and the resistivity was measured at room temperature (25 ° C.). An optical bandgap E _gopt was also created using these samples. 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.

[0116]

[Table 1] This is because by increasing the applied high frequency f, the ions in the plasma are trapped, and the flux of the ions incident on the substrate surface or the chamber wall is reduced. Impurities in the film are surely reduced because there is no blowout from the chamber wall. It is considered that the spin density in the film was realized by the reduction of impurities in the film and the reduction of ion damage during film formation. In this example, the higher resistivity is due to Si-Si, Si-
It is considered that the inconsistency of bonds such as N was improved by the reduction of 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 the device configuration.

A 1000 liter film of aluminum was formed on the glass substrate 131 by a vacuum vapor deposition method and patterned to form a gate electrode 132.

Next, this glass substrate 131 was mounted on the anode electrode in the chamber 400 shown in FIG. 24 and exhausted to 10 ^-6 Torr by exhaust pumps 408 and 409. Set the substrate temperature to 350 ° C and use SiH ₄ gas for 3 s.
ccm flow, H ₂ gas flow at 30 sccm, nitrogen gas flow at 60 sccm, chamber internal pressure was 0.2 Torr, holding for 30 minutes, and waiting for the substrate temperature to stabilize. After that, high-frequency power was applied and the matching device was adjusted to start discharge, and discharge was performed for a required time to form a film. At this time, the frequency was fluctuated around f = 80 MHz. The high frequency power was set so that the film forming rate was uniform at 10 Å / sec. After discharging, evacuate the gas to 10 ^-6
A high vacuum was drawn up to Torr.

Next, the substrate temperature is set to 250 ° C. and the Si
H ₄ gas was caused to flow at 3 sccm, H ₂ gas was caused to flow at 30 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. After that, a normal high frequency of 13.56 MHz is applied at 10 mW / cm ²
The discharge was started by turning on the electric power of No. 1 and adjusting the matching device, and the film was formed by discharging for a required time. Intrinsic amorphous silicon 13 of 5000 Å after discharging for 3.5 hours
4 was deposited. After that, the gas is exhausted and 10 ^-6 Torr
High vacuum was pulled up to.

Next, the substrate temperature is set to 250 ° C. and the Si
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 to wait for the substrate temperature to stabilize. After that, a normal high frequency of 13.56 MHz was applied with a power of 30 mW / cm ² , and the matching device was adjusted to start discharge, and the discharge was performed for a required time to form a film. Discharge for 30 minutes and 1500Å
Of n ⁺ type amorphous silicon 135 was deposited. After that, the gas was exhausted and a high vacuum was drawn up to 10 ⁻⁶ Torr.

Next, this substrate was taken out from the film forming apparatus,
Aluminum 136 was formed into a film with a thickness of 1 μm by a vacuum deposition method.

After that, 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.

Characteristics of a thin film transistor in which a silicon nitride film is formed at f = 80 MHz, which is a typical thin film transistor thus formed, is shown in FIG. It shows sufficiently good characteristics. The ON state is 100 in FIG.
The change in the threshold voltage V _th when the time is maintained is shown. In the figure, (a) is data of a conventional device.
Conventionally, the shift was performed to the positive side with time, but according to the present embodiment, this shift is considerably improved. Generally, this V _th shift is due to carriers entering during ON operation, in this case N-channel operation, so that electrons enter the insulating film and are trapped by the trap levels in the film to form fixed charges there.
Therefore, according to the manufacturing method of the present invention, it is considered that the impurities in the film are reduced, the ion damage during the film formation is also reduced, the defects in the film are reduced, and this characteristic is improved. The dependence of the V _th shift on the applied high frequency is shown in FIG. It can be seen that the above effect appears from around f = 30 MHz.

Next, an amorphous silicon nitride film under the same conditions was used as a passivation film of a thin film transistor and evaluated. However, the substrate temperature was set to 250 ° C. in order to avoid adverse effects on the thin film transistor. FIG. 36 shows the configuration of the device.

A 1000 liter film of aluminum was formed on the glass substrate 141 by a vacuum vapor deposition method and patterned to form a gate electrode 142.

Next, this glass substrate 141 was mounted on the anode electrode in the chamber 400 shown in FIG. 24, and exhausted to 10 ^-6 Torr by exhaust pumps 408 and 409. Substrate temperature is set to 250 ° C and SiH ₄ gas is applied for 3s.
ccm flow, H ₂ gas flow of 30 sccm, nitrogen gas flow of 60 sccm, the chamber internal pressure was set to 0.5 Torr, the temperature was kept for 30 minutes, and the substrate temperature was waited for stabilization. After that, high-frequency power was applied and a matching device was adjusted to start discharge, and discharge was performed for a required time to form the gate insulating film 143. At this time, the frequency is f = 13.5
6 MHz, high frequency power was 30 mW / cm ² . After the discharge was completed, the gas was exhausted and a high vacuum was drawn up to 10 ⁻⁶ Torr.

Next, the substrate temperature is set to 250 ° C. and the Si
H ₄ gas was caused to flow at 3 sccm, H ₂ gas was caused to flow at 30 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. After that, a normal high frequency of 13.56 MHz is applied at 10 mW / cm ²
The discharge was started by turning on the electric power of No. 1 and adjusting the matching device, and the film was formed by discharging for a required time. 5000 Å intrinsic amorphous silicon 14 after 3.5 hours of discharge
4 was deposited. After that, the gas is exhausted and 10 ^-6 Torr
High vacuum was pulled up to.

Next, the substrate temperature is set to 250 ° C. and the Si
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 to wait for the substrate temperature to stabilize. After that, a normal high frequency of 13.56 MHz was applied with a power of 30 mW / cm ² , and the matching device was adjusted to start discharge, and the discharge was performed for a required time to form a film. Discharge for 30 minutes and 1500Å
Of n ⁺ type amorphous silicon 145 was deposited. After that, the gas was exhausted and a high vacuum was drawn up to 10 ⁻⁶ Torr.

Next, this substrate was taken out from the film forming apparatus,
Aluminum 146 was deposited to a thickness of 1 μm by the vacuum deposition method. After that, this 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. The process up to this step is the conventional process of forming a thin film transistor.

Next, a passivation film 147 was deposited on the substrate which has been subjected to these steps by the manufacturing method according to the present invention. First, the substrate was mounted on the anode electrode in the chamber 400 again, and the exhaust pumps 408 and 409 evacuated it to 10 ⁻⁶ Torr. Substrate temperature is 200 ℃
Then, SiH ₄ gas was flowed at 3 sccm, H ₂ gas was flowed at 30 sccm, nitrogen gas was flowed at 60 sccm, the chamber internal pressure was 0.2 Torr, and the temperature was kept for 30 minutes to wait until the substrate temperature became stable. Then, turn on high frequency power and adjust the matching device to start discharge.
A film was formed by discharging for a required time. At this time, the frequency is f =
I touched some points around 80MHz. After the discharge was completed, the gas was exhausted and a high vacuum was drawn up to 10 ⁻⁶ Torr. As a comparative sample, the frequency is f
A sample having a passivation film of = 13.56 MHz and high frequency power of 30 mW / cm ² was also prepared. The typical f of the thin film transistors prepared in this way is 80M
FIG. 33 shows the characteristics when the passivation film is formed at Hz.
It shows in (c). In the figure, (b) shows the case of the conventional method. In the figure, (a) shows initial characteristics without a passivation film. Conventionally, the threshold voltage was positively shifted from the initial state by attaching a passivation film due to damage by ions in plasma, but with the passivation film of the present invention, the shift can be considerably reduced. .. The applied high frequency dependency of this V _th shift is shown in FIG. It can be seen that the above effect appears from around f = 30 MHz. From this experimental result, it is considered that by increasing the applied high frequency from around f = 30 MHz, the ions incident on the substrate are reduced and the ion damage during film formation is also reduced. [Second Embodiment] Next, a second embodiment according to the third invention of the present application will be described.

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

First, the state of plasma at this time will be shown. FIG. 27 shows the frequency dependence of the emission intensity of SiF ^* radicals. It can be seen that the emission intensity is also increased by increasing the applied high frequency. It is considered that this is 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 SiF ^* radicals. It can be seen that the emission intensity increases as the applied power increases. The applied high frequency in this example was set from 13.56 MHz to 150 MHz.

Samples were prepared under the conditions showing these plasma states. The glass substrate is attached to the anode electrode in the chamber of FIG. 24, and the exhaust pumps 408 and 409
It was exhausted to below 0 ^-6 Torr. After setting the substrate temperature to 350 ° C., the valves 414 and 424 are opened to make the silicon fluoride gas 3 sccm, and the valves 411 and 421 are opened to make H ₂
Gas is flowed at 40 sccm and nitrogen gas at 120 sccm,
Hold for 30 minutes. After that, high-frequency power was applied and the matching device was adjusted to start plasma discharge and form a film.
The film thickness of all samples was about 1 μm.

The applied frequency f of the film formation rate R is shown in FIG.
Indicates dependency. As seen from the above plasma emission, the gas was sufficiently decomposed by increasing the applied high frequency, and it was possible to realize a higher film formation rate than before.

The film formed here was used as a gate insulating film of a thin film transistor and evaluated. The single film characteristics at this time are shown in Table 1. Since the device manufacturing process is basically the same as the process in the first embodiment, it will be omitted. f = 80MHz
Figure 3 shows the device characteristics when a silicon nitride film is formed by
It is shown in 0 (b). FIG. 31C shows a change in the threshold voltage V _th when the ON operation is maintained for 100 hours.
FIG. 32C shows changes in the threshold voltage V _th when heat treatment is applied. In the figure, data of a conventional device is shown. The basic characteristics were as good as the conventional ones. Also, the V _th shift due to the ON operation was reduced. This is because the impurities in the film are reduced, the defects associated therewith and the defects due to plasma damage at the time of film formation are reduced, the trap levels of carriers are reduced overall, and the number of electrons trapped in them is reduced. I think that the. In the device of this example, since hydrogen in the film was suppressed, diffusion of hydrogen due to heat did not easily occur, and the V _th shift to the negative side due to heat treatment was small. Further, FIG. 34B shows the applied high frequency dependency of V _th shift due to this ON operation, and FIG. 34D shows the applied high frequency dependency of V _th shift due to heat. It can be seen that the above effect appears from around f = 30 MHz. From this experimental result, it is considered that by increasing the applied high frequency from around f = 30 MHz, the ions incident on the substrate are reduced and the ion damage during film formation is also reduced.

Next, the fourth invention of the present application will be described.

First, the inter-electrode distance, which is the premise of the embodiment of the present invention, will be described.

As already described with reference to FIG. 2, the distribution becomes large when the frequency is large for a certain inter-electrode distance d. This becomes a big problem for increasing the area. Therefore, the inventors of the present invention tried to improve various film forming parameters, found that the inter-electrode distance had an influence on the film thickness distribution, and by further increasing the inter-electrode distance, the distribution It was found that Under various conditions of the present invention, the relationship was obtained under the condition that the film thickness distribution T (%) in the substrate was within 10%. When d = 2 cm, the distribution was remarkably large, and it was not within the usable range. Is 3
It has been found that a good distribution can be obtained at a value larger than cm if d satisfies f / d <30.

Further, as shown in the relationship diagram between the electrode distance under various conditions and the defect level density in the film in FIG. 3, the defect density gradually decreases when the electrode distance exceeds 4 cm. It can be seen that, when the distance between the electrodes becomes smaller than 4 cm, it rapidly increases. The distance between the electrodes is preferably 4
It can be seen that cm or more is desirable. Therefore, in this example, the distance between the electrodes was set to 4 cm.

FIG. 37 shows a manufacturing apparatus used in this embodiment. As a basic structure, a conventional parallel plate type plasma C
It is similar to 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. Reference numeral 504 is a matching unit, and 505 is a high frequency power source. 5
07 is a gate valve, 508 is a turbo molecular pump, 50
9 is a rotary pump.

First, the SiH ₄ —NH ₃ mixed gas is diluted with H ₂ if necessary and introduced into the vacuum chamber 500. In this example, 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, respectively, and the pressure was maintained at 0.2 Torr. The frequency f of the high frequency power source was changed from 13.56 MHz to 150 MHz. At this time, the applied power is 10 mW / cm ^{2 for} film formation.
The above is sufficient, but in this example, 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 formation rate DR. In the figure, the substrate temperature T _{S is} 350 ° C. The deposition rate does not depend on the substrate temperature, but has a peak with respect to frequency. The reason is that the decomposition of the raw material gas is promoted as the discharge frequency increases, and the film forming rate increases once. However, when the frequency further increases, the raw material gas and the precursor start to overdecompose, and the film forming rate decreases. It is presumed to be because. Next, FIG. 39 shows the power supply frequency f and the in-film hydrogen amount C _H at each film forming temperature. The relationships between the amount of hydrogen in the film and the stress at the respective substrate temperatures of 350 ° C., 250 ° C. and 150 ° C. are shown in FIGS. 40, 41 and 42. From the figure, a slight compressive stress (specifically, 1 × 10 ⁹ dyn / cm ² or more and 4 × 10 5
⁹ dyn / cm ² or less) indicates that the frequency of the high frequency power supply is 30 MHz to 120 MH at a substrate temperature of 250 ° C. to 350 ° C. that realizes a conventional high quality film.
It can be realized by setting z or less.

Next, FIG. 43 shows the relationship between the frequency and the spin density in the film. The figure shows the frequency dependence at a substrate temperature of 350 ° C., but the same tendency was shown at 150 ° C. or higher. That is, it is presumed that in a low region where the frequency f is less than 30 MHz, the damage to the ions incident on the substrate is large and the film has many defects. As described above, FIG. 22 in which the mass spectrometer is installed at the substrate position and the distribution of the incident energy and the incident amount of the ions that jump in here is obtained is one 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, high energy components are incident on the substrate. Also, the frequency f is 120
The film quality also deteriorates in the region above MHz. It is presumed that the reason is that the raw material gas and the precursor were overdecomposed as the high-frequency discharge was transferred. Further, in consideration of increasing the area of this region, problems such as a film thickness / film quality distribution problem arise.

From these results, the frequency is 30 MHz.
It is in the range of less than 120 MHz, a stress slightly compressed side, and, N / Si ratio, optical band gap, high quality without adversely affecting spin density, and high productivity SiN _X
A thin film can be created.

Next, an example 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 on the gate electrode 32.
Are stacked. Source / drain electrodes 36 are formed on the semiconductor layer 34 via an ohmic contact layer 35. Then, it is covered with a protective film 37. Next, a method of manufacturing this TFT will be described with reference to FIG.
This is described using (d).

First, as shown in FIG. 45A, a Cr thin film (about 1000 Å) is formed on a Corning 7059 glass substrate 41 by a sputtering device and patterned to form a gate electrode 42.

After that, as a gate insulating layer 43, silicon nitride, SiN _x (about 30
00 Å) A thin film is formed, and then, as the semiconductor layer 44,
Non-doped amorphous silicon, i-type a-Si (about 6000
Å) Thin film, as ohmic contact layer 45, phosphorus-doped microcrystalline silicon, n ⁺ -type μc-Si (about 1000)
Å) Thin films are sequentially formed using the same equipment.

Secondly, as shown in FIG. 45B, an Al thin film (about 1 μm) is formed by a sputtering apparatus and patterned to form source / drain electrodes 46. The channel width W and the channel length L were set to W / L = 100.

Thirdly, as shown in FIG. 45C, unnecessary n ⁺ type μc-S is formed by reactive ion etching.
The i layer is etched to form the gap portion 48.

Fourth, as shown in FIG. 45 (d), an unnecessary SiN _x / i-type a-Si / n ⁺ -type μc-Si layer is further isolated, and then a protective film 47 is deposited. Forty-four thin film transistors are created.

Here, SiN _{x which is} the point of the present invention
The thin film manufacturing method will be described in detail.

As described in the first section, the a-Si thin film is formed by the parallel plate type plasma CVD apparatus as shown in FIG. This figure shows a SiN _x thin film forming chamber, 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 substrate heating heater, 605 is a grounding terminal, 606 is a matching box, 607 is a high frequency power source, 608 is an exhaust port, 609 is an exhaust pump, and 610 is a raw material. Gas inlet, 620, 630, 640, 622, 63
2, 642 are valves, and 621, 631, 641 are mass flow controllers.

After being preheated in a load chamber (not shown) in the front chamber, the substrate was loaded and the chamber was heated to 1 × 10 ⁻⁶ To.
Evacuate to rr or less. Next, the source gas Si
Mass flow controller 62 for H ₄ , NH ₃ , and H ₂
1,631,641, 10,200,100scc
m, the pressure is maintained at 0.2 Torr, the substrate heating heater 604 is set and held until the substrate temperature reaches 350 ° C., and then the frequency is set to 80 M from the high frequency power source 607.
Hz and power of 30 mW / cm ² are applied to deposit a SiN _x film of 3000 Å. After film formation, the same chamber is also set to 1
Evacuate to less than × 10 ^-6 Torr. Next, it is moved to the i-type a-Si film forming chamber in the next chamber (not shown).

Thus, 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. Si deposited at each frequency f
Electric field mobility of TFT using N _x thin film μ (cm ² / Vs
ec) is summarized with respect to the stress of the thin film as shown in FIG. Compared with the conventional case of using 13.56 MHz, the electric field mobility μ becomes maximum at the frequency f = 80 MHz, and an improvement of about twice was confirmed. Conventional 13.56MH
The electric field mobilities of the SiN _x thin film formed by the RF plasma CVD method of z are represented by black and white plots of NH ₃ and N ₂ , respectively.

That is, the frequency is 30 MHz or more and 120
The electric field mobility is improved at MHz or less, preferably 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 with z was compared. FIG. 48 shows the change in the threshold voltage when the ON state is maintained for 100 hours. It can be seen that the reliability is also improved.

Next, the fifth invention of the present application will be described.

FIG. 49 shows a manufacturing apparatus used in this embodiment. As a basic structure, a conventional parallel plate type plasma C is used.
It is similar to the VD device.

In the figure, 700 is a vacuum chamber,
Reference numeral 701 is an anode electrode, 702 is a substrate, and 703 is a cathode electrode. The anode electrode 701 is grounded at 706. Reference numeral 704 is a matching unit, and 705 is a high frequency power source. Reference numeral 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.

In addition to the parallel plate type as in the present embodiment, the carousel electrode type used in the manufacture of the photoconductor drum is not limited to this embodiment, if attention is paid to the way of applying the high frequency and the handling. Is applicable.

First, the principle of the manufacturing method according to this embodiment will be described. FIG. 50 shows the emission intensity [SiH ^* ] of SiH ^* radical (414 nm) and the emission intensity [H ^* ] of hydrogen radical.
The applied high frequency f dependence of (656 nm) is shown. FIG. 51 shows the dependency of the deposition rate R on the applied high frequency f. 52 and 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 3sccm, hydrogen 15
The pressure is 0 sccm and the pressure is 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 accordingly around f = 30 MHz.
However, it has a maximum value around f = 80 MHz,
It can be seen that after that, there is a decreasing tendency, and when it exceeds 120 MHz, it begins to decrease sharply. 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.

From 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 over 100 MHz, the film thickness distribution on the substrate becomes large, and polysilane is easily formed, which becomes dust and pinholes are made cheaper. Further, it was not possible to obtain a film having uniformly good film characteristics. Therefore, preferably, the effects of the present invention can be sufficiently exerted 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.

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

Generally, there are some conditions for producing microcrystalline silicon. First, the relationship [H ^* ] / R> a (a is a constant) must be established between [H ^* ] in plasma and the film formation rate R. This indicates that it is difficult to crystallize unless there is a certain amount of hydrogen covering the film formation surface.
Further, in plasma using silane gas, the film formation rate R is proportional to [SiH ^* ], so this condition is [H ^* ]
It can be rewritten as / [SiH ^* ]> a '. Under the actual conditions of the invention, this value was a '= 1. In a normal system, the dilution ratio of hydrogen gas is increased to earn this ratio.

However, by doing so, the partial pressure of the silane gas was lowered, and the film formation rate was extremely reduced. Therefore, by increasing the applied high frequency as in the present invention, it is possible to increase the gas decomposition efficiency and prevent the film formation rate from decreasing. Further, it is possible to realize a higher film forming rate and shorten the film forming time. This is the first effect of the present invention.

52 and 53, [H ^* ] / [SiH
^Paying attention to the point P where ^* ] = 1, the point P moves to the upper left as the applied high frequency f is increased. 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 the point where [H ^* ] / [SiH ^* ] = a ′ is satisfied shows the same change. That is, in order to realize the [H ^* ] / [SiH ^* ] ratio above a certain fixed ratio at a certain applied high frequency f, the applied high frequency power must be adjusted.

When this is obtained under various conditions this time,
The lower limit is the curve of k = 1 as shown in FIG. 54, and preferably, the region indicated by the slanted lines in the figure as k = 10, which is slightly outside the boundary region, is the region in which the present invention can be realized. found. This point is the second effect of the present invention. That is, by increasing the applied high frequency, the desired film can be obtained in a wider applied high frequency power range without deteriorating the conditions for producing microcrystalline silicon. This was particularly effective when the apparatus was enlarged and film formation was performed on a large area. That is, the high frequency power source can be downsized despite the large size of the device, and the device cost can be reduced.
In addition, even if it affects the characteristics of the film, if it can be created in a region where the applied power is small, the total energy of the ions in the plasma will be reduced, so the damage caused by the ions incident on the film surface should be reduced. It is possible to produce a film having good film characteristics.

Further, from the viewpoint of reducing the damage of ions, pay attention to the movement of ions in plasma. Generally, the ions in the high frequency plasma oscillate in the plasma according to the oscillating electric field due to the high frequency in the plasma.
This situation can be expressed in an equation as follows. Here, A is the amplitude of oscillation of the ions.

A≈V / w V: maximum speed in one cycle of high frequency w: angular frequency of high frequency: f = 2πw Let us assume that the film forming apparatus currently being considered is a parallel plate type apparatus, and the distance between electrodes is d. .. Then, if the condition of d> A is satisfied, the ions in the plasma will move back and forth in the plasma without reaching the substrate. Such a state is generally called a state of being trapped or trapped in plasma. As is clear from this relational expression, increasing the applied high frequency makes it possible to create a trapped state of ions regardless of the size of the device. By doing so, the amount of ions incident on the substrate could be reduced. Further, as will be described later, since ions are considered to have an adverse effect on the formation of fine crystals, it is effective not only for simple ion damage but also for efficiently producing fine crystals. The present invention intends to positively utilize such a state.

This is illustrated in FIG. 22 already described. A mass spectrometer was installed at the substrate position, and the distribution of the incident energy and the incident amount of the ions that jumped in here were 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
= 13.56 MHz and f = 80 MHz according to the present invention, the incident energy and the incident amount of the ions incident on the substrate are different. Obviously, under the condition of f = 100 MHz, the average incident energy becomes lower and the incident amount decreases.

As shown in FIG. 2, when the frequency is large for a certain electrode distance d, the distribution becomes large. This becomes a big problem for increasing the area. Therefore, the inventors of the present invention tried to improve various film forming parameters, found that the inter-electrode distance affected the film thickness distribution, and by further increasing the inter-electrode distance,
It was found that the distribution became smaller. Under various conditions of the present invention, the relationship was obtained under the condition that the film thickness distribution T (%) in the substrate was within 10%. When d = 2 cm, the distribution was remarkably large, and it was not within the usable range. Is larger than 3 cm, if d satisfies f / d <30,
It was found that a good distribution can be obtained.

FIG. 3 shows the relationship between the interelectrode distance and the defect level density in the film under various conditions. It can be seen that the defect density gradually decreases when the distance between the electrodes exceeds 4 cm.
It can be seen that when the distance between the electrodes becomes smaller than 4 cm, it rapidly increases. It can be seen 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
The examination was conducted in cm.

Based on the above experimental facts and consideration, microcrystalline silicon containing no impurities was prepared 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 is set to 250 ° C., SiH ₄ gas is caused to flow at 3 sccm, and H ₂ gas is set to 1
The flow rate was 50 sccm, the internal pressure of the chamber was 0.5 Torr, and the pressure 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 required time to form a film.

Samples were prepared by changing the applied high frequency from f = 13.56 MHz to f = 150 MHz. The high frequency power at this time is 7 mW / cm ² to 0.1
It was set to W / cm ² .

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

The solid line shown in FIG. 57 (a) shows the dependence of the dark conductivity of the film applied under this condition on the applied high frequency. Figure 5
8 (a) shows the dependence of activation energy on the applied high frequency. The broken line in the figure indicates that the film has a lot of dust and the reproducibility of the characteristics is not sufficient. When the frequency exceeds 100 MHz, particularly 120 MHz, overdecomposition of silane gas is likely to occur, and polysilane is easily formed, which seems to be the cause of dust.

57 and 58, it can be seen that as the applied high frequency is increased, the dark conductivity is increased and the activation energy is decreased. This is a phenomenon that accompanies crystallization of the film, and it has been previously pointed out that the amount of ions incident on the substrate surface is reduced as a condition for crystallization of the deposited film. From this experimental result, the applied high frequency is raised. As a result, the ions in the plasma are trapped,
As described with reference to FIG. 22, it is considered that the crystallization actually progressed because the number of ions incident on the substrate and the energy thereof decreased.

A further effect of the present invention is improvement of the initial film. Generally, when depositing microcrystalline silicon, 5
It is known that the initial film of about 00Å is a region where the growth of microcrystals is insufficient and there are many defects. It is considered that this is because a negative bias is applied to the insulating substrate at the initial stage of film formation, and accordingly, ions are incident on the substrate, which causes the above inconvenience. Microcrystalline silicon is often used as a blocking layer or an ohmic layer of a semiconductor device, and its film thickness is 100 at most.
It is often about 0Å, which means that about half of this thickness does not have good film quality.

It has been known that such an initial film causes fluctuations due to film formation conditions and process instability, and finally causes deterioration and instability of device characteristics. Such troubles at the production site are especially serious.

Therefore, if the manufacturing method of the present invention is utilized, the amount of ions trapped in the plasma in the first place and incident on the substrate can be reduced. Therefore, it was confirmed that the initial film of microcrystalline silicon obtained by the method of the present invention was a good film. [Embodiment 2] Next, a second embodiment will be described in which an n ⁺ type microcrystalline silicon film containing impurities is formed by the manufacturing method according to the fifth invention of the present application. First, the state of 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 100
Samples with varying mW / cm ² were prepared. The applied high frequency was changed from 13.56 MHz to 150 MHz.

A glass substrate 702 is mounted on the anode electrode in the chamber 700, and exhaust pumps 708, 70 are attached.
It was evacuated to 10 ^-6 Torr by 9. Next, after setting the substrate temperature to 250 ° C., the valves 710 and 718 are opened and SiH ₄ gas is caused to flow at 3 sccm, and the valves 712 and 7
Open 20 and PH ₃ diluted to 100 ppm with H ₂ gas
Flow gas 150sccm and set the chamber pressure to 0.5T.
It was set to orr and kept for 30 minutes, and waited for the substrate temperature to stabilize. After that, high-frequency power was applied and the matching device was adjusted to start discharge, and discharge was performed for a required time to form a film. A 1 μm film was formed. After that, the gas was exhausted and a high vacuum was drawn up to 10 ⁻⁶ Torr.

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

FIG. 57B shows the dependence of the dark conductivity of the film formed under these conditions on the applied high frequency. (B) in FIG. 58
Shows the dependence of activation energy on the applied high frequency. FIG. 59.
Shows the dependence of doping efficiency on the applied high frequency. 57,
58, it can be seen that as the applied high frequency is increased, the dark conductivity is increased and the activation energy is decreased. As can be seen from the movement of the non-doping film in (a) in the figure, the crystallization of the film is promoted when the doping efficiency is increased and the high frequency of the doping is also promoted, and accordingly, the incorporation of phosphorus into the film becomes active. It seems that it is being done. Moreover, as can be seen from FIG. 59, the doping efficiency also rises as the applied high frequency is increased, which is also considered to be due to the improvement of the crystallinity.

Next, of the films formed here, the film having an applied high frequency of 80 MHz was evaluated by using it as an ohmic layer of a photoconductive type 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 exhausted to 10 ^-6 Torr by exhaust pumps 708 and 709. Next, the substrate temperature was set to 250 ° C., SiH ₄ gas was made to flow at 3 sccm, H ₂ gas was made to flow at 30 sccm, the chamber internal pressure was set to 0.5 Torr, and held for 30 minutes to stabilize the substrate temperature. waited. After that, a normal high frequency of 13.56 MHz was applied with a power of 10 mW / cm ² , and the matching device was adjusted to start discharge, and the discharge was performed for a required time to form a film. Discharge for 3.5 hours and 5000
Å Intrinsic amorphous silicon was deposited. After that, the gas was exhausted and a high vacuum was drawn up to 10 ⁻⁶ Torr.

Next, n ⁺ type microcrystalline silicon was deposited on this intrinsic amorphous silicon by the manufacturing method of the present invention. The substrate was held on the anode electrode in the chamber 700, while the substrate temperature was set to 250 ° C., SiH ₄
The 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 until the substrate temperature became stable. After that, a high frequency of 80 MHz was applied and the matching device was adjusted to start discharge, and the discharge was performed for a required time to form 1500 Å n ⁺ -type amorphous silicon film. After that, the gas is exhausted and 10 ^-6 Torr
High vacuum was pulled up to.

Next, this substrate was taken out from the film forming apparatus,
Aluminum was deposited to a thickness of 1 μm by a vacuum evaporation method.

After that, this aluminum was patterned to form an electrode.

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

The bias dependence of the dark current of the device thus manufactured is shown in FIG. 61 (b). FIG. 62B shows the bias dependence of the photocurrent under the light source of wavelength 560 (nm) and 200 (lx). In the figure, (a) is data of a conventional device. Conventionally, the dark current exhibited a non-ohmic characteristic when the bias was low. The photocurrent also showed slightly similar characteristics. This is considered to occur because the junction between the intrinsic amorphous silicon layer and the n ⁺ microcrystalline silicon layer is not good. However, according to 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, the damage to the intrick amorphous silicon layer by ions was reduced, and the photoelectric characteristics were also improved. [Embodiment 3] Next, in the manufacturing method according to the fifth invention of the present application, p ⁺
A third embodiment in which a mold type microcrystalline silicon film is formed will be described.

First, a state of plasma at this time will be shown. FIG. 55 shows the frequency dependence of the emission intensity of boron radicals. It can be seen that the emission of boron radicals, which normally shows no emission, is observed, and that the emission intensity is also increased by increasing the applied high frequency. It is considered that this is because the electron density in the plasma increased as in the case of silane gas and the decomposition efficiency increased. FIG. 56 shows the applied power dependence of the emission intensity of boron radicals. It can be seen that the emission intensity increases as the applied power increases. The applied high frequency in this embodiment is 13.56 MHz to 150 MH.
z.

Samples were prepared under the conditions showing these plasma states.

The glass substrate 702 shown in FIG. 49 is attached to the anode electrode in the chamber, and the exhaust pump 708,
At 709, the gas was exhausted to 10 ^-6 Torr or less. Substrate temperature is 2
After setting the temperature to 00 ° C., valves 710 and 718 were opened to flow silane gas at 3 sccm, valves 713 and 721 were opened to flow 150 sccm of diborane diluted to 1% with H ₂ gas, and held for 30 minutes. Then, turn on high frequency power,
By adjusting the matching device, plasma discharge was started and a film was formed. The film 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 vapor-deposited on this film, and dark conductivity and activation energy were measured at room temperature (25 ° C.).

FIG. 57 (c) shows the applied high frequency dependence of the dark conductivity of the film formed under these conditions. FIG. 58C shows the dependence of activation energy on the applied high frequency. FIG. 59 shows the dependence of the doping efficiency on the applied high frequency. 57 and 58
As the applied high frequency is increased, 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), when the applied high frequency is also increased in the doping efficiency, crystallization of the film is promoted, and accordingly, boron is actively taken into the film. It seems that there is. Moreover, FIG.
As can be seen from (b), the doping efficiency also rises as the applied high frequency is increased, and it is considered that this is also due to the improvement of the crystallinity.

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

First, the substrate 26 on which the lower electrode 262 is formed
N ⁺ -type microcrystalline silicon 263 was deposited on the No. 1 substrate. The substrate was held on the anode electrode in the chamber 700 of FIG. 49, SiH ₄ gas was flowed at 3 sccm and phosphine gas diluted to 100 ppm with H ₂ gas was flowed at 150 sccm while the substrate temperature was set at 250 ° C. Was set to 0.5 Torr and held for 30 minutes to wait for the substrate temperature to stabilize. After that, the usual 13.56
A high frequency of MHz was applied at a power of 30 mW / cm ² , and electric discharge was started by adjusting the matching device, and the electric discharge was performed for a necessary time to form 1500 Å n ⁺ -type amorphous silicon film. After that, the gas was exhausted and a high vacuum was drawn up to 10 ⁻⁶ Torr.

Next, the substrate was held in the chamber, and the substrate temperature was set at 250 ° C., while SiH ₄ gas was added for 3 sc.
cm flow, 30 sccm flow with H ₂ gas, the chamber internal pressure was set to 0.5 Torr, the chamber was kept for 30 minutes, and waited for the substrate temperature to stabilize. After that, the usual 13.5
Input a high frequency of 6 MHz with a power of 10 mW / cm ² ,
Discharge was started by adjusting the matching unit, and the film was formed by discharging for a required time. Discharged for 3.5 hours to form 5000 Å intrinsic amorphous silicon 264. After that, the gas was exhausted and a high vacuum was drawn up to 10 ⁻⁶ Torr.

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

Next, this substrate was taken out from the film forming apparatus,
The transparent conductive film 266 was formed by the vacuum evaporation method.

FIG. 64B shows the diode characteristics of this device. In the figure, (a) shows data when the p ⁺ microcrystalline silicon layer is formed by the conventional manufacturing method. The current during reverse bias could be reduced considerably. Moreover, 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 characteristic was improved.
This is probably because the damage caused by ions was reduced.

In these examples, only phosphine and diborane are taken up for description, but the same effect can be obtained by using arsine or the like as the other doping gas.

The respective embodiments described above are the same as the first embodiment of the present invention.
-Although it is about the case where each manufacturing method of the fifth invention is implemented, each of the first to fifth inventions of the present application can be arbitrarily combined. For example, the manufacturing method of the third or fourth invention of the present application can be used for a gate insulating layer of a thin film transistor or the like, and the manufacturing method of the first or second invention of the present application can be used for an i-type semiconductor layer. Here, all of the layers (i-type semiconductor layer, n ⁺ semiconductor layer, insulating layer, etc.) are the first to fifth layers of the present application.
It is needless to say that it is desirable to be formed by the manufacturing method of the invention.

A case where a non-single crystal semiconductor device is manufactured by combining the manufacturing methods of the first to fifth inventions of the present application will be described below.

As described above, in the field effect transistor as shown in FIG. 18, the P-I-N type semiconductor device, etc., it is desirable to continuously stack the functional films.
The problem in controlling the interface, which is an important factor for the characteristics, is that not all films have the same film formation rate, but also different required thicknesses. As a result, a rate-determining step occurs during continuous film formation, which becomes the takt time.

In the above-described device as shown in FIG. 18, the film 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-determining step can be eliminated, throughput can be improved, and cost reduction can be realized. Further, the throughput can be increased by further increasing the discharge frequency of each layer in consideration of quality.

Of course, not only the throughput is increased, but also the amorphous silicon nitride film according to the present invention is used as the gate insulating layer, and the non-single crystal film such as the amorphous silicon film or the microcrystalline silicon film according to the present invention is used. When used as a semiconductor layer, it has high reliability and excellent characteristics as described above.
Can be realized.

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

[0216]

As described above, according to the first invention of the present application, in the plasma CVD method, the frequency of the high frequency power source, the input power depending on the frequency, the pressure, and the inter-electrode distance are defined. As a result, the a-Si film can be manufactured inexpensively with high yield and 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.

Further, according to the second invention of the present application, in the plasma CVD method, the frequency of the high frequency power source, the pressure, and the distance between the electrodes are defined, and further, the time during which the source gas stays in the discharge space, that is, By defining the residence time, a-
Even with a large area of Si film, it is inexpensive and has a high yield.
Can be manufactured with high quality. 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.

Further, according to the third invention of the present application, it is possible to suppress a decrease in the film formation rate and obtain a sufficient film formation rate.
As a result, manufacturing throughput can be increased. In addition, the decomposition efficiency of the film forming gas can be increased, the amount of gas used can be reduced, and the gas utilization efficiency can be significantly increased. As a result, the manufacturing cost can be reduced. Furthermore, since ions that deteriorate the characteristics of the film are confined in the plasma to form a film, it is possible to suppress the generation of defects and provide a film having good characteristics. Moreover, since plasma damage at the interface can be reduced, a high-quality film can be stably provided. Also, degassing from the chamber can be suppressed,
Incorporation of impurities into the film is also reduced, defects due to this can be reduced, and a high-quality film can be provided. Further, since film formation can be performed with a small electric power in the conventional device, the power supply device can be easily downsized, and the device cost can be reduced particularly for a large-scale device for production.

According to the fourth invention of the present application, the plasma C
In the VD method, by defining the frequency of the high frequency power source and the distance between the electrodes, the SiN _x thin film can be manufactured inexpensively with high yield and high quality even in a large area. In particular, in thin film transistors, thin film transistor type optical sensors, and the like, various characteristics such as electric field mobility and photoelectric characteristics, and improvement in stability thereof can be achieved.

Further, according to the fifth aspect of the present invention, it is possible to obtain a sufficient film formation rate while suppressing a decrease in the film formation rate. As a result, manufacturing throughput can be increased. In addition, the decomposition efficiency of the film forming gas can be increased, the amount of gas used can be reduced, and the gas utilization efficiency can be significantly increased. As a result, the manufacturing cost can be reduced.
Furthermore, since ions that deteriorate the characteristics of the film are confined in the plasma to form a film, it is possible to suppress the generation of defects and provide a film having good characteristics. Moreover, since plasma damage at the interface can be reduced, a high-quality film can be stably provided.
Moreover, it is possible to improve the initial film, and by removing the cause of the unstable interface characteristics, it is possible to stably provide a high-quality film. Further, since film formation can be performed with a small amount of electric power as compared with the conventional film forming apparatus, it is possible to easily downsize the power supply device, and to reduce the device cost particularly for a large-sized device for production.

According to the sixth aspect of the present invention, the non-single-crystal semiconductor layer is formed by the plasma CVD method using high-frequency discharge with a frequency of 30 MHz or more and 120 MHz or less. Therefore, it is possible to provide a non-single-crystal semiconductor device capable of improving the characteristics, enabling high-speed film formation, and further improving the interface characteristics that influence the device characteristics. The sixth invention of the present application can be applied to a semiconductor device having an insulated gate transistor structure such as a TFT. In this case, the gate insulating layer and / or the ohmic contact layer is formed by a plasma CVD method using a high frequency discharge having a frequency of 30 MHz or more. If manufactured, a higher quality non-single-crystal semiconductor device can be provided. Further, by appropriately selecting the discharge frequency in consideration of the quality of each layer, the rate-determining step of each layer can be eliminated, throughput can be improved, and cost reduction can be realized. Further, the throughput can be increased by further increasing the discharge frequency of each layer in consideration of quality.

Further, according to the seventh invention of the present application, by forming the protective layer by the plasma CVD method utilizing the high frequency discharge having the frequency of 30 MHz or more, it is possible to form the high quality protective layer with less ion damage.

[Brief description of drawings]

FIG. 1 is a characteristic diagram showing a relationship between an emission intensity ratio and a hydrogen bond 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 defect level density 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 the relationship between frequency and hydrogen bonding state.

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

FIG. 10 is a characteristic diagram showing the relationship between frequency and film formation rate.

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 formation rate and photoelectric characteristics.

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

FIG. 14 is a characteristic diagram showing the relationship between residence time and 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 the relationship between residence time and film formation rate.

FIG. 17 is a characteristic diagram showing the 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 drawing that shows the manufacturing method of the thin film transistor.

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

FIG. 21 is a TFT using the amorphous silicon thin film of the present invention.
It is a figure which shows the initial characteristic of.

FIG. 22 is a characteristic diagram showing substrate incident energy due to a difference in frequency.

FIG. 23 is a TFT using the amorphous silicon thin film of the present invention.
It is a figure which shows the electric field mobility of.

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

FIG. 25: Emission intensity of SiH ^* radical [SiH ^* ]
And applied high frequency f of emission intensity [N ^* ] of nitrogen radicals
It is a characteristic view which shows dependence.

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

FIG. 27: Luminescence intensity of SiF ^* radical [SiF ^* ]
And applied high frequency f of emission intensity [N ^* ] of nitrogen radicals
It is a characteristic view which shows dependence.

FIG. 28: Emission intensity of SiF ^* radical [SiF ^* ]
3 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 the dependency of the deposition rate R on the 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 V _th shift during ON operation.

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

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

FIG. 34 is a characteristic diagram showing frequency dependence of 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 the relationship between frequency and film formation rate.

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

FIG. 40 is a characteristic diagram showing a relationship between hydrogen amount 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 drawing that shows the manufacturing method of the thin film transistor.

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

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

FIG. 48 is a characteristic diagram showing changes in threshold voltage in the present example.

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

FIG. 50: Emission intensity of SiH ^* radical [SiH ^* ]
And the applied high frequency f of the emission intensity [H ^* ] of hydrogen radicals
It is a characteristic view which shows dependence.

FIG. 51 is a characteristic diagram showing the dependency of the deposition rate R on the applied high frequency f.

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

FIG. 53: Emission intensity of SiH ^* radical [SiH ^* ]
3 is a characteristic diagram showing the dependence of the emission intensity [H ^* ] of hydrogen radicals on the applied high frequency power Pw.

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

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

FIG. 56: Applied high frequency power P of doping gas radical
It is a characteristic view which shows w dependence.

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

FIG. 58 is a characteristic diagram showing the dependence of activation energy on the 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 this example.

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

FIG. 62 is a characteristic diagram showing bias dependence of photocurrent of a 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 formation rate and photoelectric characteristics.

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

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

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

[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 Grounding 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 ⁺ 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 Kus 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 matcher 705 high frequency power supply 706 ground 707 gate valve 708 turbo molecular pump 709 rotary pump 710,718 silane gas line valve 711 719 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

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Hidemasa Mizutani 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc.

Claims (18)

[Claims] 1. A method of manufacturing an amorphous silicon film by a plasma CVD method using a high frequency discharge, wherein 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 30 MHz.
Above 120MHz and below, input power P _W (W / c
m ² ) is less than or equal to the value specified by 10 / f (MHz),
A method for manufacturing an amorphous silicon film, characterized in that an inter-electrode distance d (cm) is set to a value larger than a value defined by f / 30. 2. A method for producing an amorphous silicon film by a plasma CVD method using high frequency discharge, wherein 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 30 MHz.
Above 120MHz and below, distance between electrodes d (cm)
Is larger than the value defined by f / 30, and the residence time τ (sec) during which the source gas Q (sccm) stays in the discharge space V (cm ³ ) is τ = 78.947 × 10 ⁻³ × V ×
The residence time τ when defined as P / Q is 0.05 se
A method of manufacturing an amorphous silicon film, characterized in that the time is not less than c and not more than 2.5 seconds. 3. At least by plasma CVD method,
In a manufacturing method of depositing an amorphous silicon nitride film by using a mixed gas containing a gas containing Si and a nitrogen gas, a VHF high frequency having a frequency f of 30 MHz or more and an inter-electrode distance is d (cm). At this time, a plasma is generated by applying so as to satisfy f / d <30, and a method of manufacturing an amorphous silicon nitride film. 4. The amorphous silicon nitride film manufacturing method according to claim 3, wherein a mixed gas containing at least a gas containing Si, a hydrogen gas, and a nitrogen gas is used. Manufacturing method of silicon nitride film. 5. The method for producing an amorphous silicon nitride film according to claim 3, wherein a mixed gas containing at least a gas containing Si and F and a nitrogen gas is used. Silicon film manufacturing method. 6. The method for producing an amorphous silicon nitride film according to claim 3, wherein a mixed gas containing at least a gas containing Si and F, a hydrogen gas, and a nitrogen gas is used. Method for manufacturing amorphous silicon nitride film. 7. A manufacturing method for depositing an amorphous silicon nitride film by using a mixed gas containing at least a silicon compound and ammonia as a source gas by a plasma CVD method, wherein V having a frequency f of 30 MHz or more and 120 MHz or less is used.
F / d when the distance between the electrodes of HF high frequency is d (cm)
A method of manufacturing an amorphous silicon nitride film, characterized in that a voltage is applied so as to satisfy <30 and plasma is generated. 8. The method of manufacturing an amorphous silicon nitride film according to claim 7, wherein the method of manufacturing the amorphous silicon nitride film is used in a laminated structure with an amorphous silicon film. 9. The stress of the amorphous silicon nitride film is 1 ×.
10 ⁹ dyn / cm ² or more, 4 × 10 ⁹ dyn / cm ²
The method for producing an amorphous silicon nitride film according to claim 8, wherein the method exhibits the following compressive stress. 10. A method of 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 converted into 1 / f (W / cm ² ) (f : MHz) or more so that f / d <30 is satisfied when the distance between the electrodes is d (cm), and plasma is generated to produce a microcrystalline silicon film. 11. The method for producing a microcrystalline silicon film according to claim 10, wherein a gas containing boron, a gas containing phosphorus, and a gas containing miso are used as impurity gases with respect to the gas containing Si. Method for manufacturing a microcrystalline silicon film. 12. The method for producing microcrystalline silicon according to claim 10, wherein the ratio of the emission intensity [H ^* ] of hydrogen radicals to the emission intensity [SiH ^* ] of silane radicals is [H ^* ] /. A method for manufacturing a microcrystalline silicon film, wherein [SiH ^* ] ≧ 1. 13. A non-single-crystal semiconductor device having a non-single-crystal semiconductor layer formed by a plasma CVD method using a high-frequency discharge having a frequency of 30 MHz or more and 120 MHz or less. 14. A substrate, at least a gate electrode, a gate insulating layer, a non-single-crystal semiconductor layer, and a pair of source / drain electrodes are sequentially stacked, and the non-single-crystal semiconductor layer and the source / drain are stacked. The non-single crystal semiconductor device according to claim 13, further comprising an ohmic contact layer provided between the electrode and the electrode. 15. The gate insulating layer has a frequency of 30 MHz.
15. The non-single-crystal semiconductor device according to claim 14, wherein the non-single-crystal semiconductor device is manufactured by a plasma CVD method using a high frequency discharge of z or more. 16. The plasma CV using the high frequency discharge having a frequency of 30 MHz or more for the ohmic contact layer.
15. The non-single crystal semiconductor device according to claim 14, wherein the non-single crystal semiconductor device is manufactured by the D method. 17. The non-single crystal according to claim 14, wherein at least the gate insulating layer, the non-single-crystal semiconductor layer, and the ohmic contact layer are continuously formed without being exposed to the atmosphere. Crystal semiconductor device. 18. A non-single-crystal semiconductor device having a protective layer formed by a plasma CVD method using a high-frequency discharge having a frequency of 30 MHz or more.