JPS6233772A - Deposited film forming device by microwave plasma cvd method - Google Patents

Abstract

PURPOSE:To stably form a deposited film having high quality on a substrate at a high speed by a microwave CVD method by forming plasma by the microwaves in a reaction vessel and impressing a bias voltage to a substrate or substrate holding body. CONSTITUTION:A gaseous raw material contg. SiH4, H2 or SiF4 is supplied through a gas chamber B from a perforated inside wall 3 into the reaction chamber A of the reaction vessel 1 and thereafter the microwaves 61 generated by a microwave power source 6 are introduced from a dielectric window 4 consisting of quartz, etc. into the reaction chamber A to form the plasma. The cylindrical substrate 10 disposed in the reaction chamber A is heated and held to and at a prescribed temp. by a substrate holding cylinder 9 contg. a heater 11. The negative side of a DC power source 15 is connected to the above- mentioned substrate 10 or to the substrate holding cylinder 9 if the substrate 10 is an insulator to impress the bias voltage thereto. A plasma boundary 16 is thereby formed near the surface of the substrate 10, by which the transfer of the charge particles, H<+>2, etc. is controlled and the a-Si(H, F) film having high quality is formed at a high speed.

Description

Detailed Description of the Invention [Technical Field to which the Invention Pertains] The present invention relates to a film deposited on a substrate, particularly a functional film, particularly a semiconductor device, a photosensitive device for electrophotography, a line sensor for image input, an imaging device, and a photosensitive device. The present invention relates to an apparatus for forming an amorphous semiconductor film used in power devices and the like.

[Description of prior art]

Conventionally, semiconductor devices, photosensitive devices for electrophotography,
Amorphous silicon, such as amorphous silicon compensated with hydrogen or/and halogen (e.g. fluorine, chlorine, etc.), is used as an element member for image input line sensors, imaging devices, photovoltaic elements, and various other electronic elements, optical elements, etc. Silicon (hereinafter referred to as RA-3i)
It is written as H,X)j. ) have been proposed, and some of them have been put into practical use.

Then, such a deposited film is deposited using a plasma CVD method, that is,
It is known that the material gas is decomposed by direct current, high frequency, microwave, or glow discharge to form a thin deposited film on the substrate 9 such as glass, quartz, stainless steel, aluminum, etc. Various devices have also been proposed.

Such a conventional apparatus for forming a deposited film using the plasma CVD method typically has an apparatus configuration shown in the schematic cross-sectional view of FIG. 6. In FIG. 6, 1 indicates the entire reaction vessel, 2 indicates the side wall, and 21 indicates the bottom wall. 6 is a multi-perforated inner wall,
4 is a dielectric window made of alumina ceramics or quartz, 5 is a waveguide, 6 is a microwave power source, 61 is a microwave, 7 is an exhaust pipe, 71 is a valve, 8 is a raw material gas supply pipe, 81 is pulp, 9 10 represents a cylindrical substrate, 11 represents a heater, and 12 represents a support leg. Further, A indicates a reaction chamber, and B indicates a gas chamber.

Deposited film formation using such conventional deposited film forming equipment is
This is done as follows.

That is, the gas in the reaction chamber A of the reaction vessel 1 is evacuated through the exhaust pipe 7, and the cylindrical substrate 10 is heated to a predetermined temperature by the heater 11 built in the substrate holding cylinder 9.
Hold. Next, if an amorphous silicon deposited film is to be formed, for example, via the raw material gas supply pipe 8,
A raw material gas such as run gas, hydrogen gas, SiF4 gas, etc. is introduced into the gas chamber B, and the raw material gas is fed to the multi-perforated inner wall 3 of the gas chamber B.
is discharged into the reaction chamber A from a number of holes. At the same time, a frequency of 2.45 GHz is generated from the microwave power source 6.
The microwaves are introduced into the reaction chamber A through the waveguide 5 and the dielectric window 4. In this way, the raw material gas introduced into the reaction chamber A is excited by the microwave energy and dissociated, generating lanocal particles, ion particles, electrons, etc., which react with each other to form a deposited film on the surface of the substrate 10. be done.

By the way, in such a plasma CVD method, generally when the degree of vacuum is on the order of 10-2 Torr, the frequency is 13.
When using a high frequency of 56MHz, the electron temperature is ~2ev
When a low ionization plasma with a concentration of about 1 electron to 1010 cIrL-5 is generated and microwaves with a frequency of 2.45 GHz are used, the electron temperature is 6 to 5 eV1 and the electron concentration is about 7.
Highly ionized plasma of approximately X 10"crrt-"5 is generated.

On the other hand, in the decomposition reaction of silane (SiH4) gas molecules due to electron collision, S
iH2+f(2(2,1eV), SiH3+E(4
, 1eV: 5iE2-1-H (2,6eV
)), Si + 2)12 (4,4eV), 5i
Particles such as H-+-820H (5,9 eV) are generated.

Among these decomposition products, at a vacuum level of about 10-2 Torr, neutral radical species are mainly generated due to inelastic collisions between electrons and molecules, and the amount of radical species in the plasma is S
The number decreases in the order of SiH2*, SiH3*, Si*, and S1♂ (* represents an excited state).

However, the difference in the amount of SiH2* and SiH* is only about 3 times (, there is almost no difference in concentration between Sin* and S1*. Among these neutral radical species, good quality a-3i (H, X)
S1* and 5i mainly contribute to the formation of the semiconductor film.
It is ns. On the other hand, when higher-order silicon particles such as 5iB2* and 5ills* become the main radical species in deposited film formation, the formed deposited film becomes a polymeric one with a high hydrogen content, and the defect density in the film decreases. This results in a high quality a-8i (H,X) semiconductor film.

In other words, a large number of crystal defects called dangling bonds due to dangling bonds occur in an amorphous 7-licon film formed only with Si radicals, and an amorphous silicon film formed only with SiH2 and SiH3 radicals occurs.
Because the silicon film contains too much hydrogen, it becomes a polymeric film in which bonds are completely broken by hydrogen atoms, which becomes a trap for charges within the semiconductor, leading to a decline in the electrical properties of the semiconductor. Generally, an amorphous silicon semiconductor film having excellent properties as a semiconductor contains 10 to 20 hydrogen atoms, and dangling punts are appropriately compensated by the hydrogen atoms. Therefore, in order to form a high quality amorphous silicon semiconductor film on a substrate, it is necessary to appropriately supply S1 radicals and 81B radicals to the surface of the substrate.

Microwave plasma CVD as shown in Figure 6 above
When an a-3i film is formed using a deposited film forming apparatus using the method,
The generated highly ionized plasma generates a large amount of low-order neutral radical species, Si* and Sin*, so compared to the deposited film formed by high-frequency plasma CVD, which generates low-ionized plasma, , a high-quality deposited film can be obtained even with high-speed film formation.

However, when a deposited film is formed by such a microwave CVD method, there is a problem in that not only low-order neutral radical species but also high-order neutral radical species are generated in large quantities at the same time.

In order to solve this problem, in recent years, 5iR has been developed as a raw material gas.
4 gas and hydrogen gas, silicon tetrafluoride (SiF'4
) A technology has been developed that uses a gas to generate fluorine radical species with high binding energy and reacts with silicon radical species to suppress the generation of higher-order silicon radical species. That is, by mixing SiF4 gas with the raw material gas, the formation of a polymeric film is reduced, the production of polysilane powder, which is conventional, is also reduced, and a-8i (H,
X) Utilization efficiency of raw material gas used for film formation is also improved.

Moreover, since fluorine atoms are contained in the a-8i (H, When an a-8i (H, .

L/f)' L The microwave CVD method using SiF4 gas has the following problems. Below, the fourth
This will be explained using figures. FIG. 4 is a diagram schematically showing the film forming process that progresses near the surface of the substrate at a degree of vacuum of about 10 -2 Torr. In the figure, 20 is a conductive base and is electrically grounded.

21 is a-3i (H,X) semiconductor film, 22 is S
1* is a neutral radical species such as Sin*, SiF*, F*, etc., 26 is a positive ion species such as H2 or 81, 24 is a negative ion species, and 25 is an electron. 26 is SiF2 and SiF4, in which S1 atoms and H atoms in the a-81(H+χ) film once deposited on the substrate react with highly reactive active species such as fluorine radical species and escape from the film. It is a gas body such as. These particles near the substrate surface move randomly, regardless of whether they are neutral particles or charged particles, and the a-3i ( H, X) contributes to the formation of the film.

That is, as shown in Fig. 4, in the conventional microwave CVD method using SiF4 gas as one of the raw material gases, the reaction is performed to suppress the production of higher-order silane particles that are the cause of polysilane production. Fluorine neutral radical species are
A-81 (Hr
) There is a problem in that the film reacts with 81 atoms of the film to generate gases such as SiF2 and SiF4 and etches the film, thereby reducing the deposition rate of the deposited film.

In addition, 81 atoms in the a-S L (H+
There is also the problem of increasing defects in the film and deteriorating its electrical properties as a semiconductor.

Furthermore, in microwave plasma, the frequency of the microwave is high, so the heavy charged particles generated by the decomposition of the source gas cannot keep up with the vibration, and are almost stationary in the plasma atmosphere. For this reason,
These heavy charged particles do not have the kinetic energy to collide with the source gas and generate new neutral lanocal particles, and the generation of neutral lanocal particles that contribute to film formation is limited to micro The problem is that it proceeds only through direct excitation of waves or decomposition due to collisions with light-mass charged particles such as electrons.

Furthermore, there is also the problem that charged particles such as 5iF3'' ions, which are thought to contribute to film formation, cannot contribute to film formation unless they are generated near the substrate surface, and are not effectively utilized.

[Purpose of the invention]

The present invention overcomes the problems in conventional devices as described above, and provides semiconductor devices, photosensitive devices for electrophotography, line sensors for image input, imaging devices, photovoltaic devices, various other electronic devices, optical devices, etc. The deposited film as an element member used for
The purpose of this is to provide an apparatus that can perform stable and high-speed formation using method D.

That is, the main object of the present invention is to add SiF to one of the raw material gases.
In an apparatus that forms an amorphous silicon film by the microwave CVD method using + gas, etching of the deposited film by fluorine radical particles is suppressed, and a high quality deposited film with low defect density in the film is constantly and stably produced. The object of the present invention is to provide a deposited film forming apparatus that can form a film at high speed.

Another object of the present invention is to make heavy charged particles movable and consume them on the substrate surface, thereby promoting the generation of new charged particles and improving the degree of ionization of plasma. An object of the present invention is to provide a deposited film forming device that can increase the amount of neutral Lanocal particles that mainly contribute to film formation and further improve the deposition rate by promoting decomposition reactions caused by collisions of raw material gases. .

[Structure of the invention]

The present invention provides an apparatus for forming a deposited film by a microwave plasma CVD method that can achieve the above-mentioned objects.

In order to overcome the above-mentioned problems in conventional devices, the inventor of the present invention continued his intensive research and discovered that in order to suppress the etching of an amorphous silicon film caused by fluorine radical particles, it is necessary to It was found that it is necessary to reduce the concentration of

By causing the fluorine radical particles flying to the surface of the amorphous silicon film to react with the hydrogen positive ion particles in the space mid-flight, the amount of fluorine radical particles reaching the surface of the amorphous silicon film is reduced, and the amorphous silicon film is actively It has been found that by supplying hydrogen ions to the surface, it is also possible to cause fluorine radical particles that have reached the surface to react so that they do not contribute to etching of the film.

Further research revealed that by applying a negative DC voltage to the substrate, glass ions such as H2+ are attracted to the substrate surface in a cubic manner, promoting the generation of new charged particles and reducing the degree of ionization of the plasma. We found that it is possible to improve the

Generally, when an electrically insulated substrate is placed in a microwave plasma atmosphere, the substrate has a negative potential called a floating potential with respect to the plasma due to the mass difference between electrons and ions, and its surface There is a plasma interface nearby that prevents charged particles with negative potential, such as negative ion particles and electrons, from entering.
Although it is known to have a sheath region, the size of the floating potential and the width of the ion sheath take values that are uniquely determined depending on the plasma state, so it is difficult to arbitrarily control the size.

In order to improve this point, the present inventor applied a negative DC voltage to the substrate to arbitrarily control the movement of charged particles in the plasma, and at the same time, the amount of positive ion particles such as H2+ reaching the surface of the substrate By controlling the a
It was found that -8i (H,X) film can be formed.

That is, by forming an electric field, heavy charged particles that are almost stationary in the plasma are moved toward the substrate and the wall of the reaction vessel, and stationary particles that do not contribute to the collision-decomposition reaction of the source gas in the plasma are removed. At the same time, it contributes to the decomposition reaction of the raw material gas by imparting kinetic energy to these heavy mono-charged particles, and a
It has been found that it is possible to increase the amount of neutral Lanocal particles that mainly contribute to -3i(H,X) film formation.

It has also been found that etching of the a-3i (H,

Furthermore, by controlling the magnitude of the applied voltage, the amount of H2+ ions reaching the substrate surface can be controlled, and the amount of hydrogen atoms contained in the deposited film can be controlled, thereby increasing the electrical potential of the deposited film. It was also found that the characteristics could be controlled.

The deposited film forming apparatus by the microwave plasma CVD method of the present invention has been completed based on the above-mentioned knowledge, and includes a reaction vessel equipped with a reaction chamber, a means for generating plasma by microwaves, and a substrate or a substrate. A voltage applying means for applying a bias voltage to the holding body.

In the device of the present invention, the substrate has a negative potential and an ion sheath is formed at the boundary between the substrate surface and the microwave plasma, so heavy charged particles can move and neutral radical particles As the production amount increases, positive hydrogen ions are actively supplied to the surface of the substrate, causing the positive hydrogen ions to react with the fluorine compound particles, thereby consuming the fluorine compound particles and losing their etching ability. It is possible to prevent the phenomenon that the deposited film is etched by the compound particles, and to solve the problem of a decrease in the formation rate of the deposited film and a decrease in film quality due to etching.

Further, in the apparatus of the present invention, by controlling the applied DC voltage, the amount of hydrogen ions reaching the substrate surface can be controlled, and the amount of hydrogen atoms contained in the deposited film can be adjusted.

The raw material gas used to form the deposited film by the apparatus of the present invention may be of the kind that can be excited by microwave energy and chemically interact with it to form the desired deposited film on the substrate surface. Any of these can be used; however, when forming an amorphous silicon film, a furan-based gas in which hydrogen is bonded to silicon, a silicon halide gas in which halogen is bonded to silicon, and Hydrogen gas or the like can be used.

Among these, it is preferable to use a mixture of fluorine gas such as 3iB4, hydrogen gas, and fluorine compound gas such as silicon tetrafluoride (S IF 4). By mixing and using a fluorine compound gas such as SiF4, the formation of a polymeric film is reduced, and a-3i (H,
X) Fluorine atoms are contained in the film, dangling bonds are compensated, and a stable, high-quality deposited film can be formed.

Further, these raw material gases may be used after being diluted with an inert gas such as He or Ar. Furthermore, a-8i
(H,X) film contains 1 p-type impurity element or n-type impurity element.
- It is possible to introduce a raw material gas containing these impurity elements as a constituent into the reaction space alone or in a mixture with the aforementioned raw material gas and/or diluting gas. can.

In the apparatus of the present invention, a plasma is formed in the reaction chamber,
The microwave used to excite the raw material gas mentioned above is one in which microwaves from a microwave power source are radiated into the reaction chamber via a three-pillar matching box, a rectangular waveguide, an isolator, etc. Preferably, microwaves with a frequency of 500 MHz to 300 GHz, more preferably 2.45 GHz are used.

In the device of the present invention, the substrate may be made of an electrically conductive material such as a metal, or an electrically insulating material such as glass or ceramics, and its shape may be a sheet-like material, or It may be cylindrical. When the base is made of a conductive material, a DC power source is electrically connected to the base to apply a negative DC voltage.

In addition, if the base is made of an electrically insulating material, the base holder that holds the base is made of a conductive material,
Similar actions and effects can be obtained by similarly applying a negative DC voltage to the substrate holder.

In addition, the substrate is heated as necessary by a heater built into the substrate holder, and the substrate is heated and maintained at a temperature of 60 to 450°C, preferably 50 to 650°C during the film forming operation. It is desirable that

Furthermore, in forming a deposited film, it is preferable to place the inside of the reaction container of the apparatus of the present invention under reduced pressure conditions, and before introducing the raw material gas, the pressure inside the reaction container is reduced to 5x 10-6T.
orr or less, preferably I
It is desirable to use the X10 Torr level.

Hereinafter, the deposited film forming apparatus using the plasma CVD method of the present invention will be explained in more detail with reference to the embodiments of the drawings, but the deposited film forming apparatus of the present invention is not limited thereto.

FIG. 1 is a schematic cross-sectional view of an optimal example of a deposited film forming apparatus using the plasma CVD method of the present invention.

In the figure, components of the device having the same functions as those of the conventional device described above (shown in FIG. 6) are indicated by the same symbols as in FIG. 3.

In the figure, 1 indicates the entire reaction vessel of the apparatus of the present invention. 2 is
The side wall of the reaction vessel, 21, is the bottom wall of the reaction vessel. 3
is a multi-perforated inner wall that is erected to form a certain gap (gas chamber) with the inner surface of the side wall 2, and has gas communication holes 31, 51... into the reaction chamber A. . The multi-perforated inner wall usually has no perforations at the lower end 6' and the upper end 6'' where the substrate 10 is not present at opposing positions in the reaction chamber A. 2 and bottom wall 2
1 can of course be made into separate members, but usually they are formed integrally.

4 is a dielectric window for introducing microwaves, preferably a window made of alumina (At203) ceramics or quartz.

Reference numeral 5 denotes a waveguide section, which is connected to a microwave power source B via a three-pillar matching box, a rectangular waveguide, and an isolator (not shown), and transmits microwaves 61 to a reaction vessel via a dielectric window 4. It is something that leads inward.

The reaction chamber A includes the aforementioned side wall 2, bottom wall 21, and dielectric window 4.
It is hermetically sealed. 7 opens into the reaction chamber A from the bottom wall 2 of the reaction vessel 1 at one end, and has a valve means 71 at the other end.
Exhaust pipes are connected to an exhaust system (not shown) through the exhaust pipes, and there are usually four exhaust pipes installed in the circumferential direction, but one exhaust pipe may be installed. Reference numeral 8 denotes a raw material gas supply pipe, one end of which opens into the gas chamber B from the side wall of the reaction vessel 1, and the other end communicates with a raw material gas supply source (not shown) via a valve means 81.

Reference numeral 9 denotes a holding part for the base body 10, and the base body holding part 9 has a built-in heater 11 and is usually cylindrical in shape. A base 10 is installed on the surface of the base holding section. The base body is made of an electrically conductive material or an electrically insulating material, and may be rectangular or cylindrical in shape, and in the case of a rectangular shape, it is arranged in parallel with the surface of the cylindrical holding part.

15 is a DC power supply, which is connected to the conductive substrate 1 through a conductive wire 14.
0 or the conductive substrate holder 9 so that a negative DC voltage can be applied to the substrate 10 or the substrate holder 9. By making the DC power supply 15 a variable power supply, the base 1
0 or the DC voltage applied to the substrate holder 9 can be arbitrarily controlled.

In order to electrically insulate between the substrate 10 and the reaction vessel 1 or between the substrate holder 9 and the reaction vessel, insulation is provided between the support legs 12 attached to the bottom of the substrate holder 9 and the substrate holder. Insulation is provided on the lower wall of the reaction vessel (in Fig. 1, it is the lower wall, but it may be either the soil wall or the side wall) through which the conductor 14 passes. Set up

In the apparatus of the present invention, the reaction vessel and other internal jigs other than the substrate or the substrate holder are electrically grounded. In other words, a structure in which a positive DC voltage is applied can also be used.

mechanically coupling a drive means (not shown) to the support leg 12;
The drive means can rotate during the film forming operation. Alternatively, it is also possible to keep the substrate holder 9 fixed and rotate the reaction vessel 1 about the support legs 12.

16 indicates a plasma interface.

The apparatus according to the embodiment of the present invention shown in FIG. 1 has a structure in which one cylindrical substrate 10 is disposed inside the reaction vessel 1. By doing so, an electric field is formed in the plasma, and the heavy charged particles, which move slowly in the microwave glazma, are made to move sharply and contribute to the reaction, and hydrogen plus ions are generated on the surface of the substrate 6 by the action of the electric field. By supplying a-
It is possible to prevent etching of the 3i (H, Taking this into consideration, the number of the above-mentioned substrates may be plural. For example, it is possible to establish several substrate holding parts 9, 9, etc. coaxially and equally spaced on a circular stator, in which case a plurality of cylindrical substrates can be placed in the reaction chamber A at the same time. By installing the substrate, a deposited film can be formed on each surface of the substrate at once.

FIG. 2 is a schematic diagram showing the film forming process near the substrate surface when using the apparatus of the present invention.

In the figure, the same symbols are used for the same parts as in the diagram (shown in FIG. 4) showing the film forming process near the substrate surface when the conventional apparatus described above is used.

That is, in the figure, 20 is a substrate, 21 is an amorphous silicon film 22 is a neutral radical, 25 is a positive ion particle, and 24
25 is a negative ion particle, 25 is an electron, 27 is a plasma interface, 28 is an ion sheath region, and 29 is an accelerated hydrogen glass ion.

As already mentioned, in the conventional apparatus, the heavy charged particles in the microwave plasma cannot keep up with the high-speed vibrations of the microwaves, and are almost stationary in the plasma.

On the other hand, in the apparatus of the present invention having the above-described configuration, when the base body 10 to which an electrically negative voltage is applied is placed in plasma, the positive ion particles 23 are attracted to the base body 10 by electrical attraction. On the other hand, since the electrons 25, the negative ion particles 24, and the base 20 have a negative potential,
Electrical force acts on the ions, they are stopped at the interface 27 between the surface of the substrate 20 and the plasma, and cannot penetrate into the ion sheath 28, so they cannot reach the surface of the substrate 20.
The direction away from the substrate 20, that is, the side wall 2 of the reaction vessel 1
An electric field acts on the side and it moves.

Charged particles moving under the action of an electric field collide with raw material gas molecules on the way, thereby exciting and decomposing the raw material gas molecules. As a result, new neutral radical particles 22 are generated. The neutral Lanocal particles 22 are not affected by the electric field and reach the substrate surface along the diffusion and exhaust flow, forming a-3i (H
, X) is deposited as a film 21. Fluorine compounds, neutral Lanocal particles and positive ion particles near the base 20
Although an attempt is made to etch the 8i (H, of gas is produced,
Fluorine atoms do not etch the a-3i(H,X) film. In addition, the silicone particles remaining after fluorine is extracted from the fluorosilicon compound particles such as 5iF3+ are a-8i
(H,X) can contribute to film formation.

That is, not only the neutral Lanocal particles but also the positively charged silicon fluoride compound ionic particles a-8i (B,
X) It can contribute to film formation.

In addition, hydrogen plus ion particles that were not consumed in the reaction with fluorine atoms are contained in the a-8i (H,
It acts to reduce the defect density of the film. However, the excessively supplied hydrogen glass ion particles, on the contrary, a −
This causes crystal lattice terminations in the S l (Hr x ) film and increases the defect density. Therefore, the amount of hydrogen ions 29 reaching the substrate 20 needs to be optimally adjustable.

In the apparatus according to the embodiment of the present invention, by adjusting the magnitude of the negative DC voltage mentioned above, the amount of hydrogen plus ions 2o supplied to the substrate 6 can be adjusted, and the amount of the deposited a-8i (
H, X) The hydrogen content in the film can be adjusted as desired.

Next, an example of forming a deposited film by operating the apparatus of the present invention will be described.

In this example, one substrate holder 9 shown in FIG. 1 is installed coaxially with the reaction vessel, and a driving device (not shown) is installed.
An apparatus was used in which the substrate 1o was an At plate cylinder, and the insulation made of alumina ceramics was electrically insulated by the stones. The raw material gases include SiH4 gas (70sccm), H2 gas (30secm), and SiF4 gas (10secm).
) was used.

First, the pulp 81 is closed, the pulp 71 is opened, and the reaction chamber A is opened.
The inside was degassed, and the system pressure was adjusted to 1×1 Q=Torr or less. Next, the heater 11 was energized to bring the temperature of the substrate 10 to 2[)0° C., and a DC voltage of -20 V was applied to the substrate. There, the pulp 81 is opened and the raw material gas is supplied through the raw material gas supply pipe 8 to a system pressure of 1x102T.
At the same time, the microwave power source 6 was energized to radiate microwaves with a frequency of 2.45 GHz through the conductive window 4. Next, the supply and exhaust of raw material gases were adjusted to the pulps 81 and 71 to keep the system pressure constant, and while the substrate 10 was rotated, open film formation was performed at predetermined times. After that, heating and rotation of the substrate, gas supply, microwave irradiation, etc. are stopped, and the substrate is allowed to cool.
The substrate was carried out. The same operation was performed on nine other new substrates to obtain substrates on which a total of 10 deposited films were formed.

When we tested the deposited films on the surfaces of the 10 substrates obtained, we found that all of them had an extremely dense composition, were homogeneous throughout, and had a uniform thickness. It had extremely excellent optical and photoconductive properties.

[Summary of effects of the invention]

The device of the present invention applies a negative DC voltage to a conductive substrate to form an electric field, thereby causing heavy charged particles in microwave plasma to contribute to the reaction and increasing the amount of neutral radical particles generated. At the same time, hydrogen plus ions are collected on the surface of the substrate to prevent etching of the a-8i (H,X) film, and the hydrogen content in the a-3i (H,X) film is controlled. , has effective performance for high-speed deposition of high-quality a-3i° (E,X) films.

[Brief explanation of drawings]

FIG. 1 is a schematic cross-sectional view of an embodiment device of the present invention, and FIG.
The figure is a schematic diagram showing the film forming process in the vicinity of the substrate surface when using the apparatus of the present invention. FIG. 6 is a schematic cross-sectional view showing an example of a deposition film forming apparatus using the conventional microwave plasma CVD method, and FIG. 4 shows the film forming process near the substrate surface when the conventional apparatus is used. It is a schematic diagram. In the figure,

Claims (1)

[Claims] The invention is characterized by comprising: a reaction vessel equipped with a reaction chamber; means for generating plasma using microwaves; and voltage application means for applying a bias voltage to a substrate or a substrate holder. microwave plasma CVD
Deposited film forming device using method.