JPS62196377A - Device for forming deposited film by plasma chemical vapor deposition method - Google Patents

Abstract

PURPOSE:To enhance the various characteristics, film forming velocity, reproducibility and productivity of a formed film and to uniformize and homogenize quality of the film by providing an electric discharge controlling means to at least either one part of an upper part or a lower part of a cylindrical base body provided in a reaction space. CONSTITUTION:A cylindrical base body 7 is provided in a reaction space which is closed and formed by a top wall 3, a surrounding wall 2 combined with a cathode and a bottom wall 4 and rotated by a rotary driving means 8. Then a gaseous raw material for forming a deposited film which is fed through a gas introducing pipe 9 is introduced into the above- mentioned reaction space via a gas discharge port 9a and exhausted through an exhaust pipe 11 and thereby the reaction space is regulated to the prescribed degree of vacuum. Voltage is impressed between the above-mentioned surrounding wall 2 and the base body 7 by a voltage impressing means 13 to cause electric discharge and the above-mentioned gaseous raw material is energized, seeded and allowed to react and the deposited film is formed on the base body 7. In the above-mentioned device, an electric discharge controlling plate 14 provided with a voltage impressing means 16 is provided to the upper part of the base body 7 so that it can be vertically transferred in the direction shown in the arrows by a vertical driving means 15. Thereby the plasma discharge space is regulated in accordance with the fluctuation of the film forming conditions and the formation of the deposited film in the plasma chemical vapor deposition method is stabilized.

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, and an imaging device. , plasma CV, which is optimal for forming non-monocrystalline deposited films such as amorphous or polycrystalline for use in photovoltaic devices, etc.
Regarding D device.

[Description of prior art]

Conventionally, semiconductor devices, photosensitive devices for electrophotography,
For example, an amorphous material containing silicon (hereinafter simply referred to as "a-8iJ") can be used as an element member used for an image input line sensor, an imaging device, a photovoltaic element, etc.
Films or amorphous (hereinafter simply referred to as [a-5iHJ) films containing silicon hydride have been proposed, and some of them have been put into practical use. And such a
-8i film and a-5iH film as well as a-5i film and a
Several methods have been proposed for forming -8iH films, etc., and devices for implementing them, including vacuum evaporation, ion blating, so-called thermal CVD, plasma CVD, and photo-CVD, among which plasma CVD The method has been put into practical use as the optimal one and is widely used in general.

By the way, the plasma CVD method utilizes direct current, high frequency, or microwave energy to excitedly species (radicalize) the deposited film-forming gas near the substrate surface to cause chemical interaction, thereby causing a chemical interaction to occur on the substrate surface. The method is to deposit a film, and various devices for this purpose have been proposed.

FIG. 2 is a schematic cross-sectional view schematically showing a typical example of a deposited film forming apparatus using the conventional plasma CVD method. In the figure, 1 indicates the entire reaction vessel, and 2 also serves as the side wall of the reaction vessel. 3 is the upper wall of the reaction vessel, and 4 is the bottom wall of the reaction vessel. The cathode electrode 2, top wall 3, and bottom wall 4 are insulated by an upper flange 5 and a lower insulator 6, respectively.

Reference numeral 7 denotes a cylindrical substrate placed within the reaction vessel, and the cylindrical substrate 7 is grounded and serves as an anode electrode.

A heater (not shown) for heating the substrate is installed inside the cylindrical substrate 7, and is used to heat the substrate to a set temperature before film formation, maintain the substrate at the set temperature during film formation, Alternatively, it is used to subject the substrate to a 7-dil treatment after film formation. Further, the cylindrical substrate 7 is connected to a rotation drive means 8 via a shaft, and is rotated during film formation.

Reference numeral 9 denotes a raw material gas introduction pipe for forming a deposited film, which is provided with a large number of gas release holes 9a for releasing the raw material gas toward the substrate surface.The other end of the raw material gas introduction pipe 9 is connected to a pulp It communicates with a source gas supply means (not shown) for forming a deposited film via 10.

Reference numeral 11 denotes an exhaust pipe for evacuating the inside of the reaction vessel, and it communicates with an evacuation device (not shown) via an exhaust valve 12.

13 is a means for applying voltage to the cathode electrode 2;

The operation of such a deposited film forming apparatus using the conventional plasma CVD method is performed as follows.

That is, the gas in the reaction container is evacuated through the exhaust pipe 10, and the cylindrical substrate 7 is heated and maintained at a predetermined temperature.
Further, it is rotated by the rotation drive means 8. Next, in the case of forming, for example, an a-8iH deposited film, a raw material gas such as silane is introduced into the reaction vessel via the raw material gas introduction pipe 9, and the raw material gas is released from the gas introduction pipe. It is released from the hole 9a toward the substrate surface. At the same time, a high frequency, for example, is applied between the cathode electrode 2 and the substrate (anode electrode) 7 from the voltage application means 13 to generate plasma discharge. In this way, the raw material gas in the reaction vessel is excited and becomes excited species, and radical particles such as Si", SiH" (the inside represents the excited state), electrons, ionic particles, etc. are generated, and these particles react with each other. a-5 on the surface of the cylindrical base
A deposited film of iH is formed.

The above-mentioned deposition film apparatus using the conventional plasma CVD method is
Although it is generally widely used as the optimal one, it has some problems as follows.

That is, since the distance between the cathode electrode and the cylindrical substrate is often fixed, the discharge space for the generated plasma depends on the film forming conditions, such as the flow rate of the raw material gas for forming the deposited film, and the pressure in the film forming space. , discharge power, substrate temperature, etc. Therefore, when various film forming conditions are changed for each layer to be formed, such as when manufacturing an element member with a multilayer structure, the discharge space of the plasma that is formed changes, and over time. As a result, the thickness and quality of the film formed on the upper and lower parts of the cylindrical substrate become uneven. Such unevenness in film thickness and film quality is thought to be due to differences in the amount of various radicals generated near the surface of the cylindrical substrate and differences in doping efficiency of doping agents, but it is also possible that the unevenness in the upper and lower parts of the cylindrical substrate is uniform. When trying to form a deposited layer with different film thicknesses and film qualities, the various types of film formation methods mentioned above are naturally limited, and as a result, it is difficult to continuously deposit various films with a wide range of characteristics in the same equipment. It would be extremely difficult to form such a structure.

Conventionally, as a method to solve these problems, dummy drums are placed at both the upper and lower ends of a cylindrical substrate, and a deposited film is formed on the surface of the cylindrical substrate, and at the same time, a deposited film is also formed on the surface of the dummy drum. Methods such as forcing are used. However, in order to reuse the dummy drum, not only is extra work required such as removing the deposited film formed on the dummy drum, but the size of the cylindrical substrate to be used is naturally limited. I end up.

For these reasons, although the plasma CVD method is considered to be the optimal method, it is difficult to mass produce the desired deposited film.
There are problems such as requiring a large investment in equipment and making the manufactured product considerably expensive.

In addition, as the various devices mentioned above have become more diverse, there is a social demand for forming deposited films with a wide variety of characteristics as element components, and in some cases, forming deposited layers with a large area. There is a strong desire to develop an apparatus that can regularly mass-produce deposited films that meet these requirements.

[Purpose of the invention]

The present invention solves the above-mentioned problems and satisfies the above-mentioned requirements regarding conventional apparatuses for forming deposited films used in optical power devices, semiconductor devices, line sensors for image input, imaging devices, photosensitive devices for electrophotography, etc. The purpose is to satisfy the following.

That is, the main object of the present invention is to have electrical, optical, and photoconductive properties that are virtually always stable regardless of the usage environment, to have excellent light fatigue resistance, and to be suitable for repeated use. Excellent durability, with no deterioration phenomenon even under
It is an object of the present invention to provide a deposited film mass production apparatus using a plasma CVD method for mass producing a uniform, homogeneous and improved deposited film that has moisture resistance and does not cause the problem of residual potential.

Another object of the present invention is to improve film productivity, particularly to enable mass production, while aiming to improve the properties, film formation speed, and reproducibility of the film formed, and to make the film quality uniform and homogeneous. ,
At the same time, it is an object of the present invention to provide an apparatus for mass-producing deposited films using a plasma CVD method, which makes it possible to increase the area of films.

[Structure and effect of the invention]

The inventors of the present invention have conducted extensive research to overcome the aforementioned problems with conventional plasma CVD deposited film forming apparatuses and to achieve the above objectives. The present invention has been completed based on the knowledge that the above-mentioned problems can be solved and the above-mentioned objects can be achieved by providing a discharge control plate at one or both ends.

That is, the deposited film forming apparatus using the plasma CVD method of the present invention includes a reaction space formed in a sealed manner with an upper wall, a peripheral wall, and a bottom wall, means for installing a cylindrical substrate in the reaction space, and the reaction space. means for introducing a source gas for forming a deposited film into the
A deposited film forming apparatus using a plasma CVD method, comprising a discharge chamber energy applying means for exciting the raw material gas to form excited species, and a means for exhausting the inside of the reaction space, the apparatus comprising: The feature is that a discharge control means is provided at least either above or below, and preferably further includes means for moving the discharge control means up and down and/or.
Alternatively, the present invention relates to a deposited film forming apparatus using a plasma CVD method, which is provided with means for applying a voltage to the discharge control means.

The deposited film forming apparatus using the plasma CVD method of the present invention having the above configuration controls the discharge space of the generated plasma by the discharge control means, that is, the discharge control plate provided at least on either the upper or lower side of the cylindrical substrate. Since this can be controlled, it is possible to prevent unevenness in the film thickness, film quality, or characteristics of the deposited film formed on the upper and lower parts of the cylindrical substrate.

That is, when forming a deposited film using the apparatus of the present invention, various film forming conditions are set in order to form a deposited film having desired film thickness, film quality, and properties, and under the film forming conditions, moving the position of the discharge control plate up and down so that the most preferable plasma discharge space is formed;
Alternatively, by further applying a voltage to the discharge control plate, the state of the discharge space of the formed plasma can be controlled.

When forming a deposited film using the apparatus of the present invention, it is possible to prevent unevenness of the deposited film on the upper and lower parts of the cylindrical substrate as described above, so a conventional dummy drum is used. There is no need to
A uniform and homogeneous deposited film can be formed over the entire surface even on a large cylindrical substrate. In addition, multiple cylindrical substrates are installed (
Even when deposited in multiple stages, it is possible to form a deposited film with no difference in film quality and thickness between the upper and lower parts. Furthermore,
It becomes possible to efficiently mass-produce various deposited films having a wide range of characteristics using the same equipment, and it becomes possible to provide low-cost products.

The raw material gas used to form the deposited film by the apparatus of the present invention is one that is excited and speciated by high frequency or microwave energy, and undergoes chemical interaction to form the desired deposited film on the substrate surface. For example, in the case of forming an a-Si film, silane in which hydrogen, halogen, or hydrocarbon, etc. are bonded to silicon may be used. It is possible to use gaseous materials exclusively for silanes and halogenated silanes, or gasified materials that can be easily gasified.

These raw material gases may be used alone or in combination.
You may use more than one species in combination. In addition, these raw material gases are
It may be used after being diluted with an inert gas such as He or Ar. Furthermore, the a-9i film can be doped with a pg impurity element or an n-type impurity element, and a source gas containing these impurity elements as a constituent may be used alone or with the aforementioned source gas or/and It can be mixed with a diluent gas and introduced into the reaction space.

The substrate may be conductive, semiconductive, or electrically insulating, and specific examples thereof include metal, ceramics, glass, and the like. The substrate temperature during the film forming operation is not particularly limited, but is generally in the range of 30 to 450°C, preferably 50 to 350°C.

Further, in forming a deposited film, it is preferable to place the inside of the reaction space of the apparatus of the present invention under reduced pressure conditions, but of course it may be placed under normal pressure conditions, and depending on the case, it may also be placed under pressurized conditions. When forming a deposited film under reduced pressure, the pressure in the reaction space is reduced to 5X10'''' before introducing the raw material gas.
Torr or less, preferably I x 10” Torr
When the raw material gas is introduced, the pressure in the reaction space is 1X IF” to I Torr, preferably 5×
It is desirable to set it as 10''1 to I Torr.

〔Example〕

Hereinafter, embodiments of the apparatus of the present invention will be illustrated and the present invention will be explained in detail using the drawings, but the present invention is not limited to the embodiments.

FIG. 1 is a schematic cross-sectional view schematically showing a typical example of the device of the present invention.

In the figure, the same reference numerals as in the above-mentioned FIG. That is, 1 is a reaction vessel, 2 is a cathode electrode, 3 is an upper wall, 4 is a bottom wall, 5 is an upper insulator, 6 is a lower insulator, 7 is a cylindrical base, 8 is a rotational drive means, 9 is a gas introduction pipe, 9a is a gas discharge hole, 10 is pulp, 11 is an exhaust pipe, 1
Reference numeral 2 indicates an exhaust pulp, and reference numeral 13 indicates a voltage application means.

14 is an eccentric control plate installed above the cylindrical base, and is connected to the vertical drive means 15 via a shaft,
The distance between the upper end of the cylindrical base 1 and the discharge control plate 14 can be freely selected. Further, 16 is a means for applying a voltage to the discharge control board. The voltage applying means 16 and the discharge control board 14 are connected through a switch 17, and by switching the switch 17, a voltage can be applied to the discharge control board or the discharge control board can be grounded. They are doing everything they can. The discharge control board may be conductive, or may be made of a conductive material coated with an absolute material, or may be made of an insulating material such as Teflon or ceramic. . Further, its shape may be a flat plate or a mesh plate.

In this example, a disk manufactured by A was used. 18 is an insulator placed at the top.

In this embodiment, a discharge control plate is provided above the circular base, but a similar discharge control plate may be provided below the circular base.

Song A] Using the apparatus shown in FIG. 1, an electrophotographic light-receiving member was manufactured in the following manner.

In this example, a cylindrical Al support (diameter 80zi
As a), a sample was used which was divided into three parts: an upper part (120° C.m), a middle part (357 m), and a lower part (123 mg).

First, all the main valves of the raw material gas supply means (not shown) for deposited film formation are closed, valves 10 and 12 are opened, and the exhaust device (
(not shown), the pressure inside the reaction vessel was reduced to 10-' Torr. At the same time, the Al support 106 is heated to 250°C using a substrate heating heater (not shown).
The temperature was kept constant at 50'C. Further, the rotation drive means 8 was driven to rotate the Al support.

First, the raw material gas for forming the heavy injection blocking layer is introduced from the gas introduction pipe 9 to these places, and the inside of the reaction vessel is set to 0.2 T.
Valve 12 was adjusted to V4 so that it was orr. When the inside of the reaction vessel stabilized at 0.2 Torr, high frequency power (13.56MH!) 15 was applied from the voltage application means 14.
A glow discharge was generated between the cathode electrode 2 and the Al support 7 by applying 0 W to form a charge injection blocking layer made of a-Si:H:B. At this time, the discharge control board 15 is grounded, and the distance from the upper end of the Al support is 60m5.
And so.

Next, a process was carried out in the same manner as described above, except that the composition of the raw material gas was changed to one for forming the photosensitive layer, the applied power was aoow, and the distance between the discharge control plate and the upper end of the Al support was 120 m. A photosensitive layer consisting of -9i:H was formed.

Finally, a- 8i: A surface layer made of C(H) was formed.

When the flow rate or flow rate ratio of the raw material gas for forming each layer is lowered, and the formation of each layer is completed, the discharge, heating of the substrate, and rotational driving are stopped, and the Al support is allowed to cool, and the Al support is removed from the reaction vessel. I took it out.

Two of each of the upper, middle and lower Al supports are provided,
The j3 thickness, dark potential, and dark potential per 1 μm of each layer formed were measured. The results are shown in Table 2 below.

As is clear from this table, there is almost no difference in the thickness of the charge injection blocking layer, photosensitive layer, and surface layer among the upper Al support, central Al support, and lower Al support, and the film quality is also There was almost no vertical unevenness (difference in dark potential per 1 μm: 0.5 V/μm), and there was virtually no vertical unevenness in dark potential. (Within SV) The dark potential is measured using Canon's digital copier NP9.
030, the dark area surface potential was measured at the position of the imager when the corona voltage of −order charging was +7.5 kV.

Comparative Example The same tea juice as in Example 1 was used except that the device shown in FIG. 2, that is, the conventional device without a discharge control board was used.
A charge injection blocking layer, a photosensitive layer and a surface layer were formed on an Al support.

The obtained light-receiving member for electrophotography was evaluated in the same manner as in the example. The results are shown in Table 3 below.

As is clear from Table 3, the thickness of the charge injection blocking layer was uniform, but the photosensitive layer and surface layer were thicker at the top.

Regarding the film quality, the dark potential per 1 μm was higher in the lower part, and although the film quality was good, there was vertical unevenness in dark voltage.

Example 2 The distance between the discharge control plate 15 and the upper end of the AI support is 120
An electrophotographic light-receiving member was formed in the same manner as in Example 1 except that fi was fixed.

The thickness of each layer was as shown in Table 4 below.

Next, when forming a charge injection blocking layer, a high frequency 2
0W was applied. The thickness of the charge injection blocking layer in this case was 5 μm in all of the upper, central and lower supports.

As is clear from this, it is possible to effectively prevent vertical film thickness unevenness by simply applying high frequency waves or the like to the discharge control plate without moving the discharge control plate up and down.

[Brief explanation of drawings]

FIG. 1 is a schematic cross-sectional view schematically showing a typical example of the apparatus of the present invention, and FIG. 2 is a cross-sectional view schematically showing a typical example of a deposited film forming apparatus using the conventional plasma CVO method. This is a schematic diagram. Regarding Figure 1.2, 1... Reaction vessel, 2... Surrounding wall that also serves as a cathode electrode, 3... Top wall, 4... Bottom wall, 5... Upper tsuba, 6
. . . Lower insulator, 7. Cylindrical support, 8. Rotation drive means, 9. Gas introduction pipe, 9a. Gas discharge port.
DESCRIPTION OF SYMBOLS 10... Valve, 11... Exhaust pipe, 12... Exhaust valve, 13° 16... 4-way applying means, 14... Discharge control board, 15... Vertical drive means, 17...・Switch, 18...Insulator.

Claims (3)

[Claims] (1) a reaction space formed in a sealed manner by a top wall, a peripheral wall, and a bottom wall, and means for installing a cylindrical substrate within the reaction space;
A plasma CVD method comprising means for introducing a source gas for forming a deposited film into the reaction space, means for applying discharge energy to excite the source gas to form excited species, and means for exhausting the inside of the reaction space. A deposited film forming apparatus using a plasma CVD method, characterized in that a discharge control means is provided above or below the cylindrical substrate. (2) A deposited film forming apparatus using a plasma CVD method according to claim (1), wherein the discharge control means is a discharge control plate that moves up and down. (3) A deposited film forming apparatus using a plasma CVD method according to claim (1), further comprising means for applying a voltage to the discharge control means.