JPH08253865A - Formation of deposited film and deposited film forming device - Google Patents

Abstract

PURPOSE: To highly efficiently utilize a raw gas and to form a deposited film uniform in characteristic in a device for forming a functional deposited film on plural cylindrical substrates by plasma CVD by arranging the substrates and electrodes surrounding the substrates at specified positions and intervals. CONSTITUTION: Many cylindrical substrates 101 of a conductive metal such as Al and Cr are arranged in a reaction vessel 100 in the form of a lattice, and electrodes 102 of stainless steel, etc., are arranged orderly and equidistantly from all the substrates 101. The vessel 100 is evacuated from an exhaust port 105, the substrate 101 is heated to 20-50 deg.C, and a mixture of the raw gas such as SiH4 and inert gas such as Ar is supplied into the vessel to <=100mTorr. A high-frequency voltage of 50-450MHz is impressed on the electrode 102 from a power source 103 through a matching box 104 to produce plasma, hence the raw gas is decomposed, and a uniform amorphous silicon film is deposited on the substrate 101 surface.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a deposited film on a cylindrical substrate,
In particular, a functional deposited film, particularly a deposited film forming method and a deposited film forming apparatus by plasma CVD for forming an amorphous semiconductor used for a semiconductor device, an electrophotographic light receiving member, an image input line sensor, an imaging device, a photovoltaic device, and the like. Regarding

[0002]

2. Description of the Related Art Amorphous silicon, such as hydrogen and / or hydrogen, is used as an element member for semiconductor devices, electrophotographic light receiving members, image input line sensors, image pickup devices, photovoltaic devices, and other various electronic elements. Deposited films for semiconductors and the like, which are composed of an amorphous material such as halogen-compensated amorphous silicon, have been proposed, and some of them have been put to practical use.

However, some of these devices are
Some of them have problems in terms of cost in their production. For example, when manufacturing a photoreceptive member for electrophotography, a relatively thick film thickness is required, so that the deposition time of the film is necessarily long and the manufacturing cost is high. From this background, while improving productivity,
There is a demand for a deposited film forming method and a deposited film forming apparatus capable of improving efficiency in various respects.

[0004] In order to improve such problems,
Japanese Unexamined Patent Publication (Kokai) No. 60-186849 discloses a method for forming a deposited film by a plasma CVD method using microwaves. The publication discloses that an inner chamber is formed by arranging a plurality of cylindrical members in a deposition chamber, and a raw material gas is introduced into the chamber to improve gas utilization efficiency and productivity. A method of forming a deposited film is disclosed.

Further, Japanese Patent Laid-Open No. 3-219081 discloses a method of forming a deposited film of higher quality by applying a DC electric field to the plasma space and controlling the plasma potential.

[0006]

However, even in the above-described method for forming a deposited film, microwaves are introduced from above and below the inner chamber (both ends of the cylindrical conductive substrate), so that the cylindrical conductive substrate is not exposed. It was difficult to make the characteristics unevenness in the direction of the generatrix and the characteristics of the deposited film formed between a plurality of cylindrical conductive substrates formed at the same time. Such variation in characteristics affects the yield, and even if the production efficiency is improved, it has been a factor of increasing the cost of the device manufactured as a result.

Further, in the conventional method and apparatus for forming a deposited film by the microwave plasma CVD method, the cylindrical substrate is arranged so as to surround the plasma, and the cylindrical substrate is rotated to form the deposited film over the entire surface of the cylindrical substrate. Since it is formed, the substantial deposition rate is reduced.

In the microwave plasma CVD method,
When a DC electric field was not applied, the surface mobility of the active species reaching the substrate was small, dangling bonds on the outermost surface of the film growth could not be sufficiently compensated, and it was difficult to realize good film characteristics. Therefore, a direct current electric field is applied to increase the surface mobility of active species on the film surface by applying energy to the film surface by ions, and to improve the film quality by compensating for more dangling bonds. Means were used. However, this method causes a new problem of an abnormal growth of the film, which is contrary to the film characteristics, and causes a reduction in the image defect level.

On the other hand, in the high frequency plasma CVD method, the surface mobility of the active species reaching the substrate is higher than that in the microwave plasma CVD method, and the dangling bond is sufficiently compensated without applying a DC electric field, which is excellent. It is considered that excellent film characteristics can be obtained. Therefore, there is no damage to the film by the ions, and no abnormal growth of the film is observed. What is currently inferred as the cause of the large surface mobility of the active species that has reached the substrate in the high frequency plasma CVD method relates to the decomposability of the source gas. High frequency plasma C
In the VD method, generated plasma characteristics (mainly electron temperature and electron density) are significantly different from those in the microwave plasma CVD method. As a result, it is speculated that active species such as SiH ₃ having a large surface mobility on the film growth surface are mainly generated. Due to such a phenomenon, a high-quality film is formed in the high-frequency plasma CVD method regardless of whether or not an electric field is applied.

However, in the conventional RF plasma CVD method using 13.56 MHz, a silicon-based by-product called polysilane is simultaneously generated when the deposited film is formed, and the utilization efficiency of the source gas and the process of removing the same are achieved. As a result, the cost was raised. Further, as shown in the conventional apparatus of FIG. 6, in the apparatus having a structure in which a plurality of cylindrical substrates are installed by using parallel plates as electrodes, there is a problem such as variation among lots due to uneven discharge in addition to the above problems. It was

Furthermore, in recent years, the performance of copying machines has been improved, and with the spread of digital machines and color machines, it has become necessary for the photoreceptor to have higher image quality and higher quality than ever before. Came.

The present invention solves the above problems,
An object of the present invention is to provide a deposited film forming method and a deposited film forming apparatus which are excellent in raw material gas utilization efficiency, productivity and property uniformity.

Another object of the present invention is to deposit a deposited film on a cylindrical conductive substrate, especially a functional deposited film, especially a semiconductor device, a photoreceptive member for electrophotography, a line sensor for image input, an image pickup device, and a photovoltaic. A plasma CVD apparatus for forming an amorphous semiconductor used for devices and the like,
An object of the present invention is to provide a deposited film forming apparatus and a deposited film forming method that can stably supply a good quality deposited film having particularly excellent image properties at low cost.

[0014]

According to the present invention, a raw material gas introduction means, a plurality of cylindrical substrates and a plurality of electrodes for applying high-frequency power are installed in a depressurizable reaction vessel, and the raw material gas is introduced under reduced pressure. In a deposited film forming method of applying high frequency power to the plurality of electrodes in a reaction vessel to decompose the raw material gas to form a deposited film on the cylindrical substrate, all electrodes surrounding one cylindrical substrate are Provided is a deposited film forming method, which is characterized in that deposition is performed by arranging the substrate at an equal distance from a cylindrical substrate.

Furthermore, the present invention provides a reaction vessel capable of reducing pressure,
A raw material gas introduction means, a plurality of electrodes for decomposing the raw material gas in the reaction vessel by application of high-frequency power, and a plurality of cylindrical substrates on the surface of which deposited films are formed by decomposition products of the raw material gas are installed. In the deposited film forming apparatus, there is provided a deposited film forming apparatus, wherein all electrodes surrounding one cylindrical substrate are arranged at an equal distance from the cylindrical substrate.

The present inventors have set the pressure inside the reaction vessel to 100
It has been found that by controlling to mTorr or less, a desired deposited film can be formed even in a mass production apparatus having the configuration of the present invention, which is suitable.

In the present invention, the pressure inside the reaction vessel in which a plurality of cylindrical substrates and a plurality of high frequency electrodes are arranged is 100 m.
A high frequency plasma CV using a conventional frequency of 13.56 MHz is formed by forming a deposited film below Torr.
As compared with the D method and the microwave plasma CVD method using the frequency of 2.45 GHz, a further excellent deposited film can be obtained.

Further, as described above, in the conventional deposited film forming apparatus using the microwave plasma CVD method, the cylindrical substrate is arranged so as to surround the plasma, and the cylindrical substrate is rotated to cover the entire surface of the cylindrical substrate. Since the deposited film is formed, the deposition rate is substantially reduced, but the deposited film forming apparatus of the present invention forms the deposited film while the entire circumferences of the plurality of cylindrical substrates are in contact with plasma at the same time. The deposition rate is substantially higher than that of the conventional device configuration, and it is possible to industrially improve mass productivity.

[0019]

In one embodiment of the present invention, the electrodes for introducing the high frequency wave into the reaction vessel are arranged in a grid, and the cylindrical substrate is installed in the center of one of the grids. That is, when viewed from one cylindrical substrate, it is close to it,
That is, it is preferable that all of the plurality of electrodes surrounding the substrate have the same positional relationship.

The material of the electrode may be basically any conductive material, for example, stainless steel, Al, Cr, Mo, Au, In, Nb, Ni, T.
e, V, Ti, Pt, Pb, Fe and other metals, their alloys, or those provided with ceramic spraying or a cover on the surface of these metals or alloys to improve the adhesion of the deposited film used.

In the present invention, the frequency of the high frequency power introduced into the reaction vessel is preferably 50 to 450 MHz. According to the experiments by the present inventors, the frequency is 50 MHz.
If it is less than the above, it may be difficult to maintain the discharge depending on conditions when the spread of the discharge is obtained. Further, if the pressure in the reaction vessel is increased in order to maintain the discharge, at the same time as the discharge is deviated, a silicon-based by-product called polysilane is generated in the reaction vessel and the productivity is reduced. Also 450M
If it is higher than Hz, the transmission characteristic of the high frequency power deteriorates, and if the high frequency power is considerably smaller than the power that completely decomposes the raw material gas (hereinafter referred to as the raw material gas decomposition saturated power),
The plasma may become unstable.

As a source gas for the deposited film used in the present invention
Is, for example, silane (SiH_Four), Disilane (Si₂H₆)
Amorphous silicon forming raw material gas, such as germane (G
eH _Four) Etc. functional material for forming a deposited film, or
These mixed gases are mentioned.

Examples of the diluent gas include hydrogen (H ₂ ), helium (He), argon (Ar) and the like. Also,
Gases containing nitrogen such as nitrogen (N ₂ ) and ammonia (NH ₃ ), oxygen (O ₂ ), nitric oxide (NO), dinitrogen oxide ( Gas containing oxygen such as N ₂ O), methane (CH ₄ ),
Hydrocarbons such as ethane (C ₂ H ₆ ), ethylene (C ₂ H ₄ ), acetylene (C ₂ H ₂ ), propane (C ₃ H ₈ ), silicon tetrafluoride (SiF ₄ ), disilicon hexafluoride Examples thereof include (Si ₂ H ₆ ), fluorides such as germanium tetrafluoride (GeF ₄ ), and mixed gas thereof.

For the purpose of doping, diborane (B ₂ H ₆ ), boron fluoride (BF ₃ ), phosphine (P
The simultaneous introduction of a dopant gas such as H ₃ ) is also effective in the present invention.

The substrate used in the present invention may be any one as long as it is cylindrical and conductive, and its material is, for example, Al, Cr, Mo, Au, In, Nb, Te,
Examples include metals such as V, Ti, Pt, Pb, and Fe, and alloys thereof (for example, stainless steel). In addition, a sheet of synthetic resin such as polyester, polystyrene, polycarbonate, cellulose acetate, polypropylene, polyvinyl chloride, polyethylene, polyamide, etc., or an electrically insulating substrate such as glass, ceramic, etc., at least the surface on which the deposited film is formed is subjected to a conductive treatment. Can also be used. Further, it is desirable that the side opposite to the side on which the deposited film is formed be subjected to conductive treatment.

The surface shape of the substrate can be a smooth flat surface or an uneven surface. For example, when an image is recorded using a coherent light such as a laser beam on a light receiving member for electrophotography, in order to eliminate an image defect due to an interference fringe pattern appearing in a visible image, JP-A-60- 168156
No. 60-178457, No. 60-225.
It may be an uneven surface produced by a known method described in Japanese Patent No. 854, etc.

The substrate temperature at the time of forming the deposited film is not particularly limited, but good characteristics are obtained when it is formed preferably at 20 ° C. or more and 500 ° C. or less, more preferably 50 ° C. or more and 450 ° C. or less.

The present invention is also applicable to the production of photoconductors for copying machines and printers such as blocking type amorphous photoconductors, high resistance amorphous photoconductors, and function-separated type amorphous photoconductors, as well as photoconductors for various devices. It is applicable.

That is, the present invention is for forming a deposited film, particularly a functional deposited film, particularly an amorphous semiconductor used for a semiconductor device, a photoreceptive member for electrophotography, a line sensor for image input, an imaging device, a photovoltaic device and the like. It can be suitably applied.

The deposited film forming apparatus of the present invention will be described in more detail below with reference to the drawings.

FIG. 1 is a diagram schematically showing an example of the deposited film forming apparatus of the present invention. FIG. 1 (A) is a longitudinal sectional view and FIG. 1 (B) is a lateral sectional view.

First, the substrate 101 that has been degreased and washed in advance is placed in the reaction container 100, and the reaction container 100 is evacuated by an exhaust device (not shown) (for example, a vacuum pump).
Then, the temperature of the base 101 is controlled to a predetermined temperature by a heater (not shown). When the substrate 101 reaches a predetermined temperature, a source gas is supplied from a source gas supply system (not shown) into the reaction vessel. At this time, be careful not to cause extreme pressure fluctuations such as gas ejection. Next, when the flow rate of the raw material gas reaches the specified flow rate, a vacuum gauge (not shown)
While looking at it, adjust the exhaust valve (not shown) to obtain a predetermined internal pressure.

When the internal pressure is stable, the high frequency power source 10
3 is set to a predetermined power. The high frequency power is applied to the electrode 102 through the matching box 104. By this discharge energy, the reaction container 100
The source gas introduced therein is decomposed and a deposited film is formed on the substrate 101. After the desired film thickness is formed, the supply of the high frequency power is stopped, the gas flow into the reaction container 100 is stopped, and the formation of the deposited film is completed.

When a deposited film consisting of a plurality of layers is formed on a substrate in order to obtain a deposited film having characteristics according to the use, the above operation is repeated to obtain a deposited film having a desired layer structure. Obtainable.

[0035]

EXAMPLES The present invention will be specifically described below based on examples, but the present invention is not limited thereto.

Example 1 Outer diameter 108 mm, length 370
mm, 5 mm thick aluminum cylinder that has been mirror-finished and degreased and washed is used as a substrate, and the apparatus of the present invention shown in FIG. A blocking type electrophotographic light receiving member 500 (hereinafter, referred to as a drum) having a layer structure including the charge injection blocking layer 502, the photoconductive layer 503, and the surface layer 504 shown in FIG. 5 was formed. The produced light-receiving member was set in an electrophotographic apparatus (NP6150 manufactured by Canon was modified for testing), and electrophotographic characteristics and image properties were evaluated by the following methods.

[0037]

[Table 1] Image defect Canon halftone chart (Part number: FY9-904
2) was placed on the platen, and the number of white spots having a diameter of 0.5 mm or less within the same area of the copy image obtained when copying was counted. The image defect evaluation criteria based on the number of white points are as follows. ⊚: 0-2, no problem at all ◯: 3-5, no problem Δ: 6-10, somewhat inferior ×: 11 or more, practically problematic.

Halftone Image Mura Canon Halftone Chart (Part No. FY9-904
2) is placed on a document table and irradiated with a normal exposure amount and a double exposure amount to make a copy. In the image thus obtained, image density at 100 points was measured with a circular area having a diameter of 5 mm as one unit, and the variation in the density was evaluated. The evaluation criteria are as follows. ⊚: Variation is less than 3%: ◯: Variation is 3% or more and less than 10% Δ: Variation is 10% or more and less than 20% x: Variation is 20% or more and less than 30%.

Sensitivity The electrophotographic photoreceptor is charged to a constant dark surface potential.
Then, the light image is immediately irradiated. The light image is emitted by using a xenon lamp light source and excluding light in a wavelength range of 600 mm or more using a filter. At this time, the surface potential of the bright portion of the electrophotographic photosensitive member is measured with a surface potential meter. The exposure amount was adjusted so that the light surface potential became a predetermined potential, and the exposure amount at that time was evaluated as the sensitivity. The evaluation criteria of sensitivity are as follows. ⊚: Particularly good ○: Good Δ: No problem in practical use ×: There is a problem in practical use Variability in the same lot Regarding the drums made in the same lot, the variations in the potential characteristics were evaluated in two items, sensitivity and chargeability temperature characteristic.

A) Charging ability temperature characteristic The charging ability was measured by charging the drum to a constant dark surface potential and varying the temperature of the drum from room temperature to about 45 ° C. to measure the charging ability per 1 ° C. temperature. The change was measured.

B) Sensitivity The sensitivity was measured as described above.

Evaluation criteria for variations in sensitivity and temperature characteristics of charging ability are as follows. ⊚: Particularly good with variation of less than 3% ◯: Good with variation of 3% or more and less than 5% Δ: Practical use with variation of 5% or more and less than 10% x: Practical problem with variation of 10% or more Is represented.

(Comparative Example 1) As in Example 1, an outer diameter of 10
An aluminum cylinder having a length of 8 mm, a length of 370 mm, and a wall thickness of 5 mm, which was mirror-finished and degreased and washed, was used as a substrate, and the conventional device shown in FIG. 6 was used to inject the charge shown in FIG. A blocking type drum having a layer structure including a blocking layer, a photoconductive layer, and a surface layer was formed.

The drum making by the apparatus of FIG. 6 will be briefly described below.

A cylindrical substrate 601 is installed in a discharge region sandwiched by parallel plate electrodes 602 installed in the reaction container 600, and the reaction container is evacuated by an exhaust device. After exhausting to a predetermined pressure, the cylindrical substrate 601 is heated to a predetermined temperature. After that, the source gas is introduced into the reaction vessel 600, and high frequency power is adjusted while being adjusted by the matching box 604 to generate plasma. This discharge energy decomposes the source gas introduced into the reaction vessel 600 to form a deposited film on the substrate 601. After the desired film thickness is formed, the high-frequency power supply is stopped, the gas flow to the reaction vessel side is stopped, and the formation of the deposited film is completed.

When a deposited film consisting of a plurality of layers is formed on the substrate for the purpose of obtaining desired deposited film characteristics, the above operation is repeated.

[0047]

[Table 2] The drum of Comparative Example 1 thus prepared was evaluated in the same manner as in Example 1, and the results are shown in Table 3 together with Example 1.

As shown in Table 3, the drum produced in Example 1 gave very good results in all evaluation items as compared with the drum of Comparative Example 1.

[0049]

[Table 3] (Embodiment 2) Using the apparatus of the present invention in which a cylindrical substrate as shown in FIG. 2 also serves as an electrode, the relation between the substrate for forming a deposited film and the substrate to be an electrode is The power supply was connected so as to have the same relationship (i.e., the arrangement in which the electrode is located at the center of the cylindrical substrates arranged in a grid), and the drum was prepared and evaluated in the same manner as in Example 1. . As a result, good results similar to those of Example 1 were obtained in all items.

Example 3 A drum was prepared in the same manner as in Example 1 except that the pressure was changed under the conditions for forming the photoconductive layer, and the same evaluation was performed. The results shown in Table 4 were obtained. Was given. As can be seen from Table 4, the internal pressure is 100 mm
Good results were obtained for all items in the range of Torr or less.

[0051]

[Table 4] (Example 4) Using the apparatus of the present invention shown in FIG. 3, a drum was produced under the conditions shown in Table 5, and the same evaluation as in Example 1 was carried out. The results are shown in Table 7.

[0052]

[Table 5] (Example 5) Further, using the apparatus of the present invention shown in FIG. 4, a drum was produced under the conditions shown in Table 6, and Example 1 was prepared.
The same evaluation as was done. The results are shown in Table 7.

[0053]

[Table 6]

[0054]

[Table 7] (Example 6) A drum was manufactured and evaluated in the same manner as in Example 1 except that the high frequency in the manufacturing conditions was changed as shown in Table 8. The results are shown in Table 8. From the table, it can be seen that good results are obtained in the frequency range of 50 MHz to 450 MHz.

[0055]

[Table 8] ^{* In} case of frequency 105MHz, data of Example 1

[0056]

According to the deposited film forming method and the deposited film forming apparatus of the present invention, it is possible to mass-produce a deposited film having excellent characteristics, which is used for an electrophotographic photosensitive member and the like. Furthermore, since the plasma state is uniform, variations in characteristics within the same lot can be reduced, which is advantageous in terms of yield and cost.

[Brief description of drawings]

FIG. 1 is a schematic view of an example of a deposited film forming apparatus of the present invention, in which (A) is a vertical sectional view and (B) is a horizontal sectional view.

2A and 2B are schematic views of another example of the deposited film forming apparatus of the present invention, where FIG. 2A is a vertical sectional view and FIG. 2B is a horizontal sectional view.

FIG. 3 is a schematic cross-sectional view of still another example of the deposited film forming apparatus of the present invention.

FIG. 4 is a schematic cross-sectional view of still another example of the deposited film forming apparatus of the present invention.

FIG. 5: 1 of layer constitution of light receiving member (drum) for electrophotography
It is sectional drawing which shows an example.

FIG. 6 is a schematic view of an example of a conventional deposited film forming apparatus,
(A) is a longitudinal sectional view and (B) is a lateral sectional view.

[Explanation of reference numerals] 100, 200, 300, 400, 600 Reaction vessels 101, 201, 301, 401, 501, 601
Substrate 102, 202, 302, 402, 602 Electrode 103, 203, 603 Power supply 104, 204, 604 Matching box 105, 205, 605 Exhaust filter 500 Electrophotographic photoreceptor 502 Charge injection blocking layer 503 Photoconductive layer 504 Surface layer

Claims (8)

[Claims] 1. A raw material gas introducing means, a plurality of cylindrical substrates, and a plurality of electrodes for applying high-frequency power are installed in a reaction vessel capable of depressurization, and the plurality of electrodes are placed under a reduced pressure in the reaction vessel containing the raw material gas. In a deposited film forming method of applying a high frequency power to a substrate to decompose the source gas and form a deposited film on the cylindrical substrate, all electrodes surrounding one cylindrical substrate are arranged at an equal distance from the cylindrical substrate. A method for forming a deposited film, characterized in that the deposition is performed. 2. The deposited film forming method according to claim 1, wherein the plurality of cylindrical substrates are arranged in a grid pattern, and an electrode is arranged in the center of one grid. 3. The deposited film forming method according to claim 1, wherein the electrode is a cylindrical substrate connected to a power source. 4. The method for forming a deposited film according to claim 1, wherein the deposition is carried out at a pressure in the reaction vessel of 100 mTorr or less. 5. The frequency of the high frequency power is 50 MHz to
The deposited film forming method according to any one of claims 1 to 4, wherein the frequency is 450 MHz. 6. A reaction vessel capable of depressurizing, a raw material gas introducing means, a plurality of electrodes for decomposing the raw material gas in the reaction vessel by applying high frequency power, and a deposited film formed on the surface by a decomposition product of the raw material gas. Deposited film forming apparatus in which a plurality of cylindrical substrates to be formed are installed, all electrodes surrounding one cylindrical substrate are arranged at an equal distance from the cylindrical substrate. apparatus. 7. The plurality of cylindrical substrates are arranged in a grid, and an electrode is arranged in the center of one grid.
The deposited film forming apparatus described. 8. The deposited film forming apparatus according to claim 6 or 7, wherein the electrode is a cylindrical substrate connected to a power source.