JPS61149965A - Production of amorphous silicon photosensitive body - Google Patents

Abstract

PURPOSE:To obtain a surface protective layer having a stable compsn. and good light transmittance by decomposing independently only the gaseous silane of which the hydrogen atoms are substd. with a methyl group to form the surface protective layer of an amorphous silicon photosensitive body formed on a conductive base body. CONSTITUTION:A drum 22 is provided in a vessel 23 and the inside of the vessel 23 is evacuated to a vacuum by using a diffusion pump 46 and a rotary pump 48. The drum 22 is then heated by using a heater 21 for heating and further valves 29, 30, 33, 34 are opened to introduce gaseous B2H6 and gaseous Si2H6 into the vessel. A high-frequency voltage is then impressed between an electrode 26 and the drum 22 by using a high-frequency power source 27 to decompose the gases and to form a blocking layer 3 on the drum 22. Gaseous Si2H6 and gaseous B2H6 are introduced into the vessel while the flow rate of the gaseous B2H6 is throttled to form the amorphous silicon photosensitive layer 2 added slightly with boron. Valves 37, 38 are further opened to introduce independently gaseous [(CH3)2SiH2] into the vessel to form the surface protective layer 4. The protective layer having the stable compsn. and good light transmittance is thus formed.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an electrophotographic photoreceptor, in particular an electrophotographic photoreceptor that is formed on a conductive substrate using a plasma CVD method and has a surface protective layer on the surface of the photoreceptor. The present invention relates to a method of manufacturing an amorphous silicon photoreceptor.

The photoconductive layer of a recording drum having a photoconductive layer formed around it is uniformly charged, and the photoconductive layer is selectively irradiated with laser light based on printed information to increase the charged potential of the photoconductive layer. Electrophotographic devices such as laser printers are well-known, which selectively lower the latent image to form a latent image, develop the latent image by attaching charged toner to the area where the latent image is formed, and transfer and record the developed printed image onto recording paper. be.

[Conventional technology]

Conventionally, selenium (Se) has been used as such a photoconductive layer.
Se-based materials were used, but this Se is harmful;
There is a problem of pollution when discarded after long-term use, and there are many problems such as poor mechanical strength and scratches on the surface of the photoconductive layer, which deteriorates printing quality when used for a long time. .

Therefore, recently, a recording drum has been developed in which an amorphous silicon layer, which is harmless to the human body and has high mechanical strength, is formed as a photoconductive layer around a rotating body made of aluminum (All) instead of Se.

By the way, as a characteristic of such an electrophotographic photoreceptor, in order to accumulate the necessary charge on the surface of the photoreceptor, the resistance when no light is irradiated, that is, the dark resistance, must be 10 to 1'+10 Ω-cm or more. be. However, in the case of amorphous silicon, a small amount of group II rings, such as boron (B
) to increase the resistance by doping with 10
Ω - I can only get my resistance.

Therefore, in order to use amorphous silicon as a photoreceptor, as shown in FIG. An amorphous silicon layer made into a P-type by adding a high concentration of Si, or an amorphous silicon layer made into an N-type by adding a group II ring to Si in a high concentration, is used as a photoreceptor for positive charging or a photoreceptor for negative charging, respectively. This blocking layer 3 prevents charge injection from the conductive substrate 1.

Furthermore, the surface of the amorphous silicon photoreceptor layer 2 is protected from being damaged by ozone gas generated on the surface of the photoreceptor by a corona discharger used to charge the photoreceptor. In order to prevent this, a silicon carbide compound which is a compound of Si and carbon (C), or a silicon nitride compound which is a compound of Si and nitrogen (N) is formed as the surface protective layer 4. A photoreceptor composed of an amorphous silicon photoreceptor layer 2 and a surface protection layer 4 is referred to as an amorphous silicon photoreceptor.

In addition, an amorphous silicon photoreceptor with such a structure is
A blocking layer 3 prevents the transfer of charges from the conductive substrate 1 to the amorphous silicon photoreceptor layer 2; a surface protection layer 4 prevents the surface of the amorphous silicon photoreceptor layer 2 from being damaged by a corona discharger; The amorphous silicon photoreceptor is called a functionally separated amorphous silicon photoreceptor because its respective functions are separated, such as in the photoreceptor layer 2 which is sensitive to and generates electrons and holes.

In addition, as shown in FIG. 3, a thick amorphous silicon photoreceptor layer 12 is directly formed on the conductive substrate 1) without forming the above-mentioned blocking layer, and the resistance value of the photoreceptor layer is increased. Even in the case of type amorphous silicon, on the amorphous silicon photoreceptor layer 12,
The above-mentioned surface protective layer 13 is usually formed to prevent damage to the photoreceptor layer 12 by a corona discharger.

[Problem that the invention seeks to solve]

By the way, conventionally, when forming a silicon carbide compound to serve as such a surface protective layer, ethylene (C2H4) gas, which is an easily available hydrogen compound of carbon, and silane (SiH4) gas, which is a hydrogen compound of Si, or There is a method of decomposing a mixed gas of C2H4 gas and disilane (Si2H6) gas by plasma CVD. In addition, when forming silicon nitride compounds, easily available ammonia (
It was formed by decomposing a mixed gas of NHa) gas and 5iHa gas, or a mixed gas of NH gas and Si2H6 gas using a plasma CVD method.

However, when a mixed gas of silane gas such as SiH4 gas or Si2 H6 gas and C2H4 gas, which is a hydrocarbon gas, is decomposed by the plasma CVD method, a The way in which the amorphous silicon layer is decomposed depends on the deposition conditions of the amorphous silicon layer, such as the pressure of each gas and the mixing ratio of both gases, and therefore the degree of light transmission of the photoreceptor film formed and the atomic composition ratio of the crystals formed. There was a problem that it was not possible to obtain a surface protective layer whose film quality was controlled to a constant value.

[Means for solving problems]

The above problem can be solved by decomposing the surface protective layer of an amorphous silicon photoreceptor, which is formed on a conductive substrate and has a protective layer on the surface, solely with a silane gas in which hydrogen atoms are replaced with methyl groups. This problem is solved by the method of manufacturing an amorphous silicon photoreceptor of the present invention.

[Effect]

That is, in the method of manufacturing an amorphous silicon photoreceptor of the present invention, the surface protective layer of the amorphous silicon photoreceptor layer is formed by using a methyl group such as dimethylsilane (St(CHO) 2 H2) or tetramethyldisilane (Siz (CH3) 4 H2). By decomposing a single gas with a ratio of 2 = 1 to silicon atoms, even if the film formation conditions such as gas pressure change,
A film with always the same characteristics, that is, the composition ((1"0-3("o,
44'H) so that a surface protective layer can be obtained.

〔Example〕

Hereinafter, one embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a schematic diagram showing an apparatus for manufacturing an amorphous silicon photoreceptor by the method of the present invention.

As shown in the figure, a cylindrical drum 22 having a heater 21 provided therein is placed in an airtightly sealed container 23 and rotated by a motor 24 .

A cylindrical electrode 25 that is hollow inside and has a double structure is provided around the drum 22, and inside the electrode 25 that has a double structure is a surface protective layer of an amorphous silicon photoreceptor. A forming gas is introduced into the electrode 25, and a large number of gas exhaust ports 26 are provided on the surface of the electrode 25 facing the drum 22. This electrode 25 is led out to the outside of the container 23, and a high frequency power source 27 is connected to the end thereof.
is connected. Further, the gas introduction pipe 28 connected to the hollow electrode 26 is connected to a diborane (B2H6) gas cylinder 32 via a valve 29.30 and a gas flow meter 31, and further includes a valve 33.34 and a flow meter 35.
is connected to a disilane (5i2Hs) gas cylinder 36 through a valve 37, 3B, and a dimethylsilane ((CH3) 25iH2) gas cylinder 40 through a flowmeter 39.
It is connected to the.

Further, a mechanical booster pump 43 and a rotary pump 4 are connected to the exhaust port 41 of the container 23 via a valve 42.
4 is connected, a diffusion pump 46 is connected through a valve 45, and a rotary pump 48 is connected through a valve 47.

A case will be described in which a functionally separated amorphous silicon photoreceptor as shown in FIG. 1 is manufactured using such an apparatus.

First, the drum 22 is installed in the container 23, and the valve 45.4 is
7 is opened and the inside of the container 23 is evacuated to a degree of vacuum of 1O-6 torr using the diffusion pump 46 and the rotary pump 48. Next, the drum 22 is heated to 200°C to 300°C using the heater 21. do.

Furthermore, valves 29, 30, 33, and 34 are opened and 82H
6 gas and Si2H6 gas are introduced into the container 23 to bring the degree of vacuum to 0.5 torr, and then a high frequency voltage is applied between the electrode 26 and the drum 22 using the high frequency power supply 27 to generate a glow discharge. The decomposed gas is made into a plasma state, and the decomposed components of the gas are deposited on the drum 22 to form the blocking layer 3 shown in FIG.
Form to a thickness of ~1 μm.

Next, the flow rate of B2H6 gas is reduced and valve 2 is opened.
With 9.30 and 33.34 open, Si2H6
The gas and B2H6 gas are introduced into the container 23 and Poron (B
) is added to an amorphous silicon photoreceptor layer 2 shown in FIG. 2 to a thickness of 5 to 30 μm.

Furthermore, valves 29, 30, 33, and 34 are closed, and valve 37 is closed.
．． 38 is opened and ((CHa)25 is in the container 23.
iH2) A gas is introduced singly to form a surface protective layer 4 made of a silicon carbide compound and shown in FIG. 2 to a thickness of 0.01 to 1 μm.

In this way, the surface protective layer 4 ((CHa)25iH2)
By forming using a single gas, Si
The ratio of atoms to methyl groups is 1=2, and since Si and C are decomposed at this ratio, the surface protective layer 4 is always stable in the light guiding degree and the atomic composition ratio of the formed crystal. can get. Furthermore, the composition of the amorphous silicon surface protective layer 4 thus formed was investigated using an analyzer such as an electron probe microanalysis (EPMA), and the composition of -si, J, c, 6; H was determined. The dark resistance of this surface protective layer is 10Ω-0 or more, and even when this surface is charged, it has good blocking properties that block the charge on the surface from being injected into the interior, and it also has good blocking properties that prevent corona. A good surface protective layer was obtained that was not easily deteriorated by ozone gas generated around the photoconductor by discharging the discharge device. Furthermore, since the optical band gap was as large as 2.8 eV, a surface protective layer with good laser transmittance was obtained when a latent image was formed using a laser beam or the like.

The above has been described using an example of a method for manufacturing a functionally separated type amorphous silicon photoreceptor, but as shown in Figure 3, when forming a surface protective layer on the surface of a high resistance type amorphous silicon photoreceptor, Also, by using the method of the present invention, a protective layer with good light transmittance and a uniform atomic composition ratio of the crystals forming the film forming the surface protective layer was obtained.

Incidentally, for comparison with this example, when a surface protective layer is formed by mixing Si2H6 gas and C2H4 gas as in the conventional method, the mixing ratio of the two types of gases and the gas pressure are controlled much more strictly. Otherwise, the properties of the surface protective layer obtained by the method of the present invention could not be obtained.

Furthermore, in this example, dimethylsilane (St(CH3)2
H2) gas was used, but in addition, tetramethyldisilane (
Si2(CHa)4B2) gas etc., methyl group and Si
A silane gas having an atomic ratio of 2:1 may also be used.

[Effects of the Invention] As described above, according to the amorphous silicon photoreceptor of the present invention, since the surface protective layer is formed using a single gas, it is faster to form a film than in the conventional case where a film is formed using multiple gases. As a result, a high-quality surface protective layer with a stable atomic arrangement in the formed surface protective layer can be obtained, so if such a surface protective layer is used for an amorphous silicon photoreceptor, a highly reliable amorphous silicon photoreceptor can be obtained. There is an effect that can be obtained.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of an apparatus used to form the amorphous silicon photoreceptor of the present invention, and FIGS. 2 and 3 are cross-sectional views showing the structure of the amorphous silicon photoreceptor. In the figure, 1.1) is the substrate, 2.12 is the photoreceptor layer, and 3
is a blocking layer, 4.13 is a surface protection layer, 21 is a heater, 22 is a drum, 23 is a container, 24 is a motor, 25 is an electrode, 26 is a gas outlet, 27 is a high frequency power supply, 28 is a gas introduction pipe, 29 ,30.33,34.37.38.42
．． 45.47 is the valve, 31.35.39 is the flow needle, 3
2 is a B2 H6 gas cylinder, 36 is a Si2 H6 gas cylinder, 40 is a ((CHa)25iH2) gas cylinder, 4
1 is an exhaust port, 43 is a mechanical booster pump, 44.
48 is a rotary pump, and 46 is a dephasing pump.

Claims (2)

[Claims] (1) The surface protective layer of an amorphous silicon photoreceptor formed on a conductive substrate and having a protective layer on the surface is formed by solely decomposing only a silane gas in which hydrogen atoms are replaced with methyl groups. A method for manufacturing an amorphous silicon photoreceptor characterized by: (2) The method for manufacturing an amorphous silicon photoreceptor according to claim (1), wherein the ratio of the number of silicon atoms to the number of methyl groups in the silane-based gas is 1:2.