JPH07117764B2 - Method for manufacturing electrophotographic photoreceptor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Field of Industrial Application> The present invention relates to a method for producing an electrophotographic photosensitive member used in an image forming apparatus using electrophotography.

<Prior Art> Recently, a photoconductive layer formed on a conductive substrate is made of amorphous silicon (a-Si) as an electrophotographic photosensitive member used in an image forming apparatus that forms an image using an electrophotographic method. Photoconductors have been proposed. This a-Si photoreceptor has been desired to be put into practical use due to the following advantages.

 It has a long life.

 It is harmless to the human body.

 High sensitivity.

Such an a-Si photoconductor is as described in Japanese Patent Publication No. 60-35059, and a plasma CVD method or a sputtering method is used to form the a-Si layer of the photoconductive layer. Moreover, it is specified that the amount of hydrogen be 10 to 40 atomic%.

<Problems to be Solved by the Invention> In the conventional a-Si photoconductor, the amount of hydrogen in the film of the a-Si layer is strictly specified to be 10 to 40 atomic% as described above. Therefore, when trying to maintain sufficient photosensitivity for the electrophotographic photosensitive member, the specific resistance becomes 10 ⁹ Ωcm,
Even when doped with boron (B), it is as small as 10 ¹¹ Ωcm. Therefore, it is inferior to the existing selenium and OPC photoconductors in charge retention ability.

Moreover, conventional a-Si photosensitive member will be just because it is created by a plasma CVD method, Suppata method (SiH _{2) n} comprised polymer particles occurs, which adheres to the substrate of the photoreceptor in a film forming normal The film growth was hindered and the photoconductor was made defective. Further, in the conventional manufacturing method, the film forming speed is very small and it takes a long time to prepare the photosensitive member, so that the cost cannot be reduced.

<Means for Solving the Problems> In order to solve the above problems, the method for producing an electrophotographic photosensitive member of the present invention comprises:
A feature is that a photoconductive layer of amorphous silicon containing atomic% or less of hydrogen and / or halogen is formed by an electron cyclotron resonance method.

<Operation> The photoconductive layer made of amorphous silicon is formed by the electron cyclotron resonance method.
In this case, hydrogen and / or halogen is contained in the amorphous silicon in the range of 40 atomic% or more and 65 atomic% or less, and since it is not affected by the (SiH ₂ ) n polymer powder during film formation, The rate of non-defective products can be high, and the film formation speed can be increased, so that the cost reduction as a photoconductor can be achieved.

In particular, by setting the content of hydrogen or the like as described above, it is possible to obtain a photoconductor having excellent photosensitivity and having sufficiently high charge retention ability and having sufficiently excellent characteristics for electrophotography.

<Example> FIG. 1 is a sectional view showing a layer structure of an electrophotographic photosensitive member according to the present invention, and FIG. 2 is a process for producing an electrophotographic photosensitive member as shown in FIG. 1 by an electron cyclotron resonance method. It is sectional drawing which shows a membrane device.

First, in FIG. 2, the film forming apparatus has, for example, a plasma chamber 11 for generating hydrogen plasma and a deposition chamber 12 for depositing an a-Si layer. The plasma chamber 11 and the deposition chamber 12 communicate with each other through a plasma extraction window 13 and are evacuated by an oil diffusion pump and an oil rotary pump (not shown).

The plasma chamber 11 has a cavity resonator structure, and the waveguide 14
2.45GHz microwave is introduced from. The microwave introduction window 15 is made of a quartz glass plate through which microwaves can pass. H ₂ gas is introduced into the plasma chamber 11. Magnetic coils 16 and 17 are arranged around the plasma chamber 11. The magnetic coil 16 generates a plasma generating magnetic field (875G), and the magnetic coil 17 forms a divergent magnetic field for drawing the plasma generated in the plasma chamber 11 into the deposition chamber 12.

A conductive substrate 18 made of aluminum (A1) is installed in the deposition chamber 12. In the case of this embodiment, since the conductive substrate 18 is drum-shaped, it is supported by the support and rotated. Deposition chamber
12 includes, for example, SiH ₄ , Si ₂ H ₆ , SiF ₄ , and SiCl ₄ as source gases.
A compound containing hydrogen such as ₄ , SiHCl ₃ or SiH ₂ Cl ₂ , a silicon compound containing halogen, or a mixture thereof is introduced.

With such a configuration, first, the plasma chamber 11
The deposition chamber 12 is evacuated, H ₂ gas is introduced into the plasma chamber 11, and the above-mentioned source gas is introduced into the deposition chamber 12.
The gas pressure at this time is set to 10 ^-3 torr to 10 ^-4 torr. Here, while introducing microwave into the plasma chamber 11,
A magnetic field is also applied to excite the plasma. Turned into plasma
H ₂ and the raw material gas by the divergent magnetic field, the plasma extraction window 13
Is guided to the conductive substrate 18 in the deposition chamber 12 via and the a-Si is deposited on the surface thereof. Since the support is rotated, a film is uniformly formed on the conductive substrate 18. Furthermore, by adjusting the position and size of the plasma extraction window, a-Si
It is possible to improve the uniformity of the film.

In such a film forming apparatus, SiH ₄ gas was used as a raw material gas, and a film forming experiment was conducted by changing the gas pressure. In this case, the a-Si film was formed on the base 18 without heating the conductive base 18. The amount of hydrogen (H) in the film, bright conductivity (η
μτ) · Dark resistivity (ρd) gas pressure dependence when SiH ₄ gas flow rate is used as a parameter.
It is shown in the figure as a graph.

As shown in these, by setting the H content to 40 atomic% or more, the dark resistivity becomes 10 ¹² Ωcm or more for the first time without doping with boron, and the bright conductivity is high (high photosensitivity). -Si film could be created. Thus, an a-Si film having a dark specific resistance of 10 ¹² Ωcm or more and high bright conductivity (high photosensitivity) has a conventional H content of 40% or less.
It could not be achieved with the −Si film.

The reason why the a-Si film having excellent characteristics as described above can be produced by setting the H amount to 40 atomic% or more is that dangling of Si atoms by adding sufficient H in the film.
It is considered that the bonds could be reduced, or the thermally excited carriers could be reduced by increasing the optical band gap slightly.

Further, in the present invention, by forming the a-Si film by the electron cyclotron resonance method, no powder of (SiH ₂ ) _n is generated, and the film forming speed and the gas utilization efficiency are large in the gas pressure. Depending on the gas pressure selected, a considerably high value of 6 to 10 times that of the conventional method was obtained.

More preferably, by setting the gas pressure so that the H content is 40 atomic% or more, an a-Si film having a dark resistivity of 10 ¹² Ωcm or more can be formed. Moreover, it was found that at a gas pressure (2 to 3.5 mtorr) at which an a-Si film having high bright conductivity (high photosensitivity) can be produced, both the film forming rate and the gas utilization efficiency show high values.

On the other hand, the H content produced by the conventional method is 40 at
The a-Si film with an omic% or less generally has a tendency that the photosensitivity is deteriorated in a region where the film forming speed is increased. From this point as well, it was found that there is an advantage of the present invention which is not present in the conventional method.

When a silicon compound containing halogen is introduced as the source gas, the total amount of H and halogen in the film is 40 atomic.
It goes without saying that it must be at least%. As a result of further diligent experiments, when the amount of H and / or halogen in the film is set to 65 atomic% or more, the optical band gap of the film becomes too large, and electrophotography which requires photosensitivity to visible light. It has been found that it is not suitable as a photoconductive layer of a photoreceptor. That is, the amount of H and / or the amount of halogen in the film is preferably 40 to 65 atomic%, and most preferably 40 to 55 at.
The value is omic%.

The a-Si film according to the present invention converts not only the photoconductive layer of an electrophotographic photosensitive member, but also external light information such as a photosensitive portion of an image sensor, a photosensitive portion of a display element laminated with a liquid crystal, etc., into an electric signal. Most suitable for the photosensitive part of the device. Furthermore, it can be applied to devices such as solar cells and thin film transistors.

Next, examples in which a-Si containing 40 atomic% or more of H and / or halogen in the film according to the present invention is used as a photoconductive layer of an electrophotographic photoreceptor will be described.

(Example 1) In order to obtain an electrophotographic photoreceptor 1 for positive charging having a structure as shown in FIG. 1, an intermediate layer 3, a photoconductive layer 4 and a surface coating layer 5 were formed on a conductive substrate 2 (18). It was formed in this order.

That is, the SiH ₄ flow rate of the photoconductive layer 4 is 120 SCCM so that the hydrogen content is 48 atomic%, and a small amount of boron (B) is doped, and further the surface coating layer 5 is formed by the electron cyclotron resonance method. A positive charging photoreceptor having the a-SiC film thus prepared and the a-Si film, which was prepared by the same method and was heavily doped with boron as the intermediate layer 3, was prepared. The preparation conditions at this time are summarized in Table 1 below.

As a gas for doping boron, in addition to B ₂ H ₆ ,
Compounds of boron and hydrogen or halogen such as BCl ₃ and BH ₃ are preferred. Aluminum, gallium, indium, etc. are suitable as atoms having the same function as boron. At this time, no powder of (SiH ₂ ) _n is generated,
Moreover, the film forming speed and the gas utilization efficiency are 6 compared with the conventional method.
I got a fairly high value of ~ 10 times. Further, when the characteristics of the photoconductor thus prepared were measured, it was found that the charging characteristics were particularly excellent. When this was mounted on a commercially available copying machine for positive charging and image formation was carried out, a good image was obtained.

The surface coating layer 5 is an a-SiN film or an a-SiO film formed by the electron cyclotron resonance method.
Good results have been obtained even when using a membrane.

(Example 2) Table 2 shows the respective results when only the gas pressure at the time of forming the photoconductive layer was changed and the other conditions were exactly the same as in (Example 1).

As described in Table 2 above, select the gas pressure and set the hydrogen amount to 40 atomic.
Good results have been obtained when the content is more than 100% (see FIG. 3).

(Example 3) As the photoconductive layer 4, when the flow rate of SiH ₄ was 90 sccm, the film contained 53 atomic% of H and was doped with a small amount of boron.
A-SiC prepared by cyclotron resonance method
A positive charging photoreceptor having a film and an a-Si film having the same dimensions as the intermediate layer 3 and having a large amount of boron doped was prepared. The preparation conditions at this time are summarized in Table 3.

As a gas for doping boron, a compound of boron and H or halogen such as BCl ₃ or BH ₃ is preferable as described in (Example 1) in addition to B ₂ H ₆ . Also,
Aluminum and gallium indium are suitable as atoms that have the same function as boron. At this time (S
No powder of iH ₂ ) _n was generated at all, and the film formation rate and gas utilization efficiency were 6 to 10 times higher than those of the conventional method, and high values were obtained. Further, when the characteristics of the photoconductor thus prepared were measured, it was found that the charging characteristics were particularly excellent. When this was mounted on a commercially available copying machine for positive charging and an image was formed, a good image was obtained.

In addition, electron cyclotron
Good results are obtained even when an a-SiN film or a-SiO film formed by the resonance method is used.

Example 4 When only the gas pressure at the time of forming the photoconductive layer was changed and the other conditions were exactly the same as in (Example 3), the respective results are shown in Table 4. As shown in this table, good results were obtained when the gas pressure was selected and the H content was 40 atomic% or more.

Example 5 As the photoconductive layer 4, the SiH ₄ flow rate was set to 120 sccm, and the H amount was set to 48 atoms.
mic%, and a small amount of phosphorus (P) is doped, and further, a-SiC film formed by the electron cyclotron resonance method as the surface coating layer 5, and the same method as the intermediate layer 3 A negative charging photoreceptor having an a-Si film heavily doped with phosphorus (P) was prepared. The preparation conditions at this time are summarized in Table 5.

As a gas for doping phosphorus, other than PH3, PCl ₃
Compounds of phosphorus and hydrogen or halogen, such as and PCl ₅ , are suitable. Nitrogen, antimony, oxygen, etc. are suitable as atoms that have the same function as phosphorus.

At this time, no powder of (SiH ₂ ) _n was generated, and the film formation rate and gas utilization efficiency were considerably higher than those of the conventional method. Furthermore, when the characteristics of the photoconductor thus prepared were measured,
In particular, it had excellent charging characteristics. When this was mounted on a commercially available copying machine for negative charging and image formation was carried out, a good image was obtained.

In addition, electron cyclotron
Good results are obtained even when an a-SiN film or a-SiO film formed by the resonance method is used.

(Example 6) As the photoconductive layer 4, the SiH ₄ flow rate was set to 90 sccm, the film contained 53 atomic% of H, and a small amount of phosphorus (P) was doped, and further, the surface coating layer 5 was formed of electrons. A-SiC prepared by cyclotron resonance method
A negative charging photoreceptor 1 was prepared which comprises a film and an a-Si film, which was prepared by the same method as the intermediate layer 3 and was heavily doped with phosphorus (P). Table 6 summarizes the preparation conditions at this time.

As the gas for doping phosphorus, as shown in the above table, not only PH ₃ but also a compound of phosphorus and H or halogen such as PCl ₃ or PCl ₅ is suitable. Nitrogen, antimony, oxygen, etc. are suitable as atoms having the same function as phosphorus.

Here, no powder of (SiH ₂ ) _n was generated, and the film formation rate and gas utilization efficiency were considerably higher than those of the conventional method. Further, when the characteristics of the prepared photoconductor were measured, it was found that the charging characteristics were particularly excellent. Further, when this was mounted on a commercially available negative charging copying machine to form an image, a good image could be obtained.

As the surface coating layer, an a-SiN film or a-SiO film prepared by the electron cyclotron resonance method is used.
Good results have been obtained even when using a membrane.

<Effect> According to the method for manufacturing an electrophotographic photosensitive member of the present invention, as a photoconductive layer made of amorphous silicon by the electron cyclotron resonance method, the content of hydrogen and / or halogen is 40 atomic% or more and 65 atomic% or less. There is. At the time of this production, there is no fear of generation of (SiH ₂ ) n polymer powder, and it is possible to obtain a photoreceptor having a large dark resistivity, which is important for electrophotography, and having excellent photosensitivity.

In addition, the film formation speed is higher than that of the conventional method without being affected by the powder, the yield rate is high, and an inexpensive photoreceptor made of amorphous silicon can be obtained.

[Brief description of drawings]

FIG. 1 is a sectional view showing a structure of an electrophotographic photosensitive member according to the present invention, and FIG. 2 is a sectional view showing a film forming apparatus by an electron cyclotron resonance method for forming an a-Si layer of the present invention. Figures 4, 5 and 5 are characteristic diagrams showing the gas dependence of hydrogen content, light conductivity (ημτ) and dark resistivity (ρd) in the film when the SiH ₄ gas flow rate was used as a parameter. is there. 1: photoconductor, 2: conductive substrate, 3: intermediate layer, 4: photoconductive layer, 5: surface coating layer.

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Claims (1)

[Claims] 1. A method for manufacturing an electrophotographic photosensitive member, comprising forming a photoconductive layer made of amorphous silicon on a conductive substrate, wherein hydrogen and / or halogen of 40 atomic% or more and 65 atomic% or less is added to the conductive layer substrate. A method of manufacturing an electrophotographic photosensitive member, characterized in that a photoconductive layer of amorphous silicon containing is formed by an electron cyclotron resonance method.