JPH087448B2 - 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, as an electrophotographic photosensitive member used in an image forming apparatus for forming an image using an electrophotographic method, a photoconductive layer formed on a conductive substrate is formed of amorphous silicon (a).
Photoconductors composed of -Si) have been proposed. This a-
Due to the following advantages, Si photoconductors have been desired for practical use.

 It has a long life.

 It is harmless to the human body.

 High sensitivity.

Such an a-Si photoreceptor is as described in JP-B-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 optimum amount of hydrogen is 10 to 40 atomic%.

<Problems to be Solved by the Invention> In the conventional a-Si photoconductor, the amount of hydrogen (H) in the film of the a-Si layer is strictly specified to be 10 to 40 atomic% as described above. . A-Si containing 10 to 40 atomic% hydrogen
In the film, the absorption coefficient α (SiH ₂ ) of the absorption near 2100 cm ^−1, which originates from the SiH ₂ bond in the infrared absorption spectrum,
The ratio α (SiH ₂ ) / α (SiH) to the absorption coefficient α (SiH) of absorption around 2000 cm ⁻¹ derived from SiH bond is about 0.2 to
The setting of 1.7 is disclosed in Japanese Patent Application Laid-Open No. 57-158650. When it is attempted to maintain sufficient photosensitivity for such an a-Si electrophotographic photosensitive member, its specific resistance is 10%.
It becomes ⁹ Ωcm, and even if boron (B) is doped, 10
^It is as small as ¹¹ Ωcm. Therefore, it is inferior to the existing selenium and OPC photoconductors in charge retention ability.

Alternatively, in order to improve the charge retention ability, in the conventional a-Si photoconductor, the absorption coefficient ratio α (SiH ₂ ) /
It is necessary to increase α (SiH). So plasma C
In the VD method and the sputtering method, it is necessary to increase the high frequency power during film formation. However, the plasma CVD method
In the sputter method, the high-frequency power during film formation is increased to activate the reaction of the source gas in the gas phase (Si
A large amount of H ₂ ) n polymer powder is generated, which adheres to the substrate of the photoconductor during film formation and prevents normal film growth.
The photoconductor was a defective product. Further, in the conventional 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 Problem> In order to solve the above problems, the method for producing an electrophotographic photosensitive member of the present invention, on the conductive substrate, 2100 cm ⁻ derived from SiH ₂ bond of the infrared absorption spectrum- the ratio of the absorption coefficient of the absorption appears near ^{1 α} (SiH _2), the absorption coefficient of the absorption appears near 2000 cm ^-1 derived from SiH bond _{α (SiH) α (SiH 2} ) /
α (SiH) should be 1.3 to 2.5, and hydrogen should be 40ato.
It is characterized in that a photoconductive layer made of amorphous silicon contained in a range of mic% or more and 60 atomic% or less is formed by an electron cyclotron resonance method.

<Operation> The photoconductive layer made of amorphous silicon is formed by the electron cyclotron resonance method. There is no concern about the generation of (SiH ₂ ) n polymer powder during this film formation, and there is no influence of this powder. Therefore, the rate of non-defective products is high, and the film formation speed can be increased,
Therefore, according to this manufacturing method, cost reduction of the photoconductor can be achieved.

Further, according to the photoconductor of the present invention, the absorption coefficient α (SiH ₂ ) of hydrogen, which contains 40 atomic% or more and 60 atomic% or less, and which appears near 2100 cm ⁻¹ derived from the SiH ₂ bond in the infrared absorption spectrum. And the absorption coefficient α (SiH) of the absorption that appears near 2000 cm ^{-1 due} to the SiH bond, ratio α (SiH ₂ ) / α
(SiH) is set to 1.3 to 2.5, and very high dark resistivity is exhibited even though boron or phosphorus is not doped.
By using this as a photoreceptor for electrophotography, it has sufficient photosensitivity and excellent charge retention ability.
It becomes possible to form a clearer image.

<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 drawing window 13 and are evacuated by an oil diffusion pump, a turbo molecular pump, or an oil rotary pump (not shown).

The plasma chamber 11 has a cavity resonator structure
Microwaves from 14 to 2.45 GHz are introduced. 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 through the introduction pipe 17. A magnetic coil 16 surrounds the plasma chamber 11.
Is arranged. The magnetic coil 16 generates plasma and forms a divergent magnetic field for drawing the plasma generated in the plasma chamber 11 to the deposition chamber 12.

A conductive substrate 18 made of aluminum (Al) 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. A raw material gas is introduced into the deposition chamber 12 through an introduction pipe 19. Examples of the source gas include hydrogen (H) such as SiH ₄ and Si ₂ H _6.
It is a silicon compound containing, or a gas obtained by mixing them. In the figure, 20 is a microwave transmitter, 21 is a conductive substrate 18
It is a heating lamp.

With such a configuration, first, the plasma chamber is
11 and the deposition chamber 12 are evacuated, H ₂ gas is introduced into the plasma chamber 11 through the introduction pipe 17, and the above-mentioned source gas is introduced into the deposition chamber 12 through the introduction pipe 19. The gas pressure at this time is
It is set to 10 ^-3 torr to 10 ^-4 torr. Where the plasma chamber
A microwave is introduced from the oscillator 20 to 11 and a magnetic field is also applied to excite plasma. Plasmaized H ₂
The source gas is guided to the conductive substrate 18 by the divergent magnetic field, and 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, it is possible to improve the uniformity of the a-Si 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. Absorption coefficient ratio α (SiH ₂ ) / SiH ₂ and SiH bond of this a-Si film
α (SiH) / Bright conductivity (ημτ) / Dark resistivity (ρd)
The gas pressure dependence of is shown in graphs in FIGS. 3, 4, and 5, respectively.

As shown in these, the absorption coefficient ratio α (SiH ₂ ) / α
By setting the value of (SiH) to 1.3 to 2.5, the dark resistivity becomes 1
It was possible to form an a-Si film having a high electrical conductivity (high photosensitivity) of 0 ¹² Ωcm or more. Thus, the dark resistivity is 10
^The a-Si film with a resistivity of ¹² Ωcm or more and high dark conductivity (high photosensitivity) has a conventional H content of 40 atomic% or less,
This cannot be achieved with an a-Si film having an α (SiH ₂ ) / α (SiH) value of 0.2 to 1.7.

As a result of further diligent experiments, α (SiH ₂ ) / of a-Si film
When the value of α (SiH) is 1.3 to 2.5 and the amount of hydrogen in the film is 40 atomic% or more, the effect of the present invention is further promoted. However, if the amount of H in the a-Si film is 65 atomic% or more, the optical band cap of the film becomes too large, and it is suitable as a photoconductive layer of an electrophotographic photosensitive member requiring photosensitivity to visible light. Turned out not. That is, the amount of H in the film is preferably
The value is 40 to 60 atomic%, most preferably 40 to 55 atomic%.

As shown in FIG. 2, the film formation according to the present invention is performed by the electron cyclotron resonance method, and no powder of (SiH ₂ ) n is generated.
Both film formation speed and gas utilization efficiency were 6 to 10 times higher than those of the conventional method.

In addition, the a-Si film according to the present invention transmits optical information from outside such as a photoconductive layer of an electrophotographic photosensitive member, a photosensitive portion of an image sensor, a photosensitive portion of a storage device for optical information laminated with liquid crystal, and the like to an electric signal. Most suitable for the photosensitive part of the device to be converted into. Furthermore, it can be applied to devices such as solar cells and thin film transistors.

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

(Example 1) Electrophotographic photoreceptor 1 for positive charging having a structure as shown in FIG.
To obtain the intermediate layer 3 and the photoconductive layer 4 on the conductive substrate 2.
And the surface coating layer 5 were formed in this order.

That includes hydrogen as the photoconductive layer 4, the absorption coefficient ratio of 2100 cm ^-1 and 2000 cm ^-1 in the infrared absorption spectrum alpha (Si
H ₂ ) / α (SiH) is 2.15, and a small amount of boron (B) is doped.
The a-Si film formed by the resonance method, the a-SiC film formed by the electron cyclotron resonance method as the surface coating layer 5, and the a-Si film formed by the same method as the intermediate layer 3 and heavily doped with boron. A positive charging photoreceptor having a -Si film was prepared. The preparation conditions at this time are summarized in Table 1 below.

A gas for doping boron (B) is B
Compounds of boron and hydrogen such as ₂ H ₆ and BH ₃ are preferable. Aluminum, gallium, indium, etc. are suitable as atoms having the same function as boron. No powder of (SiH ₂ ) n was generated at the time of film formation, and the film formation speed and gas utilization efficiency were 6 to 10 times higher than those in the conventional case. Further, when the characteristics of the prepared photoconductor were measured, it was found that the charging property was particularly excellent as compared with the conventional a-Si photoconductor. When this was mounted on a commercially available copying machine for positive charging and images were printed, good images were obtained. Further, the amount of H contained in the a-Si film described in this example was measured.
It was 48 atomic%.

Good results are obtained even when an a-SiN film or an a-SiO film formed by the electron cyclotron resonance method is used as the surface coating layer 5.

(Example 2) Table 2 shows the results of the respective photoreceptor characteristics 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 shown in Table 2 above, the gas pressure is selected and the absorption coefficient ratio α
Good results are obtained when the value of (SiH ₄ ) / α (SiH) is set to 1.3 to 2.5 (see FIG. 3).

In addition, as a result of measuring the H content contained in the photoconductive layer of each sample (photoreceptor), when the gas pressure was 2.8 to 3.4 mtorr, it was 45
~ 52atomic% and 20 ~ 30atomi at 3.8 ~ 5.0mtorr
It was a value of c%.

(Example 3) The photoconductive layer 4 contains 46 atomic% of H, and
A-Si prepared by electron cyclotron resonance method doped with a small amount of phosphorus (P)
The film, further, an a-SiC film formed by the electron cyclotron resonance method as the surface coating film 5, and an a-Si film formed by the same method as the intermediate layer 3 and heavily doped with phosphorus (P). To prepare a negative charging photoreceptor. The preparation conditions at this time are summarized in Table 3.

A compound of phosphorus and hydrogen such as PH ₃ is suitable as a gas for doping phosphorus. Nitrogen, antimony, oxygen, etc. are suitable as atoms having the same function as phosphorus.

At this time, no powder of (SiH ₂ ) n is generated, and moreover,
Both film formation speed and gas utilization efficiency were significantly higher than those of the conventional method. 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 negative charging and images were printed, good images were obtained.

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

<Effect> According to the method for producing an electrophotographic photosensitive member of the present invention, hydrogen is added in an amount of 40 atomic% to 60 atomic% to the photoconductive layer formed of the a-Si layer by the electron cyclotron resonance method.
Infrared absorption ratio α (SiH ₂ ) at that time
Since / α (SiH) is set to 1.3 to 2.5, no polymer powder of (SiH ₂ ) n is generated during the production of the photoconductor, and the dark specific resistance and photosensitivity which are important for electrophotography are high. A photoreceptor having excellent characteristics can be obtained.

Further, according to the photoconductor obtained by this manufacturing method,
There is no generation of H ₂ ) n powder, the film formation rate is high, and the gas utilization rate is considerably higher than that of the conventional method, thus increasing the non-defective product rate and enabling inexpensive production.

[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. FIG. 4, FIG. 5 and FIG. 5 are characteristic charts showing α (SiH ₂ ) / α (SiH) value, light conductivity (ημτ) and dark resistivity (ρd) in the film with respect to gas pressure. 1: a-Si photoconductor conductive substrate 2: conductive substrate, 3: intermediate layer, 4: photoconductive layer 5: surface coating layer

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-58-186748 (JP, A) JP-A-54-98588 (JP, A) JP-A-61-83544 (JP, A) JP-A-59- 159167 (JP, A) JP 63-81361 (JP, A) JP 57-158650 (JP, A)

Claims (1)

[Claims] 1. A method for producing an electrophotographic photosensitive member, comprising forming a photoconductive layer containing amorphous silicon as a component on a conductive substrate, wherein 2100 cm ⁻ derived from SiH ₂ bond of infrared absorption spectrum is formed on the conductive substrate. Absorption coefficient α (SiH ₂ ) that appears near ¹
And the ratio α (SiH ₂ ) / α (SiH) between the absorption coefficient α (SiH) of the absorption appearing near 2000 cm ⁻¹ derived from the SiH bond are 1.3
~ 2.5, and 60atomic with hydrogen of 40atomic% or more
A method for manufacturing an electrophotographic photosensitive member, comprising forming a photoconductive layer made of amorphous silicon contained in a range of mic% or less by an electron cyclotron resonance method.