JP2013104925A - Manufacturing method of electrophotographic photoreceptor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method of an electrophotographic photoreceptor capable of achieving uniformity and improvement of characteristics of a deposition film and suppressing an image defect at the same time.SOLUTION: A method for manufacturing an electrophotographic photoreceptor by a plasma CVD method includes the processes of: setting up a cylindrical base substance inside a reaction vessel which can be decompressed; introducing a raw material gas for forming a deposition film into the reaction vessel; forming a deposition film to form the deposition film on the surface of the cylindrical base substance by decomposing the raw material gas by applying an alternating voltage of sine wave between an electrode and a cylindrical base substance so that one potential of the electrode located inside the reaction vessel and disposed to be separated from the cylindrical base substance and the cylindrical substance with respect to the other potential becomes positive and negative alternately. The maximum value of the potential difference is below a value of a discharge maintenance voltage when the frequency of the alternating voltage is not less than 10 kHz and not more than 300 kHz and one potential of the electrode and the cylindrical base substance is positive with respect to the other potential, and is above a discharge starting voltage when one potential of the electrode and the cylindrical base substance is negative with respect to the other potential.

Description

  The present invention relates to a method for producing an electrophotographic photosensitive member by plasma CVD (plasma chemical vapor deposition).

  Conventionally, an electrophotographic photoreceptor using amorphous silicon (hereinafter also referred to as “a-Si”) is manufactured by forming a deposited film such as a photoconductive layer on the surface of a cylindrical substrate. As a method for forming a deposited film, a so-called plasma CVD method, in which a deposition gas forming raw material gas is decomposed by glow discharge and the decomposition product is deposited on the surface of a cylindrical substrate, is widely employed.

In recent years, there has been a strong demand for higher image quality in electrophotographic apparatuses. Corresponding to this, the uniformity of deposited films (thickness of deposited films and the uniformity of film quality) of electrophotographic photoreceptors has been increased. There is a strong demand for improvements and improved characteristics of deposited films.
With respect to film characteristics formed by the plasma CVD method, as in Patent Document 1, a technique for improving the durability of the treatment surface by generating plasma at 5 kHz to 30 kHz on which direct current is superimposed has been proposed.

Although improvement of film characteristics is being achieved by the technique of applying a DC bias to such an alternating voltage, the electrophotographic photosensitive member produced by the above method has a problem in further improving film characteristics.
That is, although the film characteristics are improved by Patent Document 1, ions are reciprocated according to the positive / negative voltage because of bipolar discharge in which plasma is continuously generated at positive and negative voltages. During the reciprocating motion, powdered compounds generated by repeating secondary reactions with other charged particles, neutral active species, and source gases are taken into the deposited film. Therefore, it has been a problem in further improving the film characteristics.

On the other hand, in Patent Document 2, in order to suppress the secondary reaction in the plasma, all the voltages are adjusted so as to have either positive or negative polarity, that is, only the voltage of one polarity is applied. (Hereinafter also referred to as “unipolar discharge”).
In this technique, since ions only move to one side, the secondary reaction is suppressed, and the reproducibility of the characteristics of the deposited film can be improved.

JP-A-10-1551 International Publication WO2006 / 134781

Improvement of the uniformity and characteristics of the deposited film is being achieved by such a technique of applying a voltage having only positive or negative polarity.
However, when an electrophotographic photosensitive member produced by such a method is used in an electrophotographic apparatus, there remains room for improvement in the level of image defects.
That is, in the case of unipolar discharge in the technique of Patent Document 2, a fine spark may occur.

The electrical damage at the time of spark causes local degradation of deposited film characteristics and minute film peeling, which appears as an image defect when used in an electrophotographic apparatus.
The image defect referred to here is a solid black (for example, when a toner other than black is used, it is expressed as “solid black” for the sake of convenience). A white dot appears on the image, or a black dot appears on the solid white image. (When a toner other than black is used, it is expressed as “black dot” for convenience.). Such an image defect is a so-called “pochi”.

Moreover, even if the minute film peeling is in the vicinity of the substrate, the film piece adheres to the substrate, and this causes a film defect on the substrate, which also causes image defects (pots). It may be connected.
As described above, in the method of manufacturing an electrophotographic photoreceptor using the plasma CVD method, a method has been found that simultaneously solves the problems of improving the uniformity of the deposited film, suppressing image defects, and improving the deposited film characteristics. There wasn't. For this reason, in the method of manufacturing an electrophotographic photosensitive member using the plasma CVD method, it has been difficult to simultaneously improve the uniformity of the deposited film, improve the deposited film characteristics, and suppress image defects at a high level.
An object of the present invention is to provide a method for producing an electrophotographic photosensitive member capable of simultaneously achieving a high level of improvement in uniformity of the deposited film, improvement in deposited film characteristics, and suppression of image defects.

In the plasma CVD method, the present inventors have intensively studied from the viewpoint of realizing a manufacturing method capable of achieving high-order improvement in deposition film uniformity, deposition film characteristics, and image defect suppression.
As a result, a low-frequency sine wave voltage is applied so that the potential of the other electrode is alternately positive and negative with respect to the potential of one electrode, and the positive and negative potentials are set within a specific range. It has been found that improvement in film uniformity, improvement in deposited film characteristics, and suppression of image defects can be achieved simultaneously.

  As a result of further detailed investigation, plasma is generated by causing discharge with the maximum value of either positive or negative potential difference (hereinafter also referred to as “potential difference absolute value”) being equal to or greater than the discharge start voltage. Is generated. Furthermore, the maximum value of the absolute value of the potential difference of the other polarity is set to a value less than the sustaining voltage (excluding 0 V). As a result, it has been found that the uniformity of the deposited film, the improvement of the deposited film characteristics, and the suppression of image defects can be simultaneously achieved, and the present invention has been completed.

That is, the present invention
A cylindrical substrate installation step of installing a cylindrical substrate inside a reaction vessel capable of depressurization;
A source gas introduction step for introducing a source gas for forming a deposited film into the reaction vessel;
A sinusoidal wave is formed so that the electrode disposed inside the reaction vessel and spaced apart from the cylindrical substrate and the other potential of the cylindrical substrate are alternately positive and negative. A deposition film forming step of applying an alternating voltage between the electrode and the cylindrical substrate to decompose the source gas and form a deposited film on the surface of the cylindrical substrate; In a method for producing a photoreceptor,
The frequency of the alternating voltage is 10 kHz to 300 kHz,
One of the maximum absolute value of the potential difference when the other potential with respect to one potential of the electrode and the cylindrical substrate is positive and the maximum absolute value of the potential difference when the negative potential is negative It is a value (V1) less than the voltage, and the other is a value (V2) equal to or higher than the discharge start voltage.

  By using the method for producing an electrophotographic photosensitive member of the present invention, an electrophotographic photosensitive member having good deposited film uniformity and deposited film characteristics, suppressing image defects, and capable of outputting high-quality electrophotography is provided. Manufacturable.

It is a schematic diagram for demonstrating the sine wave voltage which can be used for this invention. It is typical explanatory drawing for demonstrating the example of an apparatus for enforcing the manufacturing method of this invention. It is a schematic diagram for demonstrating the measurement example of a discharge start voltage and a discharge maintenance voltage. It is a schematic diagram for demonstrating an example of a sine wave voltage. It is typical explanatory drawing for demonstrating the example of an apparatus for enforcing the manufacturing method of this invention.

Hereinafter, the present invention will be described with reference to FIGS.
In FIG. 1, the electrodes are spaced apart from the cylindrical substrate. A sinusoidal voltage is applied to the substrate with respect to the opposing electrode, and the period T (= 1 / f, f) so that the absolute value V1 of the absolute potential difference is on the positive polarity side and the absolute value V2 of the absolute potential difference is on the opposite polarity side. Is applied at a frequency). FIG. 1 shows that the maximum value of the positive potential difference absolute value is less than the discharge sustaining voltage (V _{discharge maintaining} ) (V1), and the maximum value of the negative potential difference absolute value is greater than or equal to the discharge starting voltage (V _{discharge starting} ) ( V2) shows a sine wave applied to the substrate with respect to the opposing electrode. The sine wave is applied with the amplitude (Va) and the DC bias (Vo) controlled.

As described above, V1 and V2 are absolute values.
The discharge start voltage (V _{discharge start} ) and the discharge sustain voltage (V _{discharge sustain} ) are also absolute values.
For example, in order to maintain the discharge when the substrate has a negative potential with respect to the opposing electrode, the potential of the substrate with respect to the opposing electrode needs to be smaller than the −V _{discharge maintenance} . This is equivalent to the fact that the absolute value of the potential of the substrate with respect to the opposing electrode needs to be larger than the sustaining voltage ( _sustaining V _discharge ).

The amplitude (Va) of the sine wave is an absolute value. The value of the DC bias (Vo) is a value at which the voltage when the DC bias (Vo) is applied becomes positive and negative.
For example, when the time waveform of the potential applied to the substrate with respect to the opposing electrode is a sine wave biased to the negative side, the DC bias (Vo) takes a negative value, but the amplitude of the sine wave (Va) ) Always takes a positive value.
The discharge start voltage means the absolute value of the lowest voltage at which discharge can occur from a state where no discharge has occurred, and the discharge sustain voltage was performed by gradually lowering the voltage from the state where discharge has occurred. It means the absolute value of the lowest voltage that can sustain the discharge.

In FIG. 2, a sinusoidal alternating potential difference having a frequency of 10 kHz or more and 300 kHz or less is applied between the electrode 214 and the cylindrical substrate 212 so that the potential is alternately positive and negative, and a deposited film is formed on the surface of the cylindrical substrate 212. Is a device for forming 2A is a longitudinal sectional view, and FIG. 2B is a transverse sectional view.
The control unit 231 controls the frequency (f), sine wave amplitude (Va), and DC bias (Vo) of the sine wave alternating voltage output from the power supply 230 and applied to the cylindrical substrate 212 with respect to the electrode 214.

The frequency is set in the range from 10 kHz to 300 kHz, which becomes the LF band from the VLF band. Within this range, an electrophotographic photoreceptor having good image defects and film uniformity can be obtained.
If the frequency is too low, abnormal discharge such as arc or spark occurs and the discharge is not stable, and many film defects are likely to occur in the deposited film. When an electrophotographic photosensitive member having such a film defect is used in an electrophotographic apparatus, it is observed as an image defect depending on the size of the film defect.
If the frequency becomes too high, the electric field in the discharge space becomes uneven due to the influence of the standing wave and the impedance of the device, and it becomes difficult to ensure sufficient uniformity of the deposited film.

In the present invention, plasma is generated by generating a discharge with a positive or negative potential of a sinusoidal alternating voltage of 10 kHz to 300 kHz as a value (V2) equal to or higher than the discharge start voltage, and the other potential is maintained. It is important that the value (V1) is less than the voltage.
This will be described by taking as an example a case where the electrode 214 is set to the ground potential and a voltage is applied so that the potential of the cylindrical substrate 212 is as shown in FIG.

In a period in which the potential of the cylindrical substrate 212 is negative with respect to the electrode 214, a period (period t2) in which the absolute value of the potential difference is greater than the discharge start voltage (V _{discharge start} ) is between the electrode 214 and the cylindrical substrate 212. Plasma is generated.
At this time, neutral active species and positive ions in the plasma reach the cylindrical substrate 212 to form a deposited film (plasma CVD method).

On the other hand, since the absolute value of the potential difference is smaller than the discharge sustaining voltage (V _{discharge maintaining} ) during the period (period t1) in which the potential of the cylindrical substrate 212 with respect to the electrode 214 is a positive potential, no discharge is generated.
By not performing bipolar discharge, the incorporation of the powdery compound into the deposited film is suppressed, and the characteristics of the film are improved.
Furthermore, by providing a period during which the potential difference is a positive potential (period t1), abnormal discharge such as arcing or sparking is suppressed.

In the present invention, image defects are suppressed because abnormal discharge such as minute sparks on the substrate surface and in the vicinity of the substrate is suppressed.
Note that “plasma is generated” means that a discharge occurs between the electrode and the cylindrical substrate, and the source gas is ionized to generate charged particles (ions and electrons). .

Next, the discharge start voltage and the discharge sustain voltage will be described in detail.
In the discharge between the electrode and the cylindrical substrate, a small amount of electrons existing between the electrode and the cylindrical substrate are carried to the positive potential side by the electric field, and collide with gas molecules on the way to ionize it. The α action that generates electrons and ions continues. In order to cause this ionization, the energy of electrons at the time of collision needs to be equal to or higher than the ionization energy of gas molecules. The energy when electrons collide with gas molecules increases as the electric field increases, that is, as the voltage applied between the electrode and the cylindrical substrate increases. The voltage applied between the electrode and the cylindrical substrate is gradually increased, and when the energy when the electrons collide with the gas molecule reaches the ionization energy of the gas molecule, the ionization of the gas molecule causes the electrode and the cylindrical substrate to The number of electrons existing in between increases. Due to the increase in electrons, gas molecules are continuously ionized due to collisions, thereby starting discharge. The voltage at the beginning of this discharge is called the discharge start voltage.

  Further, if the voltage applied between the electrode and the cylindrical substrate is lowered from the state where the discharge is started, the discharge cannot be maintained when the voltage becomes lower than a certain voltage. The lowest voltage at which discharge can be maintained is called the discharge sustain voltage. The discharge sustaining voltage is usually lower than the discharge start voltage. In the state where discharge has occurred, the number of electrons in the discharge space is larger than in the state where discharge has not occurred. Therefore, even if the applied voltage between the electrode and the cylindrical substrate is less than the discharge start voltage, if there is more than the discharge sustain voltage, there will be more electrons than the number necessary to maintain the discharge, with the energy capable of ionizing gas molecules. To do. Therefore, as described above, the discharge sustaining voltage is usually lower than the discharge start voltage.

  In addition, a phenomenon called γ action is one of the reasons why the discharge sustaining voltage is lower than the discharge start voltage. The γ action is a phenomenon in which secondary electrons are emitted from the surfaces of ions generated by ionization of gas molecules when they collide with an electrode or a cylindrical substrate. After the discharge occurs, the electrons generated by this γ action also contribute to the ionization of the gas molecules, so that the discharge can be maintained at a voltage lower than the discharge start voltage.

  Thus, the discharge start voltage and the discharge sustain voltage are dominated by the ionization voltage of the gas molecules and the energy when the electrons collide with the gas molecules. The ionization voltage of gas molecules is determined once the gas type is determined. The energy of electrons when colliding with gas molecules is a function of the electric field strength and the distance traveled until the electrons collide with the gas. In other words, it is a function of the applied voltage, the distance between the electrodes, and the moving distance until the electrons collide with the gas. Further, the moving distance until the electrons collide with the gas is a function of the density of the gas, in other words, a function of the pressure.

When a mixed gas composed of a plurality of gas types is used, the gas mixing ratio together with the ionization voltage of each gas is an element that determines the discharge start voltage and the discharge sustain voltage.
Other factors that affect the discharge start voltage and discharge sustaining voltage include the electrode surface material, shape, and temperature, but these are less affected than the ionization voltage, applied voltage, interelectrode distance, and pressure. small.

  As described above, the discharge start voltage and the discharge sustain voltage vary depending on the gas type, gas mixing ratio, interelectrode distance, and pressure, and therefore have specific values depending on the gas conditions used and the configuration of the plasma CVD apparatus. That is, if the plasma CVD apparatus to be used and the gas conditions to be used are determined, the discharge start voltage and the discharge sustain voltage are uniquely determined.

  In the present invention, the discharge is caused by a positive or negative electric field rather than the values of the discharge start voltage and the discharge sustaining voltage, and then the discharge is not maintained by the electric field having the opposite polarity. It is important to get an effect. Therefore, although the values of the discharge start voltage and the discharge sustain voltage themselves vary depending on the gas conditions used and the configuration of the plasma CVD apparatus, the effects of the present invention can be obtained if the conditions of the present invention are satisfied. For example, when a mixed gas of silane gas (silicon hydride gas) and hydrogen gas is used, and when a mixed gas of silane gas, hydrogen gas, and methane gas is used, the discharge start voltage and the discharge sustain voltage are different. However, in either case, the effects of the present invention can be obtained by satisfying the conditions of the present invention.

As described above, the maximum value of the potential difference absolute value of either the positive potential or the negative potential of the cylindrical substrate 212 with respect to the electrode 214 is set to a value (V2) equal to or higher than the discharge start voltage.
Furthermore, the effect of the present invention can be obtained by applying a sinusoidal alternating potential in which the maximum value of the absolute value of the potential difference of the other polarity is a value (V1) less than the sustaining voltage.
Whether or not the discharge has started and whether or not the discharge is maintained includes, for example, a method of judging from voltage-current characteristics and a method of judging by detecting plasma emission.

FIG. 3 shows voltage-current characteristics when the discharge start voltage and the discharge sustain voltage are obtained using the apparatus of FIG. From this voltage-current characteristic, it was judged whether or not the discharge was started and whether or not the discharge was maintained, and the discharge start voltage and the discharge sustain voltage were obtained.
When discharge occurs at a negative potential, a discharge start voltage at a negative potential and a discharge sustain voltage at a positive potential are obtained.

As an example, the control unit 231 controls a sine wave output with a frequency of 25 kHz, the bias voltage (Vo) is fixed at 0V, and the current change when the amplitude (Va) is increased in increments of 10V is measured.
As shown in FIG. 3A, when the amplitude (Va) is gradually increased from 0V, it is observed that the current suddenly increases. The amplitude at that time is the discharge start voltage.

Although some current is measured up to the discharge start voltage, the current does not accompany the discharge, but is a dark current caused by movement of charged particles existing between the electrodes and a leakage current in the apparatus. .
In FIG. 3A, the current when Va is 1000 V is shown as 100%.
Next, as shown in FIG. 3 (b), it is observed that when the voltage Va is increased to 1000V and Va is decreased in increments of 10V in the direction of 0V, the current suddenly decreases. The Va immediately before the current suddenly decreased was defined as a discharge sustaining voltage. Also in FIG. 3B, the current when Va is 1000 V is shown as 100%.

In the present invention, the maximum value (V2) of the potential difference absolute value of the negative potential applied to the cylindrical substrate 212 with respect to the opposing electrode 214 is, for example, equal to or higher than the discharge start voltage (V _{discharge start} ) obtained as described above. Must be set to a value.
In addition, the maximum value (V1) of the positive potential difference absolute value applied to the cylindrical substrate 212 with respect to the opposing electrode 214 is, for example, a value less than the discharge sustaining voltage (V _{discharge maintaining} ) obtained as described above. There is a need to.

When V1 is set to a value equal to or higher than the discharge sustaining voltage, bipolar discharge occurs, so that a secondary reaction is likely to occur in the gas phase, and the generated compound may adversely affect the deposited film characteristics.
However, if V1 is set to 0V, the image defect suppressing effect cannot be obtained.
As described above, a sine wave in which the potential difference of one polarity is a value (V2) greater than or equal to the discharge start voltage and the potential difference of the other polarity is a value (V1) less than the discharge sustaining voltage is applied to the electrode 214 and the cylindrical substrate 212. It is necessary to apply in between.

<First Embodiment>
A first embodiment of the present invention will be described in detail with reference to FIG.
The electrophotographic photosensitive member produced by the present invention has a deposited film formed on the outer peripheral surface of a cylindrical substrate, for example. The deposited film is formed, for example, by sequentially laminating a lower charge injection blocking layer, a photoconductive layer, an upper charge injection blocking layer, and a surface layer. The lower charge injection blocking layer is for blocking charge injection from the cylindrical substrate, and is made of, for example, an a-Si material.
The photoconductive layer is for generating charges by irradiation with light such as laser light, and is formed of, for example, an a-Si material. In addition, the thickness of the photoconductive layer may be appropriately set depending on the photoconductive material to be used and desired electrophotographic characteristics. When the photoconductive layer is formed using an a-Si-based material, The thickness is, for example, 5 μm to 100 μm, preferably 10 μm to 60 μm.

  The upper charge injection blocking layer is for blocking the injection of surface charges when charged during the electrophotographic process, and is formed of, for example, an a-Si material. This upper charge injection blocking layer is formed, for example, as a material containing boron (B), nitrogen (N), or oxygen (O) in a-Si. Furthermore, it is necessary to have a wide optical band gap so that light such as irradiated laser light is not absorbed. For example, it is formed by containing carbon (C). The thickness is 0.01 μm or more and 1 μm or less.

  The surface layer is for protecting the surface of the electrophotographic photosensitive member, and is formed so as to withstand abrasion due to rubbing in the image forming apparatus. For example, an amorphous silicon film formed of an a-Si-based material such as hydrogenated amorphous silicon carbide (hereinafter also referred to as “a-SiC”) or hydrogenated amorphous silicon nitride (hereinafter also referred to as “a-SiN”). (A-Si film) or an amorphous carbon film (a-C film) formed of amorphous carbon (hereinafter also referred to as “a-C”). This surface layer has a sufficiently wide optical band gap with respect to the irradiated light so that light such as laser light irradiated to the electrophotographic photosensitive member is not absorbed. Further, it has a resistance value (generally 1011 Ω · cm or more) that can hold an electrostatic latent image in image formation.

The electrophotographic photosensitive member is formed by using, for example, the vacuum processing apparatus shown in FIG. The vacuum processing apparatus of FIG. 2 includes a cylindrical reaction vessel 211 for forming a deposited film on the cylindrical substrates 212A and 212B by plasma processing, and a heater 216 for heating the cylindrical substrates 212A and 212B. Yes.
In addition, substrate holders 213A and 213B for holding cylindrical substrates 212A and 212B, and a gas block 235 for introducing a source gas for forming a deposited film into the cylindrical reaction vessel 211 are provided.

The gas block 235 is provided with an introduction hole for introducing a gas from the source gas mixing device 225 and a plurality of discharge holes for releasing the gas into the cylindrical reaction vessel 211. Further, a pipe for distributing gas from the introduction hole to the plurality of discharge holes is formed inside.
The gas block 235 has a structure that can be detached (removable) from the electrode 214. The electrode 214 constitutes at least a part of the inner wall of the cylindrical reaction vessel 211.

  The connection between the gas block 235 and the gas supply system is connected via a joint member (not shown). By setting it as such a structure, it can replace | exchange for the reaction container of the structure corresponding to manufacture of each kind by replacing only a gas block, Therefore It is not necessary to replace the reaction container for every kind. For this reason, the work time for the setup change can be greatly shortened. In addition, it is not necessary to manufacture the reaction vessel for each product type, and it is sufficient to manufacture only the gas block according to the product type, so that the merit of greatly reducing the investment cost of the apparatus is produced.

Although there is no restriction | limiting in particular regarding the shape of the gas block 235, It is preferable that the level | step difference with the inner surface of the electrode 214 is as small as possible. Further, the surface of the gas block (the surface on the gas discharge hole side) that forms the same surface as the inner surface of the electrode 214 may be a flat surface, but is preferably a curved surface having the same curvature as the inner surface of the electrode 214.
The diameter of the gas discharge hole of the gas block is preferably in the range of 0.5 mm to 2.0 mm. Furthermore, the accuracy of each discharge hole is preferably within ± 20% of the diameter. Depending on the accuracy of the gas discharge hole, not only the longitudinal (axial) characteristic unevenness of the electrophotographic photosensitive member but also the circumferential unevenness may be affected when the deposited film is formed while rotating the cylindrical substrate. is there.

  In the gas block, it is also effective to use a material made of an insulating ceramic as a material in the vicinity of the gas discharge hole. Depending on the film forming conditions, the vicinity of the gas discharge hole may be in a state where the plasma tends to concentrate due to the influence of the gas flow (protrusion pressure), which is effective in suppressing this. Since the gas block 235 can be detached from the electrode 214 (demountable), the block can be processed by itself, so that the process of embedding a tubular ceramic component in the vicinity of the gas discharge hole can be easily performed. Specific examples of the ceramic material include alumina, zirconia, mullite, cordierite, silicon carbide, boron nitride, and aluminum nitride. Among these, alumina, boron nitride, and aluminum nitride are preferable because of their excellent insulation resistance, and in view of cost, workability, etc., a material having alumina as a base material is more preferable.

  The cylindrical reaction vessel 211 forms a space that can be decompressed by the electrode 214, the base plate 219, and the upper lid 220. The electrode 214 is preferably at a constant predetermined potential, and more preferably grounded. Since the potential difference between the electrode 214 and other portions in the cylindrical reaction vessel 211 can be kept constant by setting the electrode 214 to a constant predetermined potential, the reproducibility of the characteristics of the electrophotographic photosensitive member to be manufactured is improved. . Furthermore, the device can be easily handled by grounding the electrode 214. When the base plate 219 and the upper lid 220 are grounded and the electrode 214 is not grounded, insulating members are provided between the electrode 214 and the base plate 219 and between the electrode 214 and the upper lid 220, respectively. In the apparatus shown in FIG. 2, all of the electrode 214, the base plate 219, and the upper lid 220 are grounded.

2 includes a raw material gas mixing device 225 and a raw material gas inflow valve 224 that include a mass flow controller (not shown) for adjusting the flow rate of the raw material gas.
The base holders 213A and 213B that hold the cylindrical bases 212A and 212B are rotatably supported. The rotation support mechanism includes a support shaft 222 and a motor 221 connected to the support shaft 222 with a gear.

Joining electrodes 217A and 217B are joined to the inside of the base holders 213A and 213B. The joining electrodes 217A and 217B are connected to the power source 230 via the support shaft 222. The electrode 214, the cylindrical base bodies 212A and 212B, and the base body holders 213A and 213B are arranged so that their central axes coincide.
The outer surface of the heater 216 is grounded, and the insulating member 215A is provided between the heater 216 and the cylindrical bases 212A and 212B, so that the heater 216 and the cylindrical bases 212A and 212B are insulated. . Inside the heating heater 216, an insulating member 215B is installed between the heating shaft 216 and the support shaft 222, and the heating heater 216 and the support shaft 222 are insulated.

  The exhaust system provided in the vacuum processing apparatus of FIG. 2 has an exhaust pipe 226 communicated with the exhaust port of the cylindrical reaction vessel 211, an exhaust main valve 227, and a vacuum pump 228 such as a rotary pump or a mechanical booster pump. doing. The inside of the cylindrical reaction vessel 211 is maintained at a predetermined pressure while looking at the vacuum gauge 223 provided in the cylindrical reaction vessel 211 by this exhaust system.

The operation of the power supply 230 is controlled by the control unit 231. The control unit 231 is configured to be able to supply a sinusoidal alternating voltage of 10 kHz to 300 kHz (see FIG. 1) to the cylindrical base body 212 and the base body holder 213 by controlling the power source 230.
A discharge space for forming a deposited film on the cylindrical substrate 212 is defined by an insulating plate 218B attached to the grounded electrode 214 and the grounded base plate 219, and an insulating plate 218A attached to the grounded upper lid 220. Has been.

  The distance between the cylindrical base bodies 212A and 212B and the electrode 214, that is, the inter-electrode distance D will be described. When the inter-electrode distance D is smaller than 5 mm, there is an influence of the variation between lots of the inter-electrode distance caused by the coaxial deviation between the cylindrical base bodies 212A and 212B and the electrode 214 when the cylindrical base bodies 212A and 212B are installed. It tends to occur and it becomes difficult to obtain stable reproducibility. On the other hand, when the distance D is large, the cylindrical reaction vessel 211 becomes large and the productivity per unit installation area is deteriorated. For this reason, the inter-electrode distance D is preferably about 5 mm to 300 mm.

Hereinafter, an example of a method for forming an electrophotographic photoreceptor using the apparatus of FIG. 2 will be described.
(Cylindrical substrate installation process)
For example, the cylindrical substrates 212A and 212B whose surfaces are mirror-finished using a lathe are mounted on the substrate holders 213A and 213B so as to include the substrate heater 216 in the cylindrical reaction vessel 211.

(Raw material gas introduction process)
Next, also serving as exhaust in the gas supply device, the raw material gas inflow valve 224 is opened, the exhaust main valve 227 is opened, and the cylindrical reaction vessel 211 and the gas block 235 are exhausted. When the reading of the vacuum gauge 223 becomes 0.67 Pa or less, an inert gas for heating, for example, argon, is introduced from the gas block 235 into the cylindrical reaction vessel 211 through the source gas introduction valve 224. Then, the flow rate of the heating gas and the opening of the exhaust main valve 227 or the exhaust speed of the vacuum pump 228 are adjusted so that the inside of the cylindrical reaction vessel 211 has a desired pressure. Thereafter, a temperature controller (not shown) is operated to heat the cylindrical base bodies 212A and 212B with the heater 216, and the temperature of the cylindrical base bodies 212A and 212B is controlled to a predetermined temperature of 20 ° C to 500 ° C. When the cylindrical substrates 212A and 212B are heated to a desired temperature, the inert gas is gradually stopped. Concurrently, prescribed raw material gas for film formation, for example _{SiH 4, Si 2 H 6,} CH 4, the material gas such as C 2 _{H 6,} also the raw material a doping gas such as _B 2 _H 6, PH ₃ After mixing by the gas mixing device 225, it is gradually introduced into the cylindrical reaction vessel 211. Next, each source gas is adjusted to a predetermined flow rate by a mass flow controller (not shown) in the source gas mixing device 225. At that time, the opening of the exhaust main valve 227 or the exhaust speed of the vacuum pump 228 is adjusted while looking at the vacuum gauge 223 so that the inside of the cylindrical reaction vessel 211 is maintained at a predetermined pressure.

(Deposited film formation process)
After completing the film formation preparation by the above procedure, the lower charge injection blocking layer is formed on the cylindrical substrates 212A and 212B. Specifically, after confirming that the internal pressure is stable, the power supply 230 is set to a desired voltage, and the control unit 231 sets the desired frequency and duty ratio. Accordingly, an alternating voltage is applied to the cylindrical base bodies 212A and 212B and the base body holders 213A and 213B through the support shaft 222 to cause glow discharge. Each source gas introduced into the cylindrical reaction vessel 211 is decomposed by the energy of this discharge, and a predetermined deposited film is formed on the cylindrical substrates 212A and 212B. During film formation, the cylindrical base bodies 212A and 212B may be rotated at a predetermined speed by the motor 221.

  After the formation of the desired film thickness, the supply of the alternating voltage is stopped, the flow of each source gas into the cylindrical reaction vessel 211 is stopped, and the inside of the reaction vessel is once evacuated to a high vacuum. The electrophotographic photosensitive member is formed by repeating the above operation.

EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention further in detail, this invention is not restrict | limited at all by these.
<Example 1 and Comparative Example 1>
In Example 1 and Comparative Example 1, the frequency at which the photoconductive layer was formed was 100 kHz, the amplitude (Va) was 600 V, and the dependence of the electrophotographic characteristics on the bias voltage (Vo) at the time of forming the photoconductive layer was examined. .

  Using the deposition forming apparatus shown in FIG. 2, an electrophotographic photosensitive member is formed on the cylindrical substrate (cylindrical aluminum substrate having a diameter of 108 mm, a length of 358 mm, and a thickness of 5 mm) under the conditions shown in Table 1. Produced. At that time, the lower injection blocking layer, the photoconductive layer, the upper injection blocking layer, and the surface layer were formed in this order. The discharge start voltage (negative potential) and the discharge sustain voltage (positive potential) shown in Table 1 are values measured in advance by the method described above under the internal pressure and gas conditions of each layer.

At the time of forming the photoconductive layer, a sinusoidal voltage composed of an amplitude (Va) and a bias voltage (Vo) with respect to the electrode 214 is applied to the cylindrical substrate 212 from the power supply 230 and the control unit 231.
The bias voltage (Vo) was set as shown in Table 2.
The potential differences V1 and V2 in the table represent the maximum value of the absolute potential difference of the negative potential and the maximum value of the absolute potential difference of the positive potential with respect to the electrode 214 of the cylindrical base body 212, respectively.
Note that it was confirmed that the discharge was not maintained at the value of V1 in Example 1-2.

In Example 1, the magnitude of V2 is greater than or equal to the discharge start voltage, while the magnitude of V1 is less than the sustaining voltage but not zero. Although the cylindrical substrate 212 is discharged with a negative polarity and is not discharged with a positive polarity, a non-zero positive electrode potential difference is applied to the electrode 214.
Next, in Comparative Example 1-1, the magnitudes of V1 and V2 are both equal to or higher than the discharge start voltage. Therefore, the cylindrical substrate 212 discharges with both positive and negative electrodes with respect to the opposing electrode 214.

  And in the comparative example 1-2, while the magnitude | size of V2 is more than a discharge start voltage, the magnitude | size of V1 is zero. Therefore, the cylindrical substrate 212 is discharged with a polarity that is negative with respect to the opposing electrode 214. On the other hand, no potential difference is applied with a positive polarity. Therefore, only one side of the voltage is applied.

  A total of 12 electrophotographic photoconductors were evaluated by the following methods for each of the two conditions prepared in Example 1 and Comparative Example 1. The evaluation results are shown in Table 3.

(Image defect)
Image defects of the produced electrophotographic photosensitive member were evaluated as follows.
The produced electrophotographic photosensitive member was installed in a modified iR8500 manufactured by Canon Inc., which was modified to have a negative charging and reversal development method. The developer of this modified machine was removed, a surface potential meter (Surface potential meter Model 344, probe Model 555-P manufactured by Trek) was installed at the position of the developer, and the surface potential of the electrophotographic photosensitive member was measured by the following procedure. .

First, a solid white image (latent image forming laser non-exposure) is output, the dark portion potential of the electrophotographic photosensitive member is measured, and the primary current and grid voltage of the primary charger are adjusted so that the dark portion potential becomes −450V. Adjusted.
Next, the surface potentiometer was removed and the developing unit was returned, and an image was output under conditions that would make it easy to produce a spot in order to evaluate image defects strictly. More specifically, the slightly biased image was output by adjusting the DC bias condition of the development condition. The “fogging” means a phenomenon in which the density increases due to toner adhering to a non-image portion that should originally be whitened by a developing operation in electrophotography (from the Imaging Society Glossary).

  The fog density was measured according to the following procedure, and an image for evaluation was output under development conditions where the fog density was in the range of 0.4 to 0.8%. The reflectance of the evaluation image was measured, and the reflectance of unused paper was further measured. The reflectance value of the evaluation image was subtracted from the reflectance value of unused paper to obtain the fog density. The reflectance was measured by attaching an amber filter to a white photometer (TC-6DS manufactured by Tokyo Denshoku).

Image output was performed in the following printing environment.
Printing environment Temperature 23 ° C./humidity 60 RH% (hereinafter also referred to as “N / N”)
The output paper and output image were as follows, and 10 solid white images (latent image forming laser non-exposure) were continuously output, and evaluation was performed using the last two sheets.
Paper A3 paper CS-814 (81.4g / m2)
Canon Marketing Japan Co., Ltd. Image electrophotographic photosensitive member equivalent to one round (= about 339 mm from the leading edge in the paper transport direction) × image area width of 292 mm within a circle with a diameter of 0.1 mm or more (0.1 mm) Count the number of pots that have a part that protrudes from the circle when the circles are stacked.

For the evaluation, the two electrophotographic photosensitive members of each example and comparative example were counted for each of the two images, the average value of the four evaluation numbers was calculated, and the numbers after the decimal point were rounded up to indicate integer values. .
Furthermore, the evaluation was ranked according to the following criteria.
A ... 15 or less B ... 16 or more and 25 or less C ... 26 or more and 35 or less D ... 36 or more The effect of the present invention appears clearly with C evaluation or more, and image defects Less good images can be obtained. In D evaluation, it was judged that the effect of this invention was not acquired.

(Optical memory)
The optical memories of the electrophotographic photoreceptors produced in this example and the comparative example were evaluated as follows.
The produced electrophotographic photosensitive member was installed in a modified iR8500 manufactured by Canon Inc., which was modified to have a negative charging and reversal development method. Then, the developing device of the modified machine was removed, and a surface potential meter (surface potential meter Model 344, probe Model 555-P manufactured by Trek) was installed at the position of the developing device, and the surface potential of the electrophotographic photosensitive member was measured.

  First, the dark portion potential of the electrophotographic photosensitive member is measured while performing a solid white image (latent image forming laser non-exposure) output operation, and the dark portion potential becomes −450 V by adjusting the primary current and grid voltage of the primary charger. Adjusted as follows. Next, the bright portion potential of the electrophotographic photosensitive member is measured while performing a solid black image (latent image forming laser exposure) output operation, and the light amount of the latent image forming laser is adjusted so that the bright portion potential becomes −100V. Adjusted as follows.

  The charging setting and the laser exposure setting are fixed, the surface potential meter is removed, the developing unit is returned, and an output operation of 10 A3 size solid white images is performed. In addition, a solid black image of one A3 size electrophotographic photosensitive member (a solid black image of about 339 mm of A3 and a solid white image other than that), one solid white image of A3 size, a total of 12 images Perform output operation. The surface potential between them was measured. The surface potential was measured at seven points in the axial direction of the electrophotographic photosensitive member (± 50 mm, ± 100 mm, ± 150 mm with the axial center of the electrophotographic photosensitive member being 0 mm). In the circumferential direction of the electrophotographic photoreceptor, data at 40 points at 9 ° intervals were acquired.

After the surface potential measurement, for each axial position, the potential difference between the same position in the circumferential direction of the electrophotographic photosensitive member between the dark portion potential before one round of the solid black portion output operation and the dark portion potential after one round of the solid black portion output operation was obtained. . Next, the average value of the potential difference at each axis position was calculated, and the value with the largest potential difference was defined as the optical memory. In addition, the value of each Example and the comparative example employ | adopted the one with a larger value among the two electrophotographic photoreceptors produced by 1 batch.
The smaller the size, the smaller the optical memory and the better the electrophotographic characteristics.
Furthermore, the evaluation was ranked according to the following criteria.

A: 0.0 V or more and less than 1.0 V B ... 1.0 V or more and less than 2.0 V C ... 2.0 V or more and less than 3.0 V D ... 3.0 V or more Thus, it was determined that the density difference could be clearly confirmed, and the effect of improving the characteristics of the present invention did not appear.

(Thickness uniformity)
The film thickness uniformity was evaluated by the following method.
The film thickness of the produced electrophotographic photosensitive member was measured at the following measurement points. In the axial direction, the central position of the electrophotographic photosensitive member was set to 0 cm. Then, 9 points (± 2 cm, ± 4 cm, ± 6 cm, ± 8 cm, ± 10 cm, ± 12 cm, ± 14 cm, ± 16 cm, ± 18 cm) at intervals of 2 cm on each side, and a total of 19 points including the 0 cm position. At each axial position, 12 points at 30 ° intervals in the circumferential direction, a total of 228 points were taken as measurement positions. The value obtained by dividing the difference between the maximum value and the minimum value of the film thickness at each measurement point by the average film thickness was defined as film thickness uniformity.

The measurement was performed by an eddy current method with a probe ETA3.3H attached to FISCHERSCOPE mms (manufactured by MELMUT FISHER). The smaller the value, the better the film thickness uniformity.
In addition, the value of the film thickness uniformity of each Example and the comparative example made the value with a larger value out of two drums the evaluation value.
Furthermore, the evaluation was ranked according to the following criteria.

A ... less than 3.0% B ... 3.0% or more and less than 4.0% C ... 4.0 or more and less than 5.0% D ... 5.0% or more Since the thickness unevenness is large and, as a result, a density difference corresponding to the film thickness unevenness may be confirmed in the image, it was determined that the effect of improving the characteristics of the present invention did not appear.

(Comprehensive evaluation)
The lowest evaluation rank in each rank of image defect, optical memory, and film thickness uniformity is shown as a comprehensive evaluation.
Rank A was the best, and it was judged that the characteristic improvement effect of the present invention did not appear in rank D.

The results of ranking are shown in Table 4.

From the evaluation results of Table 3, it was found that the defect suppression effect could not be sufficiently obtained by voltage application with only one electrode because the number of image defects increased in Comparative Example 1-2.
The optical memory showed a large value in Comparative Example 1-1. From this, it is surmised that the bipolar discharge is a cause of an increase in the amount of the compound by vapor phase growth during the formation of the electrophotographic photosensitive member, thereby deteriorating the characteristics of the deposited film.

On the other hand, in Examples 1-1 to 1-4, since the number of image defects was reduced compared to Comparative Example 1-2, it is considered that the effect of suppressing image defects was improved. Moreover, since the optical memory decreased with respect to Comparative Example 1-1, it is considered that the deposited film characteristics were improved.
That is, in the potential of the cylindrical substrate 212 with respect to the opposing electrode 214, the maximum absolute value when the potential is positive is set to a value (V1) less than the sustaining voltage, and the maximum absolute value when the potential is negative is discharged. The value (V2) was equal to or higher than the starting voltage. By doing so, it was found that an electrophotographic photosensitive member with few image defects and good characteristics can be obtained.

<Example 2 and Comparative Example 2>
An electrophotographic photosensitive member was produced in the same manner as in Example 1-1 except that the amplitude (Va) at the time of forming the photoconductive layer was changed to the value shown in Table 5. Note that it was confirmed that the discharge was not maintained at the value of V1 in Example 2-2. In Example 2, the dependence of the electrophotographic characteristics on the amplitude (Va) at the time of forming the photoconductive layer was examined.
In Example 2, the cylindrical base 212 is discharged with a negative polarity and is not discharged with a positive polarity, but a non-zero positive electrode potential difference is applied to the opposing electrode 214.

In Comparative Example 2-1, the cylindrical substrate 212 discharges with both positive and negative electrodes with respect to the opposing electrode 214.
In Comparative Example 2-2, the cylindrical substrate 212 is discharged with a negative polarity with respect to the opposing electrode 214, and voltage is applied only to one electrode.
A total of eight electrophotographic photoreceptors were evaluated in the same manner as in Example 1 for each of the two conditions prepared in Example 2 and Comparative Example 2. The evaluation results are shown in Table 6, and the results of ranking are shown in Table 7.

As shown in Table 6, since the number of image defects was increased in Comparative Example 2-2, voltage application with only one electrode sufficiently obtained a defect suppression effect as in Comparative Example 1-2. It is inferred that it is the cause of the absence.
The optical memory showed a large value in Comparative Example 2-1. From this, as in Comparative Example 1-1, it is surmised that the bipolar discharge is a cause of an increase in the compound due to vapor phase growth during the formation of the electrophotographic photosensitive member, thereby deteriorating the characteristics of the deposited film.

On the other hand, in Examples 2-1 to 2-2, the number of image defects decreased compared to Comparative Example 2-2, and the optical memory decreased compared to Comparative Example 2-1.
Therefore, in the potential of the cylindrical substrate 212 with respect to the opposing electrode 214, the maximum absolute value when the potential is positive is set to a value (V1) less than the sustaining voltage, and the maximum absolute value when the potential is negative is The value (V2) was equal to or higher than the discharge start voltage. By doing so, it was found that an electrophotographic photoreceptor having good characteristics with few image defects can be obtained.

<Example 3>
An electrophotographic photosensitive member was produced in the same manner as in Example 1-1 except that the internal pressure during the formation of the photoconductive layer was changed to the values shown in Table 8. In Example 3, the dependence of the electrophotographic characteristics on the internal pressure during the formation of the photoconductive layer was examined.
Table 8 also shows the discharge start voltage and the discharge sustain voltage at each internal pressure.

In Example 3, the magnitude of V2 is greater than or equal to the discharge start voltage, while the magnitude of V1 is less than the sustaining voltage but not zero. Therefore, a positive electrode potential difference that is not zero is applied to the opposing electrode 214, although the cylindrical substrate 212 discharges with a negative polarity and does not discharge with a positive polarity.
A total of four electrophotographic photoreceptors were evaluated in the same manner as in Example 1 for each of the two conditions prepared in Example 3. The evaluation results are shown in Table 9, and the results of ranking are shown in Table 10.

  As shown in Table 9, it can be seen that the evaluation of the optical memory of Example 3-1 in which the internal pressure was increased was slightly lower than that in Examples 1 and 2, but the deposited film characteristics were sufficient and good deposition was achieved. It is considered that film characteristics were obtained.

<Example 4 and Comparative Example 4>
In Example 4, the potential difference of the cylindrical substrate with respect to the opposing electrode is applied and the electrophotographic characteristics with respect to the frequency at which the photoconductive layer is formed are prepared at the frequency at which the photoconductive layer is formed as shown in Table 12. The dependence of was investigated.
5 using the deposited film forming apparatus shown in FIG. 5 on the cylindrical substrate (cylindrical aluminum substrate having a diameter of 108 mm, a length of 358 mm, and a thickness of 5 mm) under the conditions shown in Table 11 and Table 12. A photographic photoreceptor was prepared.

In the deposited film forming apparatus shown in FIG. 5, a sinusoidal voltage having an amplitude (Va) is applied to the cylindrical substrates 512A and 512B. A bias voltage was applied from the power source 534 to the electrode 514 on the container wall surface side. As a result, the cylindrical substrate 512 and the electrode 514 have the other potential as shown in FIG.
FIG. 4A shows a schematic diagram of a sine wave voltage applied to the cylindrical substrate 512 and a bias voltage applied to the electrode 514 on the container wall surface side.
Table 12 shows the discharge start voltage and the discharge sustain voltage at each frequency.

In all of Examples 4-1 to 4-3, the magnitude of V2 is equal to or higher than the discharge start voltage, while the magnitude of V1 is less than the discharge sustaining voltage but is not zero. For this reason, the cylindrical substrate 512 is discharged with a negative polarity with respect to the electrode 514 and is not discharged with a positive polarity, but a non-zero positive electrode potential difference is applied.
A total of four electrophotographic photoreceptors were evaluated by the following methods, each for two conditions prepared in Example 4. The evaluation results are shown in Table 13, and the results of ranking are shown in Table 14.

As shown in Table 13, although the film thickness uniformity tends to decrease slightly when the frequency increases to 300 kHz (Example 4-3), it is sufficient film thickness uniformity. It is considered that good discharge uniformity was obtained.
Further, when the frequency is lowered to 10 kHz, the number of image defects tends to increase slightly (Example 4-1), but it is sufficiently small, and it is considered that a good image quality was obtained.
In addition, almost the same results are obtained in Example 4-2 and Example 1-1.

From the above, a sinusoidal alternating voltage having a positive potential of the cylindrical substrate 512 with respect to the electrode 514 (V1) less than the sustaining voltage, a negative potential greater than the discharge start voltage (V2), and a frequency of 10 kHz to 300 kHz is applied. As a result, an electrophotographic photosensitive member with few image defects was obtained.
In addition, the electrophotographic photosensitive member obtained by applying this sine wave alternating voltage had good characteristics and uniformity.

The fourth embodiment is different from the first embodiment in the voltage application method.
However, as in Example 1, a sine wave alternating potential having a positive potential less than the sustain voltage (V1) and a negative potential greater than the discharge start voltage (V2) is applied to the opposite electrode to the substrate. Thus, it was found that an electrophotographic photosensitive member having good uniformity and characteristics and few defects can be obtained.

211 Cylindrical reaction vessel 212 Cylindrical substrate 212A Upper cylindrical substrate 212B Lower cylindrical substrate 213 Substrate holder 213A Upper substrate holder 213B Lower substrate holder 214 Electrode 215A Insulating member (outside)
215B Insulation member (inside)
216 Heating heaters 217A, 217B Joining electrodes 218A, 218B Insulating plate 219 Base plate 220 Upper lid 221 Motor 222 Support shaft 223 Vacuum gauge 224 Raw material gas inflow valve 225 Raw material gas mixing device 226 Exhaust piping 227 Exhaust main valve 228 Vacuum pump 230, 530 Power supply 231 and 531 Controllers 533A and 533B Vacuum-tight and insulating ceramic 534 DC power supply

Claims (4)

A cylindrical substrate installation step of installing a cylindrical substrate inside a reaction vessel capable of depressurization;
A source gas introduction step for introducing a source gas for forming a deposited film into the reaction vessel;
A sinusoidal wave is formed so that the electrode disposed inside the reaction vessel and spaced apart from the cylindrical substrate and the other potential of the cylindrical substrate are alternately positive and negative. A deposition film forming step of applying an alternating voltage between the electrode and the cylindrical substrate to decompose the source gas and form a deposited film on the surface of the cylindrical substrate; In a method for producing a photoreceptor,
The frequency of the alternating voltage is 10 kHz to 300 kHz,
One of the maximum absolute value of the potential difference when the other potential with respect to one potential of the electrode and the cylindrical substrate is positive and the maximum absolute value of the potential difference when the negative potential is negative A method for producing an electrophotographic photosensitive member, characterized in that the value is less than the voltage (V1) and the other is a value (V2) greater than or equal to the discharge start voltage.   The method for producing an electrophotographic photosensitive member according to claim 1, wherein in the deposited film forming step, the potential of the electrode is constant.   The method of manufacturing an electrophotographic photosensitive member according to claim 1, wherein the source gas contains a silicon hydride gas, and the deposited film is an amorphous silicon film.   The method for producing an electrophotographic photosensitive member according to any one of claims 1 to 3, wherein the electrode constitutes at least a part of an inner wall of the reaction vessel.