JP2005163162A - Apparatus and method for forming deposition film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an apparatus and a method for forming a deposition film, whereby unevenness in electrical properties of a photoreceptor is suppressed, unevenness in image density is improved and reduction of globular projections causing image defects can be achieved. <P>SOLUTION: In the method, the deposition film having good properties is formed on a plurality of substrates by placing cylindrical substrates on the circumference of the same circle at regular intervals in a reaction vessel which is at least partially composed of a dielectric member and introducing a high-frequency powder from outside of the reaction vessel. A cylindrical member is installed approximately in the center of the reaction vessel, and the distance between a conductive upper lid composing a part of the reaction vessel and the upper end face of an auxiliary substrate facing the conductive upper lid is adjusted to 10-150 mm. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an apparatus and method for forming a deposited film on a substrate. In particular, the present invention relates to an apparatus and a method for forming a functional film, particularly a deposited film used for a semiconductor device, an electrophotographic photosensitive member, an image input line sensor, a photographing device, a photovoltaic device, and the like.

  Conventionally, as a deposition film forming method used for forming semiconductor devices, electrophotographic photosensitive members, line sensors for image input, photographing devices, photovoltaic devices, other various electronic elements, optical elements, etc., plasma CVD method, ion plating method Many methods using plasma generated by high-frequency power, such as a plasma etching method, are known, and an apparatus therefor has been put into practical use.

  For example, a plasma CVD method, that is, a method in which a source gas is decomposed by high-frequency glow discharge to form a thin deposited film on a substrate has been put to practical use as a suitable deposited film forming means. Various devices have been proposed for use in the formation of silicon (hereinafter referred to as “a-Si: H”) deposited films.

  In particular, plasma CVD (hereinafter abbreviated as “VHF-PCVD”) using high-frequency power in the VHF band is attracting attention, and the development of various deposited films using this VHF-PCVD method is active. It is being advanced. This is because the VHF-PCVD method has a relatively high deposition rate, and a high-quality deposited film can be obtained, so that it is expected that the cost of the product and the quality can be improved at the same time. is there. Development of a deposited film forming apparatus that can simultaneously form a plurality of light-receiving members for a-Si: H-based electrophotography and has high productivity is in progress.

  For example, by arranging a plurality of cathode electrodes on the outside of the reaction vessel and using a part of the reaction vessel between the cathode electrode and the counter electrode as a dielectric member, a uniform high frequency discharge can be easily achieved in a large area. An apparatus that can perform plasma processing on an area substrate uniformly and at high speed is disclosed (for example, see Patent Document 1).

  In addition, a method is shown that has uniform vacuum processing characteristics over a wide range by simultaneously supplying high-frequency power of at least two different frequencies (see, for example, Patent Document 2).

  In addition, the substrate to be treated is placed in a depressurizable reaction vessel at least partially made of a conductive member, and the gas introduced into the reaction vessel is decomposed by the high frequency power applied to the high frequency electrode installed outside the reaction vessel. In the plasma processing apparatus for forming plasma and processing the substrate, the end surface of the auxiliary substrate facing the conductive member forming a part of the reaction vessel is substantially parallel to the conductive member, and the end surface of the auxiliary substrate and the conductive member A plasma processing apparatus and method have been shown in which the plasma characteristics, the uniformity of plasma processing, and the long-term stability of plasma are improved by setting the distance from the conductive member to 1 mm to 30 mm (for example, Patent Document 3). reference).

  FIG. 4 shows a schematic configuration diagram of such a deposited film forming apparatus.

4A is a schematic cross-sectional view, and FIG. 4B is a schematic cross-sectional view taken along the cutting line AA ′ of FIG. 4A. The reaction vessel 401 is composed of 401 (a) and 401 (b), 401 (a) is made of a dielectric member, and an exhaust pipe 409 is connected to the lower part of the reaction vessel 401, and the other end of the exhaust pipe 409 Is connected to an exhaust device (not shown) (for example, a vacuum pump). A plurality of cylindrical substrates 405 (consisting of a main body 405 (a) and an auxiliary substrate 405 (b)) on which the deposited film is formed are arranged on the same circumference so as to surround the central portion of the reaction vessel 401. Is arranged. The plurality of cylindrical substrates 405 are respectively held by a substrate support 406 having a substrate heating heater 407 built therein. In the reaction vessel 401, gas supply means 410 connected to a gas supply device (not shown) composed of gas cylinders such as SiH ₄ , GeH ₄ , H ₂ , CH ₄ , B ₂ H ₆ , PH ₃ , Ar, and He. A high frequency electrode 402 is installed outside the reaction vessel 401. A high frequency power source 403 is connected to the high frequency electrode 402 via a matching box 404 and a high frequency power branching means 412. Further, the cylindrical base 405 can be rotated by each rotating mechanism 408.
JP 9-310181 A Japanese Patent Laid-Open No. 2002-241944 Japanese Patent Laid-Open No. 2003-82466

  By such a conventional electrophotographic photosensitive member forming method and apparatus, it is possible to shorten the substrate processing time by increasing the film deposition rate, increase the number of simultaneously processable substrates, and improve the uniformity and reproducibility of deposited film characteristics. It has become possible to obtain an electrophotographic photosensitive member having practical characteristics and uniformity to a certain extent at low production costs. Further, if the inside of the vacuum reaction vessel is strictly cleaned, it is possible to obtain an electrophotographic photosensitive member having a certain number of defects.

  However, the level of market demand for products using these deposited films is increasing day by day, and higher quality deposited films are required to meet this demand.

  In other words, in recent years, demand for image defects is more severe than ever in color copying machines, for which demand is rapidly expanding. For example, even in a product that requires a relatively thick deposited film with a large area, such as an electrophotographic photoreceptor, abnormal growth of the deposited film that occurs in the manufacturing process of the photoreceptor is directly linked to image defects, and therefore can be eliminated as much as possible. It has been demanded. Therefore, there remains a problem to be solved that it is difficult to obtain a deposited film with a uniform film quality, satisfying the requirements of optical and electrical characteristics, and with few image defects at the time of image formation by an electrophotographic process. Yes.

  The abnormal growth of the deposited film that occurs in the manufacturing process of the photosensitive member is as follows.

  The a-Si: H film has the property that when dust of the order of several μm adheres to the surface of the substrate, abnormal growth, that is, so-called “spherical protrusions” grow with the dust as a nucleus during film formation. . Spherical protrusions have a shape that is a reversal of the conical shape starting from dust, and there are many localized levels at the interface between the normal deposition part and the spherical protrusion part, so the resistance decreases, and the charged charge passes through the interface. Therefore, it has the property of coming out to the substrate side. For this reason, the part with the spherical protrusion appears as a white point in the solid black image on the image (in the case of reversal development, it appears as a black point in the solid white image). The so-called “pochi” image defect has a stricter standard every year, and depending on the size, even if there are several A3 sheets, they may be treated as defective. Furthermore, the standard becomes more stringent when mounted on a color copying machine, and even if one is present on A3 paper, it may be defective.

  Since these spherical protrusions start from dust, the substrate to be used is precisely cleaned before film formation, and all the steps to be installed in the film formation apparatus are performed in a clean room or under vacuum. In this way, efforts have been made to reduce the amount of dust adhering to the substrate before the start of film formation, and the effect has been improved. However, the cause of the generation of the spherical protrusion is not only the dust adhering to the substrate. That is, when an a-Si: H photoconductor is manufactured, the required film thickness is very large, from several μm to several tens of μm, and therefore the film formation time ranges from several hours to several tens of hours. During this time, the a-Si: H film is deposited not only on the substrate but also on the film forming furnace wall and the structure in the film forming furnace. Since these furnace walls and structures do not have a controlled surface like the substrate, the adhesion is weak in some cases, and film peeling may occur during film formation over a long period of time. If even a slight peeling occurs during the film formation, it becomes dust and adheres to the surface of the photoreceptor being deposited, and this causes the abnormal growth of the spherical projections. Therefore, in order to maintain a high yield, careful management is required not only for management of the substrate before film formation, but also for prevention of film peeling in the film formation furnace during film formation. : H The manufacture of the photoconductor was made difficult.

  In addition to image defects, there is a growing demand for image quality.

  Especially in digital electrophotographic devices and color electrophotographic devices, not only textual manuscripts but also photographs, pictures, design drawings, etc. are frequently copied, so many manuscripts including halftones are copied, Minor variations in image density are also visually evident, as are image defects. Therefore, the reduction in image density unevenness is strongly demanded more than ever. In order to improve the characteristics of the photosensitive member, the conditions for forming the deposited film and the deposited film stack structure have been optimized, but at the same time, improvements in terms of the deposited film forming apparatus and the deposited film forming method are also strongly desired. ing.

  Under such circumstances, there is still room for improvement in the above-described conventional deposited film forming apparatus and deposited film forming method with respect to reducing image defects and improving deposited film characteristics and uniformity. is there.

[Object of the invention]
The object of the present invention is to overcome the problems associated with the conventional electrophotographic photosensitive member as described above, and to manufacture an electrophotographic photosensitive member that is easy to use with high image quality with few image defects, which can be manufactured inexpensively, stably and with good yield. An object of the present invention is to provide a deposited film forming apparatus and a deposited film forming method that can be performed.

  As a result of diligent investigations to achieve the above object, the inventors of the present invention firstly, in a deposited film forming apparatus and a deposited film forming method, a cylinder is placed in a depressurizable reaction vessel at least partially made of a dielectric member. When the cylindrical substrates are arranged at equal intervals on the same circumference and high frequency power is introduced from outside the reaction vessel, the shape of the space surrounded by the cylindrical substrate is devised, and the conductive material constituting a part of the reaction vessel By optimizing the distance between the upper surface of the auxiliary substrate and the upper surface of the auxiliary substrate, it was found that a deposited film having good characteristics can be uniformly formed on a plurality of substrates, and the present invention has been completed. Is.

  That is, the present invention comprises a reaction vessel that can be depressurized, at least partly composed of a dielectric member, a plurality of cylindrical substrates and raw material gas introduction means disposed on the same circumference inside the reaction vessel, A plurality of high-frequency electrodes arranged outside the reaction vessel, a high-frequency power is applied to the high-frequency electrode, and a glow discharge is generated in the reaction vessel, so that the source gas introduced into the reaction vessel In a deposited film forming apparatus that decomposes and forms deposited films on the plurality of cylindrical substrates, a cylindrical member is installed at the approximate center of the reaction vessel, and a conductive upper lid that constitutes a part of the reaction vessel; An apparatus and a method for forming a deposited film, characterized in that the distance from the upper end surface of the auxiliary substrate facing the conductive upper lid is 10 mm or more and 150 mm or less.

  The present invention capable of obtaining such effects will be described in detail below.

  In the deposited film forming apparatus in which a plurality of cylindrical substrates are arranged at equal intervals on the same circumference and the high-frequency power introducing means is arranged outside the reaction vessel, the adhesion of the deposited film is improved. When considering a method for reducing the generation of dust, it was noticed that the configuration around the cylindrical substrate was asymmetric. Roughly speaking, this asymmetry can be considered by dividing it into the inside and the outside of the arrangement circle of the cylindrical substrate, and the effect of this was confirmed.

  That is, in the normal film formation, the rotating cylindrical substrate was placed in a stationary state in order to deposit uniformly in the circumferential direction to form a deposited film, and the distribution of spherical protrusions in the circumferential direction of the cylindrical substrate was examined. As a result, it was found that the number of spherical protrusions did not occur evenly in the circumferential direction, but a large number occurred inside the arrangement circle of the cylindrical substrate. In other words, in such a deposited film forming apparatus, in order to improve the spherical protrusions and reduce image defects to a level that can withstand use in a color copying machine, the inner spherical protrusions are mainly reduced. Confirmed that there is a need to do.

  The details of the reason why there are many spherical protrusions on the inner side of the arrangement circle of the cylindrical substrate are currently unknown, but when looking at the structure of the deposited film forming device, the outside of the circumference where the cylindrical substrates are arranged is that of the deposited film forming device. Whereas the furnace wall faces, there is no furnace wall on the inside, and this difference in the shape of the space generates a difference in the film stress of the deposited film, which affects the adhesion. I imagine that there will be.

  On the other hand, when the distribution of the number of spherical protrusions in the circumferential direction of the cylindrical substrate was examined in the deposited film forming apparatus in which the cylindrical member according to the present invention was installed in the internal space of the plurality of cylindrical substrates, The incidence of protrusions was reduced, and it was found that the distribution of spherical protrusions was almost uniform in the circumferential direction. This is thought to be because the cylindrical member installed in the internal space of the plurality of cylindrical bases has a function corresponding to the furnace wall on the inner side, and the internal and external structures are symmetric while being simulated.

  When the cylindrical member is made of the same dielectric material as the furnace wall, the effect of reducing the spherical protrusion is most apparent when the distance between the furnace wall and the cylindrical base is substantially equal to the distance between the cylindrical base and the cylindrical member. It was. However, as a side effect at this time, a deposited film also adheres to the cylindrical member, and thus a phenomenon has occurred in which the deposition rate of the film deposited on the cylindrical substrate is slightly reduced. Therefore, the present inventors diligently studied a configuration in which both the spherical protrusion improvement effect and the maintenance of the deposition rate are compatible.

  As a result, by changing the material of the cylindrical member from a dielectric material to a conductive material (e.g. metal) and grounding, the outer diameter of the cylindrical member can be reduced while maintaining the effect of reducing spherical protrusions. It turned out to be possible. On the other hand, it was confirmed that the deposition rate was greatly improved by reducing the outer diameter of the cylindrical member.

  Furthermore, when the present inventors have considered the reduction of image defects in the other deposited film, the conductive upper lid constituting a part of the reaction vessel, the upper end surface of the auxiliary substrate attached to the upper portion of the cylindrical substrate, It has been found that a further effect can be obtained by optimizing the interval. Conventionally, the distance between the conductive upper lid and the upper end surface of the auxiliary base has been configured to be as close as possible in order to prevent the discharge from wrapping around, but conversely, this distance is increased to reduce mutual interaction. Surprisingly, it was found that the adhesion of dust was prevented, leading to a significant reduction in image defects. Although the details of this reason are unknown, it is speculated that the electric field distribution of the cylindrical substrate is changed by optimizing the distance between the conductive upper lid and the auxiliary substrate.

  Furthermore, it has been found that optimizing the distance between the conductive top lid and the upper end surface of the auxiliary base improves the variation in the characteristics of the cylindrical base in the axial direction as an unexpected effect. The mechanism is speculative, but it is thought that the change in the electric field distribution of the cylindrical substrate is also related.

  In the present invention, since the cylindrical member is installed in the approximate center of the reaction vessel, a plurality of substrates are provided in a range different from the distance between the end surface of the auxiliary substrate and the conductive member described in Patent Document 3 mentioned above. In addition, it is possible to uniformly form a deposited film having few image defects and good characteristics.

  The present invention has been completed by the above process.

  According to the present invention, a cylindrical substrate is arranged at equal intervals on the same circumference in a reaction vessel at least partially composed of a dielectric member, and a plurality of high frequency powers are introduced from outside the reaction vessel. In an apparatus and method for forming a deposited film having good characteristics on a substrate, a cylindrical member is installed in the approximate center of the reaction vessel, and further, a conductive upper lid that constitutes a part of the reaction vessel, and the conductive upper lid. By setting the distance from the upper end surface of the auxiliary substrate to 10 mm or more and 150 mm or less, it is possible to suppress unevenness in the potential characteristics of the electrophotographic photosensitive member and to significantly reduce the spherical protrusions that cause image defects. .

  Hereinafter, a deposited film forming apparatus and a deposited film forming method of the present invention will be described in detail with reference to the drawings.

  FIG. 1 schematically shows an example of a highly productive apparatus capable of simultaneously forming a plurality of electrophotographic light-receiving members in the deposited film forming apparatus and method of the present invention.

  FIG. 1A is a schematic cross-sectional view, and FIG. 1B is a schematic cross-sectional view taken along the cutting line A-A ′ of FIG. The deposited film manufacturing apparatus shown in FIG. 1 limits the film formation space in which the source gas is decomposed to a cylindrical region by a reaction vessel 101 composed of a dielectric member 101 (a) and a conductive upper lid 101 (b). The center axis of the film formation space is configured to pass through the center of the cylindrical substrate 105 (a) arrangement circle, and the high-frequency power introduction means 102 installed outside the arrangement circle of the cylindrical substrate 105 (a) is a dielectric member 101. By positioning it outside (a), the utilization efficiency of the source gas can be improved, and at the same time, defects in the formed deposited film can be reduced.

An exhaust pipe 109 is connected to the lower part of the reaction vessel 101, and the other end of the exhaust pipe 109 is connected to an exhaust device (not shown) (for example, a vacuum pump). A plurality of cylindrical substrates 105 (a) on which a deposited film is formed are arranged on the same circumference so as to be parallel to each other so as to surround the central portion of the reaction vessel 101. The plurality of cylindrical substrates 105 (a) are respectively held by a substrate support 106 incorporating a substrate heating heater 107. In the reaction vessel 101, there is a cylindrical member 111 made of a conductive material at the approximate center, a gas cylinder made of SiH ₄ , GeH ₄ , H ₂ , CH ₄ , B ₂ H ₆ , PH ₃ , Ar, He or the like. There is a gas supply means 110 connected to the illustrated gas supply apparatus, and a high-frequency power introduction means 102 is installed outside the reaction vessel 101. A high frequency power supply 103 is connected to the high frequency power introducing means 102 through a matching box 104 and a high frequency power branching means 112. Further, the cylindrical base body 105 (a) can be rotated by each rotating mechanism 108.

  In the present invention, in order to maintain the unevenness of the characteristics of the deposited film and the effect of improving the spherical protrusion, it is necessary to install a cylindrical member at the approximate center of the reaction vessel, and further, the conductivity constituting a part of the reaction vessel. The distance d between the upper lid 101 (b) and the upper end surface of the auxiliary base body 105 (b) attached to the upper part of the cylindrical base body 105 (a) opposite to the upper cover 101 (b) needs to be in a certain range. Details of these positional relationships are shown in FIG. Each code corresponds to the last two digits. That is, it has been found that it is effective to set the interval to 10 mm to 150 mm, preferably 31 mm to 100 mm.

  If the distance is too small, it is difficult to obtain the effect of the present invention as described in the above-mentioned estimation. If the distance is too large, the space between the conductive upper lid and the upper end surface of the auxiliary substrate becomes too large and is formed of a dielectric. The temperature distribution due to the difference in plasma density tends to occur in the axial direction inside the reaction vessel, and film peeling may occur. In addition, since the reaction vessel itself becomes large, there is a disadvantage that the investment cost of the apparatus becomes large.

  Here, the cylindrical member 111 is made of a conductive material. Any material can be used for the cylindrical member as long as it is a conductive material. However, metal materials such as aluminum, iron, stainless steel, gold, silver, copper, nickel, chromium, and titanium are easy to process and highly durable. It is also preferable in terms of convenience. In addition, composite materials composed of two or more of these materials are also preferably used.

  In the deposited film forming apparatus of the present invention, the cylindrical member 111 needs to be electrically grounded. By grounding, it is presumed that the high-frequency power introducing means 102 is acting as a pseudo counter electrode. On the contrary, since the cylindrical member 111 can sufficiently obtain the effects of the present invention simply by being grounded, for example, another high-frequency power source is prepared for the cylindrical member 111, Since there is no cost or labor for branching and aligning the output between the power introduction means 102 and the cylindrical member 111, the cost of the deposited film forming apparatus 101 itself can be reduced. This also leads to a reduction in manufacturing costs.

  The auxiliary base 105 (b) is made of copper, aluminum, gold, silver, platinum, lead, nickel, cobalt, iron, chromium, molybdenum, titanium, stainless steel, etc., as it is conductive and has good heat conductivity. Is preferred. A composite material composed of two or more of these materials is also preferably used, but it is more preferable to use the same material as that of the cylindrical substrate 105 (a). The length L of the auxiliary base 105 (b) is determined so that the distance d between the auxiliary base 105 (b) and the conductive upper lid 101 (b) falls within the scope of the present invention. This detail is also shown in FIG.

  The cylindrical substrate 105 (a) may be any material having a material corresponding to the purpose of use. Of the materials, copper, aluminum, gold, silver, platinum, lead, nickel, cobalt, iron, chromium, molybdenum, titanium, and stainless steel are preferable because of their good electrical conductivity. Furthermore, a composite material composed of two or more of these materials is also desirable for improving heat resistance.

  In the present invention, the effect of reducing image defects is particularly high when the frequency of the high frequency power is in the range of 50 to 450 MHz. This seems to be due to the rapid increase in pressure at which plasma can be stably generated in a frequency region lower than 50 MHz. According to the study by the present inventors, for example, when the frequency is 13.56 MHz, it is confirmed that the pressure at which plasma can be stably generated is about one to half digits higher than that when the frequency is 50 MHz or more. ing. At such a high pressure, particles such as polysilane are easily generated in the film formation space, and when these particles are taken into the deposited film, spherical protrusions are easily generated. In the present invention, since the plasma generation pressure can be sufficiently lowered by setting the frequency of the high frequency power to 50 MHz or more, the generation probability of particles is drastically reduced, and a good deposited film is formed over the entire circumference of the cylindrical substrate. It is considered a thing.

  Further, in a frequency region higher than 450 MHz, the uniformity of the film characteristics is different from the case of 450 MHz or less due to a decrease in plasma uniformity. If there is a difference in the uniformity of such film characteristics, there will also be a difference in the stress of the film at the same time, and film peeling is likely to occur near the boundary. For this reason, image defects are likely to deteriorate. In the frequency region where the frequency is higher than 450 MHz, the power absorption near the power introduction means is large, and electrons are most frequently generated here, so that plasma non-uniformity is likely to occur and the characteristics of the deposited film are uneven. Easy to connect. At frequencies of 450 MHz or less, extreme power absorption in the vicinity of the power introduction means is unlikely to occur, resulting in high plasma uniformity and even film property uniformity.

  In the present invention, by setting the high frequency power to a superposition frequency obtained by superposing two or more frequencies in the range of 50 to 450 MHz, it is possible to obtain further effects in reducing image defects and uniformity of characteristics. it can.

  As the high frequency power source 103, any device can be suitably used as long as it can generate high frequency power suitable for the apparatus. Further, the output fluctuation rate of the high frequency power supply 103 is not particularly limited.

  The matching box 104 used in the present invention can be suitably used in any configuration as long as the high frequency power supply 103 and the load can be matched. In addition, as a method of taking the alignment, an automatically adjusted method is preferable in order to avoid complexity at the time of manufacturing, but even if manually adjusted, there is no influence on the effect of the present invention. . In addition, as for the position where the matching box 104 is disposed, there is no problem wherever the matching box 104 can be placed within the range where matching can be achieved, but the layout is made so that the inductance of the wiring from the matching box 104 to the high-frequency power introducing means 102 is made as small as possible. This is desirable because it enables matching under a wide range of load conditions.

  Copper, aluminum, gold, silver, platinum, lead, nickel, cobalt, iron, chrome, molybdenum, titanium, stainless steel, etc. are good materials for heat conduction and high-frequency power introduction means 102 and high-frequency power branch means 112. It is preferable because it is good. A composite material composed of two or more of these materials is also preferably used.

  More preferably, the number of high-frequency power introducing means 102 is the same as the cylindrical base body 105 (a) or 1/2 of the cylindrical base body 105 (a). When the cylindrical base 105 (a) is halved, it is optimal to arrange the cylindrical bases 105 (a) so that the distances between two adjacent cylindrical bases 105 (a) are equal. The supply of power to the plurality of high-frequency power introducing means 102 can be performed, for example, by branching the power supply path by the high-frequency power branching means 112 after passing through the matching box 104 from one high-frequency power supply 103. Further, for example, after a power supply path is branched from one high-frequency power source 103 by the high-frequency power branching means 112, power may be supplied through a plurality of matching boxes, and further, for example, individual high-frequency power introducing means 102 A separate high frequency power supply and a matching box may be provided for each, but the frequency of the high frequency power introduced from all the high frequency power introduction means 102 is completely the same, the cost of the device, the size of the device Therefore, it is preferable that power is supplied to all high-frequency power introducing means 102 from one high-frequency power source.

  As the high-frequency power introducing means 102, a rod-like, cylindrical, spherical, plate-like cathode electrode, a means for providing an opening in the outer conductor of the coaxial structure, and supplying power from there can be used.

  The material of the dielectric member 101 (a) of the reaction vessel 101 used in the present invention is preferably a ceramic material, specifically, alumina, zirconia, mullite, cordierite, silicon carbide, boron nitride, nitride. It is preferable to use a material containing at least one of aluminum, silicon nitride, and the like because the deposited film has high adhesion and is effective for preventing the occurrence of spherical protrusions. Among these, alumina, boron nitride, and aluminum nitride are more preferable because they have excellent electrical characteristics such as dielectric loss tangent and insulation resistance, and have low absorption of high-frequency power.

  Further, when producing an electrophotographic photosensitive member from the ease of processing, the shape of the dielectric member 101 (a) is preferably a cylindrical shape, but if necessary, an elliptical shape or a polygonal shape may be used. What is necessary is just to select a shape according to the member to produce.

  At least a part of the surface of the dielectric member 101 (a) of the reaction vessel 101 preferably has an arithmetic average roughness (Ra) in the range of 1 μm to 20 μm in order to increase the effect of reducing spherical protrusions. In addition, Ra is controlled within the above range, and the average inclination angle (θa) is controlled within the range of 9 degrees to 20 degrees, or Ra is set within the above range, and at the same time, the average interval (S) between the local peaks is 30 μm. More preferably, it is in the range of 100 μm or less. Further, by making Ra, θa, and S all within the above ranges, the image defect improvement effect becomes particularly remarkable.

  The conductive upper lid 101 (b) of the reaction vessel 101 is made of conductive material such as copper, aluminum, gold, silver, platinum, lead, nickel, cobalt, iron, chromium, molybdenum, titanium, and stainless steel. This is preferable because of good conduction. A composite material composed of two or more of these materials is also preferably used.

  The substrate heating heater 107 may be a heating element having a vacuum specification. Specifically, it is an electric resistance heating element such as a sheathed heater, a plate heater, a ceramic heater, or a carbon heater, and heat radiation such as a halogen lamp or an infrared lamp. Examples include a heating element using a heat exchange means using a lamp heating element, liquid, gas, or the like as a heating medium. As the surface material of the substrate heating heater 107, metals such as stainless steel, nickel, aluminum, and copper, ceramics, heat resistant polymer resins, and the like can be used.

  Formation of a deposited film using the deposited film forming apparatus of FIG. 1 is performed, for example, as follows.

  First, the cylindrical substrate 105 (a) held by the substrate holder 106 is installed in the reaction vessel 101, and the inside of the reaction vessel 101 is exhausted through an exhaust port 109 by an exhaust device (not shown). Subsequently, the cylindrical base 105 (a) is heated and controlled to a predetermined temperature by the heating element 107.

  When the cylindrical substrate 105 (a) reaches a predetermined temperature, the source gas is introduced into the reaction vessel 101 through the source gas supply means 110. After confirming that the flow rate of the raw material gas becomes the set flow rate and the pressure in the reaction vessel 101 is stable, predetermined high frequency power is supplied from the high frequency power source 103 to the high frequency power introducing means 102 via the matching box 104. The supplied high-frequency power causes glow discharge in the reaction vessel 101, and the source gas is excited and dissociated to form a deposited film on the cylindrical substrate 105 (a).

  After the formation of the desired film thickness, the supply of the high frequency power is stopped, and then the supply of the source gas is stopped to finish the formation of the deposited film. When forming a multi-layered deposited film, the same operation is repeated a plurality of times. In this case, in each layer, as described above, once the formation of one layer is completed, the discharge is once stopped completely, and after the setting is changed to the gas flow rate and pressure of the next layer, the discharge occurs again. The next layer may be formed, or a plurality of layers may be continuously formed by gradually changing the gas flow rate, pressure, and high-frequency power to the set values of the next layer within a certain period of time after the formation of one layer. It may be formed. In addition, it is preferable to sufficiently evacuate the residual gas in the reaction vessel 101 once between the layers, because there is no fear of contamination when different gas species are used between the layers.

  During the formation of the deposited film, the cylindrical substrate 105 (a) may be rotated at a predetermined speed by the rotation mechanism 108 as necessary.

  By using the present invention, for example, an a-Si: H-based electrophotographic light-receiving member as shown in FIG. 3 can be formed.

  An electrophotographic photosensitive member 300 shown in FIG. 3A has amorphous silicon (hereinafter referred to as “a-Si: H, X”) containing a hydrogen atom or a halogen atom as a constituent element on a support 301. A photoconductive layer 302 having photoconductivity is provided.

  An electrophotographic photosensitive member 300 shown in FIG. 3B has a photoconductive layer 302 made of a-Si: H, X and having photoconductivity on a support 301, and an a-Si: H system (or amorphous). A carbon-based) surface layer 303 is provided.

  The electrophotographic photosensitive member 300 shown in FIG. 3 (c) has a photoconductive material composed of a-Si: H based charge injection blocking layer 304 and a-Si: H, X on a support 301. A layer 302 and an a-Si: H-based (or amorphous carbon-based) surface layer 303 are provided.

  In the electrophotographic photosensitive member 300 shown in FIG. 3D, a photoconductive layer 302 is provided on a support 301. The photoconductive layer 302 includes a charge generation layer 305 and a charge transport layer 306 made of a-Si: H, X, and an a-Si: H-based (or amorphous carbon-based) surface layer 303 is provided thereon. Yes.

  EXAMPLES Hereinafter, although an Example demonstrates this invention in more detail, this invention is not restrict | limited at all by these.

(Example 1)
Using the deposited film forming apparatus in which an aluminum cylindrical member is installed in the center of the discharge space shown in FIG. 1, the cylindrical base 105 (a) is shown in Table 1 on a cylindrical aluminum cylinder having a diameter of 80 mm and a length of 358 mm. According to the conditions, an electrophotographic photosensitive member comprising a charge injection blocking layer, a photoconductive layer, and a surface layer was formed.

  In this embodiment, the oscillation frequency of the high frequency power source 103 is 105 MHz, and the distance d between the conductive upper lid and the upper end surface of the auxiliary substrate is 50 mm.

(Comparative Example 1)
Using a conventional deposited film forming apparatus having no cylindrical member in the discharge space shown in FIG. 4, a photoreceptor composed of a charge injection blocking layer, a photoconductive layer, and a surface layer is formed in the same manner as in Example 1 under the conditions shown in Table 1. Produced. Also in this comparative example, the oscillation frequency of the high frequency power supply 403 is 105 MHz, and the distance d between the conductive upper lid and the upper end surface of the auxiliary substrate is 50 mm.

(Evaluation)
The a-Si: H photoconductor produced in this way was installed in a Canon copier iR5000 modified for this test, and the characteristics of the photoconductor were evaluated. The evaluation items were two items, “the number of spherical protrusions” and “image defect”. Each item was evaluated by the following specific evaluation method, and the results are shown in Table 2.

(Number of spherical protrusions)
The surface of the obtained photoreceptor was observed with an optical microscope, and the number of spherical protrusions was counted. Specifically, the diameter was 10 μm or more and less than 20 μm and the number of spherical protrusions of 20 μm or more was counted, and the number per 10 cm ² was examined.

The obtained results were ranked by the reduction rate of the spherical protrusions based on the value in Comparative Example 1.

◎… More than 80% decrease
◎ ~ ○ ... 60% or more and less than 80% reduction
○… Reduction of 40% or more and less than 60%
○ ～ △… 10% or more and less than 40% decrease
△… 0% or more and less than 10% decrease
×… Increased.

(Image defect)
Installed an electrophotographic photosensitive member on Canon iR5000, a solid black image under the conditions of a process speed of 265 mm / sec, pre-exposure (LED with a wavelength of 660 nm), a light intensity of 4 lx · s, and a charger current value of 1000 μA. The image obtained at a density of 100% was observed, and an A3 size black original was copied. The images thus obtained were observed, and the number of white spots caused by spherical protrusions having a diameter of 0.3 mm or more was counted.

  The evaluation image has a transmission density of 2.0. The transmission density of the image was measured using an image densitometer: Macbeth RD914, measured at approximately the center of the image, and an image of 2.0 was used.

The obtained results were ranked based on the image defect reduction rate based on the value in Comparative Example 1.

◎… More than 80% decrease
◎ ~ ○ ... 60% or more and less than 80% reduction
○… Reduction of 40% or more and less than 60%
○ ～ △… 10% or more and less than 40% decrease
△… 0% or more and less than 10% decrease
×… Increased.

(Example 2)
Using the deposited film forming apparatus in which an aluminum cylindrical member is installed in the center of the discharge space shown in FIG. 1, the cylindrical base 105 (a) is shown in Table 1 on a cylindrical aluminum cylinder having a diameter of 80 mm and a length of 358 mm. According to the conditions, an electrophotographic photosensitive member made of an a-Si: H deposited film was formed by the above-described deposited film forming method.

  In this embodiment, the oscillation frequency of the high-frequency power source 103 is 20, 50, 70, 105, 250, 450, 500 MHz, and several types are obtained by changing the distance d between the conductive upper cover and the upper end surface of the auxiliary substrate under each condition. An electrophotographic photoreceptor was formed for the combination.

(Comparative Example 2)
A photoconductor comprising a charge injection blocking layer, a photoconductive layer and a surface layer was prepared in the same manner as in Example 1 except that the distance d between the conductive upper lid and the upper end surface of the auxiliary substrate was 2 mm and 160 mm.

(Evaluation)
The a-Si: H photoconductor produced in this way was installed in a Canon copier iR5000 modified for this test, and the characteristics of the photoconductor were evaluated. The evaluation items are “spherical projection number”, “image defect”, and “image density unevenness”, and “spherical projection number” and “image defect” are obtained by evaluating in the same procedure as in Example 1. The results were ranked according to the reduction rate based on the value in Comparative Example 2 (condition of 2 mm spacing and 20 MHz).

(Image density unevenness)
First, after adjusting the main charger current so that the dark part potential at the developing unit position becomes a constant value, a predetermined white paper with a reflection density of 0.01 or less is used for the original, and the bright part potential at the developing unit position becomes a predetermined value. The amount of image exposure was adjusted so that Subsequently, a Canon halftone chart (part number: FY9-9042) was placed on the document table, and the evaluation was made based on the difference between the maximum value and the minimum value of the reflection density in the entire area on the copy image obtained when copying. The evaluation result was the average value of all the photoconductors.

  The evaluation result of the image density unevenness was determined by the degree of improvement of each item, based on the value in Comparative Example 2 (interval 2 mm, 20 MHz condition).

◎… 40% or better
◎ ~ ○ ... 30% to less than 40% improvement
○… 20% to less than 30% improvement
○ ~ △ ... Improvement of 10% or more and less than 20%
△… Improvement of 0% or more and less than 10%
×… worse

  In the evaluation results, all the items clearly differed between Example 2 and Comparative Example 2, which are within the scope of the present invention. In particular, it can be seen that spherical protrusions are remarkably improved by setting the distance d to 31 mm to 100 mm in relatively small ones of 10 μm or more and less than 20 μm.

Example 3
Using the deposited film forming apparatus in which an aluminum cylindrical member is installed in the center of the discharge space shown in FIG. 1, the cylindrical base 105 (a) is shown in Table 1 on a cylindrical aluminum cylinder having a diameter of 80 mm and a length of 358 mm. According to the conditions, an electrophotographic photosensitive member made of an a-Si: H deposited film was formed by the above-described deposited film forming method.

  In this embodiment, two types of frequencies of 105 MHz and 50 MHz are simultaneously oscillated from the high frequency power source 103. Each output was 50% of the total output.

  In this embodiment, the photosensitive member was produced by changing the distance d between the conductive upper lid and the upper end surface of the auxiliary substrate in the range of 10 to 150 mm.

  The photoconductors prepared in this example were evaluated for spherical protrusions in the same manner as in Example 2.

  As in Example 2, the obtained results were ranked according to the reduction rate of the spherical protrusions based on the values in Comparative Example 2 (conditions of interval 2 mm, 20 MHz).

  The results are shown in Table 7.

  As shown in Table 7, it can be seen that in this embodiment, the number of spherical protrusions is more significantly reduced by superimposing two types of frequencies on the high-frequency power. This is presumably because the electric field distribution of the cylindrical substrate has changed to a more favorable state by setting the high frequency power to a superposition frequency of two or more frequencies.

  As described above, according to the present invention, cylindrical substrates are arranged at equal intervals on the same circumference in a reaction vessel at least partly composed of a dielectric member, and high frequency power is introduced from outside the reaction vessel. Thus, in a deposited film forming apparatus and method having good characteristics on a plurality of substrates, a cylindrical member is installed at the approximate center of the reaction vessel, and a conductive upper lid constituting a part of the reaction vessel; By setting the distance from the upper end surface of the auxiliary substrate facing the conductive upper lid to 10 mm or more and 150 mm or less, the unevenness of the electric potential characteristics of the electrophotographic photosensitive member is suppressed and the spherical projections causing image defects are greatly reduced. Became possible.

It is the typical block diagram which showed an example of the deposited film formation apparatus of this invention. It is a typical block diagram which shows the positional relationship of an electroconductive upper cover and a cap. It is the figure which showed an example of the layer structure of the light-receiving member for electrophotography which can be formed by this invention. It is the typical block diagram which showed an example of the conventional deposited film formation apparatus.

Explanation of symbols

101 reaction vessel
101 (a) Dielectric material
101 (b) Conductive top cover
102 High-frequency power introduction means
103 high frequency power supply
104 matching box
105 (a) Cylindrical substrate
105 (b) Auxiliary substrate
106 Substrate support
107 Substrate heating heater
108 Rotating mechanism
109 Exhaust piping
110 Gas supply means
111 Cylindrical member
112 High-frequency power branching means
201 (b) Conductive top cover
205 (a) Cylindrical substrate
205 (b) Auxiliary substrate
211 Cylindrical member
300 Electrophotographic photoconductor
301 Support
302 Photoconductive layer
303 surface layer
304 Charge injection blocking layer
305 Charge generation layer
306 Charge transport layer
401 reaction vessel
401 (a) Dielectric material
401 (b) Conductive top cover
402 High frequency power introduction means
403 high frequency power supply
404 matching box
405 (a) Cylindrical substrate
405 (b) Auxiliary substrate
406 Substrate support
407 Substrate heating heater
408 Rotating mechanism
409 Exhaust piping
410 Gas supply means
412 High-frequency power branching means

Claims (9)

A reaction vessel capable of being depressurized, at least partly composed of a dielectric member, a plurality of cylindrical substrates and raw material gas introduction means arranged on the same circumference inside the reaction vessel, and arranged outside the reaction vessel A plurality of high-frequency electrodes, and applying a high-frequency power to the high-frequency electrodes to generate a glow discharge in the reaction vessel, thereby decomposing the raw material gas introduced into the reaction vessel, In a deposited film forming apparatus for forming a deposited film on a cylindrical substrate,
A cylindrical member is installed at the approximate center of the reaction vessel, and the distance between the conductive upper lid constituting a part of the reaction vessel and the upper end surface of the auxiliary substrate facing the conductive upper lid is 10 mm or more and 150 mm or less. A deposited film forming apparatus characterized by the above.   The deposited film forming apparatus according to claim 1, wherein a distance between the upper end surface of the auxiliary base and the conductive upper lid is set to 31 mm or more and 100 mm or less.   The deposited film forming apparatus according to claim 1, wherein the cylindrical member is conductive.   The deposition according to any one of claims 1 to 3, wherein the high-frequency power introduction means are installed at equal intervals on a concentric circle having the same center as the arrangement circle of the plurality of cylindrical substrates. Film forming device.   5. The deposited film forming apparatus according to claim 1, wherein a frequency of the high-frequency power is in a range of 50 to 450 MHz.   The deposited film forming apparatus according to claim 5, wherein the high-frequency power is a plurality of high-frequency powers having different frequencies.   The deposited film forming apparatus according to claim 1, wherein the deposited films formed on the plurality of cylindrical substrates are non-single-crystal materials having silicon atoms as a base material. .   8. The deposited film forming apparatus according to claim 1, wherein the deposited film forming apparatus is used for manufacturing an electrophotographic photosensitive member.   A deposited film forming method using the deposited film forming apparatus according to claim 1.

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