JP4901264B2 - Plasma CVD equipment - Google Patents

Description

  The present invention relates to a plasma CVD apparatus for decomposing and activating a source gas to form a thin film on a cylindrical substrate.

  The CVD method is often used for film formation of various semiconductor devices. There are various CVD methods, and typical examples thereof include a plasma CVD method, a heating element (catalyst) CVD method, and a thermal CVD method.

  In particular, glow discharge plasma CVD is mainly used for the manufacture of electrophotographic photoreceptors, solar cells, image sensors, photosensors, TFTs (thin film transistors), etc. using amorphous silicon (hereinafter abbreviated as a-Si) materials. The film forming apparatus by the method has been widely used.

  When an electrophotographic photosensitive member is produced by this glow discharge plasma CVD method, a glow discharge plasma CVD apparatus 9 as shown in FIG. 12 is used (see, for example, Patent Document 1).

  The glow discharge plasma CVD apparatus 9 shown in the figure forms an a-Si-based film by glow discharge plasma on a cylindrical conductive substrate 91 disposed almost at the center of a cylindrical vacuum vessel 90. is there. The CVD apparatus 9 uses a conductive base 91 held by a base support 92 via a ring member 93 as a ground electrode, and a hollow cylindrical metal electrode 94 surrounding the base base 92 at an equal distance. This is an electrode for applying high-frequency power. The metal electrode 94 is provided with a gas inlet 95 for introducing a raw material gas for film formation, and the raw material gas introduced through the gas inlet 95 is provided on the inner peripheral surface of the metal electrode 94. The gas blowing holes 94a are blown out toward the conductive substrate 91. A high frequency power is applied between the metal electrode 94 and the conductive substrate 91 by a high frequency power source 96 to cause glow discharge. Inside the substrate support 92, a substrate heating means 97 made of a nichrome wire, a cartridge heater or the like is provided, and the conductive substrate 91 can be heated to a desired temperature. The substrate support 92 and the conductive substrate 91 can be rotated together by a rotation driving means 98 including a rotation motor 98a.

  When an a-Si film is formed on the conductive gas 91 using the plasma CVD apparatus 9, a raw material gas set at a predetermined flow rate and gas ratio passes through the gas blowing hole 94 a from the gas introduction pipe 95. It is introduced between the metal electrode 94 and the conductive substrate 91. On the other hand, the gas pressure in the vacuum vessel 90 is set to a predetermined value by adjusting the exhaust amount from the exhaust port 99 by a vacuum pump (not shown). Then, high frequency power is applied between the metal electrode 94 and the conductive substrate 91 by the high frequency power source 96, and glow discharge plasma is generated between the metal electrode 94 and the conductive substrate 91 to decompose the source gas. Then, an a-Si based film is formed on the conductive substrate 91 set to a desired temperature. At the time of film formation, the conductive substrate 91 is rotated together with the substrate support 92 by the rotation driving means 98, so that the film thickness and film quality in the circumferential direction of the conductive substrate 91 are made uniform.

JP-A-2002-004050

  In recent years, demands for colorization and high image quality have rapidly increased in electrophotographic apparatuses, and electrophotographic photoreceptors are also required to be able to form images with higher quality and uniformity. .

  However, in the plasma CVD apparatus 9 described above, the heat from the substrate heating means 97 is transmitted to the conductive substrate 91 via the substrate support 92, so that the substrate support 92 is made of a material having high thermal conductivity. Is formed. For this reason, heat easily escapes from the end of the conductive base 91 to the base support 92 through the ring member 93, and the temperature of the end of the conductive base 91 tends to be lower than that of the central portion. . As a result, the film quality is nonuniform in the axial direction of the conductive substrate 91. For example, in a portion where the temperature at the start of film formation is lower than the target temperature, the residual potential on the electrophotographic characteristics increases, which causes unevenness in the image image. As described above, when the electrophotographic photosensitive member is formed by the plasma CVD apparatus 9, the characteristic unevenness caused by the non-uniformity of the film quality in the axial direction of the conductive substrate 91 impairs the uniformity of the image image, and the image There is a problem that the quality is lowered, and it is not possible to sufficiently meet the above-described requirements.

  In order to solve such a problem, it is conceivable to set the film forming temperature high. However, in this case, the adhesion between the conductive substrate 91 and the a-Si film is lowered, and the film peeling occurs. Cause.

  The present invention has been made in view of the above-described circumstances, and is capable of forming a film with less unevenness in film quality in the axial direction on a cylindrical substrate, and for electrophotography manufactured by applying the technique. An object of the present invention is to form an image with high quality and uniformity when a photoconductor is used.

In the present invention, in the plasma CVD apparatus for forming a thin film by depositing a decomposition component when the source gas is decomposed by glow discharge on the cylindrical substrate held in the vacuum film formation chamber for film formation, A vacuum film forming chamber is defined as a preheating chamber for preheating the cylindrical substrate, and a linear shape extending along the axial direction of the cylindrical substrate so as to face the outer peripheral surface of the cylindrical substrate. Preheating means including one or a plurality of heating elements made of arranged wires , wherein the heating elements are formed so that, for example, the amount of heat generated at both ends is larger than that at the center. A plasma CVD apparatus is provided.

  Here, the phrase “extending along the axial direction” means that the wire is arranged so as to extend parallel to or substantially parallel to the axial direction outside the cylindrical substrate.

The outgoing hot body, for example can be used by winding the end portions of the wire helically.

  The plasma CVD apparatus of the present invention preferably further includes a plurality of gas blowing holes for blowing an inert gas to the cylindrical substrate in the preheating chamber. The plurality of gas blowing holes, for example, the occupied area in the central region facing the axial central portion of the cylindrical substrate is larger than the occupied area in the end regions facing the both axial ends of the cylindrical substrate. Made big. More specifically, the plurality of gas blowing holes are formed, for example, such that the distribution density in the central region is larger than the distribution density in the end region, or the opening area in the central region is in the end region. It is formed to be larger than the opening area.

  The amount of gas blown out from the plurality of gas blowout holes is, for example, 0.1 sccm to 30 sccm with respect to the diameter of the gas blowout hole of 1.5 mm.

  In the plasma CVD apparatus of the present invention, for example, the preheating chamber is configured to be decompressed to a vacuum state during preheating. The pressure of the preheating chamber at the time of preheating is maintained at 0.1 to 150 Pa, preferably 0.1 to 100 Pa, for example.

  The plasma CVD apparatus of the present invention preferably further includes a pedestal that can be moved from the preheating chamber to the vacuum film forming chamber in a state where the gas blowing plate having a plurality of gas blowing holes is fixed and the cylindrical substrate is held. It is supposed to be provided.

  The plurality of heating elements are preferably arranged so that the amount of heat radiation applied to the plurality of cylindrical substrates arranged in the preheating chamber is uniform.

  The plasma CVD apparatus of the present invention uses a heating element composed of a wire as a heat source for preheating. For this reason, it is possible to raise the temperature to a state where there is little temperature unevenness in the axial direction as compared with the case where the cylindrical substrate is heated using heating means such as a cartridge heater. In particular, when a heating element having a large calorific value at both ends is used, the temperature at the end of the cylindrical substrate, which tends to be low, can be made the same as that at the center. It is possible to further suppress the occurrence of temperature unevenness in the direction.

  In addition, if the temperature unevenness in the axial direction of the cylindrical substrate can be suppressed by preheating, the film formed on the surface of the cylindrical substrate has a uniform film quality in the axial direction of the cylindrical substrate. As a result, in the electrophotographic photosensitive member produced in the plasma CVD apparatus of the present invention, it is possible to suppress the formation of a portion that is formed at a temperature lower than the target temperature, so that the residual potential increases locally. It is also possible to suppress the occurrence of unevenness in the image. Therefore, the plasma CVD apparatus can produce an electrophotographic photosensitive member capable of forming a uniform image, and can meet demands for colorization and high image quality.

  Furthermore, when a wire such as a wire is used for heating the cylindrical substrate, the electric power required for preheating can be reduced compared to the case where the cylindrical substrate is heated using a heating means such as a cartridge heater. it can. As a result, the cylindrical substrate can be preheated at low cost.

  If the plasma CVD apparatus of the present invention further includes a plurality of gas blowing holes for blowing an inert gas to the cylindrical substrate, the shape, arrangement, etc. of the plurality of gas blowing holes can be appropriately selected. Thus, it is possible to suppress the occurrence of temperature unevenness in the axial direction of the cylindrical substrate during preheating. For example, if the occupied area of the plurality of gas blowing holes in the central region is larger than the occupied area of the plurality of gas blowing holes in the end region, the amount of inert gas blown out in the end region is This is smaller than the amount of blown out inert gas. Therefore, the amount of inert gas blown to the end portion of the cylindrical substrate is smaller than the amount of inert gas blown to the center portion of the cylindrical substrate. As a result, the cooling effect with the inert gas is smaller at the end of the cylindrical substrate than at the center. On the other hand, as described above, the end portion of the cylindrical base body tends to have a temperature lower than that of the central portion. Therefore, by reducing the cooling effect at the end portion of the cylindrical base body where the temperature tends to be low, the temperature difference between the central portion and the end portion of the cylindrical base body can be reduced. This makes it possible to appropriately suppress the occurrence of temperature unevenness in the axial direction of the cylindrical substrate during preheating.

  In the plasma CVD apparatus of the present invention, if the amount of gas blown from a plurality of gas blowout holes is 0.1 sccm to 30 sccm with respect to the diameter of the gas blowout holes of 1.5 mm, the cylindrical substrate can be appropriately treated with an inert gas. By cooling, the occurrence of temperature unevenness in the axial direction of the cylindrical substrate can be suppressed. That is, if the flow rate of the inert gas is less than 0.1 sccm, the amount of gas blown out from the gas blowing holes is too small to obtain the required cooling effect, so that the temperature difference between the end portion and the central portion of the cylindrical substrate is sufficiently large. On the other hand, if the flow rate of the inert gas exceeds 30 sccm, the amount of gas blown out from the gas blowing holes is too large, the cooling effect becomes excessive, and the heating efficiency of the cylindrical substrate deteriorates. Although the temperature of the central portion may be lower than that of the end portion and temperature unevenness may occur, these problems can be avoided when the flow rate of the inert gas is set in the above range.

  In the plasma CVD apparatus according to the present invention, when the cylindrical substrate is moved from the preheating to the vacuum film forming chamber if the pressure is reduced to the vacuum state during the preheating, the preheating chamber and the vacuum film forming are performed. Since both chambers are in vacuum, the temperature of the cylindrical substrate is hardly lowered by moving the cylindrical substrate. On the other hand, as described above, in the preheating in the preheating chamber, the occurrence of temperature unevenness in the axial direction in the cylindrical substrate is suppressed. Therefore, the heating state of the cylindrical substrate in the preheating chamber can be maintained also in the vacuum film forming chamber, and it is possible to more reliably suppress the occurrence of temperature unevenness in the axial direction of the cylindrical substrate.

  In the plasma CVD apparatus of the present invention, if the pressure in the preheating chamber during preheating is maintained at 0.1 to 150 Pa, evaporation of the heating element can be suppressed and the influence of heat transfer due to the source gas can be avoided. That is, when the pressure of the inert gas is less than 0.05 Pa, the vapor pressure temperature of the heating element decreases, and when the temperature of the heating element is raised to the temperature necessary for heating the cylindrical substrate, the evaporation phenomenon of the heating element occurs. On the other hand, at high gas pressures where the pressure of the inert gas exceeds 150 Pa, the effect of heat transfer due to the gas may increase and temperature unevenness may occur. This can be avoided when the pressure is set.

  The plasma CVD apparatus according to the present invention further includes a pedestal that is movable from the preheating chamber to the vacuum film forming chamber in a state where the gas blowing plate having a plurality of gas blowing holes is fixed and the cylindrical substrate is held. If so, the positional relationship between the gas blowing holes and the cylindrical base body is made uniform. Therefore, for cylindrical substrates with different lots, preliminary heating (inert gas blowing) and film formation (raw material gas blowing) can be performed under the same conditions. It becomes possible to suppress variations in the film quality.

  In the plasma CVD apparatus of the present invention, if the plurality of heating elements are arranged so that the amount of heat radiation applied to the plurality of cylindrical substrates arranged in the preheating chamber is uniform, the plurality of cylindrical substrates In contrast, even when the films are formed at the same time, preheating can be performed under the same conditions in the cylindrical substrates. Therefore, it is possible to suppress the variation in film quality between the cylindrical substrates on the same rod.

  Hereinafter, a plasma CVD apparatus according to the present invention will be described as first and second embodiments with reference to the drawings.

  First, a first embodiment of the present invention will be described with reference to FIGS.

  The plasma CVD apparatus 1 shown in FIG. 1 moves the cylindrical substrate 3 in the order of the preheating chamber 4 and the film forming chamber 5 in a state where a plurality of cylindrical substrates 3 are held on the gantry 2. A desired film is formed on the surface of the cylindrical substrate 3 after preheating 3. The preheating chamber 4 and the film forming chamber 5 are defined by a container 10. In the container 10, the base carry-in port 11 and the base carry-out port 12 can be opened and closed by gates G1 and G2, and the preheating chamber 4 and the film forming chamber 5 are partitioned by the gate G3.

  As shown in FIGS. 1 and 2, the gantry 2 has a gas blowing plate 21 and a plurality of substrate supports 22 fixed to a base 20. Note that a known mechanism such as a combination of gears or a combination of gears and solenoids is used to transmit the moving force to the gantry 2.

  As shown in FIG. 3, the gas blowing plate 21 is provided with a plurality of gas blowing holes 23 and is fixed to the base 20 via an insulating member 24 and is electrically insulated from the base 20. Has been. The plurality of gas blowing holes 23 are formed in the same circular shape having a hole diameter D of about 0.5 to 2.0 mm, and a plurality of rows extending in the axial direction on the front surface of the cylindrical substrate 3 are in the left-right direction. They are arranged in a circular lattice pattern. The interval Pa in the vertical direction (the axial direction of the cylindrical substrate 3) in the plurality of gas blowing holes 23 is, for example, 10 to 30 mm, and the interval Ph in the left and right direction is, for example, 30 to 60 mm. The gas blowing plate 21 also functions as an electrode when a film is formed on the surface of the cylindrical substrate 3 in the film forming chamber 5, and is entirely formed of a conductor such as metal.

  As shown in FIGS. 1 and 2, the plurality of substrate supports 22 are for holding the cylindrical substrate 3, and are rotatably supported with respect to the base 20. Each substrate support 22 is formed in a hollow shape, and a through hole 22Aa is provided in the bottom 22A. This through hole 22Aa communicates with the through hole 20a provided in the base 20, and is for allowing the movement of a heating body 52 (see FIG. 5) described later. These substrate supports 22 also function as electrodes when a film is formed on the surface of the cylindrical substrate 3 in the film forming chamber 5, and are entirely formed of a conductor such as metal.

  The preheating chamber 4 is for preheating the cylindrical substrate 3 before forming a film on the cylindrical substrate 3. The preheating chamber 4 communicates with the outside through a gas inlet 40 and a gas outlet 41 provided in the container 10, and a plurality of heating elements 42 are disposed therein. The container 10 is further provided with a rotating means 43.

  The gas inlet 40 is for introducing an inert gas into the preheating chamber 4 and is connected to an inert gas source not shown. On the other hand, the gas discharge port 41 is for discharging the gas in the preheating chamber 4 to the outside, and is connected to a vacuum pump (not shown).

  The plurality of heating elements 42 function as a radiant heat source for raising the temperature of the cylindrical substrate 3, and are configured to generate heat when power is supplied from the outside via the terminals 44. The heating temperature at each heating element 42 is a temperature at which the cylindrical substrate 3 can be raised to 200 ° C. to 300 ° C. Each heating element 42 is made of a wire, and is preferably formed so that the heat generation temperature at both ends is higher than that at the center. Such a heating element 42 can be formed by selectively winding both ends of a wire as shown in FIG. In the heating element 42, the ratio of the length L2 of the end portion 42a to the total length L1 is 5 to 20%, the spiral diameter Dw at the end portion 42a is 2 to 10 mm, and the helical pitch Pw is 2 to 15 mm.

  In addition, in the heating element 42 shown in FIG. 4A, the winding pitch at both ends of the wire is constant, but as the heating element 42 shown in FIG. The winding pitch may be reduced, and the heat generation amount may be gradually increased toward the end. Of course, as the heating element 42, a wire having a uniform wire diameter and not wound at the end can be used. In that case, as the wire, a wire whose dimension is sufficiently longer than the dimension in the axial direction of the cylindrical substrate 3 is used.

  In addition, as the material of the heating elements 42 and 42 ', a material that is not easily sublimated or evaporated during preheating is used. Such materials include tungsten (W), platinum (Pt), palladium (Pd), molybdenum (Mo), Ti, niobium (Nb), tantalum (Ta), cobalt (Co), Ni, Cr, and Mn. Or an alloy of the exemplified metal.

  The plurality of heating elements 42 are arranged in a straight line extending along the axial direction of the cylindrical base body 3 in a state of facing the outer peripheral surface of the cylindrical base body 3, and the like with respect to the moving direction A of the gantry 2. Arranged at intervals. The heating elements 42 arranged at both ends in the movement direction A of the plurality of heating elements 42 are the cylindrical substrate 3 in which the amount of heat radiation of the cylindrical substrate 3 arranged at the ends in the movement direction A is arranged in the center. It is also located outside the cylindrical base 3 so as to be uniform.

  Here, the positional relationship between each heating element 42 and the cylindrical substrate 3 is determined by the material, thickness, size, and the like of the cylindrical substrate 3 and the substrate support 22. From the standpoint of uniformity, the distance between them is preferably 10 to 150 mm, preferably 30 to 80 mm, and most preferably 50 to 70 mm.

  The rotating means 43 is for rotating each substrate support 22 and is configured so that it can be connected and disconnected in a vacuum. As such a connection mechanism, a combination of a current connection terminal and a solenoid or a combination of a slip ring and a brush is used for electrical wiring, and a combination of a quick coupling and a solenoid is used for a medium. For transmission of rotational power, a combination of gears or a combination of gears and solenoids is used. A rotating mechanism capable of maintaining the vacuum of the preheating chamber 4 is provided at the contact point between the rotating means 43 and the container 10 defining the preheating chamber 4. As such a rotating mechanism, vacuum seal means such as an oil seal or a mechanical seal can be used with a rotating shaft having a double or triple structure. When the temperature of the cylindrical substrate 3 is detected to control the temperature of the cylindrical substrate 3, the rotation shaft is formed hollow, and the temperature detection means and its wiring are provided inside the rotation shaft. Can also be provided.

  When the substrate support 22 is rotated by such a rotating means 43, the cylindrical substrate 3 held on the substrate support 22 can be rotated, so that the heating element with respect to the outer periphery of the cylindrical substrate 3. The radiant heat from 42 can be transmitted evenly. As a result, it becomes possible to raise the temperature of each cylindrical substrate 3 to a substantially uniform temperature.

  As shown in FIGS. 1 and 5, the film forming chamber 5 is a place for forming a desired film on the surface of the cylindrical substrate 3, and includes a gas inlet 50 and a gas outlet provided in the container 10. While communicating with the exterior via 51, the some heating body 52 is arrange | positioned in the inside. The container 10 is further provided with a rotating means 53.

  The gas inlet 50 is for introducing a source gas into the film forming chamber 5 and is connected to a source gas source not shown. On the other hand, the gas discharge port 51 is for discharging the gas in the film forming chamber 5 to the outside, and is connected to a vacuum pump (not shown). The film forming chamber 5 is brought into a high vacuum state of, for example, about 1.0 to 100 Pa by discharging the gas from the gas exhaust port 51.

  The heating body 52 is for heating the cylindrical substrate 3 in order to maintain the temperature rising state of the cylindrical substrate 3 heated in the preheating chamber 4. The heating body 52 is movable in the vertical direction. That is, when the gantry 2 is carried into the film forming chamber 5 and the gantry 2 is unloaded from the film forming chamber 5, the heating body 52 is retracted downward so as not to hinder the movement of the gantry 2. On the other hand, at the time of film formation, the heating body 52 is projected into the film formation chamber 5 so as to be accommodated inside the substrate support 22. As a result, the cylindrical substrate 3 can be heated via the substrate support 22. Such a heating body 52 is constituted by, for example, a nichrome wire or a cartridge heater.

  The rotating means 53 is for rotating each substrate support 22 during film formation, and has the same configuration as the rotating means 43 (see FIG. 2) of the preheating chamber 4 described above. When film formation is performed by rotating the substrate support 22 by such a rotating means 53, the cylindrical substrate 3 is rotated, so that the source gas is decomposed evenly with respect to the outer periphery of the cylindrical substrate 3. It becomes possible to deposit components.

  Next, the case where the electrophotographic photosensitive member 6 shown in FIG. 6 is produced using the plasma CVD apparatus 1 will be described as an example. The electrophotographic photoreceptor 6 shown in FIG. 6 is obtained by sequentially laminating a carrier injection blocking layer 60, a photoconductive layer 61, and a surface protective layer 62 on the surface of the cylindrical substrate 3.

  When a target film is formed on the cylindrical substrate 3 using the plasma CVD apparatus 1, the cylindrical substrate 3 is first set on the substrate support 22 of the gantry 2.

  As the cylindrical substrate 3, a conductive or insulating material is used according to the application of the product, or a conductive layer formed on the surface of the insulating substrate is used.

  Examples of the conductive substrate include aluminum (Al), stainless steel (SUS), iron (Fe), nickel (Ni), chromium (Cr), manganese (Mn), copper (Cu), and titanium (Ti). The thing formed with the metal or these alloys can be mentioned.

  Examples of the insulating substrate include inorganic insulators such as glass (borosilicate glass and soda glass), ceramics, quartz, and sapphire, or fluororesin, polycarbonate, polyethylene terephthalate, polyester, polyethylene, polypropylene, polystyrene, polyamide, and vinylon. And synthetic resin insulators such as epoxy and mylar.

  As the conductive layer formed on the insulating base, for example, on the surface of the insulating base, a conductive layer such as ITO (indium / tin / oxide), tin oxide, lead oxide, indium oxide, and copper iodide, Al Metal layers such as Ni, Au, and gold (Au) can be employed. The conductive layer may be, for example, a vacuum deposition method, an active reaction deposition method, an ion plating method, an RF sputtering method, a DC sputtering method, an RF magnetron sputtering method, a DC magnetron sputtering method, a thermal CVD method, a plasma CVD method, a spray method, It can be formed by a coating method or a dipping method.

  Next, the gantry 2 holding the cylindrical substrate 3 is carried into the preheating chamber 4. When the gantry 2 is carried into the preheating chamber 4, the base carry-in port 11 in the container 10 is opened by opening the gate G1. On the other hand, after the platform 2 is carried in, the base carry-in port 11 is closed by the gate G1, and the preheating chamber 4 is set as a sealed space.

  After the preheating chamber 4 is sealed, the preheating chamber 4 is decompressed. This pressure reduction is performed by exhausting the preheating chamber 4 through the gas exhaust port 41 by a vacuum pump (not shown). The degree of pressure reduction in the preheating chamber 4 is a high vacuum of about 1 × 10 −3 Pa. By depressurizing the preheating chamber 4 in this way, moisture and residual impurity gas are removed from the preheating chamber 4. Thereby, it is possible to prevent the moisture and residual impurity gas remaining in the preheating chamber 4 from being decomposed when the heating element 42 is heated later, and a film is formed on the surface of the cylindrical substrate 3 by the preheating. Can be prevented.

  Next, the heating element 42 is caused to generate heat, and the cylindrical substrate 3 is heated. The heating element 42 is heated by supplying electric power from the outside via the terminal 44. The heating temperature of the heating element 42 is determined by the positional relationship between the heating element 42 and the cylindrical base 3 or the temperature rise temperature of the cylindrical base 3. When the distance between them is 30 to 70 mm and the temperature rise temperature of the cylindrical substrate 3 is set to 200 ° C. to 300 ° C., the heat generation temperature of the heating element 42 is, for example, 500 to 2200 ° C., preferably 800 to 2000. ℃.

  Simultaneously with the heat generation of the heating element 42, an inert gas (a rare gas such as He, Ne, Ar, Xe, or N 2) other than the inert gas source (not shown) is spared via the gas inlet 40. Supply to the heating chamber 4. The inert gas introduced into the preheating chamber 4 is blown out toward the cylindrical substrate 3 through the gas blowing holes 23 of the gas blowing plate 21. Generally, since the temperature of the inert gas is sufficiently lower than the heated cylindrical substrate 3, the inert gas acts as a cooling gas after the cylindrical substrate 3 is heated to a certain temperature or higher. Then, heat is taken from the surface of the cylindrical substrate 3. Thus, by raising the temperature of the preheating chamber 4 in an inert gas environment, the influence of the residual impurity gas can be further reduced, and the vapor pressure of the heating element 42 can be controlled by performing constant pressure control. The temperature can be made sufficiently high.

  Here, the flow rate of the inert gas is adjusted to a constant amount by a flow rate adjusting valve or a mass flow controller (not shown) provided between the inert gas source and the gas inlet 40. A preferable inert gas flow rate range in the present invention is, for example, when the diameter D of the gas blowing hole 23 is 1.5 mm and the distance between the gas blowing (gas blowing plate 21) hole 23 and the cylindrical substrate 3 is 50 mm. It is set to 0.1 sccm to 30 sccm, preferably 0.3 sccm to 20 sccm per gas blowing hole 23. This is because if the flow rate of the inert gas is less than 0.1 sccm, the amount of blowout from the gas blowout holes 23 is too small to obtain the required cooling effect, whereas if the flow rate of the inert gas is 30 sccm or more, the gas blowout holes 23. This is because the amount of air blown out from the air is so great that the cooling effect becomes excessive and the heating efficiency of the cylindrical substrate 3 is deteriorated.

  In addition, a good gas pressure range of the inert gas is 0.05 Pa to 150 Pa, preferably 0.1 Pa to 100 Pa. This is because when the pressure of the inert gas is less than 0.05 Pa, the vapor pressure temperature of the heating element 42 decreases, and the heating element 42 evaporates when the temperature of the heating element is increased to a temperature necessary for heating the cylindrical substrate 3. While the phenomenon may occur, at high gas pressures where the pressure of the inert gas exceeds 150 Pa, the effect of heat transfer by the gas becomes large and temperature unevenness may occur.

  Preheating by the heating element 42 in such an inert gas environment is performed, for example, for 0.5 to 3 hours.

  In the plasma CVD apparatus 1, a heating element composed of a wire is used as a heat source for preheating. For this reason, it is possible to raise the temperature of the cylindrical substrate 3 to a state in which the temperature unevenness in the axial direction is small as compared with the case where the cylindrical substrate 3 is heated using a heating means such as a cartridge heater. In particular, when a heat generating element having a large amount of heat generation at both ends, such as the heating element 42 shown in FIGS. 4A and 4B, is used, both ends in the axial direction of the cylindrical substrate 3 are used. Therefore, it is possible to further suppress the occurrence of temperature unevenness in the axial direction.

  Further, when a wire such as a wire is used for heating the cylindrical substrate 3, the power required for the preliminary heating is reduced as compared with the case where the cylindrical substrate 3 is heated using a heating means such as a cartridge heater. be able to. As a result, the cylindrical substrate 3 can be preheated at low cost.

  When the preheating of the cylindrical substrate 3 is completed, the gantry 2 holding the cylindrical substrate 3 is moved from the preheating chamber 4 to the film forming chamber 5. When the gantry 2 is carried into the film forming chamber 5, the preheating chamber 4 and the film forming chamber 5 are in communication with each other by opening the gate G <b> 3 in the container 10. On the other hand, after carrying the gantry 2 into the film forming chamber 5, the gate G3 is closed and the film forming chamber 5 is set as a sealed space.

  Note that the pressure in the film forming chamber 5 is reduced in advance before the platform 2 is carried in. The film forming chamber 5 is decompressed by evacuating the film forming chamber 5 through the gas exhaust port 51 by a vacuum pump (not shown). The degree of pressure reduction in the film forming chamber 5 is a high vacuum of about 1 × 10 −3 Pa.

  After the film formation chamber 5 is sealed, the heating body 52 is moved upward and the heating body 52 is inserted into the substrate support 22. The heating body 52 is heated by supplying electric power from the outside. Due to the heat generated by the heating body 52, the cylindrical substrate 3 is maintained at a target temperature. The temperature of the cylindrical substrate 3 is selected depending on the type of film to be formed on the surface thereof. For example, when an a-Si film is formed, the temperature is set in the range of 250 to 300 ° C.

  Here, since the cylindrical substrate 3 is heated in advance in the preheating chamber 4 to a state in which the temperature unevenness in the axial direction is small, even when the cylindrical substrate 3 is heated using the heating body 52, The occurrence of temperature unevenness in the direction is suppressed. In particular, when the preheating is performed in a vacuum state and the cylindrical substrate 3 is moved to the vacuum film formation chamber 5 by the gantry 2, both the preheating chamber 4 and the film formation chamber 5 are in vacuum. For this reason, the temperature drop of the cylindrical base body 3 due to the movement of the cylindrical base body 3 hardly occurs. Therefore, in the film forming chamber 5, it is possible to more reliably suppress the occurrence of temperature unevenness in the axial direction of the cylindrical substrate 3.

  Simultaneously with the heat generation of the heating body 52, a source gas of a source gas source (not shown) is supplied to the film forming chamber 5 through the gas inlet 50, and the gas blowing plate 21 and the substrate support 22 are A high frequency voltage is applied between them.

  The source gas introduced into the preheating chamber 4 is blown out toward the cylindrical substrate 3 through the gas blowing holes 23 of the gas blowing plate 21. In the gas blowing plate 21, the plurality of gas blowing holes 23 are arranged at equal intervals in the axial direction of the cylindrical substrate 3, so that the inert gas is uniformly blown onto the cylindrical substrate 3 in the axial direction. The

  Here, the source gas is appropriately selected according to the type of film to be formed on the cylindrical substrate 3. For example, when the charge injection blocking layer 60 is formed, for example, a mixed gas of SiH4, NO and B2H6 diluted with H2 is used as the source gas, and when the photoconductive layer 61 is formed, for example, A material gas obtained by diluting a mixed gas of SiH4 and B2H6 with H2 is used as the raw material gas, and when the surface protective layer 62 is formed, for example, a mixed gas of SiH4 and CH4 as the raw material gas is diluted with H2. used. Of course, the source gas composition may be appropriately selected and is not limited to the exemplified composition. Further, the flow rate and supply pressure of the source gas may be appropriately selected according to the composition and thickness of the film to be formed.

  On the other hand, when a high frequency voltage is applied between the gas blowing plate 21 and the substrate support 22, glow discharge occurs between the gas blowing plate 21 and the substrate support 22, and the raw material gas components are decomposed to generate plasma. It becomes. The decomposition component of the source gas is deposited on the surface of the cylindrical substrate 3. Then, the charge injection blocking layer 60, the photoconductive layer 61, and the surface protective layer 62 are sequentially stacked on the surface of the cylindrical substrate 3 by appropriately switching the source gas.

  In the plasma CVD apparatus 1, the cylindrical substrate 3 is heated by the wire in the preheating chamber 4, thereby suppressing temperature unevenness in the axial direction. On the other hand, even when the cylindrical substrate 3 is carried into the film forming chamber 5, the temperature unevenness in the cylindrical substrate 3 is maintained while being suppressed. Therefore, the film formed on the surface of the cylindrical substrate 3 is homogenized in the axial direction of the cylindrical substrate 3. As a result, in the electrophotographic photosensitive member 6 created in the plasma CVD apparatus 1, it is possible to suppress the formation of a film formed at a temperature lower than the target temperature. It is difficult to occur, and it is possible to suppress the occurrence of unevenness in the image. Therefore. In the plasma CVD apparatus 1, it is possible to produce the electrophotographic photosensitive member 6 capable of forming a uniform image, and it is possible to meet demands for colorization and high image quality.

  In the plasma CVD apparatus 1, the plurality of heating elements 42 in the preheating chamber 4 are arranged so as to uniformly apply radiant heat to the plurality of cylindrical substrates 3. Therefore, even when forming a film on a plurality of cylindrical substrates 3 simultaneously, preliminary heating can be performed under the same conditions in the cylindrical substrates 3. As a result, it is possible to suppress variations in film quality between the cylindrical substrates 3 of the same lot.

  Further, in the plasma CVD apparatus 1, the substrate support 22 and the gas blowing plate 21 are fixed to the gantry 2, so that the positional relationship between the gas blowing holes 23 and the cylindrical substrate 3 is made uniform. Therefore, the cylindrical substrates 3 of different lots can perform preheating (inert gas blowing) and film formation (raw material gas blowing) under the same conditions. In this case, it is possible to suppress the variation in film quality.

  Next, a second embodiment of the present invention will be described with reference to FIGS.

  The plasma CVD apparatus 1 ′ shown in FIG. 7 is different from the plasma CVD apparatus 1 described above with reference to FIGS. 1 to 5 in the configuration of the gas blowing plate 7.

  As shown in FIG. 8, the gas blowing plate 7 has an end portion corresponding to the end portion of the cylindrical substrate 3 as compared with the distribution density of the gas blowing holes 71 in the central region E1 corresponding to the central portion of the cylindrical substrate 3. The distribution density of the gas blowing holes 72 in the region E2 is reduced. The interval P1a between the gas blowing holes 71 in the central region E1 is 3 to 15 mm, and the interval P2a between the gas blowing holes 72 in the end region E2 is 20 to 30 mm. The distribution density of the gas blowing holes 71 and 72 is 0.04 when the distribution density of the central region E1 is set to 1 on the basis of the occupied area of the gas blowing holes 71 and 72. ˜0.64.

  In such a gas blowing plate 7, the amount of inert gas blown in the end region E2 is smaller than the amount of inert gas blown in the central region E1 during preheating. Therefore, the amount of inert gas irradiated to the end portion of the cylindrical substrate 3 is smaller than the amount of inert gas irradiated to the center portion of the cylindrical substrate 3. As a result, the cooling effect with the inert gas is smaller at the end of the cylindrical substrate 3 than at the center. On the other hand, the end of the cylindrical substrate 3 is a portion where the temperature tends to be lower than that of the central portion. Therefore, by reducing the cooling effect at the end portion of the cylindrical base body, the temperature of which tends to be low, the temperature difference between the central portion and the end portion of the cylindrical base body 3 can be reduced. This makes it possible to appropriately suppress the occurrence of temperature unevenness in the axial direction of the cylindrical substrate 3 during preheating.

  Further, as the gas blowing plate, for example, the one shown in FIGS. 9 to 11 can be adopted, and in this case, the same as the case where the gas blowing plates 8A, 8B, 8C shown in FIG. 8 are adopted. There is an effect. In the gas blowing plate 8A shown in FIG. 9, the distribution density of the gas blowing holes 80A gradually decreases from the center toward the end, and the gas blowing plate 8B shown in FIG. The diameter D1 of the gas blowing hole 81B is made smaller than the diameter D2 of the gas blowing hole 82B in the end region E2, and the gas blowing plate 8C shown in FIG. 11 gradually increases from the center toward the end. Further, the hole diameter of the gas blowing hole 80C is made smaller.

  The gas blowing holes do not necessarily have to be provided in the form of a gas blowing plate and do not need to be fixed to the gantry 2. For example, the gas blowing holes may be provided individually in the preheating chamber and the film forming chamber.

  In this example, the electrophotographic photosensitive member 6 shown in FIG. 6 is formed using the plasma CVD apparatus 1 according to the first embodiment of the present invention described above with reference to FIGS. In the process, various evaluations were performed, and the obtained electrophotographic photosensitive member 6 was evaluated.

  In the plasma CVD apparatus 1, a tantalum wire having a purity of 99.99% having a uniform wire diameter of 0.5 mm and a length of 500 mm was used as the heating element 42. The wires used in the present example are straight wires that are not wound at both ends, and six wires are arranged so that the distance between the heating element 42 and the cylindrical substrate 3 is 50 mm.

  As the cylindrical substrate 3, an aluminum substrate having a mirror finished surface and a diameter of 30 mm and a length of 359 mm was used. Sixteen cylindrical substrates 3 were set in the preheating chamber 4.

  The preheating chamber 4 is evacuated to a vacuum of 1 × 10 −3 Pa by a rotary pump and a mechanical booster pump, and then introduced 100 sccm Ar gas controlled by a mass flow controller through the gas introduction hole 40. The preheating chamber was kept constant at a gas pressure of 6.65 Pa.

  The preheating was performed for 1 hour in a state where the heating element 42 was energized and heated to 1900 ° C.

  Of the cylindrical substrate 3 preheated in this way, the temperature of the center and upper and lower end portions (portions with a distance of 30 mm from the end surface) are measured for each of the cylindrical substrates 3 arranged at the end and the center. did. The temperature of the cylindrical substrate 3 was measured by attaching a thermocouple to the surface of the cylindrical substrate 3. The results of temperature measurement are shown in Table 1. In Table 1, the temperature measurement result when the cylindrical substrate 3 is preheated with a cartridge heater is also shown for comparison.

  As is apparent from the results in Table 1, when preheating is performed using a straight wire, the axial direction of the cylindrical substrate 3 is larger than when a cartridge heater, which is a general method, is used as a heating means. The temperature unevenness is improved. In particular, the temperature unevenness at the lower part of the cylindrical substrate 3 is remarkably improved, and the temperature unevenness in the axial direction of the cylindrical substrate 3 is about ½ when a linear heater is used and when a cartridge heater is used. It turns out that it has improved to.

  Next, the preliminarily heated cylindrical substrate 3 was transferred to the film forming chamber 5 and the electrophotographic photosensitive member 6 shown in FIG. 6 was manufactured under the film forming conditions shown in Table 2.

  With respect to the a-Si photoreceptor thus obtained, the light portion potential of each part was measured with an electrophotographic characteristic measuring machine. The results of measuring the bright part potential are shown in Table 3.

  As is apparent from the results in Table 3, in the cylindrical substrate 3 preheated by the wire, the bright portion potential non-uniformity becomes about ½ of that in the case of preheating by the cartridge heater, and the potential nonuniformity. A good drum with a small amount was obtained. Further, when a photoconductor obtained by preheating with a wire was subjected to image evaluation using a full color printer KMC-2630 manufactured by Kyocera Mita, a good image free of fog and density unevenness was obtained.

  Table 4 shows the amount of power consumed by the wire heater and cartridge heater used in the preheating. The power consumption when preheated by the wire is about half that when preheated by the cartridge heater. It was also revealed that there was an unexpected effect of power saving and high efficiency.

  Next, preheating was similarly performed by changing the gas pressure in the preheating chamber 4, and the surface temperature of the cylindrical substrate 3 was measured. Ar gas was used as the inert gas. The gas flow rate was 0 (no inert gas) only when the gas pressure was 0.06 Pa, and constant at 100 sccm for other gas pressures. The results of temperature measurement are shown in Table 5.

  When the cylindrical substrate after the preheating was observed, a thin cloud was observed on the surface only when the gas pressure was 0.06 Pa and the preheating was performed without supplying an inert gas. This is considered that the component of the heating element 42 is evaporated and adhered. Based on this fact, considering the results in Table 5, it can be seen that a good gas pressure range during preheating is 0.1 to 100 Pa.

  In this example, evaluation was performed in the same manner as in Example 1 except that the winding wire 42 shown in FIG.

  The heating element 42 used in this example has a configuration in which a spiral wound portion 42a is provided in a range of 15 to 40 mm from the end of the wire. In the winding portion 42a, the winding diameter Dw was set to 4 mm, and the pitch Pw was set to 6 mm (4 windings).

  Of the cylindrical substrate 3 heated using the heating element 42, the center and upper and lower end portions (distance from the end surface is 30 mm) of the cylindrical substrate 3 disposed at the end in the moving direction A and at the center. Temperature). The temperature of the cylindrical substrate 3 was measured by attaching a thermocouple to the surface of the cylindrical substrate 3. The results of temperature measurement are shown in Table 6. In Table 6, the temperature measurement result when the cylindrical substrate 3 is preheated by the heating element 42 (straight wire) used in Example 1 is also shown for comparison.

  As is apparent from the results in Table 6, when a heating element 42 (winding wire) having winding portions at both ends to increase the amount of heat generated at both ends is used, In comparison, it can be seen that the temperature unevenness in the axial direction of the cylindrical substrate 3 is improved to about 1/3.

  Next, the pre-heated cylindrical substrate 3 is transferred to the film forming chamber 5 in the same manner as in Example 1, and the electrophotographic photosensitive member 6 shown in FIG. Produced.

  With respect to the a-Si photoreceptor thus obtained, the light portion potential of each part was measured with an electrophotographic characteristic measuring machine. The measurement results of the bright part potential are shown in Table 7.

  As is apparent from the results in Table 7, in the cylindrical base body 3 that was preheated by the heating element 42 of the winding wire, the unevenness of the bright part potential was observed when the preheating was performed by the heating element 42 of the straight wire. As a result, it was about ½, and a good drum with little potential unevenness was obtained. Further, when a photoreceptor obtained by preheating with a heating element 42 of a winding wire was subjected to image evaluation using a full color printer KMC-2630 manufactured by Kyocera Mita, a good image free from fogging and density unevenness was obtained. .

  In this example, preheating was performed using a straight wire made of tungsten in the same manner as in Example 1 except that the plasma CVD apparatus 1 ′ of FIG. 7 provided with the gas blowing plate 7 shown in FIG. 8 was used. The case where it performed is evaluated.

  As the gas blowing plate 7, the gas blowing holes 71, 72 have an axial interval P 1 a for the end region E 1 (region from the end to 100 mm) corresponding to both ends of the cylindrical substrate 3 (imaginary line in FIG. 8). Is set to be 50 mm, and in the central region E2 corresponding to the central portion of the cylindrical substrate 3 (a region 250 mm in the axial direction existing between the end regions), the axial interval P2a is 25 mm. The one arranged in was used.

  Of the cylindrical substrate 3 preheated using the gas blowing plate 7, the center and upper and lower end portions (parts having a distance of 30 mm from the end surface) of the cylindrical substrate 3 disposed at the end and the center are respectively provided. ) Was measured. The temperature of the cylindrical substrate 3 was measured by attaching a thermocouple to the surface of the cylindrical substrate 3. The results of temperature measurement are shown in Table 8. In Table 8, for comparison, the cylindrical substrate 3 was preheated using a gas blowing plate 23 (see FIG. 3) in which a plurality of blowing holes 23 similar to those in Example 1 were arranged at equal intervals in the axial direction. The temperature measurement results were also shown at the same time.

  As is apparent from the results of Table 8, when preheating is performed using the gas blowing plate 7 (see FIG. 8) in which the distribution density of the blowing holes 72 in the end region E2 is reduced, the distribution of the blowing holes 23 is obtained. Compared with the case where the preheating is performed using the gas blowing plate 21 (see FIG. 3) having a uniform density (equally spaced in the axial direction), the temperature unevenness in the axial direction in the cylindrical substrate 3 is reduced by half. It turns out that it has improved to the extent or less.

  Next, the pre-heated cylindrical substrate 3 is transferred to the film forming chamber 5 in the same manner as in Example 1, and the electrophotographic photosensitive member 6 shown in FIG. Produced.

  With respect to the a-Si photoreceptor thus obtained, the light portion potential of each part was measured with an electrophotographic characteristic measuring machine. Table 9 shows the measurement results of the light portion potential.

  As is clear from the results in Table 9, in the cylindrical substrate 3 that has been preheated using the gas blowing plate 7 (see FIG. 8) in which the distribution density of the blowing holes 72 in the end region E2 is reduced, a plurality of blowings Compared with the case where the preheating is performed using the gas blowing plate 21 (see FIG. 3) in which the distribution density of the holes 23 is uniform (equally spaced in the axial direction), the unevenness of the bright portion potential is about ½. A good drum with little potential unevenness was obtained. Further, when a photoconductor obtained by preheating with the gas blowing plate 7 of FIG. 8 was evaluated with a full color printer KMC-2630 manufactured by Kyocera Mita, a good image free from fogging and density unevenness was obtained. .

  Next, preheating was similarly performed by changing the gas flow rate in the preheating chamber 4, and the surface temperature of the cylindrical substrate 3 was measured. Ar gas was used as the inert gas. The gas flow rate was kept constant during preheating at the values shown in Table 10 below. The results of temperature measurement are shown in Table 10.

  As is clear from Table 10, a sufficient cooling effect is exhibited when the gas blowing amount per gas blowing hole 71, 72 is about 0.1 sccm, but if it is less than that, the cooling effect is sufficient. Temperature unevenness has not been improved. On the other hand, when the gas blowing amount per gas blowing hole 71, 72 is about 30 sccm, a sufficient cooling effect is exhibited. The temperature was also lowered and the heating efficiency was worse.

  Therefore, it was found that the gas flow rate per gas blowing hole 71, 72 is preferably set to 0.1 to 30 sccm.

1 is a plan perspective view of a plasma CVD apparatus according to a first embodiment of the present invention. It is for demonstrating the preheating chamber in the plasma CVD apparatus shown in FIG. 1, and is sectional drawing cut | disconnected and shown along the II-II line | wire of FIG. It is a front view for demonstrating the gas blowing plate in the plasma CVD apparatus shown in FIG. (A) is a front view for demonstrating the heat generating body in the preheating chamber shown in FIG. 2, (b) is a front view which shows the edge part for demonstrating the other example of a heat generating body, (c) is a front view which shows the edge part for demonstrating the further another example of a heat generating body. FIG. 5 is a cross-sectional view taken along line VV in FIG. 1 for explaining a film forming chamber in the plasma CVD apparatus shown in FIG. 1. It is the longitudinal cross-sectional view of the electrophotographic photoreceptor manufactured by the CVD plasma apparatus shown in FIG. 1, and its principal part enlarged view. It is sectional drawing equivalent to FIG. 2 for demonstrating the plasma CVD apparatus which concerns on the 2nd Embodiment of this invention. It is a front view equivalent to FIG. 3 for demonstrating the other example of the gas blowing plate in the plasma CVD apparatus shown in FIG. It is a front view equivalent to FIG. 3 for demonstrating the other example of a gas blowing plate. It is a front view equivalent to FIG. 3 for demonstrating the further another example of a gas blowing plate. It is a front view equivalent to FIG. 3 for demonstrating the further another example of a gas blowing plate. It is a longitudinal cross-sectional view for demonstrating the conventional plasma CVD apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,1 'Plasma CVD apparatus 2 Base 21 Gas blowing plate 23 Gas blowing hole 3 Cylindrical base | substrate 4 Preheating chamber 42, 42' Heat generating body 5 (Vacuum) Film-forming chamber 7, 8A, 8B, 8C Gas blowing plate 71, 72, 80A, 81B, 82B, 80C Gas blowout holes

Claims (10)

In a plasma CVD apparatus that forms a thin film by depositing decomposition components when a source gas is decomposed by glow discharge on a cylindrical substrate held in a vacuum film formation chamber,
A preheating chamber partitioned from the vacuum film forming chamber and preheating the cylindrical substrate;
One or a plurality of heating elements made of a linearly arranged wire extending in the axial direction of the cylindrical base so as to face the outer peripheral surface of the cylindrical base;
Further comprising a,
The said heat generating body is formed so that the emitted-heat amount of both ends may be larger than a center part , The plasma CVD apparatus characterized by the above-mentioned. 2. The plasma CVD apparatus according to claim 1 , wherein the heating element is formed by spirally winding both ends of a wire. The preheating chamber further includes a plurality of gas blowing holes for blowing an inert gas to the cylindrical base body,
The plurality of gas blowout holes occupy an end area of the cylindrical substrate facing an axial center of the cylindrical substrate, and an occupied area of the cylindrical substrate at an end region of the cylindrical substrate facing the axial ends. characterized in that it is made larger than the area, the plasma CVD apparatus according to claim 1 or 2. The plasma CVD apparatus according to claim 3 , wherein the plurality of gas blowing holes are formed so that a distribution density in the central region is larger than a distribution density in the end region. . The plasma CVD apparatus according to claim 3 , wherein the plurality of gas blowing holes are formed so that an opening area in the central region is larger than an opening area in the end region. . Exhaust-gas from the plurality of gas blowing holes is characterized by a 0.1sccm~30sccm the diameter 1.5mm of the gas blowing holes, according to any one of claims 3 to 5 Plasma CVD equipment. Wherein the plurality of gas blow gas having a hole blowout plate is fixed, and the while holding the cylindrical substrate further comprises a moveable platform from said preheating chamber to said vacuum deposition chamber, according to claim 3 7. The plasma CVD apparatus according to any one of items 6 to 6 . The plasma CVD apparatus according to any one of claims 1 to 7 , wherein the preheating chamber is decompressed to a vacuum state during preheating. The plasma CVD apparatus according to claim 8 , wherein the preheating chamber is maintained at a pressure of 0.1 to 150 Pa during preheating. Wherein the plurality of heating elements, characterized in that the heat radiation amount that is irradiated for a plurality of cylindrical substrates are arranged in the preheating chamber is arranged to be uniform, claims 1 9 The plasma CVD apparatus according to any one of the above.

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