JP2004190132A - Hot wire cvd system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thin film deposition system ähot wire CVD (chemical vapor deposition) system} by which unevenness in the film thickness of a thin film to be deposited on a substrate is improved, and the thin film of uniform film thickness is deposited on the surface of the substrate, and to provide a thin film deposition system (hot wire CVD system) by which a film with uniform quality is formed on the surface of a substrate. <P>SOLUTION: As for the hot wire CVD system, a planar gas blowing-out body 43 having a hollow is arranged at the inside of a reaction chamber 40, catalytic bodies 44 are provided so as to be confronted with the main face of the gas blowing-out body 43, a substrate 42 for film deposition is arranged at the outside of the catalytic bodies 44, further, a plurality of gas blowing-out holes 45 are formed on the main face of the gas blowing-out body 43, and, the distribution density of the blowing-out holes 45 is made higher from the central part toward the outer circumferential part in the main face. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

  The present invention relates to a hot wire CVD apparatus for forming, for example, an amorphous silicon-based thin film on a film formation substrate by a hot wire CVD method.

  2. Description of the Related Art Conventionally, glow discharge is mainly used for manufacturing an electrophotographic photosensitive member, a solar cell, an image sensor, an optical sensor, a TFT (thin film transistor), and the like using an amorphous silicon (hereinafter, amorphous silicon is abbreviated as a-Si) material. A film forming apparatus using a plasma CVD method has been widely used.

  To manufacture an electrophotographic photosensitive drum made of a-Si using this film forming apparatus, a glow discharge plasma CVD apparatus 1 as shown in FIG. 16 is used.

  FIG. 1 is a schematic configuration diagram of a glow discharge plasma CVD apparatus 1. Numeral 2 denotes a cylindrical vacuum vessel, and a cylindrical conductive substrate made of aluminum metal material or the like is provided substantially in the center of the vacuum vessel 2. In this technique, an a-Si film is formed on the conductive substrate 4 by glow discharge plasma.

  The conductive base 4 is held by a base support 3 made of SUS or the like provided therein, and the conductive base 4 is used as a ground electrode and the other high-frequency power application electrode is equidistant from the outer peripheral surface. A cylindrical metal electrode 5 made of SUS or the like is arranged.

  A gas introduction pipe 6 for introducing a source gas for film formation is connected to the metal electrode 5. Both gas introduction pipes 6 are provided to the conductive substrate 4 from gas blowing holes 7 provided on the inner peripheral surface of the metal electrode 5. A source gas is introduced between the electrodes.

  Above and below the metal electrode 5, insulating rings 8 and 8 'made of ceramic or the like for insulation from ground are provided. A high-frequency power source 9 is connected between the metal electrode 5 and the conductive base 4, Glow discharge plasma is generated between the conductive substrate 4 and the metal electrode 5 with the introduction of the gas.

  In generating such glow discharge plasma, a substrate heating means 10 including a nichrome wire and a cartridge heater is provided inside the substrate support 3 to set the conductive substrate 4 to a desired temperature. Further, the substrate support 3 and the conductive substrate 4 are integrally rotated by a rotation motor 11 via a rotation transmitting means 12, thereby achieving uniform film thickness and film quality.

  In forming an a-Si-based film using the glow discharge plasma CVD apparatus 1 having the above-described configuration, a source gas set to a predetermined flow rate and a gas ratio is supplied from a gas introduction pipe 6 through a gas blowing hole 7. A predetermined gas pressure is set by adjusting the amount of exhaust from an exhaust pipe 13 connected to a vacuum pump (not shown) while being introduced between both electrodes, and high-frequency power is applied by a high-frequency power supply 9. Then, a glow discharge plasma is generated between the two electrodes to decompose the source gas, and an a-Si-based film is formed on the conductive substrate 4 set at a desired temperature.

  However, according to the above-described glow discharge plasma CVD method, since the surface of the a-Si film during film formation is damaged by plasma, there is a problem that there is a limit in improving film characteristics and controlling the interface characteristics of the laminated film. There was a point.

  In addition, an expensive high-frequency power supply for generating glow discharge plasma is required for each glow discharge plasma CVD apparatus 1, thereby increasing the manufacturing cost. Furthermore, with the generation of glow discharge plasma due to high frequency, a part of the power leaks as high frequency noise to various parts of the film forming apparatus and to the outside, causing malfunctions in various control devices for gas flow rate, gas pressure and substrate temperature. There were also points.

  In addition, as a decomposition product by plasma, a large amount of yellow flammable powder is generated as a by-product during the formation of the a-Si-based film, and a portion other than the conductive substrate 4 in the vacuum vessel, that is, The powder adheres and accumulates on the electrodes, the inner wall of the container, the exhaust pipe system, and the like, and the powder flies to the surface of the conductive substrate 4 during the film formation, causing a film formation defect. In addition, every time a film is formed, a powder cleaning operation in the reaction furnace is required, and handling thereof involves a danger such as ignition.

  In order to solve these problems and improve the characteristics of the a-Si based film, Patent Documents 1 and 2 disclose a hot wire CVD method (also referred to as a catalytic CVD method or a Cat-CVD method). A so-called film forming method and an apparatus therefor have been proposed.

  The hot wire CVD apparatus will be described based on the schematic view of the apparatus shown in FIG.

  In a reaction chamber 14 composed of a vacuum vessel, a substrate 16 for film formation is held and installed on a substrate holder 15, and a catalyst body 17 composed of tungsten or the like is provided above the substrate 16 at an appropriate interval. The gas introduction pipe 18 is arranged so that the raw material gas can be supplied onto the base 16 through the catalyst body 17. 19 is a vacuum pump used for evacuation, and 20 is a heater as substrate heating means.

In order to form an a-Si film using this hot wire CVD apparatus, a source gas such as a mixed gas of SiH ₄ and H ₂ is introduced into a reaction chamber 14 evacuated to a vacuum state by a vacuum pump 19. The catalyst is introduced from the introduction pipe 18 and passed through the catalyst body 17 heated to 1000 to 2000 ° C. to cause a catalytic reaction. The reactive species decomposed and generated by the reaction reach the substrate 16 to form an a-Si based film. Deposit.

  Further, according to Patent Document 3, a radiant heat insulating member having an opening through which gas can pass is provided between the catalyst body and the substrate for film formation, thereby preventing a temperature rise of the substrate due to radiation from the catalyst body. A technique has been proposed.

  In relation to the hot wire CVD apparatus as described above, Patent Documents 4 and 5 propose a technique for preventing impurities such as heavy metals contained in the catalyst from being mixed into the film.

Further, Patent Document 6 discloses that a material gas such as H ₂ is decomposed and activated by a catalyst, and an active species generation space generated as an active species and a raw material gas such as SiH ₄ are chemically reacted with the active species. A configuration is described in which a film formation processing space for depositing a film on a substrate is isolated in the same vacuum vessel. With such a configuration, the high-melting point metal used in the catalyst body, for example, a tungsten wire, reacts with SiH ₄ to generate a silicon compound, and the deterioration of the catalyst body caused by the silicon compound is reduced. It is preventing.

  Further, according to Patent Document 7, the support at the end of the catalyst body is covered with a cover, a diluent gas, an inert gas, or the like is introduced into the gap, and the temperature-lowering part at the end of the catalyst body is isolated from the raw material gas. As a result, techniques for preventing the generation of the silicon compound have been proposed.

  According to such a hot wire CVD method, excellent film characteristics can be obtained, interface characteristics of the laminated film can be improved, and an a-Si film containing hydrogen can be obtained by eliminating damage due to plasma in a film forming reaction. , The optical band gap of the a-Si film is reduced, and as a result, the photoelectric conversion efficiency of the solar cell is improved, the photodeterioration in the solar cell and the image sensor is improved, and the TFT is improved. Carrier mobility is improved.

  Next, an outline of a hot wire CVD apparatus proposed in Patent Document 2 will be described with reference to FIGS.

  FIG. 5 is a front view schematically showing the hot wire CVD apparatus 21, and FIG. 6 is a schematic plan view of the apparatus 21.

  According to the hot wire CVD apparatus 21, the gas blowing body 23 is provided at the center of the reaction chamber 27 formed of a vacuum vessel, and the gas comes into contact with the catalyst 25 through the gas blowing hole 24 to be decomposed. After the activation, a film is formed on the cylindrical film-forming base 22.

  Each film-forming substrate 22 is supported by a support 26 which is linearly arranged in parallel with the gas blowing body 23 and the catalyst 25, and the support 26 is integrally mounted on a carriage 29 having wheels 28. The substrate temperature control means 30 and the rotation transmitting means 31 are configured to be connected and disconnected in a vacuum.

  The outer surface of the gas blowing body 23 receives heat radiation from the catalyst body 25 during film formation in the same manner as the film-forming base 22, while the gas blowing body 23 receives , The radiation heat can be effectively absorbed and radiated, and as a result, there is no need to provide a radiation blocking member between the catalyst body 25 and the gas blowing body 23, and the gas use efficiency is reduced. improves.

  As shown in FIG. 6, the vacuum vessel 27 of the apparatus 21 has a plurality of film-forming substrates arranged linearly so that the film-forming substrates 22 can be integrally set and taken out. Several gate valves 32 are provided on the side wall of the container 27 orthogonal to the side 22. By connecting a plurality of vacuum vessels 27 via the gate valve 32, a vacuum chamber or a preliminary chamber for performing vacuum evacuation or preliminary heating, cooling or vacuum leak is provided before and after the film forming chamber, A so-called in-line type hot wire CVD apparatus which is excellent in mass productivity is achieved by improving the film quality of each layer by separating each film forming chamber.

Regarding the behavior of the raw material gas, based on recent research results, the gas decomposed and activated by the catalyst body, that is, the deposited species, is diffused almost uniformly and radially from the catalyst body as a starting point. It has been clarified that the arrival density from one point to a certain point on the substrate is proportional to 1 / r ² with respect to the distance r from that point to a point on the catalyst body (see Non-Patent Document 1). ).
Japanese Patent Publication No. 03-065434 Japanese Patent No. 3145536 Japanese Patent No. 2692226 JP 2000-277501 A JP 2000-277502 A JP 2001-345280 A JP 2002-93723 A NEDO University Collaborative Industrial Science and Technology R & D Project "Semiconductor Device Manufacturing Process by CaT-CVD Method" Achievement Report / Document 2001.6.4 (page 16)

  However, when each of the substrates 22 for film formation is formed using the hot wire CVD apparatus 21 of Patent Document 2 described above, unevenness in film thickness between the substrates or in the vertical direction of each substrate. It was found that film quality unevenness occurred.

  Accordingly, the present invention has been completed in view of the above circumstances, and an object of the present invention is to provide a thin film deposition apparatus (hot wire CVD apparatus) for forming a thin film having a uniform thickness on a substrate surface.

  Another object of the present invention is to provide a thin film deposition apparatus (hot wire CVD apparatus) for forming a film on a substrate surface with uniform film quality.

  The hot wire CVD apparatus of the present invention includes, in a reaction chamber, a gas blowing body, a long catalyst body, and a long film-forming substrate disposed substantially in parallel with the catalyst body. The catalyst body is disposed between the gas blow-off body and the substrate for film formation, and a plurality of gas blow-offs are provided on the gas blow-off body along a longitudinal direction of the substrate for film formation. A hole is formed, and the distribution density of the gas blowing holes is higher at both ends than at the center in the longitudinal direction of the film-forming substrate.

  Further, the hot wire CVD apparatus of the present invention is arranged along the arrangement of the gas blowing body, the plurality of deposition substrates arranged in a predetermined direction, and the deposition substrates in the reaction chamber. A catalyst body is disposed so that the catalyst body is located between the gas blowing body and the array of the film-forming substrates, and the gas blowing body is arranged in a direction in which the film-forming substrates are arranged. , A plurality of gas blowing holes are formed along the line, and the distribution density of the gas blowing holes is higher at both ends than at the center in the arrangement direction of the film-forming substrate.

  Further, in the hot wire CVD apparatus of the present invention, a plate-shaped gas blowing body having a hollow is disposed in the reaction chamber, and a catalyst body is provided so as to face a main surface of the gas blowing body. A substrate for film formation is disposed on the main surface of the gas blowing body, and a plurality of gas blowing holes are formed on the main surface of the gas blowing body, and the distribution density of the gas blowing holes is increased from the central portion of the main surface toward the outer peripheral portion. It is characterized by comprising.

  Further, the hot wire CVD apparatus of the present invention is characterized in that the substrate for film formation is cylindrical.

  Furthermore, the hot wire CVD apparatus according to the present invention is characterized in that the substrate for film formation is flat.

  According to the thin film deposition apparatus (hot wire CVD apparatus) of the present invention, the distribution density of the gas blowing holes of the gas blowing body is set at both ends in the longitudinal direction of the film-forming substrate and both ends of the array of the film-forming substrates. By increasing toward, the amount of gas blowout in the peripheral portion increases, and the gas concentration near the end portion of the catalyst body is made higher than the gas concentration near the center portion of the catalyst body, and between the bases, Alternatively, a uniform film thickness distribution is achieved in each individual substrate.

  Hereinafter, a hot wire CVD apparatus according to the present invention will be described in detail with reference to the drawings, taking as an example a case where a substrate for film formation is cylindrical.

  FIG. 1 is a schematic front view of a thin film deposition apparatus (hot wire CVD apparatus) of the present invention, FIG. 2 is a schematic top view of the apparatus, and FIG. 3 is a gas blowout viewed from the substrate side of the apparatus. Figure 2 shows a side view of the body and the catalyst body.

  In the hot wire CVD apparatus 38 shown in FIG. 1, a gas blowing body 43 is provided in the center of a reaction chamber 40 formed of a vacuum vessel, and the gas blowing body 43 is provided so as to face both main surfaces of the gas blowing body 43, respectively. The provided planar catalyst bodies 44 are provided, and the substrate 42 for film formation is arranged outside each of the catalyst bodies 44.

  The catalyst body 44 is a catalyst body having the same configuration as the catalyst body 25 shown in FIG. 5, in which nine straight tungsten wires are vertically arranged at equal intervals.

  Then, according to the hot wire CVD device 38, the gas introduced from the gas blowing body 45 comes into contact with the catalyst body 44 so as to flow along the surface thereof, and is decomposed and activated. The heat is diffused more radially, reaches the rotating substrate 42 for film formation, and is formed on the outer peripheral surface thereof. A current introduction terminal (not shown) is connected below the catalyst body 44, and is connected to an external power supply through this terminal.

  According to the present example, eight cylindrical film-forming bases 42 are arranged on both sides of the catalyst body 44 at substantially equal intervals. These arrangement surfaces are substantially parallel to the catalyst body 44.

  Each substrate 42 for film formation is supported by supports 41 linearly arranged in parallel with a gas blowing body 43 and a catalyst body 44, and each support 41 is integrally formed with a carriage 46 having wheels 47. The base temperature control means 48 and the rotation transmission means 39 are provided so that they can be connected and disconnected in a vacuum.

  The substrate temperature control means 48 is provided inside each of the supports 41, thereby setting the substrate 42 for film formation to a required temperature.

  Further, according to the hot wire CVD apparatus 38 having the above configuration, as shown in FIG. 2, the vacuum vessel 40 of the apparatus 38 has a straight line so that the substrate 42 for film formation can be integrally set and taken out. Some gate valves 46 are provided on the side wall of the container 40 on the side orthogonal to the plurality of film-forming substrates 42 arranged in a line. By connecting a plurality of vacuum vessels 40 via the gate valve 46, a vacuum chamber or a preliminary chamber for performing vacuum evacuation or preliminary heating, cooling or vacuum leak is provided before and after the film forming chamber, A so-called in-line type hot wire CVD apparatus which is excellent in mass productivity is achieved by improving the film quality of each layer by separating each film forming chamber.

  According to the hot wire CVD apparatus 38 of the present invention, in the gas blowing body 43, the distribution density of the gas blowing holes 45 is reduced toward the central portion, thereby increasing the gas blowing amount in the peripheral portion. The feature is that the gas concentration near the end of the catalyst body 44 is higher than the gas concentration near the center of the catalyst body 44.

  For example, as shown in FIG. 3, by increasing the distribution density of the gas blowing holes 45 of the gas blowing body 43 in the central portion and increasing the density in the peripheral portion, the gas blowing amount in the peripheral portion increases, and the end of the catalyst body 44 is increased. A state where the gas concentration in the vicinity of the portion is higher than the gas concentration in the vicinity of the central portion of the catalyst body 44, whereby a uniform film thickness distribution is achieved between the substrates or on the individual substrates.

  More specifically, while the inside of the reaction chamber 40 is set to a state close to a vacuum, the raw material gas is introduced into the gas blowing body 43 at a constant flow rate. At this high pressure, the raw material gas is blown out toward the catalyst body 44 through the gas blowing holes 45 of the gas blowing body 43 in an approximately inverse normal distribution form. Since the flow rates in the individual gas outlets 45 are the same, the concentration distribution of the raw material gas reaching the vicinity of the catalyst body 44 from the gas outlets 45 depends on the distribution density of the gas outlets 45.

  That is, in the place of the catalyst body 44 that receives the flow of the raw material gas from the place where the distribution density of the gas blowing holes 45 is high, the concentration of the raw material gas becomes high, and the flow of the raw material gas flows from the place where the distribution density of the gas blowing holes 45 is low. At the location of the catalyst body 44 that receives the gas, the concentration of the source gas becomes low.

  As described above, in the present example, the distribution density of the gas blowing holes 45 on both sides of the gas blowing body 43 facing the catalyst body 44 was reduced in the central portion and increased in the peripheral portion. The concentration distribution of the raw material gas in the vicinity is low in the central part in the vicinity of the catalyst body 44 and becomes high in the peripheral part, thereby complementing the substrate on which film formation is insufficient among the substrates for film formation. As a result, the film thickness can be adjusted so as to have a uniform film thickness or uniform film quality over each film forming substrate 42 or for each film forming substrate 42. it can. The thickness of the thin film and the degree of film quality distribution can be adjusted according to the density distribution of the gas blowing holes 45.

  In the present embodiment, the shape of the gas blowing body 43 is formed in a plate shape. Alternatively, the shape of the gas blowing body 43 may be formed in a curved shape.

  Further, in the above-described embodiment, the distribution density of the gas blowing holes 45 is set to be higher at the outer peripheral portion than at the central portion of the gas blowing member, but instead, as shown in FIG. The distribution density of the holes may be higher at both ends than the center in the longitudinal direction of the cylindrical film-forming substrate 42, or the distribution density of the gas blowing holes may be increased as shown in FIG. It may be higher at both ends than at the center in the arrangement direction of the film forming substrate. In this case, in the former case, the film thickness of each film-forming substrate 42 can be made substantially uniform, and in the latter case, the film thickness variation among the film-forming substrates 42 can be reduced. be able to. Further, the distribution density of the gas blowing holes is made higher at both ends than the central portion in the longitudinal direction of the cylindrical film-forming substrate 42, or the distribution density of the gas blowing holes is made higher than the central portion in the arrangement direction of the film-forming substrates. Even when the height is increased at both ends, the gas blowing body 43 is not necessarily required to be plate-shaped, but can be applied to various shapes such as a cylindrical shape and a columnar shape.

  Hereinafter, each configuration of the hot wire CVD apparatus of the present invention will be described in more detail.

  Inside each of the supports 41, a substrate temperature setting means 48 is provided to set the temperature of the substrate 42 for film formation to a required temperature. Is installed, a contact for heating and temperature detection is installed at a lower portion of the carriage 46, and an electrode contact connected to an external device is moved up and down from the lower portion to be electrically connected. Externally controlled. Alternatively, the carriage 46 and the support 41 may have a hollow structure, and the temperature control means itself may move up and down (raise and lower) when moving.

  As described above, in order to maintain the substrate temperature during film formation at a desired value even when receiving the radiant heat from the catalyst body 44, the temperature detection means (not shown) and the heating means (see FIG. (Not shown) and / or the cooling means 48 are attached so as to detect the temperature of the outer wall of the support 41 using a thermocouple, a thermistor, a temperature controller, or the like, and the cooling means held on the support 41 via the outer wall. While monitoring the temperature state of the film forming substrate 42, the heating unit and the cooling unit are controlled by a temperature controller (not shown) to maintain the substrate temperature at a desired value.

  As the heating unit, an electric device such as a nichrome wire, a sheath heater, a cartridge heater, or the like, or a heat medium such as oil is used. As the cooling means, a gas such as air or nitrogen gas, or a cooling medium composed of water, oil, or the like is used so as to circulate inside the substrate support 41. The substrate temperature during film formation is controlled to a constant temperature of 100 to 500 ° C., preferably 200 to 350 ° C. by the substrate temperature control means 48.

  Further, a rotation motor is provided on each of the supports 41, and the motor rotates the support 41 via the rotation transmission means 39, and at the same time, rotates the film-forming base 42.

  The motor and the rotation transmitting means 39 may be configured to 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 electric wiring, and a combination of a quick coupling and a solenoid is used for the medium. For transmission of power for rotation and conveyance, combinations of gears or combinations of gears and solenoids are used. At the contact point between the rotation transmitting means 39 and the container 40, there is provided a rotation mechanism for functioning the base temperature control means while maintaining the vacuum inside the apparatus. Such a rotating mechanism uses a vacuum sealing means such as an oil seal or a mechanical seal having a double or triple rotating shaft, and a temperature detecting means and a heater wiring and a heating and cooling inside the hollow rotating shaft. A circulation path for a medium such as the above is provided. A slip ring, a rotation introduction terminal, or the like is used to connect a circulation path of a medium for heating, cooling, or the like to an external control device.

  The container 40 has a gas exhaust pipe connected to a vacuum pump (not shown) at the lower part, and is also connected to a pressure gauge (not shown) for monitoring the degree of vacuum.

  The material of the film-forming substrate 42 is selected from those having conductivity, insulation, or the surface of an insulating substrate subjected to a conductive treatment, depending on the use of the product.

  Examples of the conductive substrate include metals such as aluminum (Al), stainless steel (SUS), iron (Fe), nickel (Ni), chromium (Cr), manganese (Mn), copper (Cu), and titanium (Ti). Or these alloys are mentioned.

  Examples of the insulating substrate include glasses such as borosilicate glass, soda glass, and Pyrex (R) glass; inorganic insulators such as ceramics, quartz, and sapphire; and fluorocarbon resins, polycarbonate, polyethylene terephthalate, polyester, polyethylene, and polypropylene. Examples include synthetic resin insulators such as polystyrene, polyamide, vinylon, epoxy, and mylar. These insulating substrates are subjected to a conductive treatment at least on the surface on which a film is to be formed, if necessary.

  This conductive treatment includes a conductive layer of ITO (indium tin oxide), tin oxide, lead oxide, indium oxide, copper iodide, or the like, Al, Ni, gold (Au), or the like on the surface of the insulating substrate. The metal layer is formed by 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, a coating method, It is performed by forming by an immersion method or the like.

  Further, as a material of the catalyst body 44, a catalytic reaction or a thermal decomposition reaction occurs in at least a part of the raw material gas, and a reaction product thereof is used as a deposition species, and the catalyst material itself is deposited by sublimation or evaporation. Those that are hardly mixed into the film are selected.

Such materials include tungsten (W), platinum (Pt), palladium (Pd),
There are molybdenum (Mo), titanium (Ti), niobium (Nb), tantalum (Ta), cobalt (Co), nickel (Ni), chromium (Cr), manganese (Mn), and alloys thereof.

  The structure of the catalyst body 44 is shown in FIGS.

  According to FIG. 12, as shown in the three configurations (a), (b), and (c), the material of the above-described catalyst body 44 is formed inside the window frame-shaped (square frame-shaped) insulating member 67. This is a structure in which a wire 64 that mainly generates heat is stretched.

  In the catalyst body shown in (a), both ends of each wire 64 are joined to a metal electrode 68, and both metal electrodes 68 are electrically connected to the outside via the current introduction terminals 62. Reference numeral 69 denotes a mounting hook for fixing the wire 64 to the metal electrode 68.

  In the catalyst body shown in (b) and (c), the wire 64 is stretched in a zigzag manner by the mounting hook 69.

  As described above, one or a plurality of wires 64 or a filament, a ribbon, or the like is used to form a grid, a saw, or a fixed wave, and one or more wires 64 are stretched on a plane, thereby providing a gas-permeable structure.

  Alternatively, the main body of the above-described catalyst body 44 is mainly composed of heat, so that the main body is a lattice, mesh, or mesh as shown in six types of catalyst bodies (a) to (f) shown in FIG. And a honeycomb structure, or a structure in which wires, filaments, ribbons, and the like are combined with a lattice shape, a mesh shape, a mesh shape, and a honeycomb shape.

  In addition, a thin flat plate made of the above-described material may be provided on a thin plate made of the above-mentioned materials with various shapes including a circle, a triangle, a square, a rectangle, a diamond, a hexagon, a vertically long slit, a horizontally long slit, an oblique slit, and a combination thereof. A configuration in which many pores are provided may be adopted. The catalyst body having such a configuration is shown in five ways (g) to (k) shown in FIG.

  In addition, a plurality of cylindrical flat plates provided with ventilation holes, the catalyst body of the stacked configuration such that the ventilation holes do not overlap each other, and have a gap through which gas passes between the cylindrical flat plates. Is also good. These catalysts are shown in (i) and (m).

  According to the catalyst body 44 having the above-described configuration, electric power is supplied from the outside of the vacuum vessel 40 via the current terminal 62, and the temperature is increased to 500 to 2200 ° C., preferably 800 to 2000 ° C. by Joule heat by energization. Heated.

  The position of the film-forming substrate 42 held by the substrate support 41 is preferably designed so that heat radiation from the catalyst body 44 is radiated and absorbed.

  According to the experiment repeatedly performed by the inventor, it differs depending on the material, thickness, size, etc. of the support 41 and the substrate 42 for film formation, but the points such as heat radiation and deposition density, uniformity of film thickness, etc. Therefore, the interval between the film-forming base 42 and the catalyst body 44 is preferably 10 to 150 mm, preferably 40 to 80 mm, and most preferably 50 to 70 mm.

  When an a-Si film is formed using the hot wire CVD apparatus of the present invention, the source gas for the a-Si film is the same as that used in the glow discharge plasma CVD method.

As a film forming material gas, a compound composed of silicon and hydrogen or a halogen element, for example, SiH ₄ , Si ₂ H ₆ , Si ₃ H ₈ , SiF ₄ , SiCl ₄ , SiCl ₂ H ₂ or the like is used.

As the diluting gas, H ₂ , N ₂ , He, Ar, Ne, Xe or the like is used.

The valence electron control gas includes a compound containing an element (B, Al, Ga, or the like) of Group IIIB of the periodic table as a P-type impurity, for example, B ₂ H ₆ , B (CH ₃ ) ₃ , Al (CH ₃ ) ₃ , Al (C ₂ H ₅ ) ₃ , Ga (CH ₃ ) ₃ or the like is used, and a compound containing an element (P, As, Sb, or the like) of Group V B of the periodic table as an N-type impurity is used. For example, PH ₃ , P ₂ H ₄ , AsH ₃ , SbH _{3 and the} like are used.

Examples of the band gap adjusting gas include compounds containing C, N, and O, which are elements for expanding the band gap, such as CH ₄ , C ₂ H ₂ , C ₃ H ₈ , N ₂ , NH ₃ , NO, and N. ₂ O, NO ₂ , O ₂ , CO, CO ₂ and the like, and compounds containing Ge and Sn which are band gap narrowing elements, for example, GeH ₄ , SnH ₄ , Sn (CH ₃ ) _{3 and the} like are used.

  In film formation, these gases are adjusted to desired flow rates and mixing ratios using a pressure reducing valve, a mass flow controller, or the like, introduced into a vacuum vessel 40, and supplied from a gas blowing body 43 to a catalyst body 44.

The gas pressure at the time of film formation is set to 0.1 to 300 Pa, preferably 2 to 6 Pa. By setting the gas pressure in such a range, the supplied gas is efficiently decomposed and transported. In addition, since a secondary reaction in the gas phase between the reaction products is suppressed, a high-quality a-Si-based film can be formed on the base. In order to obtain a higher quality film, before starting the film formation, the inside of the vacuum container 40 after the substrate is set is once evacuated to a high vacuum of about 10 ⁻² Pa, and the inside of the container is evacuated. It is desirable to remove moisture and residual impurity gas.

  (Example 1) and (Example 2) explain a case where the substrate for film formation is a flat plate shape. (Example 1) shows a comparative hot wire CVD apparatus first, and (Example 2) shows the present invention. 1 shows a hot wire CVD apparatus. Further, a hot wire CVD apparatus of the present invention in which the substrate for film formation is cylindrical will be described by (Example 3).

(Example 1)
In the hot wire CVD apparatus shown in FIG. 5, the raw material gas blown out from the blowing hole 24 of the gas blowing body 23 is decomposed and activated by the catalyst 25 to become a reactive species. The reaction species are thermally diffused almost uniformly and radially from the catalyst body 25 as a starting point, and the arrival density from one point on the catalyst body 25 to a certain point on the base body 22 is determined by that point and the point on the catalyst body 25. It is proportional to 1 / r ² with respect to the distance r to. Therefore, in order to make the gas concentration distribution reaching the surface of the base body 22 uniform, that is, to form a thin film having a uniform thickness on the base body 22, the gas concentration in the central portion near the catalyst body 25 is reduced. It is necessary to increase the gas concentration in the part.

  The present inventor has confirmed this point through experiments as follows. In the apparatus 21, the cylindrical substrate 22 was used. Instead, as shown in FIG. 8, a flat substrate 22 '(an Al plate having a width of 350 mm, a height of 350 mm, and a thickness of 5 mm) was mounted on the support 26'. The set hot wire CVD apparatus 21 'was manufactured, and the following experiment was performed using this apparatus 21'.

  In this experiment, nine tungsten wires each having a diameter of 0.5 mm and arranged vertically in a grid shape with a width of 50 mm and a width of 50 mm are used as the catalyst body 25. The a-Si film is formed by disposing the catalyst body 25 with a gap of 50 mm (distance from the surface of the catalyst body 25 to the surface of the flat substrate 22 ') with the base 22'. The gas blowing holes 24 are formed in a circular shape having a diameter of 1 mm, are arranged in a matrix at equal intervals of 25 mm, and are uniformly blown to the catalyst body 25 in a shower shape. Then, the distance between the gas blowing body 23 and the catalyst body 25 (the distance from the surface of the gas blowing body 23 to the surface of the catalyst body 25) was set to 30 mm.

  When the film was formed using the hot wire CVD apparatus having the above-described configuration, the film thickness distribution on the film formation surface of the flat substrate 22 ′ when the film was formed using the hot wire CVD apparatus 21 ′ was measured. The result as shown in FIG. 19 was obtained.

  In these figures, straight lines AB and CD represent a straight line connecting points A and B, and a straight line connecting points C and D, respectively, in the gas blowing body 23 shown in FIG.

  FIG. 18 is a line showing a film thickness distribution corresponding to a straight line AB of the thin film formed on the base 22 ′ in FIG. 8, and the horizontal axis represents each line between the points A and B shown in FIG. The vertical axis indicates the relative film thickness value at each part (position) between point A and point B when the maximum film thickness is set to 1.

  FIG. 19 is a diagram showing a film thickness distribution corresponding to the straight line CD of the thin film formed thereon on the base 22 ′ shown in FIG. 8, and the horizontal axis represents the points C and D shown in FIG. The vertical axis indicates a relative film thickness value at each part (position) between point C and point D when the maximum film thickness is set to 1.

  As is clear from these results, in both the vertical direction and the horizontal direction, the center shows a gently convex shape with a convex at the center, and the difference in film thickness between the center and both ends is as large as 20 to 30%.

(Example 2)
According to the gas blowing body 23 of the conventional hot wire CVD apparatus 21 ′ shown in FIG. 8, the gas blowing holes 24 are formed almost uniformly over the plate surface. In this example, as in the hot wire CVD apparatus 38 'shown in FIG. 4, the distribution density of the gas blowing holes 45 on both sides of the gas blowing body 43 facing the catalyst body 44 is directed toward the center. The lower one is used.

  Then, an a-Si film was deposited using the hot wire CVD device 38 'under the conditions shown in Table 1, and the film thickness distribution was confirmed as in FIGS. The results are shown in FIGS. 9 and 10.

  The material and dimensional relationship between the gas blowing body 43, the catalyst body 44, and the substrate 82 of the hot wire CVD apparatus 38 'in this embodiment are as follows.

Plate base 82 dimensions: 350 × 350 × 5 mm
Substrate 82 material: Al plate Dimensions and material of catalyst body 44: Nine tungsten wires having a diameter of 0.5 mm are vertically arranged at equal intervals with a width of 50 mm, and by combining these wires, 460 × The size is 460 mm.

Distance between catalyst body 44 and substrate 82: 50 mm
Distance between catalyst body 44 and gas blowing body 43: 30 mm
Diameter of each gas blowing hole 45: 1 mm
The pitch between the gas blowing holes 45 is 35 mm in a 200 × 200 mm area at the center and 25 mm in a peripheral area.

Height a of side surface of gas blowing body 43 facing catalyst body a: 460 mm

  As is clear from the results shown in FIGS. 9 and 10, the film thickness unevenness which was 20 to 30% in the conventional substrate range was improved to about 10% or less, and good results were obtained.

(Example 3)
The inventor manufactured an a-Si photosensitive drum having a laminated structure as shown in FIG. 11 in the hot wire CVD apparatus 38 shown in FIG. In FIG. 11, reference numeral 34 denotes an Al base, and reference numerals 35, 36, and 37 denote a charge injection blocking layer, a photoconductive layer, and a surface protection layer, respectively.

The film formation was performed under the conditions shown in Table 2.

  The material and dimensional relationship of the gas blowing body 43, the catalyst body 44, and the base 42 in this embodiment are shown below.

Base 42 dimensions: 254 x 30 mm
Substrate 42 material: Al plate Dimensions and material of catalyst body 44: Nine tungsten wires having a diameter of 0.5 mm are vertically arranged at equal intervals with a width of 50 mm, and by combining these wires, 460 × The size is 460 mm.

Distance between catalyst body 44 and substrate 42: 50 mm
Distance between catalyst body 44 and gas blowing body 43: 30 mm
Diameter of each gas blowing hole 45: 1 mm
The pitch between the gas blowing holes 45 is 35 mm in the central 200 × 200 mm area, and 25 mm in the peripheral area.

Height a of side surface of gas blowing body 43 facing catalyst body a: 460 mm
Table 3 shows the film thickness distribution of the 16 a-Si photosensitive drums thus obtained. This table shows the ratio (%) to the maximum film thickness. In Table 3, drums 1 to 8 represent drums 1 to 8 in the hot wire CVD apparatus shown in FIG. The upper, middle, and lower portions of the drum represent a position 30 mm from the upper end of the drum, a position at the center of the drum, and a position 30 mm from the lower end of the drum, respectively.

  As is clear from Table 3 above, very good results were obtained when the variation in the thickness of all the drums was 10% or less.

Next, the charging characteristics of these drums were measured using a corona charger to which a voltage of +6 kV was applied, and the light sensitivity characteristics were reduced by half-exposure from 250 V with monochromatic light having a center wavelength of 680 nm and a half-value width of 2 nm. The residual potential was evaluated, and the fog and resolution were evaluated using an electrophotographic printer FS-1550 manufactured by Kyocera. The results shown in Table 4 were obtained.

  As is clear from the table, a high-quality a-Si drum with excellent non-uniformity and low resolution is obtained in the image evaluation. Was done.

  Thus, according to the hot wire CVD apparatus 38 of the present invention, the gas concentration in the vicinity of the catalyst body 44 is made thinner in the central part and the gas concentration in the peripheral part is made denser. By forming a structure with a low density at the portion and a high density distribution at the outer portion, it was possible to mass-produce a good a-Si photosensitive drum having a small thickness unevenness at the outer and center portions.

  It should be noted that the present invention is not limited to the above embodiment, and various changes and improvements may be made without departing from the spirit of the present invention.

1 is a schematic front view of a hot wire CVD apparatus using a drum substrate according to the present invention. 1 is a schematic top view of a hot wire CVD apparatus using a drum substrate according to the present invention. FIG. 2 is a side view of a gas blowing body and a catalyst body as viewed from a substrate on which a film is formed in the hot wire CVD apparatus according to the present invention. 1 is a schematic front view of a hot wire CVD apparatus using a flat substrate according to the present invention. 1 is a schematic plan view of a hot wire CVD apparatus using a drum substrate according to a conventional technique. 1 is a schematic top view of a hot wire CVD apparatus using a drum substrate according to a conventional technique. FIG. 4 is a side view of a gas blowing body and a catalyst body as viewed from a substrate on which a film is formed in a hot wire CVD apparatus according to a conventional technique. 1 is a schematic front view of a hot wire CVD apparatus using a flat substrate according to a conventional technique. 5 is a graph showing a film thickness distribution of a thin film formed by a hot wire CVD apparatus using a flat substrate according to the present invention. 5 is a graph showing a film thickness distribution of a thin film formed by a hot wire CVD apparatus using a flat substrate according to the present invention. FIG. 2 is a cross-sectional view illustrating a layer configuration of an electrophotographic photosensitive member formed by a hot wire CVD apparatus according to the present invention. (A) to (C) are front views of main parts of the catalyst body according to the present invention. (A)-(m) is a principal part front view of the catalyst body concerning this invention. It is a side view of the modification of the gas blowing body shown in FIG. It is a side view of the modification of the gas blowing body shown in FIG. It is a front schematic diagram of the conventional glow discharge plasma CVD apparatus. It is a front schematic diagram of the conventional hot wire CVD apparatus. 9 is a graph showing a film thickness distribution by a conventional hot wire CVD apparatus. 9 is a graph showing a film thickness distribution by a conventional hot wire CVD apparatus.

Explanation of reference numerals

11 ... motors 14, 27, 40 ... reaction chambers 16, 22, 42 ... film-forming substrates 17, 25, 44 ... catalyst bodies 21, 38 ... hot wire CVD apparatus 24, 45 ... gas blowing bodies 26, 41 ... supports 30, 48 ... substrate temperature setting means 44 ... wires

Claims (5)

In the reaction chamber, a gas blowing body, a long catalyst body, and a long film-forming substrate disposed substantially parallel to the catalyst body are formed by the gas blowing body and the film-forming body. A plurality of gas blowing holes are formed in the gas blowing body along a longitudinal direction of the film-forming substrate, and the gas blowing holes are formed in the gas blowing body. Characterized in that the distribution density is higher at both ends than at the center in the longitudinal direction of the film-forming substrate. In the reaction chamber, a gas blowing body, a plurality of film-forming substrates arranged in a predetermined direction, and a catalyst body arranged along the arrangement of the film-forming substrates, the gas blowing body and The catalyst body is disposed so as to be positioned between the substrate and the film-forming substrate, and a plurality of gas blowing holes are formed in the gas blowing body along the direction in which the film-forming substrates are arranged. A hot wire CVD apparatus characterized in that the distribution density of the gas blowing holes is higher at both ends than at the center in the arrangement direction of the substrate for film formation. In the reaction chamber, a plate-shaped gas blowing body having a hollow is provided, a catalyst body is provided so as to face a main surface of the gas blowing body, and a substrate for film formation is arranged outside these catalyst bodies. Further, a hot wire CVD apparatus in which a plurality of gas blowing holes are formed in a main surface of the gas blowing body, and a distribution density of the gas blowing holes is increased from a central portion of the main surface toward an outer peripheral portion. 4. The hot wire CVD apparatus according to claim 1, wherein the substrate for forming a film has a cylindrical shape. 4. The hot wire CVD apparatus according to claim 1, wherein the substrate for film formation is a flat plate.

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