JP4903473B2 - Heating element CVD equipment - Google Patents

Description

  The present invention relates to a heating element CVD apparatus that forms a film by depositing decomposition components by decomposing a source gas with heat generated by a heating element.

  The CVD method is often used for film formation of various semiconductor devices. The CVD method includes a plasma CVD method, a thermal CVD method, and a heating element CVD method. Among these CVD methods, the heating element CVD method is a film forming method in which a source gas is decomposed by the heat of the heating element and is formed on a substrate (for example, see Patent Documents 1 and 2). Therefore, the heating element CVD method can lower the temperature of the substrate during film formation compared to the thermal CVD method, so that the range of use of the substrate material can be widened, and a film on the substrate can be formed like the plasma CVD method. It has the advantage that it is not damaged by plasma. For these reasons, the heating element CVD method has attracted attention as a film forming method capable of obtaining high-quality films on various substrates.

  As a heat generating body CVD apparatus, there exists a thing of the structure shown, for example in FIG. 6 (for example, refer patent document 3). The heating element CVD apparatus 9 shown in the figure is configured to laminate two or more kinds of films on the surface of the substrate 90. In the heating element CVD apparatus 9, the source gas is supplied to the film forming chamber 93 by the gas supply means 92 in a state where the base 90 is held by the base holding means 91, while the source gas is supplied to the first or second heating element 94. , 95, and the film is formed by depositing the decomposition components at that time on the surface of the substrate 90.

  For example, in the heating element CVD apparatus 9, when an amorphous silicon (a-Si) layer and an a-SiC (amorphous silicon carbide) layer are sequentially laminated on the surface of the substrate 90, the formation is performed as follows. A membrane is performed.

First, the first source gas for forming the a-Si layer is supplied to the film forming chamber 93 using the gas supply means 92 in a state where the film forming chamber 93 is kept in a vacuum state using a vacuum pump (not shown). To do. As the first source gas, for example, a mixed gas of SiH ₄ and H ₂ is used. In the film forming chamber 93, the first source gas is brought into contact with the first heating element 94 in a state where the first heating element 94 is heated to 1600 ° C. to 1800 ° C. Thereby, the first source gas is decomposed, Si generated at that time is deposited on the surface of the base body 90, and an a-Si layer is formed on the surface of the base body 90.

Next, the second source gas for forming the a-SiC layer is supplied to the film forming chamber 93 using the gas supply unit 92 while the vacuum state of the film forming chamber 93 is maintained. As the second source gas, for example, a mixed gas of SiH ₄ , C ₂ H ₂ and H ₂ is used. In the film forming chamber 93, the second source gas is brought into contact with the second heating element 95 in a state where the second heating element 95 is heated to 2000 ° C. to 2500 ° C. As a result, the second source gas is decomposed, and at that time, generated SiC is deposited on the surface of the base body 90, and an a-SiC layer is formed on the surface of the base body 90.

JP 2005-133161 A JP 2005-133162 A JP 2005-179768 A

By the way, in the film-forming method by the above-mentioned heating element CVD method, the first and second heating elements 94 and 95 generally have the same form (wire diameter, element). On the other hand, the temperature of the first heating element 94 needs to be a temperature at which the first heating element 94 does not react with the silicon compound and can decompose the silicon compound. The temperature needs to be a temperature at which the second heating element 95 does not react with the carbon compound and decomposes the carbon compound. For example, as the first and second heating elements 94 and 95, when a single Gusuten (W) or tantalum (Ta), as the temperature of the first heating element 94 is required above 1600 ° C., second heating The temperature of the body 95 is required to be 2000 ° C. or higher.

  However, when the second heating element 95 having the same form as that of the first heating element 94 is set to a high temperature of 2000 ° C. or more, the substrate 90 moves to the substrate 90 as compared with the time when the a-Si layer is formed on the first heating element 94. The heat radiation increases dramatically. Therefore, the temperature of the base body 90 increases due to the heat radiation from the second heating element 95. On the other hand, the temperature of the substrate 90 is controlled to 200 ° C. to 350 ° C. during the formation of the a-Si layer and the a-SiC layer by the heating / cooling means 96 inside the substrate support 91. However, when the heat radiation from the second heating element 95 is large, the cooling effect from the inside of the substrate support 91 by the heating / cooling means 96 cannot be sufficiently obtained, and the temperature of the substrate 90 is appropriately set. There is a problem that it is difficult to control.

  The present invention has been devised in view of the above problems, and the problem is that even when a plurality of layers are formed on a substrate in the same film formation chamber, the temperature control of the substrate can be performed easily and easily. It is an object of the present invention to provide a heating element CVD apparatus that can perform reliably.

In the first aspect of the present invention, the film forming chamber for housing the substrate, the first heating element disposed in the film forming chamber so as to be in contact with the first source gas, and the second source gas are in contact with each other. wherein the second heating element arranged in the deposition chamber, comprising a, and, depositing a cracking component when decomposing the first raw material gas by the heat from the first shot heat body before SL on substrates Then, in the heating element CVD apparatus for depositing a decomposition component when the second source gas is decomposed by heat from the second heating element to form a film on the substrate , the second source gas is The first source gas has a different composition and is decomposed at a higher temperature than the first source gas, and the second heating element has a higher heating temperature than the heating temperature of the first heating element. together are configured, the wire diameter than the first heating element is small Characterized Rukoto, heating element CVD system is provided.

  The wire diameter of the second heating element is preferably 0.2 to 0.8 times, more preferably 0.4 to 0.6 times the wire diameter of the first heating element.

In the second aspect of the present invention, the film forming chamber for accommodating the substrate, the first heating element disposed in the film forming chamber so as to be in contact with the first source gas, and the second source gas are in contact with each other. wherein the second heating element arranged in the deposition chamber, comprising a, and, depositing a cracking component when decomposing the first raw material gas by the heat from the first shot heat body before SL on substrates Next, in the heating element CVD apparatus for forming a film by depositing a decomposition component when the second source gas is decomposed by heat from the second heating element on the substrate , the first source gas is silicon. consists of a system compounds, together with the second material gas is composed of a silicon compound and a carbon-based compound, the second source gas, which is decomposed at a temperature higher than the first material gas, the The first heating elements are tantalum (Ta), tungsten (W , Platinum (Pt), palladium (Pd), molybdenum (Mo), titanium (Ti), niobium (Nb), cobalt (Co), nickel (Ni), chromium (Cr), and manganese (Mn) The second heating element is formed of a material containing rhenium (Re) as a main component or an alloy component. The second heating element is formed of a material containing at least one selected as a main component or an alloy component. A heating element CVD apparatus is provided.

The first source gas, for example, a silicon compound, the second source gas, for example, composed of silicon compound and a carbon-based compound.

  According to the first aspect of the present invention, the wire diameter of the second heating element is made smaller than the wire diameter of the first heating element. Therefore, even if the heating temperature of the second heating element is kept high, the surface area of the second heating element is made smaller than that of the first heating element, so that the amount of heat generated in the second heating element can be suppressed. Therefore, even when film formation is performed using the second source gas that is decomposed at a high temperature, the amount of radiant heat at the second heating element can be reduced while maintaining the heating temperature of the second heating element high. As a result, the temperature of the substrate can be prevented from becoming too high during film formation using the second source gas. As a result, as in the case where film formation is performed using the first source gas that is decomposed at a lower temperature than the second source gas, the cooling effect of the substrate by the cooling means can be sufficiently obtained. The temperature control of the substrate can be performed easily and reliably.

  In the present invention, if the second heating element is formed of a Re-based material, the decomposition temperature of the source gas during film formation is higher than when the heating element is formed of tungsten (W), tantalum (Ta), or the like. Can be set low. For example, when a material containing a carbon compound is used as a raw material gas, in the heating element of tungsten (W) or tantalum (Ta), it is necessary to set the decomposition temperature of the carbon compound to a high temperature of 2000 ° C. or higher as described above. On the other hand, in the Re-based material heating element, the decomposition temperature of the carbon compound can be set to about 1800 ° C. As described above, when a Re-based material heating element is used as the second heating element, the temperature of the second heating element can be made closer to the temperature of the first heating element. (For example, when forming an a-SiC layer) and when forming a film with the second heating element (for example, when forming an a-SiC layer), the difference in the amount of heat radiation is reduced. The temperature of the substrate is not so high. As a result, since the cooling effect of the substrate by the cooling means can be sufficiently obtained even during the film formation by the second heating element, the temperature control of the substrate during the film formation can be performed easily and reliably.

  Further, by separately providing a first heating element for the first source gas and a second heating element for the second source gas, for example, after the first source gas is decomposed to form a deposited film, the second heating element is formed. When the deposited gas is formed by decomposing the source gas, the decomposition component of the first source gas adhering to the surface of the first heating element when the first source gas is decomposed decomposes and deposits the second source gas. When the film is formed, it can be suppressed from being taken into the deposited film by the second source gas. For this reason, the characteristics of the deposited film by the second source gas are not impaired by the decomposition component of the first source gas, so that a plurality of deposited films having the desired characteristics can be obtained appropriately.

  Hereinafter, a heating element CVD apparatus according to the present invention will be described with reference to the drawings.

  A heating element CVD apparatus 1 shown in FIGS. 1 and 2 is for forming a deposited film on a cylindrical substrate 30 in a film forming chamber 20 defined by a container 2. Two base support bodies 4, a rotation means 5, a gas supply means 6, and first or second heating means 7 and 8 are provided.

The container 2 is formed so that a part of the upper lid can be opened and closed so that the cylindrical substrate 30 can be taken into and out of the film forming chamber 20, and has a gas exhaust port 21. The gas exhaust port 21 is for exhausting the gas in the film forming chamber 20 to the outside, and is connected to a pump (for example, a mechanical booster pump or a rotary pump) not shown. The film forming chamber 20 is maintained in a vacuum state by exhausting gas from the film forming chamber 20 through the gas exhaust port 21 by a pump (not shown). The pressure in the film forming chamber 20 is, for example, about 1.0 to 100 Pa during film formation. Moreover, it is preferable that the film forming chamber 20 is previously set to a high vacuum of about 10 ⁻³ Pa before film formation. Then, since moisture and residual impurity gas are removed from the film forming chamber 20 before film formation, the water and residual impurity gas remaining in the film forming chamber 20 are decomposed and deposited on the cylindrical substrate 30. Can be prevented.

  The plurality of substrate supports 4 (two in the drawing) are for holding the cylindrical substrate 30 and are rotatably supported by the container 2 by the rotating means 5. The cylindrical substrate 30 is held by the substrate support 4 with the substrate support 4 inserted through the cylindrical substrate 30. Each substrate support 4 is formed in a hollow cylindrical shape, and temperature adjusting means 40 is provided therein.

  The temperature adjusting means 40 is for maintaining the temperature of the cylindrical substrate 30 at a target temperature, and has a heating / cooling mechanism and a temperature detection mechanism. As the heating mechanism, for example, an electrical device such as a nichrome wire, a sheathed heater and a cartridge heater, or a device using oil or the like as a heat medium is used. As the cooling mechanism, for example, a gas such as air and nitrogen gas, water or Oil or the like is used as a cooling medium. In the heating / cooling mechanism, it is preferable to configure the heat transfer medium that circulates and flows through the inside of the substrate support 4 with a liquid or gas as the heat transfer medium. As the temperature detection mechanism, a thermistor, a thermocouple, or the like is used.

  In such temperature adjusting means, the temperature of the substrate support 4 is monitored by the temperature detection mechanism, and the heating / cooling mechanism is controlled by the control means (not shown), so that the substrate support is formed before and during film formation. 4 (cylindrical substrate 30) is adjusted to the target temperature.

  Here, the temperature of the cylindrical substrate 30 is determined by the composition of the deposited film to be formed on the surface of the cylindrical substrate 30, the material of the cylindrical substrate 30, and the like. For example, the temperature of the a-Si system or the a-SiC system is used. In the case of forming a deposited film, the temperature is controlled to a substantially constant temperature of 100 to 400 ° C, preferably 200 to 350 ° C.

  As the substrate, various shapes other than a cylindrical shape, for example, a flat shape can be used. In order to use a flat substrate, the substrate support 4 is surrounded by a plurality of flat substrates so that the whole of the plurality of flat substrates is substantially cylindrical or polyhedral. A substrate is supported. In addition, when a flat substrate is used, the substrate support may be formed in a flat plate shape or a polygonal column shape.

  The rotating means 5 is for rotating each substrate support 4 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. Note that a rotating mechanism capable of maintaining the vacuum of the film forming chamber 20 is provided at the contact point between the rotating means 5 and the container 2. As such a rotation mechanism, vacuum seal means such as an oil seal or a mechanical seal having a double or triple rotation shaft can be used. Further, when the temperature of the cylindrical substrate 30 is detected to control the temperature of the cylindrical substrate 30, the rotation shaft is formed hollow, and the temperature detection mechanism, its wiring, etc. are provided inside the rotation shaft. Can also be provided.

  When the substrate support 4 is rotated by such a rotating means 5, the cylindrical substrate 30 held on the substrate support 4 can be rotated. Therefore, the first and second heat generating means 7, 8 The decomposed components of the decomposed source gas can be deposited in a substantially uniform film thickness over the entire surface of the cylindrical substrate 30. The rotation speed of the substrate support 4 by the rotating means 5 is, for example, 1 to 10 rpm.

  The gas supply means 6 is for supplying a source gas to the film forming chamber 20 and includes a gas blowing portion 60 and a plurality (four in the drawing) of gas cylinders 61A, 61B, 61C, 61D. .

  The gas blowing section 60 is for blowing the source gas of the gas cylinders 61A, 61B, 61C, 61D into the film forming chamber 20. The gas blowing portion 60 is formed in a hollow rod shape having a plurality of gas blowing holes 60A. The plurality of gas blowing holes 60A are for blowing the source gas toward the first and second heating elements 70, 80 of the first and second heat generating means 7, 8, and these gas blowing holes 60A are Arranged at equal intervals in the longitudinal direction of the gas blowing part 60 so as to face the first and second heating elements 70, 80. The plurality of gas blowing holes 60A are formed in a circular shape, for example, and the interval thereof is, for example, 10 to 30 mm, and the hole diameter thereof is, for example, 0.5 to 2.0 mm.

  Of course, the configuration of the gas blowing section 60 can be variously changed, and it may be in the form of a plate or a drum in addition to the rod shape, and the gas blowing section 60 may be separated from the container 2. , At least a part may be integrated. In addition to the circular shape, the gas blowing hole 60A may have various shapes such as a triangle, a square, a rectangle, a rhombus, or a hexagon.

  The plurality of gas cylinders 61A, 61B, 61C, 61D are filled with the raw material gas to be supplied to the film forming chamber 20, and are connected to the gas blowing section 60 via the pipes 62A, 62B, 62C, 62D, 63. ing. Here, FIG. 1 shows an example of gas cylinders 61A, 61B, 61C, 61D in the case where a-Si-based and a-SiC-based deposited films are formed on the surface of the cylindrical substrate 30. That is, each of the source gas cylinders 61A, 61B, 61C, 61D is filled with a Si source gas, a C source gas, a charged electron control source gas, or a dilution gas. In the middle of the pipes 62A, 62B, 62C, 62D, 63, pressure reducing valves 63A, 63B, 63C, 63D and mass flow controllers 64A, 64B, 64C, 64D are provided. It is possible to adjust the flow rate, gas pressure, and composition of the raw material gas components.

Examples of the Si source gas include compounds composed of Si and H, such as SiH ₄ , Si ₂ H ₆ , and Si ₃ H ₈ , and compounds composed of silicon and a halogen element, such as SiF ₄ , SiCl ₄ , or Si H _2. Cl ₂ or the like can be used. These source gases constitute a first source gas when an a-Si-based deposited film is formed, and a second source gas when an a-SiC-based deposited film is formed.

As the C source gas, for example, a compound containing C such as CH ₄ , C ₂ H ₂ , C ₃ H ₈ , CO, or CO ₂ is used. These C source gases constitute the second source gas together with the Si source gas when an a-SiC-based deposited film is formed.

As a valence electron control gas (a gas for controlling the number of valence electrons in the film), a P-type impurity or an N-type impurity can be used. Examples of P-type impurities include compounds containing Group 13 elements (B, Al, Ga, etc.), such as 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 can be used. On the other hand, as the N-type impurity, a compound containing an element belonging to Group 15 of the periodic table (P, As, Sb, etc.), for example, PH ₃ , P ₂ H ₄ , AsH ₃ , SbH _3, etc. can be used.

The diluent gas can be used, for example _{H 2, N 2, He,} Ar, Ne, and Xe.

Moreover, you may use the band gap adjustment gas as needed. As the band gap adjusting gas, when increasing the band gap, a compound containing C, N, O, for example, CH ₄ , C ₂ H ₂ , C ₃ H ₈ , N ₂ , NH ₃ , NO, N ₂ O, NO ₂ , O ₂ , CO, and CO ₂ can be used. When the band gap is reduced, for example, a compound containing Ge or Sn, for example, GeH ₄ , SnH ₄ , Sn (CH ₃ ) ₃ is used. Can be used.

  The first or second heat generating means 7 and 8 are for decomposing the source gas. More specifically, the first heat generating means 7 is for decomposing the first source gas having a low decomposition temperature, and has a first heat generating body 70 and electrodes 71 and 72. On the other hand, the second heat generating means 8 is for decomposing the second source gas having a high decomposition temperature, and includes a second heat generating body 80 and electrodes 81 and 82. These heating means 7 and 8 are joules generated in the first or second heating elements 70 and 80 when electric power is supplied to the first or second heating elements 70 and 80 via the electrodes 71, 72, 81 and 82. The material gas is decomposed by heat.

  The first and second heating elements 70 and 80 are composed of linear resistors, and are arranged on the same straight line as the gas blowing section 60 in plan view. These heating elements 70 and 80 are made of, for example, a single wire, filament, or ribbon, and any one of these wires can be bundled. As a material for forming the first and second heating elements 70 and 80, a catalytic reaction or a thermal decomposition reaction is caused with the raw material gas, the reaction product can be used as a deposition species, and a relatively high melting point (for example, The melting point is 2600 ° C. to 3400 ° C.), and the heating element itself is not easily mixed into the film deposited by sublimation or evaporation. Examples of such materials include tantalum (Ta), tungsten (W), platinum (Pt), palladium (Pd), molybdenum (Mo), titanium (Ti), niobium (Nb), cobalt (Co), nickel ( A material having at least one selected from the group consisting of Ni), chromium (Cr), manganese (Mn), and rhenium (Re) as a main component or an alloy component can be given.

  Here, the second heating element 80 has a smaller wire diameter than the first heating element 70, has a smaller surface area than the first heating element 70, and has a larger heat generation amount. The wire diameter of the first heating element 70 is, for example, 0.3 to 1.0 mm, and the wire diameter of the second heating element 80 is, for example, 0.1 to 0.8 mm. Preferably, the diameter of the second heating element 80 is 0.2 to 0.8 times, more preferably 0.4 to 0.6 times that of the first heating element 70. The second heating element 80 is preferably made of rhenium (Re). When the second heating element 80 is formed of rhenium (Re), the diameter of the second heating element 80 is not necessarily limited. Need not be smaller than the wire diameter of the first heating element 70.

  The distance between the heating elements 70 and 80 and the cylindrical base 30 is set to efficiently transport the deposition species (decomposition component) generated by the decomposition of the raw material gas toward the cylindrical base 30 or the heating 70 and 80. In order to prevent damage to the cylindrical substrate 30 and the deposited film due to radiant heat from, for example, 3 to 100 mm, preferably 5 to 50 mm, more preferably 10 to 40 mm.

  On the other hand, the electrodes 71, 72, 81, 82 are for supplying external power to the heating elements 70, 80, and are electrically connected to the first or second heating elements 70, 80. . The electrodes 71, 72, 81, 82 may be directly connected to the first or second heating element 70, 80, or may be connected via a crimp terminal. Such electrodes 71, 72, 81, 82 are formed of a metal material such as Al, Cu, Au, or Ag.

  Next, the case where the electrophotographic photosensitive member 3 shown in FIG. 3 is produced using the heating element CVD apparatus 1 will be described as an example. The electrophotographic photosensitive member 3 shown in FIG. 3 is obtained by sequentially laminating a carrier injection blocking layer 31, a photoconductive layer 32, and a surface protective layer 33 on the surface of a cylindrical substrate 30.

  When a target film is formed on the cylindrical substrate 30 using the plasma CVD apparatus 1, first, the cylindrical substrate 30 is set on the substrate support 4.

  As the cylindrical substrate 30, a conductive or insulating material is used, or a material in which a conductive layer is 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.

  When the cylindrical substrate 30 is supported on the substrate support 4, the carrier injection blocking layer 31 and the photoconductive layer 32 are formed as an a-Si layer on the cylindrical substrate 30. In this process, the gas in the film forming chamber 20 is exhausted from the gas exhaust port 21 using a vacuum pump and the film forming chamber 20 is kept in a vacuum state, and the first source gas is formed using the gas supply means 6. The first heating element 70 is heated while being supplied to the film chamber 20.

As the first source gas, for example, a mixed gas in which SiH ₄ as a Si source gas and H ₂ as a dilution gas are mixed at a desired ratio is used. Further, the mixing ratio of SiH ₄ and H ₂ is adjusted using the pressure reducing valves 63A, 63B, 63C, 63D and the mass flow controllers 64A, 64B, 64C, 64D. The mixed gas is mixed with a valence electron control gas, a band gap adjusting gas, or the like as necessary. On the other hand, the heat generation temperature of the first heating element 70 is set in a range of 1600 ° C. to 1800 ° C., for example.

  Thus, by supplying the first source gas to the film forming chamber 20 and causing the first heating element 70 to generate heat, the first source gas is brought into contact with the first heating element 70 and heated and decomposed. The decomposition components generated at this time are deposited on the surface of the cylindrical substrate 30 to form an a-Si layer. Then, by appropriately changing the composition of the first source gas, the carrier injection blocking layer 31 and the a-Si layer as the photoconductive layer 32 are sequentially formed on the surface of the cylindrical substrate 30.

  When an a-Si layer is formed on the surface of the cylindrical substrate 30 using the carrier injection blocking layer 31 and the photoconductive layer 32, the surface protective layer 33 is then formed as an a-SiC layer. In this step, first, supply of the first source gas and the like is temporarily interrupted, and preparation for supplying the second source gas to the film forming chamber 20 is performed. Next, in the state where the gas in the film forming chamber 20 is exhausted from the gas exhaust port 21 using a vacuum pump and the vacuum state of the film forming chamber 20 is maintained, the second source gas is supplied into the film forming chamber using the gas supply unit 6. 20 and the second heating element 80 generates heat.

As the second source gas, for example, a mixed gas in which SiH ₄ as a Si source, C ₂ H ₂ as a C source, and H ₂ as a dilution gas are mixed in a desired ratio is used. Further, the mixing ratio of SiH ₄ , C ₂ H ₂ and H ₂ is adjusted using the pressure reducing valves 63A, 63B, 63C, 63D and the mass flow controllers 64A, 64B, 64C, 64D, as with the first source gas. The mixed gas is mixed with a valence electron control gas, a band gap adjusting gas, or the like as necessary. On the other hand, the heat generation temperature of the second heating element 80 is set in a range of 2000 ° C. to 2300 ° C. when the second heating element 80 is formed of tantalum (Ta) or tungsten (W), for example. In the case of using the two heating elements 80 made of rhenium (Re), the temperature is set in the range of 1800 ° C. to 2000 ° C.

  Thus, by supplying the second source gas to the film forming chamber 20 and causing the second heating element 80 to generate heat, the second source gas is brought into contact with the second heating element 80 and heated and decomposed. The decomposition component generated at this time is deposited on the surface of the cylindrical substrate 30, and an a-Si layer as the surface protective layer 33 is formed on the surface of the cylindrical substrate 30.

  According to the heating element CVD apparatus 1 described above, the wire diameter of the second heating element 80 is made smaller than the wire diameter of the first heating element 70. Therefore, even if the heating temperature of the second heating element 80 is kept high, the surface area of the second heating element 80 is made smaller than that of the first heating element, so that the amount of heat generated in the second heating element 80 can be suppressed. it can. Therefore, even when film formation is performed using the second source gas that is decomposed at a high temperature, the amount of radiant heat in the second heating element 80 can be reduced while maintaining the heating temperature of the second heating element 80 high. . As a result, it is possible to suppress the temperature of the cylindrical substrate 30 from becoming too high during film formation using the second source gas. Thereby, the cooling effect of the cylindrical substrate 30 by the temperature adjusting means 40 can be sufficiently obtained as in the case where the film is formed using the first source gas that is decomposed at a lower temperature than the second source gas. Thus, the temperature control of the cylindrical substrate 30 during film formation can be performed easily and reliably.

  In addition, when a second heating element formed of a Re-based material is used, the second heating element is formed in comparison with the case where the second heating element 80 formed of tungsten (W), tantalum (Ta), or the like is used. The decomposition temperature of the second source gas during film formation can be set low. For example, when the second source gas containing a carbon compound is used, the second heating element 80 of tungsten (W) or tantalum (Ta) needs to have a decomposition temperature of the carbon compound of 2000 ° C. or higher. On the other hand, in the second heating element 80 of the Re-based material, the decomposition temperature of the carbon compound can be set to about 1800 ° C. As described above, when the Re-based material is used as the second heating element 80, the temperature of the second heating element 80 can be made closer to the temperature of the first heating element 70. The difference in the amount of heat radiation between the film formation (for example, when the a-Si layer is formed) and the film formation by the second heating element 80 (for example, when the a-SiC layer is formed) is reduced. Even during film formation, the temperature of the cylindrical substrate 30 does not become so high. As a result, since the cooling effect of the cylindrical substrate 30 by the temperature adjusting means 40 can be sufficiently obtained even during the film formation by the second heating element 80, the temperature control of the cylindrical substrate 30 during the film formation is simple and easy. You will be able to do it reliably.

  Further, by separately providing a first heating element 70 for the first source gas and a second heating element 80 for the second source gas, the first source gas is decomposed to deposit a film (for example, a-Si). When the second raw material gas is decomposed to form a deposited film (for example, an a-SiC layer) after forming the first layer, the first adhering to the surface of the first heating element 70 when the first raw material gas is decomposed. The decomposition component of the source gas is taken into the deposition film (for example, a-SiC layer) by the second source gas when the second source gas is decomposed to form the deposition film (for example, a-SiC layer). Can be suppressed. Therefore, the characteristics of the deposited film (for example, the a-Si layer) by the second source gas are not impaired by the decomposition component of the first source gas, and therefore, a plurality of deposited films (for example, the a-Si layer having the desired characteristics) And a-SiC layer)) can be suitably obtained.

 The present invention can be variously modified and improved without departing from the gist thereof. For example, in the above-described embodiment, the case where two heat generating means 7 and 8 (heat generating elements 70 and 80) are provided has been described as an example, but three or more heat generating means (heat generating elements) may be provided, Three or more heat generating means (heating elements) may be divided into two or more groups. In this case, the number of heat generating means (heat generating elements) in each group may be one or plural.

  In the above-described embodiment, the case where the a-Si layer and the a-SiC layer are formed on the surface of the same cylindrical substrate 30 has been described as an example. However, the present invention has different compositions on the surfaces of different substrates. The present invention can also be applied when forming a deposited film. For example, after forming an a-Si layer on the surface of the substrate using the heat of the first heating element, the substrate is replaced with another substrate, and the surface of another substrate is replaced with the heat of the second heating element. Alternatively, an a-SiC layer may be formed.

(First embodiment)
In this example, when the electrophotographic photosensitive member 3 shown in FIG. 3 was formed, the influence of the wire diameter of the second heating element 80 on the saturated substrate temperature during the formation of the surface protective layer 33 was examined.

  As the cylindrical substrate 30, an Al substrate with a mirror-finished surface and a diameter of 30 mm and a length of 254 mm was used. One cylindrical substrate 30 was set in the film forming chamber 20.

  As the first heating element 70, a tantalum wire having a wire diameter of 0.5 mm and a purity of 99.9% was used. On the other hand, as the second heating element 80, a tantalum wire having a purity of 99.9% and having a wire diameter of 0.2 mm, 0.3 mm, 0.4 mm, or 0.5 mm was used.

Note that after the cylindrical substrate 30 is set in the film forming chamber 20 of the heating element CVD apparatus 1, a vacuum in the film forming chamber 20 is maintained while the cylindrical substrate 30 is held at 250 ° C. using a cartridge heater before film formation. The degree is set to 1 × 10 ⁻² Pa, and then a carrier injection blocking layer 31, a photoconductive layer 32, and a surface protective layer 33 are sequentially stacked on the surface of the cylindrical substrate 30 under the conditions shown in Table 1 below. Was done. The surface temperature of the cylindrical substrate 30 was measured using a thermocouple. Regarding the measurement result of the surface temperature of the cylindrical substrate 30, the change with time is shown in FIG. 4, and the saturation temperature is shown in Table 1 (Table 2) together with the film forming conditions.

  From the results shown in FIG. 4 and Table 2, when the wire diameter of the second heating element 80 is 0.5 mm (the same diameter as the first heating element 70), the surface protective layer is formed using the second source gas. When the (a-SiC layer) was formed, the temperature of the cylindrical substrate 30 became 450 ° C. or higher. For this reason, the cylindrical substrate 30 made of AL might be melted, so that the film formation was stopped halfway.

  On the other hand, when the wire diameter of the second heating element 80 is smaller than 0.4 mm (0.8 times that of the first heating element 70), the surface protective layer (a-SiC layer) is formed using the second source gas. The temperature of the cylindrical substrate 30 when forming a) became 390 ° C. or less. Therefore, when the wire diameter of the second heating element 80 is smaller than 0.4 mm (0.8 times that of the first heating element 70), the temperature of the cylindrical substrate 30 can be controlled within a desired temperature range. I understand. In particular, when the wire diameter of the second heating element 80 is smaller than 0.3 mm (0.6 times that of the first heating element 70), the temperature of the cylindrical substrate 30 is 330 ° C. or less, and the target substrate temperature Fit in range. This is considered to be because by reducing the wire diameter of the second heating element 80, the surface area of the second heating element 80 is reduced, and heat radiation to the cylindrical substrate 30 is suppressed.

(Second embodiment)
In this example, the influence of the material of the second heating element 80 on the saturated substrate temperature during the formation of the surface protective layer 33 was examined.

  In this example, the second heating element 80 was implemented except that a tantalum wire with a purity of 99.9% with a wire diameter of 0.5 mm or a rhenium wire with a purity of 99.9% with a wire diameter of 0.5 mm was used. In the same manner as in Example 1, the surface temperature of the cylindrical substrate 30 was measured. Regarding the measurement results of the surface temperature of the cylindrical substrate 30, the change with time is shown in FIG. 5 and the saturation temperature is shown in Table 3 below.

  From the results of FIG. 5 and Table 3, even when the wire diameter of the second heating element 80 is 0.5 mm, which is the same as the wire diameter of the second heating element 70, the surface protective layer 33 can be obtained by setting the material to Re. The surface temperature (carbide decomposition temperature) of the cylindrical substrate 30 when forming the film was approximately the same as that during the film formation of the carrier injection blocking layer 31 and the photoconductive layer 32. Therefore, when Re is adopted as the material of the second heating element 80, it can be seen that the temperature of the cylindrical substrate 30 can be controlled within a desired temperature range. This is considered to be because when Re is adopted as the material of the second heating element 80, the temperature of the cylindrical substrate 30 is suppressed because thermal radiation is suppressed.

It is a longitudinal cross-sectional view which shows an example of the heat generating body CVD apparatus which concerns on this invention. It is a cross-sectional view of the heating element CVD apparatus shown in FIG. FIG. 3 is a longitudinal sectional view of an electrophotographic photosensitive member formed in the heating element CVD apparatus of FIGS. 1 and 2 and a sectional view showing an enlarged main part thereof. 3 is a graph showing the relationship between the substrate temperature measured in Example 1 and the film formation time. 6 is a graph showing the relationship between the substrate temperature measured in Example 2 and the film formation time. It is a longitudinal cross-sectional view for demonstrating the conventional heat generating body CVD apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Heat generating body CVD apparatus 20 Film-forming chamber 30 Cylindrical base | substrate 70 1st heat generating body 80 2nd heat generating body

Claims (4)

A film forming chamber for containing a substrate; a first heating element disposed in the film forming chamber so as to be in contact with the first source gas; and a first heater disposed in the film forming chamber so as to be in contact with the second source gas. comprising a second heating element, a, and, the deposited before SL on the substrate a cracking component when decomposing the first raw material gas by the heat from the first shot heat body, then, from the second heating element In the heating element CVD apparatus for forming a film by depositing a decomposition component when the second source gas is decomposed by the heat of
The second source gas has a composition different from that of the first source gas , and is decomposed at a higher temperature than the first source gas.
The second heating element is configured such that the heating temperature is higher than the heating temperature of the first heating element, and the wire diameter is smaller than that of the first heating element. Heating element CVD device.   The heating element CVD apparatus according to claim 1, wherein a wire diameter of the second heating element is 0.2 to 0.8 times a wire diameter of the first heating element. Wherein the first raw material gas is composed of a silicon-based compound, the second raw material gas is composed of a silicon compound and a carbon-based compound, the heating element CVD system according to claim 1 or 2. A film forming chamber for containing a substrate; a first heating element disposed in the film forming chamber so as to be in contact with the first source gas; and a first heater disposed in the film forming chamber so as to be in contact with the second source gas. comprising a second heating element, a, and, the deposited before SL on the substrate a cracking component when decomposing the first raw material gas by the heat from the first shot heat body, then, from the second heating element In the heating element CVD apparatus for forming a film by depositing a decomposition component when the second source gas is decomposed by the heat of
The first source gas is composed of a silicon-based compound, the second source gas is composed of a silicon-based compound and a carbon-based compound, and the second source gas is decomposed at a higher temperature than the first source gas. Is,
The first heating element includes tantalum (Ta), tungsten (W), platinum (Pt), palladium (Pd), molybdenum (Mo), titanium (Ti), niobium (Nb), cobalt (Co), nickel (Ni ), Chromium (Cr), and manganese (Mn), and at least one selected from the group consisting of manganese (Mn) is formed of a material whose main component or alloy component,
The heating element CVD apparatus, wherein the second heating element is made of a material having rhenium (Re) as a main component or an alloy component.

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