JP2005179768A - Heating element cvd system, and film deposition method by heating element cvd method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a film deposition method by a heating element CVD (chemical vapor deposition) method of high performance where, even in the case a plurality of layers are film-deposited, the formation of the layers having desired properties can be performed. <P>SOLUTION: In the heating element CVD system provided with: a vacuum vessel 1 storing a substrate 2; a gas feeding means 7 feeding a gaseous starting material into the vacuum vessel 1; and a plurality of heating elements 4 arranged so as to be contacted with a gaseous starting material fed from the gas feeding means 7, and wherein, the gaseous starting material from the gas feeding means is cracked with heat generated by the heating elements 4, and the cracked gaseous starting material components are deposited on the substrate 2 to perform film deposition, the plurality of heating elements 4 are at least composed of the first heating element 4a for thermally cracking the first gaseous starting material fed from the gas feeding means 7 and the second heating element 4b for thermally cracking the second gaseous starting material fed from the gas feeding means 7. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a heating element CVD apparatus and a film forming method using a heating element CVD method in which a source gas is decomposed by heat generated by a heating element to deposit a decomposition component to form a film.

  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 them, the heating element CVD method is a film forming method in which the source gas is decomposed by the heat of the heating element and formed on the substrate, and the temperature of the substrate during film formation can be lowered as compared with the thermal CVD method. Therefore, the range of use of the substrate material can be widened, and the film on the substrate is not damaged by plasma unlike the plasma CVD method, so that a high-quality film can be obtained on various substrates. It is attracting attention as a possible film forming method.

  For example, as shown in FIG. 15, the conventional heating element CVD apparatus includes a vacuum vessel 21 that houses a base 22 and a base holding means 23, a gas supply means 27 that supplies a source gas into the vacuum vessel 21, and the gas A structure having a heating element 24 disposed in the vacuum vessel 21 so as to be in contact with the source gas supplied from the supply means 27 is known.

  For example, when an a-Si layer and an a-SiC layer are sequentially laminated on a substrate using this heating element CVD apparatus, the film is formed through the following steps.

(1) Supplying the first source gas for forming the a-Si layer into the vacuum container 21 using the gas supply means 27 in a state where the vacuum container 21 is kept in a vacuum state using the vacuum pump. In addition, the heating element 24 is heated at 1200 ° C. to 2500 ° C. while the supplied first source gas is brought into contact with the heating element 24, the first source gas is decomposed by the heat, and Si generated by the decomposition is changed. By depositing on the substrate 22, an a-Si layer is deposited on the substrate 22. For example, SiH ₄ is used as the first source gas, and H ₂ is used as the dilution gas. Further, the mixing ratio of SiH ₄ and H ₂ is adjusted using a pressure reducing valve of a gas tank, a mass flow controller, or the like.

(2) Next, supply of the first source gas is temporarily interrupted, and preparation for supplying the second source gas for forming the a-SiC layer into the vacuum vessel 21 is made. As the second source gas, a gas in which SiH ₄ and C ₂ H ₂ are mixed is preferably used, and H ₂ is used as a dilution gas. The gas mixing ratio is adjusted by using a gas tank pressure reducing valve, a mass flow controller, or the like.

(3) Finally, the above-mentioned second source gas is supplied into the vacuum vessel 21 using the gas supply means 27 while the inside of the vacuum vessel 21 is kept in a vacuum state using a vacuum pump, and the supply The heating element 24 is heated at 1200 ° C. to 2500 ° C. while bringing the generated first source gas into contact with the heating element 24, the second source gas is decomposed by the heat, and SiC generated by the decomposition is converted into an a-Si layer. By depositing on the a-SiC layer.
Japanese Patent No. 3145536

  By the way, in the film-forming method by the above-mentioned heat generating body CVD method, it was common to use the same heat generating body 24 for decomposition | disassembly of 1st raw material gas and decomposition | disassembly of 2nd raw material gas.

  However, when the first source gas is decomposed, the decomposition components of the first source gas often adhere to the surface of the heating element 24. Therefore, when the second source gas is decomposed, the first source gas is decomposed. When the same heating element 24 as the heating element 24 used in the above is used, the decomposition component of the first source gas adhering to the surface of the heating element 24 is taken into the a-SiC layer as the second layer, and as a result. There is a problem that it is difficult to obtain an a-SiC layer having desired characteristics.

  Such a problem is that when the heating temperature of the heating element is higher when the second layer is formed than when the first layer is formed, the surface of the heating element is attached by the heat generated by the heating element 24 when the second layer is formed. Since the kimono is easily taken into the layer, it is particularly likely to occur.

  The present invention has been devised in view of the above problems, and the purpose thereof is a high-performance heating element CVD apparatus capable of forming a layer having desired characteristics even when a plurality of layers are formed, Another object of the present invention is to provide a film forming method using a heating element CVD method.

  The heating element CVD apparatus of the present invention is disposed so as to contact a vacuum vessel that accommodates a substrate, a gas supply unit that supplies a source gas into the vacuum vessel, and a source gas supplied from the gas supply unit. A heating element CVD comprising: a plurality of heating elements, wherein the source gas from the gas supply means is decomposed by the heat generated by the heating element, and the decomposed source gas components are deposited on a substrate to form a film. In the apparatus, the plurality of heating elements thermally decomposes a first heating element for thermally decomposing the first source gas supplied from the gas supply means and a second source gas supplied from the gas supply means. And at least a second heating element.

  The heating element CVD apparatus of the present invention is characterized in that, in the above-described heating element CVD apparatus, either the first source gas or the second source gas is supplied into the vacuum vessel one by one.

  Furthermore, the heating element CVD apparatus of the present invention is characterized in that, in the above-described heating element CVD apparatus, the second heating element has a higher heating temperature than the first heating element.

  Furthermore, the heating element CVD apparatus of the present invention is the heating element CVD apparatus described above, wherein the first heating element and the second heating element are provided adjacent to each other, and the first heating element and the second heating element are disposed between the first heating element and the second heating element. A shielding member is interposed so that the surfaces of the heating elements do not directly face each other.

  The heating element CVD apparatus of the present invention is characterized in that the shielding member is rotated for film formation.

  Furthermore, the heating element CVD apparatus of the present invention is characterized in that the rotating shaft of the shielding member is substantially parallel to the longitudinal direction of the shielding member.

  On the other hand, in the film forming method by the heating element CVD method of the present invention, the first source gas is supplied into the vacuum container that accommodates the base body, the first heating element, and the second heating element, and the first source gas is supplied to the first source gas. (1) a first step of decomposing by heat generated by a heating element and depositing the decomposed component on a substrate to form a first layer; and a second source gas in the vacuum vessel in place of the first source gas And a second step of decomposing the second source gas by heat generated by the second heating element and depositing the decomposition component to form a second layer.

  Further, the film forming method by the heating element CVD method of the present invention is characterized in that, in the above-described film forming method, the second heating element has a higher heat generation temperature than the first heating element.

  Furthermore, the film forming method by the heating element CVD method of the present invention is the above-described film forming method, wherein the second heating element is disposed between the interruption of the supply of the first source gas and the start of the supply of the second source gas. Heat generation is performed at a temperature equal to or higher than the vapor pressure temperature of the constituent material of the first layer and equal to or lower than the vapor pressure temperature of the constituent material of the heating element.

  Still further, the film forming method by the heating element CVD method of the present invention is the above-described film forming method, wherein the first heating element and the second heating element are provided adjacent to each other, and the first heating element and the second heating element are provided. A shielding member is interposed between the bodies so that the surfaces of the heating elements do not directly face each other.

  Furthermore, the film forming method by the heating element CVD method of the present invention is characterized in that, in the film forming method described above, the first layer is mainly composed of an a-Si based material and the second layer is composed of an a-SiC based material. And

  Further, the film forming method by the heating element CVD method of the present invention is characterized in that the shielding member rotates during film formation.

  Furthermore, the film forming method by the heating element CVD method of the present invention is characterized in that the rotating shaft of the shielding member is substantially parallel to the longitudinal direction of the shielding member.

  According to the present invention, when the first source gas is decomposed to form the first layer and then the second source gas is decomposed to form the second layer, the heating element for decomposing the source gas is provided. Since a plurality of heating elements are provided, the heating element includes a first heating element for thermally decomposing the first source gas and a second element for thermally decomposing a second source gas of a different type from the first source gas. It can be divided into two heating elements. Therefore, the decomposition component of the first source gas adhering to the surface of the first heating element when the first source gas is decomposed is taken into the layer formed by decomposing the second source gas when the second source gas is decomposed. It is easy to obtain a layer having desired characteristics. The present invention can be applied not only when the first layer and the second layer are sequentially laminated on the same substrate, but also when the films are formed on different substrates.

  Further, according to the present invention, after the supply of the first source gas is interrupted and before the supply of the second source gas is started, the second heating element has a vapor pressure temperature equal to or higher than the vapor pressure temperature of the constituent material of the first layer. When the decomposition component of the first source gas adheres to the surface of the second heating element, the decomposition component of the first source gas is converted into the second by the heat of the second heating element. It can be removed better than the surface of the heating element. Therefore, when the second source gas is decomposed, the decomposition component of the first source gas is further suppressed from being taken into the second layer.

  Furthermore, according to the present invention, the first heating element and the second heating element are provided so as to be adjacent to each other, and the surfaces of the heating elements are not directly opposed to each other between the first heating element and the second heating element. Since the shielding member is interposed, the component decomposed by the heat of the first heating element is prevented from adhering to the surface of the second heating element when the first source gas is decomposed. In addition, it is possible to further suppress the decomposition component of the first source gas from being taken into the second layer when the second source gas is decomposed.

  Still further, according to the present invention, by rotating the shielding member interposed between the first heating element and the second heating element during film formation, the decomposition component of the gas shielded by the shielding member is prevented. Therefore, the adhesion between the shielding member and the deposit can be improved. Therefore, the deposit of the decomposition component of the gas shielded by the shielding member is suppressed from peeling off from the shielding member, and the deposit is favorably prevented from adhering to the substrate during film formation.

  Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

(First embodiment)
FIG. 1 is a side view of the heating element CVD apparatus according to the first embodiment, FIG. 2 is a top view of the heating element CVD apparatus of FIG. 1, and the heating element CVD apparatus shown in FIG. 2, a gas supply means 7 for supplying a raw material gas into the vacuum container 1, a heating element 4 disposed so as to contact the raw material gas supplied from the gas supply means 7, It has the structure provided with.

  The vacuum vessel 1 is formed in a hollow state so as to accommodate the base 2, the base support 3, the heating element 4, and the gas supply means 7 therein, and a part of the container is provided so that the base 2 can be taken in and out. For example, the upper lid is formed to be openable and closable. The vacuum vessel 1 also has a gas exhaust port 6 that is used when exhausting the source gas introduced by the gas supply means 7.

  The base 2 accommodated in the vacuum vessel 1 can be of various shapes such as cylindrical or flat (cylindrical in FIG. 1), and when a cylindrical base is used, It is set in the vacuum vessel 1 by inserting a cylindrical substrate support. When a flat substrate is used, the plurality of substrates 2 are set in the vacuum container 1 by being arranged on the substrate support so as to be substantially cylindrical or polyhedral.

  As the material of the substrate 2, a conductive or insulating material or a material having a conductive layer formed on the surface of an insulating substrate is used. 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. Insulating substrates include borosilicate glass, soda glass, pyrex glass and other inorganic materials such as ceramics, quartz, sapphire, or fluororesin, polycarbonate, polyethylene terephthalate, polyester, polyethylene, polypropylene, polystyrene, polyamide, vinylon. And synthetic resin insulators such as epoxy and mylar. When a conductive layer is formed on an insulating substrate, the material of the conductive layer is ITO (indium, tin, oxide), tin oxide, lead oxide, indium oxide, copper iodide, Al, Ni, gold (Au) Such a conductive layer may be a conventionally known thin film forming technique such as vacuum deposition, active reaction deposition, ion plating, RF sputtering, DC sputtering, RF magnetron sputtering, DC magnetron sputtering, It is formed by a thermal CVD method, a plasma CVD method, a spray method, a coating method, a dipping method, or the like. In addition, when forming the base | substrate 2 in a cylindrical shape with Al, it manufactures by employ | adopting a conventionally well-known extrusion method.

  The substrate support 3 for supporting the substrate 2 is formed in a cylindrical shape when supporting a cylindrical substrate, and is formed in a flat plate shape or a polygonal column shape when supporting a flat substrate. (Cylindrical in FIG. 1). The substrate support 3 is preferably rotated together with the substrate 2 around the central axis by power of a rotary motor or the like during film formation, whereby the decomposition component of the source gas decomposed by the heating element 4 is transferred over the entire surface of the substrate. A substantially uniform film thickness distribution can be obtained. The rotation speed of the substrate support 3 is preferably 1 rpm to 10 rpm. The substrate support 3 is rotated using the power of a rotating means 18 such as a rotary motor provided at the end thereof.

  The substrate support 3 has heating means, cooling means, and temperature detection means inside thereof, and the temperature detection means detects the temperature of the substrate support 3 and monitors the detected temperature while monitoring the temperature. The substrate temperature is maintained at a desired temperature by controlling the heating means and the cooling means using a temperature controller that does not. Note that the substrate temperature during film formation is controlled to a constant temperature of 100 to 500 ° C., preferably 200 to 350 ° C. when an a-Si or a-SiC material is deposited. As heating means, electrical devices such as nichrome wires, sheathed heaters, cartridge heaters, and heat media such as oil are used. As cooling means, cooling is performed using gas such as air or nitrogen gas, water, oil, or the like. It is preferable that a medium is used and these are made to flow so as to circulate inside the substrate support 3. As the temperature detecting means, a thermistor or a thermocouple is used.

  On the other hand, a plurality of heating elements 4 arranged substantially parallel to the above-described base 2 are disposed inside the vacuum vessel 1, and these heating elements 4 are in contact with the source gas supplied from the gas supply means 7. It is arranged to do.

  The heating element 4 includes a first heating element 4a for thermally decomposing the first source gas supplied from the gas supply means 7, and a second heating element for decomposing a second source gas different from the first source gas. 4b.

  Each of the first heating element 4a and the second heating element 4b is made of a resistance material, and when power is supplied through the electrodes 5 connected to both ends, Joule heating is generated and the corresponding source gas is decomposed. It becomes temperature required for this (for example, 1200 degreeC-2500 degreeC).

  As described above, when a plurality of types of source gases (first source gas and second source gas) are supplied into the vacuum vessel by the gas supply means 7 and thermally decomposed for each source gas, the first source gas is heated. Since the heating element 4 to be decomposed and the heating element 4 to thermally decompose the second source gas are separated, the first source gas is decomposed on the surface of the first heating element when forming the first layer. The decomposition component of the attached first source gas is satisfactorily suppressed from being taken into the second layer when the second source gas is decomposed to form the second layer. Therefore, it becomes easy to obtain the second layer having desired characteristics.

  As the resistance material of the heating element 4, a catalytic reaction or a thermal decomposition reaction with the raw material gas occurs, the reaction product is used as a deposition species, and the heating element itself is mixed in a film deposited by sublimation or evaporation. For example, tungsten (W), platinum (Pt), palladium (Pd), molybdenum (Mo), Ti, niobium (Nb), tantalum (Ta), cobalt (Co), Ni, Cr, Mn And alloys thereof are preferably used. The resistance material of the heating element 4 preferably has a relatively high melting point. For example, a resistance material having a melting point of 2600 ° C. to 3400 ° C. is preferable.

  The resistance material of the heating element 4 may be the same between the first heating element 4a and the second heating element 4b or may be different, but the first heating element 4a and the second heating element 4b are different. When the heat generation temperatures are different, it is preferable that the heat generating element having a high heat generation temperature is formed of a resistance material having a higher melting point than the heat generation element having a low heat generation temperature.

  Examples of the shape of the heating element 4 include a linear shape as in the present embodiment, or a cylindrical shape having a diameter larger than that of the cylindrical substrate 2 as shown in FIGS. 3 and 4. In the case of forming in a linear shape, it is conceivable to form a single wire, filament, ribbon, or the like made of the above-described electrical resistance material, or to bundle a plurality of wires. Also, when forming a cylindrical shape, the wire, filament, ribbon, etc. made of the above-described resistance material are combined in a lattice shape or a mesh shape to form a cylindrical shape, or a cylindrical plate with a circular shape, a triangular shape, a square shape, a rectangular shape, a rhombus shape, It can be considered that a large number of hexagonal ventilation holes are provided by punching or electroforming.

  The heating element 4 is disposed in order to efficiently transport the deposition species (decomposition component) generated by the heat generation of the heating element 4 toward the substrate, or to the substrate or film by the radiant heat from the heating element 4. In order to prevent damage, the base 2 is set at a position 3 to 100 mm, preferably 5 to 50 mm, more preferably 10 to 40 mm apart. Further, when the heating element 4 has a cylindrical shape, the base 2 and the heating element 4 are arranged so that their central axes substantially coincide with each other so as to have a substantially equal distance.

  Electrodes 5 are connected to both ends of the heating element 4. The electrode 5 functions as a power supply wiring for supplying power from the outside to the heating element 4 and is made of a metal material such as Al, Cu, Au, or Ag. As for the electrical connection between the electrode 5 and the heating element 4, for example, it is conceivable to connect the two via a crimp terminal.

  On the other hand, the gas supply means 7 for supplying the raw material gas into the vacuum vessel 1 is arranged so that the supplied first raw material gas or the second raw material gas contacts the surface of the heating element 4. It arrange | positions so that the body 4 may be located between the base | substrate 2 and the gas supply means 7. FIG.

The gas supply means 7 has a structure in which a large number of gas blowing holes 8 are formed in a casing having a hollow structure, and a part of the gas supply means 7 is connected to a plurality of gas tanks via a gas introduction pipe (not shown). Various gases such as SiH ₄ , H ₂ , and C ₂ H ₂ are stored in these gas tanks, and the gas components introduced into the gas supply means 7 by using a pressure reducing valve or a mass flow controller of these gas tanks are stored. Adjusted. Then, the source gas introduced into the gas supply means 7 is supplied into the vacuum container 1 through the gas blowing holes 8, and the supplied source gas contacts the heating element 4. In order to facilitate the contact of the source gas with the heating element 4, the gas blowing holes 8 are preferably provided on the surface of the casing on the heating element side. As the shape of the gas blowing hole 8, various shapes such as a circle, a triangle, a square, a rectangle, a rhombus, a hexagon, and a slit shape can be considered.

  The casing of the gas supply means 7 may have various shapes such as a cylindrical shape or a linear shape (long shape), and may be separated from the vacuum vessel 1 or may be at least partially integrated. Since the number of parts of the apparatus can be reduced, there is an advantage in that the configuration of the heating element CVD apparatus can be simplified. When the casing of the gas supply means 7 and the vacuum container 1 are separated, an inner peripheral surface is provided on the inner wall of the vacuum container 1 and the inner wall, and the inner peripheral surface and the inner wall constitute the casing. Alternatively, the housing of the gas supply means 7 may be fitted to the inner wall of the vacuum vessel 1, and the gas supply means 7 of FIG. 4 can be considered as the former example. When the gas supply means 7 is linear (elongate), the gas supply means 7 in FIG. 1 is considered as an example. In this case, in order to efficiently bring the source gas into contact with the heating element 4, the heating element 4 is preferably linear.

The source gas supplied from such a gas supply means 7 is a compound composed of Si and H or a compound other than silicon and hydrogen when the film formation target is an a-Si film used for an electrophotographic photoreceptor. A compound comprising a halogen element, for example, SiH ₄ , Si ₂ H ₆ , Si ₃ H ₈ , SiF ₄ , SiCl ₄ , SiCl ₂ H _2, etc. is used, and these source gases are the first source material in the present embodiment. It becomes gas.

As the diluent gas supplied together with the first source _{gas, H 2, N 2, He} , Ar, Ne, Xe or the like is used. The valence electron control gas (gas for controlling the number of valence electrons in the film) supplied together with the source gas includes a compound containing group B elements (B, Al, Ga, etc.) of the periodic table of elements as P-type impurities. For example, B ₂ H ₆ . B (CH ₃ ) ₃ , Al (CH ₃ ) ₃ , Al (C ₂ H ₅ ) ₃ , Ga (CH ₃ ) _{3 and the} like are used. As the N-type impurity, a compound containing a group V element (P, As, Sb, etc.) of the periodic table of elements such as PH ₃ , P ₂ H ₄ , AsH ₃ , SbH ₃ or the like is used. As the band gap adjusting gas, a compound containing C, N, or O, which is an element that expands the band gap, 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, CO _{2 and the} like, and compounds containing Ge and Sn, which are elements that narrow the band gap, such as GeH ₄ , SnH ₄ , Sn (CH ₃ ) _{3, and the} like are used.

When the film formation target is an a-SiC film used for an electrophotographic photoreceptor, the raw material gas is CH ₄ , C ₂ in addition to the same gas as that used to form the a-Si film. A compound containing C, such as H ₂ , C ₃ H ₈ , CO, CO ₂ , is used, and the source gas containing these compounds is the second source gas in the present embodiment.

As the dilution gas supplied together with the second source gas, the same gas as that of the a-Si film is used. As the band gap adjusting gas, a compound containing C, N, or O, which is an element that expands the band gap, 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, CO ₂ or the like is used.

Note that the flow rates of the source gas, the valence control gas, the band gap adjusting gas, and the mixing ratio of these gases are adjusted to desired values by using a pressure reducing valve, a mass flow controller, or the like. The gas pressure during film formation is preferably 0.1 to 300 Pa in order to efficiently decompose the supplied source gas by the heat of the heating element and to suppress the secondary reaction between the reaction products. Is set to 2-6 Pa. In order to obtain a high-quality film, prior to the start of film formation, the inside of the vacuum container 1 in which the substrate 2 is set is evacuated to a high vacuum of about 1 × 10 ⁻² Pa. It is preferable to remove moisture and residual gas.

  Thus, the heating element CVD apparatus described above causes the heating element 4 to generate heat while bringing the source gas supplied from the gas supply means 7 into the vacuum vessel 1 into contact with the heating element 4, and decomposes the source gas by the heat, It functions as a heating element CVD apparatus by forming a film by depositing the decomposed source gas component on the substrate 2.

  Next, the film forming method by the heating element CVD method in the first embodiment is applied to the a-Si layer as the first layer and the a-SiC as the second layer on the cylindrical substrate using the heating element CVD apparatus described above. A case where layers are sequentially stacked will be described as an example.

  Step (1): A first raw material for forming an a-Si layer in a state where the gas in the vacuum vessel 1 is exhausted from the gas exhaust port 6 using a vacuum pump and the vacuum vessel 1 is kept in a vacuum state. Gas, dilution gas, etc. are supplied into the vacuum vessel 1 using the gas supply means 7, and the first heating element 4a is heated at a high temperature while the supplied first source gas is brought into contact with the first heating element 4a. Then, the first source gas is decomposed by the heat, and Si generated by the decomposition is deposited on the substrate 2, thereby depositing an a-Si layer on the substrate 2.

For example, SiH ₄ is used as the first source gas, and H ₂ is used as the dilution gas. Moreover, the mixing ratio of SiH ₄ and H ₂ is adjusted using a pressure reducing valve of a gas tank, a mass flow controller, or the like as described above. Further, a valence electron control gas, a band gap adjusting gas, or the like may be mixed.

  Further, the heating temperature of the first heating element 4a is preferably set in the range of 1200 ° C to 2500 ° C.

  Step (2): Next, supply of the first source gas and the like is temporarily interrupted, and preparation for supplying the second source gas, dilution gas, and the like for forming the a-SiC layer into the vacuum vessel 1 is made. .

As the second source gas, a mixture of SiH ₄ and C ₂ H ₂ at a predetermined mixing ratio is used. The H ₂ is used as a diluent gas. These may be mixed with a predetermined amount of the above-described valence electron control gas or band gap adjusting gas. Further, the gas mixing ratio is adjusted using a pressure reducing valve of a gas tank, a mass flow controller, or the like in the same manner as the first source gas.

  Step (3): Finally, the above-mentioned second source gas, dilution gas, and the like are introduced into the vacuum container 1 using the gas supply means 7 while the vacuum container 1 is kept in a vacuum state using a vacuum pump. While supplying, the 2nd heating element 4b is heated, making the supplied 2nd source gas contact the 2nd heating element 4b, the 2nd source gas is decomposed by the heat, and SiC which is the decomposition component is changed to a An a-SiC layer is formed by depositing on the -Si layer.

  As described above, the a-Si layer as the first layer and the a-SiC layer as the second layer are formed using different heating elements 4a and 4b, respectively. Even if it adheres to the surface of the first heating element 4a at the time of decomposition, it is not necessary to generate heat at the time of decomposition of the second raw material gas, and the decomposition component of the first raw material gas becomes a at the time of decomposition of the second raw material gas. -Incorporation into the SiC layer is well suppressed. Therefore, it becomes easy to obtain a layer having desired characteristics.

(Second Embodiment)
A second embodiment of the present invention will be described in detail with reference to FIGS. FIG. 5 is a side view of the inside of the heating element CVD apparatus according to the second embodiment of the present invention, and FIG. 6 is a top view of the inside of the heating element CVD apparatus of FIG. Note that components similar to those in the first embodiment are given the same reference numerals.

  This embodiment is different from the first embodiment in that when the surfaces of the first heating element 4a and the second heating element 4b are provided to face each other, as shown in FIGS. In addition, the shielding member 9 is interposed between the second heating elements so that the surfaces of the heating elements do not directly face each other.

  In this case, when the first source gas is decomposed, it is possible to prevent the components decomposed by the heat of the first heating element 4a from adhering to the surface of the second heating element 4b. Further, the decomposition component of the first source gas is further suppressed from being taken into the second layer.

  As the shielding member 9, various materials such as a metal material, an inorganic insulating material, and an organic insulating material can be selected over a wide range as long as the material can withstand radiant heat from the first heating element 4 a and the second heating element 4 b. it can. For example, examples of the metal material include aluminum (Al), stainless steel (SUS), iron (Fe), nickel (Ni), chromium (Cr), manganese (Mn), copper (Cu), titanium (Ti), and the like. It is done. Examples of the inorganic insulating material include glass such as borosilicate glass, soda glass, and Pyrex glass, ceramics such as alumina and zirconia, quartz, and sapphire. Examples of the organic insulating material include fluororesin, polycarbonate, polyethylene terephthalate, polyester, polyethylene, polypropylene, polystyrene, polyamide, vinylon, epoxy, mylar, and the like.

  Various shapes such as a cylindrical shape, a polygonal column shape, and a planar shape are conceivable as the shape of the shielding member 9, but it is preferable to make the shape suitable for the shape of the heating element 4. For example, in the present embodiment, since the heating element 4 is linear, it is preferable that the shielding member 9 is also formed in a linear shape such as a cylindrical shape or a polygonal column shape. For example, as shown in FIGS. When 4 is cylindrical, it is preferable to make the shielding member 9 cylindrical as shown in FIGS. When the shielding member 9 is formed in a cylindrical shape, the shielding member 9 prevents the gas from coming into contact with the second heating element 4b and the base 2 and at the same time, the surfaces of the first heating element 4a and the second heating element 4b In order to prevent this, the shielding member 9 is provided with a vent so as to correspond to the position of the vent provided in the first heating element 4a.

  Further, the shape of the shielding member 9 is slightly larger than the first heating element 4a and the second heating element 4b, that is, wider and longer than the heating element 4 in order to effectively block the heat of the heating element 4. Those are preferred.

  As described above, the shielding member 9 is disposed between the first heating element 4a and the second heating element 4b, but should not interfere with film formation on the substrate 2. It is preferable that the shielding member 9 is not interposed between the heating element 4 and the base 2.

When the shielding member 9 is made of a metal material, the shielding member 9 is manufactured in a predetermined shape by a conventionally known drawing method or extrusion method. In the case of ceramics, a predetermined amount of a sintering aid such as Y ₂ O ₃ is added to and mixed with ceramic raw materials such as alumina and zirconia, and reacted and dissolved by a method such as neutralization coprecipitation or hydrolysis. Thereafter, the obtained raw material is formed into a predetermined shape by extrusion molding, press molding, injection molding, or the like, and then fired at a high temperature.

  The film forming method using the heating element CVD method in the second embodiment is basically the same as the film forming method in the first embodiment.

(Third embodiment)
A third embodiment of the present invention will be described in detail with reference to FIGS. 9 is a side view of the inside of the heating element CVD apparatus according to the third embodiment of the present invention, and FIG. 10 is a top view of the inside of the heating element CVD apparatus of FIG. Note that components similar to those in the second embodiment are given the same reference numerals.

  This embodiment is different from the second embodiment in that the shielding member 9 is rotated around a predetermined rotation axis during film formation.

  For this reason, the decomposition component of the gas shielded by the shielding member 9 is uniformly adhered and deposited on the surface of the shielding member 9, and the adhesion between the shielding member 9 and the deposit can be improved. Therefore, the deposit of the decomposition component of the gas shielded by the shielding member 9 is suppressed from peeling off from the shielding member 9, and the deposit is favorably prevented from adhering to the substrate 2 during film formation. The rotation axis of the shielding member 9 is preferably substantially parallel to the longitudinal direction. Moreover, when the shielding member 9 is linear as shown in FIG. 9, it is preferable that the shielding member 9 is rotated about an axis that is substantially parallel to the longitudinal direction and passes through the shielding member 9. When the shielding member 9 has a cylindrical shape as shown in FIGS. 7 and 8, it is preferable to rotate the shielding member 9 with the central axis of the cylinder as a rotation axis. The rotation speed of the shielding member 9 is preferably set to 1 rpm to 10 rpm.

  The rotation of the shielding member 9 may be performed by separately providing a rotating means 19 such as a rotary motor at its end and using the power of the rotating means 19 (see FIG. 9), or the substrate support 3 The power of the rotating means 18 that rotates the power may be transmitted to the shielding member 9 by a gear or the like.

  Further, the rotation direction of the shielding member 9 may be opposite to or coincident with the rotation direction of the base 2.

  The film forming method by the heating element CVD method in the third embodiment is basically the same as the film forming method in the first embodiment except that the shielding member 9 is rotated during film formation. The film may be rotated continuously or intermittently. Further, the shielding member 9 may be rotated even during film formation.

  Various changes and improvements can be made without departing from the scope of the present invention. For example, in the first to third embodiments described above, the case where the a-Si layer and the a-SiC layer are sequentially stacked has been described. However, if a plurality of layers having slightly different compositions are formed, Needless to say, it is applicable to all cases.

  In the first to third embodiments described above, two heating elements 4 are provided. However, three or more heating elements 4 can be applied, and three or more heating elements 4 (that is, the first heating element 4) can be applied. 3 heating elements and a fourth heating element may be provided). Further, there may be a plurality of heating elements 4 (for example, the first heating element 4a and the second heating element 4b) for each group.

  Furthermore, in the first to third embodiments described above, the case where both the base support 3 and the base 2 are cylindrical has been described. However, the present invention can also be applied to the case where the base support 3 and the base 2 are both flat. In this case, for example, a heating element CVD apparatus is configured as shown in FIG. In such an apparatus, the plurality of heating elements 4 are arranged, for example, in a direction perpendicular to the paper surface.

  Further, in the first to third embodiments described above, the case where the first layer and the second layer are laminated on the single substrate 2 has been described. However, the first layer and the second layer are formed on different substrates. The present invention can also be applied to the case of film formation. For example, after the first layer is formed on the substrate using the heat of the first heating element 4a, the substrate is replaced with another substrate, and the second layer is formed on the replaced substrate by the second heating element 4b. It may be formed using heat. Even in this case, the decomposition of the first source gas into the second layer is well suppressed during the formation of the second layer.

  Furthermore, in step (2) of the first to third embodiments described above, the second heating element 4b generates heat at a high temperature between the supply interruption of the first source gas and the start of supply of the second source gas. May be. In this case, even when the component decomposed by the heat of the first heating element 4a adheres to the surface of the second heating element 4b when the first source gas is decomposed, the decomposition component of the first source gas evaporates. Since it is exhausted to the outside, the residual component of the first source gas can be removed better than the surface of the second heating element 4b, and the decomposition component of the first source gas is in the second layer during the formation of the second layer. It is further suppressed that it is taken in. The decomposition component of the first source gas evaporated by the heat of the second heating element 4b is exhausted from the gas exhaust port 6 provided in the vacuum container by suction of a vacuum pump.

  The heating temperature of the second heating element 4b during the period from the interruption of the supply of the first source gas to the start of the supply of the second source gas favorably removes the decomposition component of the first source gas adhering to the surface of the second heating element 4b. Therefore, the vapor pressure temperature of the constituent material of the first layer is preferably set to be equal to or higher. In order to prevent the second heating element 4b from rapidly deteriorating due to heat generation, it is preferable to set the heating temperature to be equal to or lower than the vapor pressure temperature of the second heating element 4b. For example, in the case of the present embodiment, since the constituent material of the first layer is Si, the lower limit value of the heat generation temperature of the second heating element 4b is preferably set to the vapor pressure temperature of Si or higher, that is, 1300 ° C. or higher. . When the second heating element 4b is made of tantalum, the upper limit value of the heating temperature of the second heating element 4b is preferably set to be equal to or lower than the vapor pressure temperature of tantalum, that is, 3250 ° C. or lower.

  The heat generation of the second heating element 4b during the period from the interruption of the supply of the first raw material gas to the start of the supply of the second raw material gas may be continuous or intermittent. In order to satisfactorily remove the decomposition component of the first source gas adhering to the surface of the body 4b, the second heating element 4b is continuously used from the interruption of the supply of the first source gas to the start of the supply of the second source gas. It is preferable to continue to generate heat. The total heat generation time of the second heating element 4b is preferably 10 minutes or more, more preferably 20 minutes or more, regardless of whether heat generation is continuous or intermittent.

(First embodiment)
Next, the above-described operation and effect will be confirmed by specific examples. This first embodiment does not limit the scope of the present invention. In this embodiment, an a-Si photosensitive member 14 having a photosensitive layer composed of a carrier injection blocking layer 11, a photoconductive layer 12, and a surface protective layer 13 on the upper surface of an Al base 10 as shown in FIG. This was prepared using a body CVD apparatus (Examples 1 to 3) and a conventional heating element CVD apparatus (Comparative Example 1), and the charging characteristics of the photosensitive layer of the produced a-Si photoreceptor were evaluated. .

The evaluation of the charging characteristics is carried out by using a corona charger 15 for charging the surface of the photoconductor 14 around the produced a-Si photoconductor 14, a surface potential measuring device 16 for measuring the surface potential of the photoconductor 14, and a photoconductor. As shown in FIG. 13, an erase LED 17 serving as a static elimination means for neutralizing the surface of 14 is disposed as shown in FIG. 13, and the surface charge amount Q (μC / cm ² ) applied to the photoconductor 14 by the corona charger 15 is increased stepwise. In this case, the surface potential of the photoconductor 14 is measured, and the charging ability is examined by the measured value. The peripheral speed of the photosensitive member 14 when measuring the charging ability of the photosensitive member 14 was set to 0.094 m / sec, the wavelength of the erase LED 17 was set to 650 nm, and the light amount was set to 4.0 μJ / cm ² . The surface potential was measured at the second rotation of the photoreceptor for each surface charge amount Q.

  As the heating element CVD apparatus used in the examples and comparative examples, the apparatus corresponding to the configuration of FIG. 1 is used in the examples 1 and 3, the apparatus corresponding to the configuration of FIG. Then, devices corresponding to the configuration of FIG. 15 were used. Examples 1 to 3 are common in that the carrier heating blocking layer 11 and the photoconductive layer 12 are formed by the first heating element, and the surface protective layer 13 is formed by the second heating element. In Example 2, after the photoconductive layer 12 was formed, the second heating element was continuously heated at a temperature of 2200 ° C. for 20 minutes, and then the surface protection layer 13 was formed using the second heating element. 1 and the third embodiment. In Comparative Example 1, the carrier injection blocking layer 11, the photoconductive layer 12, and the surface protective layer 13 were formed with a single heating element.

  In the heating element CVD apparatus used in the examples and comparative examples, the heating element was linearly formed using one tantalum wire having a diameter of 0.5 mm and a purity of 99.9%. A cartridge heater was used as a heating means for the substrate. In the heating element CVD apparatus used in Example 3, a cylindrical light shielding member made of stainless steel was used.

The a-Si photosensitive member 14 was prepared by setting one cylindrical Al substrate having a diameter of 30 mm and a length of 254 mm with a mirror-finished surface in the vacuum vessel of the above-described heating element CVD apparatus, and setting the substrate temperature before film formation. While maintaining the temperature at 250 ° C., the degree of vacuum in the vacuum vessel is set to 1 × 10 ⁻² Pa, and then the carrier injection blocking layer 11, the photoconductive layer 12, and the surface protection are formed on the substrate 10 under the conditions shown in Table 1. This was done by sequentially laminating layer 13.

The above implementation results are shown in FIG. This figure is a diagram showing the relationship between the surface charge amount and the surface potential of the a-Si photoreceptors produced in Examples 1 to 3 and Comparative Example 1, and the horizontal axis of the figure is given to the photoreceptor by corona charging. The surface charge amount Q (μC / cm ² ), and the vertical axis represents the surface potential (V) of the photoreceptor. As is clear from FIG. 14, Examples 1 to 3 showed higher surface potentials for the same surface charge amount as compared with Comparative Example 1, and high charging ability was obtained. Further, Example 2 in which a shielding member is interposed between the heating elements, and Example 3 in which the other heating element is heated after the formation of the photoconductive layer 12 and before the formation of the surface protective layer 3 are more than in Example 1. A slightly high charging ability was obtained. This is because in Example 2, the decomposition component of the source gas of the photoconductive layer 12 is suppressed from adhering to the surface of the second heating element due to the intervention of the shielding member, so that the decomposition component is contained in the surface protective layer 13. It is thought that the mixing was better prevented than in Example 1. In Example 3, the second heating element is heated after the formation of the photoconductive layer 12 to remove the decomposition component of the source gas of the photoconductive layer 12 attached to the surface of the second heating element. It is considered that the mixing into the protective layer 13 was better prevented than in Example 1.

(Second embodiment)
In 2nd Example, the effect by rotation of a shielding member is confirmed. This second embodiment does not limit the scope of the present invention. In this embodiment, the a-Si photosensitive member shown in FIG. 12 is used as the heating element CVD apparatus (Example 4) of the present invention shown in FIG. 5, and the heating element CVD apparatus (Examples 5 and 6) of the present invention shown in FIG. ), And the produced a-Si photoreceptor is mounted on a Kyocera Mita laser printer (ECOSYS FS-3800) to output an image, and the number of black spots in the image is evaluated.

  In any of Examples 4 to 6, the evaluation of the number of black spots in the image was performed by performing solid white printing on A4 paper using the laser printer, and the diameter of 0.1 mm or more existing on the surface of the photoconductor from the obtained image was 0. The operation of measuring the number of sunspots less than 2 mm and the number of sunspots having a diameter of 0.2 mm or more was performed 10 times, and the average number of sunspots was calculated.

  Note that black spots in the image are generated when deposits peeled off from the shielding member adhere to the substrate, resulting in film formation defects in that portion. For example, when the number of black spots is large, When there are many deposits that adhere and the number of sunspots is small, it means that there are few deposits that adhere on the substrate.

  In any of Examples 4 to 6, the carrier injection blocking layer 11 and the photoconductive layer 12 were formed by the first heating element, and the surface protective layer 13 was formed by the second heating element. Empty baking like Example 2 is not performed.

  In the heating element CVD apparatus used in Examples 4 to 6, the heating element is linearly formed using one tantalum wire having a diameter of 0.5 mm and a purity of 99.9%. A cartridge heater was used. Further, a cylindrical member made of stainless steel was used as the light shielding member, and in Examples 5 to 6, the rotation speed of the light shielding member was set to 1 rpm and 10 rpm, respectively.

The a-Si photosensitive member 14 was prepared by setting one cylindrical Al substrate having a diameter of 30 mm and a length of 254 mm with a mirror-finished surface in the vacuum vessel of the above-described heating element CVD apparatus, and setting the substrate temperature before film formation. While maintaining the temperature at 250 ° C., the degree of vacuum in the vacuum vessel is set to 1 × 10 ⁻² Pa, and then the carrier injection blocking layer 11, the photoconductive layer 12, and the surface protection are formed on the substrate 10 under the conditions shown in Table 1. This was done by sequentially laminating layer 13.

The results of the above implementation are shown in Table 2.

  According to Table 2, the average number of sunspots is smaller in Examples 5 and 6 than in Example 4, and good results are obtained. In Examples 5 and 6, gas decomposition components adhering to the shielding member due to the rotation of the shielding member are deposited on the surface of the shielding member with a uniform thickness, so that the adhesion between the deposit and the shielding member is improved. It is considered that this is because the deposits are suppressed from peeling from the surface of the shielding member.

It is a side view of the heat generating body CVD apparatus concerning 1st Embodiment of this invention. It is a top view of the heat generating body CVD apparatus of FIG. It is a side view of the modification of the heat generating body CVD apparatus of FIG. It is a top view of the modification of the heat generating body CVD apparatus of FIG. It is a side view of the heat generating body CVD apparatus concerning 2nd Embodiment of this invention. It is a top view of the heat generating body CVD apparatus of FIG. It is a side view of the modification of the heat generating body CVD apparatus of FIG. It is a top view of the modification of the heat generating body CVD apparatus of FIG. It is a side view of the heat generating body CVD apparatus concerning 3rd Embodiment of this invention. It is a top view of the heat generating body CVD apparatus concerning 3rd Embodiment of this invention. It is a side view of the 2nd modification of the heat generating body CVD apparatus of FIG. It is sectional drawing of the a-Si photoconductor produced in the Example and the comparative example. It is a figure for demonstrating the method to measure a charging capability in an Example and a comparative example. It is a diagram which shows the relationship between the surface charge amount and surface potential of the a-Si photoconductor produced in the Example and the comparative example. It is a side view of the conventional heat generating body CVD apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Vacuum container 2 ... Base | substrate 3 ... Base | substrate support body 4 ... Heat generating body 4a ... 1st heat generating body 4b ... 2nd heat generating body 5 ... Electrode 6 ... Gas Exhaust port 7 ... gas supply means 8 ... gas blowing hole 9 ... shielding member 10 ... Al base 11 ... carrier injection blocking layer 12 ... photoconductive layer 13 ... surface protective layer 14: Photoconductor 15 ... Corona charger 16 ... Surface potential measuring device 17 ... Erase LED
18, 19 ... rotating means

Claims (13)

A vacuum container that accommodates the substrate; a gas supply means that supplies a raw material gas into the vacuum container; and a plurality of heating elements that are arranged to contact the raw material gas supplied from the gas supply means. In the heating element CVD apparatus for decomposing the source gas from the gas supply means by the heat generated by the heating element and depositing the decomposed source gas component on the substrate to form a film,
The plurality of heating elements include a first heating element for thermally decomposing the first source gas supplied from the gas supply means and a second source gas supplied from the gas supply means. A heating element CVD apparatus comprising at least a second heating element. 2. The heating element CVD apparatus according to claim 1, wherein either the first source gas or the second source gas is supplied into the vacuum vessel one by one. The heating element CVD apparatus according to claim 1 or 2, wherein the second heating element has a higher heating temperature than the first heating element. The first heating element and the second heating element are provided so as to be adjacent to each other, and a shielding member is interposed between the first heating element and the second heating element so that the surfaces of the heating elements do not directly face each other. The heating element CVD apparatus according to any one of claims 1 to 3. The heating element CVD apparatus according to claim 4, wherein the shielding member rotates during film formation. The heating element CVD apparatus according to claim 5, wherein a rotation axis of the shielding member is substantially parallel to a longitudinal direction of the shielding member. The first raw material gas is supplied into a vacuum vessel that accommodates the base body, the first heating element, and the second heating element, and the first raw material gas is decomposed by the heat generated by the first heating element, and the decomposition component is decomposed into the base body. A first step of depositing thereon to form a first layer;
The second source gas is supplied into the vacuum vessel in place of the first source gas, the second source gas is decomposed by the heat generated by the second heating element, and the decomposition components are deposited to form the second layer. A film forming method using a heating element CVD method. 8. The film forming method according to claim 7, wherein the second heating element has a higher heating temperature than the first heating element. After the supply of the first source gas is interrupted and before the supply of the second source gas is started, the second heating element is set to a vapor pressure temperature of the constituent material of the heating element that is equal to or higher than the vapor pressure temperature of the constituent material of the first layer. The film forming method according to claim 7 or 8, wherein heat generation is performed in the following manner. The first heating element and the second heating element are provided so as to be adjacent to each other, and a shielding member is interposed between the first heating element and the second heating element so that the surfaces of the heating elements do not directly face each other. A film forming method by a heating element CVD method according to any one of claims 7 to 9. The film formation by a heating element CVD method according to any one of claims 7 to 10, wherein the first layer is composed mainly of an a-Si based material and the second layer is composed of an a-SiC based material. Method. 12. The film forming method according to claim 10 or 11, wherein the shielding member rotates during film formation. The film forming method according to any one of claims 10 to 12, wherein a rotation axis of the shielding member is substantially parallel to a longitudinal direction of the shielding member.

Images