JP2553337C - - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a deposited film, particularly a functional film, on a substrate, particularly a semiconductor device, a photosensitive device for electrophotography, a line sensor for image input, an imaging device, and a photovoltaic device. The present invention relates to an apparatus for forming a functional deposition film such as an amorphous semiconductor used for a power element or the like. Description of the Related Art Conventionally, amorphous silicon, for example, as an element member used for a semiconductor device, a photosensitive device for electrophotography, a line sensor for image input, an imaging device, a photovoltaic element, various other electronic elements, an optical element, and the like, Amorphous silicon (hereinafter referred to as “a”) compensated with hydrogen and / or halogen (eg, fluorine, chlorine, etc.)
—Si (H, X) ”. ) Etc. are proposed.
Some of them have been put to practical use. Such a deposited film is formed by a plasma CVD method, that is, a method in which a raw material gas is decomposed by direct current or high frequency, microwave, or glow discharge to form a thin film deposited film on a substrate such as glass, quartz, stainless steel, and aluminum. Is known, and various devices have been proposed for this purpose. By the way, recently, a plasma CVD method using microwave glow discharge decomposition (hereinafter referred to as “M
W-PCVD method ". ) Has also been attracting attention at the industrial level.
An apparatus for forming a deposited film by the W-PCVD method typically has an apparatus configuration shown in a schematic sectional view of FIG. In FIG. 3, reference numeral 301 denotes an entire reaction vessel, 302 denotes a vacuum vessel, 303 denotes a microwave introduction window formed of a dielectric material such as alumina ceramics or quartz.
04 is a microwave waveguide for transmitting microwaves, 305 is a microwave power supply, 30
An exhaust pipe 6 communicates with an exhaust device (not shown) via a valve (not shown).
Is a ring-shaped source gas supply pipe communicating with a source gas supply source (not shown);
Reference numeral 9 denotes a substrate, 310 denotes a substrate heater, 311 denotes a plasma generation region, and 312 denotes a microwave. In addition, in order to start discharge by self-excited discharge without using a discharge trigger or the like, the vacuum container 302 generally has a cavity resonator structure that resonates with the oscillation frequency of the microwave power supply 305. . The formation of a deposited film by such an apparatus is performed as follows. That is, the inside of the vacuum vessel 302 is evacuated through the exhaust pipe 306, and the base 309 is heated and maintained at a predetermined temperature by the base heater 310. Next, in the case of forming an amorphous silicon deposition film via the source gas supply pipe 307, for example, a source gas such as silane gas or hydrogen gas is supplied to the plurality of gas discharge holes 307 opened in the source gas supply pipe. 'Into the vacuum vessel 302. Simultaneously with this, the microwave power supply 305 supplies a frequency of 500 MHz or more, preferably 2.45.
A microwave 312 of GHz is generated, and the microwave is introduced into the vacuum chamber 302 through the waveguide 304 and the microwave introduction window 303. Thus, the source gas introduced into the vacuum vessel 302 is excited and dissociated by microwave energy to generate neutral radical particles, ion particles, electrons, etc., which react with each other and deposit on the surface of the substrate 309. Is formed. However, the functional deposition film forming apparatus using the conventional MW-PCVD method as described above has a small film forming area and exhibits a predetermined film forming performance when the film forming rate is low, but the same apparatus can form a film. When an attempt is made to increase the speed and increase the area of the substrate, there is a problem that the quality of the deposited film to be formed is deteriorated. In particular, when a relatively thick deposited film is to be formed at a high speed on a large-area substrate such as an electrophotographic photoreceptor, it is difficult to constantly and stably obtain a deposited film having good characteristics. It is. [Object of the Invention] The present invention overcomes the above-mentioned problems in the conventional deposition film forming apparatus by the MW-PCVD method as described above, and provides a semiconductor device, an electrophotographic photoreceptor device, an image input line sensor, and an imaging device. Functional deposition films as element members used for devices, photovoltaic elements, other various electronic elements, optical elements, etc., are manufactured using MW-PC
It is an object of the present invention to provide an apparatus which can be formed constantly and efficiently by a VD method. That is, a main object of the present invention is a case where a relatively thick deposited film is formed at a high speed on a long substrate such as an electrophotographic photosensitive member in an apparatus for forming a functional deposited film by the MW-PCVD method. Another object of the present invention is to provide an apparatus capable of constantly forming a deposited film having good film quality. Another object of the present invention is to form a functional deposition film having excellent mass productivity, high quality, excellent electrical, optical, or photoconductive properties by a MW-PCVD method. It is to provide a device. [Configuration and Effect of the Invention] The present inventor has conducted intensive studies to solve the above-mentioned problems in the conventional deposited film forming apparatus by the MW-PCVD method and to achieve the object of the present invention. Various problems in the deposited film forming apparatus by the MW-PCVD method are as follows: when microwave energy used for high-speed film formation is large, or when microwaves are introduced for a long time, (i) Thermal radiation of plasma generated by microwaves, (ii) a part of the introduced microwaves is absorbed by the microwave permeable material constituting the microwave introduction window, (iii) microwave introduction window Since the structure itself or the space between the reflection surface of the microwave introduction window and the other reflection surface becomes a cavity for the microwave to be introduced, a part of the microwave energy is consumed. , Due to causes like, in some cases microwave introduction window around proved to be due largely to become heated to above 500 ° C.. That is, the microwave introduction window in the above-mentioned conventional functional deposition film forming apparatus based on the MW-PCVD method is generally formed of a substance that transmits a microwave while maintaining a gas atmosphere such as quartz and alumina ceramics. The window made of the microwave permeable material is formed of a rubber gasket such as viton or a metal gasket such as copper or aluminum as in the case of a normal vacuum seal. However, when a rubber gasket is used, the heat generated by the temperature rise causes the material of the gasket to deteriorate, and the external gas (air) is mixed into the vacuum vessel, thereby deteriorating the quality of the deposited film. It will be a place to do. Also, when using a metal gasket, the sealing surface shifts when the temperature rises due to the difference in the coefficient of thermal expansion between the microwave permeable material and the gasket, deteriorating the gas atmosphere holding performance, and depositing due to the incorporation of air. This is where the quality of the film deteriorates. In order to prevent such temperature rise near the microwave introduction window, a method of cooling the microwave introduction window has been proposed.However, since the distribution of the electric flux lines is generated depending on the mode at the time of introduction of the microwave, for example, When microwaves are introduced in the circular TE ₁₁ mode, only two diametrical ends of the microwave introduction window are locally heated along the electric field of the microwaves. It was also found that the above problem could not be solved only by performing the above. The present invention has been further studied on the basis of these findings. In order to stably deposit a high-quality deposited film on a long substrate at high speed in a deposition film forming apparatus using a microwave plasma CVD method, local deposition is required. That the sealing means which does not deteriorate the gas atmosphere holding ability even by the excessive heating is indispensable, and the sealing means optimizes the material constituting the gasket and the surface property of the microwave permeable material in contact with the gasket. Has been reached. The present invention has been completed based on the above findings. The apparatus for forming a functional deposition film by the microwave plasma CVD method according to the present invention includes a vacuum container (which can be evacuated) that can be substantially sealed, a means for holding a substrate for forming a functional deposition film in the vacuum container, Means for supplying a source gas into a vacuum vessel, and 5 × 10 ^-6 T
What is claimed is: 1. An apparatus for forming a functional deposited film by microwave plasma CVD, comprising: means for evacuating the inside of a vacuum vessel to a pressure of not more than orr, wherein said vacuum vessel has at least partly a sealing means on a wall of said vacuum vessel. A microwave introduction window made of a microwave permeable material for introducing microwave energy provided through the gap, and a surface of the microwave permeable material contacting the sealing means has a surface roughness of 3 .2
S or less. Hereinafter, an apparatus for forming a deposited film by the microwave plasma CVD method of the present invention will be described in more detail with reference to embodiments of the drawings, but the apparatus for forming a deposited film of the present invention is not limited thereto. FIG. 1 is a schematic sectional view of the vicinity of a microwave introduction window of a deposition film forming apparatus using a microwave plasma CVD method according to the present invention. In the figure, 101 is a wall surface of a vacuum vessel, 102 is a microwave introduction window made of a microwave permeable material, 103 is a gasket for holding a gas atmosphere, 104 is a microwave introduction window holder, 105 is a microwave plasma space, and 106 is a microwave plasma space. The waves are shown respectively. In the present invention, a dielectric material such as alumina ceramics or quartz is used as the microwave transmitting material constituting the microwave introduction window. Further, as a gasket for maintaining a gas atmosphere, a constituent material of the gasket is selected and used according to the microwave permeable material, but if the microwave introduction window is made of alumina ceramic, as a gasket, It is preferable to use an O-ring whose contact surface with the microwave permeable material is made of aluminum, and in particular, a structure having an elastic core inside the aluminum coating and having an elastic restoring force has a reliable and durable seal. Optimal from. FIG. 2 shows a microwave CVD suitable for manufacturing a photosensitive drum for electrophotography.
FIG. 1 is a schematic perspective view schematically showing a functional deposited film forming apparatus by a method, and a configuration near a microwave introduction window in the apparatus is as shown in FIG. In FIG. 2, 201 is a vacuum vessel, 202 is a microwave introduction window made of a microwave permeable material, 203 is a microwave waveguide, 204 is a microwave, 205 is an exhaust pipe, 206 is a drum-shaped substrate, and 207 is plasma. Each of the occurrence areas is shown. The plasma generation region 207 has a microwave cavity resonance structure surrounded by the microwave introduction window 202 and substrates 206, 206,... Arranged concentrically, and the energy of the introduced microwave is efficiently reduced. Absorbs well. In the apparatus shown in FIG. 3, since a plurality of drum-shaped substrates are arranged on concentric circles around the plasma generation region, it is suitable for mass production of electrophotographic photosensitive drums. The source gas used to form the deposited film by the apparatus of the present invention is of a kind that is excited by high frequency or microwave energy to be seeded and chemically interacts to form the desired deposited film on the substrate surface. For example, when forming an a-Si (H, X) film, silicon, hydrogen, halogen, or hydrocarbon may be used. It is possible to use silanes and halogenated silanes, etc., which are bonded to each other, or gaseous ones that can be easily gasified. One of these source gases may be used,
Alternatively, two or more kinds may be used in combination. These source gases may be diluted with an inert gas such as He or Ar before use. Further, the a-Si (H, X) film can be doped with a p-type impurity element or an n-type impurity element, and a source gas containing these impurity elements as a constituent component can be used alone or as described above. And / or a diluent gas. Also, as for the substrate, even if it is conductive, even if it is semiconductive,
Alternatively, it may be an electrically insulating material, and specific examples thereof include metal, ceramics, and glass. The substrate temperature during the film formation operation is not particularly limited.
The temperature is generally in the range of 0 to 450 ° C, preferably 50 to 350 ° C. In forming a deposited film, the pressure in the reaction chamber is set to 5 × 10 ⁻⁶ Torr or less, preferably 1 × 10 ⁻⁶ Torr or less before the source gas is introduced. The pressure is 1 × 10 ^-2 to 1 Torr, preferably 5 ×
It is desirable that the pressure be 10 ^{-2 to 1} Torr. In the formation of a deposited film by the apparatus of the present invention, usually, as described above, a raw material gas is introduced into a reaction chamber without pretreatment (excitation seeding), where it is excited and seeded by microwave energy, and is chemically and chemically converted. This is done by causing an interaction,
When two or more kinds of source gases are used, it is possible to excite one of them into excited species in advance and then introduce them into the reaction chamber. [Example] Hereinafter, formation of a functional deposition film using the apparatus of the present invention shown in FIGS.
The present invention will be described specifically with reference to Examples and Comparative Examples, but the present invention is not limited to these. Example 1 In this example, alumina ceramics was used as a microwave transmitting material,
An O-ring coated with aluminum was used as a gasket. First, the inside of the vacuum vessel 201 is evacuated through an exhaust pipe 205, and is heated and held at a predetermined temperature by a heater (not shown) built in the cylindrical bases 206, 206,. (Not shown) at a desired rotation speed. The silane gas (Si) is supplied to such a place via a source gas supply pipe (not shown).
H _4), hydrogen gas (H _2), the raw material gas such as diborane gas (B ₂ H ₆₎ into the vacuum chamber 201 under the conditions shown in Table 1, while maintaining the degree of vacuum of 1 × 10 ^-2 Torr Released. Next, a microwave having a frequency of 2.45 GHz is introduced into the plasma generation region 207 through the waveguide 203 and the introduction window 202 made of a microwave permeable material, and charge is injected onto the cylindrical substrates 206, 206,. The blocking layer, the photosensitive layer, and the surface layer were successively formed to obtain a photosensitive drum having a blocking structure. In this example, the surface property of the contact surface with the gasket of alumina ceramics (purity 99.9%, relative dielectric constant 10.5, alumina particle diameter 20μ) which is a microwave transmitting material is shown in Table 2. Four kinds of materials which were changed as described above were used. For the surface properties of the microwave transmitting material, particularly those having a small surface roughness of 0.8S or less were processed by lapping. The photosensitive drum manufactured as described above was used as a copier NP755 manufactured by Canon Inc.
When the camera was set at 0 and an image was output, the results shown in Table 2 were obtained. Table 2 shows the difference in image quality of the produced photosensitive drum with respect to the gasket coating material. As for the image quality, an image flow generated when air was contained as an impurity in the film was mainly examined. At this time, it was confirmed that air was blown onto the alumina ceramic at a rate of 30 l / min to cool and not to cool. In addition, as a cooling method, a method such as flowing liquid nitrogen was used, but the same effect as the cooling by air was obtained. Example 2 A photosensitive drum was produced in the same manner as in Example except that quartz was used as the microwave transmitting substance, and the image quality of the produced photosensitive drum was compared.
The same result as in Example 1 was obtained. From these results, it was found that if the surface roughness of the microwave transmitting material is set to 3.2S or less, a functional deposited film having excellent characteristics without practical problems can be obtained by the microwave plasma CVD method. did. Further, it was also found that when the surface roughness was set to 0.8S or less, a functional deposited film having excellent characteristics without practical problems without using other means such as cooling was obtained. According to the present invention, particularly when alumina ceramics is used as the microwave transmitting material, in order to achieve a surface property of 3.2S, the alumina particle size must be 100 or less.
It has also been found that the particle size of alumina needs to be 20 μm or less in order to achieve 0.8S or less and 0.8S.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic sectional view near a microwave introduction window. FIG. 2 is a schematic perspective view of an apparatus for forming an amorphous silicon photosensitive drum by a microwave plasma CVD method. FIG. 3 is a schematic sectional view of an apparatus for forming a deposited film on a flat substrate by a microwave plasma CVD method. In the figure, 101: vacuum vessel wall surface, 102: microwave transparent material, 103: gasket,
104 ... press, 105 ... microwave plasma space, 106 ... microwave, 20
DESCRIPTION OF SYMBOLS 1 ... Vacuum container, 202 ... Microwave introduction window, 203 ... Microwave waveguide part, 204
... microwave, 205 ... exhaust pipe, 206 ... drum-shaped substrate, 207 ... microwave plasma generation region, 301 ... reaction vessel, 302 ... vacuum vessel, 303 ... microwave introduction window, 304 ... waveguide, 305 ... microwave power supply 306: exhaust pipe, 307: source gas supply pipe, 308: base holding plate, 309: base, 310: base heating heater, 311: plasma generation area, 312: microwave.

Claims (1)

Claims: A substantially sealed vacuum vessel, means for holding a substrate for forming a functional deposited film in the vacuum vessel, means for supplying a source gas into the vacuum vessel, and 5x
What is claimed is: 1. A functional deposition film forming apparatus using a microwave plasma CVD method, comprising: means for evacuating the inside of a vacuum vessel to a pressure of 10 ^-6 Torr or less , wherein the vacuum vessel is at least partially provided on a wall of the vacuum vessel. It has a microwave introduction window made of a microwave permeable material for introducing microwave energy provided through a sealing means, and a surface roughness of a surface of the microwave permeable material which comes into contact with the sealing means. Saga functional deposited film forming apparatus according to a microwave plasma CVD method, wherein the 3.2S or less.