JPH04333573A - Microwave plasma cvd apparatus - Google Patents

Abstract

PURPOSE:To offer an apparatus for forming a deposited film capable of stably forming a functional deposited film having good properties at low cost in high yield at high speed by a microwave plasma CVD method. CONSTITUTION:As for a microwave introducing window 102, alumina is used as a base metal, to which partially stabilized zirconia is added in the range of 1 to 90% and is uniformly dispersed, and baking is executed into an alumina- zirconia base composite. In this way, its durability to severe use by the repetition of the formation of a film on a microwave introducing window by a microwave plasma CVD method and the removal of the deposited film as posttreatment after the film forming can be improved.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention is applicable to films deposited on cylindrical substrates, particularly functional films, particularly semiconductor devices, photoreceptor devices for electrophotography, line sensors for image input, imaging devices, photovoltaic devices, etc. The present invention relates to a microwave plasma CVD apparatus that forms a deposited film using a microwave plasma CVD method using an amorphous deposited film.

0002

[Prior Art] Amorphous silicon, such as hydrogen or hydrogen Amorphous deposited films such as amorphous silicon compensated with and halogen (eg, fluorine, chlorine, etc.) have been proposed, and some of them have been put into practical use.

Conventional methods for forming such a deposited film include a sputtering method, a method of decomposing the source gas by heat (thermal CVD method), and a method of decomposing the source gas by light (optical CVD method).
A large number of methods are known, such as method D) and a method of decomposing the source gas using plasma (plasma CVD method). Among these, the plasma CVD method, in which a raw material gas is decomposed by direct current, high frequency, microwave glow discharge, etc., and a thin film deposited film is formed on a substrate such as glass, quartz, heat-resistant synthetic resin film, stainless steel, or aluminum. The method is currently being put into practical use as a method for forming an amorphous silicon deposited film for electrophotography, and various apparatuses for this purpose have also been proposed. In particular, in recent years, the plasma CVD method (hereinafter referred to as MW-PCVD) using macrowave glow discharge decomposition has been used as a method for forming deposited films.
(hereinafter referred to as "law") is attracting attention from an industrial perspective.

[0004] The MW-PCVD method has advantages over other methods in terms of high deposition rate and high raw material gas utilization efficiency. One example of microwave plasma CVD technology that takes advantage of these advantages is U.S. Patent No. 4,504,51
It is stated in No. 8. The technology described in the patent is 0.
A high quality deposited film can be obtained at a high deposition rate by the MW-PCVD method using a low pressure of 1 Torr or less.

Furthermore, a technique for improving the utilization efficiency of raw material gas by the MW-PCVD method was disclosed in Japanese Patent Application Laid-Open No. 60-186.
It is described in Publication No. 849. In the technology described in this publication, a base body is arranged to surround a microwave energy introduction part to form an internal chamber (i.e., a discharge space), thereby greatly increasing raw material gas utilization efficiency. .

These prior art techniques have made it possible to produce relatively thick photoconductive materials with reasonably high deposition rates and efficient raw material gas utilization.

FIGS. 4A and 4B are a partial vertical cross-sectional view along the axis of a conventional microwave plasma CVD apparatus and a cross-sectional view taken along the XX section thereof, respectively.

[0008] The reaction vessel 401 has a vacuum-tight structure. Further, the microwave introduction window (hereinafter referred to as introduction window) 402 is made of a material (for example, quartz glass, alumina ceramics, etc.) that can efficiently transmit microwave power into the reaction vessel 401 and maintain vacuum confidentiality. It is formed. The waveguide 403 is a waveguide for transmitting microwave power, and consists of a rectangular part extending from the microwave power source to the vicinity of the reaction vessel 401, and a cylindrical part inserted into the reaction vessel 401. It is connected to a microwave power source (not shown) along with a tuner (not shown) and an isolator (not shown). The introduction window 402 is hermetically sealed to the inner wall of the cylindrical portion of the waveguide 403 in order to maintain the atmosphere within the reaction vessel 401 . exhaust pipe 40
4 opens into the reaction vessel 401 at one end and communicates with an exhaust system (not shown) at the other end. tubes 408, 409
9 is a raw material gas supply pipe. The discharge space 406 is a space surrounded by the cylindrical base 405 . Further, this device includes a heating heater 407, a rotating shaft 410, and a rotating motor 411. Note that the reaction container 4
Since the 01 starts discharge by self-excited discharge without using a discharge trigger or the like, it generally has a cavity resonator structure that resonates with the oscillation frequency of the microwave power source (not shown).

Such conventional microwave plasma CV
Formation of a deposited film on an electrophotographic photoreceptor using apparatus D is generally carried out as follows.

First, a cylindrical substrate 405 for forming a deposited film is prepared.
Clean the substrate to remove oil, dust, and other surface contaminants. Additionally, the microwave introduction window 402
Clean other parts thoroughly. Then, the reaction vessel 401 is opened in the dust-free room to bring it to atmospheric pressure. Next, a cylindrical substrate 405 is placed in a reaction vessel 401 for forming a deposited film.
and an introduction window 402 etc. are installed. Reaction vessel 40 again
1. Close the exhaust pipe 40 using a vacuum pump (not shown).
4, the reaction vessel 401 is evacuated, and the reaction vessel 401 is evacuated via
01 Adjust the pressure within 1 x 10-7 Torr or less. Next, the temperature of the substrate 405 is maintained at a temperature suitable for film deposition using a heater 406 . There, a source gas such as silane gas is introduced into the reaction vessel 401 through tubes 408 and 409 for supplying source gas, for example, in the case of forming an amorphous silicon deposited film. At the same time, a microwave power source (not shown) generates microwaves with a frequency of 500 MHz or more, preferably 2.45 GHz, through the waveguide 403 and into the introduction window 4.
Microwave energy is introduced into the reaction vessel 401 via 02. In the discharge space 406 surrounded by the base 405, the raw material gas is excited by the microwave energy and dissociates, producing neutral radical particles, ion particles, electrons, etc., which react with each other.
A deposited film is formed on the surface of the base 405. At this time, the rotating shaft 410 of the holder on which the base 405 is installed is rotated by the motor 411, and the base 405 is rotated around the central axis in the base generatrix direction.
A deposited film is formed uniformly over the entire circumference of the 5.

[0011]

Problems to be Solved by the Invention The above-mentioned conventional microwave plasma CVD apparatus has the following drawbacks:
There are problems shown below.

Conventionally, a material with a small dielectric constant (E) and a small dielectric loss angle (tan δ) has been used for the introduction window in order to prevent transmission loss as much as possible. Examples of materials selected based on the dielectric constant and dielectric loss angle include beryllia (BeO), Teflon, and alumina ceramics. Furthermore, the characteristics that the introduced window material should have include discharge heat radiation,
Alternatively, it is necessary to have heat resistance and thermal shock resistance against the rise in temperature of the window due to absorption of microwaves, as well as vacuum retention ability to maintain a vacuum inside the reaction vessel. Conventionally, a window made of substantially 100% alumina has been used as a window material that satisfies such strict conditions. On the other hand, in order to further increase the film formation speed to improve film quality and reduce costs, it is necessary to increase the power of the microwaves introduced, and conventional window materials are When microwave power is continuously introduced to excite and maintain plasma discharge, it may be short-lived due to temperature rise due to microwave absorption of the deposited film deposited on the introduction window, or temperature rise due to microwave absorption of the introduction window itself. The disadvantage is that melting or destruction of the window material occurs over time.

For example, in the production of amorphous silicon photoreceptors, the thickness of the deposited film on the drum is usually 30 microns or more. At this time, a deposited film is similarly formed on the surface of the introduction window facing the reaction vessel. In particular, in the case of a microwave plasma CVD apparatus in which a cylindrical substrate is arranged so as to surround the discharge space as shown in FIGS. 4(A) and 4(B) in order to increase the raw material gas utilization efficiency, the entire surface of the cylindrical substrate is Since the introduction window is stationary, the thickness of the film deposited on the introduction window is several times that of the film deposited on the surface of the cylindrical substrate. turn into.

However, when a thick deposited film is formed on the surface of the introduction window, the following problems occur. (1) The deposited film deposited on the surface of the introduction window reflects and absorbs the microwaves passing through the introduction window, reducing the transmittance of the microwaves and preventing sufficient microwave power from entering the reaction vessel. (2) Microwaves are absorbed by the deposited film deposited on the surface of the introduction window, which increases the temperature and causes melting and destruction of the introduction window. (3) When the film deposited on the surface of the introduction window becomes thick, its internal stress causes it to peel off and scatter, contaminating the film forming atmosphere and causing defects in the deposited film on the substrate.

These problems reduce the durability of the introduction window and become even more pronounced under conditions of increased microwave power.

[0016] For continuous use under such conditions of increased microwave power, there is no highly durable introduction window material, and the problem is that it cannot withstand practical use at all when productivity is taken into account. , Various studies have been made to address these problems. For example, in order to solve the problem of the durability of the introduction window, Japanese Patent Application Laid-Open No. 64-56873 uses alumina ceramics such as SiO2, CaO2,
A technique has been disclosed in which the heat resistance, thermal shock resistance, microwave transmittance, etc. of the introduction window are improved by adding a small amount of a glassy component such as , MgO 2 or the like. As a result, the durability of the introduced window has improved to some extent compared to the conventional one. Furthermore, in order to solve the problem of the decrease in microwave transmittance due to the deposited film deposited on the surface of the introduction window,
One of the countermeasures is disclosed in the publication No. The technology described in this publication has a rough introduction window surface,
This suppresses the reduction in resistance of the deposited film deposited on the introduction window and suppresses the decrease in microwave transmittance.

With the progress of such deposited film forming methods,
Although it has become possible to obtain a deposited film with practical characteristics and uniformity at a certain deposition rate, the following problems exist in production equipment that repeatedly produces many batches.

As mentioned above, since a deposited film is also deposited on the surface of the introduction window on the side of the reaction vessel, it is removed from the reaction vessel after each film formation and the deposited film is removed by alkali etching or sandblasting. are being reused. This process of removing the deposited film gradually deteriorates the introduction window itself, and to some extent, if the process of film formation and removing the deposited film is repeated, durability such as heat resistance, thermal shock resistance, and mechanical strength will decrease. As a result, film peeling may increase during film formation, or melting or destruction may occur. Therefore,
Measures taken at the time of film formation, such as heat resistance, thermal shock resistance, mechanical strength, or suppression of decrease in microwave transmittance, were still insufficient to withstand the repeated harsh conditions of use during mass production. .

The introduction window must also have excellent heat resistance, thermal shock resistance, vacuum retention, and microwave transmission properties. Conventional window materials are made of alumina ceramics, SiO
2. Durability has been improved to some extent by adding small amounts of glassy components such as CaO and MgO, but the durability against repeated operations of film formation and post-processing to remove the deposited film has not been improved. The problem was not always satisfactory.

As described above, when considering efficiency in productivity, such problems remain to be solved.

[0021] The object of the present invention is to
- Overcome various problems in microwave plasma CVD equipment using the PCVD method and use it for semiconductor devices, photoreceptor devices for electrophotography, line sensors for image input, imaging devices, optical power devices, and other various electronic devices and optical devices. It is an object of the present invention to provide a microwave plasma CVD apparatus capable of forming a deposited film having good characteristics as an element member at low cost, stably, with high yield, and at high speed by the MW-PCVD method.

An object of the present invention is to provide a microwave plasma CVD apparatus capable of forming a relatively thick amorphous silicon deposited film of 10 microns or more at high speed by using the MW-PCVD method. . Specifically, the materials for the microwave introduction window are:
It has excellent heat resistance, secondly, it has excellent thermal shock resistance, thirdly, it has high fracture toughness with excellent mechanical strength, fourthly, it has excellent vacuum retention characteristics, and fifthly, it has excellent film formation and removal of deposited films. It is an object of the present invention to provide an introduction window in which the first to fourth characteristics can be maintained for a longer period of time even under severe repeated use.

[0023]

[Means for Solving the Problem] In order to achieve the above object, an amorphous silicon functional deposited film can be efficiently and stably deposited using a conventional microwave CVD apparatus which has the advantages of high deposition rate and high gas utilization efficiency. Therefore, the microwave introduction window that can efficiently and stably transmit the microwave power supplied from the microwave oscillator into the reaction vessel is sufficient for repeated use of film formation and post-processing after film formation. Durability is essential, and for this reason, by using an alumina-zirconia composite material as the introduction window material, it is possible to improve the heat resistance and thermal shock resistance in the MW-PCVD method, and also to improve the durability after the introduction window is formed. It was found that it is possible to obtain an excellent and highly durable introduction window that can sufficiently withstand repeated use in the post-treatment of removing the deposited film deposited on the introduction window.

The present invention was completed based on this knowledge, and its gist is that a base is placed in a reaction vessel that can be substantially sealed, and an introduction window is provided in a discharge space in contact with the base. A microwave plasma CVD method is used to form a deposited film by a microwave plasma CVD method, which includes means for introducing microwaves through the reactor to generate microwave discharge plasma, means for supplying raw material gas, and means for evacuating the inside of the reaction vessel. In the wave plasma CVD apparatus, the microwave introduction window is composed of Al2O3 and ZrO2, of which ZrO2 partially stabilized or stabilized by stable household materials is contained in a composition ratio of 1% to 90%. This is an alumina-zirconia composite ceramic in which the other components are substantially α-alumina.

[0025]

[Action] By using alumina-zirconia composite ceramic material as a microwave introduction window material, the durability against repeated use of film formation and deposited film removal on the introduction window is improved, and it can be used continuously over a long period of time. A deposited film with excellent properties is stably formed.

[0026]

EXAMPLES Next, experiments on which the present invention is based and their results will be explained. Experiment 1 Alumina (A-16SG), partially stabilized zirconia (T
Z-3Y), a dispersant (polyacrylic acid ammonium salt), and pure water were mixed in the composition ratio shown in Table 1, placed in an alumina ball mill, and alumina balls of 25φ, 15φ, and 5φ were mixed at a weight ratio of 1. : The same weight as the raw material powder was used at a ratio of 1:1 and wet mixed at a rotation speed of 120 rpm for 48 hours to obtain a slurry. After vacuum degassing this slurry, 32
The alumina-zirconia composite ceramic of the present invention is passed through a mesh filter, press-formed at a pressure of 1500 kg/cm2, calcined at 1000°C in an electric furnace, chamfered, and then main fired at 1600°C. A microwave power introduction window was fabricated. Using the introduction window prepared under the above conditions and the MW-PCVD apparatus shown in Figure 1, continuous discharge was performed under the discharge conditions shown in Table 2, and the alumina-zirconia composite ceramic was destroyed and it became impossible to continue the discharge. The discharge maintenance time was measured. The results are shown in Table 3. Here ◎ is durability time 15
0 minutes or more, ○ means durability time of 110 minutes or more, Δ means durability time of 60 minutes or more, × means durability time of less than 30 minutes. As is clear from Table 3, the alumina-zirconia composite ceramic according to the present invention has excellent discharge stability and heat resistance when the alumina/zirconia composition ratio is in the range of 99/1 to 10/90. 5-50/50
It was found that the discharge stability and heat resistance were extremely excellent within the range of . The inventors believe that this is because the zirconia particles dispersed in the alumina matrix can exist as a tetragonal crystal even at room temperature. We believe that this is due to the improvement in fracture toughness.

[0027]

[Table 1]

[0028]

[Table 2]

[0029]

[Table 3] Experiment 2 In order to investigate the durability against alkali etching and sandblasting, which are post-treatments after film formation, an introduction window with the composition ratio shown in Table 1, which was prepared under the same conditions as Experiment 1, was used.
The sample was left in a NaOH solution at pH≈13 for 1 hour, washed with water for 30 minutes, and dried at 150°C for 1 hour. Next, the surface of the introduction window was sandblasted for 10 minutes at a pressure of 4 kg/cm2 using a glass abrasive having a particle size of about 100 microns. After repeating this operation 50 times,
Under the same conditions as in Experiment 1, the stability of the discharge and the discharge maintenance time until the alumina-zirconia composite ceramic became impossible to continue the discharge due to destruction were measured. The results are shown in Table 4.

[0030]

[Table 4] Here, ◎ means durability time of 150 minutes or more, and ○ means durability time of 11 minutes.
0 minutes or more, △ means durability time of 60 minutes or more, × means durability time of 3 minutes
It means less than 0 minutes. As is clear from Table 4, the alumina-zirconia composite ceramic according to the present invention has an alumina/zirconia composition ratio of 99/1 to 10/1 even when used repeatedly under such harsh conditions of alkali etching and sandblasting. Excellent discharge stability and heat resistance in the range of 90%, especially in the range of 95/5 to 50%.
It was found that the discharge stability and heat resistance were extremely excellent in the range of /50. Experiment 3 The characteristics of ceramic materials change depending on the firing conditions. Therefore, in order to investigate the influence of the production temperature of the introduction window, the calcining temperature of the press-formed body was varied from 600 to 1400°C, and the appearance of the calcined body was evaluated. The introduction window was produced by firing at a temperature varying to ℃. The introduced window prepared by MW-PCVD is shown in Figure 1.
The same evaluation as in Experiment 2 was conducted using the device. however,
The alumina-zirconia composition ratio was blended under the conditions of Sample 6 (alumina/zirconia = 80/20), and the conditions for preparing the slurry were the same as in Experiment 1. The results are shown in Tables 5-1 and 5-2.

[0031]

[Table 5]

[0032]

[Table 6] Table 5-1 shows the calcination temperature of the molded body after press molding and the evaluation of the calcined body after calcination. Here, ◎ means very good, ○ means good, △ means insufficient calcination or the occurrence of minute cracks at the edges, × means very insufficient calcination or the occurrence of large cracks in some parts. There is. Furthermore, Table 5-2 shows the durability of the introduction window against continuous discharge. Here ◎ is durability time 1
50 minutes or more, ○ means durability time of 110 minutes or more, Δ means durability time of 60 minutes or more, and × means durability time of less than 30 minutes. As is clear from Tables 5-1 and 5-2, the calcination temperature and main calcination temperature of the microwave introduction window in the present invention are 700 to 1200°C and 1200 to 1700°C, respectively.
°C, preferably 750 to 1150 °C, 125 °C, respectively
0 to 1650°C, preferably 800 to 11°C, respectively
It can be seen that the temperature ranges from 00°C to 1300 to 1600°C. Furthermore, sample 3 to sample 1 with the composition shown in Table 1
Similar operations and similar evaluations were performed on Sample No. 3, and similarly good results were obtained.

The conditions for manufacturing the introduction window used in this experiment were as follows: alumina/zirconia composition ratio of 80/20, pressing pressure of 1500 kg/cm2, calcination temperature of 1000°C, and main firing temperature of 1600°C.

The characteristics of the alumina-zirconia composite ceramic according to the present invention indicate that partially stabilized ZrO2 must be present in an optimal range with respect to α-alumina, which is the main raw material. In other words, if the composition ratio of unstable ZrO2 exceeds 50%, there will be no problem in terms of strength, but the microwave transmittance will decrease slightly, making it difficult to apply microwave power to the reaction vessel. This is not preferable because it increases the loss. On the other hand, if the partially stabilized ZrO2 is less than 1% in composition ratio, that is, the α-alumina component is present in more than 99.5%, it can be used for general purposes by firing at a high temperature, but it cannot be used for microwave introduction windows. This is not preferable as a material because the bonds between alumina particles are weak and cannot withstand thermal shock due to microwave absorption heat generation and plasma radiant heat, resulting in destruction. Therefore, the effective range of the composition ratio of partially stabilized ZrO2 mixed with α-alumina, which is a feature of the present invention, is 1%.
It is 90% or less, preferably 5% or more and 50% or less.

The alumina-zirconia composite ceramic material of the present invention can be used as a microwave introduction window material because of the internal heat generation of the alumina ceramic due to microwave absorption and the plasma generated in the reaction vessel. It is extremely stable against extremely severe thermal shocks from both external heat due to radiation and enables continuous reactions for long periods of time. It has become possible to significantly improve the durability of the product even when used repeatedly to remove the deposited film (alkaline etching/sandblasting).

As the alumina for the microwave introducing window material in the present invention, α-alumina having a particle size of 0.01 to 10 μm, preferably 0.05 to 5.0 μm is suitable. Similarly, zirconia has a particle size of 0.001 to 5.
．． Partially stabilized zirconia of 0 μm, preferably 0.05 to 3.0 μm, is suitable. In addition, as stabilizers for zirconia, CeO2, CaO, MgO, Y2
It is effective to use any stabilizer such as O3. Furthermore, it is equally effective to use unstabilized zirconia and stabilized or partially stabilized zirconia in combination. It is also effective to roughen the surface of the introduction window on the side of the reaction vessel according to the present invention. As for the powder mixing method, there is no problem with either dry mixing or wet mixing, as long as alumina and zirconia are uniformly dispersed. As the forming method, any forming method such as casting method, pressure forming method, hot pressing method, hot isostatic pressing method, etc. is effective.

The shape of the introduction window in the present invention may be rectangular or circular, but in this experiment, a circular, ie, disc-shaped window material was used. FIG. 2 shows the shape of the introduction window itself and the introduction window material. Microwave power 200 is rectangular waveguide 201
, are introduced through an introduction window 203 through a circular waveguide 202 . Although the rectangular waveguide 201 and the circular waveguide 202 are converted into a horn type in FIG. 2, they may be directly converted from a rectangular waveguide to a circular waveguide without using a horn type conversion unit. Also, without circular conversion up to the introduction window 203,
It may also be guided directly through a rectangular waveguide. Microwave introduction window 20
3 is designed by the following well-known formula when the microwave mode to be used is TE11 mode. λ=2π/((1
．． 84/a√ε)2 + (π/d√ε)2 )1/2
In the formula, λ is the resonant wavelength (12.245 cm for 2.45 GHz microwave), a is the radius (cm) of the circular introduction window, and ε is the relative dielectric constant. Therefore, the dielectric constant ε≒10 of alumina ceramics, radius a=5.08 cm,
The resonance condition can be satisfied with the thickness d=1.91 cm.

Here, the length d=1.91 cm is 1/2 of the wavelength of the microwave propagating within the alumina ceramics.
corresponds to the length of

Shape radius a of alumina ceramics a=5.
08cm, thickness d=1.91cm is 1 in the thickness direction
Although it is preferable to use a multilayer structure, there is no problem even if the structure is divided into multiple layers in the thickness direction. In this experiment, 1.2
The d=1.91 cm was obtained by stacking two ceramic discs of 7 cm and 0.64 cm.

[0040] The method of heating a cylindrical substrate in the present invention is as follows:
Any heating element with vacuum specifications may be used. Specifically, electric resistance heating elements such as sheathed wrap heaters, plate heaters, ceramic heaters, heat radiation lamp heating elements such as halogen lamps and infrared lamps, and liquid heating elements. , a heating element using a heat exchange means using gas or the like as a heating medium, and the like. As the surface material of the heating means, metals such as stainless steel, nickel, aluminum, and copper, ceramics, heat-resistant polymer resins, and the like can be used. In addition, other methods may also be used, such as providing a heating-only container in addition to the reaction container and, after heating, transporting gas into the reaction container in a vacuum. Furthermore, in combination with these means or alone, it is also possible to control the substrate temperature by the microwave itself used for discharge (for example, by changing the intensity as necessary).

In the present invention, the raw material gas for the deposited film is as follows:
For example, silane (SiH4), disilane (Si2H6)
raw material gas for forming amorphous silicon such as germane (
Examples include other functional deposited film forming raw material gases such as GeH4), methane (CH4), and mixed gases thereof.

Examples of the diluent gas include hydrogen (H2), argon (Ar), helium (He), and neon (Ne).

In addition, ammonia (NH3
), elements containing nitrogen atoms such as nitrogen (N2), oxygen (O2
), elements containing oxygen atoms such as nitrogen oxide (NO), dinitrogen oxide (N2O), methane (CH4), ethane (C2
H6), ethylene (C2H4), acetylene (C4H2
), hydrocarbons such as propane (C3H8), silicon tetrafluoride (
Fluorine compounds such as SiF4), disilicon hexafluoride (Si2F6), germanium tetrafluoride (GeF4), or a mixed gas thereof can also be used.

Furthermore, diborane (
B2H6), boron fluoride (BF3), phosphine (
The present invention is equally effective even if a dopant gas such as PH3) is simultaneously introduced into the discharge space.

In the present invention, the effect appeared in any range of the pressure value of the discharge space, but especially in the range of 100 mTorr or less,
Particularly good results were obtained with good reproducibility, preferably at 50 mTorr or less.

Materials for the cylindrical substrate used in the present invention include, for example, stainless steel, Al, Cr, Mo, Au,
Metals such as In, Nb, Te, V 2 , Ti, Pt, Pd, and Fe, alloys thereof, synthetic resins such as polycarbonate whose surfaces have been subjected to conductive treatment, glass, ceramics, paper, and the like are usually used in the present invention. There is no particular limit to the diameter of the cylindrical base, but in practice it is 20 m.
The length is preferably 10 mm or more and 1000 mm or less.

Further, the distance between the cylindrical substrates of the present invention is preferably 1 mm or more and 50 mm or less in order to stably maintain the discharge space. Further, the number of cylindrical substrates may be any number as long as a discharge space can be formed, but three or more, more preferably four or more is suitable.

[0048] Next, the microwave introduction window of the present invention will be explained in detail with reference to examples. A microwave plasma CVD apparatus, which is a deposited film forming apparatus by MW-PCVD, includes the structure of the microwave introduction window of the present invention. is not limited in any way by this.

FIGS. 1A and 1B are a partial vertical cross-sectional view along the axis of an embodiment of the microwave plasma CVD apparatus of the present invention, a cross-sectional view taken along the line X--X, and FIG. ), (
B) shows the waveguide 103 and introduction window 102 shown in FIG. 1(A).
FIG. 2 is a perspective view of a waveguide and an introduction window corresponding to FIG.

In the embodiment of the present invention, FIGS. 2(A) and 2(B)
and microwave plasma C shown in Figures 1(A) and (B).
The alumina of the present invention was introduced as a window material using a VD device.
Using a zirconia-based composite material, the introduced window material was evaluated based on the conditions for producing an electrophotographic photosensitive drum.

[0051] Furthermore, the microwave plasma CVD apparatus of the present invention shown in FIGS. An example of the procedure for forming a deposited film is shown below.

First, the reaction vessel 101 is evacuated by a vacuum pump (not shown) through the exhaust pipe 104, and the pressure inside the reaction vessel 101 is adjusted to 1×10 -7 Torr or less. Then, the heater 107 heats the cylindrical base 105.
heating and maintaining the temperature at the optimum temperature. Therefore, for example, if an amorphous silicon deposited film is to be produced, a raw material gas such as silane is introduced from the raw material gas inlet 109 and discharged from the raw material gas inlet 108 into the discharge space 106 . At the same time, a microwave power source (not shown) generates microwaves with a frequency of 2.45 GHz, and the microwaves are introduced into the reaction vessel 101 through a waveguide 103 and an inlet window 102 of the present invention shown by diagonal lines in the figure. to be introduced within. Thus, the discharge space 1 surrounded by the cylindrical base 105
At step 06, the source gas is excited and dissociated by microwave energy, and a deposited film is formed on the surface of the cylindrical substrate 105. At this time, the rotating shaft 110 is rotated by the motor 111, and the cylindrical substrate 105 is rotated around the central axis in the direction of the substrate's generatrix, thereby forming a deposited film uniformly over the entire circumference of the cylindrical substrate 105. It turns out.

Examples and comparative examples conducted by the present inventors will be described below. Example 1 The introduction window of the present invention (alumina/
Zirconia = 80/20) was installed in the microwave plasma CVD apparatus shown in FIGS. 1(A) and 1(B), and an amorphous silicon photosensitive drum having a three-layer structure was produced under the conditions shown in Table 6. The electrophotographic characteristics of the amorphous silicon photosensitive drum thus produced were evaluated as follows.

[0054]

[Table 7] The produced photosensitive drum was placed in an experimental copying machine, and an image was produced on transfer paper by a normal copying process. However, at this time, a voltage of 6 KV was applied to the charger to perform charging. Image defects: Evaluation was made based on the number of white spots within the same area of an image sample obtained when a black original was placed on a document table and copied. Further, the same evaluation was performed on six drums obtained in one deposition film production, and the following judgment was made for the worst drum among them.

0055 ◎… Good.

○　…　There are some small white spots.

[0057] △...There are white spots on the entire surface, but there is no problem in character recognition.

[0058] ×... The more difficult the characters are to read, the more white dots there are. Charging performance unevenness: An aluminum cylinder on which a deposited film has been formed is installed in a copying machine, and while the drum is rotating, the surface potential of the drum under a constant charge amount is measured at the developing unit position. The surface potential was measured every 3 cm from the top to the bottom of the drum, and the average thereof was taken as the charging capacity. Then, the value farthest from the average value for one drum was determined, and this value was defined as the chargeability unevenness. The same evaluation was performed on the six drums obtained in one deposition film formation, and the following judgment was made for the drum with the largest chargeability unevenness.

◎...The voltage was 10 V or less, and the uniformity was very excellent.

○... 20V or less and excellent uniformity.

[0061] △... 30V or less, causing no practical problems.

[0062] ×...The voltage is 30 V or more, which is insufficient when used in a high-speed copying device with very high image quality. Sensitivity unevenness: The drum was charged in the same manner as above, and the surface potential was measured every 3 cm from the top to the bottom of one drum under a constant exposure amount, and the average value was taken as the sensitivity. Similarly, among these values, the value farthest from the average value was defined as the sensitivity unevenness. And 6 obtained by one-time deposited film fabrication
The same evaluation was performed on book drums, and the one with the largest sensitivity unevenness was judged as follows.

[0063] ◎... It is 3 V or less and has very excellent uniformity.

○... 6 V or less and excellent uniformity.

[0065] △... It is 10V or less, and there is no problem at all in practice.

[0066] ×... It is 10V or more, and there is a risk that the quality will deteriorate under severe conditions such as high temperature and high humidity, and low temperature and poor quality. Thin line reproducibility: An image sample obtained when copying a normal manuscript consisting of full-page text on a white background was placed on a document table, and an image sample obtained was observed to evaluate whether the thin lines on the image were connected without interruption. However, if there was unevenness on the image at this time, the entire image area was evaluated and the results for the worst part were shown. Further, the same evaluation was performed on six drums obtained in one deposition film production, and the following judgment was made for the worst drum among them.

0067 ◎… Good.

○　　…　There are some interruptions.

△...There are many breaks, but it can be recognized as characters.

×... Some characters cannot be recognized as characters. White background fog: An ordinary image sample consisting of full-page characters on a white background was placed on a manuscript table, and the resulting image sample was observed and the fog on the white background was evaluated. Further, the same evaluation was performed on six drums obtained in one deposition film production, and the following judgment was made for the worst drum among them.

0071 ◎… Good.

○　…　There is a slight fog in some parts.

[0073] △: There is a fog over the entire surface, but there is no problem with character recognition.

[0074]×: There is fog to the extent that the characters are difficult to read. Image unevenness: An image sample obtained when copying a full-page halftone original was placed on a document table and the image sample obtained was observed to evaluate the unevenness of shading. Further, the same evaluation was performed on six drums obtained in one deposition film production, and the following judgment was made for the worst drum among them.

0075 ◎… Good.

○　…　There is a slight difference in shading in some parts.

[0077] △... There is a difference in shading over the entire surface, but there is no problem in character recognition.

×... The characters are so uneven that they are difficult to read.

The results are shown in Table 7. Comparative Example 1 A conventional introduction window A other than the present invention manufactured with the composition shown in Table 9 was installed in the microwave plasma CVD apparatus shown in FIGS. 4(A) and 4(B), and the same experiment as in Example 1 was conducted. A similar evaluation was conducted.

The results are shown in Table 7 together with the results of Example 1. Comparative Example 2 A conventional introduction window B other than the present invention manufactured with the composition shown in Table 9 was installed in the microwave plasma CVD apparatus shown in FIGS. 4(A) and 4(B), and an experiment similar to Example 1 was conducted. A similar evaluation was conducted.

The results are shown in Table 7 together with the results of Example 1 and Comparative Example 1.

[0082]

[Table 8] Comparative Example 3 A conventional introduction window C other than the present invention manufactured with the composition shown in Table 9 was installed in the microwave plasma CVD apparatus shown in FIGS. An experiment was conducted and similar evaluations were made.

The results are shown in Table 7 together with the results of Example 1 and Comparative Examples 1 and 2. Example 2 The introduction window of the present invention shown in FIG. 2 (alumina/zirconia = 8
0/20 ) was installed in the microwave plasma CVD apparatus shown in FIGS. 1(A) and 1(B), and an amorphous silicon photosensitive drum was produced under the same conditions as in Example 1. After the film formation, the introduction window and the cylindrical substrate were taken out from the reaction vessel, and the deposited film deposited on the reaction vessel side of the introduction window was subjected to alkali etching under the same conditions as in Experimental Example 2, and then removed by sandblasting. This operation of film formation and deposited film removal was repeated 50 times, and the photosensitive drums obtained by each film formation were evaluated in the same manner as in Example 1. The results are shown in Table 8-1.

[0084]

[Table 9] Comparative Example 4 A conventional introduction window A other than the present invention manufactured with the composition shown in Table 9 was installed in the microwave plasma CVD apparatus shown in FIGS. We conducted an experiment and made similar evaluations.

The results are shown in Table 8-2.

[0086]

[Table 10] Comparative Example 5 A conventional introduction window B other than the present invention manufactured with the composition shown in Table 9 was installed in the microwave plasma CVD apparatus shown in FIGS. We conducted an experiment and made similar evaluations.

The results are shown in Table 8-3.

[0088]

[Table 11] Note: [-] in the table means that the introduction window was broken during film formation. Comparative Example 6 A conventional introduction window C other than the present invention manufactured with the composition shown in Table 9 was installed in the microwave plasma CVD apparatus shown in FIGS. 4(A) and (B), and the same experiment as in Example 2 was conducted. A similar evaluation was conducted.

The results are shown in Table 8-4.

[0090]

[Table 12]

[0091]

[Table 13] As shown in Tables 8-1 to 8-4, when the number of operations for film formation/removal of deposited films is relatively small, the products can be manufactured using the conventional introduction windows B and C shown in Table 9 as well as the introduction window of the present invention. It is possible to manufacture high-quality amorphous silicon drums that meet the standards of However, as the number of repetitions of this operation increases, conventional introduction windows suffer from an increase in image defects due to film peeling from the window, and melting or destruction of the introduction window itself. In contrast, the introduction window of the present invention can maintain its function for a long period of time even after repeated use of film formation/deposited film removal. In this way, the microwave introduction window of the present invention is
It can be seen that even if the number of repetitions of film formation/removal of deposited films increases, the produced photosensitive drums can still produce very good results in terms of image quality. Embodiment 3 FIGS. 2(A) and 2(B) are a perspective view of a microwave introduction part including the waveguide 103 and introduction window 102 shown in FIGS. 1(A) and 1(B), and a perspective view of the introduction window.

The introduction window of the present invention shown in FIGS. 2(A) and 2(B) and the conventional introduction window A other than the present invention manufactured with the composition shown in Table 9
, B, and C in Figures 1(A), (B), and Figure 4(A), respectively.
) and (B), and an amorphous silicon photosensitive drum having a four-layer structure was produced under the conditions shown in Table 10. When the electrophotographic characteristics of the amorphous silicon photosensitive drum thus produced were evaluated in the same manner as in Example 1, the results were exactly the same as in Example 2 and Comparative Examples 4, 5, and 6.

[0093]

Table 14 Example 4 FIG. 3 is a cross-sectional view of the mounting portion of the introduction window shown in FIGS. 2(A) and 2(B).

In FIG. 3, the microwave 300 is guided from the waveguide 306 and enters the reaction vessel through the introduction window 302 of the present invention and the introduction window 301 of the present invention, and the introduction window 302 is connected to the outer waveguide 305. O-ring 3 at the tip
04 and is pressed by the inner waveguide 306 , and the introduction window 301 is held by the tip of the waveguide 305 and the window holder 303 .

In the experiments of Examples 1 and 2, the introduction window was divided into two layers in the thickness direction as described above, but as shown in FIG. 3, the introduction window on the waveguide side 3
02 was made of a conventional material, and only the introduction window 301 on the side of the reaction vessel exposed to plasma was made of the material of the present invention. As a result, similar experiments as in Examples 1 and 2 were conducted. The results were obtained. Example 5 SiO2, MgO, CaO in the introduction window of the present invention
When examining the influence of impurities such as, the content of impurities was 10
If it is within %, the alumina/zirconia composition ratio is 90/
As in Example 2, good results were obtained within the range of 10 to 60/40.

[0096]

Effects of the Invention As explained above, the present invention has an introduction window that contains ZrO2 in the range of 1% to 90% and other components are alumina-zirconia composite ceramics. / Even under harsh usage conditions with repeated removal of deposited films, it is possible to consistently produce deposited films with uniform film quality that satisfies the requirements for various optical and electrical properties, and with very few defects at a high yield (high yield). ) Moreover, it can be manufactured at a very low cost, and its characteristics can be maintained for a long period of time compared to conventional introduction windows even when used repeatedly under harsh conditions of film formation and deposited film removal. Furthermore, it is possible to create a deposited film that maintains excellent electrophotographic properties even when charging conditions are poor, such as high temperature and high humidity, or when developing conditions are poor, such as low temperature and low quality.

[Brief explanation of drawings]

[Fig. 1] (A) and (B) are partial longitudinal cross-sectional views along the axis of the microwave plasma CVD apparatus of the present invention, and its X-X
FIG.

FIGS. 2A and 2B show the waveguide 103 shown in FIG.
Introduction window 102 is a perspective view of a corresponding waveguide and an introduction window.

FIG. 3 is a sectional view of the mounting portion of the introduction window shown in FIG. 2;

FIGS. 4A and 4B are a partial vertical cross-sectional view along the axis of a conventional microwave plasma CVD apparatus, and a cross-sectional view taken along the XX section thereof.

[Explanation of symbols]

101 Reaction vessel 102, 203 Introduction window 103 Waveguide 104 Exhaust pipe 105 Cylindrical substrate 106 Discharge space 107 Substrate heating heater 108, 109 Raw material gas introduction tube 110
Rotating shaft 111 Motors 200, 300 Microwave 201 Rectangular waveguide 202 Circular waveguide 301 Reaction container side introduction window 302 Waveguide side introduction window 303 Window holder 304 O-ring 305 Waveguide 306 Waveguide

Claims (1)

[Claims] 1. A means for generating microwave discharge plasma by arranging a substrate in a reaction vessel that can be substantially sealed, and introducing microwaves into a discharge space in contact with the substrate through a microwave introduction window; Microwave plasma C having means for supplying raw material gas and means for evacuating the inside of the reaction vessel
Microwave plasma CV to form deposited film by VD method
In device D, the microwave introduction window is made of Al2O3
and ZrO2, of which Zr is partially stabilized or stabilized with a stabilizer.
A microwave plasma CVD apparatus comprising an alumina-zirconia composite ceramic containing O2 in a composition ratio of 1% or more and 90% or less, the other component being substantially α-alumina.