JPH02107776A - Thin film forming equipment - Google Patents

Abstract

PURPOSE:To form a good-quality film and also to miniaturize a vacuum vessel for film formation by constituting a cylindrical dummy provided coaxially with a cylindrical substrate to be subjected to film formation so that the length of the cylindrical dummy in an axial direction is made variable. CONSTITUTION:A cylindrical substrate 100 and a cylindrical dummy 102 which is capable of extension and contraction in an axial direction are coaxially and concentrically held into a state capable of vertical motion and rotary motion in a vacuum chamber 61 having vacuum pumps 65-68. A gas of H2, etc., introduced into a plasma production part 73 around the above dummy 102 is formed into plasmic state by means of microwaves introduced via waveguide pipe 76 and windows 77, which is confined by means of magnets 78. The resulting H radicals are introduced into a film-forming part 71 in the lower part to decompose gaseous raw material, such as SiH4, introduced into the part 71. Subsequently, the substrate 100 on a supporting stand 62 is raised to the position of the above film-forming part 71 while contracting the dummy 102 and is allowed to perform a vertical motion and a rotary motion, by which an a-Si film, etc., are uniformly formed on the above substrate 100. By this method, a good-quality film free from plasma damage can be obtained, and further, an increase in the size of the vacuum vessel 61 can be prevented and the miniaturization of equipment can be attained.

Description

[Detailed Description of the Invention] [Summary] Regarding a thin film forming apparatus used for manufacturing photoreceptors for electrophotography, etc., it is possible to form a high quality film in a clean state, and moreover, it is possible to form a thin film in a vacuum container. With the aim of realizing miniaturization, we have developed a vacuum vessel in which a cylindrical substrate on which a film is to be formed and a cylindrical dummy are housed concentrically with their axes aligned, and a plasma generating section around the dummy in which plasma is generated. a first means for supplying generation gas and microwaves; a second means for confining the plasma-formed gas in the plasma generation section; and supplying raw material gas to a film forming section around the base. and third means, and the length of the dummy in the axial direction is variable.

[Industrial application field]

The present invention relates to a thin film forming apparatus used for manufacturing electrophotographic photoreceptors.

The surface of the photoreceptor, which has a photosensitive layer formed on a cylindrical substrate, is uniformly charged, and a laser beam or the like is selectively irradiated on the photoreceptor based on the printed information to selectively attenuate the charged potential of the photosensitive layer to form a latent image. Electrophotographic devices are well known in which the toner image is transferred and recorded onto recording paper after the toner image is developed. Photosensitive materials having a photosensitive layer of an a-3i film with high optical strength have come to be used.

[Conventional technology]

Conventionally, the formation of an a-5i film on a large-area cylindrical substrate such as this electrophotographic photoreceptor has been carried out by high-frequency plasma CVD or microwave plasma CVD.
For example, the apparatus and film-forming process for that purpose are disclosed in Japanese Patent Application No. 1877-1875 filed by the present applicant on July 29, 1988.
It is disclosed in No. 10. These are explained as follows with reference to Fig. 5.6.

Figure 5 shows conventional high frequency plasma CVD for forming a-3i film.
This is an explanatory diagram of the structure of the device, and in the figure, 100 is a cylindrical base (aluminum drum). a to the surface of this base 100
The formation of the -5i film is performed as follows.

First, as shown in the figure, a base 100 is set in a vacuum container 1 supported by a support 2, and after the inside of the vacuum container 1 is evacuated to a predetermined degree of vacuum using a rotary pump 3 and an oil diffusion pump 4, a mechanical booster is used. Switch to pump 5 and rotary pump 6. Simultaneously with the start of exhaust, the base 100 is rotated by being driven by the rotation mechanism 7 via the support base 2. When the degree of vacuum reaches a predetermined value, the base 100 is heated to 150
Heated to ~350°C. 9 is a vacuum valve provided in each pump system. On the other hand, a reactive gas is introduced into the vacuum container 1 by a 5iJ6 cylinder 10 or the like via a gas flow rate regulator 11 or the like. Then, a glow discharge is generated between the discharge electrode 12 and the substrate 100 at a predetermined flow rate and pressure to decompose the introduced gas 4, thereby depositing an aSi film on the substrate 100. 14 is a valve provided in the reactive gas supply system.

Moreover, FIG. 6 is a structural explanatory diagram of a conventional microwave plasma CVD apparatus for forming a-3i film (FIG. 6(a) is a plan view of the main part, and FIG. 6fbl is a front view showing the overall outline). In the figure,
31 is a vacuum container. When forming the a-5i film, first, the substrate 100 is supported and set on the support stand 32 in the vacuum container 31, and the inside of the vacuum container 31 is evacuated via the valve 33 using a vacuum pump or the like until a predetermined degree of vacuum is reached. do. Next, the base body 100 is rotated together with the support base 32 by the motor 34, and the base body 100 is rotated from 150 to 150 degrees by the heater 35.
Heat to 350°C. Here, a silicon atom-containing gas, which is a raw material gas, is introduced into the vacuum container 31 through the valve 37, and the microwave generated by the microwave type a38 is guided through the waveguide 39, and the microwave is guided through the quartz glass window 40 into the vacuum container 31. 31 (formed between the vacuum vessel 31 and the base 100 to constitute a coaxial cavity resonator) 41 and caused to resonate. At the same time as this microwave introduction, Magneso 1-42.4
A current with a predetermined waveform is passed through 2' to generate a magnetic field to confine plasma near the base. As a result, the introduced gas is efficiently decomposed and an a-3i film is formed on the substrate 100.

[Problem to be solved by the invention]

However, when forming a film using the high frequency plasma CVD apparatus shown in Fig. 5, the film forming rate is generally about 3 to 5 μm/hour, so it is difficult to form a photosensitive layer that requires a film thickness of about 10 to 50 μm. It took 2 to 10 hours. In addition, unless the gas pressure during film formation is set to a relatively high value of about several torr,
If a film formation rate of μm/hour is not obtained and film formation is performed at such a gas pressure, a large amount of powdery material containing Si atoms will be generated in the vacuum container 1 during film formation, contaminating the inside of the container. Therefore, it was necessary to remove this powdery substance after film formation. Furthermore, the adhesion of powdery substances onto the substrate 100 causes defects such as pinholes in the formed film, which also causes a decrease in yield.

On the other hand, when forming a film using the microwave CVD apparatus shown in Fig. 6, it is possible to form a film at a low gas pressure of about 10-4 to 10 torr, so no powdery substances are generated.
There is almost no need to clean the inside of the device, which was required in the case of FIG. 5. Furthermore, there are of course no defects such as pinholes, which are a problem in the case of FIG. 5, and a very high yield can be obtained. However, in this method, the film is formed in plasma, which tends to cause plasma damage to the film, resulting in frequent deterioration of film quality.Furthermore, since the raw material gas is decomposed near the microwave introduction window, There was a problem in that the a-Si film adhered, making it difficult to introduce microwaves.

In order to solve these problems, a dummy is placed coaxially with the substrate, plasma is generated in this area, and it is confined by a magnetic field.The atoms activated here move around the substrate and cause this. The present applicant has disclosed a method of forming an a-5i film on the surface of a substrate by reacting with a source gas supplied to the substrate (Japanese Patent Application No. 63-233668, filing date:
(September 20, 1988). Fig. 7 is a structural explanatory diagram of a microwave CVD apparatus for forming an amorphous silicon film using a dummy to which this method is applied (Fig. 7 (al is a plan view of the main part, Fig. 7 fb) is a front view showing the overall outline). , in the figure, 51 is a vacuum container, 52 is a waveguide that guides microwaves,
Reference numeral 53 indicates a magnet, and reference numeral 54 indicates a ring-shaped raw material gas introduction pipe provided with a large number of ejection ports.

During film formation, a dummy 101 is placed coaxially with the base 100, which is placed with its axis aligned with the vacuum container 51, and a plasma generating section 57 around the dummy 101 in the vacuum container 51 is placed. Hz for plasma generation, Ar
A microwave is introduced through the window 56 of the waveguide 52, and a magnetic field (dotted arrow line) is applied to the plasma generation section 57 by the magnet 53 to turn the gas into plasma and generate the plasma. Confined in section 57.

The radicals of the gas elements activated by the plasma and moving downward in the figure and the base 1 in the vacuum container 51
A film is formed on the substrate 100 by reacting with the silicon atom-containing raw material gas supplied to the film forming section 55 around 00. By adopting this method, the above-mentioned problems can be solved.

However, in this method, the dummy 101 coaxial with the base 100 is about twice as long as the base 100, and the dummy 101
1 is moved up and down as shown in FIG. 8 during film formation.
It is necessary to increase the height of the vacuum container 51, leading to an increase in the size of the vacuum container 51. FIG. 8(a) shows the base 100
FIG. 8(b) shows the time when the base body 100 is lowered, and FIG. 8(b) shows the time when the base body 100 is raised.

Furthermore, since the dummy 101 is long, it is difficult to transport the base 100 in an in-line manner.

SUMMARY OF THE INVENTION An object of the present invention is to provide a thin film forming apparatus that can form a high-quality film in a clean state and also realize a smaller vacuum container.

[Means to solve the problem]

FIG. 1 is an explanatory diagram of the principle of the present invention, in which 61 is a vacuum container, 62 is a support stand that holds a base 100, and 102 is a base 1
This is a dummy placed coaxially with 00.

The dummy 102 has a variable length in the axial direction.

Specifically, the dummy 102 is constructed by telescopically fitting a plurality of cylinders formed of, for example, SUS mesh or the like and having sequentially different diameters in a telescopic manner.

Plasma generation gas and microwaves are supplied to the plasma generation section 73 around the dummy 102 by a first means (not shown) consisting of a plasma generation gas supply source and a microwave supply source. It has become. Further, in order to confine the plasma generated in the plasma generation section 73 in this part, a second means (not shown) such as a magnet is provided at a position facing the plasma generation section 73 outside the vacuum container 61. There is. Further, the film forming section 71 around the base 100 is provided with a third means (not shown) for supplying source gas.

[For production]

Film formation is performed in the same manner as in the past, but when the base 100 is moved up and down during film formation, the dummy 102, which can be freely expanded and contracted in the length direction, becomes elongated as shown in Fig. 1 (al) and Fig. 1 fbl. This operation can be realized, for example, by hooking and holding the tip of the dummy 102 on a dummy support rod (not shown).In this way, the substrate can be moved without providing any space above the vacuum container 61. 100 can be moved up and down sufficiently to perform uniform film formation, and the vacuum container 61 can be downsized.

Further, when transporting the base body 100, the dummy 102 can be shortened as shown in FIG. 1 (C1), and in-line operation can be realized.

〔Example〕

The present invention will now be described in detail with reference to FIGS. 2 to 4.

FIG. 2 is a structural explanatory diagram of a thin film forming apparatus (a-5i film forming microwave CVD apparatus W) according to the present invention, and in the figure, 61
62. and 102 the aforementioned vacuum container.

The support stand and the dummy 63 are heater power sources for heating the substrate;
64. is a cylinder containing 5iHn (raw material gas), 6
4□ is a cylinder that stores BzL gas for boron dope,
643 is a cylinder that stores 11□ (or Ar). As shown in FIG. 3, the dummy 102 consists of n cylinders 103.
．． 1032.・,103. ,.

103o telescopically fitted telescopically and coaxially connected to the upper end of the base 100 via a cylindrical connection part 104 made of non-metallic SUS. The cylinder 103 at the top of this dummy 102. .

The upper end is supported in a suspended state by the support part 105A of the dummy support rod 105, and the dummy 102 expands and contracts due to the vertical movement of the base 100, so that the upper end surface remains at a fixed position.

As a result, the proportion of the dummy 102 in the vacuum container 61 is reduced, making the vacuum container 61 smaller (approximately 3/4 of the conventional size).
height) was achieved.

Formation of an a-Si film using this apparatus is performed as follows.

First, the base 100. With the dummy 102 set in the vacuum container 61, the vacuum container 61 is evacuated to a predetermined degree of vacuum using the rotary pump 65 and the oil diffusion pump 66, and then the mechanical booster pump 67 and the rotary pump 68 are switched over.

At the same time as the exhaust starts, the support stand 6 is moved by a rotating mechanism (not shown).
2, the substrate 100. Dummy 102 rotates. When the degree of vacuum reaches a predetermined value, the base 100 is heated from the inside by a heater 69 connected to a heater power source 63.
Heated to 50°C. 70 is a vacuum valve provided in each pump system. On the other hand, a reactive raw material gas is introduced into the film forming section 71 in the vacuum container 61 via a gas flow rate regulator 72 or the like from the cylinder 648, and into the plasma generating section 73 from the cylinder 643 11□ (or Ar) gas is introduced via a gas flow rate regulator 74 or the like. Reference numeral 75 indicates pulp provided in each of these gas introduction systems. Then, microwaves are introduced into the plasma generation section 73 from the waveguide 76 through the window 77 under a predetermined flow rate and pressure, and a current with a predetermined waveform is supplied to the magnet 78. The gas pressure at this time is 10-
The pressure is 4 to 10 torr, because the dummy 102 is placed coaxially with the vacuum vessel 61 to form a coaxial cavity resonator, and the magnetic field generated by energizing the magnet 78 is applied. , a stable plasma is generated. This plasma is confined within the shaded area in the figure by the magnetic field. The hydrogen radicals activated by this plasma move to the film forming section 71 in the lower part of the figure where plasma is not generated, where they react with the source gas ejected from the ejection port of the introduction pipe 79.

As a result, the raw material gas is efficiently decomposed and the base material 100 is
An a-Si film is formed on top.

During this film formation, the substrate 100 is given vertical movement in addition to the above-mentioned rotation, thereby achieving uniform film formation. -1
02 expands and contracts with the upper end positioned at a fixed position.

In this film formation, since the plasma generation place and the place where the source gas is decomposed and the film is formed are separated, there is no decomposition of the source gas near the microwave introduction window 77.
Film adhesion can be eliminated.

Furthermore, film formation can be achieved without plasma damage. Furthermore, this film formation is performed using plasma CV using microwaves.
Since this is the D method and film formation can be performed at low pressure, a high-quality a-5i film can be formed in a clean state, and cleaning inside the vacuum container 61 is not necessary.

Note that during film formation, the introduction tube 79 may be moved up and down together with the base 100.

Examples of setting various conditions during the a-Si film formation performed in this manner are as follows.

Setting example ■ Introduced gas Substrate rotation speed Substrate top and bottom number Magnetic field Gas pressure Film forming speed Setting example ■ Introduced gas; From the top of the vacuum vessel 61, )1z 50SCCM From the inlet pipe 79, 5i) I4.5 Q CCM Effective 100 Watts (Incidence) Power minus reflected power) 0PPM 10 times/min 875G (maximum point) 1,9 X 10-'torr 10μm/hour Microwave power; ; From the top of the vacuum vessel 61, Ar 30SCCM From the introduction pipe 79, 5iHt50 CCM Effective 100 Watts ; IORPM ; 10 times/min microwave power ; Substrate rotation speed Number of upper and lower parts of the substrate Magnetic field ; 875G (maximum point) Gas pressure
;1. OX 10-3torr film formation rate
; 11μm/hour setting example ■ Introducing gas from the top of the vacuum vessel 61 into l instead of 112
ie, the rest is the same as in setting example
3. ．． ..., 103. ,．． 103. , it is possible to reduce the size of the dummy 102 as shown in FIG. This made it possible to transport substrates from the film forming section to other rooms, which was necessary for in-line processing.

In this example, each cylinder constituting the dummy is made of SUS mesh, so the dummy is lightweight and easy to rotate during film formation and transport after film formation, and the dummy can be reused ( It can be regenerated by treatment with nitric acid).

In addition, the above-mentioned 1. Second. In this example, the third means is as follows.

First means: Consists of a cylinder 643, a piping system that guides the gas in the cylinder 643 to the plasma chamber 73, a microwave power source, and a piping system that guides the microwaves generated by the power source to the plasma chamber 13. Ru.

Second means: consists of magnetomet 78.

Third means; to Bonn 64. ．． 64□ and a piping system that guides the gas in these cylinders to the film forming chamber 71.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to achieve the following various excellent effects.

(1) Since the plasma generation area is separated from the place where the source gas is decomposed and the film is formed, there is no decomposition of the source gas near the microwave introduction window, and it is possible to eliminate the adhesion of the film to the window. . Furthermore, film formation without plasma damage is realized.

(2) Since plasma CVD using microwaves is performed in one place, and film formation can be performed at low pressure, a high-quality film can be formed in a clean state, and there is no need to clean the inside of a vacuum container.

(3) Since the dummy is provided so as to be expandable and retractable, the space occupied by the dummy in the vacuum container is reduced, allowing the vacuum container to be made smaller. Also, inline processing becomes possible.

[Brief explanation of the drawing]

Figures 1 (a), (b), and (C) are diagrams explaining the principle of the present invention, Figure 2 is a diagram explaining the structure of a thin film forming apparatus according to an embodiment of the present invention, and Figure 3 is the same, in an extended state of the dummy. FIG. 4 is a front view showing the reduced state of the dummy, FIG. 5 is a structural explanatory diagram of a conventional high-frequency plasma CVD apparatus for forming an amorphous silicon film, and FIG. Fig. 7(a) and (b) are structural explanatory diagrams of a microwave plasma CVD apparatus for forming an amorphous silicon film using a conventional dummy, and Fig. 8 ( al. (b) is an explanatory diagram of the vertical movement of the substrate and dummy during film formation by the apparatus shown in FIG. 7, in which 61 is a vacuum vessel, 71 is a film forming section, 73 is a plasma generation section, 100 is a substrate, 102 is a dummy.

Claims (1)

[Claims] A cylindrical substrate (100) on which a film is formed and a cylindrical dummy (100).
02) concentrically with their axes aligned; and a plasma generating section (73) around the dummy (102).
The first one supplies gas and microwaves for plasma generation to
means for converting the gas into plasma into the plasma generating section (73).
a second means for confining the substrate (100);
a third means for supplying raw material gas to a film forming section (71) around the dummy (102), and the length of the dummy (102) in the axial direction is variable. .