JPS62180074A - Formation of deposited film by plasma cvd method - Google Patents

Abstract

PURPOSE:To constantly form a deposited film having uniform film quality and film thickness and excellent optical, electrical and photoconductive characteristics by mixing and using >=2 kinds of diluting gases together with gaseous raw materials. CONSTITUTION:The diluting gases mixed with >=2 kinds are used together with the gaseous raw material for forming the deposited film in the stage of forming the deposited film by a plasma CVD method. A gaseous mixture composed of about 95-50vol% >=1 kinds selected from Ar, Kr and Xe and 5-50% >=1 kinds selected from H2, He and Ne is used as the diluting gas. The above- mentioned diluting gases and the gaseous raw materials are introduced into a deposition device and high-frequency or microwave energy is irradiated to the gaseous raw materials after the internal pressure is adjusted, by which the deposited film is formed on a substrate surface. >=2 Kinds of the gases which are easily electrically discharged and are hardly electrically discharged are mixed to form the diluting gases in the above-mentioned method and therefore, the formed deposited film has good quality. Desired characteristics are thus obtd.

Description

Detailed Description of the Invention [Technical Field to which the Invention Pertains] The present invention relates to a film deposited on a substrate, particularly a functional film, particularly a semiconductor device, a photosensitive device for electrophotography, a line sensor for image input, an imaging device, an optical The present invention relates to a method of forming a deposited film using a plasma CVD method, which is most suitable for forming an amorphous deposited film used in an electromotive force element or the like.

[Description of prior art and problems]

Conventionally, semiconductor devices, photosensitive devices for electrophotography,
Element members used for image input line sensors, imaging devices, photovoltaic elements, etc. are amorphous silicon, especially hydrogen atoms (I) and/or halogen atoms (
Amorphous silicon compensated with
It is written as Si (HjX)J. ] Membranes have been proposed, and some of these have been put into practical use. Along with this a-5i (H,X) film, a-5i (H
,
There are D method, plasma CVD method, photo-CVD method, etc. Among them, plasma CVD method is put into practical use as the most suitable method and is generally widely known.

The outline of the plasma CVD method is as follows: Raw material gas for forming a deposited film (for example, 5Lj1., Si box, SiF, etc.)
Alternatively, a plasma is generated in a mixture of the raw material gas and a diluent gas such as US gas, He gas, Ar gas, etc. using high frequency or microwave energy, and excited species, free radicals, A deposited film is formed on the surface of a substrate by a complex chemical action between chemically active species (radical species) such as ions or between radical species and source gas.

And such deposition IE by conventional plasma CVD method
+In the formation method-[, the formed film a-5L (H,
X) The film quality of the film may be different, or a-5i (H,
X) There is a problem that the films have different optical, electrical, or photoconductive properties.

That is, the deposited film forming method using the plasma CVD method described above generally uses Ar gas, Kr gas, xe gas as a diluent gas.
When using an inert gas such as gas, the a-
3i (H9x) is made to have good film quality, and when the deposited film is used as a photoreceptor strip for electrophotography, it is said to have excellent photographic properties. Even if the amount and film-forming conditions are strictly controlled, the powder deposited on the substrate surface is likely to become partially powdered depending on the direction of introduction and exhaust of the raw material gas, and the powder may be mixed into the deposited film. In this case, if the formed deposited film is used in a light-receiving member for electrophotography, a problem arises in that it causes image protection defects in the image. Also, H.

When using gas, He gas, etc. as a diluent gas,
Although there are advantages in that the formation rate of the deposited film is relatively fast, there are fewer problems with powder generation, and therefore the latitude of film formation is wider, the formed a-Si (H,
) The film is inferior to the above-mentioned case, and when the deposited film is used as a light-receiving layer for electrophotography, there is a problem that sufficient electrophotographic properties are not exhibited.

As described above, in the conventional plasma CVD method for forming deposited films, the quality of the a-8i (H, In addition to meeting the requirements of having excellent properties such as dark decay and low unevenness, we also met the requirements of having a wide film formation latitude with little or no powder formation on the substrate surface. The reality is that no diluent gas has been found that is suitable for dilution, and solving these problems is considered to be one of the most important issues, especially now that functional membranes are required to be diversified and have larger areas. A solution is desired.

[Purpose of the invention]

The present invention is based on the conventional plasma CVD method used to form deposited films used in photosensitive devices for electrophotography, semiconductor devices, line sensors for image processing, photodetection devices, photovoltaic devices, etc. The purpose of this method is to solve the above-mentioned problems regarding the deposited film forming method.

That is, the main object of the present invention is to provide a deposited film by plasma CVD method for regularly obtaining a deposited film having uniform film quality and thickness and excellent optical, electrical, and photoconductive properties. The object of the present invention is to provide a forming method.

Another object of the present invention is to widen the latitude of film formation, improve the productivity of deposited films, and enable mass production.
It is an object of the present invention to provide a method for forming a deposited film by plasma CVD, which allows the film to have a large area.

[Structure of the invention]

The inventors of the present invention have conducted extensive research in order to overcome the aforementioned problems with the conventional plasma CVD method for forming a deposited film and to achieve the above objectives. The present invention was completed based on the knowledge that it is possible to control the amount and energy of electrons in the discharge plasma by using the method, thereby solving the above-mentioned problems and achieving the above-mentioned objectives. .

Finding A: Depending on the type of gas used as the diluent gas, there are gases that are easy to discharge and gases that are difficult to discharge. The plasma conditions involved are different, which is why the film was formed. This is based on the fact that it has been found that the film quality and optical, electrical, photoconductive, etc. properties of the film differ.

That is, gases such as Ar gas, Kr gas, and Xe have relatively low ionization energy (for example, the ionization energy of each gas is 15.76 eV for Ar gas, 14.00 eV for Kr gas, 12.0 eV for Kr gas, and 12.0 eV for Xe gas. 13 eV), therefore, it is easy to discharge, and these diluent gases absorb most of the high frequency or microwave energy, resulting in fewer high-energy electrons in the generated plasma. , a-8t (H3
X) results in the formation of a deposited film, whereas the bird gas or tie gas has a relatively large ionization energy (e.g. the ionization energy of each gas is
He gas is 24.59 eV, tJe gas is 21.
It is 57 eV. ), therefore, most of the high frequency or microwave energy is
They are absorbed by raw materials such as lI4.5itl, SiF, etc., and the generated plasma contains many high-energy electrons, which are absorbed by SiL, S'i, SiF, etc.
a-Si(H
,X) Although the deposition rate of the film becomes faster, the formed a
-Si (H,X) W5. If the film quality is satisfactory, it will be 7yo.

Therefore, the present inventors continued their research and used a mixture of at least two different diluent gases, such as gases that are easy to discharge and gases that are difficult to discharge, and tried changing the mixing ratio of those gases. When two or more diluent gases are mixed in a specific proportion, a-5i ()l,
X) It was confirmed that the deposited film was consistently of good quality and had the desired characteristics.

The present invention was completed based on these findings,
The gist of this is that when forming a deposited film on the substrate surface by irradiating the material gas for forming a deposited film with high frequency or microwave energy, at least two types of diluent gases are mixed together with the material gas for forming the deposited film. The point is to use it.

The diluent gas is a mixture of at least one selected from the group consisting of H, gas, He gas, and Ne gas, and at least one selected from the group consisting of Ar gas, Kr gas, and Xe gas, Preferably H
, 5 to 50% by volume of at least -g< selected from the group consisting of , He gas, Ne gas, Ar gas, Kr gas,
A mixture of 95 to 50% by volume of at least one selected from the group consisting of gas and Xe gas is used.

The raw material gas used to form the deposited film according to the method of the present invention is one that can be excited by radio frequency or microwave energy and chemically interact with it to form the desired deposited film on the substrate surface. For example, a-5i (H,
X) When forming a film, specifically, silanes and halogenated silanes in which hydrogen, halogen, hydrocarbon, etc. are bonded to silicon, or those that can be easily gasified. A gasified product can be used. One type of these raw material gases may be used,
Alternatively, two or more types may be used in combination. Furthermore, a-8i
The (H, It can be mixed with a diluent gas and introduced into the reaction chamber.

The substrate may be conductive, semiconductive, or electrically insulating; specific examples include scrap metal, ceramics, glass, etc. . The temperature of the substrate during the film-forming operation is not particularly limited, but is generally in the range of 30 to 450°C, preferably 50 to 350°C.

In addition, when forming a deposited film, the pressure in the reaction chamber is set to 5 x 10''6 Torr or less, preferably 1 x 10'' Torr or less before introducing the source gas, and when the source gas is introduced, the pressure in the reaction chamber is 1 x 10-”-I
Torr, preferably 5 X 10-"~I T
It is preferable to use orr.

Incidentally, deposited film formation using the apparatus of the present invention is usually carried out by introducing the raw material gas into a reaction chamber without subjecting it to facet treatment (excitation speciation) as described above, and then applying high frequency or microwave energy there. This is done by creating excited speciation and causing chemical interaction; however, when using two or more types of raw material gases, it is also possible to make one of them into excited speciation in advance and then introduce it into the reaction chamber. It is possible.

〔Example〕

EXAMPLES Hereinafter, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited thereto.

FIG. 1 is a cross-sectional view schematically showing an example of an apparatus used in each embodiment to carry out the method of forming a deposited film by plasma CVD of the present invention.

In FIG. 1, 1 is a high frequency power supply, 2 is a matching box, 3 is a diffusion pump and a mechanical booster pump, 4 is a motor for rotating the base body, 5 is a base body, 6 is a heater for heating the base body, 7 is a gas core inlet tube, 8 is a cathode electric lamp for high-frequency insulation, 9 is a shield plate, 10 is a power source for a heater, 21 to 27
．． 41 to 47 are pulp, 31 to 37 are mass flow controllers, 51 to 57 are regulators, 61 is hydrogen (Hl
) gas cylinder, 61 is an argon (Ar) gas cylinder, 6
3 is a silane (Si&) gas cylinder, 64 is diborane (n
65 is a nitrogen oxide (NO) gas cylinder, 66 is a methane (CH4) gas cylinder, and 67 is an argon (Ar) gas cylinder.

Hereinafter, in each example, C-1 will be described in which a photoreceptor for electrophotography is formed using the apparatus shown in FIG. 1, but the application of the deposited film formed by the method of the present invention will be limited. It's not a thing.

In this example, a cylindrical Al support (
The length is 357 tnm, the diameter (r) is 80 ma),
On the AI support, a charge injection stop layer, a photosensitive layer and a surface layer were deposited as follows.

All main valves of cylinders 61 to 67 were closed, all mass flow controllers and pulps were opened, and the pressure inside the deposition apparatus was reduced to 10'' Torr using the diffusion pump 3. At the same time, the Al support 5 was heated to 250°C by the heater 6 and kept at a constant temperature of 250°C. A support temperature is 2
After reaching a constant temperature of 50°C, pulp 21~27.41~・
17. Close the cylinders 51 to 57, open the main valves of the cylinders 61 to 67, and replace the diffusion pump 3 with a mechanical booster pump. 1 secondary king of pulp with regulators 51 to 57
．． 5 Set to #l/ad, mass flow controller 3
1 to 5 O5CGH, pulp 41 and pulp 21
was opened to introduce H and gas into the sedimentary plate 1a. Next, Ar gas in the cylinder 62 was introduced into the deposition apparatus in the same manner as the introduction of Ht gas, with the mass flow controller 32 set at 2508 CCM.

Next, the 5it gas in the cylinder 63 was introduced into the deposition apparatus by setting the mass flow controller 32 to 1508 CCM, and the same procedure as for introducing the H gas was introduced into the deposition apparatus. Set the mass flow controller 34 so that the gas flow rate is 1600 ppffl of SiH4 gas flow, introduce B crystal Ganu in the same way as H gas, and finally set the gas flow rate of No gas in cylinder 65. ,
The mass flow controller 35 was set so that the flow rate was 3.4% of the SiH4 gas flow rate, and No gas was introduced in the same manner as the No gas.

At this point, the internal pressure inside the deposition apparatus is 0.2 Torr.
After adjusting the internal pressure as much as possible and stabilizing the internal pressure, turn on the high frequency power supply 1, adjust the matching box 2, and
A glow discharge was generated between the l support 5 and the cathode electrode 8, the high frequency power was set to 150 W, and an a-8i:O:H:8 layer (charge injection blocking layer) was deposited. After depositing 8 layers of a-Si:O:H with a thickness of 5 μm in this manner, the pulps 24 and 25 are closed without cutting off the discharge to stop the inflow of the B high gas and the No gas, thereby blocking the charge injection described above. ) In the same manner as in the case of forming Q, a-5i:Hf3 (photosensitive J3) was deposited 1
'fi L f:.

When the layer thickness of a-6i:H, fi reaches 20 μm, the discharge is cut off, the 7 pulps 21 and 22 are closed to stop the inflow of horse gas and Ar gas, and the mass flow controller 33
Change the setting to 35 SCCM, and also change the gas cylinder to 66 SCCM.
Since the cH4 gas flow is ε8iH, the ratio of gas flow rates is 5iH41
c) By opening the pulp 25, CH4 gas is introduced from the mass flow controller 36, which is set to close to 4=1/3 otonal, and the high frequency 'reaching power 15
7ffl of a-5iC(H) with 0.5 μm layer at 0 W
(Surface b> was deposited.

Finally, close the high frequency power supply 1 and the gas pulp,
The inside of the deposition apparatus was evacuated, the temperature of the A) support was lowered to room temperature, and the Al support on which the photoreceptive layer was formed was taken out.

The electrophotographic light-receiving member formed in this way was evaluated in terms of charging ability and image quality. The charging ability and 1. We evaluated and compared the cap elephant notes.

Regarding these evaluations, please refer to the Canon Digital Limited Edition N
This was done by measuring the charging ability and image quality under the same charging conditions using P9030. Charging 11 Suzu, the dark area surface potential when the corona voltage of -order charging is +7.5KV was measured at the position of the developing device, and the image ratio was calculated as follows: 29
Diameter 0.3 on top (7 m) = Image missing P over tac! (
This was determined by the number of occurrences (black circles on a white background or white circles on a black background).

As a result of the evaluation, it was found that the method of the present invention, that is, when a deposited film was formed using a mixed gas of lh gas and Ar gas as a diluent gas, the conventional method, that is, when only bird gas was used as a diluent gas, and It has been found that an electrophotographic light-receiving member with superior charging ability and almost no image defects can be obtained than when only Ar gas is used as the diluent gas.

Example 2 Mixing ratio of H gas and Ar gas used as diluent gas (A
except that r/H* + Ar) was changed from O to 1.
Electrophotographic light-receiving members were formed in the same manner as in Example 1, and for each of the obtained electrophotographic light-receiving members,
The chargeability and image quality were evaluated in the same manner as in Example 1. Figure 2 shows the results, where the axis represents Ar/H, +Ar, and the axis represents charging capacity (V/μ
) and 11 image defects. (−
indicates a change in both defects, and -o- indicates a change in charging ability.

As is clear from Figure 2, for band 8a Noh, Ar
25 V/ in the region of 100% to 53.5% gas
A good '5o% of more than μ was obtained. On the other hand, the image meter (
As for the difficulty, almost the same good l'u'K was obtained from Ar gas O% to 97.5%, but image defects due to film peeling and abnormal growth were noticeable from the region exceeding 97.5'6. Initially, it became impractical. Furthermore, the surface properties of the film gradually deteriorated.

As a result, the ratio of Ar gas is 97.5% to 53.5%.
It became clear that it was necessary to

Similar results were obtained when lie gas and Ne gas were used instead of H and gas.

Furthermore, similar results were obtained when Kr gas or xe gas was used instead of Ar gas.

Example 3 A long wavelength absorbing layer, a charge injection blocking layer, a photosensitive layer and a surface layer were formed on an Ad support by the same operation as in Example 1 to obtain a light receiving member for electrophotography.

Note that the raw material gas flow rate and layer thickness when forming each layer were set as shown in the table below.

The electrophotographic light-receiving member thus obtained was evaluated for charging ability and imageability in the same manner as in Example 1.
It was found that this is an electrophotographic light-receiving member with both charging ability and image quality of 1.

[Effect of invention: settled]

The deposition III forming method by the plasma CVD method of the present invention uses a mixture of Kanazawa gas of at least "Near" or higher with the raw material gas for deposited film formation, thereby improving the film quality of the deposited film formed, its optical, electrical, or It is possible to obtain a deposited film with good photoconductive properties, and since there is no powder generation period during film formation, the film formation latitude is widened, making it possible to improve productivity and enlarge the area. It is something that can be done.

[Brief explanation of drawings]

FIG. 1 is a schematic cross-sectional view schematically showing an example of an apparatus suitable for carrying out the method of forming a deposit 81 pA by plasma CVD according to the present invention. Figure 2 shows the diluent gas mixture ratio (Ar/
This is a diagram showing the change in charging ability and image quality when changing the amount of He + Ar), the vertical axis represents the charging ability and the number of image defects, and the horizontal axis represents the mixing ratio of diluent gas (Ar/15 +
Ar). About Figure 1 1...High frequency power supply, 2...Matching box 3.
・・Diffusion pump, mechanical booster pump, 4・・
- Motor for rotating the base body, 5... Base body, 6... Heater for heating the base body, 7... Gas introduction tube, 8... Cathode electrode for high frequency introduction, 9... Shield plate, 10... Power supply for heater, 21~27.41~47...pal 7",
31-37...mass flow controller, 51-57
...Regulator, 61-67...Gas cylinder Figure 2 Deposited film formation method 3, relationship with the amended case Patent applicant Address: 3-30-2 Shimomaruko, Ota-ku, Tokyo Name
(1001 Canon Co., Ltd. 4, agent address: Kojimachi Green Building, 3-12-6 Kojimachi, Chiyoda-ku, Tokyo)

Claims (3)

[Claims] (1) When forming a deposited film on the substrate surface by irradiating the raw material gas for forming a deposited film with high frequency or microwave energy, at least two types of diluent gases are mixed together with the raw material gas for forming a deposited film. 1. A method for forming a deposited film using a plasma CVD method, characterized in that the method is used in a plasma CVD method. (2) A patent claim in which the diluent gas used in a mixture is at least one selected from the group consisting of Ar gas, Kr gas, and Xe gas, and at least one selected from the group consisting of H_2 gas, He gas, and Ne gas. Range number (1)
A method for forming a deposited film using the plasma CVD method described in Section 1. (3) The method for forming a deposited film by the plasma CVD method according to claim (2), wherein the diluent gas to be mixed is a mixture of Ar gas and H_2 gas.