JP2553330B2 - Functional deposition film forming apparatus by plasma CVD - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a deposited film on a substrate, especially a functional film, particularly a semiconductor device, a photosensitive device for electrophotography, a line sensor for image input, and an imaging device. The present invention relates to an apparatus suitable for forming a non-single crystalline functional deposited film such as amorphous or polycrystalline used in devices, photovoltaic devices, etc. by a plasma CVD method.

[Description of Prior Art]

Conventionally, as an element member used for a semiconductor device, a photosensitive device for electrophotography, a licensor for image input, an imaging device, a photovoltaic device, etc., for example, an amorphous material containing silicon (hereinafter simply referred to as “a-Si”). write.)
A film or an amorphous (hereinafter simply referred to as "a-SiH") film containing silicon hydride has been proposed, and some of them have been put to practical use. And such a-
Several proposals have been made for a method for forming an a-Si film, an a-SiH film and the like as well as a Si film and an a-SiH film, and an apparatus for performing the same. A vacuum vapor deposition method, an ion plating method, so-called thermal CVD Method, plasma CVD method, optical CVD method, etc. Among them, the plasma CVD method is put to practical use as an optimum method and is generally widely used.

By the way, in the plasma CVD method, the deposited film forming gas is excited and seeded (radicalized) in the vicinity of the substrate surface by utilizing direct current, high frequency or microwave energy to cause a chemical interaction, and the substrate surface The method is to deposit a film on the substrate, and various devices have been proposed for that purpose.

FIG. 2 is a schematic cross-sectional view schematically showing a typical example of a conventional deposited film forming apparatus by the plasma CVD method, in which 1 is the whole cylindrical reaction vessel and 2 is the side wall of the reaction vessel. It also serves as a cathode electrode, 3 is the upper wall of the reaction vessel,
4 is a bottom wall of the reaction vessel. The cathode electrode 2, the upper wall 3 and the bottom wall 4 are insulated by an insulator 5, respectively.

Reference numeral 6 denotes a cylindrical substrate provided in the reaction vessel, and the cylindrical substrate 6 is grounded to serve as an anode electrode. A heater 7 for heating the substrate is provided in the cylindrical substrate 6 to heat the substrate to a set temperature before film formation,
It is used to maintain the substrate at a set temperature during film formation, or to perform an annealing process on the substrate after film formation.

Reference numeral 8 denotes a deposited film forming raw material gas introduction pipe, which is provided with a large number of gas release holes 9 for releasing the raw material gas in the reaction space, and the other end of the raw material gas introduction pipe 8 is provided with a valve 10
It communicates with the deposited film forming raw material gas supply system 20 via.

The source gas supply system 20 for forming a deposited film includes gas cylinders 201 to 2.
05, valves 211 to 215 provided on the gas cylinder, mass flow controllers 221-225, inflow valves 231-235 to the mass flow controller, outflow valves 241-245 from the mass flow controller, and pressure regulators 251-255. ing.

Reference numeral 11 denotes an exhaust pipe for evacuating the inside of the inner container, which communicates with a vacuum exhaust device (not shown) via an exhaust valve 12.

 Reference numeral 13 denotes a means for applying a voltage to the cathode electrode 2.

The operation of such a conventional deposited film forming apparatus by the plasma CVD method is performed as follows. That is, the gas in the reaction container is evacuated through the exhaust pipe 11, and the heating heater 7 heats and holds the cylindrical substrate 6 at a predetermined temperature. Next, for example, a-
In the case of forming a SiH deposited film, a raw material gas such as silane is introduced into the reaction vessel, and the raw material gas is discharged from the gas discharge hole 9 of the gas introduction pipe toward the surface of the substrate. Simultaneously with this, a high frequency, for example, is applied between the cathode electrode 2 and the base (assword electrode) 6 from the voltage applying means 13 to generate a plasma discharge. Thus, the raw material gas in the reaction vessel is excited to generate excited species, and radical particles such as Si ^* , SiH ^*, etc. (* represents an excited state), electrons, ion particles, etc. are generated, and these particles or between these particles are used. A deposited film is formed on the surface of the substrate by the chemical interaction between the particles of the above and the surface of the substrate.

By the way, in forming such a deposited film, it is known that the gas pressure of the source gas introduced into the reaction space, the gas flow rate, the discharge power, etc. affect the film quality and film thickness of the formed film. It has been proposed to rotate a cylindrical substrate to form a uniform deposited film.

However, when the cylindrical substrate is rotated to form the deposited film, there are the following problems.

That is, the thickness and characteristics of the deposited film formed by the eccentricity of the rotating shaft are likely to be non-uniform, it is difficult to electrically connect the cylindrical base and the rotating shaft, and the cylindrical base is rotated. Since it is necessary to provide a rotating mechanism for this, the cost of the device itself is high, and it is difficult to prevent leakage at the connection between the rotating shaft and the motor.Because the base is rotating, a temperature sensor is installed on the base itself. It was difficult to attach, but the temperature control of the substrate is likely to be inaccurate.

Further, in order to form a uniform deposited film, the source gas ejected from the source gas discharge hole 9 of the gas introduction pipe 8 into the reaction space and the distribution of the plasma discharge formed in the reaction space are important factors. However, in the conventional apparatus as shown in FIG. 2, since the raw material gas is introduced from one end of the raw material gas introduction pipe 8, the gas flow velocity is different between the upper part and the lower part of the reaction space, and the gas flow rate is different in the lower part on the exhaust side. The flow velocity becomes faster. Therefore, the radicals formed by the plasma discharge are more likely to escape to the outside of the system as the position approaches the lower part, and the efficiency of the plasma discharge is reduced. Further, the source gas for forming the deposited film is
A gas (hereinafter referred to as “deposition gas”) capable of forming a desired deposited film by chemical interaction with excited species by discharge energy, for example, SiH ₄ in the case of forming an a-SiH film. , Silane gas such as Si ₂ H ₆ is used,
These deposited film forming raw material gases are used after being diluted with a diluting gas such as H ₂ , He or Ar. In that case, in the conventional apparatus shown in FIG. In addition to the non-uniform intensity distribution of the plasma discharge, the mixing ratio of the deposition gas and the diluting gas also fluctuates, and especially in the lower part on the exhaust side, the diluting gas ratio becomes abnormally high. There is a problem that it will end up. And this problem when using H ₂ gas as a diluent gas,
This is particularly noticeable.

As described above, in the conventional apparatus, the plasma intensity distribution in the reaction space becomes non-uniform, and the formation of the deposited gas forming raw material gas becomes non-uniform in the system. There is a problem that the film thickness and film quality of the deposited film becomes uneven, and such a problem becomes more remarkable as the cylindrical substrate becomes longer.

For these reasons, although the plasma CVD method is considered to be the most suitable method, when forming a deposited film having a uniform film thickness and quality even on the upper and lower portions of the cylindrical substrate, the above-mentioned various methods are used. As a result, the film conditions are naturally limited, and as a result, various deposited films having a wide range of characteristics can be continuously formed in the same apparatus, or a multilayer structure having a plurality of deposited films having different characteristics on the same substrate can be deposited. It is very difficult to form films continuously in the same apparatus.

On the other hand, the above-mentioned various devices are diversifying,
As a device element for this purpose, it is a social requirement to form a deposited film having a wide variety of characteristics and, in some cases, to form a deposited layer having a large area. There is a strong demand for the development of devices that can be mass-produced.

[Object of the Invention]

The present invention solves the above-mentioned problems and solves the above-mentioned problems in a conventional device for forming a deposited film used in a photovoltaic device, a semiconductor device, an image input line sensor, an imaging device, an electrophotographic photosensitive device, and the like. The purpose is to satisfy.

That is, the main object of the present invention is to maintain a uniform deposition film with uniform film thickness and quality by keeping the distribution of the deposition film forming gas and its dilution ratio in the reaction space uniform without rotating the cylindrical substrate. Plasma that can be formed
It is to provide a deposited film forming apparatus by the CVD method.

Another object of the present invention is to improve various properties of a formed film, film forming speed, reproducibility, and uniformize and homogenize film quality, and at the same time, to improve productivity of the film and particularly mass production. At the same time, it is to provide a mass-produced apparatus for deposited films by the plasma CVD method, which makes it possible to increase the film area.

[Structure of Invention]

The inventors of the present invention have made extensive studies to overcome the above-mentioned problems of the conventional deposited film forming apparatus by the plasma CVD method and achieve the above-mentioned object, and as a result, even when the cylindrical substrate is not rotated. , Gas release hole 9 of gas introduction pipe 8
Angle, the shape factor of the gas introduction pipe 8 (for example, the inner diameter of the gas introduction pipe 8, the inner diameter of the gas release holes 9, the distance between the gas release holes, etc.) and the flow velocity of the gas released from the gas release holes 9. Then, it was found that the film thickness and the film quality uniformity of the obtained deposited film changed. That is, when the inner diameter of the gas introduction pipe and the flow velocity of the gas released from the gas release hole are constant, the deposition formed depends on the inner diameter of the gas release hole, the distance between the gas release holes, and the angle of the gas release hole. The film thickness and film quality become nonuniform in the generatrix direction and the circumferential direction of the cylindrical substrate, and when the deposited film formed on such a cylindrical substrate is used as an electrophotographic photoreceptor, the obtained image is However, it was found that there were many image defects in whole or in part.

Therefore, the present inventors have conducted further research based on this finding, and as a result, while arranging the gas discharge holes of the gas introduction pipe so as to have a specific angle [θ] with respect to the surface of the cylindrical substrate, When the inner diameter [d ₁ ] of the gas release hole and the interval [d ₂ ] between the gas release holes are set to specific values, and the introduction of gas is performed from one direction without rotating the cylindrical substrate. Even in that case, it was found that the uniformity of the film thickness and film quality of the deposited film formed is guaranteed.

The present invention has been completed based on this finding, and the deposited film forming apparatus by the plasma CVD method of the present invention has the following constitution. That is, a fixedly arranged cylindrical support on which a deposited film is formed is used as one electrode, and the other electrode is provided so as to face the electrode, and plasma is generated by discharge between the electrodes. A reaction container having a reaction space inside, a gas introduction pipe having a large number of gas discharge ports on a side wall for introducing a gas used for forming a deposited film in the reaction container, and exhausting the reaction space from a lower part In the functional deposited film forming apparatus by the plasma CVD method having a means for performing, the angle of the gas release hole with the cylindrical substrate surface is θ [rad], the inner diameter of the gas gas release hole is d ₁ [mm], the gas release hole Is ₂ mm, and the outer diameter of the cylindrical substrate is R ₁ [m
m], the distance between the center of the gas introduction pipe and the center of the cylindrical substrate is R
_{When the} thickness is ₂ [mm], the functional deposited film forming apparatus by the plasma CVD method is characterized by satisfying the following formulas I to III.

0.5 ≦ d ₁ ≦ 1.5 …… II 10 ≦ d ₂ ≦ 100 …… III The present invention will be described below with reference to the drawings.

FIG. 1 (A) is a cross-sectional view schematically showing the positional relationship between the gas release holes of the gas introduction pipe and the cylindrical substrate in the deposited film forming apparatus by the plasma CVD method of the present invention. B) is a side view of the gas introducing pipe. In the figure, 2 is a cathode electrode, 6 is a cylindrical substrate, 8 is a gas introduction tube, and 9 is a gas discharge hole. R ₁ [mm] is the outer diameter of the cylindrical substrate 6 and R ₂ [mm] is , The distance between the center of the cylindrical substrate 6 and the center of the gas introduction pipe 8, θ [rad] is the angle of the gas release hole with respect to the surface of the cylindrical substrate, d ₁ [mm] is the inner diameter of the gas release hole, d ₂
[Mm] represents the distance between the gas discharge holes. And R ₁ [mm], R ₂ [mm], θ [rad], d ₁ [mm] and d ₂
[Mm] satisfies the above formulas I, II and III.

The source gas used for forming the deposited film by the apparatus of the present invention may be of a type that excites species by microwave energy and chemically interacts to form a desired deposited film on the substrate surface. Any of them can be adopted, but for example, when forming an a-Si (H, X) film, specifically, hydrogen, halogen,
Alternatively, it is possible to use gas-like substances such as silanes and halogenated silanes having hydrocarbons bonded thereto, or gasified substances that can be easily gasified. One of these source gases may be used, or two or more thereof may be used in combination. These source gases are He, Ar
Diluted with an inert gas such as Further, the a-Si film can be doped with a p-type impurity element or an n-type impurity element, and a source gas containing these impurity elements as a constituent component can be used alone or as the above-described source gas or / and / or And a mixture with a diluting gas and introduced into the reaction space.

When two or more source gases are used, one or more of them may be excited beforehand and then introduced into the reaction chamber. .

The substrate may be conductive, semi-conductive, or electrically insulating, and specific examples thereof include metals, ceramics, and glass. . The temperature of the substrate during the film forming operation is
Although not particularly limited, the temperature is generally in the range of 30 to 450 ° C, preferably 50 to 350 ° C.

In addition, in forming the deposited film, the pressure in the reaction chamber is set to 5 × 10 ⁻⁶ Torr or less, preferably 1 × 10 ⁻⁶ Torr or less before the source gas is introduced. Preferably, the pressure in the reaction chamber is on the order of 1 × 10 ^-2 Torr.

〔Example〕

Hereinafter, the device of the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited thereto.

Example 1 An Al cylinder (drum No. 101 to 108) having an outer diameter shown in Table 1 was prepared as a cylindrical substrate, and a long wavelength light absorption layer, a charge injection blocking layer, and an intermediate layer were provided on each Al cylinder. A light receiving layer consisting of (NO-containing layer: NO change layer), photoconductive layer and surface layer was formed under the conditions for forming a deposited film shown in Table 2 by using the apparatus shown in FIG. The number of gas introduction pipes in the device shown in FIG. 2 is four, the inner diameter of the gas introduction pipe, the angle and interval of the gas release holes of the gas introduction pipe, and the arrangement position of the gas introduction pipe (center of the gas introduction pipe). And the center of the cylindrical substrate) are shown in Table 1 for drum Nos. 101 to 108, respectively.

Each of the obtained light receiving members was set in an electrophotographic copying machine, and the film thickness, various characteristics and the formed image were evaluated. As shown in Table 3, good results were obtained. .

Example 2 An Al cylinder (drum No. 201 to 208) having an outer diameter shown in Table 4 was prepared as a cylindrical substrate, and the conditions for forming a deposited film were as shown in Table 5, and in the apparatus shown in FIG. The condition of the gas introduction pipe of the book is No. 4 for each of drum Nos. 201 to 208.
A light-receiving layer was formed on an Al cylinder (drum Nos. 201 to 208) in the same manner as in Example 1 except that those shown in the table were used.

When each of the obtained light-receiving members was evaluated in the same manner as in Example 1, good results as shown in Table 6 were obtained.

Comparative Example 1 As a cylindrical substrate, an Al cylinder (drum No. 301 to 306) having an outer diameter shown in Table 7 was prepared, and the deposition film formation conditions were drum No. 301, 302, 304 (outer diameter R ₁ = 80 [mm]). Indicates the conditions shown in Table 2, and drum No. 303, 305, 36 (outer diameter R ₁
= 108 [mm]), the conditions shown in Table 5 are set, and the conditions of the four gas introduction pipes in the apparatus shown in FIG. 2 are set as shown in Table 7 for each of the drum Nos. 301 to 306. A light receiving layer was formed on an Al cylinder (drum Nos. 301 to 306) in the same manner as in Example 1 except for the above.

When the obtained light-receiving members were evaluated in the same manner as in Example 1, the results shown in Table 8 were obtained for all of them.

From the results shown in Table 8, when the conditions of the above formulas I to III are not satisfied, the layer thickness and characteristics of the formed light-receiving layer become non-uniform in the circumferential direction and the generatrix direction of the Al cylinder, and the formed layer is formed. It was found that the images were totally and partially defective.

Figure 3 is the device of the present invention, theta, shall apply those illustrated d _1, the range of d ₂ in three dimensions, the space in the thick line portions theta in the apparatus of the present invention, the d _1, d ₂ Indicates the range. (Note that the dotted line portion (θ = π) indicates that part is removed.) In FIG. 3, ◯ indicates Examples 1 and 2, and ● indicates a comparative example. (● ¹⁾ is d ₁ = 1.
6 [mm] is out of the range, and ● ²⁾ is d ₂ = 9 [mm], which is out of the range, and neither is included in the thick line portion. [Summary of Effects of the Invention] The apparatus of the present invention is arranged on the cylindrical substrate without rotating the cylindrical substrate by setting the angle, the inner diameter and the interval of the gas discharge hole of the gas introduction pipe within a specific range. The film thickness and film quality of the deposited film formed on the substrate are uniform both in the circumferential direction and in the generatrix direction. Further, since it is not necessary to rotate the cylindrical substrate, there is no fear of leakage, and the cost of the device itself is low. Further, even if the inner diameter and the interval of the gas discharge port are variously changed within the above-mentioned conditions, the obtained deposited film has good film thickness and film quality uniformity, has few image defects, and has a yield in mass production. Has improved dramatically.

[Brief description of drawings]

FIG. 1 (A) is a cross-sectional view schematically showing the positional relationship between the gas release holes of the gas introduction pipe and the cylindrical substrate in the deposited film forming apparatus by the plasma CVD method of the present invention. B) is a side view of the gas introducing pipe. FIG. 2 is a schematic cross-sectional view schematically showing a typical example of the deposited film forming apparatus by the plasma CVD method. FIG. 3 is a three-dimensional view showing the range of angles, inner diameters, and intervals of the gas discharge holes in the device of the present invention. In Figs. 1 and 2, 1 ... Reactor container, 2 ... Peripheral wall also serving as cathode electrode,
3 ... Top wall, 4 ... Bottom wall, 5 ... Insulator, 6 ... Cylindrical substrate, 7 ... Heating heater, 8 ... Gas introduction pipe, 9 ...
Gas release hole, 10 ... Valve, 11 ... Exhaust pipe, 12 ... Exhaust valve, 13 ... Voltage applying means, 20 ... Gas supply system, 201
~ 205 …… Gas cylinder, 211 ~ 215 …… Valve, 221-225
…… Mass flow controller, 231-235 …… Inflow valve, 241-245 …… Outflow valve, 251-255 …… Pressure regulator.

Claims (1)

(57) [Claims] 1. A fixedly arranged cylindrical support on which a deposited film is formed is used as one electrode, and the other electrode is provided so as to face the electrode. Plasma is generated between the electrodes by discharge. A reaction container having a reaction space to be generated therein, a gas introduction pipe having a large number of gas discharge ports on a side wall for introducing a gas used for forming a deposited film in the reaction container, and the reaction space In the functional deposited film forming apparatus by the plasma CVD method having a means for exhausting from below, the angle of the gas release holes with respect to the cylindrical substrate surface is θ [rad],
Set the inner diameter of the gas discharge holes to d ₁ [mm] and the distance between the gas discharge holes.
where d ₂ [mm], the outer diameter of the cylindrical substrate is R ₁ [mm], and the distance between the center of the gas introduction tube and the center of the cylindrical substrate is R ₂ [mm], the following formulas I to III are given. An apparatus for forming a functional deposited film by a plasma CVD method characterized by satisfying. 0.5 ≦ d ₁ ≦ 1.5 …… II 10 ≦ d ₂ ≦ 100 …… III