JPH01273A - Microwave plasma CVD equipment - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

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 photoreceptor device for electrophotography, a line sensor for image input, an imaging device, an optical The present invention relates to a microwave plasma CvDv apparatus for forming functional thin films used in electromotive force devices and the like.

[Description of prior art]

Conventionally, amorphous silicon, such as hydrogen or/and Halogens (e.g. fluorine, chlorine, etc.)
compensated by amorphous silicon (hereinafter, (A −S
Deposited films of amorphous semiconductors such as i(H,X)) have been proposed, and some of them have been put into practical use.

Then, such a deposited film is deposited using a plasma CVD method, that is,
It is formed by a method in which a source gas is mediated by direct current, high frequency, or microwave glow discharge to form a gI film-like deposited film on a support such as glass, quartz, heat-resistant synthetic resin film, stainless steel, or aluminum. This is known, and various devices for this purpose have been proposed.

Especially in recent years, plasma C using microwave glow discharge decomposition
The VD method is attracting attention from an industrial perspective, and several apparatuses have been proposed for carrying out such microwave plasma CVD methods, and these apparatuses can be roughly classified into the following 2!1M types. That is, +1) so-called ECR type plasma C in which plasma is generated by electron cyclotron resonance (ECR) in a plasma generation chamber and the plasma is introduced into a film formation chamber.
VD apparatus, and (2) a so-called direct introduction type microwave plasma CVD apparatus that directly introduces microwave discharge power into a film forming chamber to generate glow discharge plasma.

Figure 3 shows the latter direct introduction type microwave plasma CVD.
1 is a cross-sectional diagram schematically showing a typical example of a device developed by the present inventors and which has reached the level of practical use.

In Fig. 3, 301 is a microwave introduction part, 302 is a vacuum container, and 303 is a support (cylindrical).If the support is plate-shaped, the surface of the cylindrical support, such as an aluminum cylinder, is 304 is a heater for heating the support, which brings the plate-shaped support into close contact with each other to form a deposited film;
305 is an exhaust buffer plate, 306 is a vacuum seal mechanism, 3
07 is a cooling system introduction part, 308 is a support rotation motor,
Reference numeral 309 indicates a support rotating shaft, 310, 31) a support holder, 312 a plasma, 313 a microwave introduction window, and A a discharge space.

The apparatus shown in the figure includes a plurality of supports 3 in a vacuum container 302.
03,303. ... are arranged in a ring shape to create a cylindrical space (discharge space A) in the center of a vacuum container, and microwave power is input from the cylindrical end face in at least one direction to generate a discharge. The microwave introducing section 301 does not require a large electromagnetic coil or an ECR cavity as in the case of the above-mentioned ECR (electron cyclotron resonance) type plasma CVD apparatus, and is relatively easy to project. In addition, by using the vacuum vessel 302 or its internal structure as a cavity resonator, it is possible to supply higher power than an ECR type plasma CVD apparatus, so the film formation rate is relatively high and gas decomposition is possible. The yield is also close to 100%, which has the advantage of being suitable for mass production of deposited films on large area supports.

Deposited film formation using this apparatus is performed as follows.

First, a plurality of supports 3o3°30 are placed inside the vacuum container 302.
3. Install the support body 3 using the motor for rotating the support body.
03 and a diffusion pump (not shown), 10-'To
Reduce the pressure to below rr. Next, a heater 30 for heating the support body
In step 4, the temperature of the support is controlled to a predetermined temperature of 50°C to 400°C. When the support body 303 reaches a predetermined temperature, a predetermined raw material gas, for example A-5i (H) is supplied from a gas cylinder (not shown).

X) In the case of forming a film, a raw material gas such as silane gas or hydrogen gas is introduced into the discharge space A, and the internal pressure of the discharge space A is set to a predetermined pressure of 10 mTorr or less. After the internal pressure stabilizes, a microwave power source (not shown)
Microwaves of 0 MHz or higher, preferably 4!2.45 GHz, are generated, and microwave energy is introduced into the discharge space A via the microwave introducing section 301.

(Thus, the source gas in the vacuum container is decomposed by microwave energy and deposited on the support 303, forming a deposited film.

The present inventors used the apparatus shown in FIG. 3 to obtain A-3i (H,
X) When the membrane was formed, the gas decomposition efficiency was almost 100%.
, the film deposition rate was about 230 people/S. The microwave power supplied at this time was a maximum of 1 kW in total. As is clear from the results, the microwave plasma CVD apparatus achieves a deposition rate of about 10 times, which is much higher than that using the conventional plasma CVD'J apparatus that uses high-frequency power at a frequency of 13.56 MH2. is obtained.

However, in the device configuration shown in FIG. 3, a film is deposited also on the microwave introduction part 301), especially on the microwave introduction window 313 that sends microwaves from the atmosphere side to the vacuum side, which reduces the propagation efficiency of microwaves into the vacuum container. As a result, it is difficult to constantly supply microwaves into the vacuum container in a stable state, and as a result, the conditions for microwave input power to consistently and efficiently form a high-quality deposited film become difficult. The problem is that it becomes difficult to control. Furthermore, if the thickness of this deposited film exceeds about 2 μm, it becomes extremely difficult to transmit microwaves, so it is necessary to replace the microwave introduction window 313 after several to ten-odd film formations. Currently, the microwave introduction window 313 is replaced, but the time required to remove and replace it cannot be ignored, and a large number of spare parts must be prepared for replacement. However, there are problems such as the need for additional steps such as cleaning work to remove the deposited film and the costs involved.

Furthermore, in the apparatus shown in Fig. 3, microwave introducing sections are installed at both the upper and lower ends of the apparatus in order to form a uniform film on a large area or long support, but the 94M There are many cases where there is a difference in the film thickness.Needless to say, for large area or long supports, it is essential that the film formation rate is high and the film thickness distribution is uniform. However, when the present inventors examined the film forming conditions to satisfy these conditions, it was found that the following two contradictory factors were deeply involved. FIG. 4 is a diagram showing the relationship between the relative film thickness distribution in the longitudinal direction of the support and the film forming pressure when A-3t(H,X) is formed.

That is, when forming a deposited film on the aforementioned large-area or long support, (1) the film-forming rate increases as the internal pressure during film-forming increases; (2)
It is necessary to overcome the contradictory factors that the lower the internal pressure during film formation, the more uniform the thickness distribution of the formed film.

Furthermore, when actually designing the equipment, the shape of the part from the vacuum vessel to the exhaust system is determined based on the assumed film forming conditions, especially the flow rate of the material gas and the internal film forming pressure. If you try to keep the film forming internal pressure low while supplying the same flow rate of material gas, the exhaust gas exhaust capacity will increase in inverse proportion to the pressure, so in order to secure the required exhaust capacity in a low pressure range, Another problem is that it requires a pump with a very high pumping speed, which is hardly realistic.

The present inventors actually conducted A-3 using the apparatus shown in Fig. 3.
When a t(H,X) film is formed, as shown in Figure 4,
A uniform film thickness distribution could not be obtained unless the internal pressure for film formation was set to I x 10-''Torr, and the film formation rate at this time remained at a maximum of 30 people/s due to the restriction on the amount of raw material gas.

In addition, when maintaining stable discharge at the above internal pressure and performing the above film formation, the supplied microwave power should be at least 3
It required a large amount of power of kW (total value of upper and lower). Furthermore, at this time, the microwave introduction window was extremely dirty, and the microwave discharge became unstable.

[Purpose of the invention]

The purpose of the present invention is to prevent deposited films from adhering to the microwave introduction part in a direct introduction type microwave CVD apparatus, to enable stable microwave discharge at all times, and to extend the maintenance cycle of the microwave introduction window. (Our goal is to provide a device that can do this.

Another object of the present invention is to use a direct introduction type microwave plasma CVDv apparatus to produce element members used in semiconductor devices, electrophotographic photoreceptor devices, photovoltaic elements, various other electronic elements, optical elements, etc. When forming a deposited film as a material, it is possible to increase the film formation rate and obtain a film with a uniform thickness distribution. An object of the present invention is to provide a microwave plasma CvD apparatus that enables the formation of.

[Structure of the invention]

The present invention solves the above-mentioned problems in the conventional microwave plasma CVDv apparatus that directly introduces microwaves into a vacuum container, and as a result of intensive research to achieve the above-mentioned purpose, By forming a magnetic field parallel to the axial direction of the cylindrical discharge space surrounded by multiple supports and generating high-density plasma in this area, the deposition rate can be improved. We have found that by keeping the 0-wave introduction window sufficiently away from the generated plasma, it is possible to prevent the deposited film from adhering to the microwave introduction window.

The present invention has been completed based on the above findings, and the microwave plasma CVD apparatus of the present invention includes a vacuum container, a means for holding a plurality of deposited film forming supports in the vacuum container, and a plurality of supports for forming deposited films. means for supplying raw material gas into the vacuum container;
A microwave plasma C comprising a means for evacuating the inside of the vacuum container and a microwave introduction window for introducing microwave power into the vacuum container.
In the VD device, a magnet is disposed on the outer periphery of the vacuum container, the inner diameter of the microwave introduction part is made larger than the shortest distance between opposing supports, and the microwave introduction window is further provided with a magnet. It is characterized in that the position is located beyond the end of the support at a distance equal to or longer than the inner diameter of the microwave waveguide.

In the plasma CVD apparatus of the present invention, various modifications are possible regardless of the number and position of the microwave introducing portions.

Further, the magnet in the plasma CVD apparatus of the present invention may be a magnet having a certain magnetic force or may be an electromagnet, and the magnet may be magnetically shielded as necessary to prevent the influence of the magnetic field to the outside of the apparatus. can also be provided as appropriate. Furthermore, when using an electromagnet, the coil wire can be made of superconducting material.

Further, in the device of the present invention, it is desirable that components other than the magnet be formed of non-magnetic materials.

The raw material gas used to form the deposited film by the apparatus of the present invention is one that is excited and speciated by microwave energy and chemically interacts with it to form the desired deposited film on the surface of the support. Any gas can be used, but for example, in the case of forming an A-3t (H, Gases such as silanes and halogenated silanes, hydrogen gas, etc. can be used. Furthermore, the A-3t(H,X) film can be doped with a p-type impurity element or an n-type impurity element,
Raw material gases containing these impurity elements as constituents can be used alone or in combination with the aforementioned raw material gases.

The support for forming the deposited film may be conductive, semiconductive, or electrically insulating; specifically, it may be made of metal, ceramic, or glass. etc.

The substrate temperature during the film forming operation is not particularly limited, but
The temperature is preferably in the range of 30 to 450°C, preferably 50 to 350°C.

In addition, when forming a deposited film, before introducing the raw material gas, the pressure in the film forming chamber is set to 5 X 10-' Torr or less, preferably 1 X 10-' Torr or less, and when the raw material gas is introduced, the film forming chamber is The pressure in the room is I x 10
-"~I Tor'r, preferably 5X10-!~
It is desirable to set it to ITorr.

Hereinafter, the configuration and effects of the microwave plasma CVD apparatus of the present invention will be explained using specific apparatus examples, but the present invention is not limited thereto.

FIG. 1 is a schematic vertical cross-sectional view schematically showing a typical example of the microwave plasma CVD apparatus of the present invention, and FIG. 2 is a schematic cross-sectional view taken along line AA' of the apparatus shown in FIG.

In FIGS. 1 and 2, 100 is a microwave introduction section, and the microwave introduction section is composed of a microwave waveguide 102, a microwave introduction window 101, and vacuum seals 103 and 104.

105 is a support, 106.107 is a support holder, tO
S is a vacuum container, 109 is an electromagnet, 1) 0 is a support rotation axis, 1) 1 is a vacuum seal mechanism, 1) 2 is a cooling system introduction mechanism,
1) 3 is a motor for rotating the support, 1) 4 is an electromagnetic cooling jacket, 1) 5 is plasma, 1) 6 is a microwave transmission tube, 1) 7 is a heater for heating the support, 1) 8 is an exhaust port,
1) Reference numeral 9 indicates a raw material gas supply system.

As is clear from Figure 1.2, this example is an example of an apparatus in which a plurality of cylindrical long supports are installed in a ring shape in a vacuum container, and the deposited film formation using this example apparatus is as described above. This is carried out in the same manner as in the case of using the apparatus shown in FIG.

Deposited film formation using the apparatus of this embodiment will be described below.

Microwave power is supplied into the vacuum container 108 through the microwave introduction window 101. At this time, the magnetic field of the magnet 109 placed on the outer periphery of the vacuum vessel 108 is adjusted appropriately to generate plasma 1) 5 only in the discharge space A surrounded by the support 105.

It is generally desirable to set the position of the microwave introduction window so that 2c<b<5c is satisfied.

In addition, it is necessary to suppress plasma generation near the microwave introduction window as much as possible, and the electric field intensity generated by microwaves needs to be lower than the electric field intensity in the film forming space. Therefore, the inner diameter of the microwave transmission tube C It is desirable that Md be larger than the shortest distance Md between opposing supports in the film forming space.

In other words, it is necessary to set it to satisfy cod.
The placement position of the magnet affects the uniformity of the plasma, and it is necessary to arrange the magnet so that the film formation rate is uniform over a large area and long support.

Incidentally, when the film forming internal pressure is 0.01 to 1. It has been found that when the OTorr is in the range, the plasma leaks to the microwave introduction window 101 side by about the diameter of the space.

That is, the plasma leakage fia in FIG. 1 is approximately the shortest distance d between the opposing supports shown in FIG. The value of the leakage amount a can be adjusted by the pressure during film formation and the position or strength of the magnetic field. That is, the plasma leakage amount a can be reduced by increasing the pressure during film formation, by moving the magnet closer to the center, or by increasing the magnetic field.

In FIG. 1, b represents the end of the support and the microwave introduction window 1.
01, and C indicates the inner diameter of the microwave transmission tube.

By setting the distance between the microwave introduction window and the end of the support sufficiently large compared to the plasma leakage amount a described above, it is possible to prevent the deposited film from adhering to the microwave introduction window 101. However, if b is too large, microwave propagation loss will occur. From this, we formed an A-3iH film using silane gas (SiH*) as a raw material gas while rotating the support using the apparatus shown in Figure 1 set under the above conditions. And the internal pressure is 0.2 T
orr, a microwave power of 500 W, a silane gas flow rate of 1000 cc/min, and a support heating temperature of 250° C., a deposition rate of 100 persons/S was obtained.

Another embodiment of the microwave plasma CVD apparatus of the present invention is shown in FIG. In the figure,
500 is a microwave introduction part, 501 is a microwave introduction window, 502 is a microwave waveguide, 503 and 504 are vacuum seals, 505 is a flat support, 508 is a vacuum container, 50
9 is′;! L magnet, 514 is electromagnet water cooling jacket, 5
15 is a plasma, 516 is a microwave transmission tube, 517 is a heater for heating the support, 518 is an exhaust port, and 519 is a material gas supply system.

[Summary of effects of the invention]

The microwave plasma CVD apparatus of the present invention has the following effects: +1) preventing film adhesion at the microwave inlet, and (2) increasing the film formation rate, and (3) requiring a small-scale exhaust pump. It has the effect of ending it.

[Brief explanation of drawings]

FIG. 1 is a schematic vertical cross-sectional view schematically showing a typical example of the plasma CVD apparatus of the present invention, and FIG.
' is a schematic cross-sectional view at '. FIG. 3 is a sectional view showing a conventional microwave plasma CVD apparatus, and FIG.
4 is a diagram showing the relationship between the film forming pressure and the relative film thickness distribution in the longitudinal direction of the support when a deposited film is formed using the apparatus shown in FIG. 3. FIG. FIG. 5 is a schematic cross-sectional view schematically showing another example of the microwave plasma CVD apparatus of the present invention. 1st. ．． In Figure 2.5, 100,500...Microwave introduction part, 101,501...Microwave introduction window, 102.502...Microwave waveguide, 103゜1
04.503,504...Vacuum seal, 105°50
5... Support body, 106, 107... Support body holder,
108.508...Vacuum container, 109,509...
Electromagnet, 1) 0... Support rotation axis, 1) 1... Vacuum seal mechanism, 1) 2... Cooling system introduction mechanism, 1) 3...
・Support rotation motor, 1) 4.514...Electromagnetic water cooling jacket, 1) 5.515...Plasma, 1)
6゜516...Microwave transmission tube, 1) 7,517・
...Heater for heating the support, 1) 8,518... Exhaust port, 1) 9,519... Raw material gas supply system. Regarding Figure 3, 301...Microwave introduction part, 30
2... Vacuum container, 303... Support, 304...
Support heating heater, 305...exhaust buffer plate,
306... Vacuum sealing mechanism, 307... Support cooling system introduction mechanism, 308... Support rotation motor, 30
9...Support rotating shaft, 310, 31)...Support holder, 312...Microwave plasma, 313...
Microwave introduction window, A...discharge space. Figure 2 Figure 5

Claims (1)

[Claims] (1) A vacuum container, a means for holding a plurality of deposited film forming supports in the vacuum container, a means for supplying raw material gas into the vacuum container, a means for evacuating the inside of the vacuum container, A microwave plasma CVD apparatus comprising a microwave introduction section having a microwave introduction window for introducing microwave power into a vacuum container, wherein a magnet is disposed on the outer periphery of the vacuum container, and The inner diameter of the microwave introduction part is made larger than the shortest distance between opposing supports,
Furthermore, the microwave plasma CVD apparatus is characterized in that the microwave introduction window is located at a distance greater than or equal to the inner diameter of the microwave waveguide from the end of the support.