JPS60215768A - Device for forming amorphous film - Google Patents

Abstract

PURPOSE:To prevent generation of leak discharge and to obtain a film having good quality by constituting the wall part which constitutes a vacuum vessel for contg. a base body as an electrode for impressing discharge voltage in the stage of glow discharge. CONSTITUTION:A glow discharge device is so constituted that a supply gas is introduced through gas leading-out holes 5 via a space 4 between an introducing port 7 and a circumferential wall 1 into the annular spacing between an inside wall 3 and a substrate 41 and is discharged to the outside of the devicd through a butterfly valve 50 from a discharge port 9 provided to a supporting cylinder 8a of a lower cap 8. The Al substrate 41 subjected to surface cleaning is disposed in the vacuum vessel and glow discharge is executed by evacuating the gaseous pressure in the vacuum vessel to about 10<-6>Torr, heating and holding the substrate 41 to and at about 100-350 deg.C, introducing a reactive gas into the vacuum vessel and impressing high-frequency voltage by a high- frequency power source 56 under the prescribed reactive pressure. There are no objects to be subjected to electric discharge except the substrate 41 and the generation of leak discharge is obviated if the inside wall 3 of the vacuum vessel is made as an electrode and if the film is deposited on the substrate 41 by decomposing the reactive gas by the glow discharge between said wall and the substrate 41.

Description

[Detailed description of the invention] 1. Industrial application field The present invention relates to an apparatus for forming an amorphous semiconductor film.

2. Conventional technology For example, amorphous silicon (hereinafter referred to as a-8t).

) film is widely used as the photosensitive layer of photoreceptors, and its formation is by so-called plasma CVD using glow discharge decomposition of 5iHi.
It's according to the law.

a-8t on the surface of a cylindrical substrate by plasma CVD method.
The following methods can be considered as methods for forming the film. That is, as shown in FIG. 1, a drum-shaped substrate 41 is vertically and rotatably set in a vacuum chamber 52 (usually made of stainless steel) of a capacitively coupled glow discharge device 51. , the substrate 41 can be heated from the inside to a predetermined temperature by a heater 55. A cylindrical high frequency electrode 57 with a gas outlet 53 is disposed around the substrate 41, facing the substrate 41, and generates a jiglow discharge between the substrate 41 and the high frequency power source. In addition, 62 in the figure is a supply source of SiH4 which is hydrogenated silicon gas, 65 is a carrier gas supply source such as nitrogen, and weak is an impurity gas (for example, BA
H. or PH5) supply source, 67 is each flow meter.

In this glow discharge device, first, the surface of a support, for example, an M substrate 41, is cleaned, and then placed in a vacuum chamber 52, and the gas pressure in the vacuum chamber 52 is adjusted to 10-@Torr. and evacuate the substrate 41 to a predetermined temperature, especially 1
The temperature is maintained at 00 to 350°C (preferably 150 to 300°C). Next, using a high-purity inert gas as a carrier gas, SiH4 gas, which is silicon hydride, and BdL, if necessary, are appropriately introduced into the vacuum chamber 52, and the air is heated between the high-frequency power source under a reaction pressure of, for example, 0.01 to 10 Torr. A high frequency voltage (for example, 13.56 MHz) is applied. Accordingly, each of the above reaction gases is transferred between the electrode 57 and the substrate 4.
1, and is deposited on the substrate 41 as a-8i:Ht or impurity-doped a-8t:H.

In addition, by plasma CVD method, a
The following methods can be considered as methods for forming the -8t film. That is, as shown in FIG. 2, in the vacuum chamber 72 of the glow discharge device 71, a flat substrate 61 is set on a substrate holder ω, and a heater (not shown) built in the substrate holder ω is used. can be heated to a predetermined temperature. A flat high frequency electrode 77 faces the substrate 61.
is disposed, and a jiglow discharge is generated between it and the substrate 61 by the high frequency power supply 56. Note that the supply of each gas into the vacuum chamber 72 is the same as that shown in FIG. 1, so illustration thereof is omitted. Furthermore, since the formation of the A-8I film on the substrate 61 is based on the same mechanism as the formation of the A-8T film on the cylindrical substrate, the explanation thereof will be omitted.

However, when using the above method, discharge leakage from both ends of the electrode 57 or 77 shown in FIG. 1 or FIG.
A discharge unrelated to the a-8t film formation (hereinafter referred to as leakage discharge) occurs, such as a discharge between the a-8t film and the a-8t film formed between the The quality of the film is degraded and the powder adheres to the inner wall surface of the vacuum chamber 52 or 72. Such deposits deteriorate the quality of the amorphous semiconductor film to be formed when the next amorphous semiconductor film is formed. 1 in %
For example, when an amorphous germanium film is formed using the same apparatus after forming an a-8i film, Si is contained as an impurity in the formed amorphous germanium film, which is extremely inconvenient.

However, it takes a considerable amount of time to remove such deposits.

Therefore, as shown in FIGS. 1 and 2, a grounded net-shaped shield brocade or 59 is provided at a position several tens of meters away from the surface of the electrode 57 or 770, excluding the surface facing the substrate, to prevent leakage discharge as described above. Although there are ways to prevent leakage discharge, it is extremely difficult to completely prevent leakage discharge.

3. Purpose of the Invention The present invention solves the problems of the conventional amorphous amorphous membrane forming apparatus as described above, and provides an amorphous amorphous membrane forming apparatus having a function of preventing the occurrence of leakage discharge. is intended to provide.

4. Structure of the Invention In other words, the present invention provides an apparatus for forming an amorphous semiconductor film on a substrate by glow discharge decomposition of a reactive gas, in which at least a portion of a wall constituting a vacuum chamber housing the substrate is formed by the glow The present invention relates to an apparatus for forming an amorphous semiconductor film, which is configured as an electrode for applying a discharge voltage during discharge.

5. Examples Example 1 ゛This example is an example of an apparatus for forming an A-8T film on a cylindrical substrate, and as shown in FIG. and a large number of gas outlet holes 5 over the entire surface.
an inner wall 3 through which a gas circulation space 4 is formed between both walls 2.3; 8 and; upper lid 10
As shown in FIG. 4, a glow discharge device equipped with such a vacuum chamber consists of a substrate 41 which is rotated within the peripheral wall 1 by a drum-shaped drive device without a base. An inner wall 3 through which a gas outlet hole (pore or slit) 5 penetrates is located facing the substrate 41 so that it can be heated to a predetermined temperature from the inside by a heater 5, and the inner wall 3 is provided with a high frequency electrode. Also, a glow discharge is generated between the high frequency power source and the substrate 41.

Although not shown, supply sources for 5IH4, K and impurity doping gas are provided in the same way as in FIG. The gas enters the annular space between the inner wall 3 and the substrate 41 through the gas outlet hole 5, passes through the exhaust port 9 provided in the support tube 8a of the lower cover 8 to the device via a vacuum pump (not shown) Expelled outside.

The gas seal between the lower lid 8 and the outer wall 2 of the peripheral wall 1 is provided by the lower lid 8.
The groove 8c is fitted into an annular groove 8c cut into the inner circumferential surface of the flange 8b, which extends upward from the flange 8b to surround the outer wall 2.
The ring 8d provides a gas seal between the lower cover 8 and the rotating shaft 6 through a mechanical seal provided between the support tube 8a and the rotating shaft 6. Upper lid 10 and peripheral wall 1
The gas seal between the outer wall 2 and the outer wall 2 is provided by a flange 10b extending downward from the upper lid 10 to surround the outer wall 2.
This is done by an O-ring 10d fitted into an annular groove 10c cut into the inner circumferential surface of the holder.

In this glow discharge device, for example, an M substrate 41 whose surface has been cleaned in advance is placed in a vacuum chamber, the gas pressure in the vacuum chamber is evacuated to 10' Torr, and the substrate 41 is heated to 100 Torr.
Heat and maintain at ~350°C (preferably 150-300°C). Next, using M as a carrier gas, 5iHa gas and, if necessary, BJs etc. are introduced into the vacuum chamber as appropriate.
For example, a high frequency voltage (for example, 13.56 MHz) is applied by the high frequency power supply 56 under a reaction pressure of 0.01 to 10 Torr. The reaction pressure is controlled by a butterfly valve 50.

As a result, the reaction gas is decomposed by glow discharge between the inner wall 3, which also serves as an electrode, and the substrate 41, and is deposited on the substrate 41 as a-8i:H or impurity-doped a-8i:H.

By using the inner wall 3 as a high frequency electrode in this way, there is no other target for discharge other than the substrate 41, and
Leakage discharge will no longer occur.

As a result, the chemically active species are uniformly spread throughout the cross-sectional annular space between the inner wall 3 and the substrate 41, that is, the entire reaction chamber, and a high quality A-8I film is formed. It can be simplified and downsized, and it is also expected to speed up film formation. Furthermore, since the outside of the outer wall 2 is at atmospheric pressure, there is no risk of discharge leaking to the outside.

In order to prevent danger, insulating paint should be applied to the outer surfaces of the outer wall 2, the lower cover 8 and the upper cover 10, or the outer walls of the lower cover 8', the upper cover 10' and the peripheral wall 1' should be painted as shown in FIG. It is desirable that the vacuum chamber is constructed by using an insulating material as the material of 2' and a conductive material as the inner wall 3' of the peripheral wall 1'.
In order to prevent high frequency noise from occurring outside the apparatus, it is desirable to cover the entire vacuum chamber with a shielding member.

Example 2 In this example, a-8t was applied more uniformly to the apparatus of Example 1.
As shown in FIG. 6, the vacuum chamber is made up of a peripheral wall 11, a lower lid 18, and an upper lid 20. and the space between them into two spaces 14a and 14
The outer wall 12 has a gas inlet 1 that penetrates toward the space 14a.
7 and a gas exhaust port 19 penetrating toward the space 14b, and the inner wall 13 is provided with a large number of gas outlet holes 15a penetrating toward the space 14a and a large number of gas exhaust holes 15b penetrating toward the space 14b. It is set up over .

Figure 7 is a cross-sectional view showing the outline of the glow discharge device equipped with the vacuum chamber shown in Figure 6 (however, the heater (55 in Figure 4)
is not shown. ).

The lower lid 18 is different from that in the first embodiment and has a shaft 4.
A gas seal between the rotary shaft and the rotary shaft 3 is provided by a mechanical seal, and the rotation of the rotary shaft is enabled.

The gas introduced into the vacuum chamber from the gas inlet 17 enters the space 14a and the gas outlet hole (pore or slit) 15.
a, enters the annular space between the inner wall 13 and the substrate 41, and gas discharge hole (pore or slit) 15b1 space 1
It is discharged to the outside of the vacuum chamber by a vacuum pump (not shown) via the 4b1 exhaust port 19 and the butterfly nozzle.

The gas seal between the peripheral wall 11, the lower cover 18, and the upper cover and the mechanism for forming the a-8i film are the same as in Example 1, so their explanation will be omitted. By having such a structure, the inner wall 13 and the substrate 41
The reaction gas moves in the circumferential direction within the reaction chamber having an annular cross section, and the a=si film is formed more uniformly.

In addition, in FIG. 6, the 27 partition walls 16 are replaced by the peripheral wall 11.
Although the inner space is divided into two spaces 14a and 14b having the same volume, the spaces 14a and 14b do not necessarily have to have the same volume.

On the contrary, as shown in FIG. 8, if the volume of the space 14a on the side in contact with the gas outlet 17 is made larger than the volume of the space 14b on the side in contact with the gas exhaust port 19, the new reaction gas to be supplied will be reduced. The surface of the substrate 410 is in contact with the surface of the substrate 410.

Embodiment 3 In this example, in order to improve the productivity of the apparatus of Embodiment 2,
This is an example of improvements.

In this example, as shown in FIG. 9, the outer wall n of the peripheral wall 21 is formed so that its side surface is rectangular when viewed from above.
A gas inlet 27 is provided on one of the opposing longitudinal side walls.
The other side of the sheep is given an evacuation age, and a plurality of cylindrical inner wall vessels are arranged in a row in the inner longitudinal direction of the outer wall 4, and between adjacent inner wall vessels and between the inner wall vessels located at the end. A partition wall is provided between the outer wall 22 and the space formed between the outer wall 22 and the inner wall to be divided into two spaces 24a and 24b. gas outlet hole (
A penetration 41 is arranged through the pore or slit 25a towards the space 24b.

The structure of the nine-glow discharge device equipped with this peripheral wall 21 is the same as that in the third embodiment, except that the outer wall has the above-mentioned shape and a plurality of inner walls are arranged. A detailed explanation will be omitted. By doing the above, A-8T films can be formed on multiple substrates at the same time, so a large number of films can be formed in one operation, greatly increasing productivity. Embodiment 4 This example is an example of an apparatus for forming an a-St film on a flat substrate.As shown in FIG. 10, a vacuum chamber 31 has a bottom wall 31a.
The main body is not made of a conductive material, and the other parts are made of an insulating material, and a gas inlet 37 and an exhaust port 39 are provided on the side wall.

Inside the vacuum chamber 31 is a substrate holder 42 that holds a substrate 41a.
The bottom wall 31a of the vacuum chamber 31 is connected to the high frequency power source 56, and the substrate 41a is connected to the high frequency power source and the ground circuit via the substrate holder 42a.
a and the substrate 41a constitute a counter electrode.

The gas in the vacuum chamber 31 is exhausted to the outside of the apparatus by a vacuum pump (not shown) via an exhaust port 39 and a butterfly nozzle.

Incidentally, although not shown, similarly to FIG. 1, 5i
Ha, Ar, and impurity gas supply sources are provided.

Using such an apparatus, an a-8t film is formed on the surface of the flat substrate 41a in the same manner as in the first embodiment.

As mentioned above, leakage discharge does not occur in any of the examples (the a-8t film is uniformly formed and the a-8t film is of good quality).
8t film is formed, the apparatus can be simplified and miniaturized, and the film formation speed can be expected to be increased.Although the above embodiments have described &-8t film formation, the apparatus of the present invention By changing or adding a gas supply source, it can also be used to form other amorphous semiconductor films other than the A-8I film, such as an amorphous silicon carbide film, an amorphous silicon nitride film, an amorphous germanium film, etc. It goes without saying that it can be done.

Further, the present invention is applicable only to the capacitively coupled device described above.
．． 29.39・・・・・・・・・・・・Exhaust port 1
0.10-20・・・・・・・・・・・・Top lid 3
1・・・・・・・・・・・・・・・Vacuum chamber 31a
・・・・・・・・・−・・Bottom wall 41.41a・−・
・・・・・・・・・・・・Substrate 42・・・・・・・・・・
..... Board support stand 42a .....
Board holder circle...Butterfly valve connection...High frequency power supply.

Agent: Patent attorney Hiroshi Aisaka (and 1 other person) Figure 1 Figure 3 Chapter 4 Figure 5 11’l’

Claims (1)

[Claims] 1. In an apparatus for forming an amorphous semiconductor film on a substrate by glow discharge decomposition of a reactive gas, at least a portion of a wall constituting a vacuum chamber accommodating the substrate is used for applying a discharge voltage during the glow discharge. An apparatus for forming an amorphous m film, characterized in that it is configured as an electrode.