JPS627120A - Deposition film forming device - Google Patents

Abstract

PURPOSE:To prevent powder mixing into a discharge system such as pumps by providing a recovery means for powder produced in a reaction chamber in the discharge system of the reaction chamber for forming deposition film. CONSTITUTION:Vacuum valves 8b and 11b are closed and the vacuum valves 8a and 11a are opened. Only a powder trap 9 is used as a powder recovery means. To form a deposition film, a substrate is set in a reaction chamber 1 and heated as necessary. When the temperature of the substrate reaches the specified temperature, silane-based gas such as Si, H4, Si2H6 etc. is introduced into the reaction chamber 1, and discharge is performed with direct current, high-frequency, etc. so that gas is decomposed, and amorphous silicon is deposited on the substrate. The powder produced at this time reaches a powder trap 9 through a discharge pipe 2 and a vacuum valves 3 and 8a and collected there. When large amount of the powder is accumulated, the vacuum valves 8b and 11b are opened and the vacuum valves 8b and 11a are closed, and the powder trap 10 is used as a powder recovery means.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a deposited film forming apparatus, and particularly to improvement of its exhaust system.

The present invention is applied to an apparatus for forming a deposited film of amorphous silicon or the like by, for example, a plasma CVD method, a glow discharge method, an arc discharge method, or the like.

[Prior Art] FIG. 3 is a schematic configuration diagram of an example of a conventional deposited film forming apparatus.

In the figure, gas and the like in a reaction tank 1 pass through an exhaust pipe 2 and a vacuum valve 3, and are forcibly exhausted to the outside by a mechanical booster 4 and an oil rotary pump 5. Note that the oil rotary pump 5 includes an oil filter 6 and an oil tank 7.
is connected.

Such an exhaust system is used to achieve a desired degree of vacuum within one reaction tank 1 and to exhaust the reacted gas during the formation of a deposited film.

[Problems to be Solved by the Invention] However, when a deposited film is formed on a substrate set in the reaction tank 1 by, for example, a plasma CVD method, a part of the reaction product is deposited on the inner surface of the reaction tank 1 or on the piping. It adheres in powder form to etc. Therefore, in the conventional deposited film forming apparatus,
Reaction tank! When evacuating the inside, the powder gets mixed into the mechanical booster 4, oil rotary pump 5, etc. of the exhaust system, resulting in a decrease in the pump's exhaust capacity and deterioration of the pump oil, and the oil filter 8 has to be replaced more frequently. However, in some cases, the mechanical durability of the pump may be deteriorated.

[Means for Solving the Problems] The deposited film forming apparatus according to the present invention is characterized in that the exhaust system of the reaction tank for deposited film formation is provided with means for collecting powder generated in the reaction tank. be a sign.

[Function] By providing the powder recovery means in the exhaust system in this way,
Powder is prevented from entering the exhaust system such as a pump, there is no reduction in the exhaust capacity or breakdown of the exhaust system, and maintenance is significantly reduced compared to conventional systems.

[Example] Hereinafter, an example of the present invention will be described in detail using the drawings.

FIG. 1 is a schematic diagram of an embodiment of a deposited film forming apparatus according to the present invention. However, the same members as those in the conventional example described above are given the same numbers to simplify the explanation.

In the figure, the exhaust pipe 2 of the reaction tank 1 is branched via a vacuum valve 3, one pipe is connected to the suction port of a powder trap 9 via a vacuum valve 8a, and the other pipe is connected to a vacuum valve 8b. It is connected to the suction port of the powder trap 10 via the powder trap 10. Further, the respective discharge ports of the powder traps 8 and 10 join together via vacuum traps lla and llb, and are connected to the suction port of the mechanical booster 4. The discharge port of the mechanical booster 4 is connected to the suction port of the oil rotary pump 5, and the gas in the reaction tank 1 is discharged to the outside from the discharge port of the oil rotary pump 5. The configurations of the powder trap 9 and lO will be explained later using FIG. 2.

Next, the process of forming a deposited film and the operation of this embodiment will be explained.

First, the vacuum valves 8b and llb are closed, and the vacuum valves 8a and lla are left open, so that only the powder trap 9 is used as a powder collection means. continue,
A reaction tank to form a deposited film! Place the substrate inside and heat as necessary. For example, when forming an amorphous silicon film, it is generally heated to about 200 to 300°C. When the substrate reaches a certain temperature, SiH4, Si2
A silane gas such as H6 is introduced into the reaction tank 1 from a gas introduction pipe (not shown), and discharge is caused by a voltage such as a direct current or high frequency. Due to the discharge phenomenon, the introduced gas is decomposed and amorphous silicon is deposited on the substrate. The powder generated at this time is the exhaust pipe 2. Vacuum valves 3 and 8
a to the powder trap 8, where it is collected.

Therefore, the gas from which the powder has been removed is sucked into the mechanical booster 4 and the oil rotary pump 5, thereby preventing a decrease in the pumping capacity of conventional pumps and failures caused by the powder.

When a large amount of powder is accumulated in the powder trap 9 in this way, the vacuum valves 8b and ub are opened, and the vacuum valve 8
Close a and lla. As a result, the powder trap 10 is now used as a powder collection means, while
The powder trap 9 in which powder has accumulated is replaced with a new powder trap 2.
or the powder in the powder trap θ is removed as described below. By branching the exhaust pipe into two or more lines in this manner, powder traps in which powder has accumulated can be replaced one after another without interrupting the exhaust operation.

FIGS. 2(A) to 2(C) are schematic cross-sectional views showing modified examples of the powder trap in this embodiment.

In FIG. 2(A), the case 20 is provided with an inlet pipe 21 connected to the exhaust pipe 2 side of the reaction tank l and an exhaust pipe 22 connected to the mechanical booster 4 side. A cutting board 23 is provided inside. The gas from the suction pipe 21 first collides with the baffle plate 23 and is guided downward, further collides with the inner wall of the case 20 and is discharged from the exhaust pipe 22. Therefore, the powder contained in the intake gas adheres to the cutting board 23 and also to the inner wall of the case 20 due to collision or settling, and the gas from which the powder has been removed is discharged from the exhaust pipe 22. .

Note that it is clear that the shape of the baffle plate 23 is not limited to only the illustrated shape.

In FIG. 2(B), a removable tank 24 is provided at a portion where the gas from the suction pipe 21 collides. Therefore, the powder contained in the intake gas mainly adheres to the inner wall of the tank 24 due to collision or sedimentation, and the gas from which the powder has been removed is discharged from the exhaust pipe 22 provided at the upper part of the case 20. . When the powder is accumulated in the tank 24 in this way, the tank 2
4 to remove the powder, or replace it with a new tank 24.

In FIG. 2(C), a ring-shaped discharge electrode 2B is provided on the case 20 with an insulating material 25 interposed therebetween, so that attached powder can be removed by etching without disassembling the powder trap. Gas from the suction pipe 21 is blown onto the lower part of the inner wall of the case 20, and powder contained in the suction gas adheres to the lower part of the inner wall of the case 20 by collision or sedimentation.

To remove the powder thus accumulated, an etching gas such as CF4 is introduced into the case 20' from the reaction tank 1, and a high frequency is applied to the discharge electrode 26 to cause discharge.

As a result, the etching gas is decomposed and the accumulated powder can be removed by etching.

[Effects of the Invention] As described above in detail, since the deposited film forming apparatus according to the present invention includes the powder recovery means in the exhaust system, it is possible to prevent powder from entering the exhaust system such as a pump. As a result, the reduction in the exhaust capacity of the exhaust system, the deterioration of the oil in the pumps, the reduction in mechanical durability, etc. are prevented from snow, the reliability of the exhaust system is improved, and maintenance is significantly reduced compared to conventional systems.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of an embodiment of a deposited film forming apparatus according to the present invention. FIGS. 2(A) to 2(C) are schematic cross-sectional views showing modified examples of the powder trap in this embodiment. FIG. 3 is a schematic configuration diagram of an example of a conventional deposited film forming apparatus. 1... Reaction tank 4, fist, mechanical booster 5... oil rotary pump 9. 101111, powder trap 23, number, order plate 24, removable tank 2B... discharge electrode agent Patent Attorney Seki Yamashita Figure 2 ↓ (C) ↓

Claims (4)

[Claims] (1) A deposited film forming apparatus characterized in that an exhaust system of a reaction tank for forming a deposited film is provided with means for collecting powder produced in the reaction tank. (2) The deposited film forming apparatus according to claim 1, wherein the powder collecting means comprises a tank that collects the passing powder by colliding with the surface of an object therein. (3) The deposited film forming apparatus according to claim 2, wherein the collection tank accommodates a detachable container in which the collected powder is deposited. (4) The deposited film forming apparatus according to claim 2, wherein the collecting tank is provided with a discharge electrode for decomposing and vaporizing the collected powder.