JPH06326034A - Cleaning method for plasma cvd device - Google Patents

Abstract

PURPOSE:To provide a method, in which polysilane powder, etc., depositing in a plasma CVD device are cleaned. CONSTITUTION:Polysilane powder depositing in a device is removed by a reaction by using NF3 within a temperature range of 120-400 deg.C. An amorphous thin-film and polysilane powder depositing in a plasma region are removed particularly through simultaneous plasma cleaning by using NF3 within the temperature range of 120-400 deg.C.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plasma C for depositing an amorphous thin film using a silane compound such as silane.
The present invention relates to a cleaning method of a plasma CVD apparatus for removing powder (hereinafter referred to as polysilane powder) deposited on a VD apparatus.

[0002]

2. Description of the Related Art Recently, amorphous thin films such as amorphous silicon (a-Si) formed by plasma CVD (hereinafter referred to as PECVD) have been widely used in the fields of TFT, solar cell, electrophotography and the like. Is used for.

Further, the PECVD apparatus is generally of a system in which only the substrate is heated. Figure 1 Balanced flat plate PE
A schematic diagram of the CVD apparatus is shown. Conventionally, PECVD equipment immerses the jigs and parts in an aqueous solution of strong acid and strong alkali, removes the amorphous silicon film adhering to these, and scrapes out the polysilane powder deposited on the reactor wall, etc. with human power and soaks it with alcohol. It was cleaned by wiping with a clean cloth. These methods are not suitable for cleaning large equipment, and
Since a person enters the apparatus, there is a risk of mixing particles into the reactor and causing an accident.

In view of these problems, various self-cleaning methods using fluoride gas have recently been implemented or proposed. If you roughly divide the self-cleaning method,
There are plasma re-screening using an active gas such as ClF ₃ , HF and F ₂ , and a plasma cleaning method using an inert gas such as NF ₃ , CF ₄ and SF ₆ activated by plasma. However, these methods also have some problems. Plasma rescreening
Since an active gas is used, the process temperature (200 ° C-4
If the cleaning is performed at 00 ° C., there is a risk of damage to the commonly used electrode material such as stainless steel. Therefore, change the device material itself to a material with high corrosion resistance,
It is necessary to lower the process temperature for cleaning.
If the process temperature is lowered, the substrate temperature must be raised again for film formation, and cleaning takes a long time, so that the significance of introducing self-cleaning for streamlining the process becomes small. Further, depending on the conditions during cleaning, fluorine remains on the reactor wall, and there is also a problem of fluorine being mixed into the product film.

Next, regarding the conventional plasma cleaning, the compound deposited in the plasma atmosphere can be cleaned, but the polysilane powder deposited in a large amount outside the plasma region cannot be cleaned. Therefore, it was impossible to significantly reduce the particles inside the reactor.

[0006]

[Means for Solving the Problems]
And NF₃As a result of diligent study focusing on the reactivity with 1
NF at temperatures above 50 ° C₃And polysilane react rapidly
Find out that, NF ₃Conventional cleaners using gas
Polysilane powder that could not be treated is used as a material for equipment such as electrodes.
An excellent way to self-clean without changing
I found it.

That is, according to the present invention, when an amorphous thin film is formed by plasma CVD (PECVD) using a silane compound as a raw material, polysilane powder generated in the apparatus is converted into NF _{3 in} a temperature range of 120 to 400 ° C. When removing an amorphous thin film by plasma CVD (PECVD) using a silane compound as a raw material, the amorphous thin film and polysilane powder deposited in the plasma region are heated at 120 to 400 ° C.
2. The method for cleaning a plasma CVD apparatus according to claim 1, wherein the plasma cleaning is performed in the temperature range of 1) and the plasma cleaning is performed simultaneously by using NF ₃ .

In the present invention, by heating and cleaning a portion where a large amount of polysilane is deposited (reactor wall portion, in the exhaust pipe in the vicinity of the reactor), the polysilane is deposited outside the plasma atmosphere which could not be conventionally cleaned. It completely cleans the polysilane. Although various methods such as a method of directly heating the reactor wall with a heater can be considered as a method of heating the deposit in the method, the method may be appropriately selected in consideration of the apparatus structure and the like. The heating temperature is 120 ° C or higher 4
The temperature may be any number up to about 00 ° C., but if the cleaning is performed at an excessively high temperature, the reaction between polysilane and NF ₃ causes heat generation, which may damage the material of the apparatus. Also,
When the temperature is low, the reaction speed becomes slow and the cleaning time becomes long. Therefore, it is preferable that the temperature of the polysilane deposition portion is optimally controlled to a temperature of 150 to 300 ° C.
Within this temperature condition, it is possible to completely clean the device material such as metal without damaging it. Also, NF ₃
The concentration and the flow rate of the above may be determined at an appropriate time by considering the deposition amount of polysilane powder, the vacuum pump capacity of the CVD apparatus, and the like. Considering leakage of NF ₃ gas from the reactor and the like, it is desirable that the cleaning be carried out under atmospheric pressure.

[0009]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to the examples.

Reference Example 1 SiH ₄ (500 SCCM) was used as a source gas and P
ECVD (RF power 500 W, substrate temperature 250 ° C., pressure 1 Torr) was performed. Yellowish white powder (polysilane powder) was deposited on the bottom of the reactor, in the pipe near the reactor and on the reactor wall. The powder was taken out and brought into contact with NF ₃ gas in the thermogravimetric analyzer (powder weight: 100 m
g, temperature rising rate: 1 ° C./min, pressure 760 Torr, N
As a result of F ₃ flow rate: 57 SCCM and temperature rising rate: 1 ° C./min), it was found that a rapid reaction occurs from 150 ° C.

Comparative Example 1 PECVD was performed in the same manner as in Reference Example 1. NF ₃ (500 SCCM, 1 Torr, 10
0 vol%, 300 minutes) was introduced. At the time of introduction, the inside of the reactor was observed through an observation window provided on the side wall of the reactor.
Further, the reactor wall and the like were not heated at the time of introduction (the temperature of the polysilane deposition portion: 30 to 40 ° C.). as a result,
The polysilane powder deposited inside the reactor could not be cleaned.

Comparative Example 2 PECVD was performed in the same manner as in Reference Example 1. NF ₃ (500 SCCM, 760 Torr,
100 vol%, 300 minutes) was introduced. At the time of introduction, the inside of the reactor was observed through an observation window provided on the side wall of the reactor. Further, the reactor wall and the like were not heated at the time of introduction (the temperature of the polysilane deposition portion: 30 to 40 ° C.). As a result, the polysilane powder deposited inside the reactor could not be cleaned.

Comparative Example 3 PECVD was performed in the same manner as in Reference Example 1. In the reactor, under the plasma atmosphere, NF ₃ (500 SCC
M, 1 Torr, 100 vol%, 300 minutes). At the time of introduction, the inside of the reactor was observed through an observation window provided on the side wall of the reactor. Further, the reactor wall and the like were not heated at the time of introduction (the temperature of the polysilane deposition portion: 30 to
40 ° C). As a result, the polysilane powder deposited in the plasma region near the high frequency electrode could be cleaned,
The polysilane powder deposited inside the reactor could not be cleaned.

Comparative Example 4 PECVD was performed in the same manner as in Reference Example 1. NF ₃ (500 SCCM, 1 Torr, 10
0 vol%, 300 minutes) was introduced. At the time of introduction, the inside of the reactor was observed through an observation window provided on the side wall of the reactor.
Further, the reactor wall was heated at the time of introduction, and the temperature of the polysilane deposition portion was heated to 100 ° C. As a result, the polysilane powder deposited inside the reactor could not be cleaned.

Comparative Example 5 PECVD was performed in the same manner as in Reference Example 1. NF ₃ (500 SCCM, 760 Torr,
100 vol%, 300 minutes) was introduced. At the time of introduction, the inside of the reactor was observed through an observation window provided on the side wall of the reactor. At the time of introduction, the reactor wall was heated to maintain the temperature of the polysilane deposition portion at 100 ° C. As a result, the polysilane powder deposited inside the reactor could not be cleaned.

Example 1 PECVD was performed in the same manner as in Reference Example 1. NF ₃ (500 SCCM, 1 Torr, 10
0 vol%) was introduced. At the time of introduction, the inside of the reactor was observed through an observation window provided on the side wall of the reactor. At the time of introduction, the reactor wall was heated to keep the temperature of the polysilane deposition portion at 120 ° C. As a result, the polysilane powder deposited inside the reactor could be completely cleaned in 90 minutes. Also, the reactor wall after cleaning was observed, but no corrosion or the like was observed.

Example 2 PECVD was performed in the same manner as in Reference Example 1. NF ₃ (500 SCCM, 1 Torr, 10
0 vol%) was introduced. At the time of introduction, the inside of the reactor was observed through an observation window provided on the side wall of the reactor. At the time of introduction, the reactor wall was heated to keep the temperature of the polysilane deposition portion at 150 ° C. As a result, the polysilane powder deposited inside the reactor could be completely cleaned in 40 minutes. Also, the reactor wall after cleaning was observed, but no corrosion or the like was observed.

Example 3 PECVD was performed in the same manner as in Reference Example 1. NF ₃ (500 SCCM, 1 Torr, 10
0 vol%) was introduced. At the time of introduction, the inside of the reactor was observed through an observation window provided on the side wall of the reactor. In addition, the reactor wall is heated at the time of introduction, and the temperature of the polysilane deposition part is adjusted to 4
It was kept at 00 ° C. As a result, the polysilane powder deposited inside the reactor could be completely cleaned in 5 minutes. Also,
The side wall of the reactor after cleaning was observed, but no corrosion was observed.

Example 4 PECVD was performed in the same manner as in Reference Example 1. NF ₃ (500 SCCM, 760 Torr,
100 vol%) was introduced. At the time of introduction, the inside of the reactor was observed through an observation window provided on the side wall of the reactor. Also,
At the time of introduction, the reactor wall was heated to maintain the temperature of the polysilane deposition portion at 150 ° C. As a result, the polysilane powder deposited inside the reactor could be completely cleaned in 12 minutes.
Further, the side wall of the reactor after cleaning was observed, but no corrosion was observed.

Example 5 PECVD was performed in the same manner as in Reference Example 1. NF ₃ (500 SCCM, 760 Torr,
100 vol%) was introduced. At the time of introduction, the inside of the reactor was observed through an observation window provided on the side wall of the reactor. Also,
At the time of introduction, the reactor wall was heated to keep the temperature of the polysilane deposition portion at 400 ° C. As a result, the polysilane powder deposited inside the reactor could be completely cleaned in 5 minutes. Further, the side wall of the reactor after cleaning was observed, but no corrosion was observed.

Comparative Example 6 PECVD was performed in the same manner as in Reference Example 1. NF ₃ (500 SCCM, 1 Torr, 10
0 vol%, substrate temperature on the electrode: 250 ° C.)
Plasma was generated. At the time of introduction, the inside of the reactor was observed through an observation window provided on the side wall of the reactor. At the time of introduction, heating of the reactor wall and the like was not performed. (Temperature of deposited portion of polysilane: 50 ° C.). As a result of cleaning for 300 minutes under the above conditions, the polysilane powder and the amorphous silicon film deposited in the plasma region near the electrode could be cleaned, but the polysilane powder deposited inside the reactor wall and piping outside the plasma region was cleaned. could not.

Example 6 PECVD was performed in the same manner as in Reference Example 1. NF ₃ (500 SCCM, 1 Torr, 10
0 vol%, substrate temperature on the electrode: 250 ° C.)
Plasma was generated. At the time of introduction, the inside of the reactor was observed through an observation window provided on the side wall of the reactor. During the introduction, the reactor wall was heated to keep the temperature of the reactor wall and the polysilane deposition portion in the pipe at 120 ° C. As a result, the polysilane powder deposited in the reactor could be cleaned in 90 minutes. The reactor wall after cleaning was observed, but no corrosion or the like was observed.

Example 7 PECVD was performed in the same manner as in Reference Example 1. NF ₃ (500 SCCM, 1 Torr, 10
0 vol%, substrate temperature on the electrode: 250 ° C.)
Plasma was generated. At the time of introduction, the inside of the reactor was observed through an observation window provided on the side wall of the reactor. At the time of introduction, the reactor wall was heated to keep the temperature of the reactor wall and the polysilane deposition portion in the pipe at 150 ° C. As a result, the polysilane powder deposited in the reactor could be cleaned in 40 minutes. The reactor wall after cleaning was observed, but no corrosion or the like was observed.

Example 8 PECVD was performed in the same manner as in Reference Example 1. NF ₃ diluted with N ₂ in the reactor (NF ₃ flow rate 500S
CCM, N ₂ flow rate 4.5 SLM, 760 Torr, 10
vol%) was introduced. At the time of introduction, the inside of the reactor was observed through an observation window provided on the side wall of the reactor. Also, the reactor wall is heated at the time of introduction to raise the temperature of the polysilane deposition portion to 15
It was kept at 0 ° C. As a result, the polysilane powder deposited inside the reactor could be completely cleaned in 23 minutes. Also,
The side wall of the reactor after cleaning was observed, but no corrosion was observed.

Example 9 PECVD was performed in the same manner as in Reference Example 1. NF ₃ diluted with N ₂ in the reactor (NF ₃ flow rate 500S
CCM, N ₂ flow rate 4.5 SLM, 1 Torr, 10 vo
1%) was introduced. At the time of introduction, the inside of the reactor was observed through an observation window provided on the side wall of the reactor. Also, the reactor wall is heated at the time of introduction so that the temperature of the polysilane deposition part is 150 ° C.
Kept at. As a result, the polysilane powder deposited inside the reactor could be completely cleaned in 45 minutes. Further, the side wall of the reactor after cleaning was observed, but no corrosion was observed.

Example 10 PECVD was performed in the same manner as in Reference Example 1. NF ₃ diluted with N ₂ in the reactor (NF ₃ flow rate 500S
CCM, N ₂ flow rate 4.5 SLM, 1 Torr, 10 vo
1%, substrate temperature on the electrode: 250 ° C.) was introduced to generate plasma. At the time of introduction, the inside of the reactor was observed through an observation window provided on the side wall of the reactor. At the time of introduction, the reactor wall was heated to keep the temperature of the reactor wall and the polysilane deposition portion in the pipe at 150 ° C. As a result, the polysilane powder deposited in the reactor could be cleaned in 45 minutes. The reactor wall after cleaning was observed, but no corrosion or the like was observed.

[0027]

According to the present invention, in plasma CVD using a silane compound as a raw material, it becomes possible to easily and easily clean the powder deposited in the apparatus.

[Brief description of drawings]

FIG. 1 shows a schematic view of a balanced plate type plasma CVD apparatus.

Claims (2)

[Claims] 1. When forming an amorphous thin film by plasma CVD using a silane compound as a raw material, polysilane powder generated in the apparatus is removed by reaction with NF _{3 in} a temperature range of 120 to 400 ° C. A characteristic method of cleaning a plasma CVD apparatus. 2. When forming an amorphous thin film by plasma CVD using a silane compound as a raw material, the amorphous thin film and polysilane powder deposited in the plasma region are heated to a temperature range of 120 to 400 ° C. and NF ₃ is used. 2. The method for cleaning a plasma CVD apparatus according to claim 1, wherein the plasma cleaning is performed at the same time.