JPH0590229A - Plasma processor - Google Patents

Abstract

PURPOSE:To increase the productivity and the yield of semiconductor device manufacturing step by easily cleaning the whole inner wall of a processing chamber and an evacuation tube. CONSTITUTION:A cleaning electrode 10 is provided on the lower part of a processing chamber 1 and inside an evacuation tube 6 to be impressed with high-frequency so that the plasma 11 of a cleaning gas may be produced in these parts to etch away the deposited films on the inner walls.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a processing chamber of a plasma processing apparatus for manufacturing semiconductor devices, and more particularly to a plasma processing apparatus suitable for cleaning the inner wall of the processing chamber with plasma.

[0002]

2. Description of the Related Art In the manufacturing process of semiconductor devices, processes using plasma such as film formation and etching are often used. In these processes, a processing gas (film forming gas, etching gas, etc.) is introduced into the processing chamber, and this is turned into plasma, and the ions and active species generated here are introduced onto the wafer and reacted. At this time, since the ions and active species diffuse to every corner of the processing chamber, a film is deposited not only on the wafer but also on the inner wall of the processing chamber. The film deposited on the inner wall increases in thickness as the number of treatments increases, and eventually peels off. The peeled film floats in the processing chamber and may fall on the surface of the wafer being processed, which causes defects.
With the increase in the density of semiconductor devices, it is important to thoroughly remove foreign substances (peeled films). Therefore, conventionally, the process chamber is sometimes opened to remove the film on the inner wall. Performing this operation is not preferable because dust and water in the air are introduced into the processing chamber. Therefore, as a method of removing this film without opening the processing chamber, a cleaning gas was introduced into the processing chamber to generate plasma to remove the film by etching. However, in the conventional processing apparatus, as disclosed in Japanese Patent Laid-Open No. 62-43335, the plasma does not spread over the entire area of the processing chamber, resulting in a portion that cannot be removed by etching.

[0003]

In the above-mentioned prior art, there is a problem that the film is deposited on the entire inner wall of the processing chamber, but the etching removal by the plasma is limited to the range exposed to the plasma. That is, the wall surface of the portion that is not in contact with plasma cannot be cleaned.

An object of the present invention is to provide a means for cleaning the entire inner wall of the processing chamber by means of generating plasma throughout the processing chamber.

[0005]

In order to achieve the above object, the present invention provides a means for generating a plasma for cleaning separately from the means for generating a plasma used for processing a wafer. A plasma is generated throughout the chamber.

[0006]

In the plasma processing chamber of the semiconductor device, the plasma used for wafer processing is generated on the wafer.
Therefore, the back side of the wafer mounting electrode and the inside of the exhaust pipe are not in contact with the plasma. Therefore, it is necessary to generate plasma in these portions by another means.

Since the processing chamber and the exhaust pipe are usually connected to the ground, an electrode which is to be the cathode is provided separately using this as an anode. If a high frequency is applied to this electrode, the cleaning gas is plasmatized on the back side of the wafer mounting electrode and inside the exhaust pipe, and the film deposited on the inner wall can be removed by etching.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIG. In FIG. 1, the processing chamber 1 is evacuated to vacuum through an exhaust pipe 6 by a vacuum exhaust system (not shown), and the processing gas whose flow rate is adjusted by a gas flow rate controller (not shown) is introduced into the processing chamber 1 and a predetermined amount is introduced. Hold on to pressure. Microwave is introduced here (the introduction mechanism is not shown)
Plasma 2 for processing the wafer 3 is generated and the wafer 3 is processed (film formation, etching, etc.). At this time,
A high frequency is applied to the electrode on which the wafer 3 is mounted in order to attract ions from the processing plasma 2 in order to improve the processing speed. This electrode is composed of a high frequency applying electrode 4, an insulator 5 and an earth shield 13.
A high frequency power source 9 for bias applies a high frequency during processing. On the other hand, the earth shield 13 is grounded.
The ions and active species generated in the processing plasma 2 not only process the wafer 3, but also diffuse into the processing chamber 1 and the exhaust pipe 6, and a film is deposited on this inner wall. It is necessary to remove this film because it peels off from time to time and floats in the processing chamber, which adversely affects the processing as foreign matter.

However, since the processing plasma 2 cannot enter the lower part of the processing chamber 1, around the earth shield 13 or the inside of the exhaust pipe 6, even if a cleaning gas is introduced and discharged as it is, It is impossible to etch away the film deposited on the part. In order to clean this portion, the cleaning electrode 7 is provided in the exhaust pipe 6.
At the bottom of the processing chamber 1 (processing chamber wall and earth shield 13
The cleaning electrode 10 is provided between the two) and is connected to the cleaning high frequency power source 8 to apply a high frequency. Since the processing chamber is grounded and the earth shield 13 is also grounded, the cleaning gas is discharged between the cleaning electrodes 7 and 10 and the inner wall of the processing chamber or the inner wall of the exhaust pipe to generate the cleaning plasma 11. To do. The cleaning plasma 11 and the processing plasma 2 can easily remove all the films deposited on the inner wall of the processing chamber or the exhaust pipe by etching. Every time a wafer is processed by this method,
It becomes possible to perform cleaning, and no film is deposited on the inner wall of the processing chamber.

[0010]

According to the present invention, since the entire surface of the inner wall of the processing chamber of the plasma processing apparatus can be easily cleaned, the generation of foreign matters can be suppressed, the yield can be improved, and the cleaning procedure can be simplified to improve the productivity. Can be achieved.

[Brief description of drawings]

FIG. 1 is a sectional view of an embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Processing chamber, 2 ... Processing plasma, 3 ... Wafer, 4 ... High frequency applying electrode, 5 ... Insulator, 6 ... Exhaust pipe, 7 ... Cleaning electrode, 8 ... Cleaning high frequency power supply, 9 ... Bias high frequency power supply , 10 ... cleaning electrode, 11 ... cleaning plasma, 12 ... ground, 13 ... earth shield.

Claims (1)

[Claims] 1. A plasma processing apparatus comprising: a processing chamber having a structure for holding a vacuum; a means for introducing a processing gas into the processing chamber; and a means for generating and maintaining plasma in the processing chamber. And a plasma generating mechanism for cleaning the inner wall of the processing chamber with plasma.