Method for cleaning inside of chamber using RF plasma

Details Method for cleaning inside of chamber using RF plasma Method for cleaning inside of chamber using RF plasma

1998-12-04

2001-10-23

Markoff, Alexander (Department: 1743)

Cleaning and liquid contact with solids

Processes

Including application of electrical radiant or wave energy...

C134S022100, C134S022180, C438S905000

Reexamination Certificate

active

06305390

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method for manufacturing a semiconductor device, and more particularly, to a method for cleaning the inside of a chamber using a radio frequency (RF) plasma.
2. Description of the Related Art
In order to form a film on the surface of a wafer when manufacturing a semiconductor device, a chemical vapor deposition (CVD) method based on a gaseous reaction within a vacuum chamber is used. However, when using CVD, a film of unwanted, contaminating reaction products or by products is deposited all over the inside of the chamber, and more importantly, on the surface of the wafer itself. These contaminants affect the physical and chemical properties of the film deposited on the wafer, and generate particles which further contaminate the wafer. It is therefore necessary to remove the unwanted reaction product deposited inside the chamber after a certain number of wafers have been processed. A cleaning method using a plasma has been used to remove the unwanted reaction product from the inside of the chamber.
According to the contaminants plasma cleaning method, a plasma gas source is supplied to the chamber to be cleaned, and an electric field is applied, causing a cathode to emit electrons. The emitted electrons collide with the source gas, generating a plasma consisting of electrons, cations and variety of neutral species. This plasma strikes against and cleans the inner surface of the chamber.
The state of the art plasma cleaning methods use a constant pressure and a constant RF power. However, only certain parts of the chamber are cleaned, permitting contaminating reaction products to accumulate on other parts of the chamber over many deposition and cleaning cycles. Also, since adhesion between the accumulated deposited materials is weak, over time the deposited materials separate from or fall off of the surface of the chamber generating particles that reduce semiconductor device yield.
In order to prevent the accumulation of the contaminating reaction products, the typical cleaning cycle, in which the chamber is cleaned once every nine wafers, may be reduced. However, frequent cleaning reduces throughput and is inefficient.
SUMMARY OF THE INVENTION
An objective of the present invention is to provide a cleaning method that cleans the entire inner surface of a chamber using a radio frequency (RF) plasma.
It is therefore an aspect of the present invention to provided a method for cleaning the inside of a chamber using a radio frequency (RF) plasma, that includes stabilizing the inside of the chamber so that the inner surface coated with accumulated layers of contaminants can be removed through cleaning. The inside of the chamber is then cleaned using the RF plasma while continuously varying the pressure inside the chamber.
When cleaning the inside of the chamber, the pressure of the chamber may be continuously varied within the range from about 100 m Torr to about 800 m Torr, preferably, from a high pressure in the range of about 600 m Torr to a low pressure in the range of about 150 m Torr.
In another aspect of the invention, the RF plasma is obtained by applying RF power that varies according to pressure changes in the chamber, which ranges from 150 W to 500 W. It is an advantage of the present invention that the cleaning step may be performed for less than 200 seconds.
In another aspect, cleaning is performed simultaneously with introducing an inert gas through the backside of a susceptor installed in the lower portion of the chamber in order to clean the bottom of the susceptor.
It is an advantage of the present invention that by varying pressure and RF power inside the chamber, all parts inside the chamber are cleaned.


REFERENCES:
patent: 4960488 (1990-10-01), Law et al.
patent: 5158644 (1992-10-01), Cheung et al.
patent: 6030902 (2000-02-01), Donohoe

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