Plasma processing apparatus

Abstract

In the plasma processing apparatus of the present invention, a first electrode (21) for connecting a high frequency electric power source (40) in a chamber is arranged to be opposed to a second electrode (5). A substrate (W) to be processed is placed between the electrodes. There is provided a harmonic absorbing member (51) for being able to absorb harmonics of the high frequency electric power source (40) so as to come in contact with a peripheral portion or circumference of a face of the first electrode 21, which is opposite the second electrode (5). The harmonic absorbing member absorbs the reflected harmonic before the harmonic returns to the high frequency electric power source. By absorbing the harmonic in this manner, the standing wave due to the harmonic will be effectively prevented from being generated, and the density of plasma is made even.

Description

TECHNICAL FIELD The present invention relates to a plasma processing apparatus for performing etching and film forming on a substrate such as a semiconductor substrate by plasma processing. BACKGROUND ART In a process for manufacturing semiconductor devices, various plasma processing such as etching, film forming by sputtering or CVD film forming (Chemical Vapor Depositing) have been frequently employed. There have been known various types of plasma processing apparatuses, among which a capacitive coupling type parallel plate plasma processing apparatus is the apparatus the most popularly distributed and used. This type of plasma processing apparatus has a pair of parallel flat plate electrodes (upper and lower electrodes) in a reduced-pressure chamber. A semiconductor wafer to be processed is placed between the electrodes, then process gas (treatment gas) is introduced into the chamber and electric power with high frequency is applied to one of the electrodes. A high frequency ...

AI Technical Summary

Benefits of technology

The present invention is intended to provide a plasma processing apparatus capable of making the density of plasma even by suppressing the unevenness of the electric field on the surface of an electrode in the plasma processing using high-density plasma with use of which a device can be formed finer.

In the plasma processing apparatus of the present invention, high frequency electric power is applied to the first electrode. There is provided a harmonic absorbing member for absorbing a harmonic of the high frequency electric power source so as to come into contact with a peripheral portion or circumference of a face of the first electrode, which is opposite to the second electrode. The harmonic absorbing member absorbs a harmonic reflected from plasma before the harmonic returns to the high frequency electric power source. By absorbing the harmonic in this manner, the standing wave due to the harmonic will be effectively prevented from being generated, and the density of plasma is made even. With such a structure, the standing wave due to the harmonic can be prevented to suppress the unevenness of the electric field on the surface of the electrode due to the standing wave, with the result that the density of plasma can be made even.

Problems solved by technology

There are also design rule constraints on features like the contact hole.

The conventional oxide film etching method is, therefore, beginning to be not good enough to satisfy the demands of the market.

Further, such a higher density of the plasma by the higher frequency remarkably causes non-linear characteristics of the plasma, so that a harmonic may be easily interposed on the reflected wave form the plasma.

If the electric field is made uneven in such a manner, the density of plasma will be also made uneven, with the result that the etching rate of etching will be uneven.

The above-mentioned problems in generating a high-density plasma, however, have not been recognized clearly, and thus a proposal for preventing the above-mentioned uneven electric field has not sufficiently been presented yet.

Further, reflection is caused at every portions within the box in which the electric power applying is disposed, and the resultant reflected harmonic backs to the surface of the upper electrode exposed to the plasma.

With this structure, the standing wave is generated on the plasma contacting face of the upper electrode by the interference, which makes the electric field on the electrode in the direction of the diameter uneven.

The unevenness of the electric field also makes the density of the plasma uneven, which causes an uneven etching rate.

However, as mentioned before, the problems in generating the high-density plasma, have not been recognized clearly, and thus a proposal for preventing the above-mentioned uneven electric field has not been sufficiently presented yet.

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