Plasma processing apparatus with reduced parasitic capacity and loss in RF power

Abstract

A plasma processing apparatus comprises a grounded housing, a thin RF plate electrode, an opposite electrode facing the RF plate electrode, and a RF power source for applying a radio frequency to either the RF plate electrode or the opposite electrode to produce plasma between the two electrodes. If the radio frequency applied to the electrode is f (MHz), the parasitic capacity C (pF) between the grounded portion of the housing and a conductive portion through which the radio frequency propagates is less than 1210*f<-0.9>. The thickness of the RF plate electrode is 1 mm to 6 mm, and it is supported by a heat sink. The heat sink has a coolant passage in the proximity to the RF plate electrode. The heat sink also has a groove or a cavity in addition to the coolant passage, thereby reducing the value of the dielectric constant of the heat sink as a whole.

Description

[0001] The present patent application claims the benefit of earlier Japanese Patent Application No. 2000-195165 filed Jun. 28, 2000, the disclosure of which is herein incorporated entirely by reference.[0002] 1. Field of the Invention[0003] The present invention relates to a plasma processing apparatus for producing plasma under application of a radio frequency and for carrying out etching or CVD processes.[0004] 2. Description of the Related Art[0005] A parallel plate type plasma etching apparatus is generally used in semiconductor manufacturing processes. In the conventional plasma etching apparatus, a radio frequency of about 13.56 MHz is applied to the cathode electrode to excite plasma. However, in order to keep up with increasingly strict design rules, and in order to respond to a demand for improvements in productivity, techniques of applying a higher range of radio frequency, e.g., the frequency band of VHF to UHF have been studied. The proposal of raising the radio frequenc...

AI Technical Summary

Benefits of technology

This configuration maintains high plasma density and reduces RF power loss, ensuring precise etching and increased productivity while protecting the DC power source.

Problems solved by technology

However, as the frequency applied to the electrode becomes higher, the loss of RF power also increases.

If the loss of RF power increases, the electron density of plasma produced between the parallel plate electrodes decreases, lowering the etching rate.

Consequently, a wafer cannot be precisely etched into a designed shape and pattern.

This means that the loss of the RF power also increases.

The most significant example of loss due to the raised radio frequency is the growth in parasitic capacity relative to the capacity of produced plasma.

This means that, apart from that used for producing and maintaining plasma, the RF power supplied to the apparatus is wasted.

Another problem in the conventional plasma processing apparatus is the parasitic capacity existing between the RF mount electrode 4 and the pusher pins 12.

This parasitic capacity causes a loss in RF power.

Such a loss becomes particularly marked if the applied radio frequency is 60 MHz or higher.

Accordingly, the reduction of parasitic capacity is one of the most serious problems to be solved.

Still another problem in the conventional apparatus is the loss of RF power from the electrostatic chuck.

The radio frequency flowing into the low pass filter 13 may cause the break down or burning of the low pass filter, and may damage the DC power source 11.

Consequently, the heat sink becomes brittle and is likely to break.

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