Plasma processing apparatus

Abstract

The invention provides an inductively coupled plasma apparatus capable of disposing a parallel coil with a large number of total turns in a relatively small space. The present plasma processing apparatus comprises a processing chamber for subjecting an object to plasma processing, an inlet means for introducing a processing gas into the processing chamber, an evacuation means for evacuating an interior of the processing chamber, a sample stage for placing the object, a power supply means for generating plasma, and at least one induction coil connected to the power supply means, wherein the induction coil is formed by connecting a plurality of identical coil elements 101 in a parallel circuit-like arrangement, the induction coil being positioned so that its center corresponds to a center of the object, and wherein input ends 101 in of the coil elements 101 are arranged at equal angular intervals calculated by dividing 360° by the number of coil elements, the coil elements having a three-dimensional structure in a radial direction and a height direction along a surface of an annular ring with an arbitrary cross-sectional shape.

Description

[0001] The present application is based on and claims priority of Japanese patent application No. 2004-117894 filed on Apr. 13, 2004, the entire contents of which are hereby incorporated by reference. FIELD OF THE INVENTION [0002] The present invention relates to a plasma processing apparatus preferably used for etching objects or depositing films in the process of manufacturing semiconductor devices, liquid crystal display substrates or the like. DESCRIPTION OF THE RELATED ART [0003] Along with the miniaturization of semiconductor devices, process conditions (process window) of a plasma process that realizes uniform processing to be carried out across the whole wafer surface have become narrower, so there are increasing demands for plasma processing apparatuses having more complete control of the states of the processes. In order to answer to such demands, it is required a plasma processing apparatus capable of controlling the plasma distribution, the process gas dissociation and t...

AI Technical Summary

Benefits of technology

[0019] The above-mentioned problems can be solved by a configuration described below. That is, a plurality of induction coil elements in parallel connection is not simply disposed vertically or horizontally, but disposed to have a three-dimensional structure, to thereby solve the problem of coil space. Actually, for example, an annular insulating member (insulating ring) having a quadrangular cross-section, for example, is used to dispose four identical coil elements to the four planes of the insulating ring (the lower, inner, upper and outer planes). One coil element circuit extended from a power supply via a matching network is disposed at first on an upper plane of the insulating ring, runs along the outer plane forming a 90° turn, runs along the bottom plane forming a 90° turn, runs along the inner plane forming a 90° turn, and returns to the upper plane where it is connected to ground potential. In this case, the number of turns per one circuit is 90°×3=270° (¾ turns). A total of four coil circuits are disposed in the same manner at even circumferential angular intervals of 90°. At this time, the total number of turns is three. When the coil elements form a 90° turn on the upper plane, one coil circuit totals in 90°×4=360° (one turn), according to which the total number of turns is four. Similarly, by utilizing an insulating ring whose cross-sectional shape is polygonal with n faces (n>4), the number of turns per circuit can be increased. Moreover, by using the insulating ring with a quadrangular cross-section and increasing the turns on a single plane to more than 90°, the number of turns per circuit can be increased.

[0033] According to the present plasma processing apparatus, complete plasma uniformity across the circumferential direction can be achieved. Therefore, the plasma etch result is uniform in the circumferential direction, and since it is necessary only to consider the uniformity in the radial direction when determining plasma etching process conditions, the determination process is facilitated and prompt. As a result, the plasma processing performance and the controllability of the apparatus as a whole is enhanced, and it becomes possible to provide finer etching process with high throughput, and higher quality film deposition and surface treatment.

Problems solved by technology

It is desirable that the wafer etching is completely uniform across the wafer surface, but in actual, the reaction on the wafer surface is not completely uniform due to the non-uniform distribution of plasma, dissociated species and reaction products within the reaction chamber.

However, in an inductively coupled plasma processing apparatus, non-uniformity in the circumferential (azimuthal) direction occurs due to the configuration of the apparatus.

That is, a coil always has an end connected to the RF power supply and another end connected to ground, and this coil configuration causes plasma non-uniformity in the circumferential direction.

However, according to such arrangement, along with the increase of the number of coils, the power supply to the coils is restricted to be supplied only from the center of the arrangement, by which the limitation regarding the design of the apparatus becomes great.

The increased voltage causes the plasma to have better ignition property and low-density stability, but on the one hand, causes increase of damage caused by ion sputtering of the insulating member disposed between the induction coil and plasma.

On the other hand, design-related problems occur by the increased current, such as heating, the loss caused thereby, and current resistance of the variable capacitor used in the matching network.

The increase in voltage causes problems such as abnormal discharge, undesirable effect to plasma, and voltage resistance of the variable capacitor.

However, the difficulty of adopting a parallel coil is that the space for disposing the induction coil is limited from the viewpoint of apparatus design.

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