Plasma processing apparatus and method of designing the same

Abstract

Disclosed is a plasma processing apparatus having a plasma producing portion and a porous plate provided between the plasma producing portion and an object to be processed, wherein the porous plate has a plurality of holes which are made non-uniform with respect to at least one of shape, size and disposition. Specifically, the shape, the size or the disposition of the holes is determined on the basis of an active species distribution at the plasma producing portion and of diffusion calculation, so that plasma active species adjacent the object to be processed has desired concentration and distribution. This assures uniform plasma distribution adjacent the object while a decrease of plasma density can be well suppressed.

Description

FIELD OF THE INVENTION AND RELATED ART [0001] This invention relates generally to a plasma processing apparatus such as, for example, an etching apparatus, a nitriding apparatus or an oxidation apparatus, for example, to be used in a semiconductor manufacturing process for semiconductor substrate or liquid crystal substrate, for example. More particularly, the invention concerns a plasma processing apparatus by which the amount of plasma active species or active molecules adjacent a substrate (object to be processed) can be made into desired density (or concentration) and distribution. [0002] For improved yield of chips to be produced on a semiconductor substrate, the process uniformity over the semiconductor substrate surface is very important in plasma processing apparatuses. In order to accomplish the process uniformity over the semiconductor substrate surface, many attempts have been made in plasma processing apparatuses. Use of a porous plate is an example. [0003] As an example...

AI Technical Summary

Benefits of technology

[0008] It is another object of the present invention to provide a plasma processing apparatus having a porous plate which is incorporated therein and which is effective to make uniform a plasma distribution adjacent an object to be processed, while suppresssing plasma density decrease, still very easily without relying on trial and error.

[0012] Briefly, in accordance with the present invention, a porous plate having holes which are non-uniform with respect to shape, size and / or distribution is used, by which various densities and distributions of plasma active species can be provided. Particularly, the shape, size and distribution of the holes may be determined in accordance with the active species distribution at the plasma producing portion and with diffusion calculation. This effectively removes the necessity of huge time and efforts required by the trial and error works, and a porous plate that assures desired plasma active species density and distribution can be accomplished easily and conveniently.

Problems solved by technology

Although this prior art example is suitably applicable to a case wherein a thin film is to be uniformely deposited on a semiconductor substrate, it is unsuitable to a case, such as etching, wherein a semiconductor is to be processed with relatively low pressure.

However, if the slot antenna is designed to provide approximately uniform microwave transmission distribution, although this enables that uniform microwave plasma is produced at underneath the microwave transmission window in a particular restrited condition, but in other conditions it is difficult to produce uniform microwave plasma there.

This caused enlargement of the substrate processing time.

On the other hand, relatively large holes were used to decrease the contact area with the plasma to suppress the plasma decrease, but the attribution of each hole became large and huge time and effort were spent by trial and error.

Thus, it was impractical.

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