Ion to neutral control for wafer processing with dual plasma source reactor

Abstract

The disclosed techniques relate to methods and apparatus for etching a substrate. A plate assembly divides a reaction chamber into a lower and upper sub-chamber. The plate assembly includes an upper and lower plate having apertures therethrough. When the apertures in the upper and lower plates are aligned, ions and neutral species may travel through the plate assembly into the lower sub-chamber. When the apertures are not aligned, ions are prevented from passing through the assembly while neutral species are much less affected. Thus, the ratio of ion flux:neutral flux may be tuned by controlling the amount of area over which the apertures are aligned. In certain embodiments, one plate of the plate assembly is implemented as a series of concentric, independently movable injection control rings. Further, in some embodiments, the upper sub-chamber is implemented as a series of concentric plasma zones separated by walls of insulating material.

Description

technical field [0001] The present invention generally relates to the field of semiconductor manufacturing, and more particularly to the control of the ratio of ions to neutral species in a dual plasma source reactor for processing wafers. Background technique [0002] One operation that is frequently used in semiconductor manufacturing is the etching operation. In an etching operation, one or more materials are partially or completely removed from a partially fabricated integrated circuit. Plasma etching is often employed, especially where the geometries involved are small, employ high aspect ratios, or require delicate pattern transfer. Typically, plasmas contain electrons, ions and free radicals. Free radicals and ions interact with the substrate to etch features, surfaces and materials on the substrate. [0003] As device dimensions shrink, plasma etch processes need to become increasingly precise and uniform in order to produce high-quality products. One driver for ...

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Problems solved by technology

[0004] Because different processes are optimized in different ways, what is suitable for the first etch process may not be suitable for the second etch process

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