DUAL CHAMBER PLASMA ETCHER WITH ION ACCELERATOR

摘要

The embodiments herein generally deal with semiconductor processing methods and apparatus. More specifically, the embodiments relate to methods and apparatus for etching a semiconductor substrate. A partially fabricated semiconductor substrate is provided in a reaction chamber. The reaction chamber is divided into an upper sub-chamber and a lower sub-chamber by a grid assembly. Plasma is generated in the upper sub-chamber, and the substrate is positioned in the lower sub-chamber. The grid assembly includes at least two grids, each of which is negatively biased, and each of which includes perforations which allow certain species to pass through. The uppermost grid is negatively biased in order to repel electrons. The lowermost grid is biased further negative (compared to the uppermost grid) in order to accelerate positive ions from the upper to the lower sub-chamber. Etching gas is supplied directly to the lower sub-chamber. The etching gas and ions react with the surface of the substrate to etch the substrate as desired.

主权项

1. An apparatus for etching a substrate, comprising:
(a) a reaction chamber, (b) a grid assembly positioned in the reaction chamber and thereby dividing the reaction chamber into an upper sub-chamber and a lower sub-chamber, wherein the grid assembly comprises at least an uppermost grid and a lowermost grid, (c) electrical connections with at least the uppermost and lowermost grids of the grid assembly for independently providing negative bias to the uppermost and lowermost grids, (d) one or more inlets to the upper sub-chamber, (e) one or more inlets to the lower sub-chamber, (f) a plasma generation source configured to produce a plasma in the upper sub-chamber, (g) one or more gas outlets to the lower sub-chamber configured to remove gas from the lower sub-chamber, and (h) a controller configured to provide instructions for:
(i) supplying a plasma generating gas to the upper sub-chamber and generating the plasma from the plasma generating gas,(ii) applying a negative bias to at least the uppermost and lowermost grids of the grid assembly, wherein the bias applied to the lowermost grid is more negative than the bias applied to the uppermost grid, and accelerating ions from the plasma in the upper sub-chamber through the grid assembly toward the substrate,(iii) supplying an etching gas to the lower sub-chamber, and(iv) etching the substrate to remove at least a portion of the material for removal,wherein the lower sub-chamber is substantially free of plasma during operations (i)-(iv).