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. A method of etching a substrate, comprising:
(a) receiving a substrate having removable material in a reaction chamber of a reactor, (b) supplying a plasma generating gas above a grid assembly in the reaction chamber, the grid assembly comprising an uppermost grid and a lowermost grid, and generating a plasma from the plasma generating gas above the grid assembly, (c) simultaneously applying a first negative bias and a second negative bias respectively to the uppermost and lowermost grids of the grid assembly, wherein the second negative bias applied to the lowermost grid is more negative than the first negative bias applied to the uppermost grid, and accelerating ions from the plasma through the grid assembly toward the substrate, (d) supplying an etching gas below the grid assembly, and (e) etching the substrate to remove at least a portion of the removable material,wherein an area below the grid assembly is substantially free of plasma during operations (a)-(e).