Structural Effects on a Submicron Trench Process

Recently, silicon trenches have been widely used for device isolation or three-dimensional capacitors in dynamic memories. In this work, trenches with submicron openings have been fabricated and several structure-dependent effects were discovered. A reactive ion etching rate in the vertical direction inside a trench decreases significantly as the aspect ratio (depth/width) becomes larger. A bottle-shaped profile due to undercutting starts to appear with trenches whose openings are smaller than a micrometer and becomes worse as the width decreases. A film thickness on sidewalls for refilling trenches shows no strong dependence on the structural aspect when chemically vapor deposited at low pressure. © 1985, The Electrochemical Society, Inc. All rights reserved.