Pattern shape effects and artefacts in deep silicon etching

Abstract

Deep silicon etching in an inductively coupled plasma (ICP) reactor offers a high etch rate (7 μm/min), nearly vertical profile with simple oxide masking. Test structures with patterns of different sizes (from a few microns to over 100 μm) and shapes (square and circular holes and trenches of variable width/length) have been etched to depths up to 500 μm. Long narrow features are etched faster than wide short features, indicating the three-dimensional nature of the reactive ion etching lag. Experiments have been done for many different etch times in order to understand aspect ratio dependence of deep etching. Simple flow conductance model explains most of the observed aspect ratio and feature size dependence.