The influence of feature-scale surface geometry on CMP processes

The influence of feature-scale surface pattern dimensions on chemical mecha nical polishing (CMP) processes has been studied through numerical simulati ons using a discretized geometry approach. The development of planarity for a symmetrical 3 X 3 array of square roughness elements with various latera l dimensions and spacing was simulated. Geometrical shielding of roughness elements by neighboring elements was found to cause asymmetrical surface po lishing during the CMP processes. Given a specified trench spacing, a stron ger doming effect was predicted for smaller sized protrusions. For a fixed feature size, the most significant doming effect was found to occur when th e trench width is comparable to the gap size between the pad and the protru sion. These effects can be associated with variations in the flow pattern o f the polishing slurry in the vicinity of the roughness elements. (C) 2000 The Electrochemical Society. All rights reserved.