Topological effects regarding trench structures covered with LPCVD and PECVD thin films

Abstract

Abstract Previous experimental as well as theoretical studies on the coverage of trench and edge structures of microelectronic devices by thermally activated chemical vapour deposition (CVD) processes have shown a fundamental difference in the behaviour of the convex (top) and concave (bottom) edges of a step not depending on either the special type of CVD process or the kind of deposited films. With increasing CVD film thickness the curvature decreases at a convex edge whereas the concave edge tends to form and preserve a “sharp edge” configuration with a “growth anomaly” following the location of the sharp edge in time. This paper also takes into consideration films deposited by plasma-enhanced CVD (PECVD) processes and demonstrates that there is no significant difference concerning the topological phenomena. Because PECVD processes generally have higher deposition rates (rate constants) that the corresponding thermally activated low pressure CVD processes, an enhanced thickness non-uniformity within narrow trenches overlaps the edge behaviour.