Si/SiO2 etching in high density SF6/CHF3/O2 plasma

Response surface studies of Si and SiO2 etching in a radio-frequency-induction (RFI) plasma etcher have been conducted. Quantitative models were established to examine the variation of Si and SiO2 etch rates versus inductive power, bias power, O-2 flow, and SF6/CHF3 ratio. Equations for Si and SiO2 etching were derived from the experimental matrix and were found to be accurate to predict the etch rates in the studied parameter space. Effects of pressure on etch rates were also investigated. Etched surfaces were characterized with an atomic force microscope. The results provided the insight of the Si and SiO2 etching characteristics in the RFI-type high density plasma etcher. Based on the study of Si and SiO2 etch rates, the Si/SiO2 etch rate ratio was mapped out. By properly selecting a set of power and flow conditions in the studied parameter space, a planarization process with an etch rate ratio of 1:1 was established. (C) 1998 Elsevier Science S.A. All rights reserved.