Properties of deep etched trenches in silicon: Role of the angular dependence of the sputtering yield and the etched species redeposition

Abstract

A Monte–Carlo etching simulation code modelling the temporal evolution of a silicon substrate submitted to a SF 6/O 2 plasma mixture was developed to complete and improve the experimental results found in an induced coupled plasma reactor (ICP). It reproduces the different plasma–surface interaction mechanisms occurring during this kind of process, predicts the trench profile evolution, calculates the etching rates and gives the chemical composition on the sidewalls. It is also a powerful tool for scientific investigation, with the possibility to add and test new surface processes, which cannot be directly controlled or measured by experiments. The object of this article is to investigate the role of two of them: the angular dependence of the sputtering yield and the redeposition of the sputter products. The study is focused on their topographic and kinetic consequences, and reveals that these mechanisms can explain some common defects appearing like microtrenching and faceting.