Anisotropic plasma etching of Silicon in gas chopping process by alternating steps of oxidation and etching

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In the present work a two-stage process for deep anisotropic etching of Silicon based on alternating steps of etching in SF6 plasma and passivation of Silicon surface by oxidation in O2 plasma is proposed. This developed Ox-Etch process has advantages of being free from deposited polymers on sidewalls and does not use cryogenic equipment. Etched structures show anisotropic profile with vertical scalloped walls similar to Bosch and STiGer processes. Selectivity of Silicon etch process with respect to SiO2 mask is up to 120:1. The investigations of etching results depending on process parameters are presented. Main control parameters for Ox-Etch process defining the etch rate and degree of anisotropy are the durations of etch and oxidation steps.