Surface Damage on Si Substrates Caused by Reactive Sputter Etching

TLDR

Reactive sputter etching (RSE) induces surface damage on silicon substrates, comprising layers of contamination (C, F, O), mixed C/defect, and defect layers, with damage severity increasing with power density and etching time, and defect‑free conditions identified at 0.4 W cm⁻² for 1 min. TEM and RHEED observations classified RSE‑induced defects into four categories—precipitates surrounded by elastic strain fields, surface roughness patterns, polycrystalline/amorphous silicon, and a defect‑free state—ordered by increasing destruction. Precipitates deeper than 500 Å were found to cause OSF, and the extent of defects and contamination grows with higher power density and longer etching, with defect‑free conditions achieved at 0.4 W cm⁻² for 1 min.

Abstract

Surface damage on silicon substrates caused by RSE has been investigated. Defects are classified into four categories in order of destruction, namely, precipitates surrounded by elastic strain field, surface roughness pattern, polycrystalline and amorphous silicon, and no defects, based on the results of TEM and RHEED observation. In particular, precipitates which reach a depth more than 500 Å were found to cause OSF. The surface damage consists of contamination (C, F, O) layer, C and defect mixed layer, and defect layer in order from the top. The degree of these defects and contaminations expand with increasing power density and etching duration. RSE conditions, where no defects are formed, were determined, e.g. , within 1 minute at 0.4 W cm -2 .