Secondary Ion Analysis of Silicon under Ar+ Ion Etching in Chlorine and Fluorine Flux

Abstract

Secondary ion analysis was performed on a silicon surface during Ar⁺ ion bombardment under simultaneous exposure to chlorine or fluorine flux. The Cl⁺, Cl₂ ⁺, F⁺ and F₂ ⁺ secondary ion intensities increased with the amount of reactive gas flux. However, other secondary ion intensities, such as SiCl⁺ and SiF⁺, decreased at large reactive gas flux. In a large reactive gas flux, the Cl⁺ and F₂ ⁺ secondary ion intensities were related to the Si etching yield. The amounts of reactive atoms adsorbed on one silicon atom are the same in the large reactive gas flux region. The etching rate ratios of silicon, silicon dioxide and silicon nitride had almost the same value, no matter how much the Cl₂ flux increased. No dependence of the etching rate on the crystalline orientation was observed.