Measurements of desorbed products by plasma beam irradiation on SiO2

A plasma beam irradiation apparatus with a controllable plasma source was constructed to investigate the plasma-surface interactions for reactive etching processes. The apparatus can control the plasma parameters, such as ion energy, radical∕ion composition, and the ratio of neutral to ion flux. The desorbed products of SiFx (x=1–3) were observed separately from COFx (x=1–3) by using a C13F4–Ar gas mixture plasma beam. The major desorbed product was not SiF4. Unsaturated fluorinated silicons [SiFx(x=1–3)] were major desorbed products under ion-rich fluorocarbon plasma etching condition. It was found that the composition of silicon containing desorbed products does not depend on the incident ion energy in the ion energy range of 300–700eV.