Isotropic Plasma Etching of SiO2 Films

Abstract

The isotropic etching of SiO2 with an SF6–O2 plasma is studied experimentally. It is shown that the key factors in the process are the total and partial pressures of SF6 and O2 and the RF power. A smoothed-down edge profile of contact windows is obtained if SF6 and O2 are mixed in a ratio of 1 : 10 to 1 : 5. The maximum etch rate is achieved at total pressures of 250 to 450 Pa.