Etching mechanisms of polymers in oxygen microwave multipolar plasmas

Abstract

A parametric study of polymer etching in an oxygen microwave multipolar plasma with independent rf wafer biasing is reported. The etch rate evolution as a function of atomic oxygen concentration, measured by actinometry, indicates a monolayer adsorption kinetics for the photoresist/oxygen system. Furthermore, a step-like variation in the etch rate with ion bombardment energy is observed. In the low-energy range, where sputtering effects are negligible, ion-induced chemical etching is the main etching component. In the high-energy range, an additional etching which exhibits sputtering behavior arises.