Effect Plasma Transport on Etched Profiles with Surface Topography in Diverging Field Electron Cyclotron Resonance Plasma

Abstract

Recent studies of electron cyclotron resonance (ECR) plasma etching for fabricating fine patterns of less than a half-micron indicate a serious problem in the etched profiles caused by a charge build-up of the patterns. The relationships between the local pattern distortion and the plasma properties measured by the electrostatic probe are investigated. Lowering the electron temperature perpendicular to the surface normal is one of the most effective techniques for eliminating the local side etch. It is enhanced by setting the wafer at the lower magnetic field. As the large space charge bends the ion trajectories, the higher ion current density also enhances the local side etch. The distribution of plasma potential which accelerates the ions can reduce the local side etch in spite of the higher current density.