Investigation of Dry Plasma Etching of Silicon

Abstract

Meso-scale structures are formed on a silicon surface using a sulphur hexafluoride (SF6) based dry etching process. Etched feature parameters, including etch rate, trench profile, and selectivity are explored using an optical emission spectroscopy and a resonance hairpin probe. With increasing process power, the etch rate was observed to increase, which was correlated with an observed increase in intensity of fluorine emission. Damage of the photoresist with increasing power was observed and a marked increase in hydrogen (H) emission was found to indicate this fault. The electron density and the sidewall roughness were also found to increase with higher reactor power. The e-SF6 collisions contribute to the production of atomic fluorine, which etches the silicon by the dissociative ionization (SF+5 and F or SF+3 and F) and electron impact dissociation (SF5 and F).