Damage-free reactive ion etching of silicon in NF 3 at low temperature

Abstract

Reactive ion etching (RIE) of silicon in a nitrogen trifluoride (NF 3) plasma is studied at temperatures between +20 and −140°C. The etch rates decrease with decreasing temperature and follow an Arrhenius-type dependence below −70°C. Cross-sectional transmission electron microscopy gives evidence that the low temperature RIE in NF 3 does not create crystallographic damage in the silicon. Low sample temperatures during RIE promote smoothness of the etched silicon surfaces and anisotropy of the etched profiles.