Fabrication of high aspect ratio structures using chlorine gas chopping technique

Abstract

This article reports on the development of dry etching technology which will offer the potential to fabricate high aspect ratio structures in silicon for Micro Electro Mechanical Systems (MEMS) fabrication, using chlorine chemistry. In this study, we report about our investigations on the etching mechanisms using gas chopping technique. Chlorine with BCl3, as chopping gas for scavenging was the basis for deep trench etching in silicon. A conventional planar RIE (Reactive Ion Etching) reactor has been used. We optimised the process parameters as per our reactor's configuration to have compromise for best selectivity, anisotropy and high etch rates, which was obtained at BCl3 gas chopping time of 2 to 4 minutes, with DC-bias of −200 to −300 Volts.