Plasma etch models based on different plasma chemistry for micro-electro-mechanical-systems application

Abstract

The suitability of different plasma etch models based on various plasma chemistry has been evaluated for the fabrication of micro-mechanical structures and micro-electro-mechanical systems. Different etch models have been described for silicon etching based on fluorine and chlorine chemistry and the mechanisms involved in SiO 2 etching. Conventional planar reactive ion etching systems have been utilized for the etching of SiO 2 and silicon based on fluorine and chlorine etch models. Fluorine containing gases such as CHF 3 in combination with Ar have been used for SiO 2 etching and achieved nearly vertical sidewalls with smooth bottom surface. Gas mixtures such as SF 6/O 2 at low substrate temperatures and Cl 2/BCl 3 have been used for silicon etching and sidewall passivation techniques have been employed to achieve vertical sidewalls. The usefulness of chlorine chemistry using BCl 3 gas chopping technique for the fabrication of high aspect ratio structures has been demonstrated.