Controlled Pulse-Etching with Xenon Difluoride

Abstract

INTRODUCTION XeF 2 is a member of a family of fluorine-based silicon etchants which includes ClF 3 , BrF 3 , BrF 5 , and IF 5 . All of these compounds can be used for vapor-phase chemical etching of silicon [1, 2]. XeF 2 was first used to study the mechanisms of fluorine etch chemistry on silicon [1, 3, 4] and was found to have high etch rates and reaction probabilities at room temperature. Because XeF 2 requires no external energy sources or ion bombardment to etch silicon, it exhibits high selectivity to many metals, dielectrics, and polymers used in traditional IC processing, making it easy to integrate with other processes, such as CMOS. XeF 2 is a white solid at room temperature and pressure. The rocksalt-sized crystals are available from most major chemical vendors and are shipped in teflon vials. The cost of high purity XeF 2 crystals (?9