Microfabrication using germanium-based release masks

Abstract

A method of fabricating MicroElectroMechanical systems. The method includes: providing a substrate in which electrical interconnections and a sacrificial layer have been formed, forming a release mask including germanium, etching exposed sacrificial material, and removing the release mask. The performance of MicroElectroMechanical devices is improved by ) integrating electronics on the same substrate as the mechanical elements, ) increasing the proximity of electronics and mechanical elements, ) increasing the undercut of a release etch to reduce or eliminate etch holes or to allow circuit elements to be undercut, ) increasing the yield and reliability of the MEMS release processes. In addition to released mechanical structures, the invention also provides a means for forming circuits such as a bandgap reference as a released MEMS element. Forming a bandgap circuit as a released MEMS element may improve reference voltage performance by allowing resistive heating of the circuit region to a constant, elevated temperature independent of the substrate temperature.