Porous silicon technique for realization of surface micromachined silicon structures with large gaps

Abstract

The characteristics of vibrating microsystems are strongly influenced by air damping. With a porous silicon (PorSi) sacrificial layer technique, the substrate gap is enhanced by a factor of >10 to obtain high Q. Test structures with substrate gaps up to 100 μm and roughness <100 nm were realized. Q factor measurements with electrostatic-driven test structures demonstrating a Q factor increase of about 100% at ambient pressure are presented and discussed.