BULK MICROMACHINED SILICON COMB-DRIVE ELECTROSTATIC ACTUATORS WITH DIODE ISOLATION

A simple bulk-micromachining process for the fabrication of comb-drive electrostatic actuators in single-crystal silicon is described. A p() etch-stop layer is first formed by boron ion implantation and diffus ion into an n-type (100) Si wafer. This layer is then patterned by rea ctive ion etching, and anisotropic wet chemical etching is used to cre ate an undercut structure that is free to move on a flexure suspension . In-plane mechanical motion is obtained by applying electrostatic for ces through comb-drive electrodes, using electrode isolation provided by inbuilt diode structures. Single-and double-axis laterally driven r esonant comb-drive actuators fabricated by this process are described. (C) 1997 Elsevier Science S.A.