A sub-micron capacitive gap process for multiple-metal-electrode lateral micromechanical resonators

Abstract

A fabrication process has been demonstrated that combines polysilicon surface micromachining, metal electroplating, and a sidewall sacrificial-spacer technique, to achieve high-aspect-ratio, submicron, lateral capacitive gaps between a micromechanical structure and its metal electrodes, without the need for advanced lithographic and etching technology. Among the devices demonstrated using this process are lateral free-free beam micromechanical resonators (Q=10,470 at 10.47 MHz), contour mode disk resonators (Q=9,400 at 156 MHz), and temperature-compensated micromechanical resonators (Q=10,317 at 13.5 MHz, with a -200 ppm frequency variation over a full 80/spl deg/C range).