An etch hole-free process for temperature-compensated, high Q, encapsulated resonators

Abstract

A process is presented for the fabrication of high quality factor (Q), temperature-compensated silicon resonators without release-etch perforations within the epitaxial polysilicon encapsulation (epi-seal). Electrostatically actuated Lamé-mode square resonators up to 400 μm wide with frequencies from 8 to 107 MHz are released with no etch perforations, resulting in high f-Q products of up to 2e13 Hz. Temperature compensation with a turnover point is achieved using an epitaxially grown, highly boron-doped device layer.