UHF Nickelmicromechanical Spoke-Supported Ring Resonators

A micromechanical vibrating spoke-supported ring resonator fabricated in a low deposition temperature nickel metal material has been demonstrated in two vibration modes spanning frequencies from HF (18 MHz) to UHF (425.7 MHz) with Q's as high as 6,405 and 2,467, respectively. The use of an anchor isolating spoke-supported ring geometry along with notched support attachments between the ring structure and supporting beams contributes to demonstration of the highest reported vibrating frequency to date for any macro or macro-scale metal resonator, making this the first metal micromechanical resonator suitable for RF applications. Because the nickel structural material is deposited at 50degC, the fabrication process for this resonator is quite amenable to post-processing over finished foundry CMOS wafers, even ones with gate lengths below 65 nm slated to use advanced low-k (but low melting point from 300-400degC) dielectric material around their metals. This makes nickel structural material an attractive choice for low cost post-transistor single-chip integration of high Q vibrating passives with transistor circuits for wireless applications.