Fully monolithic CMOS nickel micromechanical resonator oscillator

Abstract

A fully monolithic oscillator achieved via MEMS-last integration of low temperature nickel micromechanical resonator arrays over finished foundry CMOS circuitry has been demonstrated with a measured phase noise of −95 dBc/Hz at a 10-kHz offset from its 10.92-MHz carrier (i.e., output) frequency. The use of a side-supported flexural-mode disk resonator-array to boost the power handling of the resonant tank is instrumental to allowing adequate oscillator performance despite the use of low-temperature nickel structural material. Because the fabrication steps for the resonator-array never exceed 50°C, the process is amenable to not only MEMS-last monolithic integration with the 0.35 μm CMOS of this work, but also next generation CMOS with gate lengths 65 nm and smaller that use advanced low-k dielectric material to lower interconnect capacitance.