One-port active polysilicon resonant microstructures

Theoretical and experimental characteristics of a two-terminal, or one-port, resonant microstructure are discussed. An equivalent circuit model that is useful for design and analysis of these devices is presented. This model is verified by experimental measurements, with a worst-case error between model and experimental parameters of 30%. A process for integrating polysilicon resonant microstructures with on-chip NMOS (N-metal oxide semiconductor) circuitry is also described. A novel feature of this process is the use of rapid thermal annealing (RTA) for strain-relief of the non-implanted phosphorus-doped polysilicon. The RTA-strain-relieved polysilicon has a Young's modulus of 0.9.10/sup 12/ dynes/cm/sup 2/ and residual strain of 0.002% as measured by resonant frequency techniques. This low value of strain indicated that RTA is a useful strain-relief technique.<>