Compact Modeling of MEMS Resonators

摘要

The main accomplishment of this project was the development, for the first time, of a compact transient large-signal MEMS resonator model for large- scale integration of resonators and transistors. The four quarterly milestones, including electrical/mechanical/thermal characterization, preliminary resonator model, electrical/mechanical/thermal validation, and extended resonator model, were all met. MEMS cantilever resonators were fabricated at Nanyang Technological University in Singapore by using a novel low-temperature wafer bonding process to realize 3D features that could not be realized in a single silicon wafer. The simple and relatively large design facilitated model development and validation. Using well-known characteristics of silicon, only the thickness of the cantilever was fine-tuned to match the modeled and measured resonance frequencies. A compact transient large-signal resonator model was developed and coded in Verilog-A, so that it could be readily installed in different circuit-design environments such as ADS and Cadence. The effects of DC-bias and AC-drive levels and frequencies were simulated in both time and frequency domains. The model validation was mostly through mechanical characterization by using a laser Doppler vibrometer. Electrical validation was more difficult due to high leakage current associated with the silicon substrate. Thermal validation was inaccurate due to weak temperature dependence.