Enhancement in CMOS-MEMS Resonator for High Sensitive Temperature Sensing

This paper presents the enhancement in frequency shift per Celsius for high-temperature sensitive applications of microresonators. Using materials with different coefficients of thermal expansion in a substrate and beam, larger axial load on fixed ends are demonstrated. This results in a larger frequency shift with the increase in the ambient temperature. An analytical model is presented that closely matches simulation and measurement results. The 120-μm CMOS-MEMS fixed-fixed beam resonators, consisting of multiple metal, dielectric layers, and polysilicon layer, were designed and measured with a center frequency around 640 kHz. A sensitivity up to -2983 Hz/°C is achieved without sacrificing stiffness constant.