Highly Sensitive Temperature Sensor Based on Coupled-Beam MN-on-Si MEMS Resonators Operating in Out-of-Plane Flexural Vibration Modes

This paper reports a type of highly sensitive temperature sensor utilizing AlN-on-Si resonators with coupled-beam structures of double- and triple-ended-tuning-fork (D/TETF). For both resonators, the out-of-plane flexural mode is adopted as it favors the effect of thermal mismatch between the composite layers inherent to the AlN-on-Si structure and thus helps attain a large temperature coefficient of resonant frequency (TCF). The analytical model to calculate TCF values of D/TETF AlN-on-Si resonators is provided, which agrees well with the finite-element simulation and experimental results. The resonant temperature sensor is built by closing the loop of the AlN-on-Si resonator, a transimpedance amplifier, a low-pass filter, and a phase shifter to form an oscillator, the output frequency of which shifts proportionally to the ambient temperature. The measured sensitivities of the temperature sensors using D/TETF resonators are better than -1000 ppm/degrees C in the temperature range of 25 degrees C similar to 60 degrees C, showing great potential to fulfill the on-chip temperature compensation scheme for cofabricated sensors.

Automated summary

This paper presents a highly sensitive temperature sensor using AlN-on-Si resonators with coupled-beam structures. The out-of-plane flexural mode is utilized to achieve a large temperature coefficient of resonant frequency. The measured sensitivities in the temperature range of 25°C to 60°C show great potential for on-chip temperature compensation scheme for cofabricated sensors.