Temperature-Insensitive Silicon Resonant Pressure Sensor By Thermal Stress Control

A temperature-insensitive silicon resonant pressure sensor is developed with an extremely low temperature coefficient of frequency (TCF). A novel self-compensation method is proposed to counteract the effect of the elastic modulus temperature coefficient (TCE) of silicon on the TCF by the thermal stress generated by vacuum packaging layers. On this basis, a positive TCFS shift is introduced by thermal tensile stress, and a negative TCFE shift is introduced by the TCE of silicon. The TCFS shifts can be adjusted as close as possible to the value of- TCFE by adjusting the thickness of the diaphragm and resonator, sharply decreasing the total TCF. The resonant pressure-sensing chip is fabricated using micromachining technology. Experimental results show that the maximum TCF value of the proposed resonant pressure sensor is 7.3 ppm/degrees C (that is, 0.46 Hz/degrees C). Moreover, its nonlinearity after polynomial compensation is better than 0.01% FS at the temperature ranging from -10 degrees C to +60 degrees C. (C) 2021 Elsevier B.V. All rights reserved.