Research on high temperature performance of pressure sensor

Abstract

This work proposes a molybdenum (Mo) based pressure sensor capable of operating at temperatures higher than 300 ℃. The sensor utilizes a 30 μm thick rectangular pressure-sensitive film and 2 μm thick gate Mo resistors to form a Wheatstone bridge structure to enhance pressure sensing. Finite element analysis (FEA) has been performed to design the sensor and analyze the pressure and temperature effect. The developed sensor with the excitation of 1 V voltage exhibits excellent performance characteristics at room temperature (25 ℃), including a sensitivity of 0.05689 mV/V/kPa, 0.15 % Full Scale (FS) accuracy, a nonlinearity of 0.79 % FS, and 0.02 % FS repeatability. The thermal zero shift of -0.13 % FS/℃ is obtained in the 25 ℃ to 300 ℃ temperature range. The simulation findings illustrate that the thermal mismatch weakens the thermal zero shift by +0.012 ‰ FS/℃, while the deviation of the temperature coefficient of resistance (TCR) and initial resistivity (ρ_(T_0 )) aggravate the thermal zero shift by -0.139 % FS/℃. Among both, the deviation of ρ_(T_0 ) and TCR is the major contributor to thermal zero shift. Moreover, it was found that the Seebeck effect caused by the on-chip temperature gradient also affects the accuracy of the sensor. A temperature difference of 5.4 ℃ produces a thermoelectric potential of 37.95 μV equivalent to a pressure of 670 Pa loading on the chip. Besides, the response characteristics of the sensor at different temperature rates were investigated.