A 600°C wireless multimorph-based capacitive MEMS temperature sensor for component health monitoring

This paper presents the design and fabrication of a new packaged MEMS capacitive temperature sensor for engine component health-monitoring applications and measurement results above 500-600°C. The multimorphs employed are thermal-SiO₂/LPCVD-Si₃N₄/sputtered-Au beams designed for deflection at these temperatures. The mean initial capacitance of the sensors is 6.441 pF; with a standard deviation of 0.197 pF. The robust fabrication process and packaging yield consistent capacitance-temperature profiles from device-to-device. Similarly, the devices exhibit a consistently-high measured average quality factor of 1,727 with a standard deviation of 54 for 5 packaged devices. Also presented are laser confocal microscope profiles from the thermal-annealing process, detailing the break-in period, after which no additional creep is observed, even after over 24 hours at 650°C. This is a first-of-its-kind MEMS sensor with unparalleled performance for harsh-environment wireless temperature sensing.