Influence of a Novel Solid Thermal Isolation Material for Mems on Thermopile Sensitivity and Dynamic Response of a Mems Flow Sensor

Abstract:
This paper reports on the wafer-level modification of thin film flow sensors with a novel solid porous material for mechanical stabilization against overpressure events. A solid porous support is formed beneath the sensor membranes by agglomeration of dry powder using atomic layer deposition (ALD). Pressure testing of modified membranes shows resistance to overpressure events with a magnitude of at least 0.8 MPa (8 bar). For the first time, the effect of this approach on the static and dynamic response of the sensor’s thermopiles is reported. The addition of porous microstructures is found to only have a moderate effect on sensor performance by slightly decreasing the thermopile sensitivity from 7.5 mV/mW to 5.5 mV/mW and increasing the time constant from 3.6 ms to 7.2 ms. These results demonstrate that the proposed technology is highly promising for the development of non-fragile thermal isolation structures for MEMS.