Design, fabrication and characterization of high temperature thin film heat flux sensors

Thin film thermopile (TFTP) heat flux sensors have been developed in this paper. The property of TFTPs was modeled and analyzed by FEA COMSOL in order to optimize performance. Two types of TFTPs were fabricated by surface micromachining technology. For the TFTPs operating at temperature no more than 400 degrees C, spin coated polyimide was used as the thermal insulator. While for high temperature operation, the ion beam deposited silicon dioxide was chosen as the thermal insulator. Furthermore, thermally grown oxide (TGO) of aluminum layer inserted between metal and silicon dioxide improved TFTPs reliability at high temperature. The TFTPs was calibrated by a halogen tungsten lamp calibration system. The results showed that the output voltage of TFTPs responded linearly with the heat flux, which indicated that the TFTPs with optimized design were capable of providing surface heat flux measurement, and the TFTPs with silicon oxide as thermal insulator had the potential to work at 1000 degrees C.