A low-power embedded poly-Si micro-heater for gas sensor platform based on a FET transducer and its application for NO₂ sensing

Gas sensors are commercialized and widely applied in various fields. Existing commercial sensors, however, have limitations in terms of power consumption. In this work, we propose a new design guideline of the FET-type gas sensor platform to significantly improve the power efficiency of the embedded poly-Si micro-heater. The fabricated sensors are capable of low power operation while maintaining high response and stability. To our knowledge, the embedded micro-heater of the proposed platform provides the best power efficiency (e.g. 300 ℃ at 1.63 mW) among reported gas sensors with external heaters. By adopting electrode metals with low thermal conductivity (Ti/TiN instead of Cr) in contact with the heater and an efficient heat insulating air gap design (increasing air gap length under the electrode from 0 μm to 28 μm), we can increase the heater temperature by 63 % at the same power consumption. Also, the proposed platform is more sensitive and advantageous for low-concentration gas detection compared to the reported FET-type platform using hot chuck that increases the temperature of the entire sensor.