A TSV-Structured Room Temperature p-Type TiO2 Nitric Oxide Gas Sensor

Abstract

Planar MOS/MEMS gas sensors have been widely studied and applied, but the detection of exhaled gas has been little developed. The flow rate of exhaled gas affects the suspension structure of the MEMS gas sensor and the operating temperature of the gas sensor. Therefore, this study uses the Bosch process and the atomic layer deposition (ALD) process to prepare a room-temperature (RT) TSV-structured TiO2 gas sensor. The results indicated that the TiO2 sensing film is uniformed and covers the through-silicon via (TSV) structure and the TiO2 sensing film is confirmed to be a p-type MOS. In terms of gas sensing at room temperature, the response of the sensor increases with the increasing NO concentration. The sensor response is 16.5% on average, with an inaccuracy of <± 0.5% for five cycles at 4 ppm NO concentration. For gas at 10 ppm, the response of the sensor to NO is 24.4%, but the sensor produces almost no response to other gases (CO, CO2, SO2, and H2S). The RT TiO2 gas sensor with a TSV structure exhibits good stability, reversibility, and selectivity to NO gas.