SnO2-based MEMS Hydrogen Sensor Prepared by Magnetron Sputtering

In this paper, a method of preparing a hydrogen sensor by depositing tin oxide (SnO2) thin film on the surface of Micro-Electro-Mechanical System (MEMS) based on radio-frequency (RF) magnetron sputtering is proposed. Under the sputtering parameters of target-substrate distance of 9.5 cm, sputtering time of 0.5 h, reaction gas flow ratio(Ar:O2) of 80:50, vacuum degree of 1 Pa, sputtering power of 50 W, rotational speed of 4 rpm, the response value of the hydrogen sensor to 1 × 10–5 (1 ppm = 1 × 10–6) hydrogen reaches 2.647, the response time is 77 s, and the recovery time is 24 s. The sensor has a low operating temperature (20 ℃) and an ultra-low detection limit (5 × 10–8), thus it can realize trace detection of hydrogen under room temperature working conditions. In addition, the coefficient of variation of the sensor ranges from 0.006 to 0.07, showing good consistency.