Reactive sputtered TiO2 thin film humidity sensor with negative substrate bias

This study has demonstrated a simple fabrication process of a thin film ceramic relative humidity sensing chip at low temperature, 500°C. This process window to optimize sensitivity and hysteresis performance of the sensor has been studied using negative sputtering substrate bias and annealing duration. This proposed optimizing method yields an adjustable rutile/anatase phase ratio of titanium oxide. It shows improvement to the hysteresis of sensors and obtains good sensitivity, which is greater than four-orders of magnitude change in dc current over 11–97% relative humidity.