Wafer-level flame-spray-pyrolysis deposition of gas-sensitive layers on microsensors

This paper presents a CMOS-compatible wafer-level fabrication process for monolithic CMOS/MEMS sensor systems coated with sensitive layers directly deposited by means of flame spray pyrolysis (FSP). Microhotplate (νHP)-based devices, featuring an FSP directly deposited SnO₂/Pt layer, have successfully been realized on a wafer level. The thermal characterization evidenced a thermal resistance of 10.6 °C mW^-1; moreover, gas test measurements with ethanol have been performed. Microhotplate membrane deformations during device operation have been investigated and have been reduced by adjustment of the intrinsic stress of a deposited silicon nitride layer.