CMOS-integrable Ultrathin SnO2 Layer for Smart Gas Sensor Devices

Abstract

The development of smart gas sensor devices for daily life application requires considerable technological efforts related to CMOS integration of gassensitive materials. We are focusing on the heterogeneous integration of ultrathin (50 nm) SnO2 layers deposited by spray pyrolysis with CMOS devices. With respect to miniaturization and implementation of the sensing layers on micro-hotplates (μhps) we compared the H2 responses for 100x100 μm2 and 5x100 μm2 sized sensing films and found a very high response of 42% and 28%, respectively, for 10 ppm H2. We performed 2-point and 4-point electrical measurements of SnO2 layers on typical CMOS Al contacts and achieved linear V-I characteristic in the full operating temperature range up to 350¡C in 4-point configuration. We also demonstrate the excellent step coverage of the deposited SnO2 layers on passivated CMOS chips, which is highly important for post-CMOS processing of the sensor films.