Resistive gas sensor with integrated MOSFET micro hot-plate based on an analogue SOI CMOS process

This paper describes the characterisation of a new type of integrated gas sensors. These gas sensors are fully CMOS compatible and offer ultra low power consumption. MOSFET micro-heaters are created within the device silicon on an SOI wafer, which elevate the substrate temperature through self-heating. A membrane is formed by the removal of the handle silicon by a DRIE process. Electrical and thermal characterisations have been performed showing operating temperatures in excess of 220°C are possible for a power consumption of less than 80 mW. The resistive gas sensor is then formed by the low-temperature CVD of a metal oxide film over a pair of gold electrodes. The utilization of CMOS technology permits the fabrication of high-temperature gas sensors at low-cost, high reproducibility, and higher sensitivity with on-chip circuit integration. This makes these smart SOI sensors suitable for a range of battery-operated, hand-held gas monitors and electronic noses.