A SUBSTRATE FOR THIN-FILM GAS SENSORS IN MICROELECTRONIC TECHNOLOGY

A laboratory model of a substrate for a gas sensor based on semiconducting tin oxide and produced in microelectronic technology is described. The paper discusses not only the problems of miniaturization of these gas sensors but also important production processes, with the exception of the gas-sensitive layer. The whole chip has a size of 2.7 by 2.7 mm and an active area of only 0.45 by 0.45 mm. The power consumption at the operating temperature of 300°C is below 75 mW. The active area is supported by a thin (10 μm) membrane of silicon oxide and nitride; an outer silicon frame provides mechanical stability. The heater is made from a NiFe alloy. The tested samples are stable and prove that a miniaturized low-cost gas sensor is feasible. © 1990.