Thermal induced stress on the membrane in integrated gas sensor with micro-heater

The control of stress on the dielectric membrane in integrated gas sensors (IGS) with micro-heater is one of the most important concerns for their reliable operation. There had been reported that the intrinsic stress in the membrane could be reduced by a stack of different materials like silicon oxide and silicon nitride films[l-3]. The major issue remains the thermal induced stress when the micro-heater is in operation. The thermal induced stress is dependent on the rate of heating and is expected to be most critical during the initial start-up period to reach the operation temperature for IGS in pulse operation mode in order to reduce power consumption. The heat-up rate has to be controlled for long term reliability. In this paper, we study the thermal induced stress on the membrane of a micro-heater in an integrated gas sensor using finite element simulation. A simplified structure of the heater and the membrane is modeled in the simulations to study the thermal-electric and stress responses of the membrane when the micro-heater is subjected to the heating current to simulate the initial heat-up period of the sensor.