Thermal model for a microhot plate used in a MEM gas sensor

Abstract

A thermal analytical model for a MEM gas sensor is presented and compared with an electrical circuit equivalent model. The objective is to study the temperature performance of the microhot plate configured within a MEM structure used for gas sensing. From this, it is possible to determine the magnitude of the electrical current that must be applied to the polysilicon heater on regard of its dimensions and materials used, for instance, when the sensor structure is fabricated with a MEMS technology compatible with CMOS integrated circuits fabrication. Results are presented where the response time and temperature level, as a function of applied current, can be determined. The model presented can be used as a base for designing microhot plates operating in gas sensors, where temperatures in the order of 300$^\circ$C are needed and that will be integrated monolithically with associated electronics, with constraints as minimum power dissipation.