Monolithic Integrated CMOS-MEMS MOS type Gas Sensor and Novel Heater for Sensitivity and Power Consumption Enhancement

This study designs and implements a metal-oxide semiconductors (MOS) type gas sensor in Fig. 1. The chip is implemented using TSMC 0.35μm 2P4M standard CMOS process and the sensing material is prepared by hydrothermal synthesis method. The gas concentration is detected based on the resistance change measured by the proposed sensor. Features of this study are (Fig. 1): (1) reduction of size through vertical integration of heater and ZnO-SnO₂ gas-sensing films on the CMOS-MEMS structure, (2) reduction of power consumption of the gas sensor through the heater design. In applications, the gas sensor will be used for O₂ concentration measurement. Measurement results show that the sensitivity of O₂ concentration sensing is improved from 0.093%/% to 0.3%/% (within O₂ concentration of 16-50%), and the power consumption is reduced from 477mw to 32mw by varying the heater design.