Design and Implementation of Multi-Layer Opened-IDAs Electrodes for the Response Enhancement of CMOS-MEMS Gas Sensors at Room Temperature

This study presents the design and implementation of gas sensors based on the standard commercial processes (TSMC 0.35µm 2P4M CMOS process) and the in-house post-CMOS processes. The proposed gas sensors feature the realization of the double-layer and triple-layer sensing electrodes to induce additional channel resistance of sensing layer. Thus, the response of gas sensor can be remarkably improved within the same footprint. Besides, top metal-layer (M4) of standard CMOS platform is deposited with additional Ti/Au layers to act as the first sensing electrode to improve the sensitivity and to short the response time of sensor. Measurement results indicate, as compared with the reference design with the single-layer sensing electrodes, the proposed design with the double-layer sensing electrodes has a near 6-fold enhancement in response and a near 2-fold decrement in response time to 1 ppm NO
2
gas at room temperature.