CMOS MEMS Thermoelectric Infrared Sensor With Plasmonic Metamaterial Absorber for Selective Wavelength Absorption and Responsivity Enhancement

This study demonstrates the integration of thermoelectric type MEMS infrared (IR) sensor with plasmonic metamaterial absorber (PMA) through a standard CMOS process platform to improve the responsivity of MEMS IR sensor in a specific range of wavelength. Based on an existing thermoelectric IR sensor with the serpentine film structure, the proposed device further combines with a Metal-Insulator-Metal (MIM) type PMA. The absorber consists of a top antenna layer, a middle dielectric spacer, and a bottom reflector, and the metal and dielectric films in the standard CMOS process are exploited in this study to implement the MIM design. The advantage of narrow linewidth in CMOS process can meet the need of critical dimensions for MIM antennas. The absorption wavelength can be adjusted by varying the pattern and dimension of antennas. The MIM PMAs are designed in the coupling regime, and hence the shifting of absorbed wavelength caused by the variation of antenna dimensions from fabrication can be prevented. The feasibility of the presented MIM PMA is demonstrated by simulations and experiments. The absorption spectra measured by FTIR show the capability of proposed MIM PMAs in extending the absorption range of far-infrared. Measurement results also indicate that under the same sensor footprint and the equal number of thermocouples, the device integrated with the proposed MIM PMA has a 20 percent improvement in responsivity as well as detectivity.