Hybrid Si Etching for Performance Enhancement of the Atmospheric CMOS MEMS Infrared Sensor

This study realizes MEMS IR sensors using novel hybrid silicon etching processes on the CMOS platform. The processes include DRIE and XeF2 silicon etching, which can control the undercut depth and release the MEMS structure respectively. Such silicon etching processes exhibit three merits: (1) the undercut depth can be increased to enhance the responsivity of MEMS IR sensors in the atmosphere, (2) the process is conducted at the front side of the chip and the inherent CMOS dielectric layers act as the hard mask to avoid the alignment issues from the traditional approach using backside etching, and (3) this process is CMOS-compatible and benefits the construction of CMOS-MEMS IR sensors. The simulation and measurement results successfully demonstrate the enhancement of the responsivity of MEMS IR sensor through the hybrid silicon etching processes.