A 3D packaging cover structure with optical filter and low signal-transmission loss for MEMS infrared detectors

This paper presents a wafer-level three-dimensional (3D) packaging cover structure for microelectromechanical systems (MEMS) infrared detectors. Subwavelength structures with an array of square coaxial apertures are designed on top of silicon substrate to obtain extraordinary optical transmission (EOT). The optical transmission is up to 58%, and its bandwidth is 4 μm. The vertical silicon vias, insulated by Pyrex glass, are used for electrical interconnections. The thickness of the insulation is optimized, such that the feed-through level is lower than -93 dB and the transmission coefficient is more than -0.032 dB at a frequency from 0 to 2 GHz. Those above results demonstrated that the proposed 3D packaging cover structure is suitable for MEMS infrared detectors.