CMOS-MEMS Fabry-Perot optical interference device with tunable resonant cavity

This study implements the CMOS-MEMS Fabry-Perot interferometer (FPI) with tunable resonant cavity. Using standard TSMC 0.35μm 2P4M CMOS process, the features of this design are as follows, (1) two optical resonant cavities are provided by the transparent oxide layer and air-gap, (2) oxide thickness is determined by post-CMOS etching process, (3) tunable gap can be controlled by integrated CMOS circuit, (4) ring-type electrode is exploited as rib-reinforced structure for thin oxide membrane. In summary, the presented FPI could modulate optical intensity by varying the dielectric membrane thickness and resonant air-gap. Moreover, the presented FPI could monolithically integrate with CMOS light sensor, and the single color reflective modulation is also achieved by color filter integration.