Fabrication of micro-optical switch by post-CMOS micromachining process

This work presents the micro-machined 2-D switch array for use on free-space optical interconnect platform integrated with a digital 1×8 de-multiplexer control circuit together. Moreover, this device employs electrostatic actuation for light beam directions control. The CMOS-MEMS array-based optical platform contains 10×10 circular micromirrors switching spots, the diameter of each mirror is about 50 μm and the overall chip size is around 2 mm by 2 mm. The commercialized simulation softwares were used to validate the micromirror design and elucidate the behavior of the micromirror before fabrication. The post-process simply employs HF based solution to etch silicon dioxide layer to release the suspended mirror structures. The micromirror array is actuated using an electrostatic force. The results reveal that the micromirror has a tilting angle of around 8° according to the triangular relation with a driving voltage of 18V at pull down state. Also described herein are the general principles of the light-beam switching method used, the detailed of device design, the post-CMOS fabrication process flow, the result of simulations and preliminary experimental results are discussed.