A new wafer-level membrane transfer technique for MEMS deformable mirrors

This paper describes a new technique for transferring an entire wafer-level silicon membrane from one substrate to another. A 1 μm thick silicon membrane, 100 mm in diameter, has been successfully transferred without using adhesives or polymers (i.e. wax, epoxy, or photoresist). Smaller or larger diameter membranes can also be transferred using this technique. The fabricated actuator membrane with an electrode gap of 1.50 μm shows a vertical deflection of 0.37 μm at 55 V. The proposed technique has the following benefits over those previously reported: 1) No post-assembly release process (e.g. using HF) is required, and no wax, photoresist, or epoxy is used for the transfer purpose 2) The bonded interface is completely isolated from any acid, etchant, or solvent, which ensures a clean and flat membrane surface. 3) It offers the capability of transferring wafer-level membranes over deformable actuators.