Surface tension powered self-assembly of 3D MOEMS devices using DRIE of bonded silicon-on-insulator wafers

Surface tension powered self-assembly is a technique for mass parallel fabrication of 3D micro-electro-mechanical systems (MEMS) from surface micromachined parts, which are rotated out-of plane by the surface tension of pads of a meltable material. Recently, we have demonstrated a simple two-mask process based on mechanical parts formed from 4 inch industry-standard bonded silicon-on-insulator (BSOI) wafers and meltable pads of thick photoresist, Hoechst A24562. Here, we describe enhancements obtained by deep reactive ion etching (DRIE) of the parts using an inductively coupled plasma (ICP), introduce improved hinge designs, and demonstrate a new range of self-assembling mechanisms. The process is first described, and the influence of critical fabrication steps such as lithography and etching on uniformity, yield and accuracy are discussed. Applications in micro-opto-electro-mechanical systems (MOEMS) are then demonstrated.