Arrays of monocrystalline silicon micromirrors fabricated using CMOS compatible transfer bonding

In this paper, we present CMOS compatible fabrication of monocrystalline silicon micromirror arrays using membrane transfer bonding. To fabricate the micromirrors, a thin monocrystalline silicon device layer is transferred from a standard silicon-on-insulator (SOI) wafer to a target wafer (e.g. a CMOS wafer) using low temperature adhesive wafer bonding. In this way, very flat, uniform and low stress micromirror membranes made of monocrystalline silicon can be directly fabricated on top of CMOS circuits. The mirror fabrication does not contain any bond alignment between the wafers; thus, the mirror dimensions and alignment accuracies are only limited by the photolithographic steps. Micromirror arrays with 4×4 pixels and a pitch size of 16 μm ×16 μm have been fabricated.