Hidden-hinge micro-mirror arrays made by heterogeneous integration of two mono-crystalline silicon layers

In this paper we present wafer-level heterogeneous integrated hidden-hinge micro-mirror arrays for adaptive optics applications. The micro-mirrors are made of mono-crystalline silicon and fabricated by two cycles of adhesive wafer bonding on fan-out substrates with addressing electrodes. The fabrication scheme allows the down-scaling of the micro-mirrors in size, the up-scaling of the array size and the implementation of additional material layers. Furthermore, large distances of the micro-mirrors to the electrodes can be achieved and hence a large deflection of the mirrors is possible. The micro-mirrors exhibit excellent deflection stability; no drift or hysteresis can be observed.