Electromagnetic micromirror array with single-crystal silicon mirror plate and aluminum spring

We have designed and fabricated an addressable 4 × 4 array of micromirrors capable of providing up to 90° of angular deflection. Each micromirror comprises a single-crystalline silicon mirror plate supported by aluminum springs, which provides an extremely flat reflective surface and a compliant spring material that enables the integration of the device into a limited area without mitigating its performance (i.e., total angular deflection). The device is fabricated using a combination of surface and bulk micromachining processes, such as electroplating, bulk wet etching and XeF₂ etch processes. Selective actuation is accomplished by the use of an electrostatic clamping force on each mirror plate. A mirror rotation angle of more than 80° can be obtained by applying an external magnetic field, and this angle can be further increased by the use of an electrostatic force. The designed structure can be used in microphotonic applications.