Integration of the DRIE, MUMPs, and bulk micromachining for superior micro-optical systems

This work integrates multi-depth DRIE etching, two-poly MUMPs, and bulk releasing to accomplish superior poly-Si micro-optical systems. The stiffness of the devices was significantly increased using the trench-refilled rib structure, so that the radius of curvature (ROC) of the 2 μm thick mirror even reached 150 mm. In addition, the space between the devices and the substrate was remarkably increased to ∼100 μm by bulk silicon etching. Moreover, the self-aligned vertical comb actuators were available through the multi-depth DRIE etching. In application, the scanning mirrors driven by vertical comb actuator were demonstrated. The scanning angle was ±3 degrees (optical angle) at 40 V driving voltages (DC) and resonant frequency was 1.8 kHz. These poly-Si micro-optical devices can further integrate with the MUMPs devices to establish a more powerful MOEMS platform.