Abstract
In this paper, we present a large-scanning-angle and large-mirror microscanner actuated by the thermal actuators. The thermal actuators are based on bimorph effect and consist of three thin film layers, Polyimide, Au, and SiO2. The thermal actuators will deflect responding to temperature variation when the coefficients of thermal expansion (CTEs) of Polyimide and SiO2 mismatch. Furthermore, Polyimide is an organic material with higher CTE, lower Young’s Modulus, and its lower thermal conductivity. We can not only decrease the heat loss via the property of low thermal conductivity but also keep the good actuation performance. The thickness of polyimide film shrinks 50% after polyimide is cured. The bimorph beam could raise the mirror automatically by the residual stress, which is generated by the volume change of the polyimide. The purposes, out-of-plane and self-assembly, can be achieved by this effect. Therefore, the actuator has the adventure of low power consumption from our design and our microscanner can achieve the purposes of self-assembly and out-of-plane by residual stress after curing processes.The large mirror is released rapidly by using poly-pad combined with surface micromachining and bulk micromachining. The quick release reduces the effects of undulate surface as well as provides better protection for the micromachined components to avoid the damage caused by etchant. Furthermore, bulk etching increases the gap under the large mirror. The poly-pad processes are thin film poly-pad. We do not need to deposit a thick sacrificial layer to ensure the release process successfully. The poly-pad processes can also improve the profile of our microscanner. The more flat profile can increase the strength and lifetime of the microscanner.The modeling and simulation of our microscanner were reported. Currently, we are working on the improvement of microfabrication to get reliable devices.