Process platform for high aspect-ratio self-aligned vertical comb actuators

Vertical comb drive actuator has been widely employed in MEMS scanning mirror, but more process challenges occur when it goes to high aspect ratio comb structures for high stroke application. This paper reports a novel process to fabricate self-aligned vertical comb drive actuator with aspect ratio up to 40. With this process platform, some process limitations can be lifted, while a vertical comb drive actuator with non-resonant scan angle larger than 20° can be obtained. A 2D scanning mirror with large scan angle is taken as an example to demonstrate this platform.