High stroke polymer based electrostatic actuators

In this work we present the successful fabrication of a polymer based zipper actuator to achieve a large stroke electrostatic actuation. Instead of the commonly used silicon [1] we use the UV-curable OrmoComp to build the actuator. OrmoComp has a significantly lower elastic modulus (about 1 GPa), only a fraction of actuation voltage is necessary for a similar deflection. The major drawback of the polymer based approach is the challenging fabrication process which is described in this paper. All process steps are realized as a lithographic structuring of positive tone, respectively negative tone resists, allowing a full wafer level fabrication of polymer based electrostatic actuators. A specific development process makes it possible to induce stress in the OrmoComp layer, creating an out of plane actuator based on a simple two dimensional lithography process. We present the results on the first completely wafer level fabricated zipper actuator, creating an out-of-plane motion up to 470 µm at an actuation voltage of 374 V.