A Process to Realize Direct Laser Written Electrostatic Actuator Elements in a Closed Microcavity

For the first time an electrostatic actuator made by 2-photon polymerization (2PP) that is integrated in a closed microcavity is presented. The cavity is closed by wafer-to-wafer bonding of Parylene-C coated borosilicate glass and silicon wafers. Additionally, the Parylene-C serves as electrical insulation. The actuator consists of a freestanding, electrically connected, movable platform with an outer diameter of 260 μm supported by conical springs. The structure can act as a microfluidic valve. The novel wafer-scale fabrication process enables the electrical connection and electrostatic actuation of movable 2PP-structures and the patterning of a metallization on wafers containing 76 μm high 3D structures. Furthermore, a silicon wafer and a borosilicate glass wafer, which contains metallized 2PP-structures that can withstand a limited temperature load only, are bonded. This process has great potential for versatile applications in MEMS.