Elimination of post-release adhesion in microstructures using conformal fluorocarbon coatings

The adhesion of polysilicon microstructures to their substrates is eliminated using a relatively conformal hydrophobic fluorocarbon (FC) coating grown in a field-free zone of a plasma reactor. Experiments show that the FC film deposition on top of the microstructure and on the underside was approximately 2:1. The FC coating is able to cover the entire underside of a 200 x 200 mu m(2) plate, with a 20% deposition nonuniformity. The coating exhibits a contact angle of 110 degrees and is able to prevent adhesion of cantilever beams and doubly supported beams to their substrates even after direct immersion in DI water. The durability of the coating was tested using an accelerated aging method, predicting a lifetime of greater than ten years at 150 degrees C. Periodic wear tests indicate that the coating remains hydrophobic even after 10(7) contact cycles.