Tribological degradation of fluorocarbon coated silicon microdevice surfaces in normal and sliding contact

Reported here is a study of the tribological degradation of the contact interface of a fluorocarbon monolayer-coated polycrystalline silicon microdevice. A surface micromachined silicon tribometer is employed to track changes in the adhesion and friction properties during repetitive normal and sliding contacts. Evidence for tribological degradation commences immediately for parallel sliding contact motion, and is slightly delayed in the case of repetitive impact loading normal to the surface. The observed changes in interfacial behavior indicate dramatic changes in the chemical (i.e., surface energy) and physical (i.e., roughness, real contact area, etc.) nature of the contacting surfaces. Results from microscale sliding and impact experiments are interpreted in the light of the primary physical and chemical degradation mechanisms of monolayer-coated silicon microdevices.