Polysilicon Microstructures to Characterize State Friction

A polysilicon microstucture to characterize static fiction has been developed. A normal force is applied to a displaced suspended structure by an underlying electrode. The tangential force to measure the frictional force is produced by a restoring force from the displaced suspension. The spring constant is found empirically by resonating the structure. The friction coefficient for course-grained polysilicon-polysilicon interfaces was found to be 5.0+/-1.0. Silicon nitride-polysilicon surfaces exhibited less friction with a friction coefficient of 2.5+/-0.5. Friction was found to be independent of the apparent area of contact. Tests were also conducted on a piezoelectric crystal resulting in a reduction of friction and improved reliability of data extraction