Polysilicon microstructures to characterize static friction

The design, fabrication process, and initial experiment results for a test microstructure for measuring static friction are described. 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 mu for coarse-grained polysilicon-polysilicon interfaces is found to be 4.9+or-1.0. Silicon nitride-polysilicon surfaces exhibit less friction with a mu of 2.5+or-0.5. Friction is found to be independent of apparent area. Tests were conducted on a piezoelectric crystal resulting in a reduction of friction and improved reliability of data extraction.<
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