MEASURING ADHESION ENERGY BETWEEN MEMS STRUCTURES USING AN ADHERED CANTILEVER

Spontaneous stiction of MEMS elements during fabrication or operation is a serious problem. Capillary or electrostatic forces causing stiction can be eliminated, but dispersion forces are always present due to their fundamental nature and should be investigated in detail. In this paper, dispersion forces are studied experimentally for Si-Au and Si-Ru systems using a test structure - an adhered cantilever. Long (12 mm) and thin (10 μm) cantilevers allow measurements with high accuracy. The paper discusses in detail the fabrication procedure of the cantilevers and the measuring chip. Information on the adhesion energy is extracted from the cantilever shape, which is registered by a scanning interferometer. The roughness of the contacting surfaces is carefully studied and the equilibrium average distance between the surfaces during contact is obtained. The work is of interest not only for MEMS, but also allows one to gain fundamental knowledge about dispersion forces at small distances, which is inaccessible for other experimental methods.