Nano- and microscale adhesion energy measurement for Au-Au contacts in microswitch structures

This paper presents a study of adhesion energies that are relevant to Au-Au microswitch contacts at the nano- and micronscales. Adhesion measurements are obtained from cantilevered Au microelectromechanical system (MEMS) microswitch structures with varying lengths. Scanning electron microscopy measurements of the microbeam profiles are combined with fracture mechanics model for the estimation of the adhesion energy. Adhesion contact and pull-off experiments are combined with theoretical models for the extraction of adhesion energies associated with Au-coated atomic force microscopy tips and Au microswitch substrates. Finite element method simulation was also performed to account for crack-tip shielding contributions from asperities in contact between Au-Au microscale cantilevered MEMS structure. The estimates of adhesion energies obtained for micron-scale contacts are shown to be in good agreement with those obtained for nanoscale contacts when appropriate "crack-tip shielding" corrections are used to account for the effects of the surface roughness of "crack-tip" shielding due to contact between micron-scale Au-Au surfaces. (c) 2006 American Institute of Physics.