Mechanical properties of Au thin film for application in MEMS/NENS using microtensile test

In the case of MEMS and NEMS, the mechanical properties of their materials are closely related to their performance and reliability. The measurement of the mechanical properties of thin film for MEMS/NEMS is difficult because of the small sizes, forces, and displacements involved as well as the need for special techniques to prepare and handle the specimens. In general, micromechanical tests involve three main issues; specimen preparation, force application and measurement, and displacement or strain measurement. The microtensile testing system was developed. The grip ends of the specimen are glued to the grips attached to a piezoelectrically actuated loading system. Strain is measured directly on the specimen with laser interferometry named ISDG. Au is one of most widely used materials in microelectromechanical systems. Au film in the pattern is deposited on Si substrate by sputtering process, of which thickness is 1 μm. For strain measurement the markers on the specimen was made by focused ion beam (FIB). Using the microtensile test, stress-strain curve, elastic modulus and ultimate tensile strength of Au thin film was obtained. The results were compared with those of nanoindentation test.