Development of Versatile Mechanical Testing Machine for Sub-Micro-Sized Specimens

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Micro (or nano) electromechanical systems (MEMS/NEMS) are expected to be applied to micro-photonics and bio-medical devices such as optical switches for electro-optical communications and micro-catheters for brain surgery. The size of the components used in such devices is considered to be in the order of submicrons to microns. Therefore, the evaluation of mechanical properties of micro-sized materials are essential for practical applications of such MEMS/NEMS devices. In particular, the fracture and fatigue properties of micro-sized components are of crucial importance to the structural integrity and long-term reliability of actual MEMS/NEMS devices. In order to evaluate fracture and fatigue properties of such submicro-sized specimens, we have developed a new type mechanical testing machine for submicro-sized specimens, which can apply small amount of static and cyclic loads to the specimens. Cantilever beam type submicron-sized specimens with notches were prepared from thin films by focused ion beam machining. Fatigue crack growth and fracture tests were carried out using the testing machine. We were able to measure fracture toughness, fatigue life and fatigue crack growth rate of the specimens. This testing machine is extremely useful for determing fracture and fatigue properties of submicron-sized specimens for MEMS/NEMS applications.