Monotonic and fatigue testing of spring-bridged freestanding microbeams application for MEMS

An electroplating spring-bridge micro-tensile specimen is fabricated to carry out a series of monotonic tensile testing on it. Freestanding thin films were loaded by performing monotonic loading/unloading and tensiontension fatigue experiments. Loading was applied using a piezoelectric actuator with 0.1 μm resolution connected through pin hole into the test chip specimen. Loads were measured by connected a capacitor load cell with a resolution of less than 0.1 mN. We found the modulus of gold, copper and tantalum nitride thin films with thickness of 200~800nm at ambient temperature. Displacement controlled tension-tension fatigue experiments have also been performed and a trend of decreasing cycles to failure with increasing displacement amplitude and increasing mean displacement has been noted.