Measurement of Young’s modulus and Poisson’s ratio for thin Au films using a visual image tracing system

The mechanical behavior of small-sized materials has been investigated for many industrial applications, including micro electrical mechanical systems (MEMS) and semiconductors. It is challenging to obtain accurate mechanical property measurements for thin films due to several technical difficulties, including measurement of strain, specimen alignment, and fabrication. We propose use of a visual image tracing (VIT) strain measurement system coupled with a micro-tensile testing unit, which consists of a piezoelectric actuator, a load cell, a microscope, and two CCD cameras. Freestanding Au films, 500 μm wide and 1, 2, and 5 μm thick prepared by sputtering, were tested using a VIT system. This system provides real-time strain monitoring up to a resolution of 50 nm during the test, and can be used to simultaneously measure Young’s modulus and Poisson’s ratio of a material. We used this system to obtain the stress–strain curve, Young’s modulus, and Poisson’s ratio of thin Au films.