A tensile-testing technique for micrometer-sized free-standing thin films

A tensile-testing technique for micrometer-sized free-standing thin films is described and sample results obtained using the technique are presented. Major components used in the technique include a three-axis micromanipulator, a force sensor, two desktop computers, and a microscope. The design and fabrication of specimens by use of microfabrication methods are an integral part of the technique because they are crucial for testing to be successful. The micromanipulator is computer-controlled and has a speed range from 0.004 to 2 μm/s in each axis. The force sensor is an eddy-current device and has force capacities in millinewtons. The desktop computers are used to control the micromanipulator, and to acquire data and images, which are used to calculate strains with a digital-image-correlation technique. The nominal dimension of a typical specimen is 180 μm × 10 μm × 1 μm and tests can be conducted from ambient temperature (∼23 °C) to 200 °C. Over the last few years, the technique has been successfully used in our laboratory to test polysilicon, pure aluminum, aluminum alloys, photodefinable polyimide, and electrodeposited copper.