Testing Thin Films by Microcompression: Benefits and Limits

Coatings are very important for numerous industrial applications such as increasing the wear resistance of tools, providing thermal conductivity to components in engines or electric conductivity in microelectronic devices. The mechanical properties of the coatings are of prime concern. The practicability of performing miniaturized compression tests in order to determine mechanical properties of various thin films was analysed. Four coatings, a polycrystalline tungsten coating, a single crystal copper coating and two single crystal hard coatings (vanadium nitride and titanium nitride) were tested. The compression samples were fabricated using a focused ion beam microscope. The compression tests were executed with a micro-indenter installed in a scanning electron microscope. The deformation of the sample was observed and in-situ recorded by scanning electron microscopy. From the measured load-displacement data true stress-true strain curves were calculated. The limits and benefits of the microcompression technique are discussed.