Nano-mechanical and tribological characteristics of ultra-thin amorphous carbon film investigated by AFM

The mechanical as well as tribological characteristics of coating films as thin as a few nm become more crucial as applications in micro-systems grow. Especially, the amorphous carbon film has a potential to be used as a protective layer for micro-systems. In this work, quantitative evaluation of nano-indentation, scratching, and wear tests were performed on the 7nm thick amorphous carbon film using an Atomic Force Microscope (AFM). It was shown that AFM-based nano-indentation using a diamond coated tip can be feasibly utilized for mechanical characterization of ultra-thin films. Also, it was found that the critical load where the failure of the carbon film occurred was about 18μN by the ramp load scratch test. Finally, the wear experimental results showed that the quantitative wear rate of the carbon film ranged 10 ^-9-10^-8 mm³/N cycle. These experimental methods can be effectively utilized for a better understanding the mechanical and tribological characteristics at the nano-scale.