Effects of thin film properties on metallic pattern formation by direct nanoimprint

In this paper, the relation between properties of metallic thin films and the formability for metal direct imprinting method is discussed. In order to obtain a better formability of thin films, aluminum thin films with different grain sizes were prepared first. Nanoindentation test was applied to measure and confirm the material properties such as the hardness and elastic modulus of the thin film. It was found that the larger grain size is, the lower hardness is. This is called the Hall–Petch effect, which was confirmed by the former paper. To measure the surface topology, roughness, and height of the transferred pattern of the aluminum thin films, atomic force microscope (AFM) was employed. After the metal direct imprinting experiments, it was found the smaller grain size with the lower pattern transfer ratio. According to the results of indentation and imprint experiments, these indicate that the bigger grain size could have better formability, because of the effects from grain boundary. The formability of the metallic thin films can be improved through the thin film fabrication process for a suitable grain size and thickness control. Base on this method, valuable guidelines for the direct metallic imprinting process in nano/microscale pattern transfer could be provided.