Size Effects in Internal Friction of Nanocrystalline Aluminum Films

Materials (Basel). 2021 Jun 19;14(12):3401. doi: 10.3390/ma14123401.


Al thin film is extensively used in micro-electromechanical systems (MEMS) and electronic interconnections; however, most previous research has concentrated on their quasi-static properties and applied their designs on larger scales. The present study designed a paddle-like cantilever specimen with metal films deposited on the upper surface to investigate the quasi-static properties of Al thin film at room temperature under high vacuum conditions at microscopic scales. Energy loss was determined using a decay technique in the oscillation amplitude of a vibrating structure following resonant excitation. Grain size and film thickness size were strictly controlled considering the quasi-static properties of the films. This study found that the internal friction of ultra-thin and thin Al films was more dependent on the grain boundaries than film thickness.

Keywords: energy loss; internal friction; quasi-static properties of thin film; thickness dependence; ultra-thin al films.