Cu deposition on rough ceramic substrate: Physical structure, microstructure, and resistivity

Abstract

Cu films with a thickness around 3.5 μm have been deposited on rough Al2O3 ceramic substrates by the partially ionized beam deposition technique. While the ion bombardment parameters are similar for all depositions, the substrate temperature during deposition is varied from 50 °C to 300 °C. Physical structure of the films is studied by SEM in cross-sectional and surface geometries. X-ray diffraction 2θ scan is performed to obtain information on the microstructure of the films, such as (111) fiber texture and average crystallite size. Resistivity of the films is also measured. It has been found that the physical structure of the films varies from a typical columnar structure at 50 °C to a completely noncolumnar structure at 300 °C. The XRD results show that the films are polycrystalline and have different degrees of 〈111〉 preferred orientation, depending on the substrate temperature. The average crystallite size increases with the increase of substrate temperature. No correlation between the physical structure and microstructure of the films is observed. The resistivity of the films was also seen to change as a function of the substrate temperature. This can be explained by quantitative models in which grain and columnar boundaries in the films are responsible for the decrease in electric conductivity of the films.