Preferred Orientation Of Vapor-deposited Thin Films And Valence Electron Structure Analysis

The properties of thin films depend strongly on their microstructure. The preferred orientation of thin films is an important microstructural characteristic which influences the mechanical and electromigration properties of thin fihns. Thereby, it is very necessary to control the preferred orientation of thin films for the reliability and functionality. The preferred orientation of thin fihns would consider the effects of surface and interface due to it being able to drive the grain growth and texture evolution in thin fihns, in which the structure of film-substrate interface affects not only the preferred orientation of thin fihns but also the combinative strength of the film-substrate. Cu and Ag films with preferred orientation and highly oriented diamond film are potential film material in the high-tech. In recent years, they were extensively applied to the large-scale integrated circuit due to variety of outstanding material properties than others films, which draws the interest of many researchers.The Cu and Ag thin fihns were deposited on single-crystal (100) -Ni wafer by magnetron sputtering. The thickness of Cu and Ag fihns was 2 μm. As shown by X-ray diffraction (XRD), they have (111), (100) and (110) preferred orientation in order. Based on the method of Bond Length Difference (BLD) of the Empirical Electron Theory of Solids and Molecules (EET), double states hybridization table of Cu and the valence electron structures of Cu, Ag and Ni have been constructed, then the average electron densities of Ni (100) and 33 planes of Cu and Ag, and relative electron-density differences (REDDs) between Ni (100) and 33 planes of Ag or Cu crystal have been calculated. From the combinative strength of the film-substrate and the continuity of electric charge, when an interface is made of two lattice planes, the larger is electron density on each plane, the higher is electron cloud and the combinative strength. On the other hand, the smaller is electron density difference on two planes, the satisfier is the continuity of electric charge. Therefore, the preferred orientation in Ag and Cu films should be (111), (100), (110) and (311) in order from minimization of the relative electron- density difference across interface, which is agreement with the experimental result. The effect of the substrate on the preferred...