Surface Science Studies of Copper Films on Sapphire (0001) Surfaces.

Metal/ceramic interfaces are an important technological concern due to its increasing use in several fields such as metallization for microelectronic packaging applications and heterogeneous catalysis. Experimental studies using surface science techniques could provide the information concerning the physics, chemistry and structure of the interface region. The material system chosen for this study is copper deposits on sapphire (0001) surfaces. The main techniques used in this investigation are the Temperature Programmed Desorption (TPD), Auger Electron Spectroscopy (AES), X -ray Photoelectron Spectroscopy (XPS), Reflection High Energy Electron Diffraction (RHEED) and Atomic Force Microscope (AFM), primarily in Ultra-High-Vacuum (UHV) systems. The TPD spectra exhibit two distinguishable peaks at submonolayer coverages, each shifting slightly toward higher temperatures as the coverage increases, the activation energies as obtained from computer simulations are in the range of 2.56 to 3.10 eV. The effect of annealing and oxidation was also studied. The XPS Cu 2p spectra suggest a weak interaction between copper and oxygen at room temperature, and the peaks broaden when the sample was annealed at temperatures over 200^circC, indicating stronger chemical reactions between copper and sapphire at higher temperatures. The RHEED studies showed that the films grown at 200^circC developed into near single crystal films whereas the films grown at 600^circC remained polycrystalline with a fiber structure.