An in situ Auger electron spectroscopy study of chromium thin film coverage of copper surfaces: Effects of surface morphology, temperature and environment

Abstract

The Auger electron spectroscopy (AES) based method used in epitaxial film growth studies has been adapted to study in situ the coverage characteristics of substrate surfaces with roughness typically encountered in microelectronic applications and to determine the practical average thickness tc below which the overlayer film is discontinuous. As an exemplary case chromium was vapor deposited in ultrahigh vacuum (10-9 Torr) over copper substrates of different surface roughnesses. The effects of substrate surface morphology, temperature (ambient and 330 °C), presence of native surface oxides, and an H2O-vapor-rich (5 × 10-5 Torr) atmosphere during chromium deposition were examined. It was shown that the surface morphology of a copper substrate plays a major role in the coverage characteristics and physical form of a growing chromium film and can be readily studied by the present technique. The presence of a native surface oxide, high substrate temperature and water-vapor-rich ambient during film growth affected the coverage mode and resulted in slower coverage rates and higher tc values. Some of the kinetic factors controlling the surface coverage are discussed. © 1991.