Journal of Materials Research

Articles

The Thermal Stability of Thin Copper Films Deposited on TiO2(110) Studied by Scanning Tunneling Microscopy

D. L. Carrolla1, M. Wagnera2, M. Rühlea2 and D. A. Bonnella3

a1 Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104–6272

a2 Max-Planck-Institut für Metallforschung, Institut für Werkstoffwissenschaft, D–70174 Stuttgart, Germany

a3 Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104–6272

Abstract

The morphology of Cu thin films is strongly dependent on the temperature of the substrate during and after deposition. Films grown at temperatures between 300 °C and 400 °C form clusters distributed in close packed domains and isolated clusters across the surface. Increased substrate temperatures result in cluster shape evolution indicative of mass flow and sintering. Deposition of Cu at substrate temperatures higher than 500 °C results in a completely different morphology of the film and the suppression of cluster formation. Annealing these Cu films to temperatures of 700 °C allows the system to relax into an equilibrium state characterized by large facets in the film and large areas of exposed surface. These observations are discussed in terms of basic thermodynamic data for bulk Cu oxidation and surface tensions for this system.

(Received September 21 1995)

(Accepted November 25 1996)

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