Properties and applications of vacuum-deposited CuCr films

Abstract

The application of Cu films is restricted by their low oxidation stability and poor adhesive behaviour. Suggested by the metallurgical and thin film properties of Cr, one can expect that CuCr composite films are able to overcome these disadvantages. Films of Cu 0.53Cr 0.47 prepared by magnetron sputtering from a mixed target were investigated by analytical (transmission electron microscopy, energy-dispersive X-ray spectroscopy, Auger electron spectroscopy), electrical (ϱ( T), temperature coefficient of resistivity (TCR)) and mechanical (σ( T)) measurements. In combination with the annealing treatment it was found that the films go through a structural and phase evolution known from co-sputtering experiments: metastable b.c.c. phase, decomposition into a two-phase region (b.c.c. and f.c.c. phases), further phases by oxidation. The electrical behaviour is characterized by small TCR caused by weak electron localization and by good stability by a self-passivating (Cr 2O 3) surface layer. The results of electrical measurements show that the CuCr films may be used as a metallization system or as a low ohmic resistor at elevated working temperatures.