Structures of co-evaporated copper alloys

Abstract

The structures of CuSn, 3CuAu and CuCr which were co-evaporated simultaneously using two electron beam sources were investigated by transmission electron microscopy. The effects of the substrate temperature and post-annealing treatment were also studied. Only the system CuSn reveals the crystal structure identical with that predicted from its phase diagram, i.e. a mixture of a long-range-ordered Cu6Sn5 phase and β-Sn phase. In contrast the 3Cu-Au film shows a disordered solid solution, while the CuCr system show a new phase, a metastable b.c.c. phase. Lattice constants of the co-evaporated films appear to be greatly affected by the post-annealing temperature and the substrate temperature, i.e. a high temperature results in a crystal structure with a small lattice constant, indicating a stress relaxation. The melting point of the element co-evaporated with copper is found to be very important in determining the final structure of the co-evaporated alloy films. A post-annealing treatment of the copper-base alloy films shows that a strong 〈110〉 texture is formed in the case of the 3CuAu alloy and the initial grain size affects the rate of the disorder-to-order transformation, i.e. a small grain is favorable for the fast transformation. © 1985.