Copper-based materials formed by high rate sputtering

Abstract

This paper presents the results of microstructure and property determinations made on pure and alloyed copper sputter deposited at rates of 20–25 nm s -1. For each material, the effects of substrate temperature and post-deposition annealing on the grain size and tensile properties were investigated. Fully dense coherent structures were obtained at all substrate temperatures. The absence of the porous poorly bonded structures obtained at temperatures in the range 0.1–0.2 T m by other workers is attributed to the low gas pressure, the normal incidence adatoms and the polished substrates used in the present study. All materials exhibited high tensile strenghts when deposited at 0.2 T m Values of 700 MPa were observed with pure copper, while precipitation-hardening and dispersion-hardening alloys produced values of 1000MPa. The principal difference between these materials was in the stability of their as-deposited structure and their strength during post-deposition annealing. For example, pure copper was unstable to recrystallization at room temperature (0.2 T m), while the dispersion- strengthened alloys exhibited only minor softening at 0.8 T m and very little grain growth at 0.95 T m. The mechanical properties are discussed in relation to the microstructure produced by high rate deposition.