Processing of intermetallic thin films: An indentation cracking study

Thin films are being used for a wide range of applications, from interconnects in microelectronics to coatings for wear resistance. Many studies have focussed on the microstructural evolution and structure-property relationships in such thin films. Recently, there is significant interest in the study of multicomponent bilayer/multilayer consisting of metals that have a tendency to form intermetallic compounds. When exposed to temperatures at which bulk diffusion and/or short circuit diffusion can occur at a reasonable rate, interdiffusion and intermetallic phase formation can be expected in such systems. In the present study, microhardness testing has been used to follow the evolution of mechanical properties of a composite thin film consisting of 10 nm Cu/200 nm Ni(V)/300 nm Al(Cu) sputter-deposited on a Si substrate. Composite hardness and fracture toughness have been followed and are presented as a function of heat treatment temperatures and times. These results are discussed along with the implications for in-situ processing of thin film intermetallic compounds.