Abstract Scope |
Co-sputtered immiscible alloys form a number of interesting morphologies depending on the processing conditions. Recent research of co-deposited Cu-Mo and Cu-Ta thin films have revealed a novel morphology consisting of hiearchical structures which mean there are distinct features present at different length scales in the film. To determine the underlying thermodynamics and kinetics that lead to this unique morphology a series of immiscible alloy pairings were studied: Cu-Mo, Cu-Ta, Cu-Ag, Cu-Fe, Mo-Ag, and Cu-Mo-Ag. Experimentation revealed the presence of hierarchical structure is tied to the disparate kinetics of the depositing constituent elements at elevated deposition temperatures. With disparate kinetics, the element with a melting temperature comparable to the processing temperature will diffuse large distances and agglomerate, trapping the immobile element as nano-precipitates. Adjacent, macroscopic phase separation for immiscible systems occurs. In the case of constituent elements with similar kinetics, e.g. Cu-Fe, Cu-Ag, the resultant microstructure only contains macroscopic features. |