Thin film processing by biased target ion beam deposition

This paper describes the development of a novel thin film deposition technology, which we call biased target ion beam deposition (BTIBD). BTIBD employs a low energy ion source (<30 eV) directed at a negatively biased target. Because typical ion energies are below the sputter threshold of vacuum construction materials, only those ions arriving at the target acquire sufficient energy to cause sputtering. A second low-energy ion source can be directed at the substrate to provide low energy (<15 eV) bombardment of the growing film. BTIBD is well suited to demanding applications requiring atomically engineered thin films and interfaces because it offers a large range of process pressures, control of adatom energies, and excellent uniformity and repeatability. This paper describes a multi-target, prototype (BTIBT) system, the associated ion sources, and process results on thin Cu films and spin valve structures.