Cluster beams for metallization of microstructured surfaces

Cluster beams from a nozzle source are characterized by a high directionality (point source) and a high intensity. These properties have been used for thin film metallization of flat and microstructured surfaces. The paper describes the cluster beam source developed for metals like silver and magnesium. At present, the final collimated cluster beam covers a total angle of 7°, which for a source distance of 1 m gives a beam diameter of 120 mm. The deposition rate at that distance is up to 10 nm/s, and the total beam flux is 20% of the metal flux out of the nozzle. The metallic films obtained with this new deposition technique are a close image of the respective substrate structure. Good metallization of substrates has been observed up to cluster incidence angles of 80°, and the negligible thermal divergence of the cluster beam allows metal deposition, e.g. into contact holes.