Abstract: A method and apparatus for forming a thin film on a substrate by sputtering of a material from a cathode, which material is subsequently reacted to form the thin film. A process chamber has a sputter zone which contains a sputter electrode assembly and in which an inert sputtering atmosphere is injected. Isolation means separates the sputtering zone from a reaction zone of the process chamber, into which a chemically reactive atmosphere is injected, and prevents the chemically reactive atmosphere from entering the sputtering zone. A substrate receives a sputtered material in the sputtering zone, and is subsequently transferred to the reaction zone where the sputtered material is contacted by and reacts with the chemically reactive atmosphere therein to form a reacted thin film.