Abstract: In a sputtering chamber where there is at least one target of some material comprising at least two elements which are to be sputtered as a compound onto a substrate within the chamber, a target having a plurality of edges is framed by a metallic shield to confine the sputtering to a forward direction and the background gas needed for maintaining stoichiometry of the sputtered material is injected directly inside of the shield so that immediately upon entry into the chamber a substantial portion thereof flows over the target. A perforated manifold running the length of an edge of the target releases the background gas to the target along its length.