Abstract: An improved shield structure for use in a sputtering apparatus for depositing a film on a substrate is disclosed. The cylindrically shaped shield structure, which extends over the ends of a cylindrical sputtering target, has at least one annular structure extending around an outside surface of the shield. The annular structure is dimensioned to interrupt or suppress movement of any arc which might otherwise travel across its outside surface. In a preferred embodiment, the annular structure is a groove capable of trapping any such arc therein and preventing its escape therefrom. In another preferred embodiment, the improved shield structure is electrically isolated such that it is prevented from becoming an anode. In this manner, the electrically isolated shield structure inhibits the formation of severe arcs between it and the cathodic target.