A superior method and magnetron sputtering cathode apparatus in which some of the flux lines forming the closed-loop magnetic tunnel are made to change their curvature from convex to slightly concave within a region of the tunnel intersecting the sputtering target volume, and over a substantial fraction...http://www.google.es/patents/US4865708?utm_source=gb-gplus-sharePatente US4865708 - Magnetron sputtering cathode
