Magnetron sputtering cathode with electrically variable source size and

Abstract

In a magnetron sputtering cathode, the magnetic field is translated across the face of the sputtering target. The magnetic field determines the region from which most material from the target is ejected, and therefore the cathode provides a means of electrically varying the size, shape or location of the active region on the face of the target. The cathode may be used to coat a large number of substrates by sweeping the magnetic field across a large target rather than mechanically transporting the substrates across a small fixed target. The cathode allows more efficient utilization of the target through rapid and periodic changes in the size or location of the magnetic field and associated target erosion. These changes prevent formation of the localized and deep erosion ring that develops on targets used with existing cathode designs and relieves the requirement that the target be changed before the bulk of the material is consumed. In one design the circular or rectangular magnetic field pattern is expanded or contracted radially. An alternative design allows translation of the magnetic field pattern. Another design provides more general two dimensional control of the field pattern and provides a novel means of cooling the target as well.