ADVANTAGEOUS POSSIBILITIES, DESIGN ASPECTS AND TECHNICAL USE OF DOUBLE-RING MAGNETRON SPUTTER SOURCES

Based on the principle of the double-ring source, some problems with s tationary deposition by magnetron sputtering can be solved so that sev eral possibilities of process control are achieved. The first is the h omogeneous deposition of one material on large substrates up to 300 mm in diameter. This problem can also be solved for coating distances in the range below 100 mm by superposing two concentric sputter zones wi th well defined diameters. Experience and results obtained during prac tical use of the devised magnetron solution are discussed. Another ver y important task is the homogeneous deposition of compounds by reactiv e magnetron sputtering. In this case the double-ring source with a con ducting target offers the advantage of solving efficiency problems wit h the anode that will be covered by reaction products so that it becom es inoperative during reactive deposition. Some aspects of magnetron d esign are discussed with regard to these partially contradictory deman ds for different applications. The model for optimizing parameters suc h as erosion track, coating distance and power ratio of the two concen tric discharges is explained. The design of a magnet system with a var iable magnetic field strength is of importance for both erosion behavi our and process control. The pros and cons of systems with electromagn ets and permanent magnets under different aspects of practical importa nce are compared.