Hugo Lievens

Advances in magnetron sputter sources

Abstract Magnetron sputtering has become one of the most important methods for depositing thin films, combined with an accurate control of process parameters and layer quality. However, this coating technique suffers from some shortcomings (e.g. low target utilization, limited sputter yield and plasma instabilities in reactive sputter processes) making it often sub-optimal for industrial purposes. In this paper, a new and advanced planar magnetron sputter source dealing with most of these problems is presented. First, the target utilization can easily be doubled by moving the magnet configuration in a well-designed and optimal way below the target. Second, the ability to apply higher power densities together with higher efficiencies results in an important increase in sputter yield. As a consequence, longer sputter runs without the need of target exchange can be achieved, together with higher machine throughput. Furthermore, this new magnetron, called Supermag™, is ready to implement new technologies (e.g. pulsed or AC power mode and balanced or unbalanced magnet configurations) with superior behavior and properties in both metallic and reactive sputter processes.

Soft-magnetic sputtered coatings on pet-substrate for electronic article surveillance

Abstract Thanks to the scaling up to large web widths and the introduction of rotatable cylindrical magnetron technology, D.C.-magnetron sputtering has also entered consumer markets such as electronic article surveillance (EAS). A very widely applied way of protecting goods in shops is the use of strip labels. Such labels have a rapidly solidified, cast, soft-magnetic strip as the active element. This strip consists of a complex alloy and has a quasi-amorphous microstructure. However, because of the finite thickness of the strip (typically 50 μm), the label is not perfectly flat and is considerably stiff. As a consequence, printing and fixing the label both have limitations. Therefore, strip labels are gradually being ruled out by soft-magnetic sputtered thin film labels. In order to yield a sufficiently high signal level in the detection gate of the EAS system, a relatively large thickness (up to 1 μm) combined with a high degree of amorphicity of the sputter-deposited soft-magnetic thin film are required. This has, of course, drastic consequences for the sputter process itself (cooling conditions, allowed working pressures, magnetic arrays, etc.). A major factor reducing production costs is the use of rotatable magnetrons: up to 90% of the magnetic material of the target can be sputtered. This is even more important since the magnetic material is an expensive, high-purity, quintary Co alloy. A drawback, however, is the fact that such targets are not readily available on the market. In the following, it will be shown that this problem can successfully be solved if know-how on target production is integrated in the coating plant.

Requirements for sputtering magnetic alloys on organic film

Deposition of magnetic thin films on organic substrates in large width roll coaters by DC-magnetron sputtering imposes specific requirements on the sputter coater in terms of magnetrons (configuration, targets, magnet arrays,...) and process conditions (substrate cooling, deposition pressure,...). This paper will discuss how the use of rotatable magnetrons and multilayer coatings can solve the technical problems for producing amorphous, soft-magnetic coatings. Integration of know-how on target manufacturing in the sputter plant has been a critical issue in reducing production costs so that the sputtered film can be used in electronic article surveillance tags. Although hard-magnetic coatings for recording applications show completely different features in terms of microstructure and thickness, the experience gained with soft-magnetic alloys has considerably helped the authors in the development of thin films with good recording characteristics (a.o. H c >40 kA m -1 ).