Geometric considerations in magnetron sputtering

The recent development of high performance magnetron type dischage sources has greatly ennhaced the range of coating applications where sputtering is a viable deposition process. Magnetron sources can provide high current densities and sputtering rates, even at low pressures. They have much reduced substrate heating rates and can be scaled to large sizes. Magnetron sputter coating apparatuses can have a variety of geometric and plasma configurations. The target geometriy affects the emission directionsof both the sputtered atoms and the energetic ions wich are neutralized and reflected at the cathode. This Fact, coupled with the long mean free particle aths chich are prevalent at low pressure, can make the coating properties very dependent on the apparatus geometry. This paper reviews the physics of magnetron operation and discusses the influences of apparatus geomety on the use of magnetron for rf sputtering and reactive sputtering, as well as on the microstructure and internal stressesin sputtered metallic coatings.