”Reactive magnetron sputtering, challenges in industrial and large area coating systems”
VON ARDENNE GmbH, Dresden, Germany
Reactive magnetron sputter deposition is a cost-effective deposition technique due to lower target costs compared to ceramic processes. Reactive sputter processes working in the so-called flow-mode, i.e. sputtering in a pre-set gas-mixture, are widely used in industry and quite easy to handle. If a process control is needed for process stabilization or to achieve high throughput, the cost-advantage of reactive sputtering is often opposed by higher efforts for process tuning and operator experience. For this reason, ceramic processes are an attractive alternative while the choice of suitable ceramic target materials is limited. Hence, for industrial use, the key task is to find the right control strategy to achieve a long-term stable, easy-care processes.
In industry, rotatable tube targets are widely used because of their high material reservoir and a high target utilisation. Another advantage in reactive sputtering, is the absence of erosion groves and therefore the minimization of re-deposition zones at the target surface, which may cause process-instabilities. On the other hand, the tube rotation can lead to different working points of the two parallel racetrack lines when sputtering reactively. In addition, the tube rotation itself often causes periodic process disturbances, which are challenging for reactive process control systems. We will discuss concepts to deal with these effects.
Next to the sputter-rate and process stability, the campaign time of reactive-sputter processes is a key parameter influencing the productivity of a PVD tool. The growth of parasitic layers in the process surrounding including the magnetron itself can lead to debris formation and subsequent process interrupt before targets are consumed. We will give some insight on how to deal with this issue.