Challenges in the industrial deposition of TCO materials by reactive magnetron
sputtering from rotatable targets
V. Linss
1
*
1
VON ARDENNE GmbH, Plattleite 19/29, D-01324 Dresden, Germany
Keywords:
reactive magnetron sputtering, rotatable magnetron, ITO, ZnO:Al
Reactive magnetron sputter deposition of transparent conductive materials (TCM) is a cost
effective deposition technique due to low target costs compared to ceramic processes.
Rotatable tube targets are industrial standard (architectural glass coating) because of their
high material reservoir and a high target utilisation (approx. factor 2 compared to planar
targets). Another advantage, in particular in reactive sputtering, is the absence of erosion
groves and therefore the minimization of re-deposition zones at the target surface. However,
the reactive sputter process is highly complex because nearly any process parameter has
strong impact on the properties of the growing film. Thus, the variation of the working point
with the target rotation and the distinct working points of the two racetrack lines along the
tube target may cause serious problems.
The most commonly sputtered transparent conductive oxide (TCO) materials are aluminium
doped zinc oxide (ZnO:Al) and indium tin oxide (ITO). The deposition of these TCO
materials is complex as it involves optimizing conductivity, transparency, and thickness over
a large substrate area. The reactive sputter processes for ZnO:Al and ITO are very distinct and
have different challenges. This concerns among others the possible process control
mechanisms as well as the dependence of the film properties on the reactive working point.
The reliable industrial application of the reactive TCO sputter processes is still a big
challenge, in particular for large area substrates. There are different possibilities to control the
sputter process as well as the film properties in situ.
IND 4
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