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P: Plasmaphysik

P 2: Niedertemperaturplasmen / Plasmatechnologie 1

P 2.4: Vortrag

Montag, 27. März 2006, 15:45–16:00, 1002

Space- and time-resolved development of a pulsed magnetron discharge — •Thoralf Dunger, Thomas Welzel, and Frank Richter — TU Chemnitz, Institut für Physik, 09107 Chemnitz, Germany

The temporal development of an asymmetrical bipolar pulsed cylindrical magnetron discharge was investigated by space- and time-resolved Langmuir double probe measurements. The temporal behaviour of the charge carrier density on the axis of symmetry showed a typical two peak structure in the on-phase followed by a transition into a stationary state. It was found that the ratio of the peaks is influenced by discharge parameters, e.g. the pulse frequency. We propose the following simple model for the development of the discharge in the on-phase: The first maximum is related to volume ionisation due to acceleration of residual electrons - from the off-phase - away from the cathode. The second one is dominated by secondary electrons released by ion bombardment from the cathode. This maximum is delayed due to the drift of the ions to the surface and the slope of the applied target voltage affected by the power supply. The spatial distribution of the maxima shows that the first maximum compared to the second one is more pronounced in the substrate region than close to the target. The obtained results are discussed in terms of the influence of the magnetic field on both No-dqresidualNo-dq and No-dqsecondaryNo-dq electrons (see above) and their contribution to the development of the discharge.