AVS 52nd International Symposium
    Thin Films Friday Sessions
       Session TF-FrM

Paper TF-FrM4
Hysteresis Behaviour during Reactive Sputtering using a Rotatable Magnetron

Friday, November 4, 2005, 9:20 am, Room 306

Session: Thin Films on Flexible and Polymer Substrates
Presenter: D. Depla, Ghent University, Belgium
Authors: D. Depla, Ghent University, Belgium
J. Haemers, Ghent University, Belgium
R. De Gryse, Ghent University, Belgium
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Reactive magnetron sputtering is a widely used technique to deposit thin compound films on different types of substrates. On laboratory scale the use of a planar magnetron is common practice. However, on an industrial scale one prefers a rotatable magnetron as the target is consumed more efficiently. Unfortunately, detailed experimental results are scarce. Some authors have reported that the well known hysteresis behavior is influenced by the target rotation speed. To study this interesting phenomenon a small rotatable magnetron was developed with a cathode length of only 20 cm making a study on laboratory scale possible. In this paper we present the first results obtained with this device. As we have investigated reactive sputtering of aluminum oxide before using a planar cylindrical magnetron@footnote1,2,3@ this reactive gas/target combination was also used in this study. The discharge voltage was measured as function of the oxygen flow. First, the oxygen flow was increased stepwise until the discharge voltage decreases abruptly, indicating target poisoning. Then the oxygen flow was decreased stepwise. In this way, several hysteresis curves were measured. Two major conclusions can be drawn from these experiments. First, the critical flow to fully poison the target, i.e. when the discharge voltage decreases abruptly, shifts towards lower values with increasing rotation speed. Secondly, we notice that the critical flow to de-poison the target, i.e. when the discharge voltage abruptly increases, also shifts towards lower values with increasing rotation speed but the influence of the rotation speed is much stronger. As such, the hysteresis widens with increasing rotation speed. @FootnoteText@ @footnote 1@D. Depla, R. De Gryse, Plasma Sources Sci. Technol. 10 (2001) 547-555@footnote 2@D. Depla, R. De Gryse, J. Vac. Sci. Technol. A 20 (2002) 521-525@footnote 3@D. Depla, R. De Gryse, Surf. Coat. Technol. 138 (2004) 190-195.