Regensburg 2007 – scientific programme

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DS: Fachverband Dünne Schichten

DS 26: Oxides

DS 26.9: Talk

Thursday, March 29, 2007, 17:00–17:15, H34

Structure Formation and Phase Composition of Zirconia Films grown by High Power Pulsed Magnetron Sputtering (HPPMS) — •Christian Klever, Kostas Sarakinos, and Matthias Wuttig — I. Institute of Physics (1A), RWTH Aachen University, 52056 Aachen, Germany

We have employed the novel HPPMS deposition technique for the deposition of ZrO₂ films. ZrO₂ is a polymorphic material, which in thin film form exhibits exceptional mechanical and optical properties and is therefore widely used as a functional coating. In HPPMS unipolar pulses of high–peak power/current and low duty cycle are applied to the target. As a result of the unique properties of the deposition process, several film properties can be improved.

In this study, pulses with pulse off–times t_off ranging from 450 to 2450 µs (pulse on–time t_on kept constant at 50 µs) are applied to a Zr target (cathode). The films are deposited in a mixed Ar–O₂ ambient on unheated silicon substrates at a constant working pressure (1.5 Pa). Ion saturation current measurements are performed using a flat electrostatic probe. They manifest an increase of the ion flux to the growing film when t_off is increased. The changes of the duty cycle settings are accompanied by changes in the film structure. It is shown that monoclinic films are obtained when t_off is higher than 950 µs, while films with a mixed monoclinic/cubic phase composition are deposited for lower t_off. Also, the effects of the sputtering pressure and substrate temperature on the structure of films grown for t_off below 1450 µs are investigated.