Hannover 2010 – wissenschaftliches Programm

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P: Fachverband Plasmaphysik

P 6: Low Temperature Plasmas I

P 6.6: Vortrag

Dienstag, 9. März 2010, 15:40–15:55, B 305

Tailored ion bombardment during plasma processing: options and limits — •Tim Baloniak, Rüdiger Reuter, Christoph Flötgen, and Achim von Keudell — Ruhr-Universität Bochum, AG Reaktive Plasmen, 44780 Bochum, Deutschland

Radio frequency biasing is a technique to control ion bombardment energies during plasma processing. The ion energies are manipulated by external voltages which are applied to the substrate holder. It is desirable to posses a technique to tailor ion energy distributions to the needs of a certain application such as dry etching or thin film deposition. In this contribution, we report about the quantitative measurement of ion velocity distributions at an arbitrarily biased electrode. Variable bias waveforms are applied to this electrode. The electrode voltage is monitored and controlled in the frequency domain using fast Fourier transformation. Ion velocity measurements are performed by a miniaturized floating retarding field analyzer. A full modulation of the ion velocity distribution is obtained only if sufficiently high sheath voltages are applied. Non-linear sheath behavior is observed for low sheath voltages. This non-linear behavior is visible both in the electrode voltage and in the ion velocity distributions. It is shown that a combined DC and RF biasing is required to gain full control over the ion bombardment of the substrate.