Dresden 2011 – wissenschaftliches Programm
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DS: Fachverband Dünne Schichten
DS 12: Layer Deposition Processes
DS 12.4: Vortrag
Montag, 14. März 2011, 18:00–18:15, GER 38
Combination of ECR plasma and asymmetric bipolar pulsed bias voltage for deposition of hard a-C:H films — •Marcus Günther, Siegfried Peter, and Frank Richter — Technical University of Chemnitz, Institute of Physics, D-09107 Chemnitz, Germany
Thin hard layers of amorphous hydrogenated carbon a-C:H show a lot of special tribological, mechanical, electrical and optical properties. The commercial use of these films is mostly limited by the small deposition rate of usual deposition processes.
We have investigated a combination of magnetically supported microwave plasma and asymmetrical bipolar pulsed bias voltage in the mid-frequency region (100 kHz) which provides separate plasma generation and ion acceleration to the growing film. An electron cyclotron resonance (ECR) plasma source, operated at 400 W microwave power, generated a high density of film forming species (radicals and ions). A separate pulsed bias voltage of up to 550 V controlled the ion fluxes and as a consequence the layer properties.The a-C:H films were characterized with respect to hardness, deposition rate and surface topography. The chemical composition of the layers was analysed by ERDA and thermal desorption spectroscopy.
The deposition process was tested in mixtures of isobutene (C4H8) and argon at pressures below 2 Pa. The variation of the bias voltage allowed the deposition of both soft, hydrogen rich layers and hard a-C:H layers with less hydrogen. Thus, DLC films with a hardness of 25 GPa were deposited at high rates exceeding 10 µm/h.