IUVSTA 15th International Vacuum Congress (IVC-15), AVS 48th International Symposium (AVS-48), 11th International Conference on Solid Surfaces (ICSS-11)
    Plasma Science Tuesday Sessions
       Session PS2+TF+SE-TuA

Paper PS2+TF+SE-TuA4
Deposition of a-C:H Films: Plasma Chemistry and Material Properties

Tuesday, October 30, 2001, 3:00 pm, Room 104

Session: PECVD/IPVD
Presenter: J. Benedikt, Eindhoven University of Technology, The Netherlands
Authors: J. Benedikt, Eindhoven University of Technology, The Netherlands
K.G.Y. Letourneur, Eindhoven University of Technology, The Netherlands
M. Wisse, Free University, The Netherlands
D.C. Schram, Eindhoven University of Technology, The Netherlands
M.C.M. van de Sanden, Eindhoven University of Technology, The Netherlands
Correspondent: Click to Email
Remote Ar-C@sub 2@H@sub 2@ plasma created by means of a cascaded arc is used for fast rate deposition of hard hydrogenated amorphous carbon films (a-C:H, rate up to 50 nm/s, hardness up to 14 GPa). First the densities of the radicals have been investigated in detail using cavity ring down absorption spectroscopy (CRDS). C@sub 2@, CH, C and H radicals were spectroscopically identified and measured as a function of C@sub 2@H@sub 2@ gas flow admixture. C@sub 2@H radical is still not spectrally resolved but broad band absorption observed around 250, 276 and 431 nm can be ascribed to this radical. The main mechanism of the dissociation of acetylene and other radicals in the plasma is a charge exchange reaction with argon ion and subsequent dissociative recombination of the molecular ion with an electron. Thus the composition of the plasma depends strongly on the amount of argon ions (and electrons) available in comparison with the amount of acetylene molecules injected. A plug-down model of plasma chemistry was made to simulate measured densities and to find creation channels of the different radicals. Second in-situ real time ellipsometry was used during deposition to measure the refractive index and the growth rate of the films. Clear correlation between plasma composition and the properties of the film was observed. Both the refractive index (which is in our case correlated with hardness) and the growth rate increase with increasing acetylene flow. The highest values are reached when the acetylene flow into the chamber is equal or higher than the argon ion flow emanating from the plasma source. In this case the C@sub 2@H radical is dominantly present in the plasma and is the main growth precursor of our films.