Comparative experimental analysis of the a-C:H deposition processes using CH{sub 4} and C{sub 2}H{sub 2} as precursors
- Institute of Physics, Chemnitz University of Technology, D-09107 Chemnitz (Germany)
The plasma enhanced chemical vapor deposition of a-C:H films using methane and acetylene as precursors was studied. Noninvasive in situ techniques were used to analyze the plasma processes with respect to the self-bias voltage, the displacement currents to the grounded electrode, the neutral gas composition, the optical sheath thickness as well as current and energy of the ions hitting the powered electrode. The a-C:H films were characterized for their deposition rate, surface roughness, hardness, mass density, and hydrogen content. Ion mean free paths, suitable for low-pressure rf sheaths, have been quantified for both precursors. The film with the highest hardness of 25 GPa was formed in the C{sub 2}H{sub 2} discharge when the mean energy per deposited carbon atom was approximately 50 eV. The hardness obtained with the CH{sub 4} discharge was lower at 17 GPa and less sensitive to changes in the process parameters. It was found that the creation of hard (hardness >15 GPa) a-C:H films from both precursors is possible if the mean energy per deposited carbon atom exceeds only {approx}15 eV. Further film characteristics such as surface roughness and hydrogen content show the interplay of ion flux and deposition from radicals to form the a-C:H structure and properties.
- OSTI ID:
- 21057526
- Journal Information:
- Journal of Applied Physics, Vol. 102, Issue 5; Other Information: DOI: 10.1063/1.2777643; (c) 2007 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-8979
- Country of Publication:
- United States
- Language:
- English
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