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Ultrananocrystalline diamond film deposition by direct-current plasma assisted chemical vapor deposition using hydrogen-rich precursor gas in the absence of the positive column

Title
Ultrananocrystalline diamond film deposition by direct-current plasma assisted chemical vapor deposition using hydrogen-rich precursor gas in the absence of the positive column
Author
전형탁
Keywords
HOT-FILAMENT; THIN-FILMS; GROWTH
Issue Date
2011-01
Publisher
AMER INST PHYSICS
Citation
JOURNAL OF APPLIED PHYSICS, v. 109, NO 2, Page. -
Abstract
We have investigated the ultrananocrystalline diamond (UNCD) deposition by direct-current plasma assisted chemical vapor deposition on 4 in. Si wafer using CH4-H-2 as well as CH4-Ar gas chemistry containing additive nitrogen. CH4/N-2/H-2 (5%/0.5%/94.5%) and CH4/N-2/H-2/Ar (0.5%/5%/6%/88.5%) gas mixtures were compared as the precursor gas. Molybdenum and tungsten were compared as cathode material. Discharge voltage and current were 480 V/45 A and 320 V/60 A, for respective gas chemistry. Chamber pressure and substrate temperature were 110-150 Torr and 750-850 degrees C, respectively. The film was characterized by near edge x-ray absorption fine structure spectroscopy, x-ray diffraction, high-resolution transmission electron microscope, electron energy loss spectroscopy, and high-resolution scanning electron microscope. We have demonstrated that (1) elimination of the positive column, by adopting very small interelectrode distance, gave some important and beneficial effects; (2) the plasma stability and impurity incorporation was sensitive to the cathode material and the precursor gas; (3) using the conventional CH4/H-2 precursor gas and tungsten cathode, the mirror-smooth 4 in. UNCD film of excellent phase-purity and grain size below 10 nm could be deposited even in the absence of the positive column. The high electric field in the unusually narrow interelectrode space and the consequent high electron kinetic energy, in conjunction with the unusually high electron current thereof, directed to the substrate, i.e., the anode, was proposed to be the source of the grain refinement to achieve UNCD at such high chamber pressure around 110-150 Torr, in the absence of the usual ion bombardment assistance. (C) 2011 American Institute of Physics. [doi:10.1063/1.3533764]
URI
http://aip.scitation.org/doi/10.1063/1.3533764
ISSN
0021-8979; 1089-7550
DOI
10.1063/1.3533764
Appears in Collections:
COLLEGE OF ENGINEERING[S](공과대학) > MATERIALS SCIENCE AND ENGINEERING(신소재공학부) > Articles
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