Characterization of remote inductively coupled CH{sub 4}-N{sub 2} plasma for carbon nitride thin-film deposition
- Department of Electrical and Computer Engineering, North Carolina State University, Raleigh, 27695-7911, North Carolina (United States)
We investigated reaction characteristics in a CH{sub 4}/N{sub 2} plasma for deposition of amorphous CN{sub x} thin films (a-CN{sub x}) by evaluating the change in electron density using the wave cutoff method, and the behavior of ions and radicals with an optical emission spectroscopy (OES). An inductively coupled plasma source that was 30 cm away from the substrate stage was used for the discharge. The change in electron density in the substrate region and OES spectra in the plasma-source region were evaluated to investigate both the reaction mechanism and the remote effect while varying process conditions such as rf power, pressure, and gas-mixing ratio. We found that the electron density in the remote CH{sub 4}/N{sub 2} plasma was closely related to recombination reactions of major ions such as N{sub 2}{sup +}, CH{sub 4}{sup +}, CH{sub 3}{sup +}, and H{sub 2}{sup +} during diffusion from the plasma source to the substrate. The electron density and optical emission of major ions and radicals in the CH{sub 4}/N{sub 2} plasma increase at higher rf power. The ratio [N]/([N]+[C]) in a-CN{sub x} films, as measured by auger electron spectroscopy, also increases with rf power since more excited N and C species are generated. For increasing pressure, the change in electron density and emission spectra showed different behavior, which arose from recombination of ions that generated more CH{sub 4}, N{sub x} (x=1,2), and CN radicals. The majority of positive ions generated from N{sub 2} species are greatly affected by the remote effect, while the majority of positive ions generated from CH{sub 4} species are not significantly influenced, since each species has different losses dependent on the pressure. A higher N{sub 2} gas fraction in the gas mixture generated more CN radicals, which resulted not only in more N incorporated into a-CN{sub x} films but also to a reduction of H passivation that retards formation of hybrid bonding between C and N in the films. These results suggest that efficient H abstraction is required to achieve more N{identical_to}C triple bonding in CH{sub 4}/N{sub 2} plasma deposition.
- OSTI ID:
- 20714050
- Journal Information:
- Journal of Applied Physics, Vol. 98, Issue 4; Other Information: DOI: 10.1063/1.2032617; (c) 2005 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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Related Subjects
AMORPHOUS STATE
AUGER ELECTRON SPECTROSCOPY
CARBON NITRIDES
CHEMICAL BONDS
DEPOSITION
ELECTRON DENSITY
EMISSION SPECTRA
EMISSION SPECTROSCOPY
HYDROGEN IONS 2 PLUS
METHANE
MIXING RATIO
NITROGEN
PASSIVATION
PLASMA
PLASMA DENSITY
PLASMA DIAGNOSTICS
RADICALS
REACTION KINETICS
RECOMBINATION
THIN FILMS