Validating optical emission spectroscopy as a diagnostic of microwave activated CH{sub 4}/Ar/H{sub 2} plasmas used for diamond chemical vapor deposition

Journal Article · Sun Feb 15 00:00:00 EST 2009 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.3078032· OSTI ID:21190028

Jie, Ma; Ashfold, Michael N. R. ^[1]; Mankelevich, Yuri A ^[2]

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1. School of Chemistry, University of Bristol, Bristol BS8 1TS (United Kingdom)
2. Skobel'tsyn Institute of Nuclear Physics, Moscow State University, Vorob'evy gory, Moscow 119991 (Russian Federation)

Spatially resolved optical emission spectroscopy (OES) has been used to investigate the gas phase chemistry and composition in a microwave activated CH{sub 4}/Ar/H{sub 2} plasma operating at moderate power densities ({approx}30 W cm{sup -3}) and pressures ({<=}175 Torr) during chemical vapor deposition of polycrystalline diamond. Several tracer species are monitored in order to gain information about the plasma. Relative concentrations of ground state H (n=1) atoms have been determined by actinometry, and the validity of this method have been demonstrated for the present experimental conditions. Electronically excited H (n=3 and 4) atoms, Ar (4p) atoms, and C{sub 2} and CH radicals have been studied also, by monitoring their emissions as functions of process parameters (Ar and CH{sub 4} flow rates, input power, and pressure) and of distance above the substrate. These various species exhibit distinctive behaviors, reflecting their different formation mechanisms. Relative trends identified by OES are found to be in very good agreement with those revealed by complementary absolute absorption measurements (using cavity ring down spectroscopy) and with the results of complementary two-dimensional modeling of the plasma chemistry prevailing within this reactor.

• OSTI ID: 21190028
• Journal Information: Journal of Applied Physics, Vol. 105, Issue 4; Other Information: DOI: 10.1063/1.3078032; (c) 2009 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ABSORPTION
ARGON
CHEMICAL VAPOR DEPOSITION
DIAMONDS
EMISSION SPECTROSCOPY
FLOW RATE
GROUND STATES
HYDROGEN
METHANE
MICROWAVE RADIATION
PLASMA
PLASMA DIAGNOSTICS
POLYCRYSTALS
POWER DENSITY
RADICALS
SIMULATION
SUBSTRATES
TWO-DIMENSIONAL CALCULATIONS
ULTRAVIOLET SPECTRA