Diagnosis Of The Emission Spectroscopy Of Plasma

The research of the plasma parameters during microwave plasma CVDof diamond is very important for preparation of high quality diamond film. Inthis paper, optical emission spectroscopy has been used to measure thecompressed waveguide microwave hydrogen plasma and compressedwaveguide microwave CVD plasma. Plasma internal particals, plasmaparameters, physical-chemical processes and plasma behavior are investigated.At the same time, optical emission spectroscopy has been used to measurebromomethane in the fumigator quantitatively and qualitatively.（1） Under the continuous high pressure （5kPa to1atmosphere）,compressed waveguide microwave hydrogen plasma has been measured byoptical emission spectroscopy. The influence of working pressure on H_α, H_β,Hγand H_δof hydrogen Balmer series and on plasma electron excitationtemperature has been investigated. The results show that the intensity of H_α,H_β, H_γand H_δlines of hydrogen Balmer series achieved maximum when thepressure was20kPa and then decreased as the gas pressure increased. Thedecreasing trend of H_αand H_βis more obvious than Hγand H_δ. The plasmaexcitation temperature decreased and then tended towards stability as the gaspressure increased.（2） During the process of compressed waveguide microwave plasmaCVD of diamond films, optical emission spectroscopy has been used to studythe internal radicals and their relationship with reaction conditions. Thespacial measurement of plasma spectroscopy along broad and narrow side ofwaveguide reflected the spatial distribution of internal radicals and activeparticals in microwave CVD plasma. The results show that the main activeparticles in CH4/H2plasma during microwave CVD diamond deposition were H_α（656.30nm）, H_β（486.25nm） and H_γ（434.56nm） of hydrogen Balmerseries, Fulcher-α（d³Π_u—a³Πg） band of hydrogen molecular, CH C²ΔΣ⁺—X²Π,B²Σ—X²Π, A²Δ—X²Π bands, C₂Swan band, C₂Mulliken （d¹Σ+_u⁺—x¹Σg）band and C2Deslandres-D’Azambuja （C¹Π_g—b¹Π_u⁺） band. The species inplasma increased with the methane concentration increasing and theincreasing of C——2Swan band was most obvious. The quality of diamond filmdecreases with the methane concentration increasing. In broad side ofwaveguide, the plasma intensity decreased from center to both sides. Innarrow side of waveguide, the plasma intensity decreased from lower to upperand carbonous species intensity in the middle of the plasma ball was higherthan both sides.（3） In this paper, a hollow cathode discharge tube using a pulsed radiofrequency power source has been designed. A pulsed radio frequency hollowcathode plasma source has been produced by exciting working gas containingbromomethane and the plasma emission spectroscopy has been measured byOcean Optics HR4000high resolution spectroscopy. The influence of gaspressure and bromomethane concentration on the intensity of the bromineatom characteristic peaks has been investigated. The results show thatbromide635.07and700.52nm characteristic peaks were identified. Theintensity of bromine atom characteristic peaks decreased with the increasingof gas pressure at the same concentration, and increased with the increasing ofconcentration of bromomethane under the same gas pressure. The linearrelation between the intensity and the bromomethane may be used to onlinemeasure the concentration of the bromomethane in the fumigator.