| An amorphous hydrogenated carbon material such as glow discharge polymer(GDP),which has low density,low atomic number,wonderful surface smoothness,uniform wall thickness,etc,is typically used as a nominal ablator in inertial confinement fusion experiments(ICF).Currently,GDP films are fabricated using plasma-enhanced chemical vapor deposition(PECVD)technology.The PECVD environment simultaneously contains charged ions,neutrals,electrons and other plasma species after ionization of Tran-2-Butene/Hydrogen(T2B/H2),leading to the complicated growth mechanisms.These groups deposit on the surface of films,which sustain the growth of GDP films.Thus,the direct factors affecting the film properties are the groups in plasma.However,researchers only focus on the correlations between the films properties and the technology parameters in PECVD processes.The influence of the plasma parameters on the growth process and the properties of films are not fully known.This article has described the correlation between the spatial distribution of T2B/H2 plasma parameter and the properties of GDP films during the films growth.The influence of T2B/H2 plasma parameters on the films growth has been discussed,which as functions of radial distance and axial distance.The correlation between T2B/H2/TMS plasma parameters and structure of Si-GDP films has also been discussed.Based on the above researches,the following research are found:(1)The plasma parameters of T2B/H2 were investigated at radial distance of 0-20 mm and axial distance of 15 mm-35 mm,respectively.Firstly,the effects of radial distance on plasma properties such as plasma potential,electron density and effective electron temperature were diagnosed by Langmuir probe.Secondly,the effects of radial distance and axial distance on ions density and ion energy distributions(IED)were diagnosed by energy-resolved mass spectrometer.The results show that both the electron density and the effective electron temperature decrease with increasing radial distance.The fraction of high-energy electrons decreases and plasma potential decreases with increasing radial distance.Additionally,the relative intensities of saturated CH ions increase with radial distance,while the unsaturated CH ions decrease.As the axial distance increases,the dissociation weakens while the polymerization enhances.The IED curves of C2H6+ present a bimodal distribution at the pressure of 10 Pa and radio frequency power of 15 W.The bimodal distribution becomes increasing obvious with increasing radial distance,while the opposite trend is observed with increasing axial distance.(2)The deposition rate,surface morphology,and chemical structure of GDP films were investigated at radial distance of 0 mm-20 mm and axial distance of 15 mm-35 mm,respectively.The results show that the deposition rates decrease with increasing spatial distances at the pressure of 10 Pa and radio frequency power of 15 W.The strong etching effect leads to the formation of etching pits when the spatial distance is too short.And the dome defects form at longer axial distance because of the enhanced polymerization.At the axial distance of 20 mm,there little defect on the surface of GDP films.As the radial distance increase,C-C bonds increase and C=C bonds decrease.The cross-linking structure of GDP films is weakened with increasing axial distance.(3)The radial distribution of plasma parameters was discussed after injecting tetramethylsilane(TMS)in T2B/H2,the chemistry structures and bond configurations of Si doped glow discharge polymer(Si-GDP)were investigated at radial distance of 0 mm-20 mm.The results show that the relative intensities of small mass CH ions first increase and then decrease with increasing radial distances,whereas the large mass CH ions are on the contrary.And the ion energy decrease with increasing radial distances.The ratio of spp/sp2 and Si.at%reduce with increasing radial distances.Based on the correlations between spatial distribution of T2B/H2 plasmas parameters and GDP film properties,it can further provides a theoretical foundation for understanding the change of films properties.And also contributes to the research about orrelations between T2B/H2/TMS plasma parameters and structure of Si-GDP films. |
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