Toukabri Rim, Shi Yujun
Department of Chemistry, University of Calgary, Calgary, Alberta, T2N 1N4 Canada.
Phys Chem Chem Phys. 2014 May 7;16(17):7896-906. doi: 10.1039/c4cp00275j.
The gas-phase reaction chemistry when using dimethylsilane (DMS) as a source gas in a hot-wire chemical vapor deposition (CVD) process has been studied in this work. The complex chemistry is unraveled by using a soft 10.5 eV single photon ionization technique coupled with time-of-flight mass spectrometry in combination with the isotope labelling and chemical trapping methods. It has been demonstrated that both free-radical reactions and those involving silylene/silene intermediates are important. The reaction chemistry is characterized by the formation of 1,1,2,2-tetramethyldisilane (TMDS) from dimethylsilylene insertion into the Si-H bond of DMS, trimethylsilane (TriMS) from free-radical recombination, and 1,3-dimethyl-1,3-disilacyclobutane (DMDSCB) from the self dimerization of either dimethylsilylene or 1-methylsilene. At low filament temperatures and short reaction time, silylene chemistry dominates. The free-radical reactions become more important with increasing temperature and time. The same three products have been detected when using tantalum and tungsten filaments, indicating that changing the filament material from Ta to W does not affect much the gas-phase reaction chemistry when using DMS as a source gas in a hot-wire CVD reactor.
本工作研究了在热丝化学气相沉积（CVD）工艺中使用二甲基硅烷（DMS）作为源气体时的气相反应化学。通过使用软10.5 eV单光子电离技术结合飞行时间质谱，并结合同位素标记和化学捕获方法，揭示了复杂的化学过程。结果表明，自由基反应以及涉及硅烯/硅宾中间体的反应都很重要。反应化学的特征在于，二甲基硅烯插入DMS的Si-H键形成1,1,2,2-四甲基二硅烷（TMDS），自由基重组形成三甲基硅烷（TriMS），以及二甲基硅烯或1-甲基硅宾的自二聚反应形成1,3-二甲基-1,3-二硅环丁烷（DMDSCB）。在低灯丝温度和短反应时间下，硅烯化学占主导。随着温度和时间的增加，自由基反应变得更加重要。使用钽丝和钨丝时检测到了相同的三种产物，这表明在热丝CVD反应器中使用DMS作为源气体时，将灯丝材料从Ta改为W对气相反应化学影响不大。
