A good understanding of the gas-phase reaction chemistry in chemical vapor deposition (CVD) is important for the development of a comprehensive deposition model for a rational optimization of the process. We have employed laser ionization mass spectrometry in combination with isotope labeling and chemical trapping methods to unravel the complex gas-phase chemistry in the catalytic CVD process with organosilicon compounds. Several complimentary ionization methods, including the non-resonant single photon ionization with a vacuum ultraviolet laser radiation of 118 nm (10.5 eV) and laser-induced electron ionization, have been developed in our laboratory. The results from using these methods for the study of reaction chemistry of methyl-substituted silane molecules (mono-, di-, tri-, and tetra-methylsilane) will be presented in this work. We have shown that the rate-limiting step in the primary decomposition of methyl-substituted silane molecules is the Si-H bond cleavage on the metal surfaces. Our study on the effect of filament materials has led to the conclusion that the decomposition chemistry on the metal filament surfaces play an important role in determining the subsequent secondary gas-phase reactions in the reactor that produce the actual film growth precursors. Comparison of the secondary gas-phase reaction chemistry of the four compounds sheds lights on the influence of increasing number of Si-H bond. A switch from radical-dominated chemistry to silylene-dominated chemistry occurs as the number of Si-H bond increases in the methyl-substituted silane molecules.

Unraveling the complex chemical vapor deposition chemistry using laser ionization mass spectrometry

248th National Meeting (2014)

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