A mass spectroscopic study of the vapor phase thermal decomposition of trimethylamine

Trimethylamine has been used in the growth of compound semiconductors either through the formation of an adduct, as in trimethylamine allane, or as a possible growth reactant. The kinetics of the gas-phase decomposition and dominant reaction products relevant to these applications were determined in this study. The multistep thermal decomposition of trimethylamine in hydrogen (H-2 and D-2) in a laminar-flow tube reactor was studied by in situ mass spectroscopy and the analysis of isolated decomposition products. A dimethylamino radical and a methyl group are formed in a first-order Arrhenius-type decomposition that begins at similar to 525 and is complete at similar to 650 degrees C. Additional products of this first step were deuterated methane, CH3D, (in D-2) and ethane, C2H5. The activation energy is 50.8 kcal/mol. In subsequent steps the dimethylamino radical degrades through the series N-methylenemethylamine, (CH3)N = CH2, the imidoyl radical (CH3)N = (CH)-H-., and hydrogen cyanide, accompanied by loss of H-2, hydrogen radical, and methyl radical, respectively, as well as by the formation of unidentified solids.