Disproportionation of dimethylalane on aluminum surfaces. Part 1. Experimental studies

An experimental study of the growth chemistry of dimethylaluminum hydride ( DMAH) has been performed to elucidate the reaction pathways underlying the growth of aluminum by chemical vapor deposition. Results find that DMAH gro ws clean aluminum films through a surface disproportionation mechanism, whi ch produces trimethylaluminum (TMA) and hydrogen as byproducts. Effusive be am scattering and temperature programmed desorption experiments provide evi dence that the growth mechanism proceeds through the adsorption and decompo sition of DMAH into Al(CH3)(2), Al(CH3), and CH3 surface species. TMA is pr oduced via recombination reactions involving freely diffusing surface methy l groups as primary intermediates. At high temperatures (> 560.600 K), thes e methyl groups undergo dehydrogenation reactions which lead to irreversibl e carbon contamination. This latter reaction pathway is proposed to be acco mpanied by methyl radical ejection reactions. (C) 2001 Elsevier Science B.V . All rights reserved,