Surface reactions in the chemical vapor deposition of aluminum by triisobutylaluminum pyrolysis.

In our studies of the deposition of aluminum films by triisobutylaluminum (TIBA) pyrolysis on clean and oxidized Si(111) (7x7), Si(100) (2x1), an evaporated aluminum film on silicon, and Al(111) surfaces, we have observed several interesting chemistries. First, the rate of elimination of the alkyl ligands from aluminum during steady state growth is limited by beta-hydride elimination from surface-bound isobutyl species to give isobutene and hydrogen. Neither of these species chemisorb strongly on aluminum surfaces. Second, this reaction is highly structure sensitive, being about 100 times faster on flat Al(111) terraces than at other types of surface sites. Third, in the steady state deposition of aluminum on top of silicon, gas phase silanes such as isobutyl- and diisobutylsilane are produced.