Surface organometallic chemistry in the chemical vapor deposition of Aluminum films using triisobutylaluminum: beta-Hydride and beta-alkyl elimination reactions of surface alkyl intermediates.

Thermal decomposition of triisobutylaluminum (TIBA) to deposit aluminum films shows promise as a way to form conductive contacts on silicon-based electronic devices. An important step in the steady state deposition is the reaction of TIBA with the growing aluminum surface. We have studied this chemistry by reacting TIBA with single crystal Al(111) and Al(100) surfaces. A combination of effusive molecular beam scattering, thermal desorption mass spectroscopy, Auger electron spectroscopy, low-energy electron diffraction, high resolution electron energy loss spectroscopy, and scanning electron microscopy were used in these studies. We find that TIBA decomposes on both of these aluminum surfaces above -470K by beta-hydride elimination reactions to deposit aluminum and evolve hydrogen and isobutylene. This surface beta-hydride elimination reaction is the rate-determining step. We find that the reaction is 2-5 times faster on Al (111) than on Al(100).