Nucleation and interface formation mechanisms in atomic layer deposition of gate oxides

We present an in situ infrared spectroscopic study of the interface formation during atomic layer deposition of alternative high-permittivity (high-kappa) gate dielectrics. Layer-by-layer oxide growth may be achieved by alternating pulses of a molecular metal precursor (e.g., trimethylaluminum for aluminum oxide growth) and water vapor. Contrary to common belief, we find that the metal precursor, not the oxidizing agent, is the key factor to control Al2O3 nucleation on hydrogen-terminated silicon. Metal surface species catalyze subsurface Si oxidation. These findings have direct implications on growth conditions to optimize semiconductor-dielectric interfaces. (C) 2003 American Institute of Physics.