In situ investigation of growth and thermal stability of ultrathin Si layers on the HfO2/Si(100) high-κ dielectric system -: art. no. 191904

We report on growth behavior and thermal stability of ultrathin (0.5 - 12 nm) Si layers grown on HfO2 (3 nm)/ Si (100) by pulsed laser deposition (PLD) as investigated by in situ x-ray photoelectron spectroscopy and low-energy ion scattering spectroscopy. Layer-by-layer growth of ultrathin Si overlayer was observed during room-temperature deposition, while an island-like growth behavior dominated at T. 900 K. Vacuum annealing of the Si(3.5 nm) / HfO2 (3 nm)/ Si (100) structure resulted in Si crystallization and coarsening. The process was accompanied by hafnium oxide reduction at the surface causing HfO2 layer decomposition and hafnium silicide formation. These interface reactions depended on the thickness of the Si cap layer - the thicker (12 nm) Si layer on HfO2 (40 nm)/ Si (100) appeared to be stable at least up to T=1200 K. An ultrathin (0.3 nm) Al2O3 layer PLD deposited between HfO2 and the Si overlayer also effectively inhibited the reactions up to T=1200 K. (c) 2005 American Institute of Physics.