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The evolution of microstructure and phase structure of ultrathin HfO2 films on Si(100) under ultrahigh-vacuum annealing is investigated in situ by x-ray photoelectron spectroscopy (XPS) and low-energy ion scattering (LEIS). The onset temperature of degradation is found to depend on film thickness. It is established that, for HfO2 (4 nm)/SiO2 (1 nm)/Si(100) specimens, 5-min annealing at about 900°C causes silicon (LEIS evidence) to appear on the surface, the silicon being uncombined with oxygen or the metal (XPS evidence). A longer annealing at the same temperature produces HfSix; annealing at 950°C converts the entire HfO2 film into polycrystalline silicide whose grains are partly oriented as the Si substrate. With respect to annealing in a low-oxygen environment, the experimental results support a model whereby the degradation of an ultrathin HfO2 film starts with the formation of nanopores by …
Publication date: 
1 Jul 2006

AV Zenkevich, YY Lebedinskii, NS Barantsev, VN Nevolin, VS Kulikauskas, G Scarel, M Fanciulli

Biblio References: 
Volume: 35 Issue: 4 Pages: 210-215
Russian Microelectronics