Fabrication and electrical characteristics of ultrathin (HfO2)x(SiO2)1?x films by surface solgel method and reaction-anneal treatment
Hafnium oxide (HfO2) films were deposited on Si substrates with a pre-grown oxide layer using hafnium chloride (HfCl4) source by surface solgel process, then ultrathin (HfO2)x(SiO2)1?x films were fabricated due to the reaction of SiO2 layer with HfO2 under the appropriate reaction-anneal treatment. The observation of high-resolution transmission electron microscopy indicates that the ultrathin films show amorphous nature. X-ray photoelectron spectroscopy analyses reveal that surface solgel derived ultrathin films are HfSiO alloy instead of HfO2 and pre-grown SiO2 layer, and the composition was Hf0.52Si0.48O2 under 500C reaction-anneal. The lowest equivalent oxide thickness (EOT) value of 0.9nm of film annealed at 500C has been obtained with small flatband voltage of ?0.31V. The experimental results indicate that a simple and feasible solution route to fabricate (HfO2)x(SiO2)1?x composite films has been developed by means of combination of surface solgel and reaction-anneal treatment.
(hfo2)x(sio2)1?x surface solgel reaction-anneal high-k dielectrics