Postannealing effect on pseudobilayer HfO2/HfSixOy/Si gate oxides formed by an inductively coupled sputtering process.

Pseudobilayer HfO₂/HfSi_xO_y gate dielectrics in metal-oxide-semiconductor devices were prepared using an inductively coupled rf plasma sputtering technique. This sputtering method was designed to improve the uniformity and efficiency of formation of high-quality gate dielectrics at room temperature. Crystallization of the gate dielectrics was easily controlled from amorphous to monoclinic by varying the external power from 0 to 60 W at RT. The chemical bond states of the interfacial layers in the as-deposited and postannealed samples were analyzed with an x-ray photoelectron spectroscopy (XPS) system. The XPS results revealed that the interfacial layers of the as-deposited and annealed samples were hafnium silicide and hafnium silicate, respectively. Compared with the as-deposited sample, the pseudobilayer HfO₂/HfSi_xO_y gate dielectric annealed at 750 °C yielded excellent electrical characteristics due to the hafnium silicate interfacial layer. The dielectric constant and leakage current of the postannealed samples were about 15 at 100 kHz and less than ∼10^-6 A/cm² at -1.5 V, respectively. [ABSTRACT FROM AUTHOR]