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

Abstract

Pseudobilayer HfO2∕HfSixOy 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 0to60W 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∕HfSixOy 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 100kHz and less than ∼10−6A∕cm2 at −1.5V, respectively.