We have investigated the effects of annealing temperature on the physical and electrical properties of the HfSixOy/HfO2 thin film for high-k gate oxides in a metal-oxide-semiconductor device. The oxidation and subsequent postoxidation N2 annealing at 500 °C of Hf deposited directly on the Si substrate results in the HfSixOy/HfO2 stack layer with excellent electrical properties. For instance, we observe a negligible hysteresis window, an excellent equivalent oxide thickness (1.2 nm), and a low leakage current density (⩽4×10−5 A/cm2 at 2 V after compensating the flatband voltage shift). However, the formation of an interfacial SiOx layer enhances as annealing temperature increases. Based on current observation, we suggest that annealing temperature must be carefully controlled to obtain the excellent electrical properties of HfO2/HfSixOy high-k gate oxides.

We have investigated the effects of high temperature annealing on the physical and electrical properties of multilayered high-k gate oxide [HfSixOy/HfO2/intermixed-layer(IL)/ZrO2/intermixed-layer(IL)/HfO2] in metal-oxide-semiconductor device. The multilayered high-k films were formed after oxidizing the Hf/Zr/Hf films deposited directly on the Si substrate. The subsequent N2 annealing at high temperature (⩾ 700 °C) not only results in the polycrystallization of the multilayered high-k films, but also causes the diffusion of Zr. The latter transforms the HfSixOy/HfO2/IL/ZrO2/IL/HfO2 film into the Zr-doped HfO2 film, and improves electrical properties in general. However, the thin SiOx interfacial layer starts to form if annealing temperature increases over 700 °C, deteriorating the equivalent oxide thickness.