The effective work function (Φm,eff) of TaN on HfO2 after postmetallization annealing (PMA) was investigated using TaN∕HfO2∕SiO2∕Si as a sample structure. We found that Φm,eff on HfO2 is stable at PMA temperatures of less than 600°C and is 4.6eV, which is approximately 0.2eV higher than that on SiO2. In contrast, Φm,eff is modulated by PMA at temperatures greater than 750°C. An analysis by x-ray photoelectron spectroscopy suggests that the increased Φm,eff is strongly related to Ta oxide formation near the TaN∕HfO2 interface. The modulation of Φm,eff on HfO2 is discussed on the basis of intrinsic and extrinsic Fermi level pinning due to Ta–O bond formation at the TaN∕HfO2 interface.

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High-permittivity (high-k) dielectrics with HfO 2 /Hf x Si 1−x O y /Si structures were fabricated using plasma oxidation and the subsequent annealing for a Hf/SiO 2 /Si structure. By changing a SiO 2 film in an initial structure from plasma oxidation at a low temperature to dry oxidation at a high temperature, the drastic decrease in the trap density in an interfacial layer (IL: Hf x Si 1−x O y ) could be successfully achieved, which showed an interface state density of 1 × 10 11 eV −1 cm −2 , an effective oxide thickness (EOT) of 1.2 nm and four orders decrease in the leakage current density relative to SiO 2 with the same EOT. The influence of post-annealing on structural and electrical properties of the IL was investigated by using x-ray photoelectron spectroscopy and a transmission electron microscope. It was clarified that the increase in EOT after post-annealing at 900 • C was caused by the decrease in Hf content in the IL and the increase in the IL thickness. The kinetics of the IL formation is discussed in detail. The effects of O 2 gas ambience during post-annealing on EOT and flat-band voltage (V fb ) were investigated, which showed that the V fb decreased with increasing O 2 gas pressure while maintaining a low EOT.

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High-permittivity (high-k) dielectrics with HtD 2 IHf x Si 1 _ x OylSi structures were fabricated using plasma oxidation and subsequent annealing of HflSi0 2 /Si structure. By replacing Si0 2 film of initial structure from plasma oxidized Si0 2 to thermal oxidized Si0 2 , the drastic decrease of traps in interfacial layer (IL: HfxSi1_xO y ) could be successfully achieved, which shows interface state density of 1xlOll ey·lcm-2 , effective oxide thickness (EOT) of 1.2 nm, and 4 orders decrease of leakage current density relative to Si0 2 with EOT of 1.2 nm. The influence of post annealing on structural and electrical properties of IL was investigated by using XPS analysis and TEM observation. It was clarified that the increase of EOT after post annealing at 900°C is caused by the decrease of Hf content in IL and the increase of IL thickness. The kinetics of IL formation is discussed in details.