Performance improvement of n-MOSFETs with constituent gradient HfO2/SiO2 interface

We investigated an influence of the constituent gradient interfacial layer (CG-IL) between HfO2 and SiO2 on the electrical characteristics of high-k MOSFETs. The CG-IL structure was successfully grown by the newly developed layer-by-layer deposition and annealing (LL-D & A) technique. The dielectric constant of the CG-IL was higher than that of SiO2-IL, because Hf atoms were diffused into the underlying SiO2 layer and Si-O-Hf bonds were formed. Furthermore, the CG-IL structure can significantly reduce the scattering center which is considered to exist at the HfO2/SiO2 interface, and thus improve the effective electron mobility. We consider that the CG-IL structure is useful to improve the electrical characteristics of n-MOSFETs with HfO2 films.