As the scaling of MOSFETs continues towards 45 nm technology node, it is inevitable that Hf-based high-k materials replace the traditional SiO2 as the gate dielectrics of MOSFETs. But there are still many issues to be settled. Rare earth doping can increase the k value of dielectrics, decrease the defect densities of dielectrics and modulate the threshold voltage shift of MOSFETs. This paper reviews recent progress, the challenge of Hf-based high-k materials, the influence of rare earth doping on Hf-based high-k materials and its future trend.