Improving the electrical properties of lanthanum oxide gate dielectric film by using nitrogen and aluminum doping

In this work, results and mechanisms for improving the electrical properties of lanthanum gate oxide (La₂O₃) by using nitrogen and aluminum doping are reported. The aluminum doping resulted in the formation of a thin Al₂O₃ layer at the La₂O₃/Si interface. This layer suppressed the out-diffusion of substrate Si and the formation of interfacial silicate layer. For nitrogen doping, oxidation of substrate Si occurred and the metallic La-Si bonds can be converted into La-N bonds at the interface. Nitrogen atoms were also incorporated into the bulk network of lanthanum oxide by filling the oxygen vacancies. These effects resulted in a significant reduction on the bulk and interface trap densities and the gate leakage current.