ANNEALING EFFECT AND SUPPRESSION OF HYDRATION OF La_2O_3 THIN FILMS

摘要

Lanthanum oxide thin films were deposited using alternate injections of La(iPrCp)_3 and H_2O. The deposited films were hydrated easily when exposed to air, and Si diffusion during PDA in the La_2O_3 film was remarkable. An AIN capping layer on the La_2O_3 films was effective to prevent hydration. Annealing in NH_3 gas increased thermal stability and the dielectric constant due to nitrogen incorporation. The film annealed in NH_3 gas at 800 °C showed an EOT of 2.2nm and a leakage current of 1.7 x 10~(-8) A/cm~2 at -1 V. The amount of Si atoms diffused into the La_2O_3 films decreased in the sequence; O_2-annealed, NH_3-annealed and prenitrided samples. A pre-nitridation to form a SiN reaction barrier was effective to increase thermal stability.