La-based medium material high-K metal gate structure based on Si substrate and preparation method thereof

The invention discloses a La-based medium material high-K metal gate structure based on a Si substrate and a preparation method thereof, and mainly solves the problems that the gate oxide dielectric constant of the conventional high-K metal gate structure is low and gate metal is diffused to the gate oxide. The high-K metal gate structure comprises a La-based high-k gate medium film (1), a TiN barrier layer (2), a Ti oxygen adsorption layer (3) and a heavy metal Pt gate electrode (4) which are arranged on the Si substrate from the bottom to the top. A La2O3 or LaAlO3 or La2O3/Al2O3 laminated structure of which the thickness is 4-10nm is adopted for the La-based high-k gate medium film; the thickness of the TiN barrier layer is 2-3nm; the thickness of the Ti oxygen adsorption layer is 4-6nm; and the thickness of the heavy metal Pt gate electrode is 100-150nm. The gate oxide dielectric constant is high and the gate oxide/substrate interface property is great so that the structure can be used for manufacturing a