La-base medium material high-K metal gate structure based on Ge substrate, and preparation method

The invention discloses a La-base medium material high-K metal gate structure based on a Ge substrate, and a preparation method, mainly for solving the problems of low dielectric constant of a gate oxide layer of a conventional high-K metal gate structure and diffusion of gate metal towards the gate oxide layer. The structure comprises the Ge substrate (1), an La-base high-K medium film (2), a TiN barrier layer (3), a Ti oxygen element absorption layer (4) and a heavy metal Pt gate electrode (5) from bottom to top, wherein the La-base high-K medium film (2) employs a La2O3 or LaAlO3 or La2O3/Al2O3 lamination structure with a thickness of 6-12nm; the TiN barrier layer has a thickness of 2-4nm; the Ti oxygen element absorption layer has a thickness of 3-6nm; and the heavy metal Pt gate electrode has a thickness of 100-200nm. According to the invention, the dielectric constant of the gate oxide layer is high, the interface features of the gate oxide layer/substrate are good, and the structure and the method can