Preparation method of high k-gate dielectric layer and silicon carbide MOS power device

Abstract

The present invention provides a preparation method of a high k-gate dielectric layer and a silicon carbide MOS power device. The preparation method comprises the steps of: performing high-temperaturesacrificial oxidation of a silicon carbide epitaxial wafer with a first conductive type, and forming a sacrificial oxidation layer at the upper surface of the epitaxial layer of the silicon carbide epitaxial wafer; performing corrosion of the sacrificial oxidation layer until the sacrificial oxidation layer on the epitaxial layer is completely removed; performing high-temperature surfacing processing of the upper surface of the epitaxial layer after removal of the sacrificial oxidation layer, and forming a smooth passivated surface; and depositing an Al2O3 dielectric coating layer, a LaAlO3 dielectric layer and an Al2O3 dielectric coating layer at the smooth passivated surface in order, performing annealing of a laminated structure formed by the Al2O3 dielectric coating layer, the LaAlO3dielectric layer and the Al2O3 dielectric coating layer, and forming a high k-gate dielectric layer. Compared to the prior art, the preparation method of the high k-gate dielectric layer and the silicon carbide MOS power device can reduce the interface defects caused by impurities and/or surface lattice defects at a SiC/SiO2 interface so as to improve the voltage endurance capability of the gate dielectric layer.

Description

technical field [0001] The invention relates to the technical field of semiconductor devices, in particular to a method for preparing a high-k gate dielectric layer and a silicon carbide MOS power device. Background technique [0002] Silicon carbide semiconductor material has a wide band gap (3.2eV), a high breakdown electric field strength (2.2MV / cm), a high high saturation electron mobility (2.0×10 7 cm / s), high thermal conductivity (5.0W / cm K), excellent physical and chemical stability and other characteristics, suitable for the manufacture of high power, high voltage, high operating temperature, high operating frequency power semiconductor devices material, and since silicon carbide is the only compound semiconductor material that has the ability to generate dense SiO through oxidation 2 The ability of the dielectric layer, which makes the silicon carbide process and the conventional CMOS process have higher process compatibility and maturity, and also makes the silico...

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Problems solved by technology

[0005] 2. The crystal lattice of silicon carbide has anisotropic characteristics, and its oxidation rate has strong anisotropy, which leads to the problem of uneven thickness of the oxide layer on different crystal planes;

[0006] 3. SiO 2 The dielectric constant K of the dielectric material OX The value is only 3.9, making SiC / SiO 2 SiO in the interface electric field intensity distribution 2 A higher electric field strength will appear on the side, thereby limiting the high breakdown electric field strength of SiC

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