Method for manufacturing silicon carbide MOSFET

Abstract

The present invention discloses a method for manufacturing a silicon carbide MOSFET. The method comprises the steps of making a field oxide window on a silicon carbide epitaxial piece and forming a silicon dioxide insulating film in the field oxide window, depositing a layer of polycrystalline silicon carbide on the silicon dioxide insulating film, etching the polycrystalline silicon carbide and taking the remaining polycrystalline silicon carbide as a gate electrode, etching the silicon dioxide insulating film, and doping the polycrystalline silicon carbide and carrying out annealing. Due to the above methods, the deposed polycrystalline silicon carbide is used to make the gate electrode of the silicon carbide MOSFET, thus the adjustment ability of device threshold voltage can be improved, and the gate signal delay time can be reduced.

Description

Technical field [0001] The invention relates to the technical field of semiconductor device manufacturing, in particular to a method for manufacturing a silicon carbide MOSFET. Background technique [0002] Silicon carbide, as a representative of the third-generation semiconductor material, has outstanding advantages such as wide band gap, high saturation drift speed, high thermal conductivity and high critical breakdown electric field. It is particularly suitable for making high-power, high-pressure, high-temperature and radiation-resistant electronic devices. Compared with other wide-bandgap semiconductors, silicon carbide is the only semiconductor material that can grow a silicon dioxide layer on its surface by thermal oxidation, which means that silicon carbide is used to make high-power metal-oxide semiconductor field effect transistors (MOSFET) And an ideal material for insulated gate bipolar transistors (IGBT). [0003] However, in the process of using silicon-based semicon...

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Problems solved by technology

[0003] However, in the process of manufacturing silicon carbide MOSFET power devices using silicon-based semiconductor manufacturing technology, due to the unique properties of silicon carbide, some problems have arisen: at present, the gate electrode of silicon carbide MOSFET power devices uses doped polysilicon, due to carbonization The forbidden band width of silicon is large (3.2eV), while the forbidden band width of polysilicon is small (1.1eV), which makes the doping concentration of the polysilicon gate electrode less able to adjust the threshold voltage of silicon carbide MOSFET. Moreover, due to the resistance of polysilicon The rate is large, and the gate signal delay time is long in large-area silicon carbide MOSFET devices

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