Trench silicon carbide MOSFET device and preparation method thereof

Abstract

The invention discloses a trench silicon carbide MOSFET device and a preparation method thereof. The trench silicon carbide MOSFET device comprises an N-epitaxial layer, at least two P+ type injection regions suspended in the N-epitaxial layer, and a trench gate structure with two bottom corners respectively contacted with the two P+ type injection regions. Particularly, the electric field intensity of the oxide layer at the bottom and the side surface of the gate groove is effectively reduced, and the reliability of the gate oxide is improved; a depletion region is formed when the floating type P-type buried layer is reversely blocked, so that the reverse voltage withstanding characteristic of the device is obviously improved; the gate-drain contact area is reduced, the gate-drain capacitance is reduced, and the switching rate is improved.

Description

technical field [0001] The invention belongs to the technical field of semiconductors, and more specifically, the invention relates to a trench silicon carbide MOSFET device and a preparation method thereof. Background technique [0002] Silicon carbide (SiC) material, as one of the representatives of the third-generation wide bandgap semiconductor materials, has the advantages of large bandgap width, high critical field strength, high thermal conductivity, high carrier saturation rate, and high power density. SiC can be thermally oxidized to obtain oxide materials (SiO 2 ), thus making it possible to develop MOSFET devices and circuits based on silicon carbide materials. Compared with other types of SiC power electronic devices, SiC MOSFET has the advantages of high switching speed, high reverse blocking voltage, etc., and the driving circuit is simple, and it is compatible with existing power electronic devices (silicon-based power MOS FET and IGBT) Well, it has been wid...

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Problems solved by technology

[0005] The current method to solve the electric field concentration of the gate trench generally prepares the P+ shielding area protection structure at the bottom, which can greatly reduce the electric field intensity of the gate oxide layer when the device breaks down, and enhance the reliability of the gate oxide layer, which is located at the bottom of the trench. The shielding gate can make the oxide layer at the bottom and corner of the trench get stronger protection, but the oxide layer on the sidewall of the trench will still be potentially challenged by the high electric field in the blocking state

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