A trench-type silicon carbide mosfet prepared based on a buffer layer and a preparation method thereof

Abstract

The invention provides a trench-type silicon carbide MOSFET prepared based on a buffer layer and a preparation method thereof, comprising: a drain (10), a silicon carbide substrate (9), and a silicon carbide N epitaxy (8); The upper left side of the silicon N epitaxy (8) includes a Pwell region (3), and the trench region (32) includes a bottom-up PplusBottom region (7), a gate oxide region (6) and a polysilicon region (5); source (1). The trench-type silicon carbide MOSFET prepared based on the buffer layer and the preparation method thereof provided by the present invention apply an implanted buffer layer during Pwell implantation to form a PwellBottom with a depth greater than that of the trench, and then perform silicon carbide etching in the PwellBottom area to make the bottom of the trench Part of the PwellBottom is reserved, and the PwellBottom and Pwell are kept connected through the unetched area, that is, the grounded contact is reserved; under the protection of the sidewall of SiN or SiO2, the PwellBottom is enriched and implanted to form PplusBottom; the Since PplusBottom maintains the same potential at the same source, it can pinch off the electric field of the gate oxide at the trench to avoid failure caused by the strong electric field of the gate oxide.

Description

technical field [0001] The invention relates to the technical field of preparation of trench-type silicon carbide MOSFETs, in particular to a trench-type silicon carbide MOSFET prepared based on a buffer layer and a preparation method thereof. Background technique [0002] Silicon carbide MOSFET is an important part of modern power electronic devices. Due to its high frequency and high power density, it can greatly reduce the size of the power supply and improve the conversion efficiency. Silicon carbide MOSFETs mainly include two structures, planar and trenched. Due to the low channel mobility of planar silicon carbide MOSFETs, the current density is not as good as that of trenched silicon carbide MOSFETs. Infineon, ROHM and other well-known semiconductor device manufacturers generally use trench MOSFETs. For example, ROHM uses a double trench structure, and Infineon uses a single trench plus a single-sided implanted P-emmitter structure to weaken the corners of the trench....

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Problems solved by technology

[0003] However, the protection of the bottom of the gate of the above-mentioned trench MOSFET is not well considered, which will increase the risk of breakdown and limit the service life of the trench MOSFET. Therefore, it is necessary to improve this defect

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