Groove type silicon carbide MOSFET prepared based on buffer layer and preparation method thereof

Abstract

The invention provides a groove type silicon carbide MOSFET prepared based on a buffer layer and a preparation method thereof. The groove type silicon carbide MOSFET comprises a drain electrode (10), a silicon carbide substrate (9) and a silicon carbide N epitaxy (8), the left side of the upper part in the silicon carbide N epitaxy (8) comprises a Pwell region (3), and the trench region (32) comprises a PlusBottom region (7), a gate oxide region (6) and a polycrystalline silicon region (5) from bottom to top; and a source (1). According to the groove type silicon carbide MOSFET prepared based on the buffer layer and the preparation method thereof, the injection buffer layer is applied during Pwell injection, a Pwell Bottom with the depth larger than that of the groove is formed, then silicon carbide etching of a Pwell Bottom area is carried out, part of the Pwell Bottom is reserved at the bottom of the groove, the Pwell and the Pwell are kept in a connection state through an unetched area, namely, a grounded contact is reserved, and the groove type silicon carbide MOSFET prepared based on the buffer layer and the preparation method of the groove type silicon carbide MOSFET are obtained. Under the protection of the side wall of SiN or SiO2, the Pwell Bottom is subjected to enrichment injection, and a Pplus Bottom is formed; the PplusBottom can pinch off the electric field of the gate oxide at the groove due to the fact that the homologous electrode is kept equipotential, and the failure caused by the strong electric field of the gate oxide is avoided.

Description

technical field [0001] The invention relates to the technical field of trench-type silicon carbide MOSFET preparation, 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 planar and trench structures. Due to the low channel mobility of planar silicon carbide MOSFETs, the current density is not as good as that of trench silicon carbide MOSFETs. Well-known semiconductor device manufacturers such as Infineon and Rohm generally use trench MOSFETs. For example, Rohm uses a double-trench structure, and Infineon uses a single-trench and single-side implanted P-emitter structure to weaken the corners of the trench. The electric fi...

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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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