Silicon carbide trench type MOSFETs integrated with SBD and preparation method thereof

Abstract

The invention provides a silicon carbide trench type MOSFETs integrated with an SBD and a preparation method thereof. A side wall gate electrode contact of the MOSFETs is located on the side wall of amain trench, a source electrode metal contact is formed at the bottom of the trench, and a Schottky metal contact is integrated. When a first quadrant is conducted forward, electrons flow from bottomto top through an inversion layer of the side wall of the trench, and a reverse conduction channel different from a conventional trench MOSFETs is formed. When a third quadrant is conducted forward,a Schottky diode is conducted at first, effectively inhibiting conduction of an in-vivo parasitic PN diode. During reverse blocking, a p-type shield layer at the bottom of the trench effectively shields a high electric field in a device body region, so that a device gate dielectric electric field and a Schottky contact electric field are greatly reduced, and an avalanche occurs at a PN junction ofthe device body region. The silicon carbide trench type MOSFETs integrated with an SBD has a low total chip area, satisfies good first and third quadrant conduction characteristics and reverse blocking abilities, and enables the static and dynamic reliability of a device to be improved.

Description

technical field [0001] The invention relates to a structure of a trench type metal-oxide-semiconductor field-effect transistor (MOSFETs) integrating a silicon carbide Schottky diode (SBD) and a preparation method thereof. Background technique [0002] In the field of power electronic conversion, reducing the loss of power devices and the area of ​​integrated chips can significantly improve the overall efficiency of the system. The critical breakdown electric field of silicon carbide is 10 times that of Si, and it is currently the most mature wide bandgap power semiconductor device. SiC trench MOSFETs have higher cell integration and non-polar surface carrier mobility, which can further reduce the chip area and on-state resistance of SiC-based power devices. This makes SiC trench MOSFETs attract more and more attention, especially for power electronics applications such as electric vehicles, charging piles, uninterruptible power supplies and smart grids. [0003] However, w...

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Problems solved by technology

[0005] The purpose of the present invention is to provide a silicon carbide trench MOSFETs integrated with SBDs, so as to alleviate the problem of excessive electric field of the gate dielectric in silicon carbide trench MOSFETs in the prior art, and at the same time greatly improve the power source when MOSFETs work in reverse. Leakage current density can effectively suppress the electrical stress of parasitic PN diodes inside SiC trench MOSFETs, thereby improving chip integration and functionality, reducing the total chip area of ​​SiC MOSFETs and SBDs and the cost of the entire power module

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