A trench-type silicon carbide MOSFET with T-type bottom protection and preparation method thereof

Abstract

The invention provides a T-type bottom-protected trench-type silicon carbide MOSFET and a preparation method thereof, comprising: a drain (10), a silicon carbide substrate (9), a silicon carbide N epitaxy (8); a silicon carbide N The upper left side of the epitaxy (8) includes the Ppluswell region (5) and the first N+ region (3) above the Ppluswell region (5); the trench region (11); the insulating dielectric isolation layer (2); the source electrode (1) ). In the present invention, by applying an implanted buffer layer, a Ppluswell package Pwell morphology is formed, and then the Ppluswell region is selectively etched to obtain a silicon carbide trench, and a Ppluswell is reserved between the two trenches, and a part of the Ppluswell is reserved at the bottom of the trench. In order to form the source electrode; under the protection of the silicon nitride sidewall, the residual Ppluswell is concentrated and implanted to form a PplusBottom, where the PplusBottom is connected to the source electrode through the unetched Ppluswwell on the edge; the unetched Ppluswell is formed The source electrode is used to deplete the silicon carbide N epitaxy with PplusBottom, and the drift region is depleted to avoid excessive electric field impacting the gate oxide and Pwell at the corner, and improve the withstand voltage level of the device.

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 with T-type bottom protection and a preparation method thereof. Background technique [0002] Compared with the traditional silicon MOSFET, the silicon carbide MOSFET has the characteristics of fast turn-on and turn-off, low switching loss, low on-resistance, etc. It is suitable for working in the field of higher operating frequency. Can work in a higher temperature environment. Therefore, 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. [0003] 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 ...

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Problems solved by technology

[0005] In view of this, it is necessary to provide a trench silicon carbide MOSFET with T-shaped bottom protection and its preparation method to solve the gate oxide and P-type substrate withstand voltage at the corner caused by excessive electric field impact in the prior art Minor technical issues that tend to drain the battery

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