Bottom protective ground trench type silicon carbide MOSFET and preparation method thereof

Abstract

The invention provides a bottom protection ground trench type silicon carbide MOSFET and a preparation method thereof, comprising: a drain (11), a silicon carbide substrate (10), a silicon carbide N epitaxy (9); a silicon carbide N epitaxy ( 9) Pwell region (5) on the left side above the interior, trench region (12) on the middle side, and Ppluswell region (6) on the right side; insulating dielectric isolation layer (2) and source electrode (1). The present invention includes Pwell, Ppluswell and PBottomPlus, and Pwell and Ppluswell can keep Ppluswell with relatively thick and deep doping under the action of implanting the buffer layer, taking into account the adjustment of Vth and breakdown resistance; selective etching of Pwell and Ppluswell at the same time area, the two sides of the obtained trench are Pwell and Ppluswell respectively, and part of the Ppluswell area is reserved on one side of the bottom of the trench; based on the sidewall protection layer, the Ppluswell at the bottom of the trench is enriched and implanted to obtain a densely doped and deep PBottomPlus; The Ppluswell retained at the bottom of the trench has a good electrical connection with PBottomPlus, which ensures that the adjacent PBottomPlus area can be grounded, pinches off the strong electric field between Pwell and PlusWell, and protects the gate oxide at the corner.

Description

technical field [0001] The invention relates to the technical field of preparation of trench type silicon carbide MOSFETs, in particular to a bottom protection ground trench type silicon carbide MOSFET and a preparation method thereof. Background technique [0002] Since the 1990s, the rapid development of silicon carbide (SiC) MOSFET technology has attracted extensive attention to this new generation of power devices. Compared with Si material, the higher thermal conductivity of SiC material determines its high current density, and the higher band gap determines the high breakdown field strength and high operating temperature of SiC devices. Especially in the development and application of SiC MOSFET, compared with Si MOSFET of the same power level, the on-resistance and switching loss of SiC MOSFET are greatly reduced, which is suitable for higher operating frequencies. sex. However, the price of SiC MOSFET is quite expensive, which limits its wide application. [0003]...

AI Technical Summary

Problems solved by technology

[0005] In view of this, it is necessary to provide a bottom-protected grounded trench silicon carbide MOSFET and its preparation method, which can solve the problem of product performance degradation or even damage due to insufficient grounding of the bottom of the trench silicon carbide MOSFET in the prior art. question

Images