SiC-based groove-type field effect transistor and preparation method thereof

Abstract

The invention discloses a preparation method of a bottom n-type doped SiC-based UMOSFET with a p-type buried layer and a groove. The method is characterized in that the p-type buried layer (4) is formed through epitaxial growth on an n- drift layer (3); an n- drift layer (30) is formed through epitaxial growth on the p-type buried layer (4); a p-type base region layer (5) is formed through epitaxial growth on the n- drift layer (30); and an n-type doped layer (900) is formed at the bottom of a main groove (7). The electric field of a gate oxide layer (10) is effectively reduced in a reverse blocking state. Due to the shielding effects of the p-type buried layer (4) and the n-type doped layer (900), the thickness of the p-type base region layer (5) is greatly reduced, the groove is reduced to below 0.5[mu]m and the on-state performance is improved. The SiC-based UMOSFET has a relatively high Baliga optimum value and a relatively low switching loss. The invention further provides a structure of the SiC-based UMOSFET.

Description

technical field [0001] The invention relates to a method for preparing a SiC-based trench field effect transistor (MOSFET), in particular to a method for manufacturing a SiC-based UMOSFET with a p-type buried layer and n-type doping at the bottom of the trench. Background technique [0002] SiC has superior physical and electrical properties, such as high critical breakdown electric field, wide band gap, and high electron saturation drift velocity, so it is very suitable for high-voltage, high-temperature power electronics. Vertical MOS field effect transistors include double injection type (DMOSFET) and trench type (UMOSFET), and 4H-SiC-based trench MOSFETs can theoretically have lower on-resistance and larger due to the lack of JFET resistance. Channel density, so it has a wider application prospect. [0003] However, on the one hand, the high gate-oxygen interface state density of SiC-based MOS devices leads to low channel mobility, which has always restricted the improv...

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Problems solved by technology

[0003] However, on the one hand, the high gate-oxygen interface state density of SiC-based MOS devices leads to low channel mobility, which has always restricted the improvement of the on-state performance of MOSFET devices; on the other hand, under high reverse voltage, the trench oxidation The electric field in the object is too large, especially the two-dimensional electric field accumulation at the corner of the bottom groove, which causes device breakdown in advance, which is not conducive to the improvement of the breakdown voltage; although a series of measures are taken, such as injecting a p-type shielding layer at the bottom of the groove to protect the electric field of the oxide layer , but the JFET resistance brought by it is not conducive to the improvement of the on-state characteristics of 4H-SiC-based trench MOSFET (UMOSFET)

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