L-type base region SiC MOSFET cellular structure, device and manufacturing method

Abstract

The invention discloses an L-type base region SiC MOSFET cellular structure, a device and a manufacturing method. The L-type base region SiC MOSFET cellular structure comprises an N++ SiC substrate, an N- SiC drift layer, a P-type base region and an N+ source region. The N- SiC drift layer is located above the N++ SiC substrate, a source trench and a gate trench are formed in the N- SiC drift layer, and a gate dielectric layer and a gate electrode are arranged in the gate trench. The P-type base region and the N+ source region are positioned on the N- SiC drift layer between the source trench and the gate trench and are arranged from bottom to top, an N-type current conducting layer is arranged between the P-type base region and the N- SiC drift layer, and a source N+ ohmic contact region is arranged between the P-type base region and the source trench. According to the device structure, the on resistance and the gate-drain capacitance can be further reduced, the conduction loss and the switching loss can be reduced, the working frequency can be improved, the premature breakdown of the P-type base region can be avoided, and the reliability of the device can be ensured.

Description

technical field [0001] The invention relates to the technical field of transistor electronic device preparation, in particular to a SiC MOSFET cell structure, a device and a manufacturing method thereof. Background technique [0002] Silicon carbide (SiC) is a third-generation semiconductor material. The band gap is three times that of silicon (Si), the first-generation semiconductor material, the critical breakdown electric field strength is ten times that of Si, and the electron saturation drift rate is Si 2 times that of Si, and the thermal conductivity is 3 times that of Si, which makes SiC power semiconductor devices, especially SiC MOSFETs, have significant performance advantages such as high temperature, high voltage, high frequency, and high efficiency, and have broad application prospects in power electronic systems. [0003] A key challenge for SiC MOSFETs is in SiC / SiO 2 There are interface states and the scattering effect of trapped charges on electrons at the i...

AI Technical Summary

Problems solved by technology

However, the traditional L-shaped base trench SiC MOSFET structure will add a section of lateral channel and compress the width of the current path, resulting in an increase in on-resistance, and knee voltage may appear in the output characteristic curve

At the same time, the P-type base region cannot cover the middle of the bottom of the gate trench, where the electric field concentration effect is still serious, and the gate-to-drain capacitance is high, which limits the improvement of operating frequency and system efficiency

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