Cell structure, device and manufacturing method of L-type base sic MOSFET

Abstract

The invention discloses an L-type base SiC MOSFET cell structure, a device and a manufacturing method thereof, including N ++ type SiC substrate, N ‑ type SiC drift layer, P type base region and N + type source region, N ‑ type SiC drift layer located on the N ++ type SiC substrate, which has a source trench and a gate trench, and a gate dielectric layer and a gate electrode in the gate trench; the P-type base region and the N + type source region located between the source trench and the gate trench in the N ‑ Type SiC drift layer, and arranged from bottom to top, in the P-type base and N ‑ There is an N-type current conduction layer between the SiC-type drift layer, and a source N-type layer between the P-type base region and the source trench. + type ohmic contact area. The device structure of the present invention can further reduce on-resistance and gate-drain capacitance, is beneficial to reducing conduction loss and switching loss, improves operating frequency, and can avoid premature breakdown of the P-type base region to ensure device reliability.

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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