Double-groove silicon carbide MOSFET structure and manufacturing method

Abstract

The invention discloses a double-groove silicon carbide MOSFET structure and a manufacturing method. The structure is formed by arranging a plurality of cells, wherein each cell is provided with a substrate and a drift layer; each drift layer is provided with a gate trench and a source trench, an N-type hole barrier layer and a P+ type shielding layer are arranged around the source trench, and source metal is formed in the source trench; a P- type base region is formed at the tops of each drift layer and each N-type hole blocking layer, N+ type source regions are formed at the tops of the P- type base regions and the P+ type shielding layers, and ohmic contact metal layers are arranged between the N+ type source regions and source electrode metal; gate thermal oxidation dielectric layers are formed on the bottom surfaces, the inner side surfaces and the like of the gate trenchs, the gate thermal oxidation dielectric layers are cavity-shaped, and gate precipitation dielectric layers and gate electrodes are formed in the cavities; and interlayer mediums are arranged between the gate electrodes and the source electrode metal. According to the above structure, the reliability of a gate dielectric layer of the device can be improved, and on-resistance is reduced, so on-static loss is reduced, gate-drain capacitance and gate charge are reduced, and the dynamic loss of a switch is reduced.

Description

technical field [0001] The invention relates to the field of semiconductors, in particular to a double-groove silicon carbide MOSFET structure and a manufacturing method. Background technique [0002] Silicon carbide is a third-generation semiconductor material. Compared with the first-generation semiconductor material silicon, it has a larger band gap, a larger critical breakdown field strength, a faster electron saturation drift speed, and a higher heat dissipation. Conductivity. Therefore, silicon carbide power semiconductor devices, especially silicon carbide MOSFETs, can work better under high temperature, high pressure, and high frequency conditions, significantly improving the energy efficiency of power electronic systems, improving system heat dissipation, and reducing system volume. [0003] A key challenge for SiC MOSFETs is the existence of interface states at the SiC / SiO2 interface and the scattering effect of trapped charges on electrons, resulting in lower cha...

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Problems solved by technology

These two methods can achieve the transfer of the peak position of the field intensity, but both will compress the path width of the current flowing from the channel to the drift layer, resulting in an increase in the on-resistance

The double-trench silicon carbide MOSFET structure proposed by Rohm can achieve a good compromise between the critical breakdown voltage and on-resistance, but the electric field concentration effect at the middle of the bottom of the gate trench is still serious, and the gate-drain capacitance Higher, which limits the improvement of operating frequency and system efficiency

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