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提升反向恢复性能的超结 4H-SiC沟槽 MOSFET结构

Super Junction 4H-SiC Trench MOSFET for Enhancing Reverse Recovery Performance

  • 摘要: 针对4H-SiC沟槽MOSFET在高压、高频应用中因传统沟槽MOSFET结构(CT-UMOS)pn结面积增大而影响反向恢复性能的问题,提出了一种新型超结4H-SiC沟槽MOSFET结构(NSJ-UMOS)。该结构在源极下方引入NSJ超结,通过高浓度n+、低浓度n1+及p1+区组成的SSJ结构优化体内和栅氧化层间的电场分布。通过TCAD仿真测试,验证了NSJ-UMOS在性能上的显著提升。仿真结果表明,NSJ-UMOS的反向恢复时间从1.01 μs缩短至0.02 μs,击穿电压提升至4 030 V,栅漏电容从33.6 pF减少至0.402 pF,比导通电阻从54.49 mΩ·cm2降至8.26 mΩ·cm2,开关功耗降低幅度高达39.51 %。以上改进大幅提升了器件的正向导通性能、反向恢复性能及第三象限表现,使其在高压、高可靠性和高频应用中更具优势。

     

    Abstract: In the report, aimed the problem that in the high-voltage and high-frequency applications, because of the increase of the pn junction area of the traditional trench MOSFET structures (CT-UMOS), 4H-SiC trench MOSFET structure affects the reverse recovery performance, a novel super junction 4H-SiC trench MOSFET structure (NSJ-UMOS) was designed. The structure introduced an NSJ super junction below the source, an SSJ structure composed of high concentration n+, low concentration n1+, and p1+regions was used to optimize the electric field distribution between the internal and gate oxide layers. TCAD simulation test was performed to verify the significant improvement of the performance of NSJ-UMOS. The results indicated that the reverse recovery time of NSJ-UMOS is shortened from 1.01 μs to 0.02 μs, the breakdown voltage is increased to 4030 V, the gate drain capacitance is reduced from 33.6 pF to 0.402 pF, the specific on resistance is reduced from 54.49 mΩ·cm2 to 8.26 mΩ·cm2, and the switching power consumption is reduced by 39.51%. The above improvements improved significantly the forward conduction performance, reverse recovery performance, and third quadrant performance of the device, which make it more advantageous in the high-voltage, high reliability, and high-frequency applications.

     

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