带有肖特基漏极和场板结构的反向阻断垂直MOSFET研究

Study on Vertical MOSFET with Schottky-Drain and Field-Plate for Reverse Blocking

提出了一种采用肖特基漏极(SD)与场板相结合、实现硅基垂直MOSFET器件反向阻断应用的技术。基于该技术,采用二维仿真提出并研究了两种新型垂直MOSFET器件,即带有垂直场板(VFP)的SD-VFP-MOS器件和带有倾斜场板(SFP)的SD-SFP-MOS器件。相比采用肖特基漏极的MOSFET(SD-MOS)和采用超结和肖特基漏极的MOSFET(SD-SJ-MOS),所提出的SD-VFP-MOS,尤其是SD-SFP-MOS,反向击穿电压有显著提高,且几乎不影响导通特性。开展了器件的开态电流密度、关态电势分布、关态电流密度和电场分布分析,揭示了VFP和SFP提高器件反向阻断能力的内在机理。详细讨论了场板结构参数对器件反向击穿电压和场板效率的影响,研究结果对于SD-VFP-MOS和SD-SFP-MOS的设计具有重要意义。

A technology of the Schottky-drain(SD)combined with the field-plated structure is proposed to realize the reverse blocking applications in Si-based vertical MOSFETs.Based on this technology,two novel vertical MOSFETs,SD-VFP-MOS with a vertical field-plate(VFP)as well as SD-SFP-MOS with a slant field-plate(SFP),are proposed and investigated by two-dimensional simulations.Compared with the MOSFET with a SD(SD-MOS)and the MOSFET with a superjunction(SJ)as well as a SD(SD-SJ-MOS),the proposed SD-VFP-MOS,especially SD-SFP-MOS,exhibits a remarkable improvement of reverse breakdown voltage and nearly none influence on the on-state characteristics.Analyses associated with the distributions of the on-state current density,off-state potential,off-state current density and electric field for all the devices are performed,which reveals the inherent mechanism of the VFP and the SFP to improve the reverse blocking ability.Detailed discussions of the dependence of the reverse breakdown voltage and the field-plate efficiency on the parameters of the field-plated structures are conducted,which could be of great value to the design of SD-VFP-MOS and SD-SFP-MOS.