【作者】 王栋；

【导师】 宋庆文； 乐立鹏；

【作者基本信息】 西安电子科技大学 ， 工程硕士（专业学位）， 2020， 硕士

【摘要】 与Ge、Si等传统半导体材料相比较,第三代半导体材料(SiC)具有优异的材料性能:禁带宽度大、击穿电场高、热导率大和饱和电子漂移速度高等特点。是制造耐高温、抗辐照、大功率等恶劣环境下电力电子器件最理想的材料。混合PiN肖特基(MPS)二极管,具有开启电压小、导通电流大、开关速度快、反向漏电流小、击穿电压高的特点,是最为理想的一种功率二极管。兼具SBD二极管良好的正向特性、开关特性和PiN二极管优异的击穿特性。SiC卓越的材料特性,加之MPS二极管优异的结构优势,使得SiC MPS二极管成为最有发展潜力的一类功率二极管。本文首先使用TCAD对MPS二极管内部的PN结与肖特基结的能带进行分析,揭示了 MPS二极管中PN结开启电压较单独的PiN二极管大背后的物理机理。接着研究了 MPS二极管结构参数对双极导通电压的影响,给出了计算MPS二极管双极导通电压的解析模型,经验证该模型的计算结果与仿真结果基本一致。下一步分析了结构参数对平面MPS二极管正向导通特性和击穿特性的影响。最后分析了 MPS二极管的浪涌过程,并研究了结构参数对浪涌特性的影响。对于传统沟槽结构MPS二极管,使用仿真研究了沟槽深度对器件正向导通和反向阻断特性影响。通过改变沟槽结构势垒高度和肖特基宽度,与平面结构比较正向特性和击穿特性,证明了沟槽结构的优势。而且沟槽结构的浪涌特性更优越,在沟槽深度为1.5 μm,相比于平面结构,最高结温降低了 12%,双极导通电压降低了 20%。为了改善传统沟槽的正向导通特性,提出了一种新型氧化物沟槽MPS二极管结构(TOMPS),相比于传统沟槽结构在反特性退化不严重的情况下,显著改善其正向特性。因为存在电荷共享的原因,在相同导通电阻下,TOMPS结构相比于平面结构原胞大小降低了 1 0%;而且双极导通电压比传统沟槽结构降低了 2.3%。最后分析了结构参数对TOMPS二极管结构特性的影响。更多还原

【Abstract】 Compared with Ge,Si and other traditional semiconductor materials,the third generation semiconductor materials(SiC)have excellent material properties:wide band gap、high breakdown electric field、high thermal conductivity and high saturated electron drift speed.It is the most ideal material for the manufacture of power electronic devices in high temperature、irradiation、high power and other harsh environments.The merged pin Schottky(MPS)diode is the most ideal power diode with the characteristics of small opening voltage、large on current、fast switching speed、small reverse leakage current and high breakdown voltage.It combines the good forward characteristic、switching characteristic of SBD diodes and excellent breakdown characteristic of PiN diode’s.The excellent material properties of SiC and the excellent structure advantages of MPS diode make SiC MPS diode the most potential power diode.In this thesis,we first use TCAD to analyze the internal energy band of MPS diode,and reveal the physical mechanism behind the larger opening voltage of PN junction in MPS diode than that of PiN diode.Then,the influence of the structure parameters of MPS diode on the bipolar conduction voltage is studied,and a simple analytical model is given.The calculation results of the model are basically consistent with the simulation results.The next step is to analyze the influence of structure parameters on the forward conduction and breakdown characteristics of planar MPS diodes.Finally,the surge process of MPS diode is analyzed,and the influence of structure parameters on surge characteristics is studied.For the traditional groove structure MPS diode,the influence of groove depth on the forward and reverse blocking characteristics of the device is studied by simulation.By changing the barrier height and Schottky width of the groove structure,the forward and breakdown characteristics are compared with the plane structure,which proves the advantages of the groove structure.Moreover,the surge characteristics of the groove structure are more superior.At the groove depth of 1.5μm,compared with the plane structure,the maximum junction temperature is reduced by 12%,and the bipolar conduction voltage is reduced by 20%In order to improve the forward conduction characteristics of the trench,a new type of oxide trench MPS diode structure(TOMPS)is proposed.Compared with the traditional trench structure,it can significantly improve the forward characteristics when the reverse degradation is not serious.Because of charge sharing,under the same on-resistance,the cell size is reduced by 10%compared with the plane structure,and the bipolar on voltage is reduced by 2.3%compared with the traditional groove structure.Finally,the influence of structure parameters on the structure characteristics of TOMPS diode is studied.更多还原