一种能够改善鲁棒性的新型4H-SiC ESD防护器件

A novel 4H-SiC ESD protection device with improved robustness

2020年,韩国学者以4H-SiC材料为基底提出了一种新型ESD防护器件HHFGNMOS(high holding voltage floating gate NMOSFET),此结构显著改善了4H-SiC GGNMOS(grounded-gate NMOSFET)因SiC材料特性导致的剧烈回滞现象.但是在HHFGNMOS结构中仍存在电流分布过于密集的问题.在本文中首次将comb-like结构用于HHFGNMOS防护器件,将器件的漏区底部进行梳型改造,充分利用电流集边效应使电流分布变得均匀,并通过TCAD仿真给出了Comb-like结构的设计变量对结构性能的影响.基于4H-SiC的GGNMOS,HHFGNMOS,Comb-like HHFGNMOS在TLP脉冲下的瞬态仿真结果显示,comb-like HHFGNMOS的二次失效电流I相比GGNMOS以及HHFGNMOS由17 A提高到22 A,提高了29%;此外comb-like HHFGNMOS回滞相比GGNMOS及HHFGNMOS减小了55.2%和5%.因此在面积不变、工艺相兼容的情况下较大程度改善了器件的鲁棒性,减小了回滞效应.

In 2020,Korean scholars proposed a new elect rot at ic discharge(ESD) protection device HHFGNMOS(high holding voltage floating gate nMOSFET) based on 4 H-SiC material,which can significantly improve the severe snapback phenomenon of 4 H-SiC GGNMOS due to the characteristics of SiC material.However,there still exists a problem that the current distribution is too dense in the HHFGNMOS structure.In this work,the comb-like structure is used for the HHFGNMOS protection device for the first time.The bottom of the drain region of the device is comb transformed,and the current distribution is made uniform by making full use of the current edge effect.The influence of design variables of comb-like structure on structure performance is given by TCAD simulation.The transient simulation results of GGNMOS,HHFGNMOS and comb-like HHFGNMOS based on 4 H-SiC under TLP pulse show that the secondary failure current Iof comb-like HHFGNMOS increases from 17 to 22 A i.e.by 29%,compared with that of GGNMOS and HHFGNMOS.In addition,the comb-like HHFGNMOS snapback is reduced by 55.2% and 5% compared with GGNMOS snapback and HHFGNMOS snapback,respectively.Therefore,the robustness of the device is greatly improved and the snapback effect is reduced under the condition of constant area and compatible process.