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

In 2020, Korean scholars proposed a new electrotatic discharge (ESD) protection device HHFGNMOS(high holding voltage floating gate nMOSFET) based on 4H-SiC material, which can significantly improve the severe snapback phenomenon of 4H-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 4H-SiC under TLP pulse show that the secondary failure current I_T2 of 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.