Effects of 5 MeV Proton Irradiation on 1200 V 4H-SiC VDMOSFETs ON-State Characteristics

Dongxun Li,Xiaoyan Tang,Qingwen Song,Yanjing He,Yimen Zhang,Yuming Zhang

doi:10.1109/access.2020.2999642

Abstract

The effects of 5 MeV proton irradiation on ON-state characteristics of 1200 V 4H-SiC VDMOSFETs are investigated in this paper, and related mechanisms have been revealed by the analysis of their test structure of ohmic contacts, lateral nMOSFETs and MOS capacitors simultaneously fabricated on same wafer. The results show that the threshold voltage (V TH ) decreases obviously with increasing irradiation doses because the dominant hole traps induced by nitrogen passivation might capture more holes produced by the ionization effect of proton irradiation, resulting in the generation of net positive charges nearby the SiO 2 /4H-SiC interface. The interface trap density (Dit) extracted by subthreshold swing increases but field effective mobility (μ FE ) is improved with increasing irradiation doses. The un-trapped near interface electron traps (NIETs) are reduced by the ionization effect of proton irradiation, which could be beneficial to the improvement of μ FE . And after the maximum irradiation dose of 1 × 10 14 p/cm 2 the VDMOSFET fails in the ON-state capability. Before it fails, the ON-state resistivity (R ON ) firstly decreases and then increases with the increase of irradiation dose. The deterioration of the resistance of lightly doped drift region (R D ) and the resistance of JFET region (R JFET ) caused by the displacement effect of proton irradiation covers up the improvement of the channel resistance (R CH ) with increasing irradiation doses, finally leading to the failure of the VDMOSFET at the maximum proton irradiation dose.

Highlights

Silicon Carbide (SiC) is an attractive wide-bandgap semiconductor material in the rapidly increased demands of the power, high temperature and space electronic fields due to its excellent electrical and thermal properties [1], [2]
The effects of 5 MeV proton irradiation on ON-state characteristics of 1200 V 4H-SiC VDMOSFETs are investigated in this paper, in which the VDMOSFETs were fabricated with their test structure of ohmic contacts, lateral nMOSFETs and MOS capacitors simultaneously on same wafer
The results show that the threshold voltage (VTH) decreases obviously with increasing irradiation doses because the dominant hole traps induced by nitrogen passivation might capture more holes produced by the ionization effect of proton irradiation, resulting in the generation of net positive charges nearby the SiO2/4H-SiC interface

Summary

INTRODUCTION

Silicon Carbide (SiC) is an attractive wide-bandgap semiconductor material in the rapidly increased demands of the power, high temperature and space electronic fields due to its excellent electrical and thermal properties [1], [2]. D. Li et al.: Effects of 5 MeV Proton Irradiation on 1200 V 4H-SiC VDMOSFETs ON-State Characteristics the devices such as the ohmic contact, the channel, the JFET region and the low doped drift region cannot be differentiated in detail. Li et al.: Effects of 5 MeV Proton Irradiation on 1200 V 4H-SiC VDMOSFETs ON-State Characteristics the devices such as the ohmic contact, the channel, the JFET region and the low doped drift region cannot be differentiated in detail Proton irradiation has both the ionization effect and displacement effect.

HIGH ENERGY PROTON IRRADIATION

RESULT

CONCLUSION