Effect of Radiation on Interface Traps of SOI NMOSFETs by the Direct-Current Current-Voltage Technique

Yangyang Li,Duoli Li,Chuanbin Zeng,Linchun Gao,Zhengsheng Han,Fangfang Wang,Weiwei Yan,Jiajun Luo,Bo Li,Xiaojing Li

doi:10.1109/access.2019.2935532

Abstract

This paper investigates the effect of total ionizing dose radiation on back-gate interface traps in SOI NMOSFETs. The concentration and energy distribution of interface traps at Si/SiO 2 back-gate interface of SOI NMOSFETs during irradiation are studied by the direct-current current-voltage technique. When transistors are subjected to radiation, DCIV bulk current increases. The calculated results suggest that the interface trap density increases and its equivalent energy level is far away from the midgap with irradiation dose increasing, which can be explained by the energy distribution of interface traps. The interface trap energy density D IT (E IT ) as a function of the energy level E IT has been obtained by the least square optimization and shows the typical “U-shape”distribution. In detail, the rising humps at equivalent energy level in D IT (E IT ) curves are due to Si-H bonds that are broken down after irradiation, which corresponds to the increasing trap density. Moreover, it is found that the energy level of interface traps is redistributed after irradiation. The peak of humps in D IT (E IT ) curves occurs at the farther energy level with the increase of dose, which is similar to the equivalent energy level. It might arise from the shallow energy level of interface traps induced by radiation.

Highlights

Silicon on insulator (SOI) technology is a promising candidate for aerospace applications compared to the bulk technology due to the excellent single event effect (SEE) tolerance
This reveals that the voltage drops across the body-to-drain and body-to-source PN junctions could enhance the concentration of electrons injected into the body, which impacts the trapping efficiency of interface traps to electrons and holes at the interface of Si-film/buried oxide
The radiation characteristics of interface traps at Si/SiO2 back-gate interface of SOI NMOSFETs are studied by DCIV approach

Summary

Introduction

Silicon on insulator (SOI) technology is a promising candidate for aerospace applications compared to the bulk technology due to the excellent single event effect (SEE) tolerance. Zhang et al [26] have estimated radiation-induced interface trap density (Nit ) from the charge pumping data but the energy level distribution of interface traps in his work is not involved.

Results

Conclusion