Heavy-ion Radiation Strikes on LDD Implanted RingFET using 3D Numerical Device Simulations

IMPACT OF RADIATION ON LDD IMPLANTED RINGFET

Abstract

A ringFET is formed on vertically revolving bulk MOSFET with concentrical cylinders acting as the source, gate, and drain areas. By integrating lightly doped regions into conventional ringFET structures, three distinct types of LDD implanted ringFETs can be designed, with the implantation location defining each type. If LDD is implanted merely on the source side, it creates an SLDD ringFET, and if LDD is implanted only on the drain side, it results in a DLDD ringFET. Lastly, upon implanting LDD on both the drain and source sides, it forms an LDD ringFET structure. The effects of heavy ion radiation on three different types of LDD ringFET structures are assessed using 3D TCAD simulations and compared to the effects on a conventional ringFET structure under normal incidence. The ion strike's position, angle of incidence, and the resulting transient current and charge collected all affect the device's sensitivity and can be used to identify its vulnerable area. It has been found that the ringFET structure with LDD implanted on both the source and drain sides is more resilient to radiation-induced damage, as it exhibits a lower collected charge of 98.271 fC compared to conventional ringFET (106.768 fC), SLDD ringFET (101.549 fC), and DLDD ringFET (100.468 fC) for a LET value of 100 MeV/(mg/cm²). Additionally, the LDD-implanted ringFET exhibits a superior I_ON/I_OFF ratio compared to the other two LDD structures and conventional ringFET structures.