超薄屏蔽层300 V SOI LDMOS抗电离辐射总剂量仿真研究

Simulation study on radiation hardness for total ionizing dose effect of ultra-thin shielding layer 300 V SOI LDMOS

本文研究了300 V绝缘体上硅横向双扩散金属氧化物半导体场效应管在电离辐射总剂量效应下的线性电流退化机理,提出了一种具有超薄屏蔽层的抗辐射结构实现线性电流加固.超薄屏蔽层位于器件场氧化层的下方,旨在阻止P型掺杂层表面发生反型,从而截断表面电流路径,有效抑制线性电流的退化.对于横向双扩散金属氧化物半导体场效应管,漂移区上的场氧化层中引入的空穴对线性电流的退化起着主导作用.本文基于器件工艺仿真软件,研究器件在辐照前后的电学特性,对超薄屏蔽层的长度、注入能量、横向间距进行优化,给出相应的剂量窗口,在电离辐射总剂量为0—500 krad(Si)的条件下,将最大线性电流增量从传统结构的447%缩减至10%以内,且辐照前后击穿电压均维持在300 V以上.

In this work,the linear current degradation mechanism of 300 V silicon-on-insulator laterally doublediffused metal-oxide-semiconductor field effect transistor under total ionizing effect is studied,and a method in radiation-hardness for linear current by introducing an ultra-thin shielding layer is proposed.This new structure is realized with P-type ultra-thin shielding layer implantation under field oxide,in order to prevent the P-type layer from complete surface inversion,thereby truncating the surface current route and mitigating the current degradation effectively.For a laterally double-diffused metal-oxide-semiconductor field effect transistor,linear current degradation can be attributed mainly to holes introduced in the field oxide.In this work,the influence of introduced holes on electrical properties in the transistor oxides under harsh environment is simulated based on device and process simulation software,with optimized layer length,implantation energy,lateral distance and dose window,and the goal of linear current hardness(linear current increment decreasing from 447% in conventional structure to less than 10% in proposed structure) is achieved while maintaining pre-rad and postrad breakdown voltages above 300 V under total dose of 0–500 krad(Si).