超深亚微米CMOS集成电路中子多比特翻转效应机理研究

Single event effects (SEE) observed during neutron irradiation of microelectronics are induced by ionizing nuclear recoils produced when energic neutrons interact with silicon nuclei. As the feature sizes decrease, with charge sharing and bipolar effect appearing , single event upsets(SEUs) and multiple event upsets (MBUs)induced by neutron are becoming a key challenge for integrated circuits working in space and nuclear explosion. Thus, some accurate approaches to estimate the neutron induced upset cross section are needed to address this challenge. Based upon the physics processes of SEE induced by neutron,firstly, monte-carlo method is adopted for analyzing effects of secondary partices induced by n+Si reaction. Secondly, the mechanism of MBU effect is studied including charge sharing effect and bipolar effect. Thirdly,a photocurrent source model with charge sharing effect and bipolar effect considered is developed for performing single event analysis quickly and efficiently,which calculates the effects of radiation in an efficient way, based on device physics. Lastly,a prediction model for upset cross section induced by secondary particles generated from neutron will be developed for sequentical cells. The goal of this project is to provide an efficient approach to evalute neutron-induced single event upset cross section for integrated circuits fabricated in submicron and nanometer process techonologies.

随着集成电路进入超深亚微米时代,由于工艺线宽的缩小、电荷共享效应和双极放大效应的出现,当集成电路工作于中子辐照环境时,中子入射不仅会造成单粒子翻转甚至还会导致多比特翻转，这就给中子引入的单粒子翻转效应的评估和预测带来很大挑战。在此形势下,中子引入的单粒子翻转效应的评估和预测成为该领域的主要研究课题之一。本研究课题将首先采用蒙特卡洛集成分析方法对核反应过程进行分析,并对中子入射产生的次级粒子的整体作用进行预测。其次,研究超深亚微米工艺下的多比特翻转机理并对电荷共享以及双极放大效应进行建模,在此基础上基于器件物理方程推导次级粒子的电流源注入模型。最后,针对中子引入的单粒子翻转截面建立一种两参数的预测模型,并针对不同工艺完成典型单元的中子单粒子翻转效应评估。本课题的研究成果主要为超深亚微米下的大规模集成电路的中子引入的单粒子翻转问题提供一种高效的分析评估方法。

随着工艺的进步，集成电路的器件特征尺寸减小、工作电压降低、敏感节点的关键电荷减小以及器件间的间距减小，CMOS器件变的异常敏感。在深亚微米工艺和超深亚微米工艺下，当有中子入射器件时，中子会与半导体器件反应产生次级粒子，所产生的次级粒子会在多个敏感节点同时产生电荷累积现象，从而导致产生中子多比特翻转效应（Multiple Bit Upset, MBU）。在此形势下，中子导致的多比特翻转效应成为该领域的主要研究课题之一。本课题旨在为深亚微米和超深亚微米下的中子的多比特翻转效应提供有效的评估方法。本课题首先研究了中子多比特翻转效应机理，并分析了中子与半导体材料反应的全过程。基于器件物理理论，本课题提出了面向次级粒子的电流源瞬态注入模型。其次，在此基础上，本课题基于GEANT4软件建立了新的复合敏感体模型，并对该模型进行了实验验证。然后，基于复合敏感体模型，本课题搭建了用于多比特翻转的多敏感体预测模型，对中子的单粒子效应进行预测，预测了20MeV能量以下中子辐射的单比特翻转和多比特翻转。试验结果与文献数据基本一致。最后，本课题研究了不同入射角度、不同截断值、不同阈值电荷和不同金属互联层材料情况下的中子翻转效应。本课题的技术可以用于指导相应的抗辐射加固技术。