温度对SRAM器件单粒子翻转重离子测试的影响

本文基于单粒子效应地面重离子模拟实验,选取体硅SRAM与SOI SRAM两种待测器件,在兰州重离子加速器上（HIRLF）研究了温度对单粒子翻转测试的影响。用12C粒子对体硅SRAM器件的温度实验显示,单粒子翻转截面易受温度的影响。对于SOI SRAM器件,12C粒子测得的单粒子翻转截面随温度升高有显著的增大,但209Bi 粒子测得的单粒子翻转截面却随温度保持恒定。用Monte Carlo的方法分析了温度对单粒子翻转测试的影响规律,发现在单粒子翻转阈值LET附近温度对单粒子翻转截面有大的影响,但是随着单粒子翻转的发生接近于饱和,单粒子翻转截面渐渐的表现出低的温度依赖性。基于该模拟结果,我们对实验数据进行了分析,同时提出了一种准确评估在轨翻转率的合理方法。     

北京正负电子对撞机次级束质子单粒子翻转计算和试验研究

北京正负电子对撞机(BEPC)电子直线加速器试验束打靶产生的次级束中包含质子,其中能量约为50MeV~100MeV的质子占有很大比例,这弥补了国内高能质子源的空白。本工作计算得到次级束中的质子能谱,建立质子单粒子翻转截面计算方法,在北京正负电子对撞机次级束质子辐射环境中,计算静态随机存取存储器的质子单粒子翻转截面,设计了SRAM质子单粒子翻转截面测试试验,发现SRAM单粒子翻转和注量有良好的线性,这是SRAM发生单粒子翻转的证据。统计得到不同特征尺寸下SRAM单粒子翻转截面,试验数据与计算结果相符,计算和试验结果表明随着器件特征尺寸的减小器件位单粒子翻转截面减小,但器件容量的增大,翻转截面依然增大,BEPC次级束中的质子束可以开展中高能质子单粒子效应测试。     

质子引入的6T SRAM单粒子翻转截面预测模型

提出了一种基于SOI工艺6T SRAM单元质子辐射的单粒子饱和翻转截面的预测模型,该模型通过器件物理来模拟辐照效应,利用版图和工艺参数来预测质子引入的单粒子饱和翻转截面。该模型采用重离子的SPICE测试程序对质子辐射的翻转截面进行预测,该方法简单高效,测试实例表明在0.15μm SOI工艺下,预测的质子引入的单粒子翻转饱和截面和实际测试的翻转截面一致。     

一种多模式SRAM单粒子试验系统的设计与实现

提出了一种基于NIOS II的异步SRAM单粒子效应检测系统,用于评估抗辐射加固SRAM电路的抗单粒子效应能力.该检测系统可以对异步SRAM进行四种工作模式下的动态和静态检测,利用该检测系统在重离子加速器上对一款异步SRAM进行了单粒子效应试验,获得了5种离子的试验数据,统计分析后得到了器件的单粒子翻转阈值、单粒子翻转饱和截面和单粒子翻转在轨错误率,并与国外同款电路进行了对比,最后依据试验结果给出了评估结论.     

基于激光背部辐照方法的小尺寸器件的单粒子效应特性

本文基于脉冲激光背部辐照试验方法,测试了小尺寸器件的单粒子翻转与闩锁特性,以克服高集成度器件日益增加的金属布线层对激光试验的影响。研究了SRAM器件存储的数据类型对器件单粒子翻转阈值与截面的影响特性。试验测试了深亚微米器件微闩锁效应的电流变化特征。建立了一种激光能量与重离子LET值对应关系的经验公式,用于评估小尺寸器件的等效激光LET值。此外,利用激光背部辐照试验方法,初步试验研究了90nmSOI工艺PowerPC微处理器的单粒子翻转特性。     

基于Geant4的三维半导体器件单粒子效应仿真

在空间中,辐射粒子入射半导体器件,会在器件中淀积电荷.这些电荷被器件的敏感区域收集,造成存储器件(如静态随机存储器(SRAM))逻辑状态发生变化,产生单粒子翻转(SEU)效应.蒙特卡洛工具-Geant4能够针对上述物理过程进行计算机数值模拟,可以用于抗辐射器件的性能评估与优化.几何描述标示语言(GDML)能够在Geant4环境下对器件模型进行描述.通过使用GDML建立三维的器件结构模型,并使用Geant4进行不同能量质子入射三维器件模型的仿真.实验结果表明,在三维器件仿真中低能质子要比高能质子更容易引起器件的单粒子翻转效应.     

基于三维模型的InGaP/GaAs HBT单粒子效应仿真

为全面评估航天型号用元器件的抗辐射性能,对InGaP/GaAs异质结双极晶体管(Heterojunction Bipolar Transistor,HBT)的单粒子效应进行了仿真研究。首先,介绍了空间辐射环境中重离子诱发器件产生单粒子瞬态脉冲的机理。然后,建立了InGaP/GaAs HBT器件三维仿真模型,并利用蒙特卡罗方法模拟了不同能量的C、F、Cl、Br、I等重离子在器件中的射程和LET值。最后,基于ISE-TCAD仿真软件对器件的单粒子瞬态脉冲电流曲线进行了仿真和分析。结果表明:重离子在器件中产生的集电极瞬态脉冲电流可达几百微安,集电极瞬态脉冲电流与重离子的能量成反比,与离子的原子序数成正比。由此可知,InGaP/GaAs HBT器件对单粒子效应比较敏感,且对不同重离子的敏感程度不同。这可以为航天型号用元器件的设计选型和可靠性评估提供技术支撑。     

基于PDSOI单粒子翻转物理机制的SPICE模型研究

通过研究半导体器件单粒子翻转的物理机制,利用Synopsys TCAD工具对基于中国科学院微电子所开发的0.35μm部分耗尽SOI器件进行单粒子翻转的模拟,讨论了器件模拟物理模型的选择,验证了理论分析的正确性,并对重离子撞击引起的瞬态电流过程进行分析.分析表明单粒子翻转存在两个放电阶段,第一阶段过量电子漂移扩散电流组成激增电流部分;第二阶段部分耗尽SOI器件寄生三极管放电机制以及过量空穴放电机制引起的缓慢电流放电＂尾部＂.结合激增电流的物理意义,提出合理的数学模型,推导出描述此电流的一维解析解;对于缓慢衰减的＂尾部＂电流,提出子电路模型,并基于SPICE三极管模型进行参数提取,着重讨论了单粒子翻转的敏感参数.最后给出了以反相器为例的SPICE模拟与TCAD模拟在瞬态电流,输出节点电荷收集,LET阈值的对比结果,验证了SPICE模型的合理性和精确性.     

沟槽型VDMOS的重离子辐射失效研究

空间辐射环境中含有各种高能带电粒子,高能带电粒子与电子器件相互作用可能引发单粒子效应（SEE）,单粒子效应中单粒子烧毁（SEB）和单粒子栅穿（SEGR）是两种最主要的单粒子事件。对重离子环境下的器件退化和失效进行了研究,分析了重离子环境下的失效机理,提出了重离子条件下的器件改善结构,同时完成了仿真和重离子实验验证,提升了MOSFET抗重离子能力。     

倒装SRAM型FPGA单粒子效应防护设计验证

在倒装芯片的单粒子效应防护设计验证中,重离子在到达器件敏感区前要经过几百微米的衬底材料,需要计算器件敏感区中离子的线性能量传输(LET)值。采用兰州重离子加速器加速的55 MeV/μ58Ni离子对基于倒装的Xilinx公司550万门现场可编程门阵列(FPGA)实现的典型系统的单粒子效应防护设计进行了试验验证,采用SRIM、FLUKA和GEANT等不同方法对试验中的LET值进行了分析,同时将SRIM分析的典型结果与基于磁偏转飞行时间法的试验数据进行了比较,发现与现有的重离子分析结果有一定差异。因此在防护验证中采用离子LET作为主要参数的情况下,应对重离子(尤其是高能段)的LET的计算方法进行约定,以规范试验过程,增强数据的可比性。     

Predictions for proton and heavy ions induced SEUs in 65 nm SRAMs

We report on irradiation induced single event upset (SEU) by high-energy protons and heavy ions. The experiments were performed at the Paul Scherer Institute, and heavy ions at the SEE irradiating Facility on the HI-13 Tandem Accelerator in China's Institute of Atomic Energy, Beijing and the Heavy Ion Research Facility in Lanzhou in the Institute of Modern Physics, Chinese Academy of Sciences. The results of proton and heavy ions induced (SEU) in 65 nm bulk silicon CMOS SRAMS are discussed and the prediction on several typical orbits are presented.     

One-Parameter Model for the Estimation of IC Susceptibility to Proton-Induced Single-Event Upsets

Singe-event upsets (SEUs) caused by high-energy protons are considered. An analytical model is proposed to represent the dependence of SEU cross section on proton energy. The model is based on a simple mechanism of proton-induced nuclear reactions in silicon. A computer simulation is conducted by the model. The results are found to agree with previous experiments. They indicate that the model enables one to predict susceptibility to proton-induced SEUs on the basis of a single value of SEU cross section measured at a proton energy higher than 100 MeV. It is shown that the approach may also work for heavy ions.     

Experimental research of heavy ion and proton induced single event effects for a Bi-CMOS technology DC/DC converter

This paper tested and analyzed heavy ion and proton induced single event effects (SEE) of a commercial DC/DC converter based on a 600 nm Bi-CMOS technology. Heavy ion induced single event transients (SET) testing has been carried out by using the Beijing HI-13 tandem accelerator at China Institute of Atomic Energy. Proton test has been carried out by using the Canadian TRIUMF proton accelerator. Both SET cross section versus linear energy transfer (LET) and proton energy has been measured. The main study conclusions are: (1) the DC/DC is both sensitive to heavy ion and proton radiations although at a pretty large feature size (600 nm), and threshold LET is about 0.06 MeV·mg/cm²; (2) heavy ion SET saturation cross section is about 5 magnitudes order larger than proton SET saturation cross section, which is consistent with the theory calculation result deduced by the RPP model and the proton nuclear reaction model; (3) on-orbit soft error rate (SER) prediction showed, on GEO orbit, proton induced SERs calculated by the heavy ion derived model are 4-5 times larger than those calculated by proton test data.     

Single Event Upset rate determination for 65 nm SRAM bit-cell in LEO radiation environments

The degradation of SRAM bit-cells designed in a 65 nm bulk CMOS technology in a Sun-Synchronous Low Earth Orbit (LEO) ionizing radiation environment is analyzed. We propose an inflight SEU rate estimation approach based on a modeled heavy ion cross section as opposed to the standard experimental characterization. Effects of irradiation with estimated LET spectrum in SRAM bit cell, i.e. the location of sensitive regions, its tendency to cause upset, magnitude and duration of transient current as well as voltage pulses were determined. It was found with SEU map that 65 nm SRAM bit-cell can flip even if high LET particle strikes in close proximity of bit-cell outside the SRAM bit-cell area. The SEU sensitive parameters required to predict SEU rate of on-board target device, i.e., 65 nm SRAM were calculated with typical aluminum spot shielding using fully physical mechanism simulation. In order to characterize the robustness of scaled CMOS devices, state of the art simulation tools such as Visual TCAD/Genius, GSEAT/Visual Particle, runSEU, were utilized whereas LEO radiation environment assessment, upset rate prediction was accomplished with the help of OMERE-TRAD software.     

SRAM single event upset calculation and test using protons in the secondary beam in the BEPC

The protons in the secondary beam in the Beijing Electron Positron Collider(BEPC) are first analyzed and a large proportion at the energy of 50-100 MeV supply a source gap of high energy protons.In this study, the proton energy spectrum of the secondary beam was obtained and a model for calculating the proton single event upset(SEU) cross section of a static random access memory(SRAM) cell has been presented in the BEPC secondary beam proton radiation environment.The proton SEU cross section for different characteristic dimensions has been calculated.The test of SRAM SEU cross sections has been designed,and a good linear relation between SEUs in SRAM and the fluence was found,which is evidence that an SEU has taken place in the SRAM.The SEU cross sections were measured in SRAM with different dimensions.The test result shows that the SEU cross section per bit will decrease with the decrease of the characteristic dimensions of the device,while the total SEU cross section still increases upon the increase of device capacity.The test data accords with the calculation results,so the high-energy proton SEU test on the proton beam in the BEPC secondary beam could be conducted.     

Single-Event Transient Measurements on a DC/DC Pulse Width Modulator Using Heavy Ion,Proton, and Pulsed Laser

This paper discusses multiple methods of Single-Event Transient (SET) measurements on a commercial DC/DC Pulse Width Modulator (PWM). Heavy ion, proton, and pulsed laser are used in the experiments. The correlations between the heavy ion, pulsed laser and proton data are analyzed and presented. A proton cross-section model is used to derive proton cross-section from heavy ion test data. The calculated result is close to the real proton data, which means the heavy ion and proton data fit well. The relationship between pulsed laser and proton are also analyzed through heavy as a medium.     

The single-event effect evaluation technology for nano integrated circuits

Single-event effects of nano scale integrated circuits are investigated. Evaluation methods for single-event transients, single-event upsets, and single-event functional interrupts in nano circuits are summarized and classified in detail. The difficulties in SEE testing are discussed as well as the development direction of test technology, with emphasis placed on the experimental evaluation of a nano circuit under heavy ion, proton, and laser irradiation. The conclusions in this paper are based on many years of testing at accelerator facilities and our present understanding of the mechanisms for SEEs, which have been well verified experimentally.     

Electronically controlled pH gradients and proton oscillations

An organic electronic ion pump, including poly(3,4-ethylenedioxythiophene) as the active material has been used to electronically control the transport of protons between two electrolytes and to change the pH of the target solution from 7 to 3 in a few minutes. The number of transported protons equals the time-integrated current between the two addressing electrodes. If no voltage is applied the leakage due to diffusion is not detectable, which indicates an overall proton delivery on/off ratio exceeding 1000. Locally, the pH drop can be even larger and the relationship between the proton delivery rate of the pump and proton diffusion in the electrolyte forms pH gradients. If the device is instead addressed with short pulses, local pH oscillations are created. The transport of protons presented here can be extended to other small sized ions, which in combination with the biocompatibility of the delivery surface make the device promising for cell communication studies and lab-on-a-chip applications.     

卫星光通信系统中单粒子翻转计算方法研究

高能带电粒子造成的单粒子翻转是影响卫星光通信系统性能的重要因素,给出了单粒子翻转的物理机制及主要研究方法。利用OMERE 3.4软件对星载CMOS 2164器件进行了单粒子翻转率计算,结果表明,通过对轨道倾角和轨道高度的优化设计可以有效减小卫星光通信系统中电子器件的单粒子翻转率。为了有效克服单粒子辐射效应,除了简单的增加屏蔽层厚度等防护方法外,还应考虑通过电子器件的选择来提高抗辐射性能。