总剂量辐射环境中的静态随机存储器功能失效模式研究

本文对静态随机存储器 (SRAM) 总剂量辐射引起的功能失效进行了六种不同测试图形下的测试. 利用不同测试图形覆盖的出错模式不同, 通过对比一定累积剂量下同一器件不同测试图形测试结果的差异, 以及对失效存储单元单独进行测试, 研究了总剂量辐照引起的SRAM器件功能失效模式. 研究表明: 器件的功能失效模式为数据保存错误 (Data retention fault) 且数据保存时间具有离散性, 引起数据保存错误的SRAM功能模块为存储单元. 通过对存储单元建立简化的等效电路图, 分析了造成存储单元数据保存错误以及保存时间离散性的原因, 并讨论了该失效模式对SRAM总剂量辐射功能测试方法的影响. 关键词： 静态随机存储器 功能失效 测试图形 数据保存错误     

部分耗尽绝缘层附着硅静态随机存储器总剂量辐射损伤效应的研究

通过分析部分耗尽绝缘层附着硅互补金属氧化物半导体静态随机存储器(SRAM)在动态偏置条件下的电学参数和功能参数随累积剂量的变化规律, 研究了绝缘层附着硅(SOI)工艺SRAM器件在⁶⁰Co-γ射线辐照后的总剂量辐射损伤效应及器件敏感参数与功能错误数之间的相关性,为进一步深入研究大规模SOI集成电路的抗总剂量辐射加固及其辐射损伤评估提供了可能的途径和方法.实验结果表明:辐射引起的场氧和埋氧漏电是功耗电流增大的主要原因; 阈值电压漂移造成输出高电平下降、低电平微小上升和峰-峰值大幅降低,以及传输延迟增大; 当总剂量累积到一定程度,逻辑功能因关断功能的失效而出现突变错误; 传输延迟和输出高电平与逻辑功能错误之间存在一定相关性.     

累积剂量影响静态随机存储器单粒子效应敏感性研究

本文利用60Coγ源和兰州重离子加速器,开展不同累积剂量下,静态随机存储器(static random access memory,SRAM)单粒子效应敏感性研究,获取不同累积剂量下SRAM器件单粒子效应敏感性的变化趋势,分析其辐照损伤机理.研究表明,随着累积剂量的增加,SRAM器件漏电流增大,影响存储单元低电平保持电压、高电平下降时间等参数,导致"反印记效应".研究结果为空间辐射环境中宇航器件的可靠性分析提供技术支持.     

静态随机访问存储器型现场可编程门阵列辐照效应测试系统研制

 在调研静态随机访问存储器型现场可编程门阵列(FPGA)器件空间辐照效应失效机理的基础上,详细论述FPGA辐照效应测试系统内部存储器测试、功能测试及功耗测试的实现原理,给出了系统的软硬件实现方法。所建立的系统可以测试FPGA器件的配置存储器翻转截面、块存储器翻转截面、功能失效截面、闭锁截面等多个参数,其长线传输距离达到50 m以上,最大可测门数达到了100万门,为FPGA辐照效应研究提供了测试平台。     

静态随机访问存储器型现场可编程门阵列辐照效应测试系统研制

在调研静态随机访问存储器型现场可编程门阵列(FPGA)器件空间辐照效应失效机理的基础上,详细论述FPGA辐照效应测试系统内部存储器测试、功能测试及功耗测试的实现原理,给出了系统的软硬件实现方法。所建立的系统可以测试FPGA器件的配置存储器翻转截面、块存储器翻转截面、功能失效截面、闭锁截面等多个参数,其长线传输距离达到50 m以上,最大可测门数达到了100万门,为FPGA辐照效应研究提供了测试平台。     

各向异性静态随机存储器中的多位翻转分析研究

重离子实验结果表明,具有高线性能量转移(LET)或大角度入射的快重离子导致静态随机存储器(SRAM)中的多位翻转(MBU)比例增大,甚至超过单位翻转比例。单个离子径迹中的电荷可以沿着径向扩散数个微米,被临近的灵敏区收集后引起MBU。器件灵敏区的各向异性空间布局与离子入射方向共同影响测试器件的MBU图形特征。位线接触点的纵向隔离导致横向型成为主要的两位翻转图形;"L"型和"田"型分别是主要的三位翻转和四位翻转图形。最后,对SRAM抗MBU加固设计和实验验证方法进行了讨论。     

纳米静态随机存储器低能质子单粒子翻转敏感性研究

针对65, 90, 250 nm三种不同特征尺寸的静态随机存储器基于国内和国外质子加速器试验平台, 获取了从低能到高能完整的质子单粒子翻转截面曲线. 试验结果表明, 对于纳米器件1 MeV以下低能质子所引起的单粒子翻转截面比高能质子单粒子翻转饱和截面最高可达3个数量级. 采用基于试验数据和器件信息相结合的方法, 构建了较为精确的复合灵敏体积几何结构模型, 在此基础上采用蒙特卡罗方法揭示了低能质子穿过多层金属布线层, 由于能量岐离使展宽能谱处于布拉格峰值的附近, 通过直接电离方式将能量集中沉积在灵敏体积内, 是导致单粒子翻转截面峰值的根本原因. 并针对某一轨道环境预估了低能质子对空间质子单粒子翻转率的贡献.     

累积辐照影响静态随机存储器单粒子翻转敏感性的仿真研究

基于解析分析对比了大尺寸与深亚微米尺度下静态随机存取存储器(static random access memory, SRAM)单元单粒子翻转敏感性的表征值及引入累积辐照后的变化趋势. 同时借助仿真模拟计算了0.18 μm工艺对应的六管SRAM单元在对应不同累积剂量情况下, 离子分别入射不同中心单管时的电学响应变化, 计算结果与解析分析所得推论相一致, 即只有当累积辐照阶段与单粒子作用阶段存储相反数值时, SRAM单元的单粒子翻转敏感性才会增强. 关键词： 累积辐照 单粒子翻转 静态随机存储器 器件仿真     

随机静态存储器低能中子单粒子翻转效应

建立了中子单粒子翻转可视化分析方法,对不同特征尺寸（0.13~1.50 μm）CMOS工艺商用随机静态存储器(SRAM)器件开展了反应堆中子单粒子翻转效应的实验研究,获得了SRAM器件的裂变谱中子单粒子翻转截面随特征尺寸变化的变化趋势。研究结果表明:SRAM器件的特征尺寸越小,其对低能中子导致的单粒子翻转的敏感性越高。     

纳米静态随机存储器质子单粒子多位翻转角度相关性研究

器件特征尺寸的减小带来单粒子多位翻转的急剧增加, 对现有加固技术带来了极大挑战. 针对90 nm SRAM(static random access memory, 静态随机存储器)开展了中高能质子入射角度对单粒子多位翻转影响的试验研究, 结果表明随着质子能量的增加, 单粒子多位翻转百分比和多样性增加, 质子单粒子多位翻转角度效应与质子能量相关. 采用一种快速计算质子核反应引起单粒子多位翻转的截面积分算法, 以Geant4中Binary Cascade模型作为中高能质子核反应事件发生器, 从次级粒子的能量和角度分布出发, 揭示了质子与材料核反应产生的次级粒子中, LET(linear energy transfer)最大, 射程最长的粒子优先前向发射是引起单粒子多位翻转角度相关性的根本原因. 质子能量、临界电荷的大小是影响纳米SRAM器件质子多位翻转角度相关性的关键因素. 质子能量越小, 多位翻转截面角度增强效应越大; 临界电荷的增加将增强质子多位翻转角度效应.     

Synergistic effects of total ionizing dose on single event upset sensitivity in static random access memory under proton irradiation

Nitrogen plasma passivation （NPP） on （111） germanium （Ge） was studied in terms of the interface trap density, roughness, and interfacial layer thickness using plasma-enhanced chemical vapor deposition （PECVD）. The results show that NPP not only reduces the interface states, but also improves the surface roughness of Ge, which is beneficial for suppressing the channel scattering at both low and high field regions of Ge MOSFETs. However, the interracial layer thickness is also increased by the NPP treatment, which will impact the equivalent oxide thickness （EOT） scaling and thus degrade the device performance gain from the improvement of the surface morphology and the interface passivation. To obtain better device performance of Ge MOSFETs, suppressing the interfacial layer regrowth as well as a trade-off with reducing the interface states and roughness should be considered carefully when using the NPP process.     

Pattern imprinting in deep sub-micron static random access memories induced by total dose irradiation

Pattern imprinting in deep sub-micron static random access memories(SRAMs) during total dose irradiation is investigated in detail. As the dose accumulates, the data pattern of memory cells loading during irradiation is gradually imprinted on their background data pattern. We build a relationship between the memory cell’s static noise margin(SNM) and the background data, and study the influence of irradiation on the probability density function of ?SNM, which is the difference between two data sides’ SNMs, to discuss the reason for pattern imprinting. Finally, we demonstrate that, for micron and deep sub-micron devices, the mechanism of pattern imprinting is the bias-dependent threshold shift of the transistor, but for a deep sub-micron device the shift results from charge trapping in the shallow trench isolation(STI) oxide rather than from the gate oxide of the micron-device.     

Recovery of single event upset in advanced complementary metal-oxide semiconductor static random access memory cells

Using computer-aided design three-dimensional (3D) simulation technology,the recovery mechanism of single event upset and the effects of spacing and hit angle on the recovery are studied.It is found that the multi-node charge collection plays a key role in recovery and shielding the charge sharing by adding guard rings.It cannot exhibit the recovery effect.It is also indicated that the upset linear energy transfer (LET) threshold is kept constant while the recovery LET threshold increases as the spacing increases.Additionally,the effect of incident angle on recovery is analysed and it is shown that a larger angle can bring about a stronger charge sharing effect,thus strengthening the recovery ability.     

Recovery of single event upset in advanced complementary metalben oxide semiconductor static random access memory cells

Using computer-aided design three-dimensional (3D) simulation technology, the recovery mechanism of single event upset and the effects of spacing and hit angle on the recovery are studied. It is found that the multi-node charge collection plays a key role in recovery and shielding the charge sharing by adding guard rings. It cannot exhibit the recovery effect. It is also indicated that the upset linear energy transfer (LET) threshold is kept constant while the recovery LET threshold increases as the spacing increases. Additionally, the effect of incident angle on recovery is analysed and it is shown that a larger angle can bring about a stronger charge sharing effect, thus strengthening the recovery ability.     

Ionizing radiation effect on single event upset sensitivity of ferroelectric random access memory

The impact of ionizing radiation effect on single event upset(SEU) sensitivity of ferroelectric random access memory(FRAM) is studied in this work. The test specimens were firstly subjected to ~(60)Co γ-ray and then the SEU evaluation was conducted using ~(209)Bi ions. As a result of TID-induced fatigue-like and imprint-like phenomena of the ferroelectric material, the SEU cross sections of the post-irradiated devices shift substantially. Different trends of SEU cross section with elevated dose were also found, depending on whether the same or complementary test pattern was employed during the TID exposure and the SEU measurement.