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.     

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.     

静态随机存储器单粒子翻转效应三维数值模拟

针对特征尺寸为1.5 μm的国产静态随机存储器（SRAM）,构建了三维SRAM存储单元模型,并对重离子引起的SRAM单粒子翻转效应进行了数值模拟.计算并分析了单粒子引起的单粒子翻转和电荷收集的物理图像,得到了SRAM器件的单粒子翻转截面曲线.单粒子翻转的数值模拟结果与重离子微束、重离子宽束实验结果比较一致,表明所建立的三维器件模型可以用来研究SRAM器件的单粒子翻转效应. 关键词： 三维数值模拟 单粒子翻转 微束 宽束     

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.     

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.     

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     

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.     

Angular dependence of multiple-bit upset response in static random access memories under heavy ion irradiation

Experimental evidence is presented relevant to the angular dependences of multiple-bit upset (MBU) rates and patterns in static random access memories (SRAMs) under heavy ion irradiation. The single event upset (SEU) cross sections under tilted ion strikes are overestimated by 23.9% 84.6%, compared with under normally incident ion with the equivalent linear energy transfer (LET) value of ～ 41 MeV/(mg/cm 2 ), which can be partially explained by the fact that the MBU rate for tilted ions of 30 is 8.5%-9.8% higher than for normally incident ions. While at a lower LET of ～ 9.5 MeV/(mg/cm 2 ), no clear discrepancy is observed. Moreover, since the ion trajectories at normal and tilted incidences are different, the predominant double-bit upset (DBU) patterns measured are different in both conditions. Those differences depend on the LET values of heavy ions and devices under test. Thus, effective LET method should be used carefully in ground-based testing of single event effects (SEE) sensitivity, especially in MBU-sensitive devices.     

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.     

光电耦合器不同辐照剂量率下的伽玛总剂量效应

开展了光电耦合器在0.01,0.1,1.0和50rad(Si)/s四种剂量率下的伽玛射线(60 Coγ)辐照实验,结果表明:γ辐照导致光电耦合器电流传输比下降,辐照到相同总剂量,电流传输比下降幅度基本上随剂量率的减小而增大。在不拆封破坏光电耦合器的情况下,通过对光电耦合器中的发光二极管I-V特性、光敏晶体管增益及初级光电流的测试,以及耦合介质传输损耗特性的分析,证明了导致光电耦合器电流传输比退化的主导因素是光敏晶体管C-B区光响应度的下降。     

Pattern dependence in synergistic effects of total dose on single-event upset hardness

The pattern dependence in synergistic effects was studied in a 0.18 μm static random access memory(SRAM) circuit.Experiments were performed under two SEU test environments:3 Me V protons and heavy ions.Measured results show different trends.In heavy ion SEU test,the degradation in the peripheral circuitry also existed because the measured SEU cross section decreased regardless of the patterns written to the SRAM array.TCAD simulation was performed.TIDinduced degradation in n MOSFETs mainly induced the imprint effect in the SRAM cell,which is consistent with the measured results under the proton environment,but cannot explain the phenomena observed under heavy ion environment.A possible explanation could be the contribution from the radiation-induced GIDL in pMOSFETs.     

铁电存储器~(60)Co γ射线及电子总剂量效应研究

以型号为FM28 V100的铁电存储器为研究对象,进行了~(60)Co γ射线和2 Me V电子辐照实验.研究了铁电存储器不同工作方式、不同辐射源下的总剂量辐射损伤规律,用J-750测试部分直流参数和交流参数,分析了存储器敏感参数的变化规律.实验结果表明:对动态、静态加电、静态不加电三种工作方式下的结果进行比较.其中静态加电工作方式下产生的陷阱电荷最多,是存储器最恶劣的工作方式;器件的一些电参数随总剂量发生变化,在功能失效之前部分参数已经失效;在静态加电这种最恶劣的工作方式下,得到~(60)Co γ射线比电子造成更加严重的辐照损伤.     

Single event upset on static random access memory devices due to spallation,reactor, and monoenergetic neutrons

This paper presents new neutron-induced single event upset(SEU) data on the SRAM devices with the technology nodes from 40 nm to 500 nm due to spallation, reactor, and monoenergetic neutrons. The SEU effect is investigated as a function of incident neutron energy spectrum, technology node, byte pattern and neutron fluence rate. The experimental data show that the SEU effect mainly depends on the incident neutron spectrum and the technology node, and the SEU sensitivity induced by low-energy neutrons significantly increases with the technology downscaling. Monte–Carlo simulations of nuclear interactions with device architecture are utilized for comparing with the experimental results. This simulation approach allows us to investigate the key parameters of the SEU sensitivity, which are determined by the technology node and supply voltage. The simulation shows that the high-energy neutrons have more nuclear reaction channels to generate more secondary particles which lead to the significant enhancement of the SEU cross-sections, and thus revealing the physical mechanism for SEU sensitivity to the incident neutron spectrum.     

14 nm FinFET和65 nm平面工艺静态随机存取存储器中子单粒子翻转对比

使用中国散裂中子源提供的宽能谱中子束流,开展14 nm FinFET工艺和65 nm平面工艺静态随机存取存储器中子单粒子翻转对比研究,发现相比于65 nm器件,14 nm FinFET器件的大气中子单粒子翻转截面下降至约1/40,而多位翻转比例从2.2%增大至7.6%,源于14 nm FinFET器件灵敏区尺寸(80 nm×30 nm×45 nm)、间距和临界电荷(0.05 fC)的减小.不同于65 nm器件对热中子免疫的现象,14 nm FinFET器件中M0附近10B元素的使用导致其表现出一定的热中子敏感性.进一步的中子输运仿真结果表明,高能中子在器件灵敏区中产生的大量的射程长、LET值大的高Z二次粒子是多位翻转的产生诱因,而单粒子翻转主要来自于p,He,Si等轻离子的贡献.     

静态随机存储器总剂量辐射损伤的在线与离线测试方法

以静态随机存储器为研究对象,对其在线和离线测试下的总剂量辐射损伤规律进行了研究,探寻了两种测试条件下总剂量损伤的差异并对造成差异的物理机制进行了分析和讨论,研究结果表明:由于静态随机存储器存在多种总剂量失效模式,相对于在线测试只能覆盖存储单元固定错误的一种失效模式,离线测试可覆盖多种功能失效模式;由于信号完整性对测试频率的限制,使得在线测试得到的动态功耗电流值要明显小于离线测试得到的动态功耗电流值;由于"印记效应"的存在,在线测试静态功耗电流小于离线测试中器件存储与辐照相反数据时的静态功耗电流值;在线无法测量的一些电参数,有可能先于在线可测参数而失效,这些研究结果对于静态随机存储器在星用辐射环境下的总剂量辐射损伤规律的研究和实验评估具有重要意义。     

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.     

Supply voltage scaled dependency of the recovery of single event upset in advanced complementary metal-oxide-semiconductor static random-access memory cells

Using the technology computer-aided design three-dimensional simulation, the supply voltage scaled dependency of the recovery of single event upset and charge collection in static random-access memory cells are investigated. It reveals that the recovery linear energy transfer threshold decreases with the supply voltage reducing, which is quite attractive to the dynamic voltage scaling and subthreshold circuits radiation-hardened design. Additionally, the effect of supply voltage on charge collection is also investigated. It is concluded that the supply voltage mainly affects the bipolar gain of parasitical bipolar junction transistor (BJT) and the existence of the source plays an important role in the supply voltage variation.     

The supply voltage scaled dependency of the recovery of single event upset in advanced complementary metal-oxide-semiconductor static random-access memory cells

Using computer-aided design three-dimensional simulation technology,the supply voltage scaled dependency of the recovery of single event upset and charge collection in static random-access memory cells are investigated.It reveals that the recovery linear energy transfer threshold decreases with the supply voltage reducing,which is quite attractive for dynamic voltage scaling and subthreshold circuit radiation-hardened design.Additionally,the effect of supply voltage on charge collection is also investigated.It is concluded that the supply voltage mainly affects the bipolar gain of the parasitical bipolar junction transistor(BJT) and the existence of the source plays an important role in supply voltage variation.     

双极晶体管的系统电磁脉冲与剂量率综合效应

建立典型半导体器件系统电磁脉冲与剂量率综合效应计算模型,对在瞬态X射线辐照下电缆末端典型n+-p-n-n+结构的双极晶体管负载的系统电磁脉冲与剂量率综合效应进行研究,得到了综合效应现象,分析了综合效应机理,总结了综合效应规律。在系统电磁脉冲与剂量率综合效应作用下,双极晶体管内部,由于载流子数量剧增,其反向击穿阈值降低,综合效应比单一效应更易造成双极晶体管的毁伤。编制的系统电磁脉冲与剂量率综合效应计算程序可用于分析电子学系统中其他类型半导体器件的效应机理与规律。     

卫星光通信系统中SRAM/MOS器件的单粒子翻转率分析

为了分析单粒子事件对卫星光通信系统造成的影响,需要预估器件的单粒子翻转率。通过比较微分能谱方法和FOM方法,选取FOM方法估算了在不同高度和不同倾角下的单粒子翻转率。分析了质子单粒子翻转率与空间轨道的关系。提出了基于单粒子翻转率的器件可靠性指标。数值计算结果表明,在较低轨道高度和较小轨道倾角条件下,SRAM/MOS器件受单粒子翻转影响较小、可靠性较高。