适用于纳米工艺的SET/SEU加固触发器设计

针对触发器在纳米级工艺下容易受空间辐射中单粒子效应的影响而产生软错误的情况,基于CPSH触发器结构,研究了一种对单粒子效应中SET/SEU加固的延时采样软错误防护(DSSEP)触发器结构.该触发器由延时采样单元、输入传输单元、软错误鲁棒存储锁存器和反相输出单元组成.延时采样单元对来自其他逻辑电路的输出数据进行采样,采样数据经输入传输单元写入软错误鲁棒存储锁存器,并通过一个反相输出单元输出.仿真结果表明,DSSEP触发器具有很好的SET/SEU加固能力.经过比较和分析,证明DSSEP触发器与具有同样SET/SEU加固能力的保护门触发器(GGFF)相比,在晶体管数目和传播延时方面仅为GGFF的62％和33％.     

基于DICE结构的主-从型抗辐照触发器设计

基于双互锁存储单元(DICE)结构,采用TSMC 0.18μm体硅CMOS工艺,设计了一个带复位和清零端的主一从型抗辐照触发器.通过将数据存放在不同的节点以及电路的恢复机制,使单个存储节点具有抗单粒子翻转的能力.采用多种改进设计,增强抗单粒子瞬态脉冲(single event transient,SET)的能力,并且降低了电路功耗.通过Spectre仿真,测试了触发器的抗单粒子翻转(single event upset,SEU)能力,确定了版图设计规则.采用新颖的3倍高度的版图布置及环栅NMOS结构,消除了总剂量效应;采用双保护环,降低了单粒子闩锁效应;最终完成了全方位抗辐照的触发器电路设计.     

改进DICE结构的D触发器抗SEU设计

基于DICE结构主-从型D触发器的抗辐照加固方法的研究,在原有双立互锁存储单元(DICE)结构D触发器的基础上改进电路结构,其主锁存器采用抗静态、动态单粒子翻转(SEU)设计,从锁存器保留原有的DICE结构。主锁存器根据电阻加固与RC滤波的原理,将晶体管作电阻使用,使得电路中存在RC滤波,通过设置晶体管合理的宽长比,使其与晶体管间隔的节点的电平在SEU期间不变化,保持原电平状态,从而使电路具有抗动态SEU的能力。Spectre仿真结果表明,改进的D触发器既具有抗动态SEU能力,又保留了DICE抗静态SEU较好的优点,其抗单粒子翻转效果较好。     

0.18 μm SOI工艺抗辐照触发器性能研究

随着集成电路制造工艺尺寸不断减小、集成度不断提高,集成电路在太空环境应用中更容易受到单粒子辐照效应的影响,可靠性问题越发严重。特别是对高频数字电路而言,单粒子翻转效应(SEU)及单粒子瞬态扰动(SET)会导致数据软错误。虽然以往的大尺寸SOI工艺,具有很好的抗单粒子性能,但仍需要对深亚微米SOI电路进行辐照效应研究。文中通过对4种触发器链进行抗辐照设计,用0.18μm SOI工艺进行了流片验证,并与体硅CMOS工艺对比分析。1.8V电源电压条件下的触发器翻转阈值可以达到41.7MeV·cm2/mg,抗辐射性能比0.18μm体硅CMOS工艺提升了约200%。     

基于时序优先的电路容错混合加固方案

为了有效降低容忍软错误设计的硬件和时序开销,该文提出一种时序优先的电路容错混合加固方案。该方案使用两阶段加固策略,综合运用触发器替换和复制门法。第1阶段,基于时序优先的原则,在电路时序松弛的路径上使用高可靠性时空冗余触发器来加固电路;第2阶段,在时序紧张的路径使用复制门法进行加固。和传统方案相比,该方案既有效屏蔽单粒子瞬态(SET)和单粒子翻转(SEU),又减少了面积开销。ISCAS89电路在45 nm工艺下的实验表明,平均面积开销为36.84%,电路平均软错误率降低99%以上。     

源区浅结SOI MOSFET的辐照效应模拟

研究了源区浅结的不对称SOI MOSFET对浮体效应的改善,模拟了总剂量、抗单粒子事件(SEU)、瞬时辐照效应以及源区深度对抗辐照性能的影响.这种结构器件的背沟道抗总剂量能力比传统器件有显著提高,并且随着源区深度的减小,抗总剂量辐照的能力不断加强.体接触不对称结构的抗SEU和瞬时辐照能力优于无体接触结构和传统结构器件,这与体接触对浮体效应的抑制和寄生npn双极晶体管电流增益的下降有关.     

28 nm工艺触发器中能质子单粒子效应研究

基于采取不同加固措施的28 nm体硅CMOS工艺的触发器链,开展了中能质子对纳米级电路单粒子翻转(SEU)效应影响的研究。选取20 MeV、40 MeV、60 MeV以及100 MeV质子对电路进行辐照,得到相关的SEU截面,结果显示,随着入射质子能量的增加,SEU截面增加,并在60 MeV质子能量点附近达到饱和,翻转截面接近8×10^-14cm^-2/bit。对采取了不同加固方法的触发器链的试验数据进行分析对比,可以看到,单独的版图加固措施只能稍微降低翻转率;DICE结构可以将翻转截面降低一个数量级,电路面积增加一倍左右;时间冗余延迟+DICE的方法基本可以使电路不发生翻转,但电路面积大大增加且造成一定的延迟。     

源区浅结SOI MOSFET的辐照效应模拟

研究了源区浅结的不对称SOIMOSFET对浮体效应的改善 ,模拟了总剂量、抗单粒子事件 (SEU)、瞬时辐照效应以及源区深度对抗辐照性能的影响 .这种结构器件的背沟道抗总剂量能力比传统器件有显著提高 ,并且随着源区深度的减小 ,抗总剂量辐照的能力不断加强 .体接触不对称结构的抗SEU和瞬时辐照能力优于无体接触结构和传统结构器件 ,这与体接触对浮体效应的抑制和寄生npn双极晶体管电流增益的下降有关     

反熔丝和Flash FPGA对造成器件功能故障具有免疫能力

在设计高可靠性系统时,无论是陆地、航空或太空应用,设计人员都必须非常小心地选择器件技术。如果选择不当会导致FIT(FailuresInTime)大幅度提高,即使基站应用也不例外。军事和航空设计人员认识到半导体器件存在单事件翻转(SingleEventUpset;SEU)效应,以及基于SRAM技术器件的相关软错误率(SoftErrorRate;SER)。SEU的发生是由于带电的亚原子粒子撞击触发器或SRAM单元,这个进入的粒子会沉积足够的电荷,导致触发器或存储器单元的状态改变,以致损坏所存储的数据。因为这种现象不会永久损坏存储单元,SEU常被称为软错误。在太空应用…     

一种异构双核SoC的抗SEU加固方案

异构双核SoC结构复杂,不同部分受到单粒子翻转(SEU)的影响程度不同。采用单一的技术对整个SoC进行加固,既浪费资源,效果也不好。根据不同部分受SEU影响的不同特点,选取SoC中受SEU影响最大的几个部分进行优化加固。使用自动三模冗余添加技术对处理器的寄存器堆和取指通道进行了加固,使用汉明码对存储器进行了加固,使用软硬协同的软件签名技术对CPU运行的程序进行了检测,不会对CPU的性能产生影响。仿真和物理实现的结果表明,相对于未加固的设计,该方案抗SEU能力提高了6倍,与全加固设计的抗SEU能力相当。该方案的面积消耗仅为34%,而全加固的为88%。     

Exploring the Limitations of Software-based Techniques in SEE Fault Coverage

This paper presents a detailed analysis of the efficiency of software-based techniques to mitigate SEU and SET in microprocessors. A set of well-known rules is presented and implemented automatically to transform an unprotected program into a hardened one. SEU and SET are injected in all sensitive areas of a MIPS-based microprocessor architecture. The efficiency of each rule and a combination of them are tested. Experimental results show the limitations of the control-flow techniques in detecting the majority of SEU and SET faults, even when different basic block sizes are evaluated. A further analysis on the undetected faults with control flow effect is done and five causes are explained. The conclusions may lead designers into developing more efficient techniques to detect these types of faults.     

基于保护门的纳米CMOS电路抗单粒子瞬态加固技术研究

随着器件特征尺寸的缩减,单粒子瞬态效应(SET)成为空间辐射环境中先进集成电路可靠性的主要威胁之一。基于保护门,提出了一种抗SET的加固单元。该加固单元不仅可以过滤组合逻辑电路传播的SET脉冲,而且因逻辑门的电气遮掩效应和电气隔离,可对SET脉冲产生衰减作用,进而减弱到达时序电路的SET脉冲。在45 nm工艺节点下,开展了电路的随机SET故障注入仿真分析。结果表明,与其他加固单元相比,所提出的加固单元的功耗时延积(PDP)尽管平均增加了17.42%,但容忍SET的最大脉冲宽度平均提高了113.65%,且时延平均降低了38.24%。     

Single event soft error in advanced integrated circuit

As technology feature sizes decrease, single event upset (SEU), and single event transient (SET) dominate the radiation response of microcircuits. Multiple bit upset (MBU) (or multi cell upset) effects, digital single event transient (DSET) and analogue single event transient (ASET) caused serious problems for advanced integrated circuits (ICs) applied in a radiation environment and have become a pressing issue. To face this challenge, a lot of work has been put into the single event soft error mechanism and mitigation schemes. This paper presents a review of SEU and SET, including: a brief historical overview, which summarizes the historical development of the SEU and SET study since their first observation in the 1970's; effects prominent in advanced technology, which reviews the effects such as MBU, MSET as well as SET broadening and quenching with the influence of temperature, device structure etc.; the present understanding of single event soft error mechanisms, which review the basic mechanism of single event generation including various component of charge collection; and a discussion of various SEU and SET mitigation schemes divided as circuit hardening and layout hardening that could help the designer meet his goals.     

A Stage-Wise Soft-Error Detection Scheme for Flip-Flop Based Pipelines in Secure Cloud Servers

The shrinking feature sizes make transistors increasingly susceptible to soft errors, which can severely degrade the systems’ RAS (Reliability, Availability, and Serviceability). The tough challenge results from not only increasing SER (soft error rate) of storage cells, but also the increasing susceptibility of combinational logics to soft errors. How to efficiently detect soft errors becomes the primary problem in the Backward Error Recovery (BER) schemes that are cost-effective in soft error tolerance. This paper presents a soft error detection scheme, AUDITOR, for flip-flop based pipelines. The AUDITOR copes with both types of soft errors—single event upset (SEU) and single event transient (SET). We propose a “local-audit” fault detection mechanism, by which each pipeline stage is verified independently and the verifying result registers with a dedicated “audit” bit (V-bit). All the V-bits are distributed across the whole pipeline and synergically monitor the pipeline execution. To relax the constraint of SET detection capability imposed by the inherent fully synchronous operation mode in flip-flop based pipelines, we firstly propose using path-compensation technique to address this constraint. Furthermore, a reuse-based design paradigm is employed to reduce the implementation complexity and area overhead. The AUDITOR possesses robust detection capability and short detection latency, at the expense of about 29 % and 50 % increase in area and power consumption, respectively.     

A Timing-Aware Probabilistic Model for Single-Event-Upset Analysis

With device size shrinking and fast rising frequency ranges, the effect of cosmic radiations and alpha particles known as single-event upset (SEU) and single-event transients (SET), is a growing concern in logic circuits. Accurate understanding and estimation of SEU sensitivities of individual nodes is necessary to achieve better soft error hardening techniques at logic level design abstraction. We propose a probabilistic framework to the study the effect of inputs, circuits structure, and gate delays on SEU sensitivities of nodes in logic circuits as a single joint probability distribution function (pdf). To model the effect of timing, we consider signals at their possible arrival times as the random variables of interest. The underlying joint probability distribution function, consists of two components: ideal random variables without the effect of SEU and the random variables affected by the SEU. We use a Bayesian network to represent the joint pdf which is a minimal compact directional graph for efficient probabilistic modeling of uncertainty. The attractive feature of this model is that not only does it use the conditional independence to arrive at a sparse structure, but it also utilizes the same for smart probabilistic inference. We show that results with exact (exponential complexity) and approximate nonsimulative stimulus-free inference (linear in number of nodes and samples) on benchmark circuits yield accurate estimates in reasonably small computation time     

Emulation-based fault analysis on RFID tags for robustness and security evaluation

This paper presents an FPGA (field-programmable gate array) based fault emulation system for analysis of fault impact on security and robustness of RFID (radio frequency identification) tags. This emulation system that deals with any RFID protocol consists of two tag-reader pairs, a fault injection module and an emulation controller all implemented in a single FPGA. The designed approach performs single event upset (SEU) and single event transient (SET) fault injection and permits with high flexibility to set communication scenarios and related parameters. Moreover, we propose a classification of produced errors to evaluate fault impacts and identify most sensitive tag flip-flops causing large number of failures and security concerns. The proposed fault injection approach provides suitable means to increase tags' security and robustness. In our experimentation campaign, an ultra-high frequency (UHF) tag architecture has been exposed to intensive SEU and SET fault injections. The duration of the campaign including results analysis is 30 min in where 6,215,316 faults are experimented. Our results have shown that the tag has tolerated 61.82% of SEUs and 67.83% of SETs. The flip-flops that constitute the tag FSM (finite state machine) have been identified as the most sensitive parts causing large number of failures.     

Strength violation effect on soft-error detection in sub-micron technology

In nanometer technologies, circuits are increasingly sensitive to various kinds of perturbations. Alpha particles and atmospheric neutrons induce single-event upsets (SEU), affecting memory cells, latches, and flip-flops. In addition, single-event transients (SET) can be initiated in the combinational logic and captured by the latches and flip-flop associated with the logic outputs. Designers cannot control the sources of soft-errors, but their effects can be mitigated through soft-error detection techniques. This paper proposes an algorithm to detect soft-errors at the switch-level caused by current spikes which can affect the driving strength. The offered approach uses a novel coding system to be applied in certain functions that are sensitive to strength variations. It is able to detect even the slight changes in signal strength caused by both cosmic rays and alpha particle from package contamination. Most soft-error detection techniques sense the logic changes in the circuit while this paper proves that a wide range of soft-errors are the result of strength violation in switch-level. Experimental results illustrate the importance of accurate simulation methods and stress the effect of driving strength changes in switch-level for soft-error detection in today’s technology.     

设计和表征一个65nm抗辐射标准单元库

提出了一个基于商用65nm工艺在晶体管级设计抗辐射数字标准单元库的方法。因为当C单元的两个输入是不同的逻辑值时输出会进入高阻模式,并保持输出逻辑电平不变,而当输入端有相同的逻辑值时,C单元的功能就像一个反相器的特性。因此它有把因为辐射粒子引起的单粒子翻转（SEU）效应或单粒子传输（SET）效应所产生的毛刺滤除掉的能力。在这个标准单元库中包含了在晶体管级使用C单元设计了抗辐射的触发器,以便于芯片设计者可以使用这个库来设计具有更高抗辐射能力和减小面积、功耗和延迟的芯片。在最后为了能表征标准单元在硅片上的延迟特性,一个基于环形振荡器的芯片结构用来测量每个单元的延迟,以及验证抗辐射能力。延迟测量结果跟版图后仿真结果偏差在10％以内。     

改进型抗单粒子效应D触发器

在对抗单粒子效应技术研究的基础上,构造了一种改进型的抗单粒子翻转和单粒子瞬变的主从型边沿D触发器.该D触发器在不影响设计流程的情况下能使得整个芯片都具有抗单粒子效应,并有效改善了以往由于引入抗辐射设计而导致芯片面积大幅度提高的问题.