Heavy ion energy influence on multiple-cell upsets in small sensitive volumes:from standard to high energies

The 28 nm process has a high cost-performance ratio and has gradually become the standard for the field of radiation-hardened devices.However,owing to the minimum physical gate length of only 35 nm,the physical area of a standard 6T SRAM unit is approximately 0.16μm^(2),resulting in a significant enhancement of multi-cell charge-sharing effects.Multiple-cell upsets(MCUs)have become the primary physical mechanism behind single-event upsets(SEUs)in advanced nanometer node devices.The range of ionization track effects increases with higher ion energies,and spacecraft in orbit primarily experience SEUs caused by high-energy ions.However,ground accelerator experiments have mainly obtained low-energy ion irradiation data.Therefore,the impact of ion energy on the SEU cross section,charge collection mechanisms,and MCU patterns and quantities in advanced nanometer devices remains unclear.In this study,based on the experimental platform of the Heavy Ion Research Facility in Lanzhou,low-and high-energy heavy-ion beams were used to study the SEUs of 28 nm SRAM devices.The influence of ion energy on the charge collection processes of small-sensitive-volume devices,MCU patterns,and upset cross sections was obtained,and the applicable range of the inverse cosine law was clarified.The findings of this study are an important guide for the accurate evaluation of SEUs in advanced nanometer devices and for the development of radiation-hardening techniques.

Microstructure and mechanical properties of AZ31-Mg_2Si in situ composite fabricated by repetitive upsetting

AZ31-4.6% Mg2Si （mass fraction） composite was prepared by conventional casting method. Repetitive upsetting （RU） was applied to severely deforming the as-cast composite at 400 ℃ for 1, 3, and 5 passes. Finite element analysis of the material flow indicates that deformation concentrates in the bottom region of the sample after 1 pass, and much more uniform deformation is obtained after 5 passes. During multi-pass RU process, both dendritic and Chinese script type Mg2Si phases are broken up into smaller particles owing to the shear stress forced by the matrix. With the increasing number of RU passes, finer grain size and more homogeneous distribution of Mg2Si particles are obtained along with significant enhancement in both strength and ductility. AZ31-4.6%Mg2Si composite exhibits tensile strength of 284 MPa and elongation of 9.8%after 5 RU passes at 400 ℃ compared with the initial 128 MPa and 5.4%of original AZ31-4.6%Mg2Si composite.

BREAKAGE MECHANISM OF TUNGSTEN BASED ALLOY BLOCK FOR ELECTRO-HEAT UPSETTING

The breakage mechanism of W-Ni-Fe alloy in the process of electro-heat upsetting studied both theoretically and experimetnally, and also the behaviors of crack formation and propagation were analysed. Alloy suffers from corrosion and thermal-mechanical fatigue mutual function. Simultaneously, the practical ways to improve the anvil life was discussed.

Unique microstructure and property of a 2024 aluminum alloy subjected to upsetting extrusion multiple processing

The microstructure and hardness of a 2024 aluminum alloy subjected tomulti-pass upsetting extrusion at ambient temperature were studied. Experimental results indicatedthat with the number of upsetting extrusion passes increasing, the grains of the alloy are graduallyrefined and the hardness increases correspondingly. After ten passes of upsetting extrusionprocessing, the grain size decreases to less than 200 nm in diameter and the sample maintains itsoriginal shape, while the hardness is double owing to equal-axial ultrafine grains and workhardening effect caused by large plastic deformation.

ANALYSIS OF THREE-DIMENSIONAL UPSETTING PROCESS BY THE RIGID-PLASTIC REPRODUCING KERNEL PARTICLE METHOD

A meshless approach, called the rigid-plastic reproducing kernel particle method （RKPM）, is presented for three-dimensional （3D） bulk metal forming simulation. The approach is a combination of RKPM with the flow theory of 3D rigid-plastic mechanics. For the treatments of essential boundary conditions and incompressibility constraint, the boundary singular kernel method and the modified penalty method are utilized, respectively. The arc-tangential friction model is employed to treat the contact conditions. The compression of rectangular blocks, a typical 3D upsetting operation, is analyzed for different friction conditions and the numerical results are compared with those obtained using commercial rigid-plastic FEM （finite element method） software Deform^3D. As results show, when handling 3D plastic deformations, the proposed approach eliminates the need of expensive meshing and remeshing procedures which are unavoidable in conventional FEM and can provide results that are in good agreement with finite element predictions.

Velocity Field and Variation of Wall Thickness During Tube Dieless Upsetting

Theoretical analyses show that the variation of wall thickness is in direct proportion to outer-diameter, inter-diameter, and (1+R_s)^(1/2) (Rs is sectional increase ratio of tube), the theoretical calculated results of wall thickness during tube dieless upsetting are very approximate to the experimental one. As the width of deformation field increases, both the variation of wall thickness and the derivative of wall thickness variation to width of deformation field (to/tf) reduce.

Formation mechanism of basin-like depression defect in electric upsetting process of Ni80A superalloy

A kind of surface instability,basin-like depression defect companied by mixed grain structure at the bottom of large-scale valve during electric upsetting process,would significantly influence the microstructures and mechanical properties of components.In order to analyze the forming process of the basin-like depression defect,a finite element model for the electric upsetting process of Ni80A superalloy was developed using multi-field and multi-scale coupling analysis method.Subsequently,a series of parameters loading path schemes for force and current were designed by varying the initial value,peak value and value level,and their effects on basin-like depression and mixed grain structure were simulated and uncovered.It is concluded that the changes of heating speed and pressurization speed result in the different flow velocities between the inner and outer layers of billet,thus exerting the basin-like depression.Simulation results also indicate that these defects can be optimized through the parameter coordination between force and current.Finally,the validity and reliability of the finite element model were verified by physical experiments in electric upsetting process.

Effect of material parameters on stress wave propagation during fast upsetting

Based on a dynamic analysis method and an explicit algorithm,a dynamic explicit finite element code was developed for modeling the fast upsetting process of block under drop hammer impact,in which the hammer velocity during the deformation was calculated by energy conservation law according to the operating principle of hammer equipment.The stress wave propagation and its effect on the deformation were analyzed by the stress and strain distributions.Industrial pure lead,oxygen-free high-conductivity (OFHC) copper and 7039 aluminum alloy were chosen to investigate the effect of material parameters on the stress wave propagation.The results show that the stress wave propagates from top to bottom of block,and then reflects back when it reaches the bottom surface.After that,stress wave propagates and reflects repeatedly between the upper surface and bottom surface.The stress wave propagation has a significant effect on the deformation at the initial stage,and then becomes weak at the middle-final stage.When the ratio of elastic modulus or the slope of stress-strain curve to mass density becomes larger,the velocity of stress wave propagation increases,and the influence of stress wave on the deformation becomes small.

ELASTO-PLASTIC FEM ANALYSIS OF CYLINDER UPSETTING BETWEEN TWO FLAT PLATENS

A whole analysis model including forging and flat platens is built,which is used to analyse the process of upsetting a cylinder between flat platens.The influence of surface friction and transient temperature are comprehensively considered.By means of ANSYS software,the elasto plastic FEM analysis of the whole upsetting process is carried out.From the point of view of numerical calculation,the correctness of the centre region tension stress theory about upsetting a cylinder between flat platens is tested and verified.The concept of plasto nucleus is presented to explain the forming of double dumps.The efffect of temperature is inspected.The relation curves between the radial stress of the symmetry centre point and the relative pression ratio are given.

Influence of Friction Condition on Cold Upsetting of Tube Flange

FEM is used to analyze the influence of interface friction on the material flow and the cause of forming defect in the cold upsetting of tube flange. Based on the FEM simulation results, the relationships between flange width and the extreme friction factors are established. The concept of forming limit diagram for cold upsetting of tube flange is presented.

Design of Novel and Low Cost Triple-node Upset Self-recoverable Latch

With the development of semiconductor technology,the size of transistors continues to shrink.In complex radiation environments in aerospace and other fields,small-sized circuits are more prone to soft error(SE).Currently,single-node upset(SNU),double-node upset(DNU)and triple-node upset(TNU)caused by SE are relatively common.TNU’s solution is not yet fully mature.A novel and low-cost TNU self-recoverable latch(named NLCTNURL)was designed which is resistant to harsh radiation effects.When analyzing circuit resiliency,a double-exponential current source is used to simulate the flipping behavior of a node’s stored value when an error occurs.Simulation results show that the latch has full TNU self-recovery.A comparative analysis was conducted on seven latches related to TNU.Besides,a comprehensive index combining delay,power,area and self-recovery—DPAN index was proposed,and all eight types of latches from the perspectives of delay,power,area,and DPAN index were analyzed and compared.The simulation results show that compared with the latches LCTNURL and TNURL which can also achieve TNU self-recoverable,NLCTNURL is reduced by 68.23%and 57.46%respectively from the perspective of delay.From the perspective of power,NLCTNURL is reduced by 72.84%and 74.19%,respectively.From the area perspective,NLCTNURL is reduced by about 28.57%and 53.13%,respectively.From the DPAN index perspective,NLCTNURL is reduced by about 93.12%and 97.31%.The simulation results show that the delay and power stability of the circuit are very high no matter in different temperatures or operating voltages.

Numerical simulation of upsetting-extruding process of dispersion strengthened copper welding electrode

The simulation of the upsetting-extruding process of dispersion strengthened copper welding electrode was carried out using Deform-2D finite element analysis software, and the characteristics of metal flow and the effect of different friction factors were analysed. The results show that the whole forming process consists of a forward extrusion and a backward extrusion. When the friction factor of the female die is 0.4, it is advantageous to the forward extrusion forming of the electrode work nose part, while the friction factor of the male die is only 0.1, it would be benefit to the backward extrusion forming of the electrode fit-up hole part. Addition of a scoop channel with 1.5 mm in depth and 4 mm in diameter at the bottom of the female die can avoid folds at the work nose. The rise in temperature is about 60 ℃ during the forming process.

一种基于C单元的三节点翻转自恢复锁存器

随着集成电路中工艺尺寸的不断缩减,锁存器也越来越容易受到粒子辐射引起的三节点翻转的影响。针对该问题,基于C单元的结构,提出一种低功耗、低延时和高鲁棒性的三节点翻转并自恢复的MKEEP锁存器。通过仿真实验和PVT的波动实验表明,相对于其他拥有三节点容忍或自恢复能力的锁存器,该锁存器拥有低功耗、低延迟和更小的面积开销,且对工艺、电压和温度的敏感度较低,优势明显。

多向镦拔2219铝合金硬质相形貌观测与分析

为进一步优化2219铝合金的力学性能,采用多向镦拔工艺改善2219铝合金中硬质相形貌。随着累积变形量增加到7.9,硬质相面积占比从9.66%降低为7.37%;并且其中长径比大于3的硬质相占比由初始的83.15%降低到34.23%。基于应变梯度理论建立了长椭球硬质相的细观模型,考虑到硬质相尺度效应,当其长径比从1增加到8时,应力集中系数从3.17增大为11.67;随着变形量的增加,硬质相的尺度效应逐渐弱化。通过多向镦拔实验证明了其可以有效改善硬质相形貌;将实验结果与计算结果进行对比,证明了应变梯度理论应用于2219铝合金硬质相分析的可行性。

多楔轮毂缘多道次旋压成形工艺研究

针对传统锻后切削工艺生产多楔轮存在材料利用率低、切断齿形金属流线等问题,以某多楔轮零件为研究对象,基于旋压近净成形原理,对多楔轮毂缘制定了多道次旋压工艺方案。基于SIMUFACT软件平台建立了多道次旋压成形全流程三维有限元模型,通过数值模拟研究了各道次旋压成形过程中的毂缘区材料流动规律及增厚情况。模拟结果表明,旋压预制坯外缘在第1道次旋弯轮弧挤压作用下发生明显的弯曲和增厚,板坯整体呈“半弧形”结构,后经过第2道次旋平轮镦挤推平,板坯整体发生二次增厚并成形出满足旋齿厚度要求的毂缘筒壁;通过第3道次和第4道次旋齿工艺使毂缘筒壁金属发生转移,形成满足尺寸要求的齿形结构。根据模拟结果进行试验研究,成功试制出质量合格的多楔轮零件,验证了该成形方案的可行性。

NMOS晶体管电荷共享导致的SRAM单元单粒子翻转恢复效应研究

基于Synopsys公司的三维器件模拟软件TCAD,本文研究了NMOS晶体管电荷共享导致SRAM单元的单粒子翻转恢复(SEUR)效应。分析了NMOS晶体管电荷共享导致SEUR效应的物理机制,系统研究了NMOS晶体管偏置(如电源电压、P阱偏置电压)和工艺参数(如P+深阱掺杂浓度、P阱接触距离)对线性能量传输翻转恢复阈值(LETrec)以及单粒子翻转脉冲宽度(PWrec)的影响。研究发现:PWrec随着电源电压的增大而增大;PWrec和LETrec随着P阱偏置电压的增大而减小;LETrec随着P+深阱掺杂浓度的增大而增大;PWrec随着P阱接触与NMOS晶体管之间距离的增大而增大,而LETrec随着P阱接触与NMOS晶体管之间距离增大而减小。本文研究结论有助于优化SRAM单元抗单粒子效应设计,尤其是基于SEUR效应的SRAM单元的抗辐照加固设计提供了理论指导。

Multiple Node Upset in SEU Hardened Storage Cells

We study the problem of multiple node upset （MNU） using three-dimensional device simulation. The results show the transient floating node and charge lateral diffusion are the key reasons for MNU. We compare the MNU with multiple bit upset （MBU）,and find that their characteristics are different. Methods to avoid MNU are also discussed.

TC18钛合金热锻成形摩擦系数的实验研究

在TC18钛合金热锻成形过程中,摩擦系数对锻件成品率和模具服役寿命有显著影响。为了精确测定不同工艺条件下的摩擦系数,基于工艺实验结合Deform-3D有限元分析的方法,通过建立摩擦系数标定曲线,测定了TC18钛合金圆环在不同润滑条件下镦粗过程中的摩擦系数,对温度场、应变场及金属流动状态进行了分析。结果表明,在TC18钛合金热锻成形工艺过程中,干摩擦条件下的摩擦系数最大,为0.70~0.80;复合润滑布条件下的摩擦系数最小,为0.30~0.40;在保温棉+纤维布的润滑条件下,摩擦系数为0.40;保温棉润滑条件下的摩擦系数为0.60~0.70。

FinFET器件单粒子翻转物理机制研究评述

鳍式场效应晶体管(FinFET)器件由于其较高的集成度以及运算密度,已成为未来航天应用领域的重要选择。FinFET器件的辐射敏感性与其制作工艺和工作条件息息相关。为了解FinFET器件的单粒子翻转(SEU)敏感机制,文章结合国内外开展的相关研究,从SEU机理出发,分析了器件特征尺寸、电源电压和入射粒子的线性能量传输(LET)值等不同条件对器件SEU敏感性的影响,最后结合实际对FinFET器件SEU的研究发展方向进行展望。

空间混合辐射环境器件单粒子在轨错误率预估及不确定度分析方法

针对空间混合辐射对器件单粒子在轨错误率的影响,基于典型静态随机存储器利用中国原子能科学研究院HI-13串列加速器以及钴源总剂量模拟辐照试验装置开展协合效应研究,发展了一种器件在混合辐射环境下的单粒子在轨错误率计算方法。并利用该方法计算了协合效应影响下的航天器典型任务周期器件的在轨错误率,同时分析了器件在轨错误率计算中的不确定度来源并计算了在轨错误率不确定度。结果表明,对于该类型器件,空间混合辐射场导致的协合效应将降低器件单粒子在轨错误率。