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.

Experimental study of temperature dependence of single-event upset in SRAMs

We report on the temperature dependence of single-event upsets in the 215–353 K range in a 4M commercial SRAM manufactured in a 0.15-lm CMOS process,utilizing thin film transistors. The experimental results show that temperature influences the SEU cross section on the rising portion of the cross-sectional curve(such as the chlorine ion incident). SEU cross section increases 257 %when the temperature increases from 215 to 353 K. One of the possible reasons for this is that it is due to the variation in upset voltage induced by changing temperature.

An online fast multi-track locating algorithm for high-resolution single-event effect test platform

To improve the efficiency and accuracy of single-event effect(SEE)research at the Heavy Ion Research Facility at Lanzhou,Hi’Beam-SEE must precisely localize the position at which each heavy ion hitting the integrated circuit(IC)causes SEE.In this study,we propose a fast multi-track location(FML)method based on deep learning to locate the position of each particle track with high speed and accuracy.FML can process a vast amount of data supplied by Hi’Beam-SEE online,revealing sensitive areas in real time.FML is a slot-based object-centric encoder-decoder structure in which each slot can learn the location information of each track in the image.To make the method more accurate for real data,we designed an algorithm to generate a simulated dataset with a distribution similar to that of the real data,which was then used to train the model.Extensive comparison experiments demonstrated that the FML method,which has the best performance on simulated datasets,has high accuracy on real datasets as well.In particular,FML can reach 238 fps and a standard error of 1.6237μm.This study discusses the design and performance of FML.

Temperature dependence of single-event transients in SiGe heterojunction bipolar transistors for cryogenic applications

We experimentally demonstrate that the dominant mechanism of single-event transients in silicon-germanium heterojunction bipolar transistors(SiGe HBTs)can change with decreasing temperature from+20℃to-180℃.This is accomplished by using a new well-designed cryogenic experimental system suitable for a pulsed-laser platform.Firstly,when the temperature drops from+20℃to-140℃,the increased carrier mobility drives a slight increase in transient amplitude.However,as the temperature decreases further below-140℃,the carrier freeze-out brings about an inflection point,which means the transient amplitude will decrease at cryogenic temperatures.To better understand this result,we analytically calculate the ionization rates of various dopants at different temperatures based on Altermatt's new incomplete ionization model.The parasitic resistivities with temperature on the charge-collection pathway are extracted by a two-dimensional(2D)TCAD process simulation.In addition,we investigate the impact of temperature on the novel electron-injection process from emitter to base under different bias conditions.The increase of the emitter-base junction's barrier height at low temperatures could suppress this electron-injection phenomenon.We have also optimized the built-in voltage equations of a high current compact model(HICUM)by introducing the impact of incomplete ionization.The present results and methods could provide a new reference for effective evaluation of single-event effects in bipolar transistors and circuits at cryogenic temperatures,and could provide a new evidence of the potential of SiGe technology in applications in extreme cryogenic environments.

Azimuthal dependence of single-event and multiple-bit upsets in SRAM devices with anisotropic layout

Experimental evidence is presented showing obvious azimuthal dependence of single event upsets(SEU) and multiple-bit upset(MBU) patterns in radiation hardened by design(RHBD) and MBU-sensitive static random access memories(SRAMs), due to the anisotropic device layouts. Depending on the test devices, a discrepancy from 24.5% to 50% in the SEU cross sections of dual interlock cell(DICE) SRAMs is shown between two perpendicular ion azimuths under the same tilt angle. Significant angular dependence of the SEU data in this kind of design is also observed, which does not fit the inverse-cosine law in the effective LET method. Ion trajectory-oriented MBU patterns are identified, which is also affected by the topological distribution of sensitive volumes. Due to that the sensitive volumes are periodically isolated by the BL/BLB contacts along the Y-axis direction, double-bit upsets along the X-axis become the predominant configuration under normal incidence.Predominant triple-bit upset and quadruple-bit upset patterns are the same under different ion azimuths(Lshaped and square-shaped configurations, respectively). Those results suggest that traditional RPP/IRPP model should be promoted to consider the azimuthal and angular dependence of single event effects in certain designs.During earth-based evaluation of SEE sensitivity, worst case beam direction, i.e., the worst case response, should be revealed to avoid underestimation of the on-orbit error rate.

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.

Investigation of maximum proton energy for qualified ground based evaluation of single-event effects in SRAM devices

Existing standards show a clear discrepancy in the specification of the maximum proton energy for qualified ground-based evaluation of single-event effects,which can range from 180 to 500 MeV. This work finds that the threshold linear energy transfer of a tested device is a critical parameter for determining the maximum proton energy. The inner mechanisms are further revealed. Highenergy deposition events(>10 MeV) in sensitive volumes are attributed to the interaction between protons and the tungsten vias in the metallization layers.

Single-event effects induced by medium-energy protons in 28 nm system-on-chip

Single-event effects(SEEs)induced by mediumenergy protons in a 28 nm system-on-chip(SoC)were investigated at the China Institute of Atomic Energy.An on-chip memory block was irradiated with 90 MeV and 70 MeV protons,respectively.Single-bit upset and multicell upset events were observed,and an uppermost number of nine upset cells were discovered in the 90 MeV proton irradiation test.The results indicate that the SEE sensitivities of the 28 nm SoC to the 90 MeV and 70 MeV protons were similar.Cosmic Ray Effects on Micro-Electronics Monte Carlo simulations were analyzed,and it demonstrates that protons can induce effects in a 28 nm SoC if their energies are greater than 1.4 MeV and that the lowest corresponding linear energy transfer was 0.142 MeV cm^2 mg^-1.The similarities and discrepancies of the SEEs induced by the 90 MeV and 70 MeV protons were analyzed.

Prototype of single-event effect localization system with CMOS pixel sensor

The single-event effect(SEE) is a serious threat to electronics in radiation environments. The most important issue in radiation-hardening studies is the localization of the sensitive region in electronics to the SEE. To solve this problem, a prototype based on a complementary metal oxide semiconductor(CMOS) pixel sensor, i.e., TopmetalM, was designed for SEE localization. A beam test was performed on the prototype at the radiation terminal of the Heavy Ion Research Facility in Lanzhou(HIRFL). The results indicated that the inherent deflection angle of the prototype to the beam was 1.7°, and the angular resolution was 0.6°. The prototype localized heavy ions with a position resolution of 3.4 μm.

Analysis of single-event transient sensitivity in fully depleted silicon-on-insulator MOSFETs

Based on 3 D-TCAD simulations, single-event transient(SET) effects and charge collection mechanisms in fully depleted silicon-on-insulator(FDSOI) transistors are investigated. This work presents a comparison between28-nm technology and 0.2-lm technology to analyze the impact of strike location on SET sensitivity in FDSOI devices. Simulation results show that the most SET-sensitive region in FDSOI transistors is the drain region near the gate. An in-depth analysis shows that the bipolar amplification effect in FDSOI devices is dependent on the strike locations. In addition, when the drain contact is moved toward the drain direction, the most sensitive region drifts toward the drain and collects more charge. This provides theoretical guidance for SET hardening.

Single-event-effect propagation investigation on nanoscale system on chip by applying heavy-ion microbeam and event tree analysis

The propagation of single-event effects(SEEs)on a Xilinx Zynq-7000 system on chip(SoC)was inves-tigated using heavy-ion microbeam radiation.The irradia-tion results reveal several functional blocks’sensitivity locations and cross sections,for instance,the arithmetic logic unit,register,D-cache,and peripheral,while irradi-ating the on-chip memory(OCM)region.Moreover,event tree analysis was executed based on the obtained microbeam irradiation results.This study quantitatively assesses the probabilities of SEE propagation from the OCM to other blocks in the SoC.

Catalytic Cracking of Cycloparaffins Admixed with Olefins:1. Single-Event Microkinetic(SEMK) Modeling

Single-event microkinetic(SEMK) model of the catalytic cracking of methylcyclohexane admixed with 1-octene over REUSY zeolites at 693 K—753 K in the absence of coke formation is enhanced. To keep consistency with the wellknown carbenium ion chemistry, hydride transfer forming and consuming allylic carbenium ions in the aromatization of cycloparaffins are further investigated and differentiated. The reversibility of endocyclic β-scission and cyclization reactions is refined by accounting explicitly for the reacting olefins and resulting cycloparaffins in the corresponding thermodynamics. 24 activation energies for the reactions involved in the cracking of cycloparaffins are obtained by the regression of 15 sets of experimental data upon taking the resulting 37 main cracking products, i. e., responses into account. The enhanced SEMK model can adequately describe the catalytic behavior of 37 main products with conversion and temperature.

Scaling effects of single-event gate rupture in thin oxides

The dynamics of the excess carriers generated by incident heavy ions are considered in both SiO2 and Si substrate. Influences of the initial radius of the charge track, surface potential decrease, external electric field, and the LET value of the incident ion on internal electric field buildup are analyzed separately. Considering the mechanisms of recombination, impact ionization, and bandgap tunneling, models are verified by using published experimental data. Moreover, the scaling effects of single-event gate rupture in thin gate oxides are studied, with the feature size of the MOS device down to 90 nm. The walue of the total electric field decreases rapidly along with the decrease of oxide thickness in the first period （1 2 nm to 3.3 nm）, and then increases a little when the gate oxide becomes thinner and thinner （3.3 nm to 1.8 nm）.

Catalytic Cracking of Cycloparaffins Admixed with Olefins:2. Single-Event Microkinetic(SEMK) Assessment

The developed SEMK model is used to provide an insight into the contribution of individual reactions in the cracking of methylcyclohexane as well as the site coverage by various carbenium ions. The preferred reaction pathways for the conversion of methylcyclohexane are hydride transfer reactions followed by PCP-isomerizations, deprotonation and endocyclic β-scission, accounting for 61%, 22% and 12% of its disappearance, respectively, at 693 K and 30% conversion of methylcyclohexane. Protolysis plays a minor role in the cracking of methylcyclohexane. Once cyclic diolefins are formed, all of them can be instantaneously transformed to aromatics, which are easily interconverted via disproportionation. Judging from the carbenium ion concentrations it is evident that, at the investigated operating conditions, less than 5% of the acid sites are covered by carbenium ions, less than 2% of which corresponds to cyclic type species including allylic ones.

Mechanism of single-event transient pulse quenching between dummy gate isolated logic nodes

As integrated circuits scale down in size, a single high-energy ion strike often affects multiple adjacent logic nodes.The so-called single-event transient（SET） pulse quenching induced by single-event charge sharing collection has been widely studied. In this paper, SET pulse quenching enhancement is found in dummy gate isolated adjacent logic nodes compared with that isolated by the common shallow trench isolation（STI）. The physical mechanism is studied in depth and this isolation technique is explored for SET mitigation in combinational standard cells. Three-dimensional（3D） technology computer-aided design simulation（TCAD） results show that this technique can achieve efficient SET mitigation.

Impact of proton-induced alteration of carrier lifetime on single-event transient in SiGe heterojunction bipolar transistor

This paper presents an investigation into the impact of proton-induced alteration of carrier lifetime on the singleevent transient(SET) caused by heavy ions in silicon–germanium heterojunction bipolar transistor(SiGe HBT).The ioninduced current transients and integrated charge collections under different proton fluences are obtained based on technology computer-aided design(TCAD) simulation.The results indicate that the impact of carrier lifetime alteration is determined by the dominating charge collection mechanism at the ion incident position and only the long-time diffusion process is affected.With a proton fluence of 5 × 1013 cm-2, almost no change is found in the transient feature, and the charge collection of events happened in the region enclosed by deep trench isolation(DTI), where prompt funneling collection is the dominating mechanism.Meanwhile, for the events happening outside DTI where diffusion dominates the collection process, the peak value and the duration of the ion-induced current transient both decrease with increasing proton fluence, leading to a great decrease in charge collection.

Development of Contactless Method of the DUT Heating during Single-Event Effect Tests

This paper presents two approaches to perform the electronic device heating during radiation hardness assurance tests.Commonly used conductive heating approach is compared with contactless laser-based approach,characteristics and limitations of these methods are described.Experimental results for temperature dependence of single-event latchup(SEL)cross-section during heavy ion irradiation along with some aspects of physics-based numerical simulation of heat transfer processes are presented.

Experimental and simulation studies of single-event transient in partially depleted SOI MOSFET

In this study, we investigate the single-event transient（SET） characteristics of a partially depleted silicon-on-insulator（PDSOI） metal-oxide-semiconductor（MOS） device induced by a pulsed laser.We measure and analyze the drain transient current at the wafer level. The results indicate that the body-drain junction and its vicinity are more SET sensitive than the other regions in PD-SOI devices.We use ISE 3D simulation tools to analyze the SET response when different regions of the device are hit. Then, we discuss in detail the characteristics of transient currents and the electrostatic potential distribution change in devices after irradiation. Finally, we analyze the parasitic bipolar junction transistor（p-BJT） effect by performing both a laser test and simulations.

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.

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。