Showing papers in "IEEE Transactions on Nuclear Science in 2003"
TL;DR: Physical mechanisms responsible for nondestructive single-event effects in digital microelectronics are reviewed, concentrating on silicon MOS devices and integrated circuits as discussed by the authors, and the impact of technology trends on single event susceptibility and future areas of concern are explored.
Abstract: Physical mechanisms responsible for nondestructive single-event effects in digital microelectronics are reviewed, concentrating on silicon MOS devices and integrated circuits. A brief historical overview of single-event effects in space and terrestrial systems is given, and upset mechanisms in dynamic random access memories, static random access memories, and combinational logic are detailed. Techniques for mitigating single-event upset are described, as well as methods for predicting device and circuit single-event response using computer simulations. The impact of technology trends on single-event susceptibility and future areas of concern are explored.
1,028Â citations
TL;DR: In this article, the basic physical mechanisms of the interactions of ionizing radiation with MOS oxides, including charge generation, transport, trapping and detrapping, and interface trap formation, are discussed.
Abstract: This paper reviews the basic physical mechanisms of the interactions of ionizing radiation with MOS oxides, including charge generation, transport, trapping and detrapping, and interface trap formation. Device and circuit effects are also discussed briefly.
735Â citations
TL;DR: A historical review of the literature on the effects of radiation-induced displacement damage in semiconductor materials and devices to provide a guide to displacement damage literature and to offer critical comments regarding that literature in an attempt to identify key findings.
Abstract: This paper provides a historical review of the literature on the effects of radiation-induced displacement damage in semiconductor materials and devices. Emphasis is placed on effects in technologically important bulk silicon and silicon devices. The primary goals are to provide a guide to displacement damage literature, to offer critical comments regarding that literature in an attempt to identify key findings, to describe how the understanding of displacement damage mechanisms and effects has evolved, and to note current trends. Selected tutorial elements are included as an aid to presenting the review information more clearly and to provide a frame of reference for the terminology used. The primary approach employed is to present information qualitatively while leaving quantitative details to the cited references. A bibliography of key displacement-damage information sources is also provided.
607Â citations
TL;DR: In this paper, the authors review the total dose, single-event effects, and dose rate hardness of silicon-on-insulator (SOI) devices and use body ties to reduce bipolar amplification.
Abstract: Silicon-on-insulator (SOI) technologies have been developed for radiation-hardened applications for many years and are rapidly becoming a main-stream commercial technology. The authors review the total dose, single-event effects, and dose rate hardness of SOI devices. The total dose response of SOI devices is more complex than for bulk-silicon devices due to the buried oxide. Radiation-induced trapped charge in the buried oxide can increase the leakage current of partially depleted transistors and decrease the threshold voltage and increase the leakage current of fully depleted transistors. Process techniques that reduce the net amount of radiation-induced positive charge trapped in the buried oxide and device design techniques that mitigate the effects of trapped charge in the buried oxide have been developed to harden SOI devices to bulk-silicon device levels. The sensitive volume for charge collection in SOI technologies is much smaller than for bulk-silicon devices potentially making SOI devices much harder to single-event upset (SEU). However, bipolar amplification caused by floating body effects can significantly reduce the SEU hardness of SOI devices. Body ties are used to reduce floating body effects and improve SEU hardness. SOI ICs are completely immune to classic four-layer p-n-p-n single-event latchup; however, floating body effects make SOI ICs susceptible to single-event snapback (single transistor latch). The sensitive volume for dose rate effects is typically two orders of magnitude lower for SOI devices than for bulk-silicon devices. By using body ties to reduce bipolar amplification, much higher dose rate upset levels can be achieved for SOI devices than for bulk-silicon devices.
384Â citations
TL;DR: In this paper, the authors analyzed the performance enhancements made possible by improved timing as a function of the coincidence time resolution, and showed that PET scanners based on LSO have the potential for significantly better coincidence timing resolution than the 6 ns FWHM typically achieved with BGO.
Abstract: PET scanners based on LSO have the potential for significantly better coincidence timing resolution than the 6 ns FWHM typically achieved with BGO. This study analyzes the performance enhancements made possible by improved timing as a function of the coincidence time resolution. If 500 ps FWHM coincidence timing resolution can be achieved in a complete PET camera, the following four benefits can be realized for whole-body FDG imaging: 1) the random event rate can be reduced by using a narrower coincidence timing window, increasing the peak NECR by /spl sim/50%; 2) using time-of-flight (TOF) in the reconstruction algorithm will reduce the noise variance by a factor of 5; 3) emission and transmission data can be acquired simultaneously, reducing the total scan time; and 4) axial blurring can be reduced by using TOF to determine the correct axial plane of origin for each event. While TOF was extensively studied in the 1980s, practical factors limited its effectiveness at that time and little attention has been paid to timing in PET since then. As these potential improvements are substantial and the advent of LSO PET cameras gives us the means to obtain them without other sacrifices, efforts to improve PET timing should resume after their long dormancy.
337Â citations
TL;DR: The progress on developing models of the radiation environment since the 1960s is reviewed with emphasis on models that can be applied to predicting the performance of microelectronics used in spacecraft and instruments as mentioned in this paper.
Abstract: The progress on developing models of the radiation environment since the 1960s is reviewed with emphasis on models that can be applied to predicting the performance of microelectronics used in spacecraft and instruments. Space, atmospheric, and ground environments are included. It is shown that models must be adapted continually to account for increased understanding of the dynamics of the radiation environment and the changes in microelectronics technology. The IEEE Nuclear and Space Radiation Effects Conference is a vital forum to report model progress to the radiation effects research community.
308Â citations
TL;DR: An overview of these radiation-induced effects, their dependencies, and the many different approaches to their mitigation is presented in this paper, where the authors present an overview of the radiation effects on metal-oxide-semiconductor devices and integrated circuits.
Abstract: Total ionizing dose radiation effects on the electrical properties of metal-oxide-semiconductor devices and integrated circuits are complex in nature and have changed much during decades of device evolution. These effects are caused by radiation-induced charge buildup in oxide and interfacial regions. This paper presents an overview of these radiation-induced effects, their dependencies, and the many different approaches to their mitigation.
274Â citations
TL;DR: In this paper, the authors reviewed the development of destructive single-event effects over the last 40 years, including latchup, burnout, gate rupture, and snap-back.
Abstract: Developments in the field of destructive single-event effects over the last 40 years are reviewed. Single-event latchup, single-event burnout, single-event gate rupture, and single-event snap-back are discussed beginning with the first observation of each effect, its phenomenology, and the development of present day understanding of the mechanisms involved.
234Â citations
TL;DR: The method demonstrates improved image quality in all cases when compared to the conventional FBP and EM methods presently used for clinical data (which do not include resolution modeling).
Abstract: Methodology for PET system modeling using image-space techniques in the expectation maximization (EM) algorithm is presented. The approach, applicable to both list-mode data and projection data, is of particular significance to EM algorithm implementations which otherwise only use basic system models (such as those which calculate the system matrix elements on the fly). A basic version of the proposed technique can be implemented using image-space convolution, in order to include resolution effects into the system matrix, so that the EM algorithm gradually recovers the modeled resolution with each update. The improved system modeling (achieved by inclusion of two convolutions per iteration) results in both enhanced resolution and lower noise, and there is often no need for regularization-other than to limit the number of iterations. Tests have been performed with simulated list-mode data and also with measured projection data from a GE Advance PET scanner, for both [/sup 18/F]-FDG and [/sup 124/I]-NaI. The method demonstrates improved image quality in all cases when compared to the conventional FBP and EM methods presently used for clinical data (which do not include resolution modeling). The benefits of this approach for /sup 124/I (which has a low positron yield and a large positron range, usually resulting in noisier and poorer resolution images) are particularly noticeable.
205Â citations
TL;DR: The simulation of decaying sources is illustrated on a dual-isotope acquisition with multiple time-frames and first comparisons of simulated point-spread functions and spectra with experimental results obtained from a small-animal gamma camera prototype are presented.
Abstract: GATE, the Geant4 application for tomographic emission, is a simulation platform developed for PET and SPECT. It combines a powerful simulation core, the Geant4 toolkit, with newly developed software components dedicated to nuclear medicine. In particular, it models the passing of time during real acquisitions, allowing it to handle dynamic systems such as decaying source distributions or moving detectors. We present several series of results that illustrate the possibilities of this new platform. The simulation of decaying sources is illustrated on a dual-isotope acquisition with multiple time-frames. Count rate curves taking into account random coincidences and dead-time are shown for a dual-crystal setup and for a small-animal PET scanner configuration. Simulated resolution curves and reconstructed images are shown for rotating PET scanners. Lastly, we present first comparisons of simulated point-spread functions and spectra with experimental results obtained from a small-animal gamma camera prototype.
204Â citations
TL;DR: In this article, the proton-induced nonionizing energy loss (NIEL) for representative device materials is presented for the energy range between the displacement damage threshold to 1 GeV.
Abstract: The proton-induced nonionizing energy loss (NIEL) for representative device materials are presented for the energy range between the displacement damage threshold to 1 GeV. All interaction mechanisms (Coulomb and nuclear elastic/nonelastic) are fully accounted for in the present NIEL calculations. For Coulomb interactions, the Ziegler-Biersack-Littmark (ZBL) screened potential was used in the lower energy range (<50 MeV) and the relativistic formulation was used in the higher energy range (/spl ges/50 MeV). A charged particle transport code, MCNPX, was used to compute the NIEL due to nuclear interactions.
TL;DR: The degradation of high electron mobility transistors due to 1.8-MeV proton irradiation was measured at fluences up to 3/spl times/10/sup 15/ cm/sup -2.
Abstract: The degradation of AlGaN/AlN/GaN high electron mobility transistors due to 1.8-MeV proton irradiation was measured at fluences up to 3/spl times/10/sup 15/ cm/sup -2/. The devices have much higher mobility than AlGaN/GaN devices, but they possess similarly high radiation tolerance, exhibiting little degradation at fluences up to 1/spl times/10/sup 14/ cm/sup -2/. Decreased sheet carrier mobility due to increased carrier scattering and decreased sheet carrier density due to carrier removal are the primary damage mechanisms. The device degradation is observed as a decrease in the maximum transconductance, an increase in the threshold voltage, and a decrease in the drain saturation current.
TL;DR: In this article, the performance in X-ray spectroscopy using planar diode and drift detectors in SiC has been estimated in a wide range of operating temperature (up to 150/spl deg/C).
Abstract: This work presents an analysis of silicon carbide (SiC) as semiconductor for the realization of detectors for soft X-rays (<20 keV). On the basis of experimental data on prototype SiC junctions, the performance in X-ray spectroscopy using planar diode and drift detectors in SiC have been estimated in a wide range of operating temperature (up to 150/spl deg/C). It has been derived that, due to their extremely low reverse current density (4.7 pA/cm/sup 2/ at 300 K and 17 pA/cm/sup 2/ at 340 K and at electric field of 100 kV/cm), SiC detectors can potentially reach superior performance with respect to all the other semiconductors presently employed at or above room temperature. In particular, a comparative theoretical analysis, based on experimental data on state-of-the-art silicon and SiC junctions, shows that SiC detectors with areas larger than 1 mm/sup 2/ have the potentiality to offer higher energy resolution when operating at temperature above 25/spl deg/C. An energy resolution of about 700 and 1300 eV FWHM have been estimated for 1 mm/sup 2/ and 10 mm/sup 2/ SiC pad detectors operating at 100/spl deg/C with a silicon front-end FET. The contribution of a standard silicon front-end electronics on the system performance has been analyzed. The open issues in SiC technology for X-ray detector development are highlighted.
TL;DR: In this paper, carrier generation based on subbandgap two-photon absorption is used to perform three-dimensional mapping of the single-event transient response of the LM124 operational amplifier.
Abstract: Carrier generation based on subbandgap two-photon absorption is used to perform three-dimensional mapping of the single-event transient response of the LM124 operational amplifier. Three classes of single-event-induced transients are observed for the input transistor Q20. A combination of experiment and transistor level modeling is used to assign the different classes of measured transients to charge collection across specific junctions. The large-amplitude, positive-going transients cannot be assigned to a single junction, and are identified with a collector-substrate photocurrent.
TL;DR: Total-dose radiation hardness assurance is reviewed for MOS and bipolar devices and integrated circuits (ICs), with an emphasis on issues addressed by recent revisions to military and commercial standard test methods.
Abstract: Total-dose radiation hardness assurance is reviewed for MOS and bipolar devices and integrated circuits (ICs), with an emphasis on issues addressed by recent revisions to military and commercial standard test methods. Hardness assurance typically depends upon sample tests of a subgroup of devices or circuits to determine whether the full group meets its performance and functionality requirements to a desired confidence level. The dose rates of many standard test methods match neither the very high dose rates of some military environments nor the very low dose rates of most space environments. So, one must ensure that hardness assurance test plans address device response in the radiation environment of interest. An increasing emphasis has been placed over the last few decades on standardized test procedures to qualify devices for use in the natural space radiation environment. Challenging issues for defining test methods for space environments are nMOS transistor threshold-voltage rebound and enhanced low-dose-rate sensitivity for linear bipolar devices and ICs. Effects of preirradiation elevated temperature stress on MOS radiation response are also a significant concern. Trends are identified for future radiation hardness tests on advanced microelectronics technologies.
TL;DR: The development of the investigation of total dose effects in bipolar devices and circuits is covered over the past 40 years as discussed by the authors, with the early studies on discrete transistors highlighted by the early study on linear circuits and I/sup 2/L, the effects of total doses on recessed field oxide digital circuits and most recently, the low dose rate sensitivity of bipolar linear circuits.
Abstract: The development of the investigation of total dose effects in bipolar devices and circuits is covered over the past 40 years. There are at least four chronological stages in this field of study highlighted by the early studies on discrete transistors, the effects of total dose on linear circuits and I/sup 2/L, the effects of total dose on recessed field oxide digital circuits and, most recently, the low dose rate sensitivity of bipolar linear circuits.
TL;DR: Radiation testing of a commercial-off-the-shelf SRAM-based field-programmable gate arrays (FPGAs) with heavy ions shows the FPGA look-up table (LUT) resources are the most sensitive to SEUs, whereas interconnect resources areThe most critical for the device cross section because they use the largest number of configuration bits.
Abstract: This paper presents the radiation testing of a commercial-off-the-shelf SRAM-based field-programmable gate arrays (FPGAs) with heavy ions. Test experiments have been conducted to identify and to classify the single-event upsets (SEUs) in the configuration memory that induce single-event functional interrupt for the user-implemented circuit. Moreover the paper presents a new approach for assessing the effects of SEUs based on the combination of radiation testing and simulation-based fault injection tool. First experimental results show the FPGA look-up table (LUT) resources (used to implement combinatorial logic) are the most sensitive to SEUs, whereas interconnect resources are the most critical for the device cross section because they use the largest number of configuration bits. The analysis of experimental data underlines that the most probable error affecting interconnections is the shorting of two nets. This observation indicates that new fault models should be considered along with the classic stuck-at one model designing fault-tolerant architectures, which are intended for implementation in FPGA devices.
TL;DR: Mechanisms for enhanced low-dose-rate sensitivity are described, which include electron-hole recombination, hydrogen recapture at hydrogen source sites, and hydrogen dimerization to form hydrogen molecules that dominate the kinetics at high dose rates.
Abstract: Mechanisms for enhanced low-dose-rate sensitivity are described. In these mechanisms, bimolecular reactions dominate the kinetics at high dose rates thereby causing a sub-linear dependence on total dose, and this leads to a dose-rate dependence. These bimolecular mechanisms include electron-hole recombination, hydrogen recapture at hydrogen source sites, and hydrogen dimerization to form hydrogen molecules. The essence of each of these mechanisms is the dominance of the bimolecular reactions over the radiolysis reaction at high dose rates. However, at low dose rates, the radiolysis reaction dominates leading to a maximum effect of the radiation.
TL;DR: In this article, an accelerator test was used to validate the performance of an FPGA single event upset (SEU) simulator, which is used to probe the sensitive bits in various logic designs.
Abstract: An accelerator test was used to validate the performance of an FPGA single event upset (SEU) simulator. The Crocker Nuclear Laboratory cyclotron proton accelerator was used to irradiate the SLAAC1-V, a Xilinx Virtex FPGA board. We also used the SLAAC1-V as the platform for a configuration bitstream SEU simulator. The simulator was used to probe the "sensitive bits" in various logic designs. The objective of the accelerator experiment was to characterize the simulator's ability to predict the behavior of a test design in the proton beam during a dynamic test. The test utilized protons at 63.3 MeV, well above the saturation cross-section for the Virtex part. Protons were chosen because, due to their lower interaction rate, we can achieve the desired upset rate of about one configuration bitstream upset per second. The design output errors and configuration upsets were recorded during the experiment and compared to results from the simulator. In summary, for an extensively tested design, the simulator predicted 97% of the output errors observed during radiation testing. The SEU simulator can now be used with confidence to quickly and affordably examine logic designs to 'map' sensitive bits, to provide assurance that incorporated mitigation techniques perform correctly, and to evaluate the costs and benefits of various mitigation strategies. The simulator provides an excellent test environment that accurately represents radiation induced configuration bitstream upsets.
TL;DR: In this paper, an analytical model for calculating nonionizing energy loss (NIEL) for heavy ions based on screened Coulomb potentials in the nonrelativistic limit is described.
Abstract: We describe an analytical model for calculating nonionizing energy loss (NIEL) for heavy ions based on screened Coulomb potentials in the nonrelativistic limit. The model applies to any incident ion on any target material where the Coulomb interaction is primarily responsible for atomic displacement. Results are compared with previous methods of extracting NIEL from Monte Carlo SRIM runs. Examples of NIEL calculations are given for incident ions having energies ranging from the threshold for atomic displacement to 1 GeV. The incident ions include H, He, B, Si, Fe, Xe, and Au. Example targets include Si, GaAs, InP, and SiC.
TL;DR: A-PET as mentioned in this paper uses relatively large 19 mm diameter photomultiplier tubes (PMT) but nevertheless achieves good spatial and energy resolution, and can achieve high NEC rates for small cylindrical phantoms.
Abstract: In recent years it has been shown that PET is capable of obtaining in vivo metabolic images of small animals. These serve as models to study the development and progress of diseases within humans. Imaging small animals requires not only image resolution better than 2 mm, but also high sensitivity in order to image ligands with low specific activity or radiochemical yields. Toward achieving these goals, we have developed a discrete 2 /spl times/ 2 /spl times/ 10 mm/sup 3/ GSO Anger-logic detector for use in a high resolution, high sensitivity, and high count-rate animal PET scanner. This detector uses relatively large 19 mm diameter photomultiplier tubes (PMT), but nevertheless achieves good spatial and energy resolution. The scanner (A-PET) has a port diameter of 21 cm, transverse field-of-view of 12.8 cm, axial length of 11.6 cm, and operates in 3-D volume imaging mode. The absolute coincidence sensitivity is 1.3% for a point source. Due to the use of large PMTs in an Anger design, the encoding ratio (number of crystals/PMT) is high, which reduces the complexity and leads to a cost-effective scanner. Simulation results show that this scanner can achieve high NEC rates for small cylindrical phantoms due to its high sensitivity and low dead-time. Initial measurements show that our design goals for spatial resolution and sensitivity were realized in the prototype scanner.
TL;DR: In this article, improved experimental methods are discussed for laboratory measurement of conductivity and electric field in insulating spacecraft material intended for space radiation and plasma environments, which are up to four orders of magnitude smaller than those determined by existing standard methods.
Abstract: Improved experimental methods are discussed for laboratory measurement of conductivity and electric field in insulating spacecraft material intended for space radiation and plasma environments. These measurement techniques investigate the following features: 1) measurements of conductivity are up to four orders of magnitude smaller than those determined by existing standard methods. 2) Conductivity is altered as radiation accumulates and trapping states fill with electrons. 3) With intense kiloelectronvolt electron irradiation, electrons are continually emitted for hours from the irradiated surface after the irradiation ceases. 4) Charging induced by electron irradiation is strongly modified by the electron-hole pairs that the irradiation generates in the insulator. 5) High field effects at 10/sup 6/ V/cm act strongly on the electron-hole pairs and on electrons in shallow traps to provide extended conductivity. 6) The capacitance of the sample can be measured in the same apparatus along with the other testing. 7) Visible light can be used to investigate conduction by electrons (or holes) emitted from shallow trapping levels. The qualitative physics of such processes in solid dielectrics has long been known, and instrumentation is developed here for measuring the effects in practical spacecraft charging applications.
TL;DR: In this paper, ASER on SOI and BULK SRAMs for the 250-, 130-, and 90-nm technologies are modeled with Monte Carlo simulations to predict SER to the 65-nm node.
Abstract: This paper presents experimental ASER on SOI and BULK SRAMs for the 250-, 130-, and 90-nm technologies. The key parameters controlling soft error rate (SER) in these technologies are modeled with Monte Carlo simulations to predict SER to the 65-nm node.
TL;DR: In this paper, a linear quadratic Gaussian with loop transfer recovery (LQG/LTR) at the plant output was used to improve the temperature response performance of nuclear reactors via modifying the embedded classical controller reference signal.
Abstract: State feedback assisted classical (SFAC) control has been developed to improve the temperature response performance of nuclear reactors via modifying the embedded classical controller reference signal. This is done by means of an outermost state feedback controller. A linear quadratic Gaussian with loop transfer recovery (LQG/LTR) at the plant output seems a good candidate for the state feedback loop of SFAC structure, but it ends up in a closed loop system with tightly controlled power. To pay more attention to temperature responses, this paper presents the results of using LQG/LTR at the plant input in SFAC structure. We impose a minor change for considering, to some extent, the variation of system poles (and hence its speed) due to linearization of the nonlinear plant in equilibrium conditions other than the design power. The results are compared to an existing LQG controller with LTR at the plant output. Sensitivity of dominant closed loop poles and nonlinear simulations are used for demonstration and comparison.
TL;DR: In this article, the evolution of radiation effects understanding in infrared detector technology, charge coupled devices, and active pixel sensors is summarized and a discussion of key radiation effects developments and a view of the future of the technologies from a radiation effects perspective.
Abstract: Photonic imagers are being increasingly used in space systems, where they are exposed to the space radiation environment. Unique properties of these devices require special considerations for radiation effects. This paper summarizes the evolution of radiation effects understanding in infrared detector technology, charge coupled devices, and active pixel sensors. The paper provides a discussion of key radiation effects developments and a view of the future of the technologies from a radiation effects perspective.
TL;DR: In this article, high-electron mobility transistors and corresponding unprocessed material were characterized as a function of 1.8 MeV proton fluence and showed degradation of the electrical contacts at low fluences and degradation of channel properties for higher fluences.
Abstract: We have characterized high-electron mobility transistors and corresponding unprocessed material as a function of 1.8 MeV proton fluence. Electrical data shows degradation of the electrical contacts at low fluences (10/sup 11/-10/sup 14/ p/sup +//cm/sup 2/) and degradation of the channel properties for higher fluences. In conjunction with the electrical data, cathodoluminescence and secondary-ion mass spectrometry results suggest mechanisms for the higher fluence degradation.
TL;DR: In this paper, the concentrations of radiation-induced oxide-trap and interface-trap charge are separated using midgap and dual-transistor charge separation analysis techniques, which is shown to be especially well suited for charge separation of pseudo-MOSFETs.
Abstract: Pseudo-metal-oxide-semiconductor (MOS) silicon-on-insulator (SOI) transistors are used to study the total ionizing dose response of buried oxides. The concentrations of radiation-induced oxide-trap and interface-trap charge are separated using midgap and dual-transistor charge separation analysis techniques. Dual-transistor analysis is shown to be especially well suited for charge separation of pseudo-MOSFETs (/spl Psi/-MOSFETs) because the electron conduction mode of this simple point-contact device resembles an nMOS transistor, and the hole conduction mode resembles a pMOS transistor. That this is a single device ensures that the dual-transistor assumption of equal oxide-trap charge in otherwise identical n and pMOS transistors is satisfied automatically. Both electron and hole conduction current-voltage (I-V) traces must extrapolate to a common, physically realistic midgap voltage; this is employed as a test for the self-consistency of /spl Psi/-MOSFET data. Charge separation performed using midgap and dual-transistor analyses show good agreement for the devices employed in this paper.
TL;DR: In this article, the chalcogenide material used for phase-change applications in rewritable optical storage (Ge/sub 2/Sb/Sub 2/Te/sub 5/) has been integrated with a 0.5/spl mu/m radiation-hardened CMOS process to produce 64-Kbit memory arrays.
Abstract: The chalcogenide material used for phase-change applications in rewritable optical storage (Ge/sub 2/Sb/sub 2/Te/sub 5/) has been integrated with a 0.5-/spl mu/m radiation-hardened CMOS process to produce 64-Kbit memory arrays. On selected arrays, electrical testing demonstrated up to 100% memory cell yield, 100-ns programming and read speeds, and write currents as low as 1 mA/bit. Devices functioned normally from -55/spl deg/C to 125/spl deg/C. Write/read endurance has been demonstrated to 1/spl times/10/sup 8/ before first bit failure. Total ionizing dose (TID) testing to 2 Mrad(Si) showed no degradation of chalcogenide memory element, but it identified a write current generator circuit degradation specific to the test chip, which can be easily corrected in the next generation of array and product. Static single-event effects (SEE) testing showed no effect to an effective linear energy transfer (LET/sub EFF/) of 98 MeV/mg/cm/sup 2/. Dynamic SEE testing showed no latchup or single-event gate rupture (SEGR) to an LET/sub EFF/ of 123 MeV/mg/cm/sup 2/. Two sensitive circuits, neither containing chalcogenide elements, and both with small error cross sections, were identified. The sense amp appears sensitive to transients when reading the high-resistance state. The write driver circuit may be falsely activated during a read cycle, resulting in a reprogrammed bit. Radiation results show no degradation to the hardened CMOS or effects that can be attributed to the phase-change material.
TL;DR: In this paper, the authors report on enhanced susceptibility for neutron-induced soft errors from accelerated testing of static random access memories (SRAMs), performed at Los Alamos National Laboratory.
Abstract: We report on enhanced susceptibility for neutron-induced soft errors from accelerated testing of static random access memories (SRAMs), performed at Los Alamos National Laboratory. This enhancement is per bit of memory.
TL;DR: In this article, the effective linear energy transfer of heavy nuclear recoils (Z/spl ges/3) produced by proton interactions in silicon are calculated for incident proton energies of 50, 100, 200, and 500 MeV.
Abstract: The effective linear energy transfer of heavy nuclear recoils (Z/spl ges/3) produced by proton interactions in silicon are calculated for incident proton energies of 50, 100, 200, and 500 MeV. The LAHET intranuclear cascade and evaporation code is used to obtain the energy spectra of the nuclear recoils and a Monte Carlo code is then used to follow these recoils as they stop in silicon. The total LET spectra at an observation layer located at a depth of 100 microns in the silicon is calculated. The effectiveness of each proton energy level for single event effects screening of microelectronics is evaluated.