SEU Characterization of Three Successive Generations of COTS SRAMs at Ultralow Bias Voltage to 14.2 MeV Neutrons

This paper presents a SEU sensitivity characterization at ultra-low bias voltage of three generations of COTS SRAMs manufactured in 130 nm, 90 nm and 65 nm CMOS processes. For this purpose, radiation tests with 14.2 MeV neutrons were performed for SRAM power supplies ranging from 0.5 V to 3.15 V. The experimental results yielded clear evidences of the SEU sensitivity increase at very low bias voltages. These results have been cross-checked with predictions issued from the modeling tool MUlti-SCAles Single Event Phenomena Predictive Platform (MUSCA-SEP3). Large-scale SELs and SEFIs, observed in the 90-nm and 130-nm SRAMs respectively, are also presented and discussed

Statistical Deviations from the Theoretical only-SBU Model to Estimate MCU rates in SRAMs

This paper addresses a well-known problem that occurs when memories are exposed to radiation: the determination if a bitflip is isolated or if it belongs to a multiple event. As it is unusual to know the physical layout of the memory, this paper proposes to evaluate the statistical properties of the sets of corrupted addresses and to compare the results with a mathematical prediction model where all of the events are SBUs. A set of rules easy to implement in common programming languages can be iteratively applied if anomalies are observed, thus yielding a classification of errors quite closer to reality (more than 80% accuracy in our experiments)

Experimental and Analytical Study of the Responses of Nanoscale Devices to Neutrons Impinging at Various Incident Angles

In harsh radiation environments, it is well known that the angle of incidence of impinging particles against the surface of the operating devices has significant effects on their sensitivity. This article discusses the sensitivity underestimations that are made if particle isotropy is not taken into account, by means of an analytical study made with a single-event upset predictive platform. To achieve this goal, experimental results carried out with a commercial-off-the-shelf (COTS) bulk 130-nm nonvolatile static random access memory (SRAM) for various incident angles on 14.2 MeV neutrons are first discussed. Then, a modeling tool called multiscales single-event phenomena predictive platform (MUSCA-SEP3) is used to predict the sensitivity of this memory under the same environmental conditions. Predictions and experimental results will be cross-checked, and therefore, the feasibility of this tool will be demonstrated for testing any other incident angle. Finally, an isotropic environment and an XY SRAM array will be emulated with MUSCA in order to demonstrate that the asymmetrical cross sections that were observed experimentally for various incidence angles are due to the underlying asymmetry of the metalization/passivation layers within the device with respect to its active silicon. Conclusions will finally be drawn as for the importance of taking into account particle isotropy in radiation-ground tests

Testing a fault tolerant mixed-signal design under TID and heavy ions

This work presents results of three distinctradiation tests performed upon a fault tolerant data acqui-sition system comprising a design diversity redundancytechnique. The first and second experiments are Total Ion-izing Dose (TID) essays, comprising gamma and X-rayirradiations. The last experiment considers single eventeffects, in which two heavy ion irradiation campaignsare carried out. The case study system comprises threeanalog-to-digital converters and two software-based vot-ers, besides additional software and hardware resourcesused for controlling, monitoring and memory manage-ment. The applied Diversity Triple Modular Redundancy(DTMR) technique, comprises different levels of diversity(temporal and architectural). The circuit was designed ina programmable System-on-Chip (PSoC), fabricated in a130nm CMOS technology process. Results show that thetechnique may increase the lifetime of the system underTID if comparing with a non-redundant implementation.Considering the heavy ions experiments the system wasproved effective to tolerate 100% of the observed errorsoriginated in the converters, while errors in the process-ing unit present a higher criticality. Critical errors occur-ring in one of the voters were also observed. A secondheavy ion campaign was then carried out to investigatethe voters reliability, comparing the the dynamic cross sec-tion of three different software-based voter schemes im-plemented in the considered PSoC

Evaluation of a COTS 65-nm SRAM Under 15 MeV Protons and 14 MeV Neutrons at Low VDD

This article presents an experimental study on the sensitivity of a commercial-off-the-shelf (COTS) bulk 65-nm static random access memory (SRAM) under 15.6 MeV proton irradiation when powered up at ultralow bias voltage. Tests were run on standby and while reading the memory. Results show obvious evidence indicating that decreasing the bias voltage below 1 V exponentially increases the number of observed errors. Single-bit upsets (SBUs) and multiple-cell upsets (MCUs) (mostly with vertical shapes according to the manufacturers' layout) are reported and their behavior is analyzed in this article. Predictions on the single-event upset (SEU) sensitivity obtained with the multiscales single-event phenomena predictive platform (MUSCA-SEP3) modeling tool are also provided and compared with the experimental results. These are also compared with 14.2 MeV neutrons, showing a significant difference in the cross sections for both irradiation sources. Total ionizing dose (TID) tests and GEANT4 simulations were also run to check for the reason behind the difference in the cross section between these two particles

Radiation Study of a 4Mbit Ferroelectric RAM for Space Applications

International audienceWe present a Heavy Ion radiation study for a ultra low power non volatile 4Mbit ferroelectric memory(FRAM) for space applications manufactured on a 130nm domestic CMOS technology node. The radiation summary includes SEU data from Heavy Ions static as well as dynamic stress tests. The FRAM device meets the space level upset criteria for static device stress, but requires additional system mitigation for dynamic device stress

Statistical anomalies of bitflips in SRAMs to discriminate MCUs from SEUs

This paper presents an approach to discern MCUs from SEUs in SRAM memories. Experiments involving radiation tests with 14-MeV neutrons on two successive generations (130 and 90 nm) of Cypress devices are presented

Effects of Thermal Neutron Irradiation on a Self-Refresh DRAM

In this study, static and dynamic test methods were used to define the response of a self-refresh DRAM under thermal neutron irradiation. The neutron-induced failures were investigated and characterized by event cross-sections, soft-error rate and bitmaps evaluations, leading to an identification of permanent and temporarily stuck cells, block errors, and singlebit upsets

Investigating the Impact of Radiation-Induced Soft Errors on the Reliability of Approximate Computing Systems

Approximate Computing (AxC) is a well-known paradigm able to reduce the computational and power overheads of a multitude of applications, at the cost of a decreased accuracy. Convolutional Neural Networks (CNNs) have proven to be particularly suited for AxC because of their inherent resilience to errors. However, the implementation of AxC techniques may affect the intrinsic resilience of the application to errors induced by Single Events in a harsh environment. This work introduces an experimental study of the impact of neutron irradiation on approximate computing techniques applied on the data representation of a CNN.nonPeerReviewe