Radiation and Reliability Concerns for Modern Nonvolatile Memory Technology

Commercial nonvolatile memory technology is attractive for space applications, but radiation issues are serious concerns. In addition, we discuss combined radiation/reliability concerns which are only beginning to be addressed

Investigation of Current Spike Phenomena During Heavy Ion Irradiation of NAND Flash Memories

A series of heavy ion and laser irradiations were performed to investigate previously reported current spikes in flash memories. High current events were observed, however, none matches the previously reported spikes. Plausible mechanisms are discussed

Current Single Event Effects Compendium of Candidate Spacecraft Electronics for NASA

We present the results of single event effects (SEE) testing and analysis investigating the effects of radiation on electronics. This paper is a summary of test results

Computational Modeling and Monte Carlo Simulation of Soft Errors in Flash Memories

International audienc

Recent Single Event Effects Compendium of Candidate Electronics for NASA Space Systems

We present the results of single event effects (SEE) testing and analysis investigating the effects of radiation on electronics. This paper is a summary of test results

Statistical analysis of Total Ionizing Dose response in 25-nm NAND Flash memory

Variabilità degli errori, ovvero bit flip, dovuti alla dose totale ionizzante (TID) in memorie Flash SLC da 25 nm. Più di 1 Terabit di celle è stato esposto a raggi gamma da Co-60 e sono stati misurati gli errori indotti dalla radiazione ionizzante. L'obiettivo della tesi è stato lo studio del comportamento delle memorie Flash nello spazio e prevederne l’affidabilità.ope

TID and SEE Response of Advanced 4G NAND Flash Memories

Abstract-

Design, implementation and testing of SRAM based neutron detectors

Neutrons of thermal and high energies can change the value of a bit stored in a Static Random Access Memory (SRAM) memory chip. The effect is non destructive and linearly dependent on the amount of incoming particles, which makes it exploitable for use as a neutron detector. Detection is done by writing a known pattern to the memory and continuously reading it back checking for wrong values. As the SRAM memory is immune to gamma radiation it is ideal for use in for instance medical linear accelerators for detection of neutron dose to a patient. The intention of this work has been twofold: (1) Testing of different SRAM devices of different bit-sizes, manufacturers, feature sizes and voltages for their sensitivity to neutrons of different energies from thermal to high energies. (2) Design and implement detector hardware, firmware and its accompanying readout system for successful use in irradiation testing. The work has been done in close collaboration with Eivind Larsen, whose main contributions has been related to the nuclear physics aspect of the work in addition to arrangements in regard to beam setup and experimentation. Testing have been done at the Physikalisch-Technische Bundesanstalt (PTB) facility in Braunschweig Germany in a quasi-monochromatic neutron beam of 5:8MeV, 8:5MeV and 14:8MeV, finding a dependence of the sensitivity on the energy. In addition there have been testing conducted in the high energy hadron field at CERF at CERN, finding that by using the results from the other experiments an estimated range of the saturation cross section could be determined. Testing was also conducted at two occasions in the 29MeV proton beam at Oslo Cyclotron Laboratory (OCL) in Oslo Norway, where it was found that the detector could be used as a reference detector for beam monitoring and for beam profile characterization. The cross sections of the detectors were found to be comparable to the 14:8MeV cross section found at PTB. Thermal neutron testing of the devices was done in the thermal neutron field of the nuclear reactor at Institute for Energy Technology (IFE) at Kjeller Norway. All the devices were found to be sensitive to the field. Detector electronics, adapted to the different devices, has been built which can withstand the same radiation as the memory device without malfunctioning. There has been a focus on using Commercial Off The Shelf (COTS) components for reducing the total cost of the detector to about 100-200$US. The use of COTS SRAM memory devices also simplifies the reproducibility and availability of spares. The detector currently uses a two way communication between the detector and iv Abstract the readout computer over two pair of cables reducing the amount of cabling needed for experiments. The detectors can be connected to the communication link in a bus fashion, currently enabling a total of 14 detectors to be tested simultaneously from 100m away, over the same cable. Single Event Latch-up (SEL) and problems with irregular count rate of SRAMs created in the 90nm fabrication node has created problems during testing. Some solutions and techniques to mitigate these in hardware and firmware are presented in this work.Master i FysikkMAMN-PHYSPHYS39

Investigation of radiation-hardened design of electronic systems with applications to post-accident monitoring for nuclear power plants

This research aims at improving the robustness of electronic systems used-in high level radiation environments by combining with radiation-hardened (rad-hardened) design and fault-tolerant techniques based on commercial off-the-shelf (COTS) components. A specific of the research is to use such systems for wireless post-accident monitoring in nuclear power plants (NPPs). More specifically, the following methods and systems are developed and investigated to accomplish expected research objectives: analysis of radiation responses, design of a radiation-tolerant system, implementation of a wireless post-accident monitoring system for NPPs, performance evaluation without repeat physical tests, and experimental validation in a radiation environment. A method is developed to analyze ionizing radiation responses of COTS-based devices and circuits in various radiation conditions, which can be applied to design circuits robust to ionizing radiation effects without repeated destructive tests in a physical radiation environment. Some mathematical models of semiconductor devices for post-irradiation conditions are investigated, and their radiation responses are analyzed using Technology Computer Aided Design (TCAD) simulator. Those models are then used in the analysis of circuits and systems under radiation condition. Based on the simulation results, method of rapid power off may be effectively to protect electronic systems under ionizing radiation. It can be a potential solution to mitigate damages of electronic components caused by radiation. With simulation studies of photocurrent responses of semiconductor devices, two methods are presented to mitigate the damages of total ionizing dose: component selection and radiation shielding protection. According to the investigation of radiation-tolerance of regular COTS components, most COTS-based semiconductor components may experience performance degradation and radiation damages when the total dose is greater than 20 K Rad (Si). A principle of component selection is given to obtain the suitable components, as well as a method is proposed to assess the component reliability under radiation environments, which uses radiation degradation factors, instead of the usual failure rate data in the reliability model. Radiation degradation factor is as the input to describe the radiation response of a component under a total radiation dose. In addition, a number of typical semiconductor components are also selected as the candidate components for the application of wireless monitoring in nuclear power plants. On the other hand, a multi-layer shielding protection is used to reduce the total dose to be less than 20 K Rad (Si) for a given radiation condition; the selected semiconductor devices can then survive in the radiation condition with the reduced total dose. The calculation method of required shielding thickness is also proposed to achieve the design objectives. Several shielding solutions are also developed and compared for applications in wireless monitoring system in nuclear power plants. A radiation-tolerant architecture is proposed to allow COTS-based electronic systems to be used in high-level radiation environments without using rad-hardened components. Regular COTS components are used with some fault-tolerant techniques to mitigate damages of the system through redundancy, online fault detection, real-time preventive remedial actions, and rapid power off. The functions of measurement, processing, communication, and fault-tolerance are integrated locally within all channels without additional detection units. A hardware emulation bench with redundant channels is constructed to verify the effectiveness of the developed radiation-tolerant architecture. Experimental results have shown that the developed architecture works effectively and redundant channels can switch smoothly in 500 milliseconds or less when a single fault or multiple faults occur. An online mechanism is also investigated to timely detect and diagnose radiation damages in the developed redundant architecture for its radiation tolerance enhancement. This is implemented by the built-in-test technique. A number of tests by using fault injection techniques have been carried out in the developed hardware emulation bench to validate the proposed detection mechanism. The test results have shown that faults and errors can be effectively detected and diagnosed. For the developed redundant wireless devices under given radiation dose (20 K Rad (Si)), the fault detection coverage is about 62.11%. This level of protection could be improved further by putting more resources (CPU consumption, etc.) into the function of fault detection, but the cost will increase. To apply the above investigated techniques and systems, under a severe accident condition in a nuclear power plant, a prototype of wireless post-accident monitoring system (WPAMS) is designed and constructed. Specifically, the radiation-tolerant wireless device is implemented with redundant and diversified channels. The developed system operates effectively to measure up-to-date information from a specific area/process and to transmit that information to remote monitoring station wirelessly. Hence, the correctness of the proposed architecture and approaches in this research has been successfully validated. In the design phase, an assessment method without performing repeated destructive physical tests is investigated to evaluate the radiation-tolerance of electronic systems by combining the evaluation of radiation protection and the analysis of the system reliability under the given radiation conditions. The results of the assessment studies have shown that, under given radiation conditions, the reliability of the developed radiation-tolerant wireless system can be much higher than those of non-redundant channels; and it can work in high-level radiation environments with total dose up to 1 M Rad (Si). Finally, a number of total dose tests are performed to investigate radiation effects induced by gamma radiation on distinct modern wireless monitoring devices. An experimental setup is developed to monitor the performance of signal measurement online and transmission of the developed distinct wireless electronic devices directly under gamma radiator at The Ohio State University Nuclear Reactor Lab (OSU-NRL). The gamma irradiator generates dose rates of 20 K Rad/h and 200 Rad/h on the samples, respectively. It was found that both measurement and transmission functions of distinct wireless measurement and transmission devices work well under gamma radiation conditions before the devices permanently damage. The experimental results have also shown that the developed radiation-tolerant design can be applied to effectively extend the lifespan of COTS-based electronic systems in the high-level radiation environment, as well as to improve the performance of wireless communication systems. According to testing results, the developed radiation-tolerant wireless device with a shielding protection can work at least 21 hours under the highest dose rate (20 K Rad/h). In summary, this research has addressed important issues on the design of radiation-tolerant systems without using rad-hardened electronic components. The proposed methods and systems provide an effective and economical solution to implement monitoring systems for obtaining up-to-date information in high-level radiation environments. The reported contributions are of significance both academically and in practice