Soft-Error Rate of Advanced SRAM Memories: Modeling and Monte Carlo Simulation

International audienc

Reliability Assessment of Nanoscale System on Chip Depending on Neturon Irradiation

The atmospheric neutron poses a serious hazard to nanoscale electronics reliability. Spallation neutron irradiations on a nanoscale system on chip (SoC) were conducted applying the China Spallation Neutron Source (CSNS), and the results were compared and analyzed using Monte Carlo simulation. The contribution from thermal neutron on the SoC single event effect (SEE) was analyzed. Analysis indicated the SoC atmospheric neutron SEE vulnerability can be reduced by 44.4% if the thermal neutron was absorbed. The influences of the B and Hf elements on the SEEs were evaluated, too. It can be concluded that 10 B interacting with thermal neutron is the reason for thermal neutron inducing SEE in the SoC. Although the Hf element has no contribution to the 28 nm SoC atmospheric neutron SEE cross section, it increases the total dose risk 5 times during atmospheric neutron irradiation

プレーナーガタオヨビフィンフェットガタエスラムニオケルチジョウホウシャセンキインシングルイベントアップセットニカンスルジッケンテキケンキュウ

T. Kato et al., "Muon-Induced Single-Event Upsets in 20-nm SRAMs: Comparative Characterization With Neutrons and Alpha Particles," in IEEE Transactions on Nuclear Science, vol. 68, no. 7, pp. 1436-1444, July 2021, doi: 10.1109/TNS.2021.3082559

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

International audienc

Characterizing the influence of neutron fields in causing single-event effects using portable detectors

The malfunction of semiconductor devices caused by cosmic rays is known as Single Event Effects(SEEs). In the atmosphere, secondary neutrons are the dominant particles causing this effect. The neutron flux density in atmosphere is very low. For a good statistical certainty, millions of device hours are required to measure the event rate of a device in the natural environment. Event rates obtained in such testings are accurate. To reduce the cost and time of getting the event rate, a device is normally taken to artificial accelerated neutron beams to measure its sensitivity to neutrons. Comparing the flux density of the beam and the flux density of a location in the atmosphere, the real time event rate can be predicted by the event rate obtained. This testing method was standardized as the neutron accelerated soft error rate (ASER) testing in JEDEC JESD89A standard. However, several life testings indicated that the neutron flux density predictions given by the accelerated testings can have large errors. Up to a factor of 2 discrepancy was reported in the literature. One of the major error sources is the equivalence of the absolute neutron flux density in the atmosphere and in accelerated beam. This thesis proposes an alternative accelerated method of predicting the real-time neutron error rate by using proxy devices. This method can avoid the error introduced by the uncertainty in the neutron flux density. The Imaging Single Event Effect Monitor (ISEEM) is one of the proxy devices. It is the instrument originally developed by Z. Török and his co-workers in the University of Central Lancashire. A CCD was used as the sensitive element to detect neutrons. A large amount of data sets acquired by Török were used in this work. A re-engineered ISEEM has been developed in this work to improve ISEEM performance in life testings. Theoretical models have been developed to analyze the response of ISEEM in a wide range of neutron facilities and natural environment. The agreement of the measured and calculated cross-sections are within the error quoted by facilities. Because of the alpha contamination and primary proton direct ionization effects, performance of ISEEM in life testings appeared to be weak

Design of Soft Error Robust High Speed 64-bit Logarithmic Adder

Continuous scaling of the transistor size and reduction of the operating voltage have led to a significant performance improvement of integrated circuits. However, the vulnerability of the scaled circuits to transient data upsets or soft errors, which are caused by alpha particles and cosmic neutrons, has emerged as a major reliability concern. In this thesis, we have investigated the effects of soft errors in combinational circuits and proposed soft error detection techniques for high speed adders. In particular, we have proposed an area-efficient 64-bit soft error robust logarithmic adder (SRA). The adder employs the carry merge Sklansky adder architecture in which carries are generated every 4 bits. Since the particle-induced transient, which is often referred to as a single event transient (SET) typically lasts for 100~200 ps, the adder uses time redundancy by sampling the sum outputs twice. The sampling instances have been set at 110 ps apart. In contrast to the traditional time redundancy, which requires two clock cycles to generate a given output, the SRA generates an output in a single clock cycle. The sampled sum outputs are compared using a 64-bit XOR tree to detect any possible error. An energy efficient 4-input transmission gate based XOR logic is implemented to reduce the delay and the power in this case. The pseudo-static logic (PSL), which has the ability to recover from a particle induced transient, is used in the adder implementation. In comparison with the space redundant approach which requires hardware duplication for error detection, the SRA is 50% more area efficient. The proposed SRA is simulated for different operands with errors inserted at different nodes at the inputs, the carry merge tree, and the sum generation circuit. The simulation vectors are carefully chosen such that the SET is not masked by error masking mechanisms, which are inherently present in combinational circuits. Simulation results show that the proposed SRA is capable of detecting 77% of the errors. The undetected errors primarily result when the SET causes an even number of errors and when errors occur outside the sampling window

On the Evaluation of SEEs on Open-Source Embedded Static RAMs

3Static RAM modules are widely adopted in high performance systems. Single Event Effects (SEEs) resilient memories are required in many embedded systems applied in automotive and aerospace applications to increase their overall resiliency against SEEs. The current SEE resilient SRAM modules are obtained by applying radiation-hardened by design solutions which leads to elevated area overhead and difficulty to tune the resiliency capability with respect to the particle’s radiation profile. To overcome these limitations, we propose a methodology for the analysis and mitigation of embedded SRAMs generated by the OpenRAM memory compiler. A technology-oriented radiation analysis tool is presented to support the interaction of the charged radiation particles with the SRAM layout and depict the sensitive transistors of the SRAM memory. A selective duplication of the sensitive transistors has been applied to the 6T-SRAM cell designed at the layout level. The designed cell is included in the OpenRAM compiler and used to generate a mitigated 8Kb SRAM-bank. We evaluated the SEEs sensitivity by comparative simulation-based radiation analysis observing a reduction more than 6 times with respect to the original 6T-SRAM cell for the SEE sensitivity at high energy heavy ions particles, with negligible degradation of operations margins and power consumption and area overhead of less than ̴4%.partially_openopenAzimi, Sarah; De Sio, Corrado; Sterpone, LucaAzimi, Sarah; De Sio, Corrado; Sterpone, Luc

Characterizing the influence of neutron fields in causing single-event effects using portable detectors

The malfunction of semiconductor devices caused by cosmic rays is known as Single Event Effects(SEEs). In the atmosphere, secondary neutrons are the dominant particles causing this effect. The neutron flux density in atmosphere is very low. For a good statistical certainty, millions of device hours are required to measure the event rate of a device in the natural environment. Event rates obtained in such testings are accurate. To reduce the cost and time of getting the event rate, a device is normally taken to artificial accelerated neutron beams to measure its sensitivity to neutrons. Comparing the flux density of the beam and the flux density of a location in the atmosphere, the real time event rate can be predicted by the event rate obtained. This testing method was standardized as the neutron accelerated soft error rate (ASER) testing in JEDEC JESD89A standard. However, several life testings indicated that the neutron flux density predictions given by the accelerated testings can have large errors. Up to a factor of 2 discrepancy was reported in the literature. One of the major error sources is the equivalence of the absolute neutron flux density in the atmosphere and in accelerated beam. This thesis proposes an alternative accelerated method of predicting the real-time neutron error rate by using proxy devices. This method can avoid the error introduced by the uncertainty in the neutron flux density. The Imaging Single Event Effect Monitor (ISEEM) is one of the proxy devices. It is the instrument originally developed by Z. Török and his co-workers in the University of Central Lancashire. A CCD was used as the sensitive element to detect neutrons. A large amount of data sets acquired by Török were used in this work. A re-engineered ISEEM has been developed in this work to improve ISEEM performance in life testings. Theoretical models have been developed to analyze the response of ISEEM in a wide range of neutron facilities and natural environment. The agreement of the measured and calculated cross-sections are within the error quoted by facilities. Because of the alpha contamination and primary proton direct ionization effects, performance of ISEEM in life testings appeared to be weak.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Study of Layout Techniques in Dynamic Logic Circuitry for Single Event Effect Mitigation

Dynamic logic circuits are highly suitable for high-speed applications, considering the fact that they have a smaller area and faster transition. However, their application in space or other radiation-rich environments has been significantly inhibited by their susceptibility to radiation effects. This work begins with the basic operations of dynamic logic circuits, elaborates upon the physics underlying their radiation vulnerability, and evaluates three techniques that harden dynamic logic from the layout: drain extension, pulse quenching, and a proposed method. The drain extension method adds an extra drain to the sensitive node in order to improve charge sharing, the pulse quenching scheme utilizes charge sharing by duplicating a component that offsets the transient pulse, and the proposed technique takes advantage of both. Domino buffers designed using these three techniques, along with a conventional design as reference, were modeled and simulated using a 3D TCAD tool. Simulation results confirm a significant reduction of soft error rate in the proposed technique and suggest a greater reduction with angled incidence. A 130 nm chip containing designed buffer and register chains was fabricated and tested with heavy ion irradiation. According to the experiment results, the proposed design achieved 30% soft error rate reduction, with 19%, 20%, and 10% overhead in speed, power, and area, respectively