Single Event Upset Cross Section Research Articles

A calculation method to estimate single event upset cross section

We calculate single event effect cross-section with a new general method based on the evaluation of the current collected by an electrode and the ability of the cell to dissipate the charge involved in the event. Basically, a part of the charge deposited by an ionizing particle is collected, and a part of this latest is dissipated during the transient. The approach allows explaining experimental cross section obtained for heavy ions irradiations. Moreover, the use of heavy ions experimental results allow predicting the single event crosses section for protons.

Ionizing radiation effect on single event upset sensitivity of ferroelectric random access memory

The impact of ionizing radiation effect on single event upset (SEU) sensitivity of ferroelectric random access memory (FRAM) is studied in this work. The test specimens were firstly subjected to 60Co γ-ray and then the SEU evaluation was conducted using 209Bi ions. As a result of TID-induced fatigue-like and imprint-like phenomena of the ferroelectric material, the SEU cross sections of the post-irradiated devices shift substantially. Different trends of SEU cross section with elevated dose were also found, depending on whether the same or complementary test pattern was employed during the TID exposure and the SEU measurement.

Total Ionizing Dose Influence on the Single-Event Upset Sensitivity of 130-nm PD SOI SRAMs

Effect of total ionizing dose (TID) on single-event upset (SEU) hardness of 130 nm partially depleted (PD) silicon-on-insulator (SOI) static random access memories (SRAMs) is investigated in this paper. The measurable synergistic effect of TID on SEU sensitivity of 130-nm PD SOI SRAM was observed in our experiment, even though that is far less than micrometer and submicrometer devices. Moreover, SEU cross section after TID irradiation has no dependence on the data pattern that was applied during TID exposure: SEU cross sections are characterized by TID data pattern and its complement data pattern are decreased consistently rather than a preferred state and a nonpreferred state as micrometer and sub-micrometer SRAMs. The memory cell test structure allowing direct measurement of static noise margin (SNM) under standby operation was designed using identical memory cell layout of SRAM. Direct measurement of the memory cell SNM shows that both data sides’ SNM is decreased by TID, indicating that SEU cross section of 130-nm PD SOI SRAM will be increased by TID. And, the decreased SNM is caused by threshold shift in memory cell transistors induced by “radiation-induced narrow channel effect.”

Impact of energy straggle on proton-induced single event upset test in a 65-nm SRAM cell**Project supported by the National Natural Science Foundation of China (Grant Nos. 11690041 and 11675233).

This paper presents a simulation study of the impact of energy straggle on a proton-induced single event upset (SEU) test in a commercial 65-nm static random access memory cell. The simulation results indicate that the SEU cross sections for low energy protons are significantly underestimated due to the use of degraders in the SEU test. In contrast, using degraders in a high energy proton test may cause the overestimation of the SEU cross sections. The results are confirmed by the experimental data and the impact of energy straggle on the SEU cross section needs to be taken into account when conducting a proton-induced SEU test in a nanodevice using degraders.

Comparison of single-event upset generated by heavy ion and pulsed laser

Single-event upset (SEU) is investigated using heavy ion and pulsed laser. The measured SEU cross sections of D and DICE flip-flops are compared. Measurement results indicate pulsed laser is capable of inducing similar SEU to those induced by heavy ion. 3D-TCAD simulation is performed to investigate the factors to impact pulsed laser induced SEU. Simulation results show that the beam spot size significantly impacts SEU cross sections in both low and high laser energy while the variation of the equivalent LET only impacts SEU cross sections in the low laser energy.

Low energy proton induced single event upset in 65 nm DDR and QDR commercial SRAMs

The single event upset (SEU) response of 65nm commercial double data rate static random access memory (SRAM) and quad data rate SRAM was investigated by using proton beams with energies in the range of 0.15MeV to 8.0MeV. Experimental results show that a significant number of SEU occurrences can be triggered when the energy of incident proton is below 1MeV. For the low energy protons, the SEU cross section measured in these SRAMs was found to increase with increasing proton energy, attaining a peak value, and then decreases as the proton energy was further increased. While in case of quad data rate SRAMs, it seems that they are more sensitive to SEU occurrences as compared with double data rate SRAMs. The bias voltage and data pattern dependence on SEU cross section induced by the low energy protons were also investigated in this work. In addition, the over-layer thickness of the SRAMs and the impact of degrader use in proton induced SEU test were also analyzed in detail. Monte Carlo simulations results indicate that the use of degrader in case of low energy proton induced SEU test results in a significant reduction of the SEU cross section.

A simple analytical model of single-event upsets in bulk CMOS

During the last decade, multiple new methods of single event upset (SEU) rate prediction for aerospace systems have been proposed. Despite different models and approaches being employed in these methods, they all share relatively high usage complexity and require information about a device that is not always available to an end user.This work presents an alternative approach to estimating SEU cross-section as a function of linear energy transfer (LET) that can be further developed into a method of SEU rate prediction. The goal is to propose a simple, yet physics-based, approach with just two parameters that can be used even in situations when only a process node of the device is known. The developed approach is based on geometrical interpretation of SEU cross-section and an analytical solution to the diffusion problem obtained for a simplified IC topology model. A good fit of the model to the experimental data encompassing 7 generations of SRAMs is demonstrated.

Single event upset characteristics and physical mechanism for nanometric SOI SRAM induced by space energetic ions

Based on Monte-Carlo method, the characteristics and physical mechanisms for deposited-energy spectra in sensitive volume (SV), single event upset cross sections, and on-orbit error rates in 65-32 nm silicon-on-insulator static random access memory (SOI SRAM) devices induced by space energetic ions are investigated. Space ions on geostationary earth orbit exhibit a flux peak at an energy point of about 200 MeV/n. In consequence, the single event response of nanometric SOI SRAMs under 200 MeV/n heavy ions is studied in detail. The results show that 200 MeV/n space ions exhibit the large straggling of deposited-energy in the device SV with thickness ranging from 60 nm to 40 nm, which causes the single event upsets to occur in the sub-LETmth region. The device SV can only partially collect the electron-hole pairs in the single ion track with a wide distribution of secondary electrons. As a result, the maximum and average deposited-energy in the SV decrease by 25% and 33.3%, respectively. Further, the single event upset probability decreases and the on-orbit error rate decreases by about 80%. With the downscaling of feature size, the per-bit saturated cross sections and on-orbit error rates of nanometric SOI SRAM devices decrease dramatically. The phenomenon of constant-increasing single event upset cross section with higher ion linear energy transfer (LET) is not observed, owing to the fact that (a) the density of electron-hole pairs in the track of 200 MeV/n space ion is relatively low and (b) the SOI device has thin sensitive volume, which results in the fact that the secondary-electron effect cannot upset nearby sensitive cells. Besides, it is found that the direct-ionization process of trapped protons leads to an increase of on-orbit error rate of 65 nm SOI SRAM by one to two orders of magnitude.

Effects of Threshold Voltage Variations on Single-Event Upset Response of Sequential Circuits at Advanced Technology Nodes

Threshold voltage (V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">T</sub> ) of transistors plays an important role in single-event upsets (SEU) and system power consumption. Effect of V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">T</sub> on single-event upsets can be very different for different technologies. SEU responses of flip-flops and logic circuits in 20-nm bulk planar and 16-nm bulk FinFET technologies with different V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">T</sub> options are investigated. Results show that for the 20-nm bulk planar technology, the design with the highest threshold voltage among all V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">T</sub> options shows the lowest SEU cross-section for alpha particle irradiation. For the 16-nm FinFET technology, the option with the highest threshold voltage shows the highest SEU cross-section. As frequency increases, the SEU cross-section of the highest V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">T</sub> design shows a faster increase and a larger curve slope due to increased single-event transient (SET) pulse width compared to the lower V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">T</sub> designs for the 16-nm FinFET technology node.

Estimating Single-Event Logic Cross Sections in Advanced Technologies

Reliable estimation of logic single-event upset (SEU) cross section is becoming increasingly important for predicting the overall soft error rate. As technology scales and single-event transient (SET) pulse widths shrink to widths on the order of the setup-and-hold time of flip-flops, the probability of latching an SET as an SEU must be reevaluated. In this paper, previous assumptions about the relationship of SET pulsewidth to the probability of latching an SET are reconsidered and a model for transient latching probability has been developed for advanced technologies. A method using the improved transient latching probability and SET data is used to predict logic SEU cross section. The presented model has been used to estimate combinational logic SEU cross sections in 32-nm partially depleted silicon-on-insulator (SOI) technology given experimental heavy-ion SET data. Experimental SEU data show good agreement with the model presented in this paper.

Recoil-Ion-Induced Single Event Upsets in Nanometer CMOS SRAM Under Low-Energy Proton Radiation

Low-energy (<10 MeV) proton-induced single event upsets (SEUs) were investigated through proton and heavy ion experiments on a 65 nm CMOS bulk SRAM. It is unlikely that 2-10 MeV proton direct ionization can induce SEUs in the 65 nm SRAM and the observed single-bit upsets (SBUs) and multiple cell upsets (MCUs) are mainly induced by the ionization from the recoil ions. The MCUs induced by low-energy protons in our 65 nm SRAM can be corrected by the error correction codes (ECC) because they usually occur along the SRAM bit line. The Geant4 simulations revealed that the SEU cross-section may show two different trends for 2-10 MeV protons depending on the critical charge for triggering a SEU. With the increase of proton energy, SEUs in small critical charge SRAM tend to decrease while SEUs in large critical charge SRAM tend to increase. Further, the Geant4 simulations demonstrated that the SEUs induced by recoil oxygen are more than those induced by recoil silicon and SEUs induced by recoil ions from elastic collisions dominate in our 65 nm CMOS SRAM under 2-10 MeV proton radiation.

Angular Effects of Heavy-Ion Strikes on Single-Event Upset Response of Flip-Flop Designs in 16-nm Bulk FinFET Technology

Radiation particles are incident on an integrated circuit (IC) from all angles. For planar technologies, angular incidence increases the deposited charge in a given volume, resulting in higher collected charge at a node and more transistors collecting charge due to increased charge sharing. For FinFET technologies, the physical structure of a FinFET is very different from that of a planar transistor. As a result, deposited and collected charge at a node for angular incidences will be different from what has been published for planar technologies. 3D TCAD simulations and heavy-ion experiments were carried out to investigate the angular effects on flip-flop (FF) single-event upsets (SEU) at the 16-nm bulk FinFET technology. Results show different SEU cross-section trends for the FinFET technology compared to planar technologies. Results show increased upset probability and SEU cross-sections with increasing tilt angles, but those are reduced with increasing roll angles for low-LET heavy-ion incidence. The main reason for this behavior is posited to be variations in charge track length within active Si regions.

Single-Event Performance of Sense-Amplifier Based Flip-Flop Design in a 16-nm Bulk FinFET CMOS Process

The increasing need for high-speed logic circuits is causing the conventional flip-flop (FF) designs to migrate to differential FF designs. With the small magnitude of input voltages (and the resulting small noise margins) needed for proper operation, sense-amplifier based FF designs (SAFF) are susceptible to single-event effects (SEE). Single event upset (SEU) performance of high-speed SAFF designs is investigated in this paper for 16-nm bulk FinFET CMOS technology. SEU cross-sections for SAFF are evaluated over particle LET, temperature, and operating frequency. Results show significant increases in cross-sections as a function of frequency, but not so for temperature. Results presented in this work can guide designers to harden the SAFF that satisfies their specific circuit SEU error rate constraints.

Impact of recombination on heavy ion induced single event upset cross-section

The experimental dependence of the single event upset (SEU) cross-section versus linear energy transfer (LET) function in the nanoscale (with feature size less than 100 nm) memories is explained with the proposed recombination-limited charge yield, which is significantly dependent on LET.

Failure rate calculation method for high power devices in space applications at low earth orbit

This paper discusses the universal calculation method for space proton induced failure rate on high power device. High energetic particles can be the reason of power device failure in both terrestrial and space. T-CAD simulation result gives a threshold charge value for the device destruction which is triggered by energetic proton from space. The amount of threshold charge depends on applied voltage for high power device. The probability of charge generation in silicon due to proton penetration is considered as well. This probability function variation depends on the thickness of device and incident energy of proton which studied before at there. Last consideration on this paper is 3.3kV PiN diode's Single Event Upset Cross section and failure rate which was calculated by proposed method in Low earth orbit environment condition.

Semi-Empirical Method for Estimation of Single-Event Upset Cross Section for SRAM DICE Cells

We propose a new semi-empirical method for estimation of Single Event Upset (SEU) cross section for SRAM Dual Interlocked Cells (DICE) with known distance between neighboring sensitive volumes. The method is based on experimental analysis of SEU maps in sub-100 nm 6T SRAM along with layout considerations and SPICE simulations. This method could help designers to estimate the SEE robustness of DICE cells at the design stage.

The Power Law Shape of Heavy Ions Experimental Cross Section

Instead of using encapsulated sensitive volumes to simulate charge collection during single event upset (SEU) mechanism, we use continuous variation of the charge collection in the device. Basically, the collection efficiency is equal to 1 in the core of the sensitive volume and decreases outside. Assuming that the collection efficiency decreases as a power law of the distance, we analytically find that heavy ion SEU cross-section follows a power law of the linear energy transfer (LET). Results are in agreement with a set of various experimental data from 250nm to 28nm. We also show that experimental results allow extracting technological parameters of the sensitive volume as well as the threshold LET, which is a feature of the device.

Single event upsets sensitivity of low energy proton in nanometer static random access memory

Low-energy protons are able to generate enough energy through direct ionization to cause a high single event upset cross section as the feature size of semiconductor devices shrinks. It poses a large challenge on the present proton single event modeling test technique and the space upset rate prediction method. Experimental study of proton single event effect in three different feature sizes of static random access memory (SRAM) (i.e. 65 nm, 90 nm, and 250 nm) is carried out based on domestic low-energy proton accelerators and also the foreign middle-high proton accelerators. Complete cross section curves of proton single event upset from low energy to high energy are acquired. Test results show that single event upset cross section below 1 MeV proton is up to three orders of magnitude higher than the saturation cross section of high-energy proton in nanometer SRAM. However, single event upset is not observed for protons below 3 MeV in 250 nm SRAM, and no single event multiple-cell upsets occur for protons below 1 MeV in 90 nm and 65 nm SRAM. The accurate geometrical structure model of composite sensitive volume is constructed through the combination of test data with device information, and calibrated further by single event test data of low-LET heavy ion and high-energy proton. Simulation results based on the model and Monte-Carlo calculation can reveal the root cause of low-proton single event upset cross section peak. Proton single event upsets are only caused through direct ionization of protons below 1 MeV. When low-energy protons pass through the multiple metallization and passivation layers of the device, the energy spectrum is broadened near the Bragg peak of the proton direct ionization, and the energy is deposited concentratedly into the sensitive volume through direct ionization. When the proton energy is too high or too low, the energy can not be deposited effectively into the sensitive volume through direct ionization. The energy spectrum straggling of low-energy protons due to the use of degrader has a large influence on the height and width of the single event upset cross section peak. Moreover, the contribution of low protons to the space proton single event upset rate is predicted for GEO orbit environment in the worst day environment. It shows that the direct ionization from low energy dominates the proton single event upset rate in the space in 65 nm SRAM. With the development of device technology, the critical charge of single event upset will be further reduced; and to the single event upset from low proton direct ionization more attention must be paid in the study and evaluation of single event effect.

Energy and angular dependence of single event upsets in ESA SEU Monitor

The new generation ESA SEU Monitor is first applied to beam verification of Beijing HI-13 Tandem accelerator according to the popularization need of Europe Space Agency and at the desire of contrast of domestic acceleraor with international accelerator. Heavy ion single event cross section of ESA SEU Monitor obtained at HI-13 is compared with those from European facilities. Beam homogeneity is also analyzed based on the SEU physical bitmap. The accuracy of heavy ion beam monitoring technique at HI-13 accelerator is verified. Through combining the heavy ion testing result with the data from the other test sites, it can be observed that the differences between SEU cross sections with different heavy ion energies of the same LET value can reach 1-3 orders of magnitude in the sub-threshold zone of single event upset cross section curve below the direct ionization LET threshold. The geometrical structure, critical charge and collection efficiency of sensitive volume are constructed on the basis of testing data and process information. The physical mechanism of energy effect on single event upsets in ESA SEU Monitor is revealed through using the Monte-Carlo calculation. Nuclear reactions between incident heavy ions and material atoms can account for single event upsets below the direct ionization LET threshold. The differences in nuclear reaction type and cross section between the diferent energy heavy ions and material atoms are the root cause of the difference among heavy ion SEU cross sections with different energies at the same LET value. On the other hand, SEU bitmap nonuniformity among different blocks in memory array and different orientation dices in ESA SEU Monitor is first reported when the heavy ion is incident at a tilting angle at the low LET value. The analysis of device layout and calculation verification can account for this phenomenon. The material of interlayer dielectric with the tilting ion passing through is different when heavy ion reaches the sensitive volume of memory blocks with different data. This leads to the difference between efficient LET values inside the sensitive volume for different data blocks. Eventually the sensitivity difference in single event upset among blocks with different data occures. The applications of ESA SEU Monitor in beam calibrating, tuning of domestic accelerator and single event effect test can be broadened further. Prediction method of space single event upset rate including heavy ion energy dependence and special angular dependence based on full-physical simulation should be developed in the future.

Single-Event Upset Characterization Across Temperature and Supply Voltage for a 20-nm Bulk Planar CMOS Technology

Isotropic alpha particle single-event upsets (SEU) in flip-flops are characterized over temperature and voltage supply variations in a 20-nm bulk planar complementary metal-oxide semiconductor (CMOS) process. The decrease of the MOSFET drain current in saturation with respect to increased temperature and reduced supply voltage explains the increased SEU sensitivity of the flip-flop designs. Experimental SEU cross sections from isotropic Americium-241, 5.4-MeV alpha particle show irradiation increases by 30 × on average, and up to orders of magnitude, as a result of increased device temperature and reduced supply voltage.