Linear Energy Transfer Threshold Research Articles

Heavy-ion and pulsed-laser single event effects in 130-nm CMOS-based thin/thick gate oxide anti-fuse PROMs

Single event effects of 1-T structure programmable read-only memory (PROM) devices fabricated with a 130-nm complementary metal oxide semiconductor-based thin/thick gate oxide anti-fuse process were investigated using heavy ions and a picosecond pulsed laser. The cross sections of a single event upset (SEU) for radiation-hardened PROMs were measured using a linear energy transfer (LET) ranging from 9.2 to 95.6 MeV cm2 mg−1. The result indicated that the LET threshold for a dynamic bit upset was ~ 9 MeV cm2 mg−1, which was lower than the threshold of ~ 20 MeV cm2 mg−1 for an address counter upset owing to the additional triple modular redundancy structure present in the latch. In addition, a slight hard error was observed in the anti-fuse structure when employing 209Bi ions with extremely high LET values (~ 91.6 MeV cm2 mg−1) and large ion fluence (~ 1 × 108 ions cm−2). To identify the detailed sensitive position of a SEU in PROMs, a pulsed laser with a 5-μm beam spot was used to scan the entire surface of the device. This revealed that the upset occurred in the peripheral circuits of the internal power source and I/O pairs rather than in the internal latches and buffers. This was subsequently confirmed by a 181Ta experiment. Based on the experimental data and a rectangular parallelepiped model of the sensitive volume, the space error rates for the used PROMs were calculated using the CREME-96 prediction tool. The results showed that this type of PROM was suitable for specific space applications, even in the geosynchronous orbit.

Heavy-Ion Induced Single Event Upsets in Advanced 65 nm Radiation Hardened FPGAs

The 65 nm Static Random Access Memory (SRAM) based Field Programmable Gate Array (FPGA) was designed and manufactured, which employed tradeoff radiation hardening techniques in Configuration RAMs (CRAMs), Embedded RAMs (EBRAMs) and flip-flops. This radiation hardened circuits include large-spacing interlock CRAM cells, area saving debugging logics, the redundant flip-flops cells, and error mitigated 6-T EBRAMs. Heavy ion irradiation test result indicates that the hardened CRAMs had a high linear energy transfer threshold of upset ∼18 MeV/(mg/cm 2 ) with an extremely low saturation cross-section of 6.5 × 10 − 13 cm 2 /bit, and 71% of the upsets were single-bit upsets. The combinational use of triple modular redundancy and check code could decline ∼86.5% upset errors. Creme tools were used to predict the CRAM upset rate, which was merely 8.46 × 10 − 15 /bit/day for the worst radiation environment. The effectiveness of radiation tolerance has been verified by the irradiation and prediction results.

Investigation of maximum proton energy for qualified ground-based evaluation of single-event effects in SRAM devices

Existing standards show a clear discrepancy in the specification of the maximum proton energy for qualified ground-based evaluation of single-event effects, which can range from 180 to 500 MeV. This work finds that the threshold linear energy transfer of a tested device is a critical parameter for determining the maximum proton energy. The inner mechanisms are further revealed. High-energy deposition events (> 10 MeV) in sensitive volumes are attributed to the interaction between protons and the tungsten vias in the metallization layers.

Mechanisms of Electron-Induced Single-Event Latchup

In this paper, possible mechanisms by which electrons can induce single-event latchups in electronics are discussed. The energy deposition and the nuclear fragments created by electrons in silicon are analyzed in this context. The cross section enhancement effect in the presence of high-Z materials is discussed. First experimental results of electron-induced latchups are shown in static random access memory devices with low linear energy transfer thresholds. The radiation hardness assurance implications and future work are discussed.

Silicon nanotube SRAM and its SEU reliability

In this work, silicon nanotube FET (SiNT FET) based 6T SRAM cell operation is demonstrated and its Read, Write and Hold SNMs (static noise margin) are analyzed. The SRAM is also investigated for one of the important dynamic stability performance metrics, single event upset under heavy ion irradiation (SEU). Three different striking locations (region closer to source, center of channel and region closer to drain) and three different striking angles are used during SEU study. The worst case threshold Linear Energy Transfer (LET) is found to be 36 MeV/(mg/cm2). All the studies are carried out using mixed mode 3D numerical simulations.

Radiation Hard Contactless Angular Position Sensor Based on Hall Effect

The results of the total ionizing dose (TID) and single event effect (SEE) tests on the contactless angular position sensor based on Hall effect are presented. The TID testing reveals that the devices are resistant to the gamma radiation exhibiting only a slight increase in the supply current, not more than 1 % of the initial values. In general, both the serial peripheral interface (SPI) output errors and analog output errors have recovered to their initial values after annealing at high temperatures. Only the biased sample with magnet showed a significant increase of the analog output error at higher radiation levels and did not return to its initial value, it remained about a 56 % higher. Nevertheless, the error is still within the limits for space application of the sensor. SEE tests were performed up to linear energy transfer (LET) levels of 67.7 MeV $\cdot $ cm2/mg and the sensors experienced neither single event latch-up (SEL) nor single event transient (SET). The upper limit of cross section for single event functional interrupt (SEFI) was found by Weibull fit as being $3.53\cdot 10^{\mathrm {-6}}$ cm2 and the LET threshold was 15.1 MeV $\cdot $ cm2/mg. The SEFI rates were calculated by means of the CREME96 for geostationary orbit (GEO) and the orbit of the International Space Station (ISS). Calculations were performed for minimum solar and peak 5 minutes environment, and in the case of the ISS orbit also trapped particles and magnetic weather conditions were included.

An Area Efficient Stacked Latch Design Tolerant to SEU in 28 nm FDSOI Technology

In this paper, we present D flip-flop, Quatro, and stacked Quarto flip-flop designs fabricated in a commercial 28-nm CMOS FDSOI technology. Stacked-transistor structures are introduced in the stacked Quatro design to protect the sensitive devices of the original structure. Striking either of the stacked devices will not upset the latch because the conduction path to the supply rail is still cut off by the other off-state device. The irradiation experimental results substantiate that the stacked Quatro design has significantly better SEU tolerance (e.g., higher heavy ion upset Linear Energy Transfer threshold and smaller cross-section data) than the reference designs. It introduces power and area penalties because the proposed design duplicates and stacks two sensitive PMOS devices. Additionally, the impact of technology scaling on Quatro in various technology nodes (130-nm, 65-nm, and 40-nm) has been studied suggesting decreasing upset threshold and decreasing cross-section data.

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.

Experimental research of heavy ion and proton induced single event effects for a Bi-CMOS technology DC/DC converter

This paper tested and analyzed heavy ion and proton induced single event effects (SEE) of a commercial DC/DC converter based on a 600 nm Bi-CMOS technology. Heavy ion induced single event transients (SET) testing has been carried out by using the Beijing HI-13 tandem accelerator at China Institute of Atomic Energy. Proton test has been carried out by using the Canadian TRIUMF proton accelerator. Both SET cross section versus linear energy transfer (LET) and proton energy has been measured. The main study conclusions are: (1) the DC/DC is both sensitive to heavy ion and proton radiations although at a pretty large feature size (600 nm), and threshold LET is about 0.06 MeV·mg/cm2; (2) heavy ion SET saturation cross section is about 5 magnitudes order larger than proton SET saturation cross section, which is consistent with the theory calculation result deduced by the RPP model and the proton nuclear reaction model; (3) on-orbit soft error rate (SER) prediction showed, on GEO orbit, proton induced SERs calculated by the heavy ion derived model are 4–5 times larger than those calculated by proton test data.

Fast luminescence in vacuum ultraviolet region in heavy-ion-irradiated α-Al2O3

We analyzed the time-resolved luminescence properties of α-Al2O3 under heavy ion irradiations in the vacuum ultraviolet (VUV) wavelength region. A luminescence band at approximately 170nm, at which a luminescence band was observed under VUV irradiation and was ascribed to self-shrunk excitons. The decay rate increased with the linear energy transfer (LET). The luminescence efficiency of the band increased sharply with the LET for the case of Xe irradiation, whose LET was estimated to be higher than the threshold LET for track formation. The fast decay rate and high luminescence intensity for Xe irradiation was explained according to the enhanced radiative rate caused by close interactions among excited states.

Spectroscopic study of chemical modifications induced by swift heavy ions on polymers: the contribution of the CIRIL Platform and the CIMAP Laboratory

This paper gathers results obtained on the chemical ageing of polymers, at the CIRIL platform, using Swift heavy ions (SHI) from the GANIL accelerator. Swift heavy ions induce high values of electronic stopping power or LET (Linear Energy Transfer) and deposit their energy in the polymer through electronic processes, in a few nanometer size cylinder centered on the ion path. This results in huge local doses and dose rates. Both defects created in the polymer chain and gas release were quantified using spectroscopic methods (FTIR and Residual gas analysis (RGA)). Defects created in polymers submitted to SHI can be separated in two main series: defects common to all ionizing radiations and defects specific to SHI. A common trend of the evolution of these defects, under inert environment, is the following: 1) for the first group of defects, in most of the polyolefins, there is a limited (if inexistent) effect of LET on the radiation chemical yield of creation at low doses. Among defects of this first series, the behavior of vinyl groups is particular, 2) LET effect on SHI specific defects (triple bonds and cumulenes) is tremendous. Triple bonds (alkynes, alkyl or aryl cyanates) are created after a LET threshold value, depending on the polymer chemical structure. The dose effect on macromolecular defects, under inert environment, is also presented. The study of the LET effect on gas release, in various polyolefines, gives an insight on the mechanism of bond cleavage in presence of high ionization and excitation densities. Finally, few results on radiation-induced oxidation are presented. Compared to low-ionizing radiations, oxidation is reduced and unsaturated bonds are created under SHI.

Impact of temperature on single event upset measurement by heavy ions in SRAM devices

The temperature dependence of single event upset (SEU) measurement both in commercial bulk and silicon on insulator (SOI) static random access memories (SRAMs) has been investigated by experiment in the Heavy Ion Research Facility in Lanzhou (HIRFL). For commercial bulk SRAM, the SEU cross section measured by 12C ions is very sensitive to the temperature. The temperature test of SEU in SOI SRAM was conducted by 209Bi and 12C ions, respectively, and the SEU cross sections display a remarkable growth with the elevated temperature for 12C ions but keep constant for 209Bi ions. The impact of temperature on SEU measurement was analyzed by Monte Carlo simulation. It is revealed that the SEU cross section is significantly affected by the temperature around the threshold linear energy transfer of SEU occurrence. As the SEU occurrence approaches saturation, the SEU cross section gradually exhibits less temperature dependency. Based on this result, the experimental data measured in HIRFL was analyzed, and then a reasonable method of predicting the on-orbit SEU rate was proposed.

Calculation of single event upset based on Monte Carlo and device simulations

An extraction method for single event upset cross section based on Monte Carlo code and device simulation is proposed, which can be used to calculate single event effects and sensitive regions in memories accurately. Single event upset cross sections of domestic static random access memory (SRAM) and field programmatic gate array (FPGA) devices are calculated, and results agree well with these from heavy ion test. Simulation results reveal the physical mechanism of the relationship between single event upset sensitivity and surface area of off-state NMOSFET and PMOSFET. Sensitive regions of single event upset under different linear energy transfer (LET) values are obtained. The radial ionization profiles of heavy ions with different energy, but the same LET, are also calculated using the Monte Carlo method. The track radius of high-energy ion is significantly larger than that of low-energy ion, while the charge density at the track center of low-energy ion is higher by two or three orders of magnitude. With decreasing technology scaling, the impact of these differences on single event effects will be more pronounced, and the threshold LET and saturated cross-section will not be capable of describing the single event response completely.

The supply voltage scaled dependency of the recovery of single event upset in advanced complementary metal—oxide—semiconductor static random-access memory cells

Using computer-aided design three-dimensional simulation technology, the supply voltage scaled dependency of the recovery of single event upset and charge collection in static random-access memory cells are investigated. It reveals that the recovery linear energy transfer threshold decreases with the supply voltage reducing, which is quite attractive for dynamic voltage scaling and subthreshold circuit radiation-hardened design. Additionally, the effect of supply voltage on charge collection is also investigated. It is concluded that the supply voltage mainly affects the bipolar gain of the parasitical bipolar junction transistor (BJT) and the existence of the source plays an important role in supply voltage variation.

Single event upset sensitivity of 45 nm FDSOI and SOI FinFET SRAM

In this work single event upset (SEU) sensitivity of 45 nm fully depleted silicon-on-insulator (FDSOI) static random access memory (SRAM) cell and that of SOI fin-shaped field-effect-transistor (FinFET) SRAM cell have been investigated by 3D TCAD simulations. The critical charges and SEU threshold linear energy transfer (LET) value of the two SRAM cells are consistent due to similar gate capacitance. The low electrical field and the high recombination rate account for the non-sensitivity to SEU in heavily doped drain region. Compared with FDSOI SRAM, SOI FinFET SRAM cell exhibits lower SEU sensitivity at the center of the gate. The smaller sensitive area in SOI FinFET SRAM cell may result in a smaller SEU saturation cross section than that of SOI FinFET SRAM.

Establishing Best-Practice Modeling Approaches for Understanding Single-Event Transients in Gb/s SiGe Digital Logic

Single-event transient (SET) simulations of a Gb/s SiGe BiCMOS master/slave D flip-flop circuit are performed, employing both a decoupled current-injection SET modeling technique and a fully-coupled mixed-mode TCAD technique to model heavy-ion strikes to the storage and input cells. New insights are provided into the physical mechanisms underlying the single-event upset (SEU) sensitivity of high-speed SiGe digital latches and shift registers. A close analysis of the transient circuit behavior identifies the limitations of the current-injection approach in predicting SEU in fast SiGe digital logic. Furthermore, the physical ion track linear energy transfer (LET) is varied to establish the threshold LET for SEU using each simulation technique, further highlighting the SEU prediction error inherent to conventional decoupled modeling approaches. Finally, clocked mixed-mode circuit simulations are used to explain the fundamental SEU mechanisms and relate them to corresponding regions of the device-level SET.

Development of Neutron Measurement in Intense Gamma Field Using New Type of Nuclear Emulsion

Abstract To precisely measure the neutron emissions from a spent fuel assembly of a fast breeder reactor, we formed nuclear emulsions based on a non-sensitized Oscillation Project with Emulsion tRacking Apparatus (OPERA) film with AgBr grain sizes of 60, 90, and 160 nm. The efficiency for 252Cf neutron detection of the new emulsion was calculated to be 0.7 × 10−4, which corresponded to an energy range from 0.3 to 2 MeV and was consistent with a preliminary estimate based on experimental results. The sensitivity of the new emulsion was also experimentally estimated by irradiating with 565 keV and 14 MeV neutrons. The emulsion with an AgBr grain size of 60 nm had the lowest sensitivity among the above three emulsions but was still sensitive enough to detect protons. Furthermore, the experimental data suggested that there was a threshold linear energy transfer of 15 keV/μm for the new emulsion, below which no silver clusters developed. Further development of nuclear emulsion with an AgBr grain size of a few tens of nanometers will be the next stage of the present study.

Recovery of single event upset in advanced complementary metal—oxide semiconductor static random access memory cells

Using computer-aided design three-dimensional (3D) simulation technology, the recovery mechanism of single event upset and the effects of spacing and hit angle on the recovery are studied. It is found that the multi-node charge collection plays a key role in recovery and shielding the charge sharing by adding guard rings. It cannot exhibit the recovery effect. It is also indicated that the upset linear energy transfer (LET) threshold is kept constant while the recovery LET threshold increases as the spacing increases. Additionally, the effect of incident angle on recovery is analysed and it is shown that a larger angle can bring about a stronger charge sharing effect, thus strengthening the recovery ability.

Research on single event transient pulse quenching effect in 90 nm CMOS technology

Since single event transient pulse quenching can reduce the SET (single event transient) pulsewidths effectively, the charge collected by passive device should be maximized in order to minimize the propagated SET. From the perspective of the layout and circuit design, the SET pulsewidths can be greatly inhibited by minimizing the layout spacing and signal propagation delay, which sheds new light on the radiation-hardened ICs (integrated circuits) design. Studies show that the SET pulsewidths of propagation are not in direct proportion to the LET (linear energy transfer) of incident particles, thus the defining of the LET threshold should be noted when SET/SEU (single event upset) occurs for the radiation-hardened design. The capability of anti-radiation meets the demand when LET is high but some soft errors may occur when LET is low. Therefore, radiation experiments should be focused on evaluating the LET that demonstrates the worst response to the circuit.

Mixed-Mode Simulation of Bit-Flip With Pulsed Laser

This paper shows an adaptation of the Sentaurus TCAD suite to pulsed laser SEE simulation. After the literature review, we present the model of the target transistor, calibrated against the HSPICE model of the foundry. The target model is used to evaluate the Linear Energy Transfer threshold for bit-flip in a simulated flip-flop circuit using the heavy-ion simulation tools of Sentaurus TCAD. Those simulations help us to make an adaptation of Sentaurus TCAD physical model for simulation of pulsed laser experiments. The pulsed laser simulation results are compared with a pulsed laser experiment, showing that the proposed model achieves more accuracy than previous models referred to in the literature.