Proton Single Event Effect Research Articles

Proton single event effects on 8T global exposure CMOS image sensors

CMOS image sensors in optical payloads are susceptible to single-event effects when irradiated by high-energy protons from the spatial radiation environment. Single-event transients in images primarily manifest as bright spots, and the characteristics of transient bright spots generated under different incident conditions exhibit some differences. In this study, we conducted proton irradiation experiments on CMOS image sensors at different energy levels and incident angles. The characteristics of single-event transient bright spots generated under various incident conditions were extracted and analysed in detail. Furthermore, the abnormal phenomena of different functional modules of CMOS image sensors observed during proton irradiation experiments were investigated. The results of this study establish the foundation for classifying the detected targets and transient bright spots, indicating that the validation of CMOS image sensor radiation reliability should account for functional abnormalities resulting from high-energy proton irradiation.

A new model for predicting proton SEE cross sections based on heavy ion data

Based on the physical mechanism of the proton single event effects (SEEs), a new analytical model is proposed to predict the proton SEE cross sections of electronic devices from the heavy ion data. The experimental data of five SRAMs from our experiments and the literature are used to test the new model, and the predicted results agree well with them. The existing models only apply to the devices with low LET threshold whose proton SEE cross sections are dominated by the p + Si reactions, and cannot predict the angular effects. Compared to them, our model applies to the devices with from low to high LET threshold whose proton SEE cross sections are dominated by the proton interactions with silicon and/or high-Z materials, and can also predict the angular effects. Moreover, for two SRAMs with low LET threshold, our model performs much better than two classic models, the BGR and microdosimetry models, in predicting their proton SEE cross sections at normal incidence. A new physical concept called the indirect ionization power of protons, which is very helpful for understanding the proton SEE mechanism, is put forward and used in our model. It is expected that the new model will be widely used in studying the proton SEE mechanism, predicting the proton SEE cross sections and on-orbit error rates of electronic devices in space.

Measurement of medium-energy proton flux

<sec>Proton is the main particle component in the space radiation environment. The proton single event effect cannot be ignored with the continuous development of semiconductor technology. Accelerator simulation is the most important method to evaluate the single event effect caused by proton radiation, and the accurate measurement of proton flux is the most critical aspect in the device evaluation process. The research is based on the 100 MeV proton single-event irradiation device of the Atomic Energy Institute, which breaks through the wide-range mid-energy proton fluence rate measurement technology. The detection tools are developed such as Faraday cup, plastic scintillator detectors and secondary electron emission monitors, which can be used for measuring the proton beam current in a wide range. Faraday cup and plastic scintillator detector can be used for measuring the high flux proton and the low flux proton, respectively. Secondary electron emission monitor can be used for conducting the online real-time measurement. The proton fluxes in a range of 10<sup>6</sup>– 10<sup>7</sup> p·cm<sup>–2</sup>·s<sup>–1</sup> are measured by using two separate detectors.</sec><sec>The analysis of the fluence rate uncertainty is carried out. The uncertainty of measurement results mainly include three aspects: measurement method, measuring instrument and equipment, and repeatability of multiple measurement results. Here in this work, the Faraday cup is taken for example to analyze the uncertainty sources in the proton flux measurement. The measurement methods include the calculation of the collection efficiency of the Faraday cup (collection efficiency + escape rate = 1) and the calculation method of flux (flux = current/collection area). For the measuring instruments and equipment, mainly including 6517A and other electronic devices, their errors are determined by the accuracies of the instruments themselves. Repeatability of multiple measurement results mainly from the error caused by the instability of the accelerator beam output, the error caused by randomness of multiple measurement results, and the error given by the statistical method. The analysis shows that the uncertainty of flux measurement by Faraday cup is 7.26%, and the uncertainty of flux measurement by plastic scintillator detector is 1.64%.</sec><sec>The flux measurement of the proton fluence rate has reached the level of similar devices in the world, filling the gap in this field in China. It has a certain reference and guiding significance for the follow-up study of medium- and high-energy proton beam measurement in China. The mid-energy proton flux measurement system and uncertainty analysis method established in this study lay the foundation for accurately evaluating the component radiation effects.</sec>

Single event transient effect of frontside and backside illumination image sensors under proton irradiation

Complementary metal oxide semiconductor (CMOS) image sensor is susceptible to proton single event effect when being applied to space environment. Proton irradiation experiments with different energy values are carried out on a commercial FSI and BSI CMOS image sensors. The proton single event effect is analyzed by on-line testing, the maximum proton energy is 200 MeV, and the total fluence is 10<sup>10 </sup>particle/cm<sup>2</sup>. The single-event transient bright spots of different shapes are observed in the pixel array. By extracting the deposition energy and size, the effects of different energy protons on transient bright spot characteristics are compared, and the transient bright spot characteristics between FSI and BSI are also compared. Finally, the energy deposition distribution of the transient bright spot generated by proton in CMOS image sensor pixel unit is predicted by comparing the simulation method with the experimental results. The simulation results verify that the decrease of PPD depletion region thickness and the thinning of epitaxial layer are the main factors leading the proton energy deposition distribution to shift leftward in BSI image sensor.

Prediction of proton single event upset sensitivity based on heavy ion test data in nanometer hardened static random access memory

In order to evaluate the radiation tolerance to proton single event effect(SEE) in nanometer dual interlocked cell (DICE) hardening device accurately, single event upset (SEU) linear energy transfer (LET) threshold at heavy ion normal and tilt incidence, and the worst case SEU orientational angle are acquired based on the analysis of heavy ion SEU testing data in 65 nm dual DICE static random access memory (SRAM). It is proved that dual DICE design is effective for improving the LET threshold against SEU. Howerer, heavy ion tilt incidence at the worst orientational angle will significantly reduce the SEU threshold and increase the SEU cross section. The worst orientational angle for SEU in DICE SRAM is the large tilting angle along the well. The maximum LET value and the emission angle distribution of secondary particle induced by the nuclear reaction between protons with different energy and layers with different multiple metallization are obtained by using Monte-Carlo simulation. The maximum LET value of secondary particle from proton-copper spallation reaction is higher than 15 MeV·cm<sup>2</sup>/mg for 100 MeV and 200 MeV protons. Secondary particles with the maximum energy and longest range are emitted preferentially in the forward direction. Proton SEU sensitivity is further predicted through combining heavy ion test data with Monte-Carlo simulation. Proton SEU test data verify the effectiveness of the prediction method and the accuracy of the prediction results. The research results indicate that the tolerance of nanometer DICE hardening technique against proton SEU will be overestimated if SEE evaluation test is carried out with only 100 MeV proton accelerator or normal incidence. Proton single event upset in nanometer dual DICE SRAM has an evident dependence on tilt angle and orientational angle. By adopting the above prediction method, whether proton SEE test needs performing or not in nanometer radiation-hardening device can be judged and screened. The requirements for the maximum energy of proton accelerator can be ascertained. In order to ensure that the devices are applied to space with high reliability, SEE test should be carried out including tilt incidence at the worst orientational angle in nanometer DICE hardening device in the process of heavy ion and proton SEE test evaluation.

Design of 100-MeV proton beam spreading scheme with double-ring double scattering method

To obtain a large uniform beam field for proton single event effect (SEE) experiments, the double-ring double scattering method (DDSM) is employed for spreading the 100 MeV proton beam provided by the 100 MeV proton cyclotron at China Institute of Atomic Energy. With the Geant 4 simulations, the fundamentals of the DDSM are further explored, the achieved effect of our DDSM scheme design is presented, and the influences of some possible factors in practice on the produced beam field are discussed. We find that the the outer part of the second scatter plays an important role in enlarging the area of the uniform field and improving its uniformity. We also find that the first scatter and the inner part of the second scatter play a decisive role in determining the proton flux of the uniform area. The scattering between the spread proton beam and the accelerator tube behind the second scatter damages the uniformity and leads the energy of the produced beam field to straggle. Therefore, the tube should be made as short as possible. The size of the initial beam spot on the first scatter affects the produced beam field to some extent. The spot should be focused as much as possible in a circle with a radius of 0.5 cm. At a larger distance, a larger uniform field can be produced due to the spreading of the proton beam along the space. The decrease in the incident proton energy causes the flux and uniformity to decrease, and also leads the energy loss to increase and the energy of the produced proton beam field to straggle. Using our DDSM schematic design, the simulations show that an 8-cm-diameter beam field with a uniformity of ±1.89% can be produced at a distance of 2.4 m, thereby meeting the need for an SEE experiment of a device-level sample, and that a 20-cm-radius beam field with a uniformity of ±5.32% can be created at a distance of 5.0 m, thereby meeting the need for an SEE experiment of a system-level sample of comparable size. By taking into consideration the uniformity and energy straggling, our design is basically applicable to the protons in the 70−100 MeV energy region that the accelerator can provide directly.

Incorporating Radiation Effects Into AE9/AP9

This paper describes a framework for incorporating linear radiation effects into the statistical machinery of the AE9/AP9 radiation climatology model software via “kernel” files. Users can provide their own kernels without modification of the software. Kernels can be applied to a variety of radiation effects such as proton single-event effect rate, internal charging current, ionizing dose, and nonionizing dose. Kernels can be generated for custom shielding geometry and materials and for custom parts or material susceptibilities.

Single event effects sensitivity of low energy proton in Xilinx Zynq-7010 system-on chip

In this paper, experimental methods are emphatically described for measuring the proton single event effects (SEE) in Xilinx Zynq-7010 system-on chip. Experimental data are presented showing that low energy (3MeV≤Energy≤10MeV) proton irradiation can cause single event effects in different hardware blocks of Xilinx Zynq-7010 SoC, including D-Cache, programmable logic (PL), arithmetic logical unit (ALU), float point unit (FPU) and direct memory access (DMA). Moreover, the sensitivities of different hardware blocks to single event effects are different. Finally, the Stopping and Range of Ions in Matter (SRIM) software calculations show the possible reasons for this difference.

Prediction of proton-induced SEE error rates for the VATA160 ASIC

We predict proton single event effect (SEE) error rates for the VATA160 ASIC chip on the Dark Matter Particle Explorer (DAMPE) to evaluate its radiation tolerance. Lacking proton test facilities, we built a Monte Carlo simulation tool named PRESTAGE to calculate the proton SEE cross-sections. PRESTAGE is based on the particle transport toolkit Geant4. It adopts a location-dependent strategy to derive the SEE sensitivity of the device from heavy-ion test data, which have been measured at the HI-13 tandem accelerator of the China Institute of Atomic Energy and the heavy-ion research facility in Lanzhou. The AP-8, SOLPRO, and August 1972 worst-case models are used to predict the average and peak proton fluxes on the DAMPE orbit. Calculation results show that the averaged proton SEE error rate for the VATA160 chip is approximately 2.17 × 10−5/device/day. Worst-case error rates for the Van Allen belts and solar energetic particle events are 1–3 orders of magnitude higher than the averaged error rate.

Monte Carlo predictions of proton SEE cross-sections from heavy ion test data**Supported by National Natural Science Foundation of China (11179003, 10975164, 10805062, 11005134)

The limits of previous methods prompt us to design a new approach (named PRESTAGE) to predict proton single event effect (SEE) cross-sections using heavy-ion test data. To more realistically simulate the SEE mechanisms, we adopt Geant4 and a location-dependent strategy to describe the physics processes and the sensitivity of the device. Cross-sections predicted by PRESTAGE for over twenty devices are compared with the measured data. Evidence shows that PRESTAGE can calculate not only single event upsets induced by indirect proton ionization, but also direct ionization effects and single event latch-ups. Most of the PRESTAGE calculated results agree with the experimental data within a factor of 2–3.

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.