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Variability of the space radiation environment is investigated with regard to parts categorization for total dose hardness assurance methods. It is shown that it can have a significant impact. A modified approach is developed that uses current environment models more consistently and replaces the radiation design margin concept with one of failure probability during a mission.

The Hubble Space Telescope has been at the forefront of discoveries in the field of astronomy for more than 20 years. It was the first telescope designed to be serviced in space and the last such servicing mission occurred in May 2009. The question of how much longer this valuable resource can continue to return science data remains. In this paper a detailed analysis of the total dose exposure of electronic parts at the box level is performed using solid angle sectoring/3-dimensional ray trace and Monte Carlo radiation transport simulations. Results are related to parts that have been proposed as possible total dose concerns. The spacecraft subsystem that appears to be at the greatest risk for total dose failure is identified. This is discussed with perspective on the overall lifetime of the spacecraft.

The low-energy proton energy spectra of all shielded space environments have the same shape. This shape is easily reproduced in the laboratory by degrading a high-energy proton beam, producing a high-fidelity test environment. We use this test environment to dramatically simplify rate prediction for proton direct ionization effects, allowing the work to be done at high-energy proton facilities, on encapsulated parts, without knowledge of the IC design, and with little or no computer simulations required. Proton direct ionization (PDI) is predicted to significantly contribute to the total error rate under the conditions investigated. Scaling effects are discussed using data from 65-nm, 45-nm, and 32-nm SOI SRAMs. These data also show that grazing-angle protons will dominate the PDI-induced error rate due to their higher effective LET, so PDI hardness assurance methods must account for angular effects to be conservative. As a result, we show that this angular dependence can be exploited to quickly assess whether an IC is susceptible to PDI.

The speed, tight timing requirements packaging and complicated error behavior of DDR2 and DDR3 SDRAMs pose significant challenges for single-event testing. Often, each new generation will require an expensive new tester with a state-of-the-art controller for the memory. We explore the trade-offs in the use of commercial FPGA based evaluation boards for radiation testing DDR2 and DDR3 SDRAMs. We evaluate the resulting data quality and discuss tester performance while also elucidating and comparing SEE susceptibilities in DDR2 and DDR3 SDRAMs.

We have compared the data retention of irradiated commercial NAND flash memories at different doses. Activation energies for retention testing at high temperature have also been determined.

Pulsed laser test results for NAND flash memories are compared with broad beam heavy ion results and also with heavy ion results obtained with the collimated Milli-Beam™ source. The pulsed laser measurements reported here, with smaller focused spot sizes and as a function of the incident pulse energy, serve to reconcile the previously reported inconsistencies. The Milli-Beam™ and pulsed laser results appear to be consistent, and differences from the broad beam heavy ion results can be explained. The results suggest that the high current SEFIs reported by us and others arise from multiple ion (or multiple photon) interactions, and are not associated with single ion strikes.

TID test results of CMOS Flash-based FPGAs in gamma-rays are presented. The use of realistic low dose-rates and oriented bias-conditions are shown to extend the FPGA TID tolerance. Implications to qualification methods and to most of the new CMOS technologies are noted.

We have compared the data retention of irradiated commercial NAND flash memories with that of unirradiated controls. For parts aged by baking at high temperature, there was a statistically significant difference between irradiated samples and unirradiated controls. For parts aged by repetitive Program/Erase (P/E) cycling, the effect of radiation was not statistically significant.

This paper presents and explains test results showing the effect of ion species on the single event burnout (SEB) failure voltage using a SEB sensitive engineering power double diffused metal oxide silicon field effect transistor (DMOSFET). The analyses show the determining factor of tested SEB failure voltage is the ion species itself rather than test or beam conditions such as initial beam energy, surface linear energy transfer (LET), ion range, or ionized charge. Also, results from five test facilities and five test setups are compared to determine if there will be differences in test results when different test setups or different heavy ion accelerator facilities were used.

We measured low-energy proton radiation induced soft error rates (SER) of standard and reduced-SER (RSER) latches, manufactured in 32 nm and 45 nm bulk CMOS technologies, and conclude that sequential logic elements built in these technologies are not yet susceptible. Further, our results demonstrate that at proton energies where direct ionization dominates, critical charge (Qcrit) plays a far bigger role than at proton energies above the nuclear reaction threshold.

An analysis of charge pump design for improved radiation tolerance of phase locked loops is presented. Two radiation-hardened-by-design approaches are considered to mitigate the total ionizing dose damage of the circuit, and a thick-film SOI SiGe process technology has been used to reduce charge collection of single event strikes. The results show that a modified design approach to implement the charge pump using SiGe HBTs can provide advantages in radiation tolerance to improve tri-state leakage performance, particularly for missions expecting large accumulated doses.

The relative importance of heavy-ion interaction with the oxide, charge ionized in the epilayer, and charge ionized in the drain substrate, on the bias for SEGR failure in vertical power MOSFETs is experimentally investigated. The results indicate that both the charge ionized in the epilayer and the ion atomic number are important parameters of SEGR failure. Implications on SEGR hardness assurance are discussed.

We present results on the effects of ELDRS at dose rates of 10, 5, 1, and 0.5 mrad(Si)/s for a variety of commercial, radiation hardened, and ELDRS-free devices. We observed low dose rate enhancement below 10 mrad(Si)/s in several different part types. The magnitudes of the low dose rate enhancement varied substantially. The most notable case showed dose rate sensitivity in the functional failures for a commercial voltage regulator, with initial failures occurring after 10 krad(Si) for the parts irradiated at 0.5 mrad(Si)/s. Radiation hardened and ELDRS-free devices also showed ELDRS at the ultra-low dose rates. An ELDRS-free high power regulator showed a low dose rate enhancement factor of ×33 after 10 krad(Si) for parts irradiated at 0.5 mrad(Si)/s. The enhanced degradation at the ultra-low dose rates present challenges for hardness assurance.

Single event upset (SEU) experimental heavy ion data and modeling results for CMOS, silicon-on-insulator (SOI), 32 nm and 45 nm stacked and DICE latches are presented. Novel data analysis is shown to be important for hardness assurance where Monte Carlo modeling with a realistic heavy ion track structure, along with a new visualization aid (the Angular Dependent Cross-section Distribution, ADCD), allows one to quickly assess the improvements, or limitations, of a particular latch design. It was found to be an effective technique for making SEU predictions for alternative 32 nm SOI latch layouts.

A novel approach to SEE characterization of counters implemented in a RTAX-S FPGA is presented. Net fan-out, capacitive loading, and operational frequency have demonstrated a direct impact to counter SEU cross sections as compared to shift registers.

A novel approach to dynamic SEE ADC testing is presented. The benefits of this test scheme versus prior implemented techniques include the ability to observe ADC SEE errors that are in the form of phase shifts, single bit upsets, bursts of disrupted signal composition, and device clock loss.

We report on complementary use of two-photon absorption laser and heavy-ion SEE testing to evaluate the single-event response of SDRAMs. The tandem testing technique helps disentangle the response of devices exhibiting multiple SEE modes.

We have compared the endurance of irradiated commercial NAND flash memories with that of unirradiated controls. Radiation exposure has little or no effect on the endurance of flash memories. Results are discussed in light of the relevant models for electron and hole trapping.

Silicon-germanium heterojunction bipolar transistor (SiGe HBT) heavy ion-induced current transients are measured using Sandia National Laboratories' microbeam and high- and low-energy broadbeam sources at the Grand Acce?le?rateur National d'Ions Lourds, Caen, France, and the University of Jyva?skyla?, Finland. The data were captured using a custom broadband IC package and real-time digital phosphor oscilloscopes with at least 16 GHz of analog bandwidth. These data provide detailed insight into the effects of ion strike location, range, and LET.

We present results of laser-induced analog SETs at elevated temperatures. We found increasing pulse widths with increasing temperature for the LM124. We also observed increasing pulse amplitudes with increasing temperature for several sensitive transistors in the LM139. However the response from the input transistor was a rapidly shrinking SET, suggesting that the SET threshold increases at elevated temperatures for the input stage transistors. In addition we observed increases in the SET leading edge fall times with increasing temperature for the LM139 that are consistent with independently measured slew rates. Simulations revealed that the dominant mechanism is bipolar current gain enhancement at elevated temperatures. These temperature-induced changes to the SETs may have critical implications for radiation hardness assurance.

Experimental results are presented on single-bit-upsets (SBU) and multiple-bit-upsets (MBU) on a 45 nm SOI SRAM. The accelerated testing results show the SBU-per-bit cross section is relatively constant with technology scaling but the MBU cross section is increasing. The MBU data show the importance of acquiring and analyzing the data with respect to the location of the multiple-bit upsets since the relative location of the cells is important in determining which MBU upsets can be corrected with error correcting code (ECC) circuits. For the SOI SRAMs, a large MBU orientation effect is observed with most of the MBU events occurring along the same SRAM bit-line; allowing ECC circuits to correct most of these MBU events.

A methodology for evaluating various types of FPGAs targeted for space missions is presented. The premise is to supply unambiguous SEE information so that flight-projects may insert the optimal device for their application.

Experimental results are presented on proton induced single-event-upsets (SEU) on a 65 nm silicon-on-insulator (SOI) SRAM. The low energy proton SEU results are very different for the 65 nm SRAM as compared with SRAMs fabricated in previous technology generations. Specifically, no upset threshold is observed as the proton energy is decreased down to 1 MeV; and a sharp rise in the upset cross-section is observed below 1 MeV. The increase below 1 MeV is attributed to upsets caused by direct ionization from the low energy protons. The implications of the low energy proton upsets are discussed for space applications of 65 nm SRAMs; and the implications for radiation assurance testing are also discussed.

The effects of device orientation on heavy ion-induced multiple-bit upset (MBU) in 65 nm SRAMs are examined. The MBU response is shown to depend on the orientation of the device during irradiation. The response depends on the direction of the incident ion to the n- and p-wells of the SRAM. The MBU response is simulated using Monte Carlo methods for a space environment. The probability is calculated for event size. Single-bit upsets in the space environment account for 90% of all events with exponentially decreasing probabilities of larger MBU events.

A comparison of two scrubbing mitigation schemes for Xilinx field programmable gate array (FPGA) devices is presented. The design of the scrubbers is briefly discussed along with an examination of mitigation limitations. Heavy ion data are then presented and analyzed.

As sub-100 nm CMOS technologies gather interest, the radiation effects performance of these technologies provide a significant challenge. In this paper, we shall discuss the radiation testing challenges as related to commercial memory devices. The focus will be on complex test and failure modes emerging in state-of-the-art flash non-volatile memories (NVMs) and synchronous dynamic random access memories (SDRAMs), which are volatile. Due to their very high bit density, these device types are highly desirable for use in the natural space environment. In this paper, we shall discuss these devices with emphasis on considerations for test and qualification methods required.

We present guidelines to reduce risk to an acceptable level when using complex devices in space applications. An example of application for the use of Virtex 4 field programmable gate array (FPGA) on express logistic carrier(ELC) project is presented.

The RADSAFE simulation framework is described and applied to model SEU in a 0.25 mum CMOS 4 Mbit SRAM. For this circuit, the RADSAFE approach produces trends similar to those expected from classical rectangular parallelepiped models, but more closely represents the physical mechanisms responsible for SEU in the SRAM circuit.

In order to investigate frequency and architectural effects on Single Event Upset cross sections within RTAX-S FPGA devices, a novel approach to high speed testing is implemented. Testing was performed at variable speeds ranging from 15 MHz to 150 MHz

An advanced commercial 2Gbit NAND flash memory (90 nm technology, one bit/cell) has been characterized for TID and heavy ion SEE. Results are qualitatively similar to previous flash results in most respects, but we also detected a new dynamic failure mode

This paper describes application of the pulsed laser approach for identifying latch-up sensitive regions in CMOS circuitry. The utility of this approach for preliminary latchup screening of both COTS and space-qualified parts for applications in radiation environments is described. An application of hardening-by-design principles in which a space qualified CMOS product is modified, based on the pulsed laser results, to be latchup immune is presented in detail. The design modifications are described.

SEE testing at multi-Gbit/s data rates has traditionally involved elaborate high speed test equipment setups for at-speed testing. We demonstrate a generally applicable self test circuit approach implemented in IBM's 5AM SiGe process, and describe its ability to capture complex error signatures during circuit operation at data rates exceeding 5 Gbit/s. Comparisons of data acquired with FPGA control of the CREST ASIC versus conventional bit error rate test equipment validate the approach. In addition, we describe SEE characteristics of the IBM 5AM process implemented in five variations of the D flip-flop based serial register. Heavy ion SEE data acquired at angles follow the traditional RPP-based analysis approach in one case, but deviate by orders on magnitude in others, even though all circuits are implemented in the same 5AM SiGe HBT process.

Simulations show that neglecting ion-ion interaction processes (both particles having Z>1) results in an underestimation of the total on-orbit single event upset error rate by more than two orders of magnitude for certain technologies. The inclusion of ion-ion nuclear reactions leads to dramatically different SEU error rates for CMOS devices containing high Z materials compared with direct ionization by the primary ion alone. Device geometry and material composition have a dramatic effect on charge deposition in small sensitive volumes for the spectrum of ion energies found in space, compared with the limited range of energies typical of ground tests.

The performance of Michigan State University's Single-Event Effects Test Facility (SEETF) during its inaugural runs is evaluated. Beam profiles and other diagnostics are presented, and prospects for future development and testing are discussed.

We describe a stand-alone experiment with autonomous error checking and logging used to acquire proton-induced bit error response of a 10 Gb/s multimode fiber optic data link operating over a 100-m fiber length. Comparisons with previously tested lower data rate data links indicate the primary source of bit errors arise in the link receiver's photodiode. The serial 10 Gb/s results show relatively lower bit error rate (BER) sensitivity to 63 MeV protons. Proton BER results of supporting high-speed bipolar multiplexer and demultiplexer circuitry are also presented.

Combining broad-beam circuit level single-event upset (SEU) response with heavy ion microprobe charge collection measurements on single silicon-germanium heterojunction bipolar transistors improves understanding of the charge collection mechanisms responsible for SEU response of digital SiGe HBT technology. This new understanding of the SEU mechanisms shows that the right rectangular parallel-piped model for the sensitive volume is not applicable to this technology. A new first-order physical model is proposed and calibrated with moderate success.

Historically, proton-induced single-event effects (SEES) ground test data are collected independent of the orientation of the microelectronic device to the proton beam direction. In this study, we present experimental and simulation evidence that shows an effect of over an order of magnitude on the proton-induced single-event upset (SEU) cross section when the angle of incidence of the proton beam is varied. The magnitude of this effect is shown to depend on the incidence proton energy and the device critical charge. The angular effect is demonstrated for Silicon-On-Sapphire and Silicon-On-Insulator technologies, but would not necessarily be limited to these technologies.

Assessing the risk of using optocouplers in satellite applications offers challenges that incorporate those of commercial off-the-shelf devices compounded by hybrid module construction techniques. We discuss approaches for estimating this risk. In the process, we benchmark our estimates for proton and heavy-ion induced single-event transient rate estimates with recent flight data from the Terra mission. For parametric degradation, we discuss a method for acquiring test data and mapping it into an estimation approach that captures all the important variables of circuit application, environment, damage energy dependence, complex response to total ionizing dose and displacement effects, temperature, and annealing.

We present single-event transient (SET) test data on linear devices under many operational conditions in an attempt to understand the SET generation and characteristics. This is done in an attempt to define a low-cost conservative test methodology to characterize these effects. Heavy ion and laser irradiation test results are reported for a variety of bipolar analog integrated circuits.

We measure the energy dependence of proton-induced LED degradation using large numbers of devices and incremental exposures to gain high confidence in the proton energy dependence and device-to-device variability of damage. We compare single versus double heterojunction AlGaAs technologies (emitting at 880 nm and 830 nm, respectively) to previous experimental and theoretical results. We also present a critical review of the use of nonionizing energy loss in AlGaAs for predictions of on-orbit degradation and assess the uncertainties inherent in this approach.

We present a study of proton transient effects in metal-semiconductor-metal (MSM) photodetectors, which demonstrates their inherent advantage for minimizing Single Event Effects (SEEs) in proton environments. Upset mechanisms are characterized for 830 nm GaAs and 1300 nm InGaAs detectors. Only protons incident at grazing angles are likely to cause bit errors by direct ionization. The MSM technology appears to be a more robust to single bit errors than thicker 1300 nm p-i-n diode structures which we have previously shown to be susceptible to errors from direct ionization events at all angles, and also at relatively high optical powers. For a given receiver, the relative contributions of direct ionization and nuclear reaction upset mechanisms at a specific data rate and optical power are determined by the geometry of the charge collection volume of the detector. We show that state-of-the-art p-i-n detectors can also display a reduced sensitivity to direct ionization by incident protons except at grazing angles.

We present ground test and space flight data describing a single event anomaly that affects multiple bytes in a stacked DRAM module. A 12 Gbit solid state recorder containing 1,440 DRAM die experiences the anomalous events at a rate requiring testing of a large sample set of these modules.

Spacecraft performance requirements drive the utilization of commercial-off-the-shelf (COTS) components and emerging technologies in systems. The response of these technologies to radiation is often complex. This engenders a set of emerging radiation hardness assurance (RHA) issues which include displacement damage in optocouplers, high-precision and hybrid devices, enhanced low dose rate (ELDR) and proton damage enhancement (PDE) in linear circuits, linear transients, and catastrophic single event effects (SEEs) phenomena. NASA has developed an approach to designing reliable space systems which address these emerging RHA issues. This programmatic methodology includes hazard definition, hazard evaluation, requirements definition, evaluation of device usage, and application of radiation engineering techniques with the active involvement of designers. Risk assessment is an integral constituent in the approach as is an established program to assess future technology needs for programs.

We present a comparison of proton single event ground test results for two generations of MIL-STD-1773 fiber optic data bus interface modules. Single event upset rate prediction techniques for fiber optic data systems are also demonstrated and compared with in-flight space performance.