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Gamma radiation effects on passive silicon photonic waveguides using phase sensitive methods

Optics Express

Boynton, Nicholas; Gehl, M.; Dallo, Christina M.; Pomerene, Andrew P.; Starbuck, Andrew L.; Hood, Dana; Dodd, Paul E.; Swanson, Scot; Trotter, Douglas; DeRose, Christopher T.; Lentine, Anthony L.

Passive silicon photonic waveguides are exposed to gamma radiation to understand how the performance of silicon photonic integrated circuits is affected in harsh environments such as space or high energy physics experiments. The propagation loss and group index of the mode guided by these waveguides is characterized by implementing a phase sensitive swept-wavelength interferometric method. We find that the propagation loss associated with each waveguide geometry explored in this study slightly increases at absorbed doses of up to 100 krad (Si). The measured change in group index associated with the same waveguide geometries is negligibly changed after exposure. Additionally, we show that the post-exposure degradation of these waveguides can be improved through heat treatment.

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DFF Layout Variations in CMOS SOI -Analysis of Hardening by Design Options

IEEE Transactions on Nuclear Science

Black, Jeffrey B.; Black, Dolores A.; Domme, Nicholas A.; Dodd, Paul E.; Griffin, Patrick J.; Nowlin, R.N.; Trippe, James M.; Salas, Joseph G.; Reed, Robert A.; Weller, Robert A.; Tonigan, Andrew M.; Schrimpf, Ronald D.

Four D flip-flop (DFF) layouts were created from the same schematic in Sandia National Laboratories' CMOS7 silicon-on-insulator (SOI) process. Single-event upset (SEU) modeling and testing showed an improved response with the use of shallow (not fully bottomed) N-type metal-oxide-semiconductor field-effect transistors (NMOSFETs), extending the size of the drain implant and increasing the critical charge of the transmission gates in the circuit design and layout. This research also shows the importance of correctly modeling nodal capacitance, which is a major factor determining SEU critical charge. Accurate SEU models enable the understanding of the SEU vulnerabilities and how to make the design more robust.

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Using MRED to Screen Multiple-Node Charge-Collection Mitigated SOI Layouts

IEEE Transactions on Nuclear Science

Black, Jeffrey B.; Dame, Jeff A.; Black, Dolores A.; Dodd, Paul E.; Shaneyfelt, Marty R.; Teifel, John T.; Salas, Joseph G.; Steinbach, Robert; Davis, Matthew; Reed, Robert A.; Weller, Robert A.; Trippe, James M.; Warren, Kevin M.; Tonigan, Andrew M.; Schrimpf, Ronald D.; Marquez, Richard S.

Silicon-on-insulator latch designs and layouts that are robust to multiple-node charge collection are introduced. A general Monte Carlo radiative energy deposition (MRED) approach is used to identify potential single-event susceptibilities associated with different layouts prior to fabrication. MRED is also applied to bound single-event testing responses of standard and dual interlocked cell latch designs. Heavy ion single-event testing results validate new latch designs and demonstrate bounds for standard latch layouts.

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Understanding the Implications of a LINAC's Microstructure on Devices and Photocurrent Models

IEEE Transactions on Nuclear Science

McLain, Michael L.; McDonald, Joseph K.; Hembree, Charles E.; Sheridan, Timothy J.; Weingartner, Thomas A.; Dodd, Paul E.; Shaneyfelt, Marty R.; Hartman, Elmer F.; Black, Dolores A.

The effect of a linear accelerator's (LINAC's) microstructure (i.e., train of narrow pulses) on devices and the associated transient photocurrent models are investigated. The data indicate that the photocurrent response of Si-based RF bipolar junction transistors and RF p-i-n diodes is considerably higher when taking into account the microstructure effects. Similarly, the response of diamond, SiO2, and GaAs photoconductive detectors (standard radiation diagnostics) is higher when taking into account the microstructure. This has obvious hardness assurance implications when assessing the transient response of devices because the measured photocurrent and dose rate levels could be underestimated if microstructure effects are not captured. Indeed, the rate the energy is deposited in a material during the microstructure peaks is much higher than the filtered rate which is traditionally measured. In addition, photocurrent models developed with filtered LINAC data may be inherently inaccurate if a device is able to respond to the microstructure.

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Outstanding Conference Paper Award: 2015 IEEE Nuclear and Space Radiation Effects Conference

IEEE Transactions on Nuclear Science

Dodds, Nathaniel A.; Martinez, Marino M.; Dodd, Paul E.; Shaneyfelt, Marty R.; Sexton, Frederick W.; Black, Jeffrey B.; Lee, David S.; Swanson, Scot E.; Bhuva, B.L.; Warren, K.W.; Reed, R.A.; Trippe, J.M.; Sierawski, B.D.; Weller, R.A.; Mahatme, N.M.; Gaspard, N.G.; Assis, T.A.; Austin, R.A.; Weeden-Wright, S.L.; Massengill, L.M.; Swift, G.S.; Wirthlin, M.W.; Cannon, M.C.; Liu, R.L.; Chen, L.C.; Kelly, A.K.; Marshall, P.W.; Trinczek, M.C.; Blackmore, E.W.; Wen, S.-J.W.; Wong, R.W.; Narasimham, B.N.; Pellish, J.A.; Puchner, H.P.

This conference presents the recipients of the Outstanding Conference Paper Award from the 2015 IEEE Nuclear and Space Radiation Effects Conference.

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The Contribution of Low-Energy Protons to the Total On-Orbit SEU Rate

IEEE Transactions on Nuclear Science

Dodds, N.A.; Martinez, Marino M.; Dodd, Paul E.; Shaneyfelt, Marty R.; Sexton, Frederick W.; Black, J.D.; Lee, David S.; Swanson, Scot E.; Bhuva, B.L.; Warren, K.M.; Reed, R.A.; Trippe, J.; Sierawski, B.D.; Weller, R.A.; Mahatme, N.; Gaspard, N.J.; Assis, T.; Austin, R.; Weeden-Wright, S.L.; Massengill, L.W.; Swift, G.; Wirthlin, M.; Cannon, M.; Liu, R.; Chen, L.; Kelly, A.T.; Marshall, P.W.; Trinczek, M.; Blackmore, E.W.; Wen, S.J.; Wong, R.; Narasimham, B.; Pellish, J.A.; Puchner, H.

Low-and high-energy proton experimental data and error rate predictions are presented for many bulk Si and SOI circuits from the 20-90 nm technology nodes to quantify how much low-energy protons (LEPs) can contribute to the total on-orbit single-event upset (SEU) rate. Every effort was made to predict LEP error rates that are conservatively high; even secondary protons generated in the spacecraft shielding have been included in the analysis. Across all the environments and circuits investigated, and when operating within 10% of the nominal operating voltage, LEPs were found to increase the total SEU rate to up to 4.3 times as high as it would have been in the absence of LEPs. Therefore, the best approach to account for LEP effects may be to calculate the total error rate from high-energy protons and heavy ions, and then multiply it by a safety margin of 5. If that error rate can be tolerated then our findings suggest that it is justified to waive LEP tests in certain situations. Trends were observed in the LEP angular responses of the circuits tested. Grazing angles were the worst case for the SOI circuits, whereas the worst-case angle was at or near normal incidence for the bulk circuits.

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New Insights Gained on Mechanisms of Low-Energy Proton-Induced SEUs by Minimizing Energy Straggle

IEEE Transactions on Nuclear Science

Dodds, N.A.; Dodd, Paul E.; Shaneyfelt, Marty R.; Sexton, Frederick W.; Martinez, Marino M.; Black, J.D.; Marshall, P.W.; Reed, R.A.; McCurdy, M.W.; Weller, R.A.; Pellish, J.A.; Rodbell, K.P.; Gordon, M.S.

We present low-energy proton single-event upset (SEU) data on a 65 nm SOI SRAM whose substrate has been completely removed. Since the protons only had to penetrate a very thin buried oxide layer, these measurements were affected by far less energy loss, energy straggle, flux attrition, and angular scattering than previous datasets. The minimization of these common sources of experimental interference allows more direct interpretation of the data and deeper insight into SEU mechanisms. The results show a strong angular dependence, demonstrate that energy straggle, flux attrition, and angular scattering affect the measured SEU cross sections, and prove that proton direct ionization is the dominant mechanism for low-energy proton-induced SEUs in these circuits.

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New insights gained on mechanisms of low-energy proton-induced SEUs by minimizing energy straggle

IEEE Transactions on Nuclear Science

Dodds, Nathaniel A.; Dodd, Paul E.; Shaneyfelt, Marty R.; Sexton, Frederick W.; Martinez, Marino M.; Black, Jeffrey B.; Marshall, P.W.; Reed, R.A.; McCurdy, M.M.; Weller, R.A.; Pellish, J.A.; Rodbell, K.P.; Gordon, M.G.

In this study, we present low-energy proton single-event upset (SEU) data on a 65 nm SOI SRAM whose substrate has been completely removed. Since the protons only had to penetrate a very thin buried oxide layer, these measurements were affected by far less energy loss, energy straggle, flux attrition, and angular scattering than previous datasets. The minimization of these common sources of experimental interference allows more direct interpretation of the data and deeper insight into SEU mechanisms. The results show a strong angular dependence, demonstrate that energy straggle, flux attrition, and angular scattering affect the measured SEU cross sections, and prove that proton direct ionization is the dominant mechanism for low-energy proton-induced SEUs in these circuits.

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The contribution of low-energy protons to the total on-orbit SEU rate

IEEE Transactions on Nuclear Science

Dodds, Nathaniel A.; Martinez, Marino M.; Dodd, Paul E.; Shaneyfelt, Marty R.; Sexton, Frederick W.; Black, Jeffrey B.; Lee, David S.; Swanson, Scot E.; Bhuva, B.L.; Warren, K.W.; Reed, R.A.; Trippe, J.M.; Sierawski, B.D.; Weller, R.A.; Mahatme, N.M.; Gaspard, N.G.; Assis, T.A.; Austin, R.A.; Massengill, L.M.; Swift, G.S.; Wirthlin, M.W.; Cannon, M.C.; Liu, R.L.; Chen, L.C.; Kelly, A.K.; Marshall, P.W.; Trinczek, M.C.; Blackmore, E.W.; Wen, S.-J.W.; Wong, R.W.; Narasimham, B.N.; Pellish, J.A.; Puchner, H.P.

Low- and high-energy proton experimental data and error rate predictions are presented for many bulk Si and SOI circuits from the 20-90 nm technology nodes to quantify how much low-energy protons (LEPs) can contribute to the total on-orbit single-event upset (SEU) rate. Every effort was made to predict LEP error rates that are conservatively high; even secondary protons generated in the spacecraft shielding have been included in the analysis. Across all the environments and circuits investigated, and when operating within 10% of the nominal operating voltage, LEPs were found to increase the total SEU rate to up to 4.3 times as high as it would have been in the absence of LEPs. Therefore, the best approach to account for LEP effects may be to calculate the total error rate from high-energy protons and heavy ions, and then multiply it by a safety margin of 5. If that error rate can be tolerated then our findings suggest that it is justified to waive LEP tests in certain situations. Trends were observed in the LEP angular responses of the circuits tested. As a result, grazing angles were the worst case for the SOI circuits, whereas the worst-case angle was at or near normal incidence for the bulk circuits.

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The contribution of low-energy protons to the total on-orbit SEU rate

Dodds, Nathaniel A.; Martinez, Marino M.; Dodd, Paul E.; Shaneyfelt, Marty R.; Sexton, Frederick W.; Black, Jeffrey B.; Lee, David S.; Swanson, Scot E.; Bhuva, B.L.; Warren, K.W.; Reed, R.A.; Trippe, J.M.; Sierawski, B.D.; Weller, R.A.; Mahatme, N.M.; Gaspard, N.G.; Assis, T.A.; Austin, R.A.; Massengill, L.M.; Swift, G.S.; Wirthlin, M.W.; Cannon, M.C.; Liu, R.L.; Chen, L.C.; Kelly, A.K.; Marshall, P.W.; Trinczek, M.C.; Blackmore, E.W.; Wen, S.-J.W.; Wong, R.W.; Narasimham, B.N.; Pellish, J.A.; Puchner, H.P.

Abstract not provided.

Outstanding conference paper award 2014 IEEE nuclear and space radiation effects conference

IEEE Transactions on Nuclear Science

Dodds, Nathaniel A.; Dodds, Nathaniel A.; Schwank, James R.; Schwank, James R.; Shaneyfelt, Marty R.; Shaneyfelt, Marty R.; Dodd, Paul E.; Dodd, Paul E.; Doyle, Barney L.; Doyle, Barney L.; Trinczek, M.C.; Trinczek, M.C.; Blackmore, E.W.; Blackmore, E.W.; Rodbell, K.P.; Rodbell, K.P.; Reed, R.A.; Reed, R.A.; Pellish, J.A.; Pellish, J.A.; LaBel, K.A.; LaBel, K.A.; Marshall, P.W.; Marshall, P.W.; Swanson, Scot E.; Swanson, Scot E.; Vizkelethy, Gyorgy V.; Vizkelethy, Gyorgy V.; Van Deusen, Stuart B.; Van Deusen, Stuart B.; Sexton, Frederick W.; Sexton, Frederick W.; Martinez, Marino M.; Martinez, Marino M.

The recipients of the 2014 NSREC Outstanding Conference Paper Award are Nathaniel A. Dodds, James R. Schwank, Marty R. Shaneyfelt, Paul E. Dodd, Barney L. Doyle, Michael Trinczek, Ewart W. Blackmore, Kenneth P. Rodbell, Michael S. Gordon, Robert A. Reed, Jonathan A. Pellish, Kenneth A. LaBel, Paul W. Marshall, Scot E. Swanson, Gyorgy Vizkelethy, Stuart Van Deusen, Frederick W. Sexton, and M. John Martinez, for their paper entitled "Hardness Assurance for Proton Direct Ionization-Induced SEEs Using a High-Energy Proton Beam." For older CMOS technologies, protons could only cause single-event effects (SEEs) through nuclear interactions. Numerous recent studies on 90 nm and newer CMOS technologies have shown that protons can also cause SEEs through direct ionization. Furthermore, this paper develops and demonstrates an accurate and practical method for predicting the error rate caused by proton direct ionization (PDI).

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Hardness assurance for proton direct ionization-induced SEEs using a high-energy proton beam

IEEE Transactions on Nuclear Science

Dodds, N.A.; Schwank, James R.; Shaneyfelt, Marty R.; Dodd, Paul E.; Doyle, Barney L.; Trinczek, M.; Blackmore, E.W.; Rodbell, K.P.; Gordon, M.S.; Reed, R.A.; Pellish, J.A.; LaBel, K.A.; Marshall, P.W.; Swanson, Scot E.; Vizkelethy, Gyorgy V.; Van Deusen, Stuart B.; Sexton, Frederick W.; Martinez, Marino M.

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. We show that this angular dependence can be exploited to quickly assess whether an IC is susceptible to PDI.

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Mapping of radiation-induced resistance changes and multiple conduction channels in TaOx memristors

IEEE Transactions on Nuclear Science

Hughart, David R.; Pacheco, Jose L.; Lohn, Andrew L.; Mickel, Patrick R.; Bielejec, Edward S.; Vizkelethy, Gyorgy V.; Doyle, Barney L.; Wolfley, Steven L.; Dodd, Paul E.; Shaneyfelt, Marty R.; McLain, Michael L.; Marinella, Matthew J.

The locations of conductive regions in TaOx memristors are spatially mapped using a microbeam and Nanoimplanter by rastering an ion beam across each device while monitoring its resistance. Microbeam irradiation with 800 keV Si ions revealed multiple sensitive regions along the edges of the bottom electrode. The rest of the active device area was found to be insensitive to the ion beam. Nanoimplanter irradiation with 200 keV Si ions demonstrated the ability to more accurately map the size of a sensitive area with a beam spot size of 40 nm by 40 nm. Isolated single spot sensitive regions and a larger sensitive region that extends approximately 300 nm were observed.

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SOI substrate removal for SEE characterization: Techniques and applications

IEEE Transactions on Nuclear Science

Shaneyfelt, Marty R.; Schwank, James R.; Dodd, Paul E.; Stevens, Jeffrey S.; Vizkelethy, Gyorgy; Swanson, Scot E.; Dalton, Scott M.

Techniques for removing the back substrate of SOI devices are described for both packaged devices and devices at the die level. The use of these techniques for microbeam, heavy-ion, and laser testing are illustrated. © 2012 IEEE.

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Hardness assurance testing for proton direct ionization effects

Proceedings of the European Conference on Radiation and its Effects on Components and Systems, RADECS

Schwank, James R.; Shaneyfelt, Marty R.; Ferlet-Cavrois, Véronique; Dodd, Paul E.; Blackmore, Ewart W.; Pellish, Jonathan A.; Rodbell, Kenneth P.; Heidel, David F.; Marshall, Paul W.; LaBel, Kenneth A.; Gouker, Pascale M.; Tam, Nelson; Wong, Richard; Wen, Shi J.; Reed, Robert A.; Dalton, Scott M.; Swanson, Scot E.

The potential for using the degraded beam of high-energy proton radiation sources for proton hardness assurance testing for ICs that are sensitive to proton direct ionization effects are explored. SRAMs were irradiated using high energy proton radiation sources (∼67-70 MeV). The proton energy was degraded using plastic or Al degraders. Peaks in the SEU cross section due to direct ionization were observed. To best observe proton direct ionization effects, one needs to maximize the number of protons in the energy spectrum below the proton energy SEU threshold. SRIM simulations show that there is a tradeoff between increasing the fraction of protons in the energy spectrum with low energies by decreasing the peak energy and the reduction in the total number of protons as protons are stopped in the device as the proton energy is decreased. Two possible methods for increasing the number of low energy protons is to decrease the primary proton energy to reduce the amount of energy straggle and to place the degrader close to the DUT to minimize angular dispersion. These results suggest that high-energy proton radiation sources may be useful for identifying devices sensitive to proton direct ionization. © 2011 IEEE.

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A comprehensive understanding of the efficacy of N-ring SEE hardening methodologies in SiGe HBTs

IEEE Transactions on Nuclear Science

Phillips, Stan D.; Moen, Kurt A.; Najafizadeh, Laleh; Diestelhorst, Ryan M.; Sutton, Akil K.; Cressler, John D.; Vizkelethy, Gyorgy; Dodd, Paul E.; Marshall, Paul W.

We investigate the efficacy of mitigating radiation-based single event effects (SEE) within circuits incorporating SiGe heterojunction bipolar transistors (HBTs) built with an N-Ring, a transistor-level layout-based radiation hardened by design (RHBD) technique. Previous work of single-device ion-beam induced charge collection (IBICC) studies has demonstrated significant reductions in peak collector charge collection and sensitive area for charge collection; however, few circuit studies using this technique have been performed. Transient studies performed with Sandia National Laboratory's (SNL) 36 MeV 16O microbeam on voltage references built with N-Ring SiGe HBTs have shown mixed results, with reductions in the number of large voltage disruptions in addition to new sensitive areas of low-level output voltage disturbances. Similar discrepancies between device-level IBICC results and circuit measurements are found for the case of digital shift registers implemented with N-Ring SiGe HBTs irradiated in a broadbeam environment at Texas A&M's Cyclotron Institute. The error cross-section curve of the N-Ring based register is found to be larger at larger ion LETs than the standard SiGe register, which is clearly counter-intuitive. We have worked to resolve the discrepancy between the measured circuit results and the device-level IBICC measurements, by re-measuring single-device N-Ring SiGe HBTs using a time-resolved ion beam induced charge (TRIBIC) set-up that allows direct capture of nodal transients. Coupling these measurements with full 3-D TCAD simulations provides complete insight into the origin of transient currents in an N-Ring SiGe HBT. The detailed structure of these transients and their bias dependencies are discussed, together with the ramifications for the design of space-borne analog and digital circuits using SiGe HBTs. © 2010 IEEE.

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Design of digital circuits using inverse-mode cascode SiGe HBTs for single event upset mitigation

IEEE Transactions on Nuclear Science

Thrivikraman, Tushar K.; Wilcox, Edward; Phillips, Stanley D.; Cressler, John D.; Marshall, Cheryl; Vizkelethy, Gyorgy; Dodd, Paul E.; Marshall, Paul

We report on the design and measured results of a new SiGe HBT radiation hardening by design technique called the inverse-mode cascode (IMC). A third-generation SiGe HBT IMC device was tested in a time resolved ion beam induced charge collection (TRIBICC) system, and was found to have over a 75% reduction in peak current transients with the use of an n-Tiedown on the IMC sub-collector node. Digital shift registers in a 1st-generation SiGe HBT technology were designed and measured under a heavy-ion beam, and shown to increase the LET threshold over standard npn only shift registers. Using the CREME96 tool, the expected orbital bit-errors/day were simulated to be approximately 70% lower with the IMC shift register. These measured results help demonstrate the efficacy of using the IMC device as a low-cost means for improving the SEE radiation hardness of SiGe HBT technology without increasing area or power. © 2010 IEEE.

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Effects of moisture on radiation-induced degradation in CMOS SOI transistors

IEEE Transactions on Nuclear Science

Shaneyfelt, Marty R.; Schwank, James R.; Dodd, Paul E.; Hill, Thomas A.; Dalton, Scott M.; Swanson, Scot E.

The effects of moisture on radiation-induced charge buildup in the oxides of a 0.35 μSOI technology are explored. Data show no observable effects of moisture-related aging on radiation hardness. These results are in contrast to those of previous work performed on bulk MOS technologies fabricated in the 1980s. The cause of these differences do not appear to be due to differences in final chip passivation layers. Instead, other processing variables (e.g., thicker overlayers) may account for these differences. In any case, the SOI technology results indicate that not all advanced technologies exposed to moisture are necessarily susceptible to enhanced radiation-induced degradation. © 2010 IEEE.

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Hardness assurance test guideline for qualifying devices for use in proton environments

IEEE Transactions on Nuclear Science

Schwank, James R.; Shaneyfelt, Marty R.; Dodd, Paul E.; Felix, James A.; Baggio, J.; Ferlet-Cavrois, V.; Paillet, P.; Label, K.A.; Pease, R.L.; Simons, M.; Cohn, L.M.

Proton-induced singl -event effects hardness assurance guidelines are developed to address issues raised by recent test results in advanced IC technologies for use in space environments. Specifically, guidelines are developed that address the effects of proton energy and angle of incidence on single-event latchup and the effects of total dose on single-event upset. The guidelines address both single-event upset (SEU), single-event latchup (SEL), and combined SEU and total ionizing dose (TID) effects. © 2006 IEEE.

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SOI-Enabled MEMS Processes Lead to Novel Mechanical Optical and Atomic Physics Devices Presentation

Herrera, Gilbert V.; McCormick, Frederick B.; Nielson, Gregory N.; Nordquist, Christopher N.; Okandan, Murat O.; Olsson, Roy H.; Ortiz, Keith O.; Platzbecker, Mark R.; Resnick, Paul J.; Shul, Randy J.; Bauer, Todd B.; Sullivan, Charles T.; Watts, Michael W.; Blain, Matthew G.; Dodd, Paul E.; Dondero, Richard D.; Garcia, Ernest J.; Galambos, Paul; Hetherington, Dale L.; Hudgens, James J.

Abstract not provided.

SOI-Enabled MEMS Processes Lead to Novel Mechanical Optical and Atomic Physics Devices

Herrera, Gilbert V.; McCormick, Frederick B.; Nielson, Gregory N.; Nordquist, Christopher N.; Okandan, Murat O.; Olsson, Roy H.; Ortiz, Keith O.; Platzbecker, Mark R.; Resnick, Paul J.; Shul, Randy J.; Bauer, Todd B.; Sullivan, Charles T.; Watts, Michael W.; Blain, Matthew G.; Dodd, Paul E.; Dondero, Richard D.; Garcia, Ernest J.; Galambos, Paul; Hetherington, Dale L.; Hudgens, James J.

Abstract not provided.

Effects of total dose irradiation on single-event upset hardness

IEEE Transactions on Nuclear Science

Schwank, James R.; Shaneyfelt, Marty R.; Felix, James A.; Dodd, Paul E.; Baggio, J.; Ferlet-Cavrois, V.; Paillet, P.; Hash, Gerald L.; Flores, Richard S.; Massengill, L.W.; Blackmore, E.

The effect of total dose on SEU hardness is investigated as a function of temperature and power supply voltage to determine worst-case hardness assurance test conditions for space environments. SRAMs from six different vendors were characterized for single-event upset (SEU) hardness at proton energies from 20 to 500 MeV and at temperatures of 25 and 80°C after total dose irradiating the SRAMs with either protons, Co-60 gamma rays, or low-energy x-rays. It is shown that total dose irradiation and the memory pattern written to the memory array during total dose irradiation and SEU characterization can substantially affect SEU hardness for some SRAMs. For one SRAM, the memory pattern made more than two orders of magnitude difference in SEU cross section at the highest total dose level examined. For all SRAMs investigated, the memory pattern that led to the largest increase in SEU cross section was the same memory pattern that led to the maximum increase in total-dose induced power supply leakage current. In addition, it is shown that increasing the temperature during SEU characterization can also increase the effect of total dose on SEU hardness. As a result, worst-case SEU hardness assurance test conditions are the maximum total dose and temperature of the system environment, and the minimum operating voltage of the SRAM. Possible screens for determining whether or not the SEU cross section of an SRAM will vary with total dose, based on the magnitude of the increase in power supply leakage current with total dose or the variation in SEU cross section with power supply voltage, have been suggested. In contrast to previous works, our results using selective area x-ray irradiations show that the source of the effect of total dose on SEU hardness is radiation-induced leakage currents in the memory cells. The increase in SEU cross section with total dose appears to be consistent with radiation-induced currents originating in the memory cells affecting the output bias levels of bias level shift circuitry used to control the voltage levels to the memory cells and/or due to the lowering of the noise margin of individual memory cells caused by radiation-induced leakage currents. © 2006 IEEE.

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Elimination of enhanced low-dose-rate sensitivity in linear bipolar devices using silicon-carbide passivation

IEEE Transactions on Nuclear Science

Shaneyfelt, Marty R.; Maher, Michael C.; Camilletti, Robert C.; Schwank, James R.; Pease, Ronald L.; Russell, Brian A.; Dodd, Paul E.

The type of final chip passivation layer used to fabricate linear bipolar circuits can have a major impact on the total dose hardness of some circuits. It is demonstrated that National Semiconductor Corporation linear bipolar devices fabricated with only an amorphous silicon carbide passivation layer do not exhibit enhanced low-dose-rate sensitivity (ELDRS), while devices from the same production lot fabricated with other types of passivation layers are ELDRS sensitive. SiC passivation possesses mechanical, electrical and chemical properties that make it compatible with linear device fabrication processes. These properties of SiC passivation layers, combined with the excellent radiation response of devices passivated with SiC, make SiC passivation layers a very attractive choice for devices packaged in either ceramic or plastic-encapsulated packages for use in space environments. © 2006 IEEE.

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Effects of particle energy on proton-induced single-event latchup

IEEE Transactions on Nuclear Science

Schwank, James R.; Shaneyfelt, Marty R.; Baggio, J.; Dodd, Paul E.; Felix, James A.; Ferlet-Cavrois, V.; Paillet, P.; Lambert, D.; Sexton, Frederick W.; Hash, Gerald L.; Blackmore, E.

The effect of proton energy on single-event latchup (SEL) in present-day SRAMs is investigated over a wide range of proton energies and temperature. SRAMs from five different vendors were irradiated at proton energies from 20 to 500 MeV and at temperatures of 25° and 85°C. For the SRAMs and radiation conditions examined in this work, proton energy SEL thresholds varied from as low as 20 MeV to as high as 490 MeV. To gain insight into the observed effects, the heavy-ion SEL linear energy transfer (LET) thresholds of the SRAMs were measured and compared to high-energy transport calculations of proton interactions with different materials. For some SRAMs that showed proton-induced SEL, the heavy-ion SEL threshold LET was as high as 25 MeV-cm 2/mg. Proton interactions with Si cannot generate nuclear recoils with LETs this large. Our nuclear scattering calculations suggest that the nuclear recoils are generated by proton interactions with tungsten. Tungsten plugs are commonly used in most high-density ICs fabricated today, including SRAMs. These results demonstrate that for system applications where latchups cannot be tolerated, SEL hardness assurance testing should be performed at a proton energy at least as high as the highest proton energy present in the system environment. Moreover, the best procedure to ensure that ICs will be latchup free in proton environments may be to use a heavy-ion source with LETs ≥40 MeV-cm 2/mg. © 2005 IEEE.

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Radiation-induced off-state leakage current in commercial power MOSFETs

Proposed for publication in the IEEE Transactions on Nuclear Science.

Felix, James A.; Shaneyfelt, Marty R.; Dodd, Paul E.; Draper, Bruce L.; Schwank, James R.; Dalton, Scott D.

The total dose hardness of several commercial power MOSFET technologies is examined. After exposure to 20 krad(SiO{sub 2}) most of the n- and p-channel devices examined in this work show substantial (2 to 6 orders of magnitude) increases in off-state leakage current. For the n-channel devices, the increase in radiation-induced leakage current follows standard behavior for moderately thick gate oxides, i.e., the increase in leakage current is dominated by large negative threshold voltage shifts, which cause the transistor to be partially on even when no bias is applied to the gate electrode. N-channel devices biased during irradiation show a significantly larger leakage current increase than grounded devices. The increase in leakage current for the p-channel devices, however, was unexpected. For the p-channel devices, it is shown using electrical characterization and simulation that the radiation-induced leakage current increase is related to an increase in the reverse bias leakage characteristics of the gated diode which is formed by the drain epitaxial layer and the body. This mechanism does not significantly contribute to radiation-induced leakage current in typical p-channel MOS transistors. The p-channel leakage current increase is nearly identical for both biased and grounded irradiations and therefore has serious implications for long duration missions since even devices which are usually powered off could show significant degradation and potentially fail.

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Identification of radiation-induced parasitic leakage paths using light emission microscopy

IEEE Transactions on Nuclear Science

Shaneyfelt, Marty R.; Tangyunyong, Paiboon T.; Hill, Thomas A.; Soden, Jerry M.; Flores, Richard S.; Schwank, James R.; Dodd, Paul E.; Hash, Gerald L.

Eliminating radiation-induced parasitic leakage paths in integrated circuits (ICs) is key to improving their total dose hardness. Semiconductor manufacturers can use a combination of design and/or process techniques to eliminate known radiation-induced parasitic leakage paths. However, unknown or critical radiation-induced parasitic leakage may still exist on fully processed ICs and it is extremely difficult (if not impossible) to identify these leakage paths based on radiation induced parametric degradation. We show that light emission microscopy can be used to identify the location of radiation-induced parasitic leakage paths in ICs. This is illustrated by using light emission microscopy to find radiation-induced parasitic leakage paths in partially-depleted silicon on insulator static random-access memories (SRAMs). Once leakage paths were identified, modifications were made to the SRAM design to improve the total dose radiation hardness of the SRAMs. Light emission microscopy should prove to be an important tool for the development of future radiation hardened technologies and devices.

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Radiation effects microscopy for failure analysis of microelectronic devices

Doyle, Barney L.; Dodd, Paul E.; Shaneyfelt, Marty R.; Schwank, James R.

Microelectronic devices in satellites and spacecraft are exposed to high energy cosmic radiation. Furthermore, Earth-based electronics can be affected by terrestrial radiation. The radiation causes a variety of Single Event Effects (SEE) that can lead to failure of the devices. High energy heavy ion beams are being used to simulate both the cosmic and terrestrial radiation to study radiation effects and to ensure the reliability of electronic devices. Broad beam experiments can provide a measure of the radiation hardness of a device (SEE cross section) but they are unable to pinpoint the failing components in the circuit. A nuclear microbeam is an ideal tool to map SEE on a microscopic scale and find the circuit elements (transistors, capacitors, etc.) that are responsible for the failure of the device. In this paper a review of the latest radiation effects microscopy (REM) work at Sandia will be given. Different SEE mechanisms (Single Event Upset, Single Event Transient, etc.) and the methods to study them (Ion Beam Induced Charge (IBIC), Single Event Upset mapping, etc.) will be discussed. Several examples of using REM to study the basic effects of radiation in electronic devices and failure analysis of integrated circuits will be given.

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3-D Simulation of Heavy-Ion Induced Charge Collection in SiGe HBTs

IEEE Transactions on Nuclear Science

Varadharajaperumal, Muthubalan; Niu, Guofu; Krithivasan, Ramkumar; Cressler, John D.; Reed, Robert A.; Marshall, Paul W.; Vizkelethy, Gyorgy; Dodd, Paul E.; Joseph, Alvin J.

This paper presents the first 3-D simulation of heavy-ion induced charge collection in a SiGe HBT, together with microbeam testing data. The charge collected by the terminals is a strong function of the ion striking position. The sensitive area of charge collection for each terminal is identified based on analysis of the device structure and simulation results. For a normal strike between the deep trench edges, most of the electrons and holes are collected by the collector and substrate terminals, respectively. For an ion strike between the shallow trench edges surrounding the emitter, the base collects appreciable amount of charge. Emitter collects negligible amount of charge. Good agreement is achieved between the experimental and simulated data. Problems encountered with mesh generation and charge collection simulation are also discussed.

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Heavy-Ion Broad-Beam and Microprobe Studies of Single-Event Upsets in 0.20-μm SiGe Heterojunction Bipolar Transistors and Circuits

IEEE Transactions on Nuclear Science

Reed, Robert A.; Marshall, Paul W.; Pickel, James C.; Carts, Martin A.; Fodness, Bryan; Niu, Guofu; Fritz, Karl; Vizkelethy, Gyorgy; Dodd, Paul E.; Irwin, Tim; Cressler, John D.; Krithivasan, Ramkumar; Riggs, Pamela; Prairie, Jason; Randall, Barbara; Gilbert, Barry; LaBel, Kenneth A.

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 parallele-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.

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Improved capabilities for proton and neutron irradiations at TRIUMF

Shaneyfelt, Marty R.; Dodd, Paul E.; Shaneyfelt, Marty R.

Improvements have been made at TRIUMF to permit higher proton intensities of up to 10{sup 10} cm{sup -2}s{sup -1} over the energy range 20-500 MeV. This improved capability enables the study of displacement damage effects that require higher fluence irradiations. In addition, a high energy neutron irradiation capability has been developed for terrestrial cosmic ray soft error rate (SER) characterization of integrated circuits. The neutron beam characteristics of this facility are similar to those currently available at the Los Alamos National Laboratory WNR test facility. SER data measured on several SRAMs using the TRIUMF neutron beam are in good agreement with the results obtained on the same devices using the WNR facility. The TRIUMF neutron beam also contains thermal neutrons that can be easily removed by a sheet of cadmium. The ability to choose whether thermal neutrons are present is a useful attribute not possible at the WNR.

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Radiation-induced charge trapping in thin Al2O3/SiOxNy/Si(100) gate dielectric stacks

Proposed for publication in IEEE Transactions on Nuclear Science.

Felix, James A.; Shaneyfelt, Marty R.; Meisenheimer, Timothy L.; Schwank, James R.; Dodd, Paul E.

We examine the total-dose radiation response of capacitors and transistors with stacked Al{sub 2}O{sub 3} on oxynitride gate dielectrics with Al and poly-Si gates after irradiation with 10 keV X-rays. The midgap voltage shift increases monotonically with dose and depends strongly on both Al{sub 2}O{sub 3} and SiO{sub x}N{sub y} thickness. The thinnest dielectrics, of most interest to industry, are extremely hard to ionizing irradiation, exhibiting only {approx}50 mV of shift at a total dose of 10 Mrad(SiO{sub 2}) for the worst case bias condition. Oxygen anneals are found to improve the total dose radiation response by {approx}50% and induce a small amount of capacitance-voltage hysteresis. Al{sub 2}O{sub 3}/SiO{sub x}N{sub y} dielectrics which receive a {approx}1000 C dopant activation anneal trap {approx}12% more of the initial charge than films annealed at 550 C. Charge pumping measurements show that the interface trap density decreases with dose up to 500 krad(SiO{sub 2}). This surprising result is discussed with respect to hydrogen effects in alternative dielectric materials, and may be the result of radiation-induced hydrogen passivation of some of the near-interfacial defects in these gate dielectrics.

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Passivation layers for reduced total dose effects and ELDRS in linear bipolar devices

Proposed for publication in IEEE Transactions on Nuclear Science.

Shaneyfelt, Marty R.; Schwank, James R.; Dodd, Paul E.; Riewe, Leonard C.

It is shown that final chip passivation layers can have a significant impact on total dose hardness. A number of final chip passivation layers are evaluated to identify films that mitigate enhanced low-dose-rate sensitivity (ELDRS) in National Semiconductor Corporation's linear bipolar technologies. It is shown that devices fabricated with either a low temperature oxide or a tetraethyl ortho silicate passivation do not exhibit significant ELDRS effects up to 100 krad(SiO{sub 2}). Passivation studies on CMOS SRAMs suggest that it is unlikely that the passivation layers (or processing tools) are acting as a new source of hydrogen, which could drift or diffuse into the oxide and increase ELDRS sensitivity. Instead, it is possible that the passivation layers affect the mechanical stress in the oxide, which may affect oxide trap properties and possibly the release and mobility of hydrogen. Correlations between mechanical stress induced by the passivation layers and radiation degradation are discussed.

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Radiation effects in SOI technologies

IEEE Transactions on Nuclear Science

Schwank, James R.; Ferlet-Cavrois, V.; Shaneyfelt, Marty R.; Paillet, P.; Dodd, Paul E.

Silicon-on-insulator (SOI) technologies have been developed for radiation-hardened applications for many years and are rapidly becoming a main-stream commercial technology. The authors review the total dose, single-event effects, and dose rate hardness of SOI devices. The total dose response of SOI devices is more complex than for bulk-silicon devices due to the buried oxide. Radiation-induced trapped charge in the buried oxide can increase the leakage current of partially depleted transistors and decrease the threshold voltage and increase the leakage current of fully depleted transistors. Process techniques that reduce the net amount of radiation-induced positive charge trapped in the buried oxide and device design techniques that mitigate the effects of trapped charge in the buried oxide have been developed to harden SOI devices to bulk-silicon device levels. The sensitive volume for charge collection in SOI technologies is much smaller than for bulk-silicon devices potentially making SOI devices much harder to single-event upset (SEU). However, bipolar amplification caused by floating body effects can significantly reduce the SEU hardness of SOI devices. Body ties are used to reduce floating body effects and improve SEU hardness. SOI ICs are completely immune to classic four-layer p-n-p-n single-event latchup; however, floating body effects make SOI ICs susceptible to single-event snapback (single transistor latch). The sensitive volume for dose rate effects is typically two orders of magnitude lower for SOI devices than for bulk-silicon devices. By using body ties to reduce bipolar amplification, much higher dose rate upset levels can be achieved for SOI devices than for bulk-silicon devices.

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Radiation-Induced Prompt Photocurrents in Microelectronics: Physics

Dodd, Paul E.; Walsh, David S.; Buller, Daniel L.; Doyle, Barney L.

The effects of photocurrents in nuclear weapons induced by proximal nuclear detonations are well known and remain a serious hostile environment threat for the US stockpile. This report describes the final results of an LDRD study of the physical phenomena underlying prompt photocurrents in microelectronic devices and circuits. The goals of this project were to obtain an improved understanding of these phenomena, and to incorporate improved models of photocurrent effects into simulation codes to assist designers in meeting hostile radiation requirements with minimum build and test cycles. We have also developed a new capability on the ion microbeam accelerator in Sandia's Ion Beam Materials Research Laboratory (the Transient Radiation Microscope, or TRM) to supply ionizing radiation in selected micro-regions of a device. The dose rates achieved in this new facility approach those possible with conventional large-scale dose-rate sources at Sandia such as HERMES III and Saturn. It is now possible to test the physics and models in device physics simulators such as Davinci in ways not previously possible. We found that the physical models in Davinci are well suited to calculating prompt photocurrents in microelectronic devices, and that the TRM can reproduce results from conventional large-scale dose-rate sources in devices where the charge-collection depth is less than the range of the ions used in the TRM.

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Long-term reliability degradation of ultrathin dielectric films due to heavy-ion irradiation

IEEE Transactions on Nuclear Science

Schwank, James R.; Shaneyfelt, Marty R.; Meisenheimer, Timothy L.; Dodd, Paul E.

High-energy ion-irradiated 3.3-nm oxynitride film and 2.2-nm SiO2-film MOS capacitors show premature breakdown during subsequent electrical stress. This degradation in breakdown increases with increasing ion linear energy transfer (LET), increasing ion fluence, and decreasing oxide thickness. We explain the reliability degradation due to high-energy ion-induced latent defects by a simple percolation model of conduction through SiO2 layers with irradiation and/or electrical stress-induced defects. Monitoring the gate-leakage current reveals the presence of latent defects in the dielectric films. Finally, our results may be significant to future single-event effects and single-event gate rupture tests for MOS devices and ICs with ultrathin gate oxides.

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Investigation of body-tie effects on ion beam induced charge collection in silicon-on-insulator FETs using the Sandia nuclear microprobe

Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms

Walsh, David S.; Dodd, Paul E.; Shaneyfelt, Marty R.; Schwank, James R.

Silicon-on-insulator (SOI) technology exhibits three main advantages over bulk silicon technology for use in radiation environments. (1) SOI devices are immune to latchup, (2) the volume of the sensitive region (body) and hence total charge collection per transient irradiation is much reduced in SOI devices and (3) the insulating layer blocks charge collection from the substrate (i.e., no funneling effect). This effectively raises the single event upset (SEU) threshold for the SOI device. However, despite their small active volume SOI devices are still vulnerable to single event effects (SEE). Inherent in the SOI transistor design is a parasitic npn bipolar junction transistor (BJT), where the source-body-drain acts as an emitter-base-collector BJT. An ion strike to a floating (not referenced to a specific potential) body creates a condition where the excess minority carriers in the drain-body cause the parasitic BJT to turn on and inject more charge into the drain than was deposited in the device by the ion. In extreme cases the floating body effect (FBE) can trigger a high-current state called single-event snapback (SES) where channel conduction is sustained indefinitely through regenerative electron-impact ionization near the drain junction. Tying the body to the source limits the emitter-base current and reduces the sensitivity of the device to single ion strikes. Unfortunately, the body-tie loses effectiveness with distance due to resistivity, and in regions far enough from the tie the BJT is still in effect. Using the Sandia nuclear microprobe we have created charge collection maps on Sandia CMOS6rs SOI FETs of varying channel widths. These devices have body ties at both ends of the channel region. Results clearly demonstrate that distance of the ion strike from the body tie has an inverse effect upon charge collection and SES sensitivity due to the resistivity of the channel. Experimental results compare well with DAVINCI simulations and electrically induced snapback thresholds. In addition, an intere sting saturation effect of SES versus the amount of injected charge is observed. © 2001 Elsevier Science B.V. All rights reserved.

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Single-Event Upset and Snapback in Silicon-on-Insulator Devices and Integrated Circuits

IEEE Transactions on Nuclear Science

Dodd, Paul E.; Shaneyfelt, Marty R.; Walsh, David S.; Schwank, James R.; Hash, Gerald L.; Jones, Rhonda L.; Draper, Bruce L.; Winokur, Peter S.

The characteristics Of ion-induced charge collection and single-event upset are studied in SOI transistors and circuits with various body tie structures. Impact ionization effects including single-event snapback are shown to be very important. Focused ion microbeam experiments are used to find single-event snapback drain voltage thresholds in n-channel SOI transistors as a function of device width. Three-Dimensional device simulations are used to determine single-event upset and snapback thresholds in SOI SRAMS, and to study design tradeoffs for various body-tie structures. A window of vulnerability to single-event snapback is shown to exist below the single-event upset threshold. The presence of single-event snapback in commercial SOI SRAMS is confirmed through broadbeam ion testing, and implications for hardness assurance testing of SOI integrated circuits are discussed.

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Time resolved ion beam induced charge collection

Sexton, Frederick W.; Walsh, David S.; Doyle, Barney L.; Dodd, Paul E.

Under this effort, a new method for studying the single event upset (SEU) in microelectronics has been developed and demonstrated. Called TRIBICC, for Time Resolved Ion Beam Induced Charge Collection, this technique measures the transient charge-collection waveform from a single heavy-ion strike with a {minus}.03db bandwidth of 5 GHz. Bandwidth can be expanded up to 15 GHz (with 5 ps sampling windows) by using an FFT-based off-line waveform renormalization technique developed at Sandia. The theoretical time resolution of the digitized waveform is 24 ps with data re-normalization and 70 ps without re-normalization. To preserve the high bandwidth from IC to the digitizing oscilloscope, individual test structures are assembled in custom high-frequency fixtures. A leading-edge digitized waveform is stored with the corresponding ion beam position at each point in a two-dimensional raster scan. The resulting data cube contains a spatial charge distribution map of up to 4,096 traces of charge (Q) collected as a function of time. These two dimensional traces of Q(t) can cover a period as short as 5 ns with up to 1,024 points per trace. This tool overcomes limitations observed in previous multi-shot techniques due to the displacement damage effects of multiple ion strikes that changed the signal of interest during its measurement. This system is the first demonstration of a single-ion transient measurement capability coupled with spatial mapping of fast transients.

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Correlation between Co-60 and x-ray exposures on radiation-induced charge buildup in silicon-on-insulator buried oxides

Schwank, James R.; Shaneyfelt, Marty R.; Jones, Rhonda L.; Draper, Bruce L.; Dodd, Paul E.; Witczak, Steven C.; Riewe, Leonard C.

Large differences in charge buildup in SOI buried oxides can result between x-ray and Co-60 irradiations. The effects of bias configuration and substrate type on charge buildup and hardness assurance issues are explored.

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