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Graphene's linear band structure and two-dimensional density of states provide an implicit advantage for sensing charge. Here, these advantages are leveraged in a deeply depleted graphene–oxide–semiconductor ( D 2 GOS) junction detector architecture to sense carriers created by ionizing radiation. Specifically, the room temperature response of a silicon-based D 2 GOS junction is analyzed during irradiation with 20 MeV S i 4 + ions. Detection was demonstrated for doses ranging from 12 to 1200 ions with device functionality maintained with no substantive degradation. To understand the device response, D 2 GOS pixels were characterized post-irradiation via a combination of electrical characterization, Raman spectroscopy, and photocurrent mapping. This combined characterization methodology underscores the lack of discernible damage caused by irradiation to the graphene while highlighting the nature of interactions between the incident ions and the silicon absorber. [ABSTRACT FROM AUTHOR]

As device dimensions decrease, single displacement effects become more important. We measured the gain degradation in III–V heterojunction bipolar transistors due to single particles using a heavy ion microbeam. Two devices with different sizes were irradiated with various ion species ranging from oxygen to gold to study the effect of the irradiation ion mass on gain change. From the single steps in the inverse gain (which is proportional to the number of defects), we calculated cumulative distribution functions to help determine design margins. The displacement process was modeled using the MARLOWE binary collision approximation code. The entire structure of the device was modeled and the defects in the base–emitter junction were counted to be compared with the experimental results. While we found good agreement for the large device, we had to modify our model to reach reasonable agreement for the small device. [ABSTRACT FROM PUBLISHER]

Displacement damage caused by ions or neutrons in microelectronic devices can have significant effect on the performance of these devices. Therefore, it is important to predict not only the displacement damage profile, but also its magnitude precisely. Analytical methods and binary collision approximation codes working with amorphous targets use the concept of displacement energy, the energy that a lattice atom has to receive to create a permanent replacement. It was found that this “displacement energy” is direction dependent; it can range from 12 to 32 eV in silicon. Obviously, this model fails in BCA codes that work with crystalline targets, such as Marlowe. Marlowe does not use displacement energy; instead, it uses lattice binding energy only and then pairs the interstitial atoms with vacancies. Then based on the configuration of the Frenkel pairs it classifies them as close, near, or distant pairs, and considers the distant pairs the permanent replacements. Unfortunately, this separation is an ad hoc assumption, and the results do not agree with molecular dynamics calculations. After irradiation, there is a prompt recombination of interstitials and vacancies if they are nearby, within a recombination radius. In order to implement this recombination radius in Marlowe, we used the comparison of MD and Marlowe calculation in a range of ion energies in single crystal silicon target. The calculations showed that a single recombination radius of ∼7.4 Å in Marlowe for a range of ion energies gives an excellent agreement with MD. [ABSTRACT FROM AUTHOR]

Abstract: Ion Beam Induced Charge (IBIC) is the basic mechanism of the operation of semiconductor detectors and it can lead to Single Event Effects (SEEs) in microelectronic devices. To be able to predict SEEs in ICs and detector responses one needs to be able to simulate the radiation-induced current as the function of time on the electrodes of the devices and detectors. There are analytical models, which work for very simple detector configurations, but fail for anything more complex. Technology Computer Aided Design (TCAD) programs can simulate this process in microelectronic devices, but these TCAD codes costs hundreds of thousands of dollars and they require huge computing resources. In addition, in certain cases they fail to predict the correct behavior. Here a simulation model based on the Gunn theorem was developed and used with the COMSOL Multiphysics framework, version 3.5. In the model, the induced current can be calculated both directly and in certain cases using the powerful adjoint method. A brief description of the model will be given in the paper with examples for detectors and microelectronic devices using both the direct and the adjoint method. [Copyright &y& Elsevier]

Abstract: The motion of ionizing-radiation-induced rogue charge carriers in a semiconductor can create unwanted voltage and current conditions within a microelectronic circuit. If sufficient unwanted charge or current occurs on a sensitive node, a variety of single event effects (SEEs) can occur with consequences ranging from trivial to catastrophic. This paper describes the application of heavy ion microprobes to assist with calibration and validation of SEE modeling approaches. [Copyright &y& Elsevier]

Abstract: Model experiments were performed on MOS (metal-oxide semiconductor) capacitors to study ion beam induced charge generation in silicon-on-insulator (SOI) devices. Surprisingly large induced charge was found and a lateral non-uniformity of the induced charge was discovered across the top electrode of the capacitor. In this paper we will give a simple model for the charge induction in MOS structures and an explanation of the lateral changes in the amount of induced charge. [Copyright &y& Elsevier]

Semiconductor–insulator interfaces play an important role in the reliability of integrated devices; however, the impact of these interfaces on the physical mechanisms related to single-event effects has not been previously reported. We present experimental data that demonstrate that single-event charge collection can be impacted by changes in interface quality. The experimental data, combined with simulations, show that single-event response may depend on surface recombination at interface defects. The effect depends on strike location and increases with increasing linear energy transfer (LET). Surface recombination can affect single-event charge collection for interfaces with a surface recombination velocity (SRV) of 1000 cm/s and is a dominant charge collection mechanism with SRV $> 10^{5}$ cm/s. [ABSTRACT FROM AUTHOR]

Accurate predictions of device performance in 14-MeV neutron environments rely upon understanding the recoil cascades that may be produced. Recoils from 14-MeV neutrons impinging on both gallium nitride (GaN) and gallium arsenide (GaAs) devices were modeled and compared to the recoil spectra of devices exposed to 14-MeV neutrons. Recoil spectra were generated using nuclear reaction modeling programs and converted into an ionizing energy loss (IEL) spectrum. We measured the recoil IEL spectra by capturing the photocurrent pulses produced by single neutron interactions with the device. Good agreement, with a factor of two, was found between the model and the experiment under strongly depleted conditions. However, this range of agreement between the model and the experiment decreased significantly when the bias was removed, indicating partial energy deposition due to cascades that escape the active volume of the device not captured by the model. Consistent event rates across multiple detectors confirm the reliability of our neutron recoil detection method. [ABSTRACT FROM AUTHOR]

Abstract: The next generation of Martian rovers to be launched by Jet Propulsion Laboratory (JPL) are to examine polar regions where temperatures are extremely low and the absence of an earth-like atmosphere results in high levels of cosmic radiation at ground level. Cosmic rays lead to a plethora of radiation effects including Single Event Transients which can severely degrade microelectronic functionality. As such, a radiation-hardened, temperature compensated CMOS Single-on-insulator (SOI) Operational Amplifier has been designed for JPL by the University of Tennessee and fabricated by Honeywell using the SOI V process. SOI technology has been shown to be far less sensitive to transient effects than both bulk and epilayer Si. Broad beam heavy-ion tests at the University of Texas A&M using Kr and Xe beams of energy 25MeV/amu were performed to ascertain the duration and severity of the SET for the op-amp configured for a low and high gain application. However, some ambiguity regarding the location of transient formation required the use of a focused MeV ion microbeam. A 36MeV O6+ microbeam at the Sandia National Laboratory (SNL) was used to image and verify regions of particular concern. [Copyright &y& Elsevier]

The rapidly increasing use of electronics in high-radiation environments and the continued evolution in transistor architectures and materials demand improved methods to characterize the potential damaging effects of radiation on device performance. Here, electron-beam-induced current is used to map hot-carrier transport in model metal-oxide semiconductor field-effect transistors irradiated with a 300 KeV focused He+ beam as a localized line spanning across the gate and bulk Si. By correlating the damage to the electronic properties and combining these results with simulations, the contribution of spatially localized radiation damage on the device characteristics is obtained. This identified damage, caused by the He+ beam, is attributed to localized interfacial Pb centers and delocalized positive fixed-charges, as surmised from simulations. Comprehension of the long-term interaction and mobility of radiation-induced damage are key for future design of rad-hard devices. [ABSTRACT FROM AUTHOR]

Bulk 14-nm FinFET technology was irradiated in a heavy-ion environment (42-MeV Si ions) to study the possibility of displacement damage (DD) in scaled technology devices, resulting in drive current degradation with increased cumulative fluence. These devices were also exposed to an electron beam, proton beam, and cobalt-60 source (gamma radiation) to further elucidate the physics of the device response. Annealing measurements show minimal to no “rebound” in the ON-state current back to its initial high value; however, the OFF-state current “rebound” was significant for gamma radiation environments. Low-temperature experiments of the heavy-ion-irradiated devices reveal increased defect concentration as the result for mobility degradation with increased fluence. Furthermore, the subthreshold slope (SS) temperature dependence uncovers a possible mechanism of increased defect bulk traps contributing to tunneling at low temperatures. Simulation work in Silvaco technology computer-aided design (TCAD) suggests that the increased OFF-state current is a total ionizing dose (TID) effect due to oxide traps in the shallow trench isolation (STI). The significant SS elongation and ON-state current degradation could only be produced when bulk traps in the channel were added. Heavy-ion irradiation on bulk 14-nm FinFETs was found to be a combination of TID and DD effects. [ABSTRACT FROM AUTHOR]

We study the impact of irradiation on magnetic tunnel junction (MTJ) films with perpendicular magnetic anisotropy (PMA) and spin–orbit torque (SOT) switching using magneto-optical Kerr effect and transmission electron microscopy. Our results show that the thin-film stack is robust to gamma ionizing dose up to 1 Mrad(Si) and Ta1+ ion irradiation fluences up to 1012 ions/cm2, showing SOT PMA MTJs are radiation-hard. But, at very high Ta1+ ion irradiation between 1012 and 1014 ions/cm2, reduced coercivity and eventually greatly reduced PMA are observed, corresponding with an increase in intermixing of the CoFeB–MgO layers, particularly at the lower CoFeB–MgO interface. These results agree with displacement damage modeling that predicts higher damage in the layers closer to the bottom heavy metal and substrate. Compared to spin transfer torque and in-plane anisotropy MTJs, needing a top-pinned stack, a thicker heavy metal layer, and perpendicular anisotropy that is pinned out of plane by interfaces, all could make SOT PMA MTJs more susceptible to damage at high doses. [ABSTRACT FROM AUTHOR]

We evaluate the resilience of CoFeB/MgO/CoFeB magnetic tunnel junctions (MTJs) with perpendicular magnetic anisotropy (PMA) to displacement damage induced by heavy-ion irradiation. MTJs were exposed to 3-MeV Ta2+ ions at different levels of ion beam fluence spanning five orders of magnitude. The devices remained insensitive to beam fluences up to $10^{11}$ ions/cm2, beyond which a gradual degradation in the device magnetoresistance, coercive magnetic field, and spin-transfer-torque (STT) switching voltage were observed, ending with a complete loss of magnetoresistance at very high levels of displacement damage (>0.035 displacements per atom). The loss of magnetoresistance is attributed to structural damage at the MgO interfaces, which allows electrons to scatter among the propagating modes within the tunnel barrier and reduces the net spin polarization. Ion-induced damage to the interface also reduces the PMA. This study clarifies the displacement damage thresholds that lead to significant irreversible changes in the characteristics of STT magnetic random access memory (STT-MRAM) and elucidates the physical mechanisms underlying the deterioration in device properties. [ABSTRACT FROM AUTHOR]

Heavy-ion measurements are used to define a multiply nested sensitive-volume model for a 180-nm static random access memory (SRAM) test structure using the Monte Carlo radiative energy deposition (MRED) tool. We demonstrate that the fundamental assumptions of simple rectangular-parallelepiped (RPP) or integral-RPP models are inappropriate for single-event latchup (SEL) in this test structure, indicating that more advanced modeling is needed. We develop an MRED model that agrees well with latchup data at normal incidence and at roll and tilt angles of 60°. This process should facilitate estimates of SEL cross section and event rates for this and similar technologies in space environments. [ABSTRACT FROM AUTHOR]

Single crystal diamond is a suitable material for the next generation particle detectors because of the superior electrical properties and the high radiation tolerance. In order to investigate charge transport properties of diamond particle detectors, transient currents generated in diamonds by single swift heavy ions (26 MeV O 5 + and 45 MeV Si 7 + ) are investigated. Two dimensional maps of transient currents by single ion hits are also measured. In the case of 50 μm-thick diamond, both the signal height and the collected charge are reduced by the subsequent ion hits and the charge collection time is extended. These results are thought to be attributable to the polarization effect in diamond and it appears only when the transient current is dominated by hole current. In the case of 6 μm-thick diamond membrane, an “island” structure is found in the 2D map of transient currents. Signals in the islands shows different applied bias dependence from signals in other regions, indicating different crystal and/or metal contact quality. Simulation study of transient currents based on the Shockley-Ramo theorem clarifies that accumulation of space charges changes distribution of electric field in diamond and causes the polarization effect. [ABSTRACT FROM AUTHOR]

Displacement damage reduces ion beam induced charge (IBIC) through Shockley–Read–Hall recombination. Closely spaced pulses of \200 keV\ \Si^ + + ions focused in a 40 nm beam spot are used to create damage cascades within \0.25 \mu\m^2 areas. Damaged areas are detected through contrast in IBIC signals generated with focused ion beams of \200 \keV\ \Si^ + + ions and \60 keV\ \Li^+ ions. IBIC signal reduction can be resolved over sub-micron regions of a silicon detector damaged by as few as 1000 heavy ions. [ABSTRACT FROM PUBLISHER]

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. [ABSTRACT FROM PUBLISHER]

Charge collection mechanisms in AlGaN/GaN MOS-HEMTs are investigated. Device types include those with no gate oxide, and those with HfO_2 and Al_2O_3 gate oxides. Simultaneous charge collection is observed at the gate and the drain or the source, depending on strike location. Heavy ion data coupled with device simulations show that the introduction of a thin HfO_2 layer in the gate stack introduces only a small valence band barrier, reducing but not preventing collection of holes at the gate in HfO_2-gate devices. Furthermore, using Al_2O_3 gate oxide increases the valence band barrier over that of the HfO_2, to the point where the radiation-induced transient is not detectable. [ABSTRACT FROM PUBLISHER]

The effects of radiation on memristors created using tantalum oxide and titanium oxide are compared. Both technologies show changes in resistance when exposed to 800 keV Ta ion irradiation at fluences above 10^10~\cm^\-2. TaOx memristors show a gradual reduction in resistance at high fluences whereas TiO_2 memristors show gradual increases in resistance with inconsistent decreases. After irradiation TaOx devices remain fully functional and can even recover resistance with repeated switching. TiO_2 devices are more variable and exhibit significant increases and decreases in resistance when switching after irradiation. Irradiation with 28 MeV Si ions causes both technologies to switch from the off-state to the on-state when ionizing doses on the order of 60 Mrad(Si) or greater (as calculated by SRIM) are reached without applying current or voltage to the part. Irradiation with 10 keV X-rays up to doses of 18 Mrad(Si) in a single step show little effect on either technology. TaOx and TiO_2 memristors both show high tolerance for displacement damage and ionization damage and are promising candidates for future radiation-hardened non-volatile memory applications. [ABSTRACT FROM PUBLISHER]

Radiation-induced effects on the electrical characteristics of TaOx memristive (or redox) memory are experimentally assessed. 10 keV x-ray irradiation is observed to cause switching of the memristors from high to low resistance states, as well as functional failure due to cumulative dose. Gamma rays and 4.5 MeV energy protons are not observed to cause significant change in resistance state or device function at levels up to 2.5 Mrad(Si) and 5 Mrad(Si) protons, respectively. 105 MeV and 480 MeV protons cause switching of the memristors from high to low resistance states in some cases, but do not exhibit a consistent degradation. 800 keV silicon ions are observed to cause resistance degradation, with an inverse dependence of resistance on oxygen vacancy density. Variation between different devices appears to be a key factor in determining the electrical response resulting from irradiation. The proposed degradation mechanism likely involves the creation of oxygen vacancies, but a better fundamental understanding of switching is needed before a definitive understanding of radiation degradation can be achieved. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Single-event upsets are studied in digital logic cells in a radiation-hardened CMOS SOI technology. The sensitivity of SEU to different strike locations and hardening approaches is explored using broadbeam and focused beam experiments. Error distributions in chains of logic flip-flops are studied to determine the impact of various cell designs and hardening techniques on upset uniformity. [ABSTRACT FROM PUBLISHER]

Abstract: Five metal-organic frameworks (MOFs) were synthesized and investigated via steady-state photoluminescence and radioluminescence measurements. Unique spectral features were observed in the 2.5MeV proton spectra, corresponding to differences in the electronic and crystalline structures of each material. Targeted structural transformations and infiltration with extrinsic dopants were also employed to modify the luminescence of these frameworks, establishing MOFs as a platform to design new radiation detection materials. [Copyright &y& Elsevier]

The amounts of charge collection by single-photon absorption (SPA) and by two-photon absorption (TPA) laser testing techniques have been directly compared using specially made SOI diodes. For SPA measurements and some TPA measurements, the back substrates of the diodes were removed by etching with XeF_2. With the back substrates removed, the amount of TPA induced charge collection can be correlated to the amount of SPA induced charge collection. There are significant differences, however, in the amount of TPA induced charge collection for diodes with and without substrates. For the SOI diodes of this study, this difference appears to arise from several contributions, including nonlinear-optical losses and distortions that occur as the pulse propagates through the substrate, as well as displacement currents that occur only when the back substrate is present. These results illustrate the complexity of interpreting TPA and SPA single-event upset measurements. [ABSTRACT FROM AUTHOR]

Pulse widths of single-event transients produced by alpha particles in a 65-nm bulk CMOS technology are reported. The experimental setup and calibration of the alpha particle experiment is described in detail. A focused-ion beam is also utilized to explore how pulse broadening in the test circuit impacts the alpha particle SET measurements. The results of this work show that alpha particles are able to induce transient signals with a width of about 25 ps in this technology. [ABSTRACT FROM AUTHOR]

We report heavy-ion microbeam and total dose data for a new complementary (npn + pnp) SiGe on thick-film SOI technology. Measured transient waveforms from heavy-ion strikes indicate a significantly shortened single-event-induced transient current, while maintaining the total dose robustness associated with SiGe devices. Heavy-ion broad-beam data confirm a reduced single event upset (SEU) cross-section in a high-speed shift register circuit. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Digital single-event transient (SET) measurements in a bulk 65-nm process are compared to transients measured in 130-nm and 90-nm processes. The measured SET widths are shorter in a 65-nm test circuit than SETs measured in similar 90-nm and 130-nm circuits, but, when the factors affecting the SET width measurements (in particular pulse broadening and the parasitic bipolar effect) are considered, the actual SET width trends are found to be more complex. The differences in the SET widths between test circuits can be attributed in part to differences in n-well contact area. These results help explain some of the inconsistencies in SET measurements presented by various researchers over the past few years. [ABSTRACT FROM AUTHOR]

We investigate the single-event transient (SET) response of T-body and notched-body contacted MOSFETs from a commercial 45 nm SOI RF-CMOS technology. Although body-contacted devices suffer from reduced RF performance compared to floating body devices, previous work on 65 nm and 90 nm MOSFETs has shown that the presence of a body-contact significantly mitigates the total ionizing dose (TID) sensitivity that is exhibited in floating-body SOI MOSFETs. The influence of body-contacting schemes on the single-event effect (SEE) sensitivity is examined here through time-resolved measurements of laser and microbeam-induced transients from T-body and notched-body MOSFETs. Laser-induced transients demonstrate the reduced SEE sensitivity of the notched-body MOSFETs as compared to the T-body MOSFETs; this is evidenced by a uniform reduction in the peak transient magnitudes and collected charge for transients captured at the worst-case bias of \ VDS = 1.0~\ V, as well as with all terminals grounded. Microbeam-induced transient data are also presented to support the validity of the laser-induced transient data. Together, these data provide new insight into the RF versus TID versus SEE tradeoffs associated with body contacting schemes in nm-scale MOSFETs, an important concern for emerging space-based electronics applications. [ABSTRACT FROM AUTHOR]

The transient response of Silicon Carbide (SiC) Metal-Oxide-Semiconductor Field Effect Transistors (MOSFETs) with three different gates due to a single ion strike is studied. Comparing the experiment and numerical simulation, it is suggested that the charge enhancement is due to the bipolar effect. We find the bipolar gain depends on the quality of gate oxide. The impact of fixed charge in SiO2 and interface traps at SiC/SiO2 on the charge collection is discussed. [ABSTRACT FROM AUTHOR]

We investigate a novel implementation of junction isolation to harden a 200 GHz SiGe:C HBT technology without deep trench isolation against single event effects. The inclusion of isolation is shown to have no effect on the de or ac performance of the nominal device, and likewise does not reduce the HBTs inherent tolerance to TID radiation exposure on the order of a Mrad. A 69% reduction in total integrated charge collection across a slice through the center of the device was achieved. In addition, a 26% reduction in collected charge is reported for strikes to the center of the emitter. 3-D NanoTCAD simulations are performed on RHBD and control device models yielding a good match to measured results for strikes from the emitter center to 8 μm away. This result represents one of the most effective transistor layout-level RHBD approaches demonstrated to date in SiGe. [ABSTRACT FROM AUTHOR]

Abstract-We investigate the single-event transient (SET) response of bandgap voltage references (BGRs) implemented in SiGe BiCMOS technology through heavy ion microbeam experiments. The SiGe BGR circuit is used to provide the input reference voltage to a voltage regulator. SiGe HBTs in the BGR circuit are struck with 36-MeV oxygen ions, and the subsequent transient responses are captured at the output of the regulator. Sensitive devices responsible for generating transients with large peak magnitudes (more than 5% of the dc output voltage) are identified. To determine the effectiveness of a transistor-layout-based radiation hardened by design (RHBD) technique with respect to immunity to SETs at the circuit level, the BGR circuit implemented with HETs surrounded by an alternate reverse-biased pn junction (n-ring RHBD) is also bombarded with oxygen ions, and subsequent SETs are captured. Experimental results indicate that the number of events causing transients with peak magnitude more than 5% above the dc level have been reduced in the RHBD version; however, with the inclusion of the n-ring RHBD, new locations for the occurrence of transients (albeit with smaller peak magnitude) are created. Transients at the transistor-level are also independently captured and are presented. It is demonstrated that while the transients are short at the transistor level (ns duration), relatively long transients are obtained at the circuit level (hundreds of nanoseconds). In addition, the impact of the SET response of the BGR on the performance of an ultra-high-speed 3-bit SiGe analog-to-digital converter (ADC) is investigated through simulation. It is shown that ion-induced transients in the reference voltage could eventually lead to data corruption at the output of the ADC. [ABSTRACT FROM AUTHOR]

We investigate, for the first time, the potential for SEE mitigation of a newly-developed device architecture in a 3rd generation high-speed SiGe platform. This new device architecture is termed the "inverse-mode cascode SiGe HBT" and is comprised of two standard devices sharing a buried subcollector and operated in a cascode configuration. Verification of the TID immunity is demonstrated using 10 keV X-rays, while an investigation of the SEE susceptibility is performed using a 36 MeV16O ion. IBICC results show strong sensitivities to device bias with only marginal improvement when compared to a standard device; however, by providing a conductive path from the buried subcollector (C-Tap) to a voltage potential, almost all collected charge is induced on the C-Tap terminal instead of the collector terminal. These results are confirmed using full 3-D TCAD simulations which also provides insight into the physics of this new RHBD device architecture. The implications of biasing the C-Tap terminal in a circuit context are also addressed. [ABSTRACT FROM AUTHOR]

Silicon-germanium heterojunction bipolar transistor (SiGe HBT) heavy ion-induced current transients are measured using Sandia National Laboratories' microbeam and highand low-energy broadbeam sources at the Grand Accélérateur National d'Ions Lourds, Caen, France, and the University of Jyväskyla, 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. [ABSTRACT FROM AUTHOR]

We study proton and heavy ion irradiation effects on phase change memories (PCM) with MOSFET and BJT selectors and the effect of the irradiation on the retention characteristics of these devices. Proton irradiation produces noticeable variations in the cell distributions in PCM with MOSFET selectors mostly due to leakage currents affecting the transistors. PCM with BJT selectors show only small variations after proton irradiation. PCM cells do not appear to be impacted by heavy-ion irradiation. Using high temperature accelerated retention tests, we demonstrate that the retention capability of these memories is not compromised by the irradiation. [ABSTRACT FROM PUBLISHER]

We present the first charge loss model of heavy ion induced radiation damage on nanocrystal memory cells. The model takes into account the nanocrystal distribution non uniformity and the effect of different programming techniques, which may produce non uniform charging of the nanocrystals. The model has been validated with a focused microbeam test. It provides an estimation of both the ion track size and the average number of ion hits required for achieving a given charge loss. In our irradiation experiments we estimated an ion track size (diameter) of 85 nm for 50-MeV Cu ions. This model confirms also the good robustness of nanocrystal memories against heavy ion irradiation and their much stronger tolerance than the conventional floating gate based memories. [ABSTRACT FROM PUBLISHER]

Microbeam measurements and TCAD simulations are used to examine the effects of ion angle of incidence on the charge collected from events occurring in a Silicon Germanium (SiGe) Heterojunction Bipolar Transistor (HBT). The results identify the geometrically driven charge-collection mechanisms that dominate the low LET broad beam SEU response. The deep trench isolation that surrounds the transistor significantly modulates the charge transport and, therefore, the charge collected by the collector. A new way of estimating critical charge, , for upset in SiGe HBT circuits is proposed based on TCAD simulation results and measured broadbeam data. [ABSTRACT FROM PUBLISHER]

We investigate transistor-level layout-based techniques for SEE mitigation in advanced SiGe HBTs. The approach is based on the inclusion of an alternate reverse-biased pn junction (n-ring) designed to shunt electron charge away from the sub-collector to substrate junction. The inclusion of the n-ring affects neither the dc nor ac performance of the SiGe HBT and does not compromise its inherent multi-Mrad TID tolerance. The effects of ion strike location and angle of incidence, as well as n-ring placement, area, and bias on charge collection are investigated experimentally using a 36 MeV O2 microbeam. The results indicate that charge shunting through the n-ring can result in up to a 90% reduction in collector collected charge for strikes outside the DT and a 18% reduction for strikes to the emitter center. 3-D transient strike simulations using NanoTCAD are used to verify the experimental observations, as well as shed insight into the underlying physical mechanisms. Circuit implications for this RHBD technique are discussed and recommendations made. [ABSTRACT FROM AUTHOR]

Delayed charge collection from ionizing events outside the deep trench can increase the SEU cross section in deep trench isolation technologies. Microbeam test data and device simulations demonstrate how this adverse effect can be mitigated through substrate engineering techniques. The addition of a heavily doped p-type charge-blocking buried layer in the substrate can reduce the delayed charge collection from events that occur outside the deep trench isolation by almost an order of magnitude, implying an approximately comparable reduction in the SEU cross section. [ABSTRACT FROM AUTHOR]

The probability of proton-induced multiple-bit upset (MBU) has increased in highly-scaled technologies because device dimensions are small relative to particle event track size. Both proton-induced single event upset (SEU) and MBU responses have been shown to vary with angle and energy for certain technologies. This work analyzes SEU and MBU in a 130 nm CMOS SRAM in which the single-event response shows a strong dependence on the angle of proton incidence. Current proton testing methods do not account for device orientation relative to the proton beam and, subsequently, error rate prediction assumes no angular dependencies. Proton-induced MBU is expected to increase as integrated circuits continue to scale into the deep sub-micron regime. Consequently, the application of current testing methods will lead to an incorrect prediction of error rates. [ABSTRACT FROM AUTHOR]

In this work, we have focused our attention on MOSFETs, which are the real basic elements of all CMOS applications. We have studied the immediate and latent effects produced by heavy ion irradiation on MOSFETs with ultrathin gate oxide, even after electrical stresses subsequent to irradiation. We found that a single ion can generate a physically damaged region (PDR) localized in the Si-SiO2 interface, which may hamper the surface channel formation. In order to generate a PDR the ion hit must be close enough to MOSFET borders, i.e., in correspondence with the STI or the LDD spacer. Consequently, if both MOSFET W and L are large enough only few ion hits may give place to a PDR, mitigating the radiation damage. Finally we have developed an original model to describe the impact of the PDR on channel conductance in the ohmic linear region. On the basis of this model, we predicte a PDR size around 0.2-1 μm. [ABSTRACT FROM AUTHOR]

This paper presents the first 3D simulation of heavy-ion induced charge collection in a SiGe RBT,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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]