Search

An on-chip measurement circuit that was specifically designed to capture the high-speed transient characteristics of photocurrent is employed to measure total-ionizing-dose (TID)-induced leakage from 10 keV X-rays. This circuit uses a photocurrent-controlled oscillator (PCO) to produce an analog frequency, which provides linearity comparable to traditional, off-chip methods of TID measurement. The circuit was fabricated in a sub-50 nm, fully depleted silicon-on-insulator (FD-SOI) technology. TID-induced leakage currents were measured using the circuit and results were compared to off-chip direct measurements from identical transistor arrays. Additionally, potential in situ applications of this circuit in conjunction with a TID-compensating back-gate biasing technique are explored. [ABSTRACT FROM AUTHOR]

Static random access memories (SRAMs) are prone to a single-event upset (SEU), also known as soft errors, due to transient noise caused by a single strike of radiation. Beam testing has been extensively used to measure the SEU cross section of SRAMs as a function of the linear energy transfer (LET) of charged particle radiation. The evolution of the cross section as a function of LET is called the cross section curve, which plays a vital role in upset rate analysis for hardness assurance. Various analytical models have been developed to describe SRAM SEU cross section curves, and they have proven to be useful in reducing the cost of beam testing as well as revealing the physics behind test results. However, they involve arbitrary parameters, which make it challenging to predict cross section curves without any beam results. Moreover, the current method of analyzing cross section curves or the LET dependence of cross sections relies on a model different from that is used in the analysis of power-supply-voltage dependence, which is becoming increasingly important because of the demand for low-power operation. To overcome these problems, this article proposes a unified equation that describes both LET and the power-supply-voltage dependence of SRAM SEU cross sections. It comprises only parameters that are physically clear and familiar to SEU researchers. As well as giving possible constraints, comparisons with data from the literature suggest it can be applied to SRAMs fabricated in bulk and silicon-on-insulator (SOI) processes across generations from the early 1000-nm-scale to the current 10-nm-scale technology nodes. [ABSTRACT FROM AUTHOR]

The effects of buried-well potential perturbation under the buried-oxide (BOX) layer are studied in both a heavy-ion single event upset (SEU) test and a high-energy proton-SEU test of a silicon-on-insulator (SOI) dual interlocked storage cell (DICE)-based flip-flop. Their dependence on incident angle and back bias is discussed. We fabricated both DICE-based flip-flop and conventional flip-flop, which are designed as 80 000-stage shift-register chains. In a heavy-ion test, a considerable number of SEUs were observed at back bias exceeding 2.4 V, and a ten-times larger SEU-cross section was finally recorded at back bias of 3.0 V compared with the total active area of a DICE-based flip-flop cell. This marks the first case where DICE topology was found to be broken by buried-well potential perturbation on an SOI DICE-based flip-flop. In a proton test, one error was observed at back bias of 2.0 V. The SEU rate in the Van Allen belt at an altitude of 2300 km and an inclination of 90° was estimated as being once every 5 years. [ABSTRACT FROM AUTHOR]

This article investigates heavy-ion irradiation effects on perpendicular magnetic anisotropy spin-transfer torque magnetic tunnel junction devices (PMA STT-MTJs). The radiative campaign took place at the Université Catholique de Leuven (UCL) facility. The considered devices consist of STT p-MTJs purely magnetic memories and they were fabricated at SPINTEC using the most advanced CoFeB-MgO MTJ technology. Single-event upset (SEU) tolerance and modification of magnetic properties has been investigated. [ABSTRACT FROM AUTHOR]

The history of integrated circuit (IC) development is another record of human challenges involving space. Efforts have been made to protect ICs from sudden malfunctions due to single-event effects (SEEs). These effects are triggered by only a single strike of particle radiation, such as an α-ray or cosmic ray, originating from our solar activity and galactic events including supernovas. This article explores how SEEs have evolved along with the progress in complementary metal-oxide-semiconductor (CMOS) digital IC technology, or device scaling, from the early micrometer-scale generations to the current nanometer-scale generations. For this purpose, focusing on basic digital elements, that is, inverters and static random access memories (SRAMs), this study collected more than 100 sets of data on four characteristic parameters of single-event upsets (SEUs) and single-event transients (SETs), both of which are undesired flips in digital logic states. The results show that all the examined parameters, such as the SEU critical charge, decrease with the device feature size. Analysis involving structure classification, such as bulk versus silicon-on-insulator (SOI) substrates and planar versus fin channels, reveals relationships between the examined SEE parameters and other device features such as the power supply voltage. All the data collected in this survey are explicitly given in tables for future exploration of IC reliability. [ABSTRACT FROM AUTHOR]

The radiation response of TaOx-based resistive memory (RRAM) devices fabricated in academic (Set A) and industrial (Set B) settings was compared. Ionization damage from a 60Co gamma source did not cause any changes in device resistance for either device type, up to 45 Mrad(Si). Displacement damage from a heavy ion beam caused a decrease in resistance at 1 × 1021 oxygen displacements per cm3 in Set B devices in the high-resistance state (HRS); meanwhile, Set A devices did not exhibit any decrease in resistance due to displacement damage. Both types of devices exhibited an increase in resistance around 3 ×1022 oxygen displacements per cm3, possibly due to the damage at the oxide/metal interfaces. These extremely high levels of damage represent near-total atomic disruption, and if this level of damage was ever reached, other circuit elements would likely fail before the RRAM devices in this article. Overall, both sets of devices were much more resistant to radiation effects than the similar devices reported in the literature. Displacement damage effects were only observed in the Set A devices once the displacement-induced oxygen vacancies surpassed the intrinsic vacancy concentration in the devices, suggesting that high oxygen vacancy concentration played a role in the devices’ high tolerance to displacement damage. [ABSTRACT FROM AUTHOR]

Static random access memory (SRAM) is one the most sensitive devices to radiation. It may often exhibit undesired reversals of memory bits, called single-event upsets or soft errors. Sensitivity to such undesired events is widely quantified with the parameter of cross sections, which varies from cell to cell due to process variations. Many efforts have been made to quantify such variations, most commonly using simulations that often become a hurdle especially for commercial-off-the-shelf SRAMs. In this regard, an analysis method is proposed to extract such variations easily from radiation test data. It relies on the data retention voltage, which is an electrical parameter associated with the static noise margin. This voltage can be measured on a desk without special circuits. The validity of the proposed method is experimentally demonstrated using SRAM fabricated in a 65-nm silicon-on-insulator technology, which was exposed to various high-energy heavy ions simulating the effects of galactic and terrestrial cosmic rays. Theoretical discussion provides further evidence, while revealing an interesting relationship between the data retention voltage and power supply voltage. This relationship suggests power-supply voltage tuning to deal with chip-to-chip variations in cross sections and also with similar variations caused by total-dose effects and aging effects such as negative bias temperature instability. [ABSTRACT FROM AUTHOR]

Novel design techniques for efficient testability are developed and have been implemented in a 14-/16-nm bulk FinFET node technology characterization vehicle. The result of this paper was the measurement of over 300 000 SETs across 12 combinational logic variants and 415 000 SEUs in three D-flip-flop designs over a large test matrix of heavy-ion linear energy transfer, angle of incidence, and supply voltage in only 319 test runs with a total test time of 108 h. A similar-sized data set with equivalent technology coverage, using the traditional serial testing approach as used in previous work, would typically require thousands of test runs and a significant number of additional hours of testing. The methodologies developed in this paper are technology agnostic and have provided the capability to efficiently characterize the radiation-induced response of the 14-/16-nm FinFET technology generation and yielded insights for assessing the feasibility for incorporation in systems requiring radiation resiliency. [ABSTRACT FROM PUBLISHER]

This paper describes a circuit called dynamic and applicative measurement of single events in logic (DAMSEL), which can individually measure the impact of single event upsets and single-event transients (SETs) in realistic, synchronous digital circuits. Heavy-ion and pulsed laser test results are presented. Both a simple digital and an analog simulation methodology are demonstrated to provide similar cross sections to those observed during the tests. Overall, the DAMSEL structure has many advantages over current circuits used for measuring SETs, including the ease with which test results can be extrapolated to real designs. [ABSTRACT FROM PUBLISHER]

Heavy-ion-induced degradation in the reverse leakage current of SiC Schottky power diodes exhibits a strong dependence on the ion angle of incidence. This effect is studied experimentally for several different bias voltages applied during heavy-ion exposure. In addition, TCAD simulations are used to give insight on the physical mechanisms involved. [ABSTRACT FROM PUBLISHER]

Experimental results on ion-induced leakage current increase in 4H-SiC Schottky power diodes are presented. Monte Carlo and TCAD simulations show that degradation is due to the synergy between applied bias and ion energy deposition. This degradation is possibly related to thermal spot annealing at the metal semiconductor interface. This thermal annealing leads to an inhomogeneity of the Schottky barrier that could be responsible for the increase leakage current as a function of fluence. [ABSTRACT FROM PUBLISHER]

We report on a measurement of low energy ion irradiation effects on as-grown films of SiO_2 on a Si substrate. Beams of normally incident Na^ + ions with kinetic energies of 2 keV to 5 keV were focused onto \sim 1900 \ \AA SiO_2 films. Aluminum top metal contacts were subsequently deposited onto these targets such that irradiated regions and unexposed (pristine) regions of the target could be compared using capacitance–voltage (C–V) measurements of individual metal-oxide-semiconductor (MOS) devices. The C–V data reveal an energy-dependent shift in the flatband voltage (VFB) that can be returned to its near-pristine value by a low temperature anneal. An increase in the density of interface states (Dit) inferred from the C–V curves is found to have a superlinear dependence on the incident kinetic energy. These data are consistent with previously observed UV radiation effects on MOS oxides, where transferred energy leads to electron-hole pair production and the diffusion and trapping of holes throughout the oxide. Our measured trapped hole densities are compared with calculated densities, which are based on the incident ion dose and the predicted ion implantation range, to arrive at a fractional yield for hole survival and measurement within an encapsulated MOS device. [ABSTRACT FROM AUTHOR]

Circuit parameters and configuration are very important when studying the synergistic effects total dose/SET. We explore a method combining dynamic parameter measurement and spectrum analysis which lead to a better understanding of this complex phenomenon. In this paper symbolic circuit analysis is used to obtain the relationship between input, output and noise injection due to photocurrent generation in the form of a rational function using symbolic variables in the complex frequency domain. This simulation technique was able to predict the impact of (i) total dose level, (ii) circuit parameters, and (iii) the injected energy on the ASET shapes. Basic mechanisms as field collapse and collection efficiency were also predicted and assessed. [ABSTRACT FROM PUBLISHER]

Charge collection mechanisms are investigated in surface channel GaAs MOSFETs under broadbeam heavy ion irradiation and pulsed two-photon-absorption laser irradiation. The large barrier between the gate dielectric and GaAs eliminates gate conduction current, but there is significant gate displacement current. Charge enhancement occurs because radiation-generated holes accumulate in the substrate, which increases the local electrostatic potential. The increased potential enhances the source-to-drain current, resulting in excess collected charge. The collected charge increases significantly with gate bias, due to the long tails of the charge waveforms that occur for higher gate bias. The collected charge increases with increasing drain bias. [ABSTRACT FROM PUBLISHER]

A non-volatile memory element called a perpendicular-anisotropy magnetic tunnel junction was fabricated using CoFeB/MgO/CoFeB film stack technology. It exhibits two stable resistance values, high or low, depending on the relative directions of the magnetizations of the two ferromagnetic CoFeB layers. After being programmed into the high resistance state with a current injection scheme based on the spin transfer torque theory, the tunnel junction was exposed to 15-MeV Si ions under different voltage stress conditions. The tested structure remained in the programmed high resistance state after being bombarded with 10–100 Si ions, even under the stressed situations. A time-domain analysis proved that this result is due to the perfect immunity of the tested magnetic tunnel junction to single event upsets. Some degradation in resistance due to the heavy-ion irradiation was detected through a precise parameter analysis based on a tunneling theory but it was negligibly small (1%). There were no statistically significant changes in the thermal stability factor before and after irradiation, and this means the long-term retention properties remained unchanged. [ABSTRACT FROM PUBLISHER]

Radiation shielding is of primary importance in the planning of new interplanetary manned missions, and the ISS represents the largest laboratory for radiation shielding in space ever built. The ISS radiation environment has been thoroughly characterised by the Monte Carlo-based high-energy physics toolkit Geant4. It has been found that the ISS structure is quite effective at shielding from most forms of radiation, largely due to its internal arrangement. The internal environment found is consistent with literature values and astronaut dosimetry, and results indicate that the internal arrangement of a spacecraft may be the key to the radiation environment within it. Simulation results are also presented for the interplanetary case, including detailed comparisons with other codes. Guidelines for interplanetary manned mission design are presented using these findings. [ABSTRACT FROM AUTHOR]

Electric conductivity variations of hydrogenated amorphous silicon due to self-ion irradiation, i.e. irradiation with Si or H ions, are comprehensively investigated. The anomalous enhancement of dark conductivity (DC) and photoconductivity (PC) are firstly observed due to proton irradiation in the cases of undoped and n-type a-Si:Hs, and after that both decrease with increasing the irradiation fluence. However, Si ion irradiation does not induce the anomalous enhancement and induce a monotonic decrease in DC and PC in the low fluence regime. It is shown from the Seebeck effect analysis that the anomalous enhancement is caused by generation of donor-centers which have metastable nature at room temperature. The decrease in DC and PC is ascribed to the carrier removal effect and the carrier lifetime decrease accompanied by accumulation of dangling bonds, respectively. However, further irradiation causes the loss of photoconduction and the drastic increase in DC. This indicates that the dominant conduction mechanism changes from the band transport to the hopping transport due to excessive accumulation of dangling bonds. The change in the dominant conduction mechanism occurs at above about 10^-4\ \ dpa (displacement per atom) and is independent of the majority carrier concentration before irradiation. It is concluded that the conductivity variations caused by self-ion irradiation can be systematically categorized according to the ratio of the nuclear energy deposition to the electronic energy deposition of incident ions. [ABSTRACT FROM PUBLISHER]

We present an experimental methodology developed to probe the clustered defect formation in GaAs devices under both neutron and ion irradiations. The strengths, limitations, and path forward to gather structural defect information will be addressed. [ABSTRACT FROM PUBLISHER]

Scintillating screens are commonly used at accelerator facilities. However, their imaging qualities are not well understood, especially for high-current ion beam operation. Several types of inorganic scintillators were investigated for various ion species and energies of 4.8 and 11.4 MeV/u. For ion beam applications, the exact reproduction of the beam profile is of great importance. Due to the impact by ions, the dose rate during beam delivery is more than 10 orders of magnitude higher as for other applications of scintillators in typical nuclear physics experiments. To validate the imaging quality of the scintillators, different profile measurement methods are compared. Ceramic Al2O3 showed the best results compared to other ceramics like ZrO2:Y or quartz glass Herasil 102. The imaging properties of the materials can depend significantly on the ion energy. For Al2O3 irradiated with a Ca beam the of 4.8 MeV/u, the results agree with the reference methods. However, for 11.4 MeV/u, the screen image does not reflect the beam distribution, which cannot be attributed to material degradation. A model is under development taking into account the radial dose distribution along the ion track as well as the overlap of tracks. For Al2O3, this model can describe the observed saturation effect and is able to reconstruct saturated images. The basics and applications of this model are discussed. Detailed spectroscopic investigations were performed to determine the influence of the ion beam intensity on the luminescence spectra emitted by the materials. No significant dependence on the spectra with respect to the beam intensity was found for most of the scintillators. [ABSTRACT FROM PUBLISHER]

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]

High-bandwidth (16 GHz) time-resolved charge-collection measurements for heavy-ion irradiation of up to 70 GeV/amu are performed on low-power 6.1 Å lattice spacing InAlSb/InAs HEMT devices. Event cross sections are measured to be significantly larger than the active areas of the devices. Novel energy-dependent effects are observed. [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]

At GSI, the Helmholtz Centre for Ion Research, the properties of scintillation screens, irradiated by an ion beam, were studied. For various materials, the different ion beams H+, C2+, Ar10+, Ni9+, Ta24+, and U28+ in the energy range from 4.8-11.4 MeV/u were applied with currents ranging from nA to some mA, delivered by the heavy ion LINAC at GSI. Scintillation screens are widely used for qualitative ion beam profile monitoring. However, precise measurements of the beam profile yield ambivalent results, especially for high beam currents. Thus, the properties (light yield, beam width, and higher statistical moments) of well-known scintillators, ceramic materials, and different quartz glasses are compared. The image of each ion beam pulse was recorded by a digital CCD camera and individually evaluated. A change of the imaged ion beam shape was observed for some materials. The recorded beam profile shows dependence on the scintillator material. Even for low beam intensities (17 nA) a difference in the beam width of about 25% was measured. Additionally, the light yield and beam width depend significantly on the screen temperature, which is increased by the ion impact. For ZrO2 : Al the influence of the screen temperature on the statistical moments was investigated. Furthermore the spectra of scintillation screens were studied in the region from 350 to 750 nm for the irradiation with H+ and Ta24+ ions. Empirical results are discussed and give rise to further investigations on the materials. [ABSTRACT FROM AUTHOR]

Heavyion-induced single events transients (SETs) in advanced digital circuits are a significant reliability issue for spacebased systems. SET pulse widths in silicon-on-insulator (SOI) technologies are often significantly shorter than those in comparable bulk technologies. In this paper, heavy-ion-induced digital singleevent transient measurements are presented for a 180-nm fully depleted SOI technology. Upset cross-sections for this technology with and without body-ties are analyzed using 3-D TCAD simulations. Pulse broadening is shown to lengthen the measured SET pulse widths significantly for the circuit without body contacts. [ABSTRACT FROM AUTHOR]

Factors that affect single-event transient pulse widths, such as drift, diffusion, and parasitic bipolar transistor parameters, are also strong functions of operating temperature. In this paper, SET pulse-width measurements are performed over a wide temperature range in both bulk and fully-depleted SOI (silicon on insulator) technologies. The average pulse-width increases with temperature for the bulk process, but not for the FDSOI process. [ABSTRACT FROM AUTHOR]

Heavy ion-induced single events transients (SETs) in advanced digital circuits are becoming a significant reliability issue for space-based systems. In this work, two experiments are performed on devices designed to look specifically at digital single event transients. Small voltage variations, like those that can be found across an integrated circuit, are shown to affect the digital single event transient response significantly. For technologies with supply voltages near 1 V, these potential variations may result in unexpected vulnerability. [ABSTRACT FROM AUTHOR]

Novel techniques have been developed to simulate particle transport in arbitrarily complex back-end-of-line topologies. They are shown to be critical for single event effect analyses of new device structures for 65 nm CMOS technologies and beyond. The salient features of the new modeling methods are illustrated by the simulation results taken from several case studies of particle-induced radiation problems in the back end. [ABSTRACT FROM AUTHOR]

Different amounts of degradation for n-Si and p-Si are observed after X-ray, H+, and He+ irradiations. Recombination lifetime and forward I-V measurements made on abrupt-junction diodes are compared to theory. Ionizing damage and displacement damage associated with surface and bulk trapping mechanisms, respectively, compete with each other and lead to different behaviors according to the doping type of the silicon on the lightly doped side of the junction. Surface effects are dominant in the n+/p diodes compared to the p+/n diodes; bulk trapping prevails in the n-Si compared to p-Si. Independently of ion type or fluence, the lifetime damage factor due to irradiation is worse in the p-Si than in the n-Si by a factor of 2-3 times. [ABSTRACT FROM AUTHOR]

In this paper, data are presented from test chips in four technology nodes. With this data, the trends in single event effects as feature sizes shrink are studied. Some of the trends discussed include upset thresholds, shrinking cross sections, multiple bit upsets, and per bit error rate trends. Also included in this paper is some of the first ever heavy ion data from a 65 nm CMOS technology. With data from the 250 nm, 180 nm, 90 nm, and 65 nm technology nodes, the past, present, and future of what the radiation effects community has dealt with and will be dealing with when it comes to single event effects is presented. [ABSTRACT FROM AUTHOR]

Digital single event transients induced in combinatorial logic are quickly becoming a significant error source as circuit feature sizes shrink and digital circuits operate faster. In this paper, we are able to compare the combinatorial logic error rate to the sequential logic error rate in both heavy ion and proton environments in a simple digital circuit created in a 0.18 μm CMOS technology. We are able to do this by comparing data from two unique test chips. [ABSTRACT FROM AUTHOR]

Gamma-ray large area space telescope (GLAST) is a next generation high-energy gamma-ray space observatory designed for observations of celestial gamma-ray sources in the energy band extending from 10 MeV to more than 100 GeV. The main instrument, the large area telescope (LAT), consists of a microstrip silicon tracker, a calorimeter, an anticoincidence detector, and the data acquisition (DAQ) system. This paper summarizes the results obtained during the radiation testing of the ASIC chips used in the LAT tracker. Both single event effects (SEE) and total ionizing dose effect (TID) tests have been performed, as part of the radiation hardness assurance (RHA) for the planned 5-yr mission. Heavy-ion SEE tests have been performed at the SIRAD irradiation facility at the INFN National Laboratories of Legnaro, Italy (LNL) and at the Texas A&M University (TAMU) Cyclotron Institute, with LET values ranging up to ∼80 MeV × cm²/mg. The tolerance of the chips to ionizing radiation has been evaluated with heavy ions and by irradiating chips with the spherical 60Co gamma source of the LNL CNR-ISOF laboratory. [ABSTRACT FROM AUTHOR]