Mechanisms of Electron-Induced Single-Event Upsets in Medical and Experimental Linacs

In this paper, we perform an in-depth analysis of the single-event effects observed during testing at medical electron linacs and an experimental high-energy electron linac. For electron irradiations, the medical linacs are most commonly used due to their availability and flexibility. Whereas previous efforts were made to characterize the cross sections at higher energies, where the nuclear interaction cross section is higher, the focus of this paper is on the complete overview of relevant electron energies. Irradiations at an electron linac were made with two different devices, with a large difference in feature size. The irradiations at an experimental linac were performed with varying en…

Mechanisms of Electron-Induced Single-Event Latchup

In this paper, possible mechanisms by which electrons can induce single-event latchups in electronics are discussed. The energy deposition and the nuclear fragments created by electrons in silicon are analyzed in this context. The cross section enhancement effect in the presence of high-Z materials is discussed. First experimental results of electron-induced latchups are shown in static random access memory devices with low linear energy transfer thresholds. The radiation hardness assurance implications and future work are discussed.

Mechanisms of Electron-Induced Single Event Upsets in Medical and Experimental Linacs

In this paper, we perform an in-depth analysis of the single-event effects observed during testing at medical electron linacs and an experimental high-energy electron linac. For electron irradiations, the medical linacs are most commonly used due to their availability and flexibility. Whereas previous efforts were made to characterize the cross sections at higher energies, where the nuclear interaction cross section is higher, the focus of this paper is on the complete overview of relevant electron energies. Irradiations at an electron linac were made with two different devices, with a large difference in feature size. The irradiations at an experimental linac were performed with varying en…

Heavy-Ion-Induced Degradation in SiC Schottky Diodes : Incident Angle and Energy Deposition Dependence

International audience; 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.

Semi-Empirical Model for SEGR Prediction

The underlying physical mechanisms in single event gate rupture (SEGR) are not known precisely. SEGR is expected to occur when the energy deposition due to a heavy ion strike exceeds a certain threshold simultaneously with sufficient electric field across the gate dielectric. Typically the energy deposition is described by using the linear energy transfer (LET) of the given ion. Previously the LET has been demonstrated not to describe the SEGR sufficiently. The work presented here introduces a semi-empirical model for the SEGR prediction based on statistical variations in the energy deposition which are described theoretically.

Direct Ionization Impact on Accelerator Mixed-Field Soft-Error Rate

We investigate, through measurements and simulations, the possible direct ionization impact on the accelerator soft-error rate (SER), not considered in standard qualification approaches. Results show that, for a broad variety of state-of-the-art commercial components considered in the 65-16-nm technological range, indirect ionization is still expected to dominate the overall SER in the accelerator mixed-field. However, the derived critical charges of the most sensitive parts, corresponding to ~0.7 fC, are expected to be at the limit of rapid direct ionization dominance and soft-error increase.

Statistical Analysis of Heavy-Ion Induced Gate Rupture in Power MOSFETs—Methodology for Radiation Hardness Assurance

A methodology for power MOSFET radiation hardness assurance is proposed. It is based on the statistical analysis of destructive events, such as gate oxide rupture. Examples of failure rate calculations are performed.

High-Energy Electron-Induced SEUs and Jovian Environment Impact

We present experimental evidence of electron-induced upsets in a reference European Space Agency (ESA) single event upset (SEU) monitor, induced by a 200-MeV electron beam at the Very energetic Electronic facility for Space Planetary Exploration in harsh Radiation environments facility at CERN. Comparison of experimental cross sections and simulated cross sections is shown and the differences are analyzed. Possible secondary contributions to the upset rate by neutrons, flash effects, and cumulative dose effects are discussed, showing that electronuclear reactions are the expected SEU mechanism. The ESA Jupiter Icy Moons Explorer mission, to be launched in 2022, presents a challenging radiat…

SEGR in SiO<inf>2</inf>-Si<inf>3</inf>N<inf>4</inf> stacks

Effects of high-energy electrons in advanced NAND flash memories

We study the effects of high-energy electrons on advanced NAND Flash memories with multi-level and single-level cell architecture. We analyze the error rate in floating gate cells as a function of electron energy, evaluate the impact of total ionizing dose, and discuss the physical origin of the observed behavior.

Single Event Upsets Induced by Direct Ionization from Low-Energy Protons in Floating Gate Cells

Floating gate cells in advanced NAND Flash memories, with single-level and multi-level cell architecture, were exposed to low-energy proton beams. The first experimental evidence of single event upsets by proton direct ionization in floating gate cells is reported. The dependence of the error rate versus proton energy is analyzed in a wide energy range. Proton direct ionization events are studied and energy loss in the overlayers is discussed. The threshold LET for floating gate errors in multi-level and single-level cell devices is modeled and technology scaling trends are analyzed, also discussing the impact of the particle track size. peerReviewed

Incident angle effect on heavy ion induced reverse leakage current in SiC Schottky diodes

Heavy-ion induced degradation in the reverse leakage current of SiC Schottky power diodes shows distinct dependence on the angle of incidence. TCAD simulations have been used to study the physical mechanisms involved.

MBU characterization of NAND-Flash memories under heavy-ion irradiation

The angular dependence of the MBU-Cross-Section of two 8-Gbit-SLC-NAND-Flash and the orientation of the MBU-pattern has been measured.

Heavy Ion Induced Degradation in SiC Schottky Diodes : Bias and Energy Deposition Dependence

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. peerReviewed

Microbeam SEE Analysis of MIM Capacitors for GaN Amplifiers

Broad-beam and microbeam single-event effect tests were performed on metal–insulator–metal capacitors with three different thicknesses of silicon nitride (Si3N4) dielectric insulator: 250, 500, and 750 nm. The broad-beam tests indicated that the devices with the thicker, 500- and 750-nm dielectric did not have a greater breakdown voltage. The surrounding structures of the capacitor were suspected to be a possible cause. Microbeam techniques made it possible to localize the failure location for the 500- and 750-nm devices. The failure occurs in the air bridge structure connected to the top capacitor plate, which can therefore be considered as an edge effect, while for the 250-nm devices, the…

SEGR in SiO${}_2$–Si$_3$N$_4$ Stacks

Abstract. This work presents experimental Single Event Gate Rupture (SEGR) data for Metal–Insulator–Semiconductor (MIS) devices, where the gate dielectrics are made of stacked SiO2–Si3N4 structures. A semi-empirical model for predicting the critical gate voltage in these structures under heavy-ion exposure is first proposed. Then interrelationship between SEGR cross- section and heavy-ion induced energy deposition probability in thin dielectric layers is discussed. Qualitative connection between the energy deposition in the dielectric and the SEGR is proposed. peerReviewed

Heavy Ion Sensitivity of 16/32-Gbit NAND-Flash and 4-Gbit DDR3 SDRAM

16/32-Gbit NAND-Flash and 4-Gbit DDR3 SDRAM memories have been tested under heavy ion irradiation. At high LET, 25nm NAND-Flash show MBUs at normal incidence. Techniques for SEFI mitigation in DDR3 SDRAM are studied.

Heavy ion SEE test of 2 Gbit DDR3 SDRAM

New generation 2 Gbit DDR3 SDRAMs from Micron, Samsung and Nanya have been tested under heavy ions. SEFIs significantly outweigh random SEU errors even at low LET; however, SEFIs can be mitigated by frequent re-initialization.

Charge Transport Mechanisms in Heavy-Ion Driven Leakage Current in Silicon Carbide Schottky Power Diodes

Under heavy-ion exposure at sufficiently high reverse bias voltages silicon carbide (SiC) Schottky diodes are observed to exhibit gradual increases in leakage current with increasing ion fluence. Heavy-ion exposure alters the overall reverse current-voltage characteristics of these diodes, leaving the forward characteristics practically unchanged. This paper discusses the charge transport mechanisms in the heavy-ion damaged SiC Schottky diodes. A macro model, describing the reverse current-voltage characteristics in the degraded SiC Schottky diodes is proposed. peerReviewed

SEU and MBU Angular Dependence of Samsung and Micron 8-Gbit SLC NAND-Flash Memories under Heavy-Ion Irradiation

The angular dependence of the SEU and MBU cross sections of two 8-Gbit NAND-Flash memories, Samsung and Micron, is measured under Ar, Fe, and Kr irradiation. The omnidirectional sensitivity is calculated based on experimental results.

Mechanisms of Electron-Induced Single Event Latchup

In this paper, possible mechanisms by which electrons can induce single-event latchups in electronics are discussed. The energy deposition and the nuclear fragments created by electrons in silicon are analyzed in this context. The cross section enhancement effect in the presence of high-Z materials is discussed. First experimental results of electron-induced latchups are shown in static random access memory devices with low linear energy transfer thresholds. The radiation hardness assurance implications and future work are discussed. peerReviewed

Mono-energetic electron induced single-event effects at the VESPER facility

We present experimental evidence of electron induced upsets in a reference ESA SEU monitor, the SEU based particle detector, induced by 200 MeV electron beam at the VESPER facility at CERN. Comparison of experimental cross sections and simulated cross sections are shown and the differences are analyzed. Possible secondary contributions to the upset rate by neutrons and cumulative dose effects are discussed, showing that electronuclear reactions are the expected SEU mechanism. Insight is given as to possible overall electron contribution to the upset rates in the Jovian radiation environment inside a typical spacecraft shielding are evaluated.

Comparison of Single Event Transients Generated at Four Pulsed-Laser Test Facilities-NRL, IMS, EADS, JPL

Four pulsed-laser single-event effects systems, differing in wavelength and pulse width, were used to generate single event transients in a large-area silicon photodiode and an operational amplifier (LM124) to determine how transient amplitude and charge collection varied among the different systems. The optical wavelength and the focused spot size are the primary factors influencing the resultant charge density profile. In the large-area photodiode the transients can be distorted by high charge-injection densities that occur for tightly focused, higher energy optical pulses. When the incident laser-pulse energies are corrected for reflection losses and photon efficiency, with collection de…

Influence of beam conditions and energy for SEE testing

GANIL/Applications industrielles; The effects of heavy-ion test conditions and beam energy on device response are investigated. These effects are illustrated with two types of test vehicles: SRAMs and power MOSFETs. In addition, GEANT4 simulations have also been performed to better understand the results. Testing to high fluence levels is required to detect rare events. This increases the probability of nuclear interactions. This is typically the case for power MOSFETs, which are tested at high fluences for single event burnout or gate rupture detection, and for single-event-upset (SEU) measurement in SRAMs below the direct ionization threshold. Differences between various test conditions (…

Single-Event Effects in the Peripheral Circuitry of a Commercial Ferroelectric Random Access Memory

International audience; This paper identifies the failure modes of a commercial 130-nm ferroelectric random access memory. The devices were irradiated with heavy-ion and pulsed focused X-ray beams. Various failure modes are observed, which generate characteristic error patterns, affecting isolated bits, words, groups of pages, and sometimes entire regions of the memory array. The underlying mechanisms are discussed.

Low Energy Protons at RADEF - Application to Advanced eSRAMs

A low energy proton facility has been developed at RADEF, Jyvskyl, Finland. The proton energy selection, calibration and dosimetry are described. The first experiment with external users was performed using two memory test vehicles fabricated with 28 nm technology. Examples of single event upset measurements in the test vehicles embedded SRAMs (eSRAMs) as a function of proton energy are provided.