Microdose analysis of ion strikes on SRAM cells
TL;DR: In this paper, the effect from exposure to highly localized ionizing radiation on microstructures is described, and the voltage at which a commercial SRAM cell cannot hold a programmed state changes with microdose.
Abstract: A method of measuring the effect from exposure to highly localized ionizing radiation on microstructures is described. The voltage at which a commercial SRAM cell cannot hold a programmed state changes with microdose. The microdose distribution across the array, in addition to the analysis of the occurrence of anomalous shifts in operating bias due to rare, large energy-deposition events is studied. The effect of multiple hits on a SRAM cell is presented. A general theory on multiple hits from which basic device parameters can be extracted is presented. SPICE, as well as analysis of basic device physics, is used to analyze the damage to individual transistors and the response of a SRAM cell.
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TL;DR: In this article, the authors give detailed test guidelines for single event upset (SEU), single-event latchup (SEL), single event burnout (SEB), and single event gate rupture (SEGR) hardness assurance testing.
Abstract: This document gives detailed test guidelines for single-event upset (SEU), single-event latchup (SEL), single-event burnout (SEB), and single-event gate rupture (SEGR) hardness assurance testing. It includes guidelines for both heavy-ion and proton environments. The guidelines are based on many years of testing at remote site facilities and our present understanding of the mechanisms for single-event effects.
73 citations
Cites background from "Microdose analysis of ion strikes o..."
...If errors are still detected the device may no longer be functional, or may be sensitive to microdose effects or stuck bits [2], [3]....
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01 Aug 2007-Nuclear Instruments & Methods in Physics Research Section B-beam Interactions With Materials and Atoms
TL;DR: The single event error rate in advanced semiconductor technologies can be estimated more accurately than conventional methods by using simulation based on accurate descriptions of a large number of individual particle interactions as discussed by the authors.
Abstract: The single-event error rate in advanced semiconductor technologies can be estimated more accurately than conventional methods by using simulation based on accurate descriptions of a large number of individual particle interactions. The results can be used to select the ion types and energies for accelerator testing and to identify situations in which nuclear reactions will contribute to the error rate.
27 citations
MBDA1
TL;DR: In this article, it was shown that the number of stuck bits increases exponentially with temperature, due to the general increase in the leakage currents through the damage centers with temperature and that stuck bits are seen to pseudo-randomly stick and unstick in the context of a continuously rising trend of temperature.
Abstract: This paper reports behavior analogous to the Random Telegraph Signal (RTS) seen in the leakage currents from radiation induced hot pixels in Charge Coupled Devices (CCDs), but in the context of stuck bits in Synchronous Dynamic Random Access Memories (SDRAMs). Our analysis suggests that pseudo-random sticking and unsticking of the SDRAM bits is due to thermally induced fluctuations in leakage current through displacement damage complexes in depletion regions that were created by high-energy neutron and proton interactions. It is shown that the number of observed stuck bits increases exponentially with temperature, due to the general increase in the leakage currents through the damage centers with temperature. Nevertheless, some stuck bits are seen to pseudo-randomly stick and unstick in the context of a continuously rising trend of temperature, thus demonstrating that their damage centers can exist in multiple widely spaced, discrete levels of leakage current, which is highly consistent with RTS. This implies that these intermittently stuck bits (ISBs) are a displacement damage phenomenon and are unrelated to microdose issues, which is confirmed by the observation that they also occur in unbiased irradiation. Finally, we note that observed variations in the periodicity of the sticking and unsticking behavior on several timescales is most readily explained by multiple leakage current pathways through displacement damage complexes spontaneously and independently opening and closing under the influence of thermal vibrations.
26 citations
Cites background from "Microdose analysis of ion strikes o..."
...There has been some ongoing debate as to whether this phenomenon is attributable to a microdose mechanism or to localized displacement damage complexes (Single Particle Displacement Damage Effects-SPDDE) [4], [5]....
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TL;DR: In this paper, the heavy ion induced electron/hole charge yield in silicon-oxide versus electric field was determined by comparing the voltage shifts of MOSFET transistors irradiated with 10-keV X-rays and several different heavy ions.
Abstract: The heavy-ion induced electron/hole charge yield in silicon-oxide versus electric field is presented. The heavy-ion charge yield was determined by comparing the voltage shifts of MOSFET transistors irradiated with 10-keV X-rays and several different heavy ions. The obtained charge yield for the heavy ions is in average nearly an order of magnitude lower than for the X-rays for the entire range of measured electric fields.
23 citations
Cites background from "Microdose analysis of ion strikes o..."
...Indeed, recent works investigating the heavy-ion induced degradation of power MOSFETs have shown that heavy-ion induced microdose effects can lead to voltage shifts at very low ion fluence [1], [2]....
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TL;DR: The use of multi-scale simulations are demonstrated to examine two radiation-related problems: enhanced low-dose-rate sensitivity (ELDRS) in bipolar transistors and single-event effects (SEE) in CMOS integrated circuits.
Abstract: As integrated circuits become smaller and more complex, it has become increasingly difficult to simulate their responses to radiation. The distance and time scales of relevance extend over orders of magnitude, requiring a multi-scale, hierarchical simulation approach. This paper demonstrates the use of multi-scale simulations to examine two radiation-related problems: enhanced low-dose-rate sensitivity (ELDRS) in bipolar transistors and single-event effects (SEE) in CMOS integrated circuits. Examples are included that demonstrate how information can be passed from simulation tools operating at one level of abstraction to those operating at higher levels, while maintaining accuracy and gaining insight.
20 citations
Cites background from "Microdose analysis of ion strikes o..."
...active devices [49], [60], microdose effects [61], and highly localized displacement damage, can be analyzed quantitatively....
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References
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Book•
01 Jan 1989TL;DR: In this article, Hughes et al. present a survey of the effects of radiation on MOS devices and circuits, including hardening technology, process-induced radiation effects, and interface traps.
Abstract: Historical Perspective (H. Hughes). Electron--Hole Generation, Transport, and Trapping in SiO2 (F. McLean, et al.). Radiation--Induced Interface Traps (P. Winokur). Radiation Effects on MOS Devices and Circuits (P. Dressendorfer). Radiation--Hardening Technology (P. Dressendorfer). Process--Induced Radiation Effects (T. Ma). Source Considerations and Testing Techniques (K. Kerris). Transient--Ionization and Single--Event Phenomena (S. Kerns). Index.
1,026 citations
"Microdose analysis of ion strikes o..." refers background in this paper
...The field oxide and the bird's beak structure are also expected to affect response [l]....
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TL;DR: In this article, the physical interactions of ions with MOS gate oxides-charge generation, recombination, transport, and trapping were examined, and it was concluded that hard errors from single ions are to be expected, and should not be considered surprising.
Abstract: Hard errors from single heavy ions have been reported in advanced commercial CMOS memories. The authors examine the physical interactions of ions with MOS gate oxides-charge generation, recombination, transport, and trapping. They also consider device and circuit characteristics. They conclude that hard errors from single ions are to be expected, and should not be considered surprising. >
116 citations
"Microdose analysis of ion strikes o..." refers background in this paper
...Oldham predicted that gate oxides will not trap charge if the thickness is less than a critical distance, 7.5 nm [ 14 ]....
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...Other studies have shown that SHE occur in SRAMs on the order of 50 krad of TID [2], [ 14 ]....
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TL;DR: In this paper, the authors addressed the problem of threshold voltage variation in flash memory cells after heavy ion irradiation by using specially designed array structures and test instruments, and proposed a new mechanism, based on the excess of positive charge produced by a single ion, temporarily lowering the tunnel oxide barrier (positive charge assisted leakage current) and enhancing the tunneling current.
Abstract: We have addressed the problem of threshold voltage (V/sub TH/) variation in flash memory cells after heavy-ion irradiation by using specially designed array structures and test instruments. After irradiation, low V/sub TH/ tails appear in V/sub TH/ distributions, growing with ion linear energy transfer (LET) and fluence. In particular, high LET ions, such as iodine used in this paper, can produce a bit flip. Since the existing models cannot account for large charge losses from the floating gate, we propose a new mechanism, based on the excess of positive charge produced by a single ion, temporarily lowering the tunnel oxide barrier (positive charge assisted leakage current) and enhancing the tunneling current. This mechanism fully explains the experimental data we present.
85 citations
TL;DR: In this paper, the trapped charge density in the LOCOS bird's beak resulting from irradiating a conventional NMOSFET has been analyzed using a 2D finite element simulation.
Abstract: The trapped charge density in the LOCOS bird's beak resulting from irradiating a conventional NMOSFET has been analysed using a 2D finite element simulation. This paper shows a maximum of trapped charge density in the bird's beak region. The resulting voltage shift of the lateral parasitic transistor in the bird's beak region induces a high leakage current, and prevents any normal circuit operation. The silicon doping level, the supply voltage and the bird's beak shape are key parameters for device hardening of rad-tolerant technologies.
81 citations
"Microdose analysis of ion strikes o..." refers methods in this paper
...Several numerical simulations have been conducted [9]‐[ 12 ]....
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TL;DR: In this article, a novel way to measure the radiation characteristics of DRAM memory cells is presented, where the change in retention time (the time period required for a cell to upset without refreshing) is used to evaluate the effect of irradiation on the DRAM cells.
Abstract: A novel way to measure the radiation characteristics of DRAM memory cells is presented. Radiation exposure tends to drive retention times lower for cells. The change in retention time (the time period required for a cell to upset without refreshing) is used to measure the effect of irradiation on the DRAM cells. Both the radiation response of a single DRAM cell and the response of all cells as a statistical whole are analyzed.
52 citations