Criticality of Low-Energy Protons in Single-Event Effects Testing of Highly-Scaled Technologies

The thermal neutron threat to the reliability of electronic devices caused by 10 B capture is a recognized issue that prompted changes in the manufacturing process of electronic devices with the aim of limiting as much as possible the presence of this isotope nearby device sensitive volumes. 14 N can also capture thermal neutrons and release low-energy protons (through the 14 N(n,p) 14 C reaction) that have high enough linear energy transfer to cause single-event upsets (SEU). Typically, nitrogen is used in thin barrier layers made of TaN or TiN or even as insulator in the form of Si3N4. Numerical simulations on sensitive volumes calibrated on proton and ion experimental data and with an accurate description of the metallization layer on top of the sensitive region show that the presence of nitrogen in these thin barrier layers can be enough to justify the experimentally observed thermal neutron SEU cross section for a static random access memory sensitive to low-energy protons. Nevertheless, the expected SEU cross section from thermal neutrons is usually a few orders of magnitude lower than that of high-energy particles, therefore, not representing an important threat in atmospheric applications. At the same time, for high-energy accelerators, the contribution to the total soft error rate could become substantial, though easy to handle by margins.

Section: Introductionmentioning

confidence: 99%

An Analysis of the Significance of the ¹⁴N(n, p) ¹⁴C Reaction for Single-Event Upsets Induced by Thermal Neutrons in SRAMs

Coronetti

Alía

Lucsanyi

et al. 2023

“…Remarkably, these differences in the travelled paths may lead to protons reaching the active area with LET values that may differ up to 50%. This highlights that care is needed when evaluating SEU from proton direct ionization and predicting the corresponding error rate in space, as already shown in recent papers [3]- [5]. When possible, the physical removal of layers above the sensitive region would be of course the ideal solution [4], but also simulations can greatly help to gain insight into energy loss in the overlayers, if details on the die stack are available.…”

Section: A Trim and Srim Simulationsmentioning

confidence: 85%

“…The threshold LET for heavy-ion induced upsets in CMOS technology is decreasing as the device dimensions are scaled down and bit flips from proton direct ionization have been reported on 65-nm SOI latches and SRAM cells for the first time in 2007 by IBM researchers [1], [2]. Today the effects of low-energy protons are a hot topic: the importance of these particles as a potentially relevant source of errors in space has been recently highlighted [3] and the criticalities of the related testing have been discussed in literature [4], [5].…”

Section: Introductionmentioning

confidence: 99%

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

Bagatin

Gerardin

Paccagnella

et al. 2017

Abstract-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.

“…D IRECT ionization from low-energy protons (LEP) and related upsets in highly integrated memory devices have been a subject of study for one and a half decades [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16]. When the critical charge is low enough (as it is the case for advanced node technologies, < 90 nm [5]), even LEPs can have sufficient linear energy transfer (LET) [0.1-0.5 MeV/(mg/cm 2 )] to cause a bit flip [16].…”

Section: Introductionmentioning

confidence: 99%

Proton Direct Ionization Upsets at Tens of MeV

Coronetti

Alía

Lucsanyi

et al. 2023

Experimental mono-energetic proton single-event upset (SEU) cross-sections of a 65 nm low core-voltage static random access memory (SRAM) were found to be exceptionally high not only at low energies (< 3 MeV), but also at energies > 3 MeV and extending up to tens of MeV. The SEU crosssection from 20 MeV protons exceed the 200 MeV proton SEU cross-section by almost a factor of 3. Similarly, mono-energetic neutron cross-sections at 14 MeV are about a factor of 3 lower than the 20 MeV proton cross-section. Thanks to Monte-Carlo (MC) simulations it was determined that this strong enhancement is due to the proton direct ionization process as opposed to the elastic and inelastic scattering processes that dominate the SEU response above 3 MeV in other SRAMs. As shown by means of a detailed energy deposition scoring analysis, however, this does not appear to be caused by the critical charge of the SRAM being lower than the charge resulting from the average proton ionization through the linear energy transfer (LET). On the other hand, this is caused by high-energy δ-rays (> 1 keV) that can deposit their full kinetic energy within the sensitive volume (SV) of a cell despite their range being theoretically much longer than the characteristic size of the SV. Multiple scattering events are responsible for increasing the trajectory path of the δ-rays within the sensitive volume, resulting in a 6 fold increase in the probability of upset with respect to the sole electron ionization.