SEU characterization of commercial and custom-designed SRAMs based on 90 nm technology and below

Lucsanyi

et al. 2023

IEEE Trans. Nucl. Sci.

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: Discussionmentioning

confidence: 99%

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

Lucsanyi

et al. 2023

IEEE Trans. Nucl. Sci.

“…The experimental data [16] were collected at various accelerators capable of delivering quasi-mono-energetic low-and high-energy protons [respectively, CNA [27] and RADEF [28,29] for low-and intermediate-energy protons (< 20 MeV), and PARTREC [30] and PSI [31] for high-energy protons (> 20 MeV)]. The experimental details are reported in [16,32]. Other than the proton cross-sections, it is relevant to report the 14 MeV neutron cross-sections [32,33] (measured at FNG [34]) in order to compare it with proton cross-sections in the few tens of MeV energy interval.…”

Section: Experimental Observationsmentioning

confidence: 99%

“…The experimental details are reported in [16,32]. Other than the proton cross-sections, it is relevant to report the 14 MeV neutron cross-sections [32,33] (measured at FNG [34]) in order to compare it with proton cross-sections in the few tens of MeV energy interval.…”

Section: Experimental Observationsmentioning

confidence: 99%

Proton Direct Ionization Upsets at Tens of MeV

Lucsanyi

et al. 2023

IEEE Trans. Nucl. Sci.

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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.

“…D50 [3], [4] is the former installation at ILL used for irradiation to electronics that will no longer be used for such purpose as of 2021. The fast neutrons released by the reactor are cooled down to thermal energies (peaking at 13 meV) by means of liquid deuterium at 20 K. The corresponding equivalent thermal neutron flux (at 25 meV) was 1.1 x 10 9 n/cm 2 /s at the time of these tests.…”

Section: A Ill -D50mentioning

confidence: 99%

Thermal-to-high-energy neutron SEU characterization of commercial SRAMs

2021 IEEE Nuclear and Space Radiation Effects Conference (NSREC)

Létiche

et al. 2021

Self Cite