New ground-based measurements of the cosmic-ray induced neutron flux and its energy distribution have been made at several locations across the United States using an extended-energy Bonner sphere ...spectrometer. The data cover over twelve decades of neutron energy, from meV to GeV. An expression to scale the flux to other locations has been developed from a fit to the altitude dependence of our measurements and an expression from the literature for the geomagnetic and solar-activity dependence of neutron monitor rates. In addition, an analytic expression is provided which fits the neutron spectrum above about 0.4 MeV. The neutron flux is important for estimating the soft-error rate in computer memories and recent computer logic devices.
Experimental results are presented on single-bit-upsets (SBU) and multiple-bit-upsets (MBU) on a 45 nm SOI SRAM. The accelerated testing results show the SBU-per-bit cross section is relatively ...constant with technology scaling but the MBU cross section is increasing. The MBU data show the importance of acquiring and analyzing the data with respect to the location of the multiple-bit upsets since the relative location of the cells is important in determining which MBU upsets can be corrected with error correcting code (ECC) circuits. For the SOI SRAMs, a large MBU orientation effect is observed with most of the MBU events occurring along the same SRAM bit-line; allowing ECC circuits to correct most of these MBU events.
Experimental data are presented showing that low energy (<2 MeV) proton irradiation can upset exploratory 65 nm node, silicon-on-insulator circuits. Alpha particle SER data, modeling and simulation ...results provide a plausible mechanism. This work suggests that track structures need to be understood and effectively modeled, especially for small, modern devices.
The low-energy proton energy spectra of all shielded space environments have the same shape. This shape is easily reproduced in the laboratory by degrading a high-energy proton beam, producing a ...high-fidelity test environment. We use this test environment to dramatically simplify rate prediction for proton direct ionization effects, allowing the work to be done at high-energy proton facilities, on encapsulated parts, without knowledge of the IC design, and with little or no computer simulations required. Proton direct ionization (PDI) is predicted to significantly contribute to the total error rate under the conditions investigated. Scaling effects are discussed using data from 65-nm, 45-nm, and 32-nm SOI SRAMs. These data also show that grazing-angle protons will dominate the PDI-induced error rate due to their higher effective LET, so PDI hardness assurance methods must account for angular effects to be conservative. We show that this angular dependence can be exploited to quickly assess whether an IC is susceptible to PDI.
We present low-energy proton single-event upset (SEU) data on a 65 nm SOI SRAM whose substrate has been completely removed. Since the protons only had to penetrate a very thin buried oxide layer, ...these measurements were affected by far less energy loss, energy straggle, flux attrition, and angular scattering than previous datasets. The minimization of these common sources of experimental interference allows more direct interpretation of the data and deeper insight into SEU mechanisms. The results show a strong angular dependence, demonstrate that energy straggle, flux attrition, and angular scattering affect the measured SEU cross sections, and prove that proton direct ionization is the dominant mechanism for low-energy proton-induced SEUs in these circuits.
Experimental results are presented on proton induced single-event-upsets (SEU) on a 65 nm silicon-on-insulator (SOI) SRAM. The low energy proton SEU results are very different for the 65 nm SRAM as ...compared with SRAMs fabricated in previous technology generations. Specifically, no upset threshold is observed as the proton energy is decreased down to 1 MeV; and a sharp rise in the upset cross-section is observed below 1 MeV. The increase below 1 MeV is attributed to upsets caused by direct ionization from the low energy protons. The implications of the low energy proton upsets are discussed for space applications of 65 nm SRAMs; and the implications for radiation assurance testing are also discussed.
XIA has provided IBM with a prototype ultralow background alpha particle counter for evaluation. Results show a significant decrease in background compared to other commercial counters allowing for ...rapid measurement of low-emissivity materials.
Contact resistances are directly measured for contacts with sizes from 25 to 330 nm using e-beam based nano-TLM devices. Record low contact resistivities ~1.5 × 10 -9 Ω· cm 2 are extracted from ...Ni(Pt) silicide contacts on in situ boron-doped Si 0.7 Ge 0.3 with a chemical boron-doping density of 2 × 10 21 /cm 3 . This is very promising for pMOS applications beyond the 10-nm node. A clear dependence of contact resistance on the silicide thickness has also been found.
In this paper, we review the current status of single-event upsets caused by alpha-particles in IBM circuits and technology. While both alpha-particles and cosmic radiation can induce upsets, the ...alpha-particle-induced upset rate has become an increasingly important issue because alpha-particle-induced upsets are no longer limited to memory circuits. Latch circuits have become highly sensitive to alpha-particles. The alpha-particle-induced upset rate of latch circuits is one of the most critical issues for microprocessors requiring both high performance and high reliability. PUBLICATION ABSTRACT
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