As a continuation and a development of previous studies of our group that were devoted to the investigation of nuclear reactions induced by protons of moderately high energy (between 10 and 400 MeV) in silicon, aluminum, and tungsten atoms, the results obtained by exploring nuclear reactions on atoms of copper, which is among the most important components in materials for contact pads and pathways in modern and future ultralarge-scale integration circuits, especially in three-dimensional topology, are reported in the present article. The nuclear reactions in question lead to the formation of the mass and charge spectra of recoil nuclei ranging fromheavy target nuclei down to helium and hydrogen. The kineticenergy spectra of reaction products are calculated. The results of the calculations based on the procedure developed by our group are compared with the results of calculations and experiments performed by other authors.

Рассматривается фрагментация вольфрама, возникающая в ядерных реакциях под действием космических протонов в электронном оборудовании космических аппаратов. Во многих современных микросхемах с трехмерной слоевой архитектурой вольфрам используется в качестве межуровневой проводящей связи. В рамках предравновесной модели по программам TALYS и EMPIRE-II-19 проведены расчеты таких характеристик фрагментации вольфрама, как сечения упругого и неупругого рассеяния протонов с энергией от 30 до 240 МэВ, выход изотопов и изобар, их энергетические, зарядовые и массовые распределения, а также энергетические спектры отдачи. Показано, что фрагментация вольфрама оказывает существенное влияние на прогнозирование сбоев в электронном оборудовании космических аппаратов.

Tungsten fragmentation arising in nuclear reactions induced by cosmic-ray protons in space-vehicle electronics is considered. In modern technologies of integrated circuits featuring a three-dimensional layered architecture, tungsten is frequently used as a material for interlayer conducting connections. Within the preequilibrium model, tungsten-fragmentation features, including the cross sections for the elastic and inelastic scattering of protons of energy between 30 and 240 MeV; the yields of isotopes and isobars; their energy, charge, and mass distributions; and recoil energy spectra, are calculated on the basis of the TALYS and EMPIRE-II-19 codes. It is shown that tungsten fragmentation affects substantially forecasts of failures of space-vehicle electronics.

In modern integrated-circuit (IC) technology, an increase in transistor density leads to the fact that the insulated current-carrying metallized layers occupy a continuously increasing part of the chip volume. The aluminum in these layers is often replaced by copper and tungsten. The spallation reaction of Wnuclei induced by protons with an energy of ∼1 GeV creates a huge number of isotopes of different elements (from O to Ta). Experimental data on cross sections of the aforementioned nuclear reactions and the average velocities of residual fission fragments have been published. In this work, the published data are analyzed and the ionization effects of certain fragments of the reaction W(p, X) are estimated. It is assumed that this reaction occurs in the sensitive regions of transistors in an IC manufactured via 3D technology with clips made from tungsten rods.

Radiation effects leading to degradation and failures in the operation of electronic equipment on board a space ship are of increasing concern in connection with the constantly decreasing sizes and increasing density of modern onboard microelectronics elements. The propagation of the energetic heavy ions of galac-tic cosmic rays (GCR) through a multi-layer structure (an integrated-circuit prototype) is discussed in the paper. The amount of electron-hole pairs induced by an ion in the sensitive area of a transistor has been esti mated with consideration for energy losses in the chip body as well as in the protective oxide layers, contacts, and metallized layers. Calculation of the energy of various particles initiating the generation of a charge potentially capable to induce a single failure of onboard electronics has been carried out. The existence of a spatial region from which heavy fragments of a nuclear reaction, with a kinetic energy sufficient enough to induce a charge above the critical one, can penetrate into the gate region of a transistor has been demon-strated.

В статье рассматривается прохождение энергичными тяжелыми ионами галактических космических лучей через многослойную структуру – прототип интегральной схемы. Оценка индуцированного ионом числа электронно-дырочных пар в чувствительной области транзистора проведена с учетом потерь энергии в корпусе микросхемы, а также в защитных оксидных слоях, в контактах и металлизированных слоях. Проведены расчеты энергии различных частиц, вызывающих генерацию заряда, потенциально способного приводить к одиночному сбою бортовой электроники. Было показано, что имеется пространственная область, из которой тяжелые фрагменты ядерных реакций могут проникать в подзатворную область транзистора, обладая кинетической энергией, достаточной для индуцирования заряда с концентрацией выше критической.

The radiation environment in space is reviewed in short as an impact factor affecting onboard spacecraft electronics. The mass and energy distributions of the heavy component of space radiation and the contribution of galactic cosmic rays to the general flux are analyzed during a quiet period in solar activity. The nature of the limitations in the concept of linear energy transfer, including the effects of electronic semiconductor component crystallinity, is discussed. Protective measures against upsets in onboard electronics, caused by cosmic ray ions, are considered.

The accuracy attained in theoretically estimating the yields of isotopes and isobars and their energy, charge, and mass distributions in silicon fragmentation that occurs in spacecraft electronics under the effect of cosmic-ray protons is an important factor in forecasting the probability for single-event upsets in the electronics and the reliability of spacecraft operation in general. In previous studies of our group, it was shown that the results of the calculations are highly sensitive to the choice of parameters for opticalmodel potentials. In addition to cross sections for elastic and inelastic proton scattering and charge, mass, and energy distributions of heavy nuclear-reaction products, the results of our calculations for doubledifferential spectra of protons originating from the interaction of highly energetic (30–400 MeV) protons with aluminum and double-differential spectra of other particles (neutrons and alpha particles) arising in competing channels of the p + 27Al reaction are also described in the present article. The calculations in question were performed on the basis of the EMPIRE-II-19 code by using various optical-model potentials, including the Becchetti-Greenlees potential for the (p, n) channel, the Wilmore-Hodgson potential for the (p, n) channel, the Madland potential for the (p, p) channel, the Koning-Delaroche potential for the (p, p) channel, and the McFadden-Satchler potential for the (p, α) channel. A comparative analysis of the double-differential spectra obtained for outgoing protons, neutrons, and alpha particles experimentally and in the calculations of various authors was performed.

The results of calculations for the mass, charge, and energy distributions of nuclear reaction products containing the heavy nuclei that come into being upon the interaction of a proton with energies between 30 and 400 MeV and the 28Si nucleus are presented which is the main chemical element in spacecraft the onboard electronics. Similar calculations for the (p + 27Al) reaction were performed using the EMPIRE-II-19 program using different potentials (Becchetti-Greenlees (p, n), Wilmore-Hodson (p, n), Madland (p, p), Koning-Delaroch (p, p), and Fadden-Satchler (p, α)) of the optical model. The high sensitivity of the kinetic spectrum of the final nuclei to the energy of incident protons, and to the parameters of the optical potentials, is illustrated.

The results obtained by calculating the cross sections for the elastic and inelastic scattering of 50- to 1000-MeV protons interacting with (28)Si, which is the main integrated-circuit element of onboard spacecraft electronics, are presented along with the calculated mass, charge, and energy distributions of heavy products of respective nuclear reactions. To compare the results of the calculations with experimental data, similar calculations were performed for the p + (27)Al reaction. This comparison shows that the elasticand inelastic-scattering cross sections calculated by using the EMPIRE-II-19 code are in satisfactory agreement with available experimental data. Considerably wider scatter of available data is observed in the isotope and isobar yields. A high sensitivity of the kinetic spectrum of the final nuclei to the incident-proton energy is demonstrated.

The cross sections for nuclear reactions induced by 50-to 1000-MeV protons in silicon and the angular distributions of products of these reactions are calculated, along with the recoil-nucleus spectra. The recoil-nucleus spectra are shown to contain a monotonically decreasing portion and a recoil peak, which is manifested most clearly at incident-proton energies in excess of 100 MeV. The possibility of employing these results to derive more reliable estimates of single-event upsets in onboard spacecraft electronics is discussed.

The dynamics of charged particle channeling in a crystal consisting of atomic chains is considered. The multiple scattering of charged particles, introduced by the trajectory integral method, leads to transitions between dynamical modes of the axial channeling, whereby double channeling is a sink for the normal channeling. Volume rechanneling takes place under the conditions of random motion. In this case, up to ∼20% of incident charged particles move in the channeling regime over a depth equal to the normal range, and a considerable fraction of these particles are involved in the double channeling regime.

Lindhard's statistical equilibrium model has been revised considerably after computer simulations, and analytical studies of channeling of light ions through the "crystal of atomic chains" at energies ranging up to relativistic values have been performed. The modification is related to the existence of the regime of "double channeling," which is a regime of regular motion of ions along the rows of atoms. "Normal channeling" is a regime of random walks in the field of atomic chains. Because the ion trajectories are globally unstable in this regime, it admits a statistical description. It is demonstrated that the focusing by pairs of atomic chains increases nuclear scattering and energy losses at angles exceeding considerably Lindhard's angle. Thermal vibrations of the lattice cause transitions between the two above channeling regimes, and the double channeling is an attractor of this diffusion. Ion rechanneling becomes significant at large crystal depths. An important feature observed at these depths is the angular anisotropy-the pattern of "channeling stars." For the initial conditions of random motion, bulk rechanneling causes the appearance of supertails in the ion range distributions.