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The key issues of cosmic-ray-induced softerror rates, SER (also referred to as singieevent upset, SEU, rates) in microeiectronic devices are discussed from the viewpoint of fundamental atomic and nuciear interactions between high-energy particles and semiconductors. From sea level to moderate altitudes, the cosmic ray spectrum is dominated by three particle species: nucleons (protons and neutrons), pions, and muons. The characteristic features of high-energy nuclear reactions of these particles with light elements are reviewed. A major cause of soft errors is identified to be the ionization electron-hole pairs induced by the secondary nuclear fragments produced in certain processes. These processes are the inelastic collisions between the cosmic ray particles and nuclei in the host material. A state-of-the-art nuclear spallation reaction model, NUSPA, is developed to simulate these reactions. This model is tested and validated by a large set of nuclear experiments. It is used to generate the crucial database for the soft-error simulators which are currently used throughout IBM for device and circuit analysis. The relative effectiveness ®Copyright 1996 by International Business Machines Corporation. Copying in printed form for private use is permitted without payment of royalty provided that (1) each reproduction is done without alteration and (2) the Journal reference and IBM copyright notice are included on the first page. The title and abstract, but no other portions, of this paper may be copied or distributed royalty free without further permission by computer-based and other information-service systems. Permission to republish any other portion of this paper must be obtained from the Editor.of nucleons, plons, and muons as soft-errorinducing agents is evaluated on the basis of nuclear reaction rate calculations and energydeposition analysis.

Recent renewed interest in the time-dependentHartree-Fock approximation (TDHF) for the microscopic description of the dynamics of nuclear systems was pioneered by Bonche, Koonin, and Negele. 1 Since then, many TDHF calculations were carried out 2 and many different theoretical investigations were initiated. 2 ' 3 However, in the TDHF approximation, the fermions are assumed to interact only through the mean field and the collisions between particles due to residual interactions are neglected. Because particle collisions are capable of altering the occupation probabilities and dissipating energies, the pattern of behavior of the quantum fluid can be that of hydrodynamics 4 or elastic response, 5 ' 4 depending on the degree of particle collisions. A careful analysis of particle collision also helps our understanding of dissipative phenomena for which much progress has been made recently. 6 However, the incorporation of particle collisions into the TDHF approximation has, up to now, not been formulated.Previous extension of the TDHF approximation was discussed in terms of a multideterminant representation and Pauli's master equation. 4 In this Letter, we present a different extended time-by Do H. . 9 W. M. MacDonald, to be published. 10 A o Mekjian and W. MacDonald, Phys. Rev. Lett. JL8, 706 (1967). 11 Wo M. MacDonald, " Strength Functions for the Analysis of Configuration Broadened States" (to be published). dependent Hartree-Fock approximation (ETDHF) in which collisions between particles are explicitly taken into account. The final set of equations turns out to be simple and physically transparent and may be of practical interest to those working in the field of the dynamics of nuclear or other fermion systems. Furthermore, concepts such as entropy, temperature, thermal equilibrium, and local equilibrium can be naturally and quantitatively introduced. The approach from nonequilibrium to thermal equilibrium can be quantitatively studied.Being the configuration-space analog of the quantum Boltzmann equation, our set of equations should retain certain characteristics of the Boltzmann equation. It should be closed Markovian in the sense that all the quantities are to be specified at the same time coordinate. 7 This requirement necessitates an integration over the collision history analytically. Just as in the Boltzmann equation, we wish to keep terms only up to the second order in the residual interaction. Finally, as the Boltzmann equation violates timereversal invariance, the latter concept needs to be properly introduced.We formulate an extended time-dependent Hartree-Fock approximation which includes particle collisions. As the configuration-space analog of the quantum Boltzmann equation, it can be utilized to study the dynamics of nuclear or other fermion systems when irreversible dissipation is present. 1070