Relations Between Basic Nuclear Data and Single-Event Upsets Phenomena
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Relations Between
Basic Nuclear Data and Single-Event Upsets Phenomena Jan Blomgren, Bo Granbom, Thomas Granlund, and Nils Olsson
Abstract This article approaches single-event upset (SEU) problems from the standpoint of experimental nuclear physics, with a focus on certain neutron experiments and neutron data essential for SEU studies. A review is given of some research programs, both basic and applied, that are strongly motivated by SEU applications. Some specific examples are presented from the The (short for Theodor) Svedberg Laboratory (TSL) in Uppsala, Sweden: First, using the quasi-monoenergetic neutron beam, SEU cross sections (of chips) are measured over the neutron energy range of 20–150 MeV. Data from the same technology generation, in general, can be fitted into a simple curve. Second, the particle origins of SEUs are discussed from the framework of neutron–nucleus spallation reactions. Keywords: microelectronics, nuclear data, single-event upsets.
Introduction Radiation effects induced by terrestrial cosmic rays in microelectronics—on aircraft as well as at sea level—have attracted much attention in the last two decades. When a memory circuit is exposed to cosmic rays, the memory state of a cell can be flipped, from a 1 to a 0 or vice versa, resulting in an error in a bit. This phenomenon is called a single-event upset (SEU), or soft error. This is a random error, which is irreproducible, but does not induce any hardware damage in the circuit. But as one bit of data is corrupted, it raises serious reliability and performance issues in many applications in which data integrity is of critical importance. First predicted in the late 1970s, SEUs were experimentally confirmed in mainframe computers at IBM and extensively studied by the researchers there during the 1980s and 1990s.1 Similar software errors were rediscovered by accident in a portable personal computer used in an airplane a few years ago. The PC SEU effects were later verified under controlled conditions, in flight measurements2,3 and in laboratory tests.4–6
MRS BULLETIN/FEBRUARY 2003
A single-event upset, at the most fundamental level, is caused by a single particle hitting a device. This is in contrast to the permanent damage in electronics caused by an integrated radiation dose, which is usually delivered by a high particle flux. At flight altitudes, as well as at sea level, the cosmic rays are dominated by neutrons and muons. Neutrons interact with device materials through the strong nuclear force, whereas muons interact with these materials through the much weaker electromagnetic force. As far as SEUs are concerned, neutrons are the most important part of the terrestrial cosmic rays. This has been pointed out in the article by Tang and Rodbell in this issue of MRS Bulletin, and also in References 7–10. The status of our current knowledge of terrestrial neutron flux on the ground and in the atmosphere is reviewed by Goldhagen in this issue. Since neutrons do not carry electric charge, they do not ionize the device they hit. However, wh
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