The damage equivalence of electrons, protons, and gamma rays in MOS devices

In most cases of device testing or characterization in the laboratory, Cobalt-60 sources are commonly used, since they are an inexpensive and convenient source of ionizing radiation. However, some scientists and engineers had suspected for some time that the damage effects from gamma rays in MOS devices are not equivalent to those produced by electrons and protons. The issue of the validity of device test data obtained with Cobalt-60 sources arises when the devices are intended for use on satellites, because the effective space radiation environment consists predominantly of charged particles. This paper reports on an experiment which was designed to establish the relation among the damage effects obtained with Cobalt-60, electron, and proton radiation in order to derive relative damage factors. These factors would then greatly increase the validity of assessments of the vulnerability of MOS LSI devices in space