Upset Phenomena Induced by Energetic Protons and Electrons

Large scale integrated static Random-Access-Memory devices have been exposed to 18-130 MeV protons and found to exhibit soft errors at rates of about one upset for 109 protons/cm2. These rates are two to three orders of magnitude lower than previously observed for dynamic memory devices exposed under identical conditions. Both sets of data appear to be consistent with model calculations based on the assumption that the errors are the result of secondary particles created in inelastic interactions between the incident protons and the nuclei of atoms comprising the device. The model was found to agree with pulse height spectra obtained with silicon detectors of various thicknesses exposed to 130 MeV protons. Both types of memory devices were also exposed to short bursts (10-150 nsec) of 10 ± 0.5 MeV electrons. A sharp threshold was found in the soft-error response to increasing dose rates. Most devices became more sensitive with increasing duration of the electron pulse in the sense that they required lower dose rates to exhibit soft errors. On the other hand the threshold total dose for failure increased with pulse duration.