IMPLICATIONS OF ANGLE OF INCIDENCE IN SEU TESTING OF MODERN CIRCUITS

Simulations show that ignoring the angular dependence of proton SEU cr oss sections produces errors in predictions of SEU rates in space. Mor eover, they suggest that devices with thin sensitive volumes may upset to protons at grazing incidence despite high threshold LET values (>8 0 MeV cm(2)) at normal incidence. Incorporating angular effects in spa ce predictions requires accurate knowledge of the dimensions of the se nsitive volume associated with the SEU-sensitive junction, especially the thickness. A method is proposed for using proton SEU measurements at different angles and energies combined with simulations to determin e the thickness of the sensitive volume and to test the reliability of the predictions.