Simple Calculations of Proton SEU Cross Sections from Heavy Ion Cross Sections

Simple expressions, based on previous analytical and empirical models for the energy deposited by protons through their p+Si interactions, are proposed for calculating proton induced SEU cross sections from heavy ion cross sections in devices with sub-micron sensitive volumes. Calculations for modern devices yield good agreement with the experiments. The implications on calculating SEU rates in space are discussed

I. Introduction

Single event upsets (SEUs) are caused in space by protons and heavier ions (HI). Most ground tests are conducted using the heavier ions for which the SEU sensitivity is expresses by cross section versus the ion linear energy transfer (LET denoted by ), i.e., by . in most cases, protons have too low LET to cause SEUs directly. They may induce SEUs through ions emitted in their nuclear interactions with the device matter. Assuming a flux of protons with energy reaching the device, a proton has the probability that a secondary ion of its nuclear interaction hits the sensitive (to SEU) volume (SV) with a given [1]. Note that the interaction point can be away from the SV and that is not the secondary ion LET value at that point but rather at the SV. If is known, the proton-induced SEU ( -SEU) cross section is easily calculable by integrating (see below). This approach is good for small SVs where the secondary-ion LET is well defined.