Impact of Coulomb elastic scattering of protons and iron ions on single-event upsets in a 22 nm SOI SRAM

Abstract

The contribution of Coulomb elastic scattering of protons and heavy ions to single-event upsets (SEUs) is concerned in nanometric electronic devices. In this work, Monte Carlo Geant4 simulations are used to investigate the impact of Coulomb elastic scattering of protons and iron ions on SEUs in a 22 nm silicon-on-insulator (SOI) static random access memory (SRAM). The SEU cross section and multiple-bit upset (MBU) proportion versus incident energy curves for protons and iron ions have been estimated for the SRAM thanks to numerical Geant4 simulations. The ionization processes of ionizing radiation causing SEUs are sorted into three parts: direct ionization from primary particles, indirect ionization from Coulomb recoil atoms, and indirect ionization from secondary particles produced by nuclear reactions. Their relative contributions to SEUs and MBUs are analyzed. The contribution of Coulomb elastic scattering to SEUs cannot be neglected in the energy range from 2 to 6 MeV and below 40 MeV for protons and iron ions, respectively. In the case of iron ion incidence, it is observed that the total SEU cross section decreases in the energy range from 16 to 40 MeV. It can be attributed to the decrease in the Coulomb elastic scattering cross section of iron ions. The probability distributions of energy deposited in the sensitive volumes (SVs) are calculated for iron ions with different energies. The sources of energy deposited in an SV can be sorted into three cases. The three parts of the probability distribution of deposited energy corresponding to these three cases change with increasing incident energy, which can well explain the observed SEU response.