LAUSR

Low-energy (<10 MeV) proton-induced single event upsets (SEUs) were investigated through proton and heavy ion experiments on a 65 nm CMOS bulk SRAM. It is unlikely that 2-10 MeV proton direct ionization can induce SEUs in the 65 nm SRAM and the observed single-bit upsets (SBUs) and multiple cell upsets (MCUs) are mainly induced by the ionization from the recoil ions. The MCUs induced by low-energy protons in our 65 nm SRAM can be corrected by the error correction codes (ECC) because they usually occur along the SRAM bit line. The Geant4 simulations revealed that the SEU cross-section may show two different trends for 2-10 MeV protons depending on the critical charge for triggering a SEU. With the increase of proton energy, SEUs in small critical charge SRAM tend to decrease while SEUs in large critical charge SRAM tend to increase. Further, the Geant4 simulations demonstrated that the SEUs induced by recoil oxygen are more than those induced by recoil silicon and SEUs induced by recoil ions from elastic collisions dominate in our 65 nm CMOS SRAM under 2-10 MeV proton radiation.