Evaluation of a COTS 65-nm SRAM Under 15 MeV Protons and 14 MeV Neutrons at Low VDD

This article presents an experimental study on the sensitivity of a commercial-off-the-shelf (COTS) bulk 65-nm static random access memory (SRAM) under 15.6 MeV proton irradiation when powered up at ultralow bias voltage. Tests were run on standby and while reading the memory. Results show obvious evidence indicating that decreasing the bias voltage below 1 V exponentially increases the number of observed errors. Single-bit upsets (SBUs) and multiple-cell upsets (MCUs) (mostly with vertical shapes according to the manufacturers' layout) are reported and their behavior is analyzed in this article. Predictions on the single-event upset (SEU) sensitivity obtained with the multiscales single-event phenomena predictive platform (MUSCA-SEP3) modeling tool are also provided and compared with the experimental results. These are also compared with 14.2 MeV neutrons, showing a significant difference in the cross sections for both irradiation sources. Total ionizing dose (TID) tests and GEANT4 simulations were also run to check for the reason behind the difference in the cross section between these two particles.