Heavy ion energy influence on multiple-cell upsets in small sensitive volumes: from standard to high energies

The 28 nm process has a high cost-performance ratio and has gradually become the standard for the field of radiation-hardened devices. However, owing to the minimum physical gate length of only 35 nm, the physical area of a standard 6T SRAM unit is approximately \(0.16\,\upmu \hbox{m}^{2}\), resulting in a significant enhancement of multi-cell charge-sharing effects. Multiple-cell upsets (MCUs) have become the primary physical mechanism behind single-event upsets (SEUs) in advanced nanometer node devices. The range of ionization track effects increases with higher ion energies, and spacecraft in orbit primarily experience SEUs caused by high-energy ions. However, ground accelerator experiments have mainly obtained low-energy ion irradiation data. Therefore, the impact of ion energy on the SEU cross section, charge collection mechanisms, and MCU patterns and quantities in advanced nanometer devices remains unclear. In this study, based on the experimental platform of the Heavy Ion Research Facility in Lanzhou, low- and high-energy heavy-ion beams were used to study the SEUs of 28 nm SRAM devices. The influence of ion energy on the charge collection processes of small-sensitive-volume devices, MCU patterns, and upset cross sections was obtained, and the applicable range of the inverse cosine law was clarified. The findings of this study are an important guide for the accurate evaluation of SEUs in advanced nanometer devices and for the development of radiation-hardening techniques.