In this paper, the soft error rate (SER) induced by neutrons in 65-nm 10T static random access memory (SRAM) is measured over a wide range of supply voltages from 1.0 to 0.3 V. The results show that the neutron-induced SER at 0.3 V is around eight times that at 1.0 V. The dependence of multiple cell upsets (MCUs) on the supply voltage and on the distance between well ties is also investigated. The dependence of the MCU rate on the supply voltage between 1.0 and 0.5 V is small and increases as the voltage is reduced below 0.5 V. This is because the effect of another mechanism, such as charge-sharing, becomes larger in the subthreshold region, rather than the parasitic bipolar effect, which is considered the dominant mechanism causing MCUs in SRAM at the nominal supply voltage in our design.