The effects of proton irradiation on the subsequent time-dependent dielectric breakdown (TDDB) of partially depleted SOI devices are experimentally investigated.It is demonstrated that heavy-ion irradiation will induce the decrease of TDDB lifetime for many device types,but we are amazed to find a measurable increase in the TDDB lifetime and a slight decrease in the radiation-induced leakage current after proton irradiation at the nominal operating irradiation bias.We interpret these results and mechanisms in terms of the effects of radiation-induced traps on the stressing current during the reliability testing,which may be significant to expand the understanding of the radiation effects of the devices used in the proton radiation environment.