Impact of High TID Irradiation on Stability of 65 nm SRAM Cells

Impact of high total ionizing dose (TID) irradiation on stability of 65 nm static random-access memory (SRAM) cells is investigated in this article. The stability of 65 nm SRAM cells is measured not only by the SRAM array but also by the independent cell test structure. The test chip has been subjected to a TID irradiation of 200 Mrad(Si). Experimental results show a reverse data pattern imprinting effect, i.e., irradiated 65 nm SRAM cells are more inclined to the complementary TID data pattern, and the above asymmetry of irradiated 65 nm SRAM cells is due to the bias-dependent shift in threshold of the pull-down nMOSFETs constituting the SRAM cell.