Impact of TID Irradiation on Static Noise Margin of 22 nm UTBB FD-SOI 6-T SRAM Cells

Impact of total ionizing dose (TID) irradiation on Static Noise Margin (SNM) of 22 nm Ultrathin Body and Buried oxide (BOX) Fully Depleted Silicon-On-Insulator (UTBB FD-SOI) 6-T static random-access memory (SRAM) cells is investigated in this article. TID effect on SNM was measured by the single SRAM cell test structure allowing precise measurement of cell SNM under hold, read, and write modes. Experimental results show that SNM of 22 nm UTBB FD-SOI SRAM cell is significantly decreased by TID. And read SNM is more vulnerable to irradiation, even to be lowered down 0 mV at 500 krad(Si), leading to the read functionality failure. The bias-dependent TID induced threshold voltage shift is responsible for the significant SNM decrease. Moreover, the TID effect on SNM, including transistor-to-transistor variation caused by within-die process and TID damage variability, is explored by Monte Carlo simulation, illustrating that the TID effect on SNM will be underestimated by measurement of a limited number of SRAM cells.