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

Impact of total ionizing dose (TID) Irradiation on Static Noise Margin (SNM) of 22nm Ultra-Thin Body and Buried oxide Fully Depleted Silicon-On-Insulator (UTBB FD-SOI) 6-T static random access memory (SRAM) Cells is investigated in this paper. 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 22nm UTBB FD-SOI SRAM cell is significantly decreased by TID. And, read SNM is more vulnerable to irradiation, even to be lowered down 0mV at 500krad(Si), leading to the read functionality failure. The bias-dependent TID induced threshold voltage shift is responsible for the significant SNM decrease. Moreover, 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 TID effect on SNM will be underestimated by measurement of limited number of SRAM cells.