Alpha-SER determination from word-line voltage margin (WVM) measurements: Design architecture and experimental results

Experimental results from a 65nm CMOS commercial technology SRAM test chip reveal a high correlation between the word-line voltage margin (WVM)-defined as the difference between the memory nominal supply voltage and the lower mean voltage applied to the word-line capable of writing a cell - and the measured circuit alpha-SER. Additional experiments show that no other memory cell robustness-related parameters (like the minimum supply voltage during hold or read) exhibit such correlation. After an initial irradiation experiment on a reduced sample circuits, the WVM technique can be used to estimate the alpha-SER levels on each particular circuit without requiring additional irradiation experiments. The technique requires a specific memory design modification that does not degrade circuit performance while circuit area increase is negligible.