SRAM Alpha-SER Estimation From Word-Line Voltage Margin Measurements: Design Architecture and Experimental Results

Abstract

Experimental results from a 65 nm CMOS commercial technology SRAM test chip reveal a linear correlation between a new electrical parameter -- the word-line voltage margin (VWLVM) -- and the measured circuit alpha-SER. Additional experiments show that no other memory cell electrical robustness-related parameters exhibit such correlation. The technique proposed is based on correlating the VWLVM to the SER measured on a small number of circuit samples to determine the correlation parameters. Then, the remaining non-irradiated circuits SER is determined from electrical measurements (VWLVM) without the need of additional radiation experiments. This method represents a significant improvement in time and cost, while simplifying the SER-determination methods since most of the circuits do not require irradiation. The technique involves a minor memory design modification that does not degrade circuit performance, while circuit area increase is negligible.