Nuclear Science and Techniques

Abstract:

Single event upsets (SEUs) induced by heavy ions have been observed in 65 nm SRAMs to quantitatively evaluate the applicability and effectiveness of single-bit error correcting code (ECC) utilizing Hamming Code. The experiment results reveal three interesting phenomena. First, applying ECC does dramatically improve the performance, the SEU cross sections of SRAMs with ECC (at the order of 10??11 cm2/bit) have two orders of magnitude superior than that without ECC (at the order of 10??9 cm2/bit); Second, ineffectiveness of ECC module was detected, which including 1, 2 and 3 bits errors in single word (not Multiple Bit Upsets, MBUs), through deeply analysis, ECC modules in SRAMs are utilizing (12, 8) Hamming code, and it would lose work when 2 bits upset accumulating in one codeword; Third, the probabilities of failure modes which involving 1, 2 and 3 bits errors, are respectively 39.39%, 37.88% and 22.73% in theoretical calculation, and it has a good match with the experimental testing.

Key words: SEU, SRAM, ECC, Hamming code, Effectiveness, Failure modes