The reliability of semiconductor RAM memories with on-chip error-correction coding

The mean lifetimes are studied of semiconductor memories that have been encoded with an on-chip single error-correcting code along each row of memory cells. Specifically, the effects of single-cell soft errors and various hardware failures (single-cell, row, column, row-column, and entire chip) in the presence of soft-error scrubbing are examined. An expression is presented for computing the mean time to failure of such memories in the presence of these types of errors using the Poisson approximation; the expression has been confirmed experimentally to accurately model the mean time to failure of memories protected by single error-correcting codes. These analyses will enable the system designer to accurately assess the improvement in mean time to failure (MTTF) achieved by the use of error-control coding.