Utilization of SECDED for Soft Error and Variation-Induced Defect Tolerance in Caches

Combination of SECDED with a redundancy technique can effectively tolerate a high variation-induced defect rate in future processes. However, while a defective cell in a block can be repaired by SECDED, the block becomes vul-nerable to soft errors. This paper proposes a technique to deal with the degraded resilience against soft errors. Only clean data can be stored in defective blocks of a cache. This constraint is enforced through selective write-through mechanism. An error occurring in a defective block can be detected and the correct data can be obtained from the lower level caches.