On the reconfiguration of memory arrays containing clustered faults

Reconfiguration of memory arrays using spare rows and spare columns, a useful technique for yield enhancement of memories, is considered under a compound probabilistic model that shows clustering of faults. It is shown that the total number of faulty cells that can be tolerated when clustering occurs is larger than when faults are independent. It is shown that an optimal solution to the reconfiguration problem can be found in polynomial time for a special case of the clustering model. Efficient approximation algorithms are given for the situation in which faults appear in clusters only and the situation in which faults occur both in clusters and singly. It is shown through simulation that the computation time required by this algorithm to repair large arrays containing a significant number of clustered faults is small.<>