Mechanisms for built-in self repair of memory devices using failed bit maps and obvious repairs

摘要

Failure bit map (FBM) data and a built-in-self-test-repair (BISTR) module enable collecting and analyzing FBM data of an entire memory to identify the best repairing method (or mechanism) to make repairs. As a result, the repair method is better and more efficient than algorithms (or methods) known to the inventors, which only utilize partial (or incomplete) failure data. At the same time, the compressed data structures used for the FBMs keep the resources used to capture the FBM data and to repair the failed cells relatively limited.

主权项

1. A method of self-testing and self-repairing a random access memory (RAM), comprising:
collecting failure data of the RAM with redundant rows and columns, wherein the failure data of all failed cells of the RAM are stored in two failure bit map (FBM) data structures, and wherein the RAM is divided into a number of segments; analyzing the failure data in the two FBM data structure to determine repair methods; and repairing failed cells of the RAM by using the redundant rows and columns until either all failed cells are repaired or the redundant rows and columns are all used.