Efficient BISR Techniques for Word-Oriented Embedded Memories with Hierarchical Redundancy

In this paper, BISR (built-in self-repair) techniques with hierarchical redundancy architecture are proposed for word-oriented embedded memories. Our BISR circuit consists of a built-in self-test (BIST) module and a built-in redundancy-analysis (BIRA) module. Spare words, spare rows, and spare columns are added into the memory cores as redundancy. However, the spare rows and spare columns are virtually divided into spare row blocks and spare column group blocks. The address reconfiguration is performed at row block or column group block level instead of the traditional row or column level. An extended essential spare pivoting (EESP) algorithm is proposed for redundancy analysis based on the proposed redundancy organization. A practical 16Ktimes32 SRAM with BISR circuitry is designed and implemented. Experimental results show that we can obtain a higher repair rate with negligible area overhead (2.56%) of the BISR circuit for a 1024Ktimes2048-bit SRAM chip