Memory BISR Based on Content Addressable Memory

With increasing defect density,the number of defective cells would be increase．Adding spare rows or columns in memories to replace defective cells is a widely accepted method for yield enhancement．However,existing repair schemes not only have low resource utilization,complex redundancy analysis algorithms,but also greatly depend on the spare structure provided by memory manufactures．Therefore,a repair method using content addressable memory combined with spare rows and columns are proposed in this work．Content addressable memory is not only used to store repair information,but also used as spare words to replace defective words．Meanwhile,spare rows and columns are used to repair row or column address decode defects．A control circuit which controls the access to defective cells is inserted at the output of the address decoder．Advantages of the proposed method are simple implementation,low area overhead,good scalability and high repair rate． Experimental results indicate that the redundancy and content addressable memory area overhead of the proposed repair method is only 20％ of other 2D repair methods to obtain the same repair ratio．