A FLEXIBLE REDUNDANCY TECHNIQUE FOR HIGH-DENSITY DRAMS

This paper points out the limitations of conventional redundancy techniques and proposes a novel redundancy technique for high-density DRAM's, especially DRAM's using multidivided data-line structures. The proposed technique features a flexible relationship between spare lines and spare decoders. It provides higher usage efficiency of both spare lines and spare decoders, as well as lower probability of unsuccessful repair. With this technique the yield improvement factor of 64-Mb DRAM's and beyond is estimated to be more than twice that with the conventional technique in the early stages of production.