METHOD FOR MAKING MEMORY DEVICE FAULT TOLERANT USING VARIABLE DOMAIN REDUNDANT REPLACEMENT CONSTITUTION

PROBLEM TO BE SOLVED: To make a memory of arbitrary size fault tolerant by enabling using an effective replacement domain out of at least two variable domains in which one part is overlapped. SOLUTION: Capacitive electric charges from a capacitor 25 on a bit line BL is amplified by a sense amplifier 28, selected as bit information by a corresponding column address, and sent to a data output circuit. A 256K redundant block including RWL of 128 lines is used for each 16Mb primary array 19 instead of a redundant word line RWL in each 1Mb block. A redundant block 22 includes RU 0-63 of 64 pieces. One 1MB domain A is related to each of RU 0-15, RU 16-31 are used with 4Mb domain B, residual R32-R63 are related to whole replacement domain C. The most effective and efficient domain selection can be performed in an obstacle type so that domain A-C are overlapped one another, at unit restorable possibility is improved at the time of hard obstacle and holding obstacle.