| 摘要 |
A redundancy technique is introduced for a semiconductor memory and, more particularly, a redundancy technique for a dynamic random access memory (DRAM) having a storage capacity of 16 mega bits or more. In such a DRAM, the memory array is divided into memory mats. According to the present redundancy technique, for a semiconductor memory including a memory array which has a plurality of word lines, a plurality of bit lines arranged so that two-level crossings are formed between the word lines and the bit lines, memory cells disposed at desired ones of the two-level crossings, and spare bit lines, there are provided, address comparing circuits each of which storing therein a defective address existing in the memory array and comparing an address to be accessed with the stored defective address, and selection circuitry including logical OR gates for replacing a defective bit line by a spare bit line in accordance with the result of the comparison. Each of the address comparing circuits has stored therein the column address of a defective bit line and a part of the row address indicating the memory mat corresponding to the defective bit line.
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