Semiconductor memory device and defect repair method for semiconductor memory device

摘要

In a semiconductor memory device, rows of normal cell array blocks are selected by 13-bit row addresses corresponding to a refresh period of 8 kc respectively, so that the selected rows are successively refreshed. A spare memory array block is selected by a 12-bit row address for 4 kc excluding the most significant row address in the 13-bit row addresses corresponding to the row addresses of 8 kc. Thus, the semiconductor memory device can effectively carry out defect repair without reducing the yield also when a spare memory cell is inferior in data retention ability.