| 摘要 |
PROBLEM TO BE SOLVED: To provide a memory cell for defect relief capable of being composed of redundant cells of the less number even when an ECC(error detecting/ correcting circuit) is used. SOLUTION: When an ECC is used in a multilevel memory, the least significant bit data (8 bits) in each cell includes, in redundant memory cells (4 bits), information indicating whether a defect exists or not as well as positional information of the defect, while more significant bit data (the bit data other than the least significant bit data) (8 bits) include, in a redundant memory cell (1 bit), only information indicating whether a defect exists or not. Since the more significant redundant memory cells only require 1 bit, the redundant memory cells of only 3 bits are required by storing, in the more significant redundant memory cells, information indicating whether a defect exists or not as well as positional information of the defect with respect to the least significant bit data. |
