| 摘要 |
PURPOSE: A semiconductor memory device having a redundant low substitution structure is provided to enhance access time(access speed) without increasing a layout area, and has a redundant low substitution scheme of a sub word line structure. CONSTITUTION: A semiconductor memory device includes a sub word line structure(SWD), and includes a main word line decoder driver(160), address program circuit(220) and a redundant main word line decoder driver(260). When low address bit signals for indicating a main word lint are input, the main word line decoder driver drives a main word line corresponding to the low address bit signals without relation to a low redundancy. If the low address bit signals are identical with defective low address bit signals, the address program circuit generates a redundancy low selection signal. Accordingly, the activated main word line is inactivated, and a redundant main word line is activated. According to a redundant low substitution scheme, the access time can be reduced without increasing a layout area.
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