1. Field of the Invention
The present invention relates to a semiconductor memory device. For example, the present invention relates to a semiconductor memory device including memory cells each having a charge accumulation layer and a control gate.
2. Description of the Related Art
Electrically erasable and programmable read-only memories (EEPROMs) are known as nonvolatile semiconductor memories that allow data to be electrically rewritten. For data reading in an EEPROM, a row decoder selects one of word lines and transfers a voltage to the selected word line. For example, Jpn. Pat. Appln. KOKAI Publication Nos. 2006-114139 and 2003-086720 have proposed row decoder configurations.
NAND flash memories are known as EEPROMs that allow an increase in capacity and in integration degree. For data reading in a NAND flash memory, a voltage that enables memory cells to be turned on is transferred to unselected word lines regardless of data held in the memory cells.
Then, if a high voltage needs to be applied to the unselected word lines, an increased load is imposed on a voltage generator that generates this voltage. Furthermore, the voltage generator tends to have a large circuit area.