Non-volatile semiconductor memory device with verify mode for verifying data written to memory cells

摘要

A non-volatile semiconductor memory device includes a flip- flop circuit for holding write data in one of first and second states. A bit line is connected to the flip-flop circuit via a switching element, and a transistor charges the bit line. A non-volatile memory cell, connected to the bit line and having a MOS transistor structure, stores data when a threshold thereof is set in one of first and second threshold ranges, wherein at the time of a write mode the threshold of the memory cell is shifted from the first threshold range towards the second threshold range while the flip-flop circuit remains in the first state and the shift of the threshold is not effected while the flip-flop circuit remains in the second state, and at the time of a verify mode following the write mode the bit line is kept at a charge potential by the charging transistor while the threshold remains in the second threshold range. A data setting circuit for connects one of first and second signal nodes of the flip- flop circuit to a predetermined potential when the bit line is at the charge potential in the verify mode, thereby setting the flip-flop circuit in the second state irrespective of the state prior to the verify mode.