NON-VOLATILE SEMICONDUCTOR MEMORY DEVICE USING WEAK CELLS AS READING IDENTIFIER

摘要

A nonvolatile semiconductor memory device using weak cells as a reading identifier is provided to prevent a read error for a region where the read operation is mainly performed in a memory cell region of a flash EEPROM(Electrically Erasable Programmable Read-Only Memory). According to an EEPROM(Electrically Erasable Programmable Read-Only Memory) type nonvolatile semiconductor memory, a memory cell array comprises normal memory cells and flag memory cells(4). The normal memory cells are constituted with MOS transistors having a control gate(50) and a floating gate(40) to store data. The flag memory cells are fabricated to have weak characteristics rather than the normal memory cells for applied electrical stress, by being fabricated to have relatively larger coupling ratio than coupling ratio of the normal memory cells, in order to monitor variation symptom for data retention characteristics of the normal memory cells.