PROGRAM METHOD OF FLASH MEMORY CAPABLE OF COMPENSATING REDUCTION OF READ MARGIN BETWEEN STATES DUE TO HOT TEMPERATURE STRESS

摘要

A program method of a flash memory for compensating reduction of a read margin due to high temperature stress is provided to secure the read margin between states in spite of the increase of threshold voltage due to electric field coupling/F-poly coupling and the decrease of threshold voltage due to high temperature stress, by performing a second program operation after a first program operation. A flash memory device comprises first and second bit lines, which are connected to plural memory cells for storing multi-bit data indicating one of plural states. The memory cells connected to a selected row and the second bit lines are programmed by multi-bit data(S120). The selected row is compared with the last row(S130). A re-programming process is performed to re-program the programmed memory cells connected to the last row and the first bit lines in order to increase a read margin between adjacent states, which is reduced due to high temperature stress, when the selected row is determined as the last row(S140~S160).