PROGRAM VERIFY METHOD OF FLASH MEMORY DEVICE TO OBTAIN WIDE PASS VOLTAGE WINDOW

摘要

A verifying method of flash memory device is provided to expand the pass voltage window by improving the channel boosting efficiency regardless of the reduction of the pass voltage which is applied to the memory cell. In case the selected memory cell is the program failure, the bit line(BL) connected to the memory string is pre-charged by the power supply voltage(VDD). The fixed voltage(VDD+Vth) is applied to the string selection line(SSL) connected to the string selection transistor(SG1A). The fixed voltage is obtained by adding the threshold voltage of the string selection transistor to the power supply voltage. The ground voltage(VSS) is applied to the word line connected to the memory cell, and the ground selection line(GSL) connected to the ground-selection transistor(SG2A). The selected memory cell is again programmed. At this time, the program voltage is applied to the word line of the selected memory cell. Moreover, the pass voltage is applied to the word line of the memory cell which is unselected.