Patent ID: 7567459
Filing Date: 2009-07-28
Classification: G11C

Abstract:
1. A method of measuring a channel boosting voltage in a NAND flash memory device, the method comprising: applying a pass voltage to unselected memory cells, and applying a first pass voltage to a selected memory cell in an erase state; measuring a first threshold voltage of the selected memory cell when a level of the first pass voltage applied to the selected memory cell is changed; applying a program voltage to the selected memory cell, and applying a second pass voltage to the unselected memory cells; measuring a second threshold voltage of the selected memory cell when a level of the second pass voltage applied to the unselected memory cells is changed; detecting a level of the second threshold voltage that has been measured when the second pass voltage having the same level as a pass bias voltage applied in a program operation is applied to the unselected memory cells, and detecting a level of the first pass voltage that has been applied to the selected memory cell when the first threshold voltage is identical to the second threshold voltage; and measuring the channel boosting voltage by using the level of the detected first pass voltage and a level of the program voltage.