Patent ID: 7602648

Claim:
Method of determining an ending bias voltage in incremental step pulse comprising: applying a first program voltage to selected memory cells to measure a first threshold voltage of the memory cells; applying a second program voltage to the memory cells to measure a second threshold voltage of the memory cells, the second program voltage being determined by adding the first program voltage to a difference between a lowest threshold voltage among the first threshold voltage and a middle threshold voltage among the first threshold voltage; repeatedly applying a new program voltage to the memory cells to measure a new threshold voltage of the memory cells until the new threshold voltage of the memory cells is higher than a verify voltage, the new program voltage being increased by adding the second program voltage to a difference between a lowest threshold voltage among a threshold voltage which is measured in previous step and a middle threshold voltage among the first threshold voltage; and defining the new program voltage when a lowest threshold voltage among the new threshold voltage of the memory cells is higher than the verify voltage as the ending bias voltage.