Patent ID: 7990771

Claim:
A program method of a flash memory device including a plurality of MLCs that share word lines and bit lines, the program method comprising the steps of: selecting one of the word lines; first programming first MLCs that are connected to the selected word line and that have a threshold voltage in a first voltage range by applying a first program voltage and a first verify voltage, wherein the first program voltage gradually rises from a start program voltage at the ratio of a first step voltage to the selected word line; and second programming the first MLCs connected to the selected word line by applying a second program voltage and a second verify voltage, wherein the second program voltage gradually rises from the first program voltage, which has finally risen in the first program step, at the ratio of a second step voltage; wherein a highest voltage of the first MLCs is lower than a lowest voltage of second MLCs that are connected to the selected word line and that have a threshold voltage in a second voltage range.