Patent ID: 6836431
Filing Date: 2004-12-28
Classification: G11C

Abstract:
A method of programming a multi-level flash memory using a sensing circuit that includes a comparator, a reference current supply unit, a sense amplifier driving determining circuit, and a register array, the method comprising:a data storing step of storing data, in each register which is included in each memory cell, corresponding to a level to be programmed; a first program step of, after a first program voltage is applied to word lines, not performing a program to maintain threshold voltages of memory cells each of which register having a first data, at a first level and performing a program to raise threshold voltages of remaining memory cells each of which register not having the first data, to a second level; a second program step of, after a second program voltage is applied to the word lines, not performing a program to maintain threshold voltages of memory cells each of which register having one of the first data or a second data, and performing a program to raise threshold voltages of remaining memory cells each of which not having of the first or second data, to a third level; and a third program step of, after a third program voltage is applied to the word lines, not performing a program to maintain threshold voltages of memory cells each of which register having one of the first data, the second data, and a third data, and performing a program to raise threshold voltages of remaining memory cells not having one of the first data, the second data, and the third data, to a fourth level.