NONVOLATILE MEMORY (NVM) USING ADAPTIVE WRITING OPERATION

PROBLEM TO BE SOLVED: To provide a nonvolatile memory (NVM) using an adaptive writing operation.SOLUTION: A method for executing a writing operation of a memory cell of a memory array includes: a step for applying a plurality of first pulses of a writing operation to the memory cell in accordance with a first prescribed ramp speed, the plurality of first pulses being the prescribed number of pulses; a step for executing comparison of a threshold voltage of a subset of the memory cell with a provisional verification voltage; and a step for continuing a writing operation by applying a plurality of second pulses to the memory cell in accordance with a second prescribed ramp speed having an increased ramp speed in comparison with the first prescribed ramp speed in a case of failing in comparing the threshold voltage of one of subsets of the memory cell with provisional verification voltage.