Phase change memory device, memory system, and programming method using variable verification pulses

摘要

In a method of programming a phase change memory device, write data is programmed in a plurality of phase change memory cells by applying write pulses to each of the plurality of phase change memory cells. Whether each of the phase change memory cells is programmed is verified by applying verification pulses to each of the phase-change memory cells. A number of applications for the verification pulses and the intervals between respective applications of the verification pulses are varied in accordance with a verification result for each of the phase-change memory cells.