Patent ID: 7242605

Claim:
A method of maintaining a resistance of a phase-change material in a program operation within a constant resistance range, the method comprising; providing data to a first phase-change memory cell; first determining whether data stored in the first phase-change memory cell and the data provided to the first phase-change memory cell are identical; if the data stored in the first phase-change memory cell and the data provided to the first phase-change memory cell are not identical, providing a complementary write current to the first phase-change memory cell that increases based on a number of times it is provided to the first phase-change memory cell and second determining whether the data stored in the first phase-change memory cell and the data provided to the first phase-change memory cell are identical; and providing data to a second phase-change memory cell if the data stored in the first phase-change memory cell and the data provided to the first phase-change memory cell are identical.