Patent ID: 7535747
Filing Date: 2009-05-19
Classification: G11C

Abstract:
1. A method of performing a program operation in a phase change random access memory (PRAM) device comprising a plurality of phase change memory cells divided into a plurality of cell groups, the method comprising: reading verification data from selected memory cells among the plurality of phase change memory cells; comparing the verification data with program data to be programmed in the selected memory cells and identifying “n” (“n” is a natural number greater than 2) failed memory cells among the selected memory cells based on the comparison; and programming the “n” failed memory cells with a subset of the program data using “m” (“m” is a natural number greater than 2) divisional program operations corresponding to “m” failed cell groups, wherein each of the “m” failed cell groups includes at least one of the “n” failed memory cells; wherein the “m” divisional program operations are performed in “m” consecutive and substantially evenly spaced timeslots of a current program loop.