Patent ID: 9224483
Filing Date: 2015-12-29
Classification: G11C

Abstract:
1. A method of operating a nonvolatile memory device including a plurality of multi-level memory cells, the plurality of multi-level memory cells including at least one first memory cell, at least one second memory cell and at least one third memory cell, the method comprising: applying a first programming voltage to a selected wordline connected to the plurality of multi-level memory cells; after the first programming voltage is applied to the selected wordline, performing a first two-step operation on the at least one first memory cell connected to the selected wordline, the first two-step operation including performing a first pre-verification operation on the at least one first memory cell corresponding to a first threshold voltage and performing a first verification operation on the at least one first memory cell corresponding to a second threshold voltage greater than the first threshold voltage; after the first programming voltage is applied to the selected wordline, performing a second two-step operation on the at least one second memory cell connected to the selected wordline, the second two-step operation including performing a second pre-verification operation on the at least one second memory cell corresponding to a third threshold voltage greater than the second threshold voltage and performing a second verification operation on the at least one second memory cell corresponding to a fourth threshold voltage greater than the third threshold voltage; applying a second programming voltage to the selected wordline, the second programming voltage being greater than the first programming voltage; and after the second programming voltage is applied to the selected wordline, performing a third one-step operation on the at least one third memory cell connected to the selected wordline, the third one-step operation consisting essentially of performing a third verification operation on the at least one third memory cell corresponding to a fifth threshold voltage greater than the fourth threshold voltage.