Patent ID: 9190151
Filing Date: 2015-11-17
Classification: G11C

Abstract:
1. A method of performing a read operation in a nonvolatile memory comprising multiple cell strings each comprising multiple memory cells stacked in a direction perpendicular to a substrate, a ground selection transistor disposed between the memory cells and the substrate, and a string selection transistor disposed between the memory cells and a bitline, the method comprising: during a first interval: applying a first turn-on voltage to string selection lines connected to string selection transistors of a first group of cell strings among the multiple cell strings, and to a first ground selection line connected in common to ground selection transistors of the first group of cell strings; and applying a second turn-on voltage to string selection lines connected to string selection transistors of a second group of cell strings among the multiple cell strings, and to a second ground selection line connected in common to ground selection transistors of the second group of cell strings; during a second interval following the first interval: applying the first turn-on voltage to a string selection line of a selected cell string among the first group of cell strings, and to the first ground selection line; and applying a turn-off voltage to string selection lines of unselected cell strings among the first group of cell strings, to string selection lines of cell strings in the second group of cell strings, and to the second ground selection line; and during both the first and second intervals: applying a first read voltage to a selected wordline among wordlines connected to memory cells of the first group of cell strings and the second group of cell strings; and applying a second read voltage to unselected wordlines among the wordlines connected to memory cells of the first group of cell strings and the second group of cell strings of the wordlines.