Patent ID: 9496038
Filing Date: 2016-11-15
CPC Classification: G11C

Claim Text:
1. A three-dimensional flash memory device which includes a plurality of cell strings arranged in a direction perpendicular to a substrate, the three-dimensional flash memory comprising: a first dummy word line disposed between a ground selection line and a main word line; and a second dummy word line disposed between the main word line and a string selection line, and being asymmetric with respect to the first dummy word line, wherein voltages of different levels are respectively applied to the first and second dummy word lines during a read operation, wherein the first and second dummy word lines are asymmetric in that: (1) the number of word lines assigned to the first dummy word line differs from the number of word lines assigned to the second dummy word line, (2) the distance between the first dummy word line and the ground selection line differs from the distance between the second dummy word line and the string selection line, or (3) the width of the first dummy word line differs from the width of the second dummy word line.