Memory device

Abstract

Provided is a memory device including a stack structure. The stack structure is in the memory array region of a substrate. The stack structure comprises a plurality of first insulating layers and a plurality of conductive layers stacked alternately on each other. A first staircase structure and a second staircase structure are located in a first staircase region and a second staircase region of the substrate respectively. The second staircase structure has steps descending from an upper layer proximal to the memory array region to a lower layer distal to the memory array region. Block slits and zone slit are disposed over the substrate in the second staircase region. The block slits divide the stack structure, the first staircase structure and the second staircase structure into memory blocks. The zone slits divide one of the memory blocks into a plurality of zones separately within the memory blocks.