Marking pattern in forming staircase structure of three-dimensional memory device

Abstract

Embodiments of a marking pattern in forming the staircase structure of a three-dimensional (3D) memory device are provided. In an example, a semiconductor device includes a stack structure having a plurality of insulating layers and a plurality of conductor layers arranged alternatingly over a substrate along a vertical direction. In some embodiments, the semiconductor device also includes a marking pattern having a plurality of interleaved layers of different materials over the substrate and neighboring the stack structure. The marking pattern includes a central marking structure located in a marking area, the central marking structure dividing the marking area into a first marking sub-area farther from the stack structure and a second marking sub-area closer to the stack structure, a first pattern density of the first marking sub-area being higher than or equal to a second pattern density of the second marking sub-area.