US 2026/0313893 A1Published application

Three-dimensional memory device with overlapped staircases and methods for forming the same

AssigneeSanDisk Technologies LLC

InventorsRuogu Matthew ZHU, Koichi MATSUNO, Jixin YU, Johann ALSMEIER

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Abstract

A device structure includes a first alternating stack of first insulating layers and first electrically conductive layers containing a first staircase region extending along a first horizontal direction, a second alternating stack of second insulating layers and second electrically conductive layers located over or under the first alternating stack, the second alternating stack containing a pair of second staircase regions that are laterally separated from each other along a second horizontal direction and extending along the first horizontal direction, first electrically conductive contacts contacting the first electrically conductive layers in the first staircase region, and second electrically conductive contacts contacting the second electrically conductive layers in the second staircase regions. The first staircase region laterally overlaps the pair of second staircase regions along the first horizontal direction, and the first staircase region is laterally offset from the pair of second staircase regions along the second horizontal direction.

Claims20

Dependent claims

A device structure, comprising:

a first alternating stack of first insulating layers and first electrically conductive layers comprising a first staircase region comprising a first row of stepped surfaces extending along a first horizontal direction and comprising first horizontal surface segments separated by first vertical surface segments;
a second alternating stack of second insulating layers and second electrically conductive layers located over or under the first alternating stack, the second alternating stack comprising a pair of second staircase regions that are laterally separated from each other along a second horizontal direction perpendicular to the first horizontal direction by a bridge region, wherein each of the second staircase regions comprise a second row of stepped surfaces extending along the first horizontal direction and comprising second horizontal surface segments separated by second vertical surface segments;
first electrically conductive contacts contacting the first electrically conductive layers in the first staircase region;
and
second electrically conductive contacts contacting the second electrically conductive layers in the second staircase regions,
wherein:
the first staircase region laterally overlaps the pair of second staircase regions along the first horizontal direction;
the first staircase region is laterally offset from the pair of second staircase regions along the second horizontal direction;
and
the first staircase region is located above or below the bridge region of the second alternating stack.

7 more elements

A method of forming a device structure, comprising:

forming a first-tier structure including a first-tier alternating stack of first-tier insulating layers and first-tier sacrificial material layers embedding a first-tier retro-stepped dielectric material portion;
forming a second-tier structure including a second-tier alternating stack of second-tier insulating layers and second-tier sacrificial material layers embedding a second-tier retro-stepped dielectric material portion;
forming a first sacrificial through-via structure through the second-tier alternating stack and through the first-tier retro-stepped dielectric material portion and through a subset of the first-tier sacrificial material layers;
forming a second sacrificial through-via structure through the first-tier alternating stack and through the second-tier retro-stepped dielectric material portion and through a subset of the second-tier sacrificial material layers;
replacing the first-tier sacrificial material layers and the second-tier sacrificial material layers with first-tier electrically conductive layers and second-tier electrically conductive layers, respectively;
and
replacing the first sacrificial through-via structure and the second sacrificial through-via structure with a first through-via contact structure and a second through-via contact structure, respectively, wherein the first through-via contact structure is electrically connected to a first electrically conductive layer that replaces a topmost first-tier sacrificial material layer within the subset of the first-tier sacrificial material layers, and the second through-via contact structure is electrically connected to a second electrically conductive layer that replaces a topmost second-tier sacrificial material layer within the subset of the second-tier sacrificial material layers.

4 more elements

Dependencies are inferred from the claim text.