US 11,749,600 B2
Three-dimensional memory device with hybrid staircase structure and methods of forming the same
Akihiro Tobioka, Yokkaichi (JP)
Assigned to SANDISK TECHNOLOGIES LLC, Addison, TX (US)
Filed by SANDISK TECHNOLOGIES LLC, Addison, TX (US)
Filed on Apr. 7, 2021, as Appl. No. 17/224,370.
Prior Publication US 2022/0328403 A1, Oct. 13, 2022
Int. Cl. H01L 23/528 (2006.01); H01L 23/522 (2006.01); H01L 21/768 (2006.01); H10B 41/27 (2023.01); H10B 43/27 (2023.01)
CPC H01L 23/5283 (2013.01) [H01L 21/76816 (2013.01); H01L 21/76877 (2013.01); H01L 23/5226 (2013.01); H10B 41/27 (2023.02); H10B 43/27 (2023.02)] 13 Claims
OG exemplary drawing
 
1. A three-dimensional memory device, comprising:
first alternating stacks of first insulating layers and first electrically conductive layers located over a substrate, wherein the first alternating stacks laterally extend along a first horizontal direction and are laterally spaced apart along a second horizontal direction that is perpendicular to the first horizontal direction by line trenches, and wherein each of the first alternating stacks comprises a respective first staircase region in which a lateral extent of the first electrically conductive layers along the first horizontal direction decreases with an increasing vertical distance from the substrate;
trench fill structures located between and contacting a respective neighboring pair of the first alternating stacks and filling a respective one of the line trenches;
arrays of memory stack structures vertically extending through a respective one of the first alternating stacks, wherein each of the memory stack structures comprises a respective vertical stack of memory elements located at levels of the first electrically conductive layers;
first retro-stepped dielectric material portions overlying a first staircase region of a respective one of the first alternating stacks, wherein one of the first retro-stepped dielectric material portions has a vertical cross-sectional profile within a vertical plane that is perpendicular to the first horizontal direction in which:
a first boundary of the one of the first retro-stepped dielectric material portions continuously extends from a first horizontal plane including a bottommost surface of the one of first retro-stepped dielectric material portions to a second horizontal plane including topmost surfaces of the first alternating stacks; and
a second boundary of the one of the first retro-stepped dielectric material portions continuously extends from the first horizontal plane to a first point on a sidewall of a respective one of the trench fill structures, the first point being located at a height located between the first horizontal plane and the second horizontal plane.