Three-dimensional memory device including multi-tier moat isolation structures and methods of making the same

Abstract

A method of forming a three-dimensional memory device includes forming a first-tier alternating stack of first insulating layers and first sacrificial material layers, forming first-tier memory openings, first-tier support openings, and first-tier moat trenches through the first alternating stack using a same etching step, forming a first dielectric moat structure in the first moat tier-trenches and first support pillar structures in the first-tier support openings during a same deposition step, forming memory stack structures in the first-tier memory openings, forming backside trenches through the first-tier alternating stack after forming the first dielectric moat structure, replacing portions of the first sacrificial material layers with first electrically conductive layers through the backside trenches, and forming at least one through-memory-level interconnection via structure through the first vertically alternating sequence of first insulating plates and first dielectric material plates surrounded by the first dielectric moat structure.