Through-array conductive via structures for a three-dimensional memory device and methods of making the same

Abstract

An alternating stack of insulating layers and dielectric spacer layers is formed over a semiconductor substrate. Memory stack structures are formed through the alternating stack. Backside trenches, a moat trench, and a contact opening are formed through the alternating stack, and are subsequently filled with sacrificial backside trench fill material structures, a sacrificial moat trench fill structure, and a sacrificial contact opening fill structure, respectively. The sacrificial moat trench fill structure is replaced with tubular dielectric wall structure. Portions of the dielectric spacer layers located outside the tubular dielectric wall structure are replaced with electrically conductive layers. The sacrificial backside trench fill material structures are replaced with backside trench fill structures. The sacrificial contact opening fill structure is replaced with a conductive via structure. Concurrent formation of the backside trenches, the moat trench, and the contact opening reduces processing steps and cost.