Three-dimensional memory device containing horizontal and vertical word line interconnections and methods of forming the same

Abstract

A method of forming a three-dimensional memory device includes forming a vertically alternating sequence of insulating layers and spacer material layers over a substrate, such that the spacer material layers are formed as, or are subsequently replaced with, electrically conductive layers, iteratively performing a first set of non-offset layer patterning processing steps at least twice to form a first part of a terrace region including a set of stepped surfaces which extend in a first horizontal direction, and performing a second set of offset layer patterning processing steps to form a second part of the terrace region and to form a stepped vertical cross-sectional profile for patterned surfaces of the vertically alternating sequence along a second horizontal direction which is perpendicular to the first horizontal direction.