Three-dimensional memory device including contact via structures for multi-level stepped surfaces and methods for forming the same

Abstract

A three-dimensional memory device includes an alternating stack of insulating layers and electrically conductive layers containing a terrace region having a plurality of steps, memory stack structures extending through the alternating stack, a retro-stepped dielectric material portion overlying the terrace region, first laterally isolated contact structures including a respective first contact via structure and a respective first dielectric spacer, and second laterally isolated contact structures including a respective second contact via structure and a respective second dielectric spacer. The respective first contact via structure contacts a top surface of a respective first electrically conductive layer in the respective step of the plurality of steps. The respective second contact via structure extends through the respective first electrically conductive layer in the respective step and contacts a top surface of a respective second electrically conductive layer which underlies the first electrically conductive layer in the respective step.