Three-dimensional memory device with staircase etch stop structures and methods for forming the same

A method of forming a three-dimensional memory device, comprising:

• forming an alternating stack of insulating layers and sacrificial material layers over a substrate, wherein the alternating stack comprises at least one memory array region in which each layer of the alternating stack is present and a staircase region comprising stepped surfaces of the alternating stack;
• forming an insulating liner over the stepped surfaces of the alternating stack;
• forming discrete openings through the insulating liner;
• forming a plurality of discrete dielectric plates over the insulating liner, wherein the plurality of discrete dielectric plates are spaced apart from each other and fill a respective discrete opening through the insulating liner;
• forming a dielectric material portion over the plurality of discrete dielectric plates;
• forming memory openings through the alternating stack in the memory array region;
• forming memory opening fill structures in the memory openings, wherein each of the memory opening fill structures comprises a respective vertical stack of memory elements;
• and
• replacing the sacrificial material layers and the plurality of discrete dielectric plates with electrically conductive layers, wherein each of the electrically conductive layers is formed within a volume including a volume of a respective sacrificial material layer and a volume of a respective discrete dielectric plate of the plurality of discrete dielectric plates.