Uniform thickness blocking dielectric portions in a three-dimensional memory structure

Abstract

A memory opening is formed through a stack of alternating layers comprising first material layers and second material layers. Sidewall surfaces of the second material layers are laterally recessed with respect to sidewall surfaces of the first material layers within the memory opening. Annular semiconductor material portions can be formed by depositing a semiconductor material from the sidewall surfaces of the second material layers while the semiconductor material does not grow from surfaces of the first material layers. Optionally, an inner portion of each annular semiconductor material portion can be converted into an annular dielectric material portion that includes a dielectric material. A memory film is formed in the memory opening. During removal of the second material layers, the annular semiconductor material portions can be employed as an etch stop material, thereby minimizing collateral etching of the memory film or annular dielectric material portions.

Dependencies are inferred from the claim text.