Three-dimensional memory device with self-aligned etch stop rings for a source contact layer and method of making the same

Abstract

A memory device includes a lower source-level semiconductor layer, a source contact layer, an upper source-level semiconductor layer, and an alternating stack of insulating layers and electrically conductive layers, and a memory opening fill structure vertically extending through the alternating stack and down to an upper portion of the lower source-level semiconductor layer. The memory opening fill structure includes a vertical semiconductor channel, a memory film laterally surrounding the vertical semiconductor channel, and an annular semiconductor cap contacting a bottom surface of the memory film and contacting a top surface segment of the source contact layer. The annular semiconductor cap may be employed as an etch stop structure during a manufacturing process.