Three-dimensional nand device containing support pedestal structures for a buried source line and method of making the same

Abstract

A three-dimensional memory device includes an alternating stack of electrically conductive layers and insulating layers located over a substrate, an array of memory stack structures. An alternating sequence of support pedestal structures and conductive rail structures extending along a same horizontal direction are provided between the substrate and the alternating stack. Each memory stack structure straddles a vertical interface between a conductive rail structure and a support pedestal structure. A semiconductor channel in each memory stack structure contacts a respective conductive rail structure, and is electrically isolated from an adjacent support pedestal structure by a portion of a memory film. The conductive rail structures can function as source regions of memory device.