Three-dimensional phase change memory device having a laterally constricted element and method of making the same

Abstract

A phase change memory device includes first conductive rails laterally extending along a first horizontal direction over a substrate, a rectangular array of memory pillar structures overlying top surfaces of the first conductive rails, and second conductive rails laterally extending along a second horizontal direction and overlying top surfaces of the rectangular array of memory pillar structures. Each memory pillar structure includes a vertical stack of structural elements including, from one end to another, a selector-side conductive element, a selector element, a selector-memory conductive element, a phase change memory element, and a memory-side conductive element. At least one structural element within the vertical stack is a laterally constricted structural element having laterally recessed sidewalls relative to sidewalls of a respective immediately vertically underlying structural element.