Three-dimensional memory device with silicided word lines, air gap layers and discrete charge storage elements, and method of making thereof

摘要

A vertically alternating sequence of silicon-containing semiconductor layers and sacrificial material layers is formed over a substrate. Memory stack structures are formed through the vertically alternating sequence. After formation of backside trenches, backside recesses are formed by removing the sacrificial material layers employing an isotropic etchant introduced through the backside trenches. Composite electrically conductive layers are formed by reacting a metal layer with surface portions of silicon-containing semiconductor layers. A dielectric material can be anisotropically deposited to form a continuous material portion that includes vertically-extending dielectric material portions formed in the backside trenches and cavity-containing layers formed in the backside recesses. The composite electrically conductive layers include word lines, which are vertically spaced by cavity-containing layers. Each memory film can include a charge storage layer that is divided into a plurality of discrete charge storage material portions.