Three-dimensional memory device with composite charge storage structures and methods for forming the same

Abstract

A memory device includes an alternating stack of insulating layers and electrically conductive layers located over a substrate, and a memory stack structure extending through the alternating stack. The memory stack structure includes a composite charge storage structure, a tunneling dielectric layer, and a vertical semiconductor channel. The composite charge storage structure may include a vertical stack of tubular charge storage material portions including a first charge trapping material located at levels of the electrically conductive layers, and a charge storage layer including a second charge trapping material extending through a plurality of electrically conductive layers of the electrically conductive layers. The first charge trapping material has a higher charge trap density than the second charge trapping material. Alternatively, the composite charge storage material portions may include discrete charge storage elements each containing a silicon nitride portion and a silicon carbide nitride liner.