Three-dimensional memory device including discrete charge storage elements and methods of forming the same

A method of forming a three-dimensional memory device, comprising:

• forming an alternating stack of insulating layers and spacer material layers over a substrate, wherein the spacer material layers are formed as, or are subsequently replaced with, electrically conductive layers;
• forming a memory opening through the alternating stack;
• forming annular lateral recesses at levels of the insulating layers by laterally recessing sidewalls of the insulating layers relative to sidewalls of the spacer material layers around the memory opening;
• forming a vertical stack of discrete metal portions in the annular lateral recesses;
• forming a semiconductor material layer on the vertical stack of the metal portions;
• forming a vertical stack of metal-semiconductor alloy portions by reacting the vertical stack of metal portions with portions of the semiconductor material layer located at levels of the insulating layers;
• removing the vertical stack of metal-semiconductor alloy portions selective to unreacted portions of the semiconductor material layer, wherein unreacted portions of the semiconductor material layer remain at levels of the spacer material layers and comprise a vertical stack of discrete semiconductor material portions;
• and
• forming a tunneling dielectric layer and a vertical semiconductor channel in the memory opening.