Ultrahigh density vertical NAND memory device and method of making thereof

A method of making a monolithic three dimensional NAND string, comprising:

• forming a stack of alternating layers of a first material and a second material different from the first material over a substrate;
• etching the stack to form at least one opening in the stack;
• forming a discrete charge storage material layer on a sidewall of the at least one opening;
• forming a tunnel dielectric layer on the discrete charge storage material layer in the at least one opening;
• forming a semiconductor channel material on the tunnel dielectric layer in the at least one opening;
• selectively removing the second material layers without removing the first material layers;
• etching the discrete charge storage material layer using the first material layers as a mask to form a plurality of separate discrete charge storage segments;
• depositing an insulating material between the first material layers to form alternating layers of insulating material layers and the first material layers;
• selectively removing the first material layers to expose side wall of the discrete charge storage segments;
• forming a blocking dielectric on the side wall of the discrete charge storage segments exposed between the insulating material layers;
• and
• forming control gates on the blocking dielectric between the insulating material layers.