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 over a substrate, wherein the first material comprises a conductive or semiconductor control gate material and wherein the second material comprises an insulating material;
• etching the stack to form at least one opening in the stack;
• selectively etching the first material to form first recesses in the first material;
• forming a blocking dielectric in the first recesses;
• forming a plurality of discrete charge storage segments separated from each other in the first recesses over the blocking dielectric;
• forming a tunnel dielectric over a side wall of the discrete charge storage segments exposed in the at least one opening;
• and
• forming a semiconductor channel in the at least one opening;
• wherein the step of forming a semiconductor channel in the at least one opening comprises:
• forming an amorphous semiconductor layer in the at least one opening and over the stack of the alternating layers;
• forming a nucleation promoter layer over the amorphous semiconductor layer;
• recrystallizing the amorphous semiconductor to form polycrystalline semiconductor layer;
• and
• removing the nucleation promoter layer and an upper portion of the polycrystalline semiconductor layer using top surface of the stack of alternating layers as a stop.