Ultrahigh density vertical NAND memory device

A monolithic three dimensional NAND string, comprising:

• a semiconductor channel located over a substrate, the semiconductor channel having a U-shaped side cross section, wherein two wing portions of the U-shaped semiconductor channel which extend substantially perpendicular to a major surface of the substrate are connected by a connecting portion which extends substantially parallel to the major surface of the substrate;
• an insulating fill located over the connecting portion and separating two wing portions of the U-shaped semiconductor channel;
• a plurality control gate electrodes having a strip shape extending substantially parallel to the major surface of the substrate, wherein the plurality of control gate electrodes comprise at least a first control gate electrode located in a first device level and a second control gate electrode located in a second device level located over the substrate and below the first device level;
• a plurality of blocking dielectric segments, wherein each of the plurality of blocking dielectric segments is located in contact with a respective one of the plurality of control gate electrodes;
• a plurality of discrete charge storage segments;
• and
• a tunneling dielectric located between the plurality of discrete charge storage segments and the semiconductor channel.