Three-dimensional inverse flat nand memory device containing partially discrete charge storage elements and methods of making the same

A three-dimensional memory device comprising:

• alternating stacks of insulating strips and electrically conductive strips located over a substrate and laterally spaced apart among one another by line trenches, wherein the line trenches having sidewalls that laterally extend along a first horizontal direction and are spaced apart along a second horizontal direction;
• and
• line trench fill structures located in the line trenches, wherein each line trench fill structure comprises a laterally undulating dielectric rail having a laterally undulating width along the second horizontal direction and extending along the first horizontal direction and a row of memory stack structures located at a plurality of neck regions of the laterally undulating dielectric rail,
• wherein each memory stack structure comprises a vertical semiconductor channel, a blocking dielectric contacting an outer sidewall of the vertical semiconductor channel, and a charge storage layer contacting an outer sidewall of the blocking dielectric, vertically extending continuously through each level of the electrically conductive strips, and having a vertically undulating lateral thickness.