Three-dimensional memory device including discrete memory elements and method of making the same

A memory device, comprising:

• an alternating stack of insulating layers and electrically conductive layers located over a substrate;
• and
• a memory stack structure extending through each layer in the alternating stack, wherein:
• the memory stack structure comprises a memory film and a vertical semiconductor channel;
• the memory film comprises a tunneling dielectric layer and a vertical stack of discrete memory-level structures that are vertically spaced from each other without direct contact between them;
• each of the discrete memory-level structures comprises a lateral stack including, from one side to another, a charge storage material portion, a silicon oxide blocking dielectric portion, and a dielectric metal oxide blocking dielectric portion;
• and
• an interface between the charge storage material portion and the silicon oxide blocking dielectric portion within each of the discrete memory-level structures comprises a respective vertical segment and a respective pair of horizontal segments that extend from the respective vertical segment toward the vertical semiconductor channel.

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

• forming a vertical stack of material layers that includes a vertically alternating sequence of first sacrificial material layers and second sacrificial material layers over a substrate;
• forming a memory opening vertically extending through the vertical stack;
• forming a memory opening fill structure in the memory opening, the memory opening fill structure comprising an in-process memory film and a vertical semiconductor channel, wherein the in-process memory film comprises a layer stack that includes a dielectric metal oxide blocking dielectric layer, a silicon oxide blocking dielectric layer, a charge storage layer, and a tunneling dielectric layer;
• forming first lateral recesses by removing the first sacrificial material layers selective to the second sacrificial material layers around the memory opening fill structure;
• converting the in-process memory film into a memory film including a vertical stack of discrete memory-level structures that are vertically spaced from each other without direct contact between them by performing an etch process that etches portions of the in-process memory film around the first lateral recesses, wherein each of the discrete memory-level structures comprises a lateral stack including, from one side to another, a charge storage material portion, a silicon oxide blocking dielectric portion that is a patterned portion of the silicon oxide blocking dielectric layer, and a dielectric metal oxide blocking dielectric portion that is a patterned portion of the dielectric metal oxide blocking dielectric layer;
• and
• replacing the second sacrificial material layers with electrically conducive layers.