Three-dimensional memory device and method of making thereof using double pitch word line formation
A three-dimensional memory device includes a vertical repetition of multiple instances of a unit layer stack, memory openings vertically extending through the vertical repetition, and memory opening fill structures located within the memory openings. Each of the memory opening fill structures contains a respective vertical stack of memory elements. The unit layer stack includes, from bottom to top or from top to bottom, a cavity-free insulating layer that is free of any cavity therein, a first-type electrically conductive layer, a cavity-containing insulating layer including an encapsulated cavity therein, and a second-type electrically conductive layer.
1 . A three-dimensional memory device, comprising:
a vertical repetition of multiple instances of a unit layer stack, wherein the unit layer stack comprises, from bottom to top or from top to bottom, a cavity-free insulating layer that is free of any cavity therein, a first-type electrically conductive layer, a cavity-containing insulating layer including an encapsulated cavity therein, and a second-type electrically conductive layer;
a retro-stepped dielectric material portion overlying, and contacting, stepped surface of the vertical repetition;
memory openings vertically extending through the vertical repetition; and
memory opening fill structures located within the memory openings,
wherein:
each of the memory opening fill structures comprises a respective vertical stack of memory elements;
the first-type electrically conductive layers, the second-type electrically conductive layers, and the cavity-free insulating layers are free of lateral recesses and contact the retro-stepped dielectric material portion; and
the cavity-containing insulating layers comprises lateral recesses into which a dielectric material of the retro-stepped dielectric material portion laterally protrude.
2 . The three-dimensional memory device of claim 1 , wherein each of the encapsulated cavities is laterally spaced from the memory opening fill structures by tubular portions of a respective one of the cavity-containing insulating layers.
3 . The three-dimensional memory device of claim 1 , wherein each of the encapsulated cavities comprises an air gap which is free of any solid phase material.
4 . The three-dimensional memory device of claim 1 , further comprising an insulating material portion comprising a same dielectric material as the cavity-containing insulating layers and connected to each of the cavity-containing insulating layers.
5 . The three-dimensional memory device of claim 4 , wherein the insulating material portion comprises an insulating spacer laterally surrounding a backside contact via structure that vertically extends through each layer within the vertical repetition.
6 . The three-dimensional memory device of claim 5 , wherein each of the cavity-containing insulating layers comprises a respective laterally-extending seam that continuously extends from a respective one of the encapsulated cavities through the insulating spacer and to the backside contact via structure.
7 . The three-dimensional memory device of claim 4 , wherein the insulating material portion comprises a plurality of sidewalls that contact sidewalls of each of the cavity-free insulating layers, each of the first-type electrically conductive layers, and each of the second-type electrically conductive layers within the vertical repetition.
8 . A three-dimensional memory device, comprising:
a vertical repetition of multiple instances of a unit layer stack, wherein the unit layer stack comprises, from bottom to top or from top to bottom, a cavity-free insulating layer that is free of any cavity therein, a first-type electrically conductive layer, a cavity-containing insulating layer including an encapsulated cavity therein, and a second-type electrically conductive layer;
memory openings vertically extending through the vertical repetition; and
memory opening fill structures located within the memory openings, wherein each of the memory opening fill structures comprises a respective vertical stack of memory elements,
wherein:
the first-type electrically conductive layers and the second-type electrically conductive layers consist essentially of a single metal; and
each of the first-type electrically conductive layers and the second-type electrically conductive layers contacts a horizontal surface of a respective one of the cavity-free insulating layers and a horizontal surface of a respective one of the cavity-containing insulating layers.