Three-dimensional memory device and method of making thereof using double pitch word line formation
A vertical repetition of multiple instances of a unit layer stack is formed over a substrate. The unit layer stack includes an insulating layer and a sacrificial material layer. Lateral recesses are formed by removing the sacrificial material layers selective to the insulating layers. Each lateral recess is sequentially fill with at least one conductive fill material and an insulating fill material, and vertically-extending portions of the at least one conductive fill material are removed such that a vertical layer stack including a first-type electrically conductive layer, a seamed insulating layer, and a second-type electrically conductive layer are formed in each lateral recess. Memory opening fill structures including a respective vertical stack of memory elements is formed through the insulating layers and the layer stacks. Access points for providing an etchant for removing the sacrificial material layers may be provided by memory openings, contact via cavities or backside trenches.
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, a first-type insulating layer, a first-type electrically conductive layer, a second-type insulating layer, and a second-type electrically conductive layer;
memory openings vertically extending through the vertical repetition;
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; and
a laterally insulated contact structure comprising:
a tubular contact via structure vertically extending through at least one instance of the unit layer stack and contacting an annular top surface of the second-type electrically conductive layer in an underlying instance of the unit layer stack; and
a cylindrical contact via structure laterally surrounded by the tubular contact via structure and contacting an annular top surface of the first-type electrically conductive layer in the underlying instance of the unit layer stack;
wherein:
the first-type electrically conductive layer comprises a first conductive barrier liner and a first conductive fill material layer that overlies the first conductive barrier liner;
the second-type electrically conductive layer comprises a second conductive fill material layer and a second conductive barrier liner that overlies the second conductive fill material layer;
the cylindrical contact via structure contacts the first conductive fill material layer of the underlying instance of the unit layer stack and does not contact the first conductive barrier liner of the underlying instance of the unit layer stack; and
the tubular contact via structure contacts the second conductive barrier liner of the underlying instance of the unit layer stack and does not contact the second conductive fill material layer of the underlying instance of the unit layer stack.
2. 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, a first-type insulating layer, a first-type electrically conductive layer, a second-type insulating layer, and a second-type electrically conductive layer;
memory openings vertically extending through the vertical repetition;
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; and
a laterally insulated contact structure comprising:
a tubular contact via structure vertically extending through at least one instance of the unit layer stack and contacting an annular top surface of the second-type electrically conductive layer in an underlying instance of the unit layer stack; and
a cylindrical contact via structure laterally surrounded by the tubular contact via structure and contacting an annular top surface of the first-type electrically conductive layer in the underlying instance of the unit layer stack;
wherein the laterally insulated contact structure comprises an outer dielectric tubular spacer laterally surrounding the tubular contact via structure and contacting an additional annular top surface of the second-type electrically conductive layer in the underlying instance of the unit layer stack; and
wherein the laterally-insulated contact structure further comprises an inner dielectric tubular spacer laterally surrounded by the tubular contact via structure, laterally surrounding the cylindrical contact via structure, and contacting a sidewall of the second-type electrically conductive layer in the underlying instance of the unit layer stack, a sidewall of the second-type insulating layer in the underlying instance of the unit layer stack, and an annular top surface of the first-type electrically conductive layer in the underlying instance of the unit layer stack.
3. 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, a first-type insulating layer, a first-type electrically conductive layer, a second-type insulating layer, and a second-type electrically conductive layer;
memory openings vertically extending through the vertical repetition;
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; and
a laterally insulated contact structure comprising:
a tubular contact via structure vertically extending through at least one instance of the unit layer stack and contacting an annular top surface of the second-type electrically conductive layer in an underlying instance of the unit layer stack; and
a cylindrical contact via structure laterally surrounded by the tubular contact via structure and contacting an annular top surface of the first-type electrically conductive layer in the underlying instance of the unit layer stack;
wherein:
the first-type electrically conductive layer comprises a first conductive barrier liner and a first conductive fill material layer that overlies the first conductive barrier liner; and
the second-type electrically conductive layer comprises a second conductive fill material layer and a second conductive barrier liner that overlies the second conductive fill material layer; and
wherein within each instance of the unit layer stack:
an entirety of a bottom surface of the second-type insulating layer is in direct contact with a top surface of the first conductive fill material layer; and
an entirety of a bottom surface of the second conductive fill material layer is in direct contact with a top surface of the second-type insulating layer.