Three-dimensional memory device containing through-memory-level contact via structures
A contact via structure vertically extending through an alternating stack of insulating layers and electrically conductive layers is provided in a staircase region having stepped surfaces. The contact via structure is electrically isolated from each electrically conductive layer of the alternating stack except for an electrically conductive layer that directly underlies a horizontal interface of the stepped surfaces. A laterally-insulated structure includes a conductive via structure having an upper conductive via portion overlying and contacting an annular area of a top surface of one of the electrically conductive layers, a lower conductive via portion having a lesser lateral dimension than the upper conductive via portion and extending through at least a bottommost one of the electrically conductive layers, and an interconnection conductive via portion located between the upper conductive via portion and the lower conductive via portion and contacting a cylindrical sidewall of the one of the electrically conductive layers.
1. A device structure comprising:
an alternating stack of insulating layers and electrically conductive layers located over a substrate and including stepped surfaces in a staircase region;
a retro-stepped dielectric material portion overlying the stepped surfaces of the alternating stack; and
a laterally-insulated via structure vertically extending through the alternating stack and the retro-stepped dielectric material portion,
wherein the laterally-insulated via structure comprises a conductive via structure having an upper conductive via portion overlying and contacting an annular area of a top surface of one of the electrically conductive layers, a lower conductive via portion having a lesser lateral dimension than the upper conductive via portion and extending through at least a bottommost one of the electrically conductive layers, and an interconnection conductive via portion located between the upper conductive via portion and the lower conductive via portion and contacting an upper portion of a cylindrical sidewall of the one of the electrically conductive layers, and the laterally-insulated via structure further comprises a lower insulating spacer that laterally surrounds the lower conductive via portion and a lower portion of the cylindrical sidewall of the one of the electrically conductive layers laterally surrounds an upper portion of the lower insulating spacer wherein a dielectric material layer is located on the lower portion of the cylindrical sidewall of the one of the electrically conductive layers, and the upper portion of the lower insulating spacer contacts the dielectric material layer, and wherein the dielectric material layer extends continuously over the lower portion of the cylindrical sidewall and a horizontal bottom surface of the one of the electrically conductive layers, and the dielectric material layer is not present in the upper portion of the cylindrical sidewall of the one of the electrically conductive layers.
2. The device structure of claim 1 , wherein:
the upper conductive via portion has a first lateral dimension between a facing pair of sidewalls thereof; and
the lower conductive via portion has a second lateral dimension that is less than the first lateral dimension between a facing pair of sidewalls thereof.
3. The device structure of claim 2 , wherein:
the interconnection conductive via portion has a third lateral dimension between a facing pair of sidewalls thereof; and
the third lateral dimension is greater than the second lateral dimension and is less than the first lateral dimension.
4. The device structure of claim 1 , further comprising lower-level metal interconnect structures embedded in lower-level dielectric material layers and located between the substrate and the alternating stack, wherein a bottom surface of the lower conductive via portion contacts an area of a top surface of one of the lower-level metal interconnect structures.
5. The device structure of claim 4 , wherein the laterally-insulated via structure further comprises an upper insulating spacer that laterally surrounds the upper conductive via portion and overlies an additional annular area of the top surface of the one of the electrically conductive layers.
6. The device structure of claim 5 , wherein the lower insulating spacer that laterally surrounds the lower conductive via portion has a same material composition as the upper insulating spacer.
7. The device structure of claim 6 , wherein the lower insulating spacer contacts an annular area of the top surface of one of the lower-level metal interconnect structures.
8. The device structure of claim 1 , wherein:
each of the electrically conductive layers comprises a respective metal nitride liner and a respective metal fill portion that is embedded in the respective metal nitride liner; and
the annular area of the top surface of the one of the electrically conductive layers comprises an annular area of a top surface of a metal nitride liner of the one of the electrically conductive layers.
9. The device structure of claim 1 , wherein the lower portion of the cylindrical sidewall of the one of the electrically conductive layers contacts the upper portion of the lower insulating spacer.