Three-dimensional memory device with dielectric wall support structures and method of forming the same
A three-dimensional memory device includes an alternating stack of insulating layers and electrically conductive layers located between line trenches, a first memory array region and a second memory array region, and a pair of dielectric wall structures located between the first line trench and the second line trench and between the memory array regions. Each layer within the alternating stack continuously extends between the first memory array region and the second memory array region in a connection region. The electrically conductive layers of the alternating stack have lateral extents that decrease with a distance from the substrate in a staircase region. Dielectric material plates interlaced with insulating plates or insulating layers are provided between the dielectric wall structures.
1. A three-dimensional memory device, comprising:
an alternating stack of insulating layers and electrically conductive layers located between a first line trench and a second line trench that laterally extend along a first horizontal direction and over a substrate;
a first memory array region and a second memory array region that are laterally spaced apart along the first horizontal direction and including each layer of the alternating stack, wherein a respective set of memory stack structures each comprising a vertical semiconductor channel and a memory film vertically extends through the alternating stack within each of the first memory array region and the second memory array region;
a first dielectric wall structure and a second dielectric wall structure that are located between the first line trench and the second line trench and between the first memory array region and the second memory array region, laterally extending along the first horizontal direction, and having a respective lateral extent along the first horizontal direction that is less than a lateral extent of the first line trench along the first horizontal direction, and is less than a lateral extent of the second line trench along the first horizontal direction, wherein a connection region is located between the first line trench and the first dielectric wall structure, and a staircase region is located between the second line trench and the second dielectric wall structure, and the electrically conductive layers of the alternating stack have lateral extents along the first horizontal direction that decrease in a vertical direction with an increase in a vertical distance away from the substrate; and
an alternating stack of dielectric material plates and insulating plates or layers located between the first dielectric wall structure and the second dielectric wall structure, wherein the dielectric material plates have horizontal cross-sectional areas that decrease in the vertical direction with an increase in the vertical distance away from the substrate.
2. The three-dimensional memory device of claim 1 , wherein:
the dielectric material plates have first lateral extents along the first horizontal direction that decrease with the vertical distance from the substrate; and
the dielectric material plates have second lateral extents along a second horizontal direction that decrease with the vertical distance from the substrate, wherein the second horizontal direction is perpendicular to the first horizontal direction.
3. The three-dimensional memory device of claim 2 , further comprising a dielectric fill material portion overlying the dielectric material plates and contacting the first dielectric wall structure and the second dielectric wall structure, wherein the dielectric fill material portion has a greater contact area with the second dielectric wall structure than with the first dielectric wall structure.
4. The three-dimensional memory device of claim 1 , further comprising:
lower-level dielectric material layers located between the substrate and a combination of the alternating stack and the dielectric material plates and embedding lower-level metal interconnect structures;
upper-level dielectric material layers located above the combination of the alternating stack and the dielectric material plates and embedding upper-level metal interconnect structures;
connection via structures that vertically extend through the dielectric material plates and contacting a respective one of the lower-level metal interconnect structures and a respective one of the upper-level metal interconnect structures; and
layer contact via structures contacting a top surface of a respective one of the electrically conductive layers within an area of the staircase region.
5. The three-dimensional memory device of claim 4 , wherein the layer contact via structures are electrically connected to a respective one of the connection via structures through a respective metal line of the upper-level metal interconnect structures.
6. The three-dimensional memory device of claim 4 , further comprising:
an additional alternating stack of additional insulating layers and additional electrically conductive layers located between the first line trench and the second line trench and overlying, or underlying, the alternating stack; and
additional dielectric material plates that are embedded within the additional alternating stack, wherein the connection via structures vertically extend through each of the additional dielectric material plates.
7. The three-dimensional memory device of claim 6 , further comprising a first additional dielectric wall structure and a second additional dielectric wall structure that contact the additional dielectric material plates, wherein the additional dielectric material plates are laterally bounded along a second horizontal direction that is perpendicular to the first horizontal direction by the first additional dielectric wall structure and the second additional dielectric wall structure.
8. The three-dimensional memory device of claim 6 , wherein:
the additional dielectric material plates overlie the staircase region of the alternating stack; and
the layer contact via structures vertically extend through each of the additional dielectric material plates.
9. The three-dimensional memory device of claim 1 , further comprising a moat trench laterally surrounding the dielectric material plates and laterally surrounded by the alternating stack, wherein the first dielectric wall structure and the second dielectric wall structure are portions of a moat-shaped dielectric material that fill two-laterally extending portions of the moat trench, and are directly or indirectly connected to each other by a pair of widthwise dielectric wall portions.
10. The three-dimensional memory device of claim 1 , wherein:
the first dielectric wall structure and the second dielectric wall structure are two disjoined material portions that are not in direct contact with each other; and
the electrically conductive layers of the alternating stack and the dielectric material plates are in contact at vertical interfaces located within two vertically-extending planes that are laterally spaced apart along the first horizontal direction.
11. The three-dimensional memory device of claim 1 , wherein:
the dielectric material plates are interlaced with insulating plates along the vertical direction;
the insulating layers and the insulating plates have a same material composition; and
each horizontal surface of the insulating layers is located within a horizontal plane including a horizontal surface of a respective one of the insulating plates.