Three-dimensional memory device including ferroelectric-metal-insulator memory cells and methods of making the same
A memory opening or a line trench is formed through an alternating stack of insulating layers and sacrificial material layers. A memory opening fill structure or a memory stack assembly is formed, which includes a vertical stack of discrete intermediate metallic electrodes formed on sidewalls of the sacrificial material layers, a gate dielectric layer, and a vertical semiconductor channel. Backside recesses are formed by removing the sacrificial material layers selective to the insulating layers, and a combination of a ferroelectric dielectric layer and an electrically conductive layer within each of the backside recesses. The electrically conductive layer is laterally spaced from a respective one of the discrete intermediate metallic electrodes by the ferroelectric dielectric layer. Ferroelectric-metal-insulator memory elements are formed around the vertical semiconductor channel.
1. A three-dimensional memory device comprising:
alternating stacks of insulating strips and electrically conductive strips located over a substrate and laterally spaced apart from each other by line trenches laterally extending along a first horizontal direction and spaced apart from each other along a second horizontal direction;
a two-dimensional array of memory stack assemblies located in the line trenches;
a two-dimensional array of dielectric pillar structures located in the line trenches and laterally offset from, and interlaced with, the two-dimensional array of memory stack assemblies, wherein each line trench is filled with a respective row of memory stack assemblies and a respective row of dielectric pillar structures that is interlaced with the respective row of memory stack assemblies,
wherein:
each memory stack assembly comprises a vertical semiconductor channel, at least one gate dielectric layer, and two vertical stacks of discrete intermediate metallic electrodes;
each of the electrically conductive strips is laterally spaced from each memory stack assembly by a respective ferroelectric dielectric layer; and
each of the discrete intermediate metallic electrodes has a greater contact area with a respective gate dielectric layer than with the respective ferroelectric dielectric layer.
2. The three-dimensional memory device of claim 1 , wherein the ferroelectric dielectric layer comprises a horizontally-extending portion that contacts a horizontal surface of a respective one of the insulating strips.
3. The three-dimensional memory device of claim 1 , wherein each of the discrete intermediate metallic electrodes comprises a concave outer sidewall that contacts a convex inner sidewall of the respective ferroelectric dielectric layer.
4. The three-dimensional memory device of claim 3 , wherein the at least one gate dielectric layer contacts a respective vertical stack of discrete intermediate metallic electrodes within the two vertical stacks of discrete intermediate metallic electrodes.
5. The three-dimensional memory device of claim 3 , wherein the at least one gate dielectric layer has a laterally-undulating vertical cross-sectional profile that includes straight gate dielectric segments that contact a respective one of the insulating strips and curved gate dielectric segments contacting a respective vertical stack of discrete intermediate metallic electrodes.
6. The three-dimensional memory device of claim 5 , wherein each of the curved gate dielectric segments comprises a concave outer sidewall that contacts a respective one of the discrete intermediate metallic electrodes and a convex inner sidewall that contacts a concave sidewall segment of the vertical semiconductor channel.
7. The three-dimensional memory device of claim 1 , wherein the vertical semiconductor channel has a laterally-undulating vertical cross-sectional profile, and includes straight semiconductor channel segments located at levels of the insulating strips and curved semiconductor channel segments located at levels of the vertical stacks of discrete intermediate metallic electrodes.
8. The three-dimensional memory device of claim 7 , wherein the vertical semiconductor channel comprises a polycrystalline semiconductor material.
9. The three-dimensional memory device of claim 1 , wherein:
the substrate comprises a single crystalline semiconductor material; and
the vertical semiconductor channel comprises a single crystalline semiconductor material that is in epitaxial alignment with the single crystalline semiconductor material of the substrate.
10. The three-dimensional memory device of claim 1 , wherein the two vertical stacks of discrete intermediate metallic electrodes consist essentially of ruthenium.
11. The three-dimensional memory device of claim 1 , wherein each discrete intermediate metallic electrode within the two vertical stacks of discrete intermediate metallic electrodes comprises:
an outer concave sidewall in contact with a respective one of the ferroelectric dielectric layers; and
an inner convex sidewall in contact with the at least one gate dielectric layer.
12. The three-dimensional memory device of claim 11 , wherein each discrete intermediate metallic electrode within the two vertical stacks of discrete intermediate metallic electrodes comprises:
an upper vertical sidewall connecting an upper periphery of the inner convex sidewall and an upper periphery of the outer concave sidewall; and
a lower vertical sidewall connecting a lower periphery of the inner convex sidewall and a lower periphery of the outer concave sidewall.
13. The three-dimensional memory device of claim 1 , wherein each of the memory stack assemblies comprises a dielectric core contacting convex surfaces of the vertical semiconductor channel.