Vertical array of resistive switching devices having a tunable oxygen vacancy concentration

1. A vertical resistive device comprising:

a conductive horizontal electrode;

an opening extending through the horizontal electrode;

a filament region positioned within the opening and communicatively coupled to a sidewall of the horizontal electrode;

a barrier region positioned within the opening and communicatively coupled to the filament region; and

a conductive vertical electrode positioned within the opening and communicatively coupled through the barrier region to the filament region;

wherein:

the vertical electrode comprises a first conductive alloy material;

oxygen vacancy formation in the filament region is controlled by the first conductive alloy material of the vertical electrode;

a thickness dimension of the barrier region; and

a room temperature resistivity of the first conductive alloy material is below about 5×10 −8 ohm meters and controlled by at least one element that forms the first conductive alloy material.

2. The device of claim 1 , wherein the at least one of the elements that form the first conductive alloy material comprises aluminum.

3. The device of claim 2 , wherein the first conductive alloy material comprises a titanium aluminum alloy or a cobalt aluminum alloy.

4. The device of claim 1 , wherein:

oxygen vacancy formation in the filament region comprises diffusion of oxygen molecules across the barrier region; and

the diffusion of oxygen molecules across the barrier region is tuned by selecting:

a barrier material that forms the barrier region; and

the thickness dimension of the barrier metal layer.

5. The device of claim 1 , wherein the barrier material is configured to prevent alloying of the filament region with the vertical electrode.

6. The device of claim 5 , wherein the barrier material is selected from a group consisting of titanium nitride (TiN), tantalum nitride (TaN), hafnium nitride (HfN), niobium nitride (NbN), tungsten nitride (WN), and combinations thereof.

7. The device of claim 1 further comprising:

a first dielectric layer across from the horizontal electrode; and

a second dielectric layer on an opposite side of the horizontal electrode than the first dielectric layer;

wherein:

the opening also extends through the first dielectric layer and the second dielectric layer; and

sidewalls of the opening comprise sidewalls of the first dielectric layer and sidewalls of the second dielectric layer.

8. The device of claim 7 , wherein:

the first dielectric layer and the second dielectric layer comprise silicon nitride (SiN) or silicon dioxide (SiO 2 );

the filament region comprises a metal oxide comprising a compound selected from the group consisting of HfO 2 , Ta 2 O 5 , and ZrO 2 .

9. The device of claim 1 further including a resistive switching device (RSD) comprising:

a bottom electrode comprising the horizontal electrode;

the filament region; and

a top electrode comprising the vertical electrode.

10. The device of claim 1 , wherein the conductive horizontal electrode comprises titanium nitride (TiN) or tungsten (W).

11. A method of fabricating a vertical resistive device, the method comprising:

forming a conductive horizontal electrode;

forming an opening that extends through the horizontal electrode;

depositing a filament region within the opening such that the filament region is communicatively coupled to a sidewall of the horizontal electrode;

depositing a barrier region within the opening such that the barrier region is communicatively coupled to the filament region; and

forming a conductive vertical electrode within a remaining portion of the opening such that the vertical electrode is communicatively coupled to the barrier region;

wherein:

the vertical electrode comprises a first conductive alloy material;

oxygen vacancy formation in the filament region is controlled by a thickness dimension of the barrier region and by the first conductive alloy material of the vertical electrode; and

a room temperature resistivity of the first conductive alloy material is below about 5×10 −8 ohm meters and controlled by at least one element that forms the first conductive alloy material.

12. The method of claim 11 , wherein the at least one element that forms the first conductive alloy material comprises aluminum.

13. The method of claim 12 , wherein the first conductive alloy material comprises a titanium aluminum alloy or a cobalt aluminum alloy.

14. The method of claim 11 , wherein forming the conductive vertical electrode comprises:

depositing a wetting layer over the barrier layer;

depositing a fill metal over the wetting layer; and

reflowing the wetting layer and the fill metal to form an alloy of the wetting layer and the fill metal.

15. The method of claim 14 , wherein the barrier region comprises a barrier material configured to prevent alloying of the filament region with the wetting layer and the fill metal.

16. The method of claim 15 , wherein the barrier material is selected from a group consisting of titanium nitride (TiN), tantalum nitride (TaN), hafnium nitride (HfN), niobium nitride (NbN), tungsten nitride (WN), and combinations thereof.

17. The method of claim 11 further comprising:

forming a first dielectric layer across from the horizontal electrode; and

forming a second dielectric layer on an opposite side of the horizontal electrode than the first dielectric layer;

wherein:

the opening also extends through the first dielectric layer and the second dielectric layer; and

sidewalls of the opening comprise sidewalls of the first dielectric layer and sidewalls of the second dielectric layer.

18. The method of claim 17 , wherein:

the first dielectric layer and the second dielectric layer comprise silicon nitride (SiN) or silicon dioxide (SiO 2 );

the filament region comprises a metal oxide comprising a compound selected from the group consisting of HfO 2 , Ta 2 O 5 , and ZrO 2 .

19. The method of claim 11 , wherein the vertical resistive device comprises a resistive switching device (RSD) comprising:

a bottom electrode comprising the horizontal electrode;

the filament region; and

a top electrode comprising the vertical electrode.

20. The method of claim 11 , wherein the horizontal electrode comprises titanium nitride (TiN) or tungsten (W).