Resistive random access memory (RRAM) structure

1. A resistive random access memory (RRAM) cell comprising:

a bottom electrode layer;

a group-V oxide layer arranged over the bottom electrode layer;

a hafnium oxide based layer arranged over and abutting the group-V oxide layer;

a capping layer arranged over and abutting the hafnium oxide based layer;

a top electrode layer arranged over the capping layer; and

a fully or partially formed conductive filament arranged within the hafnium oxide and group-V oxide layers, and extending from the group-V oxide layer into the hafnium oxide based layer, wherein the conductive filament includes an upper region and a lower region demarcated by an interface between the hafnium oxide and group-V oxide layers, and wherein the lower region has a smaller footprint than the upper region.

2. The RRAM cell according to claim 1 , wherein the hafnium oxide based layer is bisected into an upper region and a lower region, and wherein the RRAM cell further includes:

a data storage region comprising the group-V oxide layer and the lower region of the hafnium oxide based layer, and configured to vary in resistance in response to external electric fields; and

an ion reservoir including the capping layer and the upper region of the hafnium oxide based layer, and configured to store oxygen ions from the data storage region.

3. The RRAM cell according to claim 1 , wherein the capping layer has a lower concentration of oxygen than the hafnium oxide based layer, and is configured to extract oxygen from the hafnium oxide based layer.

4. The RRAM cell according to claim 1 , wherein the group-V oxide layer is one of tantalum oxide, niobium oxide, vanadium oxide, tantalum titanium oxide, and tantalum aluminum oxide.

5. The RRAM cell according to claim 1 , wherein the hafnium oxide based layer consists of hafnium and oxide.

6. The RRAM cell according to claim 1 , wherein the hafnium oxide based layer includes hafnium, oxide, and one or more additional elements.

7. The RRAM cell according to claim 1 , wherein the hafnium oxide based layer includes one or more of hafnium aluminum oxide, hafnium silicon oxide, hafnium titanium oxide, and hafnium tantalum oxide.

8. The RRAM cell according to claim 1 , wherein the hafnium oxide based layer is about 15-40 Angstroms thick, and wherein the group-V oxide layer is about 5-40 Angstroms thick.

9. A method for manufacturing a resistive random access memory (RRAM) cell, the method comprising:

forming a RRAM stack comprising a bottom electrode layer, a group-V oxide layer, a hafnium oxide based layer, a capping layer, and a top electrode layer stacked in that order;

forming a hard mask layer masking a device region of the RRAM stack;

performing a first etch of the top electrode layer and the capping layer according to the hard mask layer, wherein the first etch extends to the hafnium oxide based layer;

forming a sidewall spacer layer over the hafnium oxide based layer, and lining the remaining to electrode and capping layers and the hard mask layer; and

performing a second etch of the bottom electrode layer, the group-V oxide layer, and the hafnium oxide based layer according to the hard mask layer and the sidewall spacer layer.

10. The method according to claim 9 , further including:

forming the hafnium oxide based layer over and abutting the group-V oxide layer; and

forming the capping layer over and abutting the hafnium oxide based layer.

11. The method according to claim 9 , further including:

applying a forming voltage across the top and bottom electrode layers to form a conductive filament within the hafnium oxide based and group-V oxide layers, and extending from the group-V oxide layer into the hafnium oxide based layer, wherein the conductive filament includes an upper region and a lower region demarcated by an interface between the hafnium oxide based and group-V oxide layers, and wherein the lower region has a smaller footprint than the upper region.

12. The method according to claim 9 , further including:

forming the capping layer with a lower concentration of oxygen than the hafnium oxide based layer.

13. The method according to claim 9 , further including:

forming the group-V oxide layer from one of tantalum oxide, niobium oxide, vanadium oxide, tantalum titanium oxide, and tantalum aluminum oxide.

14. The method according to claim 9 , further including:

forming the hafnium oxide based layer with hafnium, oxide, and one or more additional elements.

15. The method according to claim 9 , further including:

forming the hafnium oxide based layer from one or more of hafnium aluminum oxide, hafnium silicon oxide, hafnium titanium oxide, and hafnium tantalum oxide.

16. The method according to claim 9 , further including:

forming the hafnium oxide based layer with a thickness of about 15-40 Angstroms; and

forming the group-V oxide layer with a thickness of about 5-40 Angstroms.

17. The method according to claim 9 , further including:

forming an insulating layer lining the remaining bottom electrode, group-V oxide, and hafnium oxide layers and the hard mask layer;

forming an interlayer dielectric (ILD) layer over and around the insulating layer; and

forming a metallization layer over the ILD layer and a via extending between the remaining top electrode layer and the metallization layer.

18. An integrated circuit of a resistive random access memory (RRAM) cell, the integrated circuit comprising:

a bottom electrode layer;

a high κ layer with a variable resistance and a dielectric constant exceeding 3.9, wherein the high κ layer includes:

a group-V oxide layer arranged over the bottom electrode layer; and

a hafnium oxide based layer arranged over and abutting the group-V oxide layer, wherein the hafnium oxide based layer is bisected into an upper region and a lower region;

a capping layer arranged over and abutting the hafnium oxide based layer;

a top electrode layer arranged over the capping layer;

a data storage region comprising the group-V oxide layer and the lower region, and configured to vary in resistance in response to external electric fields; and

an ion reservoir including the capping layer and the upper region, and configured to store oxygen ions from the data storage region.

19. The integrated circuit according to claim 18 , further comprising:

a conductive filament arranged within the hafnium oxide and group-V oxide layers, and extending from the group-V oxide layer into the hafnium oxide based layer, wherein the conductive filament includes an upper region and a lower region demarcated by an interface between the hafnium oxide and group-V oxide layers, and wherein the lower region of the conductive filament has a smaller footprint than the upper region of the conductive filament.

20. The integrated circuit according to claim 18 , wherein the capping layer has a lower concentration of oxygen than the hafnium oxide based layer, and is configured to extract oxygen from the hafnium oxide based layer.