Resistive memory cell using an interfacial transition metal compound layer and method of forming the same
A resistive memory cell includes a lower electrode, a resistive transition metal oxide layer, and an upper electrode. The lower electrode includes at least one lower metallic barrier layer, a lower metal layer including a first metal having a melting point higher than 2,000 degrees Celsius, and a transition metal compound layer including an oxide or nitride of a transition metal selected from Ti, Ta, and W. The resistive transition metal oxide layer includes a conductive-filament-forming dielectric oxide of at least one transition metal and located on the transition metal compound layer. The upper electrode includes an upper metal layer including a second metal having a melting point higher than 2,000 degrees Celsius and at least one upper metallic barrier layer.
1. A device structure comprising a resistive memory cell, wherein the resistive memory cell comprises:
a lower electrode comprising at least one lower metallic barrier layer, a lower metal layer comprising a first metal having a melting point higher than 2,000 degrees Celsius, and a transition metal compound layer comprising an oxide or nitride of a transition metal selected from Ti, Ta, and W;
a resistive transition metal oxide layer comprising a conductive-filament-forming dielectric oxide of at least one transition metal and located on the transition metal compound layer; and
an upper electrode comprising an upper metal layer comprising a second metal.
2. The device structure of claim 1 , wherein the transition metal compound layer comprises a transition metal oxide material selected from titanium oxide and tantalum oxide.
3. The device structure of claim 1 , wherein the transition metal compound layer comprises a transition metal nitride material selected from titanium nitride, tantalum nitride, and tungsten nitride.
4. The device structure of claim 1 , wherein an entirety of a top surface of the transition metal compound layer is in contact with an entirety of a bottom surface of the resistive transition metal oxide layer.
5. The device structure of claim 1 , wherein the conductive-filament-forming dielectric oxide comprises a material selected from hafnium oxide, zirconium oxide, titanium oxide, hafnium zirconium oxide, and strontium cobalt oxide.
6. The device structure of claim 1 , wherein the resistive memory cell comprises a dielectric spacer laterally surrounding the upper electrode.
7. The device structure of claim 6 , wherein:
an entirety of a bottom surface of the upper metal layer contacts a center portion of a top surface of the resistive transition metal oxide layer; and
an entirety of a bottom surface of the dielectric spacer contacts a peripheral portion of the top surface of the resistive transition metal oxide layer.
8. The device structure of claim 6 , wherein the resistive memory cell comprises a dielectric cap contacting a top surface of the upper electrode, wherein a periphery of a bottom surface of the dielectric cap coincides with a periphery of a top surface of the upper electrode.
9. The device structure of claim 8 , further comprising:
a dielectric material layer laterally surrounding the resistive memory cell and having a top surface located above a horizontal top surface of the dielectric cap; and
an upper connection via structure vertically extending through the dielectric material layer and the dielectric cap and contacting a top surface of the upper electrode.
10. The device structure of claim 1 , further comprising a dielectric etch stop layer including an opening, wherein:
a center portion of the lower electrode is located within the opening;
a peripheral portion of the lower electrode is locate outside the opening above a top surface of the dielectric etch stop layer; and
a cylindrical connection portion of the lower electrode contacts a sidewall of the opening and vertically extends between the center portion of the lower electrode and the peripheral portion of the lower electrode.
11. The device structure of claim 10 , wherein the transition metal compound layer comprises:
a bottom surface including a planar central bottom surface segment located within an area of the opening through the dielectric etch stop layer, a planar peripheral bottom surface segment located outside the area of the opening through the dielectric etch stop layer, and a concave connecting bottom surface segment that connects the planar central bottom surface segment and the planar peripheral bottom surface segment; and
a top surface including a planar central top surface segment located within an area of the opening through the dielectric etch stop layer, a planar peripheral top surface segment located outside the area of the opening through the dielectric etch stop layer, and a convex connecting top surface segment that connects the planar central top surface segment and the planar peripheral top surface segment.
12. The device structure of claim 1 , wherein:
the first metal comprises an element selected from ruthenium, tantalum, tungsten, rhenium, niobium, molybdenum, osmium, and iridium; and
the second metal comprises an element selected from ruthenium, tantalum, tungsten, rhenium, niobium, molybdenum, osmium, and iridium.
13. The device structure of claim 1 , wherein:
the at least one lower metallic barrier layer comprises a lower vertical stack including, from bottom to top, a first lower tantalum nitride layer, a lower tantalum layer, and a second lower tantalum nitride layer; and
the upper electrode comprises at least one upper metallic barrier layer, which comprises an upper vertical stack including, from bottom to top, an upper tantalum nitride layer and a titanium nitride layer.
14. A device structure comprising a resistive memory cell, wherein the resistive memory cell comprises:
a lower electrode comprising at least one lower metallic barrier layer, a lower metal layer comprising a first metal having a melting point higher than 2,000 degrees Celsius, and a transition metal compound layer comprising an oxide or nitride of a transition metal selected from Ti, Ta, and W;
a resistive transition metal oxide layer comprising a conductive-filament-forming dielectric oxide of at least one transition metal and located on the transition metal compound layer;
an upper electrode comprising an upper metal layer comprising a second metal; and
a dielectric spacer laterally surrounding the upper electrode, wherein a bottom periphery of an outer sidewall of the dielectric spacer coincides with a periphery of a top surface of the resistive transition metal oxide layer.
15. The device structure of claim 14 , wherein the bottom periphery of the outer sidewall of the dielectric spacer is laterally offset outward from a bottom periphery of an inner sidewall of the dielectric spacer by a uniform lateral offset distance.
16. The device structure of claim 14 , wherein the resistive transition metal oxide layer comprises:
a peripheral portion in contact with the dielectric spacer;
a center portion that is vertically recessed relative to the peripheral portion; and
a tapered annular connecting portion that connects the peripheral portion and the center portion.
17. The device structure of claim 14 , wherein the upper metal layer comprises downward protrusion at a center region thereof, wherein the downward protrusion extends below a horizontal plane including an annular horizontal bottom surface of a peripheral portion of the resistive transition metal oxide layer.
18. The device structure of claim 14 , wherein the conductive-filament-forming dielectric oxide comprises a material selected from hafnium oxide, zirconium oxide, titanium oxide, hafnium zirconium oxide, and strontium cobalt oxide.
19. A device structure comprising a resistive memory cell, wherein the resistive memory cell comprises:
a dielectric etch stop layer including an opening therethrough;
a lower electrode comprising at least one lower metallic barrier layer, a lower metal layer comprising a first metal having a melting point higher than 2,000 degrees Celsius, and a transition metal compound layer comprising an oxide or nitride of a transition metal selected from Ti, Ta, and W, wherein the lower electrode comprises a peripheral portion overlying the dielectric etch stop layer and a center portion located within the opening in the dielectric etch stop layer;
a resistive transition metal oxide layer comprising a conductive-filament-forming dielectric oxide of at least one transition metal and located on the transition metal compound layer; and
an upper electrode comprising an upper metal layer comprising a second metal.
20. The device structure of claim 19 , wherein the transition metal compound layer comprises:
a bottom surface including a planar central bottom surface segment located within an area of the opening through the dielectric etch stop layer, a planar peripheral bottom surface segment located outside the area of the opening through the dielectric etch stop layer, and a concave connecting bottom surface segment that connects the planar central bottom surface segment and the planar peripheral bottom surface segment; and
a top surface including a planar central top surface segment located within an area of the opening through the dielectric etch stop layer, a planar peripheral top surface segment located outside the area of the opening through the dielectric etch stop layer, and a convex connecting top surface segment that connects the planar central top surface segment and the planar peripheral top surface segment.