Self-aligned composite M-MOx/dielectric cap for Cu interconnect structures
View Patent ↗An interconnect structure is provided that has improved electromigration resistance as well as methods of forming such an interconnect structure. The interconnect structure includes an interconnect dielectric material having a dielectric constant of about 4.0 or less. The interconnect dielectric material has at least one opening therein that is filled with a Cu-containing material. The Cu-containing material within the at least one opening has an exposed upper surface that is co-planar with an upper surface of the interconnect dielectric material. The interconnect structure further includes a composite M-MOx cap located at least on the upper surface of the Cu-containing material within the at least one opening. The composite M-MOx cap includes an upper region that is composed of the metal having a higher affinity for oxygen than copper and copper oxide and a lower region that is composed of a non-stoichiometric oxide of said metal. The interconnect structure further includes a dielectric cap located on at least an upper surface of the composite M-MOx cap.
1. An interconnect structure comprising:
an interconnect dielectric material having a dielectric constant of about 4.0 or less, said interconnect dielectric material having at least one opening therein that is filled with a Cu-containing material, said Cu-containing material within the at least one opening having an upper surface that is co-planar with an upper surface of the interconnect dielectric material;
a composite M-MOx cap located at least atop said Cu-containing material within the at least one opening, wherein said composite M-MOx cap includes an upper region M that is composed of a metal having a higher affinity for oxygen than copper and copper oxide and a lower region MOx that is composed of a non-stoichiometric oxide of said metal, wherein a bottommost surface of said lower region of said composite M-MOx cap is located directly on said upper surface of said Cu-containing material and wherein said lower region of said composite M-MOx cap has edges that are vertically coincident with edges of said Cu-containing material; and
at least one dielectric cap layer located on at least an upper surface of the composite M-MOx cap.
2. The interconnect structure of wherein claim 1 wherein said metal M of said composite M-MOx cap is selected from Mn, Ta, Nb, Ti, Zr, Al, Ru, Co, Zn, Fe and Sn.
3. The interconnect structure of claim 2 wherein said metal of said composite M-MOx cap is Mn.
4. The interconnect structure of claim 1 wherein said lower region of said composite M-MOx cap has a higher oxygen content than the upper region of said composite M-MOx cap.
5. The interconnect structure of claim 4 wherein said content of oxygen within the lower region diminishes from an interface with the Cu-containing material upwards to the upper region of the composite M-MOx cap.
6. The interconnect structure of claim 1 wherein said dielectric cap is a non-oxygen containing dielectric capping material.
7. The interconnect structure of claim 6 wherein said non-oxygen containing dielectric capping material is selected from SiC, Si 3 N 4 , a carbon doped oxide, a nitrogen and hydrogen doped silicon carbide SiC(N,H), boron nitride, SiCBN, carbon boron nitride and multilayers thereof.
8. The interconnect structure of claim 1 wherein said Cu-containing material within said at least one opening includes elemental Cu or a Cu alloy.
9. The interconnect structure of claim 1 further comprising a diffusion barrier located between said interconnect dielectric material and said Cu-containing material.
10. The interconnect structure of claim 1 wherein said upper region of said composite M-MOx cap has edges that are vertically coincident with said edges of said lower region of said composite M-MOx cap.
11. The interconnect structure of claim 1 wherein a portion of said upper region of said composite M-MOx extends onto an upper surface of the interconnect dielectric material, wherein said portion of said upper region of said composite M-MOx cap that extends onto the upper surface of the interconnect dielectric material includes at least one element of said interconnect dielectric material.
12. An interconnect structure comprising:
an interconnect dielectric material having a dielectric constant of about 4.0 or less, said interconnect dielectric material having at least one opening therein that is filled with a Cu-containing material, said Cu-containing material within the at least one opening having an upper surface that is co-planar with an upper surface of the interconnect dielectric material;
a composite M-MOx cap located at least atop said Cu-containing material within the at least one opening, wherein said composite M-MOx cap includes an upper region M that is composed of a metal having a higher affinity for oxygen than copper and copper oxide and a lower region MOx that is composed of a non-stoichiometric oxide of said metal, wherein a bottommost surface of said lower region of said composite M-MOx cap is located directly on said upper surface of said Cu-containing material and wherein said lower region of said composite M-MOx cap has edges that are vertically coincident with edges of said Cu-containing material and wherein said upper region of said composite M-MOx cap has edges that are vertically coincident with said edges of said lower region of said composite M-MOx cap; and
at least one dielectric cap layer located on at least an upper surface of the composite M-MOx cap, wherein a portion of said at least one dielectric cap layer directly contacts said upper surface of said interconnect dielectric material.
13. The interconnect structure of wherein claim 12 wherein said metal M of said composite M-MOx cap is selected from Mn, Ta, Nb, Ti, Zr, Al, Ru, Co, Zn, Fe and Sn.
14. The interconnect structure of claim 13 wherein said metal of said composite M-MOx cap is Mn.
15. The interconnect structure of claim 12 wherein said lower region of said composite M-MOx cap has a higher oxygen content than the upper region of said composite M-MOx cap.
16. The interconnect structure of claim 15 wherein said content of oxygen within the lower region diminishes from an interface with the Cu-containing material upwards to the upper region of the composite M-MOx cap.
17. An interconnect structure comprising:
an interconnect dielectric material having a dielectric constant of about 4.0 or less, said interconnect dielectric material having at least one opening therein that is filled with a Cu-containing material, said Cu-containing material within the at least one opening having an upper surface that is co-planar with an upper surface of the interconnect dielectric material;
a composite M-MOx cap located at least atop upper surface of said Cu-containing material within the at least one opening, wherein said composite M-MOx cap includes an upper region M that is composed of a metal having a higher affinity for oxygen than copper and copper oxide and a lower region MOx that is composed of a non-stoichiometric oxide of said metal; and at least one dielectric cap layer located on at least an upper surface of the composite M-MOx cap, wherein said metal M of said composite M-MOx cap is selected from Mn, Ta, Nb, Ti, Zr, Al, Ru, Co, Zn, Fe and Sn.
18. The interconnect structure of claim 17 wherein a bottommost surface of said lower region of said composite M-MOx cap is located directly on said upper surface of said Cu-containing material and wherein said lower region of said composite M-MOx cap has edges that are vertically coincident with edges of said Cu-containing material.
19. The interconnect structure of claim 18 wherein said upper region of said composite M-MOx cap has edges that are vertically coincident with said edges of said lower region of said composite M-MOx cap.