Patternable low-k dielectric interconnect structure with a graded cap layer and method of fabrication

1. An interconnect structure comprising:

at least one patterned and cured low-k material located directly on a surface of a patterned graded cap layer, wherein said at least one patterned and cured low-k material and said patterned graded cap layer each have conductively filled regions embedded therein, wherein said patterned and cured low-k material is a cured product of a patternable composition comprising a functionalized polymer, copolymer, or a blend including at least two of any combination of polymers and/or copolymers having one or more photo/acid-sensitive imageable groups, and said patterned graded cap layer has a gradually varied composition along a vertical direction relative to an underlying substrate and comprises a lower region that functions as a barrier region and an upper region that has the properties of a permanent antireflective coating, wherein said lower region and said upper region are separated by at least one middle region, said at least one middle region including a combination of atoms present in both said lower region and said upper region.

2. The interconnect structure of claim 1 further comprising at least one airgap located within that at least one patterned and cured low-k material adjacent, but not directly abutting the conductively filled regions.

3. The interconnect structure of claim 1 wherein said lower region of the graded cap layer includes atoms of Si and C; atoms of Si and N; atoms of Si and O, atoms of Si, O and N; atoms of Si, C and O; atoms of Si, C, O and H; or atoms of Si, C, N and H.

4. The interconnect structure of claim 1 wherein said lower region of the graded cap layer comprises atoms of Ru, Co, W and P.

5. The interconnect structure of claim 1 wherein said graded cap layer has a thickness range from 2 nm to 200 nm.

6. The interconnect structure of claim 1 wherein said upper region comprises atoms of Si, C, O, N and H; atoms of Si and C; atoms of Si, O and C; atoms of Si, C, O and H; and atoms of W, Co, Ru, Ta, Ti, and Ru.

7. The interconnect structure of claim 1 wherein said upper region includes atoms of M, C and H, wherein M is selected from at least one atom of Si, Ge, B, Sn, Fe, Ta, Ti, Ni, Hf and La.

8. The interconnect structure of claim 7 further comprising at least one atom of O, N, S or F.

9. The interconnect structure of claim 1 wherein said upper region comprises a vapor deposited M:C:H film wherein M is selected from at least one atoms of Si, Ge, B, Sn, Fe, Ta, Ti, Ni, Hf and La.

10. The interconnect structure of claim 9 further comprising X, wherein is at least one atom of O, N, S or F.

11. The interconnect structure of claim 1 wherein said upper region comprises a polymer that has at least one monomer unit of the formula M-R A wherein M is at least one of the elements of Si, Ge, B, Sn, Fe, Ta, Ti, Ni, Hf and La, and R A is a chromophore.

12. The interconnect structure of claim 11 wherein M of the at least one monomer unit is bonded to an organic ligand selected from elements of C and H, a cross-linking component, another chromophore and mixtures thereof.

13. The interconnect structure of claim 11 further comprising another monomer unit, said another monomer unit having the formula M′-R B , wherein M′ is at least one of the elements of Si, Ge, B, Sn, Fe, Ta, Ti, Ni, Hf and La, and R B is a cross-linking component.

14. The interconnect structure of claim 11 wherein M and M′ is bonded to an organic ligand selected from elements of C and H, a cross-linking component, another chromophore and mixtures thereof.

15. An interconnect structure comprising:

a lower patterned and cured low-k material located directly on a patterned graded cap layer and an abutting upper patterned and cured low-k material located on said lower patterned and cured low-k material, said lower and upper patterned and cured low-k materials and said patterned cap layer each having conductively filled regions, wherein said patterned and cured upper and lower low-k materials each are cured products of a same or different patternable composition comprising functionalized polymer, copolymer, or a blend including at least two of any combination of polymers and/or copolymers having one or more photo/acid-sensitive imageable groups, and said patterned graded cap layer has a gradually varied composition along a vertical direction relative to an underlying substrate and comprises a lower region that functions as a barrier region and an upper region that has properties of a permanent antireflective coating, wherein said lower region and said upper region are separated by at least one middle region, said at least one middle region including a combination of atoms present in both said lower region and said upper region.

16. An airgap-containing interconnect structure comprising:

a lower patterned and cured low-k material located directly on a patterned graded cap layer and an abutting upper patterned and cured low-k material located on said lower patterned and cured low-k material, said lower and upper patterned and cured low-k materials and said patterned cap layer each having conductively filled regions, wherein said patterned and cured upper and lower low-k materials each are cured products of a same or different patternable composition comprising functionalized polymer, copolymer, or a blend including at least two of any combination of polymers and/or copolymers having one or more photo/acid-sensitive imageable groups, and said patterned graded cap layer has a gradually varied composition along a vertical direction relative to an underlying substrate and comprises a lower region that functions as a barrier region and an upper region that has properties of a permanent antireflective coating, wherein said lower region and said upper region are separated by at least one middle region, said at least one middle region including a combination of atoms present in both said lower region and said upper region, and further wherein at least one airgap is located within the upper patterned and cured low-k material located adjacent, but not directly abutting the conductively filled regions.