Modified via bottom structure for reliability enhancement

1. An interconnect structure comprising:

a first dielectric layer having at least one metallic interconnect embedded therein, wherein said at least one metallic interconnect has a metallic interconnect top surface;

a second dielectric layer that is located atop said first dielectric layer and has at least one aperture having an upper line region containing at least one metal line with a metal line bottom surface and a lower via region containing at least one metal via, wherein said metal line bottom surface contacts said lower via region, said at least one metal via includes a cylindrical portion with a substantially constant horizontal cross-sectional area and having a cylindrical portion top surface, at least one substantially vertical sidewall, and a kinked interface that lies above, but not directly within, said at least one metallic interconnect embedded in said first dielectric layer, said at least one substantially vertical sidewall adjoins said kinked interface and said cylindrical portion top surface, said metal line has a top surface that is substantially at the same level over said at least one metal via as over an area outside said at least one metal via, and said cylindrical portion top surface abuts said metal line bottom surface;

at least one pair of liners having a liner bottom surface and located on at least vertical walls of said at least one aperture, wherein said liner bottom surface is located below said metallic interconnect top surface; and

a conductive material filling said at least one aperture.

2. The interconnect structure of claim 1 wherein said metallic interconnect comprises a conductive metal or metal alloy.

3. The interconnect structure of claim 2 wherein said metal is Cu, W or Al.

4. The interconnect structure of claim 1 wherein said metallic interconnect comprises Cu.

5. The interconnect structure of claim 1 wherein said first dielectric layer has a dielectric constant of about 4.0 or less.

6. The interconnect structure of claim 5 wherein said first dielectric layer comprises SiO 2 , a polyarylene resin, or an organosilicate glass.

7. The interconnect structure of claim 1 further comprising a patterned cap layer on a surface of said first dielectric layer, said patterned cap layer having an opening that exposes a surface portion of said metallic interconnect.

8. The interconnect structure of claim 7 wherein said patterned cap layer comprises a nitride, oxynitride or a combination thereof.

9. The interconnect structure of claim 1 wherein said second dielectric layer has a dielectric constant of about 4.0 or less.

10. The interconnect structure of claim 9 wherein said second dielectric layer comprises SiO 2 , a polyarylene resin, or an organosilicate glass.

11. The interconnect structure of claim 1 further comprising a patterned hard mask on a surface of said second dielectric layer.

12. The interconnect structure of claim 11 wherein said patterned hard mask comprises a nitride, oxynitride or a combination thereof.

13. The interconnect structure of claim 1 wherein said at least one pair of liners comprises a first liner and a second liner comprising the same or different diffusion resistant material selected from the group consisting of refractory metals, refractory metal nitrides and TiNSi.

14. The interconnect structure of claim 13 further comprising a third liner, said third liner comprising the same or different diffusion resistant material as said first or second liner.

15. The interconnect structure of claim 1 wherein said at least one pair of liners extends over a surface portion of the metallic interconnect.

16. The interconnect structure of claim 1 wherein said at least one pair of liners do not entirely cover an upper surface of said at least one metallic interconnect providing an opened, yet kinked via bottom.

17. The interconnect structure of claim 1 wherein said conductive material comprises polySi, a conductive metal, an alloy including one conductive metal or a conductive metal silicide.

18. The interconnect structure of claim 1 wherein said conductive material comprises Cu.

19. An interconnect structure comprising:

a first dielectric layer having at least one Cu interconnect embedded therein, wherein said at least one Cu interconnect has a Cu interconnect top surface;

a patterned cap located on said first dielectric layer, said patterned cap has an opening that exposes a surface of said Cu interconnect;

a second dielectric layer that is located atop said patterned cap and has at least one aperture having an upper line region containing at least one metal line with a metal line bottom surface and a lower via region containing at least one metal via, wherein said metal line bottom surface contacts said lower via region, said at least one metal via includes a cylindrical portion with a substantially constant horizontal cross-sectional area and having a cylindrical portion top surface, at least one substantially vertical sidewall, and a kinked interface that lies above, but not directly within, said at least one metallic interconnect embedded in said first dielectric layer, said at least one substantially vertical sidewall adjoins said kinked interface and said cylindrical portion top surface, said metal line has a top surface that is substantially at the same level over said at least one metal via as over an area outside said at least one metal via, and said cylindrical portion top surface abuts said metal line bottom surface;

at least one pair of liners having a liner bottom surface and located on at least vertical walls of said at least one aperture, wherein said liner bottom surface is located below said metallic interconnect top surface;

a patterned hard mask on said second dielectric layer; and

Cu filling said at least one aperture.