Mechanically robust metal/low-k interconnects

• US 8,445,377 B2
• Filed: 09/09/2011
• Issued: 05/21/2013
• Est. Priority Date: 01/24/2007
• Status: Active Grant

• Current Assignee: Taiwan Semiconductor Manufacturing Company Limited
• Original Assignee: International Business Machines Corporation
• Inventors: Lin, Qinghuang, Spooner, Terry A., Gandhi, Darshan D., Tyberg, Christy S.
• Primary Examiner(s): Nguyen, Dao H
• Application Number:
  US13/229,250
• Publication Number:
  US 20110318942A1
• Time in Patent Office: 620 Days
• Field of Search: 438/622, 438/623, 438/624, 438/627, 438/675, 438/687, 257/753, 257/759, 257/760, 257/E21.54, 257/E21.241, 257/E21.261, 257/E21.277, 257/E21.576
• US Class Current: 438/624
• CPC Class Codes: H01L 21/3105 After-treatment
• CPC Class Codes: H01L 21/76805 the opening being a via or contact hole penetrating the underlying conductor
• CPC Class Codes: H01L 21/76825 by exposing the layer to particle radiation, e.g. ion implantation, irradiation with UV light or electrons etc. plasma treatment H01L21/76826
• CPC Class Codes: H01L 21/76826 by contacting the layer with gases, liquids or plasmas
• CPC Class Codes: H01L 21/76834 formation of thin insulating films on the sidewalls or on top of conductors H01L21/76831 takes precedence

Abstract

A mechanically robust semiconductor structure with improved adhesion strength between a low-k dielectric layer and a dielectric-containing substrate is provided. In particular, the present invention provides a structure that includes a dielectric-containing substrate having an upper region including a treated surface layer which is chemically and physically different from the substrate; and a low-k dielectric material located on a the treated surface layer of the substrate. The treated surface layer and the low-k dielectric material form an interface that has an adhesion strength that is greater than 60% of the cohesive strength of the weaker material on either side of the interface. The treated surface is formed by treating the surface of the substrate with at least one of actinic radiation, a plasma and e-beam radiation prior to forming of the substrate the low-k dielectric material.

Claims

1. A method for improving the adhesion strength between two different layers comprising:

forming a blanket layer of a dielectric capping material directly on an uppermost surface of an interconnect dielectric material and directly on an uppermost surface of at least one conductive feature embedded in said interconnect dielectric material;

treating an upper region of said blanket layer of dielectric capping material with at least one of actinic radiation and electron beam (e-beam) radiation to form a treated surface layer within said upper region of said blanket layer of dielectric capping material, said treated surface layer is located upon an untreated portion of said blanket layer of dielectric capping material, and is physically and chemically different from said untreated portion of said blanket layer of dielectric capping material, and said untreated portion of said blanket layer of dielectric capping material separates the treated surface layer within said upper region of said blanket layer of dielectric capping material from both said interconnect dielectric material and said at least one conductive feature; and

forming a low-k dielectric layer having a dielectric constant of less than 4.0 on said treated surface layer, wherein said treated surface layer remains as a permanent element in a semiconductor structure and is located between a remaining portion of the blanket layer of dielectric capping material and said low-k dielectric layer.

2. The method in claim 1 where said treating comprises actinic radiation, said actinic radiation includes a UV light of a wavelength in a range from about 10 to about 1000 nm, or X-ray radiation.

3. The method of claim 1 wherein said treating comprises e-beam radiation, said e-beam radiation is performed at an electron beam energy from about 0.1 to about 10,000 eV, a radiation time of about 10 sec to about 30 min and a temperature from room temperature to about 500°

C.

4. The method of claim 1 wherein said blanket layer of dielectric capping material has a different composition than said low-k dielectric layer.

5. The method of claim 4 wherein said blanket layer of dielectric capping material is selected from the group consisting of silicon oxide, silicon nitride, silicon oxynitride, SiC, Si₄NH₃, SiCH, a carbon doped oxide, a nitrogen and hydrogen doped silicon carbide SiC(N,H) and multilayers thereof.

6. The method of claim 1 wherein said low-k dielectric layer is selected from the group consisting of a silsesquioxane, a C doped oxide that includes atoms of Si, C, O and H, thermosetting polyarylene ethers, SiC, SiCH, SiCN, SiCHN, and multilayers thereof.

7. The method of claim 1 wherein said blanket layer of dielectric capping material is formed by PECVD or spin-coating.

8. The method of claim 1 wherein said forming said low-k dielectric layer comprises a deposition step followed by a curing step.

9. The method of claim 1 wherein said treating further comprises plasma treatment in conjunction with one of said actinic radiation and electron beam radiation.

10. The method of claim 1 wherein only actinic radiation is employed in said treating the upper region of the blanket layer of dielectric capping material.

11. The method of claim 1 wherein only electron beam radiation is employed in said treating the upper region of the blanket layer of dielectric capping material.

12. The method of claim 1 wherein a combination of both actinic radiation and electron beam radiation is employed in said treating the upper region of the blanket layer of dielectric capping material.

13. The method of claim 1 wherein said blanket layer of dielectric capping material spans an entirety of an interconnect level containing said interconnect dielectric material and said at least one conductive feature.

14. A method of forming an interconnect structure comprising:

providing an interconnect level having at least one conductive feature embedded within a dielectric material;

forming a dielectric capping layer on an uppermost surface of both said dielectric material and said at least one conductive feature of said interconnect level; and

treating an upper region of the dielectric capping layer with at least one of actinic radiation and electron beam (e-beam) radiation to form a treated surface layer within said upper region of the dielectric capping layer, said treated surface layer is located upon an untreated portion of said dielectric capping layer, and is physically and chemically different from said untreated portion of said dielectric capping layer, wherein said treated surface layer remains as a permanent element in said interconnect structure and is located between a remaining portion of said dielectric capping layer and both said dielectric material and said at least one conductive feature of said interconnect level.

15. The method in claim 14 where said treating comprises actinic radiation, said actinic radiation includes a UV light of a wavelength in a range from about 10 to about 1000 nm, or X-ray radiation.

16. The method of claim 14 wherein said treating comprises e-beam radiation, said e-beam radiation is performed at an electron beam energy from about 0.1 to about 10,000 eV, a radiation time of about 10 sec to about 30 min and a temperature from room temperature to about 500°

C.

17. The method of claim 14 wherein said treating further comprises plasma treatment in conjunction with one of said actinic radiation and electron beam radiation.

18. The method of claim 14 wherein only actinic radiation is employed in said treating the upper region of the dielectric capping layer.

19. The method of claim 14 wherein only electron beam radiation is employed in said treating the upper region of the dielectric capping layer.

20. The method of claim 14 wherein a combination of both actinic radiation and electron beam radiation is employed in said treating the upper region of the dielectric capping layer.