Mechanically robust metal/low-κ interconnects

• US 8,017,522 B2
• Filed: 01/24/2007
• Issued: 09/13/2011
• Est. Priority Date: 01/24/2007
• Status: Expired due to Fees

• Current Assignee: GlobalFoundries, Inc.
• Original Assignee: International Business Machines Corporation
• Inventors: Spooner, Terry A., Gandhi, Darshan D., Lin, Qinghuang, Tyberg, Christy S.
• Primary Examiner(s): Nguyen; Dao H
• Application Number:
  US11/626,550
• Publication Number:
  US 20080173984A1
• Time in Patent Office: 1,693 Days
• Field of Search: 438/622, 438/624, 438/627, 438/675, 438/687, 438/700, 257/753, 257/759, 257/760, 257/E21.241, 257/E21.261, 257/E21.277, 257/E21.576
• US Class Current: 438/687
• 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 dielectric layers comprising:

treating an upper surface region of a previously formed dielectric-containing substrate in the absence of a precursor used in forming the dielectric-containing substrate and at room temperature to form a treated surface layer only within the upper surface region of the dielectric-containing substrate that is physically and chemically different from a remaining portion of said dielectric-containing substrate that is not subjected to said treating; and

forming in a separate step from said treating a low-k dielectric layer having a dielectric constant of less than 4.0 on said treated surface 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 a plasma, said plasma comprises a surface pretreatment gas selected from the group consisting of an inert gas, H₂, O₂, NH₃, SiH₄ and mixtures thereof.

4. 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.

5. The method of claim 1 wherein said dielectric-containing substrate comprises a dielectric capping layer having a different composition than said low-k dielectric layer.

6. The method of claim 5 wherein said dielectric capping layer 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.

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

8. The method of claim 1 wherein said dielectric-containing substrate is formed by PECVD or spin-coating.

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

10. The method of claim 1 wherein the treated surface layer and said low-k dielectric layer 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 said interface.

11. 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 upper surface of said interconnect level;

treating an upper surface region of the previously formed dielectric capping layer in the absence of a precursor used in forming the dielectric capping layer and at room temperature to form a treated surface layer only within the upper surface region of dielectric capping layer that is physically and chemically different from a remaining portion of said dielectric capping layer that is not subjected to said treating; and

forming in a separate step from said treating a low-k dielectric layer having a dielectric constant of less than 4.0 on said treated surface layer.

12. The method in claim 11 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.

13. The method of claim 11 wherein said treating comprises a plasma, said plasma comprises a surface pretreatment gas selected from the group consisting of an inert gas, H₂, O₂, NH₃, SiH₄ and mixtures thereof.

14. The method of claim 11 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.

15. The method of claim 11 wherein the treated surface layer and said low-k dielectric layer 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 said interface.