Fabrication of semiconductor interconnect structure

• US 7,531,463 B2
• Filed: 10/24/2006
• Issued: 05/12/2009
• Est. Priority Date: 10/20/2003
• Status: Expired due to Fees

• Current Assignee: Novellus Systems Incorporated (Lam Research Corporation)
• Original Assignee: Novellus Systems Incorporated (Lam Research Corporation)
• Inventors: Mountsier, Thomas, Cleary, Timothy Patrick, Park, Heung L., Mayer, Steven T., Koos, Daniel A.
• Primary Examiner(s): Vinh; Lan
• Application Number:
  US11/586,394
• Publication Number:
  US 20070105377A1
• Time in Patent Office: 931 Days
• Field of Search: 438/692, 438/693, 438/745, 438/750, 438/641, 438/678, 438/754, 438/751, 438/753, 438/752, 216/102, 216/106
• US Class Current: 438/754
• CPC Class Codes: C23C 18/1608 from pretreatment step, i.e. selective pre-treatment
• CPC Class Codes: C23C 18/1689 After-treatment
• CPC Class Codes: C23C 18/1692 Heat-treatment
• CPC Class Codes: C23C 18/1696 Control of atmosphere
• CPC Class Codes: C23C 18/1893 with use of organic or inorganic compounds other than metals, first
• CPC Class Codes: C23F 1/18 for etching copper or alloys thereof
• CPC Class Codes: C23F 1/34 for etching copper or alloys thereof
• CPC Class Codes: H01L 21/288 from a liquid, e.g. electrolytic deposition
• CPC Class Codes: H01L 21/32134 by liquid etching only
• CPC Class Codes: H01L 21/76849 the layer being positioned on top of the main fill metal
• CPC Class Codes: H01L 21/76856 by treatment in plasmas or gaseous environments, e.g. nitriding a refractory metal liner
• CPC Class Codes: H01L 21/76858 by diffusing alloying elements
• CPC Class Codes: H01L 21/76883 Post-treatment or after-treatment of the conductive material
• CPC Class Codes: H01L 23/53238 Additional layers associated with copper layers, e.g. adhesion, barrier, cladding layers
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00

Abstract

An etching process for selectively etching exposed metal surfaces of a substrate and forming a conductive capping layer over the metal surfaces is described. In some embodiments, the etching process involves oxidation of the exposed metal to form a metal oxide that is subsequently removed from the surface of the substrate. The exposed metal may be oxidized by using solutions containing oxidizing agents such as peroxides or by using oxidizing gases such as those containing oxygen or ozone. The metal oxide produced is then removed using suitable metal oxide etching agents such as glycine. The oxidation and etching may occur in the same solution. In other embodiments, the exposed metal is directly etched without forming a metal oxide. Suitable direct metal etching agents include any number of acidic solutions. The process allows for controlled oxidation and/or etching with reduced pitting. After the metal regions are etched and recessed in the substrate surface, a conductive capping layer is formed using electroless deposition over the recessed exposed metal regions.

Claims

1. A method of etching metal portions of a substrate containing a layer of metal and dielectric, the method comprising:

receiving the substrate containing the layer of metal and dielectric, wherein the substrate comprises metal overburden covering dielectric field regions;

at least partially completing planarization of the overburden; and

etching to remove at least a portion of metal remaining exposed on the substrate after planarization by contacting the substrate with a wet etching composition at a pH in a range of between about 5 and 12, the wet etching composition consisting essentially of (i) a complexing agent for ions of the metal, wherein the complexing agent is an aminoacid;

(ii) an oxidizer selected from the group consisting of peroxides, permanganates, persulfates, and ozone solution, and (iii) water, wherein the etching composition is a solution, and wherein the etching is accomplished by contacting at least the metal with said solution, wherein the contacting comprises at least one of immersing, spraying, dipping, spin on contact, and using a thin film reactor.

2. The method of claim 1, wherein the aminoacid is glycine.

3. The method of claim 1, wherein the oxidizer is hydrogen peroxide.

4. The method of claim 1, wherein the etching solution has a pH in a range of between about 6 and 10.

5. The method of claim 1, wherein the metal is copper.

6. The method of claim 1, wherein the planarization is chemical mechanical polishing.

7. The method of claim 1, wherein the planarization is an electroplanarization technique.

8. The method of claim 1, wherein said etching removes metal from a metal line and creates a recess in said line of about 5-50 nm below the dielectric field region.

9. The method of claim 1, further comprising forming a capping layer on the etched metal portions of the substrate.

10. The method of claim 9, wherein said etching removes metal from a metal line and creates a recess in said line of about 5-50 nm below the dielectric field region, prior to forming the capping layer.

11. A method of etching metal portions of a substrate containing a layer of metal and dielectric, the method comprising:

receiving the substrate containing the layer of metal and dielectric, wherein substrate comprises metal overburden covering dielectric field regions; and

etching to remove at least a portion of the overburden on the substrate by contacting the substrate with a wet etching composition at a pH in a range of between about 5 and 12, the wet etching composition consisting essentially of (i) a complexing agent for ions of the metal, wherein the complexing agent is an aminoacid, (ii) an oxidizer selected from the group consisting of peroxides, permanganates, persulfates, and ozone solution, and (iii) water, wherein the etching composition is a solution, and wherein the etching is accomplished by contacting at least the metal with said solution, wherein the contacting comprises at least one of immersing, spraying, dipping, spin on contact, and using a thin film reactor.

12. The method of claim 11, wherein the aminoacid is glycine.

13. The method of claim 11, wherein the metal is copper.

14. The method of claim 11, wherein the etching solution has a pH in a range of between about 6 and 10.

15. The method of claim 11, wherein the oxidizer is hydrogen peroxide.

16. The method of claim 11, wherein said etching removes metal from a metal line and creates a recess in said line of about 5-50 nm below the dielectric field region.

17. The method of claim 11, further comprising forming a capping layer on the etched metal portions of the substrate.

18. The method of claim 17, wherein said etching removes metal from a metal line and creates a recess in said line of about 5-50 nm below the dielectric field region, prior to forming the capping layer.

19. A method of etching metal portions of a substrate containing a layer of metal and dielectric, the method comprising:

receiving the substrate containing the layer of metal and dielectric, wherein substrate comprises metal overburden covering dielectric field regions; and

etching to remove at least a portion of the overburden on the substrate by contacting the substrate with a wet etching composition at a pH in a range of between about 5 and 12, the wet etching composition consisting essentially of (i) a complexing agent for ions of the metal, wherein the complexing agent is an aminoacid, (ii) an oxidizer selected from the group consisting of peroxides, permanganates, persulfates, and ozone solution, (iii) a pH adjustor and (iv) water, wherein the etching composition is a solution, and wherein the etching is accomplished by contacting at least the metal with said solution, wherein the contacting comprises at least one of immersing, spraying, dipping, spin on contact, and using a thin film reactor.

20. The method of claim 19, wherein the metal is copper.

21. The method of claim 19, wherein the aminoacid is glycine.

22. The method of claim 19, wherein the oxidizer is hydrogen peroxide.

23. The method of claim 22, wherein the pH adjustor is selected from the group consisting of tetra-alkyl ammonium hydroxide, alkali metal hydroxide, an acetate, a carbonate, and a phosphate.

24. The method of claim 19, wherein said etching removes metal from a metal line and creates a recess in said line of about 5-50 nm below the dielectric field region.

25. The method of claim 24, further comprising forming a capping layer on the etched metal portions of the substrate.

26. A method of etching metal portions of a substrate containing a layer of metal and dielectric, the method comprising:

receiving the substrate containing the layer of metal and dielectric, wherein the substrate comprises metal overburden covering dielectric field regions;

at least partially completing planarization of the overburden by chemical mechanical polishing (CMP) or electroplanarization; and

using a wet etching method different from CMP and electroplanarization, to remove at least a portion of metal remaining exposed on the substrate after planarization by contacting the substrate with a wet etching solution at a pH in a range of between about 5 and 12and comprising (i) a complexing agent for ions of the metal, wherein the complexing agent is an aminoacid; and

(ii) an oxidizer selected from the group consisting of peroxides, permanganates, persulfates, and ozone solution, wherein the etching composition is a solution, and wherein the etching is accomplished by contacting at least the metal with the etching solution, wherein the contacting comprises at least one of immersing, spraying, dipping, spin on contact, and using a thin film reactor.

27. The method of claim 26, wherein the aminoacid is glycine.

28. The method of claim 26, wherein the oxidizer is hydrogen peroxide.

29. The method of claim 26, wherein said etching removes metal from a metal line and creates a recess in said line of about 5-50 nm below the dielectric field region.

30. The method of claim 29, further comprising forming a capping layer on the etched metal portions of the substrate.