HIGH ASPECT RATIO ELECTROPLATED METAL FEATURE AND METHOD

• US 20090148677A1
• Filed: 12/10/2007
• Published: 06/11/2009
• Est. Priority Date: 12/10/2007
• Status: Active Grant

• Current Assignee: GlobalFoundries, Inc.
• Original Assignee: International Business Machines Corporation
• Inventors: Wong, Keith Kwong Hon, Yang, Chih-Chao, Yang, Haining S., Edelstein, Daniel C.
• Granted Patent: US 7,727,890 B2
• Time in Patent Office: Days
• US Class Current: 428/209
• CPC Class Codes: C25D 5/02 Electroplating of selected surface areas
• CPC Class Codes: Y10T 428/24331 including nonapertured component
• CPC Class Codes: Y10T 428/24917 including metal layer

Abstract

Disclosed are embodiments of an improved high aspect ratio electroplated metal structure (e.g., a copper or copper alloy interconnect, such as a back end of the line (BEOL) or middle of the line (MOL) contact) in which the electroplated metal fill material is free from seams and/or voids. Also, disclosed are embodiments of a method of forming such an electroplated metal structure by lining a high aspect ratio opening (e.g., a high aspect ratio via or trench) with a metal-plating seed layer and, then, forming a protective layer over the portion of the metal-plating seed layer adjacent to the opening sidewalls so that subsequent electroplating occurs only from the bottom surface of the opening up.

Claims

1. A metal structure comprising:

a substrate;

a dielectric layer adjacent said substrate;

an opening extending through said dielectric layer to said substrate, wherein said opening has sidewalls and a bottom surface;

a metal-plating seed layer lining said opening and comprising a first portion adjacent said sidewalls and a second portion adjacent said bottom surface;

a protective layer adjacent said first portion of said metal-plating seed layer; and

an electroplated layer comprising one of a metal and a metal alloy adjacent said protective layer and said second portion of said metal-plating seed layer, wherein said electroplated layer fills said opening.

2. The metal structure of claim 1, all the limitations of which are incorporated herein by reference, wherein an aspect ratio of said opening is greater than approximately 6:

1.

3. The metal structure of claim 1, all the limitations of which are incorporated herein by reference, wherein said metal-plating seed layer is adapted to promote electroplating of said one of said metal and said metal alloy.

4. The metal structure of claim 1, all the limitations of which are incorporated herein by reference, wherein said protective layer comprises one of an additional metal layer and an additional dielectric layer adapted to selectively prevent electroplating of said one of said metal and said metal alloy.

5. The metal structure of claim 1, all the limitations of which are incorporated herein by reference, further comprising a barrier layer lining said opening between said metal-plating seed layer and said dielectric layer.

6. An interconnect structure comprising:

a substrate;

a dielectric layer adjacent said substrate;

an opening extending through said dielectric layer to said substrate, wherein said opening has sidewalls and a bottom surface;

a copper-plating seed layer lining said opening and comprising a first portion adjacent said sidewalls and a second portion adjacent said bottom surface;

a protective layer adjacent said first portion of said copper-plating seed layer; and

an electroplated layer comprising one of copper and a copper alloy adjacent said protective layer and said second portion of said copper-plating seed layer, wherein said electroplated layer fills said opening.

7. The interconnect structure of claim 6, all the limitations of which are incorporated herein by reference, wherein an aspect ratio of said opening is greater than approximately 6:

1.

8. The interconnect structure of claim 6, all the limitations of which are incorporated herein by reference, wherein said protective layer is adapted to selectively prevent electroplating of said one of said copper and said copper alloy.

9. The interconnect structure of claim 6, all the limitations of which are incorporated herein by reference, wherein said protective layer comprises an additional metal layer having a copper-plating over-potential sufficient to prevent electroplating of said one of said copper and said copper alloy.

10. The interconnect structure of claim 9, all the limitations of which are incorporated herein by reference, wherein said additional metal layer comprises one of tantalum, tungsten, titanium, and chromium.

11. The interconnect structure of claim 6, all the limitations of which are incorporated herein by reference, wherein said protective layer comprises an additional dielectric layer having a copper-plating over-potential sufficient to prevent electroplating of said one of said copper and said copper alloy.

12. The interconnect structure of claim 6, all the limitations of which are incorporated herein by reference, further comprising a barrier layer lining said opening between said copper-plating seed layer and said dielectric layer.

13. An interconnect structure comprising:

a substrate;

a dielectric layer adjacent said substrate;

an opening extending through said dielectric layer to said substrate, wherein said opening has sidewalls and a bottom surface;

a barrier layer lining said opening;

an adhesion layer lining said opening above said barrier layer;

a copper-plating seed layer lining said opening above said adhesion layer, wherein said copper-plating seed layer comprises a first portion adjacent said sidewalls and a second portion adjacent said bottom surface;

a protective layer adjacent said first portion of said copper-plating seed layer; and

an electroplated layer comprising one of copper and a copper alloy adjacent said protective layer and said second portion of said copper-plating seed layer, wherein said electroplated layer fills said opening and is free from seams and voids.

14. A method of forming a metal structure comprising:

forming an opening through a dielectric layer to a substrate;

lining said opening with a metal-plating seed layer;

forming a protective layer on said metal-plating seed layer;

removing said protective layer from a bottom surface of said opening; and

performing an electroplating process to fill said opening with an electroplated layer comprising one of a metal and a metal alloy,

wherein said protective layer on sidewalls of said opening prevents electroplating of said one of said metal and said metal alloy, and an exposed portion of said metal-plating seed layer at said bottom surface of said opening promotes electroplating of said one of said metal and said metal alloy such that said electroplating process fills said opening with said electroplated layer from said bottom surface up.

15. The method of claim 14, all the limitations of which are incorporated herein by reference, further comprising:

providing said substrate;

forming said dielectric layer on said substrate such that said dielectric layer has a predetermined thickness; and

patterning said opening in said dielectric layer such that an aspect ratio of said opening is greater than approximately 6;

1.

16. The method of claim 14, all the limitations of which are incorporated herein by reference, wherein said forming of said protective layer comprises depositing a conformal additional metal layer over said metal-plating seed layer, wherein said additional metal layer is pre-selected to selectively prevent electroplating of said one of said metal and said metal alloy.

17. The method of claim 14, all the limitations of which are incorporated herein by reference, wherein said forming of said protective layer comprises depositing a conformal additional dielectric layer, wherein said additional dielectric layer is pre-selected to selectively prevent electroplating of said one of said metal and said metal alloy.

18. The method of claim 14, all the limitations of which are incorporated herein by reference, wherein said removing of said protective layer from said bottom surface of said opening comprises performing a directional etch process.

19. A method of forming an interconnect structure, said method comprising:

forming an opening through a dielectric layer to a substrate;

lining said opening with a copper-plating seed layer;

forming a protective layer on said copper-plating seed layer;

removing said protective layer from a bottom surface of said opening; and

performing an electroplating process to fill said opening with an electroplated layer comprising one of copper and a copper alloy,

wherein said protective layer on sidewalls of said opening prevents electroplating of said one of said copper and said copper alloy, and an exposed portion of said copper-plating seed layer at said bottom surface of said opening promotes electroplating of said one of said copper and said copper alloy such that said electroplating process fills with said opening with said electroplated layer from said bottom surface up.

20. The method of claim 19, all the limitations of which are incorporated herein by reference, further comprising:

providing said substrate;

forming said dielectric layer on said substrate such that said dielectric layer has a predetermined thickness; and

patterning said opening in said dielectric layer such that an aspect ratio of said opening is greater than approximately 6;

1.

21. The method of claim 19, all the limitations of which are incorporated herein by reference, wherein said forming of said protective layer comprises depositing a conformal layer of one of a metal and a metal alloy having a copper-plating over-potential sufficient to selectively prevent electroplating of said one of said copper and said copper alloy

22. The method of claim 21, all the limitations of which are incorporated herein by reference, wherein said metal comprises one of tantalum, tungsten, titanium, and chromium.

23. The method of claim 19, all the limitations of which are incorporated herein by reference, wherein said forming of said protective layer comprises depositing a conformal layer of a dielectric having a copper-plating over-potential sufficient to selectively prevent electroplating of said one of said copper and said copper alloy.

24. The method of claim 19, all the limitations of which are incorporated herein by reference, wherein said removing of said protective layer from said bottom surface of said opening comprises performing a directional etch process.

25. The method of claim 19, all the limitations of which are incorporated herein by reference, wherein said performing of said electroplating process comprises using a copper-plating chemistry with additives to promote super-filling of said opening with said electroplated layer.