METHOD FOR FABRICATING LAST LEVEL COPPER-TO-C4 CONNECTIONWITH INTERFACIAL CAP STRUCTURE

• US 20070166992A1
• Filed: 01/18/2006
• Published: 07/19/2007
• Est. Priority Date: 01/18/2006
• Status: Active Grant

• Current Assignee: GlobalFoundries, Inc.
• Original Assignee: International Business Machines Corporation
• Inventors: Daubenspeck, Timothy H., Landers, William F., Zupanski-Nielsen, Donna S.
• Granted Patent: US 7,863,183 B2
• Time in Patent Office: Days
• US Class Current: 438/613
• CPC Class Codes: H01L 21/288 from a liquid, e.g. electrolytic deposition
• CPC Class Codes: H01L 2224/03009 for protecting parts during manufacture
• CPC Class Codes: H01L 2224/0401 Bonding areas specifically adapted for bump connectors, e.g. under bump metallisation [UBM]
• CPC Class Codes: H01L 2224/05147 Copper [Cu] as principal constituent
• CPC Class Codes: H01L 2224/05575 Plural external layers
• CPC Class Codes: H01L 2224/05599 Material
• CPC Class Codes: H01L 2224/1148 Permanent masks, i.e. masks left in the finished device, e.g. passivation layers
• CPC Class Codes: H01L 2224/13007 Bump connector smaller than the underlying bonding area, e.g. than the under bump metallisation [UBM]
• CPC Class Codes: H01L 2224/13022 the bump connector being at least partially embedded in the surface
• CPC Class Codes: H01L 2224/13111 Tin [Sn] as principal constituent
• CPC Class Codes: H01L 23/3192 Multilayer coating
• CPC Class Codes: H01L 24/03 Manufacturing methods
• CPC Class Codes: H01L 24/05 of an individual bonding area
• CPC Class Codes: H01L 24/11 Manufacturing methods for bumps on insulating substrates H01L21/4853
• CPC Class Codes: H01L 24/13 of an individual bump connector
• CPC Class Codes: H01L 2924/00014 the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed without further technical details
• CPC Class Codes: H01L 2924/01004 Beryllium [Be]
• CPC Class Codes: H01L 2924/01005 Boron [B]
• CPC Class Codes: H01L 2924/01006 Carbon [C]
• CPC Class Codes: H01L 2924/01013 Aluminum [Al]
• CPC Class Codes: H01L 2924/01015 : Phosphorus [P]
• CPC Class Codes: H01L 2924/01029 : Copper [Cu]
• CPC Class Codes: H01L 2924/01033 : Arsenic [As]
• CPC Class Codes: H01L 2924/01042 : Molybdenum [Mo]
• CPC Class Codes: H01L 2924/01073 : Tantalum [Ta]
• CPC Class Codes: H01L 2924/01074 : Tungsten [W]
• CPC Class Codes: H01L 2924/01075 : Rhenium [Re]
• CPC Class Codes: H01L 2924/01078 : Platinum [Pt]
• CPC Class Codes: H01L 2924/01082 : Lead [Pb]
• CPC Class Codes: H01L 2924/01327 : Intermediate phases, i.e. intermetallics compounds
• CPC Class Codes: H01L 2924/014 : Solder alloys
• CPC Class Codes: H01L 2924/04941 : TiN
• CPC Class Codes: H01L 2924/14 : Integrated circuits
• CPC Class Codes: H01L 2924/19041 : being a capacitor
• CPC Class Codes: H01L 2924/19042 : being an inductor
• CPC Class Codes: H01L 2924/19043 : being a resistor

Abstract

The present invention relates to a method for fabricating a semiconductor device with a last level copper-to-C4 connection that is essentially free of aluminum. Specifically, the last level copper-to-C4 connection comprises an interfacial cap structure containing CoWP, NiMoP, NiMoB, NiReP, NiWP, and combinations thereof. Preferably, the interfacial cap structure comprises at least one CoWP layer. Such a CoWP layer can be readily formed over a last level copper interconnect by a selective electroless plating process.

Claims

1. A method comprising:

providing a semiconductor device that comprises a last level copper interconnect embedded in a last level dielectric layer;

forming an interfacial conductive cap structure that selectively covers the last level copper interconnect, wherein said interfacial conductive cap structure comprises CoWP, NiMoP, NiMoB, NiReP, NiWP, or combinations thereof;

forming a first dielectric cap layer over the interfacial conductive cap structure and the last level dielectric layer;

forming at least one additional dielectric cap layer over the first dielectric cap layer;

forming a via through the first dielectric cap layer and the at least one additional dielectric cap layer to expose the interfacial conductive cap structure;

forming at least one ball-limiting metallurgy (BLM) layer in the via over the interfacial conductive cap structure; and

forming at least one controlled-collapse chip connection (C4) over the at least one BLM layer.

2. The method of claim 1, wherein the interfacial conductive cap structure is essentially free of aluminum.

3. The method of claim 1, wherein the interfacial conductive cap structure comprises a CoWP layer having a thickness ranging from about 200 Å

to about 1000 Å

.

4. The method of claim 1, wherein the interfacial conductive cap structure is embedded in the first dielectric cap layer.

5. The method of claim 1, wherein the first dielectric cap layer comprises silicon nitride and has a thickness ranging from about 100 Å

to about 300 Å

.

6. The method of claim 1, wherein the last level copper interconnect, the interfacial conductive cap structure, the at least one BLM layer, and the at least one C4 connection form an electrically conductive path that extends through the first dielectric cap layer and the at least one additional dielectric cap layer.

7. The method of claim 1, wherein at least three additional dielectric cap layers are formed over the first dielectric cap layer, which include a silicon dioxide layer, a silicon nitride layer, and a photosensitive polyimide layer.

8. The method of claim 1, wherein the last level copper interconnect comprises a fat wire.

9. The method of claim 1, wherein the last level dielectric layer comprises fluorinated silica glass.

10. The method of claim 1, wherein the interfacial conductive cap structure is formed by selective electroless plating.

11. The method of claim 1, wherein the via is formed by first selectively removing a portion of the at least one additional dielectric cap layer to expose the first dielectric cap layer, and then selectively removing the exposed portion of the first dielectric cap layer, stopping at the interfacial conductive cap structure.

12. The method of claim 11, wherein the portion of the first dielectric cap layer is selectively removed by a pre-BLM sputter clean process.

13. A method comprising:

providing a semiconductor device that comprises a last level copper interconnect embedded in a last level dielectric layer;

forming an interfacial conductive cap structure that selectively covers the last level copper interconnect;

forming a first dielectric cap layer over the interfacial conductive cap structure and the last level dielectric layer;

forming at least one additional dielectric cap layer over the first dielectric cap layer;

selectively removing a portion of said at least one additional dielectric cap layer to expose the first dielectric cap layer;

conducting in situ sputter cleaning, which selectively removes the exposed portion of the first dielectric cap layer, stopping at the at least one additional dielectric cap layer;

forming at least one ball-limiting metallurgy (BLM) layer over the interfacial conductive cap structure; and

forming at least one controlled-collapse chip connection (C4) over the at least one BLM layer.

14. The method of claim 13, wherein the interfacial conductive cap structure is formed by selective electroless plating.

15. The method of claim 13, wherein the interfacial conductive cap structure is essentially free of aluminum.

16. The method of claim 13, wherein the interfacial conductive cap structure comprises a CoWP layer having a thickness ranging from about 200 Å

to about 1000 Å

.

17. The method of claim 13, wherein the first dielectric cap layer comprises silicon nitride and has a thickness ranging from about 100 Å

to about 300 Å

.

18. The method of claim 13, wherein the last level copper interconnect, the interfacial conductive cap structure, the at least one BLM layer, and the at least one C4 connection form an electrically conductive path that extends through the first dielectric cap layer and the at least one additional dielectric cap layer.

19. The method of claim 13, wherein at least three additional dielectric cap layers are formed over the first dielectric cap layer, which include a silicon dioxide layer, a silicon nitride layer, and a photosensitive polyimide layer.