MECHANISMS FOR FORMING COPPER PILLAR BUMPS

• US 20110101527A1
• Filed: 07/29/2010
• Published: 05/05/2011
• Est. Priority Date: 11/05/2009
• Status: Active Grant

• Current Assignee: Taiwan Semiconductor Manufacturing Company Limited
• Original Assignee: Taiwan Semiconductor Manufacturing Company Limited
• Inventors: CHANG, Chia-Tung, CHENG, Ming-Da, CHEN, Ching-Wen, LU, Wen-Hsiung, LIN, Chih-Wei, LIU, Chung-Shi, WU, Yi-Wen, HO, Ming-Che
• Granted Patent: US 8,659,155 B2
• Time in Patent Office: Days
• US Class Current: 257/738
• CPC Class Codes: H01L 2224/0345 Physical vapour deposition [PVD], e.g. evaporation, or sputtering
• CPC Class Codes: H01L 2224/03912 the bump being used as a mask for patterning the bonding area
• CPC Class Codes: H01L 2224/0401 Bonding areas specifically adapted for bump connectors, e.g. under bump metallisation [UBM]
• CPC Class Codes: H01L 2224/05027 the internal layer extending out of an opening
• CPC Class Codes: H01L 2224/05099 Material
• CPC Class Codes: H01L 2224/05166 Titanium [Ti] as principal constituent
• CPC Class Codes: H01L 2224/05181 Tantalum [Ta] as principal constituent
• CPC Class Codes: H01L 2224/05186 with a principal constituent of the material being a non metallic, non metalloid inorganic material
• CPC Class Codes: H01L 2224/05552 in top view
• CPC Class Codes: H01L 2224/05572 the external layer extending out of an opening
• CPC Class Codes: H01L 2224/05599 Material
• CPC Class Codes: H01L 2224/05647 Copper [Cu] as principal constituent
• CPC Class Codes: H01L 2224/10145 Flow barriers
• CPC Class Codes: H01L 2224/1145 Physical vapour deposition [PVD], e.g. evaporation, or sputtering
• CPC Class Codes: H01L 2224/11452 Chemical vapour deposition [CVD], e.g. laser CVD
• CPC Class Codes: H01L 2224/1146 Plating
• CPC Class Codes: H01L 2224/1147 using a lift-off mask
• CPC Class Codes: H01L 2224/11827 Chemical vapour deposition [CVD], e.g. laser CVD
• CPC Class Codes: H01L 2224/13006 Bump connector larger than the underlying bonding area, e.g. than the under bump metallisation [UBM]
• CPC Class Codes: H01L 2224/1308 being stacked
• CPC Class Codes: H01L 2224/13082 : Two-layer arrangements
• CPC Class Codes: H01L 2224/13083 : Three-layer arrangements
• CPC Class Codes: H01L 2224/13099 : Material
• CPC Class Codes: H01L 2224/13111 : Tin [Sn] as principal constituent
• CPC Class Codes: H01L 2224/13147 : Copper [Cu] as principal constituent
• CPC Class Codes: H01L 2224/13599 : Material
• CPC Class Codes: H01L 2224/13647 : Copper [Cu] as principal constituent
• CPC Class Codes: H01L 2224/16225 : the item being non-metallic, e.g. insulating substrate with or without metallisation
• CPC Class Codes: H01L 2224/16227 : the bump connector connecting to a bond pad of the item
• CPC Class Codes: H01L 2224/16507 : comprising an intermetallic compound
• CPC Class Codes: H01L 2224/29099 : Material
• CPC Class Codes: H01L 2224/29599 : Material
• CPC Class Codes: H01L 2224/81191 : wherein the bump connectors are disposed only on the semiconductor or solid-state body
• CPC Class Codes: H01L 2224/81815 : Reflow soldering
• 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 24/16 : of an individual bump connector
• 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 2924/00012 : Relevant to the scope of the group, the symbol of which is combined with the symbol of this group
• CPC Class Codes: H01L 2924/00013 : Fully indexed content
• 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 2924/0002 : Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00
• CPC Class Codes: H01L 2924/01005 : Boron [B]
• CPC Class Codes: H01L 2924/01006 : Carbon [C]
• CPC Class Codes: H01L 2924/01012 : Magnesium [Mg]
• CPC Class Codes: H01L 2924/01013 : Aluminum [Al]
• CPC Class Codes: H01L 2924/01015 : Phosphorus [P]
• CPC Class Codes: H01L 2924/01019 : Potassium [K]
• CPC Class Codes: H01L 2924/01022 : Titanium [Ti]
• CPC Class Codes: H01L 2924/01023 : Vanadium [V]
• CPC Class Codes: H01L 2924/01024 : Chromium [Cr]
• CPC Class Codes: H01L 2924/01025 : Manganese [Mn]
• CPC Class Codes: H01L 2924/01027 : Cobalt [Co]
• CPC Class Codes: H01L 2924/01029 : Copper [Cu]
• CPC Class Codes: H01L 2924/0103 : Zinc [Zn]
• CPC Class Codes: H01L 2924/01032 : Germanium [Ge]
• CPC Class Codes: H01L 2924/01033 : Arsenic [As]
• CPC Class Codes: H01L 2924/01038 : Strontium [Sr]
• CPC Class Codes: H01L 2924/0104 : Zirconium [Zr]
• CPC Class Codes: H01L 2924/01046 : Palladium [Pd]
• CPC Class Codes: H01L 2924/01047 : Silver [Ag]
• CPC Class Codes: H01L 2924/01049 : Indium [In]
• CPC Class Codes: H01L 2924/01051 : Antimony [Sb]
• CPC Class Codes: H01L 2924/01073 : Tantalum [Ta]
• CPC Class Codes: H01L 2924/01075 : Rhenium [Re]
• CPC Class Codes: H01L 2924/01078 : Platinum [Pt]
• CPC Class Codes: H01L 2924/01079 : Gold [Au]
• CPC Class Codes: H01L 2924/01082 : Lead [Pb]
• CPC Class Codes: H01L 2924/01083 : Bismuth [Bi]
• CPC Class Codes: H01L 2924/01322 : Eutectic Alloys, i.e. obtained by a liquid transforming into two solid phases
• 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 2924/04953 : TaN
• CPC Class Codes: H01L 2924/05 : 10th Group
• CPC Class Codes: H01L 2924/1305 : Bipolar Junction Transistor [BJT]
• CPC Class Codes: H01L 2924/1306 : Field-effect transistor [FET]
• CPC Class Codes: H01L 2924/13091 : Metal-Oxide-Semiconductor Field-Effect Transistor [MOSFET]
• CPC Class Codes: H01L 2924/14 : Integrated circuits
• CPC Class Codes: H01L 2924/19041 : being a capacitor
• CPC Class Codes: H01L 2924/3651 : Formation of intermetallics

Abstract

The mechanism of forming a metal bump structure described above resolves the delamination issues between a conductive layer on a substrate and a metal bump connected to the conductive layer. The conductive layer can be a metal pad, a post passivation interconnect (PPI) layer, or a top metal layer. By performing an in-situ deposition of a protective conductive layer over the conductive layer (or base conductive layer), the under bump metallurgy (UBM) layer of the metal bump adheres better to the conductive layer and reduces the occurrence of interfacial delamination. In some embodiments, a copper diffusion barrier sub-layer in the UBM layer can be removed. In some other embodiments, the UBM layer is not needed if the metal bump is deposited by a non-plating process and the metal bump is not made of copper.

Claims

1. A bump structure on a substrate, comprising:

a composite conductive layer on the substrate, wherein the composite conductive layer includes a protective conductive layer over a base conductive layer, and wherein the protective conductive layer and the base conductive layer are deposited in a system to prevent the oxidation of the base conductive layer, wherein the composite conductive layer is made of a material less likely to be oxidized in presence of air or water than a material for the base conductive layer;

a dielectric layer over the composite conductive layer;

a polymer layer over the dielectric layer; and

a metal bump, wherein the metal bump fills a second opening of a photoresist layer, wherein the second opening is formed above a first opening created in the polymer layer to make contact with the protective conductive layer of the composite conductive layer, and wherein the metal bump forms a strong bonding with the protective conductive layer.

2. The bump structure of claim 1, wherein an under bump metallurgy (UBM) layer lines a surface of the first opening and an interface between the polymer layer and the photoresist layer and wherein the UBM layer is part of the metal bump.

3. The bump structure of claim 2, wherein the metal bump includes a copper pillar formed by plating and the UBM layer includes a copper seed layer.

4. The bump structure of claim 2, wherein the metal bump includes a copper layer, a copper diffusion barrier, and a solder ball, and wherein the UBM layer includes a copper seed layer.

5. The bump structure of claim 1, wherein the metal bump includes a solder ball.

6. The bump structure of claim 1, wherein the protective conductive layer is made of a material selected from a group consisting of Ta, TaN, Ti, TiN, or combination thereof.

7. The bump structure of claim 1, wherein the protective conductive layer has a thickness in a range between about 1000 Å

to about 2,000 Å

.

8. The bump structure of claim 1, wherein base conductive layer is made of a material selected from a group consisting of copper, aluminum, and copper alloy.

9. The bump structure of claim 1, wherein the composite conductive layer is a metal pad a post passivation interconnect (PPI), or a top metal layer.

10. The bump structure of claim 1, wherein the polymer layer is made of a material selected from a group consisting of epoxy, polyimide, benzocyclobutene (BCB), or polybenzoxazole (PBO).

11. The bump structure of claim 10, wherein the polyimide is poly(4,4′

-oxydiphthalic anhydride-1,3-aminophenoxybenzene-8-azaadenine) (ODPA-APB-8-azaadenine).

12. The bump structure of claim 2, wherein the UBM layer includes a diffusion barrier layer and a copper seed layer.

13. The bump structure of claim 3, wherein the metal bump further includes a cap layer over the copper pillar, and a solder layer over the cap layer.

14. The bump structure of claim 13, wherein the copper pillar is made of copper or copper alloy, and wherein the cap layer is made of a material selected from a group consisting of nickel, tin, tin-lead, gold, silver, palladium, indium, nickel-palladium-gold, nickel-gold, or other types of alloys of above-mentioned materials, and wherein the solder layer is lead-free or contains lead.

15. A bump structure on a substrate, comprising:

a composite conductive layer on the substrate, wherein the composite conductive layer includes a protective conductive layer over a base conductive layer, and wherein the protective conductive layer and the base conductive layer are deposited in a system to prevent the oxidation of the base conductive layer, wherein the composite conductive layer is made of a material less likely to be oxidized in presence of air or water than a material for the base conductive layer;

a dielectric layer over the composite conductive layer;

a polymer layer over the dielectric layer;

a copper bump, wherein the copper bump fills a second opening of a photoresist layer, wherein the second opening is formed above a first opening created in the polymer layer to make contact with the protective conductive layer of the composite conductive layer, and wherein the copper bump includes an under bump metallurgy (UBM) layer lining a surface of the first opening and an interface between the polymer layer and the photoresist layer, and wherein the UBM layer forms a strong bonding with the protective conductive layer.

16. The bump structure of claim 15, wherein the UBM layer is a copper seed layer.

17. The bump structure of claim 15, wherein the protective conductive layer is made of a material selected from a group consisting of Ta, TaN, Ti, TiN, or combination thereof, and wherein the conductive protective layer has a thickness between about 1000 Å

to about 2,000 Å

.

18. The bump structure of claim 15, wherein base conductive metal layer is made of a material selected from a group consisting of copper, aluminum, and copper alloy.

19. A method of preparing a bump structure on a substrate, comprising:

forming a composite conductive layer on the substrate, wherein the composite conductive layer includes a base conductive layer and a protective conductive layer, and wherein the protective conductive layer is deposited right after the base conductive layer without exposing the substrate to air or water;

depositing a dielectric layer over the composite conductive layer;

depositing a polymer layer over the dielectric layer;

forming a first opening for a copper pillar bump by etching through the dielectric layer and the polymer layer;

depositing an under bump metallurgy (UBM) layer, wherein the UBM layer includes a copper seed layer;

forming a photoresist pattern on the substrate, wherein the photoresist has a second opening defined over the first opening; and

depositing a metal pillar bump layer, wherein both the UBM layer and the metal pillar bump layer are part of the bump structure.

20. The method of claim 19, further comprising:

performing a plasma surface treatment after the second opening is defined to treat an exposed surface of the polymer layer, wherein the plasma surface treatment increases the reactivity of the copper seed layer with the exposed surface of the polymer layer to cause crosslinking of polymers, and wherein the crosslinked polymers creates a barrier to copper diffusion.

21. The method of claim 20, wherein the plasma surface treatment utilizes a plasma containing oxygen, nitrogen, or both the above-mentioned gases.

22. The method of claim 19, wherein the polymer layer is made of a polyimide, and wherein the polyimide is poly(4,4′

-oxydiphthalic anhydride-1,3-aminophenoxybenzene-8-azaadenine) (ODPA-APB-8-azaadenine).

23. The method of claim 19, wherein protective conductive layer has a lower oxidation rate than the base conductive layer when exposed to air or water.

24. The method of claim 19, wherein protective conductive layer reduces delamination between the base conductive layer and the metal bump structure.