Lead-free tin alloy electroplating compositions and methods

Abstract

Disclosed are electrolyte compositions for depositing a tin alloy on a substrate. The electrolyte compositions include tin ions, ions of one or more alloying metals, a flavone compound and a dihydroxy bis-sulfide. The electrolyte compositions are free of lead and cyanide. Also disclosed are methods of depositing a tin alloy on a substrate and methods of forming an interconnect bump on a semiconductor device.

Description

technical field

[0001] The present invention relates to lead-free tin alloy electroplating compositions and methods. More particularly, the present invention relates to lead-free tin alloy electroplating compositions and methods that provide improved tin alloy deposition morphology, improved reflow performance, and the ability to deposit at high current densities. Background technique

[0002] Tin and tin-lead alloy deposits are useful in the electronics industry, particularly in the manufacture of printed wiring boards, electrical contacts and connections, semiconductors, electrical conduits, and other related components where the inherent properties of these deposits are highly desirable. Among various electronic applications, wafer level packaging (WLP) is currently concentrated in the semiconductor manufacturing industry. With wafer-level-packaging, the IC interconnections can be fabricated together on the wafer, and the entire IC module can be formed on the wafer befor...

Examples

Embodiment 1

[0053] An electrolyte composition was prepared by mixing 50 g / L tin from tin methanesulfonate, 0.4 g / L silver from silver methanesulfonate, 70 g / L methanesulfonic acid, 8 g / L 3 , 6-dithia-1,8-octanediol, 1 g / L ethyl maltol, 4 g / L ethoxylated bisphenol A (13 ethylene oxide units), 30 mg / L V Hydroxyflavone, 1 g / L hydroquinone monosulfonic acid potassium salt and deionized water (remainder) are mixed. A 4 x 4 cm wafer fragment with photoresist patterned vias on a copper seed, 120 microns in diameter and 50 microns deep, was dipped in the composition in a glass container at 6A / dm 2 Current density plating a layer of tin-silver.

[0054] With Hitachi S2460 TM The morphology of the formed tin-silver layer was examined by scanning electron microscopy. The deposit was uniform, smooth, dense and non-nodular.

[0055] The silver concentration of the tin-silver layer prepared by the sample was measured by the AAS method. The AAS equipment for the measurements was manufactured by V...

Embodiment 2

[0057] An electrolyte composition was prepared by mixing 50 g / L tin from tin methanesulfonate, 0.4 g / L silver from silver methanesulfonate, 70 g / L methanesulfonic acid, 1 g / L 3 , 6-dithia-1,8-octanediol, 1 g / L ethyl maltol, 4 g / L ethoxylated bisphenol A (13 ethylene oxide units), 10 mg / L V Hydroxyflavone, 1 g / L hydroquinone monosulfonic acid potassium salt and deionized water (remainder) are mixed. A 4 x 4 cm wafer segment with 120 micron diameter, 50 micron deep vias patterned with photoresist, a copper seed layer and 5 micron copper studs was immersed in the glass container. Composition, at 6A / dm 2 Current density plating a layer of tin-silver. After plating, the photoresist and exposed copper seed layer were removed using a Hitachi S2460 TM Scanning electron microscopy to examine the tin-silver layer. The deposit was uniform, smooth, dense and non-nodular.

[0058] The tin-silver layer was then reflowed to form bumps and the bumps were inspected with a WBI-Fox X-ray in...

Embodiment 3

[0061] An electrolyte composition was prepared by mixing 50 g / L tin from tin methanesulfonate, 0.4 g / L silver from silver methanesulfonate, 70 g / L methanesulfonic acid, 8 g / L 3 , 6-dithia-1,8-octanediol, 1 g / L ethyl maltol, 4 g / L ethoxylated bisphenol A (13 ethylene oxide units), 50 mg / L V Hydroxyflavone, 1 g / L hydroquinone monosulfonic acid potassium salt and deionized water (remainder) are mixed. A 4 x 4 cm wafer fragment with photoresist patterned vias 120 microns in diameter and 50 microns deep, a copper seed layer and 5 microns copper pillars was dipped in the composition in a glass container, at 6A / dm 2 Current density plating a layer of tin-silver. After plating, the photoresist and copper seed layer were removed, and the morphology of the formed tin-silver layer was examined using the scanning electron microscope described above. The deposit was uniform, smooth, dense and non-nodular.

[0062] The tin-silver layer was then reflowed to form bumps and the bumps were ...

technical field

[0001] The present invention relates to lead-free tin alloy electroplating compositions and methods. More particularly, the present invention relates to lead-free tin alloy electroplating compositions and methods that provide improved tin alloy deposition morphology, improved reflow performance, and the ability to deposit at high current densities. Background technique

[0002] Tin and tin-lead alloy deposits are useful in the electronics industry, particularly in the manufacture of printed wiring boards, electrical contacts and connections, semiconductors, electrical conduits, and other related components where the inherent properties of these deposits are highly desirable. Among various electronic applications, wafer level packaging (WLP) is currently concentrated in the semiconductor manufacturing industry. With wafer-level-packaging, the IC interconnections can be fabricated together on the wafer, and the entire IC module can be formed on the wafer befor...

Examples

Embodiment 1

[0053] An electrolyte composition was prepared by mixing 50 g / L tin from tin methanesulfonate, 0.4 g / L silver from silver methanesulfonate, 70 g / L methanesulfonic acid, 8 g / L 3 , 6-dithia-1,8-octanediol, 1 g / L ethyl maltol, 4 g / L ethoxylated bisphenol A (13 ethylene oxide units), 30 mg / L V Hydroxyflavone, 1 g / L hydroquinone monosulfonic acid potassium salt and deionized water (remainder) are mixed. A 4 x 4 cm wafer fragment with photoresist patterned vias on a copper seed, 120 microns in diameter and 50 microns deep, was dipped in the composition in a glass container at 6A / dm 2 Current density plating a layer of tin-silver.

[0054] With Hitachi S2460 TM The morphology of the formed tin-silver layer was examined by scanning electron microscopy. The deposit was uniform, smooth, dense and non-nodular.

[0055] The silver concentration of the tin-silver layer prepared by the sample was measured by the AAS method. The AAS equipment for the measurements was manufactured by V...

Embodiment 2

[0057] An electrolyte composition was prepared by mixing 50 g / L tin from tin methanesulfonate, 0.4 g / L silver from silver methanesulfonate, 70 g / L methanesulfonic acid, 1 g / L 3 , 6-dithia-1,8-octanediol, 1 g / L ethyl maltol, 4 g / L ethoxylated bisphenol A (13 ethylene oxide units), 10 mg / L V Hydroxyflavone, 1 g / L hydroquinone monosulfonic acid potassium salt and deionized water (remainder) are mixed. A 4 x 4 cm wafer segment with 120 micron diameter, 50 micron deep vias patterned with photoresist, a copper seed layer and 5 micron copper studs was immersed in the glass container. Composition, at 6A / dm 2 Current density plating a layer of tin-silver. After plating, the photoresist and exposed copper seed layer were removed using a Hitachi S2460 TM Scanning electron microscopy to examine the tin-silver layer. The deposit was uniform, smooth, dense and non-nodular.

[0058] The tin-silver layer was then reflowed to form bumps and the bumps were inspected with a WBI-Fox X-ray in...

Embodiment 3

[0061] An electrolyte composition was prepared by mixing 50 g / L tin from tin methanesulfonate, 0.4 g / L silver from silver methanesulfonate, 70 g / L methanesulfonic acid, 8 g / L 3 , 6-dithia-1,8-octanediol, 1 g / L ethyl maltol, 4 g / L ethoxylated bisphenol A (13 ethylene oxide units), 50 mg / L V Hydroxyflavone, 1 g / L hydroquinone monosulfonic acid potassium salt and deionized water (remainder) are mixed. A 4 x 4 cm wafer fragment with photoresist patterned vias 120 microns in diameter and 50 microns deep, a copper seed layer and 5 microns copper pillars was dipped in the composition in a glass container, at 6A / dm 2 Current density plating a layer of tin-silver. After plating, the photoresist and copper seed layer were removed, and the morphology of the formed tin-silver layer was examined using the scanning electron microscope described above. The deposit was uniform, smooth, dense and non-nodular.

[0062] The tin-silver layer was then reflowed to form bumps and the bumps were ...