Sn ALLOY PLATING APPARATUS AND METHOD

Inactive Publication Date: 2014-06-19
EBARA CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The present invention provides an Sn alloy plating apparatus and method that can control the concentration of Sn ions and their acid complexing agent in the plating solution, making it easy to control the solution and simplify the apparatus. The apparatus includes an anode chamber where bubbles of nitrogen gas can agitate the solution and prevent oxidation of the Sn ions. The solution containing the acid forming a complex with divalent Sn ions is supplied to the anode chamber to maintain the Sn ion concentration and prevent the acid concentration from becoming too low. This results in a stable, high-Sn ion concentration solution being supplied to the plating solution, enabling stable replenishment with Sn ions.

Problems solved by technology

This is because, if a soluble anode made of Sn (i.e., Sn anode) is used, displacement deposition of the nobler metal on the surface of the Sn anode will occur, leading to unstable concentration of metal component and contamination of the plating solution.
The method described in this Japanese Patent No. 4441725 necessitates a supply line and a supply device, such as a pump, to supply the Sn ion to the cathode chamber, leading to a complicated construction of the apparatus.

Method used

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Embodiment Construction

[0050]Embodiments will now be described in detail with reference to the drawings. The same reference numerals are used in the figures and descriptions to refer to the same or like members, components, etc., and duplicate descriptions thereof are omitted.

[0051]The following embodiment illustrates an exemplary case where Ag (silver) is used as a metal which is nobler than Sn (tin) and a film of an Sn—Ag alloy is formed on a substrate surface. Methanesulfonic acid is used as an acid that forms a complex with a divalent Sn ion. Thus, an Sn—Ag alloy plating solution is used which contains tin methanesulfonate as a source of Sn ions (Sn2+) and silver methanesulfonate as a source of Ag ions (Ag+). It is also possible to use silver alkylsulfonate as a source of Ag ions (Ag+).

[0052]FIG. 1 is a schematic view of an Sn alloy plating apparatus according to an embodiment. As shown in FIG. 1, the Sn alloy plating apparatus includes a plating bath 16 in which a box-shaped anode bath 10 is disposed...

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Abstract

An Sn alloy plating apparatus includes: a plating bath having a cathode chamber for holding therein an Sn alloy plating solution in which the substrate is to be immersed and an anode chamber for holding therein an anolyte containing Sn ions and an acid; an Sn anode located in the anode chamber; and an electrolytic solution supply line configured to supply an electrolytic solution containing the acid into the anode chamber such that a Sn ion concentration of the anolyte in the anode chamber is kept not less than a predetermined value and a concentration of the acid in the anolyte is kept not less than a predetermined acceptable value. The electrolytic solution supply line supplies the electrolytic solution into the anode chamber to increase an amount of the anolyte in the anode chamber and supply the anolyte into the Sn alloy plating solution by the increased amount.

Description

CROSS-REFERENCE TO RELATED APPLICATION[0001]This document claims priority to Japanese Patent Application No. 2012-272168 filed Dec. 13, 2012, the entire contents of which are hereby incorporated by reference.BACKGROUND OF THE INVENTION[0002]1. Field of the Invention[0003]The present invention relates to an Sn alloy plating apparatus and method useful for forming a metal film of an alloy of Sn and a metal which is nobler than Sn (e.g., a lead-free Sn—Ag alloy having good soldering properties) on a substrate surface.[0004]2. Description of the Related Art[0005]As is known in the art, a plating film of an alloy of Sn (tin) and a metal which is nobler than Sn (e.g., an Sn—Ag alloy which is an alloy of Sn and silver), formed by electroplating on a substrate surface, can be used for lead-free solder bumps. Sn—Ag alloy plating is typically carried out by applying a voltage between an anode and a substrate surface, which are disposed opposite to each other and immersed in an Sn—Ag alloy pla...

Claims

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Application Information

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IPC IPC(8): C25D21/14C25D3/30
CPCC25D3/30C25D21/14C25D17/008C25D17/001C25D17/002C25D21/10C25D21/18C25D5/003C25D17/00
InventorSHIMOYAMA, MASASHIFUJIKATA, JUMPEIARAKI, YUJITAMURA, MASAMICHIMIYAKAWA, TOSHIKI
OwnerEBARA CORP