KR20140077112A - Sn alloy plating apparatus and method - Google Patents

Abstract

A Sn alloy plating apparatus of the present invention comprises: an anion exchanging membrane (54) partitioning the inside of a plating bath (16) into a cathode chamber (12) which keeps a Sn alloy plating solution (Q) and soaks and arranges a substrate (W) in the Sn alloy plating solution, and an anode chamber (14) which keeps anolyte (E) containing Sn ions, bivalent Sn ions, and acid forming a complex and soaks and arranges an Sn Anode (32) in the anolyte; and an electrolyte supply line (24) for supplying electrolyte containing the acid in the anode chamber. The electrolyte supply line (24) supplies the electrolyte into the anode chamber and supplies the increased anolyte in the anode chamber by the supply of the electrolyte to the Sn alloy plating solution in order to keep the Sn ion density of the anolyte in the anode chamber above a predetermined value and to prevent the density of the acid from dropping below the permissible level.

Description

Sn ALLOY PLATING APPARATUS AND METHOD BACKGROUND OF THE INVENTION 1. Field of the Invention [0001]

The present invention relates to a Sn alloy plating apparatus and method used for forming a plating film made of a Sn-Ag alloy, which is a precious metal rather than Sn and Sn, for example, a lead-free solder.

A Sn-Ag alloy, which is an alloy of Sn (tin) and a metal that is more precious than Sn, for example, an alloy of Sn and Ag (silver) is formed on the surface of the substrate by electroplating and a plating film made of Sn- Is known. In this Sn-Ag alloy plating, a voltage is applied between the anode and the substrate surface so as to be opposed to each other while being immersed in a Sn-Ag alloy plating solution having Sn ions and Ag ions to form a Sn-Ag alloy plating film on the substrate surface . Examples of the alloy of Sn and Sn that are more valuable than Sn include Sn-Ag alloy, Sn-Cu alloy which is an alloy of Sn and Cu, Sn-Bi alloy which is an alloy of Sn and Bi (bismuth) .

In the plating of an alloy of a metal that is more valuable than Sn and Sn, an insoluble anode is often used as the anode. This is because, when a soluble anode (Sn anode) made of Sn as the anode is used, a metal more precious than Sn is deposited on the surface of the Sn anode to cause problems such as destabilization of the metal component concentration and contamination of the plating solution.

An Sn alloy plating method using a soluble anode (Sn anode) made of Sn, comprising the steps of: isolating an anode chamber in which an Sn anode is disposed, from an electroplating bath through an anion exchange membrane; (Refer to Japanese Patent No. 4441725), a plating bath containing a Sn alloy plating solution in which a Sn ion in the anode chamber can be fed to a Sn alloy plating solution in a plating bath by a return pump (See Japanese Patent No. 3368860) has been proposed in which an object to be plated placed in a plating tank is plated with an Sn anode isolated by an anode bag or box formed of a cation exchange membrane.

Further, an auxiliary tank, which is separate from the cathode chamber and the anode chamber by a diaphragm or a partition wall, is provided in the plating vessel so that the deteriorating substance is not diffused into the cathode chamber. In this auxiliary tank, the plating liquid in the anode chamber An anolyte) is supplied to a Sn-Ag alloy plating method (see Japanese Unexamined Patent Publication No. 11-21692).

As described in Japanese Patent No. 4441725, the present inventors have found that when an anode chamber and a cathode chamber are separated by an anion exchange membrane and an Sn anode stored in an anode chamber and an electrolyte solution (anolyte solution) containing an acid or a salt thereof It is important to control the acid concentration of the anolyte in the anode chamber in order to stably dissolve Sn ions in the anode chamber in the anode chamber in the method of dissolving the Sn ions by arranging the Sn ions in the anode chamber found. Further, in the method described in Japanese Patent No. 4441725, there is also a problem that the apparatus becomes structurally complicated in that it needs a supply device such as a pump for supplying Sn ions and a supply path.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a Sn alloy plating solution containing Sn It is an object of the present invention to provide a Sn alloy plating apparatus and method which can relatively easily manage the alloy plating solution and simplify the apparatus.

Sn alloy plating apparatus comprises a cathode chamber for holding a Sn alloy plating liquid and immersing a substrate to be a cathode in the Sn alloy plating liquid, an anode liquid containing an Sn ion and an acid forming a complex with Sn ion And an electrolyte solution supply line for supplying an electrolyte solution containing the acid into the anode chamber, wherein the electrolyte solution supply line includes an electrolyte solution supplying line for supplying an electrolyte solution containing the acid to the anode chamber, , The electrolytic solution is supplied into the anode chamber so that the concentration of Sn ions in the anode liquid in the anode chamber is equal to or higher than a predetermined value and the concentration of the acid is not lower than an allowable level, Solution is supplied to the Sn alloy plating solution.

Thus, by appropriately managing the concentration of the Sn ion in the anode liquid and the concentration of the acid forming the complex with the divalent Sn ion, the anolyte in which the Sn ion concentration is high and the divalent Sn ions are stably present, Sn ions can be stably supplied to the Sn alloy plating solution by supplying the plating solution to the alloy plating solution.

In a preferred embodiment, the electrolytic solution supply line overflows the anode chamber by supplying the electrolytic solution into the anode chamber, and supplies the anode solution to the Sn alloy plating solution.

This makes it possible to supply the Sn alloy plating solution with the anode solution in which no power is required and the Sn ion concentration is high and the divalent Sn ions stably exist.

In a preferred embodiment, the Sn alloy plating apparatus further includes an overflow tank for storing the plating solution overflowing the cathode chamber, and a plating solution circulating line for returning the Sn alloy plating solution in the overflow tank to the cathode chamber for circulation .

Thus, the Sn alloy plating solution in the cathode chamber can be circulated through the plating solution circulation line and stirred.

In a preferred embodiment, the Sn alloy plating apparatus further comprises a pure water supply line for supplying pure water into the anode chamber.

Accordingly, the concentration of the acid in the anode liquid in the anode chamber can be adjusted to a desired range by controlling the liquid amount of the electrolytic solution supplied into the anode chamber through the pure water supplied into the anode chamber through the pure water supply line or the electrolytic solution supply line .

In a preferred embodiment, the Sn alloy plating apparatus further comprises an acid concentration meter for measuring the concentration of the acid in the anode liquid in the anode chamber.

In a preferred embodiment, the apparatus further comprises a dialysis vessel for extracting a part of the Sn alloy plating liquid from the cathode chamber and removing at least a part of the acid from the Sn alloy plating liquid and returning it to the cathode chamber.

Accordingly, when the concentration of the acid in the Sn alloy plating solution becomes excessive, at least a part of the acid can be removed from the Sn alloy plating solution through the dialysis bath to adjust the acid to a desired range.

In a preferred embodiment, the Sn alloy plating apparatus further includes an N ₂ gas supply line for supplying nitrogen gas to the anode liquid in the anode chamber to bubble the anode liquid.

Thereby, the anode liquid in the anode chamber is sufficiently stirred with nitrogen gas to uniformly distribute Sn ions or the acid in the anode liquid in the anode chamber, and furthermore, to prevent oxidation of Sn ions in the anode liquid.

In a preferred embodiment, a voltage is applied between the auxiliary Sn anode immersed in the anode liquid in the auxiliary anode chamber and the auxiliary cathode immersed in the cathode solution in the auxiliary cathode chamber, And an auxiliary electrolytic cell for supplying the anode solution in the auxiliary anode chamber with the increased Sn ion concentration to the Sn alloy plating solution.

Thus, when the Sn ion in the entire system is insufficient, this deficient Sn ion can be supplemented with the anode liquid in the anode chamber with the increased Sn ion concentration.

Sn alloy plating method is characterized in that a plating bath in which an inside is separated from a cathode chamber and an anode chamber by an anion exchange membrane is provided, a Sn alloy plating solution is contained in the cathode chamber, the substrate is immersed in the Sn alloy plating solution, An Sn anode containing Sn as a material and an anode containing an anode forming a complex with Sn ion and divalent Sn ion is immersed in the anode liquid, and Sn anode is disposed in the anode chamber. Supplying an electrolytic solution into the anode chamber so that the Sn ion concentration is equal to or higher than a predetermined value and the concentration of the acid is not lower than an allowable level and supplying the anode solution in the anode chamber increased in accordance with the supply of the electrolytic solution to the Sn alloy plating solution, A voltage is applied between the cathode and the Sn anode to perform Sn alloy plating on the surface of the substrate.

In a preferred embodiment, the increased anode liquid is supplied to the Sn alloy plating liquid by overflowing the anode chamber by supplying the electrolytic solution into the anode chamber.

In a preferred embodiment, the Sn alloy plating solution in the cathode chamber is circulated.

In a preferred embodiment, the supply amount of the electrolytic solution or pure water to the anode chamber is controlled based on the concentration of the acid in the anode liquid in the anode chamber.

In one preferred embodiment, the concentration of the acid in the anode liquid is such that the concentration of the acid in the initial anode liquid, the electrolytic amount and the current efficiency in the Sn anode, the supply amount of the electrolytic solution, and the anion exchange membrane, It is obtained from the transmittance of the acid which is actually transferred.

In a preferred embodiment, a part of the Sn alloy plating liquid is withdrawn from the cathode chamber, and at least a part of the acid is removed from the Sn alloy plating liquid and returned to the cathode chamber.

In a preferred embodiment, nitrogen gas is supplied into the anode liquid in the anode chamber to bubble the anode liquid.

In a preferred embodiment, a voltage is applied between the auxiliary Sn anode immersed in the anode liquid in the auxiliary anode chamber of the auxiliary electrolytic cell and the auxiliary cathode immersed in the cathode liquid in the auxiliary cathode chamber isolated from the auxiliary anode chamber and the anion exchange membrane, The anode liquid in the auxiliary anode chamber in which the ion concentration is increased is supplied to the Sn alloy plating liquid.

According to the present invention, an electrolytic solution containing the acid is supplied into the anode chamber so that the concentration of the Sn ion in the anode liquid is equal to or higher than a predetermined value and the concentration of the acid forming a complex with the divalent Sn ion is not lower than an allowable level , The concentration of Sn ions in the anode liquid and the concentration of the acid can be appropriately managed. Further, by feeding the anode liquid in the anode chamber increased to the Sn alloy plating liquid in accordance with the supply of the electrolytic solution, the anode liquid in which the Sn ion concentration is high and the divalent Sn ions are stably present is supplied to the Sn alloy plating liquid, It is possible to stably supply Sn ions to the alloy plating solution.

1 is a schematic diagram showing a Sn alloy plating apparatus according to an embodiment of the present invention.
2 is a perspective view showing an anode tank.
3 is a cross-sectional view showing a main part of another example of overflowing the anode liquid in the anode.
4 is a perspective view showing a main part of another example of overflowing the anode liquid in the anode.
5 is a perspective view schematically showing the substrate holder shown in Fig.
Figure 6 is a top view of the substrate holder shown in Figure 1;
7 is a right side view of the substrate holder shown in Fig.
8 is an enlarged view of part A of Fig.
Fig. 9 is an enlarged view of a main part showing a state in which plating is performed by a Sn alloy plating apparatus.
10 is a graph showing the comparison between the Sn ion concentration of the anode liquid in the theoretical anode chamber converted from the electrolytic amount and the actually measured Sn ion concentration.
11 is a schematic view showing another plating bath.
12 is a schematic diagram showing a Sn alloy plating apparatus according to another embodiment of the present invention.
13 is a schematic view showing a Sn alloy plating apparatus according to still another embodiment of the present invention.
14 is a schematic view showing a Sn alloy plating apparatus according to still another embodiment of the present invention.
15 is a schematic diagram showing a Sn alloy plating apparatus according to still another embodiment of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the drawings. In each of the following examples, the same or equivalent members are denoted by the same reference numerals, and redundant description is omitted.

In the following example, Ag (silver) is used as a precious metal rather than Sn (tin) to form a plated film made of Sn-Ag alloy on the surface of the substrate. Methanesulfonic acid is used as an acid to form a complex with a divalent Sn ion. Therefore, Sn-Ag alloy plating solution containing tin methanesulfonate as Sn ion (Sn ^{2 +} ) and methanesulfonic acid silver as Ag ion (Ag ⁺ ) in the plating solution is used as the plating solution. As Ag ion (Ag ⁺ ), alkylsulfonic acid silver may be used.

1 is a schematic diagram showing a Sn alloy plating apparatus according to an embodiment of the present invention. 1, this Sn alloy plating apparatus has a box-shaped anode tank 10 disposed therein, so that the interior thereof is connected to the anode chamber 14 inside the cathode chamber 12 and the anode tank 10 And a partitioned plating vessel 16 is provided.

The cathode chamber 12 is connected to the plating liquid supply line 20 extending from the plating liquid supply source 18 through the overflow bath 36 described below and is filled with an Sn-Ag alloy plating liquid (hereinafter simply referred to as plating liquid Quot; Q "). A substrate W, which is detachably held in the substrate holder 22 and becomes a cathode at the time of plating, is immersed in the plating liquid Q at a predetermined position inside the cathode chamber 12.

An anode liquid supply line 23, an electrolyte liquid supply line 24, a pure water supply line 26 and a liquid drain line 28 are connected to the anode chamber 14 and an anode liquid E Respectively. A soluble Sn anode 32 made of Sn and held by the anode holder 30 is immersed in the anode liquid E at a predetermined position inside the anode chamber 14. An N ₂ gas supply line 33 for bubbling the anode liquid E by supplying nitrogen gas into the anode liquid E is disposed at the bottom of the anode chamber 14.

In this example, as the anode liquid (E), a solution containing methane sulfonic acid and Sn ion which forms a complex with a divalent Sn ion and does not contain Ag ions is used. A part of the methanesulfonate ion in the anode liquid (E) surrounds the Sn ion and forms a complex with the divalent Sn ion, and the other part exists in the anode liquid (E) as the free acid. In the present specification, the methanesulfonic acid concentration refers to an acid concentration as a free acid, unless otherwise specified. Even if the Sn anode 32 is immersed in the anode liquid E because Ag ions are not contained in the anode liquid E, Ag reacts with the Sn anode 32 to replace the surface of the Sn anode 32 It is not precipitated. An aqueous solution containing methanesulfonic acid (methanesulfonic acid aqueous solution) is used as the electrolyte solution supplied to the anode chamber 14 through the electrolyte solution supply line 24. [

The Sn anode 32 is connected to the positive electrode of the plating power source 34 and a conductive layer (not shown) such as a seed layer formed on the surface of the substrate W is connected to the plating power source 34 And is connected to the negative electrode. As a result, a plating film made of an Sn-Ag alloy is formed on the surface of the conductive layer. This plating film is used, for example, in a lead-free solder bump.

An overflow tank 36 into which the plating liquid Q overflowing the upper end of the cathode chamber 12 flows is provided adjacent to the cathode chamber 12 in the plating vessel 16. One end of a plating liquid circulating line 46 via a pump 38, a heat exchanger (temperature regulator) 40, a filter 42 and a flow meter 44 is connected to the bottom of the overflow tank 36, The other end of the plating liquid circulating line 46 is connected to the bottom of the cathode chamber 12. A plating liquid supply line 20 extending from the plating liquid supply source 18 is connected to the top of the overflow bath 36.

An adjustment plate (regulation plate) 50, which is disposed between the substrate holder 22 and the Sn anode 32 disposed inside the cathode chamber 12 and adjusts the potential distribution in the cathode chamber 12, Respectively. In this example, the adjustment plate 50 uses vinyl chloride, which is a dielectric, as a material, and has a central hole 50a having a size that can sufficiently restrict the expansion of the electric field. The lower end of the adjusting plate (50) reaches the bottom plate of the cathode chamber (12).

And is disposed inside the cathode chamber 12 between the substrate holder 22 disposed in the cathode chamber 12 and the adjustment plate 50 and extends in the vertical direction and reciprocates in parallel with the substrate W, There is disposed an agitation paddle 52 as an agitator for agitating the plating liquid Q between the holder 22 and the regulating plate 50. [ Sufficient metal ions can be uniformly supplied to the surface of the substrate W by stirring the plating liquid Q in the cathode chamber 12 with the stirring paddle (agitator) 52 during plating.

An anion exchange membrane 54 is provided inside the partition wall 10a on the cathode chamber side of the anode tank 10 partitioning the inside of the plating vessel 16 into a cathode chamber 12 and an anode chamber 14, (12) and the anode chamber (14) are isolated by the anion exchange membrane (54). As the anion exchange membrane 54, for example, AAV manufactured by AGC Engineering Co., Ltd. is used, and an arbitrary number of anion exchange membranes 54 are provided in the partition wall 10a in accordance with the amount of permeation of water molecules containing methanesulfonic acid. The number and arrangement of the anion exchange membranes 54 are arbitrarily adjusted in accordance with the required membrane area or the permeation amount of a water molecule to be described later. The anion exchange membrane 54 is provided on the partition wall 10a in a watertight manner by an O ring or the like so that the plating liquid Q in the cathode chamber 12 does not move to the anode chamber 14. [

The partition wall 10a and the anion exchange membrane 54 are located between the Sn anode 32 and the substrate W. [ The partition wall 10a is formed by blocking the anode liquid E in the anode chamber 14 with a dam so that the anode liquid E overflowing the upper end of the partition wall 10a flows into the overflow wall . That is, the anode chamber E of the predetermined liquid level H (see FIG. 9) is held in the anode chamber 14 by the partition wall (overflow dike) 10a, The excess amount of the anode liquid E flows into the anode chamber 14 by overflowing the upper end of the partition wall 10a.

The plating liquid circulating line 46 is connected to a plating liquid supply pipe 64 which is located downstream of the flow meter 44 and supplies the plating liquid Q to the dialysis tank 62 provided with the anion exchange membrane 60 therein, The plating liquid discharge pipe 66 extending from the bath 62 is connected to the top of the overflow bath 36. The plating solution supply pipe 64 and the plating solution discharge pipe 66 are connected to a plating solution circulation line 46 and a plating solution dialysis line 68 for withdrawing and circulating a part of the plating solution Q from the plating solution circulation line 46 Respectively. The dialysis tank 62 is connected to a pure water supply line 70 for supplying pure water to the inside of the dialysis tank 62 and a pure water discharge line 72 for discharging the pure water to the outside.

The plating liquid Q flowing in the plating liquid dialysis line 68 is supplied into the dialysis tank 62 and at least part of the methane sulfonic acid as the free acid is removed by dialysis using the anion exchange membrane 60, And returns to the group (36). The methanesulfonic acid removed from the plating liquid Q by the dialysis is diffused into the pure water supplied into the dialysis tank 62 through the pure water supply line 70 and discharged from the pure water discharge line 72 to the outside.

As the anion exchange membrane 60, for example, DSV manufactured by AGC Engineering Co., Ltd. is used. An arbitrary number of anion exchange membranes 60 are provided in the dialysis tank 62 in accordance with the amount of dialysis of the plating solution (amount of methanesulfonate removed).

On the other hand, in this example, at least a part of the methanesulfonic acid as the free acid in the plating liquid Q is removed by using the dialysis vessel 62 using the diffusion dialysis method, but the free acid removal using the electrodialysis method or the ion exchange resin method At least a part of methanesulfonic acid as a free acid in the plating liquid Q may be removed by using a bath.

The plating liquid circulating line 46 is provided with a Sn ion concentration measuring instrument 74 for measuring the Sn ion concentration of the plating liquid Q flowing in the plating liquid circulating line 46 and a plating liquid circulating line 46 Methane sulfonic acid concentration meter 76 for measuring the methane sulfonic acid concentration of the methane sulfonic acid. The outputs (i.e., concentration measurement values) from the Sn ion concentration meter 74 and the methane sulfonic acid concentration meter 76 are input to the plating solution supply source 18 and the control unit 80, respectively.

2 is a perspective view showing the anode tank 10. Fig. As shown in Fig. 2, a wall-flow-use notch 10b (see Fig. 2), which is an outlet of the anode liquid E overflowing the anode chamber 14, is provided at a position offset in one direction at the upper end of the partition 10a serving as a overflow dam ). The level of the liquid level (H) (see FIG. 9) of the anode liquid E held in the anode chamber 14 is determined by the position of the lower end of the overflow notch 10b.

The electrolyte supply line 24 extends downward along the side of the anode tank 10. An electrolyte solution supply port 24a for supplying an electrolyte (methanesulfonic acid aqueous solution) to the anode chamber 14 is formed at the lower end of the electrolyte solution supply line 24. The electrolyte solution supply port 24a reaches the bottom of the anode tank 10 and opens horizontally. The pure water supply line 26 also extends downward along the side of the anode tank 10. At the lower end of the pure water supply line 26, a pure water supply port 26a for supplying pure water to the anode chamber 14 is formed. The pure water supply port 26a reaches the bottom of the anode tank 10 and opens horizontally. On the other hand, the electrolyte solution supply port 24a and the pure water supply port 26a may be opened downward. The electrolytic solution supply port 24a and the pure water supply port 26a and the wall flow notch 10b of the partition wall 10a are positioned diagonally to each other on the horizontal projection plane of the anode tank 10. [ Thus, when the pure water is supplied through the pure water supply line 26 or the electrolytic solution is supplied to the anode chamber 14 through the electrolytic solution supply line 24, the anode liquid E containing Sn ions is supplied to the pure water Or is sufficiently stirred with the electrolytic solution, then overflows the overflow notch 10b and is supplied to the cathode chamber 12.

The N ₂ gas supply line 33 extends downward along the side of the anode tank 10 and reaches the bottom of the anode tank 10 and extends almost the entire length in the longitudinal direction of the anode tank 10 have. And, N ₂ and the anolyte ring (E) by discharging the nitrogen gas from the upper side toward the outlet (33a) formed in the gas supply line 33, the bubbles. The anode liquid (E) in the anode chamber (14) is sufficiently stirred with nitrogen gas. This promotes uniform distribution of Sn ions or methanesulfonic acid in the anode liquid (E) in the anode chamber (14), and prevents oxidation of Sn ions in the anode liquid (E). For this reason, bubbling of the anode liquid E by the nitrogen gas is preferably performed from the bottom of the anode chamber 14.

On the other hand, it is preferable that the supply of the nitrogen gas is stopped immediately before supplying the pure water or the electrolytic solution to the anode chamber 14, and the bubbling of the anode liquid E by the nitrogen gas is not performed during the supply of the pure water or the electrolytic solution. Thereby, the anode liquid E in which the Sn ions are sufficiently diffused can be overflowed and supplied to the cathode chamber 12 without being excessively diluted by the supplied pure water or the electrolytic solution.

A liquid level detecting sensor for detecting a decrease in liquid level due to the evaporation of the anode liquid (E) in the anode chamber (14) by detecting the liquid level of the anode liquid (E) in the anode chamber (14) (Not shown). The anode liquid E in the anode chamber 14 is replenished with the pure water from the pure water supply line 26 to the anode chamber E in the anode chamber 14 by detecting the decrease in the liquid volume due to the evaporation of the anode liquid E. [ The liquid level of the liquid E can be made constant at all times. Further, the supply amount of Sn ions to the cathode chamber 12 can be controlled by the supply amount of the pure water or the electrolytic solution with respect to the anode chamber 14.

On the other hand, the overflow of the anode liquid E in the anode chamber 14 to the cathode chamber 12 may be caused by mechanical means. 3, the float 84 is floated on the anode liquid E in the anode chamber 14 and the float 84 is submerged in the anode liquid E. As a result, May be overflowed to the cathode chamber (12). In this case, since there is no introduction of water due to the supply of pure water or the electrolytic solution, the anode liquid E is supplied to the cathode chamber 12 without being diluted.

4, the movable dam 86 may be movable up and down inside the rectangular notch 10c provided at the upper end of the partition 10a serving as the overflow dam. In the example shown in Fig. 4, the movable dam 86 is lowered to supply the anode liquid E as much as the height to the cathode chamber 12. In this case as well, it is possible to prevent the anode liquid E from being diluted and supplied to the cathode chamber 12.

When Sn ions in the entire system are insufficient, it is necessary to supply Sn ions to the plating liquid (Q). As a method of supplying the Sn ions, a method of adding a high-concentration Sn-replenishing solution to the plating solution (Q) can be mentioned, but the high-concentration Sn-replenishing solution is generally expensive and leads to an increase in cost. Therefore, in this example, an auxiliary electrolytic bath 100 for supplying Sn ions is provided separately from the plating bath 16.

Inside the auxiliary electrolytic bath 100, a box-shaped cathode tank 102 is disposed. The interior of the auxiliary electrolytic cell 100 is divided into an anode chamber (auxiliary anode chamber) 104 and a cathode chamber (secondary cathode chamber) 106 inside the cathode chamber 102. An anion exchange membrane 108 is provided inside the partition wall 102a on the anode chamber side of the cathode tank 102 for partitioning the anode chamber 104 and the cathode chamber 106. [ The auxiliary electrolytic bath 100 is isolated from the anode chamber 104 and the cathode chamber 106 by the anion exchange membrane 108.

The anode chamber 104 is provided with an anode liquid supply line 110 for supplying an anode liquid A containing Sn ions and methane sulfonic acid and not containing Ag ions and an aqueous solution containing methane sulfonic acid (methanesulfonic acid aqueous solution) And an electrolytic solution supply line 112 for supplying the formed electrolytic solution is connected. Inside the anode chamber 104, a Sn anode (auxiliary Sn anode) 118 held by the anode holder 116 is immersed in the anode liquid A and arranged. One end of the Sn ion supply line 114 is connected to the anode chamber 104 and the other end of the Sn ion supply line 114 is connected to the upper end of the overflow bath 36 of the plating tank 16 have. The Sn ion supply line 114 is provided with a pump 120.

The cathode chamber 106 is provided with a cathode solution supply line 122 for supplying a cathode solution B made of an aqueous solution containing methanesulfonic acid (methanesulfonic acid aqueous solution), a drainage line 124 for discharging the cathode solution B, And a cathode (auxiliary cathode) 128 made of, for example, SUS held in the cathode holder 126 is immersed in the cathode liquid B and placed in the cathode chamber 106. [ The partition wall 102a and the anion exchange membrane 108 described above are located between the Sn anode 118 and the cathode 128. [

In this auxiliary electrolytic cell 100, first, an anode including a high concentration (for example, 220 g / L to 350 g / L) of Sn ion and methane sulfonic acid and containing no Ag ion through the anode liquid supply line 110 The liquid A is supplied into the anode chamber 104 and the Sn anode 118 is immersed in the anode liquid A. [ A cathode solution B composed of a methanesulfonic acid aqueous solution is supplied into the cathode chamber 106 through the cathode solution supply line 122 and the cathode 128 is immersed in the cathode solution B. [

In this state, the positive electrode of the auxiliary power source 130 is connected to the Sn anode 118, and the negative electrode is connected to the cathode 128 to start electrolysis. When the electrolysis is started in this way, Sn ions are dissolved from the Sn anode 118 and the Sn ion concentration of the anode liquid (A) is increased. Since the anode chamber 104 and the cathode chamber 106 are isolated by the anion exchange membrane 108, the Sn ions do not move into the cathode chamber 106, and the cathode 128 is not plated. Further, since Ag does not include Ag ions in the anode liquid (A), Ag is not substituted on the surface of the Sn anode (118). The Sn ions contained in the anode liquid A are supplied from the anode liquid supply line 110 before the start of operation but are supplied by being dissolved from the Sn anode 118 after the start of operation.

The anode liquid A having reached the predetermined concentration is supplied into the overflow bath 36 of the plating bath 16 through the Sn ion supply line 114 by driving the pump 120. [ The supply amount of the anode liquid A to the overflow bath 36 decreases the liquid amount of the anode liquid A in the anode chamber 104 so that the electrolytic solution for replenishing the anode liquid A is supplied from the electrolytic solution supply line 112 And is supplied to the anode chamber 104. A higher Sn ion concentration in the anode liquid (A) is advantageous because the amount of drainage from the entire system can be suppressed.

Methane sulfonic acid ions included in the cathode liquid B in the cathode chamber 106 permeate the anion exchange membrane 108 and move into the anode chamber 104. As a result, the conductivity of the cathode liquid B in the cathode chamber 106 decreases with time. Therefore, the cathode liquid B is supplied to the cathode chamber 106 through the cathode liquid supply line 122 connected to the cathode chamber 106. The cathode liquid B in the cathode chamber 106 is discharged to the outside through the drain line 124 so that the cathode liquid B as much as the supplied amount does not overflow.

5 to 8, the substrate holder 22 includes a first holding member 154 of a rectangular flat plate shape and a second holding member 154 which is attached to the first holding member 154 via a hinge 156 so as to be openable and closable And a second retaining member 158 which is made of a resin. The second holding member 158 may be disposed at a position that is opposed to the first holding member 154 to advance the second holding member 158 toward the first holding member 154, The second holding member 158 may be opened and closed by being separated from the first holding member 154. [

The first holding member 154 is made of, for example, vinyl chloride. The second holding member 158 has a base portion 160 and a ring-shaped seal holder 162. The seal holder 162 is made of, for example, a vinyl chloride material and improves the slip with the compression ring 164 below. An annular substrate side seal member 166 (see Figs. 7 and 8) is attached to the upper portion of the seal holder 162 so as to protrude inward. The substrate side seal member 166 is in contact with the outer circumferential portion of the surface of the substrate W when the substrate holder 22 holds the substrate W to be in pressure contact with the surface of the second holding member 158 and the substrate W Seal the gap. On the surface of the seal holder 162 facing the first holding member 154, an annular holder-side seal member 168 (see Figs. 7 and 8) is attached. The holder side seal member 168 presses the first holding member 154 and the second holding member 158 when the substrate holder 22 holds the substrate W, As shown in Fig. The holder side seal member 168 is located outside the substrate side seal member 166.

The substrate side seal member 166 is sandwiched between the seal holder 162 and the first retaining ring 170a and attached to the seal holder 162 as shown in Fig. The first retaining ring 170a is attached to the seal holder 162 through a fastener 169a such as a bolt. The holder side seal member 168 is sandwiched between the seal holder 162 and the second retaining ring 170b and attached to the seal holder 162. [ The second retaining ring 170b is attached to the seal holder 162 through a fastener 169b such as a bolt.

A stepped portion is formed on the outer periphery of the seal holder 162, and a pressing ring 164 is rotatably mounted on the stepped portion through a spacer 165. The pressing ring 164 is mounted so as not to be detachable by the pressing plate 172 (see Fig. 6) attached so as to protrude outward on the side surface of the seal holder 162. The pressing ring 164 is made of a material excellent in corrosion resistance against acid or alkali and having sufficient rigidity. For example, the compression ring 164 is made of titanium. The spacer 165 is made of a material having a low coefficient of friction, such as PTFE, so that the pressing ring 164 can rotate smoothly.

A plurality of clamper 174 are arranged at equal intervals along the circumferential direction of the pressing ring 164 on the outside of the pressing ring 164. These clamper 174 are fixed to the first holding member 154. Each of the clamper 174 has an inverted L-like shape having a protruding portion protruding inward. On the outer circumferential surface of the pressing ring 164, a plurality of protruding portions 164b protruding outward are provided. These protrusions 164b are arranged at positions corresponding to the positions of the clamper 174. [ The lower surface of the inner protrusion of the clamper 174 and the upper surface of the protrusion 164b of the pressing ring 164 are tapered surfaces that are inclined in opposite directions along the rotation direction of the pressing ring 164. At a plurality of positions (for example, three positions) along the circumferential direction of the pressing ring 164, convex portions 164a protruding upward are provided. Thereby, the pushing ring 164 can be rotated by rotating the rotation pin (not shown) to push the convex portion 164a from the side.

The substrate W is inserted into the center of the first holding member 154 and the second holding member 158 is closed through the hinge 156 in a state in which the second holding member 158 is opened. The pressing ring 164 is rotated in the clockwise direction so that the projection 164b of the pressing ring 164 slides into the inside projection of the clamper 174 so that the pressing ring 164 and the clamper 174 The first holding member 154 and the second holding member 158 are fastened together to fix the second holding member 158 through the formed tapered surface. The second holding member 158 is unlocked by rotating the pressing ring 164 in the counterclockwise direction to release the protrusion 164b of the pressing ring 164 from the clamper 174. [

When the second holding member 158 is fixed, the lower protrusion of the substrate-side seal member 166 is pressed against the outer circumferential portion of the surface of the substrate W. The substrate side seal member 166 is uniformly pressed against the substrate W to thereby seal the gap between the surface outer circumferential portion of the substrate W and the second holding member 158. [ Similarly, when the second retaining member 158 is fixed, the lower protruding portion of the holder-side seal member 168 is pressed against the surface of the first retaining member 154. The holder side seal member 168 is uniformly pressed against the first holding member 154 to thereby seal the gap between the first holding member 154 and the second holding member 158. [

At the end of the first holding member 154, a pair of substantially T-shaped holder hangers 190 are provided. On the upper surface of the first holding member 154, a ring-shaped protruding portion 182 approximately equal to the size of the substrate W is formed. The protrusion 182 has an annular support surface 180 for supporting the substrate W in contact with the peripheral edge of the substrate W. [ A concave portion 184 is provided at a predetermined position along the circumferential direction of the projection 182.

As shown in Fig. 6, a plurality of (in this example, twelve) conductors (electrical contacts) 186 are disposed in the concave portion 184, respectively. These conductors 186 are connected to a plurality of wirings extending from connection terminals (not shown) provided in the holder hanger 190, respectively. When the substrate W is placed on the support surface 180 of the first holding member 154, the end of the conductor 186 elastically contacts the lower portion of the electrical contact 188 shown in Fig. 8 .

The electrical contact 188 electrically connected to the conductor 186 is fixed to the seal holder 162 of the second holding member 158 by a fastener 189 such as a bolt. The electrical contact 188 is formed in a leaf spring shape. The electrical contact 188 has a contact portion which is located on the outside of the substrate side seal member 166 and protrudes in the form of a leaf spring. The electrical contact 188 has a spring property by its elastic force at this contact portion so as to be easily bent. The contact portion of the electrical contact 188 is supported on the supporting surface 180 of the first holding member 154 when the substrate W is held by the first holding member 154 and the second holding member 158. [ And is elastically brought into contact with the outer circumferential surface of the substrate W which has been formed.

The opening and closing of the second holding member 158 is performed by the own weight of the air cylinder and the second holding member 158 (not shown). That is, the first holding member 154 is formed with the passage hole 154a, and the piston rod of the air cylinder (not shown) passes through the passage hole 154a to the seal holder 162 of the second holding member 158 The second holding member 158 is opened and the piston rod is contracted to close the second holding member 158 at its own weight.

Next, the operation of the plating apparatus of this embodiment will be described. The pump 38 is driven to circulate the plating liquid Q in the cathode chamber 12 through the plating liquid circulating line 46 and stir. In this state, the substrate W held by the substrate holder 22 is immersed in the plating liquid Q in the cathode chamber 12 and arranged at a predetermined position. Meanwhile, the inside of the anode chamber 14 is filled with the initial anode liquid E, and the Sn anode 32 is immersed in the anode liquid E.

The Sn anode 32 is connected to the positive electrode of the plating power source 34 and the conductive layer such as a seed layer formed on the surface of the substrate W is connected to the negative electrode of the plating power source 34, ) On the surface of the substrate. The agitating paddle (agitator) 52 is reciprocated in parallel with the substrate W, and the plating liquid Q in the cathode chamber 12 is agitated. At the same time, the anode liquid (E) in the anode chamber (14) is bubbled with nitrogen gas through the N ₂ gas supply line (33).

As described above, when plating is performed, Sn ions are eluted from the Sn anode 32 into the anode liquid E in the anode chamber 14, as shown in Fig. Since the elution of Sn ions occurs every time the plating process is performed, the Sn ion concentration of the anode liquid (E) in the anode chamber (14) rises. When the electrolytic solution from the electrolytic solution supply line 24 or the pure water from the pure water supply line 26 is supplied into the anode chamber 14, the anode liquid E in the anode chamber 14 increases. When the liquid level of the anode liquid E in the anode chamber 14 exceeds the predetermined liquid level H and increases by DELTA H, the positive anode liquid E that matches the rising amount DELTA H of the liquid level is discharged to the anode chamber (See Fig. 2) provided in the partition 10a of the partition wall 14, and flows into the cathode chamber 12. [0064] As shown in Fig. Accordingly, a part of the Sn ions in the anode chamber 14 are supplied into the cathode chamber 12, and can replenish the Sn ions consumed by the plating on the substrate W. When the anode liquid E is supplied to the plating liquid Q as described above, the amount of the plating liquid Q increases, so that the amount of the plating liquid Q corresponding to the anode liquid E supplied into the cathode chamber 12, Is discharged in advance.

On the other hand, when an electric field is formed between the Sn anode 32 and the substrate W as a cathode, methane sulfonic acid in the cathode chamber 12 permeates the anion exchange membrane 54 together with water molecules, Lt; / RTI > The anode liquid E in the anode chamber 14 increases and the anode liquid E which exceeds the predetermined liquid level H exceeds the partition wall 10a and flows into the cathode chamber 12 ≪ / RTI > In this way, Sn ions in the anode chamber 14 can be supplied to the cathode chamber 12.

Here, the inventors have experimentally confirmed that the concentration of methanesulfonic acid as free acid in the anode chamber 14 is important for stabilizing Sn ions dissolved from Sn anodes. In the experiment, an anode liquid composed of an aqueous methanesulfonic acid solution was added to the anode chamber so that the concentration of methanesulfonic acid was 100 g / L, and electrolysis was started. In this case, when electrolysis was continued, turbidity occurred in the anode liquid in the anode chamber. This indicates that the Sn ion in the anode liquid can not stably exist as a bivalent ion and is precipitated as metal Sn or has tetravalent Sn ions.

On the other hand, when electrolysis was started at a concentration of methanesulfonic acid of 140 g / L, even if the electrolysis was continued, there was no turbidity in the anode liquid in the anode chamber, and the Sn ion concentration in the anode liquid coincided with the calculated value did. That is, since methanesulfonic acid ions are sufficiently present, divalent Sn ions are surrounded by methanesulfonic acid ions to form complexes and stably exist. Therefore, it can be understood that the concentration of methane sulfonic acid in the anode liquid is required to be a concentration suitable for stably presenting Sn ions as divalent ions.

As described above, pure water is supplied into the anode chamber 14 from the pure water supply line 26 to overflow the anode liquid E in the anode chamber 14 into the cathode chamber 12, (12). In this example, an electrolytic solution supply line 24 for supplying an electrolytic solution (methanesulfonic acid aqueous solution) to the anode chamber 14 is formed. This is for the following reasons.

When pure water is supplied from the pure water supply line 26 to the anode chamber 14 to overflow the anode liquid E in the anode chamber 14, methane sulfonic acid in the anode chamber 14 flows into the cathode chamber 12, The methane sulfonic acid concentration of the anode liquid (E) in the anode chamber (14) is lowered. The methane sulfonic acid in the cathode chamber 12 forms an electric field between the Sn anode 32 and the substrate W as a cathode to permeate the anion exchange membrane 54 from the cathode chamber 12 to the anode chamber 14 ). The transport rate of the methanesulfonic acid varies depending on the conditions, but is not 100%, and may be 50% to 90% due to loss. In this case, in the anode chamber 14, the ratio of the molar concentration of methane sulfonic acid, which permeates the anion exchange membrane 54 through the anode chamber 14 to the Sn ions dissolved from the Sn anode 32, . As a result, the concentration of methane sulfonic acid in the anode liquid (E) in the anode chamber (14) is lowered. As a result, the Sn ions in the anode chamber 14 may be destabilized as described above.

Therefore, it is necessary to supply the electrolytic solution containing methanesulfonic acid from the electrolytic solution supply line 24 to the anode chamber 14 so that the concentration of methanesulfonic acid in the anode liquid (E) in the anode chamber (14) .

For efficient operation of the plating apparatus, it is preferable to supply the anode liquid E to the cathode chamber 12 by overflow with the Sn ion concentration of the anode liquid E in the anode chamber 14 as high as possible Do. This is because when the anode liquid E is supplied to the cathode chamber 12 in a state where the Sn ion concentration is low, the anode liquid E from the anode chamber 14 for supplying a certain amount of Sn ions to the cathode chamber 12 (Overflow amount) of the plating liquid Q increases, and the amount of the plating liquid Q to be discharged from the circulation system including the cathode chamber 12 increases accordingly, which is not economical.

Specifically, the Sn ion concentration in the anode liquid (E) of the anode chamber 14 is generally 80 g / L to 500 g / L, preferably 200 g / L to 400 g / L, The range is from 220 g / L to 350 g / L. The Sn ion concentration in the anode liquid E is calculated by subtracting the Sn ion concentration in the anode liquid E newly injected into the anode chamber 14 and the Sn concentration converted from the electrolytic amount in the Sn anode 32 after the start of operation Ion concentration. The Sn ion concentration of the anode liquid (E) is very important for managing the Sn ion concentration in the entire plating bath.

The Sn ion concentration in the Sn-Ag plating liquid (Q) is usually 50 g / L to 80 g / L. When the decrease in the Sn ion concentration in the cathode chamber 12 is to be replenished with the anode liquid E containing Sn ions in the anode chamber 14, the Sn ion concentration of the anode liquid E of the anode chamber 14 The volume of the anode liquid E replenished to the cathode chamber 12 is reduced. Normally, the amount of the plating liquid Q in the cathode chamber 12 decreases due to evaporation or the like. When the anode liquid E of the anode chamber 14 is supplied to the anode chamber 14 over the weight loss, it is necessary to finally discharge the excess liquid amount from the plating liquid Q in the cathode chamber 12. However, the concentration of Sn ions in the anode liquid (E) can not be increased to the saturation concentration of tin methanesulfonate or higher. Further, in order for the Sn ions to stably exist, it is necessary to set the concentration of Sn ions in the anode liquid (E) to a saturated concentration or less.

The pure feed line 26 is used not only to replenish the moisture evaporation in the anode chamber 14 but also to increase the concentration of methane sulfonic acid in the anode chamber 14 when the concentration of methane sulfonic acid in the anode liquid E in the anode chamber 14 is sufficiently high ) To overflow the anode liquid (E) in the cathode chamber (12) to supply Sn ions into the cathode chamber (12). The pure water supply line 26 is used when adjusting the concentration of components in the anode chamber 14 by supplying pure water into the anode chamber 14. [

Next, an operation example of the Sn alloy plating apparatus shown in Fig. 1 will be described.

(E) containing methane sulfonic acid and a high concentration of Sn ions (for example, 220 g / L to 350 g / L) through the anode liquid feed line 23 before starting the operation of the Sn alloy plating apparatus, Is supplied to the anode chamber (14), and the anode chamber (14) is filled with the anode liquid (E). This is because the amount of the plating solution Q to be wasted can be reduced by supplying the anode liquid E of the anode chamber 14 to the cathode chamber 12 with the Sn ion concentration being high as described above, If the operation is started with the Sn ion concentration of the anode liquid E at a low concentration, it is necessary to wait until the Sn ion concentration of the anode liquid E becomes high, which is disadvantageous.

As described above, the pump 38 is driven to circulate the plating liquid Q in the cathode chamber 12 through the plating liquid circulating line 46, and the substrate W held by the substrate holder 22 W are immersed in the plating liquid Q in the cathode chamber 12 and arranged at predetermined positions.

The Sn anode 32 is connected to the positive electrode of the plating power source 34 and the conductive layer such as a seed layer formed on the surface of the substrate W is connected to the negative electrode of the plating power source 34, The plating process is started. The agitating paddle (agitator) 52 is reciprocated in parallel with the substrate W, and the plating liquid Q in the cathode chamber 12 is agitated. At the same time, nitrogen gas is supplied to the anode liquid (E) in the anode chamber (14) through the N ₂ gas supply line (33) to bubble the anode liquid (E).

While performing plating in this manner, the Sn ion concentration of the plating liquid Q is measured by the Sn ion concentration measuring instrument 74, and the measurement result is sent to the control unit 80 as a signal (measured value). The control unit 80 estimates the methane sulfonic acid concentration of the anode liquid E of the anode chamber 14 in this example and calculates the concentration of methane sulfonic acid in the anode chamber 14 from the electrolyte solution supply line 24 Supply pure water from the pure water supply line 26, or a combination thereof. That is, when the concentration of methanesulfonic acid as the free acid of the anode liquid (E) is lower than a predetermined value, an electrolyte solution containing methanesulfonic acid is supplied from the electrolyte supply line (24) to the anode chamber (14). Pure water is supplied to the anode chamber 14 from the pure water supply line 26 when it is necessary to supply Sn ions to the cathode chamber 12 at a time when the concentration of methane sulfonic acid in the anode chamber 14 is sufficiently high. The anode liquid E of the anode chamber 14 overflows into the cathode chamber 12 and Sn ions are supplied to the plating liquid Q of the cathode chamber 12.

The concentration of methanesulfonic acid as the free acid of the anode liquid E in the anode chamber 14 is controlled to be not less than 30 g / L. As a result, the high concentration Sn ions of, for example, 220 g / L to 350 g / Can be stably present as an ion of silver. When the concentration of methane sulfonic acid in the anode liquid E is high, the concentration of methane sulfonic acid in the plating liquid Q in the cathode chamber 12 is also increased by the supply of the anode liquid E, The sex is getting worse. Therefore, the concentration of methanesulfonic acid in the plating liquid Q is predetermined so as not to become higher than necessary in consideration of the actual operating conditions of the apparatus.

The concentration of methane sulfonic acid as the free acid in the plating solution Q in the cathode chamber 12 is determined by the electrolytic amount and the current efficiency at the Sn anode 32 and the amount of overflow of the anode liquid E, (Drain out) amount from the anion exchange membrane 54 and the permeation rate of methane sulfonic acid in the anion exchange membrane 54. If the concentration of methanesulfonic acid in the plating liquid Q in the cathode chamber 12 exceeds about 250 g / L, the uniformity of the film thickness in the substrate plating tends to deteriorate. Therefore, when methane sulfonic acid concentration of the plating liquid Q in the cathode chamber 12 is higher than the upper limit, when the methane sulfonic acid concentration meter 76 detects the methane sulfonic acid concentration, the dialysis tank 62 The plating liquid Q is flowed into the plating liquid dialysis line 68 having the methane sulfonic acid removed therefrom and the plating liquid Q from which methanesulfonic acid has been removed is returned to the overflow bath 36. Thereby, the concentration of methanesulfonic acid in the plating liquid Q used for plating can be adjusted within a preferable range of, for example, 60 g / L to 250 g / L, and more preferably within a range of 90 g / L to 150 g / L have.

The concentration of methanesulfonic acid as the free acid in the anode liquid E during the operation of the Sn alloy plating apparatus may be controlled based on the estimated value of the methanesulfonic acid concentration of the anode liquid E in the anode chamber 14. [ The estimated value of the methane sulfonic acid concentration is determined by the methane sulfonic acid concentration of the initial anode liquid E, the electrolytic amount and the current efficiency at the Sn anode 32, the supply amount of the electrolytic solution from the electrolytic solution supply line 24, And the transmittance of methane sulfonic acid which is permeated through the anion exchange membrane 54 and moved from the cathode chamber 12 to the anode chamber 14 is theoretically or experimentally obtained. The concentration of Sn ion and methane sulfonic acid in the anode chamber 14 can be estimated from the Sn ion dissolution curve and the anion exchange membrane transmittance of the acid depending on the electrolytic amount of the plating treatment.

As described above, before starting the operation of the Sn alloy plating apparatus, the anode chamber 14 is filled with an anode liquid (E) containing high concentration of Sn ions (for example, 220 to 350 g / L) and methanesulfonic acid ). During operation of the Sn alloy plating apparatus, the Sn ion concentration of the anode liquid E in the anode chamber 14 estimated from the electrolytic amount and electrolytic efficiency of the Sn anode reaches a predetermined threshold value (for example, 300 g / L) , The electrolytic solution is supplied from the electrolytic solution supply line 24 to the anode chamber 14 and the anode liquid E is overflowed to supply the Sn ions to the cathode chamber 12.

The supply of methane sulfonic acid lowers the Sn ion concentration of the anode liquid (E) in the anode chamber (14). After that, by continuing the plating process, the Sn ion concentration again rises and finally reaches the threshold value. In the meantime, Sn ions of the plating liquid Q are consumed by plating the substrate W. If the electrolytic efficiency of the substrate W and the Sn anode 32 is the same and the Sn ions are not discharged to the outside of the system, Sn ions consumed by the plating of the substrate W with the same amount as the Sn ions are discharged from the Sn anode 32 . Therefore, the amount of Sn ions in the entire system becomes constant. However, when the Sn ion concentration of the anode liquid (E) of the anode chamber (14) becomes high, the electrolytic efficiency decreases. Therefore, the amount of Sn ions to be supplied from the Sn anode 32 to the Sn anode is less than the amount of Sn ions consumed by plating, and Sn ions in the entire system become insufficient.

10 is a graph showing a comparison between the Sn ion concentration of the anode liquid in the theoretical anode chamber 14 converted from the electrolytic amount and the actually measured Sn ion concentration. 10, the electrolysis efficiency is almost 100% at the Sn ion concentration of the anode liquid E of about 130 g / L, but when the Sn ion concentration exceeds about 150 g / L, the electrolysis efficiency And when the Sn ion concentration is 300 g / L, the electrolytic efficiency is about 80%. That is, if the concentration of Sn ions in the anode liquid E is controlled to a high concentration of, for example, 220 g / L to 350 g / L, 10% to 20% of Sn ions will be deficient in the entire system. When the anode liquid E of the anode chamber 14 is introduced into the cathode chamber 12 by overflowing the plating liquid Q containing Sn ions into the cathode chamber 12 or the overflow tank 36, The amount of Sn ions in the entire system becomes insufficient.

Therefore, in this example, the auxiliary electrolytic bath 100 is provided to supplement Sn ions which are insufficient in the system as a whole. Simultaneously with the start of operation of the Sn alloy plating apparatus, or appropriately, electrolysis of the auxiliary electrolytic bath 100 is started. The pump 120 is driven based on the Sn ion concentration measured by the Sn ion concentration meter 74 and the anode liquid A in the anode chamber 104 having a high Sn ion concentration is supplied to the overflow tank (36). As a result, there is a shortage of Sn ions in the difference between the electrolytic efficiency of the plating of the substrate W and the electrolytic efficiency of the Sn anode 32 in the anode chamber 14, Can be supplemented by the supply of Sn ions from the auxiliary electrolytic bath (100).

When the Sn alloy plating apparatus is operated for a long period of time, the concentration of Sn ions and methanesulfonic acid in the anode liquid (E) in the anode chamber (14) may deviate from the predicted concentration. In this case, the Sn ion and methane sulfonic acid concentrations of the plating liquid Q are measured by the Sn ion concentration meter 74 and the methane sulfonic acid concentration meter 76, and the change is recorded. If the concentration tends to increase or decrease, the dissolution efficiency used for predicting the concentration in the case of Sn ions and the permeability of the film in the case of methanesulfonic acid are respectively changed, and the concentration of Sn ions and methanesulfonic acid continues to be managed do.

On the other hand, the supply of the anode liquid E containing the high concentration Sn ions of the anode chamber 14 to the cathode chamber 12 or the overflow tank 36 is performed by overflow It is preferable that the device is operated by a furnace. The reason is as follows.

If an anode liquid containing a high concentration of Sn ions is allowed to stay in a thin tube for a long time, metal adhesion (abnormal precipitation) occurs on the surface even if the wall of the tube is an insulating material. And, once the attachment of the metal is started, the metal tends to grow gradually on the surface. Further, if the feeding of the anode liquid from the anode chamber to the cathode chamber is continued in order to always flow the anode liquid in the tube, the total amount of the liquid in the cathode chamber increases, and the plating liquid Q equal to the amount of liquid to be supplied must always be discharged.

In contrast, when the anode liquid is supplied by overflow, the risk of metal adhesion is low. The anode liquid E in the anode chamber 14 is constantly stirred by the bubbling of the nitrogen gas at all times, so that it is also possible to avoid the occurrence of metal adhesion to the inner wall surface of the anode chamber 14. When the overflow is caused by the movement of methane sulfonic acid and thus the water molecules due to the electrolysis, the amount of overflow at that time is the volume of water and methane sulfonic acid permeated through the anion exchange membrane, , The total amount of the plating liquid does not change, so it is not necessary to drain the plating liquid.

Fig. 11 shows an outline of another plating tank 16a. An anode holder 30 holding a disk-shaped Sn anode 32 is accommodated in the anode chamber 14 of the plating vessel 16a. An annular anode mask 200 for limiting the area of the Sn anode 32 in contact with the anode liquid E is attached to the front surface of the anode holder 30 in close contact with the outer periphery of the Sn anode 32 have. An opening 10d is formed in the partition wall 10a on the cathode chamber side of the anode tank 10 and an anion exchange membrane 54 is attached along the edge of the opening 10d. The anion exchange membrane 54 is sandwiched between the partition member 10a and the mask member 202 which limits the region of the anion exchange membrane 54 on the side in contact with the plating liquid Q. In this manner, leakage of the liquid between the cathode chamber 12 and the anode chamber 14 can be prevented by sealing the gap by sandwiching the anion exchange membrane 54 with the partition wall 10a and the mask member 202. [

The anion exchange membrane 54 and the opening portion 10d are, for example, rectangular, and the mask member 202 is formed of a substantially rectangular ring. It is preferable that the opening dimension of the opening portion 10d and the mask member 202 is equal to or larger than the inner diameter of the anode mask 200. [ The area of the anion exchange membrane 54 that is in contact with the anode liquid E or the plating liquid Q is set to be larger than the size of the area of the Sn anode 32 that is in contact with the anode liquid E in order to suppress the total resistance between the anode and the cathode. A larger one is preferable.

The front surface of the mask member 202 is provided with an electric shielding plate 204 having an outer shape substantially identical to the outer shape of the mask member 202 and having a circular opening portion 204a shaped like a substrate W do. The diameter of the opening 204a of the electric-field shielding plate 204 is set to be smaller than the opening dimension of the mask member 202. [ Even when the thickness of the seed layer formed on the substrate becomes thin and the thickness of the outer periphery of the substrate becomes thick by providing the electric-field shielding plate 204 in the vicinity of the Sn anode 32 in the cathode chamber 12 , The film thickness distribution can be made uniform. In order to control the film thickness distribution, it is preferable that the electric-field shielding plate 204 has a mechanism for changing the opening area. The diameter of the opening 204a of the electric field shielding plate 204 is set to be equal to or smaller than the diameter of the center hole 50a of the adjusting plate 50 positioned between the substrate W and the Sn anode 32 . In this example, as the adjustment plate 50, a plate 206 having a cylindrical body 208 attached thereto is used.

When the anode liquid E in the anode chamber 14 overflows and is supplied to the cathode chamber 12, not only the Sn ions but also excess moisture are supplied so that the plating liquid in the cathode chamber 12 and the overflow bath 36 (Q) is increased. When the liquid amount of the plating liquid Q exceeds a predetermined amount, it is necessary to drain the liquid as much, which increases the cost. In order to avoid this as much as possible, in this example, a gas supply part 210 for promoting the evaporation of water is provided in the upper part of the plating tank 16a. The amount of evaporation of water from the cathode chamber 12 is equal to the amount of the anode liquid E supplied from the anode chamber 14 by the gas supply unit 210 so that the plating liquid Q in the cathode chamber 12, It is possible to stably maintain the concentration of the component of the liquid, and to eliminate or reduce the amount of liquid to be drained.

Further, in order to further reduce the amount of drainage, the plating liquid circulating line 46 may be provided with a dewatering device capable of removing only water to allow the plating liquid Q to pass through the dewatering device.

12 is a schematic view of a Sn alloy plating apparatus according to another embodiment of the present invention. 1 of this example is that the plating tank 16b is formed by surrounding the periphery of the inner tank 220 which is integral with the anode tank 10 by the overflow tank 36 and the anode tank 10 The anode liquor E in the anode chamber 14 is blocked by a dam so that the anode liquid E which overflows the upper end of the partition wall lOe, And serves as a swirling flow that flows into the overflow tank 36. That is, the anode chamber E of the predetermined liquid level H (see FIG. 9) is held in the anode chamber 14 by the partition wall (overflow dike) 10e, The excess amount of the anode liquid E flows into the overflow bath 36 surrounding the plating bath 16b by overflowing the upper end of the partition wall 10e. The Sn ions supplied to the overflow bath 36 are supplied to the cathode chamber 12 via the plating liquid circulating line 46.

13 is a schematic view of a Sn alloy plating apparatus according to another embodiment of the present invention. 1 of this example is that an anode liquid circulating line (not shown) for withdrawing a part of the anode liquid in the anode chamber 14 from the bottom portion of the anode tank 10 and returning it to the upper portion of the anode tank 10 230 and a pump 232 and a methane sulfonic acid concentration meter 234 are provided in the anode liquid circulation line 230.

According to this example, the pump 232 is driven to circulate the anode liquid E in the anode chamber 14 through the anode liquid circulation line 230 while the methane sulfonic acid concentration of the anode liquid E is increased to the methane sulfonic acid concentration Can be measured at all times or regularly by the meter 234.

14 is a schematic view of a Sn alloy plating apparatus according to another embodiment of the present invention. 1 in that the drain line 28 of the plating bath 16 and the electrolytic solution supply line 112 of the auxiliary electrolytic bath 100 shown in Fig. 1 are installed in the pump 240 And the Sn ion supply line 114 extending from the anode chamber 104 of the auxiliary electrolyzer 100 is connected to the upper portion of the anode chamber 14 of the plating tank 16 by a connection line 242 It is in point.

According to this example, the anode liquid E in the anode chamber 14 of the plating tank 16 is used as an electrolyte to be supplied to the anode chamber 104 of the auxiliary electrolytic bath 100, The anode liquid A having a high Sn ion concentration in the chamber 104 can be returned to the anode chamber 14 of the plating tank 16. [ Accordingly, it is possible to supply Sn ions which are insufficient.

15 is a schematic diagram of a Sn alloy plating apparatus according to still another embodiment of the present invention having a plurality of plating tanks. As shown in FIG. 15, this Sn alloy plating apparatus has a plurality of plating vessels 250 and a single reservoir vessel 252 having the same configuration as the plating vessel 16 shown in FIG. The anode chamber of the plating bath 250 and the reservoir tank 252 are connected to the anode liquid supply line 254 and the anode liquid recovery line 256, respectively. In the anode liquid supply line 254, one pump 258a is provided. The anode liquid supply line 254 branches off from the downstream side of the pump 258a and extends to each plating bath 250. A switching valve 260a is provided at each branch. The anode liquid recovery line 256 is also provided with a single pump 258b. The anode liquid recovery line 256 branches off from the upstream side of the pump 258b and extends to each plating bath 250. A switching valve 260b is provided in each branching portion.

A heater 262 for heating the anode liquid is provided in the reservoir tank 252 in order to raise the temperature of the anode liquid to increase the electrolysis efficiency. The anode liquid is maintained in a temperature range of, for example, 26 캜 to 40 캜.

According to this example, by circulating the anode liquid between the anode chamber of the plating bath 250 and the reservoir tank 252, the Sn ion concentration and the methane sulfonic acid concentration of the anode liquid in the anode chamber of each plating bath 250 are all the same . Thus, it is possible to avoid the complication associated with individually managing the Sn ion concentration and the methane sulfonic acid concentration of the anode liquid for each plating bath 250.

In this example, two pumps 258a and 258b are provided to switch the switching valves 260a and 260b so that the anode liquid circulates between the reservoir tank 252 and the anode chamber of one plating bath 250 . Thus, the liquid management of the anode chamber of each plating bath 250 is facilitated. A pump for circulating the anode liquid may be provided between the anode chamber of each plating vessel 250 and the reservoir tank 252 to circulate the anode liquid independently of the anode chamber of the other plating vessel 250.

In addition, as described above, due to the shortage of Sn ions caused by the difference in the electrolytic efficiency of plating on the substrate and the electrolytic efficiency in the Sn anode in the anode chamber and the lack of Sn ions due to drainage from the plating bath, An auxiliary electrolyzer having the same structure as the auxiliary electrolyzer 100 shown in Fig. 1 may be provided in the reservoir tank 252 to compensate for insufficient Sn ions.

Further, the entire Sn alloy plating apparatus is provided with one outer tank (overflow tank) and a plurality of cathode chambers, and the anode liquid is supplied from the outer tank through the pump chamber to the cathode chamber from below the cathode chamber, And the liquid is returned to the outer tank by the outer tank, thereby facilitating the liquid management of the cathode chamber.

Although the embodiment of the present invention has been described so far, it is needless to say that the present invention is not limited to the above-described embodiment, but may be practiced in various different forms within the scope of the technical idea.

10: anode tank 10a, 10e: partition wall
12: cathode chamber 14: anode chamber
16, 16a, 16b: Plating tank 18: Plating solution supply source
20: plating liquid supply line 22: substrate holder
23: anode liquid supply line 24: electrolytic solution supply line
26: Pure water supply line 28: Drain line
30: anode holder 32: Sn anode
33: N ₂ gas supply line 36: overflow tank
46: plating liquid circulation line 54, 60: anion exchange membrane
62: dialysis bath 68: plating solution dialysis line
74: Sn ion concentration meter 76: Methane sulfonic acid concentration meter
80: controller 82: liquid level sensor
100: auxiliary electrolytic bath 102: cathode tank
102a: partition wall 104: anode chamber
106: cathode chamber 108: anion exchange membrane
110: Anode liquid supply line 112: Electrolyte supply line
114: Sn ion supply line 116: anode holder
118: Sn anode 122: cathode solution supply line
124: Drain line 126: Cathode holder
128: cathode 200: anode mask
202: mask member 204: electric field shield plate
210: gas supply unit 230: anode liquid circulation line
234: Methane sulfonic acid concentration meter 250: Plating tank
252: reservoir tank 254: anode liquid supply line
256: anode liquid recovery line

Claims (16)

A Sn alloy plating apparatus for exposing an alloy of a metal precious than Sn and Sn on a surface of a substrate,
The inside of the plating bath is filled with a cathode chamber holding a Sn alloy plating solution and immersing a substrate to be a cathode in the Sn alloy plating solution and an anode liquid containing an acid forming a complex with Sn ions and divalent Sn ions, An anion exchange membrane for separating the Sn anode into an anode chamber immersed in the anode solution,
An electrolyte solution supply line for supplying an electrolyte containing the acid into the anode chamber;
Wherein the electrolyte solution supply line supplies the electrolyte solution into the anode chamber so that the concentration of Sn ions in the anode solution in the anode chamber is not less than a predetermined value and the concentration of the acid is not lower than a tolerance, And the anode solution in the anode chamber is supplied to the Sn alloy plating solution. The Sn alloy plating apparatus according to claim 1, wherein the electrolyte solution supply line overflows the anode chamber by supplying the electrolyte solution into the anode chamber and supplies the anode solution to the Sn alloy plating solution. The plating apparatus according to claim 1, further comprising: an overflow tank for storing a plating solution overflowing the cathode chamber;
A plating solution circulating line for returning the Sn alloy plating solution in the overflow bath to the cathode chamber,
Wherein the Sn alloy plating apparatus further comprises: The Sn alloy plating apparatus according to claim 1, further comprising a pure water supply line for supplying pure water into the anode chamber. The Sn alloy plating apparatus according to claim 1, further comprising an acid concentration meter for measuring the concentration of the acid in the anode liquid in the anode chamber. 2. The Sn alloy plating apparatus according to claim 1, further comprising a dialysis vessel for extracting a part of the Sn alloy plating liquid from the cathode chamber and for removing at least a part of the acid from the Sn alloy plating liquid and returning it to the cathode chamber. . The Sn alloy plating apparatus according to claim 1, further comprising an N ₂ gas supply line for bubbling the anode liquid by supplying nitrogen gas to the anode liquid in the anode chamber. The secondary battery according to claim 1, further comprising: a secondary anode chamber which is isolated by an anion exchange membrane and which has an auxiliary cathode chamber and which is immersed in the anode solution in the secondary anode chamber and an auxiliary cathode immersed in the cathode solution in the secondary cathode chamber And an auxiliary electrolyzer for supplying an anode liquid in the auxiliary anode chamber to the Sn alloy plating liquid, the Sn electrolytic bath having an increased Sn ion concentration. A Sn alloy plating method for electrodepositing an alloy of a metal precious than Sn and Sn on the surface of a substrate,
A plating bath in which the inside was separated from the cathode chamber and the anode chamber by an anion exchange membrane was prepared,
A Sn alloy plating solution is contained in the cathode chamber, the substrate is immersed in the Sn alloy plating solution,
A Sn anode containing Sn as a material is accommodated in the anode chamber and an anode liquid containing an acid forming a complex with Sn ion and divalent Sn ion is contained in the anode chamber,
Wherein an anode liquid in the anode chamber is supplied to the anode chamber such that the concentration of the acid in the anode chamber is equal to or higher than a predetermined value and the concentration of the acid is not lower than a tolerance, Applying a voltage between the cathode and the Sn anode while supplying the Sn alloy to the surface of the substrate while supplying the Sn alloy to the alloy plating solution. The Sn alloy plating method according to claim 9, wherein an anode solution increased by supplying the electrolyte solution into the anode chamber is supplied to the Sn alloy plating solution by overflowing the anode chamber. 10. The Sn alloy plating method according to claim 9, wherein the Sn alloy plating solution in the cathode chamber is circulated. The Sn alloy plating method according to claim 9, wherein the supply amount of the electrolytic solution or pure water to the anode chamber is controlled based on the concentration of the acid in the anode liquid in the anode chamber. 10. The method according to claim 9, wherein the concentration of the acid in the anode liquid is selected so that the concentration of the acid in the initial anode liquid, the electrolytic amount and the current efficiency in the Sn anode, the supply amount of the electrolytic solution and the anion- And the transmittance of the acid which is transferred to the surface of the Sn alloy. 10. The Sn alloy plating method according to claim 9, wherein a part of the Sn alloy plating liquid is extracted from the cathode chamber, and at least a part of the acid is removed from the Sn alloy plating liquid and returned to the cathode chamber. 10. The Sn alloy plating method according to claim 9, wherein a nitrogen gas is supplied into the anode liquid in the anode chamber to bubble the anode liquid. The method according to claim 9, wherein a voltage is applied between the auxiliary Sn anode immersed in the anode liquid in the auxiliary anode chamber of the auxiliary electrolytic cell and the auxiliary cathode immersed in the cathode liquid in the auxiliary cathode chamber isolated from the auxiliary anode chamber, Wherein the anode solution in the auxiliary anode chamber having increased Sn ion concentration is supplied to the Sn alloy plating solution.

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