Metal ion feeding system for electrolytic plating apparatus and metal ion feeding method to electrolytic plating apparatus

Abstract

An object is to provide a metal ion feeding system in which dilution of a plating solution in a plating solution circulation chamber is suppressed.A metal ion feeding system for an electrolytic plating apparatus, the metal ion feeding system includingan anode chamber,an anode disposed in the anode chamber,a cathode chamber,a cathode disposed in the cathode chamber,a plating solution circulation chamber placed between the anode chamber and the cathode chamber,a first diaphragm placed between the anode chamber and the plating solution circulation chamber, anda second diaphragm placed between the cathode chamber and the plating solution circulation chamber,wherein the plating solution circulation chamber includes an outlet for bleeding a plating solution to an electrolytic plating apparatus, and an inlet for receiving the plating solution from the electrolytic plating apparatus so that the plating solution is circulatable,a rate of diffusion osmosis of water in the second diaphragm is higher than a rate of diffusion osmosis of water in the first diaphragm,an anolyte containing an ion of the same metal as the metal included in the anode is packed in the anode chamber,a catholyte is packed in the cathode chamber, andthe catholyte has a higher osmol concentration than an osmol concentration in the plating solution in the plating solution circulation chamber.

Description

TECHNICAL FIELDThe present invention relates to a metal ion feeding system for an electrolytic plating apparatus and a metal ion feeding method to an electrolytic plating apparatus.BACKGROUND ARTIn order to apply various types of plating, such as Cu, Sn, a SnAg alloy, and Ni, to a surface of a structure such as a metal plate or a substrate, an electrolytic plating apparatus including a plating tank in which a plating solution is accommodated is used. Since a metal ion (Cu2+, Sn2+, or the like) included in such a plating solution is consumed by carrying out plating treatment, it is necessary to replenish a metal ion to such a plating solution in such a plating tank.PTL 1 discloses, as an apparatus for replenishing a metal ion to a plating solution in a plating tank, a metal enrichment cell including an anode region and a cathode region. In PTL 1, a plating solution is circulated between the metal enrichment cell and a plating tank in an electrolytic plating apparatus, to replenish a metal ion to the plating solution in the plating tank.CITATION LISTPatent LiteraturePTL 1: U.S. Pat. No. 9,637,836SUMMARY OF INVENTIONTechnical ProblemWhen a metal ion feeding system with a 3-chamber structure cell (anode chamber / plating solution circulation chamber / cathode chamber) partitioned with two diaphragms, as described in PTL 1, is used, a metal ion may be fed from the anode chamber to the plating solution in the plating solution circulation chamber. In this case, water also moves together during electro-osmosis of the metal ion from the anode chamber to the plating solution circulation chamber via the diaphragm. In this regard, electro-osmosis of a hydrogen ion from the cathode chamber to the plating solution circulation chamber via the diaphragm also occurs, and thus water also moves together during electro-osmosis of the hydrogen ion.The present inventors have made intensive studies about the above metal ion feeding system, and thus have found that the amount of movement of water in association with metal ion electro-osmosis may be larger than the amount of movement of water in association with hydrogen ion electro-osmosis, thereby diluting the plating solution in the plating solution circulation chamber. In an electrolytic plating apparatus, the plating solution usually retains a constant concentration with water replenished corresponding to a decreased plating solution due to evaporation or the like. However, if water is excessively fed to the plating solution in the plating solution circulation chamber, due to the difference between the above amounts of movement of water, the plating solution is diluted. It is not preferable to feed the diluted plating solution to the electrolytic plating apparatus, because the concentration of the plating solution in the electrolytic plating apparatus is gradually diluted. In particular, in order to enhance the production ability of the plating apparatus, the amount of metal ion feeding is required to be larger. In this case, the amount of electro-osmosis of water to the plating solution circulation chamber tends to be large as compared with the amount of evaporation of the plating solution, and such a tendency is particularly problematic.In view of such circumstances, a first object of the present invention is to provide a metal ion feeding system in which dilution of a plating solution in a plating solution circulation chamber is suppressed.When the metal ion feeding system with a 3-chamber structure cell (anode chamber / plating solution circulation chamber / cathode chamber) partitioned with two diaphragms, as described in PTL 1, is used, the operation of the electrolytic plating apparatus may be stopped for maintenance or the like.The present inventors have progressively made intensive studies about the above metal ion feeding system, and as a result, have found that, during stopping of the operation of the electrolytic plating apparatus as described above, cation exchange by diffusion may occur between the anode chamber and the plating solution circulation chamber via the diaphragm, to cause incorporation of a metal ion in the plating solution in the plating solution circulation chamber, into the anode chamber. In a case where the ionization tendency of the metal ion incorporated into the anode chamber is smaller than the ionization tendency of an anode, replacement reaction occurs on an anode surface to precipitate a metal derived from the metal ion incorporated. Such precipitation of the metal on the anode surface causes passivation of the anode surface to inhibit electrolyzation (electrolysis) in the metal ion feeding system. For example, in a case where an Ag+ ion is used as the metal ion included in the plating solution and Sn is used as the anode, incorporation of the Ag+ ion in the plating solution into the anode chamber, if occurs, can cause the occurrence of the following reaction to result in passivation of the anode surface, because the ionization tendency of Sn is larger than the ionization tendency of Ag.In view of such circumstances, a second object of the present invention is to provide a metal ion feeding method that allows passivation of an anode surface due to a metal ion incorporated from a plating solution circulation chamber to be suppressed.The metal ion feeding system with a 3-chamber structure cell (anode chamber / plating solution circulation chamber / cathode chamber) partitioned with two diaphragms, as described in PTL 1, may include a soluble anode disposed in the anode chamber, to feed a metal ion from the soluble anode into an anolyte by electrolyzation.As electrolyzation progresses, a hydrogen ion (H+) included in the anolyte in the anode chamber passes through a diaphragm and moves to the plating solution circulation chamber, thereby resulting in a reduction in hydrogen ion concentration in the anolyte and an increase in pH. Such an increase in pH may cause the occurrence of sludge derived from the metal ion, in the anolyte and / or on an adjacent diaphragm to the anode chamber.For example, in a case where the metal included in the soluble anode is Sn and Sn2+ is fed into the anolyte, the pH of the anolyte, if larger than a certain value, may cause the following reaction to generate Sn(OH)2 as sludge.Since such sludge generation inhibits the reaction of electrolyzation, such sludge generation is desired to be suppressed. Such sludge is often low in solubility in a neutral region, and it is necessary for stable dissolution of a metal ion in the anolyte to maintain the pH of the anolyte in the anode chamber at a certain value or less.Examples of a method for prevention of generation of such sludge include a method including periodically bleeding one portion of the anolyte and adding an acid such as MSA (methanesulfonic acid) to the anolyte. However, this method also causes a metal ion (for example, Sn2+) to be simultaneously bled during one portion of the anolyte is bled, leading to an increase in cost. In addition, a need for management of the anolyte occurs, leading to complication.Examples of another method for prevention of generation of such sludge include a method including separately additionally disposing an insoluble anode in the anode chamber to control the insoluble anode by another power source. However, this method leads to an increase in cost because control with another power source is added.

[0017] In view of such circumstances, a third object of the present invention is to provide a metal ion feeding system in which sludge generation is controlled in an anolyte in an anode chamber and on a diaphragm.Solution to Problem

[0018] The present inventors have made intensive studies in order to solve the above problems, and as a result, have found that at least some of the above problems can be solved by the following configurations.

[0019] (1) A metal ion feeding system for an electrolytic plating apparatus, the metal ion feeding system including

[0020] an anode chamber,

[0021] an anode disposed in the anode chamber,

[0022] a cathode chamber,

[0023] a cathode disposed in the cathode chamber,

[0024] a plating solution circulation chamber placed between the anode chamber and the cathode chamber,

[0025] a first diaphragm placed between the anode chamber and the plating solution circulation chamber, and

[0026] a second diaphragm placed between the cathode chamber and the plating solution circulation chamber,

[0027] wherein the plating solution circulation chamber includes an outlet for bleeding a plating solution to an electrolytic plating apparatus, and an inlet for receiving the plating solution from the electrolytic plating apparatus so that the plating solution is circulatable,

[0028] a rate of diffusion osmosis of water in the second diaphragm is higher than a rate of diffusion osmosis of water in the first diaphragm,

[0029] an anolyte containing an ion of the same metal as the metal included in the anode is packed in the anode chamber,

[0030] a catholyte is packed in the cathode chamber, and

[0031] the catholyte has a higher osmol concentration than an osmol concentration in the plating solution in the plating solution circulation chamber.

[0032] (4) A metal ion feeding method to an electrolytic plating apparatus, the method including

[0033] (i) a step of circulating a plating solution containing metal ions between a plating solution circulation chamber and an electrolytic plating apparatus, to feed the metal ions to the electrolytic plating apparatus, and

[0034] (ii) a step of not performing feeding of the metal ions to the electrolytic plating apparatus, in which the step is to replace an inside of the plating solution circulation chamber with a liquid substantially free of at least one of the metal ions.

[0035] (9) A metal ion feeding system for an electrolytic plating apparatus, the metal ion feeding system including

[0036] an anode chamber that includes an anode and that is packed with an anolyte,

[0037] a cathode chamber that includes a cathode and that is packed with a catholyte,

[0038] a first plating solution circulation chamber defined with a first diaphragm and a second diaphragm and placed between the anode chamber and the cathode chamber, and

[0039] one or more stacked module placed between the first plating solution circulation chamber and the cathode, the stacked module including an anolyte chamber packed with an anolyte and a second plating solution circulation chamber defined with a third diaphragm and a fourth diaphragm,

[0040] wherein the third diaphragm is formed from the same material as that of the first diaphragm, and the fourth diaphragm is formed from the same material as that of the second diaphragm,

[0041] the first plating solution circulation chamber and the second plating solution circulation chamber each include an outlet for bleeding a plating solution to an electrolytic plating apparatus, and an inlet for receiving the plating solution from the electrolytic plating apparatus so that the plating solution is circulatable, and

[0042] the anolyte chamber includes an outlet for bleeding the anolyte from the anolyte chamber and an inlet for receiving the anolyte in the anolyte chamber so that the anolyte in the anode chamber is capable of being in fluid communication.BRIEF DESCRIPTION OF DRAWINGS

[0043] FIG. 1 is a cross-sectional view illustrating the entire configuration of a metal ion feeding system;

[0044] FIG. 2 is an enlarged view of the vicinity of a cathode chamber in a metal ion feeding system;

[0045] FIG. 3 is a cross-sectional view illustrating a cell structure of a metal ion feeding system;

[0046] FIG. 4 is a side view schematically illustrating a configuration of a plating tank;

[0047] FIG. 5A is a view illustrating electrolyzation (metal ion feeding) with a 3-chamber cell;

[0048] FIG. 5B is a view of a step of stopping electrolyzation and bleeding a plating solution from a plating solution circulation chamber 1200;

[0049] FIG. 5C is a view of a step of replacing the inside of the plating solution circulation chamber 1200 with a liquid substantially free of at least one of metal ions included in the plating solution in the state of electrolyzation stopped;

[0050] FIG. 5D is a view of a step of standing in a state where electrolyzation is stopped and the plating solution circulation chamber 1200 is packed with the liquid substantially free of at least one of metal ions;

[0051] FIG. 5E is a view of a step of bleeding the liquid substantially free of at least one of metal ions from the plating solution circulation chamber 1200 in the state of electrolyzation stopped;

[0052] FIG. 6 is a cross-sectional view illustrating the entire configuration of a metal ion feeding system;

[0053] FIG. 7 is a cross-sectional view illustrating the situation of ion movement in a metal ion feeding system;

[0054] FIG. 8 is a photograph of a 3-chamber cell used in Examples;

[0055] FIG. 9A shows a graph representing the change in amount (mol) of Cu in an anolyte during a test;

[0056] FIG. 9B shows a graph representing the change in amount (mol) of Cu in a plating solution during a test;

[0057] FIG. 9C shows a graph representing the change in amount (mol) of Cu in a catholyte during a test;

[0058] FIG. 10A shows a graph representing the change in amount (Liter) of liquid of an anolyte during a test;

[0059] FIG. 10B shows a graph representing the change in amount (Liter) of liquid of a plating solution during a test;

[0060] FIG. 10C shows a graph representing the change in amount (Liter) of liquid of a catholyte during a test;

[0061] FIG. 11 is a graph representing the change in pH of an anolyte during a test;

[0062] FIG. 12 is a photograph illustrating the appearance of a cathode after a test;

[0063] FIG. 13A shows a graph relating to the change in concentration (g / L) of Cu2+ or H2SO4 in an anolyte in a case where the concentration of a catholyte (H2SO4) is set to 100 g / L;

[0064] FIG. 13B shows a graph relating to the change in concentration (g / L) of Cu2+ or H2SO4 in a plating solution in a case where the concentration of a catholyte (H2SO4) is set to 100 g / L;

[0065] FIG. 13C shows a graph relating to the change in concentration (g / L) of Cu2+ or H2SO4 in a catholyte in a case where the concentration of a catholyte (H2SO4) is set to 100 g / L;

[0066] FIG. 14 is a graph relating to the change in amount (L) of each liquid (anolyte, plating solution, catholyte) in a case where the concentration of a catholyte is set to 100 g / L;

[0067] FIG. 15A shows a graph relating to the change in concentration (g / L) of Cu2+ or H2SO4 in an anolyte in a case where the concentration of a catholyte is set to 230 g / L;

[0068] FIG. 15B shows a graph relating to the change in concentration (g / L) of Cu2+ or H2SO4 in a plating solution in a case where the concentration of a catholyte is set to 230 g / L;

[0069] FIG. 15C shows a graph relating to the change in concentration (g / L) of Cu2+ or H2SO4 in a catholyte in a case where the concentration of a catholyte is set to 230 g / L;

[0070] FIG. 16 is a graph relating to the change in amount (L) of each liquid (anolyte, plating solution, catholyte) in a case where the concentration of a catholyte is set to 230 g / L;

[0071] FIG. 17A shows a graph relating to the change in concentration (g / L) of Cu2+ or H2SO4 in an anolyte in a case where the concentration of a catholyte is set to 300 g / L;

[0072] FIG. 17B shows a graph relating to the change in concentration (g / L) of Cu2+ or H2SO4 in a plating solution in a case where the concentration of a catholyte is set to 300 g / L;

[0073] FIG. 17C shows a graph relating to the change in concentration (g / L) of Cu2+ or H2SO4 in a catholyte in a case where the concentration of a catholyte is set to 300 g / L;

[0074] FIG. 18 is a graph relating to the change in amount (L) of each liquid (anolyte, plating solution, catholyte) in a case where the concentration of a catholyte is set to 300 g / L;

[0075] FIG. 19A shows a graph relating to the change in concentration (g / L) of Cu2+ or H2SO4 in an anolyte in simulation.

[0076] FIG. 19B shows a graph relating to the change in concentration (g / L) of Cu2+ or H2SO4 in a plating solution in simulation.

[0077] FIG. 19C shows a graph relating to the change in concentration (g / L) of Cu2+ or H2SO4 in a catholyte in simulation.

[0078] FIG. 20 is a graph relating to the change in amount (L) of each liquid (anolyte, plating solution, catholyte) in simulation; and

[0079] FIG. 21 is a cross-sectional view of the entire configuration of a 3-chamber cell 2100 and a plating cell (plating tank) 10 used in Test Examples 4 to 6.DESCRIPTION OF EMBODIMENTS

[0080] Hereinafter, the detail of the present invention is described.

[0081] The description of constituent requirements described below may be made based on a representative embodiment of the present invention, but the present invention is not restricted to such an embodiment.

[0082] Herein, a numerical value range represented with “X to Y” means a range including numerical values represented by X and Y as the lower limit value and the upper limit value, respectively.

[0083] In the following description, a part having the same function and / or structure may be marked with the same symbol and the description thereof may be omitted.1. First Embodiment

[0084] A metal ion feeding system for an electrolytic plating apparatus of the first embodiment is

[0085] a metal ion feeding system for an electrolytic plating apparatus, the metal ion feeding system including

[0086] an anode chamber,

[0087] an anode disposed in the anode chamber,

[0088] a cathode chamber,

[0089] a cathode disposed in the cathode chamber,

[0090] a plating solution circulation chamber placed between the anode chamber and the cathode chamber,

[0091] a first diaphragm placed between the anode chamber and the plating solution circulation chamber, and

[0092] a second diaphragm placed between the cathode chamber and the plating solution circulation chamber,

[0093] wherein the plating solution circulation chamber includes an outlet for bleeding a plating solution to an electrolytic plating apparatus, and an inlet for receiving the plating solution from the electrolytic plating apparatus so that the plating solution is circulatable,

[0094] a rate of diffusion osmosis of water in the second diaphragm is higher than a rate of diffusion osmosis of water in the first diaphragm,

[0095] an anolyte containing an ion of the same metal as the metal included in the anode is packed in the anode chamber,

[0096] a catholyte is packed in the cathode chamber, and

[0097] the catholyte has a higher osmol concentration than an osmol concentration in the plating solution in the plating solution circulation chamber.

[0098] The metal ion feeding system of the present embodiment, in which the catholyte has a higher osmol concentration than the osmol concentration in the plating solution in the plating solution circulation chamber, can thus allow for suppression of dilution of the plating solution in the plating solution circulation chamber.

[0099] According to the first embodiment of the present invention, there is provided a metal ion feeding system in which dilution of a plating solution in a plating solution circulation chamber is suppressed.

[0100] Hereinafter, one mode of the metal ion feeding system of the present embodiment is described.

[0101] FIG. 1 is a cross-sectional view illustrating the entire configuration of the metal ion feeding system.

[0102] In FIG. 1, a metal ion feeding system 2000 includes an anode chamber 1100, a plating solution circulation chamber 1200, and a cathode chamber 1300. A first diaphragm 1400 is placed between the anode chamber 1100 and the plating solution circulation chamber 1200. A second diaphragm 1500 is placed between the plating solution circulation chamber 1200 and the cathode chamber 1300. An anode 1600 is disposed and an anolyte is packed in the anode chamber 1100. A cathode 1700 is disposed and a catholyte is packed in the cathode chamber 1300. The plating solution circulation chamber 1200 includes an outlet 1210 for bleeding a plating solution to an electrolytic plating apparatus, and an inlet 1220 for receiving the plating solution from the electrolytic plating apparatus. As indicated by arrows, the plating solution is bled from the plating solution circulation chamber 1200 to the electrolytic plating apparatus, and flows from the electrolytic plating apparatus into the plating solution circulation chamber 1200. An external power source 1900 is connected to the anode 1600 and the cathode 1700. In order to stir the anolyte, a gas 1850 such as air, nitrogen, or argon is desirably sent to the anolyte via, for example, a gas diffusion tube 1800. In a case where the anolyte contains an easily-oxidizable metal ion such as a Sn(II) ion, an inert gas such as nitrogen or argon is preferably used as the gas 1850. Any other stirring unit such as a paddle or a jet nozzle can also be used instead of or in addition to the gas diffusion tube 1800.

[0103] In the metal ion feeding system, the rate of diffusion osmosis of water in the second diaphragm 1500 is higher than the rate of diffusion osmosis of water in the first diaphragm 1400. For example, preferably, a cation exchange membrane is used as the first diaphragm and a hydrogen ion permselective membrane or a bipolar membrane is used as the second diaphragm.

[0104] The followings are used as respective constituent components in the metal ion feeding system 2000 of FIG. 1.

[0105] First diaphragm 1400: fluorine-based cation exchange membrane, second diaphragm 1500: hydrogen ion permselective membrane or bipolar membrane, anode 1600: Cu ball, anolyte: CuSO4 solution (partially containing H2SO4) (pH 1.5 to 3.5), cathode 1700: Pt / Ti (Pt-coating, lath-shaped Ti mesh), catholyte: H2SO4 solution

[0106] In a case where a voltage is applied to the anode 1600 and the cathode 1700 by the external power source 1900, Cu contained in the anode 1600 is ionized to Cu2+, and Cu2+ is released into the anolyte. Cu2+ released into the anolyte is affected by the potential difference and thus passes through the first diaphragm 1400 being a cation exchange membrane and moves to the plating solution in the plating solution circulation chamber 1200. When 1 mol of Cu2+ moves to the plating solution, n mol of water also moves along with Cu2+ (movement of water by electro-osmosis in association with movement of the ion) (designated as “Cu2+(H2O)n” in FIG. 1).

[0107] H+ present in the anolyte is also affected by the potential difference and thus passes through the first diaphragm 1400 and moves to the plating solution in the plating solution circulation chamber 1200. When H+ moves to the plating solution, water also moves along with H+. In this regard, the pH is adjusted to 1.5 to 3.5 by allowing the sulfuric acid concentration in the anolyte to be sufficiently low in the metal ion feeding system 2000 of FIG. 1. Therefore, the amount of movement of H+ from the anolyte to the plating solution is extremely small as compared with the amount of movement of Cu2+, and the movement of water in association with H+ is almost ignorable.

[0108] H+ present in the catholyte accepts an electron from the cathode 1700, and thus a hydrogen gas (H2) is generated on a surface of the cathode 1700. H+ present in the plating solution is affected by electro-osmosis, and thus passes through the second diaphragm 1500 being a hydrogen ion permselective membrane or a bipolar membrane and moves to the catholyte in the cathode chamber 1300. When 1 mol of H+ moves to the catholyte, m mol of water also moves along with H+ (movement of water by electro-osmosis in association with movement of the ion) (designated as “H+ (H2O) m” in FIG. 1).

[0109] The second diaphragm 1500 is low in permeability of Cu2+, and therefore the amount of movement of Cu2+ from the plating solution to the catholyte is extremely small and Cu2+ stays in the plating solution.

[0110] In the present embodiment, the catholyte has a higher osmol concentration than the osmol concentration (the concentration of the entire solute) in the plating solution in the plating solution circulation chamber. Accordingly, movement of water due to diffusion osmosis, from the plating solution to the catholyte, occurs (designated as “H2O” (arrow expending from plating solution to catholyte) in FIG. 1).

[0111] The plating solution circulation chamber 1200 is connected to a plating tank of the electrolytic plating apparatus, and the plating solution is circulated between the plating solution circulation chamber 1200 and the plating tank. Cu2+ moves from the anolyte chamber as described above, thereby replenishing Cu2+ being a metal ion to the plating solution in the plating solution circulation chamber 1200. Cu2+ in the plating solution is then carried from the plating solution circulation chamber 1200 to the plating tank, and used as a raw material of plating treatment. The operation of the metal ion feeding system can be thus performed to operate the electrolytic plating apparatus under metal ion feeding to the electrolytic plating apparatus, thereby allowing plating treatment to be continuously performed without stopping of the electrolytic plating apparatus.

[0112] The present inventors have made intensive studies, and thus have found that the molar ratio (n:m) of the amount (n) of electro-osmosis of water from the anolyte to the plating solution, in association with Cu2+, and the amount (m) of electro-osmosis of water from the plating solution to the catholyte, in association with H+, is about 8:3 under usual operation conditions (liquid temperature: 20 to 40° C., electric current density of diaphragm: about 3 to 6 ASD) in the metal ion feeding system of FIG. 1. In this case, the amount of water flowing into the plating solution is larger than the amount of water flowing out of the plating solution, and thus the plating solution is diluted with water. Such dilution of the plating solution is not preferred because the composition of the plating solution fed to the electrolytic plating apparatus varies.

[0113] The present inventors have found that the above problem can be solved by allowing the osmol concentration in the catholyte to be higher than the osmol concentration in the plating solution in the plating solution circulation chamber 1200. In general, the osmotic pressure is developed by the difference in osmol concentration, and thus water osmoses from the lower concentration side toward the higher concentration side. Accordingly, the osmol concentrations in the catholyte and the plating solution can be set as described above to promote movement of water due to diffusion osmosis from the plating solution to the catholyte. Thus, movement of water due to diffusion osmosis can be promoted to let out water excessively present in the plating solution, to the catholyte, and thus suppress dilution of the plating solution. Herein, suppression of dilution of the plating solution means that progression of dilution of the plating solution is delayed or dilution of the plating solution is prevented.

[0114] The relationship of the osmol concentrations in the metal ion feeding system of FIG. 1 is described in detail with reference to the following.

[0115] Table 1 summarizes the chemical equilibrium of each reaction in the metal ion feeding system.TABLE 1KaChemical equilibrium(literature value)H2SO4 ⇔ H+ + HSO4−1000Almost completely ionizedHSO4−⇔ H+ + SO42−0.0102Only this equilibrium reactionhas to be considered with respectto H+ concentrationCu2+ + H2O ⇔ CuOH+ + H+4.57 × 10−8Almost present as Cu2+

[0116] Formulae (1) and (2) described below are established under the assumption that the total CuSO4 concentration is Ac and the total H2SO4 concentration is As.

[0117] Ions in electrolytic solutions generally achieve electroneutrality, and thus formula (3) described below is established.

[0118] In the formula (3), [OH−] is substantially ignorable in the case of an acidic solution.

[0119] Accordingly, the osmol concentrations (Osm) can be represented as follows.

[0120] If the total CuSO4 concentration, the total H2SO4 concentration, and the hydrogen ion concentration (pH) in the solution are known from the above formulae, the osmol concentrations can be determined.

[0121] While the hydrogen ion concentration (pH) is required for formula (3), the pH is 0 or less and cannot be measured, for example, when the sulfuric acid concentration in the copper sulfate plating solution is more than 1 mol / L. It is considered that [HSO4−] is almost not dissociated in the case of a pH of 0 or less, and therefore the following formula may be regarded as being established.

[0122] Hereinafter, each configuration of the metal ion feeding system of the present embodiment is described in more detail.(Anode Chamber)

[0123] The anode chamber can accommodate the anode and the anolyte.

[0124] The volume (size) of the anode chamber is not particularly limited, and an optimal size can be appropriately selected depending on a required rate of metal ion feeding (amount of electrolysis per time) and the size of the anode accommodated. The anode chamber preferably includes a liquid level sensor and is connected with a pure water feeding line.

[0125] Water can be replenished into the anode chamber via the pure water feeding line. Pure water can be replenished into the anode chamber in an amount corresponding to the amount of water that is electrolyzed and thus serves as electro-osmotic water to permeate through the first diaphragm and flow out to the plating solution circulation chamber, or the amount of water decreased by evaporation of the anolyte, thereby suppressing the change in concentration in the anolyte.(Anode)

[0126] The anode is disposed in the anode chamber. The anode used here is preferably a soluble anode. A soluble anode and an insoluble anode can also be used in combination. A soluble anode and an insoluble anode can be used in combination, thereby suppressing an increase in pH of the anolyte due to electrolysis, as compared with the case of no use of any insoluble anode. Accordingly, the soluble anode can be prevented from being lowered in solubility.

[0127] The metal included in the anode can be appropriately set depending on the type of a metal to be plated. The metal included in the anode is not particularly limited, and Cu, Sn, Pb, SnPb, Ni, Ag, or Bi can be preferably used. Among them, Cu can be particularly preferably used. For the purpose of an increase in solubility of the anode, or for the purpose of suppression of undesirable reaction with a plating solution component, an anode with a small amount of impurities added thereto can also be used. For example, in the case of application to copper sulfate plating, a phosphorus-containing anode can be suitably used.

[0128] The shape of the anode is not particularly limited, and each shape of a ball, a disc, a slab, a rod, or a cylinder can be adopted.

[0129] The anode may be configured from one or plural members. For example, the anode used here may be one plate-shaped (for example, rectangular plate-shaped or round plate-shaped) anode, or can be in the form of plural anode pieces (for example, ball-shaped, grain-shaped, or rod-shaped) accommodated in a conductive case. For example, the anode may be in the form of plural Cu balls. In a case where such plural anode pieces are used, the influence on electrolysis reaction in a case where the anode is consumed and thus changed in shape and size is small. In a case where such plural anode pieces are accommodated in a conductive case and then used, a fresh anode in an amount corresponding to the amount of the anode consumed may be refilled in the conductive case and it is unnecessary to stop any apparatus for exchange of the anode. The material used for packing the anode is a metal not causing oxidation, elution, and the like by electrode reaction, and titanium lath mesh, a punched plate, or the like can be suitably used. The anode can also be accommodated in an anode bag and then used. The anode bag can be used to inhibit or prevent sludge or the like generated from the anode from being incorporated into the anolyte. The anode bag used here can be one commonly used for anodes and made of a woven cloth or a non-woven cloth. The material suitably used in the anode bag can be a chemical-resistant resin fiber such as polypropylene or polyvinylidene chloride.(Anolyte)

[0130] The anolyte is packed in the anode chamber, and includes an ion of the same metal as the metal included in the anode. For example, in a case where Cu is used as the metal in the anode, the anolyte can contain a Cu2+ ion. As the metal ion contained in such an anolyte, an ion derived from the metal described in the section “Anode” above can be used.

[0131] The metal ion contained in the anolyte is not particularly limited, and Cu2+, Sn2+, or Ni2+ can be preferably used. Among them, Cu2+ can be particularly preferably used.

[0132] The present inventors have performed a test, and thus have found that the relationship between the amount of electro-osmosis of water (n mol) from the anolyte to the plating solution, in association with the metal ion contained in the anolyte, and the amount of electro-osmosis of water (m mol) from the plating solution to the catholyte, in association with H+, satisfies n>m under usual electrolyzation conditions (liquid temperature: 20 to 40° C., electric current density of diaphragm: about 3 to 6 ASD). The reason for this is considered because, while a usual metal ion also causes movement of hydrated water according to movement of such a metal ion, the charge of H+ can also move according to a Grotthus mechanism (proton jumping mechanism), resulting in a relatively decreased amount of movement of water accompanied.

[0133] The anolyte may be a solution containing a metal salt. The metal salt contained in the solution is preferably a solution containing a metal salt contained in a plating solution used in combination. For example, in the case of use in combination with a copper sulfate plating solution, a CuSO4 solution can be used as the anolyte, or in the case of use of a plating solution containing tin methanesulfonate as a main component, a tin methanesulfonate solution can be used as the anolyte. Among them, a CuSO4 solution can be particularly used. A common copper sulfate plating solution (VMS) can be used as the anolyte.

[0134] The pH of the anolyte is not particularly limited, and a pH range in which the stability of the metal ion and the solubility of the anode are favorable and the transference number of the metal ion permeating through the first diaphragm is high is preferably selected depending on the type of the plating solution and the type of the metal ion fed. For example, in the case of use of a copper sulfate plating solution, the pH of the anolyte is preferably 0.5 to 5, more preferably 1 to 4, most preferably 1.5 to 3.5. When the pH of the anolyte falls within the above numerical value range, metal ion feeding can be made at a stably high electric current efficiency.

[0135] In the present embodiment, a gas can be blown (bubbled) into the anolyte to perform stirring. Thus, the concentration distribution of the anolyte can be made uniform to result in stabilization of the electrolytic voltage and suppression of precipitation or the like of an inorganic component.

[0136] The gas is not particularly limited, and a non-reactive gas, air, or oxygen can be used. The non-reactive gas used here can be nitrogen, carbon dioxide, or argon. In a case where the anolyte contains an easily-oxidizable metal ion such as a divalent Sn ion, the non-reactive gas is preferably used. When the non-reactive gas is used, the amount of dissolved oxygen in the anolyte is small, oxidation of the metal in the anolyte is suppressed, and generation of Sn(OH)4 being a precipitate is suppressed.

[0137] In a case where the anolyte is used in the form of a combination with a copper sulfate plating solution and the anode contains copper, a gas containing oxygen, such as air, is preferably used. Such a gas containing oxygen can be used to oxidize a monovalent Cu ion in the anolyte into a divalent ion and thus lower the concentration of the monovalent Cu ion. The concentration of the monovalent Cu ion can be lowered to not only inhibit sludge from being generated due to disproportionation reaction of the monovalent Cu ion, but also inhibit the monovalent Cu ion from permeating through a diaphragm, being incorporated into the plating solution, and causing transformation of a plating solution additive.

[0138] The gas can be used singly or in combinations of two or more kinds thereof. Any other stirring procedure such as paddle stirring or jet flow stirring can also be used instead of or in addition to the above bubbling, or plural stirring procedures can also be used in combination.(Cathode Chamber)

[0139] The cathode chamber can accommodate the cathode and the catholyte.

[0140] The volume (size) of the cathode chamber is not particularly limited, and an optimal size can be appropriately selected depending on a required rate of metal ion feeding (amount of electrolysis per time) and the size of the cathode accommodated.

[0141] The cathode chamber preferably includes a level sensor for sensing three levels of the upper limit level of the liquid level of the catholyte (catholyte upper limit level), the lower limit level of the liquid level of the catholyte (catholyte lower limit level), and the catholyte feeding level, and a catholyte feeding line and a bleeding line each interlocked with the sensor. Osmotic water due to the difference in osmol concentration between electro-osmotic water in association with electrolysis and the plating solution is fed to the catholyte via the second diaphragm, and therefore the catholyte is diluted to gradually increase the liquid level. When the liquid level reaches the catholyte upper limit level, the catholyte is bled through a bleeding port until the liquid level reaches the catholyte lower limit level. The catholyte is bled and thereafter can be fed through the catholyte feeding line until the liquid level reaches the catholyte feeding level, thereby controlling the concentration of the catholyte to a certain range. Here, a flow meter may be disposed on the catholyte feeding line or the bleeding line instead of use of the level sensor so as to feed / bleed a predetermined amount of the catholyte. Here, when a reserve tank in which the catholyte is circulated between the tank and the cathode chamber is separately disposed, the above level sensor and feeding / bleeding lines can also be disposed in the reserve tank.(Cathode)

[0142] The cathode is disposed in the cathode chamber. The cathode is not particularly limited, an inert cathode or an insoluble cathode can be used, and in particular an inert and insoluble cathode can be used. The inert and insoluble cathode can be used to stabilize the composition of the catholyte without elution of any component into the catholyte.

[0143] The metal included in the cathode is not particularly limited, and Pt, Ti, Nb, a metal coated with Pt, or any combination of two or more kinds thereof can be used. Among them, Ti coated with Pt is preferred. In the case of use of Ti coated with Pt, a Ti surface is coated with insoluble Pt, therefore an inert and insoluble cathode is obtained to cause no elution of any metal ion from the cathode, and thus the variation in composition of the catholyte is less caused.

[0144] The shape of the cathode is not particularly limited, and each shape of a rod, a ball, a disc, or a slab can be adopted. In a case where the cathode has a disc or slab shape, a shape having plural through-holes, like a punched metal plate or an expanded metal plate, may be adopted. Such a shape having plural through-holes can be adopted to increase the surface area of the cathode and lower the electrolytic voltage even at a high electric current density.

[0145] The cathode may be configured from one or plural members.(Catholyte)

[0146] The catholyte is packed in the cathode chamber.

[0147] The catholyte is not particularly limited, and is preferably an anionic acid solution included as a main component in a plating solution used in combination. In the case of use in combination with a copper sulfate plating solution, the catholyte is preferably a H2SO4 solution. The anionic acid solution included as a main component in the plating solution can be used to minimize the influence on the plating solution even in the case of slight incorporation of the catholyte into the plating solution through a diaphragm or a sealing portion.

[0148] The catholyte is preferably substantially free of an ion of the same metal as the metal included in the anode. The “metal included in the anode” may be the metal described in the section “Anode” above. Herein, the “substantially free of an ion of the same metal as the metal included in the anode” means that the concentration of the ion of the metal is 0.1 g / L or less.

[0149] In the present embodiment, a gas can be blown (bubbled) into the catholyte to perform stirring. Thus, the concentration distribution of the catholyte can be made uniform to result in stabilization of the electrolytic voltage. The gas is not particularly limited, and the same gas as the above gas used for stirring the anolyte can be used. The gas can be used singly or in combinations of two or more kinds thereof. Any other stirring procedure such as paddle stirring or jet flow stirring can also be used instead of or in addition to the above bubbling, or plural stirring procedures can also be used in combination.

[0150] In the metal ion feeding system of the present embodiment, any one of the following combinations (1) to (3) of the anode, the anolyte, the cathode, and the catholyte can be adopted.

[0151] (1) Anode: Cu ball, anolyte: mixed liquid of copper sulfate and sulfuric acid, cathode: Pt-coating Ti mesh, catholyte: sulfuric acid

[0152] (2) Anode: Sn pellet, anolyte: mixed solution of tin methanesulfonate and methanesulfonic acid, cathode: Pt-coating Ti mesh, catholyte: methanesulfonic acid solution

[0153] (3) Anode: Ni ball, anolyte: mixed solution of nickel sulfamate and boric acid, cathode: Pt-coating Ti mesh, catholyte: sulfamic acid solution(Plating Solution Circulation Chamber)

[0154] The plating solution circulation chamber is placed between the anode chamber and the cathode chamber. The plating solution circulation chamber includes an outlet for bleeding a plating solution to an electrolytic plating apparatus, and an inlet for receiving the plating solution from the electrolytic plating apparatus so that the plating solution is circulatable. The plating solution circulation chamber can accommodate the plating solution.

[0155] The plating solution circulation chamber may be defined with a first diaphragm and a second diaphragm each described later. For example, the plating solution circulation chamber may have a cell structure formed with a gasket or a spacer sandwiched between a first diaphragm and a second diaphragm each supported with a frame. The plating solution circulation chamber may have a structure in which an anode chamber with a first diaphragm placed in its opening and a cathode chamber with a second diaphragm placed in its opening are provided at a position so that both the diaphragms face each other and are disposed at a certain distance retained.

[0156] The volume of the plating solution circulation chamber is not particularly limited, and an appropriate volume can be selected depending on a required rate of metal ion feeding (amount of electrolysis per time). In particular, the plating solution circulation chamber having the cell structure is preferred because the width of the plating solution circulation chamber can be decreased to about 1 mm and the volume of the plating solution circulation chamber can be decreased.

[0157] In the present embodiment, the volume of the plating solution circulation chamber can be decreased to decrease the amount of the plating solution remaining in the plating solution circulation chamber. Thus, the amount of a metal ion incorporated from the plating solution circulation chamber into the anode chamber can be decreased, and as a result, the above-mentioned passivation of an anode surface can be further suppressed. For example, the distance between the first diaphragm and the second diaphragm can be decreased to decrease the volume of the plating solution circulation chamber. In this case, the volume of the plating solution circulation chamber can be 0.1 to 5 L.

[0158] The ratio of the volume of the plating solution circulation chamber to the volume of the anode chamber (Volume of plating solution circulation chamber / Volume of anode chamber) is not particularly limited, and is preferably 0.005 to 0.5, more preferably 0.01 to 0.2, most preferably 0.01 to 0.1. When the above ratio falls within the above numerical value range, the passivation of an anode surface can be further suppressed.

[0159] The flow rate in circulation of the plating solution in the plating solution circulation chamber is not particularly limited, and any flow rate at which the change in concentration in the plating solution in the plating solution circulation chamber is not too large can be selected depending on a required rate of metal ion feeding (amount of electrolysis per time). In this regard, in a case where no electrolysis is performed, it is preferable for minimizing ion diffusion via the first diaphragm to stop the circulation or sufficiently decrease the flow rate. However, in a case where the circulation is stopped, a crystal or the like may be precipitated in the plating solution circulation chamber by the change in composition due to ion diffusion via the first diaphragm. Therefore, in the case of stopping for a certain period or more, it is preferable to bleed the plating solution in the plating solution circulation chamber, or exchange the plating solution in the plating solution circulation chamber by circulation periodically performed.(Plating Solution)

[0160] The metal ion feeding system of the present embodiment can further include the plating solution included in the plating solution circulation chamber.

[0161] The composition of the plating solution can be appropriately set depending on a metal to be plated in the electrolytic plating apparatus. The composition of the plating solution is determined with the metal to be plated in the electrolytic plating apparatus, and a combination of the anode and the anolyte is determined depending on the composition of the plating solution. The plating solution can contain an ion of the same metal as the metal included in the anode. For example, in the case of use of Cu as the metal of the anode, the plating solution can contain a Cu2+ ion. The metal described in the section “Anode” above can be used as the metal included in the anode.

[0162] The concentration of the ion of the same metal as the metal included in the anode, in the plating solution, is not particularly limited, and an appropriate concentration can be selected depending on the type of the metal to be plated, the specification of a plated film, the demanded uniformity of the plated film, and the like. For example, the concentration of the ion of the same metal as the metal included in the anode can be 20 to 80 g / L, 30 to 70 g / L, or 30 to 65 g / L. When the concentration falls within the above numerical value range, the effect where the plated film is excellent in uniformity and productivity is obtained.

[0163] The plating solution is not particularly limited, and a copper sulfate plating solution, a Sn alloy plating solution, or a Ni sulfamate plating solution can be used. Among them, a copper sulfate plating solution can be particularly used.(First Diaphragm)

[0164] The first diaphragm is placed between the anode chamber and the plating solution circulation chamber. The first diaphragm is not particularly limited, and an ion exchange membrane or a neutral porous membrane can be used. Among them, an ion exchange membrane is preferred. The ion exchange membrane is not particularly limited, and a cation exchange membrane is preferred. The cation exchange membrane can be used to transfer the metal ion contained in the anolyte in the anode chamber to the plating solution circulation chamber. The cation exchange membrane used here can be a fluorine-based cation exchange membrane or a hydrocarbon-based cation exchange membrane. Among them, a fluorine-based cation exchange membrane is preferred because the diaphragm is excellent in durability. In particular, in a case where a halide ion is contained in the anolyte, the diaphragm tends to be easily degraded and therefore a fluorine-based cation exchange membrane can be suitably used.

[0165] The fluorine-based cation exchange membrane used here can be any of commercially available products such as FORBLUE (registered trademark) Sx-2301 and Sx-1811 (all are manufactured by AGC Inc.) and Nafion (registered trademark) N424 and N438 (all are manufactured by Chemours), and the hydrocarbon-based cation exchange membrane used here can be any of commercially available products such as Selemion (registered trademark) CMVN (manufactured by AGC Inc.) and Neosepta (registered trademark) CSE (manufactured by ASTOM Corporation.).

[0166] The rate of diffusion osmosis of water in the first diaphragm is not particularly limited, and is preferably 0.01 to 1 (mol / h·dm2·(mol / l)), more preferably 0.01 to 0.5 (mol / h·dm2·(mol / l)), most preferably 0.01 to 0.2 (mol / h·dm2·(mol / l)).(Second Diaphragm)

[0167] The second diaphragm is placed between the cathode chamber and the plating solution circulation chamber. The second diaphragm is not particularly limited, and a hydrogen ion permselective membrane, a bipolar membrane, or a monovalent cation permselective membrane can be used. Among them, a hydrogen ion permselective membrane or a bipolar membrane is particularly preferred. The hydrogen ion permselective membrane or the bipolar membrane can be used to inhibit the metal ion in the plating solution from permeating through the second diaphragm and entering the cathode chamber.

[0168] The hydrogen ion permselective membrane used here can be a commercially available product such as Selemion (registered trademark) HSFN (manufactured by AGC Engineering Co., Ltd.). The bipolar membrane used here can be a commercially available product such as Neosepta (registered trademark) BP-1EX (manufactured by ASTOM Corporation.).

[0169] The rate of diffusion osmosis of water in the second diaphragm is not particularly limited, and is preferably 0.1 to 5 (mol / h·dm2·(mol / l)), more preferably 0.2 to 3 (mol / h·dm2·(mol / l)), most preferably 0.5 to 2 (mol / h·dm2·(mol / l)).

[0170] In the metal ion feeding system of the present embodiment, preferably the first diaphragm is the cation exchange membrane and the second diaphragm is the hydrogen ion permselective membrane or the bipolar membrane. Such a combination can be adopted to feed a metal ion to the plating solution at a high electric current efficiency.

[0171] In the metal ion feeding system of the present embodiment, the rate of diffusion osmosis of water in the second diaphragm is higher than the rate of diffusion osmosis of water in the first diaphragm.

[0172] The difference between the rate of diffusion osmosis of water in the second diaphragm and the rate of diffusion osmosis of water in the first diaphragm is not particularly limited, and is preferably more than 0 and 5 or less (mol / h·dm2·(mol / l)), more preferably 0.1 to 3 (mol / h·dm2·(mol / l)), most preferably 0.2 to 2 (mol / h·dm2·(mol / l)). The ratio of the rate of diffusion osmosis of water in the second diaphragm to the rate of diffusion osmosis of water in the first diaphragm (Rate of diffusion osmosis of water in second diaphragm / Rate of diffusion osmosis of water in first diaphragm) is not particularly limited, and is preferably more than 1 and 100 or less, more preferably 3 to 50, most preferably 5 to 30.

[0173] In the metal ion feeding system of the present embodiment, the catholyte has a higher osmol concentration than the osmol concentration in the plating solution in the plating solution circulation chamber.

[0174] The osmol concentrations in the catholyte and the plating solution can be set as described above to promote movement of water due to diffusion osmosis from the plating solution to the catholyte. Thus, movement of water due to diffusion osmosis can be promoted to let out water excessively present in the plating solution, to the catholyte, and thus suppress dilution of the plating solution.

[0175] The osmol concentration in the catholyte is not particularly limited, and is preferably 1 to 15 mol / L, more preferably 2 to 10 mol / L, most preferably 3 to 8 mol / L.

[0176] The osmol concentration in the plating solution in the plating solution circulation chamber is not particularly limited, and is preferably 0.5 to 10 mol / L, more preferably 1 to 8 mol / L, most preferably 2 to 5 mol / L.

[0177] The difference between the osmol concentration in the catholyte and the osmol concentration in the plating solution in the plating solution circulation chamber is not particularly limited, and is preferably 0.1 to 10 mol / L, more preferably 0.2 to 8 mol / L, most preferably 0.5 to 5 mol / L.

[0178] The ratio of the osmol concentration in the catholyte to the osmol concentration in the plating solution in the plating solution circulation chamber (Osmol concentration in catholyte / Osmol concentration in plating solution) is not particularly limited, and is preferably 1.1 to 10, more preferably 1.2 to 5, most preferably 1.5 to 3.(Other Configurations)

[0179] The metal ion feeding system of the present embodiment can further include an external power source connected to the cathode and the anode. A reverse electric current prevention mechanism (diode or the like) is preferably disposed in the external power source. The reverse electric current prevention mechanism can be disposed to prevent a reverse electric current from flowing and causing movement of a metal ion into the anolyte during stopping.

[0180] In the present embodiment, the metal ion feeding system can further include a reserve tank in which the catholyte is circulated between the tank and the cathode chamber. A gas containing oxygen (air or the like) can be blown (bubbled) in the reserve tank. The reserve tank is exemplified and described below.

[0181] FIG. 2 is an enlarged view of the vicinity of the cathode chamber in the metal ion feeding system. The metal ion feeding system includes a cathode chamber 1300, a cathode 1700, a second diaphragm 1500, and the like.

[0182] In the metal ion feeding system illustrated in FIG. 2, a reserve tank 1310 is provided and the reserve tank 1310 can allow the catholyte to be circulated between the tank and the cathode chamber 1300.

[0183] The catholyte may slightly contain a metal ion (Sn2+ or the like) moving from the plating solution circulation chamber via the second diaphragm 1500. The metal ion may be precipitated on a cathode surface, and such a precipitate is generated to cause an increase in electrolytic voltage. In the reserve tank 1310, a gas containing oxygen is blown to oxidize the metal ion, thereby precipitating an oxidized metal ion (Sn4+ or the like) as a hydroxide. The hydroxide precipitated can be removed with a filter. Thus, the metal ion (Sn2+ or the like) moving from the plating solution circulation chamber can be inhibited from being precipitated on the cathode surface, and the increase in electrolytic voltage can be prevented.

[0184] The plating solution circulation chamber placed between the anode chamber and the cathode chamber in the metal ion feeding system of the present embodiment can have the same structure as the cell structure of an electrodialyzer. Specifically, as illustrated in FIG. 3, an inner space of a gasket 1230 / spacer 1240 sandwiched between a first diaphragm 1400 supported with a frame 1110 and a gasket 1120 and a second diaphragm 1500 supported with a frame 1320 and a gasket 1330 can be adopted as the plating solution circulation chamber.

[0185] The above structure can be adopted to minimize the volume of the plating solution circulation chamber (a width of about 1 mm). As a result, it is possible to minimize the influence by dilution or loss of the plating solution in replacement of the plating solution circulation chamber with a liquid substantially free of at least one of the metal ions.

[0186] The plating solution circulation chamber in the metal ion feeding system of the present embodiment may also be a space defined with a first diaphragm and a second diaphragm each supported with a frame.(Electrolytic Plating Apparatus)

[0187] The metal ion feeding system of the present embodiment is a system for feeding a metal ion to an electrolytic plating apparatus. Hereinafter, one mode of the electrolytic plating apparatus is described.(Configuration of Plating Tank)

[0188] FIG. 4 is a side view schematically illustrating a configuration of a plating tank in an electrolytic plating apparatus. During plating treatment, a substrate holder 11 retaining a substrate W, an anode unit 12 retaining an anode electrode AN, a regulation plate 14, and a paddle 15 are placed in a plating tank 10. The plating tank 10 accommodates a plating solution, and the substrate W and the anode electrode AN are immersed in the plating solution. The anode unit 12 has an anode holder 200 retaining the anode electrode AN, and an anode mask 300 for regulating the electric field between the anode electrode AN and the substrate W. In one example, the anode unit 12 is accommodated in an anode box 13. An opening is provided at a position opposite to the anode electrode AN in the anode box 13, and a diaphragm 13a is placed in the opening. The anode mask 300 includes one or plural substantially plate-shaped members each made of, for example, a dielectric material. The regulation plate 14 has an opening, and regulates the electric field between the plate and the substrate W as in the anode mask 300. In one example, the regulation plate 14 has a fixed dimension of the opening, and is exchanged with a regulation plate having a different opening dimension and then used. In other examples, the opening dimension of the regulation plate 14 can be adjusted. The paddle 15 stirs the plating solution in the vicinity of a surface to be plated of the substrate W. The paddle 15 can be, for example, a substantially rod-shaped member, and can be provided in the plating tank 10 so as to face the vertical direction. The paddle 15 is configured so as to be horizontally movable along with the surface to be plated of the substrate W by a driving apparatus not illustrated. The paddle 15 may be one in which plural longitudinal slits are provided in a plate-shaped member. Here, a relationship of (Exposure area or dimension of surface to be plated of substrate W)>(Opening area or dimension of regulation plate)>(Opening area or dimension of anode mask) is preferably satisfied from the viewpoint of plating quality. In this case, it is meant that the area or dimension of the substrate W itself is larger than the area or dimension of the opening in the regulation plate. Accordingly, the opening area (or opening dimension) of the anode mask and the opening area (or opening dimension) of the regulation plate are set and / or adjusted so that the relationship is satisfied.

[0189] The anode electrode AN is connected to an external power source (not illustrated) via wiring in the anode holder 200. The surface to be plated of the substrate W is connected to the external power source via wiring in the substrate holder 11. When a voltage is applied between the anode electrode AN and the substrate W from the external power source, a plating electric current flows in a pathway from the external power source through the anode electrode AN, the plating solution, and a seed layer of the surface to be plated of the substrate W, back to the external power source. Thus, the metal in the plating solution is precipitated on the surface to be plated of the substrate W, and the substrate W is subjected to plating treatment.

[0190] A circulation mechanism 700 that circulates the plating solution between the plating tank 10 and an outer tank 16 is provided in the plating tank 10. The circulation mechanism 700 includes a circulation line 702 connecting an outer tank 16 that receives the plating solution overflowing from the plating tank 10, and the plating tank 10. In one example, the circulation line 702 is connected to a bottom section of the plating tank 10 and a bottom section of the outer tank 16. A valve 704 is provided on the circulation line 702, and can perform opening and closing of the circulation line 702. The valve 704 can be, for example, an electromagnetic valve, and may be set so that opening and closing of the circulation line 702 can be controlled with a control section (not illustrated). A pump 706 is provided on the circulation line 702, and the pump 706 can allow the plating solution to be circulated from the outer tank 16 to the plating tank 10 through the circulation line 702. A temperature controller 708 is provided on the circulation line 702, and can control the temperature of the plating solution passing through the circulation line 702. For example, a thermometer not illustrated may be provided in the plating tank 10 so that the temperature controller 708 is controlled by a control section 103 depending on the plating solution temperature measured with the thermometer. A filter 710 is provided on the circulation line 702, and can remove a solid in the plating solution passing through the circulation line 702.

[0191] The plating solution circulation chamber in the metal ion feeding system of the present embodiment can be linked to the plating tank 10 illustrated in FIG. 4, to replenish a metal ion to the plating solution used in the plating apparatus. Alternatively, the plating solution circulation chamber in the metal ion feeding system of the present embodiment can be linked to a reserve tank linked to the plating tank 10, to replenish a metal ion to the plating solution used in the plating apparatus.2. Second Embodiment

[0192] A metal ion feeding method to an electrolytic plating apparatus of the second embodiment includes

[0193] (i) a step of circulating a plating solution containing metal ions between a plating solution circulation chamber and an electrolytic plating apparatus, to feed the metal ions to the electrolytic plating apparatus, and

[0194] (ii) a step of not performing feeding of the metal ions to the electrolytic plating apparatus, in which the step is to replace an inside of the plating solution circulation chamber with a liquid substantially free of at least one of the metal ions.

[0195] In step (ii) which is a step of feeding no metal ions, the inside of the plating solution circulation chamber can be replaced with a liquid substantially free of at least one of the metal ions, to allow passivation of an anode surface due to a metal ion incorporated from the plating solution circulation chamber to be suppressed by the metal ion feeding method of the present embodiment.

[0196] According to the second embodiment of the present invention, there is provided a metal ion feeding method that allows passivation of an anode surface due to a metal ion incorporated from a plating solution circulation chamber to be suppressed.

[0197] The ionization tendency of the metal included in the anode can be larger than the ionization tendency of a metal that can be incorporated from the plating solution circulation chamber to the anode chamber. In a case where such an ionization tendency relationship is established, a metal incorporated from the plating solution circulation chamber to the anode chamber is easily precipitated on an anode surface, and thus the replacement in step (ii) in the present embodiment is an effective procedure.

[0198] Hereinafter, one mode of the metal ion feeding method of the present embodiment is described.

[0199] FIG. 5A to FIG. 5E are views representing the entire process of the metal ion feeding method. In FIG. 5A to FIG. 5E, a 3-chamber cell (including an anode chamber 1100, a first diaphragm 1400, a plating solution circulation chamber 1200, a second diaphragm 1500, and a cathode chamber 1300 in the listed order) can be used to circulate the plating solution between the plating solution circulation chamber 1200 and an electrolytic plating apparatus.

[0200] FIG. 5A is a view illustrating electrolyzation (metal ion feeding) with the 3-chamber cell. FIG. 5A corresponds to step (i) that is a step of feeding metal ions. In FIG. 5A, valves V1 and V4 in a pathway between the electrolytic plating apparatus and the plating solution circulation chamber 1200 in the 3-chamber cell are opened, whereas valves V2, V3, and V5 to V7 in other pathway are closed. In FIG. 5A, the plating solution flows from the electrolytic plating apparatus to the plating solution circulation chamber 1200 in the 3-chamber cell and furthermore flows from the plating solution circulation chamber 1200 to the electrolytic plating apparatus, and the plating solution is thus circulated (CSU pump flow and CSU return flow in FIG. 5A).

[0201] FIG. 5B is a view of a step of stopping electrolyzation and bleeding the plating solution from the plating solution circulation chamber 1200. In shifting from FIG. 5A to FIG. 5B, the valves V1 and V4 in the pathway between the electrolytic plating apparatus and the plating solution circulation chamber 1200 are closed, whereas the valve V2 between a gas feeding section 1250 and the plating solution circulation chamber 1200 and the separate valve V5 between the plating solution circulation chamber 1200 and the electrolytic plating apparatus are opened. In FIG. 5B, a gas is fed from the gas feeding section 1250 to the plating solution circulation chamber 1200, thus the plating solution in the plating solution circulation chamber 1200 is pushed out of the plating solution circulation chamber 1200 and moves to the electrolytic plating apparatus and the plating solution circulation chamber 1200 is filled with the gas. In FIG. 5B, a nitrogen gas is used as the gas.

[0202] FIG. 5C is a view of a step of replacing the inside of the plating solution circulation chamber 1200 with a liquid substantially free of at least one of metal ions included in the plating solution in the state of electrolyzation stopped. The step in FIG. 5C corresponds to step (ii) that is a step of feeding no metal ions. In shifting from FIG. 5B to FIG. 5C, the valve V2 between the gas feeding section 1250 and the plating solution circulation chamber 1200 and the separate valve V5 between the plating solution circulation chamber 1200 and the electrolytic plating apparatus are closed, whereas the valve V7 between a feeding section 1260 of a liquid substantially free of at least one of the metal ions and the plating solution circulation chamber 1200 and the valve V3 between the plating solution circulation chamber 1200 and a connecting section 1270 with a waste tank are opened. In FIG. 5C, a liquid substantially free of at least one of the metal ions is fed to the plating solution circulation chamber 1200, the plating solution circulation chamber 1200 is filled with the liquid, and a nitrogen gas originally packed is wasted. In FIG. 5C, DIW (ultrapure water) or MSA (methanesulfonic acid) is used as the liquid.

[0203] FIG. 5D is a view of a step of standing in a state where electrolyzation is stopped and the plating solution circulation chamber 1200 is packed with the liquid substantially free of at least one of the metal ions. In shifting from FIG. 5C to FIG. 5D, the valves V1 to V7 in a pathway extending from the plating solution circulation chamber 1200 are closed. In FIG. 5D, the plating solution circulation chamber 1200 is filled with the liquid substantially free of at least one of the metal ions, and thus the metal ions are not incorporated into the anode chamber 1100. Therefore, no metals derived from the metal ions are precipitated on an anode surface, and passivation of the anode surface can be suppressed.

[0204] FIG. 5E is a view of a step of bleeding the liquid substantially free of at least one of the metal ions from the plating solution circulation chamber 1200 in the state of electrolyzation stopped. In shifting from FIG. 5D to FIG. 5E, the valve V2 between the gas feeding section 1250 and the plating solution circulation chamber 1200 and the valve V6 between the plating solution circulation chamber 1200 and a connecting section 1280 with a waste tank are opened. In FIG. 5E, a gas is fed to the plating solution circulation chamber 1200, thus the liquid substantially free of at least one of the metal ions in the plating solution circulation chamber 1200 is pushed out of the plating solution circulation chamber 1200 and wasted, and the plating solution circulation chamber 1200 is filled with the gas.

[0205] After the step in FIG. 5E, electrolyzation of the 3-chamber cell can be restarted to repeat the step in FIG. 5A. Furthermore, after the step in FIG. 5A, the steps from FIG. 5B to FIG. 5E can be repeated.

[0206] Hereinafter, each configuration of the metal ion feeding method of the present embodiment is described in more detail.(Plating Solution Circulation Chamber)

[0207] The plating solution circulation chamber can be placed between the anode chamber and the cathode chamber. The plating solution circulation chamber can include an outlet for bleeding a plating solution to an electrolytic plating apparatus, and an inlet for receiving the plating solution from the electrolytic plating apparatus so that the plating solution is circulatable. The plating solution circulation chamber can accommodate the plating solution.

[0208] The plating solution circulation chamber may be defined with a first diaphragm and a second diaphragm each described later. For example, the plating solution circulation chamber may have a cell structure formed with a gasket or a spacer sandwiched between a first diaphragm and a second diaphragm each supported with a frame.

[0209] The volume of the plating solution circulation chamber is not particularly limited, an appropriate volume can be selected depending on a required rate of metal ion feeding (amount of electrolysis per time), and the volume is preferably 0.1 to 50 L, more preferably 0.2 to 20 L, most preferably 0.2 to 10 L. When the volume falls within the above numerical value range, the amount of a liquid in bleeding / replacement of the plating solution in the plating solution circulation chamber can be reduced and the time necessary for replacement can be shortened. In particular, the plating solution circulation chamber having the cell structure can be adopted to decrease the width of the plating solution circulation chamber to about 1 mm and decrease the volume of the plating solution circulation chamber.

[0210] In the present embodiment, the volume of the plating solution circulation chamber can be decreased to decrease the amount of the plating solution remaining in the plating solution circulation chamber. Thus, the amount of a metal ion incorporated from the plating solution circulation chamber into the anode chamber can be decreased, and as a result, the passivation of an anode surface can be further suppressed. For example, the distance between the first diaphragm and the second diaphragm can be decreased to decrease the volume of the plating solution circulation chamber. In this case, the volume of the plating solution circulation chamber can be 0.2 to 5 L.

[0211] The ratio of the volume of the plating solution circulation chamber to the volume of the anode chamber (Volume of plating solution circulation chamber / Volume of anode chamber) is not particularly limited, and is preferably 0.005 to 0.5, more preferably 0.01 to 0.3, most preferably 0.02 to 0.2. When the above ratio falls within the above numerical value range, the passivation of an anode surface can be further suppressed.

[0212] The flow rate in circulation of the plating solution in the plating solution circulation chamber is not particularly limited, and any flow rate at which the change in concentration in the plating solution in the plating solution circulation chamber is not too large can be selected depending on a required rate of metal ion feeding (amount of electrolysis per time).(Liquid Substantially Free of at Least One of Metal Ions)

[0213] The liquid substantially free of at least one of the metal ions fed to the electrolytic plating apparatus, used in step (ii), is not particularly limited, and DIW (ultrapure water) or a solution of an acid contained in the plating solution is preferably used. The liquid used here can be a MSA solution in the case of use of a plating solution containing MSA (MeSO3H, methanesulfonic acid) or a salt of methanesulfonic acid, or can be a sulfuric acid solution in the case of use of a plating solution containing sulfuric acid or a salt of sulfuric acid. When DIW (ultrapure water) or a solution of an acid contained in the plating solution is used as the liquid, the influence in incorporation in the plating solution can be smaller.

[0214] In a case where such a metal ion fed to the electrolytic plating apparatus is in the form of one kind thereof, the liquid is substantially free of this kind of such a metal ion. In a case where such a metal ion fed to the electrolytic plating apparatus is in the form of two or more kinds thereof, the liquid may be substantially free of one of these two or more kinds of such metal ions, or may be substantially free of all of these two or more kinds of such metal ions.

[0215] A metal ion described below as a metal ion included in the plating solution can be used as such a metal ion fed to the electrolytic plating apparatus.

[0216] Herein, the “substantially free of at least one kind of the metal ions” means that at least one of the metal ions is not included, or the concentration of at least one of the metal ions is a concentration at a level where, even when such at least one of metal ions enters the anode chamber and is replaced and precipitated on an anode surface, an increase in voltage due to passivation does not occur. The “liquid substantially free of at least one of the metal ions” may be one in which the concentration of an ion of such at least one metal in the liquid is 0.1 g / L or less. Alternatively, the liquid used in step (ii) optionally does not contain the metal ions.(Additional Step)

[0217] The metal ion feeding method of the present embodiment can further include a step of bleeding the plating solution or the liquid in the plating solution circulation chamber, to an external other than the electrolytic plating apparatus, during switching between step (i) that is a step of feeding metal ions and step (ii) that is a step of feeding no metal ions. Such a step corresponds to the step in FIG. 5B or the step in FIG. 5E.

[0218] The bleeding step may be performed by feeding a gas into the plating solution circulation chamber to push out the plating solution or the liquid. Such a gas can be used to efficiently carry out bleeding of the plating solution or the liquid.

[0219] The gas is not particularly limited, and examples include a nitrogen gas, an argon gas, air, or any combination of two or more kinds thereof. Among them, a nitrogen gas is preferred. A nitrogen gas can be used to suppress oxidation of an easily-oxidizable metal ion due to oxygen, such as Sn2+.

[0220] In the metal ion feeding method of the present embodiment, a metal ion feeding system including an anode chamber, a cathode chamber, and the above plating solution circulation chamber placed between the anode chamber and the cathode chamber can be used.

[0221] This metal ion feeding system can be the same as the metal ion feeding system described in “1. First embodiment” above or a metal ion feeding system described in “3. Third embodiment” below.(Anode Chamber)

[0222] The anode chamber can accommodate the anode and the anolyte.

[0223] The volume (size) of the anode chamber is not particularly limited, and an optimal size can be appropriately selected depending on a required rate of metal ion feeding (amount of electrolysis per time) and the size of the anode accommodated. The anode chamber preferably includes a liquid level sensor and is connected with a pure water feeding line.

[0224] Water can be replenished into the anode chamber via the pure water feeding line. Pure water can be replenished into the anode chamber in an amount corresponding to the amount of water that is electrolyzed and thus serves as electro-osmotic water to permeate through the first diaphragm and flow out to the plating solution circulation chamber, or the amount of water decreased by evaporation of the anolyte, thereby suppressing the change in concentration in the anolyte.(Anode)

[0225] The anode is disposed in the anode chamber. The anode used here is preferably a soluble anode. A soluble anode and an insoluble anode can also be used in combination. A soluble anode and an insoluble anode can be used in combination, thereby suppressing an increase in pH of the anolyte due to electrolysis, as compared with the case of no use of any insoluble anode. Accordingly, the soluble anode can be prevented from being lowered in solubility.

[0226] The metal included in the anode can be appropriately set depending on the type of a metal to be plated. The metal included in the anode is not particularly limited, and Sn, Cu, Pb, SnPb, Ni, Ag, or Bi can be preferably used. Among them, Sn can be particularly preferably used.

[0227] The shape of the anode is not particularly limited, and each shape of a ball, a disc, a slab, a rod, or a cylinder can be adopted.

[0228] The anode may be configured from one or plural members. For example, the anode used here may be one plate-shaped (for example, rectangular plate-shaped or round plate-shaped) anode, or can be in the form of plural anode pieces (for example, ball-shaped, grain-shaped, or rod-shaped) accommodated in a conductive case. For example, the anode may be in the form of plural Sn balls or cylinders. In a case where such plural anode pieces are used, the influence on electrolysis reaction in a case where the anode is consumed and thus changed in shape and size is small. In a case where such plural anode pieces are accommodated in a conductive case and then used, a fresh anode in an amount corresponding to the amount of the anode consumed may be refilled in the conductive case and it is unnecessary to stop any apparatus for exchange of the anode. The material used for packing the anode is a metal not causing oxidation, elution, and the like by electrode reaction, and titanium lath mesh, a punched plate, or the like can be suitably used. The anode can also be accommodated in an anode bag and then used. The anode bag can be used to inhibit or prevent sludge or the like generated from the anode from being incorporated into the anolyte. The anode bag used here can be one commonly used for anodes and made of a woven cloth or a non-woven cloth. The material suitably used in the anode bag can be a chemical-resistant resin fiber such as polypropylene or polyvinylidene chloride.(Anolyte)

[0229] The anolyte is packed in the anode chamber. The anolyte may include an ion of the same metal as the metal included in the anode. For example, in a case where Sn is used as the metal of the anode, the anolyte can include a Sn2+ ion. The metal described in the section “Anode” above can be used as the metal included in the anode.

[0230] The anolyte is not particularly limited, and an alkylsulfonic acid solution such as a MSA solution, a sulfuric acid solution, or a sulfamic acid solution can be used. Among them, a MSA solution can be particularly used. In a case where the anolyte contains a MSA solution, the anolyte can further contain H2SO4.

[0231] The metal ion contained in the anolyte is not particularly limited, and Sn2+, Cu2+, or Ni2+ can be used. Among them, Sn2+ can be particularly used.

[0232] The pH of the anolyte is not particularly limited, and a pH range in which the stability of the metal ion and the solubility of the anode are favorable and the transference number of the metal ion permeating through the first diaphragm is high is preferably selected depending on the type of the plating solution and the type of the metal ion fed. For example, in the case of use of a tin plating solution, the pH of the anolyte is preferably 0 to 2, more preferably 0 to 1.5, most preferably 0 to 1. When the pH of the anolyte falls within the above numerical value range, metal ion feeding can be made at a stably high electric current efficiency.

[0233] Each step in the method of the present embodiment can be performed in a state where the anolyte is packed in the anode chamber.

[0234] In the present embodiment, a gas can be blown (bubbled) into the anolyte to perform stirring. Thus, the concentration distribution of the anolyte can be made uniform to result in stabilization of the electrolytic voltage and suppression of precipitation or the like of an inorganic component.

[0235] The gas is not particularly limited, and a non-reactive gas, air, or oxygen can be used. The non-reactive gas used here can be nitrogen, carbon dioxide, or argon. In a case where the anolyte contains an easily-oxidizable metal ion such as a divalent Sn ion, the non-reactive gas is preferably used. When the non-reactive gas is used, the amount of dissolved oxygen in the anolyte is small, oxidation of the metal in the anolyte is suppressed, and generation of Sn(OH)4 being a precipitate is suppressed. In addition, when the non-reactive gas is used, the Sn2+ concentration in the anolyte can be inhibited from being decreased and the amount of the anode consumed can be reduced. The gas can be used singly or in combinations of two or more kinds thereof. Any other stirring procedure such as paddle stirring or jet flow stirring can also be used instead of or in addition to the above bubbling, and plural stirring procedures can also be used in combination.(Cathode Chamber)

[0236] The cathode chamber can accommodate the cathode and the catholyte.

[0237] The volume (size) of the cathode chamber is not particularly limited, and an optimal size can be appropriately selected depending on a required rate of metal ion feeding (amount of electrolysis per time) and the size of the cathode accommodated.

[0238] The cathode chamber preferably includes a level sensor for sensing three levels of the upper limit level of the liquid level of the catholyte (catholyte upper limit level), the lower limit level of the liquid level of the catholyte (catholyte lower limit level), and the catholyte feeding level, and a catholyte feeding line and a bleeding line each interlocked with the sensor. Osmotic water due to the difference in osmol concentration between electro-osmotic water in association with electrolysis and the plating solution is fed to the catholyte via the second diaphragm, and therefore the catholyte is diluted to gradually increase the liquid level. When the liquid level reaches the catholyte upper limit level, the catholyte is bled through a bleeding port until the liquid level reaches the catholyte lower limit level. The catholyte is bled and thereafter can be fed through the catholyte feeding line until the liquid level reaches the catholyte feeding level, thereby controlling the concentration of the catholyte to a certain range. Here, a flow meter may be disposed on the catholyte feeding line or the bleeding line instead of use of the level sensor so as to feed / bleed a predetermined amount of the catholyte. Here, when a reserve tank in which the catholyte is circulated between the tank and the cathode chamber is separately disposed, the above level sensor and feeding / bleeding lines can also be disposed in the reserve tank.(Cathode)

[0239] The cathode is disposed in the cathode chamber. The cathode is not particularly limited, an inert cathode or an insoluble cathode can be used, and in particular an inert and insoluble cathode can be used. The inert and insoluble cathode can be used to stabilize the composition of the catholyte without elution of any component into the catholyte.

[0240] The metal included in the cathode is not particularly limited, and Pt, Ti, Nb, a metal coated with Pt, or any combination of two or more kinds thereof can be used. Among them, Ti coated with Pt is preferred. In the case of use of Ti coated with Pt, a Ti surface is coated with insoluble Pt, therefore an inert and insoluble cathode is obtained to cause no elution of any metal ion from the cathode, and thus the variation in composition of the catholyte is not caused.

[0241] The shape of the cathode is not particularly limited, and each shape of a rod, a ball, a disc, or a slab can be adopted. In a case where the cathode has a disc or slab shape, a shape having plural through-holes, like a punched metal plate or an expanded metal plate, may be adopted. Such a shape having plural through-holes can be adopted to increase the surface area of the cathode and lower the electrolytic voltage even at a high electric current density.

[0242] The cathode may be configured from one or plural members.(Catholyte)

[0243] The catholyte is packed in the cathode chamber.

[0244] The catholyte is not particularly limited, and is preferably an anionic acid solution included as a main component in a plating solution used in combination. In the case of use in combination with a tin methanesulfonate alloy plating solution, the catholyte is preferably a MSA solution. The anionic acid solution included as a main component in the plating solution can be used to minimize the influence on the plating solution even in the case of slight incorporation of the catholyte into the plating solution through a diaphragm or a sealing portion.

[0245] The catholyte can be substantially free of an ion of the same metal as the metal included in the anode. The “metal included in the anode” may be the metal described in the section “Anode” above. Herein, the “substantially free of an ion of the same metal as the metal included in the anode” means that the concentration of the ion of the metal is 0.1 g / L or less.

[0246] In the present embodiment, a gas can be blown (bubbled) into the catholyte to perform stirring. Thus, the concentration distribution of the catholyte can be made uniform to result in stabilization of the electrolytic voltage. The gas is not particularly limited, and the same gas as the above gas used for stirring the anolyte can be used. The gas can be used singly or in combinations of two or more kinds thereof. Any other stirring procedure such as paddle stirring or jet flow stirring can also be used instead of or in addition to the above bubbling, or plural stirring procedures can also be used in combination.

[0247] Each step in the method of the present embodiment can be performed in a state where the catholyte is packed in the cathode chamber.

[0248] In the present embodiment, any one of the following combinations (1) to (3) of the anode, the anolyte, the cathode, and the catholyte can be adopted.

[0249] (1) Anode: Sn pellet, anolyte: mixed solution of tin methanesulfonate and MSA, cathode: Pt-coating Ti mesh, catholyte: MSA solution

[0250] (2) Anode: Cu ball, anolyte: mixed solution of copper sulfate and sulfuric acid, cathode: Pt-coating Ti mesh, catholyte: sulfuric acid solution

[0251] (3) Anode: Ni ball, anolyte: mixed solution of nickel sulfamate and boric acid, cathode: Pt-coating Ti mesh, catholyte: sulfamic acid solution(Plating Solution)

[0252] The metal ion feeding system of the present embodiment can further include the plating solution included in the plating solution circulation chamber.

[0253] The composition of the plating solution can be appropriately set depending on a metal to be plated in the electrolytic plating apparatus. The composition of the plating solution is determined with the metal to be plated in the electrolytic plating apparatus, and a combination of the anode and the anolyte is determined depending on the composition of the plating solution. The plating solution can contain an ion of the same metal as the metal included in the anode. For example, in the case of use of Sn as the metal of the anode, the plating solution can contain a Sn2+ ion. The metal described in the section“Anode” above can be used as the metal included in the anode.

[0254] The concentration of the ion of the same metal as the metal included in the anode, in the plating solution, is not particularly limited, and an appropriate concentration can be selected depending on the type of the metal to be plated, the specification of a plated film, the demanded uniformity of the plated film, and the like. For example, the concentration of the ion of the same metal as the metal included in the anode can be 10 to 200 g / L, 20 to 150 g / L, or 30 to 100 g / L. When the concentration falls within the above numerical value range, the plated film is excellent in uniformity.

[0255] The plating solution is not particularly limited, and a Sn alloy plating solution, a copper sulfate plating solution, or a Ni sulfamate plating solution can be used. Among them, a Sn alloy plating solution can be particularly used.

[0256] The plating solution circulated between the plating solution circulation chamber and the electrolytic plating apparatus contains a metal ion. The metal ion is not particularly limited, and examples include Ag+, Sn2+, Cu2+, Bi3+ or any combination of two or more kinds thereof. Among them, a combination of Ag+ and Sn2+ can be particularly used.

[0257] The ionization tendency of the metal included in the anode can be larger than the ionization tendency of a metal that can be incorporated from the plating solution circulation chamber to the anode chamber. Any one of the following combinations (1) to (3) can be adopted as a combination of metals satisfying such an ionization tendency relationship.

[0258] (1) Metal included in anode: Sn, metal that can be incorporated from plating solution circulation chamber to anode chamber: Ag

[0259] (2) Metal included in anode: Sn, metal that can be incorporated from plating solution circulation chamber to anode chamber: Cu

[0260] (3) Metal included in anode: Sn, metal that can be incorporated from plating solution circulation chamber to anode chamber: Bi(First Diaphragm)

[0261] The first diaphragm is placed between the anode chamber and the plating solution circulation chamber. The first diaphragm is not particularly limited, and an ion exchange membrane or a neutral porous membrane can be used. Among them, an ion exchange membrane is preferred. The ion exchange membrane is not particularly limited, and a cation exchange membrane is preferred. The cation exchange membrane can be used to transfer the metal ion contained in the anolyte in the anode chamber to the plating solution circulation chamber. The cation exchange membrane used here can be a fluorine-based cation exchange membrane or a hydrocarbon-based cation exchange membrane. Among them, a fluorine-based cation exchange membrane is preferred because the diaphragm is excellent in durability. In particular, in a case where a halide ion is contained in the anolyte, the diaphragm tends to be easily degraded and therefore a fluorine-based cation exchange membrane can be suitably used.

[0262] The fluorine-based cation exchange membrane used here can be any of commercially available products such as FORBLUE (registered trademark) Sx-2301 and Sx-1811 (all are manufactured by AGC Inc.) and Nafion (registered trademark) N424 and N438 (all are manufactured by Chemours), and the hydrocarbon-based cation exchange membrane used here can be any of commercially available products such as Selemion (registered trademark) CMVN (manufactured by AGC Inc.) and Neosepta (registered trademark) CSE (manufactured by ASTOM Corporation.).

[0263] The rate of diffusion osmosis of water in the first diaphragm is not particularly limited, and is preferably 0.01 to 1 (mol / h·dm2·(mol / l)), more preferably 0.01 to 0.5 (mol / h·dm2·(mol / l)), most preferably 0.01 to 0.2 (mol / h·dm2·(mol / l)).(Second Diaphragm)

[0264] The second diaphragm is placed between the cathode chamber and the plating solution circulation chamber. The second diaphragm is not particularly limited, and a hydrogen ion permselective membrane, a bipolar membrane, or a monovalent cation permselective membrane can be used. Among them, a hydrogen ion permselective membrane or a bipolar membrane is particularly preferred. The hydrogen ion permselective membrane or the bipolar membrane can be used to inhibit the metal ion in the plating solution from permeating through the second diaphragm and entering the cathode chamber.

[0265] The hydrogen ion permselective membrane used here can be a commercially available product such as Selemion (registered trademark) HSFN (manufactured by AGC Engineering Co., Ltd.). The bipolar membrane used here can be a commercially available product such as Neosepta (registered trademark) BP-1EX (manufactured by ASTOM Corporation.).

[0266] The rate of diffusion osmosis of water in the second diaphragm is not particularly limited, and is preferably 0.1 to 5 (mol / h·dm2·(mol / l)), more preferably 0.2 to 3 (mol / h·dm2·(mol / l)), most preferably 0.5 to 2 (mol / h·dm2·(mol / l)).

[0267] In the metal ion feeding system, preferably the first diaphragm is the cation exchange membrane and the second diaphragm is the hydrogen ion permselective membrane or the bipolar membrane. Such a combination can be adopted to feed a metal ion to the plating solution at a high electric current efficiency.

[0268] In the metal ion feeding system, the rate of diffusion osmosis of water in the second diaphragm may be higher than the rate of diffusion osmosis of water in the first diaphragm.

[0269] The difference between the rate of diffusion osmosis of water in the second diaphragm and the rate of diffusion osmosis of water in the first diaphragm is not particularly limited, and is preferably more than 0 and 5 or less (mol / h·dm2·(mol / l)), more preferably 0.1 to 3 (mol / h·dm2·(mol / l)), most preferably 0.2 to 2 (mol / h·dm2·(mol / l)). The ratio of the rate of diffusion osmosis of water in the second diaphragm to the rate of diffusion osmosis of water in the first diaphragm (Rate of diffusion osmosis of water in second diaphragm / Rate of diffusion osmosis of water in first diaphragm) is not particularly limited, and is preferably more than 1 and 100 or less, more preferably 3 to 50, most preferably 5 to 30.(Other Configurations)

[0270] The metal ion feeding system can further include an external power source connected to the cathode and the anode. A reverse electric current prevention mechanism (diode or the like) is preferably disposed in the external power source. The reverse electric current prevention mechanism can be disposed to prevent a reverse electric current from flowing and causing movement of a metal ion into the anolyte during stopping.

[0271] In the present embodiment, the metal ion feeding system can further include a reserve tank in which the catholyte is circulated between the tank and the cathode chamber. A gas containing oxygen (air or the like) can be blown (bubbled) in the reserve tank. The reserve tank is exemplified and described below.

[0272] FIG. 2 is an enlarged view of the vicinity of the cathode chamber in the metal ion feeding system. The metal ion feeding system includes a cathode chamber 1300, a cathode 1700, a second diaphragm 1500, and the like.

[0273] In the metal ion feeding system illustrated in FIG. 2, a reserve tank 1310 is provided and the reserve tank 1310 can allow the catholyte to be circulated between the tank and the cathode chamber 1300.

[0274] The catholyte may slightly contain a metal ion (Sn2+ or the like) moving from the plating solution circulation chamber via the second diaphragm 1500. The metal ion may be precipitated on a cathode surface, and such a precipitate is generated to cause an increase in electrolytic voltage. In the reserve tank 1310, a gas containing oxygen is blown to oxidize the metal ion, thereby precipitating an oxidized metal ion (Sn4+ or the like) as a hydroxide. The hydroxide precipitated can be removed with a filter. Thus, the metal ion (Sn2+ or the like) moving from the plating solution circulation chamber can be inhibited from being precipitated on the cathode surface, and the increase in electrolytic voltage can be prevented.

[0275] The plating solution circulation chamber placed between the anode chamber and the cathode chamber in the metal ion feeding system of the present embodiment can have the same structure as the cell structure of an electrodialyzer. Specifically, as illustrated in FIG. 3, an inner space of a gasket 1230 / spacer 1240 sandwiched between a first diaphragm 1400 supported with a frame 1110 and a gasket 1120 and a second diaphragm 1500 supported with a frame 1320 and a gasket 1330 can be adopted as the plating solution circulation chamber.

[0276] The above structure can be adopted to minimize the volume of the plating solution circulation chamber (a width of about 1 mm). As a result, it is possible to minimize the influence by dilution or loss of the plating solution in replacement of the plating solution circulation chamber with a liquid substantially free of at least one of the metal ions.

[0277] The plating solution circulation chamber in the metal ion feeding system may also be a space defined with a first diaphragm and a second diaphragm each supported with a frame.

[0278] The metal ion feeding system is a system for feeding a metal ion to an electrolytic plating apparatus. The electrolytic plating apparatus can be the same as the electrolytic plating apparatus described in “1. First embodiment” above.3. Third Embodiment

[0279] A metal ion feeding system for an electrolytic plating apparatus of the third embodiment includes

[0280] an anode chamber that includes an anode and that is packed with an anolyte,

[0281] a cathode chamber that includes a cathode and that is packed with a catholyte,

[0282] a first plating solution circulation chamber defined with a first diaphragm and a second diaphragm and placed between the anode chamber and the cathode chamber, and

[0283] one or more stacked module placed between the first plating solution circulation chamber and the cathode, the stacked module including an anolyte chamber packed with an anolyte and a second plating solution circulation chamber defined with a third diaphragm and a fourth diaphragm,

[0284] wherein the third diaphragm is formed from the same material as that of the first diaphragm, and the fourth diaphragm is formed from the same material as that of the second diaphragm,

[0285] the first plating solution circulation chamber and the second plating solution circulation chamber each include an outlet for bleeding a plating solution to an electrolytic plating apparatus, and an inlet for receiving the plating solution from the electrolytic plating apparatus so that the plating solution is circulatable, and

[0286] the anolyte chamber includes an outlet for bleeding the anolyte from the anolyte chamber and an inlet for receiving the anolyte in the anolyte chamber so that the anolyte in the anode chamber is capable of being in fluid communication.

[0287] The metal ion feeding system of the present embodiment includes the one or more stacked module, and thus sludge generation in the anolyte in the anode chamber and on the diaphragms can be suppressed.

[0288] According to the third embodiment of the present invention, there is provided a metal ion feeding system in which sludge generation is suppressed in an anolyte in an anode chamber and on diaphragms.

[0289] Hereinafter, one mode of the metal ion feeding system of the present embodiment is described.

[0290] FIG. 6 is a cross-sectional view illustrating the entire configuration of the metal ion feeding system.

[0291] In FIG. 6, a metal ion feeding system 3000 includes an anode chamber 1100, a first plating solution circulation chamber 2200, a stacked module 2800, and a cathode chamber 1300. The first plating solution circulation chamber 2200 is defined by a first diaphragm 2400 and a second diaphragm 2450. An anode 1600 is disposed and the anolyte is packed in the anode chamber 1100. A cathode 1700 is disposed and the catholyte is packed in the cathode chamber 1300.

[0292] The stacked module 2800 includes an anolyte chamber 2810 and a second plating solution circulation chamber 2820. The second plating solution circulation chamber 2820 is defined by a third diaphragm 2500 and a fourth diaphragm 2550. The anolyte is packed in the anolyte chamber 2810. The anolyte chamber 2810 includes an outlet 2811 for bleeding the anolyte from the anolyte chamber 2810 and an inlet 2812 for receiving the anolyte in the anolyte chamber 2810 so that the anolyte in the anode chamber 1100 is capable of being in fluid communication. The anode chamber 1100 and the anolyte chamber 2810 are connected by pipes 2813 and 2814. The anolyte can move from the anolyte chamber 2810 to the anode chamber 1100 through the pipe 2813 and can move from the anode chamber 1100 to the anolyte chamber 2810 through the pipe 2814, respectively.

[0293] The first plating solution circulation chamber 2200 and the second plating solution circulation chamber 2820 include respectively outlets 2210 and 2821 for bleeding a plating solution to an electrolytic plating apparatus, and inlets 2220 and 2822 for receiving the plating solution from the electrolytic plating apparatus so that the plating solution is circulatable.

[0294] An external power source 1900 (illustrated in FIG. 7 described later) is connected to the anode 1600 and the cathode 1700. As indicated by arrows, the plating solution is bled from the first plating solution circulation chamber 2200 and the second plating solution circulation chamber 2820 to the electrolytic plating apparatus and the plating solution flows from the electrolytic plating apparatus into the first plating solution circulation chamber 2200 and the second plating solution circulation chamber 2820. In addition, nitrogen 2950 is sent into the anolyte through a gas diffusion tube 1800.

[0295] In the metal ion feeding system 3000 of FIG. 6, the first diaphragm 2400 and the third diaphragm 2500 used are fluorine-based cation exchange membranes, the second diaphragm 2450 and the fourth diaphragm 2550 used are hydrogen ion permselective membranes or bipolar membranes, the anode 1600 used is a Sn ball, and the cathode 1700 used is Pt-coating Ti mesh, respectively.

[0296] FIG. 7 is a cross-sectional view illustrating the situation of ion movement in the metal ion feeding system.

[0297] In FIG. 7, the transference number of Sn2+ permeating through a first diaphragm 2400 or a third diaphragm 2500 being a cation exchange membrane is designated as tSn. Herein, the transference number means the proportion of the electric current resulting from a certain ion in the total electric current in electric current application to a solution of an electrolyte.

[0298] When 1 mol of Sn2+ is dissolved in the anolyte from an anode 1600 by electrolyzation (2 Faradays), the molar number of Sn2+ permeating through the first diaphragm 2400 or the third diaphragm 2500 is tSn mol and therefore 2tSn mol of Sn2+ in total through the first diaphragm 2400 and the third diaphragm 2500 moves from the anolyte to the plating solution. In this regard, Sn2+ does not permeate through a second diaphragm 2450 and a fourth diaphragm 2550 each being a hydrogen ion permselective membrane or a bipolar membrane, and thus the change in molar number of Sn2+ in total in the anolyte is (1−2tSn) mol.

[0299] In the case of tSn>0.5, (1−2tSn)<0 is satisfied, and therefore the amount of Sn2+ in the anolyte is decreasing according to electrolyzation (that of H+ is increasing). As the concentration of Sn2+ in the anolyte decreases, tSn is also smaller, and therefore finally tSn=0.5 is satisfied and a steady state is achieved.

[0300] In this regard, in the case of tSn<0.5, (1−2tSn)>0 is satisfied, and therefore the amount of Sn2+ in the anolyte is increasing according to electrolyzation (that of H+ is decreasing). As the concentration of Sn2+ in the anolyte increases, tSn is also larger, and therefore finally tSn=0.5 is satisfied and a steady state is achieved.

[0301] In the case of tSn=0.5, (1−2tSn)=0 is satisfied, and therefore the amount of Sn2+ in the anolyte is not changed according to electrolyzation (that of H+ is also not changed). Here, 1 mol of Sn2+ is fed from the anolyte to the plating solution.

[0302] As described above, the anolyte is naturally adjusted according to electrolyzation so as to have an anolyte composition satisfying tSn=0.5. Accordingly, concentration management of the anolyte may be made only by replenishing of water decreased by electro-osmosis or the like, and any other special concentration management of the anolyte is not required.

[0303] A sufficient concentration of H+ for dissolution of Sn(OH)2 corresponding to sludge is present in the anolyte composition satisfying tSn=0.5, and therefore sludge generation can be suppressed.

[0304] While FIG. 7 illustrates one case in which the metal ion in the anolyte is Sn2+ and one stacked module is present, the type of the metal ion in the anolyte and / or the number of stacked modules can be changed. For example, in a case where the stability of the metal ion in the anolyte at the time of an increase in pH is low (the stability of a hydroxide ion is low), the number of stacked modules can be increased and the pH of the anolyte in a steady state can be set to a lower pH than that at which the hydroxide ion is precipitated, thereby suppressing sludge generation as in the example of FIG. 7.

[0305] Hereinafter, each configuration of the metal ion feeding system of the present embodiment is described in more detail.(Anode Chamber)

[0306] The anode chamber can accommodate the anode and the anolyte.

[0307] The volume (size) of the anode chamber is not particularly limited, and an optimal size can be appropriately selected depending on a required rate of metal ion feeding (amount of electrolysis per time) and the size of the anode accommodated. The anode chamber preferably includes a liquid level sensor and is connected with a pure water feeding line.

[0308] Water can be replenished into the anode chamber via the pure water feeding line. Pure water can be replenished into the anode chamber in an amount corresponding to the amount of water that is electrolyzed and thus serves as electro-osmotic water to permeate through the first diaphragm and flow out to the plating solution circulation chamber, or the amount of water decreased by evaporation of the anolyte, thereby suppressing the change in concentration in the anolyte.(Anode)

[0309] The anode is disposed in the anode chamber. The anode used here is preferably a soluble anode. A soluble anode and an insoluble anode can also be used in combination. A soluble anode and an insoluble anode can be used in combination, thereby suppressing an increase in pH of the anolyte due to electrolysis, as compared with the case of no use of any insoluble anode. Accordingly, the soluble anode can be prevented from being lowered in solubility.

[0310] The metal included in the anode can be appropriately set depending on the type of a metal to be plated. The metal included in the anode is not particularly limited, and Sn, Cu, Pb, SnPb, Ni, Ag, or Bi can be preferably used. Among them, Sn can be particularly preferably used.

[0311] The shape of the anode is not particularly limited, and each shape of a ball, a disc, a slab, a rod, or a cylinder can be adopted.

[0312] The anode may be configured from one or plural members. For example, the anode used here may be one plate-shaped (for example, rectangular plate-shaped or round plate-shaped) anode, or can be in the form of plural anode pieces (for example, ball-shaped, grain-shaped, or rod-shaped) accommodated in a conductive case. For example, the anode may be in the form of plural Sn balls or cylinders. In a case where such plural anode pieces are used, the influence on electrolysis reaction in a case where the anode is consumed and thus changed in shape and size is small. In a case where such plural anode pieces are accommodated in a conductive case and then used, a fresh anode in an amount corresponding to the amount of the anode consumed may be refilled in the conductive case and it is unnecessary to stop any apparatus for exchange of the anode. The material used for packing the anode is a metal not causing oxidation, elution, and the like by electrode reaction, and titanium lath mesh, a punched plate, or the like can be suitably used. The anode can also be accommodated in an anode bag and then used. The anode bag can be used to inhibit or prevent sludge or the like generated from the anode from being incorporated into the anolyte. The anode bag used here can be one commonly used for anodes and made of a woven cloth or a non-woven cloth. The material suitably used in the anode bag can be a chemical-resistant resin fiber such as polypropylene or polyvinylidene chloride.(Anolyte)

[0313] The anolyte is packed in the anode chamber. The anolyte may include an ion of the same metal as the metal included in the anode. For example, in a case where Sn is used as the metal of the anode, the anolyte can include a Sn2+ ion. The metal described in the section “Anode” above can be used as the metal included in the anode.

[0314] The anolyte is not particularly limited, and an alkylsulfonic acid solution such as a MSA solution, a sulfuric acid solution, or a sulfamic acid solution can be used. Among them, a MSA solution can be particularly used. In a case where the anolyte contains a MSA solution, the anolyte can further contain H2SO4.

[0315] The metal ion contained in the anolyte is not particularly limited, and Sn2+, Cu2+, or Ni2+ can be used. Among them, Sn2+ can be particularly used.

[0316] The pH of the anolyte is not particularly limited, and a pH range in which the stability of the metal ion and the solubility of the anode are favorable and the transference number of the metal ion permeating through the first diaphragm is high is preferably selected depending on the type of the plating solution and the type of the metal ion fed. For example, in the case of use of a tin plating solution, the pH of the anolyte is preferably 0 to 2, more preferably 0 to 1.5, most preferably 0 to 1. When the pH of the anolyte falls within the above numerical value range, metal ion feeding can be made at a stably high electric current efficiency.

[0317] In the present embodiment, a gas can be blown (bubbled) into the anolyte to perform stirring. Thus, the concentration distribution of the anolyte can be made uniform to result in stabilization of the electrolytic voltage and suppression of precipitation or the like of an inorganic component.

[0318] The gas is not particularly limited, and a non-reactive gas, air, or oxygen can be used. The non-reactive gas used here can be nitrogen, carbon dioxide, or argon. In a case where the anolyte contains an easily-oxidizable metal ion such as a divalent Sn ion, the non-reactive gas is preferably used. When the non-reactive gas is used, the amount of dissolved oxygen in the anolyte is small, oxidation of the metal in the anolyte is suppressed, and generation of Sn(OH)4 being a precipitate is suppressed. In addition, when the non-reactive gas is used, the Sn2+ concentration in the anolyte can be inhibited from being decreased and the amount of the anode consumed can be reduced. The gas can be used singly or in combinations of two or more kinds thereof. Any other stirring procedure such as paddle stirring or jet flow stirring can also be used instead of or in addition to the above bubbling, and plural stirring procedures can also be used in combination. The stirring unit can be disposed on the anode chamber and / or the anolyte chamber.(Cathode Chamber)

[0319] The cathode chamber can accommodate the cathode and the catholyte.

[0320] The volume (size) of the cathode chamber is not particularly limited, and an optimal size can be appropriately selected depending on a required rate of metal ion feeding (amount of electrolysis per time) and the size of the cathode accommodated.

[0321] The cathode chamber preferably includes a level sensor for sensing three levels of the upper limit level of the liquid level of the catholyte (catholyte upper limit level), the lower limit level of the liquid level of the catholyte (catholyte lower limit level), and the catholyte feeding level, and a catholyte feeding line and a bleeding line each interlocked with the sensor. Osmotic water due to the difference in osmol concentration between electro-osmotic water in association with electrolysis and the plating solution is fed to the catholyte via the second diaphragm, and therefore the catholyte is diluted to gradually increase the liquid level. When the liquid level reaches the catholyte upper limit level, the catholyte is bled through a bleeding port until the liquid level reaches the catholyte lower limit level. The catholyte is bled and thereafter can be fed through the catholyte feeding line until the liquid level reaches the catholyte feeding level, thereby controlling the concentration of the catholyte to a certain range. Here, a flow meter may be disposed on the catholyte feeding line or the bleeding line instead of use of the level sensor so as to feed / bleed a predetermined amount of the catholyte. Here, when a reserve tank in which the catholyte is circulated between the tank and the cathode chamber is separately disposed, the above level sensor and feeding / bleeding lines can also be disposed in the reserve tank.(Cathode)

[0322] The cathode is disposed in the cathode chamber. The cathode is not particularly limited, an inert cathode or an insoluble cathode can be used, and in particular an inert and insoluble cathode can be used. The inert and insoluble cathode can be used to stabilize the composition of the catholyte without elution of any component into the catholyte.

[0323] The metal included in the cathode is not particularly limited, and Pt, Ti, Nb, a metal coated with Pt, or any combination of two or more kinds thereof can be used. Among them, Ti coated with Pt is preferred. In the case of use of Ti coated with Pt, a Ti surface is coated with insoluble Pt, therefore an inert and insoluble cathode is obtained to cause no elution of any metal ion from the cathode, and thus the variation in composition of the catholyte is not caused.

[0324] The shape of the cathode is not particularly limited, and each shape of a rod, a ball, a disc, or a slab can be adopted. In a case where the cathode has a disc or slab shape, a shape having plural through-holes, like a punched metal plate or an expanded metal plate, may be adopted. Such a shape having plural through-holes can be adopted to increase the surface area of the cathode and lower the electrolytic voltage even at a high electric current density.

[0325] The cathode may be configured from one or plural members.(Catholyte)

[0326] The catholyte is packed in the cathode chamber.

[0327] The catholyte is not particularly limited, and is preferably an anionic acid solution included as a main component in a plating solution used in combination. In the case of use in combination with a tin methanesulfonate alloy plating solution, the catholyte is preferably a MSA solution. The anionic acid solution included as a main component in the plating solution can be used to minimize the influence on the plating solution even in the case of slight incorporation of the catholyte into the plating solution through a diaphragm or a sealing portion.

[0328] The catholyte can be substantially free of an ion of the same metal as the metal included in the anode. The “metal included in the anode” may be the metal described in the section “Anode” above. Herein, the “substantially free of an ion of the same metal as the metal included in the anode” means that the concentration of the ion of the metal is 0.1 g / L or less.

[0329] In the present embodiment, a gas can be blown (bubbled) into the catholyte to perform stirring. Thus, the concentration distribution of the catholyte can be made uniform to result in stabilization of the electrolytic voltage. The gas is not particularly limited, and the same gas as the above gas used for stirring the anolyte can be used. The gas can be used singly or in combinations of two or more kinds thereof. Any other stirring procedure such as paddle stirring or jet flow stirring can also be used instead of or in addition to the above bubbling, or plural stirring procedures can also be used in combination.

[0330] In the present embodiment, any one of the following combinations (1) to (3) of the anode, the anolyte, the cathode, and the catholyte can be adopted.

[0331] (1) Anode: Sn pellet, anolyte: mixed solution of tin methanesulfonate and MSA, cathode: Pt-coating Ti mesh, catholyte: MSA solution

[0332] (2) Anode: Cu ball, anolyte: mixed solution of copper sulfate and sulfuric acid, cathode: Pt-coating Ti mesh, catholyte: sulfuric acid solution

[0333] (3) Anode: Ni ball, anolyte: mixed solution of nickel sulfamate and boric acid, cathode: Pt-coating Ti mesh, catholyte: sulfamic acid solution(First Plating Solution Circulation Chamber and Second Plating Solution Circulation Chamber)

[0334] The first plating solution circulation chamber and the second plating solution circulation chamber each include an outlet for bleeding a plating solution to an electrolytic plating apparatus, and an inlet for receiving the plating solution from the electrolytic plating apparatus so that the plating solution is circulatable. The first plating solution circulation chamber and the second plating solution circulation chamber can each accommodate the plating solution.

[0335] The first plating solution circulation chamber is defined with a first diaphragm and a second diaphragm each described later. For example, the first plating solution circulation chamber may have a cell structure formed with a gasket or a spacer sandwiched between a first diaphragm and a second diaphragm each supported with a frame.

[0336] The second plating solution circulation chamber is defined by a third diaphragm and a fourth diaphragm each described later. For example, the second plating solution circulation chamber may have a cell structure formed with a gasket or a spacer sandwiched between a third diaphragm and a fourth diaphragm each supported with a frame.

[0337] The volume of each of the first plating solution circulation chamber and / or the second plating solution circulation chamber is not particularly limited, and an appropriate volume can be selected depending on a required rate of metal ion feeding (amount of electrolysis per time). In particular, the first plating solution circulation chamber and / or the second plating solution circulation chamber each having the cell structure are / is preferred because the width of such a plating solution circulation chamber can be decreased to about 1 mm and the volume of such a plating solution circulation chamber can be decreased.

[0338] In the present embodiment, the volume of each of the first plating solution circulation chamber and / or the second plating solution circulation chamber can be decreased to decrease the amount of the plating solution remaining in the first plating solution circulation chamber and / or the second plating solution circulation chamber. Thus, the amount of the metal ion incorporated from the first plating solution circulation chamber and / or the second plating solution circulation chamber into the anode chamber can be decreased, and as a result, the passivation of an anode surface can be suppressed. For example, the distance between the first diaphragm and the second diaphragm and / or the distance between the third diaphragm and the fourth diaphragm can be decreased to decrease the volume of each of the first plating solution circulation chamber and / or the second plating solution circulation chamber.

[0339] The ratio of the volume of the plating solution circulation chamber (the total of the volume of the first plating solution circulation chamber and the volume of the second plating solution circulation chamber) to the volume of the anode chamber (Volume of plating solution circulation chamber / Volume of anode chamber) is not particularly limited, and is preferably 0.005 to 0.5, more preferably 0.01 to 0.2, most preferably 0.01 to 0.1. When the above ratio falls within the above numerical value range, passivation of an anode surface can be suppressed.

[0340] The flow rate in circulation of the plating solution in the first plating solution circulation chamber and / or the second plating solution circulation chamber is not particularly limited, and any flow rate at which the change in concentration in the plating solution in the plating solution circulation chamber is not too large can be selected depending on a required rate of metal ion feeding (amount of electrolysis per time). In this regard, in a case where no electrolysis is performed, it is preferable for minimizing ion diffusion via the first diaphragm and the third diaphragm to stop the circulation or sufficiently decrease the flow rate. However, in a case where the circulation is stopped, a crystal or the like may be precipitated in the first plating solution circulation chamber and / or the second plating solution circulation chamber by the change in composition due to ion diffusion via the first diaphragm and the third diaphragm. Therefore, in the case of stopping for a certain period or more, it is preferable to bleed the plating solution(s) in the first plating solution circulation chamber and / or the second plating solution circulation chamber, or exchange the plating solution(s) in the first plating solution circulation chamber and / or the second plating solution circulation chamber by circulation periodically performed.(Plating Solution)

[0341] The metal ion feeding system of the present embodiment can further include the plating solution(s) included in the first plating solution circulation chamber and / or the second plating solution circulation chamber.

[0342] The composition of such a plating solution can be appropriately set depending on a metal to be plated in the electrolytic plating apparatus. The composition of such a plating solution is determined with the metal to be plated in the electrolytic plating apparatus, and a combination of the anode and the anolyte is determined depending on the composition of such a plating solution. Such a plating solution can contain an ion of the same metal as the metal included in the anode. For example, in the case of use of Sn as the metal of the anode, such a plating solution can contain a Sn2+ ion. The metal described in the section “Anode” above can be used as the metal included in the anode.

[0343] The concentration of the ion of the same metal as the metal included in the anode, in the plating solution, is not particularly limited, and an appropriate concentration can be selected depending on the type of the metal to be plated, the specification of a plated film, the demanded uniformity of the plated film, and the like. For example, the concentration of the ion of the same metal as the metal included in the anode can be 10 to 200 g / L, 20 to 150 g / L, or 30 to 100 g / L. When the concentration falls within the above numerical value range, the plated film is excellent in uniformity.

[0344] The plating solution is not particularly limited, and a Sn alloy plating solution, a copper sulfate plating solution, or a Ni sulfamate plating solution can be used. Among them, a Sn alloy plating solution can be particularly used.

[0345] The plating solution circulated between the first plating solution circulation chamber and the second plating solution circulation chamber, and the electrolytic plating apparatus can contain a metal ion. The metal ion is not particularly limited, and examples include Ag+, Sn2+, Cu2+, Bi3+ or any combination of two or more kinds thereof. Among them, a combination of Ag+ and Sn2+ can be particularly used.(First Diaphragm and Third Diaphragm)

[0346] In the present embodiment, the first diaphragm is formed with the same material as that of the third diaphragm.

[0347] The first diaphragm and / or the third diaphragm are / is not particularly limited, and an ion exchange membrane or a neutral porous membrane can be used. Among them, an ion exchange membrane is preferred. The ion exchange membrane is not particularly limited, and a cation exchange membrane is preferred. The cation exchange membrane can be used to transfer the metal ion contained in the anolyte in the anode chamber to the plating solution circulation chamber. The cation exchange membrane used here can be a fluorine-based cation exchange membrane or a hydrocarbon-based cation exchange membrane. Among them, a fluorine-based cation exchange membrane is preferred because the diaphragm(s) are / is excellent in durability. In particular, in a case where a halide ion is contained in the anolyte, the diaphragm(s) tend(s) to be degraded and therefore a fluorine-based cation exchange membrane can be suitably used.

[0348] The fluorine-based cation exchange membrane used here can be any of commercially available products such as FORBLUE (registered trademark) Sx-2301 and Sx-1811 (all are manufactured by AGC Inc.) and Nafion (registered trademark) N424 and N438 (all are manufactured by Chemours), and the hydrocarbon-based cation exchange membrane used here can be any of commercially available products such as Selemion (registered trademark) CMVN (manufactured by AGC Inc.) and Neosepta (registered trademark) CSE (manufactured by ASTOM Corporation.).

[0349] The rate(s) of diffusion osmosis of water in the first diaphragm and / or the third diaphragm are / is not particularly limited, and are / is preferably 0.01 to 1 (mol / h·dm2·(mol / l)), more preferably 0.01 to 0.5 (mol / h·dm2·(mol / l)), most preferably 0.01 to 0.2 (mol / h·dm2·(mol / l)).(Second Diaphragm and Fourth Diaphragm)

[0350] In the present embodiment, the second diaphragm is formed with the same material as that of the fourth diaphragm.

[0351] The second diaphragm and / or the fourth diaphragm are / is not particularly limited, and a hydrogen ion permselective membrane, a bipolar membrane, or a monovalent cation permselective membrane can be used. Among them, a hydrogen ion permselective membrane or a bipolar membrane is particularly preferred. The hydrogen ion permselective membrane or the bipolar membrane can be used to inhibit the metal ion in the plating solution from permeating through the second diaphragm and the fourth diaphragm and entering the cathode chamber.

[0352] The hydrogen ion permselective membrane used here can be a commercially available product such as Selemion (registered trademark) HSFN (manufactured by AGC Engineering Co., Ltd.). The bipolar membrane used here can be a commercially available product such as Neosepta (registered trademark) BP-1EX (manufactured by ASTOM Corporation.).

[0353] The rate(s) of diffusion osmosis of water in the second diaphragm and / or the fourth diaphragm are / is not particularly limited, and are / is preferably 0.1 to 5 (mol / h·dm2·(mol / l)), most preferably 0.2 to 3 (mol / h·dm2·(mol / l)).

[0354] In the metal ion feeding system, preferably, the first diaphragm and the third diaphragm are cation exchange membranes, and the second diaphragm and the fourth diaphragm are hydrogen ion permselective membranes or bipolar membranes. Such a combination can be adopted to feed a metal ion to the plating solution at a high electric current efficiency.

[0355] In the metal ion feeding system, the rates of diffusion osmosis of water in the second diaphragm and the fourth diaphragm may be higher than the rates of diffusion osmosis of water in the first diaphragm and the third diaphragm.

[0356] The difference between the rates of diffusion osmosis of water in the second diaphragm and the fourth diaphragm and the rates of diffusion osmosis of water in the first diaphragm and the third diaphragm is not particularly limited, and is preferably more than 0 and 5 or less (mol / h·dm2·(mol / l)), more preferably 0.1 to 3 (mol / h·dm2·(mol / l)), most preferably 0.2 to 2 (mol / h·dm2·(mol / l)). The ratio of the rates of diffusion osmosis of water in the second diaphragm and the fourth diaphragm to the rates of diffusion osmosis of water in the first diaphragm and the third diaphragm (Rates of diffusion osmosis of water of second diaphragm and fourth diaphragm / Rates of diffusion osmosis of water of first diaphragm and third diaphragm) is not particularly limited, and is preferably more than 1 and 100 or less, more preferably 3 to 50, most preferably 5 to 30.(One or More Stacked Module)

[0357] One or more stacked module(s) is placed between the first plating solution circulation chamber and the cathode.

[0358] Each stacked module in the one or more stacked module(s) includes an anolyte chamber packed with an anolyte and a second plating solution circulation chamber defined by the third diaphragm and the fourth diaphragm.

[0359] The number of such stacked module(s) may be one or more. The number of such stacked module(s) is not particularly limited, and is preferably 1 to 5, more preferably 1 to 3, most preferably 1 to 2. When the number of such stacked module(s) falls within the above numerical value range, not only the structure is not too complicated and the area of a diaphragm used is minimized, but also sludge generation in the anolyte can be suppressed. In examples in FIGS. 6 and 7, the number of such stacked module(s) is 1.(Anolyte Chamber)

[0360] The anolyte chamber can accommodate the anolyte.

[0361] The volume of the anolyte chamber is not particularly limited.

[0362] The anolyte chamber can include no anode.

[0363] The anolyte packed in the anolyte chamber can be the same as the above anolyte packed in the anode chamber. The anolyte chamber is preferably linked to the anode chamber so that the anolyte is circulatable by a pipe, a circulation pump, or the like. The anolyte can be circulated between the anode chamber-anolyte chamber to allow for feeding of a metal ion dissolved from the anode also to the anolyte chamber, thereby not only stabilizing the composition of the anolyte in the anolyte chamber, but also stirring the inside of the anolyte chamber.

[0364] The flow rate in circulation of the anolyte between the anode chamber-anolyte chamber is not particularly limited, and any flow rate at which the change in concentration in the plating solution in the anolyte chamber is not too large may be selected depending on a required rate of metal ion feeding (amount of electrolysis per time). In this regard, in a case where no electrolysis is performed, it is preferable for minimizing ion diffusion via the first diaphragm to stop the circulation or sufficiently decrease the flow rate.(Other Configurations)

[0365] The metal ion feeding system can further include an external power source connected to the cathode and the anode. A reverse electric current prevention mechanism (diode or the like) is preferably disposed in the external power source. The reverse electric current prevention mechanism can be disposed to prevent a reverse electric current from flowing and causing movement of a metal ion into the anolyte during stopping.

[0366] In the present embodiment, the metal ion feeding system can further include a reserve tank in which the catholyte is circulated between the tank and the cathode chamber. A gas containing oxygen (air or the like) can be blown (bubbled) in the reserve tank. The reserve tank is exemplified and described below.

[0367] FIG. 2 is an enlarged view of the vicinity of the cathode chamber in the metal ion feeding system. The metal ion feeding system includes a cathode chamber 1300, a cathode 1700, a fourth diaphragm 2550, and the like.

[0368] In the metal ion feeding system illustrated in FIG. 2, a reserve tank 1310 is provided and the reserve tank 1310 can allow the catholyte to be circulated between the tank and the cathode chamber 1300.

[0369] The catholyte may slightly contain a metal ion (Sn2+ or the like) moving from the plating solution circulation chamber via the fourth diaphragm 2550. The metal ion may be precipitated on a cathode surface, and such a precipitate is generated to cause an increase in electrolytic voltage. In the reserve tank 1310, a gas containing oxygen is blown to oxidize the metal ion, thereby providing an oxidized metal ion (Sn4+ or the like), and the oxidized metal ion is precipitated as a hydroxide and thus can be removed with a filter. Thus, the metal ion (Sn2+ or the like) moving from the plating solution circulation chamber can be inhibited from being precipitated on the cathode surface, and the increase in electrolytic voltage can be prevented.

[0370] The first plating solution circulation chamber and / or the second plating solution circulation chamber each placed between the anode chamber and the cathode chamber in the metal ion feeding system of the present embodiment can have the same structure as the cell structure of an electrodialyzer. Specifically, as illustrated in FIG. 3, an inner space of a gasket 1230 / spacer 1240 sandwiched between a first diaphragm 1400 supported with a frame 1110 and a gasket 1120 and a second diaphragm 1500 supported with a frame 1320 and a gasket 1330 can be adopted as the first plating solution circulation chamber.

[0371] The first diaphragm 1400 and the second diaphragm 1500 are illustrated in FIG. 3, and may be replaced respectively with a third diaphragm and a fourth diaphragm. In this case, an inner space of a gasket 1230 / spacer 1240 sandwiched between a third diaphragm supported with a frame 1110 and a gasket 1120 and a fourth diaphragm supported with a frame 1320 and a gasket 1330 can be adopted as the second plating solution circulation chamber.

[0372] The above structure can be adopted to minimize the volume(s) of the first plating solution circulation chamber and / or the second plating solution circulation chamber (a width of about 1 mm). As a result, it is possible to minimize the influence by dilution or loss of the plating solution in replacement of the plating solution circulation chamber with a liquid substantially free of at least one of metal ions described later.

[0373] The first plating solution circulation chamber in the metal ion feeding system of the present embodiment may also be a space defined with a first diaphragm and a second diaphragm each supported with a frame. The second plating solution circulation chamber may be a space defined by a third diaphragm and a fourth diaphragm each supported with a frame.

[0374] A metal ion feeding method to an electrolytic plating apparatus, including step (i) of feeding metal ions and step (ii) of not performing feeding of the metal ions in the second embodiment, can be applied to the metal ion feeding system of the present embodiment (third embodiment). In this case, the first plating solution circulation chamber and the second plating solution circulation chamber can be used in the plating solution circulation chamber.

[0375] As described above, the inside of the first plating solution circulation chamber and the inside of the second plating solution circulation chamber can be replaced with a liquid substantially free of at least one of metal ions fed to the electrolytic plating apparatus in step (ii) that is a step of feeding no metal ions, thereby suppressing passivation of an anode surface due to a metal ion incorporated from the first plating solution circulation chamber and the second plating solution circulation chamber also in the metal ion feeding system of the present embodiment (third embodiment).

[0376] The metal ion feeding system is a system for feeding a metal ion to an electrolytic plating apparatus. The electrolytic plating apparatus can be the same as the electrolytic plating apparatus described in “1. First embodiment” above.

[0377] Two or more of the above first to third embodiments can be combined.

[0378] In some embodiments of the present invention, the following configuration may be included.

[0379] (1) A metal ion feeding system for an electrolytic plating apparatus, the metal ion feeding system including

[0380] an anode chamber,

[0381] an anode disposed in the anode chamber,

[0382] a cathode chamber,

[0383] a cathode disposed in the cathode chamber,

[0384] a plating solution circulation chamber placed between the anode chamber and the cathode chamber,

[0385] a first diaphragm placed between the anode chamber and the plating solution circulation chamber, and

[0386] a second diaphragm placed between the cathode chamber and the plating solution circulation chamber,

[0387] wherein the plating solution circulation chamber includes an outlet for bleeding a plating solution to an electrolytic plating apparatus, and an inlet for receiving the plating solution from the electrolytic plating apparatus so that the plating solution is circulatable,

[0388] a rate of diffusion osmosis of water in the second diaphragm is higher than a rate of diffusion osmosis of water in the first diaphragm,

[0389] an anolyte containing an ion of the same metal as the metal included in the anode is packed in the anode chamber,

[0390] a catholyte is packed in the cathode chamber, and

[0391] the catholyte has a higher osmol concentration than an osmol concentration in the plating solution in the plating solution circulation chamber.

[0392] (2) The metal ion feeding system according to (1), wherein the anode is a soluble anode.

[0393] (3) The metal ion feeding system according to (1) or (2), wherein the first diaphragm is a cation exchange membrane, and the second diaphragm is a hydrogen ion permselective membrane or a bipolar membrane.

[0394] (4) A metal ion feeding method to an electrolytic plating apparatus, the method including

[0395] (i) a step of circulating a plating solution containing metal ions between a plating solution circulation chamber and an electrolytic plating apparatus, to feed the metal ions to the electrolytic plating apparatus, and

[0396] (ii) a step of not performing feeding of the metal ions to the electrolytic plating apparatus, in which the step is to replace an inside of the plating solution circulation chamber with a liquid substantially free of at least one of the metal ions.

[0397] (5) The metal ion feeding method according to (4), further including a step of bleeding the plating solution in the plating solution circulation chamber or the liquid substantially free of at least one of the metal ions, to an external other than the electrolytic plating apparatus, during switching between step (i) that is a step of feeding metal ions and step (ii) that is a step of feeding no metal ions.

[0398] (6) The metal ion feeding method according to (4), further including a step of stopping an operation of the plating solution circulation chamber and bleeding the plating solution in the plating solution circulation chamber or the liquid substantially free of at least one of the metal ions, to an external other than the electrolytic plating apparatus, during switching between step (i) that is a step of feeding metal ions and step (ii) that is a step of feeding no metal ions.

[0399] (7) The metal ion feeding method according to any one of (4) to (6), wherein a metal ion feeding system in which the plating solution circulation chamber is placed between an anode chamber and a cathode chamber is used.

[0400] (8) The metal ion feeding method according to any one of (4) to (6), the method being performed with a metal ion feeding system according to (1).

[0401] (9) A metal ion feeding system for an electrolytic plating apparatus, the metal ion feeding system including

[0402] an anode chamber that includes an anode and that is packed with an anolyte,

[0403] a cathode chamber that includes a cathode and that is packed with a catholyte,

[0404] a first plating solution circulation chamber defined with a first diaphragm and a second diaphragm and placed between the anode chamber and the cathode chamber, and

[0405] one or more stacked module placed between the first plating solution circulation chamber and the cathode, the stacked module including an anolyte chamber packed with an anolyte and a second plating solution circulation chamber defined with a third diaphragm and a fourth diaphragm,

[0406] wherein the third diaphragm is formed from the same material as that of the first diaphragm, and the fourth diaphragm is formed from the same material as that of the second diaphragm,

[0407] the first plating solution circulation chamber and the second plating solution circulation chamber each include an outlet for bleeding a plating solution to an electrolytic plating apparatus, and an inlet for receiving the plating solution from the electrolytic plating apparatus so that the plating solution is circulatable, and

[0408] the anolyte chamber includes an outlet for bleeding the anolyte from the anolyte chamber and an inlet for receiving the anolyte in the anolyte chamber so that the anolyte in the anode chamber is capable of being in fluid communication.

[0409] (10) The metal ion feeding system according to (9), wherein the first diaphragm and the third diaphragm are cation exchange membranes, and the second diaphragm and the fourth diaphragm are hydrogen ion permselective membranes or bipolar membranes.

[0410] Although the embodiments of the present invention have been described above based on some examples, the described embodiments are for the purpose of facilitating the understanding of the present invention and are not intended to limit the present invention. The present invention may be modified and improved without departing from the spirit thereof, and the invention includes equivalents thereof. In addition, the elements described in the claims and the specification can be arbitrarily combined or omitted within a range in which the above-mentioned problems are at least partially solved, or within a range in which at least a part of the advantages is achieved.

[0411] This application claims priority under the Paris Convention to Japanese Patent Application No. 2024-176355 filed on Oct. 8, 2024. The entire disclosure of Japanese Patent Application No. 2024-176355 filed on Oct. 8, 2024 including specification, claims, drawings and summary is incorporated herein by reference in its entirety. The entire disclosure of U.S. Pat. No. 9,637,836 (PTL 1) including specification, claims, drawings and summary is incorporated herein by reference in its entirety.EXAMPLES

[0412] Hereinafter, the present invention is described with reference to Examples, but the present invention is not limited thereto.

[0413] Test Examples 1 to 6 described below are Test Examples corresponding to the first embodiment.Test Example 1

[0414] The following studies were made in order to confirm feeding performance of a metal ion (Cu2+) of a metal ion feeding system with a 3-chamber cell (including the anode chamber, the first diaphragm, the plating solution circulation chamber, the second diaphragm, and the cathode chamber in the listed order).

[0415] Voltage stability during continuous electrolysis

[0416] Each change in pH during continuous electrolysis and during no electrolysis

[0417] Each change in concentration of inorganic component during continuous electrolysis and during no electrolysis

[0418] FIG. 8 illustrates the 3-chamber cell used. Table 2 shows electrolytic solutions (catholyte, plating solution, anolyte) and electrode·diaphragms used, electrolysis conditions, and evaluations performed.

[0419] In Test Example 1, the osmol concentration in the plating solution and the osmol concentration in the catholyte were not adjusted, and Test Example 1 corresponded to Comparative Example of the first embodiment. The osmol concentration in the plating solution is about 3.4 mol / L and the osmol concentration in the catholyte is about 2.1 mol / L at the start of the test.TABLE 2ItemConditionsElectrolytic solutionCatholyte: VMS (0-100-0)*1, no additive 350 mlPlating sol.: VMS (50-100-50)*1, no additive 450 mlAnolyte: VMS (50-0.5-0)*1, no additive, 350 mlElectrode-diaphragmCathode: Pt / Ti lath*2Anode: Cu—P ball Φ11 mm*3 × 19 pcs (~82 cm2) + Ti lath case*4Membrane - anode side: FORBLUE Sx-2301, opening 5 × 5 cmMembrane - cathode side: HSFN, opening 5 × 5 cmElectrolysisElectric current: 1.5 A (Membrane CD*5: 6ASD), 0 A (w / o plating*6,conditionsagitation only)Agitation: 80 rpm, T4*7 (plating sol.), air bubbling (anolyte)Electrolysis time: 5 hrTemperature: no controlEvaluationMeasurement of weights of anode and cathode before and aftertestChange in amount of liquid of each of anolyte, plating solution,and catholyte before and after testLiquid analysis before and after test (ECI*8, UV-Vis*9)Voltage stability during electrolysis*1Respective numbers parenthesized after VMS refer to concentration (g / L) of copper, concentration (g / L) of sulfuric acid, and concentration (mg / L) of chlorine. For example, VMS (0-100-0) means copper: 0 g / L, sulfuric acid: 100 g / L, and chlorine: 0 mg / L.*2Pt-coating, lath-shaped Ti mesh*3manufactured by Mitsubishi Materials Corporation*4Lath-shaped titanium anode basket (insoluble electrode)*5Electric current density based on diaphragm area*6No electrolysis*7T4 (4-mm thick paddle) used*8Analyzer QL-10 (manufactured by ECI Technology Inc.)*9Spectrophotometer UV-2600 (manufactured by Shimadzu Corporation)

[0420] The details of measurement methods in the item “Evaluation” in Table 2 are shown below.[Measurement of Weights of Anode and Cathode Before and After Test]

[0421] The anode and the cathode after an electrolysis test were taken out from a test cell, and the weights thereof after washing with water and drying were measured with an electronic balance. The difference between the weight before the test and the weight after the test was determined with respect to each of the anode and the cathode, and was defined as the change in weight.[Change in Amount of Liquid of Each of Anolyte, Plating Solution, and Catholyte Before and After Test]

[0422] The anolyte, the plating solution, and the catholyte after the electrolysis test were recovered from the test cell as much as possible, and the amount of the liquid of each thereof was measured with a measuring cylinder.[Liquid Analysis Before and After Test]Sulfuric acid concentration: the anolyte, the plating solution, and the catholyte were each sampled before and after the electrolysis test, and the concentration was determined with a sodium hydroxide solution according to acid-base titration.

[0424] Cu concentration: the anolyte, the plating solution, and the catholyte were each sampled before and after the electrolysis test, and precisely diluted 50-fold with pure water, to provide each liquid, and the amount of such each liquid was quantitatively determined by absorbance determination (wavelength: 810 nm) performed with a spectrophotometer.

[0425] The sulfuric acid concentration and the Cu concentration obtained as above, and the amount of each liquid of the anolyte, the plating solution, and the catholyte, as measured as above, were used to determine the amounts (molar numbers) of Cu and sulfuric acid in such each liquid.[Voltage Stability During Electrolysis]

[0426] A voltage logger was used to monitor the voltage between the anode and the cathode during the electrolysis test.

[0427] The results are represented in FIGS. 9A to 12.

[0428] FIGS. 9A to 9C are graphs representing the change in amount (mol) of Cu2+ in the anolyte, the plating solution, or the catholyte during the test. FIGS. 10A to 10 C is each graph representing the change in amount (Liter) of each liquid of the anolyte, the plating solution, or the catholyte during the test. FIG. 11 is a graph representing the change in pH of the anolyte during the test. FIG. 12 is a photograph illustrating the appearance of the cathode after the test. In FIGS. 9 to 11, “6 ASD” represents the case of voltage application at an electric current density of 6 ASD, and “0 ASD” represents the case of stirring of such each liquid without voltage application. During the test, a state was kept in which the osmol concentration in the plating solution was always higher than the osmol concentration in the catholyte.

[0429] As clear from the graph of FIG. 9B, the amount of Cu2+ in the plating solution in the plating solution circulation chamber was increased due to electrolysis. It was thus confirmed that the 3-chamber cell could function as a metal ion (Cu2+) feeding system. As clear from the graphs of FIGS. 9A and 9C, no large changes in amounts of Cu2+ in the anolyte and the catholyte were observed.

[0430] In this regard, as clear from the graphs of FIGS. 10A and 10B, the amount of the plating solution in the plating solution circulation chamber was increased and the amount of the liquid of the anolyte in the anode chamber was decreased due to electrolysis. It is presumed from these results that electro-osmosis of water from the anolyte to the plating solution in association with movement of Cu2+ occurs to dilute the plating solution with water. Dilution of the plating solution in the plating solution circulation chamber is not preferred because the composition of the plating solution fed to the electrolytic plating apparatus is varied.Test Example 2

[0431] In order to study the 3-chamber cell of Test Example 1 in more detail, an electrolysis test was performed in the same manner as in Test Example 1 except that the osmol concentration in the catholyte was changed. In addition, simulation of the electrolysis test with respect to the 3-chamber cell was performed in a condition where the osmol concentration in the catholyte was changed. In the simulation, a personal computer provided with spreadsheet software (Excel (registered trademark) of Microsoft Corporation) was used. In the simulation, computing was performed under the assumption that the amount of electro-osmotic water permeating through a membrane was proportional to the amount of an ion permeating through the membrane and the amount of osmotic water due to diffusion was proportional to the difference in osmol concentration between liquids at both sides of the membrane.

[0432] In the electrolysis test and the simulation, the osmol concentration in the plating solution was set to about 3.4 mol / L and the electric current density was set to 6 ASD.

[0433] The parameters of the diaphragms used in the simulation are shown in Tables 3 and 4 below. As clear from the value of kw in Table 3, the rate of diffusion osmosis of water in an HSFN membrane (second diaphragm) was set so as to be higher than that in an Sx-2301 membrane (first diaphragm).TABLE 3CoefficientSx-2301HSFNkw0.060.72* kw: Coefficient of diffusion rate of waterTABLE 4HSFNSx-2301Water movementWater movementaccording toType ofaccording toIon conductivityelectrolysisIon conductivityionelectrolysis (mol / F)(relative value)(mol / F)(relative value)Cu2+8181H+3438000The results of the electrolysis test and the simulation are represented in FIGS. 13A to 18.

[0435] FIGS. 13A to 13C are graphs relating to the change in concentration (g / L) of Cu2+ or H2SO4 in an anolyte, a plating solution, or a catholyte in a case where the concentration of the catholyte (H2SO4) is set to 100 g / L. FIG. 14 is a graph relating to the change in amount (L) of each liquid (anolyte, plating solution, catholyte) in a case where the concentration of the catholyte is set to 100 g / L. In a case where the concentration of the catholyte is 100 g / L, the osmol concentration of the catholyte is about 2.1 mol / L. During the electrolysis test and the simulation in FIGS. 13A to 13C and FIG. 14, a state was kept in which the osmol concentration in the plating solution was always higher than the osmol concentration in the catholyte, and corresponded to Comparative Example of the first embodiment.

[0436] FIGS. 15A to 15C are graphs relating to the change in concentration (g / L) of Cu2+ or H2SO4 in an anolyte, a plating solution, or a catholyte in a case where the concentration of the catholyte is set to 230 g / L. FIG. 16 is a graph relating to the change in amount (L) of each liquid (anolyte, plating solution, catholyte) in a case where the concentration of the catholyte is set to 230 g / L. In a case where the concentration of the catholyte is 230 g / L, the osmol concentration of the catholyte is about 4.7 mol / L. During the electrolysis test and the simulation in FIGS. 15A to 15C and FIG. 16, a state was kept in which the osmol concentration in the catholyte was always higher than the osmol concentration in the plating solution, and corresponded to Example of the first embodiment.

[0437] FIG. 17A to 17C are graphs relating to the change in concentration (g / L) of Cu2+ or H2SO4 in an anolyte, a plating solution, or a catholyte in a case where the concentration of the catholyte is set to 300 g / L. FIG. 18 is a graph relating to the change in amount (L) of each liquid (anolyte, plating solution, catholyte) in a case where the concentration of the catholyte is set to 300 g / L. In a case where the concentration of the catholyte is 300 g / L, the osmol concentration of the catholyte is about 6.3 mol / L. During the electrolysis test and the simulation in FIGS. 17A to 17C and FIG. 18, a state was kept in which the osmol concentration in the catholyte was always higher than the osmol concentration in the plating solution, and corresponded to Example of the first embodiment.

[0438] Respective solid lines or dotted lines with respect to “Anolyte”, “Catholyte” or “Plating sol.” in FIGS. 13A to 18 represent the simulation results. Plots (circles, triangles, or rectangles) with respect to “Anolyte experiment”, “Catholyte experiment” or “Plating sol. experiment” in FIGS. 13A to 18 represent the actual results of the electrolysis test performed in the same manner as in Test Example 1.

[0439] It has been found from the results in FIGS. 13A to 18 that the actual results of the electrolysis test are well matched with the results of the simulation and the electrolysis test can be sufficiently replicated by the simulation.

[0440] In the electrolysis test and the simulation in FIGS. 13A to 13C and FIG. 14, the osmol concentration in the catholyte (about 2.1 mol / L at the start of the test) is lower than the osmol concentration in the plating solution (about 3.4 mol / L at the start of the test). It has been found from the graph of FIG. 13B that the concentration of Cu2+ in the plating solution is increased over time and Cu2+ can be sufficiently fed to the plating solution. In this regard, it has been found from the graph in FIG. 14 that the amount of the plating solution is increased and dilution with water progresses over time. The plating solution, if diluted, cannot be directly used for electrolytic plating, and causes a need for addition of a fresh plating solution after wasting, leading to an increase in cost of plating treatment.

[0441] In the electrolysis test and the simulation in FIGS. 15A to 15C and FIG. 16, the osmol concentration in the catholyte (about 4.7 mol / L at the start of the test) is higher than the osmol concentration in the plating solution (about 3.4 mol / L at the start of testing). It has been found from the graph of FIG. 15B that the concentration of Cu2+ in the plating solution is increased over time and Cu2+ can be sufficiently fed to the plating solution. It has been found from the graph in FIG. 16 that the amount of the plating solution is constantly kept even over time and no dilution with water occurs. The amount of the plating solution can be thus constantly kept to make the adjustment of the plating solution unnecessary and allow for continuous plating treatment.

[0442] In the electrolysis test and the simulation in FIGS. 17A to 17C and FIG. 18, the osmol concentration in the catholyte (about 6.3 mol / L at the start of testing) is higher than the osmol concentration in the plating solution (about 3.4 mol / L at the start of the test). It has been found from the graph of FIG. 17B that the concentration of Cu2+ in the plating solution is increased over time and Cu2+ can be sufficiently fed to the plating solution. It has been found from the graph in FIG. 18 that the amount of the plating solution is decreased over time and concentration of the plating solution occurs. In a case where such concentration of the plating solution occurs, the amount of the plating solution can be easily adjusted by externally adding water to the plating solution circulation chamber, and therefore the countermeasure for such concentration of the plating solution can be sufficiently made. In this regard, this adjustment is difficult in the case of the dilution of the plating solution as observed in FIG. 14, and thus the countermeasure is difficult.Test Example 3

[0443] A metal ion feeding system with a 3-chamber cell described later (including the anode chamber, the first diaphragm, the plating solution circulation chamber, the second diaphragm, and the cathode chamber in the listed order) was selected as a mass-producible apparatus, and simulation of the electrolysis test was performed. In the simulation, a personal computer provided with spreadsheet software (Excel (registered trademark) of Microsoft Corporation) was used as in Test Example 2. In the simulation, the osmol concentration in the plating solution was set to about 3.4 mol / L and the osmol concentration in the catholyte was set to about 4.7 mol / L. During the simulation, a state was kept in which the osmol concentration in the catholyte was always higher than the osmol concentration in the plating solution, and corresponded to Example of the first embodiment.

[0444] The parameters of the diaphragms used in the simulation were the same as those in Tables 3 and 4 of Test Example 2 described above.

[0445] Table 5 below shows the plating solution, the electrodes diaphragms, plating conditions, and the like set in the simulation. As shown in Table 5, the electrolysis test was set so that, if 1.25 L of the anolyte (DIW (ultrapure water)) in the anode chamber was decreased, 1.25 L of the anolyte was fed in order to add the anolyte. The electrolysis test was also set so that, if 0.5 L of the catholyte (H2SO4 solution) in the cathode chamber was increased, 0.68 L of the catholyte was bled and 0.18 L thereof was fed in order to remove the catholyte.TABLE 5Anode chamberPlating solution chamberCathode chamberMembraneSx-2301 (20 dm2)HSFN (20 dm2)ElectrodeCu soluble—Insoluble (Pt / Ti lath)Chemical supplyDIW—dil. H2SO4 (60%)(1.25 L fed if decreased(0.68 L bled and 0.18 Lby 1.25 L)fed if 0.5 L increased)Initial electrolyteCuSO4•5H2O 196 g / LCuSO4•5H2O 196 g / LH2SO4 225 g / LH2SO4 0.5 g / LH2SO4 100 g / LVolume25 L473 L10 LElectric current100 A (Both plating cell and Cu supplying cell)

[0446] The simulation results are represented in FIGS. 19A to 19C and FIG. 20.

[0447] FIGS. 19A to 19C are graphs relating to the change in concentration (g / L) of Cu2+ or H2SO4 in an anolyte, a plating solution, or a catholyte. FIG. 20 is a graph relating to the change in amount (L) of each liquid (anolyte, plating solution, catholyte).

[0448] It has been found from the graph of FIG. 19B that the concentration of Cu2+ in the plating solution can be constantly maintained at a sufficient value regardless of a lapse of time and a sufficient function as a metal ion feeding system can be exhibited. It has been found from the graph in FIG. 20 that the amount of the plating solution is constantly kept even after a lapse of time and no dilution with water occurs. The amount of the plating solution can be thus constantly kept to make the adjustment of the plating solution unnecessary and allow for continuous plating treatment. It has been further found from the graph in FIG. 20 that both the amount of the anolyte and the amount of the catholyte can be constantly maintained by performing addition of the anolyte in the anode chamber and removal of the catholyte in the cathode chamber together and a continuous operation can be made without stopping of any system.

[0449] It has been found from these results that it is important to allow the osmol concentration in the catholyte to be higher than the osmol concentration in the plating solution also in the mass-producible apparatus.Test Example 4

[0450] A metal ion feeding system with a 3-chamber cell (including the anode chamber, the first diaphragm, the plating solution circulation chamber, the second diaphragm, and the cathode chamber in the listed order) was prepared. A plating solution of a plating tank with an undissolved anode was used and the stability of the composition of the plating solution during metal ion feeding with the metal ion feeding system was confirmed.

[0451] FIG. 21 is a cross-sectional view of the entire configuration of a 3-chamber cell 2100 and a plating cell (plating tank) 10 used.

[0452] A first diaphragm 1400 and a second diaphragm 1500 used in the 3-chamber cell 2100 were each the same membrane as in Test Example 1. Both the opening areas of the first diaphragm 1400 and the second diaphragm 1500 were 0.374 dm2, the width of the plating solution circulation chamber (distance between first diaphragm 1400 and second diaphragm 1500) was 8 mm, and the inner volume of the plating solution circulation chamber was 30 ml. A cathode 1700 (Pt / Ti lath electrode was used) was disposed in a cathode chamber in the 3-chamber cell 2100 and an anode case 1610 (one made of Ti lath was used) in which about 150 g of an anode 1600 (Cu ball (phosphorus-containing copper, diameter 12 mm) was used) was placed was disposed in an anode chamber in the 3-chamber cell 2100. In addition, 300 ml of a catholyte (sulfuric acid solution, concentration: 233 g / L, osmol concentration: 4.8 mol / L) was placed in the cathode chamber in the 3-chamber cell 2100 and 300 ml of an anolyte (copper sulfate solution, Cu concentration: 50 g / L, pH: 3.3) was placed in the anode chamber in the 3-chamber cell 2100.

[0453] An anode electrode AN (undissolved anode (IrO2 / Ti lath electrode) was used) and a substrate (substrate to be plated) W (substrate with Cu membrane was used) were disposed in a plating cell 10, and 900 ml of a copper sulfate plating solution (Cu concentration: 50 g / L, sulfuric acid concentration: 100 g / L, chlorine concentration: 50 mg / L, osmol concentration: 3.3 mol / L) was placed therein.

[0454] A voltage was applied between the substrate to be plated W and the undissolved anode AN in the plating cell 10 with a stabilized power source under stirring with a paddle 15 in the plating cell 10, to perform plating treatment at an electric current of 2.14 A for 6 hours. A voltage was applied between the anode 1600 and the cathode 1700 in the 3-chamber cell 2100 with another stabilized power source, at the same time as the plating treatment, to perform electrolysis at an electric current of 2.14 A for 6 hours. During the electrolysis, the plating solution was circulated at a flow rate of 0.21 / min between the plating solution circulation chamber and the plating cell 10 in the 3-chamber cell 2100, with a liquid transfer pump, and a gas 1850 (air was used) was sent to the anode chamber to perform stirring of the anolyte (air stirring) (flow rate of air: 1 L / min).

[0455] After 2 hours and 4 hours from the start of plating and electrolysis treatment, the anolyte and the catholyte in the 3-chamber cell 2100 were subjected to the following adjustment.

[0456] Anolyte: the height of the liquid level was lowered (the amount of the liquid was decreased), and therefore pure water was fed until the height reached the height of the liquid level at the start of electrolysis.

[0457] Catholyte: the height of the liquid level was raised (the amount of the liquid was increased), and therefore the catholyte was determined to be diluted with osmotic water, the catholyte was partially extracted, furthermore a 47 g / L sulfuric acid solution was added, and the concentration and the amount of the liquid were adjusted. Herein, the amount of the catholyte extracted and the amount of sulfuric acid added were calculated and adjusted so that the concentration and the water level at the start of electrolysis were achieved.

[0458] After completion of the plating and electrolysis treatment, the plating solution was recovered as much as possible, and the amount of the liquid was measured with a measuring cylinder. The sulfuric acid concentration and the Cu concentration in each of the plating solution and the catholyte were measured before and after the test by the same methods as in Test Example 1. The osmol concentration was calculated from the measurement results, and the average osmol concentration was calculated from the osmol concentrations before and after the test. The difference between the average osmol concentration in the catholyte and the average osmol concentration in the plating solution was calculated. The results are shown in Table 6.Test Examples 5 and 6, and Comparative Example 1

[0459] The plating and electrolysis test was performed in the same manner as in Test Example 4 above except that the sulfuric acid concentration in the catholyte at the start of the plating and electrolysis treatment was changed to each concentration shown in Table 6. The results are shown in Table 6.Comparative Example 2

[0460] The plating test was performed with the plating cell 10 as in Test Example 4 in the same manner as in Test Example 4 except that no metal ion feeding was performed with the 3-chamber cell 2100. The results are shown in Table 6.TABLE 6TablBefore electrolysis / platingCatholytePlating solutionSulfuricSulfuricCuacidOsmolCuacidOsmolAmountCu ionconcentrationconcentrationconcentrationconcentrationconcentrationconcentrationof liquidfeeding(g / L)(g / L)(mol / L)(g / L)(g / L)(mol / L)(ml)TestYes02006.0501003.3900Example 4TestYes02004.0501003.3900Example 5TestYes03507.1501003.3900Example 6ComparativeYes01002.0501003.3900Example 1ComparativeNo———501003.3900Example 2After electrolysis / platingCatholytePlating solutionSulfuricSulfuricCuacidOsmolCuacidOsmolAmountconcentrationconcentrationconcentrationconcentrationconcentrationconcentrationof liquid(g / L)(g / L)(mol / L)(g / L)(g / L)(mol / L)(ml)Test02785.7501003.3899Example 4Test02164.448963.2940Example 5Test03296.7511023.4883Example 6Comparative01002.046923.0980Example 1Comparative———33127—805Example 2ChangeinAverage osmol conventrationamountDifferenceofPlatinginPlatingCatholytesolutionconcentrationsolution(mol / L)(mol / L)(CA − PL)(ml)(CA)(PL)(mol / L)Test−15.83.32.5Example 4Test404.53.21.3Example 5Test−176.93.33.6Example 6Comparative802.03.2−1.1Example 1Comparative—5——Example 2 indicates data missing or illegible when filed

[0461] In Test Examples 4 to 6, the average osmol concentration in the catholyte was higher than the average osmol concentration in the plating solution. Therefore, as shown in Table 6, Test Examples 4 to 6 exhibited suppressed dilution of the plating solution as compared with Comparative Example 1 in which the average osmol concentration in the catholyte was lower than the average osmol concentration in the plating solution.

[0462] In Comparative Example 2 in which no Cu ion feeding was performed with the 3-chamber cell 2100, the Cu concentration in the plating solution was significantly lowered and the sulfuric acid concentration was significantly raised after the test. In this regard, in Test Examples 4 to 6 in which Cu ion feeding was performed with the 3-chamber cell 2100, the changes in Cu concentration and sulfuric acid concentration in the plating solution before and after the test were relatively small, and the composition of the plating solution was stable.

[0463] It has been found from the above results that dilution of the plating solution in the plating solution circulation chamber can be suppressed by allowing the osmol concentration in the catholyte to be higher than the osmol concentration in the plating solution in the metal ion feeding system.REFERENCE SIGNS LIST10 . . . plating tank (plating cell)

[0465] 11 . . . substrate holder

[0466] 12 . . . anode unit

[0467] 13 . . . anode box

[0468] 13a . . . diaphragm

[0469] 14 . . . regulation plate

[0470] 15 . . . paddle

[0471] 16 . . . outer tank

[0472] W . . . substrate

[0473] AN . . . anode electrode

[0474] 200 . . . anode holder

[0475] 300 . . . anode mask

[0476] 700 . . . circulation mechanism

[0477] 702 . . . circulation line

[0478] 704 . . . valve

[0479] 706 . . . pump

[0480] 708 . . . temperature controller

[0481] 710 . . . filter

[0482] 1100 . . . anode chamber

[0483] 1110 . . . frame

[0484] 1120 . . . gasket

[0485] 1200 . . . plating solution circulation chamber

[0486] 1210 . . . outlet

[0487] 1220 . . . inlet

[0488] 1230 . . . gasket

[0489] 1240 . . . spacer

[0490] 1250 . . . gas feeding section

[0491] 1260 . . . feeding section of liquid substantially free of at least one of metal ions

[0492] 1270, 1280 . . . connecting section with waste tank

[0493] V1, V2, V3, V4, V5, V6, V7 . . . valve

[0494] 1300 . . . cathode chamber

[0495] 1310 . . . reserve tank

[0496] 1320 . . . frame

[0497] 1330 . . . gasket

[0498] 1400 . . . first diaphragm

[0499] 1500 . . . second diaphragm

[0500] 1600 . . . anode

[0501] 1610 . . . anode case

[0502] 1700 . . . cathode

[0503] 1800 . . . gas diffusion tube

[0504] 1850 . . . gas

[0505] 1900 . . . external power source

[0506] 2000 . . . metal ion feeding system

[0507] 2100 . . . 3-chamber cell

[0508] 2200 . . . first plating solution circulation chamber

[0509] 2210 . . . outlet

[0510] 2220 . . . inlet

[0511] 2400 . . . first diaphragm

[0512] 2450 . . . second diaphragm

[0513] 2500 . . . third diaphragm

[0514] 2550 . . . fourth diaphragm

[0515] 2800 . . . stacked module

[0516] 2810 . . . anolyte chamber

[0517] 2811 . . . outlet

[0518] 2812 . . . inlet

[0519] 2813, 2814 . . . pipe

[0520] 2820 . . . second plating solution circulation chamber

[0521] 2821 . . . outlet

[0522] 2822 . . . inlet

[0523] 2950 . . . nitrogen

[0524] 3000 . . . metal ion feeding system

Claims

1. A metal ion feeding system for an electrolytic plating apparatus, the metal ion feeding system comprisingan anode chamber,an anode disposed in the anode chamber,a cathode chamber,a cathode disposed in the cathode chamber,a plating solution circulation chamber placed between the anode chamber and the cathode chamber,a first diaphragm placed between the anode chamber and the plating solution circulation chamber, anda second diaphragm placed between the cathode chamber and the plating solution circulation chamber,wherein the plating solution circulation chamber comprises an outlet for bleeding a plating solution to an electrolytic plating apparatus, and an inlet for receiving the plating solution from the electrolytic plating apparatus so that the plating solution is circulatable,a rate of diffusion osmosis of water in the second diaphragm is higher than a rate of diffusion osmosis of water in the first diaphragm,an anolyte containing an ion of the same metal as the metal comprised in the anode is packed in the anode chamber,a catholyte is packed in the cathode chamber, andthe catholyte has a higher osmol concentration than an osmol concentration in the plating solution in the plating solution circulation chamber.

2. The metal ion feeding system according to claim 1, wherein the anode is a soluble anode.

3. The metal ion feeding system according to claim 1, wherein the first diaphragm is a cation exchange membrane, and the second diaphragm is a hydrogen ion permselective membrane or a bipolar membrane.

4. A metal ion feeding method to an electrolytic plating apparatus, the method comprising(i) a step of circulating a plating solution containing metal ions between a plating solution circulation chamber and an electrolytic plating apparatus, to feed the metal ions to the electrolytic plating apparatus, and(ii) a step of not performing feeding of the metal ions to the electrolytic plating apparatus, in which the step is to replace an inside of the plating solution circulation chamber with a liquid substantially free of at least one of the metal ions.

5. The metal ion feeding method according to claim 4, further comprising a step of bleeding the plating solution in the plating solution circulation chamber or the liquid substantially free of at least one of the metal ions, to an external other than the electrolytic plating apparatus, during switching between step (i) that is a step of feeding metal ions and step (ii) that is a step of feeding no metal ions.

6. The metal ion feeding method according to claim 4, further comprising a step of stopping an operation of the plating solution circulation chamber and bleeding the plating solution in the plating solution circulation chamber or the liquid substantially free of at least one of the metal ions, to an external other than the electrolytic plating apparatus, during switching between step (i) that is a step of feeding metal ions and step (ii) that is a step of feeding no metal ions.

7. The metal ion feeding method according to claim 4, wherein a metal ion feeding system in which the plating solution circulation chamber is placed between an anode chamber and a cathode chamber is used.

8. The metal ion feeding method according to claim 4, the method being performed with a metal ion feeding system for an electrolytic plating apparatus,wherein the metal ion feeding system comprisesan anode chamber,an anode disposed in the anode chamber,a cathode chamber,a cathode disposed in the cathode chamber,a plating solution circulation chamber placed between the anode chamber and the cathode chamber,a first diaphragm placed between the anode chamber and the plating solution circulation chamber, anda second diaphragm placed between the cathode chamber and the plating solution circulation chamber,and wherein the plating solution circulation chamber comprises an outlet for bleeding a plating solution to an electrolytic plating apparatus, and an inlet for receiving the plating solution from the electrolytic plating apparatus so that the plating solution is circulatable,a rate of diffusion osmosis of water in the second diaphragm is higher than a rate of diffusion osmosis of water in the first diaphragm,an anolyte containing an ion of the same metal as the metal comprised in the anode is packed in the anode chamber,a catholyte is packed in the cathode chamber, andthe catholyte has a higher osmol concentration than an osmol concentration in the plating solution in the plating solution circulation chamber.

9. A metal ion feeding system for an electrolytic plating apparatus, the metal ion feeding system comprisingan anode chamber that comprises an anode and that is packed with an anolyte,a cathode chamber that comprises a cathode and that is packed with a catholyte,a first plating solution circulation chamber defined with a first diaphragm and a second diaphragm and placed between the anode chamber and the cathode chamber, andone or more stacked module between the first plating solution circulation chamber and the cathode, the stacked module comprising an anolyte chamber packed with an anolyte and a second plating solution circulation chamber defined with a third diaphragm and a fourth diaphragm,wherein the third diaphragm is formed from the same material as that of the first diaphragm, and the fourth diaphragm is formed from the same material as that of the second diaphragm,the first plating solution circulation chamber and the second plating solution circulation chamber each comprise an outlet for bleeding a plating solution to an electrolytic plating apparatus, and an inlet for receiving the plating solution from the electrolytic plating apparatus so that the plating solution is circulatable, andthe anolyte chamber comprises an outlet for bleeding the anolyte from the anolyte chamber and an inlet for receiving the anolyte in the anolyte chamber so that the anolyte in the anode chamber is capable of being in fluid communication.

10. The metal ion feeding system according to claim 9, wherein the first diaphragm and the third diaphragm are cation exchange membranes, and the second diaphragm and the fourth diaphragm are hydrogen ion permselective membranes or bipolar membranes.

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