JP2014001410A - Plating method and plating apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a plating method and a plating apparatus which facilitate handling and can resupply Sn components to plating liquid efficiently.SOLUTION: The method comprises: a plating step in which a plating tank 1 for storing plating liquid containing Sn is divided, by an anion-exchange membrane 4, into a cathode chamber 21 where a substrate 2 under treatment is located and an anode chamber 31 where an insoluble anode electrode 3 is located, and plating is applied to the substrate 2 under treatment; a resupply step for generating resupply plating liquid by supplying tin oxide to the anode chamber plating liquid in the anode chamber 31 the acid concentration of which has increased due to the plating step; and an evening step for evening the plating liquid in the plating tank 1 by circulation between the resupply plating liquid and the plating liquid in cathode chamber 21.

Description

  The present invention relates to a plating method and a plating apparatus.

In a plating apparatus using an insoluble anode electrode, in order to maintain a constant concentration of the metal component in the plating solution, it is necessary to replenish the metal component with the plating process.
As a method for replenishing the metal component to the plating solution, for example, as disclosed in Patent Document 1, a replenisher tank (electrolytic bath for dissolving tin) is used as a replenisher solution (element solution) for the plating solution component separately from the plating bath. In general, a method of replenishing the plating solution from the replenishing tank to the plating tank and circulating the plating solution and the replenishing solution based on the analysis result of the component concentration of the plating solution.

  In the case of a plating solution containing Sn, a method of supplying metal ions to the plating solution using a tin oxide powder is also known. For example, in Patent Document 2, tin oxide powder is plated by spraying (spraying) tin oxide powder on the surface of the plating solution in a replenishing tank that stores the plating solution circulated between the plating tanks. It is supposed to dissolve in the liquid. Moreover, in patent document 3, the powder of a tin oxide is directly supplied to the flow of the plating solution sent to a plating tank from a replenishment tank, and without providing a special apparatus for stirring a plating solution, Dissolving the powder in the plating solution is disclosed.

Further, in Patent Document 4, a plating tank is disposed with an anode (anode) and a cathode (cathode) separated by an anion exchange membrane, and an anion of the same type as the plating solution is formed in an anode chamber separated from the plating bath. A method of performing plating by filling an anode chamber solution (acid solution) having s.
In this case, an amount of acid corresponding to the metal ions taken out of the system by plating is generated in the anode chamber solution. Therefore, the metal to be replenished with this anode chamber solution is dissolved and used as a replenisher solution. It is disclosed that it can be done.

Japanese Patent Laid-Open No. 2-70087 JP 2009-235526 A JP 2010-202941 A Japanese Patent Laid-Open No. 51-2900

As described above, in the method disclosed in Patent Document 1, it is necessary to prepare a component liquid separately when supplying the Sn component. Moreover, in the method of dissolving the tin oxide powder and replenishing the metal component as disclosed in Patent Documents 2 and 3, there is a concern that the dissolved residue adversely affects the plating quality.
Furthermore, the method disclosed in Patent Document 4 requires an anode chamber solution (acid solution) in addition to the plating solution, and separates the plating tank into a plating bath and an anode chamber, and separate solutions (plating solution and acid solution) in each chamber. The structure satisfying (liquid) has a problem that it is difficult to handle.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a plating method and a plating apparatus that are easy to handle and can efficiently supply Sn components to the plating solution.

  In the plating method of the present invention, a plating tank for storing a plating solution containing Sn is partitioned into a cathode chamber in which a substrate to be processed is disposed and an anode chamber in which an insoluble anode electrode is disposed by an anion exchange membrane, A plating step of plating the substrate to be treated, a replenishment step of generating a replenishing plating solution by supplying tin oxide to the anode chamber plating solution of the anode chamber whose acid component concentration has increased in accordance with the plating step, and The replenishing plating solution and the cathode chamber plating solution in the cathode chamber are circulated to each other to provide a homogenizing step for making the plating solution in the plating tank uniform.

As a result of electrolysis, Sn or Sn alloy is deposited on the substrate to be treated by a reduction reaction in the cathode chamber, and the Sn component concentration in the plating solution decreases. On the other hand, in the anode chamber, oxygen is generated on the surface of the insoluble anode electrode by the electrolysis reaction of water, and the H ion (H ⁺ ) concentration increases. Since the cathode chamber and the anode chamber are separated by an anion exchange membrane, the movement of cations from the anode chamber to the cathode chamber is restricted, and the acid component concentration in the anode chamber increases with plating. become.

  According to the plating method of the present invention, since it is decided to supply tin oxide to the anode chamber plating solution of the anode chamber whose acid component concentration has increased with plating, the high acid component can be obtained simply by supplying tin oxide. It can be easily dissolved in the anode chamber plating solution of a concentration. Further, the acid is consumed by the dissolution of tin oxide, and the initial plating solution before plating on the substrate to be processed can be returned to the state. In the present invention, since the same plating solution is used for the cathode chamber and the anode chamber, it is not necessary to prepare an acid solution separately from the plating solution as disclosed in Patent Document 4. By simply supplying tin oxide, it is possible to easily replenish the metal component that has disappeared due to the plating of the substrate to be processed, and it is easy to handle.

In the plating method of the present invention, the replenishing step is preferably performed when the acid component concentration of the anode chamber plating solution has increased by 15% or more of the initial concentration.
By replenishing tin oxide (Sn component) when the acid component concentration of the anode chamber plating solution is increased by 15% or more of the initial concentration, the dissolution efficiency of tin oxide can be sufficiently improved.
If the decrease in the Sn component concentration in the cathode chamber is less than 5%, the increase in the acid component concentration in the plating solution in the anode chamber may not be sufficient. May affect the sex. Therefore, the replenishment of the Sn component is preferably performed before the decrease of the Sn component concentration in the cathode chamber exceeds 10% with respect to the initial plating solution.

In the plating method of the present invention, the plating tank may be partitioned with the anion exchange membrane so that the anode chamber is 30% or less with respect to the volume of the cathode chamber.
By setting the anode chamber to 30% or less of the cathode chamber volume, the balance between the decrease rate of the Sn component concentration of the cathode chamber plating solution and the increase rate of the acid component concentration of the anode chamber plating solution is adjusted. The dissolution efficiency of tin oxide can be further improved.
When the anode chamber exceeds 30% of the volume of the cathode chamber, the Sn component concentration of the cathode chamber plating solution decreases, and when it is time to replenish the Sn component, the acid component concentration of the anode chamber plating solution is There is a possibility that the dissolution efficiency of tin oxide may be lowered due to insufficient rise. If the volume of the anode chamber is too small, the amount of the plating solution is too small to dissolve the amount of tin oxide necessary for replenishment. Therefore, the anode chamber is set to 10% or more with respect to the volume of the cathode chamber. It is preferable.

  In the present invention, a substrate to be processed and an insoluble anode electrode are brought into contact with a plating solution containing Sn stored in a plating tank, and the substrate is processed by energizing the substrate to be processed and the insoluble anode electrode. A plating apparatus for forming a plating film on a substrate, wherein the plating tank is partitioned by an anion exchange membrane into a cathode chamber in which the substrate to be processed is disposed and an anode chamber in which the insoluble anode electrode is disposed. The anode chamber is set to 30% or less with respect to the volume of the cathode chamber, and supplies tin oxide to the anode chamber plating solution of the anode chamber separately from a part of the anode chamber or the anode chamber. And a dissolution chamber for generating a replenishing plating solution.

  By configuring the plating apparatus in this way, the Sn component can be replenished to the plating solution easily and efficiently.

  According to the present invention, it is possible to easily dissolve tin oxide by simply supplying tin oxide to the plating solution in the anode chamber whose acid component concentration has increased with plating, and to efficiently replenish the plating solution with the Sn component. . Moreover, since the plating solution of the same component is used for the cathode chamber and the anode chamber, handling is easy.

It is a whole lineblock diagram showing the plating apparatus applied to the plating method of a 1st embodiment of the present invention. It is a whole block diagram which shows the plating apparatus applied to the plating method of 2nd Embodiment of this invention.

Hereinafter, embodiments of a plating method and a plating apparatus according to the present invention will be described with reference to the drawings.
FIG. 1 shows a first embodiment of the plating apparatus of the present invention. In this plating apparatus 100, the substrate 2 and the insoluble anode electrode 3 are brought into contact with the plating solution stored in the plating tank 1, and a current is passed between the substrate 2 and the insoluble anode electrode 3 to be processed. A pure Sn or Sn alloy plating film is formed on the substrate 2. In addition, the power supply 11 is connected between the to-be-processed substrate 2 and the insoluble anode electrode 3, and it is the structure which carries out the electroplating by using the to-be-processed substrate 2 as a cathode.

  As the insoluble anode electrode 3, for example, a metal electrode obtained by coating a titanium plate or the like with platinum, iridium oxide, or the like, or an electrode made of carbon or the like is applied. Further, the target substrate 2 is a target metal such as SUS or Cu, or a metal substrate such as Cu provided by a technique such as sputtering, and a target such as a resin substrate or a Si wafer provided with conductivity. Things are provided.

  The plating tank 1 is partitioned by an anion exchange membrane 4 into a cathode chamber 21 in which the substrate 2 is disposed and an anode chamber 31 in which the insoluble anode electrode 3 is disposed. The volume of the anode chamber 31 is set smaller than the volume of the cathode chamber 21, and the volume of the anode chamber 31 is set to 10% or more and 30% or less with respect to the volume of the cathode chamber 21. Further, as the anion exchange membrane 4, for example, “Celemion” manufactured by AGC Engineering, which is excellent in acid resistance, or “Neoceptor” manufactured by Astom Co., Ltd. can be used.

In addition, a melting chamber 33 is provided in which tin oxide (SnO) powder is supplied to the anode chamber plating solution in the anode chamber 31 to generate a replenishment plating solution. The anode chamber 31 and the dissolution chamber 33 are connected by circulation pipes 51 and 52, and the plating solution in the anode chamber 31 and the plating solution in the dissolution chamber 33 can be circulated through the circulation pipes 51 and 52. .
In this case, the plating solution is circulated between the anode chamber 31 and the melting chamber 33, and the anode chamber 31 and the melting chamber 33 function as the anode chamber of the present invention as a whole. Applies to a part of the room.
The dissolution chamber 33 is provided with a supply pipe 53 for supplying the replenishing plating solution to the cathode chamber 21. Further, the supply pipe 53 is provided with a filter (not shown), which can prevent impurities from moving when supplying the replenishing plating solution to the cathode chamber 21.
1 is a supply pipe that supplies the cathode chamber plating solution in the cathode chamber 21 to the adjacent anode chamber 31, and 61 is a valve that opens and closes the flow in the pipe.

A method of performing Sn—Ag alloy plating on the substrate 2 to be processed using the plating apparatus configured as described above will be described.
Examples of the Sn—Ag alloy plating solution (plating solution containing Sn as used in the present invention) include acids such as alkylsulfonic acid such as methanesulfonic acid and ethanesulfonic acid, and plating metal ions (Sn ²⁺ , Ag ⁺ ), Additives such as antioxidants and surfactants, complexing agents and the like are blended. The Sn—Ag alloy plating solution used in this example is composed of, for example, the following composition.
Alkyl sulfonic acid; 100 to 150 g / L
Sn ²⁺ ; 40-90 g / L
Ag ⁺ ; 0.1-3.0 g / L
Note that the same Sn—Ag alloy plating solution as described above is used for the cathode chamber 21 and the anode chamber 31.

Then, when the substrate 2 and the insoluble anode electrode 3 are energized, in the cathode chamber 21 by electrolysis, Sn is applied to the substrate 2 by reduction reaction as represented by the following formulas (1) and (2). -Ag alloy precipitates (plating process). On the other hand, in the anode chamber 31, as represented by the formula (3), oxygen (O ₂ ) is generated on the surface of the insoluble anode electrode 3 by water electrolysis reaction and H ions (H ⁺ ). Concentration increases. Since the cathode chamber 21 and the anode chamber 31 are separated by the anion exchange membrane 4, the movement of cations from the anode chamber 31 to the cathode chamber 21 is limited, and the acid in the anode chamber 31 is accompanied by plating. Increases the component concentration.
In addition, since the volume of the anode chamber 31 is set small, the rate of increase of the acid component concentration is high.
Sn ²⁺ + 2e ⁻ → Sn (1)
Ag ⁺ + e ⁻ → Ag (2)
H ₂ O → 2H ⁺ + 1 / 2O ₂ + 2e ⁻ (3)

As electrolysis proceeds, the Sn component concentration in the cathode chamber 21 decreases, and the acid component concentration of the anode chamber plating solution in the anode chamber 31 increases. The replenishing plating solution is used before the acid component concentration of the anode chamber plating solution increases by 15% or more of the initial concentration and the decrease of the Sn component concentration of the cathode chamber plating solution does not exceed 10% of the initial plating solution. To replenish the Sn component.
If the decrease in the Sn component concentration in the cathode chamber plating solution is less than 5%, the acid component concentration in the anode chamber plating solution is not sufficiently increased, and the dissolution efficiency of tin oxide may decrease. In addition, when the decrease in the Sn component concentration exceeds 10%, the plating property on the substrate to be processed 2 may be affected.

The replenishing plating solution is generated using the anode chamber plating solution in the anode chamber 31. A replenishing plating solution is generated by supplying a tin oxide powder into the dissolution chamber 33 in a state where a part of the anode chamber plating solution having an increased acid component concentration is extracted and circulated between the dissolution chamber 33 ( Supply process). Since the plating solution in the anode chamber 31 and the dissolution chamber 33 contains H ions at a high concentration, just by supplying tin oxide (SnO) as represented by the following formula (4), It can be easily dissolved in the plating solution having a high acid component concentration.
SnO + 2H ⁺ → Sn ²⁺ + H ₂ O (4)

By supplying the replenishing plating solution thus generated to the cathode chamber 21 through the supply pipe 53, and supplying the same amount of cathode chamber plating solution as the replenishing plating solution from the cathode chamber 21 through the supply pipe 54 to the anode chamber 31, The plating solution in the cathode chamber 21, the anode chamber 31, and the dissolution chamber 33 is circulated to uniformize the Sn component concentration and the acid component concentration and return the substrate 2 to be processed to the state before plating (homogenization). Process).
Since the melting chamber 33 is provided separately, the Sn component can be replenished while plating by dissolving SnO in the melting chamber 33. When the melting chamber 33 is not provided, SnO needs to be replenished in the anode chamber 31. In this case, when SnO is replenished while plating, the added SnO is caused by oxygen generated from the surface of the insoluble anode electrode 3. Is not preferred because it tends to oxidize and its solubility is impaired. Therefore, when the melting chamber 33 is not provided separately, it is necessary to supply SnO after stopping the plating.

Next, a second embodiment of the plating apparatus of the present invention will be described.
In the plating apparatus 200 of the second embodiment shown in FIG. 2, the anode chamber 31 and the melting chamber 33 are connected only by a supply pipe 55 that supplies the plating solution in the anode chamber 31 to the melting chamber 33. That is, a melting chamber 33 is provided separately from the anode chamber of the present invention.
When Sn-Ag alloy plating is performed on the substrate 2 to be processed by the plating apparatus 200 configured as described above, the valve 61 of the supply pipe 55 is set in a closed state, and the anode chamber 31 and the melting chamber 33 are separated from each other. There is no movement of the plating solution between them. Also in the second embodiment, the supply of the replenishing plating solution to the cathode chamber 21 is such that the acid component concentration of the anode chamber plating solution increases by 15% or more of the initial concentration, and the Sn component concentration of the cathode chamber plating solution decreases. It is performed before exceeding 10% of the liquid.

First, the entire amount of the anode chamber plating solution in the anode chamber 31 is extracted through the supply pipe 55 and moved to the dissolution chamber 33. By supplying tin oxide powder to the anode chamber plating solution in the dissolution chamber 33, replenishment plating is performed. A liquid is produced (replenishment process). At this time, since the anode chamber plating solution in the dissolution chamber 33 contains H ions at a high concentration, it is easily dissolved in the anode chamber plating solution having a high acid component concentration simply by supplying tin oxide. be able to.
Next, the replenishing plating solution thus generated is supplied to the cathode chamber 21 through the supply pipe 53, and the same amount of cathode chamber plating solution as the replenishing plating solution is supplied from the cathode chamber 21 to the anode chamber 31 through the supply pipe 54. Thus, the plating solution in the cathode chamber 21, the anode chamber 31, and the melting chamber 33 is circulated, and the Sn component concentration and the acid component concentration are made uniform, so that the substrate 2 to be processed can be returned to the state before plating. (Uniformization process).

  As described above, since the tin oxide powder is supplied to the anode chamber plating solution in the anode chamber 31 where the acid component concentration has increased with plating, the high acid component concentration can be obtained simply by supplying tin oxide. It can be easily dissolved in the anode chamber plating solution. Further, the acid is consumed by the dissolution of tin oxide, so that the state of the initial plating solution before plating the substrate 2 to be processed can be restored. Since the same plating solution is used for the cathode chamber 21 and the anode chamber 31, it is not necessary to prepare an acid solution separately from the plating solution, it is easy to handle, and disappears with the plating of the substrate to be processed. It is possible to easily replenish the metal component.

In order to obtain the above effect, in this embodiment, the volume of the anode chamber 31 is set to 10% or more and 30% or less with respect to the volume of the cathode chamber 21. This is because when the anode chamber 31 is less than 10% with respect to the volume of the cathode chamber 21, the dissolution of tin oxide is difficult to occur, and when it exceeds 30%, the effect of increasing the acid component concentration in the anode chamber is reduced. This is because the dissolution efficiency of tin oxide is reduced.
In addition, although description was abbreviate | omitted about the Ag component which comprises Sn-Ag type alloy plating compared with Sn component, when replenishing, what is necessary is just to add an appropriate quantity at the time of melt | dissolution of SnO.

Sn-Ag alloy plating was performed under the conditions shown in Table 1 using the plating apparatus 100 shown in FIG. The volume of the plating solution supplied into the cathode chamber and the anode chamber was set as shown in “Cathode chamber” and “Anode chamber” in Table 1. In Comparative Example 1, a conventional plating tank in which the cathode chamber and the anode chamber are not divided is used. Table 1 shows the total volume of the plating tank including the cathode chamber and the anode chamber. As an anion exchange membrane for partitioning the cathode chamber and the anode chamber, “Neoceptor AMX” manufactured by Astom Co., Ltd. was used.
And as a Sn-Ag alloy plating solution in a plating tank, Sn-Ag alloy plating solution "SULA TS-140" made by Mitsubishi Materials Corporation was used, and the composition (initial plating solution) was as follows. .
Sn ²⁺ ; 50 g / L
Ag ⁺ ; 0.6 g / L
FA (acid); 120 g / L
TS-SLG (Ag complexing agent); 172 g / L
TS-140AD (additive); 40 ml / L

The bath temperature of the plating tank was set to 25 ° C. and an electrolysis current of 2 A, and the Sn component was replenished after plating was performed by energizing with the “electrolysis time” shown in Table 1.
“Post-electrolysis FA”, “post-electrolysis Sn”, and “post-electrolysis Ag” in Table 1 are the results of analysis of the composition in the plating solution in the cathode chamber and the anode chamber after electrolysis, which has changed due to plating. . Further, “Sn decrease amount” is calculated from the ratio of the Sn component concentration of the plating solution after electrolysis to the initial plating solution.

  The replenishment of the Sn component to the plating solution was performed in a state where a part of the anode chamber plating solution in the anode chamber was extracted and circulated between the dissolution chamber. The tin oxide powder was supplied into the melting chamber ("SnO replenishment amount" shown in Table 1 was supplied) to produce a replenishment plating solution. The “SnO replenishment amount” was changed according to the “Sn decrease amount” and set so that tin oxide powder containing an Sn component amount equivalent to the Sn component amount disappeared from the cathode chamber could be supplied. The time taken for dissolution of the tin oxide powder at this time was as shown in “Dissolution time”. The “dissolution time ratio” is a ratio (%) to the dissolution time in each of the examples and comparative examples based on the dissolution time of comparative example 1.

  Next, the generated replenishing plating solution is supplied to the cathode chamber through the supply pipe, and further, the cathode chamber plating solution is supplied to the anode chamber through the supply pipe, so that the plating solution in the cathode chamber, the anode chamber, and the dissolution chamber is supplied. It was circulated.

As shown in Table 1, in each Example and Comparative Example, the amount of Sn component (post-electrolysis Sn) in the cathode chamber decreased and the amount of acid component (post-electrolysis FA) increased due to plating.
It can be seen that Examples 1 to 9 all have a shorter dissolution time of tin oxide than Comparative Example 1 and have improved dissolution efficiency. In particular, in each of Examples 1 to 5, the volume of the anode chamber was set to 30% or less with respect to the volume of the cathode chamber, and the “FA increase amount” (acid component concentration increase amount) of the anode chamber plating solution was the initial concentration. The tin oxide was dissolved before the “Sn reduction amount” exceeded 10% with respect to the initial plating solution, and the dissolution time ratio was 90% compared to that of Comparative Example 1. It can be seen that the dissolution efficiency is greatly improved.
In Examples 6 to 9, since the dissolution of tin oxide is performed in a state where the “FA increase amount” of the anode chamber plating solution is less than 15% of the initial concentration, the dissolution time of tin oxide becomes longer. In comparison with Examples 1 to 5, the dissolution efficiency was lowered. In Examples 6 and 7, since the volume of the anode chamber exceeded 30% with respect to the volume of the cathode chamber, the “FA increase amount” was small.

In addition, this invention is not limited to the said embodiment, A various change can be added in the range which does not deviate from the meaning of this invention.
For example, in addition to the Sn—Ag alloy plating described above, the present invention can be applied to a Sn plating process using an insoluble anode electrode, and the present invention can also be applied to pure Sn plating or Sn—Cu alloy plating. .

DESCRIPTION OF SYMBOLS 1 Plating tank 2 Substrate 3 Insoluble anode electrode 4 Anion exchange membrane 11 Power supply 21 Cathode chamber 31 Anode chamber 33 Dissolution chamber 51 Circulation piping 53, 54, 55 Supply piping 61 Valve 100, 200 Plating apparatus

Claims (4)

  A plating tank for storing a plating solution containing Sn is partitioned into a cathode chamber in which a substrate to be processed is disposed and an anode chamber in which an insoluble anode electrode is disposed by an anion exchange membrane, and plating is performed on the substrate to be processed. A plating step to be applied, a replenishment step of generating a replenishment plating solution by supplying tin oxide to the anode chamber plating solution of the anode chamber in which the acid component concentration has increased along with the plating step, and the replenishment plating solution and the cathode chamber And a uniformizing step of making the plating solution in the plating tank uniform by circulating the cathode chamber plating solution of each other.   The plating method according to claim 1, wherein the replenishing step is performed when the acid component concentration of the anode chamber plating solution increases by 15% or more of the initial concentration.   The plating method according to claim 1 or 2, wherein the plating tank is partitioned by the anion exchange membrane so that the anode chamber is 30% or less with respect to the volume of the cathode chamber.   A substrate to be processed and an insoluble anode electrode are brought into contact with a plating solution containing Sn stored in a plating tank, and a current is passed between the substrate to be processed and the insoluble anode electrode to form a plating film on the substrate to be processed. The plating tank is divided into a cathode chamber in which the substrate to be processed is disposed by an anion exchange membrane and an anode chamber in which the insoluble anode electrode is disposed, and the anode The chamber is set to 30% or less with respect to the volume of the cathode chamber, and a replenishing plating solution by supplying tin oxide to the anode chamber plating solution of the anode chamber separately from a part of the anode chamber or the anode chamber A plating apparatus characterized in that a melting chamber is provided for generating a gas.

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