Electrolytic treatment method and electrolytic treatment apparatus

Abstract

To efficiently perform a prescribed electrolytic treatment to an object to be treated using ions to be treated in a treatment solution.SOLUTION: A direct electrode 20 and a counter electrode 22 are arranged in a plating solution M, and an indirect electrode 21 is also arranged in the plating solution M for forming an electric field. The electric field is formed in the plating solution M by applying a voltage to the indirect electrode 21, and thus copper ions C are moved to the counter electrode 22 side in the plating solution M. The copper ions C that are moved to the counter electrode 22 side are reduced by connecting the direct electrode 20 to the indirect electrode 21. Part of the direct electrode 20 is exposed to the plating solution M, and the other part of the direct electrode 20 is covered with an insulator film 23. The direct electrode 20 is connected to the counter electrode 22 through the insulator film 23. The direct electrode 20 is grounded through the insulator film 23.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an electrolytic treatment method for performing a predetermined treatment using treatment ions contained in a treatment liquid, and an electrolytic treatment apparatus for performing the electrolytic treatment method.

Background Art

[0002] The electrolytic process (electrolytic treatment) is a technique used in various treatments such as plating treatment and etching treatment.

[0003] In order to perform the above-described plating treatment, for example, the plating treatment described in Patent Document 1 has been proposed. In this plating treatment, a direct electrode and an indirect electrode are doubly arranged directly in a plating solution, and a counter electrode (workpiece) is arranged so as to sandwich the plating solution between these direct electrode and indirect electrode. Then, a voltage is applied to the indirect electrode to form an electric field in the plating solution, so that metal ions in the plating solution are moved to the counter electrode side, and further, a current is passed between the direct electrode and the counter electrode to reduce the metal ions that have moved to the counter electrode side.

[0004] In the plating treatment described in Patent Document 1, although it is attempted to perform the movement of metal ions (hereinafter sometimes referred to as the "movement step") and the reduction of metal ions (hereinafter sometimes referred to as the "reduction step") separately, during the movement step when the metal ions are moved and accumulated to the counter electrode side, the reduction of metal ions may be performed on the counter electrode side. That is, the reduction step may proceed during the movement step.

[0005] During the transfer process, applying a voltage to the indirect electrode creates an electric field in the plating solution, which in turn generates an electric field between the direct electrode and the counter electrode. Since both the direct electrode and the counter electrode are conductors, charge exchange between ions may occur between them. The amount of this charge exchange corresponds to the potential difference between the direct electrode and the counter electrode. On the other hand, the potential of the direct electrode is determined by the electric field distribution formed by the indirect electrode and the counter electrode, and this electric field is determined by the electric field line distribution between the indirect electrode and the counter electrode. Therefore, the closer the direct electrode is to the indirect electrode along the electric field lines, the higher the potential of the direct electrode becomes. In the plating process described in Patent Document 1, the direct electrode is positioned close to the indirect electrode, so the potential of the direct electrode becomes high. As a result, charge exchange of metal ions proceeds on the counter electrode side during the transfer process, and the metal ions are reduced.

[0006] For example, a plating process described in Patent Document 2 has been proposed. In this plating process, a direct electrode and a counter electrode (workpiece) are placed in close proximity in the plating solution, and an indirect electrode is placed at a distance from these direct and counter electrodes. A first switch is provided to switch between connecting the indirect electrode to the power supply and connecting the indirect electrode to the direct electrode, as well as a second switch to switch between connecting the direct electrode and the indirect electrode. Subsequently, the indirect electrode is connected to the power supply by the first switch and a voltage is applied, and the direct electrode and the counter electrode are connected by the second switch to move metal ions in the plating solution to the counter electrode side. Further, the connection with the indirect electrode is switched from the power supply to the direct electrode by the first switch, and the connection with the direct electrode is switched from the counter electrode to the indirect electrode by the second switch, connecting the direct electrode and the indirect electrode, and reducing the metal ions that have moved to the counter electrode side.

[0007] In the plating process described in Patent Document 2, the direct electrode and the counter electrode are connected during the transfer process, resulting in the direct electrode and the counter electrode being at approximately the same potential. Therefore, charge exchange (reduction) between the direct electrode and the counter electrode is suppressed. [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] Japanese Patent Publication No. 2016-113652 [Patent Document 2] Japanese Patent Publication No. 2018-3133 [Overview of the project] [Problems that the invention aims to solve]

[0009] However, in the plating process described in Patent Document 2, the direct electrode and the counter electrode are connected during the transfer process, which reduces the plating efficiency. For example, if the surface area of ​​the direct electrode and the surface area of ​​the counter electrode are equal, the charge amounts of the direct electrode and the counter electrode become equivalent, and furthermore, the charge amount of the indirect electrode becomes the sum of the charge amounts of the direct electrode and the counter electrode. That is, negative charges of charge amount Q are accumulated on the direct electrode and the counter electrode, and positive charges of charge amount 2Q are accumulated on the indirect electrode. Then, in the reduction process, positive charges of charge amount 2Q are transferred from the indirect electrode to the direct electrode, and these transferred positive charges of charge amount Q are neutralized by the negative charges of charge amount Q on the direct electrode, leaving positive charges of charge amount Q on the direct electrode. Furthermore, in the reduction process, the charge exchange of positive charges of charge amount Q remaining on the direct electrode is completed, and no charge remains on the direct electrode.

[0010] Because charge is consumed through neutralization, the charge accumulated during the transfer process cannot be effectively utilized. Therefore, there is room for improvement in terms of efficiency in conventional plating processes.

[0011] This invention has been made in view of the above circumstances, and aims to efficiently perform a predetermined electrolytic treatment on a workpiece using ions to be treated in a treatment solution. [Means for solving the problem]

[0012] The present invention, which solves the above problems, is an electrolytic treatment method that performs a predetermined treatment using ions to be treated contained in a treatment liquid, comprising: an arrangement step of arranging a direct electrode and a counter electrode in the treatment liquid and arranging an indirect electrode that forms an electric field in the treatment liquid; and an ion to be treated movement step of applying a voltage to the indirect electrode to form an electric field in the treatment liquid and moving the ions to be treated in the treatment liquid toward the counter electrode. before The process includes a treatment ion treatment step of oxidizing or reducing the ions to be treated that have moved to the opposing electrode side, wherein a portion of the direct electrode is exposed to the treatment solution, and the other portion of the direct electrode is covered with an insulating film. A portion of the direct electrode and the other portion constitute a series connection of an insulating film capacitance and an electric double layer capacitance. The direct electrode Other parts It is connected to the counter electrode via the insulating film, and the direct electrode Other parts It is grounded via the insulating film. In the ion transfer step, the indirect electrode is connected to the positive or negative side of the power supply, the other part of the direct electrode and the counter electrode are connected to the negative or positive side of the power supply, a part of the direct electrode is not connected to the indirect electrode, the counter electrode and the power supply, and in the ion processing step, the connection between the indirect electrode and the power supply is switched to a connection between the indirect electrode and a part of the direct electrode. It is characterized by the following.

[0013] According to the present invention, since the direct electrode is connected to the counter electrode via an insulating film, the direct electrode and the counter electrode are at approximately the same potential during the ion transfer process. Therefore, charge exchange (oxidation-reduction) between the direct electrode and the counter electrode exposed to the processing solution can be suppressed.

[0014] Furthermore, the direct electrode is partially exposed to the processing solution, while the other part is covered with an insulating film, forming a series connection of the insulating film capacitance and the electrical double layer capacitance. This series structure of the direct electrode significantly reduces its capacitance. In this case, when the direct electrode and indirect electrode are connected during the ion treatment process, charge moves from the indirect electrode to the direct electrode. However, because the capacitance of the direct electrode is small, less charge is wasted on the direct electrode. In other words, the wasted consumption of charge accumulated on the indirect electrode is suppressed, and the amount of array charge and reaction-deposited charge on the counter electrode can be made almost equal. Therefore, the charge accumulated on the indirect electrode can be effectively utilized, and electrolytic treatment can be performed efficiently.

[0015] Furthermore, during the ion transfer process, a sufficient number of ions to be treated accumulate on the counter electrode side, and with the ions uniformly arranged on the surface of the counter electrode, charge exchange of the ions to be treated takes place during the ion treatment process, causing the ions to be oxidized or reduced. Therefore, the electrolytic treatment can be performed uniformly.

[0016] In the arrangement step, a first switch is provided for switching between the connection of the indirect electrode and the power supply, and between the indirect electrode and the direct electrode, and a second switch is provided for switching between the connection and disconnection of the direct electrode and the indirect electrode. In the ion transfer step, the indirect electrode is connected to the power supply by the first switch and a voltage is applied to the indirect electrode, and the connection between the direct electrode and the indirect electrode is disconnected by the second switch to move the ions to be treated in the processing liquid to the counter electrode side. In the ion processing step, the direct electrode and the indirect electrode are connected by the first switch and the second switch, and the ions to be treated that have moved to the counter electrode side may be oxidized or reduced.

[0017] The processing solution is a plating solution, and in the ion treatment step, the ions to be treated are reduced to form a plating on the counter electrode side. The electrolytic treatment method may also include a plating adhesion step after the ion treatment step, in which a voltage is applied to the indirect electrode to form a reverse electric field in the processing solution that is opposite to the electric field in the ion transfer step, thereby causing the plating to adhere closely to the counter electrode side.

[0018] The cycle including the ion transfer step and the ion treatment step may be repeated, and the plating adhesion step may be performed after each cycle. Alternatively, the cycle including the ion transfer step and the ion treatment step may be repeated, and the plating adhesion step may be performed after the last cycle.

[0019] In the arrangement step, a voltage may be applied to the indirect electrode to form an electric field in the processing liquid.

[0020] From another perspective, the present invention is an electrolytic processing apparatus that performs a predetermined process using treatment ions contained in a treatment liquid, and includes a direct electrode disposed in the treatment liquid, a counter electrode disposed in the treatment liquid, and an indirect electrode that forms an electric field in the treatment liquid , power supply and The indirect electrode forms an electric field in the treatment liquid when a voltage is applied, moves the treatment ions in the treatment liquid to the counter electrode side, and the direct electrode and the indirect electrode ,before oxidize or reduce the treatment ions that have moved to the counter electrode side, a part of the direct electrode is exposed to the treatment liquid, and the other part of the direct electrode is covered with an insulating film, A portion of the direct electrode and the other portion constitute a series connection of an insulating film capacitance and an electric double layer capacitance. the direct electrode Other parts is connected to the counter electrode through the insulating film, and the direct electrode Other parts is grounded through the insulating film When moving the ions to be treated in the processing solution toward the counter electrode, the indirect electrode is connected to the positive or negative side of the power supply, the other part of the direct electrode and the counter electrode are connected to the negative or positive side of the power supply, a part of the direct electrode is not connected to the indirect electrode, the counter electrode and the power supply, and when oxidizing or reducing the ions to be treated that have moved toward the counter electrode, the connection between the indirect electrode and the power supply is switched to a connection between the indirect electrode and a part of the direct electrode. which is characterized by this.

[0021] The electrolytic processing apparatus has a first switch that switches the connection between the indirect electrode and the power source and the connection between the indirect electrode and the direct electrode, and a second switch that switches the connection and disconnection between the direct electrode and the indirect electrode. When moving the treatment ions in the treatment liquid to the counter electrode side, the first switch connects the indirect electrode and the power source to apply a voltage to the indirect electrode, and the second switch disconnects the connection between the direct electrode and the indirect electrode. When oxidizing or reducing the treatment ions that have moved to the counter electrode side, the first switch and the second switch may connect the direct electrode and the indirect electrode.

[0022] The treatment liquid is a plating solution, the treatment ions are reduced to form plating on the counter electrode side, and the indirect electrode forms a reverse electric field in the treatment liquid in the opposite direction to the electric field when moving the treatment ions in the treatment liquid to the counter electrode side when a voltage is applied, and the plating may be adhered to the counter electrode side.

Effects of the Invention

[0023] According to the present invention, a predetermined electrolytic treatment can be efficiently performed on the object to be treated using the ions to be treated in the treatment solution. [Brief explanation of the drawing]

[0024] [Figure 1] This is a longitudinal cross-sectional view showing the general configuration of the plating apparatus. [Figure 2] This is an explanatory diagram showing the connection between the indirect electrode and the DC power supply, and the disconnection between the direct electrode and the indirect electrode, during charging. [Figure 3] This is an explanatory diagram showing how the direct and indirect electrodes are connected during discharge. [Figure 4] This is an explanatory diagram showing the process of forming an inverse electrostatic field in the plating solution after copper plating has been formed. [Modes for carrying out the invention]

[0025] Embodiments of the present invention will be described below with reference to the drawings. In this specification and the drawings, components having substantially the same functional configuration are denoted by the same reference numerals, and redundant explanations are omitted. In this embodiment, the case in which plating is performed as the electrolytic treatment according to the present invention will be described.

[0026] <Configuration of Plating Equipment> First, the configuration of the plating apparatus as an electrolytic apparatus according to this embodiment will be described. Figure 1 is a longitudinal cross-sectional view showing a schematic of the plating apparatus 1. Note that in the drawings used in the following description, the dimensions of each component do not necessarily correspond to the actual dimensions in order to prioritize ease of understanding of the technology.

[0027] The plating apparatus 1 has a plating tank 10 that stores a plating solution M as a processing solution. As the plating solution M, for example, a solution in which copper sulfate is dissolved is used. That is, the plating solution M contains copper ions as the ions to be treated.

[0028] Inside the plating tank 10, a direct electrode 20, an indirect electrode 21, and a counter electrode 22 are provided, each immersed in the plating solution M. The direct electrode 20 is positioned close to the counter electrode 22. The indirect electrode 21 is positioned at a distance from both the direct electrode 20 and the counter electrode 22.

[0029] A portion of the direct electrode 20 is exposed to the plating solution M, while the other portion is covered with an insulating film 23. In the following description, the portion of the direct electrode 20 exposed to the plating solution M is sometimes referred to as the exposed portion 20a, and the portion of the direct electrode 20 covered with the insulating film 23 is sometimes referred to as the insulated portion 20b. The surface of the exposed portion 20a and the back surface of the insulated portion 20b are in contact via the insulating film 23, and the exposed portion 20a and the insulated portion 20b have an integrated structure. In other words, the direct electrode 20 constitutes a series connection of the insulating film capacitance and the electrical double layer capacitance.

[0030] The direct electrode 20 (insulating portion 20b) is connected to the counter electrode 22 via the insulating film 23. In other words, the direct electrode 20 is connected to the counter electrode 22 via a capacitor. Furthermore, the direct electrode 20 (insulating portion 20b) is grounded via the insulating film 23.

[0031] The indirect electrode 21 is covered with an insulating film 24. The counter electrode 22 is the workpiece to be plated.

[0032] A DC power supply 30 is connected to the indirect electrode 21 and the counter electrode 22. The indirect electrode 21 is connected to the positive side of the DC power supply 30. The counter electrode 22 is connected to the negative side of the DC power supply 30.

[0033] The indirect electrode 21 is provided with a first switch 31. The first switch 31 switches between the connection between the indirect electrode 21 and the DC power supply 30, and the connection between the indirect electrode 21 and the direct electrode 20. The switching of the first switch 31 is controlled by the control unit 40.

[0034] The direct electrode 20 is provided with a second switch 32. The second switch 32 switches the connection between the exposed portion 20a of the direct electrode 20 and the indirect electrode 21. The switching of the second switch 32 is controlled by the control unit 40.

[0035] The control unit 40 is, for example, a computer and has a program storage unit (not shown). The program storage unit stores a program that controls the plating process in the plating apparatus 1. The program may have been recorded on a storage medium readable by the computer and installed from that storage medium to the control unit 40.

[0036] <Plating process method> Next, we will describe a plating process using the plating apparatus 1 configured as described above.

[0037] First, as shown in Figure 2, the indirect electrode 21 is connected to the DC power supply 30 (counter electrode 22) by the first switch 31, and the connection between the direct electrode 20 and the indirect electrode 21 is disconnected by the second switch 32. Then, a DC voltage is applied with the indirect electrode 21 as the anode and the counter electrode 22 as the cathode to form an electric field (electrostatic field) in the plating solution M. As a result, positive charge accumulates on the indirect electrode 21, and negatively charged particles, anions A (sulfate ions), gather on the indirect electrode 21 side. On the other hand, negative charge accumulates on the counter electrode 22 and the direct electrode 20, respectively, and positively charged particles, copper ions C, move to the counter electrode 22 side. In the following explanation, this state in which charge accumulates on the electrodes may be referred to as "charging".

[0038] During charging, the direct electrode 20 (insulating portion 20b) and the counter electrode 22 are connected via the insulating film 23, so the direct electrode 20 and the counter electrode 22 are at approximately the same potential. Therefore, charge exchange (oxidation-reduction) between the exposed portion 20a of the direct electrode 20 and the counter electrode 22 can be suppressed.

[0039] Then, the connection of the indirect electrode 21 to the DC power supply 30 by the first switch 31, and the disconnection of the direct electrode 20 and the indirect electrode 21 by the second switch 32 are performed until sufficient charge is accumulated in the indirect electrode 21 and the counter electrode 22, that is, until fully charged. As described above, charge exchange at the counter electrode 22 is suppressed during charging, so copper ions C are uniformly arranged on the surface of the counter electrode 22. Furthermore, there is a concern that increasing the electric field when applying voltage between the indirect electrode 21 and the counter electrode 22 will cause electrolysis of water to proceed, but in this embodiment, charge exchange of copper ions C does not occur at the surface of the counter electrode 22, and electrolysis of water is also suppressed, so the electric field can be increased. This high electric field can speed up the movement of copper ions C. Furthermore, by arbitrarily controlling this electric field, the copper ions C arranged on the surface of the counter electrode 22 can also be arbitrarily controlled.

[0040] Subsequently, as shown in Figure 3, the direct electrode 20 and the indirect electrode 21 are connected by the first switch 31 and the second switch 32. This causes the positive charge accumulated on the indirect electrode 21 to move to the direct electrode 20, exchanging the charge of the anion A gathered on the indirect electrode 21 side, and oxidizing the anion A. Consequently, the charge of the copper ions C arranged on the surface of the counter electrode 22 is also exchanged, reducing the copper ions C. Finally, copper plating 50 is deposited on the surface of the counter electrode 22. In the following explanation, this state of charge transfer between electrodes may be referred to as "discharge."

[0041] Here, the capacitance of the direct electrode 20 is significantly reduced due to its structure, which consists of a series connection of the insulating film capacitance and the electrical double layer capacitance. Here, capacitance C is expressed as C = εS / d (d: thickness of the insulating film), and while the d of the electrical double layer at the liquid interface is 1 nm or less, the d of the insulating film 23 is 1 μm or more. As a result, the capacitance of the electrical double layer is significantly larger than that of the insulating film capacitance. Therefore, the capacitance of the direct electrode 20 is significantly smaller than that of the counter electrode 22. Because the capacitance of the direct electrode 20 is small in this way, less charge is wasted in the direct electrode 20 during discharge. In other words, it is possible to suppress the wasted consumption of charge accumulated in the indirect electrode 21 and to make the amount of array charge and reaction-deposited charge in the counter electrode 22 almost equal.

[0042] As a result, sufficient copper ions C accumulate on the surface of the counter electrode 22 and are reduced in a uniformly arranged state, allowing for the uniform deposition of copper plating 50 on the surface of the counter electrode 22. Consequently, the crystal density in the copper plating 50 increases, enabling the formation of high-quality copper plating 50.

[0043] Subsequently, the copper plating 50 grows to a predetermined thickness through repeated movement and accumulation of copper ions C during charging and reduction of copper ions C during discharging. In this way, the series of plating processes in the plating apparatus 1 is completed.

[0044] According to the above embodiment, since the direct electrode 20 (insulating portion 20b) is connected to the counter electrode 22 via the insulating film 23, when copper ions C are moved during charging, the direct electrode 20 and the counter electrode 22 are at approximately the same potential. Therefore, charge exchange (oxidation-reduction) between the exposed portion 20a of the direct electrode 20 and the counter electrode 22 can be suppressed. As a result, during charging, the copper ions C are uniformly arranged on the surface of the counter electrode 22 and then reduced. Therefore, the plating process can be performed uniformly, and the film thickness of the copper plating 50 can be made uniform. Moreover, since the copper ions C are uniformly arranged, the crystals in the copper plating 50 can be densely arranged. Therefore, the quality of the copper plating 50 after the plating process can be improved.

[0045] Furthermore, because the direct electrode 20 has a structure in which the insulating film capacitance and the electric double layer capacitance are connected in series, the capacitance is significantly reduced. As a result, less charge is wasted on the direct electrode 20 during discharge, and the wasteful consumption of charge accumulated on the indirect electrode 21 is suppressed, making it possible to make the amount of array charge and reaction-deposited charge on the counter electrode 22 almost equal. Therefore, the voltage (energy) applied from the DC power supply 30 during charging can be effectively utilized, and the charge accumulated on the indirect electrode 21 can also be effectively utilized, allowing for efficient plating.

[0046] <Improved plating adhesion> In the embodiments described above, it is important to ensure close contact between the counter electrode 22 and the copper plating 50. In this regard, for example, if the counter electrode 22 and the copper plating 50 are made of different types of metals, it may be difficult for the copper plating 50 to adhere to the counter electrode 22. Similarly, if the counter electrode 22 has fine grooves or fine pores with a high aspect ratio, it may also be difficult for the copper plating 50 to adhere to the counter electrode 22.

[0047] The reason why adhesion of the plating to the substrate can be a problem when plating dissimilar metals or filling micro-grooves and micro-pores with plating is that when metal ions in the plating solution are reduced and adsorbed onto the surface of the substrate and diffuse, these metal ions move unstably before being incorporated into the plating crystal. Here, metal atoms generally move in the direction of electron flow. The inventors of this invention have conceived of utilizing this characteristic of metal atoms to create an electric field in the opposite direction to the electric field during charging (hereinafter sometimes referred to as a "positive electrostatic field") in the plating solution, thereby causing the unstable metal atoms to adhere to the substrate.

[0048] The following explanation will use the plating apparatus 1 of the above embodiment. First, as shown in Figure 2, during charging, a DC voltage is applied with the indirect electrode 21 as the anode and the counter electrode 22 as the cathode to form a positive electrostatic field in the plating solution M. Then, copper ions C are moved to the counter electrode 22 side. Next, as shown in Figure 3, during discharge, the direct electrode 20 and the indirect electrode 21 are connected. Then, copper ions C are reduced on the surface of the counter electrode 22, and copper plating 50 is deposited.

[0049] Next, as shown in Figure 4, the DC power supply 30 is positioned with its positive and negative terminals reversed. That is, the indirect electrode 21 is connected to the negative terminal side of the DC power supply 30, and the counter electrode 22 is connected to the positive terminal side of the DC power supply 30. The indirect electrode 21 is also grounded via the insulating film 24.

[0050] Next, the indirect electrode 21 is connected to the DC power supply 30 (counter electrode 22) by the first switch 31, and the connection between the direct electrode 20 and the indirect electrode 21 is disconnected by the second switch 32. Then, a DC voltage is applied with the indirect electrode 21 as the cathode and the counter electrode 22 as the anode to form a reverse electrostatic field in the plating solution M. This reverse electrostatic field is an electrostatic field in the opposite direction to the positive electrostatic field during charging. Due to the reverse electrostatic field, electrons from copper atoms in the copper plating 50 are polarized and moved toward the counter electrode 22. As a result, copper atoms can be brought into close contact with the counter electrode 22, improving the adhesion of the copper plating 50 to the counter electrode 22.

[0051] Furthermore, since the electric field formed in the plating solution M is an electrostatic field, even if copper atoms in the copper plating 50 are polarized and move towards the plating solution M side, and anions A move to the surface side of the copper plating 50, these copper atoms will not be oxidized.

[0052] In this case, it is conceivable to directly form an electric field in the plating solution M in order to improve the adhesion of the copper plating 50 to the counter electrode 22. However, in this case, there is a risk that the copper plating 50 may be abraded by the direct electric field. In this respect, according to this embodiment, since an electrostatic field is formed in the plating solution M, it is possible to improve the adhesion of the copper plating 50 while preventing the copper plating 50 from being abraded.

[0053] As described above, in the plating process, a cycle including the movement and accumulation of copper ions C during charging and the reduction of copper ions C during discharging is repeatedly performed, and the copper plating 50 grows to a predetermined film thickness. In this embodiment, the adhesion treatment of the copper plating 50 by the reverse electrostatic field may be performed after each cycle. That is, the movement and accumulation of copper ions C during charging, the reduction of copper ions C during discharging, and the adhesion treatment of the copper plating 50 by the reverse electrostatic field may be repeated in this order. Alternatively, the adhesion treatment of the copper plating 50 by the reverse electrostatic field may be performed after the last cycle. That is, after performing multiple cycles to grow the copper plating 50 to a desired film thickness, the adhesion treatment of the copper plating 50 by the reverse electrostatic field may be performed.

[0054] <Measures against peeling and displacement plating on the opposing electrode side> In the embodiments described above, a predetermined undercoat may be formed on the surface of the counter electrode 22 before the copper plating 50 is formed on the counter electrode 22. For example, when forming wiring made of copper plating 50 in a semiconductor device, a barrier film (undercoat) made of, for example, cobalt plating is formed on the surface of the semiconductor substrate (counter electrode 22). If the ionization tendency of the metal in this undercoat is lower than the ionization tendency of the copper in the plating solution M, electroless displacement plating may be performed and the undercoat may peel off.

[0055] On the other hand, applying an appropriate voltage is necessary to prevent this displacement plating, but this voltage can cause electroplating to proceed, resulting in uneven electroplating. In other words, in the plating apparatus 1 described above, if electroplating is performed when, for example, the counter electrode 22 is placed in the plating solution M, the copper ions C in the plating solution M accumulated on the counter electrode 22 are unevenly distributed, or when the electric field is unstable, the plated metal will be deposited unevenly, resulting in uneven plating. Therefore, when placing the counter electrode 22 in the plating solution M, it is necessary to prevent electroless displacement plating while also preventing electroplating from progressing.

[0056] Therefore, in the plating apparatus 1, when the counter electrode 22 is placed in the plating solution M, the indirect electrode 21 and the DC power supply 30 are connected by the first switch 31 as shown in Figure 2, and the connection between the direct electrode 20 and the indirect electrode 21 is disconnected by the second switch 32. Then, a DC voltage is applied with the indirect electrode 21 as the anode and the counter electrode 22 as the cathode to form an electric field (electrostatic field) in the plating solution M. As a result, even if a base film is formed on the surface of the counter electrode 22, for example, electroless displacement plating can be prevented and peeling of the base film can be suppressed, and electrolytic plating by the plating solution M cannot proceed. As a result, the plating process can be performed uniformly.

[0057] <Other Embodiments> In the plating apparatus 1 of the above embodiments, the components are not limited to the examples above. Each component can have any configuration as long as it can perform its function. For example, the indirect electrode 21 only needs to be able to form an electric field in the plating solution M and may be provided outside the plating tank 10.

[0058] <Other Embodiments> In the embodiments described above, a case in which plating is performed as an electrolytic treatment was explained, but the present invention can be applied to various electrolytic treatments such as etching and cleaning.

[0059] Furthermore, although the above embodiments described the case in which copper ions C are reduced on the counter electrode 22 side, the present invention can also be applied to the case in which the ions to be treated are oxidized on the counter electrode 22 side.

[0060] In such cases, the ions to be treated are anions, and the same electrolytic treatment can be performed by reversing the anode and cathode in the above embodiment. That is, a voltage is applied between the indirect electrode and the counter electrode to form an electric field, causing the ions to be treated to move towards the counter electrode. Then, the direct electrode and the indirect electrode are connected. As a result, the charge of the ions to be treated that have moved towards the counter electrode is exchanged, and the ions to be treated are oxidized.

[0061] In this embodiment as well, although there is a difference between oxidation and reduction of the ions to be treated, the same effects as in the above embodiment can be enjoyed.

[0062] Although embodiments of the present invention have been described above, the present invention is not limited to these examples. It will be obvious to those skilled in the art that various modifications or alterations can be conceived within the scope of the technical idea described in the claims, and these will naturally also fall within the technical scope of the present invention. [Explanation of Symbols]

[0063] 1 Plating Apparatus 10 Plating tanks 20 direct electrode 20a Exposed part 20b Insulation 21 Indirect electrode 22 Counter electrode 23 Insulating film 24 Insulating film 30 DC power supply 31. The first switch 32. Second switch 40 Control Unit 50 Copper plating A anion C copper ions M Plating Solution

Claims

1. An electrolytic treatment method that performs a predetermined treatment using ions to be treated contained in a treatment solution, The arrangement step involves placing a direct electrode and a counter electrode in the processing liquid, and also placing an indirect electrode in the processing liquid to form an electric field. A process of transferring treated ions, wherein a voltage is applied to the indirect electrode to form an electric field in the processing liquid, and the ions to be treated in the processing liquid are moved toward the counter electrode, The process includes a treatment ion treatment step of oxidizing or reducing the ions to be treated that have moved to the counter electrode side, A portion of the direct electrode is exposed to the processing solution, and the other portion of the direct electrode is covered with an insulating film. A portion of the direct electrode and the other portion constitute a series connection of an insulating film capacitance and an electric double layer capacitance. The other part of the direct electrode is connected to the counter electrode via the insulating film. The other part of the direct electrode is grounded via the insulating film. In the ion transfer process described above, the indirect electrode is connected to the positive or negative side of the power supply, the other part of the direct electrode and the counter electrode are connected to the negative or positive side of the power supply, and a part of the direct electrode is not connected to the indirect electrode, the counter electrode and the power supply. An electrolytic treatment method characterized in that, in the ion treatment step described above, the connection between the indirect electrode and the power supply is switched to a connection between the indirect electrode and a part of the direct electrode.

2. In the arrangement step, a first switch is provided to switch between connecting the indirect electrode to the power supply and connecting the indirect electrode to the direct electrode, and a second switch is provided to switch between connecting and disconnecting the direct electrode to the indirect electrode. In the ion transfer step described above, the indirect electrode and the power supply are connected by the first switch to apply a voltage to the indirect electrode, and the connection between the direct electrode and the indirect electrode is disconnected by the second switch to move the ions to be treated in the processing liquid to the opposing electrode side. The electrolytic treatment method according to claim 1, characterized in that, in the ion treatment step, the direct electrode and the indirect electrode are connected by the first switch and the second switch, and the ions to be treated that have moved to the opposing electrode side are oxidized or reduced.

3. The aforementioned processing solution is a plating solution, In the ion treatment step described above, the ions to be treated are reduced to form a plating on the counter electrode side. The electrolytic treatment method according to claim 1 or 2, characterized in that, after the ion treatment step, a voltage is applied to the indirect electrode to form a reverse electric field in the treatment solution opposite to the electric field in the ion transfer step, and the plating is brought into close contact with the counter electrode side.

4. The cycle including the ion transfer step and the ion treatment step is repeated, The electrolytic treatment method according to claim 3, characterized in that the plating adhesion step is performed for each cycle.

5. The cycle including the ion transfer step and the ion treatment step is repeated, The electrolytic treatment method according to claim 3, characterized in that the plating adhesion step is performed after the last cycle.

6. The electrolytic treatment method according to any one of claims 1 to 5, characterized in that, in the arrangement step, a voltage is applied to the indirect electrode to form an electric field in the treatment liquid.

7. An electrolytic apparatus that performs a predetermined process using ions to be treated contained in a processing solution, A direct electrode placed in the processing liquid, A counter electrode placed in the processing liquid, An indirect electrode that forms an electric field in the processing liquid, It has a power supply, The indirect electrode, when a voltage is applied, forms an electric field in the processing liquid, moving the ions to be processed in the processing liquid toward the counter electrode. The direct electrode and the indirect electrode oxidize or reduce the ions to be treated that have moved toward the opposing electrode side. A portion of the direct electrode is exposed to the processing solution, and the other portion of the direct electrode is covered with an insulating film. A portion of the direct electrode and the other portion constitute a series connection of an insulating film capacitance and an electric double layer capacitance. The other part of the direct electrode is connected to the counter electrode via the insulating film. The other part of the direct electrode is grounded via the insulating film. When moving the ions to be treated in the processing solution toward the counter electrode, the indirect electrode is connected to the positive or negative side of the power supply, the other part of the direct electrode and the counter electrode are connected to the negative or positive side of the power supply, and a part of the direct electrode is not connected to the indirect electrode, the counter electrode and the power supply. An electrolytic apparatus characterized in that, when oxidizing or reducing the ions to be treated that have moved to the counter electrode side, the connection between the indirect electrode and the power supply is switched to a connection between the indirect electrode and a part of the direct electrode.

8. A first switch for switching between the connection of the indirect electrode to the power supply and the connection of the indirect electrode to the direct electrode, It includes a second switch for switching between connecting and disconnecting the direct electrode and the indirect electrode, When moving the ions to be treated in the processing solution toward the opposing electrode, the first switch connects the indirect electrode to the power supply and applies a voltage to the indirect electrode, and the second switch disconnects the connection between the direct electrode and the indirect electrode. The electrolytic apparatus according to claim 7, characterized in that when oxidizing or reducing the ions to be treated that have moved to the counter electrode side, the first switch and the second switch connect the direct electrode and the indirect electrode.

9. The aforementioned processing solution is a plating solution, The ions to be treated are reduced to form a plating on the opposing electrode side. The electrolytic apparatus according to claim 7 or 8, characterized in that, when a voltage is applied, the indirect electrode forms a reverse electric field in the processing solution that is in the opposite direction to the electric field that moves the ions to be processed in the processing solution toward the counter electrode, thereby causing the plating to adhere closely to the counter electrode.

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