Plating device and plating method

Abstract

The purpose of the present invention is to supply metal ions while keeping the composition of a plating liquid constant during plating.　This plating devise for plating a substrate includes: a plating tank; a cation exchange film for partitioning the inside of the plating tank into an anode chamber for holding an anode liquid and a cathode chamber for holding a cathode liquid; an anode arranged in the anode chamber; a replenishment device for replenishing the cathode liquid with the same metal as the metal deposited on the substrate or a metal compound containing the metal; and a control device for controlling the replenishment device and replenishing, from the replenishment device to the cathode liquid, the metal of a replenishment amount which is obtained by subtracting a transmission amount of the metal ion of the metal transmitted from the anode chamber to the cathode chamber through the cation exchange film from the plating deposition amount of the metal on the substrate, or the metal compound containing the metal of the replenishment amount.

Description

Plating apparatus and plating method

[0001] The present invention relates to a plating apparatus and a plating method.

[0002] A plating apparatus for plating a substrate (e.g., a semiconductor wafer) includes an anode chamber in which an anode is placed and a cathode chamber in which a substrate serving as a cathode is placed. In such plating apparatuses, a solution having the same composition as the plating solution (cathode solution) is generally introduced into the anode chamber. When plating using an insoluble anode, a metal (e.g., Cu) is deposited at the cathode (substrate) in an amount corresponding to the amount of electrolysis, consuming Cu ions in the plating solution. Meanwhile, an acid is generated at the anode. Therefore, as described in Japanese Patent No. 6767243 (Patent Document 1), a metal oxide (e.g., CuO), metal hydroxide, metal carbonate, or the like is added and dissolved in the plating solution in an amount corresponding to the amount of electrolysis to replenish the metal ions and neutralize the acid. Furthermore, an ion exchange membrane, such as that described in Patent Document 2, is generally used as a diaphragm separating the plating tank into the anode chamber and the cathode chamber.

[0003] Patent No. 6767243 Specification Patent No. 7165843 Specification

[0004] When the anode chamber and cathode chamber are separated by a cation exchange membrane, both hydrogen ions and metal ions (copper ions) pass through the cation exchange membrane. Therefore, after plating begins, copper ions in the anolyte gradually migrate into the catholyte as the anolyte electrolysis proceeds. Therefore, if the amount of metal (Cu) deposited during plating is replenished to the catholyte, excessive metal ions are added to the catholyte, resulting in a deviation in the catholyte's composition. Deviation in the composition of the catholyte, which is the plating solution that comes into contact with the substrate, can adversely affect plating quality. The smaller the ratio of the catholyte volume to the anode volume, the greater the impact (deviation in the catholyte's composition) is expected to be.

[0005] The present invention aims to solve at least some of the above-mentioned problems. One of the objects of the present invention is to supply metal ions while maintaining a constant composition of the plating solution during plating.

[0006] According to one aspect of the present invention, there is provided a plating apparatus for plating a substrate, comprising: a plating tank; a cation exchange membrane that divides the plating tank into an anode chamber that holds an anolyte and a cathode chamber that holds a catholyte; an anode disposed in the anode chamber; a replenishing device that replenishes the catholyte with the same metal as the metal that is to be deposited on the substrate, or a metal compound containing the metal; and a control device that controls the replenishing device to replenish the metal or the metal compound containing the replenishment amount of the metal from the replenishing device to the catholyte, the amount being obtained by subtracting the amount of metal ions of the metal that permeated from the anode chamber to the cathode chamber through the cation exchange membrane from the amount of the metal deposited by plating on the substrate.

[0007] According to one aspect of the present invention, there is provided a plating method for plating a substrate, comprising: supplying a replenishment amount of the metal, or a compound of the metal containing the replenishment amount of the metal, to a cathode solution, the amount being obtained by subtracting the amount of metal ions of the metal that have permeated from the anode chamber to the cathode chamber through an ion exchange membrane that separates the anode chamber and the cathode chamber in a plating tank from the amount of metal deposited on the substrate by plating.

[0008] 1 is a perspective view showing the overall configuration of a plating apparatus according to an embodiment; FIG. 2 is a plan view showing the overall configuration of a plating apparatus according to an embodiment; FIG. 3 is a schematic diagram of a plating module according to an embodiment; FIG. 4 is an explanatory diagram illustrating ion reactions in a plating tank; FIG. 5 is a graph showing changes in the concentrations of copper and sulfuric acid in an anolyte; FIG. 6 is a graph showing changes in the concentration of ions in an anolyte; FIG. 7 is a graph showing changes in the transport number of ions permeating a diaphragm; FIG. 8 is a graph showing changes in the concentrations of copper and sulfuric acid in a catholyte when CuO equivalent to the amount of plating deposition is replenished; FIG. 9 is an explanatory diagram illustrating a method for calculating the replenishment amount of CuO; FIG. 10 is an explanatory diagram illustrating a method for calculating the replenishment amount of CuO; FIG. 11 is an explanatory diagram illustrating a method for calculating the replenishment amount of CuO; FIG. 12 is an explanatory diagram illustrating a method for calculating the replenishment amount of CuO; FIG. 13 is an explanatory diagram illustrating a method for calculating the replenishment amount of CuO; FIG. 14 is a diagram illustrating an example of the configuration of a plating cell used in an experiment to estimate the ionic conductivity ratio α; FIG. 15 is a graph showing changes in Cu concentration in an anolyte by experiment and simulation; FIG. 16 is a table showing an example of an estimated result of an acid dissociation equilibrium constant Ka'; 1 shows an example of numerical values ​​of parameters used in a simulation to calculate the CuO replenishment amount. Graph showing simulation results of hydrogen ion transport number. Graph showing an enlarged view of the change in hydrogen ion transport number immediately after bath make-up. Graph showing an enlarged view of the change in hydrogen ion transport number after stabilization of the anolyte composition. A simplified calculation formula for the CuO replenishment amount is shown. Graph showing the change in hydrogen ion transport number. Graph showing an enlarged view of the change in hydrogen ion transport number immediately after bath make-up. Graph showing an enlarged view of the change in hydrogen ion transport number after stabilization of the anolyte composition. Changes in ion concentration in the cathode solution when CuO equivalent to the amount of plating deposition is replenished. Transport number t of hydrogen ions obtained by simulation Ｈ 1 shows the change in ion concentration in the catholyte when CuO is replenished based on the curve of . 2 shows the change in hydrogen ion transport number and the change in ion concentration in the catholyte. 3 shows the change in hydrogen ion transport number and the change in ion concentration in the catholyte. 4 shows the change in hydrogen ion transport number and the change in ion concentration in the catholyte. 5 shows the change in hydrogen ion transport number and the change in ion concentration in the catholyte. 6 shows the change in hydrogen ion transport number and the change in ion concentration in the catholyte. ２ SO ４The figure shows the change in hydrogen ion transport number in plating solutions with a constant ratio but different Cu concentrations. ２ SO ４ The curves showing the change in hydrogen ion transport number with different ratios are shown. Correction curve: t Ｈ 1 shows a mathematical formula representing an approximation curve of a -q curve. 2 shows a table showing an example of calculating the coefficient an. 3 shows a graph showing an example of calculating the coefficient an. 4 shows an approximation formula for the coefficient an. 5 shows a table showing an example of calculating the coefficient ki. 6 shows a mathematical formula for calculating the CuO replenishment amount for an arbitrary plating solution composition. 7 shows an approximation curve of a correction curve applicable to an arbitrary plating solution composition, and a simulation result of adjusting the ion concentration in the cathode solution using the approximation curve. 8 shows an approximation curve of a correction curve applicable to an arbitrary plating solution composition, and a simulation result of adjusting the ion concentration in the cathode solution using the approximation curve. 9 shows an approximation curve of a correction curve applicable to an arbitrary plating solution composition, and a simulation result of adjusting the ion concentration in the cathode solution using the approximation curve. 10 shows an approximation curve of a correction curve applicable to an arbitrary plating solution composition, and a simulation result of adjusting the ion concentration in the cathode solution using the approximation curve. 11 shows an explanatory diagram illustrating a method for calculating the CuO replenishment amount when the ion concentration in the anolyte is directly monitored. 12 shows an example of the configuration of a plating module when the ion concentration in the anolyte is directly monitored. 1 shows a formula for calculating the amount of CuO replenishment when plating solutions (cathode solutions) of multiple plating tanks or cells are connected and the solution is managed collectively. 2 is a schematic diagram of a plating module with an enlarged view of the vicinity of a diaphragm. 3 is an explanatory diagram illustrating the movement of ions by diffusion through a diaphragm.

[0009] Hereinafter, a plating apparatus 1000 according to an embodiment of the present invention will be described with reference to the drawings. Note that the drawings are diagrammatic illustrations to facilitate understanding of the features of the object, and the dimensional ratios of the components may not necessarily be the same as those of the actual objects.

[0010] <First Embodiment> Fig. 1 is a perspective view showing the overall configuration of a plating apparatus 1000 of this embodiment. Fig. 2 is a plan view showing the overall configuration of the plating apparatus 1000 of this embodiment. As shown in Figs. 1 and 2, the plating apparatus 1000 includes a load port 100, a transfer robot 110, an aligner 120, a pre-wet module 200, a pre-soak module 300, a plating module 400, a cleaning module 500, a spin rinse dryer 600, a transfer device 700, and a control module 800.

[0011] The load port 100 is a module for loading wafers (substrates) stored in a cassette such as a FOUP (not shown) into the plating apparatus 1000 and unloading substrates from the plating apparatus 1000 to the cassette. In this embodiment, four load ports 100 are arranged horizontally, but the number and arrangement of the load ports 100 are optional. The transfer robot 110 is a robot for transporting substrates and is configured to transfer substrates between the load ports 100, the aligner 120, the pre-wet module 200, and the spin rinse dryer 600. When transferring substrates between the transfer robot 110 and the transfer device 700, the transfer robot 110 and the transfer device 700 can transfer the substrates via a temporary stage (not shown).

[0012] The aligner 120 is a module for aligning the positions of the substrate's orientation flat, notch, and the like in a predetermined direction. In this embodiment, two aligners 120 are arranged horizontally, but the number and arrangement of the aligners 120 are optional. The prewet module 200 wets the surface of the substrate to be plated with a treatment liquid such as pure water or degassed water before plating, thereby replacing air within a pattern formed on the substrate surface with the treatment liquid. The prewet module 200 is configured to perform a prewet process that replaces the treatment liquid within the pattern with a plating liquid during plating, thereby making it easier to supply the plating liquid within the pattern. In this embodiment, two prewet modules 200 are arranged vertically, but the number and arrangement of the prewet modules 200 are optional.

[0013] The presoak module 300 is configured to perform a presoak process, which involves etching away, for example, an oxide film with high electrical resistance present on the surface of a seed layer formed on the surface of a substrate to be plated before plating, using a treatment solution such as sulfuric acid or hydrochloric acid to clean or activate the surface of the substrate to be plated. In this embodiment, two presoak modules 300 are arranged vertically, but the number and arrangement of the presoak modules 300 are optional. The plating module 400 performs plating on the substrate. In this embodiment, two sets of 12 plating modules 400 are arranged vertically, three vertically and four horizontally, for a total of 24 plating modules 400, but the number and arrangement of the plating modules 400 are optional.

[0014] The cleaning module 500 is configured to perform a cleaning process on the substrate to remove plating solution and the like remaining on the substrate after plating. In this embodiment, two cleaning modules 500 are arranged vertically, but the number and arrangement of the cleaning modules 500 are optional. The spin rinse dryer 600 is a module for drying the substrate after cleaning by rotating it at high speed. In this embodiment, two spin rinse dryers 600 are arranged vertically, but the number and arrangement of the spin rinse dryers 600 are optional. The transport device 700 is a device for transporting substrates between multiple modules within the plating apparatus 1000. The control module 800 is configured to control the multiple modules of the plating apparatus 1000 and can be configured, for example, as a general computer or a dedicated computer equipped with an input / output interface with an operator.

[0015] An example of a series of plating processes performed by the plating apparatus 1000 will be described. First, a substrate stored in a cassette is loaded into the load port 100. Next, the transfer robot 110 removes the substrate from the cassette in the load port 100 and transfers the substrate to the aligner 120. The aligner 120 aligns the positions of the orientation flat, notch, and the like of the substrate to a predetermined direction. The transfer robot 110 delivers the substrate, whose direction has been aligned by the aligner 120, to the pre-wet module 200.

[0016] The pre-wet module 200 performs a pre-wet process on the substrate. The transport device 700 transports the substrate that has been subjected to the pre-wet process to the pre-soak module 300. The pre-soak module 300 performs a pre-soak process on the substrate. The transport device 700 transports the substrate that has been subjected to the pre-soak process to the plating module 400. The plating module 400 performs a plating process on the substrate.

[0017] The transfer device 700 transfers the substrate after plating to the cleaning module 500. The cleaning module 500 performs a cleaning process on the substrate. The transfer device 700 transfers the substrate after cleaning to the spin rinse dryer 600. The spin rinse dryer 600 dries the substrate. The transfer robot 110 receives the substrate from the spin rinse dryer 600 and transfers the dried substrate to a cassette on the load port 100. Finally, the cassette containing the substrate is removed from the load port 100.

[0018] It should be noted that the configuration of the plating apparatus 1000 described in FIGS. 1 and 2 is merely an example, and the configuration of the plating apparatus 1000 is not limited to the configurations shown in FIGS.

[0019] The control module 800 may be configured to include a memory (not shown) that stores various setting data such as machine parameters and various programs, and a CPU (not shown) that executes the programs stored in the memory. The control module 800 may also include an input / output interface that includes an output device such as a display, and input devices such as a keyboard and a mouse. The storage medium that constitutes the memory may include any volatile storage medium and / or any non-volatile storage medium. The storage medium may include one or more of any storage media, such as a ROM, RAM, hard disk, CD-ROM, DVD-ROM, or flexible disk. Some or all of the functions of the control module 800 may be configured using hardware such as an ASIC. Some or all of the functions of the control module 800 may be configured using a PLC, sequencer, or the like. Some or all of the control module 800 may be located inside and / or outside the housing of the plating apparatus 1000. Some or all of the control module 800 is communicatively connected to each component of the plating apparatus via wired and / or wireless communication.

[0020] [Plating Module] Next, a description will be given of the plating module 400. Since the multiple plating modules 400 included in the plating apparatus 1000 according to this embodiment have the same configuration, only one plating module 400 will be described.

[0021] FIG. 3 is a schematic diagram of a plating module according to one embodiment. As shown in FIG. 3 , the plating apparatus 1000 (plating module 400) according to this embodiment is a plating apparatus (plating module) of a type known as a face-down type, cup type, horizontal type, or the like, in which a substrate Wf is held horizontally for plating. The plating module 400 according to this embodiment mainly includes a plating tank 410, a substrate holder 11 (also known as a plating head) that holds the substrate Wf, a rotation mechanism, a tilt mechanism, and a lift mechanism (not shown) that rotate, tilt, and lift the substrate holder 11, an anode 430 positioned below and facing the substrate Wf, and a diaphragm 440 that divides the plating tank 410 into a cathode chamber Cca and an anode chamber Can. However, the tilt mechanism may be omitted. An overflow tank 420 is provided outside the plating tank 410 to receive cathode solution Pc that overflows from the plating tank 410.

[0022] The plating tank 410 according to this embodiment is configured as a bottomed container with an opening at the top. The plating tank 410 forms a generally cylindrical internal space for storing plating solutions (cathode solution Pc and anolyte Pa). In this specification, the cathode solution and the anolyte are also referred to as catholyte and anolyte. In this specification, when used in the context of maintaining a constant composition of the plating solution, the plating solution refers to the cathode solution Pc.

[0023] The plating solution may be any solution containing ions of the metal elements that make up the plating film, and specific examples thereof are not particularly limited. In this embodiment, copper plating is used as an example of plating, and a copper sulfate solution is used as an example of plating solution. The plating solution may contain predetermined additives.

[0024] The plating tank 410 is provided with a supply port 411 as an inlet for introducing the anode solution Pa and a supply port 412 as an inlet for introducing the cathode solution Pc. The overflow tank 420 is provided with a discharge port 413 for discharging the plating solution from the overflow tank 420. In addition, an exhaust passage 417 of the anode chamber Can, which will be described later, is provided with a discharge port 414 for discharging the anode solution Pa in the exhaust passage 417 into the overflow tank 420.

[0025] A paddle (not shown) may be disposed near the substrate Wf inside the plating tank 410. The paddle reciprocates in a direction generally parallel to the surface to be plated of the substrate Wf, generating a strong flow of plating solution on the surface of the substrate Wf. This homogenizes the ions in the plating solution near the surface of the substrate Wf, improving the in-plane uniformity of the plating film formed on the surface of the substrate Wf.

[0026] A porous resistor 450 is disposed below the paddle inside the plating tank 410. Specifically, the resistor 450 is configured as a porous plate member having a plurality of holes (pores). The plating solution below the resistor 450 passes through the resistor 450 and can flow above the resistor 450. The resistor 450 is a member provided to homogenize the electric field formed between the anode 430 and the substrate Wf. By disposing the resistor 450 in the plating tank 410, the thickness of the plating film (plating layer) formed on the substrate Wf can be easily homogenized. Note that the resistor 450 is not an essential component in this embodiment, and the present embodiment may also be configured without the resistor 450.

[0027] An anode mask 431 is disposed below the resistor 450. The anode mask 431 has an opening that exposes the anode 430, and this opening adjusts the area of ​​the exposed anode 430 and adjusts the electric field between the anode and the substrate. The anode mask 431 may be a variable anode mask whose opening dimensions can be adjusted by an actuator or the like. The anode mask 431 may be omitted.

[0028] The diaphragm 440 divides the interior of the plating tank 410 into a cathode chamber Cca and an anode chamber Can below the resistor 450, or below the anode mask 431 in this embodiment. In this embodiment, a cation exchange membrane that is permeable to cations is used as the diaphragm 440. The diaphragm 440 may be composed of multiple membranes.

[0029] In this embodiment, the anode 430 is disposed in close contact with the lower surface of the diaphragm 440. The upper surface of the diaphragm 440 may be pressed from above by a diaphragm presser (for example, a plate- or sheet-like member having a plurality of holes, e.g., a mesh-like portion) not shown. In this embodiment, an insoluble anode is used as the anode 430. The specific type of this insoluble anode is not particularly limited, and examples thereof include platinum, titanium, iridium oxide (e.g., IrO ２ The surface of the anode 430 may further have a topcoat layer for the purpose of suppressing decomposition of additives in the plating solution.

[0030] In this embodiment, the anode 430 is a plate-like member (e.g., a disk-shaped member) having a large number of through-holes (not shown) connecting the front and back surfaces thereof. The anode 430 is configured so that the anolyte Pa comes into contact with the diaphragm 440 via the through-holes, allowing cations in the anolyte Pa to migrate through the diaphragm 440 to the cathode chamber Cca (cathode solution Pc).

[0031] The anode 430 and the diaphragm 440 are brought into close contact with each other, thereby preventing gas (e.g., oxygen generated at the anode) from accumulating between the anode 430 and the diaphragm 440 and affecting the electric field and ion conduction path between the anode and the substrate. The diaphragm 440 is configured to be impermeable to gases such as oxygen generated at the anode.

[0032] A back plate 81 for adjusting the amount of bubbles is disposed below the anode 430, adjacent to and spaced a predetermined distance from the underside of the anode 430. The back plate 81 adjusts the amount of oxygen generated by the anode 430 that accumulates on the underside of the anode 430 and prevents a large amount of oxygen from escaping from the underside of the anode 430 all at once, which would cause large fluctuations in the anode voltage. The back plate 81 allows a constant amount of oxygen to accumulate between the underside of the anode 430 and the back plate 81, and allows the oxygen to be released and discharged in small amounts to suppress large fluctuations in the anode voltage. This makes it possible to suppress deterioration in plating quality caused by large fluctuations in the anode voltage.

[0033] It should be noted that, instead of the back plate 81, a ring member of a predetermined height may be provided that surrounds the outer periphery of the lower surface of the anode 430. Such a ring member can also achieve similar or equivalent effects to those of the back plate 81.

[0034] The anode chamber Can is connected to the atmosphere via an exhaust passage 417 extending vertically beside the cathode chamber Cca. The exhaust passage 417 allows for the exhaust of gas (oxygen) generated in the anode 430. When an insoluble anode is used, oxygen is generated by electrolysis of water in the anode 430. A liquid level sensor 415 for detecting the liquid level of the anode fluid is disposed in the exhaust passage 417. The liquid level sensor 415 may be an analog liquid level sensor capable of continuously detecting the liquid level of the anode fluid. The liquid level sensor 415 may be an on / off liquid level sensor capable of detecting a lower limit of the anode fluid level. Alternatively, an on / off liquid level sensor capable of detecting an upper limit of the anode fluid level may be provided. By controlling the amount of anode fluid so as to maintain the liquid level at or above the lower limit, depletion of the anode fluid can be prevented. By controlling the amount of the anode fluid so as to maintain the anode fluid level at or below the upper limit, it is possible to suppress or prevent the anode fluid Pa in the anode chamber from which the additive has been consumed from flowing into the overflow tank 420 and being circulated to the cathode chamber Cca, thereby suppressing or preventing a decrease in the concentration of the additive in the cathode fluid in the cathode chamber Cca and deterioration of the additive.

[0035] In this embodiment, a common plating solution having the same composition is introduced into the cathode chamber Cca and the anode chamber Can as the cathode solution Pc and the anolyte Pa. The common plating solution is mainly composed of an aqueous copper sulfate solution and may contain a trace amount of hydrochloric acid. Note that this embodiment is also applicable to other types of cathode solutions and anolytes.

[0036] 3 , a circulation circuit 470 that supplies and circulates plating solutions (cathode solution, anode solution) is connected to the plating tank 410. A pure water supply line 474 that supplies pure water (e.g., DIW) to the cathode chamber Cca is also connected to the plating tank 410. The pure water supply line 474 is also piped to supply pure water (e.g., DIW) to a reservoir tank 481 and a plating solution adjustment tank 482 in the circulation circuit 470.

[0037] 3 , the circulation circuit 470 includes a reservoir tank 481 and a plating solution adjustment tank 482. The reservoir tank 481 receives the plating solution supplied from the plating solution adjustment tank 482, the plating solution discharged from the overflow tank 420, and DIW, and supplies the plating solution after adjusting the concentration thereof to the cathode chamber Cca and the anode chamber Can as cathode solution Pc and anolyte Pa, and also returns the plating solution to the plating solution adjustment tank 482. A fluid line 471 is connected to the output of the reservoir tank 481, and a pump 475 on the fluid line 471 supplies the plating solution from the reservoir tank 481 to the cathode chamber Cca, the anode chamber Can, and the plating solution adjustment tank 482. At the output side of the pump 475, the fluid line 471 branches into a plating tank 410 side and a plating solution adjustment tank 482 side, and the fluid line 471 on the plating tank 410 side further branches into a cathode chamber Cca side and an anode chamber Can side. Valves 477 and 478 are provided on the fluid line 471 on the cathode chamber Cca side and the anode chamber Can side, respectively. The valves 477 and 478 may be either on-off valves or flow rate control valves. By controlling the opening and closing of the valves 477 and 478, the plating solution is supplied to the cathode chamber Cca and the anode chamber Can.

[0038] The plating solution adjustment tank 482 receives the plating solution from the reservoir tank 481, appropriately adds / supplies one or more types of additives to the plating solution and powdered copper oxide (CuO) to the plating solution, adjusts the concentration of the plating solution with DIW, and then supplies the concentration-adjusted plating solution to the reservoir tank 481 via the fluid line 473 using a pump 476. The plating solution adjustment tank 482 is provided with an agitator 483, which is configured to agitate the plating solution so that the additives and copper oxide (CuO) are dissolved in the plating solution.

[0039] DIW is supplied to the anode chamber Can via a pure water supply line 474 and a valve 479. DIW is also supplied to the reservoir tank 481 via a pure water supply line 474 and a valve 480. DIW is also supplied to the plating solution adjustment tank 482 via the pure water supply line 474 and a valve (not shown).

[0040] In another embodiment, the reservoir tank 481 and the plating solution adjustment tank 482 may be integrated. That is, the reservoir tank 481 may be used to supply additives and replenish CuO, and the plating solution adjustment tank 482 may be omitted.

[0041] In this embodiment, the circulation circuit 470 circulates the cathode solution Pc in the cathode chamber Cca, but the anode solution Pa is not circulated in the anode chamber Can, and only the level of the anode solution Pa is managed by the liquid level sensor 415. Specifically, when preparing a new plating solution in the plating tank 410, after the plating solution (anode solution Pa, cathode solution Pc) is introduced into the anode chamber Can and the cathode chamber Cca, no plating solution is supplied to the anode chamber Can, and when the anode solution level falls below a predetermined lower limit, DIW is replenished to maintain the solution level at or above the lower limit.

[0042] 4 is an explanatory diagram illustrating the reaction of ions in a plating bath. As shown in the figure, water is electrolyzed at the anode 430 to produce hydrogen ions H ＋ and oxygen O ２ In addition, copper ions (Cu ions) Cu in the anode chamber Can (anode fluid Pa)２＋ and hydrogen ions H ＋ moves into the cathode chamber Cca (cathode fluid Pc) through the diaphragm 440. In the cathode chamber Cca, copper ions Cu in the cathode fluid Pc ２＋ is reduced on the substrate Wf and precipitates as copper (Cu) on the substrate Wf. In addition, CuO is dissolved in the cathode solution Pc discharged from the cathode chamber Cca in the circulation circuit 470, and copper ions Cu ２＋ When electrolysis is performed, a difference in the concentration of cations occurs between the anode chamber Can and the cathode chamber Cca, and hydrogen ions H ＋ and the movement of copper ions Cu from the cathode chamber Cca to the anode chamber Can ２＋ The movement of ions occurs, but at a slower rate than the movement of ions due to electrolysis.

[0043] FIG. 5A shows the copper (Cu) and sulfuric acid (H ２ SO ４ 5B is a graph showing changes in the concentration of ions in the anolyte. FIG. 5C is a graph showing changes in the transport number of ions permeating through the diaphragm. FIG. 5D is a graph showing changes in the copper and sulfuric acid concentrations in the catholyte when CuO equivalent to the amount of plating deposition is replenished.

[0044] Typically, in a plating apparatus, when preparing a new plating solution in a plating tank, a solution having the same composition as the cathode solution Pc (plating solution) is introduced into the anode chamber Can as the anode solution Pa. When plating is performed using an insoluble anode, copper is deposited at the cathode (substrate Wf) in an amount corresponding to the amount of electrolysis (amount of charge flowing due to the plating current), consuming copper ions in the cathode solution Pc, while acid is generated at the anode 430. For this reason, a metal or metal compound is added and dissolved in the cathode solution in an amount corresponding to the amount of electrolysis (amount of charge) to replenish the metal ions and neutralize the acid. Metal compounds include metal oxides (CuO), metal hydroxides (Cu(OH)), and the like. ２ , metal carbonate (CuCO ３ ) etc.

[0045] When the anode chamber Can and the cathode chamber Cca are separated by a cation exchange membrane diaphragm 440, both hydrogen ions and metal ions (Cu ions) pass through the cation exchange membrane. As a result, the concentrations of copper and sulfuric acid in the anolyte change as shown in FIG. 5A, and the concentration of ions in the anolyte also changes as shown in FIG. 5B. During electrolysis, the Cu ion concentration gradually decreases and the hydrogen ion concentration increases.

[0046] The transport number of ions permeating the cation exchange membrane during plating changes as shown in Figure 5C. That is, during plating (especially in the early stages of plating), Cu ions move from the anode chamber (Can) to the cathode chamber (Cca) through the cation exchange membrane. Therefore, if the amount of Cu deposited during plating is replenished to the cathode solution, excessive Cu ions will be added to the cathode solution, resulting in a deviation in the composition of the cathode solution, as shown in Figure 5D. This effect is particularly significant as the ratio of the amount of cathode solution to the amount of anolyte solution decreases. Therefore, to stabilize the composition of the cathode solution, copper must be replenished taking into account the amount of Cu ions permeating the membrane. Specifically, the amount of copper replenished is calculated by subtracting the amount of Cu ions permeating the membrane from the amount of plating deposition (amount of electrolysis).

[0047] 6A to 6D are explanatory diagrams illustrating a method for calculating the amount of CuO to be replenished. Here, an example is given in which copper oxide (CuO) is replenished to the catholyte in copper plating to replenish the metal and neutralize the acid.

[0048] In Figures 6A-C, t Ｈ (q) is hydrogen ion H ＋ Transference number, t Ｃｕ (q) is Cu ion Cu ２＋ In the following explanation, t Ｈ , t Ｃｕ The transport number is the ratio of the current carried by a specific ion to the total current when a current is passed through an electrolyte solution, and is defined as the number of moles (mol) of ions per 1 F (Faraday) multiplied by the valence of the ion. 1F means the Faraday constant, or Faraday Fd, which represents the unit of charge. The Faraday constant is the amount of charge per 1 mol of electrons (or holes), and is expressed as the Avogadro constant N Ａ (6.02 x 10 ２３ [mol－１ ]) and elementary charge e (1.60217663 × 10 －１９ [C])

[0049] If a total charge of q [F] is applied by the plating current flowing between the substrate and the anode from the time when the plating solution is newly prepared in the plating tank, then (1 / 2) q [mol] of Cu will be deposited on the substrate Wf. ２＋ is a divalent ion, and 2 moles of electrons are introduced corresponding to the deposition of 1 mole of copper, so the number of moles of Cu is calculated by multiplying the charge amount [F] by (1 / 2). Hereinafter, the total amount of charge that has flowed into the plating tank since the preparation of a new plating solution is referred to as the total charge amount.

[0050] If the total charge amount q [F] changes from q1 [F] to q2 [F] during plating, the number of moles of Cu deposited on the substrate during that time is calculated by multiplying the change in the total charge amount q2-q1 by (1 / 2), or (1 / 2)(q2-q1).

[0051] At this time, the charge amount (mol) carried by the Cu ions moving from the anode chamber Can to the cathode chamber Cca is calculated by the transport number t Ｃｕ As mentioned above, Cu ions are divalent ions, so the amount (mol) of Cu ions that move from the anode chamber Can to the cathode chamber Cca is calculated by the transport number t Ｃｕ It is the integral of (q) from q1 to q2 multiplied by (1 / 2).

[0052] Therefore, the amount (mol) of Cu ions that is net consumed in the catholyte, that is, the amount (mol) of copper that needs to be replenished, is given by the middle part of equation (1) in FIG. 6A.

[0053] Since the movement of anions through the cation exchange membrane (membrane 440) can be ignored, the ions that carry the current flow from the anolyte to the catholyte through the membrane 440 are hydrogen ions H ＋ and Cu ions Cu ２＋ Therefore, t Ｈ (q) + t Ｃｕ (q)=1 (see equation (2) in FIG. 6A). Therefore, equation (1) becomesＨ (q) (the right side of equation (1) in FIG. 6A). That is, the amount (mol) of Cu ions consumed net in the catholyte is expressed as the ratio of hydrogen ions H ＋ Transference number t Ｈ It can be calculated by integrating (q) from q1 to q2 and multiplying the integral by (1 / 2).

[0054] Hydrogen ion transport number t Ｈ (q) can be expressed as a function of the total charge amount q, and in the following explanation, t Ｈ The -q curve is also called a correction curve. The correction curve is a curve for correcting the Cu ion concentration in the catholyte. The CuO replenishment amount (mol) is calculated by the correction curve: t Ｈ It can be said that the area of ​​the -q curve is multiplied by (1 / ion valence).

[0055] If the volume of the anolyte is V [L] and the sulfuric acid concentration in the anolyte is Ca [mol / L], then V, Ca, t Ｈ (q), t Ｃｕ The relationship of Equation (3) holds between (q) and (q). Equation (3) can be expressed as Equation (4).

[0056] Hydrogen ion H ＋ , Cu ion Cu ２＋ The ionic conductivity of each Ｈ ,Λ Ｃｕ , hydrogen ions H in the anolyte ＋ , Cu ion Cu ２＋ The concentrations of [H ＋ ], [Cu ２＋ ], then the respective transport numbers t Ｈ (q), t Ｃｕ (q) can be expressed as the middle part of equations (5) and (6). Here, in the middle part of equations (5) and (6), the denominator and numerator are Λ Ｃｕ Divide by and get the ionic conductivity ratio α=Λ Ｈ / Λ Ｃｕ Then, the transport number t Ｈ (q), t Ｃｕ (q) can be expressed as the right-hand side of equations (5) and (6).

[0057] The Cu concentration in the anolyte is C Ｃｕ(mol / L), the membrane permeation of anions can be ignored, and the relationship of formula (7) holds. That is, during plating treatment, sulfuric acid (H ２ SO ４ ) Concentration Ca and Cu concentration C Ｃｕ The sum of is kept constant at C.

[0058] The method of deriving equations (8) to (12) will be described with reference to Figures 6C and 6D. As shown in Figure 6D, ２ SO ４ is ionized in two stages, and in the first stage (dissociation), monovalent hydrogen sulfate ions, HSO ４ － The acid dissociation equilibrium constant Ka = 1000 is almost completely ionized in the second stage of ionization, and the divalent sulfate ion SO ４ ２－ The ionization to hydrogen is very small (acid dissociation equilibrium constant Ka = 0.0102). Therefore, the hydrogen ion concentration [H ＋ ], only the second-stage equilibrium reaction needs to be considered.

[0059] In FIG. 6C, when the acid dissociation equilibrium constant is Ka and the activity coefficient is γ, the relationship of Equation (21) holds. Ｈ ＋ , a ＳＯ４ ２－ , a ＨＳＯ４ － indicate the activities of hydrogen ions, sulfate ions, and hydrogen sulfide ions, respectively. Ｈ ＋ , γ ＳＯ４ ２－ , γ ＨＳＯ４ － and represent the activity coefficients of hydrogen ions, sulfate ions, and hydrogen sulfide ions, respectively. ＋ ], [SO ４ ２－ ], [HSO ４ － ] represent the concentrations of hydrogen ions, sulfate ions, and hydrogen sulfate ions, respectively. If the first term on the second right-hand side of equation (21) is Kγ, it can be expressed as shown on the third right-hand side. Here, the relationship in equation (22) is derived from the left-hand side and the third right-hand side of equation (21), and Ka / Kγ=Ka'.

[0060] Total CuSO in the anolyte ４ Concentration C Ｃｕ , all H ２ SO ４ If the concentration is Ca, then C Ｃｕ = [Cu ２＋ ], and equation (23) holds.

[0061] From equations (22) and (23), as shown in equations (24) and (25), [SO ４ ２－ ], [HSO4 － ] can be written.

[0062] Here, since electroneutrality holds, the relationship of equation (26) holds.

[0063] Substituting equations (24) and (25) into equation (26) and rearranging, we obtain [H ＋ When the quadratic equation of Equation (27) is expressed using a solution formula, it is expressed as Equation (8) in FIG. 6B as [H ＋ In equation (8), the parameters b and c are expressed by equations (9) and (10). In equation (9), the relationship in equation (7) is used to determine C Ｃｕ is replaced by C—Ca. ２＋ ] can be expressed as equation (12) from equations (23) and (7).

[0064] Ka' is the acid ionization equilibrium constant in the anolyte, and can be expressed as in equation (22) to equation (11).

[0065] (Estimation of Ionic Conductivity Ratio α) Estimation of the ionic conductivity ratio α (see formulas (5) and (6) in FIG. 6A ) will be described with reference to FIGS. 7A and 7B . FIG. 7A shows an example of the configuration of a plating cell (plating tank) used in an experiment to estimate the ionic conductivity ratio α. FIG. 7B is a graph showing changes in Cu concentration in the anolyte through experiments and simulations.

[0066] 7A, a substrate Wf' and an anode 430' are disposed facing each other, and a diaphragm (ion exchange membrane) 440' that separates the cathode chamber from the anode chamber is disposed between the substrate Wf' and the anode 430'. A Cu concentration meter 416' is disposed in the anode chamber. Also shown in FIG. 7A is a paddle device 460' that stirs the cathode solution.

[0067] Using a plating cell (plating tank) such as that shown in FIG. 7A , a substrate Wf was plated at a constant current using anolyte Pa with known Cu and sulfuric acid concentrations, and the Cu concentration (or sulfuric acid concentration) in the anolyte Pa was monitored. The cathode solution Pc was periodically replenished with CuO to compensate for plating deposition. The anolyte Pa was periodically replenished with DIW to compensate for losses due to electroosmosis and evaporation, maintaining a constant anolyte level. Simulations were also performed with varying values ​​of the ionic conductivity ratio α, and the resulting Cu concentration change curves were compared with the actual Cu concentration changes obtained in experiments to determine the value of α that best reproduced the experimental results. As a result, an ionic conductivity ratio α of ≈4 was obtained. The simulations were performed using a method similar to that described in the simulation example below, with the acid dissociation equilibrium constant Ka' of sulfuric acid set to ≈0.25, the Cu concentration in the anolyte Pa, the sulfuric acid concentration, and the amount of anolyte used in the experiments set to initial values, and the value of α was varied.

[0068] (Estimation of Acid Dissociation Equilibrium Constant Ka') Next, a method for experimentally determining the acid dissociation equilibrium constant Ka' of sulfuric acid will be described. Because the activity coefficient does not become 1 at high concentrations (high ionic strength), a method was adopted in which solutions with different sulfuric acid concentrations were prepared and the pH was measured to experimentally estimate Ka'. The results are shown in Figures 8A and 8B.

[0069] 8A is a table showing the estimated results of the acid dissociation equilibrium constant Ka'. FIG. 8B is a graph showing the estimated results of the acid dissociation equilibrium constant Ka'. As can be seen from these figures, when Ka' = 0.249, the measured pH and calculated pH values ​​were roughly consistent. Based on this result, in this embodiment, the acid dissociation equilibrium constant Ka' of sulfuric acid is set to be approximately 0.25.

[0070] 9 shows an example of the numerical values ​​of parameters used in a simulation for calculating the amount of CuO supplementation. As shown in the figure, the experimentally determined ionic conductivity ratio α=Λ H / Λ cu Using the Cu concentration of the anolyte as ≈4, the acid dissociation equilibrium constant Ka' of sulfuric acid as ≈0.25, and assuming that the initial Cu concentration of the anolyte is 50 g / L (0.787 mol / L) and the initial sulfuric acid concentration of the anolyte is 100 g / L (1.02 mol / L), the constant value C in equation (7) can be set to C = 1.807 (mol / L). Here, the initial concentration refers to the concentration at the time of bath preparation. Also, the volume V [L] of the anolyte is set constant at 4.25 L. Applying these prerequisites (values) to equations (8) to (10), the hydrogen ion concentration [H ＋ ] can be expressed as a function of Ca. For convenience of explanation, [H ＋ ]=f １ (Ca). １ is Ca and [H ＋ ] is a function showing the relationship between [Cu ２＋ ] is calculated from formula (12) as [Cu ２＋ ]=C-Ca, and can be expressed as a function of Ca.

[0071] Next, in formula (5), [H ＋ ]=f １ (Ca), [Cu ２＋ ] = C - Ca, α = 4, then the transference number t Ｈ can be expressed as a function of Ca. Here, for convenience, t Ｈ = f ２ (Ca). ２ Ca and t Ｈ is a function that shows the relationship between

[0072] This transport number t Ｈ = f ２ Substituting (Ca) into equation (3), dCa / dq becomes a function of Ca, dCa / dq=f ３ (Ca), which is a differential equation for Ca. ２ is a function that shows the relationship between Ca and dCa / dq. This differential equation is dCa / dq=f ３(Ca) is numerically analyzed to calculate the value of Ca for each total charge amount q, thereby obtaining a curve (Ca-q curve) showing the relationship between Ca and q.

[0073] Next, using the Ca-q curve, the transport number t for each total charge q is calculated from equation (4). Ｈ Calculate t Ｈ and q (correction curve: t Ｈ -q curve) can be obtained.

[0074] This correction curve (t Ｈ -q curve) in equation (1), t is calculated from any change interval (q1 to q2) of the total charge amount q. Ｈ By integrating with q, the number of moles of the amount of Cu to be replenished (CuO in this embodiment) can be obtained.

[0075] (Simulation Results) Fig. 10A is a graph showing the simulation results of the hydrogen ion transport number. Fig. 10B is a graph showing, in enlarged form, the change in the hydrogen ion transport number immediately after bath make-up. Fig. 10C is a graph showing, in enlarged form, the change in the hydrogen ion transport number after the anolyte composition has stabilized.

[0076] As shown in FIG. 10A, the transport number t of hydrogen ions changes as the total charge changes from 0 to 5000 [Ah]. Ｈ changes from a value near 0.8 (less than 0.8) to a value close to 1. Figures 10B and 10C are excerpts of the graph in Figure 10A, one immediately after bath make-up and the other after the anolyte composition has stabilized. As shown in Figures 10B and 10C, the amount of CuO replenishment (mol) can be determined from the resulting curves. Here, the amount of CuO to be added when replenishing every 50 Ah is determined from the graph. In Figures 10A to 10C, the integral value of the hydrogen ion transport number is shown in [Ah], so the integral value of the hydrogen ion transport number (t Ｈ The amount of CuO replenishment [mol] can be calculated by converting the area of ​​the -q curve (area of ​​the -q curve) into [F] and multiplying it by 1 / 2 (see formula (1) in FIG. 6A).

[0077] 10A to 10C, the amount of CuO added when replenishment is performed every total charge amount q=50 Ah is shown by the correction curve: t ＨThe transport number t of hydrogen ions is determined by the total charge q (horizontal axis in Figures 10A to 10C) after the bath is made up. Ｈ Since the amount of CuO replenishment varies in each section (each section of the 50 Ah width section), the transport number t of hydrogen ions varies depending on the total charge amount, especially until the composition of the anolyte stabilizes (until the Cu concentration becomes sufficiently low). Ｈ It is believed that the total charge q substantially changes, and it can be seen that the CuO replenishment amount also changes depending on the total charge q (Fig. 10B). On the other hand, after the composition of the anolyte stabilizes (after the Cu concentration becomes sufficiently low), it is believed that the net movement of Cu ions from the anode to the cathode becomes substantially zero, so the CuO replenishment amount (hydrogen ion transport number t Ｈ The integral of t × 1 / 2) is considered to be an amount corresponding to the amount of copper precipitated. Ｈ is constant and does not change with the total charge q (horizontal axis, Ah), and the hydrogen ion transport number t Ｈ The integral value of increases at a constant gradient, and the amount of CuO replenished becomes constant.

[0078] (Simplified calculation formula) Correction curve t Ｈ Instead of calculating the area of ​​−q by integration as described above, a simplified formula for calculating the amount of CuO to be replenished by approximating it with the area of ​​a rectangle will now be described.

[0079] Fig. 11 shows a simplified formula for calculating the amount of CuO replenishment. Fig. 12A is a graph showing changes in the transport number of hydrogen ions. Fig. 12B is a graph showing, in enlarged form, changes in the transport number of hydrogen ions immediately after bath make-up. Fig. 12C is a graph showing, in enlarged form, changes in the transport number of hydrogen ions after the composition of the anolyte has stabilized. In Figs. 12A to 12C, the horizontal axis of the graph shows the total charge (Ah) from immediately after bath make-up, and the vertical axis shows the transport number of hydrogen ions.

[0080] As described above, when CuO is replenished to the cathode solution, it is sufficient to add CuO to the cathode solution in an amount equivalent to the amount of hydrogen ions that have moved from the anode chamber to the cathode chamber due to electrolysis. In the same manner as described above, the relationship between the amount of electrolysis (total charge amount) and the amount of hydrogen ions that have moved is obtained in advance by simulation, and a correction curve (t ＨUsing this correction curve and equation (1A) in FIG. 11, the total charge amount qc from the time of bath preparation to the time of replenishment, and the total charge amount q from the time of bath preparation to the time of the previous replenishment are calculated. ｐ The amount of CuO to be supplied (mol) is determined from the formula (1A) in FIG. １ , q ２ q ｃ , q ｐ It is said that. １ , q ２ and q ｃ , q ｐ may be interchangeable with each other.

[0081] CuO replenishment interval is t Ｈ When the change in the hydrogen ion transport number t Ｈ Instead of calculating the CuO replenishment amount by integrating with the total charge amount q, the correction curve: t Ｈ The integral value can be calculated approximately by the area of ​​the rectangle in the replenishment interval of the -q curve. ｐ [F] = 50 [Ah] to q ｃ Considering the section [F] = 100 [Ah], t in this section Ｈ The area / integral value of q = q ｐ From q = q ｃ t in Ｈ The average value (length of the vertical axis), that is, (1 / 2)(t Ｈ (q ｐ ) + t Ｈ (q ｃ )) the change in q in this section q ｃ -q ｐ (length of the horizontal axis) is multiplied by the area of ​​the rectangle. Therefore, the integral part of equation (1) is (1 / 2)(t Ｈ (q ｐ ) + t Ｈ (q ｃ )) × (q ｃ -q ｐ) can be substituted to calculate the CuO supplement amount (mol) as shown in formula (1A). However, since the unit of charge in formula (1A) is F, the value obtained by converting the charge [Ah] to [F] is used. Formula (1A) represents (1 / 2) × (area of ​​a rectangle).

[0082] When the replenishment interval is short, the correction curve: t Ｈ In the -q curve, the total charge q from the time of bath preparation to the time of the previous replenishment ｐ (F) and the total charge q from the time of bath preparation to the time of this replenishment ｃ By calculating the area of ​​the rectangle between (A) and (B), the amount of CuO replenished (mol) can be calculated easily and accurately.

[0083] 10A-C, in FIGS. 12A-C, the amount of CuO added when replenishment is performed every 50 Ah is determined from the correction curve. As described above, the total charge q (horizontal axis of FIGS. 12A-C) after the bath is made up is used to calculate the transport number t of hydrogen ions. Ｈ Since the amount of CuO replenishment varies in each section (each section of the 50 Ah width section), the transport number t of hydrogen ions varies depending on the total charge q as shown in FIG. 12B until the composition of the anolyte is stabilized. Ｈ changes, and the CuO replenishment amount (area of ​​the rectangle × 1 / 2) also changes depending on the total charge amount q. On the other hand, after the composition of the anolyte is stabilized, the hydrogen ion transport number t Ｈ is constant without changing, and the CuO replenishment amount (area of ​​the rectangle × 1 / 2) is also constant without changing due to the total charge amount q.

[0084] 13A shows the change in ion concentration in the cathode solution when CuO equivalent to the plating deposition amount is replenished. Ｈ The graphs show the change in ion concentration in the catholyte when CuO is replenished based on the curves of 1 and 2. As can be seen from the comparison of these graphs, in contrast to the shift in the composition of the catholyte when CuO equivalent to the plating deposition amount is replenished, the transference number t Ｈ Based on the curves, it can be seen that CuO replenishment keeps the catholyte composition constant.

[0085] (Control Example) The supply of CuO is performed by controlling the supply device 485 using the control module 800. (1) Correction curve t calculated by simulation Ｈ -q (FIGS. 10A and 12A) is stored in a storage device, and the amount of CuO replenishment (mol) is calculated from formula (1) or (1A) according to the total charge amount q (calculated from the plating current and plating time), and CuO can be replenished to the catholyte. When formula (1) is used, the correction curve t Ｈ When formula (1A) is used, the correction curve t is drawn at intervals of a predetermined total charge amount q, as shown in FIGS. Ｈ CuO of the value obtained by approximating the area of ​​-q to the area of ​​a rectangle × (1 / 2) can be replenished. The total charge amount q can be calculated from the plating current and plating time (time integral of the plating current, or multiplication of the plating current and plating time). (2) Correction curve t calculated by simulation Ｈ -q area or supply amount (= correction curve t Ｈ The area of ​​the total charge q × (1 / 2) may be stored in the storage device for each section of the total charge q. In this case, the storage device may store the correction curve t Ｈ The area of ​​-q or the amount of replenishment can be read out to replenish CuO. Ｈ When the area of ​​-q is stored, the amount of supply can be calculated by multiplying it by 1 / 2.

[0086] Second Embodiment (Correction of CuO Replenishment Amount in Different Plating Solution Compositions) The second embodiment will be described with respect to the differences from the first embodiment, and a description of the same points as the first embodiment will be omitted.

[0087] 14A to 14D show the changes in the hydrogen ion transport number and the changes in the ion concentration in the catholyte for different plating solution compositions. ２ SO ４is the initial Cu concentration in the anolyte (when the bath is made up), and the concentration ratio Cu / H ２ SO ４ As can be seen from these graphs, when the composition of the plating solution differs, it is necessary to use a different correction curve (a curve of change in the transport number of hydrogen ions) to determine the amount of CuO to be replenished and to correct the ion concentration in the cathode solution.

[0088] FIG. 15A shows Cu / H ２ SO ４ The hydrogen ion transport number t in plating solutions with a constant ratio and different Cu concentrations Ｈ FIG. 15B shows the change curve of Cu / H at a constant Cu concentration. ２ SO ４ Different ratios of hydrogen ion transport numbers t Ｈ The change curve of

[0089] As shown in FIG. 15A, Cu / H ２ SO ４ When the ratio is constant, the initial hydrogen ion transport number t Ｈ are almost the same, and the transport number t of hydrogen ions increases with the increase in the amount of electrolysis (total charge amount) as the Cu concentration increases. Ｈ When the Cu concentration is constant, as shown in FIG. ２ SO ４ The higher the ratio, the greater the initial hydrogen ion transport number t Ｈ As the amount of electrolysis (total charge) increases, the transport number t Ｈ Based on the above considerations, a correction curve (t Ｈ -q curve) obtained by simulation Ｈ An approximation curve for the -q curve was calculated, and the coefficients of the approximation curve were automatically determined according to the plating solution composition.

[0090] FIG. 16A shows the correction curve: t Ｈ The formula (31) represents an approximate curve of the -q curve. Ｃｕ In the Ｈ Equation (31A) is a mathematical formula that represents an approximation curve of the initial Cu concentration C Ｃｕ = 50 g / L, tＨ These are mathematical formulas that represent the approximate curve of the -q curve. １ , a ２ , a ３ is a coefficient. In the following description, the coefficient a １ , a ２ , a ３ An arbitrary coefficient of may be referred to as an.

[0091] 16B and 16C show the Ｈ Coefficient a of the formula representing the approximate curve of the -q curve １ , a ２ , a ３ 16B is a table and a graph showing an example of calculation of the initial Cu concentration C Ｃｕ = 50 g / L (fixed), and the initial concentration ratio Cu / H ２ SO ４ By changing t from the same simulation as above, Ｈ -q curve was calculated, and the t obtained from the simulation Ｈ Using the -q curve, the coefficient a １ , a ２ , a ３ The results are shown in FIG. 16B. The results of FIG. 16B are shown in a graph in FIG. 16C. The horizontal axis of the graph represents the initial concentration ratio Cu / H in the anolyte. ２ SO ４ and the vertical axis is the coefficient a １ , a ２ , a ３ is.

[0092] Coefficient a of FIG. １ , a ２ , a ３ and the concentration ratio Cu / H ２ SO ４ The relationship between the coefficient k and the cubic polynomial (approximation formula, approximation curve) shown in equation (32) in FIG. 16D is approximated. ｎ１ ~k ｎ４ The coefficient k ｎ１ ~k ｎ４ can be calculated by, for example, the least squares method. The results are shown in FIG. 16E. In FIG. 16E, k ｎ１ ~k ｎ４ Wok １ ~k ４For example, in FIG. 16E, k １ is k in equation (32). １１ Corresponds to.

[0093] 17 shows a formula for determining the amount of CuO to be replenished for an arbitrary plating solution composition. First, the initial concentration ratio Cu / H ２ SO ４ : Based on x, the coefficient k in equation (32) of FIG. 16D and the coefficient k in FIG. 16E are ｎ１ ~k ｎ４ From the value of １ , a ２ , a ３ Calculate the initial Cu concentration C Ｃｕ Based on [g / L], equation (31) and coefficient a １ , a ２ , a ３ From the correction curve: t Ｈ -q is calculated. Correction curve: t Ｈ Using -q, the CuO replenishment amount (mol) can be calculated from equation (1A). In this case, the CuO replenishment amount (mol) may be calculated by integral calculation, as in the middle side of equation (1A), or, if the replenishment interval is short, the CuO replenishment amount (mol) may be calculated by calculating the area of ​​a rectangle, as in the right side of equation (1A). According to this calculation method, the correction curve: t can be calculated for a plating solution of any plating solution composition without performing a simulation for each plating composition. Ｈ -q can be obtained.

[0094] 18A to 18D show approximate curves of correction curves applicable to any plating solution composition, and the results of simulations of adjusting the ion concentration in the cathode solution using the approximate curves. These figures show that the calculation method using the approximate curves in FIG. 17 can replenish an appropriate amount of CuO and stabilize the ion concentration in the cathode solution for any plating solution composition.

[0095] (Control Example) The supply of CuO is performed by controlling the supply device 485 using the control module 800. (1) Correction curve t calculated by simulation Ｈ-q (Equation (31) in FIG. 17) is stored in a storage device, and similarly to the first embodiment, the CuO replenishment amount (mol) can be calculated from Equation (1) or (1A) according to the total charge amount q (calculated from the plating current and plating time), and CuO can be replenished to the catholyte. Note that the data set (q, t Ｈ ) may be stored in a storage device. The total charge amount q can be calculated from the plating current and plating time (time integral of the plating current, or multiplication of the plating current and plating time). (2) As in the first embodiment, the correction curve t calculated by simulation Ｈ -q area or replenishment amount (= correction curve t Ｈ The area of ​​the total charge q × (1 / 2) may be stored in the storage device for each section of the total charge q. In this case, the storage device may store the correction curve t Ｈ -q area, or replenishment amount (= correction curve t Ｈ -q area × (1 / 2)) and CuO can be replenished. Ｈ When the area of ​​-q is stored, the amount of supply can be calculated by multiplying it by 1 / 2.

[0096] Third Embodiment (Calculation of CuO Replenishment Amount When Ion Concentration is Directly Monitored) The third embodiment will be described below, focusing on differences from the first and second embodiments. Explanation of similarities with the first and second embodiments will be omitted.

[0097] 19A and 19B are explanatory diagrams illustrating a method for calculating the amount of CuO replenishment when the ion concentration in the anolyte is directly monitored, respectively, and show an example of the configuration of a plating module when the ion concentration in the anolyte is directly monitored.

[0098] 19B shows the configuration of FIG. 3 with some of the components, such as the circulation circuit, supply port, and discharge port, connected to the plating module 400, omitted. The configuration of FIG. 19B differs from the configuration of FIG. 3 in that a Cu concentration meter 416 is provided in the anode chamber Can. Other components can be the same as those of FIG. 3.

[0099] Transport number t of hydrogen ion Ｈ can be expressed by the formula (5) shown in FIG. ＋ ], Cu ion concentration [Cu ２＋ 6B. However, in FIG. 19A, in the equations (9) and (10) of FIG. 6B, equation (7) is used to calculate b and c as the Cu concentration C as shown in equations (9') and (10'). Ｃｕ Using the above-mentioned α=4, Ka'=0.25, C=1.807 (mol / L), and V=4.25 L (FIG. 9), the Cu ion concentration [Cu ２＋ ]=C Ｃｕ By detecting the hydrogen ion concentration [H ＋ ] can be calculated, and the hydrogen ion concentration [H ＋ ] and Cu ion concentration [Cu ２＋ ] to equation (5), the hydrogen ion transport number t Ｈ Then, the hydrogen ion transport number t Ｈ From this, the amount of CuO replenishment (mol) can be calculated using formula (1A).

[0100] In actual control, the formulas shown in FIG. 19A are stored in a storage device, and the Cu ion concentration [Cu ２＋ ] is detected, and the hydrogen ion concentration [H ＋ ] was calculated, and the Cu ion concentration [Cu ２＋ ] and hydrogen ion concentration [H ＋ ] into equation (5) to obtain the hydrogen ion transport number t Ｈ is calculated, and the CuO supplement amount (mol) is calculated from the formula (1A). ２＋ ] is continuously detected, and the hydrogen ion transport number t Ｈ is continuously calculated to obtain the correction curve t Ｈ -q is obtained, and the CuO replenishment amount (mol) can be calculated by integral calculation for each interval of the total charge amount q, as shown in the middle of equation (1A). ｐ , q ｃ In the hydrogen ion transport number tＨ The total charge amount q can be calculated from the plating current and plating time (time integral of the plating current, or multiplication of the plating current and plating time).

[0101] According to this calculation method, the Cu ion concentration [Cu ２＋ ]=Cu concentration C Ｃｕ By directly detecting the amount of CuO replenished (mol), the amount of CuO replenished (mol) can be calculated with higher accuracy.

[0102] In addition to detecting the Cu ion concentration, a hydrogen ion concentration meter was provided in the anolyte to measure the hydrogen ion concentration [H ＋ The hydrogen ion transport number t can be calculated from the formula (5) using the detected values ​​of the Cu ion concentration and the hydrogen ion concentration. Ｈ Then, the hydrogen ion transport number t Ｈ From this, the CuO replenishment amount (mol) can be calculated by formula (1A). According to this calculation method, by directly detecting both the Cu ion concentration and the hydrogen ion concentration during plating, the CuO replenishment amount (mol) can be calculated with higher accuracy.

[0103] In actual control, the formula (5) shown in FIG. 19A is stored in a storage device, and the Cu ion concentration [Cu ２＋ ], hydrogen ion concentration [H ＋ ] was detected, and the Cu ion concentration [Cu ２＋ ] and hydrogen ion concentration [H ＋ ] into equation (5) to obtain the hydrogen ion transport number t Ｈ The amount of CuO supplied (mol) is calculated from the formula (1A). The integral calculation or rectangular area approximation calculation using the formula (1A) can be performed in the same manner as described above.

[0104] After the concentration of Cu ions in the anolyte has decreased to below a predetermined value (after the composition of the anolyte has stabilized), the hydrogen ion transport number t ＨIt is also possible to replenish a replenishment amount of CuO corresponding to the amount of copper plated and deposited on the substrate Wf without calculating the formula (1). In this way, after the concentration of Cu ions in the anolyte falls below a predetermined value, the replenishment amount can be determined based only on the change in the total charge amount without taking into account the amount of Cu ions passing from the anolyte to the cathode solution, thereby simplifying the calculation of the replenishment amount. After the anolyte composition has stabilized, in equations (1) and (1A), CuO (mol) = (½) × (q ｃ -q ｐ ), or (1 / 2) × (q ２ -q １ In the first and second embodiments, the total charge amount q at which the concentration of Cu ions in the anolyte falls below a predetermined value is calculated in advance, and after this total charge amount, the hydrogen ion transport number t Ｈ It is also possible to replenish CuO in an amount corresponding to the amount of copper deposited on the substrate Wf without calculating the amount of CuO.

[0105] 20 shows a formula for calculating the CuO replenishment amount when plating solutions (cathode solutions) of multiple plating tanks or cells are connected and the solutions are managed collectively. Let x (x=1 to m) be the cell number, and q be the total charge amount of each cell at the time of the nth replenishment after the bath preparation. ｘ,ｎ (F), the n-th CuO replenishment amount (mol) can be expressed as in formula (1B). That is, the CuO replenishment amount (mol) for batch liquid management can be calculated as the total CuO replenishment amount (mol) obtained by adding up the CuO replenishment amounts (mol) calculated for each cell using formula (1) or (1A). This embodiment can be applied to any of the above-mentioned embodiments.

[0106] <Effect of Movement of Cations by Diffusion> Fig. 21A is a schematic diagram of the plating module with an enlarged view of the vicinity of the diaphragm 440. Fig. 21B is an explanatory diagram illustrating the movement of ions by diffusion through the diaphragm 440.

[0107] During plating, the amount of ion movement due to electrolysis is >> the amount of ion movement due to diffusion, so the effect of diffusion can be almost negligible. However, when plating is not occurring, cations move (exchange) between the anolyte and the catholyte, which can cause changes in composition. However, in the anode-diaphragm contact structure of this embodiment (FIGS. 3 and 21A), an oxygen layer 433 is formed in the gap between the lower surface of the anode 430 and the upper surface of the back plate 432. Furthermore, the anolyte Pa is not circulated and remains stationary. Therefore, the movement of ions through the diaphragm 440 due to diffusion is limited, and concentration changes due to diffusion can be almost negligible. Therefore, the amount of CuO to be replenished can be accurately calculated using the above-described simulation without considering the effect of ion movement due to diffusion.

[0108] (Other Embodiments) (1) In the above, an example of replenishing a metal oxide (for example, CuO in the case of copper) was given. However, instead of a metal oxide, a metal hydroxide (for example, Cu(OH) ２ ), metal carbonate (for example, CuCO in the case of copper) ３ (2) In the above, copper plating has been described as an example, but the metal or metal compound (oxide, hydroxide, carbonate, etc.) to be replenished may be selected appropriately depending on the metal to be plated.

[0109] At least the following aspects can be understood from the above-described embodiments: [1] According to one aspect, there is provided a plating apparatus for plating a substrate, comprising: a plating tank; a cation exchange membrane that divides the plating tank into an anode chamber that holds an anolyte and a cathode chamber that holds a catholyte; an anode disposed in the anode chamber; a replenishing device that replenishes the catholyte with the same metal as the metal to be deposited on the substrate, or a metal compound containing the metal; and a control device that controls the replenishing device to replenish the metal or the metal compound containing the replenishment amount of the metal from the replenishing device to the catholyte, the amount being obtained by subtracting the amount of metal ions of the metal that permeated from the anode chamber to the cathode chamber through the cation exchange membrane from the amount of the metal deposited by plating on the substrate.

[0110] According to this embodiment, the metal is replenished to the cathode solution in consideration of the amount of cations (metal ions) that migrate from the anode solution to the cathode solution through the cation exchange membrane. This suppresses or prevents deviations in the cathode solution composition due to excessive metal ions in the cathode solution. This suppresses or prevents deterioration of plating quality. Immediately after preparing a new plating solution (cathode solution, anode solution), the metal ion concentration in the anode solution is high, and a large amount of metal ions migrate from the anode solution to the cathode solution through the cation exchange membrane. Therefore, if the amount of metal deposited by plating is replenished to the cathode solution, excessive metal ions will be added to the cathode solution, resulting in deviations in the solution composition of the cathode solution. Therefore, it is preferable to replenish the metal to the cathode solution in consideration of the amount of metal ions that migrate through the cation exchange membrane, at least until the metal ion concentration in the anode solution falls below a predetermined value.

[0111] [2] According to one embodiment, when the total charge amount is defined as the total amount of electric charge supplied by a plating current flowing between the substrate and the anode since the time when the anolyte and the catholyte were newly prepared in the plating tank, the replenishment amount is calculated based on the area of ​​a correction curve showing the relationship between the total charge amount and the transport number of hydrogen ions permeating from the anode chamber to the cathode chamber through the cation exchange membrane.

[0112] The correction curve may be data associating the transport number of hydrogen ions with the total charge amount, or may be a mathematical formula showing the relationship between the transport number of hydrogen ions and the total charge amount. Calculation based on the area of ​​the correction curve includes integrating the area of ​​the correction curve, calculating the area using a mathematical formula for calculating the area when the area of ​​the correction curve is approximated by a rectangle, or calculating the area of ​​the correction curve by any other method.

[0113] According to this embodiment, when a current is passed through an electrolyte solution, the amount (mol) of hydrogen ions that have permeated the cation exchange membrane can be calculated using the transport number, which is the proportion of the current carried by a specific ion to the total current and is defined as the number of moles (mol) of ion per 1 F (Faraday) multiplied by the valence of the ion. Because the movement of anions through the cation exchange membrane can be ignored, the ions that carry the current that passes through the cation exchange membrane from the anolyte to the catholyte are hydrogen ions and copper ions, and therefore the sum of the transport number of hydrogen ions and the transport number of copper ions is 1, i.e., (transport number of hydrogen ions) = 1 - (transport number of copper ions). Since (1 - copper ion transport number) corresponds to twice the number of moles of copper / copper ions, which is the amount of copper deposited on the substrate per 1 F minus the amount of metal ions of the metal that permeated from the anode chamber to the cathode chamber through the cation exchange membrane, the replenishment amount (mol) can be calculated based on the area of ​​a correction curve corresponding to the value obtained by adding up 1 - copper ion transport number (= hydrogen ion transport number) for each total charge amount. For example, in the case of copper, which is a divalent ion, the replenishment amount (mol) of copper is calculated by multiplying the area of ​​the correction curve by 1 / (ion valence) = 1 / 2.

[0114] [3] According to one embodiment, the control device replenishes the replenishment amount of the metal or the metal compound containing the replenishment amount of the metal from the replenishment device to the cathode solution multiple times, and when the total charge amount changes from a first charge amount to a second charge amount, the area of ​​the correction curve is calculated as an integral value obtained by integrating the correction curve from the first charge amount to the second charge amount.

[0115] According to this aspect, by integrating the correction curve, the area of ​​the correction curve can be calculated with high accuracy.

[0116] [4] According to one embodiment, the control device replenishes the replenishment amount of the metal or the metal compound containing the replenishment amount of the metal from the replenishment device to the cathode fluid multiple times, and when the total charge amount changes from a first charge amount to a second charge amount, the area of ​​the correction curve is calculated as a value obtained by approximating the area of ​​the correction curve in the section from the first charge amount to the second charge amount using an area of ​​a rectangle.

[0117] According to this embodiment, the area of ​​the correction curve can be calculated by approximating the area of ​​a rectangle with a simple calculation. The correction curve shows the relationship between the transport number of hydrogen ions and the total charge amount. The transport number of hydrogen ions varies depending on the total charge amount. However, when a metal or metal compound is replenished at intervals where the total charge amount changes slightly, the transport number of hydrogen ions varies linearly and generally in proportion to the total charge amount (note that, after the composition of the anolyte has stabilized, the transport number of hydrogen ions does not change relative to the total charge amount). Therefore, by approximating the area of ​​the correction curve with a rectangle, the area of ​​the correction curve in the section corresponding to the change in the total charge amount can be calculated with high accuracy.

[0118] [5] According to one aspect, the area of ​​the correction curve is calculated as a value obtained by multiplying an average value of the transport number of the hydrogen ion for the first charge amount and the transport number of the hydrogen ion for the second charge amount by a difference between the second charge amount and the first charge amount.

[0119] According to this embodiment, when the correction curve changes linearly or in a section where the correction curve does not change, the area of ​​the correction curve in that section can be accurately approximated as the area of ​​a rectangle having the average value of the hydrogen ion transport numbers at both ends of the section as the dimension of one side and the change in the total charge amount as the dimension of the adjacent side.

[0120] [6] According to one embodiment, the correction curve is an approximation curve calculated using the initial concentration of the metal ions in the anolyte and a ratio between the initial concentration of the metal ions and the initial concentration of an acid, and the control device calculates an area of ​​the correction curve using the approximation curve of the correction curve, and calculates the replenishment amount based on the area.

[0121] According to this embodiment, an approximation curve of the correction curve can be obtained by simple calculation according to the composition of the plating solution, without performing a simulation to calculate a correction curve for each composition of the plating solution. Note that the initial concentration means the concentration at the time of newly preparing the plating solution in the plating tank.

[0122] [7] According to one embodiment, the device further includes a storage device that stores the correction curve calculated by simulation, and the control device refers to the correction curve in the storage device to calculate the area of ​​the correction curve, and determines the replenishment amount based on the area of ​​the correction curve.

[0123] According to this embodiment, by storing the correction curve calculated by simulation in a storage device, the replenishment amount can be calculated by simple calculation during plating, and the metal or metal compound can be replenished.

[0124] [8] According to one embodiment, the device further includes a memory device that stores data correlating the total charge amount calculated by simulation with the replenishment amount, and the control device determines the replenishment amount by referring to the data in the memory device.

[0125] According to this embodiment, the metal or metal compound can be replenished during plating with simple control.

[0126] [9] According to one embodiment, the control device replenishes the catholyte with the replenishment amount of the metal or the metal compound containing the replenishment amount of the metal based on an area of ​​the correction curve during the change, each time the total charge amount changes by a predetermined charge amount.

[0127] According to this embodiment, since the metal or metal compound is replenished every time a preset total charge amount changes, the replenishment amount corresponding to the charge amount at the replenishment timing can be calculated in advance before the plating process and stored in a storage device. Therefore, during plating, the total charge amount can be monitored, and the storage device can be referenced to determine the replenishment amount corresponding to the total charge amount, and the metal or metal compound can be replenished.

[0128]

[10] According to one embodiment, the anolyte supply system further includes a first concentration sensor that detects a concentration of metal ions in the anolyte, and the control device calculates the correction curve based on a detection value of the concentration of the metal ions detected by the first concentration sensor, and determines the replenishment amount based on an area of ​​the correction curve.

[0129] According to this embodiment, the correction curve can be calculated with higher accuracy based on the metal ion concentration in the anolyte during plating.

[0130]

[11] According to one embodiment, the anolyte replenishing system further includes a second concentration sensor that detects a concentration of hydrogen ions in the anolyte, and the control device calculates the correction curve based on the detected values ​​of the metal ion concentration and the hydrogen ion concentration detected by the first and second concentration sensors, and determines the replenishment amount based on an area of ​​the correction curve.

[0131] According to this embodiment, the correction curve can be calculated with higher accuracy based on the metal ion concentration and hydrogen ion concentration in the anolyte during plating.

[0132]

[12] According to one embodiment, the replenishment amount is calculated by dividing the area of ​​the calibration curve by the valence of the metal ion.

[0133] According to this embodiment, the amount of metal or metal compound to be replenished can be accurately calculated from the transport number of hydrogen ions, taking into account the valence of the metal ions.

[0134]

[13] According to one embodiment, the system further includes a circulation circuit connected to the cathode chamber and circulating the cathode fluid in the cathode chamber, the circulation circuit having a pump that pressure-feeds the cathode fluid, wherein the replenishing device supplies and dissolves the metal or a compound of the metal to the cathode fluid in a flow path of the circulation circuit, and the control device controls the pump to circulate the cathode fluid in the cathode chamber via the circulation circuit and controls the replenishing device to replenishing the replenishing amount of the metal or the compound of the metal from the replenishing device to the cathode fluid in the flow path of the circulation circuit.

[0135] According to this embodiment, since the replenishing device is disposed in the flow path of the circulation circuit of the cathode solution, it is possible to avoid making the configuration of the plating tank complicated. When a reservoir tank and / or a plating solution adjustment tank is provided in the circulation circuit, for example, a replenishing device may be provided in the reservoir tank and / or the plating solution adjustment tank to supply and dissolve metal or metal ions in the cathode solution in the reservoir tank and / or the plating solution adjustment tank.

[0136]

[14] According to one aspect, the control device supplies the pure water to the anode chamber in response to detecting that the amount of the anolyte has fallen below a predetermined lower limit.

[0137] According to this configuration, the amount of the anode fluid can be controlled to be equal to or greater than a lower limit without circulating the anode fluid, making it easier to control the amount of the anode fluid. The amount of the anode fluid can be controlled, for example, by detecting the anode fluid level using a level sensor in a gas exhaust passage leading to the anode chamber. Maintaining the amount of the anode fluid equal to or greater than the lower limit can prevent the anode fluid from running out. When a configuration is adopted in which the anode is in close contact with the underside of the ion exchange membrane, controlling the anode fluid level to be equal to or greater than a lower limit that is higher than the cathode fluid level can increase the pressure of the anode fluid higher than the pressure of the cathode fluid, pressing the anode against the ion exchange membrane from the anode fluid side and improving the contact between the anode and the ion exchange membrane.

[0138]

[15] According to one aspect, the control device discharges the anolyte from the anode chamber in response to detecting that the amount of the anolyte has exceeded a predetermined upper limit.

[0139] According to this embodiment, it is possible to prevent the anode fluid from overflowing from the plating tank and being discharged to the outside (for example, into an overflow tank), thereby suppressing or preventing a decrease in the concentration of additives in the cathode fluid and deterioration in the cathode fluid in a configuration in which the anode fluid is circulated from the overflow tank to the cathode chamber.

[0140]

[16] According to one embodiment, the anode is in close contact with the lower surface of the ion exchange membrane.

[0141] According to this embodiment, it is possible to suppress or prevent gas (for example, oxygen) generated at the anode from accumulating between the ion exchange membrane and the anode and adversely affecting the plating current.

[0142]

[17] According to one embodiment, the device further comprises a back plate spaced a predetermined distance from the lower surface of the anode.

[0143] According to this configuration, the amount of gas (oxygen) generated at the anode and accumulated on the lower surface of the anode can be adjusted by the back plate. This suppresses or prevents a large amount of gas from being released from the lower surface of the anode at once, which causes fluctuations in the anode voltage and reduces plating quality. In addition, because the entire lower surface of the anode can be stably covered with a gas layer, the amount of ions diffusing from the anolyte through the diaphragm to the catholyte can be suppressed, eliminating the need to consider ion movement due to diffusion in calculating the hydrogen ion transport number.

[0144]

[18] According to one embodiment, after the concentration of the metal ions in the anolyte has fallen below a predetermined value, the control device supplies a replenishment amount of the metal, or the metal compound containing the replenishment amount of the metal, to the catholyte from the replenishment device, the replenishment amount corresponding to the amount of the metal deposited by plating on the substrate.

[0145] According to this embodiment, once the concentration of metal ions in the anolyte has fallen below a predetermined value, the replenishment amount can be determined based solely on the change in the total charge amount without taking into account the amount of metal ions that have passed from the anolyte to the catholyte, thereby simplifying the calculation of the replenishment amount.

[0146]

[19] According to one embodiment, when the anolyte and the catholyte are newly prepared in the plating tank, the plating tank holds the anolyte and the catholyte having the same composition.

[0147] According to this embodiment, since a common plating solution is supplied to the anode chamber and the cathode chamber, there is no need to provide separate supply sources (reservoirs), pumps, etc. for the anode fluid and the cathode fluid, and the supply sources (e.g., reservoirs), pumps, etc. can be shared for the anode fluid and the cathode fluid.

[0148]

[20] According to one embodiment, there is provided a plating method for plating a substrate, comprising: supplying a cathode solution with a replenishment amount of the metal, or a compound of the metal containing the replenishment amount of the metal, the amount being obtained by subtracting the amount of metal ions of the metal that have permeated from the anode chamber to the cathode chamber through an ion exchange membrane that separates the anode chamber and the cathode chamber in a plating tank from the amount of metal deposited on the substrate.

[0149] Although the embodiments of the present invention have been described above, the above-described embodiments are intended to facilitate 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 its spirit, and the present invention naturally includes equivalents thereof. Furthermore, any combination of the embodiments and modifications is possible within the scope of solving at least part of the above-described problems or achieving at least part of the effects, and any combination or omission of the components described in the claims and specification is possible. The specifications, drawings, and abstracts of Japanese Patent No. 6,767,243 (Patent Document 1) and Japanese Patent No. 7,165,843 (Patent Document 2) are incorporated herein by reference in their entirety.

[0150] REFERENCE SIGNS LIST 11 substrate holder 400 plating module 410 plating tank 411, 412 supply port 413, 414 discharge port 415 liquid level sensor 416 Cu concentration meter 417 exhaust passage 420 overflow tank 430 anode 431 anode mask 432 back plate 433 oxygen layer 440 diaphragm 450 resistor 470 circulation circuit 471, 472, 473 fluid line 474 pure water supply line 475, 476 pump 477, 478, 479, 480 valve 481 reservoir tank 482 plating solution adjustment tank 483 agitator 485 replenisher 100 load port 110 transport robot 120 aligner 200 pre-wet module 300 pre-soak module 400 Plating module 500 Cleaning module 600 Spin rinse dryer 700 Transfer device 800 Control module 1000 Plating device

Claims

1. A plating apparatus for plating substrates, comprising: a plating tank; a cation exchange membrane that separates the plating tank into an anode chamber that holds an anolyte and a cathode chamber that holds a catholyte; an anode disposed in the anode chamber; a replenishing device that replenishes the catholyte with the same metal as the metal that will be deposited on the substrate, or a metal compound containing the metal; and a control device that controls the replenishing device to replenish the catholyte with a replenishment amount of the metal, or the metal compound containing the replenishment amount of the metal, from the replenishing device to the catholyte, the amount being obtained by subtracting the amount of metal ions of the metal that have permeated from the anode chamber to the cathode chamber through the cation exchange membrane from the amount of the metal deposited on the substrate.

2. A plating apparatus according to claim 1, wherein, when the total charge amount is defined as the total amount of charge supplied by the plating current flowing between the substrate and the anode since the time when the anolyte and the catholyte were newly prepared in the plating tank, the replenishment amount is calculated based on the area of ​​a correction curve showing the relationship between the transport number of hydrogen ions permeating from the anode chamber to the cathode chamber through the cation exchange membrane and the total charge amount.

3. A plating apparatus according to claim 2, wherein the control device supplies the replenishment amount of the metal or the metal compound containing the replenishment amount of the metal from the replenishment device to the cathode solution multiple times, and when the total charge amount changes from a first charge amount to a second charge amount, the area of ​​the correction curve is calculated as an integral value obtained by integrating the correction curve from the first charge amount to the second charge amount.

4. A plating apparatus according to claim 2, wherein the control device supplies the replenishment amount of the metal or the metal compound containing the replenishment amount of the metal from the replenishment device to the cathode solution multiple times, and when the total charge amount changes from a first charge amount to a second charge amount, the area of ​​the correction curve is calculated as a value obtained by approximating the area of ​​the correction curve in the section from the first charge amount to the second charge amount using the area of ​​a rectangle.

5. A plating apparatus according to claim 4, wherein the area of ​​the correction curve is calculated as a value obtained by multiplying the average value of the transport number of the hydrogen ion for the first charge amount and the transport number of the hydrogen ion for the second charge amount by the difference between the second charge amount and the first charge amount.

6. A plating apparatus according to claim 2, wherein the correction curve is an approximation curve calculated using the initial concentration of the metal ions in the anolyte and the ratio of the initial concentration of the metal ions to the initial concentration of the acid, and the control device calculates the area of ​​the correction curve using the approximation curve of the correction curve, and calculates the replenishment amount based on the area.

7. A plating apparatus according to claim 2, further comprising a storage device for storing the correction curve calculated by simulation, wherein the control device refers to the correction curve in the storage device, calculates the area of ​​the correction curve, and determines the replenishment amount based on the area of ​​the correction curve.

8. A plating apparatus according to claim 2, further comprising a memory device that stores data correlating the total charge amount calculated by simulation with the replenishment amount, and the control device determines the replenishment amount by referring to the data in the memory device.

9. A plating apparatus according to claim 2, wherein the control device replenishes the cathode solution with the replenishment amount of the metal or the metal compound containing the replenishment amount of the metal based on the area of ​​the correction curve during the change each time the total charge amount changes by a predetermined charge amount.

10. A plating apparatus according to claim 2, further comprising a first concentration sensor for detecting the concentration of metal ions in the anolyte, wherein the control device calculates the correction curve based on the detected value of the metal ion concentration detected by the first concentration sensor, and determines the replenishment amount based on the area of ​​the correction curve.

11. A plating apparatus according to claim 5, further comprising a second concentration sensor for detecting the concentration of hydrogen ions in the anode solution, wherein the control device calculates the correction curve based on the detected values ​​of the metal ion concentration and the hydrogen ion concentration detected by the first and second concentration sensors, and determines the replenishment amount based on the area of ​​the correction curve.

12. The plating apparatus according to claim 2, wherein the replenishment amount is calculated by dividing the area of ​​the correction curve by the valence of the metal ions.

13. A plating apparatus according to any one of claims 1 to 12, further comprising a circulation circuit connected to the cathode chamber for circulating the cathode fluid within the cathode chamber, the circulation circuit having a pump for pressure-feeding the cathode fluid, wherein the replenishing device supplies and dissolves the metal or a compound of the metal in the cathode fluid within the flow path of the circulation circuit, and the control device controls the pump to circulate the cathode fluid within the cathode chamber via the circulation circuit and also controls the replenishing device to replenishing the replenishing amount of the metal or the compound of the metal from the replenishing device to the cathode fluid within the flow path of the circulation circuit.

14. A plating apparatus according to any one of claims 1 to 12, wherein the control device supplies the pure water to the anode chamber in response to detecting that the amount of the anolyte has fallen below a predetermined lower limit.

15. A plating apparatus according to any one of claims 1 to 12, wherein the control device discharges the anolyte from the anode chamber in response to detecting that the amount of the anolyte has exceeded a predetermined upper limit.

16. A plating apparatus according to any one of claims 1 to 12, wherein the anode is in close contact with the lower surface of the ion exchange membrane.

17. The plating apparatus according to claim 14, further comprising a back plate spaced a predetermined distance from the lower surface of said anode.

18. A plating apparatus according to any one of claims 1 to 12, wherein the control device, after the concentration of the metal ions in the anolyte has fallen below a predetermined value, supplies the catholyte with a replenishment amount of the metal, or the metal compound containing the replenishment amount of the metal, from the replenishment device, which amount corresponds to the amount of the metal deposited by plating on the substrate.

19. A plating apparatus according to any one of claims 1 to 12, wherein when the anolyte and the catholyte are newly prepared in the plating tank, the plating tank holds the anolyte and the catholyte of the same composition.

20. A plating method for plating a substrate, comprising: supplying a replenishment amount of the metal, or a compound of the metal containing the replenishment amount of the metal, to a cathode solution, the amount being calculated by subtracting the amount of metal ions of the metal that have permeated from the anode chamber to the cathode chamber through an ion exchange membrane that separates the anode chamber and the cathode chamber in a plating tank from the amount of metal deposited on the substrate.

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