Foil forming apparatus and foil forming method for forming a metal foil

Abstract

Foil forming device (1) for forming a metal foil (M), comprising: an anode (2); a solid electrolyte membrane (6) arranged between the anode (2) and a substrate serving as a cathode (4); a current supply device (8) which applies a voltage between the anode (2) and the cathode (4); a solution container (12) containing a solution (L) between the anode (2) and the solid electrolyte membrane (6), the solution (L) containing metal ions; and a pressure device (30b) which pressurizes the solid electrolyte membrane (6) towards the cathode side with a fluid pressure of the solution (L), wherein a metal foil (M) is formed on a foil forming region by applying the voltage while the foil forming region is pressurized on a surface of the substrate (4r) through the solid electrolyte membrane (6) to deposit the metal ions contained in the solid electrolyte membrane (6), and wherein the film forming apparatus (1) further includes an auxiliary cathode (14) arranged in a peripheral region of the film forming region when the surface of the substrate (4s) is viewed in plan view, wherein an electric potential of the auxiliary cathode (14) is lower than an electric potential of the anode (2), wherein when the distance from the center (Q) to the outer periphery (B) of the film forming region (4r) on the surface (4s) of the substrate is set to 1 as a standard value of a relative value, a relative value of the distance from the center (P) to the outer circumference (A) on the surface (2s) of the anode (2) is 0.95 to 1.09, a relative value of the distance from the outer circumference (B) of the film forming region (4r) to the inner circumference (C) of the surface (14s) of the auxiliary cathode (14) is 0 to 0.2, a relative value of the distance from the inner periphery (C) to the outer periphery (D) on the surface (14s) of the auxiliary cathode (14) is 0.05 to 0.17, and a relative value of the distance from the center (P) on the surface (2s) of the anode (2) to the center (Q) of the film forming region (4r) is 0.15 to 0.32.

Description

BACKGROUNDDescription of the prior art

[0001] The present invention relates to a film forming apparatus and a film forming method for forming a metal foil, and more particularly to a film forming apparatus and a film forming method for forming a metal foil which enable the metal foil to be formed on a surface of a substrate. State of the art

[0002] Conventionally, a film forming apparatus and a film forming method in which metal ions are deposited to form a metal foil are known. For example, JP 2014-51701 A proposes a film forming apparatus and a metal foil forming method using the apparatus. The film forming apparatus includes an anode, a solid electrolyte membrane disposed between the anode and a substrate serving as a cathode, a power supply device that applies a voltage between the anode and the cathode, a solution container containing a solution containing metal ions between the anode and the solid electrolyte membrane, and a pressure device that pressurizes the solid electrolyte membrane toward the cathode side with a fluid pressure of the solution. The solid electrolyte membrane is arranged to close an opening on the cathode side of the solution container.

[0003] When a metal foil is formed on a surface of a substrate by this film forming method for forming a metal foil, the solid electrolyte membrane is brought into contact with the surface of the substrate, and then the metal ions contained in the solid electrolyte membrane are deposited by applying a voltage while the surface of the substrate is pressurized with a fluid pressure of a solution through the solid electrolyte membrane, thereby forming the metal foil on the surface of the substrate.

[0004] Furthermore, the published patent applications JP 2003 - 129 294 A, EP 0 745 702 A1 and JP H07 - 188 975 A disclose prior art film forming processes. SUMMARY

[0005] In conventional foil forming apparatus and methods for forming a metal foil, when forming a metal foil on the substrate surface, the lines of electric force from the anode are locally concentrated in a peripheral edge portion of a foil forming region on the substrate surface, and a current is concentrated at the peripheral edge portion of the foil forming region, potentially causing current density variations in the foil forming region. As a result, metal ions excessively deposit on the peripheral edge portion of the foil forming region on the substrate surface, and the thickness of the metal foil increases, potentially failing to form a metal foil with a uniform foil thickness.

[0006] The present invention has been provided in view of such a situation and comprises a film forming apparatus and a film forming method for producing a metal foil, which enable the metal foil to be formed with a uniform film thickness.

[0007] To solve the above problem, a film forming apparatus for forming a metal foil of the present invention comprises an anode, a solid electrolyte membrane, a power supply device, a solution tank, and a pressure device. The solid electrolyte membrane is disposed between the anode and a substrate serving as a cathode. The power supply device applies a voltage between the anode and the cathode. The solution tank contains a solution between the anode and the solid electrolyte membrane. The solution contains metal ions. The pressure device pressurizes the solid electrolyte membrane toward the cathode side with a fluid pressure of the solution. A metal foil is formed on a film forming region by applying the voltage while the film forming region is pressurized in a surface of the substrate through the solid electrolyte membrane to deposit the metal ions contained in the solid electrolyte membrane.The film forming apparatus further includes an auxiliary cathode disposed in a peripheral region of the film forming area when the substrate surface is viewed from above. An electric potential of the auxiliary cathode is lower than an electric potential of the anode.When the distance from the center to the outer periphery of the film formation region on the surface of the substrate is set to 1 as a default value of a relative value, a relative value of the distance from the center to the outer periphery on the surface of the anode is 0.95 to 1.09, a relative value of the distance from the outer periphery of the film formation region to the inner periphery of the surface of the auxiliary cathode is 0 to 0.2, a relative value of the distance from the inner periphery to the outer periphery on the surface of the auxiliary cathode is 0.05 to 0.17, and a relative value of the distance from the center on the surface of the anode to the center of the film formation region is 0.15 to 0.32.

[0008] With the film forming apparatus for forming a metal film according to the present invention, the metal film can be formed with a uniform film thickness.

[0009] Furthermore, a film forming method for forming a metal foil of the present invention using the above-mentioned film forming apparatus for forming a metal foil comprises disposing a solid electrolyte membrane between an anode and a substrate serving as a cathode, wherein a metal foil is formed on a film forming region by applying a voltage between the anode and the cathode, while the film forming region on a surface of the substrate is pressurized through the solid electrolyte membrane with a fluid pressure of a solution to deposit metal ions contained in the solid electrolyte membrane. The solution is disposed between the anode and the solid electrolyte membrane. The solution contains the metal ions.The metal foil is formed by applying the voltage in a state where an auxiliary cathode whose electric potential is lower than an electric potential of the anode is arranged in a peripheral region of the foil forming region when the surface of the substrate is viewed in plan view.

[0010] With the foil forming method for forming a metal foil of the present invention, the metal foil can be formed with a uniform foil thickness. EFFECT

[0011] With the present invention, the metal foil can be formed with a uniform foil thickness. SHORT DESCRIPTION OF THE DRAWING Fig. 1 is a schematic perspective view illustrating a foil forming apparatus for forming a metal foil according to a first embodiment; Fig. 2A is a schematic process cross-sectional view illustrating a foil forming method for forming a metal foil according to the first embodiment; Fig. 2B is a schematic process cross-sectional view illustrating the foil forming method for forming a metal foil according to the first embodiment; Fig. 2C is a schematic process cross-sectional view illustrating the foil forming method for forming a metal foil according to the first embodiment; Fig. 3 is a schematic plan view when a surface of a substrate and a surface of an auxiliary cathode of the Fig. 1 shown in plan view, and is a drawing illustrating a shape of an anode by a dashed line; Fig. 4 is a cross-sectional view schematically illustrating an example of dimensions and a position of an anode, a film forming region on the surface of the substrate, and the auxiliary cathode in film formation by a film forming apparatus for forming a metal film according to the first embodiment; Fig. 5A is a diagram illustrating a current density distribution in the film forming region and on the surface of the auxiliary cathode analyzed for cases where a PA pitch, a BC pitch, a CD pitch, and a PQ pitch are varied to relative values ​​under predetermined conditions in the film forming apparatus for forming a metal film according to the first embodiment; Fig. 5B is a graph showing a current density change from the center of the film formation region to the surface of the auxiliary cathode in a direction (an evaluation direction) parallel to a side of the Fig. 5A illustrates the film formation region; Fig. Figure 6 is a drawing illustrating four graphs showing respective current density variations for the PA distance, the BC distance, the CD distance, and the PQ distance obtained from analyses using the response surface methodology; Fig. Figure 7 is a contour map illustrating the current density variation for the PA distance (X) and the BC distance (Y) obtained from an analysis using the response surface methodology; Fig. 8A is a cross-sectional view schematically illustrating another example of dimensions and a positional relationship of an anode, a substrate, and an auxiliary cathode of a film forming apparatus for forming a metal film in forming the metal film; Fig. 8B is a cross-sectional view schematically illustrating another example of dimensions and a positional relationship of an anode, a substrate, and an auxiliary cathode of a film forming apparatus for forming a metal film in forming the metal film; Fig. 9 is a schematic cross-sectional view illustrating a state of film formation by a film forming apparatus for forming a metal foil according to a second embodiment; and Fig. 10 is a schematic cross-sectional view illustrating a state of film formation by a film forming apparatus for forming a metal foil according to a third embodiment. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0012] Embodiments of a film forming apparatus and a film forming method for forming a metal foil according to the present invention will be described below.

[0013] First, the embodiment will be schematically described using as examples a film forming apparatus and a film forming method for forming a metal film according to a first embodiment. Fig. 1 is a schematic perspective view illustrating the film forming apparatus for forming a metal film according to the first embodiment. Fig. 2A to Fig. 2C are schematic process cross-sectional views illustrating the foil forming method for forming a metal foil according to the first embodiment, and Fig. Figure 2A illustrates a schematic cross-sectional area of ​​a main component including a solution container and a substrate of the Fig. 1 shown film forming device. Fig. 3 is a schematic plan view when a surface of the substrate of the film forming apparatus and a surface of a Fig. 1 shown auxiliary cathode in plan view, and is a drawing illustrating a shape of an anode by a dashed line.

[0014] As in Fig. 1 and Fig. 2A, a film forming apparatus 1 for forming a metal film according to the first embodiment includes an anode 2, a solid electrolyte membrane 6, a power supply device 8, a solution tank 12, and a pump (pressure device) 30b. The solid electrolyte membrane 6 is disposed between the anode 2 and a substrate 4 serving as a cathode. The power supply device 8 applies a voltage between the anode 2 and the substrate (cathode) 4. The solution tank 12 contains a metal ion-containing solution (hereinafter referred to as a "metal ion solution" in some cases) L between the anode 2 and the solid electrolyte membrane 6. The pump (pressure device) 30b pressurizes the solid electrolyte membrane 6 toward the cathode side with a fluid pressure of the metal ion solution L. In the first embodiment, an entire surface 4s of the substrate 4 serves as the film forming region 4r.The film forming apparatus 1 for forming a metal film further includes an auxiliary cathode 14 which is arranged in a frame shape in a peripheral region of the film forming region 4r when viewed from above on the surface 4s of the substrate 4.

[0015] The anode 2 is arranged on an upper surface 12a within the solution tank 12, is housed within the solution tank 12 so as to be in contact with the metal ion solution L, and is electrically connected to the power supply device 8 via a wiring 10. A surface 2s of the anode 2 is parallel to an end surface 6s on the cathode side of the solid electrolyte membrane 6, and the surface 4s of the substrate 4 and a surface 14s of the auxiliary cathode 14. The substrate 4 and the auxiliary cathode 14 are respectively embedded in a central groove 20ch and a peripheral edge groove 20ph of a base 20, so that the surface 4s of the substrate 4, the surface 14s of the auxiliary cathode 14, and a surface 20s of the base 20 are flush with each other. A free space S is provided between the substrate 4 and the auxiliary cathode 14. As in Fig. 3, the anode 2, in the plan view of the surface 4s of the substrate 4 and the surface 14s of the auxiliary cathode 14, has a rectangular shape similar to the film formation region 4r of the substrate 4, and the anode 2 has a slightly larger size than the film formation region 4r. The surface 2s of the anode 2 has a center P corresponding to a center Q of the film formation region 4r of the substrate 4, and the surface 2s of the anode 2 has a side parallel to a side corresponding to the film formation region 4r of the substrate 4. The surface 14s of the auxiliary cathode 14 has an inner periphery C and an outer periphery D, whose shapes are rectangular, similar to the film formation region 4r of the substrate 4. The inner periphery C of the surface 14s of the auxiliary cathode 14 has a slightly larger dimension than that of the anode 2.The center of the inner circumference C and the center of the outer circumference D of the auxiliary cathode 14 correspond to the center Q of the film formation region 4r of the substrate 4. One side of the inner circumference C of the auxiliary cathode 14 and one side of the outer circumference D are parallel to a corresponding side of the film formation region 4r of the substrate 4.

[0016] In the Fig. 1 and Fig. In the film forming apparatus 1 for forming a metal film illustrated in FIG. 2A, the substrate (cathode) 4 and the auxiliary cathode 14 are electrically connected to the power supply device 8 via the wiring 10 in a similar manner. The solution tank 12 is provided with an opening 12h on the cathode side. The solid electrolyte membrane 6 is arranged to cover the opening 12h of the solution tank 12. The power supply device 8 is electrically connected to a control device 50 and can receive control signals from the control device 50 to control the voltage between the anode 2 and the substrate 4. The base 20 is formed of a material having an insulating property and chemical resistance to the metal ion solution.

[0017] In the Fig. In the film forming apparatus 1 for forming a metal film illustrated in FIG. 1, a solution tank 30 containing the metal ion solution L is connected to one side of the solution tank 12 via a supply pipe 30a, and a pump (pressure device) 30b is arranged on the supply pipe 30a. A residual liquid tank 40 collecting a residual liquid of the metal ion solution L after film formation is connected to the other side of the solution tank 12 via a residual liquid line 40a, and an on-off valve 40b is arranged on the residual liquid line 40a. The pump 30b and the on-off valve 40b are electrically connected to the control device 50 and can receive control signals from the control device 50 to control their operations. This configuration of the film forming apparatus 1 makes it possible to make the interior of the solution container 12 into a closed space containing the metal ion solution L by closing the on-off valve 40b.The drive of the pump 30b allows the metal ion solution L to be supplied from the solution tank 30 to the enclosed space via the supply pipe 30a, whereby the fluid pressure of the metal ion solution L contained in the enclosed space can be adjusted to a desired value. By opening the on-off valve 40b, the waste liquid of the metal ion solution L after film formation can be fed into the residual liquid tank 40 via the residual liquid line 40a.

[0018] Furthermore, in the film forming apparatus 1 for forming a metal film, a movable device 52 is connected to an upper portion of the solution tank 12. The movable device 52 moves the solution tank 12 together with the solid electrolyte membrane 6 toward the substrate 4, thereby bringing the solid electrolyte membrane 6 into contact with the film forming region 4r on or in the surface 4s of the substrate 4. The movable device 52 is electrically connected to the control device 50 and can receive a signal from the control device 50 to control the process.

[0019] A pressure gauge 54 is arranged to measure the fluid pressure of the metal ion solution L contained in the closed space within the solution container 12. The pressure gauge 54 is electrically connected to the control unit 50 and can output a fluid pressure value of the metal ion solution L measured by the pressure gauge 54 as a signal.

[0020] The control unit 50 is electrically connected to the power supply device 8, the pump 30b, the on-off valve 40b, the movable device 52, and the pressure gauge 54. The control unit 50 can output control signals to control the power supply device 8, the pump 30b, the on-off valve 40b, and the movable device 52, and can receive the fluid pressure value output as the signal from the pressure gauge 54.

[0021] In the film forming method for forming a metal film according to the first embodiment, the film forming apparatus 1 for forming a metal film is used to form a metal film M at the film forming region 4r on the surface 4s of the substrate 4. The process will be described below.

[0022] First, as in Fig. 1, Fig. 2A and Fig. 3, so that a flush surface is formed with the surface 4s of the substrate 4, the surface 14s of the auxiliary cathode 14, and the surface 20s of the base 20, the substrate 4 and the auxiliary cathode 14 are embedded in the central groove 20ch and the peripheral edge groove 20ph of the base 20, respectively, to electrically connect the power supply device 8 to the substrate 4 and the auxiliary cathode 14. The solid electrolyte membrane 6 is arranged between the anode 2 and the substrate 4 serving as the cathode and auxiliary cathode 14. At the same time, an alignment of the substrate 4 with respect to the anode 2 is adjusted. This causes the surface 2s of the anode 2 to be parallel to the surface 4s of the substrate 4 and to the surface 14s of the auxiliary cathode 14. As shown in Fig. 3, when the surface 4s of the substrate 4 and the surface 14s of the auxiliary cathode 14 are viewed from above, the center P of the surface 2s of the anode 2 corresponds to the center Q of the film formation region 4r of the substrate 4, the side of the surface 2s of the anode 2 becomes parallel to the corresponding side of the film formation region 4r of the substrate 4, and the outer periphery A of the surface 2s of the anode 2 is arranged between the substrate 4 and the auxiliary cathode 14.

[0023] Then, when the movable device 52 is driven by the control signal of the control device 50, as shown in Fig. 2B, the solid electrolyte membrane 6 moves toward the substrate 4 together with the solution container 12. Thus, while maintaining a position between the anode 2, the substrate 4, and the auxiliary cathode 14 in plan view, the end surface 6s on the cathode side of the solid electrolyte membrane 6 is brought into contact with the film formation region 4r of the surface 4s of the substrate 4 and the surface 14s of the auxiliary cathode 14.

[0024] Next, the on-off valve 40b is closed by the input signal from the control device 50, whereby the interior of the solution container 12 becomes a closed space containing the metal ion solution L. Subsequently, in this state, the pump 30b is driven by the input signal from the control device 50, whereby the metal ion solution L is supplied from the solution container 30 to the closed space via the supply pipe 30a, thereby controlling the fluid pressure of the metal ion solution L contained in the closed space, which is measured by the pressure gauge 54, to a desired value. Furthermore, the power supply device 8 is controlled by inputting the control signal from the control device 50 to apply a voltage between the anode 2, the substrate 4, and the auxiliary cathode 14 and adjust this voltage to a desired value. Thus, as shown in Fig. 2C illustrates that while the film formation region 4r on the surface 4s of the substrate 4 is pressurized by the solid electrolyte membrane 6 with the fluid pressure of the metal ion solution L containing metal ions, which is disposed between the anode 2 and the solid electrolyte membrane 6, a voltage is applied between the anode 2 and the substrate 4 and the auxiliary cathode 14 so that the auxiliary cathode 14 is at the same potential as that of the substrate (the cathode) 4 to deposit the metal ions contained in the solid electrolyte membrane 6. Accordingly, the metal foil M is formed on the film formation region 4r on the surface 4s of the substrate 4.

[0025] Accordingly, in the film forming apparatus and the film forming method for forming a metal film according to the first embodiment, in order to form the metal foil M in the film forming region 4r of the surface 4s of the substrate (the cathode) 4, when applying the voltage between the anode 2 and the substrate 4, while the auxiliary cathode 14 is arranged in the peripheral region of the film forming region 4r when the surface 4s of the substrate 4 is viewed in plan view, a voltage is applied between the anode 2 and the substrate 4 and the auxiliary cathode 14 so that the auxiliary cathode 14 is at the same potential as that of the substrate (the cathode) 4.In view of this, electric force lines traveling from the anode 2 without the auxiliary cathode 14 toward a peripheral edge portion of the film formation region 4r of the surface 4s of the substrate 4 are caused to travel toward the auxiliary cathode 14 in the peripheral region of the film formation region 4r, thereby enabling suppressed concentration of a current on the peripheral edge portion of the film formation region 4r of the surface 4s of the substrate 4. Since the current density variation in the film formation region 4r at the surface 4s of the substrate 4 can be suppressed, the metal foil M can be formed with a uniform foil thickness.

[0026] Accordingly, with the film forming apparatus and the film forming method for forming a metal film according to the embodiment, as in the first embodiment, the concentration of the current on the peripheral edge portion of the film forming region on the surface of the substrate can be suppressed, thereby enabling the formation of the metal film with a uniform film thickness.

[0027] Next, the configurations of the film forming apparatus and the film forming method for forming a metal film according to the embodiment will be described in detail. 1. Auxiliary cathode

[0028] The auxiliary cathode is arranged in the peripheral region of the aforementioned film formation region when viewed from above, and has an electric potential lower than that of the aforementioned anode. The auxiliary cathode has electrical conductivity that allows the concentration of current to be suppressed at the peripheral edge portion of the film formation region on the substrate surface, and has, for example, chemical resistance to the solution containing metal ions.

[0029] While the aforementioned auxiliary cathode is not particularly limited as long as it is a conductive material and its electric potential is lower than that of the anode, in some embodiments, it is at the same potential as the aforementioned cathode as the auxiliary cathode according to the first embodiment. This is because the concentration of the current on the peripheral edge portion of the film formation region on the surface of the substrate serving as the cathode can be effectively suppressed. This is also because the application of the electric potential to the substrate and the auxiliary cathode is facilitated. Note that if the auxiliary cathode is brought to the same potential as that of the cathode, the cathode and the auxiliary cathode can be grounded.

[0030] While the shape of the auxiliary cathode is not particularly limited, the surface of the auxiliary cathode according to the auxiliary cathode of the first embodiment is parallel to the surface of the anode in some embodiments. While the plan view shape and plan view size of the auxiliary cathode are not particularly limited, they generally correspond to the shape and size of the film formation region on the surface of the substrate. Examples of such a shape and size include, for example, one having a rectangular frame-shaped forming shape in plan view when the film formation region on the surface of the substrate has a rectangular shape in plan view, like the auxiliary cathode according to the first embodiment.

[0031] While the material of the auxiliary cathode is not particularly limited as long as it has electrical conductivity that allows suppressing the concentration of current to the peripheral edge portion of the film forming region on the surface of the substrate, metal such as aluminum is included as an example. 2. Anode

[0032] Although the anode is not particularly limited as long as it has an electrical conductivity that can be operated as an anode, it is, for example, one that has chemical resistance to the solution containing the metal ions.

[0033] While the shape of the anode is not particularly limited, in some embodiments, the surface of the anode is parallel to the end surface on the cathode side of the solid electrolyte, like the anode according to the first embodiment. While the plan view shape and plan view size of the anode are not particularly limited, they generally correspond to the plan view shape and plan view size of the film formation region on the surface of the substrate. This is because the electric force lines from the anode to the film formation region can be made uniform, enabling the formation of a metal foil with excellent film thickness uniformity.Examples of such a shape and size include a shape having a similar shape in plan view to the film formation region on the surface of the substrate as the anode according to the first embodiment, and a size slightly smaller or slightly larger in plan view than the film formation region on the surface of the substrate, and a shape having the same shape and size in plan view as the film formation region on the surface of the substrate.

[0034] While the anode material is not particularly limited, the anode material may include a metal with a low ionization tendency compared to the metal containing the metal ions (high standard electrode potential compared to the metal containing the metal ions), a metal that is more noble than the metal containing the metal ions, and the like. This metal includes, for example, gold. 3. Solid electrolyte membrane

[0035] The solid electrolyte membrane is arranged between the anode and the substrate, which serves as the cathode.

[0036] The solid electrolyte membrane contains a solid electrolyte. The solid electrolyte membrane contains metal ions through contact with the metal ion-containing solution, and the metal ions contained within the solid electrolyte membrane are deposited on the surface of the substrate by applying a voltage between the anode and the cathode. While the solid electrolyte membrane is not particularly limited as long as it is one as described above, the solid electrolyte membrane includes a fluorine-based resin such as Nafion (registered trademark) manufactured by DuPont, a hydrocarbon resin, a polyamide acid membrane, a membrane with ion exchange function such as Selemion (CMV, CMD, CMF, and the like) manufactured by AGC Inc., and the like. 4. Solution container

[0037] The solution container contains the solution containing the metal ions (in some cases referred to as “metal ion solution”) between the anode and the solid electrolyte membrane.

[0038] While the material of the solution container is not particularly limited as long as the metal ion solution can be contained between the anode and the solid electrolyte membrane, the material of the solution container has chemical resistance to the metal ion solution and can shield the lines of electric force in some embodiments.

[0039] A metal ion solution is a solution containing the metal contained in the metal foil in the state of metal ions. Although the metal ions are not particularly limited, they include copper, nickel, silver, gold, and the like. The metal ion solution is obtained by dissolving the metal ions with an acid such as nitric acid, phosphoric acid, succinic acid, nickel sulfate, and pyrophosphoric acid. 5. Further

[0040] The current supply device applies the voltage between the anode and the cathode. The pressure device pressurizes the solid electrolyte membrane toward the cathode side using the fluid pressure of the solution.

[0041] Although the pressure device is not particularly limited, the pressure device includes, for example, a pump that supplies the metal ion solution to the inside of the solution tank, adjusts the fluid pressure of the metal ion solution inside the solution tank, and pressurizes the solid electrolyte membrane toward the cathode side with the fluid pressure of the metal ion solution, like the pressure device according to the first embodiment. 6. Foil forming device for forming metal foils

[0042] A film forming apparatus for forming a metal film includes an anode, a solid electrolyte membrane, a power supply device, a solution tank, and a pressure device. The solid electrolyte membrane is disposed between the anode and a substrate serving as the cathode. The power supply device applies a voltage between the anode and the cathode. The solution tank contains a solution between the anode and the solid electrolyte membrane. The solution contains metal ions. The pressure device pressurizes the solid electrolyte membrane toward the cathode side with a fluid pressure of the solution. A metal film is formed on a film forming region by applying the voltage while the film forming region is pressed onto the surface of the substrate through the solid electrolyte membrane to deposit the metal ions contained in the solid electrolyte membrane.The film forming apparatus for forming a metal film further includes an auxiliary cathode disposed in a peripheral region of the film forming region when a surface of the substrate is viewed in plan view. The auxiliary cathode has an electric potential lower than an electric potential of the anode.

[0043] Note that "the film formation region on the surface of the substrate" refers to a region where the metal foil is formed on the surface of the substrate. The film formation region on the surface of the substrate may be the entire surface of the substrate, as in the first embodiment, or a part of the surface of the substrate, as in a second embodiment described later. (1) Dimensions and positions of the anode, the film formation area on the surface of the substrate and the auxiliary cathode

[0044] Fig. 4 is a cross-sectional view schematically illustrating an example of the dimensions and positional relationship of the anode, the film formation region on the surface of the substrate, and the auxiliary cathode in film formation by the film forming apparatus for forming a metal foil according to the first embodiment. Specifically, it is a drawing illustrating an example of their dimensions and position when the end surface on the cathode side of the solid electrolyte membrane is brought into contact with the film formation region on the surface of the substrate to form a metal foil in the film formation region in a cross-sectional area including a direction parallel to one side of the film formation region.

[0045] Here, the result of analyzing the current density variations in a film formation region 14r when the voltage is applied between the anode 2, the cathode 4, and the auxiliary cathode 14 to form a metal foil M in the film formation region 4r on the surface 4s of the substrate 4 when the following distances are changed to appropriate values ​​in the film forming apparatus for forming a metal foil according to the first embodiment will be described. The distances are: a distance from the center Q to the outer circumference B (hereinafter referred to as "QB distance" in some cases) of the film formation region 4r on the surface 4s of the substrate 4, illustrated in Fig. 4; a distance from the center P to the outer periphery A (hereinafter referred to as "PA distance" in some cases) on the surface 2s of the anode 2; a distance from the outer periphery B of the film formation region 4r to the inner periphery C of the surface 14s of the auxiliary cathode 14 (hereinafter referred to as "BC distance" in some cases); a distance from the inner periphery C to the outer periphery D on the surface 14s of the auxiliary cathode 14 (hereinafter referred to as "CD distance" in some cases); and a distance from the center P on the surface 2s of the anode 2 to the center Q of the film formation region 4r (hereinafter referred to as "PQ distance").

[0046] In the analysis of current density variations, Abaqus, manufactured by Dassault Systemes SE, was used as the analysis software. First, for the cases where the PA spacing, BC spacing, CD spacing, and PQ spacing were changed to relative values ​​under the respective conditions illustrated in Table 1 below, after setting the QB spacing to 1 as a default relative value, the current densities at each position in the film formation region 4r on the surface 4s of the substrate 4 were calculated to analyze a current density distribution in the film formation region 4r. Fig. 5A is a diagram illustrating a current density distribution in the film forming region and on the surface of the auxiliary cathode analyzed when the PA pitch, the BC pitch, the CD pitch, and the PQ pitch are changed to relative values ​​under predetermined conditions in the film forming apparatus for forming a metal film according to the first embodiment. Fig. 5B is a graph illustrating a change in current density from the center of the film formation region to the surface of the auxiliary cathode in a direction (an evaluation direction) parallel to a side of the film formation region shown in Fig. 5A. In the graph of Fig. 5B, the current density is shown on the vertical axis with the current density in the center of the film formation region as 1. Next, from the analysis result of the current density distribution in the film formation region 4r for each condition illustrated in Table 1 below, the maximum value and the minimum value of the current density from the center Q to the outer circumference B of the film formation region 4r in the direction (the evaluation direction) parallel to the one side of the film formation region 4r shown in Fig. 5A, and "(the maximum current density value in the film formation region - the minimum current density value of the film formation region) / the current density in the center of the film formation region" was calculated and obtained as current density variations. The results are illustrated in Table 1 below. [Table 1] Zustand Q-BAbstand[-] P-AAbstand[-] B-CAbstand[-] C-DAbstand[-] P-QAbstand[-] Sromdichtevariation [-] 1 1,00 0,95 0,05 0,05 0,10 0,59 2 1,00 1,15 0,05 0,05 0,10 0,80 3 1,00 0,95 0,15 0,05 0,10 0,54 4 1,00 1,15 0,15 0,05 0,10 1,37 5 1,00 0,95 0,05 0,15 0,10 0,60 6 1,00 1,15 0,05 0,15 0,10 0,52 7 1,00 0,95 0,15 0,15 0,10 0,54 8 1,00 1,15 0,15 0,15 0,10 1,28 9 1,00 0,95 0,05 0,05 0,30 0,40 10 1,00 1,15 0,05 0,05 0,30 0,74 11 1,00 0,95 0,15 0,05 0,30 0,39 12 1,00 1,15 0,15 0,05 0,30 1,01 13 1,00 0,95 0,05 0,15 0,30 0,48 14 1,00 1,15 0,05 0,15 0,30 0,38 15 1,00 0,95 0,15 0,15 0,30 0,43 16 1,00 1,15 0,15 0,15 0,30 0,75 17 1,00 0,88928 0,10 0,10 0,20 0,65 18 1,00 1,21072 0,10 0,10 0,20 0,95 19 1,00 1,05 0,02 0,10 0,20 0,23 20 1,00 1,05 0,18 0,10 0,20 0,13 21 1,00 1,05 0,10 0,02 0,20 0,57 22 1,00 1,05 0,10 0,18 0,20 0,34 23 1,00 1,05 0,10 0,10 0,04 0,83 24 1,00 1,05 0,10 0,10 0,36 0,47 25 1,00 1,05 0,10 0,10 0,20 0,37

[0047] The following describes the results of the target ranges of the PA spacing, BC spacing, CD spacing, and PQ spacing where the current density variation is 0.3 or less, where 0.3 represents the degree of variation in the film formation by the conventional coating. The results of the target ranges are obtained by analyzing the current density variation analysis results shown in Table 1 above, using the response surface design method.

[0048] In the surface response methodology, JUSE-StatWorks (registered trademark), manufactured by the Institute of Japanese Union of Scientists & Engineers, was used as the statistical analysis software. With the current density variation used as objective variables (characteristic values) and the PA distance, BC distance, CD distance, and PQ distance used as explanatory variables, the analysis obtained the intended ranges of their distances where the current density variation becomes 0.3 or less.

[0049] Fig. Figure 6 is a drawing showing four graphs illustrating current density variations for each of the PA, BC, CD, and PQ distances obtained by the analysis using the response surface method. In the analysis using the response surface method, it was found that the optimal value of the PA distance, the optimal value of the CD distance, and the optimal value of the PQ distance at which the minimum value of the current density variation was obtained were 1.02, 0.11, and 0.24, respectively. The optimal value of the BC distance at which the minimum value of the current density variation was obtained was given as 0.10, corresponding to the optimal value (1.02) of the PA distance. Fig. Figure 6 is a graph illustrating the current density variation for the PA pitch when the CD pitch and PQ pitch are set to the optimal values, and the BC pitch is set to 0.10. The graph illustrating the current density variation for the BC pitch is a graph when the PA pitch, CD pitch, and PQ pitch are set to the optimal values. The graph illustrating the current density variation for the CD pitch is a graph when the PA pitch and PQ pitch are set to the optimal values, and the BC pitch is set to 0.10. The graph illustrating the current density variation for the PQ pitch is a graph when the PA pitch and CD pitch are set to the optimal values, and the BC pitch is set to 0.10. Fig. Figure 7 is a contour map illustrating the current density variation for the PA distance (X) and the BC distance (Y) obtained by the analysis using the response surface methodology. In Fig. 7, contour lines are illustrated when the CD distance and the PQ distance are set to the optimal values, a range in which the current density variation becomes 0.3 or less is illustrated as a filled area, and the minimum value of the current density variation, the optimal value of the PA distance, the optimal value of the BC distance, the optimal value of the CD distance, and the optimal value of the PQ distance are illustrated in the table.

[0050] As in Fig. As illustrated in Figure 6, by the analysis using the response surface methodology, the target ranges for the PA distance, the BC distance, the CD distance, and the PQ distance in which the current density variation becomes 0.3 or less were determined: the PA distance: 0.95 to 1.09, the BC distance: 0 to 0.2, the CD distance: 0.05 to 0.17, and the PQ distance: 0.15 to 0.32. Note that the target range of the BC distance in which the current density variation becomes 0.3 or less is a range in which the current density variation becomes 0.3 or less in a range where analysis accuracy can be obtained. In view of this, the film forming apparatus for forming a metal film has the PA pitch in a range of 0.95 to 1.09, the BC pitch in a range of 0 to 0.2, the CD pitch in a range of 0.05 to 0.17, and the PQ pitch in a range of 0.15 to 0.32.This is because the current density variation is 0.3 or less, and the effect that enables the film formation of the metal foil with a uniform foil thickness becomes remarkable.

[0051] As in Fig. As illustrated in Figure 7, each value of the PA distance (X) and the BC distance (Y) at which the current density variation becomes minimal at each value of the PA distance (X) satisfies a relational expression of Y = 1.76 - 1.64X (but 0 ≤ Y ≤ 0.2 for analysis accuracy), as shown by the dashed line in the graph. Considering this, the foil forming apparatus for forming a metal foil has the PA distance (X) and the BC distance (Y) satisfying the relational expression Y = 1.76 - 1.64X, where the PA distance is in a range of 0.95 to 1.09, the BC distance is in a range of 0 to 0.2, the CD distance is in a range of 0.05 to 0.17, and the PQ distance is in a range of 0.15 to 0.32. This is because the current density variation is further reduced, and the effect that enables the film formation of the metal foil with a uniform foil thickness becomes further remarkable.

[0052] Fig. 8A and Fig. 8B are cross-sectional views schematically illustrating other examples of dimensions and positions of the anode, substrate, and auxiliary cathode of the film forming apparatus for forming a metal foil in the film formation of the metal foil. Similar to Fig. 4 illustrate Fig. 8A and Fig. 8B shows their dimensions and positions when the end surface on the cathode side of the solid electrolyte membrane is brought into contact with the film forming region to form a metal foil in the film forming region on the surface of the substrate.

[0053] In the foil forming apparatus for forming a metal foil as described above, when the QB distance is 1, the PA distance is in the range of 0.95 to 1.09, and the BC distance is in the range of 0 to 0.2, making the PA distance (X) and the BC distance (Y) satisfy the relational expression Y = 1.76 - 1.64X (but 0 ≤ Y ≤ 0.2 for analysis accuracy) enables the reduction of the current density variation. Accordingly, as shown in Fig. 8A illustrates that in some embodiments, the BC distance decreases when the PA distance is increased. As in Fig. 8B, in some embodiments, the BC spacing is increased as the PA spacing is decreased. While the film forming apparatus for forming a metal film may be one having the outer periphery A of the surface 2s of the anode 2 disposed between the substrate 4 and the auxiliary cathode 14 (between BC), as in Fig. 4, it may be one having the outer periphery A of the surface 2s of the anode 2 between the inner periphery C and the outer periphery D (between CD) of the surface 14s of the auxiliary cathode 14, as in Fig. 8A, or it may be one having the outer periphery A of the surface 2s of the anode 2 between the center Q and the outer periphery B (between QB) of the film forming region 4r, as shown in Fig. 8B illustrates. (2) Other

[0054] Fig. 9 is a schematic cross-sectional view illustrating a film-forming state of the film-forming apparatus for forming a metal foil according to the second embodiment. The film-forming apparatus for forming a metal foil may be one having the auxiliary cathode in a body separated from the substrate, like the film-forming apparatus for forming a metal foil according to the first embodiment, or may be one in which the central side of the surface 4s of the substrate 4 serves as the film-forming region 4r, and the auxiliary cathode 14 is provided integrally with the substrate so that the auxiliary cathode 14 covers the region in the peripheral region of the film-forming region 4r on the surface 4s of the substrate 4, as in the film-forming apparatus 1 for forming a metal foil according to the second embodiment. Fig. 9 masked. Even with such a film forming apparatus 1, the concentration of the current on the edge portion of the film forming region 4r on the surface 4s of the substrate 4 can be suppressed. Note that when using such a film forming apparatus, the auxiliary cathode is normally removed after the metal foil is formed in the film forming region on the surface of the substrate.

[0055] Fig. 10 is a schematic cross-sectional view illustrating a film-forming state of the film-forming apparatus for forming a metal foil according to a third embodiment. The film-forming apparatus for forming a metal foil may be one having the auxiliary cathode 14 disposed at a position within the solution container 12 near the anode 2 with respect to the solid electrolyte membrane 6, such as the film-forming apparatus 1 for forming a metal foil according to the third embodiment. Fig.10. Even in such a film forming apparatus 1, the concentration of the current on the edge portion of the film forming region 4r on the surface 4s of the substrate 4 can be suppressed. 7. Foil forming method for forming a metal foil

[0056] A film forming method for forming a metal foil includes disposing a solid electrolyte membrane between an anode and a substrate serving as a cathode, forming a metal foil on a film forming region by applying a voltage between the anode and the cathode, while pressurizing the film forming region on the surface of the substrate through the solid electrolyte membrane with a fluid pressure of a solution to deposit metal ions contained in the solid electrolyte membrane. The solution is disposed between the anode and the solid electrolyte membrane. The solution contains the metal ions. The metal foil is formed by applying the voltage in a state where an auxiliary cathode whose electric potential is lower than an electric potential of the anode is disposed in a peripheral region of the film forming region when a surface of the substrate is viewed in plan view.

[0057] While the foil forming method for forming a metal foil is not particularly limited, as long as the above-mentioned auxiliary cathode has a lower electric potential than the anode, as in the foil forming method for forming a metal foil according to the first embodiment, the above-mentioned auxiliary cathode is at the same electric potential as the above-mentioned cathode in some embodiments. This is because the concentration of the current on the edge portion of the foil forming region on the surface of the substrate serving as the cathode can be effectively suppressed. This is also because the application of the electric potential to the substrate and the auxiliary cathode is facilitated.

[0058] The substrate serving as the cathode is not particularly limited as long as it has the electrical conductivity that can be operated as a cathode, and the metal foil can be formed in the film formation region on the surface of the substrate, wherein the substrate is made of metal such as aluminum, and the substrate in which a metallic base layer is disposed on a processing surface, such as a resin-made substrate and a silicon substrate. For example, a wiring pattern substrate in which a wiring pattern including a plurality of wires is disposed on a surface of an insulating substrate is included. When the wiring pattern substrate is used as the substrate serving as the cathode, the metal foil is formed on the wiring pattern in the film formation region on the surface of the substrate.This makes it possible to suppress the concentration of current on the wiring in a peripheral edge portion of the film forming region, whereby the wiring pattern obtained by forming the metal foil on a plurality of wirings with a uniform film thickness can be formed.

[0059] While the film forming method for forming a metal film is not particularly limited, for example, a method uses the film forming apparatus for forming a metal film according to the embodiment in some embodiments in the aforementioned film forming region.

[0060] Although the embodiments of the present invention have been described in detail above, the present invention is not limited thereto. DESCRIPTION OF THE CHARACTERS 1 foil forming device for forming metal foils 2 anode 2s surface of the anode 4 Substrate (cathode) 4s surface of the substrate 4r Film formation area on the surface of the substrate 6 Solid electrolyte membrane 6s end surface on the cathode side of the solid electrolyte membrane 8 Power supply device 12 solution containers 12h opening of the solution container 14 Auxiliary cathode 14s surface of the auxiliary cathode 30b Pump (pressure device) L Metal ion solution M metal foil

Claims

[1] Foil forming device (1) for forming a metal foil (M), comprising: an anode (2); a solid electrolyte membrane (6) arranged between the anode (2) and a substrate serving as a cathode (4); a current supply device (8) which applies a voltage between the anode (2) and the cathode (4); a solution container (12) containing a solution (L) between the anode (2) and the solid electrolyte membrane (6), the solution (L) containing metal ions; and a pressure device (30b) which pressurizes the solid electrolyte membrane (6) towards the cathode side with a fluid pressure of the solution (L), wherein a metal foil (M) is formed on a foil forming region by applying the voltage while the foil forming region is pressurized on a surface of the substrate (4r) through the solid electrolyte membrane (6) to deposit the metal ions contained in the solid electrolyte membrane (6), and wherein the film forming apparatus (1) further includes an auxiliary cathode (14) arranged in a peripheral region of the film forming region when the surface of the substrate (4s) is viewed in plan view, wherein an electric potential of the auxiliary cathode (14) is lower than an electric potential of the anode (2), wherein when the distance from the center (Q) to the outer periphery (B) of the film forming region (4r) on the surface (4s) of the substrate is set to 1 as a standard value of a relative value, a relative value of the distance from the center (P) to the outer circumference (A) on the surface (2s) of the anode (2) is 0.95 to 1.09, a relative value of the distance from the outer circumference (B) of the film forming region (4r) to the inner circumference (C) of the surface (14s) of the auxiliary cathode (14) is 0 to 0.2, a relative value of the distance from the inner periphery (C) to the outer periphery (D) on the surface (14s) of the auxiliary cathode (14) is 0.05 to 0.17, and a relative value of the distance from the center (P) on the surface (2s) of the anode (2) to the center (Q) of the film forming region (4r) is 0.15 to 0.

32. [2] A foil forming apparatus (1) for forming a metal foil (M) according to claim 1, wherein the auxiliary cathode (14) is at the same electric potential as an electric potential of the cathode (4). [3] A film forming method for forming a metal film (M) using the film forming apparatus (1) for forming a metal film (M) according to claim 1 or claim 2, comprising: Arranging a solid electrolyte membrane (6) between an anode (2) and a substrate serving as a cathode (4); and Forming a metal foil (M) on a foil forming region by applying a voltage between the anode (2) and the cathode (4), while the foil forming region on a surface of the substrate (4r) is pressurized through the solid electrolyte membrane (6) with a fluid pressure of a solution (L) to deposit metal ions contained in the solid electrolyte membrane (6), wherein the solution (L) is arranged between the anode (2) and the solid electrolyte membrane (6) and the solution (L) contains the metal ions, wherein the metal foil (M) is formed by applying the voltage in a state in which an auxiliary cathode (14) whose electric potential is lower than an electric potential of the anode (2) is arranged in a peripheral region of the foil forming region when the surface of the substrate (4s) is viewed in plan view. [4] A foil forming method for forming a metal foil (M) according to claim 3, wherein the auxiliary cathode (14) is at the same electric potential as an electric potential of the cathode (4).

Images