Method for forming a metal film

Abstract

To provide a deposition method for a metallic film capable of stably depositing a film in a predetermined pattern.SOLUTION: A mask 30 is placed on the surface of a substrate B, and an electrolyte membrane 13 covering an opening 15d formed in an accommodating body 15 that accommodates electrolyte solution L is brought into contact with the mask 30. With the electrolyte membrane 13 in contact with the mask 30, the electrolyte membrane 13 presses the substrate B through an open hole 35 by increasing the liquid pressure of the electrolyte solution L accommodated in the accommodating body 15. With the substrate B pressed by the electrolyte film 13, voltage is applied between an anode 11 and the substrate B to deposit a metallic film. In this deposition method, a pressing force such as magnetic force is applied to the mask 30 toward the substrate B to make the mask 30 adhere to the substrate B during the period between the placement of the mask 30 on the substrate B and the pressing of the substrate B with the electrolyte film 13.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a method for forming a metal film.

[0002] Conventionally, metal has been partially deposited on the surface of a substrate to form a metal film with a predetermined pattern. For example, Patent Document 1 describes a surface treatment apparatus including a mask that covers an opening formed in a container containing a solution containing metal ions, a conductive member disposed in the container apart from the mask, an electrolyte film disposed between the mask and the substrate, a power supply unit that applies a voltage between the conductive member and the substrate with the conductive member as the anode and the substrate as the cathode.

[0003] In this surface treatment apparatus, with the electrolyte film pressed against the surface of the substrate, the electrolytic solution contained in the container at a predetermined hydraulic pressure penetrates through the through-holes of the mask into the portion of the electrolyte film corresponding to the shape of the through-holes. Then, a voltage is applied between the conductive member and the substrate using the power supply unit. As a result, the metal ions impregnated in the electrolyte film move to the substrate in contact with the electrolyte film and are reduced on the surface of the substrate. As a result, metal is partially deposited on the surface of the substrate according to the shape of the through-holes of the mask, and a metal film is formed on the surface of the substrate.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] Incidentally, when forming a metal film with a predetermined pattern by partially depositing metal on the surface of a substrate, an electrolyte membrane may be attached to the container so as to cover the opening of the container, and a mask may be disposed between the electrolyte membrane and the substrate. When the hydraulic pressure of the electrolytic solution contained in the container is increased with the electrolyte membrane in contact with the surface of the mask, the surface of the mask is pressed by the electrolyte membrane, so that the mask is pressed against the substrate. At this time, the electrolyte membrane contacts the surface of the substrate following the shape of the through-hole in the masking plate in the region of the through-hole of the masking plate.

[0006] However, when the hydraulic pressure of the electrolytic solution is increased, the liquid derived from the electrolytic solution oozes out to the substrate side. When the through-hole of the mask is filled with the above liquid, the hydraulic pressure of the electrolytic solution in the container may become equal to the hydraulic pressure of the above liquid in the through-hole of the mask. In this case, since the force applied to the mask from the electrolyte membrane decreases, the force pressing the mask against the substrate also decreases. As a result, it is assumed that metal ions that have moved to the substrate side through the electrolyte membrane during film formation enter between the masking plate and the substrate, and a metal film with a desired pattern cannot be stably formed.

[0007] The present invention has been made in view of such points, and an object thereof is to provide a method for forming a metal film capable of stably forming a metal film with a predetermined pattern.

Means for Solving the Problems

[0008] In view of the above problems, the method for forming a metal film according to the present invention is such that through holes corresponding to a predetermined pattern are formed between an electrolyte membrane in contact with an electrolytic solution containing metal ions and a base material, and with a flexible mask disposed, a voltage is applied between an anode and the base material serving as a cathode, and by reducing the metal ions contained inside the electrolyte membrane, a metal film derived from the metal ions is formed on the surface of the base material in the predetermined pattern. The method for forming a film includes a mask placement step of placing the mask on the surface of the base material, a contact step of bringing the electrolyte membrane covering an opening formed in a container for accommodating the electrolytic solution into contact with the mask, a pressing step of pressing the base material with the electrolyte membrane through the through holes by increasing the hydraulic pressure of the electrolytic solution accommodated in the container with the electrolyte membrane in contact with the mask, and a film forming step of applying a voltage between the anode and the base material with the base material being pressed by the electrolyte membrane to form the metal film. The film forming method is characterized in that, at least from before the pressing step to the completion of the film forming step, an external force other than the hydraulic pressure is applied to the mask toward the base material to press the mask against the base material and maintain a state in which the mask is in close contact with the base material.

[0009] According to the present invention, in the pressing step, with the electrolyte membrane covering the opening of the container in contact with the mask, the hydraulic pressure of the electrolytic solution is increased, whereby the mask is pressed against the base material. At this time, the electrolyte membrane follows the shape of the through holes in the region of the through holes of the mask, and thereby the electrolyte membrane comes into contact with the surface of the base material. Thus, with the electrolyte membrane in contact with the mask and with the hydraulic pressure of the electrolytic solution increased, a voltage is applied between the anode and the base material, whereby a metal film in a predetermined pattern is formed on the surface of the base material.

[0010] Here, when the hydraulic pressure of the electrolytic solution is increased with the electrolyte membrane in contact with the mask, the liquid derived from the electrolytic solution oozes out to the substrate side. However, in the present invention, at least from before the pressing step to the completion of the film forming step, by applying an external force other than the hydraulic pressure to the mask toward the substrate, the mask is pressed against the substrate to keep the mask in close contact with the substrate. Thereby, even if the hydraulic pressure of the electrolytic solution accommodated in the container is increased, the mask can continue to be in close contact with the substrate. For this reason, metal ions that have moved to the substrate side through the electrolyte membrane are prevented from entering between the mask and the substrate together with the liquid that has oozed out from the electrolyte membrane, and a metal film with a desired pattern can be formed.

[0011] As a more preferred embodiment, the external force is a magnetic force, and the pressing of the substrate by the mask is performed by the magnetic force. According to this embodiment, the mask can be continuously pressed against the substrate by the magnetic force to keep the mask in close contact with the substrate. Further, if the magnetic force is demagnetized, the adsorbed mask can be easily removed from the substrate.

[0012] Here, a resin material containing a ferromagnetic material (for example, powder of a permanent magnet) may be used for the mask, and a soft magnetic material may be selected for the substrate. However, as a more preferred embodiment, the mask contains a soft magnetic material, and the magnetic force is the magnetic force of an electromagnet provided on the base on which the substrate is placed.

[0013] According to this embodiment, since the mask contains a soft magnetic material, the electromagnet provided on the base can be energized to magnetize the soft magnetic material by the magnetic force of the electromagnet. As a result, the mask can be adsorbed to the substrate. Further, by stopping the energization of the electromagnet, the magnetic force of the electromagnet is eliminated, and the mask can be easily removed from the substrate.

Effect of the Invention

[0014] According to the present invention, a metal film with a predetermined pattern can be stably formed.

Brief Description of the Drawings

[0015]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Embodiments for Carrying Out the Invention

[0016] First, the film forming apparatus 1 used in the method for forming a metal film according to an embodiment of the present invention will be described.

[0017] As shown in FIG. 1, the film forming apparatus 1 includes an anode 11, an electrolyte membrane 13, a power supply unit 14 that applies a voltage between the anode 11 and the base material B, and a container 15 that houses the anode 11 and an electrolytic solution L containing metal ions. A clamper 17 is attached to the container 15, and the clamper 17 fixes the electrolyte membrane 13 by sandwiching the electrolyte membrane 13 covering the opening 15d between the container 15. In the present embodiment, the mask 30 is placed on the base material B, and the electrolyte membrane 13 is disposed between the mask 30 and the anode 11. The film forming apparatus 1 further includes a base 40 on which the base material B is placed and a linear actuator 70.

[0018] As shown in FIG. 3, the film forming apparatus 1 is an apparatus that forms a metal film (not shown) on the surface of the base material B by applying a voltage between the anode 11 and the base material B using the power supply unit 14 in a state where the electrolyte membrane 13 is in contact with the base material B and reducing the metal ions contained inside the electrolyte membrane 13.

[0019] In this embodiment, for the sake of convenience of explanation, on the premise that the electrolyte membrane 13 is disposed below the anode 11 and further the mask 30 and the substrate B are disposed below it, the positional relationship of the constituent members of the film forming apparatus 1 is specified. However, as long as a metal film can be formed on the surface of the substrate B, it is not limited to this positional relationship. For example, the up and down of the film forming apparatus 1 in FIG. 1 may be reversed. For example, when the up and down of the film forming apparatus 1 in FIG. 1 is reversed, the mask 30 may be fixed to the clamper 17.

[0020] The substrate B functions as a cathode. The material of the substrate B is not particularly limited as long as it functions as a cathode (i.e., a surface having conductivity). The substrate B may be made of a metal material of a non-magnetic material such as aluminum or copper, or a metal layer such as copper may be coated on the surface of a resin or the like.

[0021] The base 40 holds the substrate B below the container 15 so that the substrate B faces the electrolyte membrane 13. In this embodiment, a mask 30 having through holes 35 of a predetermined pattern formed on the surface of the substrate B is placed. The mask 30 is for forming a metal film of a predetermined pattern on the surface of the substrate B. The configuration of the mask 30 will be described later.

[0022] The base 40 is formed of a conductive material (for example, metal) as an example. In this embodiment, it is made of a non-magnetic material such as aluminum or stainless steel. In this case, the negative electrode of the power supply unit 14 is electrically connected to the base 40, whereby the substrate B is electrically connected to the negative electrode of the power supply unit 14 via the base 40.

[0023] The anode 11 is, as an example, a non-porous (e.g., non-porous) anode made of the same metal as the metal of the metal film, and is a block-shaped or flat-plate-shaped anode. Examples of the material of the anode 11 include copper and the like. The anode 11 may be dissolved by applying a voltage using the power supply unit 14, but if a film is formed only with the electrolytic solution L, the anode 11 does not have to be dissolved. The anode 11 is attached to, for example, a container 15 formed of an insulating material. The anode 11 is electrically connected to the positive electrode of the power supply unit 14.

[0024] The electrolytic solution L is a solution containing the metal of the metal film to be formed in an ionic state. Examples of the metal include copper, nickel, gold, silver, or iron. The electrolytic solution L is a solution in which these metals are dissolved (ionized) with an acid such as nitric acid, phosphoric acid, succinic acid, sulfuric acid, or pyrophosphoric acid. Examples of the solvent of the solution include water and alcohol. For example, when the metal is copper, examples of the electrolytic solution L include an aqueous solution containing copper sulfate, copper pyrophosphate, and the like.

[0025] The electrolyte membrane 13 is a membrane that can be impregnated (contain) metal ions inside by contacting with the electrolytic solution L, and is a flexible membrane. The electrolyte membrane 13 is not particularly limited as long as metal ions can be reduced on the surface of the substrate B and the metal derived from the metal ions can be deposited when a voltage is applied by the power supply unit 14. Examples of the material of the electrolyte membrane 13 include resins having an ion exchange function such as fluorine-based resins such as Nafion (registered trademark) manufactured by DuPont.

[0026] As shown in FIG. 1, an anode 11 and an electrolyte membrane 13 are attached to a container 15, and a storage space 15c for storing an electrolytic solution L is formed by the container 15, the anode 11, and the electrolyte membrane 13. An opening 15d that opens to the side of the base material B is formed in the container 15, and the electrolyte membrane 13 is attached to the container 15 so as to cover the opening 15d. As shown in FIG. 2, the container 15 has a structure in which the electrolytic solution L stored in the storage space 15c is in direct contact with the anode 11 and the electrolyte membrane 13. The container 15 is made of a material insoluble in the electrolytic solution L.

[0027] As shown in FIG. 1, the linear actuator 70 raises and lowers at least one of the container 15 and the base 40 so that the electrolyte membrane 13 and the mask 30 can be brought into contact with and separated from each other. In the present embodiment, the base 40 is fixed, and the container 15 is raised and lowered by the linear actuator 70. The linear actuator 70 is provided above the container 15. The linear actuator 70 is, for example, an electric actuator that converts the rotational motion of a motor into a linear motion by a ball screw or the like (not shown). By this linear actuator 70, the container 15 can be raised and lowered with respect to the base 40, and the electrolyte membrane 13 can be brought into contact with and separated from a mask 30 described later. Note that the device for raising and lowering the container 15 may be a hydraulic or pneumatic cylinder or the like.

[0028] A supply channel 15a for supplying the electrolytic solution L to the storage space 15c and a discharge channel 15b for discharging the electrolytic solution L from the storage space 15c are formed in the container 15. The supply channel 15a and the discharge channel 15b are holes that communicate with the storage space 15c and are formed with the storage space 15c interposed therebetween. The supply channel 15a is fluidly connected to a liquid supply pipe 50 described later, and the discharge channel 15b is fluidly connected to a liquid discharge pipe 52 described later.

[0029] The film forming apparatus 1 includes a tank 85 and a pump 80. As shown in FIG. 1, an electrolytic solution L is stored in the tank 85. A liquid supply pipe 50 for supplying the electrolytic solution L to the container 15 and a liquid discharge pipe 52 for discharging the electrolytic solution L from the container 15 are connected between the tank 85 and the container 15.

[0030] The liquid supply pipe 50 is provided with a pump 80 for supplying the electrolytic solution L from the tank 85 to the container 15. The liquid discharge pipe 52 is provided with a pressure regulating valve 54. Thereby, it is possible to prevent the pressure (liquid pressure) of the electrolytic solution L stored in the accommodation space 15c from exceeding a predetermined pressure.

[0031] By driving the pump 80, the electrolytic solution L is sucked from the tank 85 into the liquid supply pipe 50, and the electrolytic solution L is pressure-fed from the supply flow path 15a to the accommodation space 15c. The electrolytic solution L used during film formation in the accommodation space 15c is returned to the tank 85 via the discharge flow path 15b. At this time, by continuing the rotation of the pump 80, the liquid pressure of the electrolytic solution L in the accommodation space 15c can be maintained at a predetermined pressure.

[0032] As shown in FIGS. 1 and 2, the mask 30 is placed on the surface of the base material B and is disposed between the electrolyte membrane 13 and the base material B, and has flexibility. The material of the mask 30 includes a soft magnetic material, and may further include resin and rubber.

[0033] Examples of the soft magnetic material included in the mask 30 include metal powders such as iron powder and metal foils such as iron. When the mask 30 contains a metal powder such as iron, it is preferably a mask in which the metal powder is dispersed in resin or rubber. Thereby, a magnetic force can be uniformly applied to the mask 30 by an electromagnet 60 described later. When the metal powder is dispersed in resin or rubber, it is preferable to ensure the insulation in the thickness direction of the mask 30 between the metal powders by the resin or rubber. Thereby, conduction between the mask 30 and the base material B can be avoided, and precipitation of the metal of the electrolytic solution L on the surface of the mask 30 can be prevented.

[0034] Furthermore, when the mask 30 includes a metal foil such as iron, it may be a mask in which the metal foil is sandwiched between insulating layers of resin or rubber as a metal intermediate layer. In addition to this, the metal foil may be a surface layer that contacts the substrate B side, and may have a structure of two or more layers including an insulating layer of resin or rubber as a surface layer that contacts the electrolyte membrane 13 side. An insulating layer that serves as another resin or rubber intermediate layer for enhancing flexibility may be provided between the insulating layer and the surface layer, and a metal layer may be further provided. Furthermore, metal powder such as iron may be dispersed in the insulating layer of resin or rubber.

[0035] Examples of the rubber used for the mask 30 include silicone rubber (PMDS) and ethylene propylene diene rubber (EPDM). Since the mask 30 is in the form of a film or a sheet, using these rubbers makes it easy to impart flexibility and compression deformability to the mask 30, and also makes it easy to adhere the mask 30 to the substrate B.

[0036] Furthermore, in the present embodiment, as shown in FIG. 1, an electromagnet 60 is provided on the base 40 as a device that applies a pressing force to the mask 30 toward the substrate B to adhere the mask 30 to the substrate B. Thereby, a magnetic force can be applied to the mask 30 to adhere the mask 30 to the substrate B.

[0037] The electromagnet 60 includes an iron core 61 made of a soft magnetic material such as iron, an electromagnetic coil 62 wound around the iron core 61, and a power source 63 that supplies current to the electromagnetic coil 62. Furthermore, the electromagnet 60 includes a switch 64 that supplies and cuts off the current from the power source 63, and a controller 65 that adjusts the magnitude of the current flowing from the current to the electromagnetic coil 62.

[0038] As shown in FIG. 2, by using such an electromagnet 60, when the switch 64 is turned ON, current flows from the power source 63 to the electromagnetic coil 62, and a magnetic force F1 is generated between the iron core 61 and the mask 30. The mask 30 containing a soft magnetic material is attracted to the base material B by the magnetic force F1. On the other hand, as shown in FIG. 1, when the switch 64 is turned OFF, the current flowing from the power source 63 to the electromagnetic coil 62 is interrupted, and the magnetic force F1 from the iron core 61 disappears. As a result, the magnetic force F1 acting on the mask 30 also disappears, and the mask 30 can be easily removed from the base material B.

[0039] Note that if the mask 30 contains resin or rubber, the mask 30 may elastically deform in the thickness direction due to the magnetic force F1 by the electromagnet 60, and thus the shape of the through hole 35 may also change significantly. Therefore, assuming such a point, in the present embodiment, a controller 65 for adjusting the amount of current flowing from the power source 63 is provided. Thereby, for example, when the mask 30 deforms beyond the assumed deformation amount in the thickness direction due to the magnetic force F1 by the electromagnet 60, the controller 65 decreases the amount of current flowing through the electromagnetic coil 62 to decrease the magnetic force F1 by the electromagnet 60. On the other hand, as shown in FIG. 3, when it is assumed that the adhesion between the mask 30 and the base material B is not sufficient before the film forming step described later, the controller 65 increases the amount of current flowing through the electromagnetic coil 62 to increase the magnetic force F1 by the electromagnet 60.

[0040] Next, a film forming method using the film forming apparatus 1 will be described. FIG. 4 is a flowchart for explaining an example of a method for forming a metal film according to an embodiment of the present invention.

[0041] First, in step S11, after the mask 30 is disposed on the surface of the base material B, the base material B together with the mask 30 is disposed on the base 40 (mask disposition step). Note that the mask 30 may be disposed on the base material B after the base material B is disposed on the base 40. At this time, the alignment of the base material B may be adjusted with respect to the anode 11 attached to the container 15, and the temperature of the base material B may be adjusted.

[0042] Next, an external force is applied to the mask 30 toward the base material B to bring the mask 30 into close contact with the base material (close contact step). Specifically, in step S12, energization of the electromagnet 60 is started to generate a magnetic force F1 as an external force. As shown in FIG. 2, when the switch 64 is turned ON, current flows from the power supply 63 to the electromagnetic coil 62, and a magnetic force is generated from the iron core 61. Due to this magnetic force, the mask 30 containing the soft magnetic material is attracted to the base material B by the magnetic force F1. Thereby, before pressing the mask 30 and the base material B with the hydraulic pressure of the electrolytic solution L, the mask 30 can be attracted to the base material B by the magnetic force F1.

[0043] Next, in step S13, the housing 15 is lowered with respect to the base 40 by the linear actuator 70. Thereby, the electrolyte membrane 13 covering the opening 15d of the housing 15 that houses the electrolytic solution L is brought into contact with the mask 30 (contact step). Note that when the stroke of the linear actuator 70 reaches a predetermined value, the lowering of the housing 15 stops.

[0044] Next, in step S14, the pump 80 is driven to store the electrolytic solution L in the storage space 15c of the housing 15. The electrolytic solution L sucked from the tank 85 by the pump 80 is supplied to the housing 15 through the liquid supply pipe 50. Since the pressure regulating valve 54 is provided in the liquid discharge pipe 52, by continuously rotating the pump 80, the hydraulic pressure of the electrolytic solution L in the storage space 15c is maintained at a predetermined pressure.

[0045] In this way, when the hydraulic pressure of the electrolytic solution L stored in the housing 15 is increased with the electrolyte membrane 13 in contact with the mask 30, the hydraulic pressure acts on the electrolyte membrane 13. With this hydraulic pressure, as shown in FIG. 3, the electrolyte membrane 13 follows the shape of the mask 30 and presses the base material B with the pressing force F2 through the through hole 35 with the electrolyte membrane 13 (pressing step). For example, when the mask 30 contains silicone rubber (PMDS) or ethylene propylene diene rubber (EPDM), due to the magnetic force F1 by the electromagnet and the pressing force F2 of the electrolyte membrane 13 by the hydraulic pressure of the electrolytic solution L, the mask 30 is compressed and deformed, and the adhesion between the mask 30 and the base material B is improved.

[0046] Here, when the hydraulic pressure of the electrolytic solution L is increased, the liquid derived from the electrolytic solution L oozes out toward the substrate B through the electrolyte membrane 13. However, in the present embodiment, the electromagnetic stone 60 acts a magnetic force F1 on the mask 30 toward the substrate B, and the mask 30 is brought into close contact with the substrate B. Therefore, even if the hydraulic pressure of the electrolytic solution L accommodated in the container 15 is increased, the mask 30 can be kept in close contact with the substrate B. As a result, it is possible to prevent the electrolytic solution L from entering between the mask 30 and the substrate B.

[0047] Next, proceed to step S15. Here, in a state where the mask 30 is in close contact with the substrate B by magnetic force and the substrate B is pressed together with the mask 30 by the electrolyte membrane 13 due to the increase in the hydraulic pressure of the electrolytic solution L, a voltage is applied between the anode 11 and the substrate B to form a metal film (film forming step). As a result, the metal ions contained in the electrolyte membrane 13 move to the surface of the substrate B in contact with the electrolyte membrane 13 and are reduced on this surface. As a result, metal is deposited on the surface of the substrate B, and a metal film corresponding to the pattern of the mask 30 is formed on the surface of the substrate B.

[0048] In the present embodiment, not only the pressing force F2 due to the hydraulic pressure of the electrolytic solution L but also the magnetic force F1 acting on the mask 30 bring the mask 30 into close contact with the substrate B. Therefore, it is possible to avoid the metal ions that have moved to the substrate side through the electrolyte membrane 13 from entering between the mask 30 and the substrate B together with the liquid that has oozed out from the electrolyte membrane 13, and it is possible to stably form a metal film with a desired pattern.

[0049] Next, in step S16, if the elapsed time of the voltage application has not elapsed for a predetermined time, return to step S15, the voltage application by the power supply unit 14 is continued, and the film forming step is continued. On the other hand, if the elapsed time of the voltage application has elapsed for a predetermined time, in step S17, the voltage application by the power supply unit 14 is terminated. This is because it is determined that the film thickness of the metal film on the surface of the substrate B is sufficient.

[0050] Next, in step S18, the driving of the pump 80 is stopped, and the pressing of the base material by the hydraulic pressure is released. In step S19, the energization of the electromagnet 60 is stopped. Specifically, when the switch 64 is turned OFF, the current flowing from the power source 63 to the electromagnetic coil 62 is interrupted, and the magnetic force F1 from the iron core 61 disappears.

[0051] Next, proceed to step S20. The linear actuator 70 raises the container 15 with respect to the base 40 to separate the electrolyte membrane 13 from the base material B. When the stroke of the linear actuator 70 reaches a predetermined value, the raising of the container 15 stops. Finally, in step S21, the base material B is removed from the base 40, and the mask 30 is removed from the base material B. In this way, a series of film formation methods using the film forming apparatus 1 is completed.

[0052] As described above, in the present embodiment, from before the pressing step to the completion of the film forming step, an external force (magnetic force F1) other than the hydraulic pressure is applied to the mask 30 toward the base material B, so that the mask 30 is pressed against the base material B and the state where the mask 30 is in close contact with the base material B is maintained. As a result, even if the hydraulic pressure of the electrolytic solution L is increased in the pressing step and film formation is performed in the film forming step, the liquid that has oozed out along with the movement of metal ions from the electrolyte membrane 13 can be prevented from entering the through holes 35 and penetrating between the mask 30 and the base material B. In the present embodiment, the close contact of the mask 30 with the base material B is started in step S12. However, for example, the close contact of the mask 30 with the base material B may be started after step S13 (contact step) and before step S14 (pressing step).

[0053] <Modification Example> FIG. 5 is a schematic cross-sectional view showing an example of a film forming apparatus used for a method of forming a metal film according to a modification of the present embodiment. In FIGS. 1 to 4, the mask 30 is brought into close contact with the base material B by the electromagnet 60. However, for example, as shown in FIG. 5, the base material B may be pressed together with the mask 30 by a pressing member 90. The pressing member 90 may be a permanent magnet, and the pressing member 90 may be fixed to the iron base 40 by magnetic force, and the base material B may be sandwiched between the pressing member 90 and the base 40 together with the mask 30.

[0054] In addition to this, with the base material B sandwiched between the pressing member 90 and the base 40 together with the mask 30, the pressing member 90 may be fixed to the base 40 using a fastener such as a screw or a bolt. In this fixed state, a gap may be provided between the pressing member 90 and the base 40, and by tightening the fastener, the base material B together with the mask 30 may be pressed by the pressing member 90. Thereby, an external force can be applied to the mask 30 to bring the mask 30 into close contact with the base material B.

Example

[0055] The present invention will be described by the following examples.

[0056] [Example 1] As a base material for film formation, a glass epoxy substrate (ABF substrate manufactured by Ajinomoto) formed by impregnating a cloth made of glass fiber with an epoxy resin was prepared. A copper foil was formed on the surface of this glass epoxy substrate. Next, a copper film was formed using the film forming apparatus according to the embodiment shown in FIGS. 1 and 2. At this time, the mask according to the embodiment shown in FIG. 3 was placed on the surface of the base material. The mask is formed of a silicone rubber containing iron powder. As the electrolytic solution, an aqueous copper sulfate solution (Cu - BRITE - SED) manufactured by JCU Corporation was used, and a Cu plate was used as the anode. As the film forming conditions, with the mask in close contact with the base material by an electromagnet, the temperature of the electrolytic solution was set to 42°C, the hydraulic pressure of the electrolytic solution was 0.6 MPa, the current density was 7 A / dm 2 , the film forming area was 25 cm 2 , and a 10 - μm thick copper film was formed with a cumulative film forming time of 388 seconds.

[0057] [Example 2] In the same manner as in Example 1, a copper film was formed. The difference from the example is that instead of using the electromagnet shown in FIG. 1, an external force was applied to the mask using the pressing member 90 shown in FIG. 5 to bring the mask into close contact with the base material.

[0058] [Comparative Example 1] A copper film was formed in the same manner as in the examples. The difference from Examples 1 and 2 is that the mask was not adhered to the substrate by an external force such as magnetic force.

[0059] <Confirmation of film formation state> In order to confirm whether a metal film with a desired pattern was formed on the substrate formed into a film as described above, the surface of the substrate was observed with an electron microscope. In Examples 1 and 2, the metal film showed a sharp contour that coincided with the contour of the through-hole of the mask (no bleeding). In contrast, in the comparative example, when the metal film with the desired pattern was not formed, the metal film did not coincide with the contour of the through-hole of the mask (bleeding occurred).

[0060] (Results and discussion) In Examples 1 and 2, it is considered that by applying an external force to the mask and forming a film in a state where the mask is adhered to the substrate, a metal film with a desired pattern could be formed (no bleeding). In Comparative Example 1, it is considered that since no external force was applied to the mask, the bleeding solution of the electrolyte membrane flowed into the space between the mask and the substrate, and a metal film with a desired pattern could not be formed.

[0061] As described above, the embodiments of the present invention have been described in detail. However, the present invention is not limited to the above-described embodiments, and various design changes can be made without departing from the spirit of the present invention described in the claims.

[0062] In this embodiment, the generation and disappearance of magnetic force were controlled using an electromagnet. In addition, for example, two plate-shaped permanent magnets may be overlapped, and a mechanism may be provided on the base to generate magnetic force by rotating only one of the permanent magnets so that the same poles overlap, and to cancel the magnetic force by rotating only one of the permanent magnets so that different poles overlap.

Explanation of reference numerals

[0063] 11: Anode, 13: Electrolyte membrane, 15: Container, 15d: Opening, 30: Mask, 35: Through-hole, 60: Electromagnet, B: Substrate, L: Electrolyte

Claims

【Claim 1】 A film forming method for forming a metal film derived from the metal ions on the surface of the substrate in a predetermined pattern, in which through holes corresponding to a predetermined pattern are formed between an electrolyte membrane and a substrate in contact with an electrolytic solution containing metal ions, and with a flexible mask disposed, a voltage is applied between an anode and the substrate serving as a cathode, and the metal ions contained inside the electrolyte membrane are reduced, comprising: a mask disposing step of disposing the mask on the surface of the substrate; a contact step of bringing the electrolyte membrane covering an opening formed in a container for accommodating the electrolytic solution into contact with the mask; a pressing step of pressing the substrate with the electrolyte membrane through the through holes by increasing the hydraulic pressure of the electrolytic solution accommodated in the container while the electrolyte membrane is in contact with the mask; a film forming step of applying a voltage between the anode and the substrate while pressing the substrate with the electrolyte membrane to form the metal film; the film forming method includes, from at least before the pressing step to the completion of the film forming step, applying an external force other than the hydraulic pressure to the mask toward the substrate to press the mask against the substrate and maintain a state in which the mask is in close contact with the substrate; the external force is the magnetic force of an electromagnet provided on a base on which the substrate is placed; the mask is a mask in which metal powder as a soft magnetic material is dispersed in rubber; the electromagnet includes an iron core, an electromagnetic coil wound around the iron core, a power source for passing an electric current through the electromagnetic coil, a switch for energizing and interrupting the electric current from the power source to the electromagnetic coil, and a controller for adjusting the magnitude of the electric current flowing from the power source to the electromagnetic coil; by energizing the electric current from the power source by the switch, the substrate is pressed by the mask by the magnetic force, and when the mask is deformed beyond a predetermined deformation amount in the thickness direction of the mask by the magnetic force, the controller reduces the electric current flowing through the electromagnetic coil and reduces the magnetic force. A method for forming a metal film, characterized in that.

Images