Metal film forming apparatus and method

Abstract

To provide a deposition device capable of preventing damage to a permeable membrane even when a base material is pressed with the permeable membrane before deposition or the base material is separated from the permeable membrane after deposition.SOLUTION: A metal coating deposition device comprises an upper housing 11A in which a first housing chamber 11 storing a plating solution L is formed, a permeable membrane 13 attached to the upper housing 11A so as to seal the first housing chamber 11 from below, where at least a metallic ion contained in the plating solution L permeate, and a lifting and lowering device 14 on which a base material W is placed to lift and lower the base material W so as to be brought into contact with and separated from the permeable membrane 13. A first flow channel 21 for communicating a space S and the outside of the device and a second flow channel 22 for communicating the space S and the outside of the device at a position different from the first flow channel 21 are provided in an upper part of the upper housing 11A. A cross sectional area of the first flow channel 21 is larger than a cross sectional area of the second flow channel 22. A check value 23 limiting an air flow from the outside of the device toward the space S is provided in the first flow channel 21.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an apparatus and method for forming a metal film, which deposits a metal on the surface of a substrate by electrolytic plating or electroless plating from metal ions contained in a plating solution, thereby forming a metal film derived from the metal ions on the surface of the substrate. [Background technology]

[0002] For example, Patent Document 1 proposes a film forming apparatus for forming a metal film on the surface of a substrate, which uses a solid electrolyte membrane as one of the permeable membranes that allows metal ions to pass through and forms a metal film by electrolytic plating. This film forming apparatus includes a housing in which a storage chamber for storing a plating solution is formed. The housing is formed with a storage chamber for storing the plating solution, and a permeable membrane is attached to the housing so as to seal the storage chamber from below. During film formation, a metal film is formed on the surface of the substrate from metal ions that have permeated the permeable membrane while the substrate is kept pressed against the permeable membrane. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-008646 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the permeable membrane bends and swells downward due to the weight of the plating solution in the chamber, so when an attempt is made to press the substrate uniformly against the permeable membrane, the substrate pushes up the permeable membrane. This increases the pressure in the chamber, and the permeable membrane may be damaged. Furthermore, after the membrane is formed, the substrate is separated from the permeable membrane. At this time, the permeable membrane, which was pushed up by the substrate, swells downward due to the weight of the plating solution, and the load acting at this time may damage the permeable membrane.

[0005] The present invention has been made in consideration of the above points, and provides a metal coating deposition apparatus and a deposition method thereof that can prevent damage to a permeable membrane even if the substrate is pressed with a permeable membrane before deposition, or even if the substrate is pulled away from the permeable membrane after deposition. [Means for solving the problem]

[0006] In consideration of the above problems, the present invention provides a metal coating deposition apparatus comprising: a housing having a storage chamber in which a plating solution is stored so that a space is formed at an upper portion; a permeable membrane attached to the housing so as to seal the storage chamber from below, the permeable membrane being permeable to at least metal ions contained in the plating solution; and a lifting device on which a substrate is placed and which raises and lowers the substrate so as to be able to approach and separate from the permeable membrane. The substrate placed on the lifting device is raised to press the substrate with the permeable membrane, and while maintaining the substrate pressed against the permeable membrane, a metal coating is deposited on a surface of the substrate from metal ions which have permeated the permeable membrane. The upper portion of the housing is provided with a first flow path communicating the space with the outside of the apparatus, and a second flow path communicating the space with the outside of the apparatus at a position different from the first flow path, the first flow path having a larger flow path cross-sectional area than the second flow path, and the first flow path is provided with a check valve for restricting the flow of air from the outside of the apparatus toward the space.

[0007] According to the present invention, the substrate placed on the lifting device is raised and pressed against the permeable membrane. At this time, the weight of the plating solution pushes up the downwardly bent permeable membrane, but since the cross-sectional area of ​​the first flow path is larger than the cross-sectional area of ​​the second flow path, the air in the space can be discharged from the first flow path to the outside of the device. This makes it possible to prevent the pressure in the chamber from increasing and to prevent the permeable membrane from being damaged.

[0008] Next, while the substrate is kept pressed against the permeable membrane, a metal film is formed on the surface of the substrate from the metal ions that have permeated the permeable membrane, and then the substrate on which the metal film has been formed is separated from the permeable membrane. At this time, since the first flow path is provided with a check valve that restricts the flow of air from the outside of the device toward the space of the storage chamber, air outside the device (outside air) can be sucked into the space of the storage chamber through the second flow path. Since the flow path cross-sectional area of ​​the second flow path is smaller than the flow path cross-sectional area of ​​the first flow path, the air outside the device can be gently taken into the storage chamber. As a result, the permeable membrane gently swells downward due to the weight of the plating solution in the storage chamber, thereby reducing the impact acting on the permeable membrane. As a result, the permeable membrane can be prevented from being damaged.

[0009] In a more preferred embodiment, the plating solution is an electrolytic plating solution, the permeable membrane is a nonporous solid electrolyte membrane, and the film-forming apparatus further includes an anode in the accommodation chamber, in contact with the plating solution and disposed opposite the substrate, and a power supply unit that applies a voltage between the anode and the substrate serving as a cathode.

[0010] According to this embodiment, when a voltage is applied between the anode and the substrate, which serves as a cathode, while the substrate is pressed against the solid electrolyte membrane, metal ions contained in the plating solution pass through the solid electrolyte membrane and are uniformly reduced on the surface of the substrate, causing a metal to deposit on the surface of the substrate. As a result, a metal coating can be formed on the surface of the substrate.

[0011] In another preferred embodiment, the plating solution is an electroless plating solution, and the permeable membrane is a porous membrane that allows the plating solution to permeate. In this embodiment, when the substrate is pressed against the permeable membrane and the state is maintained for a predetermined time, the plating solution seeps out from the permeable membrane, and a metal coating can be formed on the surface of the substrate by electroless plating.

[0012] The present invention discloses a method for forming a metal film using the above-mentioned film forming apparatus. The method includes a pressing step of raising the substrate placed on the lifting device and pressing the substrate against the permeable membrane, a film forming step of forming the metal film on the surface of the substrate from metal ions that have permeated the permeable membrane while maintaining the substrate pressed against the permeable membrane, and a detaching step of lowering the substrate on which the metal film has been formed and separating the metal film from the permeable membrane, in which in the pressing step, the permeable membrane that has been bent downward by the weight of the plating solution is pushed up, thereby discharging air in the space from the first flow path to the outside of the apparatus, and in the detaching step, the substrate is separated from the permeable membrane, thereby sucking air from the outside of the apparatus into the space from the second flow path.

[0013] In this way, in the pressing step before the film forming step, the permeable membrane bent downward by the weight of the plating solution is pushed up, so that the air in the space can be discharged from the first flow path to the outside of the device, and therefore damage to the permeable membrane can be prevented. Furthermore, in the detaching step after the film forming step, the base material is detached from the permeable membrane, so that the air outside the device can be gently sucked into the space in the storage chamber through the second flow path while the check valve restricts the inflow of air outside the device from the first flow path. As a result, the permeable membrane gently swells downward due to the weight of the plating solution in the storage chamber, so that the impact acting on the permeable membrane can be reduced and damage to the permeable membrane can be prevented. Effect of the Invention

[0014] According to the metal coating forming apparatus of the present invention, even if the substrate is pressed with the permeable membrane before the film formation, or even if the substrate is separated from the permeable membrane after the film formation, damage to the permeable membrane can be prevented. [Brief description of the drawings]

[0015] [Figure 1] 1 is a schematic cross-sectional view of a metal film forming apparatus according to a first embodiment of the present invention. [Diagram 2] FIG. 2 is a flow diagram of the film forming method shown in FIG. [Diagram 3] 2A to 2C are diagrams for explaining a film formation method using the film formation apparatus shown in FIG. 1, where (a) is a diagram for explaining a pressing process, (b) is a diagram for explaining a film formation process, and (c) is a diagram for explaining a detachment process. [Figure 4] FIG. 5 is a schematic cross-sectional view of a metal film forming apparatus according to a second embodiment of the present invention. [Diagram 5] 5A to 5C are diagrams for explaining a film formation method using the film formation apparatus shown in FIG. 4, where (a) is a diagram for explaining a pressing process, (b) is a diagram for explaining a film formation process, and (c) is a diagram for explaining a detachment process. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] Hereinafter, a metal film forming apparatus and a metal film forming method according to a first and second embodiments of the present invention will be described with reference to FIGS. 1 to 5.

[0017] First Embodiment 1. Metal Coating Deposition Equipment 1 The film forming apparatus 1 according to this embodiment includes a first storage chamber (storage chamber) 11, a second storage chamber 12, a permeable membrane 13, and an elevator 14. The first storage chamber 11 is formed in an upper housing 11A, and stores a plating solution L containing metal ions. The plating solution L is stored in the first storage chamber 11 such that a space S is formed above the plating solution L.

[0018] The second storage chamber 12 is formed in the lower housing 12A. The second storage chamber 12 is disposed below the first storage chamber 11, and the substrate W is stored therein. A permeable membrane 13 is disposed between the first storage chamber 11 and the second storage chamber 12 so as to separate the first storage chamber 11 from the second storage chamber 12. The first storage chamber 11 is sealed by covering the opening of the upper housing 11A with the permeable membrane 13. As a result, the first storage chamber 11 can be partitioned by the permeable membrane 13 into the first storage chamber 11 containing the plating solution L and the second storage chamber 12 containing the substrate W, while the plating solution L is stored in the first storage chamber 11. The lower housing 12A may be provided with an opening / closing door for inserting and removing the substrate W from the second storage chamber 12, and the device configuration is not particularly limited as long as the substrate W after film formation can be removed from the second storage chamber 12 and a new substrate W can be placed in the second storage chamber 12.

[0019] The lifting device 14 is a device for placing the substrate W accommodated in the second accommodation chamber 12 and lifting the substrate W, and a linear-type electric actuator (not shown) or the like is attached to the lower part of the lifting device 14. A placement table 14a for placing the substrate W is formed at the upper end of the lifting device 14. A recess for positioning the substrate W is formed in the placement table 14a.

[0020] In this embodiment, the plating solution L is an electrolytic plating solution, and the permeable membrane 13 is a nonporous solid electrolyte membrane 13A. In this embodiment, in order to form the metal film F by electrolytic plating, an anode 32 and a power supply unit 36 ​​are further provided. The anode 32 is disposed in the first storage chamber 11 at a position in contact with the plating solution L and facing the substrate W.

[0021] The anode 32 may be, for example, either a soluble anode made of the same material as the metal film F (eg, Cu), or an anode made of a material insoluble in the plating solution L (eg, Ti).

[0022] The solid electrolyte membrane 13A is, for example, a membrane of a solid electrolyte having an ion-exchangeable functional group. The solid electrolyte membrane 13A is not particularly limited as long as it can transmit metal ions by contacting with the plating solution L and can precipitate a metal derived from the metal ions on the surface of the substrate W. The solid electrolyte membrane 13A is flexible and preferably has a thickness in the range of 5 μm to 200 μm. Examples of the solid electrolyte include fluorine-based resins such as Nafion (registered trademark) manufactured by DuPont, hydrocarbon-based resins, polyamic acid resins, and resins having a cation exchange function such as Selemion (CMV, CMD, CMF series) manufactured by Asahi Glass Co., Ltd.

[0023] The plating solution L is a liquid containing the metal of the metal coating in an ionic state, and examples of the metal include Cu, Ni, Ag, and Au. The plating solution L is prepared by dissolving (ionizing) these metals in an acid such as nitric acid, phosphoric acid, succinic acid, sulfuric acid, or pyrophosphoric acid.

[0024] In this embodiment, the anode 32 is suspended in the first storage chamber 11 by a support 34 and immersed in the plating solution L. A conductor 35 is inserted inside the support 34, one end of the conductor 35 is connected to the anode 32 via a wire, and the other end of the conductor 35 is connected to the positive electrode of a power supply unit 36 ​​via an electric circuit (not shown) such as a switch. The negative electrode of the power supply unit 36 ​​is connected to the substrate W via the mounting table 14a. This allows the power supply unit 36 ​​to apply a voltage between the anode 32 and the substrate W, with the substrate W serving as the cathode.

[0025] The substrate W may be a substrate made of a metal such as copper, iron, or aluminum, and may further have a metal coating such as nickel formed on the surface of the substrate W. Alternatively, the main body of the substrate W may be an insulating plate material made of glass epoxy resin or the like, and a metal film may be formed on the surface of this plate material (main body) by, for example, sputtering, and is not particularly limited as long as the surface of the substrate W acts as a cathode.

[0026] According to the film forming apparatus 1 of the present embodiment, the substrate W placed on the lifting device 14 is raised to press the substrate W against the solid electrolyte membrane 13A, and then a voltage is applied between the anode 32 and the substrate W (cathode) while maintaining the substrate W pressed against the permeable membrane 13. This causes metal ions in the plating solution L contained in the first storage chamber 11 to permeate through the permeable membrane 13, and the permeated metal ions are reduced on the surface of the substrate W. As a result, metal derived from the metal ions is precipitated on the surface of the substrate W, and a metal coating can be formed on the surface of the substrate W.

[0027] As shown in FIG. 1, the permeable membrane 13 (solid electrolyte membrane 13A) is attached to seal the opening of the upper housing 11A at the bottom, forming the first storage chamber 11 for storing the plating solution L. The weight of the plating solution L stored in the first storage chamber 11 acts on the permeable membrane 13, causing the permeable membrane 13 to swell downward. For this reason, in order to uniformly contact the permeable membrane 13 with the surface of the substrate W when forming the metal coating, the substrate W must push up the permeable membrane 13. If the first storage chamber 11 is sealed, this pushing up compresses the air in the space S in the first storage chamber 11, which may increase the pressure in the first storage chamber 11, and may cause damage to the permeable membrane 13.

[0028] Furthermore, after the film formation, when the permeable membrane 13 is separated from the substrate W, the weight of the plating solution L again causes the permeable membrane 13 to bend downward, but the compressed air in the space S in the first storage chamber 11 expands to return to its original state. Due to the restoring force of the compressed air and the weight of the plating solution L at this time, an excessive load may be applied to the attachment portion, such as the periphery of the permeable membrane 13, and in this case as well, there is a concern that the permeable membrane 13 may be damaged.

[0029] In consideration of this point, in this embodiment, the film forming apparatus 1 is further provided with a mechanism for slowly sucking in air (outside air) from the outside of the apparatus (external space of the film forming apparatus) and quickly discharging the air to the outside of the apparatus. Specifically, as shown in Fig. 1, a first flow path 21 that connects the space S to the outside of the apparatus and a second flow path 22 that connects the space S to the outside of the apparatus are provided at a position different from the first flow path 21. Note that the "outside of the apparatus" here refers to the space around the film forming apparatus 1 where outside air under atmospheric pressure exists.

[0030] The cross-sectional area of ​​the first flow path 21 is larger than that of the second flow path 22, and the first flow path 21 is provided with a check valve 23 that limits the flow of air from the outside of the device toward the space S. Here, the first flow path 21 and the second flow path 22 are formed by connecting a first pipe 21A and a second pipe 22A to the upper housing 11A so as to communicate with the first storage chamber 11, respectively. Here, the pipe diameter (caliber) of the first pipe 21A is larger than the pipe diameter (caliber) of the second pipe 22A. As a result, the air in the space S flows more easily from the first storage chamber 11 to the outside of the device through the first flow path 21 than through the second flow path 22.

[0031] The check valve 23 is attached to the first pipe 21A and restricts (prohibits) the flow of air (outside air) from outside the apparatus toward the space S, but does not restrict (allows without resistance) the flow of air from the space S toward the outside of the apparatus. Note that the "cross-sectional area of ​​the flow path" refers to the cross-sectional area of ​​a cross section perpendicular to the direction in which the fluid (air) flows in the flow path.

[0032] The second flow path 22 may further be provided with a throttling mechanism (not shown) such as an orifice or a throttle valve for throttling the flow rate of the outside air flowing from the outside of the device into the space S. Such a throttling mechanism may be set so that the space S is kept at a negative pressure (lower than atmospheric pressure) for a period from when the metal coating F is formed on the substrate W until the next new substrate W is brought into contact with the permeable membrane 13, as will be described below.

[0033] Furthermore, if the throttle mechanism is adjusted so that the space S is at atmospheric pressure when a new substrate W comes into contact with the permeable membrane 13, the permeable membrane 13 will expand downward to its original state due to the weight of the plating solution L, and wrinkles in the permeable membrane 13 that occurred after the membrane formation will be smoothed out. In this way, the permeable membrane 13 can be straightened.

[0034] 2.Metal coating method In this film formation method, a metal film is formed on the surface of the substrate W using the above-described film formation apparatus 1. In this embodiment, as a preparation step before the film formation, a plating solution L is contained in the first storage chamber 11 so that a space S is formed in the upper part of the first storage chamber 11. Furthermore, the substrate W is contained in the second storage chamber 12 so that the substrate W is placed on the mounting table 14a. In this state, the solid electrolyte membrane 13A is sandwiched between the plating solution L and the substrate W, and the plating solution L is disposed above the solid electrolyte membrane 13A so as to be in contact with the solid electrolyte membrane 13A, and the substrate W is disposed below the solid electrolyte membrane 13A with a gap therebetween.

[0035] The pressure in the space S within the first storage chamber 11 and the pressure inside the second storage chamber 12 are atmospheric pressure, and the first storage chamber 11 is in communication with the outside of the device via the second flow path 22. The solid electrolyte membrane 13A is bent so as to bulge downward due to the weight of the plating solution L, as shown in FIG.

[0036] First, in this embodiment, a pressing step S1 shown in Fig. 2 is performed. Specifically, as shown in Fig. 3(a), the substrate W placed on the lifting device 14 is raised to press the substrate W against the solid electrolyte membrane 13A. In order to bring the solid electrolyte membrane 13A into uniform contact with the substrate W, the solid electrolyte membrane 13A that has been bent downward due to the weight of the plating solution L is pushed up (lifted).

[0037] Here, since the flow path cross-sectional area of ​​the first flow path 21 is larger than the flow path cross-sectional area of ​​the second flow path 22, the first flow path 21 has a lower flow path resistance than the second flow path 22. As a result, by pushing up the solid electrolyte membrane 13A, the air in the space S corresponding to the reduced volume of the first storage chamber 11 can be quickly discharged from the first flow path 21 to the outside of the device. This prevents the pressure in the first storage chamber 11 from increasing, and the first storage chamber 11 can maintain a pressure close to atmospheric pressure, thereby preventing damage to the solid electrolyte membrane 13A.

[0038] Next, the film-forming step S2 shown in Fig. 2 is performed. Specifically, as shown in Fig. 3(b), in the film-forming step S2, while the solid electrolyte membrane 13A is kept pressed against the substrate W, a metal coating F is formed on the surface of the substrate W from metal ions that have permeated through the solid electrolyte membrane 13A. More specifically, in the first embodiment, as described above, an electrolytic plating solution is used as the plating solution L, and a nonporous solid electrolyte membrane is used as the solid electrolyte membrane 13A.

[0039] In the first storage chamber 11, the anode 32 is placed in contact with the plating solution L and facing the substrate W. With the substrate W pressed against the solid electrolyte membrane 13A, a voltage is applied between the anode 32 and the substrate W serving as the cathode. As a result, metal ions contained in the electrolytic plating solution that has permeated the solid electrolyte membrane 13A are reduced on the surface of the substrate W, and metal derived from the metal ions is precipitated. In this way, a metal coating F derived from the metal ions can be formed on the surface of the substrate W by using electrolytic plating.

[0040] Next, a separation step S3 shown in Fig. 2 is performed. Specifically, as shown in Fig. 3(c), in the separation step S3, the substrate W on which the metal film F is formed is lowered to separate the metal film F from the solid electrolyte membrane 13A. At this time, since the first flow path 21 is provided with a check valve 23 that restricts the flow of air (outside air) from the outside of the device toward the space S of the first storage chamber 11, the air (outside air) from the outside of the device can be gently sucked into the space S of the first storage chamber 11 through the second flow path 22.

[0041] Furthermore, since the cross-sectional area of ​​the second flow passage 22 is smaller than the cross-sectional area of ​​the first flow passage 21, air outside the device can be gently drawn into the first storage chamber 11. This allows the solid electrolyte membrane 13A to gently swell downward due to the weight of the plating solution L in the first storage chamber 11, thereby reducing the impact acting on the solid electrolyte membrane 13A. As a result, damage to the solid electrolyte membrane 13A can be prevented.

[0042] <Second embodiment> The film formation apparatus 1 and film formation method according to the second embodiment differ from those of the first embodiment in that a metal coating F is formed on the surface of a substrate W by utilizing electroless plating. Specifically, the film formation apparatus 1 for forming the metal coating F of this embodiment deposits metal on the surface of the substrate W from metal ions contained in a plating solution L by electroless plating, thereby forming a metal coating F derived from the metal ions on the surface of the substrate W. The same components as those of the film formation apparatus 1 according to the first embodiment are given the same reference numerals, and detailed description thereof will be omitted, with only the differences being described.

[0043] Here, electroless plating is a method of depositing (forming) a film by a chemical reduction reaction, unlike electrolytic plating, which is electrolytically deposited by a power source. Electroless plating includes displacement plating, which utilizes the difference in ionization tendency between the metal constituting the substrate W and the metal ions contained in the plating solution (electroless plating solution), and autocatalytic reduction plating, which utilizes the reducing ability of a reducing agent.

[0044] When the electroless plating is displacement plating, it is preferable to use a metal material made of a metal (a metal having a high ionization tendency) that is more base than the metal ions contained in the plating solution L as the substrate W. A layer made of a metal that is more base than the metal ions contained in the plating solution L may be formed on the surface of the substrate W body. In this case, a metal material or a resin material that is more noble than the metal ions contained in the plating solution L may be used as the substrate body. An example of such a substrate W is one in which a Ni plating layer is formed on the surface of a substrate made of Cu when the metal ions contained in the plating solution L are Au ions.

[0045] When the electroless plating is autocatalytic reduction plating, the substrate W may be made of a metal material, a resin material, or the like, so long as it is a material that has a catalytic effect of promoting the oxidation reaction of the reducing agent. A layer made of a metal that acts as a catalyst may be formed on the surface of the substrate W body. In this case, the substrate W body may be made of a metal material or a resin material that does not have a catalytic effect. An example of such a substrate W is a substrate W having a Pd plating layer that acts as a catalyst formed on the surface of a substrate made of Cu when the metal ions contained in the plating solution (electroless plating solution) L are Ni ions.

[0046] 4, the film forming apparatus 1 according to this embodiment differs from that of the first embodiment in that it does not include an anode 32, a support 34 supporting the anode, a power supply unit 36, etc., and uses a porous membrane 13B instead of a solid electrolyte membrane 13A as a permeable membrane 13. The porous membrane 13B seals the plating solution L contained in the upper housing 11A and is attached to the upper housing 11A so as to face the substrate W (specifically, the mounting table 14a). The porous membrane 13B is a membrane that allows the plating solution L to permeate in the film thickness direction and has a plurality of holes through which the plating solution L can permeate.

[0047] The thickness of the porous membrane 13B is preferably, for example, 5 μm or more and 200 μm or less. The average pore size of the porous membrane 13B may be, for example, 0.1 μm or more and 100 μm or less, and the pore size of the porous membrane 13B is not particularly limited as long as the plating solution L can pass through the porous membrane 13B in the thickness direction when the porous membrane 13B contacts the substrate W (specifically, the plating solution L can seep out when the porous membrane 13B is pressed against the substrate W).

[0048] In this embodiment, the porous membrane 13B may not have an ion exchange functional group (cation exchange functional group or anion exchange functional group) like a solid electrolyte. This allows the porous membrane to have almost no polarity, and metal ions contained in the plating solution L to pass through the pores without being trapped in the porous membrane. Therefore, such a plating solution L can be applied to any case in which the metal ions contained in the plating solution L are cationic, anionic, or nonionic. As such a plating solution L, a polyolefin resin can be used. Examples of the polyolefin resin include polyethylene resin, polypropylene resin, and a resin obtained by mixing these.

[0049] The plating solution (electroless plating solution) L is a solution supplied to one side of the porous membrane 13B, and is a solution containing at least metal ions that are deposited by electroless plating as the metal of the metal film F. The plating solution L for displacement plating or autocatalytic reduction plating may be a plating solution that is generally available commercially.

[0050] When the electroless plating is displacement plating, the metal of the metal ions contained in the plating solution L is a metal that is more noble (has a smaller tendency to ionize) than the material of the substrate W. For example, when the substrate W is made of Cu, examples of the metal of the metal ions include Ag, Pt, and Au.

[0051] When the electroless plating is autocatalytic reduction plating, the plating solution L contains metal ions to be deposited as the metal of the metal film F, and a reducing agent. The metal of the metal ions is not particularly limited as long as it is a metal having catalytic action, and examples thereof include Ag, Pt, and Au. Examples of the reducing agent include hypophosphorous acid, dimethylamine borane, and the like. The plating solution L may further contain a stabilizer, a complexing agent, a reducing agent, and the like.

[0052] In the film forming method according to this embodiment, the pressing step S1 (see FIG. 5(a)) and the separating step S3 (see FIG. 5(c)) are performed in the same manner as in the first embodiment. As shown in FIG. 5(a), in the pressing step S1, the substrate W is pressed against the porous membrane 13B, so that the plating solution L in the first storage chamber 11 passes through the porous membrane 13B and seeps out onto the surface of the substrate W. Therefore, as shown in FIG. 5(b), in this embodiment, if the substrate W is pressed against the porous membrane 13B and maintained for a predetermined time in the film forming step S2, a metal film F can be formed on the surface of the substrate W by electroless plating.

[0053] In the present embodiment, in the pressing step S1, the porous membrane 13B bent downward by the weight of the plating solution L is pushed up, so that the air in the space S can be quickly discharged to the outside of the device through the first flow path 21, thereby preventing damage to the porous membrane 13B. In the separating step S3, the substrate W is separated from the porous membrane 13B, so that the air outside the device can be gently sucked into the space S through the second flow path 22, thereby preventing damage to the porous membrane 13B.

[0054] The second flow path 22 may further be provided with a throttling mechanism (not shown) such as an orifice or a throttle valve for throttling the flow rate of the outside air flowing from the outside of the device into the space S. For example, such a throttling mechanism may be set so that the space S is kept at a negative pressure (lower than atmospheric pressure) until the next new substrate W is brought into contact with the porous membrane 13B after the metal coating F is formed on the substrate W, as described below.

[0055] This makes it possible to prevent the plating solution L in the first storage chamber 11 from seeping out of the porous membrane 13B until the substrate W is brought into contact with the porous membrane 13B. Furthermore, if the throttle mechanism is adjusted so that the space S is at atmospheric pressure at the timing when a new substrate W is brought into contact with the porous membrane 13B, the porous membrane 13B will swell downward to its original state due to the weight of the plating solution L, and wrinkles in the porous membrane 13B that occurred after the membrane formation will be smoothed out, and the porous membrane 13B will be straightened.

[0056] Although one embodiment of the present invention has been described in detail above, the present invention is not limited to the above embodiment, and various design modifications can be made without departing from the spirit of the present invention described in the claims.

[0057] In the first and second embodiments, a metal coating is formed on the surface of a single substrate placed on a mounting table. However, for example, multiple substrates may be placed on the mounting table, and metal coatings may be formed on the surfaces of the multiple substrates simultaneously.

[0058] In the pressing step, if the plating solution is not discharged outside the apparatus, a part of the plating solution may enter the first and second flow paths. [Explanation of symbols]

[0059] 1: film forming device, 11: first storage chamber (storage chamber), 11A: upper housing (housing), 13: permeable membrane, 13A: solid electrolyte membrane, 13B: porous membrane, 14: lifting device, 21: first flow path, 22: second flow path, 23: check valve, 32: anode, 36: power supply unit, F: metal film, S: space, L: plating solution, W: substrate

Claims

1. a housing having a chamber for containing a plating solution so that a space is formed at an upper portion; a permeable membrane attached to the housing so as to seal the accommodation chamber from below, the permeable membrane being permeable to at least metal ions contained in the plating solution; a lifting device on which a substrate is placed and which lifts and lowers the substrate so as to be able to approach and separate from the permeable membrane; a film forming apparatus for forming a metal film on a surface of the substrate from metal ions that have permeated the permeable membrane while maintaining a state in which the substrate is pressed against the permeable membrane by raising the substrate placed on the lifting device, a first flow path communicating the space with the outside of the device and a second flow path communicating the space with the outside of the device at a position different from that of the first flow path are provided in an upper portion of the housing; A metal coating deposition apparatus, characterized in that a flow path cross-sectional area of ​​the first flow path is larger than a flow path cross-sectional area of ​​the second flow path, and the first flow path is provided with a check valve for limiting the flow of air from outside the apparatus toward the space.

2. The plating solution is an electrolytic plating solution, the permeable membrane is a non-porous solid electrolyte membrane; The film forming apparatus includes: an anode disposed in the accommodation chamber in contact with the plating solution and facing the substrate; 2. The metal film forming apparatus according to claim 1, further comprising a power supply unit that applies a voltage between the anode and the substrate that serves as a cathode.

3. The plating solution is an electroless plating solution, 2. The metal film forming apparatus according to claim 1, wherein the permeable membrane is a porous membrane that allows the plating solution to permeate.

4. A method for forming a metal film using the film forming apparatus according to any one of claims 1 to 3, a pressing step of lifting the substrate placed on the lifting device and pressing the substrate against the permeable membrane; a film formation step of forming the metal film on the surface of the substrate from metal ions that have permeated the permeable membrane while maintaining the substrate pressed against the permeable membrane; a detaching step of lowering the substrate on which the metal coating is formed to detach the metal coating from the permeable membrane, In the pressing step, the permeable membrane, which has been bent downward by the weight of the plating solution, is pressed up, thereby discharging air in the space from the first flow path to the outside of the apparatus; A method for forming a metal coating, comprising the steps of: separating the substrate from the permeable membrane in the separating step, thereby sucking air outside the device into the space through the second flow path.

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