JP7632260B2 - Metal film forming apparatus and method - Google Patents

Description

The present invention relates to a film forming apparatus and a film forming method for forming a metal film on the surface of a substrate.

As an example of this type of technology, Patent Document 1 proposes a film formation device that forms a metal film on the surface of a substrate. This film formation device includes an anode, an electrolyte membrane disposed between the anode and the substrate that serves as the cathode, and a power supply unit that applies a voltage between the anode and the substrate. Between the anode and the electrolyte membrane, the film formation device further includes a container that contains a plating solution so as to be in contact with the anode and the electrolyte membrane, and a suction device that sucks in air that is present between the electrolyte membrane and the substrate when they are brought into contact with each other. With this film formation device, the suction device allows the metal film to be formed while suppressing the entrapment of air between the electrolyte membrane and the substrate.

JP 2014-051701 A

However, when attempting to separate the electrolyte membrane from the substrate after forming the metal film using the film forming device described in Patent Document 1, the electrolyte membrane may be stretched because it may be in close contact with the metal film.

The present invention was made in consideration of these points, and its purpose is to provide a film forming apparatus that can easily separate the electrolyte membrane from the substrate after the metal coating is formed while preventing the electrolyte membrane from being stretched.

In consideration of the above-mentioned problems, the metal film forming apparatus according to the present invention is a film forming apparatus comprising an anode, an electrolyte membrane disposed between the anode and a substrate, a container that contains the anode and a plating solution and has an opening on the substrate side covered with the electrolyte membrane, and a power supply unit that applies a voltage between the anode and the substrate that serves as a cathode, and forms a metal film derived from metal ions in the plating solution on the surface of the substrate by applying the voltage while the electrolyte membrane is in contact with the substrate. The film forming apparatus comprises a mounting table on which the substrate is placed, a lifting device that raises and lowers at least one of the container and the mounting table so that the electrolyte membrane can be brought into contact with and separated from the substrate, and a vacuum pump that sucks in air present between the substrate placed on the mounting table and the electrolyte membrane. The apparatus further includes a suction device for drawing air between the substrate placed on the mounting table and the electrolyte membrane, a pressure-feeding device for pressurizing air between the substrate and the electrolyte membrane, and a control device for controlling the lifting operation by the lifting device, the suction operation by the suction device, the application operation by the power supply unit, and the pressure-feeding operation by the pressure-feeding device. The control device controls the lifting operation by the lifting device while controlling the suction operation by the suction device so that the substrate contacts the electrolyte membrane, controls the application operation by the power supply unit after the substrate contacts the electrolyte membrane until the metal coating reaches a predetermined thickness, and controls the lifting operation by the lifting device while controlling the pressure-feeding operation by the pressure-feeding device so that the substrate is separated from the electrolyte membrane after the application operation is completed.

According to the present invention, first, the control device controls the lifting operation by the lifting device so that the substrate contacts the electrolyte membrane, while controlling the suction operation by the suction device. This control allows the electrolyte membrane to contact the substrate while the suction device sucks in air between the electrolyte membrane covering the opening formed in the container and the substrate arranged opposite the electrolyte membrane. As a result, air is prevented from getting caught between the electrolyte membrane and the substrate, and the electrolyte membrane can be tightly attached to the substrate.

Next, after the substrate comes into contact with the electrolyte membrane, the control device controls the application operation by the power supply unit until the metal film reaches a predetermined thickness. With this control, when a voltage is applied between the anode and the substrate while the electrolyte membrane is in contact with the substrate, metal ions move to the surface side of the substrate through the electrolyte membrane and are reduced on the substrate surface, causing the metal to precipitate. As a result, a metal film derived from the precipitated metal can be formed on the substrate surface. By applying such a voltage until the metal film reaches a predetermined thickness, a metal film of the desired thickness can be formed.

Finally, after the application operation is completed (i.e., after the application of the voltage for film formation is completed), the control device controls the lifting operation by the lifting device so as to separate the electrolyte membrane from the substrate, while controlling the pumping operation by the pumping device. This allows the electrolyte membrane to be separated from the substrate while supplying air between the substrate on which the metal coating is formed and the electrolyte membrane, so that the electrolyte membrane can be easily separated from the substrate while preventing the electrolyte membrane from adhering to the substrate and being stretched. In particular, when the electrolyte membrane is in contact with the substrate within an enclosed space, the enclosed space becomes a space depressurized by the suction device, but the pressure in the space can be increased by pumping air by the pumping device, thereby preventing the electrolyte membrane from adhering to the substrate.

In a more preferred embodiment, the film forming apparatus further includes a replacement mechanism for replacing the plating solution contained in the container with the atmosphere, and the control device controls the replacement mechanism so that the plating solution is replaced with the atmosphere after the application operation by the power supply unit is completed and before the control of the lifting device's lifting operation to separate the electrolyte membrane from the substrate is started.

According to this aspect, the control device controls the replacement mechanism so that the plating solution is replaced with the atmosphere before starting to control the lifting and lowering operation. With this control, the plating solution contained in the container is replaced with the atmosphere while the electrolyte membrane is in contact with the substrate, and then the electrolyte membrane is separated from the substrate, so that the electrolyte membrane can be prevented from being deformed by the weight of the plating solution. Furthermore, since the weight of the plating solution does not act on the electrolyte membrane, it becomes easier for air to enter between the electrolyte membrane and the substrate, and the electrolyte membrane can be easily separated from the substrate. In this specification, the "air" referred to in the present specification means the air that is sucked in means the air that exists between the electrolyte membrane and the substrate, and the air that is pumped is pressurized air in the atmosphere. The "atmosphere" for replacing the plating solution contained in the container means air at atmospheric pressure in the atmosphere.

This specification also discloses a method for forming a metal film as the present invention. The method for forming a metal film according to the present invention is a method for forming a metal film derived from the metal ions contained in the electrolyte film on the surface of the substrate by applying a voltage between an anode and a substrate serving as a cathode while an electrolyte film that has been in contact with a plating solution containing metal ions is in contact with the substrate, and is characterized in that it includes the steps of: bringing the electrolyte film into contact with the substrate while sucking in air that exists between the electrolyte film covering the opening formed in the container and the substrate arranged opposite the electrolyte film; applying a voltage between the anode and the substrate while the electrolyte film is in contact with the substrate until the metal film has a predetermined thickness, thereby forming the metal film; and separating the electrolyte film from the substrate while pumping air between the substrate on which the metal film has been formed and the electrolyte film.

According to the present invention, first, with the plating solution contained in the container, the electrolyte membrane covering the opening formed in the container and the substrate placed opposite the electrolyte membrane are brought into contact with the substrate while the air between the electrolyte membrane covering the opening formed in the container and the substrate is sucked in by a suction device. As a result, it is possible to prevent air from being trapped between the electrolyte membrane and the substrate and to make the electrolyte membrane adhere closely to the substrate.

Next, when a voltage is applied between the anode and the substrate with the electrolyte membrane in contact with the substrate, metal ions migrate to the surface side of the substrate through the electrolyte membrane and are reduced on the surface of the substrate, causing the metal to precipitate. As a result, a metal film derived from the precipitated metal can be formed on the surface of the substrate. By applying this voltage until the metal film reaches a predetermined thickness, a metal film of the desired thickness can be formed.

Finally, since the electrolyte membrane can be separated from the substrate, on which the metal coating is formed, while air is supplied between the substrate and the electrolyte membrane, the electrolyte membrane can be easily separated from the substrate while preventing the electrolyte membrane from adhering to the substrate and being stretched. In particular, when the electrolyte membrane is in contact with the substrate within an enclosed space, the enclosed space becomes a space that has been depressurized by the suction device, but the pressure within the space can be increased by pumping air using the pumping device, thereby preventing the electrolyte membrane from adhering to the substrate.

A more preferred film forming method further includes a step of replacing the plating solution contained in the container with air after the step of forming the metal film and before the step of separating.

According to this aspect, after the plating solution contained in the container is replaced with air while the electrolyte membrane is in contact with the substrate, the electrolyte membrane is separated from the substrate, so that the electrolyte membrane can be prevented from being deformed by the weight of the plating solution. Furthermore, because the weight of the plating solution does not act on the electrolyte membrane, it becomes easier for air to get between the electrolyte membrane and the substrate, making it easier to separate the electrolyte membrane from the substrate.

According to the present invention, after the metal film is formed, the electrolyte membrane can be easily separated from the substrate while preventing the electrolyte membrane from being stretched.

1 is a schematic cross-sectional view of a metal film forming apparatus according to an embodiment of the present invention. 2 is a flowchart illustrating control of the film forming apparatus shown in FIG. 1 . 3 is a cross-sectional view for explaining the suction and contact step shown in FIG. 2 using the film forming apparatus shown in FIG. 1. 3 is a cross-sectional view for explaining the film forming process shown in FIG. 2 using the film forming apparatus shown in FIG. 1. 3 is a cross-sectional view for explaining the replacement step shown in FIG. 2 using the film forming apparatus shown in FIG. 1. 3 is a cross-sectional view for explaining the pressure-feeding and separation step shown in FIG. 2 using the film forming apparatus shown in FIG. 1. FIG. 13 is a diagram illustrating the relationship between the elongation rate of an electrolyte membrane and the number of membrane formation operations using the membrane formation apparatuses of the examples and the comparative examples.

The following describes a metal film deposition device according to an embodiment of the present invention with reference to the drawings.

As shown in FIG. 1, the film forming apparatus 1 includes an anode 11, an electrolyte membrane 13 disposed between the anode 11 and the substrate W, and a container 15 that contains the anode 11 and plating solution L and has an opening 15g that opens toward the substrate W and is covered with the electrolyte membrane 13. The film forming apparatus 1 further includes a power supply unit 19 that applies a voltage between the anode 11 and the substrate W that serves as the cathode, a mounting table 20 on which the substrate W is mounted, and a lifting device 70 that raises and lowers the container 15.

In the film forming apparatus 1, the lifting device 70 brings the electrolyte membrane 13 into contact with the substrate W placed on the mounting table 20, and the power supply unit 19 applies a voltage between the anode 11 and the substrate W to form a metal film on the surface wa of the substrate W. During film formation, metal ions contained inside the electrolyte membrane 13 from the plating solution L are reduced on the surface wa of the substrate W, causing the metal derived from the metal ions to precipitate, and the metal film F is formed by the precipitated metal (see, for example, FIG. 5).

The substrate W functions as a cathode. The material of the substrate W is not particularly limited as long as it functions as a cathode (i.e., a surface having electrical conductivity), and may be made of a metal material such as aluminum or iron, or the surface of a resin, ceramic, or the like may be coated with a metal layer such as copper, nickel, silver, or iron.

The mounting table 20 is made of a conductive material and is disposed below the container 15 so that the substrate W faces the electrolyte membrane 13. The substrate (specifically, the cathode) W is electrically connected to the negative electrode of the power supply unit 19 via the mounting table 20. If the mounting table 20 is made of an insulating material, the negative electrode of the power supply unit 19 may be directly connected to the substrate W via wiring.

As described below, an air pump (pressure-feeding device) 51 is connected to the mounting table 20 via a pressure-feeding path 81, and a suction pump (suction device) 52 is connected to the mounting table 20 via a suction path 82. The air pump 51 is a device that pumps pressurized atmospheric air between the substrate W placed on the mounting table 20 and the electrolyte membrane 13, and the suction pump 52 is a device that sucks in the air that exists between the substrate W placed on the mounting table 20 and the electrolyte membrane 13. The suction mechanism and pressure-feeding mechanism including the mounting table 20 will be described in detail below.

The anode 11 is attached to the container 15 described later so as to face the mounting table 20 (specifically, the substrate W), and is electrically connected to the positive electrode of the power supply unit 19 via a conductor or the like. The anode 11 has a shape corresponding to the film formation area of the substrate W. The film formation area of the substrate W is the surface wa of the substrate W facing the anode 11 that acts as a cathode. The anode 11 is a non-porous (for example, non-porous) anode made of the same metal as the metal coating, and is a block-shaped or flat anode. The anode 11 is made of the same metal as the metal coating, and may be soluble or insoluble in the plating solution L. However, as long as the required surface area is satisfied, the anode may be a porous anode, a mesh, or a metal ball laid out in a container.

When the anode 11 is soluble in the plating solution L, examples of the material include copper, nickel, silver, and tin. In this embodiment, there is no particular limitation as long as the anode 11 dissolves when a voltage is applied using the power supply unit 19. When the anode 11 is insoluble in the plating solution L, examples of the material include stainless steel, titanium, and titanium alloys.

As described above, the plating solution (electrolyte) L is a solution containing the metal of the metal film to be formed in an ionic state, and examples of such metals include copper, nickel, silver, and tin. The plating solution L is an aqueous solution in which such metals are dissolved (ionized) with an acid such as nitric acid, phosphoric acid, succinic acid, sulfuric acid, or pyrophosphoric acid. For example, when the metal is nickel, the plating solution L can be an aqueous solution of nickel nitrate, nickel phosphate, nickel succinate, nickel sulfate, nickel pyrophosphate, or nickel sulfamate. For example, when the metal is copper, the plating solution L can be an aqueous solution containing copper sulfate, copper pyrophosphate, or the like.

The electrolyte membrane (solid electrolyte membrane) 13 is a flexible membrane that can be impregnated (contained) with metal ions by contacting it with the plating solution L described above. The electrolyte membrane 13 is not particularly limited as long as the metal ions can be reduced in the substrate W when a voltage is applied from the power supply unit 19, and a metal derived from the metal ions can be precipitated. Examples of the material of the electrolyte membrane 13 include fluorine-based resins such as Nafion (registered trademark) manufactured by DuPont, hydrocarbon-based resins, polyamic acid resins, and resins with ion exchange functions such as Selemion (CMV, CMD, CMF series) manufactured by Asahi Glass Co., Ltd.

As shown in FIG. 1, the container 15 is made of a material insoluble in the plating solution L, and the anode 11 and the electrolyte membrane 13 are attached to the container 15. In this embodiment, a storage space S for storing the plating solution L is formed inside the container 15 by the side wall of the container 15, the anode 11, and the electrolyte membrane 13. The anode 11 is attached to the inner surface of the container 15, and an opening 15g that opens to the side of the substrate W is formed at a position opposite the anode 11. The opening 15g opens downward, and the electrolyte membrane 13 is attached so as to seal this opening 15g. In this embodiment, the periphery of the electrolyte membrane 13 is sandwiched between the main body 15a and the frame 15b of the container 15, thereby attaching the electrolyte membrane 13 to the container 15. The anode 11 and the electrolyte membrane 13 are arranged apart from each other and are in a non-contact state, and the storage space S formed between them is filled with the plating solution L during film formation. In this way, the container 15 is structured so that the plating solution L contained in the container space S comes into direct contact with the anode 11 and the electrolyte membrane 13.

The container 15 is formed with a supply flow path 15c for supplying the plating solution L to the storage space S, and a discharge flow path 15d for discharging the plating solution L from the storage space S. The supply flow path 15c and the discharge flow path 15d are connected to the storage space S. Both the supply flow path 15c and the discharge flow path 15d are connected to the storage space S near the electrolyte membrane 13.

The lifting device 70 is a device that lifts and lowers at least one of the container 15 and the mounting table 20 so that the electrolyte membrane 13 and the substrate W can be moved toward and away from each other. In this embodiment, the mounting table 20 is fixed and does not move, and the lifting device 70 lifts and lowers only the container 15. Specifically, as shown in FIG. 1 and FIG. 3, the lifting device 70 includes a device body 71 and a rod 72 that moves linearly relative to the device body 71, and the rod 72 is fixed to the upper part of the container 15. The lifting device 70 may be a known electric actuator that converts the rotation of a motor such as a servo motor into linear motion. As long as the electrolyte membrane 13 can be moved toward and away from the substrate W by linear motion, the lifting device 70 may be provided on the mounting table 20 or may be a hydraulic or pneumatic cylinder.

The following describes the circulation mechanism for circulating the plating solution L in the film forming apparatus 1, the suction mechanism and pressure-feed mechanism including the mounting table 20, and the control device 60. The film forming apparatus 1 includes, as the circulation mechanism, a tank 17 connected to the container 15 for storing the plating solution L discharged from the container 15, and a pump 18 connected to the tank 17 for pressure-feeding the plating solution L from the tank 17 to the container.

The tank 17 is provided with an electric heating device 90 for heating the plating solution L. The heating device 90 is not particularly limited in terms of the heating method, and may be, for example, a steam heater, as long as it can heat the plating solution L to a predetermined temperature. In this embodiment, the plating solution L contained in the tank 17 is heated by the heating device 90, and the heated plating solution L can be supplied from the tank 17 to the storage space S of the storage body 15 by the pump 18, thereby increasing the film formation speed of the metal film F. In this embodiment, the heating device is provided in the tank 17, but for example, if a film can be formed using the plating solution L heated to a predetermined temperature, the heating device may be provided in the storage body 15 or in the supply path 87 between the tank 17 and the storage body 15. In this embodiment, the "path" refers to a flow path formed by piping through which the plating solution L or air in the atmosphere (i.e., the atmosphere) flows.

In this embodiment, the tank 17 is connected to the container 15 via a supply path 87. A pump 18 is provided in the supply path 87, and the pump 18 is capable of rotating in both forward and reverse directions. When the pump 18 rotates in the forward direction, it is possible to send the plating solution L from the tank 17 to the container 15, and when the pump 18 rotates in the reverse direction, it is possible to send the plating solution L from the container 15 to the tank 17.

The container 15 is connected to discharge paths 83 and 84 that return the plating solution L discharged from the container 15 to the tank 17. In this embodiment, a three-way valve 56 is provided between the discharge paths 83 and 84. In addition to the discharge paths 83 and 84, the three-way valve 56 is connected to an open path 85 that is open to the atmosphere. The three-way valve 56 has a first switching position that connects the discharge paths 83 and 84, and a second switching position that connects the discharge path 83 and the open path 85. Each switching position of the three-way valve 56 is controlled by the control device 60.

As shown in FIG. 4, by rotating the pump 18 in the forward direction and controlling the three-way valve 56 to the first switching position, the plating solution L can be circulated while filling the container 15 with the plating solution L in the film forming apparatus 1. Specifically, the plating solution contained in the tank 17 is supplied to the container 15 by the pump 18 via the supply path 87, and the plating solution discharged from the container 15 is returned to the tank 17 via the discharge path 83 and the discharge path 84.

In this embodiment, for example, a pressure adjustment valve (not shown) may be provided in the discharge path 84 to adjust the liquid pressure of the plating solution L discharged from the container 15. This allows the liquid pressure of the plating solution L contained in the storage space of the container 15 to be adjusted to the pressure set by the pressure adjustment valve.

On the other hand, as shown in FIG. 5, if the pump 18 is rotated in reverse and the three-way valve 56 is controlled to the second switching position, the plating solution L contained in the container 15 can be replaced with air. Specifically, when the pump 18 is rotated in reverse with the three-way valve 56 in the second switching position, air is sucked in from the open path 85 and flows into the container 15 via the exhaust path 83, and the plating solution L contained in the container 15 is returned to the tank 17. As a result, the container space S of the container 15 is filled with air (atmospheric air) at atmospheric pressure.

In this embodiment, the replacement mechanism 50 is made up of the three-way valve 56, the open path 85, and the pump 18. However, the present invention is not limited to such an apparatus mechanism, and the replacement mechanism may be a mechanism in which a drain hole is provided near the bottom of the container 15 and the plating solution L is discharged by the weight of the plating solution L. Alternatively, the replacement mechanism may be a mechanism that pumps air into the storage space S of the container 15 using the air pump 51 described below or a different air pump. As long as the plating solution L can be replaced with air in the container 15, the configuration of the replacement mechanism is not particularly limited.

The mounting table 20 has a recess 21 formed therein to accommodate the substrate W. In this embodiment, a gap is formed between the sidewall of the recess 21 and the side surface of the substrate W. The mounting table 20 has a portion including the recess 21 protruding toward the housing 15 so that the surface wa of the substrate W enters the inside of the frame 15b of the housing 15 and fits loosely into the frame 15b when the surface wa of the substrate W is in contact with the electrolyte membrane 13. As a result, when the housing 15 is raised or lowered, the space including the substrate W and the electrolyte membrane 13 becomes a sealed space when the frame 15b is loosely fitted into the mounting table 20.

A flow path 22 is formed in the mounting table 20, and the flow path 22 communicates with the side wall of the recess 21 and the side surface of the substrate W and the gap. An air pump 51 is connected to the flow path 22. Specifically, a pressure-feeding path 81 is connected to the flow path 22, and the air pump 51 and an on-off valve 53 are provided in the pressure-feeding path 81 from the upstream side to the downstream side. As shown in FIG. 6, when the air pump 51 is started, the control device 60 opens the on-off valve 53 and supplies compressed air to the flow path 22 through the pressure-feeding path 81. The air supplied to the flow path 22 flows through the gap between the side wall of the recess 21 and the side surface of the substrate W, and is pressure-feed between the substrate W placed on the mounting table 20 and the electrolyte membrane 13. When the air pump 51 is driven, the on-off valve 55 provided in the flow path 22 is closed by the control device 60, and the on-off valve 54 described later may be opened by the control device 60.

In this embodiment, the flow path 22 is connected to the suction pump 52. Specifically, the flow path 22 is connected to a suction path 82 that is different from the pressure-feed path 81, and the suction path 82 is provided with an on-off valve 54 and a suction pump 52 from the upstream side to the downstream side. As shown in FIG. 6, when the suction pump 52 is started, the control device 60 opens the on-off valves 54 and 55, and the air between the electrolyte membrane 13 and the substrate W flows through the gap between the side wall of the recess 21 and the side surface of the substrate W, and is released to the atmosphere through the flow path 22 and the suction path 82. In this way, the suction pump 52 can suck in the air between the electrolyte membrane 13 and the substrate W. Note that when the air pump 51 is driven, the on-off valve 53 of the pressure-feed path 81 may be closed by the control device 60.

The control device 60 controls the lifting operation by the lifting device 70, the suction operation by the suction pump 52, the application operation by the power supply unit 19, the replacement operation by the replacement mechanism 50 (specifically, the drive and rotation direction of the pump 18), and the pumping operation by the air pump 51, as well as the operation of the on-off valves 53-55 and the three-way valve 56 accordingly. Note that the application operation by the power supply unit 19 is the operation of a switch that applies voltage by the power supply unit 19.

Although not shown, the control device 60 includes a storage device (not shown) that stores a control program for executing the following series of steps, and a computing device (not shown) that executes the control program. The storage device further stores settings such as the start timing and drive time of the pump 18, the air pump 51, and the suction pump 52, the application start time and application time of the power supply unit 19, and the amount of displacement by the lifting device 70. The control device 60 receives inputs such as a signal from a pressure sensor (not shown) that measures the pressure in the storage space S of the storage body 15 via an input device or the like.

The control flow of the control device 60 will be described with reference to FIG. 2 below. The control device 60 performs the following series of operations. First, an installation process S1 is performed. Specifically, in this process, a transport device (not shown) and the like are controlled to install the substrate W on the mounting table 20. At this time, the alignment of the substrate W with respect to the anode 11 attached to the container 15 is adjusted, and the temperature of the substrate W may be adjusted.

Next, the suction/contact step S2 is performed. Specifically, as shown in FIG. 3, the control device 60 controls the lifting operation by the lifting device 70 so that the substrate W contacts the electrolyte membrane 13, while controlling the suction operation by the suction pump 52. This control causes the electrolyte membrane 13 to contact the substrate W while sucking in the air present between the electrolyte membrane 13 covering the opening 15g of the container 15 and the substrate W arranged opposite the electrolyte membrane 13. As a result, air is prevented from being trapped between the electrolyte membrane 13 and the substrate W, and the electrolyte membrane 13 can be tightly attached to the substrate W. In this state, the control device 60 stops the suction pump 52. In this state, the flow path 22 becomes negative pressure (relative to atmospheric pressure). At this stage, the control device 60 closes the on-off valves 53 to 55 as necessary.

Next, the liquid supply process S3 is performed. In this process, the control device 60 controls the operation of the pump 18 and controls the three-way valve 56 to the first switching position. As a result, as shown in FIG. 4, by driving the pump 18 in the forward direction, the plating solution L heated to a predetermined temperature by the heating device 90 in the tank 17 can be supplied from the supply path 87 to the storage space S of the storage body 15 and returned to the tank 17 via the discharge paths 83 and 84.

Here, if the liquid pressure of the plating solution L contained in the storage space S can be maintained at a predetermined pressure by the above-mentioned pressure regulating valve, the control device 60 may continuously drive the pump 18 even during film formation. Also, an opening/closing valve (not shown) may be provided in the discharge path 83, and when the predetermined pressure is maintained, the control device 60 may close this opening/closing valve and stop the pump 18.

Next, the film-forming process S4 is performed. In this process, the control device 60 controls the application operation by the power supply unit 19 after the substrate W comes into contact with the electrolyte membrane 13 until the metal film F reaches a predetermined thickness. Specifically, when a voltage is applied between the anode 11 and the substrate W with the electrolyte membrane 13 in contact with the substrate W, metal ions move to the surface side of the substrate W through the electrolyte membrane 13 and are reduced on the surface wa of the substrate W, causing the metal to precipitate and form the metal film F. By applying such a voltage until the metal film F reaches a predetermined thickness, the metal film F can be formed to a desired thickness.

Next, the replacement step S5 is performed. In this step, the control device 60 controls the replacement mechanism 50 (specifically, the pump 18 and the three-way valve 56) so that the plating solution L is replaced with the atmosphere. Specifically, the control device 60 switches the three-way valve 56 to the second switching position and reverses the rotation of the pump 18, so that the plating solution L in the storage space S of the storage body 15 is returned to the tank 17 via the supply path 87, as shown in FIG. 5. At the same time, the atmosphere is introduced into the release path 85, and the introduced atmosphere is supplied to the storage space S of the storage body 15 via the exhaust path 83. When almost all of the plating solution L is exhausted from the storage space S, the control device stops the pump 18. Note that FIG. 5 shows a stage in the middle of replacing the plating solution L contained in the storage space with the atmosphere.

Next, the pressure-feeding/separation process S6 is performed. Specifically, as shown in FIG. 6, the control device 60 controls the lifting operation by the lifting device 70 so that the substrate W is separated from the electrolyte membrane 13, while controlling the pressure-feeding operation by the air pump 51. This control causes air to be pressure-feeded between the substrate W on which the metal film F is formed and the electrolyte membrane 13, and the electrolyte membrane 13 is separated from the substrate W. Specifically, the air pressure-feeded by the air pump 51 flows through the flow path 22 via the pressure-feeding path 81, is forced between the electrolyte membrane 13 and the substrate W, then flows through the flow path 22, and is discharged from the suction pump 52 via the suction path 82.

In this embodiment, in order to form such a flow, the control device 60 closes the on-off valve 55 and drives the suction pump 52 so that the flow path 22 does not become negative pressure (preferably to become positive pressure). However, if air can be caused to flow between the electrolyte membrane 13 and the substrate W, the suction pump 52 may not be driven and the air exhausted from the suction path 82 upstream of the suction pump 52 may be released into the atmosphere.

Finally, the removal process S7 is performed. In this process, since the substrate W and the container 15 are in the positional relationship shown in FIG. 1, a conveying device (not shown) is controlled to remove the substrate W from the mounting table 20. When forming a metal coating on a new substrate W, this series of processes is repeated.

According to this embodiment, as described above, in the pressure-feeding/separating step S6, the electrolyte membrane 13 is separated from the substrate W while pressure-feeding air between the electrolyte membrane 13 on which the metal film F is formed and the substrate W. This makes it possible to easily separate the electrolyte membrane 13 from the substrate W while preventing the electrolyte membrane 13 from being attached to the substrate W and stretched. In particular, in this embodiment, since the electrolyte membrane 13 is in contact with the substrate W in the sealed space, this sealed space becomes a space depressurized by the suction pump 52 in the suction/contact step S2, but the pressure in the space is increased by pressure-feeding air by the air pump 51 in the pressure-feeding/separating step S6, and the adhesion between the electrolyte membrane 13 and the substrate W can be suppressed.

Furthermore, with the electrolyte membrane 13 in contact with the substrate W, the plating solution L contained in the container 15 is replaced with air in the replacement step S5, and then the electrolyte membrane 13 is separated from the substrate W, so that the electrolyte membrane 13 can be prevented from being deformed by the weight of the plating solution L. Furthermore, since the weight of the plating solution L does not act on the electrolyte membrane 13, it becomes easier to get air between the electrolyte membrane 13 and the substrate W in the pressure-feeding and separation step S6, making it easier to separate the electrolyte membrane 13 from the substrate W.

The present invention is illustrated by the following examples.

[Example]
As a substrate on whose surface a film was formed, a copper block substrate having a film formation area of 18 mm×35 mm and a thickness of 3 mm was prepared.

Next, a nickel film was formed using the film forming apparatus shown in FIG. 1. A 1M nickel chloride + nickel acetate aqueous solution (pH 4.0) was prepared as the plating solution, and a nickel anode was used as the anode. As film forming conditions, the temperature of the plating solution was set to 60°C, an electrolyte membrane (Nafion (registered trademark): manufactured by DuPont) was attached to the substrate, and electricity was applied for 3 minutes and ²⁰ seconds at a liquid pressure of 1.0 MPa and a current density of 15 A/dm2 to form a nickel film. This was repeated multiple times according to the flow shown in FIG. 2.

[Comparative Example]
A nickel coating was formed in the same manner as in Example 1. The difference from Example 1 is that the pressure-feeding and separation step S6 shown in FIG.

<Confirmation of the elongation rate of the electrolyte membrane>
The elongation of the electrolyte membrane after repeated membrane formation was measured using the membrane formation apparatus of the Example and Comparative Example. The results are shown in Fig. 7. Fig. 7 is a diagram illustrating the relationship between the elongation of the electrolyte membrane and the number of membrane formations using the membrane formation apparatus of the Example and Comparative Example.

As shown in Figure 7, when a nickel film was formed using the film forming apparatus of the embodiment, the electrolyte membrane hardly stretched compared to the membrane before the film was formed, even after the number of film formations exceeded 90, due to the reasons mentioned above. However, in the comparative example, in which the pumping and separation process was not performed, the electrolyte membrane underwent plastic deformation and stretched by about 16% after only a few film formations.

Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above-mentioned embodiments, and various design modifications can be made without departing from the spirit of the present invention as described in the claims.

In this embodiment, the film formation method is performed under the control of a control device, but for example, the series of operations shown in FIG. 2 may be performed manually without being controlled by a control device, or some of them may be performed by a control device.

1: Film forming device, 11: Anode, 13: Electrolyte membrane, 15: Container, 15g: Opening, 17: Tank, 19: Power supply, 20: Mounting table, 50: Replacement mechanism, 51: Air pump (pumping device), 52: Suction pump (suction device), 60: Control device, 70: Lifting device, W: Substrate, L: Plating solution

Claims (4)

An anode;
an electrolyte membrane disposed between the anode and a substrate;
a container that contains the anode and the plating solution and has an opening that opens to the substrate side and is covered with the electrolyte membrane;
A power supply unit that applies a voltage between the anode and the base material that serves as a cathode,
A film forming apparatus for forming a metal film derived from metal ions in the plating solution on a surface of the substrate by applying the voltage while an electrolyte membrane is in contact with the substrate, the film forming apparatus comprising:
The film forming apparatus includes:
A mounting table on which the base material is placed;
a lifting device that lifts and lowers at least one of the container and the stage so that the electrolyte membrane can be brought into contact with and separated from the base material;
a suction device that sucks air present between the substrate placed on the mounting table and the electrolyte membrane;
a pressure-feeding device that pressurizes air between the substrate placed on the mounting table and the electrolyte membrane;
and a control device that controls the lifting operation by the lifting device, the suction operation by the suction device, the application operation by the power supply unit, and the pumping operation by the pumping device,
The control device includes:
controlling a lifting operation by the lifting device so that the base material comes into contact with the electrolyte membrane, while controlling a suction operation by the suction device;
After the base material comes into contact with the electrolyte membrane, the application operation by the power supply unit is controlled until the metal coating reaches a predetermined thickness;
a pressure-feeding operation by the pressure-feeding device is controlled while controlling a lifting operation by the lifting device so that the electrolyte membrane is separated from the substrate after the application operation is completed. The film forming apparatus further includes a replacement mechanism that replaces the plating solution contained in the container with air,
The metal film forming apparatus according to claim 1, characterized in that the control device controls the replacement mechanism so that the plating solution is replaced with air between the end of the application operation by the power supply unit and the start of control of the lifting operation by the lifting device so as to separate the electrolyte membrane from the substrate. A film formation method for forming a metal coating derived from the metal ions contained in the electrolyte membrane on a surface of the substrate by applying a voltage between an anode and the substrate serving as a cathode in a state in which an electrolyte membrane, which has been in contact with a plating solution containing metal ions, is brought into contact with the substrate, the method comprising the steps of:
a step of bringing the electrolyte membrane into contact with the base material while sucking air present between the electrolyte membrane covering the opening formed in the container and the base material disposed opposite the electrolyte membrane;
applying a voltage between the anode and the substrate while the electrolyte membrane is in contact with the substrate, until the metal coating reaches a predetermined thickness, thereby forming the metal coating;
and separating the electrolyte membrane from the substrate while pumping air between the substrate on which the metal film is formed and the electrolyte membrane. The method for forming a metal film according to claim 3, further comprising a step of replacing the plating solution contained in the container with air after the step of forming the metal film and before the step of separating.

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