MASKING MEMBER AND FILM FORMING APPARATUS FOR METAL FILM USING SAME

Abstract

A masking member is for forming, by electroplating, a metal film in a predetermined pattern on the surface of the substrate on which a metal layer is formed. The masking member includes a mask portion in which a penetrating portion corresponding to the predetermined pattern is formed and a metal mesh as a conductive member that contacts the metal layer. The mask portion is made of an elastic material. The metal mesh is embedded in the mask portion such that a part of the metal mesh is exposed from a contact surface, which contacts the metal layer, of a surface of the mask portion.

Description

CROSS REFERENCE TO RELATED APPLICATIONS

The present application claims priority from Japanese patent application JP 2023-122575 filed on Jul. 27, 2023, the entire content of which is hereby incorporated by reference into this application.

BACKGROUND

Technical Field

The present disclosure relates to a masking member and a film forming apparatus for a metal film using the same.

Background Art

Conventionally, a metal film has been formed by precipitating metal on a surface of a substrate by electroplating (e.g., JP 2016-125087 A). A film forming apparatus of JP 2016-125087 A includes a container (housing) for containing a plating solution. An opening is formed in the container and is shielded with an electrolyte membrane. The film forming apparatus further includes a pressing mechanism that presses a substrate by means of the electrolyte membrane with the hydraulic pressure of the plating solution.

Here, when a metal underlying layer in a predetermined pattern is formed on the surface of the substrate, voltage is applied between an anode and the substrate while pressing the substrate with the hydraulic pressure of the electrolyte membrane. In this manner, a metal film in a predetermined pattern can be formed on the underlying layer. However, when the underlying layer in a predetermined pattern is not formed on the substrate, use of a masking member shown in, for example, JP 2016-108586 A is also expected.

SUMMARY

Here, as shown in JP 2016-108586 A, in forming a metal film on a surface of a substrate on which a metal layer is formed, the surface of the substrate functions as a cathode for electroplating. In this case, a conducting jig for electrically connecting the metal layer on the surface of the substrate to a power source is disposed together with a masking member each time of film formation, which makes preparation work complicated. In addition, when the conducting jig is misaligned, the metal film could become uneven.

The present disclosure has been made in view of the foregoing, and provides a masking member capable of stably forming a metal film on a surface of a substrate, by having the surface of the substrate function as a cathode.

In view of the aforementioned problems, a masking member according to the present disclosure is a masking member for forming, by electroplating, a metal film in a predetermined pattern on a surface of a substrate on which a metal layer is formed, the masking member including: a mask portion in which a penetrating portion corresponding to the predetermined pattern is formed; and a conductive member that contacts the metal layer, in which the mask portion is made of an elastic material, and the conductive member is embedded in the mask portion such that a part of the conductive member is exposed from a contact surface, which contacts the metal layer, of a surface of the mask portion.

According to the present disclosure, the conductive member is embedded in the mask portion such that a part of the conductive member is exposed from the contact surface, which contacts the metal layer, of a surface of the mask portion. Thus, at the time of film formation, when the substrate is covered with the masking member, the conductive member and the metal layer of the substrate can be made conductive with each other. When the conductive member and the negative pole of the power source for plating are electrically connected with such a state, the surface of the metal layer of the substrate can function as a cathode where the metal film is formed. As a result, the metal film corresponding to the penetrating portion formed in the mask portion can be stably formed on the surface of the metal layer of the substrate.

In an embodiment, the conductive member is a metal mesh, and the metal mesh is embedded in the mask portion so as to be exposed from the mask portion on the contact surface. In another embodiment, the metal mesh is disposed so as to surround a periphery of the mask portion. In further another embodiment, the masking member includes a resin mesh for fixing the mask portion, on a side opposite to the contact surface across the metal mesh.

A film forming apparatus for a metal film, including the aforementioned masking member, will be disclosed. The film forming apparatus includes a container having an opening formed at a position facing the substrate, the opening covered with an electrolyte membrane with a plating solution contained in the container. The film forming apparatus includes a moving mechanism configured to move at least one of the container or the substrate so that the container and the substrate can be separated from and contact with each other via the masking member and a pressure increase mechanism configured to increase a hydraulic pressure of the plating solution contained in the container. The film forming apparatus includes an anode disposed at a position facing the electrolyte membrane in the container and a power source that applies voltage between the anode and the substrate, in which the masking member is disposed between the electrolyte membrane and the substrate, and the conductive member is made conductive with a negative pole of the power source at least at a time of film formation.

According to the present disclosure, a metal film can be stably formed on a surface of a substrate, by having the surface of the substrate function as a cathode.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a schematic cross-sectional view showing an example of a film forming apparatus including a masking member according to an embodiment of the present disclosure prior to forming a metal film;

FIG. 1B is a cross-sectional view explaining a state of the film forming apparatus of FIG. 1A at the time of film formation;

FIG. 2A is a schematic perspective view of a masking member shown in FIG. 1A as viewed from below;

FIG. 2B is a partially enlarged cross-sectional view taken along line A-A of FIG. 2A;

FIG. 2C is a partially enlarged cross-sectional view taken along line B-B of FIG. 2A;

FIG. 3A to FIG. 3D are schematic views for explaining a method for manufacturing the masking member according to the present embodiment;

FIG. 4A to FIG. 4D are schematic views for explaining a method for manufacturing the masking member according to the present embodiment;

FIG. 5A is an enlarged cross-sectional view showing a state of the metal film corresponding to FIG. 2B at the time of film formation; and

FIG. 5B is an enlarged cross-sectional view showing a state of the metal film corresponding to FIG. 2C at the time of film formation.

DETAILED DESCRIPTION

First, a film forming apparatus 1 including a masking member 60 according to an embodiment of the present disclosure will be described with reference to FIG. 1A and FIGS. 2A to 2C.

As shown in FIG. 1A, the film forming apparatus 1 is a film forming apparatus for forming, by electroplating, a metal film F in a predetermined pattern P on a substrate B. The film forming apparatus 1 forms the metal film, with the masking member 60 sandwiched between an electrolyte membrane 13 and the substrate B. The film forming apparatus 1 includes an anode 11, the electrolyte membrane 13, and a power source 14 that applies voltage between the anode 11 and the substrate B.

The film forming apparatus 1 includes a container 15 containing the anode 11 and a plating solution L, a mount base 40 on which the substrate B is placed, and the masking member 60. At the time of film formation, the masking member 60 is placed on the mount base 40 together with the substrate B. The electrolyte membrane 13 is disposed between the masking member 60 and the anode 11.

The film forming apparatus 1 includes a linear actuator 70 that raises and lowers the container 15. The linear actuator 70 corresponds to a “moving mechanism” of the present disclosure, and may be any device that moves at least one of the container 15 or the substrate B so that the container 15 and the substrate B can be separated from and contact with each other via the masking member 60 described later.

The substrate B functions as a cathode. The substrate B is a plate-shaped substrate. In the present embodiment, the substrate B is a rectangular board. A facing surface, which faces the electrolyte membrane 13, of the surface of the substrate B is a film-forming surface that functions as the cathode. In the present embodiment, the substrate B in which a metal layer Ba is formed on a surface of an insulating board Bb is used (see FIG. 5A). The insulating board Bb is made of, for example, glass, ceramic, resin, or a composite material thereof, and is made of an electrically insulating material. The metal layer Ba may be made of metal such as aluminum or copper.

In the present embodiment, since a wiring pattern is formed from the metal film F, a substrate in which the metal layer Ba of copper or the like is formed on the surface of the insulating board Bb of resin or the like is used as the substrate B. In this case, after the metal film F is formed, the metal layer Ba excluding a portion on which the metal film F is formed is removed by etching or the like. In this manner, the pattern (wiring pattern) P with the metal film F can be formed on the surface of the insulating board Bb.

The anode 11 is, as an example, a non-porous (e.g., having no pores) anode made of the same metal as that of the metal film. The anode 11 has a block-like or a plate-like shape. Examples of the material of the anode 11 may include copper. The anode 11 dissolves upon application of voltage from the power source 14. However, when the film is formed only with metal ions of the plating solution L, the anode 11 is insoluble in the plating solution L. The anode 11 is electrically connected to the positive pole of the power source 14. The negative pole of the power source 14 is electrically connected to a metal plug 42 of the mount base 40 described later.

The plating solution L is a liquid containing metal in an ionic form of the metal film to be formed. Examples of the metal may include copper or nickel. The plating solution L is a solution of these metals dissolved (ionized) with acid such as a nitric acid, a phosphoric acid, or a sulfuric acid. Examples of solvent of the solution may include water or alcohol. When the metal is copper, for example, examples of the plating solution L may include an aqueous solution containing copper sulfate, copper pyrophosphate, and the like.

The electrolyte membrane 13 is a membrane that can be impregnated with (contain) the metal ions together with the plating solution L when contacted with the plating solution L. The electrolyte membrane 13 is a flexible membrane. The electrolyte membrane 13 is not particularly limited as long as it allows the metal ions of the plating solution L to move toward the substrate B upon application of voltage by the power source 14. Examples of the material of the electrolyte membrane 13 may include a fluorine-based resin having an ion-exchange function, such as Nafion® manufactured by DuPont Corporation. The film thickness of the electrolyte membrane 13 may be in a range of 20 μm to 200 μm.

The container 15 is made of a material that is insoluble in the plating solution L. A storing space 15a for containing the plating solution L is formed in the container 15. The anode 11 is disposed in the storing space 15a of the container 15. An opening 15d is formed in the storing space 15a at a position facing the substrate B. The opening 15d of the container 15 is covered with the electrolyte membrane 13. Specifically, the periphery of the electrolyte membrane 13 is sandwiched between the container 15 and a frame 17. This allows the plating solution L in the storing space 15a to be sealed with the electrolyte membrane 13.

As shown in FIG. 1A and FIG. 1B, the linear actuator 70 raises and lowers the container 15 so that the electrolyte membrane 13 and the masking member 60 can freely contact with and be separated from each other. In the present embodiment, the mount base 40 is fixed, and the container 15 is raised and lowered by the linear actuator 70. The linear actuator 70 is an electric actuator and converts a rotational motion of a motor into a linear motion by means of a ball screw or the like (not shown). However, a hydraulic or a pneumatic actuator may be used in place of the electric actuator.

A supply port 15b for supplying the plating solution L to the storing space 15a is formed in the container 15. A discharge port 15c for discharging the plating solution L from the storing space 15a is formed in the container 15. The supply port 15b and the discharge port 15c are holes that communicate with the storing space 15a. The supply port 15b and the discharge port 15c are formed across the storing space 15a. The supply port 15b is fluidly connected to a liquid supply pipe 50. The discharge port 15c is fluidly connected to a liquid discharge pipe 52.

The film forming apparatus 1 further includes a tank 90, the liquid supply pipe 50, the liquid discharge pipe 52, and a pump 80. As shown in FIG. 1A, the tank 90 contains the plating solution L. The liquid supply pipe 50 connects the tank 90 and the container 15. The liquid supply pipe 50 is provided with the pump 80. The pump 80 supplies the plating solution L from the tank 90 to the container 15. The liquid discharge pipe 52 connects the tank 90 and the container 15. The liquid discharge pipe 52 is provided with a pressure regulating valve 54. The pressure regulating valve 54 adjusts a pressure (hydraulic pressure) of the plating solution L in the storing space 15a to a predetermined pressure.

In the present embodiment, the plating solution L is sucked into the liquid supply pipe 50 from the tank 90 by driving the pump 80. The sucked plating solution L is pumped through the supply port 15b to the storing space 15a. The plating solution L in the storing space 15a is returned to the tank 90 via the discharge port 15c. In this manner, the plating solution L circulates inside the film forming apparatus 1.

Further, by continuing driving the pump 80, the hydraulic pressure of the plating solution L in the storing space 15a can be maintained at a predetermined pressure by means of the pressure regulating valve 54. The pump 80 is for pressing the masking member 60 with the electrolyte membrane 13 on which the hydraulic pressure of the plating solution L is exerted. The pump 80 is for increasing the hydraulic pressure of the plating solution L contained in the container 15 and corresponds to a “pressure increase mechanism” of the present disclosure.

The mount base 40 includes, as an example, a body 41 formed of an insulating material. In the body 41, a convex 43 projecting toward the mask is formed, and in the convex 43, a recess 44 for accommodating the substrate B is formed. The body 41 is provided with the metal plug 42 connected to the negative pole of the power source 14.

As shown in FIG. 1A, the masking member 60 includes a frame 61 and a screen mask 62. A periphery 62a of the screen mask 62 is securely fixed to the frame 61. Examples of the material of the frame 61 may include a metallic material such as stainless steel, or a resin material such as a thermoplastic resin. The frame 61 may be made of a metallic material and contacted with a metal mesh 67 described later. In this manner, the metal film F can be formed on the surface of the metal layer Ba only by connecting the frame 61 to the negative pole of the power source 14 without providing the mount base 40 with the metal plug 42.

As shown in FIG. 2A, a penetrating portion 68 corresponding to the predetermined pattern P of the metal film F is formed in the screen mask 62. The screen mask 62 includes a resin mesh 64, a mask portion 65, and the metal mesh 67. The screen mask 62 is a flexible mask having around 50 μm to 400 μm. The screen mask 62 is supported on the frame 61 on a side of the electrolyte membrane 13.

The resin mesh 64 is securely fixed to the frame 61. The resin mesh 64 has a plurality of openings 64c, 64c, . . . formed in a grid pattern. Specifically, as shown in FIG. 2B and the like, the resin mesh 64 is a mesh-like portion in which a plurality of oriented wires 64a, 64b is woven so as to intersect each other. The plurality of wires 64a, 64a is arranged at intervals from one another, and the plurality of wires 64b, 64b intersecting the plurality of wires 64a, 64a is arranged at intervals from one another. As a result, the plurality of openings 64c, 64c, . . . is formed in a grid pattern in the resin mesh 64. The material of the wires 64a, 64b is not particularly limited as long as the wires have corrosion resistance against the plating solution L. Examples of the material of the wires 64a, 64b may include a resin material such as polyester.

The mask portion 65 is securely fixed to the resin mesh 64. The penetrating portion 68 corresponding to the predetermined pattern P is formed in the mask portion 65. The mask portion 65 is a portion that adheres to the substrate B at the time of film formation by being pressed by the electrolyte membrane 13. The material of the mask portion 65 is not particularly limited as long as it can adhere to the substrate B. Examples of the material of the mask portion 65 may include a rubber material such as silicone rubber (PMDS) or ethylene propylene diene rubber (EPDM). The hardness of the rubber material may be equal to or smaller than HS100, or equal to or smaller than HS50 in Shore A hardness.

The mask portion 65 is made of an elastic material that is compressively elastically deformed by being pressed by the electrolyte membrane 13. In order to secure the adhesion to the substrate B, the deformation amount in the thickness direction (pressing direction) of the mask portion 65 due to the pressing by the electrolyte membrane 13 may be in a range of 5 to 20% of the thickness of the mask portion before deformation. The screen mask 62 having the predetermined pattern P can be manufactured by a typical silk screen manufacturing technique using an emulsion.

As shown in FIG. 2C, the metal mesh 67 as a conductive member is disposed on a contact surface 65a, which contacts the metal layer Ba of the substrate B, of the surface of the mask portion 65. The metal mesh 67 is made of wires 67a, 67b of stainless-steel, nickel, titanium, gold, copper, silver, palladium, and the like. The metal mesh 67 is a mesh in the same structure as that of the resin mesh 64. The metal mesh 67 has a plurality of openings 67c, 67c, . . . formed in a grid pattern. The plurality of wires 67a, 67a is arranged at intervals from one another, and the plurality of wires 67b, 67b intersecting the plurality of wires 67a, 67a is arranged at intervals from one another. As a result, the plurality of openings 67c, 67c, . . . is formed in a grid pattern in the metal mesh 67. In the present embodiment, an elastic material constituting the mask portion 65 fills the openings 67c. Thus, the metal mesh 67 is fixed to the mask portion 65.

In this manner, the metal mesh 67 is embedded in the mask portion 65 so as to be exposed from the mask portion 65 on the contact surface 65a of the mask portion 65. As shown in FIG. 2A, the metal mesh 67 is disposed so as to surround a periphery of the mask portion 65. Thus, since the metal mesh 67 is disposed so as to entirely surround the penetrating portion 68 of the mask portion 65, the metal film F in a pattern corresponding to the penetrating portion 68 can be uniformly formed. Further, the masking member 60 includes the resin mesh 64 for fixing the mask portion 65, on a side opposite to the contact surface 65a across the metal mesh 67. In this manner, an elastic portion 65b of the mask portion 65 is disposed between the resin mesh 64 and the metal mesh 67 so that the metal mesh 67 can be made to follow the surface of the metal layer Ba of the substrate B.

A method for manufacturing such a masking member 60 will be described. First, the frame 61 to which the resin mesh 64 is securely fixed is prepared. Then, the screen mask 62 is coated with an uncured UV curable resin 82A using a roller or a brush. Next, as shown in FIG. 3A, the ultraviolet curing resin (emulsion) is irradiated with the ultraviolet ray UV in accordance with the predetermined pattern P to form a cured portion 82 corresponding to the predetermined pattern. Then, an uncured portion 82a is washed away to form a forming space 82b for forming the mask portion 65 as shown in FIG. 3B. Next, as shown in FIG. 3C, a resin plate 85 is disposed, and a material 65A that becomes the mask portion 65 is poured into the forming space 82b and the resin mesh 64 is impregnated with the material 65A. The metal mesh 67 is disposed in the material 65A so as to be impregnated with a part of the material 65A. Finally, as shown in FIG. 3D, the material 65A is cured to form the mask portion 65. Further, the resin plate 85 is removed from the mask portion 65 and the cured portion 82 is removed by etching. As a result, the masking member 60 shown in FIG. 2A and the like can be obtained.

Another method for manufacturing the masking member 60 will be described. As shown in FIG. 4A, the UV curable resin (emulsion) 82A is irradiated with the ultraviolet ray UV in accordance with the predetermined pattern P to form the cured portion 82 corresponding to the predetermined pattern. Next, as shown in FIG. 4B, the uncured portion 82a is washed away and the resin plate 85 is disposed together with the metal mesh 67. Then, as shown in FIG. 4C, the material 65A that becomes the mask portion 65 is poured into the forming space 82b. Finally, as shown in FIG. 4D, the material 65A is cured to form the mask portion 65. Further, the resin plate 85 is removed from the mask portion 65 and the cured portion 82 is removed by etching. As a result, the masking member 60 shown in FIG. 2A and the like can be obtained.

Referring to FIG. 1 and FIG. 5, a method for film forming using the film forming apparatus 1 will be described. First, as shown in FIG. 1A, the substrate B is disposed on the mount base 40. In the present embodiment, in a state of the substrate B being accommodated in the recess 44, the metal layer Ba of the substrate B projects from the mount base 40. Thus, the mask portion 65 of the masking member 60 can be uniformly contacted with the surface of the substrate B.

Next, the masking member 60 is disposed on the mount base 40. At this time, the masking member 60 is accommodated such that the surface of the substrate B fits within an interior space 69 of the frame 61 of the masking member 60. Note that in this manner, the surface of the substrate B is covered with the mask portion 65 of the masking member 60.

Next, as shown in FIG. 1B, the linear actuator 70 is driven. The container 15 is lowered toward the masking member 60. Note that when the masking member 60 is integrally attached to the container 15 at a position facing the electrolyte membrane 13, the surface of the substrate B can be covered with the mask portion 65 of the masking member 60 by lowering the container 15.

Next, the pump 80 is driven, thereby supplying the plating solution L to the storing space 15a of the container 15. Since the liquid discharge pipe 52 is provided with the pressure regulating valve 54, the hydraulic pressure of the plating solution L in the storing space 15a is maintained at a predetermined pressure.

Such pressing allows the screen mask 62 to adhere to the metal layer Ba of the substrate B. Since the mask portion 65 is made of an elastic material, the mask portion 65 is compressively elastically deformed by the hydraulic pressure of the plating solution L, so that the adhesion between the mask portion 65 and the substrate B is improved. Since the mask portion 65 is securely fixed to the resin mesh 64, the mask portion 65 can be uniformly pressed via the resin mesh 64, as shown in FIG. 5A. When the pressing by the electrolyte membrane 13 is continued, the penetrating portion 68 formed in the screen mask 62 is filled with a leachate (plating solution) La exuded from the electrolyte membrane 13 swollen by the plating solution L.

Next, the metal film F is formed while maintaining the pressing state by the electrolyte membrane 13. Specifically, voltage is applied between the anode 11 and the substrate B. In the present embodiment, a part of the metal mesh 67 is exposed from the contact surface 65a, which contacts the metal layer Ba, of the surface of the mask portion 65. Thus, as shown in FIG. 5B, at the time of film formation, with the substrate B covered with the masking member 60, the metal layer Ba of the substrate B and the metal plug 42 can be made conductive with each other via the metal mesh 67. When the metal mesh 67 and the negative pole of the power source 14 for plating are electrically connected via the metal plug 42, current A of the power source 14 flows from the metal layer Ba through the metal mesh 67 to the metal plug 42. In this manner, the surface of the metal layer Ba of the substrate B can function as the cathode where the metal film F is formed. Thus, the metal ions contained in the plating solution L are made to pass through the electrolyte membrane 13. The metal ions that have passed through the electrolyte membrane 13 move through the leachate La to the surface of the substrate B and are reduced on the surface of the substrate B. As a result, the metal film F corresponding to the penetrating portion 68 formed in the mask portion 65 can be stably formed on the surface of the metal layer Ba of the substrate B.

Further, since the leachate La is uniformly pressurized with the pressing by the electrolyte membrane 13, the uniform metal film F can be formed. Subsequently, the linear actuator 70 raises the container 15 to detach the substrate B from the electrolyte membrane 13 and removes the substrate B from the mount base 40. Note that when a wire is manufactured with the metal film F, the metal layer Ba formed on the surface of the insulating board Bb of the substrate B may be etched so as to maintain a portion where the metal film F is formed.

In the case where the masking member 60 is integrally attached to the container 15 as described above, when the linear actuator 70 raises the container 15 to detach the substrate B from the electrolyte membrane 13, the weight of the plating solution L can be supported by the masking member 60 via the electrolyte membrane 13. In this manner, it is possible to suppress plastic deformation of the electrolyte membrane 13 due to the weight of the plating solution L.

Although the embodiments of the present disclosure have been described in detail above, the present disclosure is not limited to the above-described embodiments, and various design changes can be made within the scope without departing from the spirit of the present disclosure described in the claims. For example, the conductive member such as metallic foil may be used in place of the metal mesh as long as it can be contacted with the metal layer of the substrate. In place of the metal mesh, metallic foil in a grid structure in which a plurality of through-holes is formed may be used. In place of the resin mesh, a conductive mesh may be used, in which case the conductive mesh may be embedded in the mask portion such that the surface of the conductive mesh is not exposed.

Claims

1. A masking member for forming, by electroplating, a metal film in a predetermined pattern on a surface of a substrate on which a metal layer is formed, the masking member comprising: a mask portion in which a penetrating portion corresponding to the predetermined pattern is formed; anda conductive member disposed on a contact surface that contacts the metal layer,whereinthe mask portion is made of an elastic material, andthe conductive member is embedded in the mask portion such that a part of the conductive member is exposed from the contact surface, which contacts the metal layer, of a surface of the mask portion.

2. The masking member according to claim 1, wherein the conductive member is a metal mesh, andthe metal mesh is embedded in the mask portion so as to be exposed from the mask portion on the contact surface.

3. The masking member according to claim 2, wherein the metal mesh is disposed so as to surround a periphery of the mask portion.

4. The masking member according to claim 2, wherein the masking member comprises a resin mesh for fixing the mask portion, on a side opposite to the contact surface across the metal mesh.

5. A film forming apparatus for a metal film, including the masking member according to claim 1, the film forming apparatus comprising: a container having an opening formed at a position facing the substrate, the opening covered with an electrolyte membrane with a plating solution contained in the container;a moving mechanism configured to move at least one of the container or the substrate so that the container and the substrate can be separated from and contact with each other via the masking member;a pressure increase mechanism configured to increase a hydraulic pressure of the plating solution contained in the container;an anode disposed at a position facing the electrolyte membrane in the container; anda power source that applies voltage between the anode and the substrate,whereinthe masking member is disposed between the electrolyte membrane and the substrate, andthe conductive member is made conductive with a negative pole of the power source at least at a time of film formation.