Post-treatment method for plated substrates

Abstract

To provide a post-treatment method for a plated substrate in which discoloration of a metallic film formed on the plated substrate can be suppressed.SOLUTION: A post-treatment method for a plated substrate BA includes: detecting a state of a liquid membrane LM of a plating solution L, which has adhered onto a film deposition surface fa including a metallic film F on the plated substrate BA at the time of film formation; determining whether the liquid membrane LM is formed all over the film deposition surface fa including the metallic film F on the basis of the state of the liquid membrane LM; and applying the plating solution L onto the film deposition surface fa so that the liquid membrane LM can be formed all over the film deposition surface fa, when determined that the liquid membrane LM is not formed all over the film deposition surface fa.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a method for post-treating a plated substrate, in which a plated substrate having a metal film formed on its surface is subjected to post-treatment while being transported. [Background technology]

[0002] Conventionally, there have been proposed film formation devices that deposit metal on the surface of a substrate to form a metal film (for example, Patent Document 1). In Patent Document 1, the film formation device includes a container that contains a plating solution. The container has an opening that is sealed with an electrolyte membrane. With this film formation device, a metal film is formed on the surface to be formed by electroplating while the hydraulic pressure of the plating solution is applied to the surface to be formed of the substrate via the electrolyte membrane, thereby producing a plated substrate. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-48210 Summary of the Invention [Problem to be solved by the invention]

[0004] However, when a film is formed using the film formation apparatus described in Patent Document 1, the plating solution that has permeated the electrolyte membrane may adhere to the plating substrate. According to the inventor's findings, if the plating solution is not uniformly adhered to the plating substrate, the metal film on the plating substrate may become discolored.

[0005] The present invention has been made in view of these problems, and its object is to provide a post-treatment method for plated substrates that can suppress discoloration of a metal coating formed on the plated substrate. [Means for solving the problem]

[0006] In view of the above-mentioned problems, the present invention provides a post-treatment method for a plated substrate, which includes a step of transporting a plated substrate having a metal film formed on a film-forming surface thereof by electrolytic plating while applying hydraulic pressure of a plating solution to the film-forming surface of the substrate via an electrolyte membrane. The post-treatment method includes a detection step of detecting a state of a liquid film of plating solution that has adhered to a film-forming surface of the plated substrate, including the metal film, during film formation, a determination step of determining, based on the state of the liquid film, whether the liquid film has formed on the entire film-forming surface, including the metal film, and, if it is determined that the liquid film has not formed on the entire film-forming surface, a coating step of applying the plating solution to the film-forming surface so that the liquid film is formed on the entire film-forming surface. [Effects of the Invention]

[0007] According to the present invention, if it is determined in the determination step after film formation that a liquid film has not been formed over the entire film-forming surface, a plating solution is applied to the film-forming surface in the application step so that a liquid film is formed over the entire film-forming surface. This allows a liquid film of the plating solution to be formed over the entire film-forming surface, including the metal coating, thereby preventing discoloration of the metal coating. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1A is a schematic cross-sectional view showing an example of a metal film forming apparatus according to an embodiment of the present invention, and FIG. 1B is a diagram for explaining a method of forming a metal film using the film forming apparatus shown in FIG. [Figure 2] 1(a) to 1(i) are diagrams for explaining a method for post-treating a substrate to be plated, and are diagrams for explaining a method for cleaning a substrate to be plated and a method for recovering a plating solution. [Figure 3] FIG. 10 is a table illustrating a method for removing a plating solution. DETAILED DESCRIPTION OF THE INVENTION

[0009] A method for post-processing a plated substrate will now be described with reference to Figures 1 to 3. First, a metal film forming apparatus 1 according to an embodiment of the present invention will be described.

[0010] 1. About the deposition equipment 1 As shown in Fig. 1(a), the film formation apparatus 1 is a film formation apparatus that forms a metal film F on a substrate B by electrolytic plating. Specifically, as shown in Fig. 1(b), the film formation apparatus 1 forms the metal film F in a state in which an electrolyte membrane is pressed against the surface of the substrate by the hydraulic pressure of a plating solution. The film formation apparatus 1 includes an anode 11, an electrolyte membrane 13, and a power source 14 that applies a voltage between the anode 11 and the substrate B.

[0011] The film forming apparatus 1 further includes a container 15, a mounting table 40, and a linear actuator 70. For ease of explanation, this embodiment is based on the premise that the electrolyte membrane 13 is disposed below the anode 11, and the substrate B is disposed further below that. However, the positional relationship is not limited to this as long as the metal film F can be formed on the surface of the substrate B.

[0012] Substrate B functions as a cathode. The material of substrate B is not particularly limited as long as it functions as a cathode (i.e., a surface having electrical conductivity). Substrate B may be made of a metal material such as aluminum or copper. When forming a wiring pattern from a metal coating F, substrate B is a substrate in which a base layer of copper or the like is formed on the surface of an insulating substrate such as a resin. In this case, after forming the metal coating F, the base layer other than the portion on which the metal coating F is formed is removed by etching or the like. This allows a wiring pattern made of metal coating F to be formed on the surface of the insulating substrate.

[0013] The anode 11 is, for example, a non-porous anode made of the same metal as the metal of the metal coating. The anode 11 has a block or flat plate shape. However, the anode 11 may also be porous, mesh, or a cage containing balls. Examples of materials for the anode 11 include copper. The anode 11 dissolves when a voltage is applied from the power source 14. However, when forming a film using only metal ions of the plating solution L, the anode 11 is an anode that is insoluble in the plating solution L. The anode 11 is electrically connected to the positive electrode of the power source 14. The negative electrode of the power source 14 is electrically connected to the substrate B via the mounting table 40.

[0014] The plating solution L is a solution containing the metal of the metal coating to be formed in an ionic state. Examples of such metals include copper, nickel, gold, and silver. The plating solution L is a solution in which these metals are dissolved (ionized) in an acid such as nitric acid, phosphoric acid, succinic acid, sulfuric acid, sulfamic acid, or pyrophosphoric acid. Examples of the solvent for the solution include water and alcohol. For example, when the metal is copper, the plating solution L can be an aqueous solution containing copper sulfate, copper pyrophosphate, or the like.

[0015] The electrolyte membrane 13 is a membrane that can be impregnated (contained) with metal ions along with the plating solution L by contacting it with the plating solution L. The electrolyte membrane 13 is a flexible membrane. The material of the electrolyte membrane 13 is not particularly limited as long as it allows the metal ions of the plating solution L to migrate to the substrate B side when a voltage is applied from the power source 14. Examples of materials for the electrolyte membrane 13 include resins with ion exchange properties, such as fluororesins such as Nafion (registered trademark) manufactured by DuPont. The thickness of the electrolyte membrane is preferably in the range of 5 μm to 200 μm. More preferably, the thickness is in the range of 20 μm to 60 μm.

[0016] The container 15 is made of a material that is insoluble in the plating solution L. The container 15 has a container space 15a that contains the plating solution. The anode 11 is disposed in the container space 15a of the container 15. An opening 15d is formed on the side of the container space 15a facing the substrate B. The opening 15d of the container 15 is covered with an electrolyte membrane 13. Specifically, the periphery of the electrolyte membrane 13 is sandwiched between the container 15 and the frame 17. This allows the plating solution L in the container space 15a to be sealed by the electrolyte membrane 13.

[0017] The container 15 includes a supply port 15b that supplies the plating solution L to the container space 15a. The container 15 further includes a discharge port 15c that discharges the plating solution L from the container space 15a. The supply port 15b and the discharge port 15c are holes that communicate with the container space 15a. The supply port 15b and the discharge port 15c are arranged on either side of the container space 15a. The supply port 15b is connected to a liquid supply pipe 50. The discharge port 15c is fluidly connected to a liquid discharge pipe 52.

[0018] The film forming apparatus 1 further includes a liquid tank 90, a liquid supply pipe 50, a liquid discharge pipe 52, and a pump 80. As shown in FIG. 1 , the liquid tank 90 contains a plating solution L. The liquid supply pipe 50 connects the liquid tank 90 to the accommodation body 15. The liquid supply pipe 50 is provided with a pump 80. The pump 80 supplies the plating solution L from the liquid tank 90 to the accommodation body 15. The liquid discharge pipe 52 connects the liquid tank 90 to the accommodation body 15. The liquid discharge pipe 52 is provided with a pressure adjustment valve 54. The pressure adjustment valve 54 adjusts the pressure (liquid pressure) of the plating solution L in the accommodation space 15a to a predetermined pressure.

[0019] In this embodiment, the plating solution L is sucked from the liquid tank 90 into the liquid supply pipe 50 by driving the pump 80. The sucked plating solution L is pressure-fed from the supply port 15b to the accommodation space 15a. The plating solution L in the accommodation space 15a is returned to the liquid tank 90 via the discharge port 15c. In this manner, the plating solution L circulates within the film forming apparatus 1.

[0020] By continuing to drive the pump 80, the liquid pressure of the plating solution L in the accommodation space 15a can be maintained at a predetermined pressure by the pressure regulating valve 54. Instead of the pump 80, the liquid pressure of the plating solution L may be applied by a piston and cylinder that injects the plating solution.

[0021] The mounting table 40 is made of, for example, a conductive material (for example, metal). A recess 41 is formed in the mounting table 40. The recess 41 is a recess for accommodating the substrate B.

[0022] 2. Film formation method First, the substrate B is placed on the mounting table 40. If a metal film F has been formed on the substrate B, the substrate B is replaced. Next, the linear actuator 70 is driven to lower the housing body 15 until the electrolyte membrane 13 attached to the housing body 15 comes into contact with the substrate B.

[0023] Next, the pump 80 is driven to supply the plating solution L into the accommodation space 15a of the accommodation body 15. Since the pressure regulating valve 54 is provided in the liquid discharge pipe 52, the liquid pressure of the plating solution L in the accommodation space 15a is maintained at a predetermined pressure. As a result, as shown in FIG. 1(b), the liquid pressure of the plating solution L can press the electrolyte membrane 13 against the substrate B.

[0024] Next, while maintaining the pressure applied by the electrolyte membrane 13, a metal coating F is formed. Specifically, a voltage is applied between the anode 11 and the substrate B. This causes the metal ions contained inside the electrolyte membrane 13 to migrate to the surface of the substrate B, where they are reduced. When manufacturing wiring using the metal coating F, it is sufficient to etch the conductive base layer formed on the surface of the insulating substrate. In this way, the plated substrate BA can be manufactured. The plating solution L and the substrate B may be heated during film formation.

[0025] Next, the pump 80 is stopped, and the plating solution L in the accommodation space 15a of the accommodation body 15 is replaced with air (atmosphere). Here, for example, compressed air may be sent to the accommodation space 15a using an air pump (not shown). Alternatively, a valve (not shown) of a drain pipe (not shown) connecting the accommodation space 15a to the atmosphere may be opened. Next, the linear actuator 70 is driven to raise the accommodation body 15 (see FIG. 2(a)). In this way, a metal coating F is formed on the deposition surface Ba of the plating substrate BA by electroplating, with the liquid pressure of the plating solution L acting on the deposition surface Ba of the substrate B via the electrolyte membrane 13.

[0026] As shown in FIG. 2(a), plating solution L may seep out from the electrolyte membrane 13 onto the surface (film formation surface fa) of the manufactured plating substrate BA during film formation. As a result, the plating solution L that seeps out from the electrolyte membrane 13 may adhere to the plating substrate BA. If the plating solution L is not uniformly adhered to the plating substrate BA, the metal coating F to which the plating solution L does not adhere may become discolored. This phenomenon is particularly noticeable when the plating solution L or the substrate B is heated during film formation.

[0027] 2(a) to 2(i), a processing method is performed on the plating substrate BA while it is being transported by a conveyor 60. First, in this post-processing method, the plating substrate BA is removed from the mounting table 40 and placed on the conveyor 60, as shown in FIG.

[0028] Next, as shown in FIG. 2(c), the state of the liquid film LM of the plating solution L that adhered to the film-forming surface fa of the plating substrate BA, which includes the metal film F, during film formation is detected (detection step). Specifically, the film-forming surface fa of the plating substrate BA is imaged by an imaging device 31. This allows the state of the liquid film LM of the plating solution L that adhered during film formation to be detected from the image of the film-forming surface fa by the imaging device 31. The "film-forming surface fa of the plating substrate BA" refers to the surface that includes the metal film F, and specifically refers to the surface of the metal film F and the surface of the substrate B exposed from the metal film F that faces the electrolyte membrane 13.

[0029] Next, based on the state of the liquid film LM of the plating solution L, it is determined whether or not the liquid film LM has been formed over the entire film-forming surface fa, including the metal film F (determination step). If it is determined that the liquid film LM has not been formed over the entire film-forming surface fa, the plating solution L is applied to the film-forming surface fa so that the liquid film LM is formed over the entire film-forming surface fa, as shown in Figures 2(d) and 2(e) (application step). Note that if the liquid film LM has been formed over the entire film-forming surface fa of the plating substrate BA, the state is as shown in Figure 2(e), and therefore application of the plating solution L is not performed. As a result, the liquid film LM of the plating solution L is formed over the entire film-forming surface fa, including the metal film F, and discoloration of the metal film F can be suppressed.

[0030] 2(f), after the application of the plating solution L (application step), and before the plating substrate BA is washed with water (water-rinsing step) described later, the plating solution L derived from the liquid film LM formed on the entire film-forming surface fa of the plating substrate BA is recovered from the film-forming surface fa of the plating substrate BA (recovery step). For example, the recovery of the plating solution L from the film-forming surface fa of the plating substrate BA is performed using a recovery mechanism 33, and the plating solution L is recovered in a recovery tank 61.

[0031] As shown in Fig. 3, the recovery mechanism 33 may include a suction mechanism 33A, a blow mechanism 33B, an absorbing member 33C, or a spin mechanism 33D. For example, as shown in Fig. 3, the suction mechanism 33A may use a suction pump (not shown) as a drive source to suck the plating solution L from the film formation surface fa of the plating substrate BA through a head 33a connected to the suction pump. In this case, the sucked plating solution L can be recovered into a recovery tank 61 by the suction pump.

[0032] In another embodiment, the blow mechanism 33B may blow air onto the film-forming surface fa of the plating substrate BA to blow off the plating solution L adhering to the film-forming surface fa, and the blown-off plating solution L may be recovered in the recovery tank 61.

[0033] In another embodiment, an absorbing member 33C containing a foamed resin such as a urethane sponge may be brought into contact with the film-forming surface fa, and the plating solution L adhering to the film-forming surface fa may be absorbed by the absorbing member 33C, and the plating solution L absorbed by the absorbing member 33C may then be recovered in the recovery tank 61.

[0034] In another embodiment, the plating substrate BA may be rotated using a spin mechanism 33D (for example, a spin coater MS-B100 manufactured by Mikasa Co., Ltd.), and the plating solution L adhering to the film formation surface fa may be blown off by centrifugal force, and the blown-off plating solution L may be recovered in a recovery tank 61.

[0035] As a result of experiments conducted by the inventors using these methods, the recovery rate of plating solution L by the suction mechanism 33A and the blow mechanism 33B was 99%, the recovery rate of plating solution L by the absorbing member 33C was 95%, and the recovery rate of plating solution L by the spin mechanism was 90% or more.

[0036] In this embodiment, based on experiments by the inventors, when the metal coating F is a copper coating, it is preferable to recover the plating solution L so that the thickness of the liquid film LM on the film-forming surface fa of the plating substrate BA does not become less than 60 μm. This makes it possible to secure the liquid film LM of the plating solution L and prevent the entire metal coating F from discoloring. By using the above-described absorbing member 33C, it is easy to secure the above-described range of the thickness of the liquid film LM of the plating solution L.

[0037] Next, as shown in FIG. 2(g), the plating solution L is recovered in a recovery tank 61. The recovered plating solution L is passed through a filter 63 by driving a pump 62 and sent to a liquid tank 90, where it can be reused. Meanwhile, as shown in FIG. 2(h), after the plating solution L has been applied (application step), the entire film-forming surface fa of the plating substrate BA is washed with cleaning water C via a cleaning device 34. After washing with cleaning water C (water-rinsing step), as shown in FIG. 2(i), air is blown onto the surface of the plating substrate BA using a blowing device 35 to dry the entire film-forming surface fa.

[0038] In this way, as shown in Figure 2(d), by applying plating solution L to the film-forming surface fa of the plating substrate BA, it is possible to prevent partial discoloration of the metal film F, and as shown in Figure 2(f), it is possible to secure a liquid film LM of plating solution L and prevent overall discoloration of the metal film F. Furthermore, by collecting the plating solution L attached to the film-forming surface fa of the plating substrate BA, the plating solution L can be regenerated in a filter 63 and reused, thereby reducing the amount of plating solution L discharged.

[0039] (Reference example) The following test was conducted to confirm whether or not discoloration due to the plating solution occurred. First, a test specimen (plated substrate) was prepared without any plating solution attached. Specifically, a 10 μm thick copper film (metal film) was formed on a 100 mm × 100 mm × 0.3 mm thick Hull Cell copper plate (manufactured by Yamamoto Plating Tester) substrate using the film formation device shown in Figure 1. After film formation, the test specimen was washed with water and dried immediately after film formation to prevent discoloration of the copper film. The weight of this test specimen was measured.

[0040] To simulate the plating solution remaining after film formation, a plating solution consisting of an aqueous solution of copper sulfate was applied to the film surface using a micropipette at a rate of 0.02 mL / cm. 2 The plating solution was dropped, and the test piece was tilted to spread the plating solution over the entire surface of the film formation surface.

[0041] The plating solution adhering to the film-forming surface of the plating substrate was collected using the suction mechanism 33A shown in Figure 3. During this process, the thickness of the plating solution liquid film was varied. Specifically, the weight of the plating solution adhering to the test specimen was calculated from the weight of the test specimen, and the thickness of the plating solution liquid film was calculated from this weight of the plating solution adhering to the test specimen. The results are shown in Table 1. Note that the thickness of the plating solution liquid film, 200 μm, is the thickness of the plating solution liquid film before the plating solution was suctioned. After leaving the test specimen for a certain period of time, the test specimen was washed with water immediately after film formation and dried to prevent further discoloration of the copper film, and the discoloration of the copper film was confirmed. The results are shown in Table 1.

[0042] [Table 1]

[0043] The results in Table 1 show that when recovering the plating solution, discoloration of the entire metal film can be avoided by recovering the plating solution so that the thickness of the plating solution film does not become less than 60 μm.

[0044] Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above-described embodiments, and various design modifications can be made without departing from the spirit of the present invention as set forth in the claims. [Explanation of symbols]

[0045] B: Substrate, Ba: Surface to be coated, BA: Plated substrate, LM: Liquid film, F: Metal film, fa: Coating surface

Claims

1. A method for post-treating a plated substrate, comprising: carrying a plated substrate having a metal film formed on a film-forming surface of the substrate by electrolytic plating in a state in which hydraulic pressure of a plating solution is applied to the film-forming surface of the substrate via an electrolyte membrane; and carrying the plated substrate while post-treating the plated substrate; The post-processing method includes: a detection step of detecting the state of a liquid film of plating solution that has adhered to a film-forming surface of the plating substrate, including the metal film, during film formation; a determining step of determining whether the liquid film is formed on the entire film-forming surface including the metal coating based on the state of the liquid film; a coating step of coating the plating solution on the film formation surface so that the liquid film is formed on the entire film formation surface when it is determined that the liquid film is not formed on the entire film formation surface; A method for post-treating a plated substrate, comprising:

2. The post-processing method includes: a water washing step of washing the entire film-forming surface with water after the coating step; The method for post-treating a plated substrate according to claim 1 , further comprising a drying step of drying the entire film-forming surface after the water-washing step.

3. 3. The post-treatment method for a plated substrate according to claim 2, further comprising a recovery step of recovering, from the film-forming surface, plating solution derived from the liquid film formed on the entire film-forming surface after the coating step and before the water-rinsing step.

4. the metal coating is a copper coating, 4. The method for post-treating a plated substrate according to claim 3, wherein the plating solution is recovered in the recovery step so that the thickness of the liquid film does not become less than 60 [mu]m.

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