Method for storing electrolyte membrane

Abstract

To provide a method for storing an electrolyte membrane that enables storage of the electrolyte membrane suitable for metal film deposition.SOLUTION: A storage method involves immersing a boiled electrolyte membrane 13 in a storage solution L, stirring the storage solution while monitoring conductivity of the storage solution L over time, and managing the storage status of the electrolyte membrane 13 based on the temporal variation of conductivity. The electrolyte membrane 13 is utilized during the process of metal film deposition onto a substrate by electrolytic plating while being in contact with the substrate.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a method for storing an electrolyte membrane used in a film forming apparatus for forming a metal film on a substrate.

Background Art

[0002] As this type of technology, for example, Patent Document 1 proposes a film forming apparatus for forming a metal film on a substrate. The film forming apparatus includes an electrolyte membrane, and forms a metal film on the substrate by electroplating in a state where the electrolyte membrane is in contact with the substrate.

Prior Art Document

Patent Document

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, before attaching the electrolyte membrane used in the film forming apparatus to the apparatus main body, it may be boiled in a boiling liquid such as pure water. As a result, the electrolyte membrane swells due to the boiling liquid and can permeate metal ions in the plating solution when electroplating is performed.

[0005] However, although the electrolyte membrane after boiling may be immersed in a storage liquid such as pure water for storage, if foreign matter is present in the storage liquid, foreign matter may adhere to the electrolyte membrane. When a metal film is formed using such an electrolyte membrane, there is a risk of film formation failure.

[0006] The present invention has been made in view of such points, and an object thereof is to provide a method for storing an electrolyte membrane that can store an electrolyte membrane suitable for forming a metal film.

Means for Solving the Problems

[0007] In view of the above problems, a method for storing an electrolyte membrane according to the present invention is a method for storing an electrolyte membrane used in a film-forming apparatus for forming a metal film on a substrate. The electrolyte membrane is attached to the apparatus main body of the film-forming apparatus and is used when forming the metal film on the substrate by electrolytic plating while being in contact with the substrate. In this storage method, while the boiled electrolyte membrane is immersed in a storage liquid, the conductivity of the storage liquid is monitored over time while stirring the storage liquid, and the storage state of the electrolyte membrane is managed based on the change in conductivity over time.

Advantages of the Invention

[0008] According to the present invention, by monitoring the conductivity of the storage liquid over time while stirring the storage liquid, it is possible to grasp the state in which foreign substances contained in the storage liquid adhere to the electrolyte membrane. Thereby, it is possible to store the electrolyte membrane suitable for forming the metal film.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Embodiments for Carrying Out the Invention

[0010] The method for storing an electrolyte membrane will be described below with reference to FIGS. 1 to 3. The storage method according to this embodiment is a method for storing the electrolyte membrane 13 used in a film-forming apparatus (not shown) that forms a metal film on a base material (not shown). The electrolyte membrane 13 is attached to the apparatus main body (not shown) of the film-forming apparatus and is used when forming a metal film on the base material by electrolytic plating while being in contact with the surface of the base material. Here, the apparatus main body has a structure in which an electrolytic solution is stored in a storage space together with an anode (not shown), and the electrolytic solution is sealed by the electrolyte membrane 13. During film formation, a voltage is applied between the anode and the base material with the electrolyte membrane 13 in contact with the base material. As a result, metal ions derived from the electrolytic solution pass through (permeate) the electrolyte membrane 13, and metal is deposited on the surface of the base material, which is the cathode. Thereby, a metal film can be formed on the surface of the base material.

[0011] Such an electrolyte membrane 13 is replaced according to the number of times of film formation of the metal film, etc. due to sagging caused by repeated use or adhesion of foreign substances on the surface. The replaced electrolyte membrane 13 is boiled in a boiling solution such as pure water in advance and stored in the storage liquid L in a swollen state. Foreign substances contained in the storage liquid L are likely to be adsorbed on the electrolyte membrane 13 immersed in the storage liquid L. Due to such adsorption of foreign substances, variations occur in the permeability of metal ions to the electrolyte membrane 13, and as a result, it is assumed that defects will occur in the metal film. From such a point, in this embodiment, the electrolyte membrane 13 is refrigerated together with the storage liquid L by the method shown below.

[0012] As shown in FIG. 1(a), in this management method, first, a boiled electrolyte membrane 13 is prepared. Specifically, as shown in FIG. 1(a), the electrolyte membrane 13 is boiled with a plurality (for example, six) of electrolyte membranes 13 attached to the frame body 40.

[0013] In this embodiment, the frame body 40 is in the shape of a rectangular parallelepiped and has four support columns 41. The support columns 41 are connected to each other by an upper long frame 42, an upper short frame 43, a lower long frame 44, and a lower short frame 45. A space S in which the stirrer 32 (see FIG. 1(b)) can move is formed at the lower part of the frame body 40.

[0014] In this embodiment, the electrolyte membranes 13 are attached inside the frame body 40 at intervals in the longitudinal direction of the frame body 40. Specifically, each electrolyte membrane 13 is attached to a pair of upper long frames 42, 42 and a pair of lower long frames 44, 44 by clips or the like. At this time, it is desirable that the electrolyte membranes 13 be attached to the frame body 40 so that no tension other than the self-weight of the electrolyte membranes 13 is generated (so that creep strain does not occur).

[0015] In this way, in the state shown in FIG. 1(a), when the frame body 40 and the electrolyte membranes 13 are put into a boiling liquid such as pure water heated to 70°C to 95°C, the electrolyte membranes 13 swell, and the electrolyte membranes 13 become more permeable to metal ions. Then, the electrolyte membranes 13 boiled in the boiling liquid are washed with water.

[0016] Next, a water tank 20 containing pure water as a storage liquid L is placed on the stirring device 30 shown in FIG. 1(b), and the electrolyte membranes 13 together with the frame body 40 shown in FIG. 1(a) are immersed in the storage liquid L contained in the water tank 20. At this time, the stirrer 32 is disposed in the space S at the lower part of the frame body 40. The stirrer 32 immersed in the boiling liquid in the water tank 20 is moved by magnetic force to stir the storage liquid L. When the inner wall surface of the water tank 20 has foreign matter attached thereto when the water tank 20 is washed, in such a case, the foreign matter contained in the storage liquid L may be captured by a capture electrolyte membrane before the electrolyte membranes 13 are immersed.

[0017] Incidentally, as shown in the waveform of the conductivity from time 0 to time TB in FIG. 2, it is known that the conductivity of the storage liquid L increases as foreign matter mixes into the storage liquid L. Thereafter (after time TB), the foreign matter in the storage liquid L is adsorbed onto the electrolyte membrane 13, the foreign matter contained in the storage liquid L decreases with the passage of time, and the conductivity of the storage liquid L also decreases. Therefore, at time TA and time TC shown in FIG. 2, the conductivity of the storage liquid L shows the same value, but the amount of foreign matter adsorbed onto the electrolyte membrane 13 is larger at time TC than at time TA. For this reason, in the present embodiment, the storage state of the electrolyte membrane 13 is managed by the conductivity of the storage liquid L at time TA.

[0018] Specifically, in the present embodiment, while the boiled electrolyte membrane 13 is immersed in the storage liquid L and the storage liquid L is stirred with a stirrer 32, the measuring portion of the conductivity measuring device 60 is immersed in the storage liquid L, and the conductivity of the storage liquid L is monitored over time (continuously). By this monitoring, the storage state of the electrolyte membrane 13 is managed based on the change in conductivity accompanying the change in time. Specifically, the electrolyte membrane 13 is used or the storage liquid L is replaced until foreign matter mixes into the storage liquid L and the value of the conductivity of the storage liquid L rises to the control value (between time 0 and TA), thereby reducing the mixing of foreign matter.

[0019] In the present embodiment, while stirring the storage liquid L, the conductivity of the storage liquid L is monitored over time, so that the foreign matter contained in the storage liquid L can be uniformly dispersed and more accurate management can be performed. In this way, the electrolyte membrane 13 suitable for forming the metal film can be stored.

[0020] The following confirmation tests were conducted. First, as a storage solution, water (conductivity 62 μS / cm) with foreign matter mixed in was prepared for pure water (conductivity 2 μS / cm), and an electrolyte membrane of 8 cm × 8 cm was immersed in 1 L of it. In this state, the conductivity of the water was measured over time. The results are shown in Figure 3. As shown in Figure 3, it was found that the conductivity of the water decreased after the electrolyte membrane was immersed in the water. This is considered to be due to the adsorption of foreign matter on the electrolyte membrane. From this, as described above, it was found that if the conductivity of the storage solution L is not continuously monitored after the electrolyte membrane is put into the storage solution L, an increase in foreign matter mixed in the storage solution L cannot be grasped. Furthermore, foreign matter was mixed into the above-mentioned pure water, and the conductivity of the water was measured depending on the presence or absence of stirring by the stirrer 32. As a result, when there was stirring, the conductivity of the water was 59.2 μS / cm, and when there was no stirring, the conductivity of the water was 52.5 μS / cm. From this result, in the case of no stirring, since foreign matter located at a position away from the conductivity measuring device 60 is not detected, the conductivity of the water is measured to be apparently low, and it can be seen that there is a possibility of incorrect management. From the above points, it was found that it is necessary to monitor the conductivity of the storage solution L while stirring the storage solution L.

Explanation of Signs

[0021] 13: Electrolyte membrane, L: Storage solution

Claims

【Claim 1】 A method for storing an electrolyte membrane used in a film-forming apparatus for forming a metal film on a substrate, wherein the electrolyte membrane is attached to the apparatus main body of the film-forming apparatus and is used for forming the metal film on the substrate by electrolytic plating while being in contact with the substrate, and in the storage method, while the boiled electrolyte membrane is immersed in a storage liquid and the storage liquid is stirred, the conductivity of the storage liquid is monitored over time, and the storage state of the electrolyte membrane is managed based on the change in the conductivity with time change. A method for storing an electrolyte membrane, characterized in that.

Images