Film deposition device of metal film and metal film deposition method

Abstract

A film deposition device (1A) of a metal film (F) includes a positive electrode (11), a solid electrolyte membrane (13), and a power supply part (14) that applies a voltage between the positive electrode (11) and a base material (B) to be a negative electrode. The solid electrolyte membrane (13) allows a water content to be 15% by mass or more and is capable of containing a metal ion. The power supply part (14) applies a voltage between the positive electrode and the base material in a state where the solid electrolyte membrane is disposed on a surface of the positive electrode such that metal made of metal ions contained inside the solid electrolyte membrane (13) is precipitated on a surface of the base material (B).

Claims

1. A film deposition device for deposition of a metal film, the film deposition device comprising a metal ion supplier configured to supply a solution containing metal ions, the metal ion supplier including an opening having an internal space and an inner wall; a metal positive electrode disposed in the internal space of the opening of the metal ion supplier and being engaged with the inner wall of the opening of the metal ion supplier; a solid electrolyte membrane disposed on a surface of the positive electrode, the solid electrolyte membrane having a water content of between 15% and 80%, inclusive, by mass, and the solid electrolyte membrane being capable of containing metal ions; a power supply part configured to apply a voltage between the metal positive electrode and a base material configured to be a negative electrode in a state where the solid electrolyte membrane is disposed on the surface of the metal positive electrode between the metal positive electrode and the base material such that metal is precipitated on a surface of the base material from the metal ions contained inside the solid electrolyte membrane; a pressing part configured to pressurize the solid electrolyte membrane against the base material by moving the metal positive electrode toward the base material, the pressing part being connected to a cap part of the metal ion supplier; a solution tank configured to house the solution containing the metal ions, the solution tank being connected via a supply tube to one side of the metal ion supplier; a waste liquid tank configured to recover waste liquid, the waste liquid tank being connected via a waste liquid tube to another side of the metal ion supplier; a pedestal configured to fix the base material and adjust alignment of the base material; and a temperature controller configured to adjust the temperature of the base material via the pedestal; wherein the metal positive electrode is a foamed metal body made of foam having continuous open cells, wherein the solution containing the metal ions is capable of transmitting through the metal positive electrode such that the metal ions are supplied to the solid electrolyte membrane.

2. The film deposition device for deposition of a metal film according to claim 1, wherein the metal positive electrode has a porosity of between 50 to 95% by volume, a pore diameter of 50 to 600 m, and a thickness of between 0.1 and 50 mm.

3. A film deposition device for deposition of a metal film, the film deposition device comprising a metal ion supplier configured to supply a solution containing metal ions, the metal ion supplier including an opening having an internal space and an inner wall; a metal positive electrode disposed in the internal space of the opening of the metal ion supplier and being engaged with the inner wall of the opening of the metal ion supplier; and a solid electrolyte membrane disposed on a surface of the positive electrode, the solid electrolyte membrane having a water content of between 15% and 80%, inclusive, by mass, and the solid electrolyte membrane being capable of containing metal ions; wherein the metal positive electrode is a foamed metal body made of foam having continuous open cells.

4. The film deposition device for deposition of a metal film according to claim 3, the film deposition device further comprising: a power supply part configured to apply a voltage between the metal positive electrode and a base material configured to be a negative electrode in a state where the solid electrolyte membrane is disposed on the surface of the metal positive electrode between the metal positive electrode and the base material such that metal is precipitated on a surface of the base material from the metal ions contained inside the solid electrolyte membrane; and, a pressing part configured to pressurize the solid electrolyte membrane against the base material by moving the metal positive electrode toward the base material, the pressing part being connected to a cap part of the metal ion supplier.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Features, advantages, and technical and industrial significance of exemplary embodiments of the invention will be described below with reference to the accompanying drawings, in which like numerals denote like elements, and wherein:

(2) FIG. 1 is a schematic conceptual diagram of a film deposition device of a metal film according to the present embodiment of the present invention;

(3) FIG. 2A is a schematic cross-sectional diagram for describing a film deposition method according to the film deposition device of a metal film shown in in FIG. 1 and a state of the film deposition device before film deposition;

(4) FIG. 2B is a schematic cross-sectional diagram for describing a film deposition method according to the film deposition device of a metal film shown in in FIG. 1 and a state of the film deposition device during film deposition; and

(5) FIG. 3 is a diagram showing a relationship between water contents of solid electrolyte membranes of the film deposition devices according to Examples 1 to 5 and Comparative Examples 1 and 2 and limiting current densities.

DETAILED DESCRIPTION OF EMBODIMENTS

(6) As shown in FIG. 1, a film deposition device 1A according to a first embodiment of the present invention makes metal precipitate from metal ions and deposits a metal film made of the deposited metal on a surface of a base material B. Here, as the base material B, a base material made of a metal material such as aluminum or a base material obtained by forming a metal underlayer on a surface to be treated of a resin or silicon base material is used.

(7) The film deposition device 1A includes at least a positive electrode 11 made of metal, a solid electrolyte membrane 13 disposed on a surface of the positive electrode 11, and a power supply part 14 for applying a voltage between the positive electrode 11 and a base material B to be a negative electrode.

(8) Further, on an upper surface of the positive electrode 11, a metal ion supply part 15 for supplying a solution containing metal ions (hereinafter, referred to as a metal ion solution) L to the positive electrode 11 is disposed. In a bottom part of the metal ion supply part 15, an opening is formed, and, in an internal space of the metal ion supply part 15, the positive electrode 11 is housed in a state engaged with an inner wall 15b.

(9) A solution tank 17 in which the metal ion solution L is housed is connected via a supply tube 17a to one side of the metal ion supply part 15, and, to the other side thereof, a waste liquid tank 18 that recovers a waste liquid after use is connected via a waste liquid tube 18a.

(10) When constituted like this, the metal ion solution L housed in the solution tank 17 can be supplied via the supply tube 17a to the inside of the metal ion supply part 15 and the waste liquid after use can be sent via the waste liquid tube 18a to the waste liquid tank 18.

(11) Further, since the positive electrode 11 is housed in a state engaged with the inner wall 15b in an internal space of the metal ion supply part 15, the metal ion solution L supplied from above of the internal space can be supplied to the positive electrode 11. Here, the positive electrode 11 is made of a porous body that transmits the metal ion solution L and supplies metal ions to the solid electrolyte membrane. As such a porous body, as long as it has (1) corrosion resistance against the metal ion solution L, (2) the electric conductivity capable of operating as a positive electrode, (3) permeability of the metal ion solution L, and (4) capability of being pressed with a pressing part 16 described below, there is no particular restriction. For example, a foamed metal body made of a foam having continuous open cells, which has an ionization tendency lower than that of the film deposited metal (or higher in an electrode potential), such as foamed titanium can be used.

(12) Further, regarding the condition of (3) described above, in the case where a foamed metal body is used, for example, it is preferable that the foamed metal body has the porosity of about 50 to 95% by volume, a pore diameter of about 50 to 600 m, and a thickness of about 0.1 to 50 mm.

(13) Further, a pressing part 16 is connected to a cap part 15a of the metal ion supply part 15. The pressing part 16 pressurizes the solid electrolyte membrane 13 against a film deposition region E of the base material B by moving the positive electrode 11 toward the base material B. For example, as the pressing part 16, a hydraulic or air cylinder and so on can be used.

(14) Further, the film deposition device 1A includes a pedestal 21 that fixes the base material B and adjusts alignment of the base material B to be a negative electrode with respect to the positive electrode 11 and a temperature controller 22 that adjusts temperature of the base material B via the pedestal 21.

(15) As the metal ion solution L, an aqueous solution that contains ions of, for example, copper, nickel, silver or the like can be used. For example, in the case of copper ion, a solution containing copper sulfate, copper pyrophosphate or the like can be used. As the solid electrolyte membrane 13, a membrane, a film or the like made of a solid electrolyte can be used.

(16) The solid electrolyte membrane 13 is a membrane made of a solid electrolyte having the water content of 15% by mass or more, which, when brought into contact with the metal ion solution L described above, can impregnate the metal ions in the inside thereof, and in which the metal ions move on a surface of the base material B when a voltage is applied, and a metal derived from the metal ions is reduced and can be precipitated.

(17) As a material of the solid electrolyte membrane, a fluororesin such as Nafion (registered trade mark) manufactured by DuPont, a hydrocarbon resin, or a resin having an, ion exchange function such as SELEMION (CMV, CMD, CMF series) manufactured by ASAHI GLASS Co., Ltd. can be used. By properly selecting a kind and a ratio of a functional group of a produced resin, a solid electrolyte (resin) of which a water content can be set to 15% by mass or more can be obtained. In general, as the number of the ion exchange groups increases, the water content of the solid electrolyte membrane can be increased, and these can be manufactured according to a generally well-known method. For example, by varying a hot-press time of these resins, the water content can be adjusted. In particular, as the resin that satisfies such a range of the water content, a resin such as a perfluorosulfonic acid resin can be used. Further, the upper limit of the water content of the solid electrolyte membrane is preferably 80% by mass or less, and, in this range, both of the metal ions and the water content can be preferably impregnated while maintaining the film strength.

(18) Hereinafter, a film deposition method according to the present embodiment will be described. Firstly, on the pedestal 21, the base material B is disposed, alignment of the base material B is adjusted with respect to the positive electrode 11, and a temperature of the base material B is adjusted by a temperature controller 22. Next, as shown in FIG. 2B, the solid electrolyte membrane 13 is disposed on a surface of the positive electrode 11 that is made of a porous body, the solid electrolyte membrane 13 is brought into contact with the base material B, and the base material B is made conductive with the negative electrode of the power supply part 14.

(19) Then, by means of the pressing part 16, the positive electrode 11 is moved toward the base material B, and the solid electrolyte membrane 13 is pressurized against the film deposition region E of the base material B thereby. Thus, since the solid electrolyte membrane 13 can be pressurized via the positive electrode 11, the solid electrolyte membrane 13 is made to uniformly follow a surface of the base material B of the film deposition region. That is, by electrical energization with the power supply part 14 described below while contacting (pressurizing) the solid electrolyte membrane 13 with the base material by use of the positive electrode 11 as a backup material, a metal film F having a more uniform film thickness can be deposited.

(20) Next, by use of the power supply part 14, a voltage is applied between the positive electrode 11 and the base material B to be a negative electrode to precipitate metal from the metal ions contained inside the solid electrolyte membrane 13 on a surface of the base material B. At this time, the metal film F is deposited while supplying the metal ion solution L to the positive electrode 11.

(21) As a result like this, by use of the positive electrode 11 made of a porous body, the metal ion solution L can be transmitted to the inside thereof, and the transmitted solution L can be supplied to the solid electrolyte membrane 13 together with the metal ions. Thus, during film deposition, the metal ion solution L can be supplied as needed to the solid electrolyte membrane 13 via the positive electrode 11 that is a porous body. The supplied metal ion solution L transmits the inside of the positive electrode 11 and comes into contact with the solid electrolyte membrane 13 adjacent to the positive electrode 11, and, the metal ions are impregnated in the solid electrolyte membrane 13 and the water content of the solid electrolyte membrane 13 can be maintained at 15% by mass or more.

(22) Then, when a voltage is applied between the positive electrode 11 and the base material B to be a negative electrode, the metal ions inside the solid electrolyte membrane 13, which are supplied from the positive electrode side move from the positive electrode 11 side to the base material B side, and metal from the metal ions contained in the inside of the solid electrolyte membrane 13 is precipitated on a base material side. Thus, a metal film F can be deposited on a surface of the base material B.

(23) According to the present embodiment, as the solid electrolyte membrane 13, a solid electrolyte membrane having the water content of 15% by mass or more (a solid electrolyte membrane having water containing capacity of 15% by mass or more as the water content) is used, and a film deposition is performed by setting the water content of the solid electrolyte membrane 13 to 15% by mass or more.

(24) Here, the conduction of the metal ions in the solid electrolyte membrane is considered to be performed not by ion hopping like proton but by ion diffusion in a water cluster. By increasing the water content of the solid electrolyte membrane 13 (by setting to the water content described above), an amount of water cluster can be increased. Thus, a region in which a transition metal ion having a high valence can move is increased, and a transportation amount of ions per unit area can be increased.

(25) As result like this, since the metal ions are made to be readily supplied from the solid electrolyte membrane 13 to the proximity of an interface between the solid electrolyte membrane 13 and the metal film F, a concentration of the metal ions can be suppressed from becoming lower. Thus, since in the proximity of an interface between the solid electrolyte membrane 13 and the metal film F, a local pH decrease accompanying the reduction of hydrogen ions can be suppressed from occurring, generation of metal hydroxide derived from the metal ions is suppressed and formation of oxide on a surface of the metal film F becomes difficult.

(26) Further, in the process of precipitation of metal ions, since the charge transfer becomes faster than the material transfer, the dendrite-like metal is difficult to be precipitated, a surface of the metal film F becomes smooth, and the metal film F is difficult to closely stick to the solid electrolyte membrane 13.

(27) Thus, even when a density of current that flows the solid electrolyte membrane 13 is high, since a transport velocity of the metal ions inside thereof does not decrease, the metal film F can be deposited at a higher speed.

(28) Here, in the case where the water content of the solid electrolyte membrane 13 becomes less than 15% by mass, since the water content of the solid electrolyte membrane 13 is low, oxide is likely to be formed on a surface of the metal film F, and the metal film F tends to closely stick to the solid electrolyte membrane 13 thereby.

(29) Further, since the metal ion solution L can be supplied as needed via the positive electrode 11 that is a porous body, without limiting an amount of metal that can be precipitated, a metal film F having a desired film thickness can be continuously deposited on surfaces of a plurality of base materials B.

(30) The present invention will be described with reference to the following examples.

Example 1

(31) By use of a device shown in FIG. 1 described above, a metal film was deposited. As a base material on a surface of which a film is deposited, a pure aluminum base material (50 mm50 mmthickness 1 mm) was prepared, on a surface of which a nickel plating film was formed, further a gold plating film was formed on a surface of the nickel plating film. Next, a positive electrode obtained by coating platinum plating at a thickness of 3 m on a surface that faces a film deposition region of a surface of a porous body (manufactured by Mitsubishi Material Corporation) that is made of a 10 mm10 mm1 mm foamed titanium and has the porosity of 65% by volume was used.

(32) A mass of a solid electrolyte membrane in a dry state (dry mass) was measured, after immersing this in pure water, moisture attached on a surface thereof was wiped, in this state, a mass of the solid electrolyte membrane (mass in wet base) was measured, and the water content (% by mass) was calculated according to the following formula.
(Mass in wet baseDry mass)/Mass in wet base
As a metal ion solution, a solution of 1 mol/L copper sulfate was prepared, while pressurizing under 0.5 MPa from above the positive electrode, at normal temperature for a treatment time of 30 minutes, a copper film was deposited on a surface of a base material. At this time, the limiting current density during film deposition (the maximum current density that does not generate film abnormality) was measured. The results are shown in the following Table 1 and FIG. 3.

Examples 2 to 5

(33) In the same manner as Example 1, a copper film was manufactured on a surface of the base material. Specifically, the solid electrolyte membrane of Example 2 had the water content of 30% by mass, the solid electrolyte membrane of Example 3 had the water content of 28% by mass, the solid electrolyte membrane of Example 4 had the water content of 28% by mass, and the solid electrolyte membrane of Example 5 had the water content of 23% by mass.

(34) With film deposition devices of these Examples 2 to 5, in the same manner as Example 1, the limiting current density during film deposition (the maximum current density that does not generate film abnormality) was measured. The results are shown in the following Table 1 and FIG. 3.

Comparative Example 1 and 2

(35) In the same manner as Example 1, a copper film was formed on a surface of a base material. Except Example 2, the water content was different from that of Example 1 (capacity that can contain water is different). Specifically, a solid electrolyte membrane of Comparative Example 1 had the water content of 11% by mass and a solid electrolyte membrane of Comparative Example 2 had the water content of 9% by mass.

(36) With film deposition devices of Comparative Example 1 and 2, in the same manner as Example 1, the limiting current density during film deposition (the maximum current density that does not generate film abnormality) was measured. The results are shown in the following Table 1 and FIG. 3.

(37) TABLE-US-00001 TABLE 1 Water content of solid Limiting electrolyte membrane current density (% by mass) (mA/cm.sup.2) Example 1 30 45 Example 2 30 30 Example 3 28 25 Example 4 28 25 Example 5 23 10 Comparative Example 1 11 <5 Comparative Example 2 9 <5

(38) (Results) As shown in FIG. 3, when films were deposited with the film deposition devices of Examples 1 to 5, the limiting current densities were 10 mA/cm.sup.2 or more. However, when films were deposited with film deposition devices of Comparative Examples 1 and 2, the limiting current densities were less than 5 mA/cm.sup.2. From this result, it is considered that when the water content of the solid electrolyte membrane is 15% by mass or more like Examples 1 to 5, the limiting current density exceeds 5 mA/cm.sup.2, and film deposition can be performed at a higher speed.

(39) In the above, Embodiments of the present invention were described in more detail. However, the present invention is not limited to the embodiments described above, and various design modifications can be applied.