JP2009052130A - Method for depositing thin film of metal germanium using electrolysis technique - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for plating the surface of an accessory or a semiconductor with a thin film of an alloy with a metal(s) selected from platinum group metals, gold and silver. <P>SOLUTION: Germanium dioxide is dissolved into an alkaline solution, thereafter, free acid is added thereto, so as to produce an acid germanium solution, and further, a coprecipitating metal(s) selected from platinum group metals, gold and silver is dissolved, so as to be an electrolytic solution. The concentration of germanium in the electrolytic solution is regulated in accordance with use in such a manner that the content of germanium is controlled to 5 to 45 wt.% in an accessory, and the content of germanium is controlled to 80 to 90% in a semiconductor device. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for producing an electrolytic solution used for forming a metal thin film containing germanium by plating, further a plating method using the electrolytic solution, and a semi-metallic germanium as a semiconductor produced by the plating method. The present invention relates to a plated product in which a thin film and a surface layer such as a jewelry (a personal coin) are coated with the thin film.

  Germanium has an enormous use as a semiconductor element such as a diode or a transistor, but its position has now been changed due to the appearance of a silicon element.

  The reason for this is that germanium itself can be ingot cast from a molten state, but germanium itself is not malleable and cannot be rolled, a thin film cannot be obtained, and the germanium ingot is mechanically pulverized, This is because there was a processing restriction that a fine powder obtained by chemically reducing germanium dioxide must be mixed with some medium and molded into the required shape by plastic processing. is there.

  Therefore, in the past, a plating technique for manufacturing a plating containing germanium has been proposed.

For example, Patent Document 1 (Japanese Patent Application Laid-Open No. 2006-45653) discloses a plating member having a plating film formed of an alloy containing Ge as an essential component on its surface. The film is formed. This plating method comprises a Ge source; an Rh source; an organic acid comprising one or more of citric acid, sulfamic acid, glycolic acid, acetic acid, succinic acid, and malic acid; potassium hydroxide or sodium hydroxide. Using an acidic plating bath containing an alkaline component; and a free acid composed of sulfuric acid, hydrochloric acid, phosphoric acid, or sulfamic acid, the pH is 5.5 or less, the bath temperature is from room temperature to 60 ° C., and the current density is 0.1 to 10 A. It has been proposed as a method for producing a plated member in which an electroplated film is formed by electrodeposition of a Ge—Rh binary alloy on a material to be plated under the condition of / dm ² .
JP 2006-45653 A

  Forming germanium flakes, such as silicon element flakes, as semiconductors is not possible at all because of the lack of extensibility, which is a characteristic of such thin pieces.

  In addition, in order to form a germanium film on the surface of a product such as a decorative item (a personal coin), it is necessary to perform alloy plating with another metal and maintain the alloy component ratio within a predetermined range. In addition, the pH of the plating bath (electrolytic solution) had to be controlled to a predetermined value. If they deviate from these requirements, the aesthetic appearance as a decorative article is lost, and the wear resistance and corrosion resistance also deteriorate. As described above, there are restrictions on the selection of the alloy component ratio and metal type of the plating bath composition for the surface treatment. For example, in Patent Document 1, in order to prepare a plating bath, a plating bath is prepared using an organic acid in addition to a free acid. As a result, there is a problem that liquid management becomes difficult.

  SUMMARY OF THE INVENTION Accordingly, it is a first object of the present invention to provide an electrolytic solution for plating that facilitates liquid management of a plating bath.

  In addition, germanium is surely dissolved in the plating bath to improve the aesthetic appearance as a decorative product, improve the wear resistance and corrosion resistance, and can form a plating film with higher purity (that is, a plating bath (that is, The second problem is to provide an electrolytic solution), a plating method using the same, and a semiconductor film and a plated product manufactured by the plating method.

  Furthermore, in the case of a plated product used as a decorative product, it is desirable that the color tone appearing on the surface thereof can be arbitrarily adjusted.

  Therefore, a third object of the present invention is to provide a plating method capable of arbitrarily adjusting the color tone of plating, and a semiconductor film and a plated product manufactured by this plating method.

  In order to solve at least one of the above problems, the present invention provides an electroplating method in which a metal surface treatment technique is applied to form a thin film of germanium, and the deposited film thickness and color tone can be adjusted as necessary. . In addition, by using the plating method (ie, surface treatment technology) on the surface of products such as ornaments (personal coins), alloy plating containing germanium is applied to provide ornaments with the characteristics of germanium. To do. Furthermore, if necessary, a material for peeling a thin film formed by the plating method from a base material (product to be plated) and using it as a semiconductor film or the like is provided.

  That is, in the present invention, a method for producing an electrolytic solution used for forming a metal thin film containing germanium by plating, which comprises dissolving germanium in an alkaline solution to produce a germanium solution, A step of adding a free acid in the presence of a free acid in the germanium solution to form an acidic germanium solution; and at least one selected from platinum group metals, gold, and silver in the acidic germanium solution Alternatively, the present invention provides a method for preparing an electrolytic solution for forming a germanium-containing thin film comprising a eutectoid metal dissolving step of dissolving two or more kinds of eutectoid metals to prepare an electrolytic solution.

  Such an electrolytic solution uses only a free acid to adjust the pH, and does not use an organic acid or the like, so that the liquid management becomes easy. Moreover, since germanium is first dissolved in an alkaline solution, a plating bath (electrolytic solution) in which germanium is sufficiently dissolved can be prepared. Since germanium is dissolved and free acid is present and the eutectoid metal is added, the mixing ratio of germanium: eutectoid metal in the electrolytic solution can be arbitrarily adjusted.

  Thereby, for example, when performing plating using the electrolytic solution, the content ratio of germanium and eutectoid metal in the electrolytic solution is adjusted and / or the temperature of the electrolytic solution at the time of electrolytic deposition is adjusted. This makes it possible to adjust the color tone of the plating and the content ratio of germanium.

  It is desirable that the eutectoid metal used for preparing the electrolytic solution is rhodium. In particular, it is desirable to dissolve germanium dioxide in the alkaline solution. This is because other eutectoid metals cannot make the electrolyte into a strong acid.

The free acid is preferably a free acid comprising at least one of sulfuric acid and phosphoric acid. When hydrochloric acid is used as the free acid, the chlorine ions generate GeCl ₄ and GeCl ₂ compounds by bonding with germanium, and when they are present in the plating bath, the cathode deposition film (target product) is obtained when electrolysis is performed. In addition, black coarse particles are precipitated, resulting in a deterioration of the alloy composition.

  Furthermore, it is desirable that the pH of the electrolytic solution is adjusted to a range of 0.1 to 2 due to the presence of the free acid. This is because if the pH is 2 or less, germanium can be reliably deposited by electrolytic deposition. Regarding the pH of the electrolytic solution, it is particularly preferable that the pH is adjusted to a range of 0.4 to 0.8.

  Further, in the present invention, in order to solve at least one of the above problems, a plating method performed using an electrolytic solution, wherein the electrolytic solution created by the method according to the present invention described above is used as the electrolytic solution. Then, after forming a germanium-containing metal thin film, gold or rhodium plating is formed.

  By further metal plating on the germanium-containing plating layer, the effect of germanium can be expressed, but the decorativeness can be further enhanced.

  Furthermore, in the present invention, in order to solve at least one of the above-described problems, a plated product including an ornamented article and a decorative device subjected to plating, the plated product is obtained by the above-described plating method according to the present invention. Provided is a plated product that is formed and has a germanium content of 5 to 45% by weight in the plated portion.

  Such plated products can teach effects derived from germanium, for example, by using them as accessories such as necklaces, bracelets, earrings, belt buckles, rings, or parts thereof.

  As an effect derived from such germanium, germanium is said to have effects such as relief of fatigue and activation of metabolism, as well as relief of shoulder stiffness, neck stiffness, low back pain and knee pain. By using this, such an effect can be expected. The effect derived from germanium is that germanium's electrical properties change greatly depending on light and temperature, so touching this with the skin etc. causes the movement of electrons and balances the biocurrent. it is conceivable that.

When a plating bath (electrolyte) that does not contain a eutectoid metal is used, a plating made of germanium alone can be prepared, and another plating layer is formed thereon by the above method, so that germanium is formed. The content based on the germanium can be further increased. In order to form such a deposited layer of germanium alone, a germanium sulfate acidic solution is used, and electrolysis is performed with a cathode current density of 5 Amp / dm ² or more to obtain a deposit (layer) of germanium alone on the cathode. be able to. At that time, since the cathode current density is set to 5 Amp / dm ² or more, the quality as a plated product is lowered, but this point can be solved by forming a metal layer further on the germanium layer. Can do.

  Furthermore, in the present invention, in order to solve at least one of the above-mentioned problems, a germanium-containing semiconductor element is formed by the above-described plating method according to the present invention, and the germanium content rate Provides a semiconductor device having a weight ratio of 80 to 90% by weight. Specifically, in the above-described plating process, a thin film (germanium film) is formed on an arbitrary metal base material by plating (that is, surface treatment technology), and then the base film is chemically damaged without damaging the germanium film. It peels from a material and obtains the thin film of the required film thickness. In particular, when a eutectoid metal is not blended as a plating bath (electrolytic solution), a thin film of germanium alone can be formed.

  By using the above-described electrolytic solution according to the present invention as a plating bath, it is possible to eliminate the difficulty of liquid management.

  In addition, by carrying out the plating method using the electrolytic solution according to the present invention, it is possible to arbitrarily adjust the content of germanium and the eutectoid metal, and to provide a plating method capable of freely adjusting the color tone and the like. Is done.

  Furthermore, in plated products such as jewelry and ornaments created by this plating method, the germanium film formed on the surface layer is characteristic of a semiconductor when it reaches 32 ° C. or more due to the user's body temperature (−). It is expected to generate electrons, smooth the blood flow of the body, and heal troubles such as stiff shoulders.

  When a semiconductor thin film piece is formed by such a plating method, it is possible to provide a thin piece of a semiconductor element corresponding to a silicon element in this field by obtaining a shape, area, and film thickness according to the application. become.

Hereinafter, an electrolytic bath according to the present invention, a plating method using the same, and a method for producing a thin film by electrolytic deposition created by the plating method will be specifically described with reference to examples.
<Experimental example 1>

  A high-purity germanium dioxide having a purity of 99.9% or more is dissolved in an equivalent amount of an aqueous solution of sodium hydroxide, and a 1: 1 sulfuric acid solution is further added thereto, so that the germanium hydrate is completely dissolved. Dissolve clarified liquid. The pH of the clarified liquid is adjusted to 6.0 or less at this time.

  In order to obtain a germanium semiconductor thin film, the following elements which impair the characteristics, namely, phosphorus (P), arsenic (As), aluminum (Al), and gallium (Ga) must be avoided. At the time of bathing, a high purity reagent was used with particular attention to this point.

  At the same time, it was a necessary condition to avoid contamination with chlorine (Cl) ions.

If a compound of GeCl ₄ , GeCl ₂ , which is a reaction product of chlorine ions and germanium, is generated in the plating bath, when electrolysis is performed using this compound, it becomes a cathode deposition film (target product). As a result, it was found that black coarse particles were deposited and the alloy composition was impaired.

In addition, in order to obtain a deposit on the cathode by electrolysis using an acidic solution of germanium sulfate (electrolyte containing no eutectoid metal), the deposition of germanium alone must have a cathode current density of 5 Amp / dm ² or more. No precipitation was obtained.

  Precipitation at a high current density resulted in incomplete precipitation due to the coarse particles of germanium, and even with a slight external force, for example, rubbed with a brush or the like, the powder fell off as a powder.

The coarse germanium deposit is not a pure metal deposit but appears to be deposited on the cathode in the form of a compound combined with hydrogen ions at the same time as the deposit. At the same time as the deposit, the oxide (GeO)
In this state, the film was black and easy to come off, and did not become the original silver-white color.

  Therefore, in this example, in order to obtain a complete silver-white germanium film at a low current density, a method of depositing a eutectoid film by adding a metal excluding an element inhibiting the semiconductor effect was used.

  As the metal to be added, a metal exhibiting a potential as close to the germanium deposition potential as possible is desirable. In this respect, noble metals such as platinum, rhodium, palladium, gold and silver are preferable.

  Since the germanium electrolyte was an acidic sulfuric acid solution, it was judged that rhodium was most suitable, and was added in the form of rhodium sulfate. The ratio of Ge: Rh in the electrolytic solution was changed from (2: 1) to (100: 1), and the precipitation state was observed.

In order to maintain the characteristics of germanium as a semiconductor element, it is ideal to keep the eutectoid metal added to a minimum. Therefore, the Ge: Rh ratio (weight ratio) is 10: 1 to 0 in terms of liquid composition. A good film was obtained when the current density was 0.2 to 0.5 Amp / dm ² .

The deposited film was a grayish white film having a bluish color of germanium of 85 to 95% and rhodium of 15 to 5%, and was semi-glossy with a film thickness of 0.5 to 3.0 μm. Further, it was confirmed by an energy dispersive X-ray analyzer that the alloy composition of this film was a germanium alloy film having a germanium content of 88.98% (weight ratio). The results are shown in FIG.
<Experimental example 2>

  In order to obtain a thin film with good electrical conductivity, Au (gold) was selected as the eutectoid metal. The alloy plating bath of Example 1 is strongly acidic and stable at a pH of 2.0 or less, and when the pH is 2.0 or more, a lath precipitation of Ge occurs. In order to replace gold with rhodium, an Au compound that is stable at pH 2.0 or lower is an absolute condition.

  Therefore, as an Au compound, we confirmed by experiment that bromide potash was stable without self-reduction to pH 2.0 or less in a sulfuric acid bath, and further experimented with Ge-Au. The electrolyte of the alloy structure was established.

Germanium oxide was dissolved in an alkali salt (NaOH or KOH) adjusted to a molar ratio of 1: 2, and sulfuric acid was added to this solution to make a solution having a pH of 1.1 to 2.0. Electrolysis was performed by adding bluish gold potash to this solution and setting the Ge: Au metal ratio in the range of 5-10: 1.0-0.05. The electrolysis conditions were a current density of 0.1 to 2.0 Amp / dm ² and a bath temperature of 30 to 50 ° C.

As a result, a glossy film having a thickness of up to 3 μm was obtained from a hard alloy exhibiting yellowish green to brown. It was confirmed with an energy dispersive X-ray analyzer that the alloy composition of this film was a gold alloy film containing germanium at 5.74% (weight ratio). The results are shown in FIG.
<Experimental example 3>

In the same manner as in Example 2, an electrolytic solution was prepared in order to obtain a Ge—Ag alloy thin film, and electrolysis was attempted. Germanium dioxide powder was dissolved in a corresponding equivalent amount of potassium cyanide solution, and silver potassium potassium was added thereto at a ratio of Ge: Ag = 10: 1 to 5 to obtain an electrolytic solution.
The current density was in the range of 0.1 to 1.0 Amp / dm ² and electrolysis was performed at room temperature.

  As a result, when the deposition potential of Ag (silver) was low and the ratio of Ge: Ag (weight ratio) was 2: 1, almost only the deposition of silver was observed, resulting in rough deposition. A semi-glossy film was finally obtained at a Ge: Ag ratio (weight ratio) of 5: 1.

The alloy component ratio of the deposited film can be obtained in proportion to the mixing ratio of the metal in the electrolytic solution. At the same time, the rhodium content ratio and color in the film can be adjusted by controlling the current density during electrolysis. I was able to.
<Experimental example 4>

  In order to obtain a plated product that can heal stiff shoulders due to the generation of (-) electrons, which is a characteristic of germanium, jewelry that touches the skin directly (such as necklaces, bracelets, rings, etc.) An alloy plating containing germanium was applied to the surface layer.

  As the plating solution (electrolytic solution), a sulfuric acid acidic bath was used as in Experimental Example 1. However, the composition ratio of the metal in the liquid is set to Ge: Rh = 5: 1, the alloy composition of the deposited film is Ge = 15 to 50% (weight ratio), and the balance is Rh so that the balance is Rh. It was adjusted.

  The deposited plating film became a beautiful grayish white surface with a bluish tinge. It was confirmed by X-ray intensity measurement that the alloy composition of the coating was a coating of an alloy such as rhodium containing 43.83% (weight ratio) of germanium. The results are shown in FIG.

If the plated product is a decorative product, considering the application, the finish can be applied with gold or rhodium plating in addition to the color of the Ge-Rh alloy. It was confirmed that the above can be done without any problems.
<Experimental example 5>

  In this experimental example, in order to verify the configuration of the electrolytic bath, plating method, and plated product according to the present invention, an electrolytic bath, a plating method, and a plated product were prepared using other compounds, and the results were confirmed. .

(1) When germanium dioxide was dissolved using citric acid, which is an organic acid, instead of a free acid composed of one or more of sulfuric acid and phosphoric acid, it was confirmed that germanium dioxide was poorly dissolved. In addition, it has been confirmed that when this electrolyte is left for one day, germanium dioxide partially precipitates and is separated. As a result, it was confirmed that when an organic acid was used instead of the free acid, germanium dioxide was not sufficiently dissolved and liquid management was difficult.
When organic acid (citric acid) is used, Au (gold) is selected as the eutectoid metal, and citric acid is gradually added to the alkali solution of germanium prepared in Example 1 to adjust the pH to 4.0 to 5. Electrolysis with Au (gold) added to the clarified solution obtained as No. 8 as gold-plated gold potash / KAu (CN) ₂ and a mixing ratio (weight ratio) of Ge: Au = 5 to 10: 1.0 Use liquid. Using this electrolytic solution, electrolysis is performed at an electrolysis condition of current density of 0.5 to 1.5 Amp / dm ² and a bath temperature of 30 to 40 ° C., so that a mirror-gloss and yellow-green hard alloy film (deposition film) Can be obtained up to 3μ).

(2) When germanium dioxide was dissolved using sulfamic acid, which is an organic acid, instead of a free acid composed of one or more of sulfuric acid and phosphoric acid, it was confirmed that germanium dioxide did not dissolve. Furthermore, in this case, germanium dioxide could not be dissolved at room temperature or 50 ° C.

(3) It was confirmed that germanium dioxide was not dissolved even when germanium dioxide was dissolved using glycolic acid, which is an organic acid, instead of a free acid composed of at least one of sulfuric acid and phosphoric acid. Also in this case, germanium dioxide could not be dissolved at room temperature or 50 ° C.

(4) To confirm the pH of the electrolytic solution, sodium hydroxide was added to the electrolytic solution prepared in Experimental Example 1 to adjust the pH. as a result,
When electroplating was performed with an electrolyte solution having a pH of 5, no germanium was deposited.
When electroplating was performed with an electrolyte solution of pH 4, no germanium was deposited.
When electroplating was performed with an electrolyte solution having a pH of 3, no germanium was deposited.
When electroplating was performed with an electrolytic solution having a pH of 2 or less, germanium deposition was confirmed.

  From the above results, it was confirmed that the electrolytic solution according to the present invention preferably has a pH of 0.4 to 0.8.

  Since the germanium alloy thin film obtained by the electrolysis method of the present invention can be arbitrarily formed with a film thickness and a planar shape, up to now, instead of a semiconductor formed by adding some kind of medium material to germanium powder, It can be provided as various semiconductor elements.

  Furthermore, the jewelry which can exhibit the effect which germanium itself has is also provided by plating by this invention with respect to jewelry.

The chart of the scanning electron microscope and energy dispersive X-ray analyzer of Experimental Example 1. The chart of the scanning electron microscope and energy dispersive X-ray analyzer of Experimental Example 2. 10 is a chart of a scanning electron microscope and an energy dispersive X-ray analyzer of Experimental Example 4.

Claims (6)

A method for producing an electrolytic solution used for forming a metal thin film containing germanium by plating,
A germanium dissolution process in which germanium dioxide is dissolved in an alkaline solution to create a germanium solution;
In the germanium solution, a free acid is added to create an acidic germanium solution in the presence of a free acid,
A eutectoid metal dissolving step in which at least any one or two or more eutectoid metals selected from platinum group metals, gold, and silver are dissolved in the acidic germanium solution to create an electrolyte solution;
A method for producing an electrolytic solution for forming a germanium-containing thin film, comprising: The eutectoid metal is rhodium;
The free acid is a free acid composed of one or more of sulfuric acid and phosphoric acid,
The electrolytic solution preparation method according to claim 1, wherein the pH of the electrolytic solution is adjusted to a range of 0.1 to 2 due to the presence of the free acid. A plating method using an electrolytic solution,
As the electrolytic solution, an electrolytic solution prepared by the method according to claim 1 or 2 is used,
In order to adjust the color of the plating and the content ratio of germanium, the content ratio of germanium and the eutectoid metal in the electrolytic solution is adjusted and / or the temperature of the electrolytic solution at the time of electrolytic deposition is adjusted. And plating method. A plating method using an electrolytic solution,
A plating characterized by forming gold, rhodium or other metal plating after forming a germanium-containing metal thin film using the electrolyte prepared by the method according to claim 1 or 2 as the electrolyte. Method. A plated product including plated ornaments and ornaments,
The plated product is formed by the plating method according to claim 3 or 4,
A plated product, wherein the content of germanium in the plated portion is 5 to 45% by weight. A semiconductor element containing germanium,
The said semiconductor element is formed by the plating method of Claim 3 or 4, and the content rate of germanium is 80 to 90 weight%, The semiconductor element characterized by the above-mentioned.

Images