JP5994524B2 - Method for producing metal hydroxide powder - Google Patents

Description

The present invention manufactures indium oxide-based transparent conductor materials such as ITO film (Indium Tin Oxide film) and IGO film (Indium Garium Oxide), and indium oxide-based oxide semiconductor materials such as IGZO (Indium Garium Zinc Oxide). a manufacturing how a metal hydroxide powder is used as a raw material.

  Sputtering targets for indium oxide-based transparent conductor materials and indium oxide-based oxide semiconductor materials used to form ITO films and IGZO films mix and pulverize oxide powders of each constituent metal element to form compacts Then, it is obtained by sintering (see, for example, Patent Documents 1 and 2).

  It has been reported that sputtering targets tend to cause abnormal discharge during sputtering or cracking of the target during processing when the sintered density is low. For this reason, it is necessary to pay close attention to the mixing of halogen elements that inhibit sintering and the mixing of coarse particles.

  In order to solve such a problem, it is common to manufacture a target by a manufacturing method in which mixing of halogen elements and coarsening of particles do not occur. For example, a high-purity metal is dissolved in nitric acid, and this is neutralized with aqueous ammonia to precipitate the generated hydroxide, which is filtered, washed, dried, and then roasted to mix halogen elements and coarse particles. A method for obtaining an oxide powder free from slag is common. Moreover, a complex oxide powder may be obtained by dissolving a plurality of high-purity metals with nitric acid, neutralizing with ammonia water, and precipitating as a hydroxide.

  However, this method has the following problems. In this method, since a large amount of nitrogen is contained in the wastewater, an expensive drainage facility for removing nitrogen is required. Also, with this method, it is difficult to make the precipitation conditions constant, and the variation in particle shape and particle size distribution increases.

  To solve such a problem, a method has been proposed in which indium or gallium is electrolyzed as an anode, and the eluted metal ions are produced as hydroxides in an electrolytic solution (see, for example, Patent Documents 3 and 4).

  However, this proposed method solves the above-mentioned problems but creates new problems. In the proposed method, since a solid metal is used as the anode, the electrode state changes with the electrolysis time, and the current density cannot be made constant, resulting in a problem that the hydroxide particle size, crystallinity, and the like vary. In the case of continuous production, the productivity decreases due to frequent replacement of the thinning anode in order to keep the current density constant. Moreover, since the anode cannot be used up to the end, it is necessary to rework the anode, which takes time.

International Publication No. 2009/148154 JP 2011-190542 A JP-A-6-171937 JP-A-11-322334

  Accordingly, the present invention has been proposed in view of such circumstances, and a metal compound powder that can efficiently produce a metal compound powder having a uniform particle size and a narrow particle size distribution without the inclusion of halogen elements. It is an object of the present invention to provide a production method, a fired powder obtained by heat-treating a metal compound powder obtained by this production method, and a sputtering target containing the fired powder.

The method for producing a metal hydroxide powder according to the present invention that achieves the above-described object includes an anode formed by melting indium-gallium metal and an electrolytic solution that does not contain a halogen element. It is characterized by depositing metal hydroxide powder on the surface.

  In the present invention, by using an anode formed by melting a single metal or an alloy, the interface between the anode and the electrolytic solution can be flattened, and even if thinning occurs due to electrolysis, the anode is merely lowered by gravity. Therefore, the interface with the electrolytic solution can be kept flat. Thereby, in this invention, since an anode surface is flat, a current density can be made constant, and a metal compound powder with a uniform particle size and a narrow particle size distribution width can be manufactured. Moreover, in this invention, since the current density of an anode can be kept constant, work, such as replacement | exchange of an anode and a process, can be reduced, and metal compound powder can be manufactured efficiently. Furthermore, in this invention, since the electrolyte solution which does not contain a halogen element is used, it can prevent that a halogen element mixes in metal compound powder.

It is the schematic which shows the apparatus to which the manufacturing method of the metal compound powder to which this invention is applied.

  Below, the manufacturing method of metal compound powder to which this invention is applied, a baked powder, and a sputtering target are demonstrated in detail. Note that the present invention is not limited to the following detailed description unless otherwise specified.

1. Method for producing metal compound powder (1-1) Method for producing metal compound powder (1-2) Metal compound powder recovery step (1-3) Metal compound powder drying step 2. Manufacturing method of baked powder Manufacturing method of sputtering target

1. Method for producing metal compound powder (1-1) Method for producing metal compound powder Metal compound powder is used for sputtering for indium oxide-based transparent conductor materials and indium oxide-based oxide semiconductor materials used for forming ITO films and IGZO films. It is used as a target raw material. Examples of the metal compound powder include oxides or hydroxides such as indium, gallium, indium-gallium alloy, and indium-gallium-zinc alloy.

  The metal compound powder is produced by melting a single metal or alloy constituting the metal compound powder as an anode, and using an electrolyte solution that does not contain a halogen element. Precipitate. The manufacturing method of metal compound powder can be performed using the electrolyzer 1 as shown, for example in FIG.

  The electrolysis apparatus 1 includes an anode 3 in which a single metal or alloy is melted at the bottom of an electrolytic cell 2, and an electrolyte solution 4 disposed on the anode 3, and the electrolyte solution 4 so as to face the carbon electrode 5 disposed in the anode 3. An inner cathode 6 is arranged, and a constant current power source 7 is connected between the carbon electrode 5 and the cathode 6. In this electrolysis apparatus 1, by using the liquid anode 3 in which a single metal or an alloy is melted, the interface 8 with the electrolyte 4 has no convex portion, and the interface 8 is flat. Furthermore, the electrolysis apparatus 1 has an anode material supply means 9 for supplying the anode material to the anode 3 and a temperature adjustment means 10 for adjusting the temperature in the electrolytic cell 2. The electrolysis apparatus 1 is provided with a circulation mechanism 15 that sucks the metal compound powder 12 deposited by the pump 11 through the suction pipe 13 together with the electrolytic solution 4 and returns only the electrolytic solution 4 from the discharge pipe 14 to the electrolytic cell 2. It has been.

  When the metal compound powder 12 is produced by the electrolytic method, the progress of the thinning of the anode 3 varies depending on the shape of the surface of the anode 3. For example, when a solid anode is used, electrolysis concentrates on the convex portion and thinning easily proceeds. For this reason, in a solid anode, uneven thinning occurs due to the shape, arrangement, etc., and the current density locally fluctuates. However, in the electrolysis apparatus 1 shown in FIG. 1, the anode 3 is in a liquid state, and since there is no convex portion, the thinning proceeds uniformly and the flatness of the interface 8 can be maintained. The metal compound powder 12 has a uniform particle size and a narrow particle size distribution.

  The anode 3 contains indium and / or gallium, and is made by melting, for example, indium simple substance, gallium simple substance, indium-gallium alloy, indium-gallium-zinc alloy, or the like. The shape of the anode material put into the electrolytic cell 2 is not particularly limited as long as it is in a liquid phase in the electrolytic cell 2. Therefore, the anode material can be solid, liquid, granular or ingot. Further, a combination of end component metals and intermetallic compounds can be used as long as they are in a liquid phase with an alloy.

  The anode 3 is supplied with a necessary amount of anode material by the anode material supply means 9 so that the distance between the electrodes does not change even if the anode 3 is thinned by electrolysis. In the electrolysis apparatus 1, the solid state anode material is liquefied in a short time in the electrolytic cell 2, or the liquid state anode material is liquid, so that the electrode area and surface state are reduced. It can be maintained in almost the same state as before meat. Thereby, even if the anode 3 is thinned, there is no protrusion at the interface 8 with the electrolytic solution 4, the interface 8 can be kept flat, and the current density can be kept constant.

  The electrolytic solution 4 does not contain a halogen element that significantly affects the sinterability. For example, ammonium nitrate, ammonium sulfate, or ammonium carbonate is preferable from the viewpoint of cost and usability.

  Moreover, the electrolyte solution 4 is preferably the same or higher than the electrolysis temperature set by the boiling point. For example, when an aqueous electrolyte solution 4 is used and a gallium suds (13.7 wt% -86.3 wt%) alloy is used as the anode 3, the melting point of the alloy is 29.8 ° C. If electrolysis is performed under conditions of 100 ° C. or lower, the anode 3 is always in a liquid state. As a result, the interface 8 between the anode 3 and the electrolytic solution 4 becomes flat, and electrolysis can be performed under conditions of a stable current density. The electrolytic solution 4 is not particularly limited except that it does not contain a halogen element and preferably has a boiling point higher than the electrolysis temperature.

  The cathode 6 is not particularly limited as long as it is insoluble in the electrolyte. As the cathode, for example, carbon, titanium and the like are preferable. As the shape of the cathode, a plate, a mesh, or the like can be used.

  The temperature adjusting means 10 is a means for adjusting the temperature in the electrolytic cell 2 to a desired temperature, and has heating and cooling functions.

  The circulation mechanism 15 collects the deposited metal compound powder 12 and circulates only the electrolytic solution 4 to the electrolytic cell 2. The circulation mechanism 15 sucks the metal compound powder 12 together with the electrolyte 4 through the suction pipe 13 with the pump 11. Although not shown in detail, the circulation mechanism 15 separates the metal compound powder 12 and the electrolytic solution 4 by, for example, a filter, collects the metal compound powder 12, and the electrolytic solution 4 enters the electrolytic cell 2 through the discharge pipe 14. return. Furthermore, even if the metal compound powder 12 formed on the carbon electrode 5 provided on the anode 3 side precipitates in the electrolysis apparatus 1, the anode 3 located above the carbon electrode 5 is agitated with a stirrer or the like to form a metal. The compound powder 12 can be recovered by dispersing it in the electrolytic solution 4.

  In the electrolysis apparatus 1 having the above-described configuration, the liquid anode 3 is disposed at the bottom of the electrolytic cell 2, and the electrolyte solution 4 is present on the anode 3, whereby the interface 8 between the anode 3 and the electrolyte solution 4. There are no projections and the interface 8 is flat. Thereby, in this electrolysis apparatus 1, the current density of the anode 3 becomes uniform.

  In the electrolysis apparatus 1, electrolysis is performed by the temperature adjusting means 10 such that the electrolysis temperature is higher than the melting point of a single metal or alloy used for the anode 3. In the electrolysis apparatus 1, the anode 3 can always be liquid by making the electrolysis temperature higher than the melting point of the single metal or alloy. For example, indium used as the anode 3 has a melting point of about 156 ° C. and gallium has a melting point of about 29 ° C., and alloys have different melting points depending on the alloy ratio.

  In the electrolysis apparatus 1, when electrolysis is performed by setting a predetermined electrolysis temperature with the temperature adjusting means 10 and applying a predetermined current density with the constant current power source 7, an oxide or hydroxide of the anode metal is electrolyzed as the metal compound powder 12. It precipitates in liquid 4. In the electrolysis apparatus 1, even if the anode 3 is thinned by electrolysis, the liquid-state anode 3 is lowered by gravity, so the interface 8 with the electrolyte 4 remains flat and the surface shape of the anode 3 does not change. . By replenishing the anode material with the anode material supply means 9, since the anode material is in a liquid state, the electrode area and the surface shape can be maintained in substantially the same state as before the thinning. As a result, the metal compound powder manufacturing method can keep the current density at the anode 3 constant even if the metal loss occurs, so that the metal compound powder 12 having a uniform particle size and a narrow particle size distribution width can be obtained. it can. In addition, even when the electrolysis is continuously performed, the anode 3 is continuously supplied, so that the current density of the anode 3 can be maintained constant. Therefore, the thinned anode is frequently replaced as in the past. Since it is not necessary, productivity does not decrease, and further, reworking of the anode is not required, so that an increase in cost can be suppressed.

(1-2) Metal Compound Powder Recovery Step The metal compound powder 12 obtained by the above-described method for producing a metal compound powder is solid-liquid separated from the electrolytic solution 4, and the separated metal compound powder 12 is washed with pure water. Then separate the liquid and collect again. Examples of the solid-liquid separation method include filtration by a rotary filter, centrifugation, filter press, pressure filtration, vacuum filtration, and the like.

(1-3) Drying step of metal compound powder Next, the recovered metal compound powder 12 is dried. The drying method is performed by a dryer such as a spray dryer, an air convection type drying furnace, an infrared drying furnace or the like. Drying conditions are the same as those generally applied in the production of transparent conductor materials and semiconductor materials, and are not particularly limited. For example, the drying temperature is preferably in the range of 80 ° C to 150 ° C. When the drying temperature is lower than 80 ° C., the drying is insufficient. When the drying temperature is higher than 150 ° C., the hydroxide of the metal compound powder 12 is changed to an oxide, which is used for calcination in the next step. As a result, the particle size distribution of the calcined powder becomes large, which causes inconvenience in adjusting the particle size distribution. In addition, even when the metal compound powder 12 is an oxide, if the drying temperature is higher than 150 ° C., there is a problem in adjusting the particle size distribution. Therefore, it is preferable that the drying temperature is as low as the moisture of the metal compound powder 12 can be removed. The drying time varies depending on the temperature, but is about 10 hours to 24 hours.

2. The manufacturing method of a baked powder The manufacturing method of a baked powder calcines the metal oxide or metal hydroxide of the metal compound powder 12 obtained by the manufacturing method of the metal compound powder mentioned above. The heat treatment is performed by firing the metal compound powder 12 at a temperature of about 400 ° C. to 1000 ° C., for example. Since the fired powder is obtained by firing the metal compound powder 12 having a uniform particle size and a narrow particle size distribution width, an oxide mixture powder or a composite oxide powder having a uniform particle size and a narrow particle size distribution width is obtained. The oxide mixture powder is, for example, a mixture powder of indium oxide and gallium oxide, and the composite oxide powder is indium-gallium alloy oxide powder.

3. Manufacturing method of sputtering target The manufacturing method of a sputtering target first mixes the baked powder mentioned above with the other raw material of a target in a predetermined ratio, and produces granulated powder. Next, a molded body is produced by using, for example, a code press method using the granulated powder. Next, the molded body is sintered in the temperature range of 1300 ° C. to 1600 ° C., for example, under atmospheric pressure. Next, processing such as polishing the flat surface and side surfaces of the sintered body is performed as necessary. And a sputtering target can be obtained by bonding a sintered compact to the backing plate made from Cu.

  In the method for producing a sputtering target, since the particle size of the fired powder as a raw material is uniform and the particle size distribution is narrow, a high-density sintered body can be obtained and the density of the target can be increased. . As a result, cracks are not generated during processing of the target, and abnormal discharge can be prevented from occurring during sputtering.

<Example 1>
In Example 1, an electrolytic apparatus as shown in FIG. 1 is used, and an indium-gallium metal (composition In: 13 mol%, Ga: 87 mol%, melting point: about 17 ° C.) is used as an anode material. In an aqueous ammonium nitrate solution (NH ₄ NO ₃ concentration: 1 mol / L), the electrolysis temperature was set to 40 ° C., and the current density was controlled to 600 A / m ² with a constant current power source to perform continuous electrolysis. During electrolysis, indium-gallium metal was sequentially put into the electrolytic cell in a liquid state so that the distance between the electrodes did not change. The voltage during electrolysis was 2% plus or minus 2 and stable electrolysis conditions could be maintained.

  After the electrolytic reaction, the electrolytic solution in the electrolytic cell was collected, filtered, washed, and dried to obtain a mixture of indium hydroxide and gallium hydroxide. This was calcined at 600 ° C. for 2 hours in the air to obtain a metal compound powder of indium oxide and gallium oxide as a calcined powder. The particle size of this powder was measured with a laser type particle size distribution analyzer. When the particle size was evaluated as D50, and the particle size distribution was evaluated as D10 and D90, particles having a very narrow particle size distribution of D50 of 0.9 μm, D10 of 0.6 μm, and D90 of 1.4 μm were obtained. The chlorine concentration in the powder was analyzed and found to be 5 ppm or less.

<Example 2>
In Example 2, using the same apparatus as in Example 1, indium-gallium metal (composition In: 50 mol%, Ga: 50 mol%, melting point: about 70 ° C.) is used as an anode, and an aqueous ammonium nitrate solution (NH ₄ NO at 75 ° C.) is used. ₃ concentration was 1 mol / L), the electrolysis temperature was set to 75 ° C., and the current density was controlled to 600 A / m ² with a constant current power source to perform continuous electrolysis. Indium-gallium metal was sequentially introduced into the electrolytic cell in a liquid state so that the distance between the electrodes did not change. The voltage during electrolysis was 2% plus or minus 2 and stable electrolysis conditions could be maintained.

  After the electrolytic reaction, the electrolytic solution in the electrolytic cell was collected, filtered, washed and dried to obtain a mixture of indium hydroxide and gallium hydroxide. This was calcined at 600 ° C. for 2 hours in the air to obtain a metal compound powder of indium oxide and gallium oxide as a calcined powder. The particle size of this powder was measured with a laser type particle size distribution analyzer. When the particle size was evaluated as D50, and the particle size distribution was evaluated as D10 and D90, D50 was 1.1 μm, D10 was 0.5 μm, and D90 was 1.2 μm. The chlorine concentration in the powder was analyzed and found to be 5 ppm or less.

<Comparative Example 1>
In Comparative Example 1, indium-gallium metal (composition In: 50 mol%, Ga: 50 mol%, melting point: about 70 ° C.) was used as the anode in the same apparatus as in Example 1. An aqueous ammonium nitrate solution (NH ₄ NO ₃ concentration: 1 mol / L) was used as the electrolytic solution. In Comparative Example 1, a required amount of anode material is put into an electrolytic cell, the liquid temperature is raised to 90 ° C., the anode material is melted and then cooled to 50 ° C., and an alloy solid anode is formed. Electrolysis was performed by controlling the current density to 600 A / m ² with a power source. The anode thinned with time, and the electrolytic potential increased by + 10% with time. For this reason, the electrolysis was once stopped, a solid anode corresponding to the electrode thickness at the time of charging was charged, and the liquid temperature was raised to 90 ° C. An anode was formed so as to dissolve and have the same electrode interval as the initial stage, and the temperature was returned to 50 ° C., the electrode was solidified and electrolysis was performed again.

  Since this operation was repeated a plurality of times, the electrolysis time was the same as in Example 2, but the actual operation time was doubled and the productivity deteriorated. After the electrolytic reaction, the electrolytic solution in the electrolytic cell was collected, filtered, washed and dried to obtain a mixture of indium hydroxide and gallium hydroxide. This was fired at 600 ° C. for 2 hours in the atmosphere to obtain a metal compound powder of indium oxide and gallium oxide. The particle size of this powder was measured with a laser type particle size distribution analyzer. When the particle size was evaluated as D50 and the particle size distribution as D10 and D90, particles having a wide particle size distribution such as D50 of 1.2 μm, D10 of 0.3 μm, and D90 of 4 μm were obtained. The chlorine concentration in the powder was analyzed and found to be 5 ppm or less.

<Comparative example 2>
In Comparative Example 2, in the same apparatus as in Example 1, indium-gallium metal (composition In: 13 mol%, Ga: 87 mol%, melting point: about 17 ° C) was used as in Example 1, and ammonium chloride at 40 ° C was used. In an aqueous solution (NH ₄ Cl concentration: 1 mol / L), the electrolysis temperature was set to 40 ° C., and the current density was controlled to 600 A / m ² with a constant current power source, and continuous electrolysis was performed. Indium-gallium metal was sequentially introduced into the electrolytic cell in a liquid state so that the distance between the electrodes did not change. The voltage during electrolysis was 2% plus or minus 2 and stable electrolysis conditions could be maintained.

  After the electrolytic reaction, the electrolytic solution in the electrolytic cell was collected, filtered, washed and dried to obtain a mixture of indium hydroxide and gallium hydroxide. This was calcined at 600 ° C. for 2 hours in the air to obtain a metal compound powder of indium oxide and gallium oxide as a calcined powder. The particle size of this powder was measured with a laser type particle size distribution analyzer. When the particle size was evaluated as D50 and the particle size distribution as D10 and D90, particles having a narrow particle size distribution of D50 of 0.9 μm, D10 of 0.6 μm, and D90 of 1.7 μm were obtained. The chlorine concentration in the powder was analyzed and found to be 40 ppm.

  Table 1 below shows the electrolytic solutions, anode compositions, melting points, anode temperatures, D10, D50, and D90 of Examples and Comparative Examples.

Next, using the metal compound powders of gallium oxide and indium oxide of Examples and Comparative Examples, press molding was performed at a pressure of 294 MPa (3 ton / cm ² ), and these were fired in air at 1500 ° C. for 7 hours. A sintered body having a diameter of 20 cm was obtained. The relative densities of Examples 1 and 2 were 95% and 98%, and the relative densities of Comparative Examples 1 and 2 were 87% and 70%.

  From the results shown in Table 1, in Examples 1 and 2, since a mixture of indium hydroxide and gallium hydroxide having a uniform particle size and a narrow particle size distribution width was obtained, oxidation with a uniform particle size and a narrow particle size distribution width was obtained. It became a metal compound powder of indium and gallium oxide, and an extremely high density sintered body could be obtained. In Examples 1 and 2, since ammonium nitrate containing no halogen element was used for the electrolyte, it was possible to suppress the halogen element from being contained in the sintered body.

  In Comparative Example 1, since a solid anode was used, the current density was not constant due to thinning of the anode, resulting in an oxide powder having a non-uniform particle size and a wide particle size distribution range. For this reason, in the comparative example 2, sintering was inhibited and the relative density of the sintered compact became low. In Comparative Example 2, ammonium chloride was used as the electrolytic solution, so that the oxide powder contained a large amount of chlorine, the sintering was inhibited, and the relative density of the target was lowered.

  As shown in Examples 1 and 2, the production method of the metal compound powder to which the present invention is applied does not require replacement of the anode, so that the productivity is high and the stability of the electrolysis conditions is high. It is possible to form a high-density sintered body. For this reason, when the metal compound powder obtained by the manufacturing method of the metal compound powder to which the present invention is applied is used as a sintered body for a sputtering target, it can be expected to exhibit excellent performance with little generation of nodules.

Claims (2)

Indium - an anode formed by molten gallium metal, metal hydroxide powder characterized by depositing a metal hydroxide powder in electrolytic solution by electrolytic reaction using an electrolytic solution containing no halogen elements Production method. 2. The method for producing a metal hydroxide powder according to claim 1, wherein the electrolysis temperature is higher than the melting point of the indium-gallium metal.

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