JP2013522473A - Method for producing highly purified and refined ruthenium (Ru) powder using used ruthenium (Ru) target - Google Patents

Abstract

The present invention relates to a method for producing high-purity and refined ruthenium powder using a used ruthenium (Ru) target, and a complicated process for producing powder in the case of producing using a conventional wet method Has been devised to overcome disadvantages such as environmental pollution problems such as wastewater treatment by using acid. In order to improve this, contaminants are removed from the surface of the used ruthenium (Ru) target by a chemical or physical method, and the surface-treated used ruthenium (Ru) target is mounted inside the plasma chamber. And, after controlling the plasma torch, reducing the pressure using a vacuum device to form plasma, producing high-purity powder, and obtaining fine and highly purified ruthenium (Ru) powder through pulverization Features.
[Selection] Figure 1

Description

  The present invention relates to the production of a ruthenium (Ru) raw material powder for the production of a target and other ruthenium (Ru) compounds. The contaminants remaining on the surface of a used ruthenium (Ru) target are physically or chemically treated. The high purity ruthenium (Ru) powder is produced by using the plasma, and finally the high purity and refined ruthenium (Ru) powder is produced through fine pulverization. The present invention relates to the production of a ruthenium (Ru) powder material that is often used for a seed layer for forming a large-capacity highly integrated magnetic layer related to a magnetic recording medium or a next-generation memory.

  The present invention produces vaporized high-purity ruthenium (Ru) powder on a used ruthenium (Ru) target using plasma, which is a kind of dry method, and finally refined ruthenium through fine grinding. (Ru) This relates to the production of powder, and more specifically, the environmental load is low and the process is shortened compared to the production process of ruthenium (Ru) powder and target using a wet method which has been frequently used in recent years. In addition, the present invention relates to a method of manufacturing ruthenium (Ru) powder using plasma and capable of shortening the manufacturing time and manufacturing a fine powder of 20 μm or less through a pulverization process.

  Generally, an electrode layer or a seed layer is formed on a wafer or glass used for next-generation semiconductor memories (RAM, MRAM, FeRAM), heads (MR, TMR), and capacitors (Capacitors). Therefore, a ruthenium (Ru) thin film is often used. However, since ruthenium (Ru) powder for producing a ruthenium (Ru) sputtering target for forming a thin film is expensive, a used ruthenium (Ru) target is used. Ruthenium (Ru) powder is produced by recycling.

  Further, since ruthenium (Ru) is expensive, in order to increase the efficiency of the target and make it easy to control the thickness of the thin film after film formation, it is required to refine the crystal grains of the target and to increase the purity. It is a trend. The ruthenium (Ru) target having such fine crystal grains and high purity and high functionality is manufactured using a sintering method instead of a melting method, and fine ruthenium (Ru) is used for controlling the crystal grains. ) The use of powder is required, and the production of fine ruthenium (Ru) powder is essential for shortening the dissolution time during the production of the compound.

  In general, a wet method is used for producing ruthenium (Ru) powder, but in the case of producing the ruthenium (Ru) powder, wet dissolution is performed on a used target using a strong acid solution, and then distillation, concentration, drying, Final ruthenium (Ru) powder is produced through oxidation and heat treatment.

  However, when applying the wet method described above, there is a handling risk due to the use of a strong acid solution, which not only requires a lot of time to dissolve in the acid solution, but also requires a lot of manufacturing time and time due to the application of complicated processes. Expenses increase and the processing of a considerable amount of spent effluent results in significant additional costs.

  Recently, an attempt has been made to produce ruthenium (Ru) powder by using a pulverization method or a dry method instead of such a wet method. For example, Japanese Patent Application Publication No. 2009-108400 discloses a method for producing ruthenium (Ru) powder through coarse pulverization, hammer milling, leaching, milling, magnetic sorting, drying, reduction, and heat treatment using a used ruthenium (Ru) target. Is disclosed.

  However, using the method of the above-mentioned patent application eliminates the use of a large amount of acid solution by applying the conventional wet method and has the advantage of shortening the powder production time, but enormous target pulverization and powder refinement from the beginning of the process When pulverizing with a pulverizing tool during pulverization (coarse pulverization and fine pulverization), there is a problem that the components of these tools are mixed into the powder and contaminated. In order to solve this problem, it has been proposed to add a step of removing the contamination using an acid solution.

  The present invention relates to the production of highly purified and refined ruthenium (Ru) powder using a used ruthenium (Ru) target, and in particular, a dry method with a low environmental load is used instead of a conventional wet method. The present invention relates to powder production, and aims to produce high-purity powder using plasma instead of powder grinding, and finally to produce highly purified and refined ruthenium (Ru) powder through fine grinding. . In the above-mentioned powder production, the production time is shortened compared with the existing wet method, the generation of waste liquid due to the use of an acid solution is eliminated, the environmental load is kept low, and the ruthenium (Ru) powder refined through fine grinding is used. Manufacturing is possible.

  More specifically, the present invention removes contaminants remaining on the surface using a physical or chemical method such as polishing or processing on the surface of a used target, and uses a plasma apparatus. An object of the present invention is to produce a high-purity ruthenium (Ru) powder and finally produce a highly purified and refined ruthenium (Ru) powder through pulverization and classification into the produced powder.

  The present invention relates to an inert atmosphere after mounting a used ruthenium (Ru) target on a used ruthenium (Ru) target by removing a surface contamination source using a physical or chemical method and removing the contaminant on the plasma apparatus. A ruthenium (Ru) powder is produced by applying a plasma to a used ruthenium (Ru) target, and finally a final ruthenium (Ru) powder is obtained through pulverization and classification.

  As described above, when applying the conventional wet method, a complicated process (wet dissolution, concentration, drying and heat treatment) is applied to the production of the powder, and it takes a long time of several days or more. There are many disadvantages such as handling restrictions and waste liquid treatment costs.

  In addition, the recently known dry method has advantages such as shorter production time and higher purity than the wet method, but contamination by target coarse pulverization occurs, and this is solved by adding a wet process. The fact is that it has been proposed.

  However, the present invention employs a dry method instead of a wet method in the production of high purity and fine ruthenium (Ru) powder, and eliminates the wet process by producing the powder using plasma instead of coarse pulverization. There is an advantage that it is possible. Through this, the production time of the final powder and the target can be shortened to produce a highly purified and refined ruthenium (Ru) powder, which is expected to improve the function of the ruthenium (Ru) sputtering target material produced by the sintering method. Is done.

FIG. 1 is an operation procedure diagram for producing a ruthenium (Ru) powder and a ruthenium (Ru) target using the used ruthenium (Ru) target of the present invention.

  In the present invention, when manufacturing ruthenium (Ru) powder using a used ruthenium (Ru) target, high-purity powder is manufactured using plasma instead of the conventional wet method and coarse pulverization method. It is characterized by producing refined and refined final ruthenium (Ru) powder. Through this, the production time is dramatically shortened compared with the existing wet method, and the use of a low environmental impact method is applied by suppressing the use of acid used for dissolving and removing contaminants. Ru) Powder production is possible, and powder production with a yield of 95% or more and 20 μm or less is possible through pulverization and classification.

The final ruthenium (Ru) powder manufacturing method is as described in FIG.
Removing contaminants remaining on the surface of the spent ruthenium (Ru) target using chemical or physical methods (S1);
Attaching the cleaned used ruthenium (Ru) target to the plasma apparatus (S2);
Depressurizing the inside of the plasma apparatus, supplying a reactive gas, and applying power to form plasma (S3);
Increasing the power applied to the plasma device to obtain highly purified ruthenium (Ru) powder through powder production and heat treatment (S4);
It is characterized by comprising the step (S5) of producing ruthenium (Ru) powder refined through fine pulverization and classification of the obtained ruthenium (Ru) powder.

  Hereinafter, the above-described process steps will be described in detail.

  First, contaminants remaining on the surface of the used ruthenium (Ru) target are removed (S1).

  The surface of the used ruthenium (Ru) target has a high possibility of surface contamination due to handling, contamination due to droplet adhesion during the sputtering process, and surface oxidation due to long-term atmospheric exposure. In some cases, it is possible to remove some contaminants by plasma treatment, but many of them are likely to remain in the manufactured ruthenium (Ru) powder, which causes a reduction in the quality of the final target. It is desirable to remove contaminants before the manufacturing process. Contaminants can be removed by using a chemical method in which the used ruthenium (Ru) target is deposited on the melting material for a short time to cut the surface by several tens of micrometers, as well as mechanical processing methods such as shelves, grinders, or MCT. It is also possible to remove a layer of a certain amount using the physical method. When removing using a mechanical processing method, it is desirable to remove a thickness of about 10 μm. The reason is that if the removal thickness is too thin, the removal of the oxide film etc. is not perfect and is too thick. This may reduce the final powder yield.

  A used ruthenium (Ru) target from which contaminants have been removed is mounted inside the plasma chamber (S2).

  It is desirable to clean the inside of the chamber before the plasma treatment to prevent impurities and foreign matters from entering. A used ruthenium (Ru) target is mounted on the bipolar mold inside the cleaned chamber, and the distance between the plasma torch and the target is adjusted for plasma formation. The material of the electrodes used for plasma formation is important and it is important to minimize contamination. Bipolar mold materials that can be used include molybdenum (Mo), tungsten (W), copper (Cu), graphite (Graphite), and ruthenium (Ru), so as not to reduce the purity of the final powder. In addition, it is important to minimize contamination by the mold, and it is important to select a mold that can easily remove contamination even if contamination is caused by the mold. For this purpose, carbon that is easy to remove is advantageous, and it is more desirable to use a ruthenium (Ru) mold that does not affect the purity even if contamination occurs.

  As the material of the cathode mold used for the plasma treatment, molybdenum (Mo), tungsten (W), ruthenium (Ru) and the like can be used. For the production of high-purity powder, the same material of ruthenium ( It is desirable to use Ru).

  The inside of the plasma apparatus is depressurized, a reaction gas is introduced, and electric power is applied to form plasma (S3).

  In order to form plasma, the pressure is reduced to 10-1 torr level using a vacuum pump, and the reaction gas is charged and the working vacuum is adjusted, and then electric power is applied. As the reaction gas used, a mixed gas such as Ar, H2, N2, CH4, Ar + H2, and Ar + N2 can be used, and H2, N2, and O2 are highly likely to remain in the final ruthenium (Ru) powder. In the case of being manufactured as a target and used in a semiconductor line, these have the effect of forming particles (Particles) during the film formation process, so that it is most advantageous to use Ar in order to avoid the problem. It is. In addition to using N2 or H2 as a reaction gas to increase the production rate of the powder, even if gas components remain in the powder produced by the residual O2 inside the chamber, the degassing treatment is performed after the powder is refined It is desirable to select and use according to the work environment.

  The working vacuum is preferably about 50 to 600 torr. However, if the working vacuum is 50 torr or less, the plasma is transferred to the mold and direct heat transfer to the material becomes difficult. This is because it may be difficult to remove gas components inside the used ruthenium (Ru) target and impurities that can be removed at low pressure.

  The degree of vacuum is preferably adjusted using a cooling degree control valve in addition to using a cooling gas provided in the apparatus.

  After the plasma is formed, the power is increased to produce ruthenium (Ru) powder, and a highly purified ruthenium (Ru) powder is produced through heat treatment (S4).

  When the plasma power is increased, the hot water is formed, and when the temperature of the hot water rises above the boiling point, the hot water is vaporized and powder is produced by cooling, and the powder is also produced by the ambient atmosphere and reaction gas pressure. Is manufactured. At this time, the applied electric power is preferably 10 to 100 kw or less. However, when the electric power is 10 kw or less, no hot water formation and vaporization occurs because the power is low. Shall.

  Since ruthenium (Ru) has a high boiling point and a short cooling time, it is advantageous to increase the amount of cooling gas inside the chamber and obtain powder inside the chamber to increase the powder yield and yield.

  When CH4 is used for the reaction gas and graphite (C) is used for the mold in order to increase the powder production rate, carbon is mixed into the produced powder, so that carbon is added through atmospheric heat treatment. It is desirable to produce a final powder that is removed and subsequently purified through hydrogen heat treatment.

  As for the heat treatment conditions, in the case of atmospheric heat treatment, the heat treatment is desirably performed at a temperature of 800 to 1200 ° C. for 1 to 5 hours. When the temperature is 800 ° C. or lower and is short within 1 hour, the remaining carbon (Carbon) is likely not to be removed sufficiently, and when the temperature is 1200 ° C. or higher and a high temperature of 5 hours or longer, it is manufactured. There is a high probability that the powder will aggregate.

  In the case of ruthenium (Ru) powder that has been subjected to atmospheric heat treatment to remove carbon, ruthenium (Ru) is oxidized to give a blue oxide due to the characteristics of ruthenium (Ru). By performing hydrogen heat treatment, reduced ruthenium (Ru) powder can be obtained.

  In order to convert ruthenium (Ru) powder subjected to atmospheric heat treatment or pulverized ruthenium (Ru) powder into a ruthenium (Ru) powder highly purified by reduction through a hydrogen heat treatment, 1 to 5 at a temperature of 800 to 1200 ° C. It is desirable to heat treat for a time. When the temperature is 800 ° C. or lower and is as short as 1 hour or less, the reduction of the ruthenium (Ru) oxide is not sufficient, and when the temperature is as high as 1200 ° C. or higher and the time is 5 hours or longer, the produced powder This is because there is a high possibility that the particles are aggregated.

  The ruthenium (Ru) powder produced by the plasma treatment is finely pulverized and classified to obtain a finally refined ruthenium (Ru) powder (S5).

  In the case of ruthenium (Ru) powder of 100 μm or less produced by plasma treatment, it is possible to use many pulverizers such as a ball mill, a planetary mill, and a jet mill that are generally used for fine pulverization. A jet mill is advantageous. In the case of ruthenium (Ru), it is easy to break and can be easily crushed. However, there is a possibility of contamination by balls due to a large amount of processing and an increase in work time, and pulverization using a jet mill that does not use balls. Is advantageous for obtaining high-purity ruthenium (Ru) powder. It is possible to obtain ruthenium (Ru) powder having a desired size using a classifier for the produced powder. Prior to pulverization, the gas components contained in the reaction gas and mold material may remain inside the powder, but can be removed using atmospheric heat treatment and hydrogen heat treatment used for powder production. .

  1.8 kg of used ruthenium (Ru) target used for hard disks to produce ruthenium (Ru) powder was secured. The used used ruthenium (Ru) target had a characteristic of a purity of 3N5 or more and a crystal grain size of the target of 20 μm or less. The secured used ruthenium (Ru) target was deposited on sodium dichlorate (NaClO) for 5 minutes in order to remove foreign matter from the surface in order to remove foreign matter on the surface. A manufacturing process in the case where 1 kg of ruthenium (Ru) powder is manufactured on a used ruthenium (Ru) target from which foreign matters have been removed using a 100 kw class DC thermal plasma apparatus is as follows.

A cleaned used ruthenium (Ru) target is mounted on a carbon mold, the electrode distance is adjusted, and then the pressure is reduced to 10-2 torr using a vacuum pump provided in the plasma apparatus. Was used as a reactive gas to form a plasma to produce a powder. Table 1 shows manufacturing process conditions of ruthenium (Ru) powder using plasma.

  The ruthenium (Ru) powder produced by plasma was pulverized and classified, and then subjected to atmospheric heat treatment and hydrogen heat treatment to obtain final ruthenium (Ru) powder. Analysis of ruthenium (Ru) powder produced first and ground and classified ruthenium (Ru) powder shows that in the case of ruthenium (Ru) powder produced through plasma, it has a spherical shape and is less than 100 μm However, as a result of grinding and classification, it was possible to produce 960 gr of fine ruthenium (Ru) powder having a central particle size of 10 μm.

  The produced powder is subjected to heat treatment at 800 ° C. for 1 hour in the atmosphere for degassing treatment to remove residual carbon, and hydrogen heat treatment is performed at 800 ° C. for 30 minutes to oxidize during the air heat treatment. The ruthenium (Ru) powder thus obtained was subjected to a reduction treatment to obtain a highly purified and refined final powder.

* 不純物単位：ｐｐｂ（ｗｅｉｇｈｔ）
* その他不純物：Ｌｉ、Ｂｅ、Ｓｃ、Ｖ、Ｍｎ、Ｃｏ、Ｇａ、Ｇｅ、Ａｓ、Ｓｅ、Ｂｒ、Ｒｂ、Ｓｒ、Ｎｂ、Ａｇ、Ｃｄ、Ｉｎ、Ｓｎ、Ｓｂ、Ｔｅ、Ｉ、Ｃｓ、Ｂａ、Ｈｆ、Ｔａ、Ａｕ、Ｈｇ、Ｐｂ、Ｂｉ、Ｒｅ In order to confirm the impurity content of the final manufactured ruthenium (Ru) dry powder, impurity analysis (Example 1) was performed through analysis of a glow discharge mass spectrometer (GDMS), and the manufactured ruthenium ( In order to grasp the level of Ru powder, commercially available ruthenium (Ru) powder having a purity of 3N5 or higher was purchased and analyzed by a glow discharge mass spectrometer (Comparative Example 1). The results are shown in Table 2.

* Impurity unit: ppb (weight)
* Other impurities: Li, Be, Sc, V, Mn, Co, Ga, Ge, As, Se, Br, Rb, Sr, Nb, Ag, Cd, In, Sn, Sb, Te, I, Cs, Ba, Hf, Ta, Au, Hg, Pb, Bi, Re

  From the results shown in Table 2, in the case of the powder of Example 1 that was finally produced, almost the same level as that of the powder of Comparative Example 1 was observed, and impurities (O, Cl, Si, etc.) that were partially reduced by the plasma treatment However, impurities (Ca, Fe, Cu, etc.) increased by handling are also observed. In particular, it can be seen that the ruthenium (Ru) powder of Example 1 was highly purified from the results that the final purity was comparable to that of the powder of Comparative Example 1 produced by the wet method.

  In order to confirm the sintering characteristics of the ruthenium (Ru) powder, a hot press sintering test was performed using the powder of Example 1 and the powder of Comparative Example 1 manufactured by a dry method to manufacture a sintered body. Thereafter, the characteristics were compared (Example 2, Comparative Example 2).

Moreover, in order to evaluate the physical property of the manufactured sintered compact, the commercially available ruthenium (Ru) target was purchased and the characteristic was also compared with this (comparative example 3).

  From Table 3, the ruthenium (Ru) sintered body manufactured according to the present invention (Example 2) is a sintered body manufactured using a ruthenium (Ru) powder manufactured by a conventional wet method (Comparative Example 2). It was found that the density and purity were equivalent levels, and no difference was found when compared with a commercially available ruthenium (Ru) target (Comparative Example 3).

  In particular, it can be seen that the size of the crystal grains is finer in the ruthenium (Ru) sintered body of the present invention than in the commercially available ruthenium (Ru) target.

Claims (8)

A method for producing ruthenium (Ru) powder using a used ruthenium (Ru) target, comprising:
Removing surface contaminants from the surface of a used ruthenium (Ru) target using chemical or physical methods;
Mounting the used ruthenium (Ru) target from which contaminants have been removed to a plasma device;
Depressurizing the inside of the plasma apparatus, supplying a reactive gas, applying electric power to form plasma; and
Increasing the applied plasma power to produce ruthenium (Ru) powder;
Heat-treating the produced ruthenium (Ru) powder to produce a highly purified ruthenium (Ru) powder;
A used ruthenium (Ru) target comprising: finely pulverizing and classifying the purified ruthenium (Ru) powder to produce a refined final ruthenium (Ru) powder. A method for producing a highly purified and refined ruthenium (Ru) powder.   The removal of surface contaminants of the used ruthenium (Ru) target may be performed by a chemical method of removing the contaminant after depositing the used ruthenium (Ru) target in a solution such as sodium dichlorate (NaClO), or The highly purified and refined ruthenium (Ru) using the used ruthenium (Ru) target according to claim 1, wherein contaminants are removed using a physical method such as surface polishing or machining. ) Powder production method.   The material of the mold of the plasma device is any one selected from graphite (Graphite), copper (Cu), molybdenum (Mo), tungsten (W) or ruthenium (Ru), A method for producing a highly purified and refined ruthenium (Ru) powder using the used ruthenium (Ru) target according to claim 1.   2. The used ruthenium (Ru) target according to claim 1, wherein the reactive gas used during plasma formation is one or more selected from Ar, H 2, N 2, and CH 4. A highly purified and refined ruthenium (Ru) powder manufacturing method using a bismuth.   The degree of vacuum inside the plasma apparatus for producing ruthenium (Ru) powder is 50 to 600 torr, and is highly purified and refined using the used ruthenium (Ru) target according to claim 1. Ruthenium (Ru) powder manufacturing method.   2. The used ruthenium (Ru) according to claim 1, wherein after the plasma treatment, a high-purity ruthenium (Ru) powder is obtained by performing an atmospheric heat treatment and a hydrogen heat treatment as a heat treatment of the manufactured ruthenium (Ru) powder. ) A method for producing highly purified and refined ruthenium (Ru) powder using a target.   The high-purity using a used ruthenium (Ru) target according to claim 6, wherein the atmospheric heat treatment is performed at a temperature of 800 ° C. to 1200 ° C. for 1 to 5 hours. And a refined ruthenium (Ru) powder production method.   The high-purity using the used ruthenium (Ru) target according to claim 6, wherein the hydrogen heat treatment is performed at a temperature of 800 ° C. to 1200 ° C. for 1 to 5 hours. And a refined ruthenium (Ru) powder production method.

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