KR20120121131A - Manufacturing method of a high purity Ru powder and target using a waste Ru target - Google Patents

Abstract

PURPOSE: A method for producing super high-purity Ru powder and target using waste Ru targets is provided to improve the function of a sputtering target material by pulverizing Ru powder and target using plasma instead of rough crushing. CONSTITUTION: A method for producing super high-purity Ru powder and target using waste Ru targets comprises the steps of: removing pollutants remaining on the surface of waste Ru targets with a chemical or mechanical method, producing Ru powder from the waste Ru targets using plasma, heat-treating and pulverizing the Ru powder to obtain high-purity Ru powder, press-molding the high-purity Ru powder to obtain a high-density sintered Ru body, and post-processing the sintered Ru body into a Ru target with controlled surface roughness.

Description

Manufacturing method of a high purity Ru powder and target using a waste Ru target {Manufacturing method of a high purity Ru powder and target using a waste Ru target}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing ruthenium (Ru) powder and a target, which are recently used in a seed layer for forming a magnetic layer according to a large capacity and a high density associated with a magnetic recording medium or a next generation memory, and a surface of a used ruthenium target after use. Simple removal of contaminants and foreign substances remaining on the surface from the surface physically and mechanically, to prepare ultra high purity ruthenium (Ru) powder using plasma, grinding and heat treatment, and high density ruthenium (Ru) target through hot pressing For the purpose of manufacturing.

The vaporized or scattered ruthenium (Ru) powder was prepared by using a thermal plasma on a waste ruthenium (Ru) target, and fine and ultra-purified ruthenium (Ru) powder was prepared by pulverization and heat treatment, and then hot pressed. The present invention relates to the production of high density ruthenium (Ru) targets by molding, and more particularly, to manufacturing ruthenium (Ru) powders and targets using the wet method, which is conventionally used to produce ruthenium (Ru) powder. Compared with the present invention, the present invention relates to a ruthenium (Ru) powder and a target manufacturing method using a plasma that is environmentally friendly, shortens a process, and can shorten manufacturing time.

In general, according to the application of wafers used in connection with next-generation semiconductor memories (RAM, MRAM, FeRAM), heads (MR, TMR), and capacitors, or the vertical magnetic method for increasing the capacity of hard disks, Ruthenium (Ru) thin films are frequently used to form seed layers for effective arrangement of magnetic layers, and because ruthenium (Ru) powder for manufacturing such ruthenium (Ru) sputtering targets is expensive, waste ruthenium ( Ru) Recycling the target (Ru) is used to produce ruthenium (Ru) powder and the target. Ruthenium (Ru) targets are not only difficult to process at room temperature due to the properties of the material, but are also manufactured using a sintering method rather than a dissolution method due to the characteristics of oxidation and volatilization in the air even at high temperatures. In addition, the preparation of fine ruthenium (Ru) powder and high purity powder is essential for fine grain control of the target.

Most ruthenium (Ru) powder is manufactured by the wet method. Briefly, the ruthenium (Ru) powder is wet-dissolved using strong acid solution to the waste target, followed by distillation, concentration, drying, oxidation and heat treatment. To prepare.

However, when the wet method is applied, there is a risk in handling due to the use of strong acid solution, it takes a lot of time to dissolve and obtain the final powder in acid solution, and also takes a manufacturing time and cost according to complex process application, After use, a considerable amount of wastewater treatment costs are additionally generated.

Recently, in order to supplement the wet method, ruthenium (Ru) powder has been tried to be prepared using only a grinding process, but the powder is manufactured by applying only mechanical grinding. Due to the pulverization applied for the generation of contamination by the crushing device, and to remove the contaminant using an acid solution to remove the proposal to add a situation that is insufficient for the production of high purity powder.

The present invention relates to a method for producing fine and highly purified ruthenium (Ru) powder using waste ruthenium (Ru) target, and to produce a high density target using the prepared powder. To solve this problem, instead of dissolving and manufacturing powders using conventional chemicals, eco-friendly plasma processes are used, powders are prepared, high purity through powder grinding and heat treatment, and ruthenium (Ru) target through hot pressing. The purpose is to prepare. When the powder and the target is produced through this, the manufacturing time is shortened compared to the existing manufacturing method, and the waste solution is not generated due to the non-use of acid solution, which is environmentally friendly, and the manufacturing process is simple, so that the powder and the target can be manufactured in a short time. There is an advantage.

In order to solve this problem, the contaminants remaining on the surface of the waste ruthenium (Ru) target are removed by physical or chemical methods such as polishing on the surface or by chemical methods, and high purity ruthenium (Ru) using a plasma device. It is intended to prepare a powder, and finally to obtain a high purity and refined ruthenium (Ru) powder through pulverization and classification to the prepared powder.

The present invention is to remove the surface contaminants and foreign substances to the ruthenium (Ru) target using a chemical or mechanical method, and to produce ruthenium (Ru) powder using a thermal plasma equipment, and then high-purity ruthenium using grinding and heat treatment Prepare a powder. In addition, a high purity ruthenium (Ru) target is obtained by using high temperature press molding for the finally obtained high purity ruthenium powder.

As described above, in the conventional wet method, a complicated process (wet dissolution, concentration, drying and heat treatment) is applied to prepare a powder, which takes a long time of several days or more, and handling constraints and waste solution treatment using strong acid solution. There are a number of disadvantages, including the cost involved.

In addition, the recently known dry method is a situation that solves this by applying some wet process due to contamination due to coarse grinding.

However, the present invention is characterized by introducing a dry method rather than a wet method in the production of ruthenium (Ru) powder, and to produce a ruthenium (Ru) powder using a plasma instead of coarse grinding. Through this, it is expected to shorten the final powder and target L / T, and to manufacture high purity and refined ruthenium (Ru) powder and target, thereby improving the function of the sputtering target material.

FIG. 1 is a FESEM image of vaporized ruthenium (Ru) powder prepared by using a plasma on a waste ruthenium (Ru) target.
FIG. 2 is an FESEM image of ruthenium arsenate (Ru) powder prepared using plasma to a waste ruthenium (Ru) target.
FIG. 3 is an FESEM image of ruthenium (Ru) powders that have been ground, quenched and hydrothermally treated using ruthenium (Ru) powders prepared by plasma.

The present invention is to produce a ruthenium powder using a waste ruthenium (Ru) target to prepare the powder by using a plasma, not a conventional wet method, or mechanical grinding method, the final high purity and refinement through fine grinding and heat treatment It is characterized by producing a ruthenium (Ru) powder. Through this, manufacturing time is drastically shortened compared to the conventional wet method, and it is possible to manufacture ruthenium (Ru) powder to which eco-friendly method is applied by suppressing acid use used for dissolving and contaminants, and manufactured high purity powder The high-temperature pressing molding has the advantage that the crystal grains are fine, and the highly purified ruthenium (Ru) target can be manufactured.

The present invention relates to an ultra-high purity ruthenium (Ru) powder using a waste ruthenium (Ru) target and a method for manufacturing the target, wherein the step of removing contaminants and foreign substances remaining on the surface of the waste ruthenium target using a chemical or mechanical method Preparing a ruthenium powder by using a plasma on the waste ruthenium target from which the contaminants and foreign substances have been removed; and preparing a highly purified ruthenium powder by heat treatment and grinding the manufactured ruthenium powder, and the highly purified ruthenium A high density ruthenium sintered body is manufactured by using hot pressing for the powder, and a ruthenium target having a controlled surface roughness through post-processing is characterized in that it is configured.

Hereinafter, the process steps will be described in detail.

First, contaminants or foreign substances remaining on the surface of the waste ruthenium (Ru) target are removed by chemical or mechanical methods.

The surface of waste ruthenium (Ru) target has a high possibility of surface contamination by handling, contamination by back depo during sputtering process and foreign substance contamination by long-term atmospheric exposure. It is preferable to remove such contaminants or foreign substances before the powder manufacturing process because the remaining contaminants or foreign substances during the preparation flows into the powder and act as a factor of reducing the purity of the powder or the final target. The removal of contaminants is preferably performed using a chemical method of immersing the ruthenium (Ru) solubilizer for a short time and shaving the surface of several tens of micrometers, or removing a certain amount of the thickness layer using a processing machine such as a lathe or a polishing machine. In the case of removal using the above mechanical processing methods, it is desirable to remove the thickness of about 0.1 mm, which is too thin to remove the oxide film is not perfect, if too thick may reduce the final powder yield Because.

In the next step, ruthenium (Ru) powder is prepared using thermal plasma on a waste ruthenium (Ru) target from which contaminants and foreign substances are removed.

In order to produce high purity powder in the powder preparation sequence, the inside of the plasma chamber is cleaned, a waste target is set on the crucible, and plasma is formed to obtain a powder.

It is preferable to first clean the inside of the chamber before the plasma treatment to prevent the incorporation of impurities or foreign matter. In addition, in order to manufacture high-purity powder, it is necessary to minimize contamination by electrodes or molds used to form thermal plasma, and the available mold materials include molybdenum (Mo), tungsten (W), copper (Cu), and graphite ( Graphite) and ruthenium (Ru) are possible, and ruthenium mold of the same material is most preferable to prevent contamination by the mold. However, in the case of highly brittle ruthenium (Ru), it is difficult to manufacture due to difficulty in processing. It is preferable to use a carbon mold which can be easily removed even if it is contaminated. Molybdenum (Mo), tungsten (W), ruthenium (Ru), and the like may be used as the electrode material that can be used for the plasma treatment, but it is most preferable to use ruthenium (Ru) of the same material to minimize contamination by the electrode.

In order to form a plasma, a vacuum pump is used to reduce the pressure, reactant gas is injected, and the working vacuum is adjusted and then electric power is applied. Reaction gases used for plasma formation include Ar, H ₂ , N ₂ , CH ₄ , Ar + H ₂ , Ar + N ₂ It is possible to use a mixed gas, and H ₂ , N ₂ and O ₂ have a high possibility of remaining in the final ruthenium (Ru) powder, and when some are left to be used as a target without being completely removed by air and hydrogen heat treatment. It is most advantageous to use Ar because it may cause particles or arcs during the film formation process, thereby lowering the yield or affecting semiconductor product characteristics. However, even if N ₂ or H ₂ is used to increase the powder manufacturing speed to secure productivity, or even gas components remain in the powder produced by the remaining O ₂ inside the chamber, the powder is completely removed through the degassing treatment after the powder is refined. If possible, the above H ₂ , N ₂ , O ₂ It is also preferable to use a gas.

Ruthenium (Ru) powder is manufactured by increasing the power after plasma formation. When plasma power is increased, a molten metal is formed, and the temperature of the molten metal is increased so that the molten metal above the vaporization temperature is vaporized and cooled to produce a powder, or an ambient atmosphere. And the molten metal is scattered by the reaction gas pressure to prepare a powder. At this time, the applied power is in the range of 10 ~ 100 kw, if it is lower than 10 kw, melt formation, vaporization or scattering may not easily occur, and should be carried out at 100 kw or less in consideration of the stability of the equipment.

Next, a highly purified ruthenium (Ru) powder is prepared by using heat treatment and grinding to the prepared ruthenium (Ru) powder. In the case of ruthenium (Ru) powder produced by plasma, the vaporized powder shows a fine powder size of several hundred nm, but when scattered, coarse powder of several tens of micrometers is obtained, and it is manufactured as a target to make high quality ruthenium (Ru) In order to obtain a thin film, a target having uniform and fine grains is advantageous. Therefore, the finer and more uniform the powder size for producing the target is, the more preferable. However, when only the fine powder is used for the powder produced by the plasma, the overall yield is drastically lowered. Therefore, it is a feature of the present invention to make fine and highly purified powder by making all coarse powders usable.

As a pulverization method for increasing the yield of the powder produced by the plasma, a variety of pulverization such as ball mill, planet mill, jet mill, etc., which are generally used for pulverization, are possible. Preferably jet mill is most preferred. This can be easily crushed in the case of ruthenium (Ru), but may be contaminated by the ball by processing a large amount or increase the working time, such that the high-purity ruthenium (Ru) powder to grind using a jet mill not using the ball It is advantageous to obtain.

In the pulverized powder, since a reaction gas or a carbon component by using a carbon crucible which is frequently used may remain in the powder, high purity ruthenium (Ru) powder can be produced by hydrogen heat treatment after atmospheric heat treatment.

For example, carbon powder, which is a mold material, is contaminated by wt% by high plasma heat.It can be removed by vaporization in the form of CO or CO ₂ through simple queuing, and ruthenium ( Ru) is oxidized to obtain a blue ruthenium (Ru) oxide, and it is preferable to prepare a highly purified ruthenium (Ru) powder using hydrothermal treatment.

In the case of the heat treatment condition, in the case of queuing, the temperature is preferably 600 to 1000 ° C. and heat treatment for 1 to 5 hours. If the temperature is 600 ° C. or less and shorter than 1 hour, there is a high possibility that the remaining carbon is not sufficiently removed, and if the temperature is 1000 ° C. or higher and for a long time of 5 hours or more, the produced powder is likely to aggregate.

In the case of hydrothermal treatment, the temperature is preferably 800 to 1000 ℃ and heat treatment for 1 to 5 hours. If the temperature is 800 ° C or less and less than 1 hour, ruthenium (Ru) oxide is not sufficiently reduced, because if the temperature is 1000 ° C or more and 5 hours or more for a long time it is likely that the prepared powder is agglomerated.

A high-density ruthenium sintered body is manufactured by high temperature press molding on the refined high purity ruthenium powder obtained by heat treatment. In this case, as an applicable high temperature pressing molding method, it is possible to manufacture by using one of hot pressing, hot isostatic pressing, plasma sintering (Spark Plasma Sintering), In order to manufacture a ruthenium target, it is most preferable to use a hot forming method that is easy to control the temperature increase rate and which is easy to remove residual oxygen or other impurities such as C, N, H in the ruthenium (Ru) powder.

In order to manufacture a high density ruthenium (Ru) sintered compact, it is preferable that the applied pressure at high temperature is 10 to 80 MPa and the sintering temperature is performed at 1300 to 1700 ° C. When the applied pressure is 10 Mpa or less and the sintering temperature is 1300 ° C. or less, it is highly likely that a low density sintered body is produced. Is likely to lower. And it is advantageous to work at 80 MPa or less for high cost carbon mold protection, which is frequently used at high sintering temperatures.

The high-density ruthenium (Ru) sintered body manufactured by high temperature pressing molding is subjected to lathe machining and polishing to secure surface roughness for sputtering and to manufacture a final target.

In the case of ruthenium (Ru) sintered body manufactured by high temperature pressing molding, carbon may be contaminated in the contact area of the used carbon mold or carbon sheet, which may affect the thin film during sputtering. It is preferable to remove a certain thickness of about 0.1 to 1 mm by processing or polishing. This is because, if the thickness is too low, the possibility of carbon remaining is high, and if the thickness is 1 mm or more, the overall yield may be lowered to increase the overall cost. In addition, in the case of ruthenium targets used in semiconductor applications, since the surface roughness affects the thin film properties, it is desirable to ensure the surface roughness of 1 ㎛ or less, in order to secure the above-mentioned surface roughness is possible through polishing, In order to shorten the overall manufacturing time, it is preferable to remove a certain thickness by turning, and then remove the remaining thickness by polishing.

[ Example ]

1.8 kg of waste ruthenium (Ru) target with 3N7 purity, 14 μm grains used for seed layer of hard disk was prepared to prepare ruthenium (Ru) powder using waste ruthenium (Ru) target. To remove waste ruthenium (Ru) target surface debris and contaminants, it was immersed in sodium hypochlorite (NaClO) for 30 minutes and the solution on the surface was washed. 1.8 kg of ruthenium (Ru) powder was prepared using a thermal plasma apparatus for the waste ruthenium (Ru) target from which foreign substances were removed.

Ruthenium (Ru) powder prepared by the plasma is shown in Figure 1,2.

In the case of Figure 1 is a vaporized ruthenium powder shows a sphere of several tens of nm size, Figure 2 is a scattered ruthenium powder shows a sphere having a size of 100 ㎛. The prepared ruthenium (Ru) powder was pulverized using a jet mill, and the pulverized ruthenium (Ru) powder was subjected to heat treatment at 800 ° C. for 1 hour in air to remove residual carbon, and at 800 ° C. Hydrothermal heat treatment was carried out for 30 minutes to reduce the ruthenium (Ru) powder oxidized during the queue treatment to obtain a final high purity and refined powder. The shapes for the milled and final heat treated powders are shown in FIG. 3.

In the case of pulverized ruthenium (Ru) powder, it shows a flake shape, and as a result of the particle size analysis, it can be seen that it is composed of a fine powder having a central particle size of 4 μm.

Impurity analysis (Example 1) was performed through Glow Discharge Mass Spectrometry (GDMS) analysis to determine the impurity content of the ruthenium dry powder prepared using the waste target and the waste target. In order to determine the level of the (Ru) powder, a commercially available high purity ruthenium (Ru) powder was purchased and analyzed by a glow discharge mass spectrometer, and the results (Comparative Example 1) are shown in Table 1. In the case of the ruthenium powder obtained by the present invention from Table 1, the same level of impurities and the final purity of the powder except oxygen were maintained compared to the waste target, whereas in the case of commercialized ruthenium powder, acid solution was used. As Na and Cl are not completely removed, the impurity content is higher than 200 ppm and the purity is low.

(Unit: .ppm) impurities Lung target Example 1 Comparative Example 1 Fe 20 23 21 Si 2 12 36 Cl 14 - 32 Na 3 2 25 K 28 <1 25 Ca 10 5 6 Mg 5 8 11 Pd 18 15 - W 3 10 - Pt 25 20 28 Rh <1 10 25 U - - - Th - - - O 120 680 890 Total impurities
(Except O) 128 105 209 Final purity 3N8 3N8 3N7

The ruthenium (Ru) dry powder and the purchased ruthenium (Ru) powder obtained by the present invention were subjected to a sintering test using a hot press, and the characteristics of the manufactured sintered body were compared. (Example 2, Comparative Example 2). In addition, in order to compare the physical properties of the produced sintered compact, the characteristics were also compared with respect to the waste ruthenium target purchased for powder production.

Item Example 2 Comparative Example 2 Comparative Example 3 Density (gr / cm3) 12.34 12.32 12.33 Relative density (%) 99 ↑ 99 ↑ 99 ↑ water 99.98 ↑ 99.97 ↑ 99.98 ↑ Grain (㎛) 6 15 18

Ruthenium (Ru) sintered body produced by the present invention from Table 3, the density and purity of the sintered body produced by using the ruthenium (Ru) powder expected to be produced by wet showed more than equivalent level, commercially available Compared with the ruthenium (Ru) target sold in the present invention, it was found that there is no difference. Particularly, the grain size of the ruthenium (Ru) sintered body of the present invention is smaller than that of a conventional wet powder or a conventional waste ruthenium target. It can be seen that the crystal grains.

Claims (12)

In preparing ultra-high purity ruthenium (Ru) powders and targets using waste ruthenium (Ru) targets,
Removing contaminants and foreign matter remaining on the surface of the waste ruthenium target using a chemical or mechanical method;
Preparing a ruthenium powder using a plasma to the waste ruthenium target from which the contaminants and foreign substances have been removed;
Preparing a highly purified ruthenium powder using heat treatment and grinding to the prepared ruthenium powder;
Preparing a high density ruthenium sintered body by using hot pressing molding the highly purified ruthenium powder;
Ultra-high purity ruthenium (Ru) powder and target manufacturing method using a waste ruthenium (Ru) target, characterized in that the step consisting of producing a ruthenium target with a controlled surface roughness through post-processing. The method of claim 1,
Ultra high purity ruthenium (Ru) powder and target manufacturing method using the waste ruthenium (Ru) target, characterized in that the removal of surface contaminants and foreign matter of the waste ruthenium (Ru) target using a chemical method or a mechanical method. The method of claim 2,
Ultra high purity using waste ruthenium (Ru) target, characterized in that using a solution mixed with sodium hypochlorite (NaClO) solution or sodium hypochlorite (NaClO) as a chemical method for removing contaminants and foreign substances on the surface of the waste ruthenium target Ruthenium (Ru) powder and method for producing a target. The method of claim 2,
Method for producing ultra-high purity ruthenium (Ru) powder and target using the waste ruthenium (Ru) target, characterized in that using a lathe or grinding processing as a mechanical method for removing contaminants and foreign matter on the surface of the waste ruthenium target. The method of claim 1,
The material of the mold used in manufacturing the ruthenium (Ru) powder using the plasma is any one selected from graphite, copper (Cu), molybdenum (Mo), tungsten (W) or ruthenium (Ru). Ultra-high purity ruthenium (Ru) powder and a method for producing a target using a waste ruthenium (Ru) target. The method of claim 1,
The material of the electrode used in manufacturing the ruthenium (Ru) powder using the plasma is a waste ruthenium (Ru) target, characterized in that any one selected from molybdenum (Mo), tungsten (W) or ruthenium (Ru). Ultra high purity ruthenium (Ru) powder and a method for producing a target. The method of claim 1,
Ar, H ₂ , N ₂ , or CH ₄ when forming the plasma Ultra high purity ruthenium (Ru) powder and a method for producing the target using a waste ruthenium (Ru) target, characterized in that the plasma is formed using one or more kinds of gases. The method of claim 1,
The heat treatment of the ruthenium (Ru) powder prepared using the plasma is a high-purity ruthenium (Ru) powder and a target using the waste ruthenium (Ru) target, characterized in that to obtain a high-purity Ru powder by performing an air heat treatment and hydrogen heat treatment Way. The method of claim 8,
The queue treatment is a method for producing ultra-high purity ruthenium (Ru) powder and target using waste ruthenium (Ru) target, characterized in that the heat treatment for 1 to 5 hours at a temperature of 800 ℃ to 1000 ℃. The method of claim 8,
The hydrothermal treatment is a method for producing ultra-high purity ruthenium (Ru) powder and target using waste ruthenium (Ru) target, characterized in that heat treatment for 1 to 5 hours at a temperature of 800 ℃ to 1000 ℃. The method of claim 1,
Grinding the ruthenium (Ru) powder prepared using the plasma is any one selected from ball mill, planetary mill or jet mill, using waste ruthenium (Ru) target Ultra high purity ruthenium (Ru) powder and a method for producing a target. The method of claim 1,
The hot pressing is hot rubbing (Hot Press), hot isostatic pressing (Hot Isostatic Press) or plasma sintering (Spark Plasma Sintering), characterized in that any one selected from ultra high purity ruthenium (Ru) using a waste ruthenium (Ru) target Ru) Method of preparing powders and targets.

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