KR100813816B1 - High Purity Iron, Method Of Manufacturing Thereof, And High Purity Iron Targets - Google Patents

Abstract

The present invention provides high purity iron with a reduced content of impurities such as copper, a production method thereof, and a high purity iron target.

Iron containing impurities such as copper are dissolved in a hydrochloric acid solution to prepare an aqueous solution of iron chloride having a hydrochloric acid concentration of 0.1 to 6 kmol / m 3. Subsequently, iron is added to the aqueous solution of iron chloride and stirred while injecting an inert gas to make copper contained in the aqueous solution of iron chloride become monovalent ions, and iron as divalent ion. Subsequently, the aqueous solution of iron chloride is poured into a column filled with an anion exchange resin. At this time, copper of monovalent ions is adsorbed to the anion exchange resin, but iron of divalent ions is not adsorbed to the anion exchange resin. Thus, copper can be separated from the iron chloride aqueous solution. Thereafter, the aqueous iron chloride solution is evaporated to dryness and oxidized, and heated in a hydrogen atmosphere to produce iron.

High purity iron, high purity iron target, iron chloride aqueous solution, anion exchange resin, hydrochloric acid solution

Description

High Purity Iron, Method Of Manufacturing Thereof, And High Purity Iron Targets}

BRIEF DESCRIPTION OF THE DRAWINGS The flowchart which shows the manufacturing process of the high purity iron and high purity iron target which concerns on one Embodiment of this invention.

FIG. 2 is a flow chart illustrating a manufacturing process following FIG. 1.

FIG. 3 is a view for explaining one manufacturing step shown in FIG. 1. FIG.

4 is a view for explaining another manufacturing process shown in FIG.

Fig. 5 is a characteristic diagram showing a change in metal ion concentration in an eluate of anion exchange resin.

Fig. 6 is another characteristic diagram showing the change of metal ion concentration in the eluate of anion exchange resin.

Explanation of symbols on the main parts of the drawings

11: metal 12: container

13: inert gas 14: stirrer

21: anion exchange resin 22: column

23: storage tank 24: recovery tank

M: iron chloride solution

The present invention relates to high purity iron with a reduced content of impurities such as copper, a method for producing the same, and a high purity iron target.

Semiconductor devices such as VLSI (Very Large Scale Integrated Circuit) and ULSI (Ultra LSI) have a structure in which a thin film of various metals is formed on a silicon (Si) wafer, for example. have. In recent years, studies have been made using iron (Fe) as a material for magnetic random memory (MRAM). However, if iron contains harmful impurities, malfunction or deterioration of the semiconductor device may occur. It is not suitable because it causes). For example, copper (Cu) has a high diffusion rate in silicon, which causes short circuits, and radioactive elements such as uranium (U) and thorium (Th) are likely to malfunction, and alkali metals or alkaline earth metals It may cause deterioration of characteristics.

In addition, iron silicide (FeSi ₂ ) is proposed as an environmental semiconductor material aiming at constructing new engineering to cope with environmental problems or resource depletion problems in the future. The impurity content of iron silicide as an environmental semiconductor is the same as that of a compound semiconductor represented by gallium arsenide (GaAs) or cadmium telluride (CdTe), which is currently commonly used, and is significantly higher than that of a semiconductor device called VLSI or ULSI. little. If an unnecessary impurity level is formed by a small amount of impurities, it immediately leads to deterioration of semiconductor characteristics, and therefore iron, which is a raw material, is required to be of high purity.

By the way, the grade of the crude iron (crude iron) currently being traded around the world is about 98% to 99.8%. Such raw iron includes transition metals such as nickel (Ni), cobalt (Co) or chromium (Cr), and gaseous elements such as oxygen (O), nitrogen (N) or sulfur (S), It contains various impurities. Therefore, in order to use iron as a material of a semiconductor device or an environmental semiconductor, it is necessary to remove these impurities from raw iron and to make it highly purified. In addition to the semiconductor device, iron is very promising as a material such as a magnetic recording medium or a magnetic recording head utilizing the characteristics as a ferromagnetic metal. Higher purity of iron is also essential for its use.

Various studies have been conducted to remove impurities from raw iron, and for example, separation of metal elements by wet treatment such as solvent extraction, ion exchange or electrolytic purification, and treatment of dry hydrogen gas (H ₂ ). There is a removal of gaseous elements such as oxygen or nitrogen, or a float zone melting refining method.

However, in solvent extraction, it is difficult to control extraction and reverse extraction and it is difficult to purify iron industrially. In ion exchange, almost all metallic impurities can be separated, but there is a problem that the removal of copper is difficult and the content does not change before and after purification. In electrolytic refining, there also existed a problem that control in the pH range of electrolyte solution is needed, and removal of nickel, copper, etc. was difficult. Floating zone molten refining is applied to refined metals to some degree to increase the purity, and reports have been reported to increase the refining effect in real time. {Ishikawa Yukio, Mimura Koji, Ishiki Minoru, Tohoku University Institute of Materials Research , 51 (1995), 10 to 18}, since it is difficult to increase the size and is not a stable production method, it is difficult to produce a large amount of high-purity iron at low cost. Therefore, there has been a demand for the development of a method for high-purity iron, particularly a method for removing copper, easily and stably.

This invention is made | formed in view of such a problem, The 1st objective is to provide the high purity iron and high purity iron target by which content of copper which is an impurity was reduced.

It is a second object of the present invention to provide a method for producing high purity iron, which can easily and stably obtain high purity iron.

The high purity iron according to the present invention has a purity of 99.99% by mass or more and a concentration of copper as an impurity of 50% by mass ppb or less.

Other high purity iron according to the present invention has a residual resistance ratio of 3000 or more and a concentration of copper as an impurity of 50 mass ppb or less.

In the method for producing high purity iron according to the present invention, iron contained in an aqueous solution of iron chloride is a divalent ion, copper contained as an impurity is a monovalent ion, and a hydrochloric acid concentration is in the range of 0.1 kmol / m 3 or more and 6 kmol / m 3 or less. It adjusts inward and isolate | separates the copper of monovalent ion from the iron chloride aqueous solution with ion exchange resin.

In another method for producing high purity iron according to the present invention, iron contained in an aqueous solution of iron chloride is used as a divalent ion, and the concentration of hydrochloric acid is 0.1 kmol / m 3. Adjusted within the range of 6 kmol / ㎥ or less, zinc, gallium, niobium, technetium, ruthenium, rhodium, palladium, silver, cadmium, indium, tin, antimony, tellurium, tantalum, tungsten, rhenium, osmium, iridium, platinum, And a step of separating at least one impurity from the group consisting of gold, mercury, thallium, lead and bismuth from an aqueous solution of iron chloride with an anion exchange resin.

The high purity iron target according to the present invention has a purity of 99.99 mass% or more and a concentration of copper as an impurity of 50 mass ppb or less.

Another high purity iron target according to the present invention has a residual resistance ratio of 3000 or more and a concentration of copper as an impurity of 50 mass ppb or less.

In the high purity iron and the high purity iron target according to the present invention, the concentration of copper is highly purified to 50 mass ppb or less.

In the method for producing high-purity iron according to the present invention, hydrochloric acid concentration is adjusted using iron as a divalent ion and copper as a monovalent ion. Thereby, while copper which is monovalent ion is adsorb | sucked to an anion exchange resin, iron which is bivalent ion is not adsorb | sucked, and copper is isolate | separated easily and stably from the iron chloride aqueous solution.

In another manufacturing method of high purity iron which concerns on this invention, hydrochloric acid concentration is adjusted using iron as a bivalent ion. Thus, zinc, gallium, niobium, technetium, ruthenium, rhodium, palladium, silver, cadmium, indium, tin, antimony, tellurium, tantalum, tungsten, rhenium, osmium, iridium, platinum, gold, mercury, thallium, lead and bismuth While at least one impurity in the group consisting of is adsorbed on the anion exchange resin, iron of divalent ions is not adsorbed, and such impurities are easily and stably separated from the iron chloride aqueous solution.

EMBODIMENT OF THE INVENTION Hereinafter, embodiment of this invention is described in detail with reference to drawings.

The high purity iron and the high purity iron target according to one embodiment of the present invention have a purity of 99.99 mass% or more, suitably 99.999 mass% or more, or a residual resistance ratio of 3000 or more, and a concentration of copper as an impurity of 50 mass ppb or less.

Here, purity (i.e. chemical purity) is obtained by quantifying all concentrations of impurities quantifiable using currently available analytical instruments and methods, and subtracting them from 1 {Isuki Minoru, Mimura Koji, Japanese Metal Society Bulletin, 31 (1992) , 880-887}. For example, it is calculated | required by using Glow Discharge Mass Spectroscopy for an analytical instrument, and measuring 70 elements or more quantifiable impurities, and subtracting from 1. For gaseous elements such as oxygen, nitrogen or hydrogen, the thermal conductivity is measured by melting in a non-disperasive infrared absorption method, thermal conductivity method or inert gas, and then separating them into columns. Appropriate methods are applied.

In addition, the residual resistance ratio is an index indicating the purity of the high purity metal, and the ratio of the specific resistance in 298K and the specific resistance in 4.2K is obtained as shown in Equation (1). Since the specific resistance is related to the resistance value (electrical resistance) as shown in Equation 2, the residual resistance ratio can be converted as shown in Equation 3, and if the volume change due to temperature is negligible, Is approximated by the ratio of the resistance to In addition, since iron is a ferromagnetic metal, when measuring resistance, it is necessary to suppress the influence by the magnetic field by geomagnetism, element conditions, or a measurement current, etc., and it is a seed field of about 60 kA / m normally. (V) (vertical magnetic method) to perform the measurement (see Takagi Seichi, Materia, 33 (1994), 6 to 10).

RRR; Residual resistance ratio

ρ _{298 K} ; Resistivity at 298 K (Ωm)

ρ _4.2K ; Resistivity at 4.2K (Ωm)

ρ; Resistivity (Ωm)

R; Resistance value (Ω)

S; Cross section area perpendicular to the direction of current (m ² )

L; Length (m)                     

RRR; Residual resistance ratio

R _298K , S _298K , L _298K ; Resistance value, cross-sectional area and length at 298 K

R _4.2K , S _4.2K , L _4.2K ; Resistance value, cross-sectional area, length at 4.2K

This high purity iron and high purity iron target are used as materials, for example, a semiconductor device, a magnetic recording medium, a magnetic recording head, or a device using an environmental semiconductor. In addition, environmental semiconductor field, will exist in abundance on earth and in addition, the semiconductor material consisting of a material excellent in the environment, for example, there may be mentioned sintered iron (FeSi ₂₎ or sintering calcium (Ca ₂ Si) {environment See the Semiconductor Research Society homepage (http://kan.engjm.saitama-u.ac.jp/SKS/index2.html).

Such high purity iron and high purity iron target can be prepared as follows.

1 and 2 are diagrams showing a manufacturing process of high purity iron according to the present embodiment. First, iron containing impurities such as copper is dissolved in a hydrochloric acid solution to prepare an iron chloride (FeCl ₂ or FeCl ₃ ) aqueous solution (step S101). At that time, the hydrochloric acid concentration is adjusted within a range of 0.1 kmol / m 3 or more and 6 kmol / m 3 or less.

Next, as shown in FIG. 3, the aqueous iron chloride solution M is placed in the container 12 together with the metal 11 such as iron, and an inert gas such as nitrogen gas (N ₂ ) or argon gas (Ar) ( 13) is injected, and the aqueous solution of iron chloride (M) and the metal (11) are agitated sufficiently by, for example, agitator 14 (stirrer) (step S102). As a result, the copper contained in the aqueous iron chloride solution M reacts, for example, as shown in the general formula (1) to form monovalent ions or metallic copper from divalent ions. In addition, iron contained in aqueous iron chloride solution (M) reacts, for example, as shown in general formula (2), and turns into trivalent ion from trivalent ion. In addition, the reaction formula shown in Formula 1 does not fully progress to the right side, and monovalent copper ions remain in a small amount of iron chloride aqueous solution.

Injecting the inert gas 13 into the aqueous solution of iron chloride (M) is for extracting oxygen dissolved in the aqueous solution of iron chloride (M). If it is dissolved, do not proceed. The inert gas 13 may be injected at the same time as the iron chloride aqueous solution M and the metal 11 are stirred, or before the metal 11 is added to the iron chloride aqueous solution M.

The metal 11 is preferably a large surface area such as powder. This is because copper and iron can be sufficiently reacted by increasing the contact area with the iron chloride aqueous solution (M). Although metal other than iron can be used, the suitable thing is iron. This is to prevent possible incorporation of other impurities into the iron chloride aqueous solution (M).

In addition, after adjusting the hydrochloric acid concentration of the aqueous solution of iron chloride (M), the solution of iron chloride (M) and the metal (11) were brought into contact with the iron to be a divalent ion and copper to the monovalent ion. ) May be brought into contact with the metal 11 to form iron as a divalent ion and copper as a monovalent ion, and then the concentration of hydrochloric acid in the aqueous iron chloride solution M may be adjusted.

Subsequently, as shown in FIG. 4, the column 22 filled with the anion exchange resin 21 is prepared, the aqueous solution of iron chloride M is poured from the storage tank 23 into the column 22, and anion exchange is carried out. It is made to fully contact with resin 21 (step S103). The flow rate of the aqueous solution of iron chloride (M) is suitably {1 bed volume (s) / hour} flowing through the resin capacity for 1 hour so that the aqueous solution of iron chloride (M) sufficiently contacts the anion exchange resin 21. Here, since iron is a divalent ion and copper is a monovalent ion, copper of monovalent ion is adsorb | sucked to the anion exchange resin 21, and iron of a divalent ion is carried out to the anion exchange resin 21 here. It is eluted from the column 22 without adsorption at all. The change (elution curve) of the metal ion concentration in the eluate at this time is shown in FIG. In Fig. 5, the horizontal axis represents the elution capacity, and the vertical axis represents the concentration normalized to the maximum concentration of metal ions. Thus, it can be seen that the peak of the elution curve between the iron of the divalent ion and the copper of the monovalent ion does not overlap at all, and the copper can be completely separated from the aqueous iron chloride solution. That is, the iron chloride aqueous solution M from which copper was isolate | separated is collect | recovered in the recovery tank 24. FIG.

In addition, zinc (Zn), gallium (Ga), niobium (Nb), technetium (Tc), ruthenium (Ru), rhodium (Rh), palladium (Pd), silver (Ag), and cadmium (M) Cd), Indium (In), Tin (Sn), Antimony (Sb), Tellurium (Te), Tantalum (Ta), Tungsten (W), Rhenium (Re), Osmium (Os), Iridium (Ir), Platinum In the case where at least one impurity is included in the group consisting of (Pt), gold (Au), mercury (Hg), thallium (Tl), lead (Pb) and bismuth (Bi), zinc and tin are shown in FIG. As shown by step S103, these impurities are also adsorbed to the anion exchange resin 21 together with the copper and separated from the iron chloride aqueous solution M by step S103.

After the copper is separated, lithium (Li), beryllium (Be), sodium (Na), magnesium (Mg), aluminum (Al), silicon (Si), phosphorus (P), and potassium (K) are added to an aqueous solution of iron chloride (M). ), Calcium (Ca), scandium (Sc), titanium (Ti), vanadium (V), chromium (Cr), manganese (Mn), cobalt (Co), nickel (Ni), rubidium (Rb), strontium (Sr) ), Yttrium (Y), zirconium (Zr), cesium (Cs), barium (Ba), lanthanoids, hafnium (Hf), francium (Fr), radium (Ra) and actinoids When one type of impurity is contained, hydrogen peroxide solution is put in the iron chloride aqueous solution M, for example, and it oxidizes, and iron is made into a trivalent ion from divalent ion (step S104). In addition, since oxidation occurs naturally even if left unattended, it is not necessary to actively perform the oxidation step.

Thereafter, the hydrochloric acid concentration of the aqueous solution of iron chloride (M) is 2 kmol / m 3 or more and 11 kmol / m 3 It adjusts to the following ranges, and as shown in FIG. 4, the iron chloride aqueous solution M is made to fully contact with anion exchange resin 21 (step S105). Thus, iron of trivalent ions is adsorbed on the anion exchange resin 21, and lithium, beryllium, sodium, magnesium, aluminum, silicon, phosphorus, potassium, calcium, scandium, titanium, vanadium, chromium, manganese, cobalt, nickel, Rubidium, strontium, yttrium, zirconium, cesium, barium, lanthanoids, hafnium, francium, radium and actinoids elute without adsorbing to the anion exchange resin 21.

The change (elution curve) of the metal ion concentration in the eluate at this time is shown in FIG. 6 represents aluminum, silicon, phosphorus, titanium, manganese, cobalt, and chromium in comparison with iron, and the horizontal and vertical axes are the same as in FIG. 5. As such, it can be seen that the peak of the eluting curve of the impurity and trivalent ions of iron has almost no overlapping portion, and the impurity and iron can be almost separated.

In addition, zinc, gallium, niobium, molybdenum (Mo), technetium, ruthenium, rhodium, palladium, silver, cadmium, indium, tin, antimony, tellurium, tantalum, tungsten, rhenium, osmium, iridium, When at least one impurity is included in the group consisting of platinum, gold, mercury, thallium, lead, bismuth and polonium (Po), in step S105, such an impurity is also anion exchange resin 21 together with iron. Is adsorbed on.

In this case, iron is adsorbed to the anion exchange resin 21, and then a hydrochloric acid solution having a concentration of 0.1 kmol / m 3 or more and 2 kmol / m 3 or less is flowed to elute iron from the anion exchange resin 21, and anion together with iron. Zinc, gallium, niobium, molybdenum, technetium, ruthenium, rhodium, palladium, silver, cadmium, indium, tin, antimony, tellurium, tantalum, tungsten, rhenium, osmium, iridium, platinum, gold, mercury, Thallium, lead, bismuth, polonium, and iron are separated (step S106). The change (elution curve) of the metal ion concentration in the eluate at this time is shown in FIG. FIG. 6 compares molybdenum and zinc with iron on behalf of the impurities described above. Thus, it can be seen that the peaks of the elution curve of these impurities and iron of trivalent ions almost do not overlap, and these impurities and iron can be almost separated.

However, in this case, in step S103, zinc, gallium, niobium, technetium, ruthenium, rhodium, palladium, silver, cadmium, indium, tin, antimony, tellurium, tantalum, tungsten, rhenium, osmium, iridium, platinum, gold, Since mercury, thallium, lead and bismuth are separated from the iron chloride aqueous solution M together with copper, molybdenum and polonium are mainly separated from iron in step S106.

After eluting iron, the resulting aqueous iron chloride solution M is evaporated to dryness and oxidized to form iron oxide (step S107). Then, iron oxide is heated to the temperature of 500K or more and less than 1800K in hydrogen atmosphere (step S108). However, in order to perform reduction quickly, it is suitable to heat at the temperature of 1000K or more. Thereby, iron oxide reacts as shown in General formula (3), and iron is obtained.

After reacting the iron oxide, the obtained iron is melted with a plasma arc using a plasma generating gas containing active hydrogen, and at least 1 is selected from the group consisting of oxygen, nitrogen, carbon (C), sulfur, halogen, alkali metal and alkaline earth metal. The impurities of the species are removed (step S109). Thereby, the high purity iron and the high purity iron target which concern on this embodiment are obtained.

Thus, according to the high purity iron and the high purity iron target of this embodiment, since copper concentration can be 50 mass ppb or less, even if it uses for a semiconductor device, the characteristic of a semiconductor device is improved, without generating a short circuit, for example. You can. Moreover, it can also be used for devices, such as a magnetic recording medium, a magnetic recording head, etc., and can improve such a characteristic. In addition, when used as a material of a compound semiconductor such as iron silicide, an excellent impurity can be obtained without forming unnecessary impurity levels due to trace impurities which cause deterioration of characteristics.

Moreover, according to the manufacturing method of the high purity iron which concerns on this embodiment, after adjusting iron into divalent ion, copper as monovalent ion, and adjusting hydrochloric acid concentration in the range of 0.1 kmol / m <3> or more and 6kmol / m <3> or less, aqueous iron chloride solution Since copper was brought into contact with the anion exchange resin, copper can be easily separated from the iron chloride aqueous solution. Therefore, high-purity iron and high-purity iron targets with low copper concentration can be easily stabilized and obtained.

Furthermore, since iron is used as a divalent ion, zinc, gallium, niobium, technetium, ruthenium, rhodium, palladium, silver, cadmium, indium, tin, antimony, tellurium, tantalum, tungsten, rhenium, osmium, iridium, platinum At least one impurity in the group consisting of, gold, mercury, thallium, lead and bismuth can be easily separated from the iron chloride solution together with copper. Therefore, high purity iron and high purity iron targets can be obtained easily and stably.

EXAMPLE

In addition, embodiments of the present invention will be described in detail with reference to FIGS. 1 to 6. In addition, in the following Example, the code | symbol used and the symbol used in the said Example are used as it is corresponded as it is.

First, scrap iron is used as a raw material, and it is dissolved in a hydrochloric acid solution having a concentration of 2 kmol / m ₃ so that the iron concentration is 0.179 kmol / m 3 (10 g / d m ₃ ), and an aqueous solution of iron chloride (FeCl ₃ ) (M) is dissolved. It manufactured (step S101). Then, as shown in Fig. 3, powdered iron 11 was placed in the aqueous iron chloride solution M, stirred while injecting an inert gas to make copper monovalent ions, and iron as divalent ions. (Step S102). Subsequently, as shown in FIG. 4, the aqueous solution of iron chloride (M) was brought into contact with the anion exchange resin 21, and copper was adsorbed and separated from the aqueous solution of iron chloride (M) (step S103).

After separating copper, hydrogen peroxide solution was added to the aqueous solution of iron chloride (M) to make iron trivalent ions (step S104). Thereafter, the hydrochloric acid concentration of the aqueous solution of iron chloride (M) was 5 kmol / m 3, and the aqueous solution of iron chloride (M) was brought into contact with the anion exchange resin 21 to adsorb iron and separated from impurities such as lithium (step S105). Subsequently, iron was eluted from the anion exchange resin 21 with a hydrochloric acid solution having a concentration of 1 kmol / m 3 and separated from impurities such as molybdenum (step S106).

After eluting iron from the anion exchange resin 21, the obtained aqueous iron chloride solution M was evaporated to dryness and oxidized to obtain iron oxide (step S107). Then, the obtained iron oxide was heated to 1073K (800 degreeC) in hydrogen atmosphere, and iron was obtained (step S108). After iron was obtained, iron was melted in a plasma arc containing active hydrogen to remove impurities such as oxygen (step S109) to obtain high purity iron.

With respect to the obtained high purity iron, impurities were quantified by glow discharge mass spectrometry to determine purity, and to obtain a residual resistance ratio. The results are shown in Table 1. As shown in Table 1, the copper concentration was extremely low at 50 mass ppb or less, the purity was 99.9997%, and the residual specific resistance was 5500, which was extremely high.

element Concentration (ppm) element Concentration (ppm) element Concentration (ppm)      Impurity concentration Al As B Ba Be Bi Ca Cd Cl Cr Cu F 0.380 <0.050 <0.010 <0.010 <0.010 0.012 0.110 0.120 <0.050 <0.020 <0.020 <0.050 Co Ga Hf In K Li Mg Mn Mo Na Ni P 0.035 0.050 <0.010 <0.020 0.015 <0.010 <0.010 <0.050 <0.050 <0.010 <0.020 0.740 Rh Ru Sb Si Sn Th Ti U V Zn Zr Pb <0.010 <0.010 <0.020 0.060 0.270 0.001 0.150 0.002 1.000 0.050 0.016 0.014 water 99.9997% Residual Resistance Ratio 5500

That is, by making iron as a divalent ion, making copper a monovalent ion, and adjusting hydrochloric acid concentration to 0.1 kmol / m <3> or more and 6kmol / m <3> or less, copper can be isolate | separated easily from the iron chloride aqueous solution, and copper It was found that high purity iron having a reduced concentration of 50 to 50 mass ppb or less can be easily obtained.

As mentioned above, although this invention was described based on embodiment and an Example, this invention is not limited to the said embodiment and Example, It can variously change. For example, in the above embodiments and examples, the concentration of hydrochloric acid in the aqueous iron chloride solution is adjusted using iron as the divalent ion and copper as the monovalent ion in the iron chloride aqueous solution, and the iron chloride aqueous solution is brought into contact with the anion exchange resin, Although copper was adsorbed and separated, after adjusting the ion valence of iron and copper, iron and copper were adsorbed to the anion exchange resin, and the concentration was 0.1 kmol / m 3 or more and 6 kmol / m 3. The copper may be separated from the iron chloride aqueous solution by being able to elute iron with the following hydrochloric acid solution.

In addition, although the said embodiment and Example demonstrated the method of removing impurities other than copper concretely, you may make it remove by another method. In addition, although iron is used as a divalent ion, impurities such as zinc are separated from the aqueous iron chloride solution together with copper, but copper may be separated by another method.

As described above, according to the high-purity iron target according to claim 1 or 2 or the high-purity iron target according to claim 12 or 13, since the concentration of copper can be 50 mass ppb or less, for example, it is used in semiconductor devices. Even if it does not generate a short circuit, it has the effect of improving the characteristics of the semiconductor device. Moreover, it can also be used for devices, such as a magnetic recording medium, a magnetic recording head, etc., and can improve those characteristics. In addition, when used as a material of a compound semiconductor such as iron silicide, an unnecessary impurity level due to trace impurities that cause deterioration of characteristics is not formed, and excellent characteristics can be obtained.

Further, according to the method for producing high purity iron according to the present invention, iron is a divalent ion, copper is a monovalent ion, and the hydrochloric acid concentration is 0.1 kmol / m 3 Since adjustment was made in the range of 6 kmol / m <3> or more, copper can be adsorb | sucked to an anion exchange resin and can be isolate | separated easily from the iron chloride aqueous solution. Therefore, it has the effect that a high purity iron and a high purity iron target with low copper concentration can be obtained easily and stably.

Furthermore, according to the method for producing high-purity iron according to the present invention, since iron is used as a divalent ion and hydrochloric acid concentration is adjusted within the range of 0.1 kmol / m 3 or more and 6 kmol / m 3 or less, impurities such as zinc are anion exchange resin. It can be easily separated from the iron chloride aqueous solution by adsorbing on. Therefore, it has the effect that a high purity iron and a high purity iron target can be obtained easily and stably.

Claims (13)

High purity iron whose purity is 99.99 mass% or more and 99.9997 mass% or less, and the density | concentration of copper which is an impurity is 20 mass ppb or more and 50 mass ppb or less. High purity iron having a residual resistivity ratio of 3000 to 5500 and a concentration of copper as an impurity of 20 to 50 mass ppb. delete delete delete delete delete delete delete delete delete A high purity iron target having a purity of 99.99% by mass or more and 99.9997% by mass or less and a concentration of copper as an impurity of 20% by mass or more and 50% by mass or less. A high purity iron target having a residual resistance ratio of 3000 or more and 5,500 or less and a concentration of copper as an impurity of 20 to 50 mass ppb.

Images