JP2003138322A - Method of manufacturing high-purity metal, high-purity metal, sputtering target consisting of this high-purity metal and thin film formed by this sputtering target - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method which uses electrodeposition metals such as iron, nickel and cobalt, obtained by using a hydrochloric acid-base bath or sulfuric acid-base bath, decreases gaseous components and inclusions incorporated in vacuum dissolving as far as possible and simultaneously manufactures the metals of high purity such as iron, nickel and cobalt, high-purity metals obtained by the method, a sputtering target consisting of these high-purity metals and a thin film formed by this sputtering target. SOLUTION: The method of manufacturing the high-purity metals having purity above 4N5 (99.995 wt.%) constituted by mixing the electrodeposited metals manufactured by using the hydrochloric acid-base bath and the electrodeposited metals manufactured by using the sulfuric acid-base bath and subjecting the mixture to vacuum to remove a gaseous component and to form an ingot.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a high-purity metal having a purity of 4N5 (99.995 wt%) or more, particularly a high-purity metal from an electrodeposited metal obtained by electrolytic refining or electrolytic extraction using a hydrochloric acid type bath and a sulfuric acid type bath. The present invention relates to a method for producing iron, nickel or cobalt nickel, a high-purity metal obtained thereby, a sputtering target made of the same high-purity metal, and a thin film formed by the sputtering target.

[0002]

2. Description of the Related Art Generally, high-purity metals having a purity level of 4N5 or higher, particularly high-purity iron, nickel or cobalt are indispensable materials for forming magnetic thin films for electronic and electric parts. Usually, a sputtering method is used as a method for forming a thin film of these materials on a substrate. As is well known, in the thin film forming method by sputtering, plasma is formed by discharging plasma between a substrate and a target in an atmosphere of an inert gas such as argon, and thereby ionized argon ions are made to collide with a target on the cathode side, and the target material Are ejected to the opposing substrate side to deposit the same target material component on the substrate.

[0003] Such a magnetic thin film forming material is required to have a purity of 4N5 level or higher in order to utilize its characteristics, but a purity of 4N5 (99.995 wt) except for gas components.
%) Has been achieved. However, recently, it has been found that oxygen, chlorine, hydrogen, etc., which are the above-mentioned gas components, cause particles and nodules due to abnormal discharge in the step of sputtering the target, and reduce these as much as possible. There is a request.
Usually, vacuum melting, particularly electron beam melting is effective for removing these gas components.

On the other hand, since iron, nickel, cobalt, etc. used as the above-mentioned magnetic thin film forming material can produce a high-purity metal at a relatively low cost, they can be electrorefined or purified by using a hydrochloric acid bath or a sulfuric acid bath. It is usually manufactured by electrowinning. However, it has been found that the high-purity iron, nickel, cobalt and the like obtained by these have large amounts of impurities such as oxygen, chlorine, hydrogen and sulfur as gas components depending on the conditions of electrodeposition. That is,
The electrodeposited metal produced using a hydrochloric acid bath has a high content of oxygen (O), chlorine (Cl), and further hydrogen (H) as impurities, while the electrodeposited metal is produced using a sulfuric acid bath. In the case of obtaining, there was a problem that the amount of sulfur (S) increased. If the contents of oxygen, chlorine, and hydrogen become high, abnormal discharge is likely to occur, and if it is attempted to reduce this, the yield will decrease. Further, if the sulfur content in the material is increased as described above, the workability is significantly reduced. Therefore, when the ingot is subjected to forging or rolling on the target, cracks occur and the yield decreases.

If a large amount of the above-mentioned gas component impurities is contained, there is a problem that the impurities cannot be sufficiently removed even by vacuum melting such as electron beam melting. Also,
When a large amount of such a gas component is contained, splash is increased during vacuum melting and the yield is reduced. Although a method of thoroughly removing such a gas component by prolonging the purification time by vacuum melting can be considered, the yield is also greatly reduced due to volatilization of the target high-purity metal. Further, depending on the crucible component used in the electron beam melting, for example, when a ceramic crucible is used, there is a problem that the ceramic component is mixed as a non-metallic inclusion as an impurity in the target thereafter. It was found that this non-metal inclusion also causes the generation of particles and nodules during sputtering. Although it is possible to use a copper crucible instead of a ceramic crucible, the electrodeposited metal obtained by using a sulfuric acid bath in particular involves the copper from the copper crucible, which causes impurities in the copper. There was a problem that the amount increased.

[0006]

According to the present invention, a high-purity metal can be produced at a relatively low cost. Therefore, an electrodeposited metal such as iron, nickel or cobalt obtained by using a hydrochloric acid-based bath or a sulfuric acid-based bath can be used. Along with use, a method for producing high-purity metals such as iron, nickel, and cobalt with a high yield while reducing gas components and inclusions mixed during vacuum melting as much as possible,
Another object of the present invention is to provide a high-purity metal obtained thereby, a sputtering target made of the same high-purity metal, and a thin film formed by the sputtering target.

[0007]

In order to solve the above problems, an electrodeposited metal produced by using a hydrochloric acid-based bath and an electrodeposited metal produced by using a sulfuric acid-based bath are mixed to obtain impurities such as gas components. It was found that the yield can be improved by adjusting the impurities finally obtained by adjusting the amount of. Based on this finding, the present invention provides 1. The electrodeposited metal produced using a hydrochloric acid-based bath and the electrodeposited metal produced using a sulfuric acid-based bath were mixed, and this was vacuum melted to form an ingot.
1. A method for producing a high-purity metal having a purity of not less than wt% 2. The ratio of electrodeposited metal manufactured using a hydrochloric acid bath is 5 to 9
2. The method for producing a high-purity metal according to the above 1, wherein the content is 5 wt%. 3. The method for producing a high-purity metal according to the above 1 or 2, wherein the melting is performed in a vacuum using a copper crucible. 4. The method for producing a high-purity metal according to the above 1 or 2, wherein the melting is performed in a vacuum using a crucible of the same quality as the high-purity metal to be produced. S content 1 wtppm or less as impurities after vacuum melting, Cl content 1 wtppm or less, O content 100 pp
5. The method for producing a high-purity metal according to each of the above 1 to 4, characterized in that it is m or less. S content of 0.5 wtpp, which is an impurity after vacuum melting
m or less, Cl content 0.1 wtppm or less, O content 5
7. The method for producing a high-purity metal according to each of 1 to 4, wherein the content is 0 ppm or less. 7. The method for producing a high-purity metal according to each of 1 to 6 above, wherein the mixed electrodeposited metal is vacuum-melted. The high-purity metal is iron, nickel or cobalt, and the method for producing a high-purity metal according to each of 1 to 7 above is provided.

The present invention also relates to 9. 4N5 (99.995) excluding gas components characterized by S content of 1 wtppm or less, Cl content of 1 wtppm or less, and O content of 100 ppm or less as impurities
wt%) or higher purity metal, a sputtering target made of the same, and a thin film formed by the sputtering target. Impurity S content 0.5 wtppm or less, C
lN content of 0.1 wtppm or less, O content of 50 ppm or less, excluding gas components, 4N5 (9
9.995 wt% or more of high purity metal, a sputtering target made of the same high purity metal, and a thin film formed by the sputtering target. 11. The high-purity metal is iron, nickel, or cobalt, and the high-purity metal according to 9 or 10 above, a sputtering target made of the same high-purity metal, and a thin film formed by the sputtering target. It has a purity of 4N5 (99.995 wt%) or more excluding gas components characterized by having an S content of 1 wtppm or less, a Cl content of 1 wtppm or less, and an O content of 100 ppm or less, which are impurities produced by the above 1 to 8. Provided are a high-purity metal, a sputtering target made of the same high-purity metal, and a thin film formed by the sputtering target.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Using an electrolytic cell 1 as shown in FIG. 1, a target raw material 2 such as massive 3N level iron, cobalt, nickel or the like is used as an anode 5, and the same material is used for a cathode 4. Then, the bath temperature is 10 to 70 ° C., the sulfuric acid electrolyte or the hydrochloric acid electrolyte is used, and the current density is 0.1 to 1.
It is carried out at 0 A / dm ² . In FIG. 1, reference numeral 3 indicates an anode basket. As a result, electrodeposited iron, cobalt, and nickel (deposition) having a purity of 4N5 or more can be obtained on the cathode 4. In the present invention, since such an electrodeposition method is not a requirement of the invention, an outline of a usual production method will be shown. Excluding gas components, 4N5 (99.995wt
Any method can be adopted as appropriate as long as an electrodeposit having a purity of at least%) can be obtained.

According to the present invention, 4N5 (99.995) produced by using an electrodeposited metal produced by using a hydrochloric acid type bath and a sulfuric acid type bath
(wt%) or more of the electrodeposited metal is mixed and vacuum-melted to form an ingot. This removes gas components and 4N
A high-purity metal of 5 (99.995 wt%) or more is manufactured. It is a major feature of the present invention that the electrodeposited metal produced using this hydrochloric acid type bath and the electrodeposited metal produced using the sulfuric acid type bath are mixed and dissolved in vacuum. As described above, in the hydrochloric acid type bath, gas components such as oxygen, chlorine and hydrogen increase, and the yield is slightly low, but conversely, the amount of sulfur is extremely small. On the other hand, the sulfuric acid-based bath is characterized by a high sulfur content, but extremely low gas components such as oxygen, chlorine and hydrogen, and a high yield. Therefore, the above-mentioned mixing cancels out these impurities and improves the yield. Further, the workability does not deteriorate due to the inclusion of sulfur, and the occurrence of cracks during rolling or forging is reduced.

Electron beam melting is preferable as the vacuum melting. As described above, the S content as an impurity after vacuum melting can be 1 wtppm or less, the Cl content can be 1 wtppm or less, and the O content can be 100 ppm or less.
Preferably, the content of S as an impurity is 0.5 wtppm or less, the content of Cl is 0.1 wtppm or less, and the content of O is 50 p.
It is pm or less. Typical high-purity metals applicable in the present invention are iron, nickel, and cobalt, which can be used as a sputtering target material for forming a magnetic thin film described later.

[0012] The above-mentioned electrodeposited metal produced using a hydrochloric acid type bath and 4N5 (99.995 wt) produced using a sulfuric acid type bath
%) Or more of the electrodeposited metal to be dissolved in vacuum, the ratio of the electrodeposited metal produced using a hydrochloric acid bath is 5 to 95 wt.
It is desirable to set it as%. As a result, the S content is 1
wtppm or less, Cl content is 1wtppm or less, O content is 100ppm or less, and further S content is 0.5wt.
It becomes easy to set ppm or less, Cl content of 0.1 wtppm or less, and O content of 50 ppm or less. In the present invention, it is desirable to use a crucible of the same quality as the high-purity metal to be produced, or to use a copper crucible for vacuum melting. This is because, as described above, when a ceramic crucible is used, there is a high possibility that non-metallic inclusions will be mixed with high-purity metal. When vacuum melting using a copper crucible, especially when using an electrodeposit using a hydrochloric acid-based electrolytic solution, the copper content tends to be low, but on the contrary, electrodeposition using a sulfuric acid-based electrolytic solution Since it is higher in the product, the effect of the copper content is offset by being offset.

According to the present invention, according to the above method, the S content as impurities is 1 wtppm or less and the Cl content is 1 wtppm.
Hereinafter, the O content is 100 ppm or less, the S content is 0.5 wtppm or less, the Cl content is 0.1 wtppm or less, and the O content is 50 ppm or less.
It is possible to obtain a high-purity metal having a purity of N5 (99.995 wt%) or higher, particularly high-purity iron, nickel or cobalt, which is suitable as a sputtering target and reduces abnormal discharge during sputtering.
Generation of particles and nodules can be suppressed, and a sputtering target thin film having excellent characteristics can be obtained.

[0014]

Examples and Comparative Examples Next, examples of the present invention will be described. The present embodiment is merely an example, and the present invention is not limited to this example. That is, it includes all aspects or modifications other than the examples within the scope of the technical idea of the present invention.

Example 1 Purity 4N5 (99.995 wt%) electrodeposited cobalt 0.5 produced using a hydrochloric acid type bath
4N5 (99.
995 wt%) 2 kg of electrodeposited cobalt was mixed and subjected to electron beam melting using a copper crucible to obtain an ingot. Electron beam melting is 1 A, 30 kW, vacuum degree 2-5 × 10
It carried out on the conditions of ^-4 mmHg. Oxygen, which is an impurity of the same ingot, obtained by mixing 4N5 electrodeposited cobalt produced using a hydrochloric acid bath and 4N5 electrodeposited cobalt produced using a sulfuric acid bath, and further subjecting this mixture to electron beam melting to form an ingot. The analytical values of sulfur, chlorine, copper and ingot are shown in Table 1. Further, the ingot was cold-rolled to a target shape. A normal high-purity cobalt target was obtained without any cracking due to rolling.

[0016]

[Table 1]

Comparative Example 1 Produced using a hydrochloric acid type bath
Purity 4N5 (99.995wt%) electrodeposited cobalt made of copper
Electron beam melting using crucible to get ingot
It was Electron beam melting was performed in the same manner as in Example 1 with 1A, 30
kW, vacuum degree 2-5 × 10 ^-4Conducted under the condition of mmHg
It was Purity 4N5 electrodeposited cobalt produced using hydrochloric acid bath
Of impurities such as oxygen, sulfur, chlorine, and copper
The analytical values of the ngots are shown in Table 1. Furthermore, this ingo
Cold rolled into a target shape. That conclusion
There was no cracking due to fruit rolling. Same as above results
Are shown in Table 1.

(Comparative Example 2) Production using a sulfuric acid bath
Purity 4N5 (99.995wt%) electrodeposited cobalt made of copper
Electron beam melting using crucible to get ingot
It was Electron beam melting was performed in the same manner as in Example 1 with 1A, 30
kW, vacuum degree 2-5 × 10 ^-4Conducted under the condition of mmHg
It was Purity 4N5 electrodeposited cobalt produced using sulfuric acid bath
Of impurities such as oxygen, sulfur, chlorine, and copper
The analytical values of the ngots are shown in Table 1. Furthermore, this ingo
Cold rolled into a target shape. That conclusion
Cracking occurred due to fruit rolling. The above results are similarly shown in Table 1.
Shown inside.

As shown in Table 1, the electrodeposited cobalt obtained in the hydrochloric acid type bath of Comparative Example 1 contained a large amount of oxygen and chlorine and had a large amount of splash during vacuum melting. In addition, the yield was low at 90% or less. However, the result is that the impurity content of copper is low. On the other hand, in the electrodeposited cobalt obtained in the sulfuric acid system of Comparative Example 2, the oxygen and chlorine contents were small and the splash was small during vacuum melting. However, the result is that the content of impurities in copper is high. The yield up to the ingot stage was as high as 98%. However, cracking occurred during rolling into the target shape. On the other hand, in the ingots of Examples, the contents of oxygen, chlorine, sulfur and copper were all reduced, and as described above, no cracks were generated during processing into the target shape.

In a mixed metal produced using a hydrochloric acid type bath and a sulfuric acid type bath under the same conditions as in Example 1, the amount (wt%) of electrodeposited metal and oxygen content obtained using the hydrochloric acid type bath The result of examining the relationship with the amount is shown in FIG. From this FIG. 2, it is possible to suppress the amount of particles generated to a low level by oxygen 100.
It can be seen that the amount of the electrodeposited metal obtained by using the hydrochloric acid bath is preferably 80 wt% or less in order to set the wtppm or less. In a mixed metal produced using a hydrochloric acid-based bath and a sulfuric acid-based bath under the same conditions as in Example 1, the amount (wt%) of electrodeposited metal obtained by using the hydrochloric acid-based bath and cracking during processing The result of examining the relationship with is shown in FIG. From FIG. 3, in order to prevent cracking, the amount of electrodeposited metal obtained by using a sulfuric acid-based bath should be reduced, that is, the amount of electrodeposited metal obtained by using a hydrochloric acid-based bath should be 15 wt. It can be seen that it is desirable to set it to be at least%.

[0021]

As described above, by mixing the electrodeposited metal produced using the hydrochloric acid type bath and the electrodeposited metal produced using the sulfuric acid type bath, and melting them in vacuum to form an ingot, 4 has a remarkable effect that the yield of high-purity metal having a purity of 4N5 (99.995 wt%) or higher can be improved and that the mixing of gas components and the like can be suppressed. By this, particularly high-purity iron, nickel, cobalt, or the like can be obtained, which is suitable as a sputtering target, can reduce abnormal discharge during sputtering, can suppress the generation of particles or nodules, and has excellent characteristics. It has a remarkable effect that a sputtering thin film such as a magnetic thin film can be obtained.

[Brief description of drawings]

FIG. 1 is a diagram showing an outline of an electrolysis process.

FIG. 2 Amount (w) of electrodeposited metal obtained using a hydrochloric acid-based bath in a mixed metal produced using a hydrochloric acid-based bath and a sulfuric acid-based bath
It is a figure which shows the result of having investigated the relationship between t%) and oxygen content.

FIG. 3 Amount (w) of electrodeposited metal obtained using a hydrochloric acid-based bath in a mixed metal produced using a hydrochloric acid-based bath and a sulfuric acid-based bath
It is a figure which shows the result of having investigated the relationship between the crack generation at the time of processing and t%).

[Explanation of symbols]

1 electrolysis tank 2 lumps of raw material 3 Anode basket 4 cathode 5 anode

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[Procedure amendment]

[Submission date] December 10, 2001 (2001.12.
10)

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0020

[Correction method] Change

[Correction content]

In a mixed metal produced using a hydrochloric acid type bath and a sulfuric acid type bath under the same conditions as in Example 1, the amount (wt%) of electrodeposited metal and oxygen content obtained using the hydrochloric acid type bath The result of examining the relationship with the amount is shown in FIG. From this FIG. 2, it is possible to suppress the amount of particles generated to a low level by oxygen 100.
It can be seen that the amount of the electrodeposited metal obtained by using the hydrochloric acid-based bath is preferably 95 wt% or less in order to achieve the wtppm or less. In a mixed metal produced using a hydrochloric acid-based bath and a sulfuric acid-based bath under the same conditions as in Example 1, the amount (wt%) of electrodeposited metal obtained by using the hydrochloric acid-based bath and cracking during processing The result of examining the relationship with is shown in FIG. Cracks from this Figure 3
In order to make the conditions that can be prevented, it is necessary to reduce the amount of electrodeposited metal obtained using a sulfuric acid-based bath, that is, to set the amount of electrodeposited metal obtained using a hydrochloric acid-based bath to 5 wt% or more. I find it desirable.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) C25C 1/06 C25C 1/06 1/08 1/08 F term (reference) 4K001 AA07 AA10 AA19 BA24 EA02 FA13 GA19 4K029 BA06 BA09 BA12 BC06 CA05 DC03 DC08 4K058 AA12 BA17 BA18 CA04 CA05 CA13

Claims (12)

[Claims] 1. An electrodeposited metal produced using a hydrochloric acid type bath and an electrodeposited metal produced using a sulfuric acid type bath are mixed and vacuum-dissolved to form an ingot.
9.995 wt%) or higher purity metal production method. 2. The method for producing a high purity metal according to claim 1, wherein the ratio of the electrodeposited metal produced using a hydrochloric acid bath is 5 to 95 wt%. 3. The method for producing a high-purity metal according to claim 1, wherein the melting is performed in a vacuum using a copper crucible. 4. The method for producing a high-purity metal according to claim 1 or 2, wherein the melting is performed in a vacuum using a crucible of the same quality as the high-purity metal to be produced. 5. The S content of 1 w as an impurity after vacuum melting
5. Tppm or less, Cl content 1 wtppm or less, O content 100 ppm or less.
The method for producing a high-purity metal according to each item. 6. The content of S which is an impurity after vacuum melting is 0.
5 wtppm or less, Cl content 0.1 wtppm or less,
O content is 50 ppm or less, The manufacturing method of the high purity metal of each of Claims 1-4 characterized by the above-mentioned. 7. The method for producing a high-purity metal according to claim 1, wherein the mixed electrodeposited metal is vacuum-melted. 8. The method for producing a high-purity metal according to each of claims 1 to 7, wherein the high-purity metal is iron, nickel or cobalt. 9. An impurity S content of 1 wtppm or less, Cl content of 1 wtppm or less, and O content of 100 pp.
4N5 excluding gas components characterized by being less than m
A high-purity metal having a purity of (99.995 wt%) or higher, a sputtering target made of the same high-purity metal, and a thin film formed by the sputtering target. 10. The content of S as an impurity is 0.5 wtpp
m or less, Cl content 0.1 wtppm or less, O content 5
4 excluding gas components characterized by being below 0 ppm
A high-purity metal having a purity of N5 (99.995 wt%) or higher, a sputtering target made of the same high-purity metal, and a thin film formed by the sputtering target. 11. The high-purity metal is iron, nickel or cobalt, and the high-purity metal according to claim 9, a sputtering target made of the same high-purity metal, and a thin film formed by the sputtering target. 12. An S content of 1 wtppm or less and an Cl content of 1 wtpp, which are impurities produced according to claims 1 to 8.
m or less, O content 100 ppm or less, formed by a high-purity metal having a purity of 4N5 (99.995 wt%) or more, excluding gas components, a sputtering target made of the same high-purity metal, and the sputtering target. Thin film.