Method for manufacturing high purity manganese and high purity manganese

Abstract

To provide a method for producing high purity manganese capable of sufficiently reducing an oxygen concentration and a boron concentration.SOLUTION: There is provided a method for producing high purity manganese which comprises: a step of preparing a raw material manganese; a step of subjecting the raw material to a heat treatment of maintaining the raw material manganese in a temperature range of 40°C or more and 200°C or less for 1 hour or more and 48 hours or less in an atmosphere in which the partial pressure of oxygen is adjusted to 1.5×104 Pa or more and 8×104 Pa or less to oxidize the surface of the raw material manganese; and a step of heating the raw material manganese whose surface is oxidized to generate manganese vapor, followed by cooling the manganese vapor to obtain high purity manganese.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a method for producing high purity manganese (Mn) and high purity manganese. [Background technology]

[0002] Manganese may be added to copper (Cu), which is a wiring material for semiconductor devices. By adding manganese in this way, it is possible to suppress the diffusion of copper into silicon (Si), which is a semiconductor material. As such manganese, high purity manganese may be adopted. As a method for producing high purity manganese, a method of performing electrolytic treatment, a method of distilling raw manganese, or a method of sublimating manganese have been proposed (for example, see Patent Documents 1 to 4). Patent Document 2 proposes a method of obtaining high purity manganese with a reduced oxygen (O) concentration by combining a method of performing electrolytic treatment and a method of sublimation. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 11-152528 [Patent Document 2] JP 2002-285373 A [Patent Document 3] International Publication No. 2013 / 105291 [Patent Document 4] International Publication No. 2015 / 060018 Summary of the Invention [Problem to be solved by the invention]

[0004] In the above-mentioned high purity manganese, there are cases where it is required to reduce not only the oxygen concentration but also the boron (B) concentration. Therefore, one of the objects is to provide a method for producing high purity manganese, which can sufficiently reduce the oxygen concentration and the boron concentration, and high purity manganese. [Means for solving the problem]

[0005] The method for producing high purity manganese according to the present disclosure includes the steps of preparing raw manganese and oxidizing the manganese under an oxygen partial pressure of 1.5×10 4 Pa or more 8×10 4 The method includes a step of oxidizing the surface of the raw manganese by carrying out a heat treatment in which the raw manganese is held at a temperature in the range of 40°C to 200°C for 1 hour to 48 hours in an atmosphere adjusted to a pressure of 100 Pa or less, and a step of heating the raw manganese with the oxidized surface to generate manganese vapor, and then cooling the manganese vapor to obtain high-purity manganese.

[0006] High purity manganese according to the present disclosure has an oxygen content of 3 ppm by mass or less and a boron content of 3 ppm by mass or less. Effect of the Invention

[0007] According to the present disclosure, it is possible to provide high-purity manganese in which the oxygen concentration and the boron concentration are sufficiently reduced. The high-purity manganese of the present disclosure can suppress the deterioration of the characteristics of semiconductor devices caused by oxygen and boron. [Brief description of the drawings]

[0008] [Figure 1] 1 is a flowchart showing an example of a method for producing high purity manganese in the first embodiment. [Diagram 2] 11 is a flowchart showing an example of a method for producing high purity manganese in the second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] [Description of the embodiments of the present disclosure] First, the embodiments of the present disclosure will be listed and described. The method for producing high purity manganese of the present disclosure includes a step of preparing raw manganese, and a step of reducing the partial pressure of oxygen to 1.5×10 4 Pa or more 8×10 4The method includes a step of oxidizing the surface of the raw manganese by carrying out a heat treatment in which the raw manganese is held at a temperature in the range of 40°C to 200°C for 1 hour to 48 hours in an atmosphere adjusted to a pressure of 100 Pa or less, and a step of heating the raw manganese with the oxidized surface to generate manganese vapor, and then cooling the manganese vapor to obtain high-purity manganese.

[0010] In the method for producing high purity manganese disclosed herein, the partial pressure of oxygen is 1.5×10 4 Pa or more 8×10 4 In an atmosphere adjusted to a pressure of 100 Pa or less, a heat treatment is performed in which the raw manganese is held at a temperature range of 40° C. to 200° C. for 1 hour to 48 hours. By performing such a heat treatment, the surface of the raw manganese is oxidized to form a manganese oxide film. When the raw manganese is heated to generate manganese vapor in a state in which a manganese oxide film is not formed, some of the boron contained as an impurity in the raw manganese is mixed into the manganese vapor as an impurity. In contrast, by forming an oxide film on the surface of the raw manganese by the heat treatment, the boron in the raw manganese is captured by the oxide film. As a result, the boron mixed into the manganese vapor can be reduced. As a result, high-purity manganese in which not only the oxygen concentration but also the boron concentration is sufficiently reduced can be obtained. In this way, according to the method for producing high-purity manganese disclosed herein, high-purity manganese in which the oxygen concentration and the boron concentration are sufficiently reduced can be obtained.

[0011] In the method for producing high purity manganese, the raw manganese may have an oxygen concentration of 570 mass ppm or less. By using such raw manganese, it is easy to obtain high purity manganese with a sufficiently reduced oxygen concentration.

[0012] In the method for producing high purity manganese, the step of preparing raw manganese may include the steps of preparing a manganese chloride aqueous solution by dissolving at least one of raw materials including manganese, manganese chloride and manganese dioxide in hydrochloric acid, and purifying the manganese chloride aqueous solution by contacting the manganese chloride aqueous solution with a chelating resin, and performing an electrolytic treatment to electrolytically deposit manganese using the purified manganese chloride aqueous solution as an electrolyte to obtain electrolytically won manganese as raw manganese. The electrolytically won manganese obtained by performing the electrolytic treatment is suitable as raw manganese.

[0013] In the above-mentioned method for producing high purity manganese, in the step of obtaining high purity manganese, the raw manganese may be heated to sublimate it to generate manganese vapor, and then the manganese vapor may be cooled to obtain high purity manganese. By generating manganese vapor by sublimating the raw manganese as described above, the oxygen concentration and boron concentration in the high purity manganese can be further reduced.

[0014] In the step of obtaining high purity manganese in the method for producing high purity manganese, the raw manganese may be evaporated by heating to generate manganese vapor, and then the manganese vapor may be cooled to obtain high purity manganese. By generating manganese vapor by evaporating the raw manganese as described above, high purity manganese can be obtained at a lower cost.

[0015] In the high purity manganese of the present disclosure, the oxygen content is 3 ppm by mass or less, and the boron content is 3 ppm by mass or less. By setting the oxygen and boron contents in the above ranges, it is possible to suppress the deterioration of the characteristics of the semiconductor device caused by oxygen and boron.

[0016] [Details of the embodiment of the present disclosure] Next, embodiments of the high purity manganese and the method for producing high purity manganese according to the present disclosure will be described with reference to the drawings. In the following drawings, the same or corresponding parts are designated by the same reference numerals, and the description thereof will not be repeated.

[0017] (Embodiment 1) First, the high purity manganese in one embodiment of the present application will be described. In the high purity manganese of this embodiment, the oxygen content is 3 ppm by mass or less, and the boron content is 3 ppm by mass or less. In this way, by setting the oxygen and boron contents within the above ranges, it is possible to suppress the deterioration of the characteristics of the semiconductor device caused by oxygen and boron. For example, when the high purity manganese of the present disclosure is used for the wiring material, the oxygen content is sufficiently reduced, so that the deterioration of the conductivity in the copper wiring can be suppressed. In addition, for example, when the high purity manganese of the present disclosure is used as a target material for sputtering, the oxygen content is sufficiently reduced, so that the generation of particles can be reduced and the deterioration of the reliability of the device can be suppressed. According to the study by the present inventors, since the boron concentration is sufficiently reduced in the high purity manganese of the present disclosure, for example, the diffusion of boron into the active layer of the semiconductor device can be reduced, and the deterioration of the life of the semiconductor device can be suppressed. The oxygen content of the high purity manganese is preferably 1 ppm by mass or less. The boron content of the high purity manganese is preferably 2 ppm by mass or less. The oxygen content can be measured, for example, by an IGA (Instrumental Gas Analysis) method. More specifically, it can be measured by an infrared absorption method. The boron content can be measured, for example, by a GDMS (Glow Discharge Mass Spectrometry) method.

[0018] Next, a procedure for producing high purity manganese according to the present embodiment will be described. With reference to FIG. 1, in the method for producing high purity manganese according to the first embodiment, first, a step (S10) of preparing raw manganese is carried out. In the present embodiment, lump raw manganese is prepared. The purity of the raw manganese according to the present embodiment is, for example, 99.9% by mass (3N) or more. In the present disclosure, the purity refers to the ratio (mass%) of the total mass of metal impurities in a sample measured by the GDMS method to the mass of the entire sample, which is subtracted from the mass of the entire sample. In the present embodiment, the oxygen concentration of the raw manganese is 570 ppm by mass or less. The oxygen concentration of the raw manganese is preferably 535 ppm by mass or less, and more preferably 500 ppm by mass or less.

[0019] Next, referring to FIG. 1, in step (S20), a step of oxidizing the surface of the raw manganese is carried out. More specifically, when the partial pressure of oxygen is 1.5×10 4 Pa or more 8×10 4 In a first heat treatment, the raw manganese is kept at a temperature range of 40°C to 200°C for 1 hour to 48 hours in an atmosphere adjusted to a pressure of 1 Pa or less. Prior to carrying out the heat treatment, the raw manganese may be acid-washed with nitric acid or the like to remove foreign matter adhering to the surface of the raw manganese. By carrying out the first heat treatment, the surface of the raw manganese is oxidized to form a manganese oxide film.

[0020] The partial pressure of oxygen in the first heat treatment in step (S20) is 1.5×10 4 If the partial pressure of oxygen in the first heat treatment is less than 8×10 Pa, the surface of the raw manganese is not sufficiently oxidized, and it is difficult to form a sufficient oxide film of manganese. 4 If the oxygen partial pressure exceeds 1.5×10 Pa, manganese may be excessively oxidized, which may affect the subsequent refining process. 4 Pa or more 8×10 4 The partial pressure of oxygen is preferably 2×10 Pa or less. 4 Pa or more 6×10 4Pa or less. If the treatment temperature in the first heat treatment is less than 40°C, the surface of the raw manganese is not sufficiently oxidized, and it is difficult to form a sufficient oxide film of manganese. If the treatment temperature in the first heat treatment is higher than 200°C, manganese may be excessively oxidized, which may affect the subsequent refining treatment. Therefore, the treatment temperature in the first heat treatment is preferably 40°C or more and 200°C or less. The treatment temperature is more preferably 50°C or more and 150°C or less. From the viewpoint of forming a sufficient oxide film, the treatment time in the first heat treatment is preferably 1 hour or more and 48 hours or less. The treatment time is more preferably 3 hours or more and 36 hours or less.

[0021] Next, referring to Fig. 1, a step of obtaining high purity manganese is carried out as step (S30). More specifically, manganese vapor is generated by heating raw manganese with an oxidized surface, and then the manganese vapor is cooled to obtain high purity manganese. In this embodiment, in the step of obtaining high purity manganese, the raw manganese is heated to sublimate it to generate manganese vapor, and then the manganese vapor is cooled to obtain high purity manganese (hereinafter also referred to as the sublimation method). The refining apparatus used in the sublimation method includes a crucible in which the raw manganese is placed, a heating section for heating the raw manganese, and a cooling section for cooling the manganese vapor.

[0022] An example of the sublimation method in this embodiment will be specifically described. First, raw manganese with an oxidized surface is placed in a crucible in a refining device. The inside of the crucible is evacuated to create a vacuum in the internal space of the crucible. In addition to evacuating the inside of the crucible, preheating may be performed in which the raw manganese is heated to about 500°C and held for about 1 hour. By carrying out preheating in this manner, it is possible to reduce volatile impurities contained in the raw manganese. Next, a sublimation process is carried out in which the raw manganese is held at a temperature range of 1000°C to 1200°C for 20 hours to 50 hours while maintaining the inside of the crucible in a vacuum state. The manganese vapor sublimated from the raw manganese is condensed by being cooled in a cooling section in the refining device, and solid high-purity manganese is obtained. If the processing temperature in the sublimation process is less than 1000°C, the sublimation speed becomes slow, and it may take a long time to obtain high-purity manganese. If the treatment temperature exceeds 1200°C, the raw manganese may partially melt depending on the loading condition of the raw material. If liquid manganese produced by such melting adheres to the inner wall of the refining device, the inner wall of the refining device may be damaged, and the resulting impurities may sublimate and contaminate the high purity manganese. Therefore, the treatment temperature is preferably 1000°C or higher and 1200°C or lower. The degree of vacuum when carrying out the sublimation treatment is 10 -5 The pressure is preferably from 0.1 Pa to 1 Pa. The sublimation treatment is preferably carried out until the mass of the residue of the raw manganese is from 20% by mass to 40% by mass of the initial mass of the raw manganese.

[0023] According to the sublimation method, impurities with a higher vapor pressure than manganese are condensed in a region of the cooling section of the refining device that is lower in temperature than the region where manganese is condensed. Meanwhile, impurities with a lower vapor pressure than manganese remain as residues of the raw manganese. In this way, high-purity manganese with improved purity can be obtained.

[0024] Here, by carrying out the first heat treatment in the method for producing high purity manganese in this embodiment, the surface of the raw manganese is oxidized to form a manganese oxide film. When the raw manganese is heated to generate manganese vapor in a state where a manganese oxide film is not formed, some of the boron contained as an impurity in the raw manganese is mixed into the manganese vapor as an impurity. By forming an oxide film on the surface of the raw manganese by the above heat treatment, the boron in the raw manganese is captured by the oxide film. As a result, the amount of boron mixed into the manganese vapor can be reduced.

[0025] In the process of obtaining high purity manganese in the above embodiment, the raw manganese is heated to sublimate it to generate manganese vapor, and then the manganese vapor is cooled to obtain high purity manganese. Oxygen contained as an impurity in the raw manganese has a large affinity with manganese, and therefore forms an oxide of manganese, which remains in the residue as it is, and can be separated from the manganese vapor. As a result, it is possible to suppress the oxygen contained as an impurity in the raw manganese from being mixed into the manganese vapor as an impurity. By generating manganese vapor by sublimating the raw manganese, high purity manganese with sufficiently reduced oxygen and boron concentrations can be obtained.

[0026] Next, a description will be given of a modified example of the method for producing high purity manganese according to the embodiment 1. In the step (S30) of obtaining high purity manganese, instead of heating the raw manganese to sublimate it and generate manganese vapor, the raw manganese may be heated to evaporate it and generate manganese vapor (hereinafter, also referred to as a distillation purification method).

[0027] An example of the above distillation purification method will be specifically described. As in the sublimation method, raw manganese with an oxidized surface is placed in a crucible in a purification device. The inside of the crucible is evacuated to create a vacuum in the internal space of the crucible. Preheating may be performed as in the sublimation method. Next, an evaporation process is performed in which the raw manganese is kept at a temperature range of 1250°C to 1300°C while maintaining the inside of the crucible in a vacuum state. By performing the evaporation process, the raw manganese melts to generate liquid manganese, and the liquid manganese further evaporates to generate manganese vapor. The evaporated manganese vapor is cooled in the cooling section of the purification device and condenses, and solid high-purity manganese is obtained. If the processing temperature in the evaporation process is less than 1250°C, manganese may not be sufficiently melted. If the processing temperature in the evaporation process is more than 1300°C, the inner wall of the purification device and the manganese vapor may react, and impurities may be introduced into the manganese vapor. Therefore, the processing temperature in the evaporation process is preferably 1250° C. or higher and 1300° C. or lower. -3 It is preferable that the pressure is from 10 Pa to 10 Pa. In the distillation purification method, the evaporation process can be carried out under a higher pressure than in the sublimation process. If the degree of vacuum during the evaporation process exceeds 10 Pa, the evaporation rate will be slow, and it may take a long time to obtain high-purity manganese. It is preferable to carry out the evaporation process until the mass of the residue of the raw manganese is from 10 mass % to 40 mass % of the initial mass of the raw manganese.

[0028] It is desirable to protect areas of the refining apparatus that may come into contact with liquid manganese with a material that is difficult to react with manganese, such as alumina, so that even if liquid manganese adheres to the inner wall of the refining apparatus, it is possible to reduce the introduction of impurities into the high purity manganese.

[0029] According to the above distillation purification method, impurities with a higher vapor pressure than manganese are condensed in a region of the cooling section of the purification device that is lower in temperature than the region where manganese is condensed. Furthermore, impurities with a lower vapor pressure than manganese remain as residues of the raw manganese. In this way, high-purity manganese with improved purity can be obtained. In the above distillation purification method, when liquid manganese is produced, low-density oxides of manganese are placed on the surface of the liquid. Boron contained as an impurity in the raw manganese is captured by the oxides. As a result, the amount of boron mixed into the manganese vapor can be reduced.

[0030] In the process of obtaining high purity manganese in the above embodiment, the raw manganese is heated to evaporate it to generate manganese vapor, and then the manganese vapor is cooled to obtain high purity manganese. Such a distillation purification method can obtain high purity manganese in a shorter time than the sublimation method. Therefore, high purity manganese can be obtained at a lower cost.

[0031] (Embodiment 2) Next, a second embodiment of the method for producing high purity manganese according to the present invention will be described. The method for producing high purity manganese in the second embodiment basically has the same steps as the method for producing high purity manganese in the first embodiment, and produces the same effects. However, the second embodiment differs from the first embodiment in that, instead of step (S10), a step (S40) of preparing a raw material, a step (S50) of purifying an aqueous manganese chloride solution, and a step (S60) of obtaining electrolytically won manganese are carried out. The following mainly describes the differences from the first embodiment.

[0032] With reference to FIG. 2, in the method for producing high purity manganese in the second embodiment, first, as step (S40), a step of preparing a raw material is carried out. In this embodiment, a raw material containing at least one of manganese, manganese chloride, and manganese dioxide is prepared. Next, as step (S50), a step of purifying the manganese chloride aqueous solution is carried out. An example of the step of purifying the manganese chloride aqueous solution will be specifically described below. First, the raw material is dissolved in hydrochloric acid to prepare a manganese chloride aqueous solution. The manganese concentration is, for example, 10 g / L or more and 80 g / L or less. Next, an ammonia aqueous solution is added to the manganese chloride aqueous solution to prepare a manganese chloride aqueous solution having, for example, a pH of 2 or more and 7 or less. Next, a step of contacting the manganese chloride aqueous solution with a chelating resin is carried out. More specifically, the manganese chloride aqueous solution is passed through a glass or vinyl chloride column packed with a chelating resin. The chelating resin in this embodiment is an iminodiacetic acid type chelating resin. The flow rate of the manganese chloride aqueous solution through the column is, for example, 1 SV (Space Velocity) or more and 10 SV or less. Metal impurities of iron (Fe), aluminum (Al) and chromium (Cr) contained in the raw material are adsorbed by the iminodiacetic acid type chelating resin. Therefore, the content of the metal impurities contained in the raw material can be reduced. Such a process of purifying the manganese chloride aqueous solution may be carried out repeatedly.

[0033] If the pH of the manganese chloride aqueous solution is less than 2, the adsorption rate of the metal impurities of iron, aluminum, and chromium to the iminodiacetic acid type chelating resin may decrease. If the pH of the manganese chloride aqueous solution exceeds 7, manganese hydroxide may precipitate. For this reason, the pH of the manganese chloride aqueous solution is preferably 2 or more and 7 or less. If the flow rate of the manganese chloride aqueous solution through the column is less than 1 SV, it takes a long time to obtain a purified manganese chloride aqueous solution. If the flow rate of the manganese chloride aqueous solution exceeds 10 SV, the metal impurities may be difficult to adsorb to the chelating resin. Therefore, the flow rate of the manganese chloride aqueous solution is preferably 1 SV or more and 10 SV or less.

[0034] Next, in step (S60), a step of obtaining electrolytically won manganese is carried out. In this embodiment, an electrolytic treatment is carried out to electrodeposit manganese using the refined aqueous manganese chloride solution as an electrolyte. An example of the electrolytic treatment is specifically described below. First, an electrolyte is prepared by adding ammonium chloride as a buffer to the refined aqueous manganese chloride solution. The concentration of manganese in the electrolyte is, for example, 5 g / L to 60 g / L. The concentration of ammonium chloride in the electrolyte is, for example, 80 g / L to 150 g / L. Next, an electrolytic treatment is carried out using the electrolyte. The current density in the electrolytic treatment is, for example, 50 mA / cm. 2 More than 120mA / cm 2 In the electrolysis, an appropriate amount of aqueous ammonia is added to the electrolytic solution to maintain the pH at 4 or more and 7 or less. In this way, smooth plate-shaped electrolytically won manganese is formed. When the pH of the electrolytic solution in the electrolysis is less than 4, the electrolytically won manganese is easily re-eluted in the electrolytic solution. When the pH is more than 7, manganese hydroxide is easily precipitated in the electrolytic solution. Therefore, the pH of the electrolytic solution in the electrolysis is preferably 4 or more and 7 or less. By carrying out the electrolysis as described above, the impurities of alkali metals and alkaline earth metals contained in the raw material can be reduced.

[0035] The electrolytically won manganese obtained by the above steps is used as raw manganese, and steps (S20) and (S30) are carried out in the same manner as in embodiment 1. The method for producing high purity manganese in embodiment 2 can also produce high purity manganese with sufficiently reduced oxygen and boron concentrations, as in embodiment 1.

[0036] In the above embodiment, the case where a raw material containing at least one of manganese, manganese chloride, and manganese dioxide is used in step (S40) has been described, but the present invention is not limited thereto, and raw manganese having a purity of 99.9 mass% (3N) or more may be used. Raw manganese having an oxygen concentration of 570 mass ppm or less may be used. The oxygen concentration of the raw manganese is preferably 535 mass ppm or less, and more preferably 500 mass ppm or less. By using such raw manganese, the oxygen concentration and boron concentration in the high purity manganese can be further reduced. EXAMPLES

[0037] A sample was prepared by the method for producing high purity manganese according to the present disclosure, and an experiment was carried out to confirm the effect of reducing the oxygen concentration and the boron concentration. The procedure of the experiment was as follows.

[0038] (Examples 1 to 3) Electrolytic manganese with an oxygen concentration of 490 mass ppm and a boron concentration of 20 mass ppm was prepared as the manganese raw material. The manganese raw material was pretreated by washing with water and alcohol. Next, the manganese was subjected to a pretreatment process in which the partial pressure of oxygen was 8×10 4 The manganese raw material was subjected to a first heat treatment in which it was held at a temperature of 50° C. for 15 hours in an atmosphere adjusted to 10 Pa. 10 kg of the manganese raw material thus subjected to the first heat treatment was placed in a crucible and preheated. -4 ~10 -3 The first heat treatment was carried out under the conditions of heating to 500°C in the range of 3.5×10 Pa and holding for 1 hour. After preheating, the raw manganese that had been subjected to the first heat treatment was heated to about 1080°C and held for 30 hours to carry out a sublimation treatment (sublimation method). Manganese vapor generated by carrying out the sublimation treatment was cooled in a cooling section made of high-purity alumina, and a sample (Example 1) weighing about 6 kg was produced. The partial pressure of oxygen in the first heat treatment was set to 3.5×10 4 A sample (Example 2) was prepared in the same manner as in Example 1, except that the partial pressure of oxygen in the first heat treatment was 2×10 Pa, the treatment temperature was 150° C., and the treatment time was 3 hours. 4A sample (Example 3) was prepared in the same manner as in Example 1, except that the treatment pressure was changed to 100 Pa, the treatment temperature was 45° C., and the treatment time was 36 hours.

[0039] (Examples 4 to 6) Electrolytic manganese with an oxygen concentration of 490 ppm by mass and a boron concentration of 20 ppm by mass was prepared as raw manganese. After washing the raw manganese with pure water, an aqueous manganese chloride solution was prepared by dissolving it in hydrochloric acid. Ammonium chloride and pure water were added to the aqueous manganese chloride solution to prepare an aqueous manganese chloride and ammonium chloride solution. The manganese concentration in the aqueous manganese chloride and ammonium chloride solution was 50 g / L, and the ammonium chloride concentration was 100 g / L. An appropriate amount of aqueous ammonia was added to the aqueous manganese chloride and ammonium chloride solution so that the pH was 6. The aqueous manganese chloride and ammonium chloride solution with the adjusted pH was passed through a column packed with an iminodiacetic acid type chelating resin (manufactured by Unitika, product name "UR-30S") to purify the aqueous manganese chloride and ammonium chloride solution. The aqueous manganese chloride and ammonium chloride solution was passed through the column at a rate of 5 SV. A column packed with 7 L of iminodiacetic acid type chelating resin was used.

[0040] Electrolysis was carried out using 30 L of an aqueous solution of purified manganese chloride and ammonium chloride as the electrolyte. The current density in the electrolysis was 100 mA / cm 2 In the electrolysis, an appropriate amount of ammonia water solution was added to the electrolyte to maintain the pH at about 6. In this way, smooth plate-shaped electrowinning manganese was formed. For 10 kg of electrowinning manganese thus formed, the partial pressure of oxygen was 2.5×10 4 The first heat treatment was carried out by heating to 200°C and holding for 1 hour in an atmosphere adjusted to 10 Pa. The electrolytic manganese thus subjected to the first heat treatment was placed in a crucible and preheated. The preheating was carried out in a vacuum of 10 -4 ~10 -3The first heat treatment was carried out under the conditions of heating to 500°C in the range of 3×10 Pa and holding for 1 hour. After preheating, the electrolytically won manganese that had been subjected to the first heat treatment was heated to about 1270°C and held for 6 hours for evaporation treatment (distillation purification method). Manganese vapor generated by carrying out the evaporation treatment was cooled in a cooling section made of high purity alumina, and a sample weighing about 7 kg (Example 4) was produced. The partial pressure of oxygen in the first heat treatment was 3×10 4 A sample (Example 5) was prepared in the same manner as in Example 4, except that the partial pressure of oxygen in the first heat treatment was 4.5×10 Pa, the treatment temperature was 60° C., and the treatment time was 20 hours. 4 A sample (Example 6) was prepared in the same manner as in Example 4, except that the pressure was 200 Pa, the treatment temperature was 80° C., and the treatment time was 12 hours.

[0041] (Examples 7 to 9) Electrolytic manganese produced by electrolytic treatment in the same manner as in Example 4 was electrolytically extracted 10 kg of manganese, and the partial pressure of oxygen was 4 × 10 4 The first heat treatment was carried out by heating to 40°C and holding for 48 hours in an atmosphere adjusted to 10 Pa. The electrolytic manganese thus subjected to the first heat treatment was used to carry out a sublimation treatment similar to that of Example 1 to produce a sample (Example 7). The partial pressure of oxygen in the first heat treatment was adjusted to 6×10 4 A sample (Example 8) was prepared in the same manner as in Example 7, except that the partial pressure of oxygen in the first heat treatment was 1.5×10 Pa, the treatment temperature was 100° C., and the treatment time was 6 hours. 4 A sample (Example 9) was prepared in the same manner as in Example 7, except that the treatment pressure was 1 Pa, the treatment temperature was 120° C., and the treatment time was 10 hours.

[0042] (Comparative Examples 1 and 2) The partial pressure of oxygen in the first heat treatment is 9×10 4 A sample (Comparative Example 1) was prepared in the same manner as in Example 1, except that the partial pressure of oxygen in the first heat treatment was 3.5×10 Pa, the treatment temperature was 50° C., and the treatment time was 15 hours. 4 A sample (Comparative Example 2) was prepared in the same manner as in Example 1, except that the treatment temperature was 150° C. and the treatment time was 0.5 hours.

[0043] (Comparative Examples 3 and 4) The partial pressure of oxygen in the first heat treatment is 2.5×10 4 A sample (Comparative Example 3) was prepared in the same manner as in Example 4, except that the partial pressure of oxygen in the first heat treatment was 3×10 Pa, the treatment temperature was 250° C., and the treatment time was 1 hour. 4 A sample (Comparative Example 4) was prepared in the same manner as in Example 4, except that the treatment temperature was 35° C. and the treatment time was 20 hours.

[0044] (Comparative Examples 5 and 6) The partial pressure of oxygen in the first heat treatment is 4×10 4 A sample (Comparative Example 5) was prepared in the same manner as in Example 7, except that the partial pressure of oxygen in the first heat treatment was 1×10 Pa, the treatment temperature was 40° C., and the treatment time was 60 hours. 4 A sample (Comparative Example 6) was prepared in the same manner as in Example 7, except that the treatment temperature was 100° C. and the treatment time was 6 hours.

[0045] (Oxygen and boron concentration measurements) The oxygen concentration and boron concentration were measured for the samples of Examples 1 to 9 and Comparative Examples 1 to 6. The oxygen concentration was measured by the infrared absorption method. The above measurement device used "ONH836" manufactured by LECO. The boron concentration was measured by the GDMS method. The above measurement device used "Element GD" manufactured by Thermo Scientific. Table 1 shows the measurement results of the oxygen concentration and boron concentration of the samples of Examples 1 to 9 and Comparative Examples 1 to 6. In the purification method of Table 1, I indicates the sublimation method. II indicates the distillation purification method. III indicates the electrolytic treatment. "I,III" indicates that the electrolytic treatment and the sublimation method are carried out as the purification method. Similarly, "II,III" indicates that the electrolytic treatment and the distillation purification method are carried out as the purification method. Table 2 shows the degree of possibility that the characteristics of the semiconductor device deteriorate in the samples of Examples 1 to 9 and Comparative Examples 1 to 6. In Table 2, A indicates that the possibility of deterioration of the characteristics of the semiconductor device is extremely low. B indicates that the possibility of deterioration of the characteristics of the semiconductor device is low. C indicates that the possibility of deterioration of the characteristics of the semiconductor device is high. D indicates that the possibility of deterioration of the characteristics of the semiconductor device is extremely high. The above A to D have a relationship of A < B < C < D with respect to the degree of possibility that the characteristics of the semiconductor device deteriorate.

[0046]

Table 1

[0047]

Table 2

[0048] Referring to Table 1, the partial pressure of oxygen in the first heat treatment is 1.5×10 4 Pa or more and 8×10 4In samples (Examples 1 to 9) in which the first heat treatment is performed at a pressure of 0.1 Pa or less, at a treatment temperature of 40° C. to 200° C. and for a treatment time of 1 hour to 48 hours, the oxygen concentration and boron concentration can be reduced compared to samples (Comparative Examples 1 to 6) in which the first heat treatment is performed outside the above ranges. In samples (Examples 1 to 9) in which the first heat treatment is performed within the above ranges, the oxygen concentration can be reduced to 3 ppm by mass or less and the boron concentration can be reduced to 3 ppm by mass or less. Therefore, it is confirmed that the oxygen concentration and boron concentration are sufficiently reduced in the samples of Examples 1 to 9.

[0049] In the samples (Examples 7 to 9) subjected to electrolysis and sublimation (sublimation method), the oxygen concentration and boron concentration can be further reduced compared to the samples (Examples 1 to 3) subjected to only sublimation without electrolysis. Therefore, it is preferable to use electrolytically obtained manganese as raw manganese. In the samples (Examples 7 to 9) subjected to electrolysis and sublimation, the oxygen concentration and boron concentration can be further reduced compared to the samples (Examples 4 to 6) subjected to electrolysis and evaporation (distillation purification). Therefore, it is more preferable to perform electrolysis and sublimation as a method for producing high purity manganese.

[0050] Referring to Table 2, it is believed that the samples of Examples 1 to 9 are less susceptible to degradation of the semiconductor device characteristics than the samples of Comparative Examples 1 to 6. In particular, it is believed that the samples (Examples 7 to 9) subjected to electrolysis and sublimation are particularly less susceptible to degradation of the semiconductor device characteristics.

[0051] From the above experimental results, it is confirmed that the method for producing high-purity manganese disclosed herein can produce high-purity manganese in which not only the oxygen concentration but also the boron concentration is sufficiently reduced.

[0052] It should be understood that the embodiments disclosed herein are illustrative in all respects and are not limiting in any respect. The scope of the present invention is defined by the claims, not the above description, and is intended to include all modifications within the meaning and scope of the claims. [Industrial Applicability]

[0053] The method for producing high purity manganese according to the present disclosure is particularly advantageously applied in cases where it is required to reduce the oxygen concentration and boron concentration of high purity manganese.

Claims

Step of preparing raw material manganese with a purity of 99.9 mass% or more, or raw material manganese with an oxygen concentration of 570 mass ppm or less and a boron concentration of 20 mass ppm or less, Step of oxidizing the surface of the raw material manganese, Step of generating manganese vapor by heating the raw material manganese with an oxidized surface, and then cooling the manganese vapor to obtain high-purity manganese, Method for producing high-purity manganese, which obtains high-purity manganese with an oxygen content of 3 mass ppm or less and a boron content of 3 mass ppm or less. The method for producing high-purity manganese according to claim 1, wherein the step of oxidizing the surface of the raw material manganese is performed at a predetermined oxygen partial pressure, temperature, and time. The method for producing high-purity manganese according to claim 2, wherein the predetermined oxygen partial pressure, temperature, and time are respectively 1.5×10 4 Pa or more and 8×10 4 Pa or less, 40°C or more and 200°C or less, and 1 hour or more and 48 hours or less.

4. In the step of obtaining the high-purity manganese, the raw material manganese is sublimated by heating to generate the manganese vapor, and then the manganese vapor is cooled to obtain the high-purity manganese. The method for producing high-purity manganese according to any one of claims 1 to 3.

5. In the step of obtaining the high-purity manganese, the raw material manganese is evaporated by heating to generate the manganese vapor, and then the manganese vapor is cooled to obtain the high-purity manganese. The method for producing high-purity manganese according to any one of claims 1 to 3.

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