Classifications

• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
  • C01G39/00—Compounds of molybdenum
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
  • C01G39/00—Compounds of molybdenum
  • C01G39/02—Oxides; Hydroxides

Definitions

• the present invention relates to a method for producing molybdenum trioxide with a reduced Sb content.
• Molybdenum (Mo) has low electrical resistivity and is chemically stable, making it a promising material for use in electronic devices, such as contact plugs and wiring in large-scale integrated circuits (LSIs), word lines in semiconductor memories, and diffusion barrier layers under wiring.
• LSIs large-scale integrated circuits
• a layer made of molybdenum or a compound thereof is formed by chemical vapor deposition (CVD), in which a compound containing molybdenum is evaporated as a precursor, and then decomposed and reacted on the substrate surface to form a thin film.
• CVD chemical vapor deposition
• molybdenum oxychloride which is a compound of chlorine and molybdenum oxide
• Molybdenum oxychloride is generally synthesized by chlorinating molybdenum oxide with chlorine gas.
• High-purity molybdenum oxide is used as a raw material.
• Patent documents 1 to 4 disclose methods for producing high-purity molybdenum or molybdenum oxide.
• Molybdenum oxychloride used as a precursor for CVD and ALD, is synthesized by chlorinating molybdenum oxides such as molybdenum trioxide with chlorine gas.
• molybdenum oxychloride the raw material, molybdenum oxide, must be purified.
• the molybdenum trioxide raw material was dissolved in aqueous ammonia, filtered to remove solid impurities, and then nitric acid was added to precipitate ammonium molybdate, which was then roasted to produce molybdenum trioxide.
• the molybdenum trioxide obtained by this method has the problem that it is difficult to reduce the antimony (Sb) impurity, or the reduction effect is low, and repeated purification is required to reduce the Sb content, which increases purification costs.
• the objective of this disclosure is to provide a method for producing molybdenum trioxide that can reduce the Sb content.
• the gist of the present disclosure includes the following.
• a method for producing molybdenum trioxide comprising the steps of: mixing a raw material consisting of a molybdenum compound or a hydrate thereof with chlorine, hydrogen chloride, or a chloride; and heating the resulting mixture at 70°C or higher.
• a method for producing molybdenum trioxide comprising the steps of: mixing a raw material consisting of molybdenum trioxide, ammonium molybdate, or a hydrate thereof with ammonium chloride; and heating the resulting mixture at 180°C or higher.
• a method for producing molybdenum trioxide comprising the steps of: mixing a raw material consisting of molybdenum trioxide, ammonium molybdate, or a hydrate thereof with an aqueous solution containing ammonium chloride; and heating the resulting mixture at 180°C or higher.
• a method for producing molybdenum trioxide comprising the steps of mixing a raw material consisting of molybdenum trioxide, ammonium molybdate, or a hydrate thereof with aqueous ammonia, then mixing with hydrochloric acid, and heating the resulting mixture at 180°C or higher.
• a raw material consisting of molybdenum trioxide, ammonium molybdate, or a hydrate thereof; 1.
• a method for producing molybdenum trioxide comprising the steps of: mixing hydrochloric acid, then mixing ammonium water, and heating the resulting mixture at 180°C or higher.
• the method for producing molybdenum trioxide according to any one of [1] to [5] above, wherein the Sb content in the produced molybdenum trioxide is 1/3 or less, in weight ratio, of the Sb content in the raw material.
• [7] The method for producing molybdenum trioxide according to any one of the above [1] to [6], wherein the S content in the produced molybdenum trioxide is 1/2 or less, in weight ratio, of the S content contained in the raw material.
• [8] The method for producing molybdenum trioxide according to any one of [1] to [7], wherein the Sb content in the produced molybdenum trioxide is 0.2 ppm by weight or less.
• [9] The method for producing molybdenum trioxide according to any one of [1] to [8], wherein the S content in the produced molybdenum trioxide is 0.1 ppm by weight or less.
• the present invention provides a method for producing molybdenum trioxide with a reduced Sb content.
• FIG. 1 is a diagram showing the results of a thermodynamic equilibrium calculation (vertical axis is log 10 (gram)) when a system consisting of a mixture of antimony trioxide (Sb 2 O 3 ) and hydrogen chloride (HCl) is heated from 0° C. to 500° C.
• FIG. 1 is a diagram showing the results of thermodynamic equilibrium calculations (vertical axis is log 10 (gram)) when a system consisting of a mixture of metallic antimony (Sb) and hydrogen chloride (HCl) is heated from 0° C. to 500° C.;
• FIG. 1 is a diagram showing the results of a thermodynamic equilibrium calculation (vertical axis is log 10 (gram)) when a system consisting of a mixture of metallic antimony (Sb) and hydrogen chloride (HCl) is heated from 0° C. to 500° C.;
• Sb antimony trioxide
• HCl hydrogen chloride
• FIG. 1 is a diagram showing the results of a thermodynamic equilibrium calculation (vertical axis is log 10 (gram)) when a system consisting of a mixture of antimony trioxide (Sb 2 O 3 ) and ammonium chloride (NH 4 Cl) is heated from 0° C. to 500° C.
• FIG. 1 is a diagram showing the results of thermodynamic equilibrium calculations (vertical axis is log 10 (gram)) when a system consisting of a mixture of metallic antimony (Sb) and ammonium chloride (NH 4 Cl) is heated from 0° C. to 500° C.
• 1 is an XRD pattern of molybdenum trioxide obtained by the manufacturing method of the present disclosure.
• a raw material consisting of molybdenum trioxide ( MoO3 ), ammonium molybdate (( NH4 ) Mo7O24 ), other molybdenum compounds, or hydrates thereof is used. It is preferable to use a raw material with few impurities, and it is preferable to use a raw material with a purity of 90% by weight or more, 99% by weight or more, or 99.9% by weight or more. According to the present disclosure, even when a high-purity raw material is used, it is possible to significantly reduce the Sb content, which is difficult to remove using conventional methods or is only poorly removed.
• MoO 3 molybdenum trioxide
• NH 4 ammonium molybdate
• HCl hydrogen chloride
• FIG. 1 shows the results of a thermodynamic equilibrium calculation when a system consisting of a mixture of antimony oxide (Sb 2 O 3 ) and hydrogen chloride (HCl) is heated from 0°C to 500°C under atmospheric pressure.
• (s) represents the solid phase
• (g) represents the gas phase.
• the calculation was performed using the thermodynamic equilibrium calculation software Factsage. It is believed that the antimony (Sb) contained in the raw material molybdenum trioxide, ammonium molybdate, or other molybdenum compounds or their hydrates exists as antimony oxide. According to the thermodynamic calculation in FIG.
• heating in the presence of hydrogen chloride causes the antimony (Sb) in the antimony oxide to react with hydrogen chloride to produce antimony trichloride (SbCl 3 ).
• This antimony trichloride becomes liquid at temperatures above 70°C, and a portion of it vaporizes and volatilizes. Furthermore, at temperatures above 100°C, it cannot exist as a solid or liquid and instead becomes a gas and desorbs from the system, thereby reducing the Sb present as an impurity (in the form of antimony oxide) in the raw material.
• FIG. 2 shows the results of a thermodynamic equilibrium calculation when a system consisting of a mixture of antimony (Sb) and hydrogen chloride (HCl) is heated from 0°C to 500°C under atmospheric pressure.
• (s) represents the solid phase
• (g) represents the gas phase.
• the calculation was performed using the thermodynamic equilibrium calculation software Factsage. Even if the antimony (Sb) contained in the raw material molybdenum trioxide, ammonium molybdate, or other molybdenum compounds or their hydrates exists in a form other than antimony oxide, such as metallic antimony, the thermodynamic calculation in FIG. 2 shows that when heated in the presence of hydrogen chloride, it reacts with hydrogen chloride to produce antimony trichloride (SbCl 3 ).
• This antimony trichloride becomes liquid at temperatures above 70°C, and a portion of it volatilizes as vapor. Furthermore, at temperatures above 145°C, it cannot exist as a solid or liquid and becomes a gas and is desorbed from the system, thereby reducing the amount of Sb present as an impurity (in the form of metallic antimony) in the raw material.
• a raw material consisting of ammonium molybdate or a hydrate thereof is mixed with ammonium chloride, and the resulting mixture is then heated at 70°C or higher.
• This causes chlorine, hydrogen chloride, or chloride to react with the Sb impurity contained in the raw material, resulting in the formation and desorption of SbCl3 (gas).
• the heating temperature is preferably 100°C or higher, more preferably 145°C or higher. There is no particular upper limit to the heating temperature, but it is preferably 550°C or lower.
• the heating time depends on the amount of raw material and the heating temperature, it is preferably 1 hour or longer.
• heating time there is no particular upper limit to the heating time, but from an energy cost perspective, it is preferably 72 hours or less, and more preferably 48 hours or less. Excess chlorine, hydrogen chloride, or chloride added can be desorbed as a gas. Furthermore, since the raw material molybdenum compound or a hydrate thereof is converted to molybdenum trioxide (solid) by heating, molybdenum trioxide with a reduced Sb content can be simultaneously produced.
• a raw material made of molybdenum trioxide ( MoO3 ), ammonium molybdate (( NH4 ) Mo7O24 ), or a hydrate thereof is used. It is preferable to use a raw material with few impurities , and it is preferable to use a raw material with a purity of 90% by weight or more, 99% by weight or more, or 99.9% by weight or more. According to the present disclosure, even when a high-purity raw material is used, it is possible to significantly reduce the Sb content, which is difficult to remove using conventional methods or is only poorly removed.
• a raw material consisting of molybdenum trioxide, ammonium molybdate, or a hydrate thereof is mixed with ammonium chloride or an aqueous solution containing ammonium chloride.
• the following methods can be used as a combination of the mixtures: 1) A method of mixing molybdenum trioxide, ammonium molybdate or a hydrate thereof (all solids) with ammonium chloride (solid). 2) A method of mixing molybdenum trioxide, ammonium molybdate or a hydrate thereof with an aqueous solution containing ammonium chloride.
• FIG. 3 shows the results of a thermodynamic equilibrium calculation when a system consisting of a mixture of antimony trioxide (Sb 2 O 3 ) and ammonium chloride (NH 4 Cl) is heated from 0° C. to 500° C. under air.
• (s) represents the solid phase
• (g) represents the gas phase.
• the calculation was performed using the thermodynamic equilibrium calculation software FactSage. It is believed that the antimony (Sb) contained in the raw material molybdenum trioxide, ammonium molybdate, or other molybdenum compounds, or their hydrates, exists as antimony oxide. According to the thermodynamic calculation in FIG.
• FIG. 4 shows the results of a thermodynamic equilibrium calculation when a system consisting of a mixture of antimony (Sb) and ammonium chloride (NH 4 Cl) is heated from 0° C. to 500° C. under air.
• (s) represents the solid phase
• (g) represents the gas phase.
• the calculation was performed using the thermodynamic equilibrium calculation software Factsage. Even if the antimony (Sb) contained in the raw material molybdenum trioxide, ammonium molybdate, or other molybdenum compounds, or their hydrates, exists in a form other than antimony oxide, for example, as metallic antimony, according to the thermodynamic calculation in FIG.
• a raw material consisting of molybdenum trioxide, ammonium molybdate, or a hydrate thereof is mixed with ammonium chloride, and the resulting mixture is then heated at 180°C or higher (preferably 270°C or higher, more preferably 400°C or higher). Heating this mixture causes the ammonium chloride to react with the Sb impurity contained in the raw material, resulting in the formation of SbCl3 (gas), which can be desorbed.
• There is no particular upper limit to the heating temperature but a temperature of 550°C or lower is preferred.
• the heating time which depends on the amount of raw material and the heating temperature, is preferably 1 hour or longer.
• heating time there is no particular upper limit to the heating time, but from an energy cost perspective, a temperature of 72 hours or less is preferred, and 48 hours or less is even more preferred. Excess ammonium chloride added can be desorbed as a gas. Furthermore, since the raw material ammonium molybdate or a hydrate thereof is converted to molybdenum trioxide (solid) by heating, molybdenum trioxide with a reduced Sb content can be simultaneously produced.
• a raw material consisting of molybdenum trioxide, ammonium molybdate, or a hydrate thereof is mixed with an aqueous solution containing ammonium chloride, and the mixture is then heated.
• the water evaporates and ammonium chloride precipitates.
• the precipitated ammonium chloride reacts with the Sb impurity contained in the raw material to form SbCl 3 (gas), which can be desorbed.
• the mixture may be heated at a relatively low temperature of about 100°C to evaporate the water and precipitate the ammonium chloride and molybdenum compound, and then the mixture of ammonium chloride and the molybdenum compound may be heated at 180°C or higher (preferably 270°C or higher, more preferably 400°C or higher).
• the mixture may be heated from the beginning at 180°C or higher (preferably 270°C or higher, more preferably 400°C or higher) without such stepwise heating.
• raw materials consisting of molybdenum trioxide, ammonium molybdate, or hydrates of these are mixed with ammonium water. At this time, some or all of the raw materials will dissolve in the ammonia water depending on the pH and the amount of ammonia water added, but it is not necessary for some to remain undissolved. In addition, pure water can be added to this mixed solution, but the amount of pure water added is not particularly important.
• hydrochloric acid is mixed with the mixed solution. The amount of hydrochloric acid to be mixed is not important, but it is preferably added until the pH reaches 9 to 6. At this time, the mixture contains molybdenum compounds or molybdenum compound ions, ammonium ions, and chloride ions.
• heating evaporates water and precipitates ammonium chloride.
• the precipitated ammonium chloride reacts with Sb, an impurity contained in the raw material, to form SbCl 3 (gas), which can be desorbed.
• heating may be performed at a relatively low temperature of about 100°C to evaporate water and precipitate ammonium chloride and a molybdenum compound, and then the mixture of ammonium chloride and a molybdenum compound may be heated at 180°C or higher (preferably 270°C or higher, more preferably 400°C or higher).
• the mixture may be heated from the beginning at 180°C or higher (preferably 270°C or higher, more preferably 400°C or higher) without such stepwise heating.
• a raw material consisting of molybdenum trioxide, ammonium molybdate, or a hydrate thereof can be mixed with hydrochloric acid.
• the raw material is suspended in the hydrochloric acid without dissolving.
• this suspension is heated to 55-65°C, some or all of the raw material dissolves depending on the amount of hydrochloric acid added.
• ammonia water is added while maintaining the temperature of this mixture at approximately 60°C, ammonium molybdate and ammonium chloride precipitate.
• the mixture is allowed to stand for approximately 30 minutes, and the supernatant liquid and solids (ammonium molybdate and ammonium chloride) are separated by decantation.
• This series of steps may be repeated, or the solids obtained by precipitation and separation may be mixed with hydrochloric acid and heated again, followed by addition of ammonium water to precipitate and separate ammonium molybdate and ammonium chloride.
• the precipitated and separated solids are then heated at 180°C or higher (preferably 270°C or higher, more preferably 400°C or higher).
• the Sb impurity contained in the raw material reacts with the ammonium chloride to form gaseous SbCl 3 , which can be desorbed from the solid.
• heating may not be necessary after mixing the raw material consisting of molybdenum trioxide, ammonium molybdate, or a hydrate thereof with hydrochloric acid.
• the raw material may dissolve, but dissolution is not necessary.
• ammonia water is added to this mixed solution to produce a mixture of the raw material and an aqueous solution containing ammonium chloride.
• this mixture is heated to 180°C or higher (preferably 270°C or higher, more preferably 400°C or higher). This causes the Sb impurity contained in the raw material to react with the ammonium chloride, forming gaseous SbCl3 , which can be desorbed from the solid.
• the above manufacturing method makes it possible to obtain molybdenum trioxide with reduced Sb, which is difficult to remove using conventional methods or is only effectively removed.
• the Sb content can be reduced to less than one-third by weight of the Sb content contained in the raw material. It can even be reduced to less than one-fifth, and especially to less than one-tenth.
• the Sb content can be reduced to less than 0.2 ppm by weight, or even less than 0.1 ppm by weight.
• the Sb content can be reduced to less than 0.05 ppm by weight, whether using high-purity or low-purity raw materials.
• the manufacturing method disclosed herein makes it possible to obtain molybdenum trioxide with reduced sulfur.
• the sulfur content can be reduced to less than half the weight ratio of the sulfur content contained in the raw material. It can even be reduced to less than one-third, and especially to less than one-tenth.
• the sulfur content can be reduced to less than 0.1 ppm by weight, and to less than 0.05 ppm by weight when high-purity raw materials are used.
• Example 1 Ammonium molybdate tetrahydrate raw material (75 g) with a purity of 99.9% or higher was mixed with 150 ml of aqueous ammonia (concentration: 28 wt%) and 250 ml of water. At this time, the ammonium molybdate raw material was dissolved in the aqueous ammonia. Furthermore, 100 ml of hydrochloric acid (concentration: 36 wt%) was mixed with this solution. At this time, the pH was adjusted to 6.99. The resulting solution was heated at 480°C for 8 hours to obtain molybdenum trioxide (solid).
• Example 2 75 g of molybdenum trioxide raw material with a purity of 98% or higher was mixed with 150 ml of ammonia water (concentration: 28 wt%) and 250 ml of water. At this time, the molybdenum trioxide raw material was dissolved in the ammonia water. 65 ml of hydrochloric acid (concentration: 36 wt%) was further mixed with this solution. At this time, the pH was adjusted to 8.26. The solution thus obtained was heated at 480°C for 5 hours to obtain molybdenum trioxide (solid).
• Example 3 363 ml of hydrochloric acid (concentration: 36 wt%) was mixed with 75 g of molybdenum trioxide raw material with a purity of 98% or higher. The molybdenum trioxide raw material was insoluble in hydrochloric acid. This suspension was heated at 60°C for 1 hour to dissolve the molybdenum trioxide raw material. While maintaining the temperature of this solution at 60°C, 270 mL of ammonia water (concentration: 28 wt%) was added. Ammonium molybdate (solid) and ammonium chloride (solid) were obtained in the solution, and the pH of the supernatant was 1.00.
• Example 4 Ammonium chloride (999 g) with a purity of 99.5% or higher was mixed with 5002 g of ammonium molybdate tetrahydrate raw material. The mixture was in powder form. The mixture was heated at 480°C for 6 hours to obtain a gray solid. When analyzed by XRD, all observed peaks were attributed to molybdenum trioxide, as shown in Figure 5, confirming that the resulting solid material was molybdenum trioxide.
• the S content in the raw material ammonium molybdate tetrahydrate was 3.1 ppm by weight, whereas the S content in the finally obtained molybdenum trioxide was 0.96 ppm by weight, which was reduced to approximately one-third of the S content in the raw material.
• one embodiment of the present invention may contribute to Goal 9 of the United Nations-led Sustainable Development Goals (SDGs), "Build resilient infrastructure, promote inclusive and sustainable industrialization and foster innovation," and Goal 12, “Ensure sustainable consumption and production patterns.”
• SDGs United Nations-led Sustainable Development Goals
• the molybdenum trioxide obtained by the production method according to the embodiment of the present invention is particularly useful as a molybdenum oxychloride raw material used as a precursor for CVD or ALD.

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  • 2024-04-23 JP JP2024069577A patent/JP2024106994A/ja active Pending
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