A method for reducing particulate matter in high-purity copper alloy ingots

Abstract

The present invention relates to a method for reducing particulate matter in a high-purity copper alloy ingot, the method comprising the following steps: (1) mixing electrolytic copper and copper oxide, and then melting to obtain copper liquid; (2) subjecting the copper liquid obtained in step (1) to a displacement reaction to obtain purified copper liquid; (3) mixing the purified copper liquid obtained in step (2) with a supplementary metal raw material, and then refining to obtain an alloy liquid; and (4) sequentially casting and cooling the alloy liquid obtained in step (3) to obtain a copper alloy ingot. The method provided by the present invention can effectively remove carbon particles in the copper alloy ingot, thereby reducing the content of total particulate matter in the ingot, and does not introduce other impurities, is simple to operate, and can be industrially applied.

Description

Technical Field

[0001] The invention relates to the technical field of copper alloy casting, and in particular to a method for reducing particulate matter in a high-purity copper alloy ingot. Background Art

[0002] With the development of large-scale integrated circuits, semiconductor chips have also experienced rapid growth, with increasing integration, smaller sizes, and lower power consumption. This has placed higher demands on the materials used in semiconductor chips. Currently, traditional aluminum and aluminum alloys are no longer able to meet the process requirements of semiconductor chips, leading to the use of copper and copper alloys with higher conductivity as sputtering targets. The quality of high-purity copper alloy ingots directly affects the quality of the target material, which in turn affects the process performance of semiconductor chips.

[0003] Currently, the smelting process for high-purity copper alloys includes multiple steps, including furnace charging, heating and smelting, alloy proportioning, and ingot casting. However, the existing process is affected by the feeding method and the crucible material, which inevitably introduces impurities such as carbon particles during the casting process, resulting in the target material being scrapped after being put into the machine. Currently, methods for improving carbon particles in the ingot include: applying special coatings to the crucible, increasing the crucible density, and changing the crucible material. Among them, while applying special coatings to the crucible can protect the crucible surface from corrosion, the crucible coating is still easily scratched due to the limited feeding method, leading to an increase in carbon particle content. While changing the crucible material can avoid the introduction of carbon particle impurities, it inevitably introduces other impurities. Therefore, these methods cannot completely solve the problem of excessive carbon particle and impurity content in the ingot. The total particle content in the target material is primarily determined by carbon particles. If the number of carbon particles is not controlled, the total particle count will ultimately increase significantly.

[0004] CN113667860A discloses an ultra-high-purity copper-aluminum ingot, its preparation method, and use. The preparation method primarily comprises slicing the aluminum ingot, surface treating it, and vacuum packaging it to obtain an aluminum block for the ultra-high-purity copper-aluminum ingot; adding the aluminum block to vacuum-melted copper raw material, shaking it to evenly mix it, casting it, and cooling it to obtain the ultra-high-purity copper-aluminum ingot. While this method can produce an ultra-high-purity copper-aluminum ingot, it still cannot avoid the problem of carbon particle content, which also increases the total particulate matter content, thereby affecting the performance of the target material.

[0005] CN113737011A discloses a method for preparing an ultra-high-purity copper-manganese alloy using electron beam melting. The method comprises the following steps: pickling and mixing ultra-high-purity copper and manganese raw materials, followed by hot isostatic pressing to produce an ultra-high-purity copper-manganese alloy billet; and electron beam melting and ingot drawing to produce the ultra-high-purity copper-manganese alloy. While this method can reduce carbon particle inclusions, it places high demands on equipment and is expensive.

[0006] Therefore, it is of great significance to provide a method that is simple to operate and can effectively reduce particulate matter in copper alloy ingots. Summary of the Invention

[0007] In response to the above problems, the purpose of the present invention is to provide a method for reducing particulate matter in high-purity copper alloy ingots. Compared with the prior art, the method provided by the present invention can effectively remove carbon particles in copper alloy ingots, thereby reducing the total particle content, and does not introduce other impurities. It is simple to operate and can be applied industrially.

[0008] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0009] The present invention provides a method for reducing particulate matter in a high-purity copper alloy ingot, the method comprising the following steps:

[0010] (1) mixing electrolytic copper and copper oxide, and then melting them to obtain molten copper;

[0011] (2) subjecting the copper water obtained in step (1) to a displacement reaction to obtain purified copper water;

[0012] (3) mixing the supplementary metal raw material and the purified copper water obtained in step (2), and then refining to obtain an alloy liquid;

[0013] (4) Casting and cooling the alloy liquid obtained in step (3) in sequence to obtain a copper alloy ingot.

[0014] The method provided by the present invention adds electrolytic copper and copper oxide simultaneously, and uses the added copper oxide to react with carbon particles in the melt at high temperature to generate copper and carbon dioxide, so that the carbon particles in the melt can be effectively removed, thereby reducing the total particle content without introducing other impurities. This method is useful for improving the purity of high-purity copper alloy ingots and avoiding scrapping due to excessive carbon particle content in subsequent applications.

[0015] In the present invention, the high-purity copper alloy ingot refers to a copper alloy with a purity of ≥99.9999%.

[0016] Preferably, the purity of the electrolytic copper in step (1) is ≥6N, for example, it can be 99.99991%, 99.99992%, 99.99993%, 99.99994% or 99.99995%, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0017] Preferably, the mass of the copper oxide in step (1) accounts for 0.0015-0.002% of the mass of the electrolytic copper, for example, it can be 0.0015%, 0.0016%, 0.0017%, 0.0018%, 0.0019% or 0.002%, but is not limited to the listed values. Other values ​​not listed within the numerical range are also applicable.

[0018] In the present invention, it is preferred to control the percentage of the mass of copper oxide to the mass of electrolytic copper within a specific range, which can further reduce the content of carbon particles in the melt while avoiding corrosion of the graphite crucible caused by excessive copper oxide content.

[0019] Preferably, the melting temperature in step (1) is 1250-1500°C, for example, 1250°C, 1300°C, 1350°C, 1340°C, 1450°C or 1500°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0020] In the present invention, it is preferred to control the melting temperature within a specific range, which can further promote the reaction between copper oxide and carbon particles and reduce the content of carbon particles in the melt.

[0021] Preferably, vacuum treatment is performed during the melting process in step (1).

[0022] Preferably, the vacuum degree at the end of the vacuum treatment is (2-7)×10 -3 Pa, for example, can be 2×10 -3 Pa, 3×10 -3 Pa, 4×10 -3 Pa, 5×10 -3 Pa or 7×10 -3 Pa, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0023] In the present invention, it is preferred to perform vacuum treatment and control the terminal vacuum degree within a specific range, so as to fully utilize the vacuum to extract the carbon dioxide gas generated by the reaction of copper oxide and carbon particles, thereby reducing the carbon content in the ingot and ultimately reducing the total particle content.

[0024] Preferably, the replacement reaction in step (2) comprises: introducing argon gas into the copper water for replacement.

[0025] Preferably, the relative pressure in the system during the replacement reaction is 300-350 Pa, for example, 300 Pa, 310 Pa, 320 Pa, 330 Pa, 340 Pa or 350 Pa, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0026] Preferably, the supplementary metal raw material in step (3) includes aluminum raw material and / or manganese raw material.

[0027] Preferably, the purity of the aluminum raw material is ≥5N, for example, it can be 99.9991%, 99.9992%, 99.9993% or 99.9994%, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0028] Preferably, the purity of the manganese raw material is ≥5N, for example, it can be 99.9991%, 99.9992%, 99.9993% or 99.9994%, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0029] Preferably, the mass of the supplementary metal raw material in step (2) accounts for 0.02-0.05% of the mass of the purified copper water, for example, it can be 0.02%, 0.025%, 0.03%, 0.035%, 0.04%, 0.045% or 0.05%, but is not limited to the listed values. Other values ​​not listed within the numerical range are also applicable.

[0030] Preferably, the refining temperature in step (3) is 1350-1450°C, for example, it can be 1350°C, 1360°C, 1370°C, 1380°C, 1390°C, 1400°C, 1410°C, 1420°C, 1430°C, 1440°C or 1450°C, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0031] Preferably, the refining time is 30-35 min, for example, 31 min, 32 min, 33 min, 34 min or 35 min, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0032] Preferably, the vacuum degree during refining is (2-7)×10 -3 Pa, for example, can be 2×10 -3 Pa, 3×10 -3 Pa, 4×10 -3 Pa, 5×10 -3 Pa or 7×10 -3 Pa, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0033] Preferably, the casting temperature in step (4) is 1150-1250°C, for example, it can be 1150°C, 1160°C, 1170°C, 1180°C, 1190°C, 1200°C, 1210°C, 1220°C, 1230°C, 1240°C or 1250°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0034] As a preferred technical solution of the present invention, the method comprises the following steps:

[0035] (1) Mix electrolytic copper and copper oxide, then heat at 1250-1500℃, (2-7)×10 -3 Melt under vacuum degree of Pa to obtain molten copper;

[0036] The purity of the electrolytic copper is ≥6N, and the mass of the copper oxide accounts for 0.0015-0.002% of the mass of the electrolytic copper;

[0037] (2) introducing argon into the copper water obtained in step (1) to perform a displacement reaction, wherein the relative pressure in the system during the displacement reaction is 300-350 Pa, to obtain purified copper water;

[0038] (3) mixing the purified copper water obtained in step (2) with the supplementary metal raw material, and then heating at 1350-1450°C and a vacuum degree of (2-7)×10 -3 Refining was carried out at 30-35 min under Pa to obtain alloy liquid;

[0039] The supplementary metal raw materials include aluminum raw materials and / or manganese raw materials, the purity of the aluminum raw materials is ≥5N, the purity of the manganese raw materials is ≥5N, and the mass of the supplementary metal raw materials accounts for 0.02-0.05% of the mass of the purified copper water;

[0040] (4) Casting the alloy liquid obtained in step (3) at 1150-1250° C. and then cooling to obtain a copper alloy ingot.

[0041] Compared with the prior art, the present invention has the following beneficial effects:

[0042] The method provided by the present invention mixes electrolytic copper and copper oxide, and utilizes the copper oxide to react with carbon particles under high temperature conditions to generate carbon dioxide, thereby effectively reducing the content of carbon particles in the ingot and further reducing the total particle content. Under optimal conditions, the preparation method provided by the present invention can reduce the content of particles larger than 1.3 μm to below 8109 ppb, the content of particles larger than 5 μm to below 1023 ppb, the content of particles larger than 10 μm to below 355 ppb, and the content of particles larger than 20 μm to below 25 ppb, while avoiding the introduction of other impurities, being simple to operate, and being suitable for industrial application. DETAILED DESCRIPTION

[0043] The technical solution of the present invention is further described below by way of specific embodiments. It should be understood by those skilled in the art that the embodiments are merely to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0044] Example 1

[0045] This embodiment provides a method for reducing particulate matter in a high-purity copper alloy ingot, the method comprising the following steps:

[0046] (1) Electrolytic copper and copper oxide were mixed and then heated at 1300℃, 4.5×10 -3 Melt under vacuum degree of Pa to obtain molten copper;

[0047] The purity of the electrolytic copper is 99.9999%, and the mass of the copper oxide accounts for 0.0017% of the mass of the electrolytic copper;

[0048] (2) introducing argon into the copper water obtained in step (1) to perform a displacement reaction, wherein the relative pressure in the system during the displacement reaction is 320 Pa, to obtain purified copper water;

[0049] (3) The purified copper water obtained in step (2) and the manganese raw material are mixed, and then heated at 1400°C and a vacuum degree of 4.5×10 -3 Refining was carried out at Pa for 32 min to obtain alloy liquid;

[0050] The purity of the manganese raw material is 99.999%, and the mass of the manganese raw material accounts for 0.03% of the mass of the purified copper water;

[0051] (4) Casting the alloy liquid obtained in step (3) at 1200° C. and then cooling it to obtain a copper alloy ingot.

[0052] Example 2

[0053] This embodiment provides a method for reducing particulate matter in a high-purity copper alloy ingot, the method comprising the following steps:

[0054] (1) Electrolytic copper and copper oxide were mixed and then heated at 1250℃ for 5×10 -3 Melt under vacuum degree of Pa to obtain molten copper;

[0055] The purity of the electrolytic copper is 99.99991%, and the mass of the copper oxide accounts for 0.002% of the mass of the electrolytic copper;

[0056] (2) introducing argon into the copper water obtained in step (1) to perform a displacement reaction, wherein the relative pressure in the system during the displacement reaction is 300 Pa, to obtain purified copper water;

[0057] (3) The purified copper water obtained in step (2) and the manganese raw material are mixed and then heated at 1450°C and a vacuum degree of 4×10 - 3 Refining was carried out at Pa for 30 min to obtain alloy liquid;

[0058] The purity of the manganese raw material is 99.9992%, and the mass of the manganese raw material accounts for 0.02% of the mass of the purified copper water;

[0059] (4) Casting the alloy liquid obtained in step (3) at 1250° C. and then cooling it to obtain a copper alloy ingot.

[0060] Example 3

[0061] This embodiment provides a method for reducing particulate matter in a high-purity copper alloy ingot, the method comprising the following steps:

[0062] (1) Mix electrolytic copper and copper oxide, then heat at 1500℃, 7×10 -3 Melt under vacuum degree of Pa to obtain molten copper;

[0063] The purity of the electrolytic copper is 99.99993%, and the mass of the copper oxide accounts for 0.0015% of the mass of the electrolytic copper;

[0064] (2) introducing argon into the copper water obtained in step (1) to perform a displacement reaction, wherein the relative pressure in the system during the displacement reaction is 350 Pa, to obtain purified copper water;

[0065] (3) The purified copper water obtained in step (2) and the aluminum raw material are mixed, and then heated at 1350°C and a vacuum degree of 7×10 - 3 Refining was carried out at Pa for 35 min to obtain alloy liquid;

[0066] The purity of the aluminum raw material is 99.9994%, and the mass of the aluminum raw material accounts for 0.05% of the mass of the purified copper water;

[0067] (4) Casting the alloy liquid obtained in step (3) at 1150° C. and then cooling it to obtain a copper alloy ingot.

[0068] Example 4

[0069] This embodiment provides a method for reducing particulate matter in a high-purity copper alloy ingot. The only difference from Example 1 is that the mass of copper oxide accounts for 0.001% of the mass of the electrolytic copper.

[0070] Example 5

[0071] This embodiment provides a method for reducing particulate matter in a high-purity copper alloy ingot. The only difference from Example 1 is that the mass of copper oxide accounts for 0.002% of the mass of electrolytic copper.

[0072] Comparative Example 1

[0073] This comparative example provides a method for preparing a high-purity copper alloy ingot, which differs from Example 1 only in that copper oxide is not added in step (1).

[0074] The total particulate matter content in the copper alloy ingots obtained in Examples 1-5 and Comparative Example 1 was detected by liquid particle technology test (LPC), where the total particulate matter content is mainly determined by the carbon particle content. The results are shown in Table 1.

[0075] Table 1

[0076]

[0077]

[0078] The following points can be seen from the data in Table 1:

[0079] (1) From the data of Examples 1-3, it can be seen that under optimal conditions, the preparation method provided by the present invention can reduce the content of particles >1.3 μm to below 8109 ppb, the content of particles >5 μm to below 1023 ppb, the content of particles >10 μm to below 355 ppb, and the content of particles >20 μm to below 25 ppb.

[0080] (2) A comprehensive comparison of the data of Example 1, Examples 4-5, and Comparative Example 1 shows that the only difference between Comparative Example 1 and Example 1 is that no copper oxide is added, and the only difference between Examples 4-5 and Example 1 is that the mass proportion of copper oxide is not within the preferred range of the present invention. The content of particulate matter in Examples 4-5 and Comparative Example 1 is significantly higher than that in Example 1. Therefore, the present invention can reduce the content of particulate matter, especially the content of carbon particles, by adding copper oxide and controlling the amount of copper oxide added within a specific range.

[0081] In summary, the method provided by the present invention can effectively reduce the content of carbon particles in the ingot, thereby reducing the total particulate matter content, and avoiding the introduction of other impurities, by mixing electrolytic copper and copper oxide, and utilizing copper oxide to react with carbon particles under high temperature conditions to generate carbon dioxide. The operation is simple and can be applied industrially.

[0082] The applicant declares that the above is only a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention fall within the scope of protection and disclosure of the present invention.

Claims

1. A method for reducing particulate matter in a high-purity copper alloy ingot, characterized in that: The method comprises the following steps: (1) mixing electrolytic copper and copper oxide in a graphite crucible and then melting them to obtain molten copper; The mass of the copper oxide accounts for 0.0015-0.002% of the mass of the electrolytic copper; (2) subjecting the copper water obtained in step (1) to a displacement reaction to obtain purified copper water; The replacement reaction comprises: introducing argon gas into the copper water for replacement; (3) mixing the supplementary metal raw material and the purified copper water obtained in step (2), and then refining to obtain an alloy liquid; (4) Casting and cooling the alloy liquid obtained in step (3) in sequence to obtain a copper alloy ingot.

2. The method according to claim 1, characterized in that The purity of the electrolytic copper in step (1) is ≥6N.

3. The method according to claim 1, characterized in that The melting temperature in step (1) is 1250-1500°C.

4. The method according to claim 1, wherein During the melting process of step (1), vacuum treatment is performed.

5. The method according to claim 4, characterized in that The terminal vacuum degree of the vacuum treatment is (2-7)×10 -3 Pa.

6. The method according to claim 1, characterized in that The relative pressure in the system during the replacement reaction in step (2) is 300-350 Pa.

7. The method according to claim 1, characterized in that The supplementary metal raw materials in step (3) include aluminum raw materials and / or manganese raw materials.

8. The method according to claim 7, characterized in that The purity of the aluminum raw material is ≥5N.

9. The method according to claim 7, characterized in that The purity of the manganese raw material is ≥5N.

10. The method according to claim 1, characterized in that The mass of the supplementary metal raw material in step (3) accounts for 0.02-0.05% of the mass of the purified copper water.

11. The method according to claim 1, characterized in that The refining temperature in step (3) is 1350-1450°C.

12. The method according to claim 1, characterized in that The refining time is 30-35 minutes.

13. The method according to claim 1, wherein The vacuum degree during refining is (2-7)×10 -3 Pa.

14. The method according to claim 1, wherein The casting temperature in step (4) is 1150-1250°C.

15. The method according to claim 1, wherein The method comprises the following steps: (1) Mix electrolytic copper and copper oxide, then heat at 1250-1500℃, (2-7)×10 -3 Melt under vacuum degree of Pa to obtain molten copper; The purity of the electrolytic copper is ≥6N, and the mass of the copper oxide accounts for 0.0015-0.002% of the mass of the electrolytic copper; (2) introducing argon into the copper water obtained in step (1) to perform a displacement reaction, wherein the relative pressure in the system during the displacement reaction is 300-350 Pa, to obtain purified copper water; (3) mixing the purified copper water obtained in step (2) with the supplementary metal raw material, and then heating at 1350-1450°C and a vacuum degree of (2-7)×10 -3 Refining was carried out at 30-35 min under Pa to obtain alloy liquid; The supplementary metal raw materials include aluminum raw materials and / or manganese raw materials, the purity of the aluminum raw materials is ≥5N, the purity of the manganese raw materials is ≥5N, and the mass of the supplementary metal raw materials accounts for 0.02-0.05% of the mass of the purified copper water; (4) Casting the alloy liquid obtained in step (3) at 1150-1250° C. and then cooling to obtain a copper alloy ingot.

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