Ultralow-oxygen-content pure copper thick plate for magnetron sputtering coating and preparation method of ultralow-oxygen-content pure copper thick plate

Abstract

The invention discloses an ultra-low oxygen content pure copper thick plate for magnetron sputtering coating and a preparation method thereof, the ultra-low oxygen content pure copper thick plate for magnetron sputtering coating comprises the following components in percentage by weight: greater than or equal to 99.997% of Cu, 1-3 ppm of O, less than or equal to 5 ppm of Fe, less than or equal to 5 ppm of P, and the balance of inevitable impurity elements; during preparation, firstly, a pure copper thick plate is baked and then fed into a smelting furnace to be smelted, impurity elements and hydrogen in molten copper are removed in an oxygen hydrogen inhibition and oxidation mode, then charcoal covering and bottom blowing of carbon monoxide are adopted for oxygen removal, then heat preservation furnace refining and vertical all-continuous casting are conducted, and finally 12-pass rolling is conducted on a hot rolling mill. By accurately controlling the heating temperature, the heat preservation time, the rolling pass and the deformation amount, the grain size, uniformity and surface quality of a final product are ensured, internal defects are reduced, the prepared pure copper thick plate has the extremely high copper content and the extremely low oxygen content, and important material support is provided for industry development.

Description

Technical Field

[0001] The invention relates to the technical field of nonferrous metal processing, in particular to a thick pure copper plate with ultra-low oxygen content for magnetron sputtering coating and a preparation method thereof. Background Art

[0002] In the field of non-ferrous metal processing technology, high-purity copper materials are widely used in electronic components, semiconductor materials, and high-end equipment manufacturing due to their excellent electrical and thermal conductivity. Among them, high-purity oxygen-free copper has become one of the important materials in these fields due to its extremely low oxygen content and excellent comprehensive performance. However, the preparation and processing technology of high-purity oxygen-free copper is relatively difficult, and its grain size and uniformity have a significant impact on the performance of the material. In particular, in certain special applications, such as magnetron sputtering coating, which has extremely high requirements for material purity, oxygen content and microstructure, it belongs to the field of high-end copper applications. Therefore, how to prepare high-purity, fine-grained oxygen-free copper materials is an important technical challenge in this field.

[0003] Existing solutions primarily utilize refining, deoxidation, and high-temperature hot rolling processes to produce high-purity oxygen-free copper. The refining and deoxidation process primarily removes oxygen and other impurities from copper through chemical methods, resulting in high-purity copper. The high-temperature hot rolling process involves plastic deformation and recrystallization of the copper material through high-temperature heating and rolling, thereby refining the grain size. However, existing technologies for producing high-purity oxygen-free copper still face several challenges and limitations. First, existing refining and deoxidation processes struggle to reduce the oxygen content in copper to extremely low levels, typically only reaching around 5 ppm. This, combined with relatively high impurity levels, limits the further application of high-purity oxygen-free copper. Second, while existing high-temperature hot rolling processes can refine grain size, they can easily lead to excessive grain growth, impacting the overall performance of the material. Furthermore, existing technologies also face challenges in controlling grain size and uniformity, necessitating further technological innovation. Therefore, developing more efficient and precise technologies for producing high-purity oxygen-free copper materials with ultra-low oxygen content remains a critical issue in this field. Summary of the Invention

[0004] The purpose of the present invention is to solve the problem that the existing refining and deoxidation process is difficult to reduce the rolling elements and oxygen content in copper to extremely low levels, and the high-temperature hot rolling process easily leads to excessive grain growth. The present invention provides an ultra-low oxygen content pure copper thick plate for magnetron sputtering coating and a preparation method thereof. The present invention ensures the grain size, uniformity and surface quality of the final product by precisely controlling the heating temperature, holding time, rolling passes and deformation amount, reduces internal defects, and the prepared pure copper thick plate has an extremely high copper content (≥99.997%) and an extremely low oxygen content (1~3 ppm).

[0005] To achieve the above object, the present invention is implemented through the following technical solutions: The present invention provides an ultra-low oxygen content pure copper thick plate for magnetron sputtering coating. Calculated by weight percentage, the ultra-low oxygen content pure copper thick plate for magnetron sputtering coating has a Cu content of ≥99.997%, an O content of 1-3 ppm, an Fe content of ≤5 ppm, a P content of ≤5 ppm, and the remainder being unavoidable impurity elements.

[0006] The ultra-low oxygen content pure copper thick plate for magnetron sputtering coating in the present invention has a hardness of 85 to 95 HV and a grain size of 20 to 60 μm.

[0007] The present invention also provides a method for preparing a thick plate of pure copper with ultra-low oxygen content for magnetron sputtering coating, comprising the following steps: Step S1: baking a high-purity cathode copper plate with a copper content of ≥99.9935%; Step S2: adding the baked high-purity cathode copper plate into a smelting furnace for smelting, and performing bottom blowing to increase oxygen during the smelting process, thereby removing impurity elements and hydrogen in the copper liquid by suppressing hydrogen with oxygen and oxidizing the hydrogen to obtain a first intermediate melt; Step S3: The first intermediate melt is covered with charcoal and deoxygenated by bottom blowing carbon monoxide, and then CuP and CuMg master alloys are added in sequence to further remove oxygen through oxidation reaction, and the oxygen content is controlled at 1-3 ppm to obtain a second intermediate melt; Step S4: transferring the second intermediate melt to a holding furnace in a sealed environment, and then further refining it by blowing argon through the bottom of the holding furnace ventilation bricks to obtain a qualified copper melt; Step S5: Passing the qualified copper melt through the pouring pipe for vertical full continuous casting, and controlling the cooling water volume in the secondary cooling zone to 720-780 L / min to obtain a copper ingot; Step S6: The copper ingot is heated and kept warm in a walking beam heating furnace, and then rolled on a hot rolling mill for 12 passes, followed by degreasing, cleaning and drying to obtain a finished ultra-low oxygen content pure copper thick plate.

[0008] In the step S1 of the present invention, the baking temperature of the copper plate is 400-450° C., and the baking time is 100-150 s.

[0009] In the present invention, the oxygen content after oxygenation in step S2 is controlled to be 400-600 ppm.

[0010] In step S3 of the present invention, the oxygen content after charcoal covering and bottom blowing of carbon monoxide for deoxygenation is controlled at 10-20 ppm.

[0011] In the step S4 of the present invention, the temperature of the holding furnace is 1150-1180°C, and the dew point of the argon gas is -70°C--74°C.

[0012] In step S6 of the present invention, the heating temperature of the walking beam furnace is 750-800° C., and the holding time is 5-6 h.

[0013] The 12-pass rolling in step S6 of the present invention is performed by hot rolling on a hot rolling mill for 11 passes and immediately water cooling followed by 1 pass of cold rolling.

[0014] The thickness processing rate of the 11-pass hot rolling process in the present invention is 9%→12.00%→15%→17%→20%→20%→24%→22%→21%→19%→10.00%; the thickness deformation of the 12th pass is 6-8%, and the plate temperature after water cooling is ≤50°C.

[0015] In order to obtain a high-purity copper plate for magnetron sputtering coating with lower impurities and lower oxygen content, the present invention requires high-purity raw materials. From the perspective of raw material selection, high-purity electrolytic copper with relatively low impurity content needs to be selected to reduce the problems of impurity removal and incomplete removal during the smelting process. After comprehensive consideration, a high-purity cathode copper plate with a copper content of ≥99.9935% is finally selected as the raw material for addition.

[0016] Before adding the high-purity cathode copper plate to the smelting furnace for smelting, in order to reduce the mixing of gases such as hydrogen into the copper liquid due to the moisture of the copper plate, the high-purity cathode copper plate needs to be quickly baked to remove the water vapor attached to the copper plate. In order to ensure that the copper plate can be completely dried without affecting the loss of the copper plate and energy waste, the baking temperature of 400~450℃ and the baking time of 100~150s were finally selected as the most suitable ranges.

[0017] When high-purity cathode copper plates are added to the smelting furnace for melting, in order to effectively remove impurities inside the melt, improve the purity of the pure copper thick plate, and further improve the quality of the melt, oxygen is added through the bottom ventilation bricks at this stage. By adding oxygen, oxygen will react with impurities in the copper liquid to form intermetallic compounds that float up, and finally form a slag phase that is removed after skimming, thereby further improving the purity of the copper liquid. At the same time, oxygen and hydrogen in the copper liquid react to form bubbles that float up and are removed, thereby reducing the hydrogen content in the copper liquid. By removing hydrogen by oxygen suppression, the quality of the copper melt is improved. Through the combination of theoretical calculations and experiments, it is ultimately most appropriate to control the oxygen content at 400~600 ppm.

[0018] After most of the impurity elements and hydrogen are removed, the oxygen content needs to be further reduced. At this time, the copper liquid needs to be covered with charcoal to ensure that the copper liquid does not come into contact with the air, thereby preventing the copper liquid from absorbing gases such as hydrogen. At the same time, the oxygen in the copper liquid reacts with the charcoal to form carbon dioxide, thereby reducing the oxygen content in the copper liquid. Furthermore, carbon monoxide is introduced into the copper liquid through bottom blowing, and reacts with the oxygen in the copper liquid to remove the oxygen in the copper liquid. Deoxygenation is achieved through the coordinated control of charcoal covering and bottom blowing of carbon monoxide. Through theoretical analysis and experimental research, it is finally found that the oxygen content is most appropriately controlled at 10-20ppm. Because the ventilation time is too long due to too low an oxygen content, it is difficult to further reduce the oxygen content if the oxygen content is too high.

[0019] After ensuring the melt oxygen content is controlled at 10-20 ppm, the CuP master alloy is first added. When the oxygen content is controlled at around 5 ppm, the slag is thoroughly skimmed to ensure that the Fe and P in the slag are reduced and enter the copper liquid. The P and Fe contents are controlled below 5 ppm. Then, the CuMg master alloy is added to further deoxidize the melt. The amount of CuMg added is sufficient to control the oxygen content below 3 ppm. Considering the deoxidation cost and melt quality, the optimal melt oxygen content is determined to be 1-3 ppm.

[0020] After the melt from the smelting furnace is transferred to the holding furnace, in order to avoid melt aspiration and ensure the melt quality, it is best to control the holding furnace temperature at 1150~1180℃. If the temperature is too low, the melt fluidity will be poor, which is not conducive to subsequent casting; if the temperature is too high, the risk of melt aspiration will increase.

[0021] In order to further remove impurities and gas, argon gas is passed through the holding furnace for degassing. Taking into account the cost of passing argon gas and the purpose of further degassing, through theoretical calculation and experimental research, it is finally found that the most appropriate argon dew point value is controlled at -70℃~-74℃.

[0022] To achieve a relatively uniform and stable ingot structure, the cooling water flow in the secondary cooling zone must be controlled. An appropriate cooling water flow can control the cooling rate of the ingot, thereby preventing grain growth and achieving a fine, uniform grain structure. Experimental research ultimately determined that a cooling water flow rate of 720-780 L / min in the secondary cooling zone is optimal.

[0023] Because the heating temperature and holding time of a walking-beam furnace significantly influence the ingot's microstructure, heating can eliminate as-cast defects such as shrinkage, porosity, pores, and cracks, thereby improving the density and overall quality of the ingot. Heating can also make the ingot's microstructure more uniform, reduce segregation, and improve the grain structure. It can also reduce or eliminate internal stresses during casting, preventing deformation or cracking caused by stress concentration during subsequent processing. If the heating temperature is too low, the goal of achieving more uniform composition and finer microstructure will not be achieved, and the as-cast microstructure will remain, affecting subsequent processing performance. While excessively high temperatures can achieve more uniform composition and reduce segregation, they can also lead to excessive grain growth, impacting subsequent costs. Considering the grain size requirements for thick plate, a walking-beam furnace heating temperature of 750-800°C and a holding time of 5-6 hours are optimal.

[0024] The ingots are hot-rolled in 12 passes on a hot rolling mill. This hot rolling process ensures that the rolled plates achieve excellent uniform fine microstructure and a hardness suitable for customer requirements. Through hot rolling simulations and experimental exploration, the thickness processing rates for the first 11 hot rolling passes were determined to be 9% → 12.00% → 15% → 17% → 20% → 20% → 24% → 22% → 21% → 19% → 10.00%, respectively. The plates, after 11 passes, are then rapidly water-cooled to ensure a temperature of ≤50°C to prevent recrystallization caused by preheating during hot rolling. Cold rolling is then performed on the hot rolling mill to control the shape and hardness of the thick plates, ultimately resulting in a plate product whose structure, performance, and shape all meet the requirements.

[0025] The present invention solves the problem that the existing refining and deoxidation process is difficult to reduce the rolling element and oxygen content in copper to an extremely low level. By optimizing the refining and deoxidation process, high-purity preparation of high-purity oxygen-free copper materials is achieved; at the same time, it solves the problem that the existing high-temperature hot rolling process easily leads to excessive grain growth. By optimizing the high-temperature hot rolling process, precise control and refinement of the grains of the high-purity oxygen-free copper material are achieved; it also solves the problem that the existing technology has difficulties in controlling grain size and uniformity. By optimizing the heating process and rolling pass distribution, precise control of the grain size and uniformity of the high-purity oxygen-free copper material is achieved.

[0026] Compared with the prior art, the present invention has the following advantages: (1) By strictly controlling the purity of raw materials and the deoxidation steps during the preparation process, the pure copper thick plate produced has an extremely high copper content (≥99.997%) and an extremely low oxygen content (1~3 ppm). Through refining and specific chemical reactions, the content of impurity elements such as iron (Fe) and phosphorus (P) is effectively controlled, ensuring the electrical conductivity of the copper plate and the quality and performance of the magnetron sputtering coating.

[0027] (2) The prepared pure copper thick plate has suitable hardness (85-95 HV) and average grain size (20-60 μm), as well as a small grain size standard deviation (8-20), which ensures that the material has good mechanical properties and processing performance.

[0028] (3) The use of charcoal covering and bottom blowing of carbon monoxide for further deoxidation, as well as the refining step of bottom blowing of argon, ensure the purity and stability of the melt, which is conducive to the casting of high-quality copper ingots.

[0029] (4) By precisely controlling the heating temperature, holding time, rolling passes and deformation, the grain size, uniformity and surface quality of the final product are ensured, and internal defects are reduced.

[0030] (5) The ultra-low oxygen content pure copper thick plate prepared by the present invention has high purity and excellent performance. This material is suitable for high-end magnetron sputtering coating fields, such as semiconductors, optical films, electronic components, etc. It has broad application prospects and also provides important material support for the development of related industries. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is a metallographic diagram of a thick plate of ultra-low oxygen content pure copper prepared in Example 1 of the present invention; Figure 2 This is a metallographic image of the ultra-low oxygen content pure copper thick plate prepared in Comparative Example 1. DETAILED DESCRIPTION

[0032] The present invention will be further described in detail below with reference to the embodiments for a clearer understanding of the present invention, but they do not limit the present invention. Example 1

[0033] The present embodiment provides a pure copper thick plate with ultra-low oxygen content for magnetron sputtering coating. The composition of the pure copper thick plate with ultra-low oxygen content for magnetron sputtering coating, calculated by weight percentage, is shown in Table 1.

[0034] This embodiment provides a method for preparing a thick pure copper plate with ultra-low oxygen content for magnetron sputtering coating, comprising the following steps: Step S1: baking a high-purity cathode copper plate with a copper content of 99.9938% at 400°C for 150 seconds; Step S2: adding the baked high-purity cathode copper plate to a smelting furnace for smelting, bottom blowing oxygen to increase oxygen during the smelting process, and controlling the oxygen content after oxygenation to 500 ppm. Impurity elements and hydrogen in the copper liquid are removed by oxygen suppression and oxidation to obtain a first intermediate melt; Step S3: The first intermediate melt is covered with charcoal and deoxygenated by bottom blowing carbon monoxide. After the charcoal covering and bottom blowing of carbon monoxide, the oxygen content is controlled at 15 ppm. Then, a CuP master alloy is added for deoxidation. When the oxygen content is controlled at 5 ppm, a CuMg master alloy is added. The oxygen is further removed by oxidation reaction and the oxygen content is controlled at 2 ppm, thereby obtaining a second intermediate melt. Step S4: The second intermediate melt is transferred to a holding furnace in a sealed environment at a temperature of 1150°C, and then further refined by blowing argon through the bottom of the holding furnace through ventilation bricks, with the argon dew point being -70°C, to obtain a qualified copper melt; Step S5: Passing the qualified copper melt through the pouring pipe for vertical full continuous casting, and controlling the cooling water flow in the secondary cooling zone to 750 L / min to obtain a copper ingot; Step S6: The copper ingot is heated and kept warm in a walking beam heating furnace at a heating temperature of 770°C for a holding time of 5.5 h, and then rolled on a hot rolling mill for 12 passes, with 11 passes being hot rolled on the hot rolling mill, and thickness processing rates being 9%→12.00%→15%→17%→20%→20%→24%→22%→21%→19%→10.00%, respectively. The plate is then water-cooled, with the plate temperature after water cooling being 50°C. The plate is then cold-rolled for the 12th pass on the hot rolling mill, with a thickness deformation of 6% in the 12th pass. Finally, degreasing, cleaning, and drying are performed to obtain a finished ultra-low oxygen content pure copper thick plate with a thickness of 24 mm.

[0035] The ultra-low oxygen content pure copper thick plate obtained in this embodiment was subjected to metallographic examination and performance test. The metallographic examination diagram is shown in the attached Figure 1 ,It can be seen from the figure that the grain size is evenly distributed, with an average size of about 30 μm. ,The results of the performance test are shown in Table 2. Example 2

[0036] The present embodiment provides a pure copper thick plate with ultra-low oxygen content for magnetron sputtering coating. The composition of the pure copper thick plate with ultra-low oxygen content for magnetron sputtering coating, calculated by weight percentage, is shown in Table 1.

[0037] This embodiment provides a method for preparing a thick pure copper plate with ultra-low oxygen content for magnetron sputtering coating, comprising the following steps: Step S1: baking a high-purity cathode copper plate with a copper content of 99.9935% at 420°C for 130 seconds; Step S2: adding the baked high-purity cathode copper plate to a smelting furnace for smelting, bottom blowing oxygen during the smelting process, and controlling the oxygen content after oxygenation to 400 ppm. Impurity elements and hydrogen in the copper liquid are removed by oxygen suppression and oxidation to obtain a first intermediate melt; Step S3: The first intermediate melt is covered with charcoal and deoxygenated by bottom blowing carbon monoxide. After the charcoal covering and bottom blowing of carbon monoxide, the oxygen content is controlled at 10 ppm. Then, a CuP master alloy is added for deoxidation. When the oxygen content is controlled at 5 ppm, a CuMg master alloy is added. The oxygen is further removed by oxidation reaction and the oxygen content is controlled at 3 ppm, thereby obtaining a second intermediate melt. Step S4: The second intermediate melt is transferred to a holding furnace in a sealed environment at a temperature of 1160°C, and then further refined by blowing argon through the bottom of the holding furnace through ventilation bricks, with the argon dew point being -72°C, to obtain a qualified copper melt; Step S5: Passing the qualified copper melt through the pouring pipe for vertical full continuous casting, and controlling the cooling water flow in the secondary cooling zone to 720 L / min to obtain a copper ingot; Step S6: The copper ingot is heated and kept warm in a walking beam heating furnace at a heating temperature of 750°C for a holding time of 6 h, and then rolled on a hot rolling mill for 12 passes, with 11 passes being hot rolled on the hot rolling mill, and thickness processing rates being 9%→12.00%→15%→17%→20%→20%→24%→22%→21%→19%→10.00%, respectively. The plate is then water-cooled, with the plate temperature after water cooling being 45°C. The plate is then cold rolled for the 12th pass on the hot rolling mill, with a thickness deformation of 7% in the 12th pass. Finally, degreasing, cleaning, and drying are performed to obtain a finished ultra-low oxygen content pure copper thick plate with a thickness of 24.5 mm.

[0038] The properties of the ultra-low oxygen content pure copper thick plate obtained in this example were tested, and the test results are shown in Table 2. Example 3

[0039] The present embodiment provides a pure copper thick plate with ultra-low oxygen content for magnetron sputtering coating. The composition of the pure copper thick plate with ultra-low oxygen content for magnetron sputtering coating, calculated by weight percentage, is shown in Table 1.

[0040] This embodiment provides a method for preparing a thick pure copper plate with ultra-low oxygen content for magnetron sputtering coating, comprising the following steps: Step S1: baking a high-purity cathode copper plate with a copper content of 99.9936% at 450°C for 100 seconds; Step S2: adding the baked high-purity cathode copper plate to a smelting furnace for smelting, bottom blowing oxygen during the smelting process, and controlling the oxygen content after oxygenation to 600 ppm. Impurity elements and hydrogen in the copper liquid are removed by oxygen suppression and oxidation to obtain a first intermediate melt; Step S3: The first intermediate melt is covered with charcoal and deoxygenated by bottom blowing carbon monoxide. After the charcoal covering and bottom blowing carbon monoxide deoxygenation, the oxygen content is controlled at 20 ppm. Then, a CuP master alloy is added for deoxidation. When the oxygen content is controlled at 5 ppm, a CuMg master alloy is added. The oxygen is further removed by oxidation reaction and the oxygen content is controlled at 1 ppm, thereby obtaining a second intermediate melt. Step S4: The second intermediate melt is transferred to a holding furnace in a sealed environment at a temperature of 1180°C, and then further refined by blowing argon through the bottom of the holding furnace through ventilation bricks, with the argon dew point being -73°C, to obtain a qualified copper melt; Step S5: Passing the qualified copper melt through the pouring pipe for vertical full continuous casting, and controlling the cooling water flow in the secondary cooling zone to 740 L / min to obtain a copper ingot; Step S6: The copper ingot is heated and kept warm in a walking beam heating furnace at a heating temperature of 800°C for a holding time of 5 h, and then rolled on a hot rolling mill for 12 passes, with 11 passes being hot rolled on the hot rolling mill, and thickness processing rates being 9%→12.00%→15%→17%→20%→20%→24%→22%→21%→19%→10.00%, respectively. The plate is then water-cooled, with the plate temperature after water cooling being 48°C. The plate is then cold-rolled for the 12th pass on the hot rolling mill, with a thickness deformation of 8% in the 12th pass. Finally, degreasing, cleaning, and drying are performed to obtain a finished ultra-low oxygen content pure copper thick plate with a thickness of 24 mm.

[0041] The ultra-low oxygen content pure copper thick plate obtained in this example was subjected to performance testing, and the test results are shown in Table 2. Example 4

[0042] The present embodiment provides a pure copper thick plate with ultra-low oxygen content for magnetron sputtering coating. The composition of the pure copper thick plate with ultra-low oxygen content for magnetron sputtering coating, calculated by weight percentage, is shown in Table 1.

[0043] This embodiment provides a method for preparing a thick pure copper plate with ultra-low oxygen content for magnetron sputtering coating, comprising the following steps: Step S1: baking a high-purity cathode copper plate with a copper content of 99.9936% at 440°C for 115 seconds; Step S2: adding the baked high-purity cathode copper plate to a smelting furnace for smelting, bottom blowing oxygen during the smelting process, and controlling the oxygen content after oxygenation to 450 ppm. Impurity elements and hydrogen in the copper liquid are removed by oxygen suppression and oxidation to obtain a first intermediate melt; Step S3: The first intermediate melt is covered with charcoal and deoxygenated by bottom blowing carbon monoxide. After the charcoal covering and bottom blowing of carbon monoxide, the oxygen content is controlled at 12 ppm. Then, a CuP master alloy is added for deoxidation. When the oxygen content is controlled at 5 ppm, a CuMg master alloy is added. The oxygen is further removed by oxidation reaction and the oxygen content is controlled at 2 ppm, thereby obtaining a second intermediate melt. Step S4: The second intermediate melt is transferred to a holding furnace in a sealed environment at a temperature of 1170°C, and then further refined by blowing argon through the bottom of the holding furnace through ventilation bricks, with the argon dew point being -74°C, to obtain a qualified copper melt; Step S5: Passing the qualified copper melt through the pouring pipe for vertical full continuous casting, and controlling the cooling water flow in the secondary cooling zone to 780 L / min to obtain a copper ingot; Step S6: The copper ingot is heated and kept warm in a walking beam heating furnace at a heating temperature of 780°C for a holding time of 5.5 h, and then rolled on a hot rolling mill for 12 passes, with 11 passes being hot rolled on the hot rolling mill, and thickness processing rates being 9%→12.00%→15%→17%→20%→20%→24%→22%→21%→19%→10.00%, respectively. The plate is then water-cooled, with the plate temperature after water cooling being 48°C. The plate is then cold-rolled for the 12th pass on the hot rolling mill, with a thickness deformation of 8% in the 12th pass. Finally, degreasing, cleaning, and drying are performed to obtain a finished ultra-low oxygen content pure copper thick plate with a thickness of 24 mm.

[0044] The ultra-low oxygen content pure copper thick plate obtained in this example was subjected to performance testing. The results of the performance testing are shown in Table 2.

[0045] Comparative Example 1 The ultra-low oxygen content pure copper thick plate for magnetron sputtering coating of this comparative example has a composition, by weight percentage, of the ultra-low oxygen content pure copper thick plate for magnetron sputtering coating as shown in Table 1.

[0046] This comparative example provides a method for preparing a thick pure copper plate with ultra-low oxygen content for magnetron sputtering coating, comprising the following steps: Step S1: baking a high-purity cathode copper plate with a copper content of 99.98% at 350°C for 115 seconds; Step S2: adding the baked high-purity cathode copper plate to a smelting furnace for smelting, bottom blowing oxygen during the smelting process, and controlling the oxygen content after oxygenation to 300 ppm. Impurity elements and hydrogen in the copper liquid are removed by oxygen suppression and oxidation to obtain a first intermediate melt; Step S3: The first intermediate melt is covered with charcoal and deoxygenated by bottom blowing carbon monoxide. After the charcoal covering and bottom blowing of carbon monoxide, the oxygen content is controlled at 25 ppm. Then, a CuP master alloy is added for deoxidation. When the oxygen content is controlled at 5 ppm, a CuMg master alloy is added. The oxygen is further removed by oxidation reaction and the oxygen content is controlled at 2 ppm, thereby obtaining a second intermediate melt. Step S4: The second intermediate melt is transferred to a holding furnace in a sealed environment at a temperature of 1120°C, and then further refined by blowing argon through the bottom of the holding furnace through ventilation bricks, with a dew point of -60°C, to obtain a qualified copper melt; Step S5: Passing the qualified copper melt through the pouring pipe for vertical full continuous casting, and controlling the cooling water flow in the secondary cooling zone to 650 L / min to obtain a copper ingot; Step S6: The copper ingot is heated and kept warm in a walking beam heating furnace at a heating temperature of 700°C for a holding time of 6 h, and then rolled on a hot rolling mill for 12 passes, with 11 passes being hot rolled on the hot rolling mill, and thickness processing rates being 9%→12.00%→15%→17%→20%→20%→24%→22%→21%→19%→10.00%, respectively. The plate is then water-cooled, with the plate temperature after water cooling being 200°C. The plate is then cold-rolled for the 12th pass on the hot rolling mill, with a thickness deformation of 8% in the 12th pass. Finally, degreasing, cleaning, and drying are performed to obtain a finished ultra-low oxygen content pure copper thick plate with a thickness of 24 mm.

[0047] The ultra-low oxygen content pure copper thick plate obtained in this embodiment was subjected to metallographic examination and performance test. The metallographic examination diagram is shown in the attached Figure 2 ,It can be seen from the figure that the grain size distribution is uniform, and the average size is about 200 μm. ,The results of the performance test are shown in Table 2.

[0048] Comparative Example 2 The ultra-low oxygen content pure copper thick plate for magnetron sputtering coating of this comparative example has a composition, by weight percentage, of the ultra-low oxygen content pure copper thick plate for magnetron sputtering coating as shown in Table 1.

[0049] This comparative example provides a method for preparing a thick pure copper plate with ultra-low oxygen content for magnetron sputtering coating, comprising the following steps: Step S1: baking a high-purity cathode copper plate with a copper content of 99.99% at 500°C for 100 seconds; Step S2: adding the baked high-purity cathode copper plate to a smelting furnace for smelting, bottom blowing oxygen during the smelting process, and controlling the oxygen content after oxygenation to 700 ppm. Impurity elements and hydrogen in the copper liquid are removed by oxygen suppression and oxidation to obtain a first intermediate melt; Step S3: The first intermediate melt is covered with charcoal and deoxygenated by bottom blowing carbon monoxide. After the charcoal covering and bottom blowing of carbon monoxide, the oxygen content is controlled at 10 ppm. Then, a CuP master alloy is added for deoxidation. When the oxygen content is controlled at 5 ppm, a CuMg master alloy is added. The oxygen is further removed by oxidation reaction and the oxygen content is controlled at 2 ppm, thereby obtaining a second intermediate melt. Step S4: The second intermediate melt is transferred to a holding furnace in a sealed environment at a temperature of 1250°C, and then further refined by blowing argon through the bottom of the holding furnace through ventilation bricks, with the argon dew point being -55°C, to obtain a qualified copper melt; Step S5: Passing the qualified copper melt through the pouring pipe for vertical full continuous casting, and controlling the cooling water flow in the secondary cooling zone to 800 L / min to obtain a copper ingot; Step S6: The copper ingot is heated and kept warm in a walking beam heating furnace at a heating temperature of 900°C for a holding time of 5 h, and then rolled on a hot rolling mill for 12 passes, with 11 passes being hot rolled on the hot rolling mill, and thickness processing rates being 9%→12.00%→15%→17%→20%→20%→24%→22%→21%→19%→10.00%, respectively. The plate is then water-cooled, with the plate temperature after water cooling being 200°C. The plate is then cold rolled for the 12th pass on the hot rolling mill, with a thickness deformation of 8% in the 12th pass. Finally, degreasing, cleaning, and drying are performed to obtain a finished ultra-low oxygen content pure copper thick plate with a thickness of 24 mm.

[0050] The ultra-low oxygen content pure copper thick plate obtained in this example was subjected to performance testing. The results of the performance testing are shown in Table 2.

[0051] Comparative Example 3 In this comparative example, a pure copper plate with ultra-low oxygen content for magnetron sputtering coating is prepared. The composition of the pure copper plate with ultra-low oxygen content for magnetron sputtering coating is the same as that of Example 1 in Table 1, with the difference that in this comparative example, a high-purity oxygen-free copper material is prepared by refining, deoxidation and high-temperature hot rolling processes. The specific steps are as follows: Step S1: placing a high-purity cathode copper plate with a copper content of 99.997% in a medium frequency melting furnace, controlling the oxygen content to less than 300 ppm, and melting at a temperature of 1150-1200°C under Ar or N2 protection; Step S2: adding 0.01-0.05 wt% of phosphorus as a deoxidizer into the smelting furnace, and performing electromagnetic stirring or mechanical stirring to ensure uniform distribution of the deoxidizer, and stirring for 10-20 minutes; Step S3: introducing a CO / H2 mixed gas with a volume ratio of 1:1 into the smelting furnace to react with residual oxygen to generate CO2 / H2O, and controlling the oxygen content to ≤50 ppm; Step S4: Casting the copper ingot into a round copper ingot under the protection of an inert gas, controlling the cooling rate to 5-10°C / s to avoid segregation, and controlling the oxygen content of the copper ingot to be ≤20 ppm; Step S5: After surface treatment, the round copper ingot is subjected to multiple hot rolling passes, with the initial rolling temperature controlled at 900-950°C, the single-pass reduction rate at 20-30%, the total deformation at ≥80%, the rolling speed at 0.5-2 m / s, and the final rolling temperature at ≥600°C. Finally, after annealing and surface finishing, a finished low-oxygen content pure copper thick plate is obtained.

[0052]

[0053] As can be seen from Table 1 above, the pure copper thick plates obtained in Examples 1-4 of the present invention have extremely high copper contents (≥99.997%) and extremely low oxygen contents (1-3 ppm). Through refining and specific chemical reactions, the contents of impurity elements such as iron and phosphorus are effectively controlled. The resulting pure copper thick plates have a hardness of 85-92 HV and an average grain size of 20-60 μm. In contrast, the copper thick plates prepared in Comparative Examples 1-2 have a copper content of only greater than 99.9%, and also have high contents of impurity elements such as oxygen, iron, and phosphorus. The resulting pure copper thick plates have unstable hardness, large grain size (a large grain size significantly affects the mechanical, physical, and processing properties of the pure copper thick plates), a large standard deviation, and lower electrical conductivity than Examples 1-4 of the present invention. The composition of the pure thick copper plate used in Comparative Example 3 is the same as that in Example 1, but the refining deoxidation and high-temperature hot rolling processes are adopted. It can be seen from the data in Table 1 that although the copper content of the added raw materials is relatively high, the oxygen content is relatively high due to the reasonable deoxidation control process after oxygenation. In addition, it can be seen from the data in Table 2 that due to the different control processes, although the conductivity of the pure copper thick plate is relatively high, the hardness is relatively low, the grain size is relatively large, and the structure is not uniform enough, which affects the application of the pure copper thick plate in sputtering targets.

[0054] The above is only a preferred embodiment of the present invention and does not limit the present invention. It should be pointed out that for ordinary technicians in this field, under the technical enlightenment provided by the present invention, other equivalent improvements can be made, all of which can achieve the purpose of the present invention and should be considered as the scope of protection of the present invention.

Claims

1. A thick plate of pure copper with ultra-low oxygen content for magnetron sputtering coating, characterized by: Calculated by weight percentage, the ultra-low oxygen content pure copper thick plate for magnetron sputtering coating has a Cu content of ≥99.997%, an O content of 1-3 ppm, a Fe content of ≤5 ppm, a P content of ≤5 ppm, and the remainder being unavoidable impurity elements.

2. The ultra-low oxygen content pure copper thick plate for magnetron sputtering coating according to claim 1, characterized in that: The ultra-low oxygen content pure copper thick plate for magnetron sputtering coating has a hardness of 85 to 95 HV and a grain size of 20 to 60 μm.

3. The method for preparing a thick plate of pure copper with ultra-low oxygen content for magnetron sputtering coating according to claim 1 or 2, characterized in that: The following steps are involved: Step S1: baking a high-purity cathode copper plate with a copper content of ≥99.9935%; Step S2: adding the baked high-purity cathode copper plate into a smelting furnace for smelting, and performing bottom blowing to increase oxygen during the smelting process, thereby removing impurity elements and hydrogen in the copper liquid by suppressing hydrogen with oxygen and oxidizing the hydrogen to obtain a first intermediate melt; Step S3: The first intermediate melt is covered with charcoal and deoxygenated by bottom blowing carbon monoxide, and then CuP and CuMg master alloys are added in sequence to further remove oxygen through oxidation reaction, and the oxygen content is controlled at 1-3 ppm to obtain a second intermediate melt; Step S4: transferring the second intermediate melt to a holding furnace in a sealed environment, and then further refining it by blowing argon through the bottom of the holding furnace ventilation bricks to obtain a qualified copper melt; Step S5: Passing the qualified copper melt through the pouring pipe for vertical full continuous casting, and controlling the cooling water volume in the secondary cooling zone to 720-780 L / min to obtain a copper ingot; Step S6: The copper ingot is heated and kept warm in a walking beam heating furnace, and then rolled on a hot rolling mill for 12 passes, followed by degreasing, cleaning and drying to obtain a finished ultra-low oxygen content pure copper thick plate.

4. The method for preparing a thick pure copper plate with ultra-low oxygen content for magnetron sputtering coating according to claim 3, characterized in that: In step S1, the baking temperature of the copper plate is 400-450° C., and the baking time is 100-150 s.

5. The method for preparing a thick pure copper plate with ultra-low oxygen content for magnetron sputtering coating according to claim 3, characterized in that: The oxygen content after oxygenation in step S2 is controlled to be 400-600 ppm.

6. The method for preparing a thick pure copper plate with ultra-low oxygen content for magnetron sputtering coating according to claim 3, characterized in that: In step S3, the oxygen content after charcoal covering and bottom blowing of carbon monoxide for deoxygenation is controlled at 10-20 ppm.

7. The method for preparing a thick pure copper plate with ultra-low oxygen content for magnetron sputtering coating according to claim 3, characterized in that: In step S4, the holding furnace temperature is 1150-1180°C, and the argon dew point is -70°C--74°C.

8. The method for preparing a thick pure copper plate with ultra-low oxygen content for magnetron sputtering coating according to claim 3, characterized in that: In step S6, the heating temperature of the walking beam furnace is 750-800° C., and the holding time is 5-6 h.

9. The method for preparing a thick pure copper plate with ultra-low oxygen content for magnetron sputtering coating according to claim 3, characterized in that: The 12-pass rolling in step S6 is performed by hot rolling on a hot rolling mill for 11 passes and immediately water cooling followed by one cold rolling pass.

10. The method for preparing a thick pure copper plate with ultra-low oxygen content for magnetron sputtering coating according to claim 9, characterized in that: The thickness processing rate of the 11-pass hot rolling process is 9%→12.00%→15%→17%→20%→20%→24%→22%→21%→19%→10.00%; the pass thickness deformation of the 12th pass is 6~8%, and the plate temperature after water cooling is ≤50°C.

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