High-purity copper sputtering target material and preparation method thereof

Abstract

The invention provides a high-purity copper sputtering target material and a preparation method thereof. The target material comprises the following components: 1-4 ppm of Fe, 1-2 ppm of P, 1-5 ppm of O, and the balance of Cu and inevitable impurity elements. The target material is prepared through the following steps that S1, an electrolytic copper blank is prepared; s2, the blank is covered with charcoal, melting and heat preservation are conducted, and copper liquid is prepared; s3, the molten copper is subjected to semi-continuous casting, and a semi-continuous cast ingot is obtained; and S4, after heating, a hot rolling process and subsequent treatment are carried out, and the high-purity copper sputtering target material is obtained. According to the method, the oxygen content is controlled to be 5 ppm or below, the casting temperature, the casting speed, the cooling water amount, the heating temperature, rolling pass deformation, key pass deformation and the like are cooperatively controlled, the purity of the sputtering target material is ensured, a casting blank which is loose inside and few in shrinkage cavities is obtained, the sputtering target material which is fine and uniform in structure and moderate in hardness is obtained, and the quality of the sputtering target material is improved. Therefore, the requirements in the fields of integrated circuits, information storage, liquid crystal display screens, laser memories, electronic control devices and the like are met.

Description

Technical Field

[0001] The invention relates to the technical field of copper material processing, and in particular to a high-purity copper sputtering target material and a preparation method thereof. Background Art

[0002] High-purity copper sputtering target is a key electronic material, widely used in integrated circuits, information storage, liquid crystal displays, laser storage, electronic control devices and other fields. Especially in integrated circuit manufacturing, high-purity copper sputtering target plays an important role in the metallization process, and its quality and performance are crucial to integrated circuit manufacturing and other high-tech industries. With the development of integrated circuit technology, higher requirements are placed on the purity and microstructure control of high-purity copper sputtering targets. In addition to its application in the semiconductor field, high-purity copper sputtering targets are also used in the field of glass coating and wear-resistant materials, high-temperature corrosion resistance, high-end decorative products and other industries. With the continuous expansion of the scale of related industries, the demand for high-purity metal and alloy sputtering targets is also increasing.

[0003] In the integrated circuit manufacturing industry, high-purity copper sputtering targets are mainly used to make interconnects, barrier layers, through holes, contact layers, metal gates, and thin films such as wetting layers, bonding layers, and antioxidant layers. The application of these materials plays a vital role in the performance and reliability of integrated circuits. With the continuous advancement and development of electronic information industry technology, the requirements for the purity, microstructure, and performance of high-purity copper sputtering targets are also constantly increasing. However, in the process of preparing high-purity copper sputtering targets in the prior art, there are problems such as excessive grain size, uneven tissue distribution, excessive impurity content, excessive oxygen content, and the inability to stably control hardness, which seriously affects the subsequent performance of the high-purity copper sputtering target.

[0004] Therefore, there is an urgent need to develop a high-purity copper sputtering target and a preparation method thereof to solve the problems existing in the existing basis. Summary of the invention

[0005] In view of this, the present invention proposes a high-purity copper sputtering target and a preparation method thereof, so as to prepare a high-purity copper sputtering target with uniform and fine grain structure, high purity and uniform hardness and high yield.

[0006] On the one hand, the present invention provides a high-purity copper sputtering target, which comprises the following components by mass content: Fe 1-4ppm, P 1-2ppm, O 1-5ppm, and the remainder is Cu and unavoidable impurity elements; the target has a thickness of 10-30mm, a Vickers hardness of 90-100Hv, and no pore defects with an average diameter of more than 0.3mm are present inside the target under water immersion ultrasonic detection.

[0007] By adopting the above technical scheme, firstly, iron, phosphorus and oxygen are the main impurity elements in the sputtering target. When the content of iron, phosphorus and oxygen is too high, it will not only lead to a decrease in the purity of the film, affecting the electrical, optical and mechanical properties of the target, but also increase the resistivity of the sputtering coating and reduce the transmittance. The problems will lead to increased defects and roughness on the surface of the film, affecting the performance and quality of the final integrated circuit product; on the contrary, when the content of iron, phosphorus and oxygen is too low, the preparation cost of the target will increase, and the mechanical properties and sputtering performance of the target will also be affected; therefore, controlling the content of each component in the target within the scope of this application can not only ensure the stability during the sputtering coating process, but also improve the quality and performance of the film and reduce production costs.

[0008] Secondly, the present application controls the thickness of the sputtering target between 10 and 30 mm, which can make the target more stable during the sputtering process, help maintain a uniform sputtering rate, and effectively control the thickness of the deposited film. The thickness of the target material in the present application can provide a longer sputtering time within the same time, reduce the frequency of target replacement, thereby reducing costs and improving production efficiency, thereby effectively avoiding the burden and energy consumption on production equipment caused by excessively thick targets.

[0009] Furthermore, the present application controls the Vickers hardness of the sputtering target material to between 90 and 100 Hv, which not only enables the target material to always maintain good stability and durability during the sputtering process, but also can resist erosion and wear during the sputtering process, maintain the flatness and uniformity of the target surface, thereby improving the quality and uniformity of the sputtered film, and laying the foundation for the excellent performance and reliability of the integrated circuit.

[0010] Finally, the present invention shows that there are no pore defects with an average diameter of more than 0.3 mm inside the target material under water immersion ultrasonic testing, which means that the material has a higher density and a more uniform structure, which helps to improve the overall quality of the sputtering target.

[0011] Furthermore, the average grain size of the target material is 20-40 μm.

[0012] On the basis of the above technical solution, further, the standard deviation of the average grain size of the target material does not exceed 4 μm and is normally distributed.

[0013] By adopting the above technical solution, the sputtering rate and film quality of the target material can be significantly improved, and the production cost can be reduced; at the same time, it helps to reduce the wear on the target surface, thereby extending the service life of the target material.

[0014] On the other hand, the present application also relates to a method for preparing the above-mentioned high-purity copper sputtering target, comprising the following steps:

[0015] S1, preheating the electrolytic copper raw material, cooling it, and obtaining an electrolytic copper billet;

[0016] S2, using charcoal to cover the electrolytic copper billet in S1, heating it until it is melted, and keeping it warm to obtain copper liquid;

[0017] S3, semi-continuously casting the copper liquid in S2 to obtain a semi-continuous ingot;

[0018] S4. After heating the semi-continuous ingot of S3, hot rolling, quenching and cold rolling are sequentially performed to obtain a high-purity copper sputtering target.

[0019] By adopting the above technical scheme, with the coordinated cooperation of preheating in S1 and smelting and heat preservation process in S2, the oxygen content is controlled below 5ppm, ensuring the purity of the sputtering target. In the semi-continuous casting process of S3, by coordinated control of casting temperature, casting speed and cooling water volume, a casting with loose interior and few shrinkage cavities is obtained. By effectively regulating the heating temperature, rolling pass and deformation amount of key passes in S4, a sputtering target with fine, uniform structure and moderate hardness is obtained, thus meeting the needs of integrated circuits, information storage, liquid crystal displays, laser memory, electronic control devices and other fields.

[0020] Furthermore, in S1, the preheating temperature is 300-400°C, the temperature is cooled to 90-100°C, and the purity of the electrolytic copper billet is not less than 99.99%.

[0021] By adopting the above technical solutions, not only can the pollutants on the copper surface (including sludge, oil and water stains) be removed and internal stress reduced, but also the sputtering efficiency and durability can be improved. In addition, high-purity copper targets not only help improve the quality and physical properties of the film, but also extend the service life of the targets and meet the application needs of high-end fields.

[0022] Furthermore, in S2, the charcoal covering thickness is 150-250 mm, and the insulation temperature is 1200-1230°C.

[0023] By adopting the above technical solution, the air can be isolated to a certain extent, and the oxidation of the surface of the electrolytic copper billet can be reduced, thereby maintaining the purity and performance of the copper material.

[0024] Furthermore, in S3, the temperature of the semi-continuous casting is 1160-1180°C, the speed is 60-70 mm / min, the cooling water volume for the large casting surface is 630-700 L / min, and the cooling water volume for the small casting surface is 420-440 L / min.

[0025] Furthermore, in S4, the heating temperature is 800-830°C, and the heating time is 260-280 min; the temperature of the ingot after quenching is 40-50°C.

[0026] Furthermore, in S4, the hot rolling passes are 11 to 12 passes, and the cold rolling passes are 1 to 2 passes.

[0027] By adopting the above technical solution, not only the microstructure of the target material can be optimized and the performance of the target material can be improved, but also the processing accuracy and yield rate of the target material can be improved, which is helpful to prepare high-quality and high-performance sputtering targets to meet the needs of various application scenarios.

[0028] On the basis of the above technical solution, further, in the hot rolling passes, the deformation amount of the 8th pass is 28-35%, and the deformation amount of the 9th pass is 30-36%.

[0029] On the basis of the above technical solution, further, the total deformation of the cold rolling pass is 5-9%. By adopting the above technical solution, the deformation of the key pass in the hot rolling process and the total deformation of the pass in the cold rolling process are set, which can ensure that the target material maintains stable deformation performance during the rolling process, thereby further improving the processing accuracy and yield rate of the target material.

[0030] In the present invention, the ingot is first hot-rolled and then cold-rolled. The hot-rolled blanking process can better weld the fine defects of the ingot, thereby obtaining a denser structure, and the hot rolling process can also eliminate the coarse structure of the ingot, laying the foundation for obtaining a fine structure. At the same time, the size of the structure can be further controlled by quenching, and then cold rolling is performed to shape the shape, which can not only control the processing accuracy (such as flatness, smoothness, etc.), but also regulate the hardness of the final product by cold rolling deformation. If only hot rolling is performed, the subsequent grain size, processing accuracy, flatness, etc. cannot be controlled. If only cold rolling is performed, the process will become complicated, increase energy consumption, and be unfavorable for eliminating casting structures and welding fine defects. In addition, the purpose of quenching is to control the size of the structure, remove the oxide scale in the hot rolling process, and facilitate the subsequent cold rolling due to the oxide scale being pressed into the surface defects, thereby increasing the amount of milling and increasing the defects, and also reducing the yield rate of the strip.

[0031] The high-purity copper sputtering target provided by the present invention has the following beneficial effects compared with the prior art:

[0032] The present invention controls the contents of Fe, P, O, etc. in the pure copper sputtering plate within a specific range, and selects the purity of the electrolytic copper, baking, smelting and heat preservation process optimization, so as to control the oxygen content below 5ppm, thereby ensuring the purity of the sputtering target. By synergistically controlling the casting temperature, casting speed and cooling water volume, a casting blank with loose interior and few shrinkage cavities is obtained. By controlling the heating temperature and the deformation of the rolling passes and key passes, a sputtering target with fine, uniform structure and moderate hardness is obtained, thereby meeting the needs of integrated circuits, information storage, liquid crystal displays, laser memory, electronic control devices and other fields. Compared with the prior art, this method has the characteristics of stable target hardness, uniform and fine structure and low impurity content. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0034] Figure 1 This is a metallographic structure photograph of the high-purity copper sputtering target prepared in Example 3 of the present invention;

[0035] Figure 2 This is a product picture of the high-purity copper sputtering target prepared in Example 3 of the present invention. DETAILED DESCRIPTION

[0036] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0037] The present invention is further described below in conjunction with specific examples, and the protection scope of the present invention is not limited by the following examples. The sources of materials mainly involved in the examples are all conventional commercial products.

[0038] Example 1

[0039] The high-purity copper sputtering target of this embodiment is prepared by the following steps:

[0040] S1, preheating the electrolytic copper raw material to 300° C., and then cooling to 90° C. to obtain an electrolytic copper billet;

[0041] S2, using charcoal with a thickness of 180 mm to cover the electrolytic copper billet of S1, heating the billet until it is completely melted, and then keeping the copper liquid at 1230°C;

[0042] S3, semi-continuously casting the copper liquid of S2 at a speed of 60 mm / min at 1180° C., setting the cooling water volume of the large casting surface to 630 L / min, and the cooling water volume of the small casting surface to 420 L / min, to obtain a semi-continuous ingot;

[0043] S4, heating the semi-continuous ingot of S3 at 800°C for 280min, and then sequentially performing hot rolling-quenching-cold rolling to obtain a high-purity copper sputtering target;

[0044] Among them, in S1, the electrolytic copper raw materials are selected from materials with clean surfaces and no sludge and oil stains; in S4, there are 11 hot rolling passes, the deformation amounts of the 8th and 9th passes are 35% and 30% respectively, the temperature of the target material billet after quenching is 40°C, there is 1 cold rolling pass, and the total deformation amount of the cold rolling passes is 7%.

[0045] The mass contents of Fe, P and O in the high-purity copper sputtering target prepared in this embodiment are shown in Table 1 below.

[0046] Example 2

[0047] The high-purity copper sputtering target of this embodiment is prepared by the following steps:

[0048] S1, preheating the electrolytic copper raw material to 400° C., and then cooling to 100° C. to obtain an electrolytic copper billet;

[0049] S2, using charcoal with a thickness of 150 mm to cover the electrolytic copper billet of S1, heating the billet until it is completely melted, and then keeping the copper liquid at 1210°C;

[0050] S3, semi-continuously casting the copper liquid of S2 at a speed of 65 mm / min at 1170°C, setting the cooling water volume of the large casting surface to 650 L / min, and the cooling water volume of the small casting surface to 425 L / min, to obtain a semi-continuous ingot;

[0051] S4, heating the semi-continuous ingot of S3 at 810°C for 275min, and then sequentially performing hot rolling-quenching-cold rolling to obtain a high-purity copper sputtering target;

[0052] Among them, in S1, the electrolytic copper raw materials are selected from materials with clean surfaces and no sludge and oil stains; in S4, there are 11 hot rolling passes, the deformation amounts of the 8th and 9th passes are 32% and 32% respectively, the temperature of the target material billet after quenching is 50°C, there are 2 cold rolling passes, and the total deformation amount of the cold rolling passes is 5%.

[0053] The mass contents of Fe, P and O in the high-purity copper sputtering target prepared in this embodiment are shown in Table 1 below.

[0054] Example 3

[0055] The high-purity copper sputtering target of this embodiment is prepared by the following steps:

[0056] S1, preheating the electrolytic copper raw material to 380° C., and cooling it to 95° C. to obtain an electrolytic copper billet;

[0057] S2, using charcoal with a thickness of 250 mm to cover the electrolytic copper billet of S1, heating the billet until it is completely melted, and then keeping the copper liquid at 1220°C;

[0058] S3, semi-continuously casting the copper liquid of S2 at a speed of 68 mm / min at 1160° C., setting the cooling water volume of the large casting surface to 680 L / min and the cooling water volume of the small casting surface to 430 L / min, to obtain a semi-continuous ingot;

[0059] S4, heating the semi-continuous ingot of S3 at 830°C for 260min, and then sequentially performing hot rolling-quenching-cold rolling to obtain a high-purity copper sputtering target;

[0060] Among them, in S1, the electrolytic copper raw materials are selected from materials with clean surfaces and no sludge and oil stains; in S4, there are 11 hot rolling passes, the deformation amounts of the 8th and 9th passes are 30% and 34% respectively, the temperature of the target material billet after quenching is 45°C, there is 1 cold rolling pass, and the total deformation amount of the cold rolling passes is 9%.

[0061] The mass contents of Fe, P and O in the high-purity copper sputtering target prepared in this embodiment are shown in Table 1 below.

[0062] Example 4

[0063] The high-purity copper sputtering target of this embodiment is prepared by the following steps:

[0064] S1, preheating the electrolytic copper raw material to 350° C., and cooling it to 90° C. to obtain an electrolytic copper billet;

[0065] S2, using charcoal with a thickness of 220 mm to cover the electrolytic copper billet of S1, heating the billet until it is completely melted, and then keeping the copper liquid at 1200°C;

[0066] S3, semi-continuously casting the copper liquid of S2 at a speed of 70 mm / min at 1170° C., setting the cooling water volume of the large casting surface to 700 L / min and the cooling water volume of the small casting surface to 440 L / min, to obtain a semi-continuous ingot;

[0067] S4, heating the semi-continuous ingot of S3 at 820°C for 270min, and then sequentially performing hot rolling-quenching-cold rolling to obtain a high-purity copper sputtering target;

[0068] Among them, in S1, the electrolytic copper raw materials are selected from materials with clean surfaces and no sludge and oil stains; in S4, there are 11 hot rolling passes, the deformation amounts of the 8th and 9th passes are 28% and 36% respectively, the temperature of the target material billet after quenching is 45°C, there are 2 cold rolling passes, and the total deformation amount of the cold rolling passes is 8%.

[0069] The mass contents of Fe, P and O in the high-purity copper sputtering target prepared in this embodiment are shown in Table 1 below.

[0070] Example 5

[0071] The high-purity copper sputtering target of this embodiment is prepared by the following steps:

[0072] S1, preheating the electrolytic copper raw material to 300° C., and then cooling to 90° C. to obtain an electrolytic copper billet;

[0073] S2, using charcoal with a thickness of 200 mm to cover the electrolytic copper billet of S1, heating the billet until it is completely melted, and then keeping the copper liquid at 1200°C;

[0074] S3, semi-continuously casting the copper liquid of S2 at a speed of 60 mm / min at 1160° C., setting the cooling water volume of the large casting surface to 660 L / min, and the cooling water volume of the small casting surface to 430 L / min, to obtain a semi-continuous ingot;

[0075] S4, heating the semi-continuous ingot of S3 at 810°C for 260min, and then sequentially performing hot rolling-quenching-cold rolling to obtain a high-purity copper sputtering target;

[0076] Among them, in S1, the electrolytic copper raw materials are selected from materials with clean surfaces and no sludge and oil stains; in S4, there are 12 hot rolling passes, the deformation amounts of the 8th and 9th passes are 28% and 30% respectively, the temperature of the target material billet after quenching is 40°C, there is 1 cold rolling pass, and the total deformation amount of the cold rolling passes is 6%.

[0077] The mass contents of Fe, P and O in the high-purity copper sputtering target prepared in this embodiment are shown in Table 1 below.

[0078] Example 6

[0079] The high-purity copper sputtering target of this embodiment is prepared by the following steps:

[0080] S1, preheating the electrolytic copper raw material to 400° C., and then cooling to 100° C. to obtain an electrolytic copper billet;

[0081] S2, using charcoal with a thickness of 230 mm to cover the electrolytic copper billet of S1, heating the billet until it is completely melted, and then keeping the copper liquid at 1230°C;

[0082] S3, semi-continuously casting the copper liquid of S2 at a speed of 70 mm / min at 1180° C., setting the cooling water volume of the large casting surface to 700 L / min and the cooling water volume of the small casting surface to 440 L / min, to obtain a semi-continuous ingot;

[0083] S4, heating the semi-continuous ingot of S3 at 800°C for 280min, and then sequentially performing hot rolling-quenching-cold rolling to obtain a high-purity copper sputtering target;

[0084] Among them, in S1, the electrolytic copper raw materials are selected from materials with clean surfaces and no sludge and oil stains; in S4, there are 12 hot rolling passes, the deformation amounts of the 8th and 9th passes are 35% and 36% respectively, the temperature of the target material billet after quenching is 50°C, there are 2 cold rolling passes, and the total deformation amount of the cold rolling passes is 7%.

[0085] The mass contents of Fe, P and O in the high-purity copper sputtering target prepared in this embodiment are shown in Table 1 below.

[0086] Comparative Example 1

[0087] The difference from Example 1 is that S1 is not included, and the other steps remain unchanged. The mass contents of Fe, P, and O in the high-purity copper sputtering target prepared in this comparative example are shown in Table 1 below.

[0088] Comparative Example 2

[0089] The difference from Example 2 is that in S2, charcoal is not used to cover the electrolytic copper blank of S1; the other steps remain unchanged. The mass contents of Fe, P, and O in the high-purity copper sputtering target prepared in this comparative example are shown in Table 1 below.

[0090] Comparative Example 3

[0091] The difference from Example 3 is that in S4, the hot rolling is performed for 10 passes, and the deformation amounts of the 8th and 9th passes are 27% and 29% respectively; the other steps remain unchanged. The mass contents of Fe, P, and O in the high-purity copper sputtering target prepared in this comparative example are shown in Table 1 below.

[0092] Comparative Example 4

[0093] The difference from Example 4 is that in S4, the cold rolling is performed for 3 passes, and the total deformation is 10%; the other steps remain unchanged. The mass contents of Fe, P, and O in the high-purity copper sputtering target prepared in this comparative example are shown in Table 1 below.

[0094] Comparative Example 5

[0095] The difference from Example 5 is that in S4, 12 hot rolling passes are provided, the deformation amounts of the 8th and 9th passes are 36% and 37% respectively, and 1 cold rolling pass is provided, and the total deformation amount is 4%; the other steps remain unchanged. The mass contents of Fe, P, and O in the high-purity copper sputtering target prepared in this comparative example are shown in Table 1 below.

[0096] Comparative Example 6

[0097] The difference from Example 6 is that in S4, after the quenching treatment, the temperature of the target blank is 80° C. The mass contents of Fe, P and O in the high-purity copper sputtering target prepared in this comparative example are shown in Table 1 below.

[0098] Comparative Example 7

[0099] The high-purity copper sputtering target of this comparative example is prepared by the following steps:

[0100] S1, preheating the electrolytic copper raw material to 500° C., and then cooling to 50° C. to obtain an electrolytic copper billet;

[0101] S2, using charcoal with a thickness of 100 mm to cover the electrolytic copper billet of S1, heating the billet until it is completely melted, and then keeping the copper liquid at 1150°C;

[0102] S3, semi-continuously casting the copper liquid of S2 at a speed of 80 mm / min at 1200° C., setting the cooling water volume of the large casting surface to 600 L / min and the cooling water volume of the small casting surface to 400 L / min, to obtain a semi-continuous ingot;

[0103] S4, heating the semi-continuous ingot of S3 at 750°C for 250 minutes, and then sequentially performing hot rolling-quenching-cold rolling to obtain a high-purity copper sputtering target;

[0104] Among them, in S1, the electrolytic copper raw materials are selected from materials with clean surfaces and no sludge and oil stains; in S4, there are 12 hot rolling passes, the deformation amounts of the 8th and 9th passes are 25% and 40% respectively, the ingot temperature after quenching is 80°C, there are 2 cold rolling passes, and the total deformation amount of the cold rolling passes is 12%.

[0105] The mass contents of Fe, P and O in the high-purity copper sputtering target prepared in this comparative example are shown in Table 1 below.

[0106] Comparative Example 8

[0107] The high-purity copper sputtering target of this comparative example is prepared by the following steps:

[0108] S1, preheating the electrolytic copper raw material to 200° C., and then cooling to 150° C. to obtain an electrolytic copper billet;

[0109] S2, using charcoal with a thickness of 300 mm to cover the electrolytic copper billet of S1, heating the billet until it is completely melted, and then keeping the copper liquid at 1250°C;

[0110] S3, semi-continuously casting the copper liquid of S2 at a speed of 50 mm / min at 1120° C., setting the cooling water volume of the large casting surface to 750 L / min, and the cooling water volume of the small casting surface to 500 L / min, to obtain a semi-continuous ingot;

[0111] S4, heating the semi-continuous ingot of S3 at 900°C for 300 minutes, and then sequentially performing hot rolling-quenching-cold rolling to obtain a high-purity copper sputtering target;

[0112] Among them, in S1, the electrolytic copper raw materials are selected from materials with clean surfaces and no sludge and oil stains; in S4, there are 12 hot rolling passes, the deformation amounts of the 8th and 9th passes are 38% and 28% respectively, the ingot temperature after quenching is 100°C, there is 1 cold rolling pass, and the total deformation amount of the cold rolling passes is 20%.

[0113] The mass contents of Fe, P and O in the high-purity copper sputtering target prepared in this comparative example are shown in Table 1 below.

[0114] Table 1 Mass contents of Fe, P and O in high purity copper sputtering targets prepared in Examples and Comparative Examples

[0115]

[0116]

[0117] The inventors conducted the following performance tests on the above-mentioned Examples 1 to 6 and Comparative Examples 1 to 7, including:

[0118] 1) Average grain size

[0119] The average grain size is measured according to the national standard GB / T 6394.

[0120] 2) Horizontal plane vertical angle

[0121] The horizontal plane squareness of the finished material is measured by a KEYENCE high-precision laser online measuring instrument.

[0122] 3) Number of defects larger than 0.3 mm

[0123] The number of defects with a size of 0.1 μm or larger is measured using an ultrasonic water immersion flaw detection system.

[0124] 4) Vickers hardness

[0125] The Vickers hardness of copper is measured according to the national standard GBT4340.

[0126] The above performance test results are recorded in Table 2 below.

[0127] Table 2 Performance test results of embodiments and comparative examples

[0128]

[0129] From the performance test results in Table 2, it can be concluded that:

[0130] (1) The grain size of the sputtering target prepared in this embodiment is between 20 and 40 μm, and the standard deviation is small, indicating that the target material prepared by the present invention has a uniform grain size; while the grain size of the comparative example is larger and more widely distributed. From this, it can be seen that the change in grain size is mainly affected by the ingot structure and the hot rolling process, including factors such as heating temperature, final rolling temperature, holding time and cooling rate. In the embodiment, by controlling the heating temperature, holding time and cooling rate, the grains can be effectively refined and the consistency and performance of the material can be improved. In the comparative example, due to the lack of certain steps or improper hot rolling process parameters (such as too low or too high holding temperature), the grains grow and the grain size distribution is uneven.

[0131] (2) The sputtering target prepared in this embodiment has a better horizontal plane perpendicularity, which means that the surface of the material is smoother. This is due to different cooling conditions during the casting process. The embodiment precisely controls the amount of cooling water for the large and small surfaces of the casting, so that the stress distribution of the material during the cooling process is more uniform, thereby reducing deformation. However, due to changes in cooling conditions (such as different amounts of cooling water) in the comparative example, the material may generate greater internal stress during the solidification process, thereby affecting the flatness of the material.

[0132] (3) The sputtering target prepared in this embodiment does not have pore defects larger than 0.3 mm. This is because charcoal covering is used in the embodiment to reduce the introduction of oxides and other impurities. At the same time, the stress distribution inside the material is controlled by a strict hot rolling process, reducing the formation of defects such as cracks. However, due to the lack of charcoal covering or improper control of hot rolling process parameters, the material in the comparative example is more likely to absorb impurities or crack at high temperature.

[0133] (4) The Vickers hardness of the sputtering target prepared in this embodiment is moderate, while the hardness of the comparative example fluctuates greatly. This is because the embodiment obtains a relatively ideal microstructure through appropriate rolling processes (such as hot rolling, quenching, and cold rolling), so that the material has sufficient hardness but is not too hard to increase brittleness. However, due to the different hot rolling processes, the hardness of the comparative example fluctuates. Too high a hardness may make the material brittle, while too low a hardness will affect the wear resistance and service life.

[0134] The inventors take Example 3 as an example and observe the metallographic structure of the final target material through a metallographic microscope. Figure 1 As shown in the photo, it can be seen that the grains are small and uniform, showing a uniform distribution state, which can meet the needs of sputtering targets. Figure 2 As can be seen from the figure, the finished sputtering target prepared in this embodiment has a large size, good flatness, and a small horizontal right angle, which well meets the needs of large-size sputtering targets.

[0135] In summary, the embodiment shows better performance in terms of grain size control, material flatness, defect control and hardness compared to the comparative example. This is mainly because the embodiment effectively improves the microstructure and mechanical properties of the material by strictly controlling the key parameters in the processing technology (such as temperature, cooling rate, hot rolling process, etc.). However, the comparative example has a decrease in material performance due to the lack of certain process steps or improper parameter adjustment. The synergistic effect between the content of each element, the operating steps and the parameters controlled by the embodiments of the present invention can meet the requirements of copper materials for high-purity copper sputtering targets, not only can a relatively uniform and fine grain size be obtained, but the hardness also meets the needs of sputtering targets, and in addition, it has a relatively excellent flatness, which meets its application requirements in high-end fields such as integrated circuits, information storage, liquid crystal displays, laser memory, and electronic control devices.

[0136] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A high-purity copper sputtering target, characterized in that: The target material comprises the following components by mass content: Fe 1-4 ppm, P 1-2 ppm, O 1-5 ppm, and the remainder is Cu and unavoidable impurity elements; The target material has a thickness of 10 to 30 mm and a Vickers hardness of 90 to 100 Hv. Under water immersion ultrasonic testing, there is no pore defect with an average diameter of more than 0.3 mm inside the target material.

2. The high-purity copper sputtering target according to claim 1, characterized in that: The average grain size of the target material is 20-40 μm; the standard deviation of the average grain size of the target material does not exceed 4 μm and is normally distributed.

3. A method for preparing a high-purity copper sputtering target as claimed in claim 1 or 2, characterized in that: The method comprises the following steps: S1, preheating the electrolytic copper raw material, cooling it, and obtaining an electrolytic copper billet; S2, using charcoal to cover the electrolytic copper billet in S1, heating it until it is melted, and keeping it warm to obtain copper liquid; S3, semi-continuously casting the copper liquid in S2 to obtain a semi-continuous ingot; S4. After heating the semi-continuous ingot of S3, hot rolling, quenching and cold rolling are sequentially performed to obtain a high-purity copper sputtering target.

4. The method according to claim 3, characterized in that In S1, the preheating temperature is 300-400°C, the temperature is cooled to 90-100°C, and the purity of the electrolytic copper billet is not less than 99.99%.

5. The method according to claim 3, characterized in that In S2, the charcoal covering thickness is 150-250 mm, and the insulation temperature is 1200-1230°C.

6. The method according to claim 3, characterized in that In S3, the temperature of the semi-continuous casting is 1160-1180°C, the speed is 60-70 mm / min, the cooling water volume for the large casting surface is 630-700 L / min, and the cooling water volume for the small casting surface is 420-440 L / min.

7. The method according to claim 3, characterized in that In S4, the heating temperature is 800-830°C, and the heating time is 260-280 min; the temperature of the ingot after quenching treatment is 40-50°C.

8. The method according to claim 3, characterized in that In S4, the hot rolling passes are 11 to 12 passes, and the cold rolling passes are 1 to 2 passes.

9. The method according to claim 8, characterized in that In the hot rolling passes, the deformation amount of the 8th pass is 28-35%, and the deformation amount of the 9th pass is 30-36%.

10. The method according to claim 8, characterized in that The total deformation of the cold rolling pass is 5-9%.

Images