A metal target and a method of manufacturing the same

Abstract

The application relates to the technical field of target material preparation, and provides a metal target material and a preparation method thereof, which comprises the following steps: heating and melting a metal raw material to form a melt; performing down-casting treatment on the melt to obtain a metal thin rod; performing continuous upsetting treatment on the metal thin rod with a deformation amount exceeding 400% to obtain a metal thick rod; performing continuous extrusion treatment on the metal thick rod to obtain a metal pipe; and performing heat treatment on the metal pipe, and then machining to obtain the metal target material. The preparation method of the metal target material provided by the application can prepare a high-purity and small metal rod by adopting the down-casting treatment on the melt, is beneficial to subsequent continuous upsetting to realize super-large deformation, effectively breaks large grains in the metal thin rod, obtains a metal thick rod with small and uniform grains, solves the problem that it is difficult to accurately control the grain uniformity when a large ingot is obtained through traditional smelting and casting and then is forged, avoids the influence of the intermittent multi-pass forging mode on the continuous production of the target material, and significantly improves the production efficiency.

Description

Technical Field

[0001] This application belongs to the field of target preparation technology, and particularly relates to a metal target and its preparation method. Background Technology

[0002] With the rapid development of high-tech industries such as semiconductors, display panels, and photovoltaic cells, the performance requirements for various thin-film materials are becoming increasingly stringent. Metal targets, as the core raw materials for thin film preparation, directly affect the quality of the final product. Among them, high-purity metal targets, such as copper, aluminum, gold, silver, indium, and tin targets, play an irreplaceable role in key areas such as microelectronic interconnection, packaging, transparent conductivity, optical reflection, and high-end decoration due to their unique physicochemical properties. For example, copper and aluminum targets are mainly used to prepare metal interconnect layers for semiconductor chips, utilizing their excellent conductivity to significantly reduce resistance, capacitance, and delay, thereby improving device processing speed and reliability. Silver and gold targets, with their excellent conductivity and chemical stability, are commonly used in high-reliability microelectronic packaging, high-frequency device electrodes, and high-end decorative coatings. Tin and indium targets are important raw materials for transparent conductive thin films, widely used in touchscreens, liquid crystal displays, and photovoltaic cells. For metal targets, properties such as grain size, orientation, purity, and oxygen content are particularly critical to ensure that the sputtered functional layers have excellent uniformity, low resistivity, and high reliability. Metal sputtering targets must meet stringent requirements such as fine grain size, high purity, and low oxygen content.

[0003] Currently, the preparation of metal sputtering targets generally adopts traditional plastic processing technology, which involves first obtaining a large ingot (typically several hundred millimeters in diameter) through melting and casting, then refining the grains through multiple forging processes, and finally processing it into the desired shape through deformation methods such as extrusion and rolling. However, this process has significant drawbacks: the large grains of the large ingots are prone to defects such as compositional segregation, shrinkage cavities, and oxide inclusions; subsequent forging requires repeated heating and processing, resulting in a lengthy process, high energy consumption, and difficulty in precisely controlling grain uniformity when forging from large ingots; moreover, the multiple intermittent processing also limits the continuity and efficiency of production, ultimately making it difficult to produce metal sputtering targets with low oxygen content and fine, uniform grains.

[0004] Therefore, in order to overcome the above-mentioned technical bottlenecks, it is urgent to develop a low-cost, efficient, and continuous method for preparing metal targets with low oxygen content and fine and uniform grains. Summary of the Invention

[0005] The purpose of this application is to provide a metal target and its preparation method, which aims to solve the problem that existing metal target preparation methods cannot produce low-oxygen content and fine and uniform grain metal targets at low cost and continuously.

[0006] To achieve the above-mentioned objectives, the technical solution adopted in this application is as follows:

[0007] In a first aspect, this application provides a method for preparing a metal target, comprising the following steps:

[0008] The metal raw material is heated and melted to form a melt;

[0009] The melt is subjected to continuous casting to obtain a thin metal rod.

[0010] The thin metal rod is subjected to continuous upsetting with a deformation exceeding 400% to obtain a thick metal rod;

[0011] The metal rod is continuously extruded to obtain a metal tube.

[0012] The metal tube is heat-treated and then machined to obtain a metal target.

[0013] Secondly, this application provides metal targets, including metal targets prepared by the method provided in this application.

[0014] Compared with the prior art, this application has the following beneficial effects:

[0015] (1) The use of bottom casting to process the melt can produce high-purity and fine metal rods, while also reducing oxygen content, increasing the density of the target material, and solving defects such as porosity and shrinkage caused by traditional casting methods, as well as oxidation inclusions. It also facilitates subsequent continuous upsetting to achieve ultra-large deformation.

[0016] (2) Continuous upsetting of metal rods with a deformation exceeding 400% can effectively break up the coarse grains in the metal rods, obtaining metal rod ingots with fine and uniform grains. This facilitates subsequent continuous extrusion to form metal targets with fine and uniform grains, solving the problem of difficulty in accurately controlling grain uniformity when forging large ingots obtained by traditional smelting and casting. At the same time, it avoids the impact of intermittent multi-pass forging on the continuous production of targets, significantly improving production efficiency.

[0017] (3) Under the synergistic effect of continuous casting under melt, continuous upsetting with large deformation and continuous extrusion, low-cost and continuous production of metal sputtering materials with low oxygen content and fine and uniform grains has been achieved, providing an effective way for large-scale and high-quality production of metal sputtering materials. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a process flow diagram of the method for preparing the metal target provided in the embodiments of this application. Detailed Implementation

[0020] To make the technical problems, technical solutions, and beneficial effects of this application clearer, the following detailed description is provided in conjunction with embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0021] The first aspect of this application provides a method for preparing a metal target, such as... Figure 1 As shown, it includes the following steps:

[0022] S01: Heating and melting metal raw materials to form a melt;

[0023] S02: The melt is subjected to continuous casting to obtain a thin metal rod;

[0024] S03: The thin metal rod is subjected to continuous upsetting with a deformation exceeding 400% to obtain a thick metal rod;

[0025] S04: A metal rod is continuously extruded to obtain a metal tube;

[0026] S05: The metal tube is heat-treated and then machined to obtain the metal target material.

[0027] The metal target preparation method provided in this application employs a bottom-casting continuous process to produce high-purity and fine metal rods. This method also helps reduce oxygen content, increases target density, and solves defects such as porosity and shrinkage cavities, as well as oxide inclusions, caused by traditional casting methods. Furthermore, it facilitates subsequent continuous upsetting to achieve ultra-large deformation. Continuous upsetting of the metal rod with a deformation exceeding 400% effectively breaks down coarse grains, resulting in fine-grained and uniform metal rod ingots. This facilitates subsequent continuous extrusion to form fine-grained and uniform metal targets, solving the problem of accurately controlling grain uniformity during forging after obtaining large ingots through traditional smelting and casting. Simultaneously, it avoids the impact of intermittent multi-pass forging methods on continuous target production, significantly improving production efficiency. Therefore, through the synergistic effect of molten continuous casting, large deformation continuous upsetting, and continuous extrusion, low-cost and continuous production of metal sputtering targets with low oxygen content and fine and uniform grains has been achieved, providing an effective way for the large-scale and high-quality production of metal sputtering targets.

[0028] In step S01 above, in the embodiment, the metal raw material includes at least one of copper, aluminum, zinc, tin, silver, gold, and indium.

[0029] In the embodiments, the purity of the metal raw material is >99.99%, preferably 99.995%. High-purity metal raw materials lay the foundation for the preparation of high-quality target materials, effectively reduce the impact of impurities on the performance of the target material, and avoid defects such as component segregation, porosity, shrinkage cavities, and oxide inclusions caused by impurities during subsequent processing and use, thereby improving the density, uniformity, and stability of the target material.

[0030] In the embodiment, the heating and melting are carried out under a vacuum of 1×10⁻⁶. -2 ~1×10 -3 The process is carried out under conditions of Pa and temperature ≤1300℃. Heating and melting the metal raw material under these conditions can prevent the metal from oxidizing and nitriding at high temperatures, thereby ensuring the purity of the metal target material.

[0031] In the above step S02, in the embodiment, the downward continuous casting process is carried out in an inert atmosphere and at a concentration of 1.01 × 10⁻⁶. 5 The process is carried out under a pressure of Pa. The inert atmosphere can be argon or nitrogen. The inert atmosphere further protects the molten metal, preventing oxidation reactions with oxygen and other gases during continuous casting, thus ensuring the purity of the metal rods.

[0032] In this embodiment, the rate of the continuous casting process is 50~300 mm / min. By controlling the continuous casting rate, the solidification process of the metal rod can be precisely adjusted. The continuous casting rate of this embodiment can effectively control the heat transfer and crystal growth of the molten metal during the solidification process, thereby obtaining a fine and uniform metal rod.

[0033] In this embodiment, the diameter of the metal rod is 8-30 mm. This diameter range facilitates subsequent continuous casting to achieve ultra-large deformation, thereby effectively breaking up the coarse grains in the metal rod and obtaining a fine and uniform copper rod. If the diameter of the metal rod is too small, the processing efficiency will be greatly reduced, resulting in excessively high production costs. If the diameter of the metal rod grains is too large, it will increase the difficulty of continuous upsetting to break up the grains, resulting in uniform grain size in the coarse metal rod, thus affecting the grain uniformity of the target material.

[0034] In step S03 above, in this embodiment, the step of continuously upsetting the metal rod with a deformation exceeding 400% includes: feeding the metal rod at a feed rate of 1~30 mm / min through a vacuum sintering furnace at a temperature of 300~800℃ for heating, and simultaneously pushing the heated metal rod to an upsetting device for continuous upsetting with a deformation exceeding 400%. This embodiment employs a continuous process of heating and upsetting, which allows the metal rod to maintain a specific temperature when pushed to the upsetting device, ensuring the plasticity of the metal rod and facilitating the achievement of a deformation exceeding 400%. Because high-purity copper, aluminum and other metal rods have low impurity content and low resistance to dislocation movement, by applying large deformation and combining it with ultrasonic vibration, the dislocations inside the material can be fully multiplied and annihilated, thereby driving the dynamic recrystallization process. This mechanism can effectively promote the refinement of grains into a uniform ultrafine grain structure, ultimately breaking through the grain size limit that cannot be achieved by traditional intermittent forging processes; at the same time, it closes pores, eliminates microcracks, and improves the density of the target material.

[0035] In this embodiment, the upsetting device includes a biting wheel, a first mold, and an ultrasonic vibration assembly. The biting wheel is connected to the first mold and is used to apply lateral friction force to the thin metal rod to push it continuously into the first mold for upsetting, ensuring uniform deformation transmission and avoiding local stress concentration caused by the "point contact" of traditional forging hammers. The ultrasonic vibration assembly is located on the outer wall of the first mold and is used to generate vibration waves with a frequency of 18~25KHz and an amplitude of 10~20μm to drive the bottom of the first mold to vibrate. This helps to eliminate stress, i.e., reduce dislocation accumulation, promote grain refinement, and avoid further grain growth if stress is not eliminated, which would weaken the refinement effect. It also breaks up coarse grains inside the metal and inhibits the nucleation of new coarse grains during deformation. Specifically, the ultrasonic vibration assembly may include two ultrasonic transducers respectively mounted on opposite outer walls of the first mold. Each transducer includes a transducer and an amplitude transformer. During the upsetting process, the ultrasonic transducers can apply vibrations of a certain frequency and amplitude to the first mold, allowing the vibration waves to be transmitted to the metal rod. This enhances the mobility of dislocations in the metal lattice, reduces flow stress, decreases dislocation accumulation, and promotes grain refinement. This reduces defects and increases density while simultaneously reducing equipment energy consumption and mold wear. Furthermore, it ensures the metal rod enters the first mold at a uniform speed, avoiding intermittent upsetting pauses and reducing dimensional deviations at different locations, thus guaranteeing uniform grain refinement. This solves the problem of uneven deformation leading to localized grain coarsening in traditional intermittent forging.

[0036] In this embodiment, the diameter of the metal rod is 60-220 mm. This diameter range facilitates subsequent continuous extrusion to form a metal tube.

[0037] In step S04 above, in the embodiment, the metal rod is subjected to continuous extrusion at a temperature of (300±10)~(800±10)℃.

[0038] In step S05 above, in this embodiment, the heat treatment temperature is 100~500℃ and the holding time is 3~5h.

[0039] In the embodiments, the average grain size of the metal target is <40 μm, and the oxygen content is <10 ppm. Preferably, the average grain size of the aluminum target is 30-40 μm, the average grain size of the copper target is 10-25 μm, the average grain size of the aluminum alloy target is 10-20 μm, the average grain size of the copper alloy target is 5-10 μm, the average grain size of the silver alloy target is 10-20 μm, and the average grain size of the silver target is 20-30 μm.

[0040] A second aspect of this application provides a metal target material, including a metal target material prepared by the method provided in this application.

[0041] The metal target material provided in this application embodiment is prepared by the preparation method provided in this application embodiment, and therefore has the characteristics of low oxygen content, fine and uniform grains.

[0042] The following description is based on specific embodiments.

[0043] Example 1

[0044] This embodiment provides a method for preparing a copper target, including the following steps:

[0045] (1) Heating and melting: Place oxygen-free copper raw material with a purity greater than 99.99% in a vacuum induction melting furnace, and melt it under a vacuum of 5×10⁻⁶. -3 It is heated and melted under conditions of Pa and temperature of 1200℃ to form a homogeneous melt.

[0046] (2) Downward continuous casting treatment: The melt obtained in step (1) is subjected to an argon protective atmosphere and 1.01×10 5 Under a pressure of Pa, a continuous casting process was carried out at a rate of 200 mm / min to obtain a copper rod with a diameter of 20 mm.

[0047] (3) Continuous rough upsetting: The upsetting device includes a biting wheel, a first mold and two ultrasonic transducers. The biting wheel is connected to the first mold, and the two ultrasonic transducers are respectively located on the two opposite outer walls of the first mold.

[0048] The copper rod obtained in step (2) is fed through a vacuum sintering furnace at a temperature of 600°C at a feed rate of 10 mm / min. At the same time, the heated copper rod is pushed into the upsetting device. The copper rod is pushed into the first mold by applying side friction force through the meshing wheel. The ultrasonic transducer generates a vibration wave with a frequency of 20KHz and an amplitude of 15μm to drive the bottom of the first mold to vibrate. The continuous upsetting process with a deformation of 500% is carried out to obtain a copper rod with a diameter of 122mm.

[0049] (4) Continuous extrusion: The copper rod obtained in step (3) is fed into a continuous extrusion press to continuously extrude the copper rod into the second mold at 600±10℃ to obtain a copper tube.

[0050] (5) Heat treatment: Place the copper tube obtained in step (4) in a vacuum annealing furnace and heat it to 400°C for 4 hours.

[0051] (6) Machining: The heat-treated copper tube is precision machined, polished and other machined to obtain a copper tube target with an outer diameter of 140mm.

[0052] Example 2

[0053] This embodiment provides a method for preparing a copper target, which differs from Embodiment 1 in that: in step (3), the upsetting device does not have an ultrasonic vibration component;

[0054] The copper rod obtained in step (2) is fed through a vacuum sintering furnace at a temperature of 600°C at a feed rate of 10 mm / min. At the same time, the heated copper rod is pushed into the upsetting device. The copper rod is pushed into the first mold by the meshing wheel to continuously upset the copper rod with a deformation of 500% to obtain a copper rod with a diameter of 122 mm.

[0055] Example 3

[0056] This embodiment provides a method for preparing a copper target, which differs from Embodiment 1 in that: in step (2), the melt obtained in step (1) is subjected to an argon protective atmosphere and 1.01×10⁻⁶ molten metal. 5 Under a pressure of Pa, a continuous casting process was carried out at a rate of 50 mm / min to obtain a copper rod with a diameter of 8.1 mm.

[0057] Example 4

[0058] This embodiment provides a method for preparing a copper target, which differs from Embodiment 1 in that: in step (2), the melt obtained in step (1) is subjected to an argon protective atmosphere and 1.01×10⁻⁶ molten metal. 5Under a pressure of Pa, a continuous casting process was carried out at a rate of 300 mm / min to obtain a copper rod with a diameter of 29.8 mm.

[0059] Example 5

[0060] This embodiment provides a method for preparing an aluminum target material. The difference from Embodiment 1 is that in step (1), oxygen-free aluminum raw material is used instead of oxygen-free copper raw material.

[0061] Comparative Example 1

[0062] This comparative example provides a method for preparing a copper target material. The difference from Example 1 is that the continuous rough upsetting operation in step (3) is not performed. After continuous extrusion, a copper rod with a diameter of 20 mm can only be used to obtain a copper tube target with an outer diameter in the range of 15~30 mm (it is impossible to form a copper tube target with a general specification diameter of 100-130 mm).

[0063] Comparative Example 2

[0064] This comparative example provides a method for preparing a copper target, which differs from Example 1 in that: in step (2), the melt obtained in step (1) is subjected to an argon protective atmosphere and 1.01×10⁻⁶ molten metal. 5 Under a pressure of Pa, a continuous casting process was carried out at a rate of 20 mm / min to obtain a copper rod with a diameter of 70 mm.

[0065] Comparative Example 3

[0066] This comparative example provides a method for preparing a copper target, comprising the following steps:

[0067] (1) Heating and melting: Place oxygen-free copper raw material with a purity greater than 99.99% in a vacuum induction melting furnace, and melt it under a vacuum of 5×10⁻⁶. -3 It is heated and melted under conditions of Pa and temperature of 1200℃ to form a homogeneous melt.

[0068] (2) Casting: The molten material is poured into a mold and cooled to solidify into a copper ingot with a diameter of 150 mm.

[0069] (3) Hot forging: The copper ingot with a diameter of 150×300mm is heated to 500℃ and subjected to upsetting-drawing three times;

[0070] (4) Hot extrusion: The hot-forged copper ingot is heated to 300°C and then hot-extruded to obtain a copper tube target with an outer diameter of 150 mm.

[0071] Relevant performance test analysis:

[0072] 1. The grain size of the target materials prepared in Examples 1-5 and Comparative Examples 1-3 was tested using a metallographic microscope;

[0073] 2. The oxygen content of the targets prepared in Examples 1-5 and Comparative Examples 1-4 was tested using an oxygen-nitrogen analyzer.

[0074] 3. The internal defects of the target material were tested using an ultrasonic flaw detection system; the test results are shown in Table 1 below:

[0075] Table 1

[0076]

[0077] As can be seen from Table 1, the average grain size of the metal targets prepared in Examples 1-5 is less than 40 μm, the oxygen content is less than 10 ppm, and there are no defects inside the targets. This is mainly due to the fact that the embodiments of this application use the downward continuous casting process to prepare high-purity and fine metal rods from the melt, which can reduce defects such as porosity and oxide inclusions, thereby reducing the oxygen content of the target material. At the same time, the high-purity metal rods are subjected to ultra-large deformation with a deformation of more than 400% and ultrasonic vibration. Ultra-large deformation can effectively break the coarse grains in the metal rods, while ultrasonic vibration can eliminate stress, that is, reduce dislocation accumulation, promote grain refinement, and further break the coarse grains inside the metal. In the process of deformation, it can also inhibit the nucleation of new coarse grains, and finally effectively refine the ingot grains to obtain a tube target with fine and uniform grains.

[0078] The average grain size of the metal target material prepared in Example 2 is significantly larger than that in Example 1. The main reason is that ultrasonic vibration was not introduced in the process of continuous upsetting to achieve ultra-large deformation in Example 2. First, the work hardening stress formed by dislocation accumulation inside the ingot cannot be effectively eliminated. Second, the lack of the coupling effect between the additional energy field and stress field generated by ultrasonic vibration makes it difficult to trigger severe plastic deformation and dynamic recrystallization behavior. Both of these factors weaken the grain refinement effect, resulting in an increase in the grain size of the target material in Example 2.

[0079] The average grain size of Comparative Example 1 is significantly larger than that of Example 1. The main reason is that Comparative Example 1 lacks continuous upsetting to generate severe plastic deformation and dynamic recrystallization motive force, which cannot effectively break the coarse grains of the cast structure, resulting in coarse and uneven grain size. Therefore, the grain size of the target material produced is larger.

[0080] The average grain size of Comparative Example 2 is significantly larger than that of Example 1. The main reason is that the slow continuous casting of Comparative Example 2 results in slow cooling of the melt, giving the grains sufficient time to grow. The excessively thick copper rod diameter makes it difficult for deformation to penetrate to the core during subsequent upsetting, preventing uniform ultra-large deformation and resulting in poor overall grain refinement. Therefore, the average grain size of the target material is large.

[0081] The average grain size and oxygen content of Comparative Example 3 were significantly inferior to those of Example 1, and it also exhibited obvious internal defects. The main reason is that Comparative Example 3, using conventional casting, is prone to crystallization defects such as shrinkage cavities and gas pores. Furthermore, the resulting copper ingot has a cast structure with coarser initial grains. Subsequent hot forging deformation is small and discontinuous, resulting in limited grain refinement and an inability to weld internal voids, leading to residual defects. Although the melting in Comparative Example 3 was carried out under vacuum, the subsequent non-vacuum-protected hot forging and hot extrusion processes easily lead to secondary oxidation.

[0082] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A method for preparing a metal target, characterized in that, Includes the following steps: The metal raw material is heated and melted to form a melt; The melt is subjected to a continuous casting process to obtain a thin metal rod with a diameter of 8-30 mm; The thin metal rod is fed through a vacuum sintering furnace at a temperature of 300-800°C at a feed rate of 1-30 mm / min. At the same time, the heated thin metal rod is pushed to an upsetting device for continuous upsetting with a deformation of more than 400%, resulting in a thick metal rod with a diameter of 60-220 mm. The metal rod is continuously extruded to obtain a metal tube. The metal tube is heat-treated and then machined to obtain a metal target. The upsetting device includes a meshing wheel, a first mold, and an ultrasonic vibration assembly; The engagement wheel is connected to the first mold, and the engagement wheel is used to apply lateral friction force to the metal rod to push the metal rod continuously into the first mold for upsetting; The ultrasonic vibration component is located on the outer wall of the first mold and is used to generate vibration waves with a frequency of 18~25KHz and an amplitude of 10~20μm to drive the first mold to vibrate.

2. The preparation method according to claim 1, characterized in that, The heating and melting is performed under a vacuum of 1×10⁻⁶. -2 ~1×10 -3 The experiment was conducted under conditions of Pa and temperature ≤1300℃.

3. The preparation method according to claim 1, characterized in that, The downward continuous casting process is carried out in an inert atmosphere and at 1.01×10⁻⁶. 5 The test was conducted under a pressure of Pa.

4. The preparation method according to claim 1, characterized in that, The rate of the downward continuous casting process is 50~300mm / min.

5. The preparation method according to claim 1, characterized in that, The metal raw materials include at least one of copper, aluminum, zinc, indium, tin, gold, and silver.

6. The preparation method according to claim 1, characterized in that, The purity of the metal raw material is >99.99%.

7. The preparation method according to claim 1, characterized in that, The heat treatment temperature is 100~500℃, and the holding time is 3~5h.

8. The preparation method according to any one of claims 1 to 7, characterized in that, The average grain size of the metal target is <40μm, and the oxygen content is <10ppm.

9. A metal target material, characterized in that, It is prepared by the method for preparing the metal target as described in any one of claims 1 to 8.

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