Aluminum copper target material and method of making the same

Abstract

This invention provides an aluminum-copper target and its preparation method. The preparation method includes the following steps: a preheated aluminum-copper ingot is sequentially subjected to hot forging, a first heat treatment, triaxial cold forging, a second heat treatment, uniaxial cold forging, static pressing, rolling, and a third heat treatment to obtain an aluminum-copper target with an average grain size ≤40μm and uniform cross-section. This invention uses a combination of hot forging, triaxial cold forging, and uniaxial cold forging to prepare a high-purity aluminum-copper target with fine grains and uniform microstructure. Compared to traditional uniaxial repeated forging, the preparation method of this invention avoids cracking problems caused by high internal stress, making the processing smoother. The preparation method has high production efficiency and low cost, making it suitable for widespread application.

Description

Technical Field

[0001] This invention relates to the field of target preparation technology, and in particular to an aluminum-copper target and its preparation method. Background Technology

[0002] In integrated circuit manufacturing, physical vapor deposition (PVD) is a crucial step in preparing metal thin films. High-purity aluminum-copper sputtering targets, as core consumable materials, directly determine the quality of the thin film and the chip yield due to their microstructure. With the continuous evolution of integrated circuit process nodes towards 7nm, 5nm, and even more advanced nodes, and the full transition of wafer sizes from 200mm to 300mm (12 inches), extremely stringent requirements have been placed on the uniformity of the microstructure and the degree of grain refinement of aluminum-copper sputtering targets. Research shows that fine and uniform equiaxed grains can significantly improve sputtering rate and film deposition uniformity, effectively suppress "nodules" and abnormal arc discharge during sputtering, reduce fine particle contamination, and simultaneously enhance the electromigration resistance and service reliability of aluminum thin films. Therefore, the preparation of ultrafine-grained aluminum-copper sputtering targets with an average grain size controlled below 40μm and minimal deviation across the entire cross-section has become the focus of technological competition in the industry.

[0003] The necessity of ultrafine and uniform grains is specifically reflected in four aspects: 1. Improve sputtering rate and film uniformity. Fine-grained targets have more high-energy grain boundaries, allowing atoms to preferentially escape from these boundaries during sputtering, resulting in high bombardment efficiency and fast deposition rate. Uniform grains ensure consistent consumption across the entire target surface, avoiding film thickness fluctuations caused by excessively rapid local wear, which is especially critical for large-size wafers of 300mm.

[0004] 2. Suppress nodule and fine particle contamination. Coarse or mixed grains can lead to localized differences in sputtering rates. Unexploded or insufficiently bombarded protrusions gradually grow into "nodules." These nodules can trigger abnormal arc discharges under high voltage, producing nano- to micron-sized aluminum particles. These particles can cause fatal defects such as interconnect short circuits and open circuits on the wafer, directly reducing yield.

[0005] 3. Meeting the electromigration and stress migration requirements of ultra-thin films. With the miniaturization of linewidths, the thickness of aluminum interconnects has been reduced to below 50nm. When the grain size approaches or exceeds the film thickness, grain boundaries become rapid channels for atomic diffusion, drastically reducing electromigration lifetime. A finer grain size (e.g., ≤80μm) has a larger ratio to film thickness, with denser and more randomly oriented grain boundaries, effectively dispersing current density, improving resistance to electromigration and stress migration, and ensuring long-term chip reliability.

[0006] 4. Improve etching uniformity and pattern fidelity. In subsequent etching processes, differences in the grain size of the aluminum film can lead to anisotropic etching rates, causing linewidth deviations or undercutting. A uniform, fine-grained structure can achieve a consistent etching response, ensuring the pattern accuracy of high-density integrated circuits.

[0007] However, existing processes struggle to simultaneously achieve "low cost, high efficiency, large size, and ultrafine grains." Conventional hot forging temperatures are too high (>300℃), leading to grain coarsening, while temperatures too low (e.g., 200℃) easily cause cracking. Unidirectional cold deformation exhibits poor uniformity and severe grain mixing. Multiple annealing processes during deformation eliminate deformation energy storage, resulting in insufficient driving force for final recrystallization, limiting grain refinement to only 150-200μm. Powder metallurgy and equal-diameter angular extrusion methods are either too costly or unable to produce large-size targets.

[0008] Currently, the mainstream preparation route for high-purity aluminum-copper sputtering targets is "casting + plastic deformation + recrystallization annealing". However, this route faces three major technical bottlenecks in actual production: First, selecting the appropriate hot deformation temperature is difficult and prone to cracking. Traditional hot forging or hot rolling is usually carried out above 300℃, which, while providing good plasticity, results in significant grain coarsening. If the temperature is lowered (e.g., below 200℃), the deformation resistance of aluminum increases sharply, and microcracks easily develop at the edges and inside, leading to scrap in subsequent processing. Existing processes lack precise control methods for the hot deformation behavior of high-purity aluminum around 200℃, making it difficult to simultaneously address both "cracking prevention" and "grain coarsening suppression."

[0009] Second, cold deformation results in insufficient uniformity and significant microstructural differences. Conventional unidirectional rolling or forging primarily distributes deformation along the principal strain direction, leading to significant differences in grain refinement between the core and edges, and between the surface and center of the target material. After annealing, mixed grains or localized coarse grains easily appear, severely affecting sputtering uniformity. Although multidirectional intense plastic deformation such as equal-diameter angular extrusion can improve uniformity, the equipment is expensive and inefficient, making it difficult to use for the industrial production of large-size targets.

[0010] Third, poor process matching before recrystallization makes it difficult to achieve the goal of ultrafine grains. Traditional processes often involve direct annealing after the final cold deformation pass. However, due to insufficient cold deformation or the elimination of some deformation energy by heat treatment during deformation, the recrystallization driving force is weak, and the grain refinement limit hovers around 40-100 μm. To obtain ultrafine grains below 40 μm, a very large cumulative deformation is often required, which increases the risk of cracking and process costs.

[0011] CN119710573A discloses a method for preparing high-purity aluminum sputtering targets. First, high-purity aluminum ingots are hot-forged at 250℃-300℃, then subjected to equal-diameter angular extrusion at 150℃-200℃, followed by cold rolling and annealing, ultimately yielding high-purity aluminum sputtering targets with grain sizes of 35-102 μm. While this method can create extremely fine grains in very small samples, its high cost, extremely low efficiency, and insurmountable size limitations make it difficult to implement in industrial applications that pursue "large size, high efficiency, and low cost."

[0012] Therefore, it is of great significance to develop a method for preparing aluminum-copper targets that takes into account both manufacturability and ultrafine grain size. Summary of the Invention

[0013] In view of the problems existing in the prior art, the present invention provides an aluminum-copper target and its preparation method. By performing a series of processes such as hot forging, heat treatment, cold forging, static pressing and rolling on the preheated aluminum-copper ingot, a high-purity aluminum-copper target with fine and uniform grains can be obtained.

[0014] To achieve this objective, the present invention adopts the following technical solution: In a first aspect, the present invention provides a method for preparing an aluminum-copper target material, the method comprising the following steps: The preheated aluminum-copper ingots are subjected to hot forging, first heat treatment, triaxial cold forging, second heat treatment, uniaxial cold forging, static pressing, rolling, and third heat treatment in sequence to obtain aluminum-copper targets with an average grain size ≤40μm and uniform cross-section.

[0015] The method for preparing aluminum-copper sputtering targets according to this invention combines hot forging and multi-directional cold forging. First, hot forging is performed to suppress cracking and prevent grain growth through dynamic recovery. Then, tri-directional cold forging is performed to achieve uniform three-dimensional deformation. Next, unidirectional cold forging accumulates strain, eliminating the need for intermediate heat treatment and allowing direct rolling to maximize the retention of deformation energy. Finally, a third heat treatment, recrystallization annealing, yields ultrafine-grained, high-purity aluminum-copper sputtering targets with an average grain size ≤40μm and uniform cross-section. This method balances manufacturability and ultrafine grain size, providing a novel solution for aluminum-copper sputtering targets in high-end manufacturing processes.

[0016] The average grain size of the aluminum-copper target material described in this invention is ≤40μm, for example, it can be 40μm, 35μm, 30μm, 28μm, 25μm or 10μm, etc., but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0017] Preferably, the aluminum-copper ingot is preheated at a temperature of 150-250°C, such as 150°C, 170°C, 190°C, 210°C, 230°C or 250°C, but not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0018] The time is 5-30 minutes, for example, 5 minutes, 10 minutes, 15 minutes, 20 minutes, 25 minutes or 30 minutes, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable to obtain preheated aluminum-copper ingots.

[0019] Preferably, the density of the aluminum-copper ingot is 99.9% or higher, for example, it can be 99.9%, 99.92%, 99.94%, 99.96%, 99.98% or 99.99%, etc., but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0020] Preferably, the purity of the aluminum-copper ingot is 99.999% or higher, for example, it can be 99.999%, 99.9992%, 99.9994%, 99.9996%, 99.9998% or 99.9999%, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0021] Preferably, the copper content in the aluminum-copper ingot is 0.2%-0.5% by mass, for example, it can be 0.2%, 0.26%, 0.32%, 0.38%, 0.44% or 0.5%, etc., but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0022] This invention uses hot forging, three-dimensional cold forging, one-dimensional cold forging, static pressing, and rolling to forge preheated aluminum-copper ingots to 120%-150% of the original aluminum-copper ingot height. For example, it can be 120%, 130%, 140%, 145%, or 150%, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0023] Preferably, the initial forging temperature of the hot forging is 200-250℃, for example, it can be 200℃, 210℃, 220℃, 230℃, 240℃ or 250℃, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0024] The final forging temperature is 150-200℃, for example, it can be 150℃, 160℃, 170℃, 180℃, 190℃ or 200℃, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0025] The heating rate is 2-3℃ / min, for example, 2.0℃ / min, 2.2℃ / min, 2.4℃ / min, 2.6℃ / min, 2.8℃ / min, or 3.0℃ / min, but is not limited to the listed values; other unlisted values ​​within this range are also applicable.

[0026] Preferably, the holding time for hot forging is 5-30 minutes, for example, 5 minutes, 10 minutes, 15 minutes, 20 minutes, 25 minutes, or 30 minutes, but it is not limited to the listed values; other unlisted values ​​within this range are also applicable.

[0027] Preferably, the temperature of the first heat treatment is 250-350℃, for example, it can be 250℃, 270℃, 290℃, 310℃, 330℃ or 350℃, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0028] The heat preservation time is 15-35 minutes, for example, it can be 15 minutes, 19 minutes, 23 minutes, 27 minutes, 31 minutes or 35 minutes, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0029] Preferably, the three-dimensional cold forging specifically includes: squarening the billet to 80%-95% of the height of the billet after hot forging, for example, it can be 80%, 83%, 86%, 89%, 92% or 95%, etc., but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable. Upsetting and drawing are performed once in each of the three directions of length, width and height.

[0030] Preferably, the upsetting deformation is 40%-60% of the original length, for example, it can be 40%, 44%, 48%, 52%, 56% or 60%, etc., but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable. The length of each of the three directions is the length after squaring.

[0031] Preferably, the temperature of the second heat treatment is 300-350°C, for example, it can be 300°C, 310°C, 320°C, 330°C, 340°C or 350°C, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0032] The heat preservation time is 10-20 minutes, such as 10 minutes, 12 minutes, 14 minutes, 16 minutes, 18 minutes or 20 minutes, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0033] Preferably, the unidirectional cold forging involves upsetting and drawing in the height direction. The upsetting deformation is 10%-50% of the original height, for example, it can be 10%, 18%, 26%, 34%, 42% or 50%, etc., but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable, and the drawing height is the original height.

[0034] Preferably, the unidirectional cold forging involves upsetting and drawing 2 to 3 times in the height direction, for example, 2 or 3 times.

[0035] Preferably, the process between unidirectional cold forging and hydrostatic pressing further includes: forging the square billet obtained after unidirectional cold forging into a round billet with a height of 70%-80% of the original height, for example, 70%, 72%, 74%, 76%, 78% or 80%, etc., but not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0036] Preferably, the amount of deformation caused by static pressing of the circular blank is 40%-60%, for example, it can be 40%, 44%, 48%, 52%, 56% or 60%, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0037] Preferably, the rolling process includes multi-directional rolling with a pressing deformation of 65%-80%, such as 65%, 68%, 71%, 74%, 77% or 80%, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0038] Preferably, the temperature of the third heat treatment is 200℃-300℃, for example, it can be 200℃, 220℃, 240℃, 260℃, 280℃ or 300℃, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0039] The heat preservation time is 15-60 minutes, for example, it can be 15 minutes, 20 minutes, 30 minutes, 40 minutes, 50 minutes or 60 minutes, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0040] Preferably, water cooling is performed after the first heat treatment, triaxial cold forging, second heat treatment, and third heat treatment.

[0041] As a preferred technical solution of the present invention, the preparation method includes the following steps: The aluminum-copper ingot is preheated at 150-250℃ for 5-30 minutes to obtain a preheated aluminum-copper ingot. The preheated aluminum-copper ingot is then subjected to a series of heat treatments: hot forging, a first heat treatment at 250-350℃ for 15-35 minutes, triaxial cold forging, a second heat treatment at 300-350℃ for 10-20 minutes, and uniaxial cold forging. The square billet obtained after uniaxial cold forging is forged into a round billet with 70%-80% of its original height, followed by static pressing, rolling, and a third heat treatment at 200℃-300℃ for 15-60 minutes to obtain an aluminum-copper target with an average grain size ≤40μm and uniform cross-section. The aluminum-copper ingot has a density of 99.9% or higher and a purity of 99.999% or higher; the copper content in the aluminum-copper ingot is 0.2%-0.5% by mass. The initial forging temperature of the hot forging is 200-250℃, the final forging temperature is 150-200℃, and the heating rate is 2-3℃ / min; the holding time of the hot forging is 5-30min. The three-way cold forging specifically includes: squarening the billet to 80%-95% of the height of the billet after hot forging, and upsetting and drawing it once in each of the three directions of length, width, and height; the deformation amount of the upsetting is 40%-60% of the original length in the three directions, and the length of drawing in each of the three directions is the length after squarening. The unidirectional cold forging involves upsetting and drawing in the height direction. The upsetting deformation is 10%-50% of the original height, and the drawing height is the original height. The unidirectional cold forging involves upsetting and drawing 2-3 times in the height direction. The static pressing of the circular billet results in a deformation of 40%-60%; the rolling process includes multi-directional rolling with a deformation of 65%-80%. Water cooling is performed after the first heat treatment, triaxial cold forging, second heat treatment, and third heat treatment.

[0042] Secondly, the present invention also provides an aluminum-copper target material, wherein the aluminum-copper target material is obtained by the preparation method of the aluminum-copper target material described in the first aspect.

[0043] The aluminum-copper target material described in this invention has a uniform structure and fine grains, which helps to obtain a more uniform film thickness and better film quality during sputtering.

[0044] Compared with the prior art, the present invention has at least the following beneficial effects: The method for preparing aluminum-copper targets provided by this invention is rationally designed. It obtains high-purity aluminum-copper targets with fine grains and uniform microstructure through a combination of hot forging, triaxial cold forging, and uniaxial cold forging. Compared with traditional uniaxial repeated forging, the preparation method of this invention avoids cracking problems caused by high internal stress, making the processing smoother. At the same time, triaxial cold forging ensures microstructure homogenization, and uniaxial cold forging does not require annealing treatment. Direct static pressing and rolling treatment lay a solid foundation for grain refinement. Attached Figure Description

[0045] Figure 1 This is a schematic diagram of the preparation method of the aluminum-copper target provided by the present invention. Detailed Implementation

[0046] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0047] This invention provides a method for preparing an aluminum-copper target, the process of which is shown in the schematic diagram below. Figure 1 As shown; the preparation method includes the following steps: The preheated aluminum-copper ingots are subjected to hot forging, first heat treatment, triaxial cold forging, second heat treatment, uniaxial cold forging, static pressing, rolling, and third heat treatment in sequence to obtain aluminum-copper targets with an average grain size ≤40μm and uniform cross-section.

[0048] The present invention will now be described in further detail. However, the examples described below are merely simplified examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention is determined by the claims.

[0049] Example 1 This embodiment provides a method for preparing an aluminum-copper target, the method comprising the following steps: The aluminum-copper ingot was preheated at 200℃ for 20 minutes to obtain the preheated aluminum-copper ingot. The preheated aluminum-copper ingots are subjected to a series of heat treatments: hot forging at 300°C for 20 minutes, triaxial cold forging at 320°C for 15 minutes, uniaxial cold forging, and then the square billet obtained after uniaxial cold forging is forged into a round billet with 75% of its original height. After that, the billet undergoes static pressing, rolling, and a third heat treatment at 250°C for 40 minutes to obtain the aluminum-copper target material. The aluminum-copper ingot has a density of 99.93% and a purity of 99.9992%; the copper content in the aluminum-copper ingot is 0.3% by mass. The initial forging temperature of the hot forging is 230℃, the final forging temperature is 180℃, and the heating rate is 2.3℃ / min; the holding time of the hot forging is 20min. The three-dimensional cold forging specifically includes: squarening the billet to 85% of the height of the hot-forged billet, and upsetting and drawing it once in each of the length, width, and height directions; the deformation amount of the upsetting is 50% of the original length in the original direction, and the length of drawing in each of the three directions is the length after squarening; The unidirectional cold forging involves upsetting and drawing in the height direction, with the upsetting deformation being 30% of the original height and the drawing height being the original height; the unidirectional cold forging involves two upsetting and drawing operations in the height direction. The circular billet undergoes a static pressing process with a compression deformation of 50%; the rolling process includes multi-directional rolling with a compression deformation of 70%. Water cooling is performed after the first heat treatment, triaxial cold forging, second heat treatment, and third heat treatment.

[0050] Example 2 This embodiment provides a method for preparing an aluminum-copper target, the method comprising the following steps: The aluminum-copper ingot was preheated at 150℃ for 30 minutes to obtain the preheated aluminum-copper ingot. The preheated aluminum-copper ingots are subjected to a series of heat treatments: hot forging at 250°C for 35 minutes, triaxial cold forging at 350°C for 20 minutes, uniaxial cold forging, and then the square billet obtained after uniaxial cold forging is forged into a round billet with 80% of its original height. After that, the billet undergoes static pressing, rolling, and a third heat treatment at 200°C for 60 minutes to obtain the aluminum-copper target material. The aluminum-copper ingot has a density of 99.96% and a purity of 99.9994%; the copper content in the aluminum-copper ingot is 0.2% by mass. The initial forging temperature of the hot forging is 200℃, the final forging temperature is 150℃, and the heating rate is 2℃ / min; the holding time of the hot forging is 30min. The three-dimensional cold forging specifically includes: squarening the billet to 95% of the height of the billet after hot forging, and upsetting and drawing it once in each of the length, width, and height directions; the deformation amount of the upsetting is 40% of the original length in the three directions, and the length of drawing in each of the three directions is the length after squarening; The unidirectional cold forging involves upsetting and drawing in the height direction, with the upsetting deformation being 50% of the original height and the drawing height being the original height; the unidirectional cold forging involves upsetting and drawing three times in the height direction. The static pressing of the circular billet results in a deformation of 40%; the rolling process includes multi-directional rolling with a deformation of 80%. Water cooling is performed after the first heat treatment, triaxial cold forging, second heat treatment, and third heat treatment.

[0051] Example 3 This embodiment provides a method for preparing an aluminum-copper target, the method comprising the following steps: The aluminum-copper ingot was preheated at 170℃ for 26 minutes to obtain the preheated aluminum-copper ingot. The preheated aluminum-copper ingots are subjected to a series of heat treatments: hot forging at 258°C for 18 minutes, triaxial cold forging at 315°C for 13 minutes, uniaxial cold forging, and then the square billet obtained after uniaxial cold forging is forged into a round billet with 77% of its original height. After that, the billet undergoes static pressing, rolling, and a third heat treatment at 210°C for 16 minutes to obtain the aluminum-copper target material. The aluminum-copper ingot has a density of 99.97% and a purity of 99.9992%; the copper content in the aluminum-copper ingot is 0.25% by mass. The initial forging temperature of the hot forging is 210℃, the final forging temperature is 156℃, and the heating rate is 2.2℃ / min; the holding time of the hot forging is 10min. The three-dimensional cold forging specifically includes: squarening the billet to 80.5% of the height of the hot-forged billet, and upsetting and drawing it once in each of the length, width, and height directions; the deformation amount of the upsetting is 47% of the original length in the three directions, and the length of drawing in each of the three directions is the length after squarening; The unidirectional cold forging involves upsetting and drawing in the height direction, with the upsetting deformation being 10%-50% of the original height and the drawing height being the original height; the unidirectional cold forging involves upsetting and drawing three times in the height direction. The static pressing of the circular billet results in a deformation of 56%; the rolling process includes multi-directional rolling with a deformation of 68%. Water cooling is performed after the first heat treatment, triaxial cold forging, second heat treatment, and third heat treatment.

[0052] Example 4 This embodiment provides a method for preparing an aluminum-copper target, the method comprising the following steps: The aluminum-copper ingot was preheated at 250℃ for 5 minutes to obtain the preheated aluminum-copper ingot. The preheated aluminum-copper ingots are subjected to a series of heat treatments: hot forging at 350°C for 15 minutes, three-dimensional cold forging, a second heat treatment at 300°C for 10 minutes, and unidirectional cold forging. The square billet obtained after unidirectional cold forging is forged into a round billet with 70% of its original height, and then subjected to static pressing, rolling, and a third heat treatment at 300°C for 15 minutes to obtain the aluminum-copper target material. The aluminum-copper ingot has a density of 99.94% and a purity of 99.9994%; the copper content in the aluminum-copper ingot is 0.5% by mass. The initial forging temperature of the hot forging is 250℃, the final forging temperature is 200℃, and the heating rate is 3℃ / min; the holding time of the hot forging is 5min. The three-dimensional cold forging specifically includes: squarening the billet to 80% of the height of the hot-forged billet, and upsetting and drawing it once in each of the three directions of length, width, and height; the deformation amount of the upsetting is 60% of the original length in the three directions, and the length of drawing in each of the three directions is the length after squarening; The unidirectional cold forging involves upsetting and drawing in the height direction, with the upsetting deformation being 10% of the original height and the drawing height being the original height; the unidirectional cold forging involves upsetting and drawing twice in the height direction. The circular billet undergoes a static pressing process with a compression deformation of 60%; the rolling process includes multi-directional rolling with a compression deformation of 65%. Water cooling is performed after the first heat treatment, triaxial cold forging, second heat treatment, and third heat treatment.

[0053] Based on Examples 1-4, it can be concluded that the preparation method provided by the present invention is reasonably designed. By sequentially performing hot forging, first heat treatment, triaxial cold forging, second heat treatment, uniaxial cold forging, static pressing, rolling, and third heat treatment, a high-purity aluminum-copper target with an average grain size ≤40μm and uniform cross-section is prepared. Compared with the traditional uniaxial repeated forging, it avoids the problem of cracking caused by large internal stress, makes the processing smoother, improves the preparation efficiency of high-purity aluminum-copper target material, and reduces the preparation cost.

[0054] Example 5 This embodiment provides a method for preparing an aluminum-copper target material. Except for the preheating temperature of 120°C, the preparation method is the same as that in Embodiment 1.

[0055] Example 6 This embodiment provides a method for preparing an aluminum-copper target material. Except for the preheating temperature of 280°C, the preparation method is the same as that in Embodiment 1.

[0056] As can be seen from the comparison between Example 1 and Examples 5-6, the preheating temperature in Example 5 is relatively low, which leads to incomplete recrystallization, resulting in a high cracking rate of the prepared target material and poor uniformity of the sputtered film thickness during sputtering. The preheating temperature in Example 6 is relatively high, which leads to coarse grains and overheating.

[0057] Example 7 This embodiment provides a method for preparing an aluminum-copper target material. Except for the fact that the rolling deformation is 50%, the preparation method is the same as in Embodiment 1.

[0058] Example 8 This embodiment provides a method for preparing an aluminum-copper target material. Except for the fact that the rolling deformation is 90%, the preparation method is the same as in Embodiment 1.

[0059] As can be seen from the comparison between Example 1 and Examples 7-8, the amount of downward deformation in the rolling process in Example 7 is relatively small, which will lead to insufficient recrystallization after the third heat treatment annealing and the overall grains are relatively coarse; the amount of downward deformation in the rolling process in Example 8 is relatively large, which will lead to the grains being extremely elongated and easily forming penetrating micro-shear bands in the grains, which will seriously affect the quality of the target material.

[0060] Comparative Example 1 This comparative example provides a method for preparing an aluminum-copper target material. The method is the same as in Example 1, except that the aluminum-copper ingot is not preheated and kept warm, and hot forging is started directly.

[0061] In this comparative example, the aluminum-copper ingots were not preheated and held at the same temperature before hot forging, resulting in a significant temperature difference between the ingot surface and core. This led to intense dynamic recrystallization on the surface, causing abnormal grain growth. Meanwhile, the core, due to lower temperature and insufficient deformation, underwent incomplete recrystallization, ultimately forming a mixed-grain structure with coarse surface grains and fine or incompletely recrystallized grains in the core. This mixed-grain structure is difficult to eliminate during subsequent heat treatment and will be inherited by the final sputtering target, reducing sputtering uniformity.

[0062] Comparative Example 2 This comparative example provides a method for preparing an aluminum-copper target material. The method is the same as in Example 1, except that the triaxial cold forging after the first heat treatment is replaced with uniaxial cold forging. The uniaxial cold forging involves upsetting and drawing in the height direction. The upsetting deformation is 30% of the original height, and the drawing height is the original height. The uniaxial cold forging involves upsetting and drawing twice in the height direction.

[0063] Because the first heat treatment in this comparative example was also followed by unidirectional cold forging, the uniformity of cold deformation was insufficient, the microstructure was significantly different, the deformation was mainly distributed along the principal strain direction, and the grain refinement of the target material was significantly different between the core and the edge, and between the surface and the center. After the third heat treatment, mixed grains or local coarse grains were prone to appear, which seriously affected the sputtering uniformity.

[0064] Comparative Example 3 This comparative example provides a method for preparing an aluminum-copper target material. The method is the same as that in Example 1, except that it does not involve static pressing and rolling.

[0065] Because this comparative example does not undergo hydrostatic pressing, it directly undergoes third heat treatment annealing after unidirectional cold forging. Due to insufficient cold deformation or the elimination of some deformation energy by midway heat treatment after deformation, the recrystallization driving force is weak and the grain refinement is insufficient.

[0066] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A method of producing an aluminum copper target material, characterized by, The preparation method includes the following steps: The preheated aluminum-copper ingots are subjected to hot forging, first heat treatment, triaxial cold forging, second heat treatment, uniaxial cold forging, static pressing, rolling, and third heat treatment in sequence to obtain aluminum-copper targets with an average grain size ≤40μm and uniform cross-section.

2. The production method according to claim 1, characterized by, The original aluminum-copper ingot is preheated at a temperature of 150-250℃ for 5-30 minutes to obtain the preheated aluminum-copper ingot. Preferably, the density of the primary aluminum-copper ingot is 99.9% or higher; Preferably, the purity of the primary aluminum-copper ingot is 99.999% or higher; Preferably, the copper content in the primary aluminum-copper ingot is 0.2%-0.5% by mass.

3. The production method according to claim 1 or 2, characterized by, The initial forging temperature of the hot forging is 200-250℃, the final forging temperature is 150-200℃, and the heating rate is 2-3℃ / min; Preferably, the holding time for hot forging is 5-30 minutes; Preferably, the temperature of the first heat treatment is 250-350℃, and the holding time is 15-35 minutes.

4. The production method according to any one of claims 1 to 3, characterized by, The three-dimensional cold forging specifically includes: squarening the billet to 80%-95% of the height of the hot-forged billet, and upsetting and drawing once in each of the length, width and height directions; Preferably, the upsetting deformation is 40%-60% of the original length, and the elongation in each of the three directions is the length after squaring.

5. The method of any one of claims 1-4, wherein, The second heat treatment is performed at a temperature of 300-350℃ for 10-20 minutes.

6. The preparation method according to any one of claims 1-5, characterized in that, The unidirectional cold forging involves upsetting and drawing in the height direction. The upsetting deformation is 10%-50% of the original height, and the drawing height is the original height. Preferably, the unidirectional cold forging involves upsetting and drawing 2 to 3 times in the height direction.

7. The preparation method according to any one of claims 1-5, characterized in that, The process between unidirectional cold forging and static pressing also includes: forging the square billet obtained after unidirectional cold forging into a round billet with 70%-80% of its original height; Preferably, the deformation amount of the circular billet under static pressure is 40%-60%; Preferably, the rolling process includes multi-directional rolling with a compression deformation of 65%-80%.

8. The preparation method according to any one of claims 1-7, characterized in that, The temperature of the third heat treatment is 200℃-300℃, and the holding time is 15-60min.

9. The preparation method according to any one of claims 1-8, characterized in that, Water cooling is performed after the first heat treatment, triaxial cold forging, second heat treatment, and third heat treatment.

10. An aluminum-copper target material, characterized in that, The aluminum-copper target material is obtained by the preparation method of the aluminum-copper target material according to any one of claims 1-9.

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