A large-size tantalum-aluminum alloy target assembly, a preparation method thereof and an application thereof

Abstract

The application provides a large-size tantalum-aluminum alloy target assembly and a preparation method and application thereof. The preparation method comprises the following steps: (1) uniformly mixing tantalum powder and aluminum powder to obtain alloy powder; (2) loading the alloy powder into a flexible mold to perform cold isostatic pressing forming, thereby obtaining an alloy green body; (3) sequentially performing vacuum degassing and sintering densification on the alloy green body encapsulated in a metal sheath, thereby obtaining a densified body; (4) removing the sheath and then performing mechanical processing on the body, thereby obtaining a tantalum-aluminum alloy target blank; (5) arranging an aluminum intermediate layer between the tantalum-aluminum alloy target blank and a back plate, sequentially performing sheath welding and vacuum degassing after assembly; (6) performing solid-phase diffusion welding on the degassed assembly, removing the sheath after welding, and then performing mechanical processing, thereby obtaining the large-size tantalum-aluminum alloy target assembly. The application successfully prepares a tantalum-aluminum alloy target with a diameter of greater than or equal to 400 mm, and the purity is stable and reaches more than 4N, thereby filling the domestic large-size high-purity TaAl target production blank.

Description

Technical Field

[0001] This invention belongs to the field of sputtering target technology, and relates to a tantalum-aluminum alloy target assembly, and more particularly to a large-size tantalum-aluminum alloy target assembly, its preparation method and application. Background Technology

[0002] Tantalum aluminum alloy (TaAl) targets are important raw materials for physical vapor deposition processes in semiconductor manufacturing and new display fields. The thin films formed by their deposition have excellent diffusion barrier properties, thermal stability, high resistivity and copper interconnect adhesion. They are key components of device structures such as high-k gate dielectric electrodes, gate and source / drain electrodes in TFT arrays, and copper interconnect barrier layers, and are widely used in the mass production of advanced logic chips, DRAM memory chips and high-generation OLED display panels.

[0003] As semiconductor manufacturing processes continue to advance to advanced nodes and wafer sizes iterate from 8 inches to 12 inches, while display panel generation lines are constantly being upgraded and the coating area per furnace is continuously expanding, the industry has put forward higher requirements for the size specifications, purity level, microstructure uniformity and high-temperature service reliability of TaAl targets. Large size, high purity and high stability have become important development directions for this type of target.

[0004] Currently, the industrial preparation of TaAl alloy targets in China mostly adopts the traditional powder metallurgy process. Limited by the significant differences in density, melting point, and atomic diffusion rate between tantalum and aluminum, existing forming and sintering processes struggle to achieve uniform densification of large-size blanks. Product diameters are generally limited to the 300mm range, failing to meet the coating production requirements of 12-inch wafers and large-size display panels. Furthermore, conventional sintering processes easily lead to the localized precipitation of hard and brittle intermetallic compound phases, resulting in insufficient overall toughness of the target blank. Subsequent machining processes frequently encounter failures such as chipping and cracking, leading to low product yields. Insufficient compositional segregation and uniformity in the microstructure also make it difficult to meet the stringent requirements of advanced processes for film thickness consistency and performance stability. There remains a gap in the domestic production technology for large-size TaAl targets with a purity consistently above 4N.

[0005] Regarding the bonding process between the target and the backplate, the mainstream domestic method is indium soldering. This technology is mature and has low implementation costs, but indium-based solders have a low melting point and poor high-temperature mechanical properties at the weld interface, making it only suitable for low-temperature sputtering conditions. With the continuous increase in sputtering power and process temperature of high-end coating equipment, traditional indium soldered targets are prone to failure problems such as weld softening and interface debonding during high-temperature sputtering, failing to meet the long-term stable use requirements of high-temperature sputtering equipment and becoming one of the bottlenecks restricting the domestic application of high-end TaAl targets.

[0006] Therefore, how to prepare large-size tantalum-aluminum alloy targets and develop a high-reliability target welding process suitable for high-temperature sputtering conditions has become a technical problem that the domestic target industry urgently needs to overcome. Summary of the Invention

[0007] To address the shortcomings of existing technologies, the present invention aims to provide a large-size tantalum-aluminum alloy target assembly, its preparation method and application, and to develop a highly reliable target welding process suitable for high-temperature sputtering conditions.

[0008] To achieve this objective, the present invention adopts the following technical solution:

[0009] In a first aspect, the present invention provides a method for preparing a large-size tantalum-aluminum alloy target assembly, comprising the following steps:

[0010] (1) Tantalum powder and aluminum powder are mixed evenly to obtain alloy powder;

[0011] (2) The alloy powder is loaded into a flexible mold and cold isostatically pressed to obtain an alloy green billet;

[0012] (3) The alloy green billet is encapsulated in a metal sleeve and then subjected to vacuum degassing and sintering densification in sequence to obtain a densified billet;

[0013] (4) Remove the cladding of the densified billet, and then machine the billet to obtain a tantalum-aluminum alloy target billet of a preset size;

[0014] (5) An aluminum intermediate layer is provided between the tantalum-aluminum alloy target blank and the back plate. After assembly, the casing welding and vacuum degassing are performed in sequence.

[0015] (6) The degassed assembly is subjected to solid-phase diffusion welding, the welded casing is removed, and the large-size tantalum-aluminum alloy target assembly is obtained after machining.

[0016] The target diameter in the large-size tantalum-aluminum alloy target assembly is ≥400mm, and the target purity is ≥4N.

[0017] This invention precisely suppresses the excessive precipitation of brittle TaAl3 phase through sintering densification, significantly improving the density of the billet, resulting in a uniform microstructure without segregation or porosity, and significantly enhancing the toughness of the billet. This greatly reduces the risk of chipping and cracking during machining and transportation. Furthermore, solid-state diffusion welding achieves a tight bond between the target material and the backing plate, with welding strength far exceeding the mechanical bonding strength of indium soldering, and no defects such as delamination, voids, or microcracks. Ultimately, a tantalum-aluminum alloy target material with a diameter ≥400mm was successfully prepared, and its purity stably reached 4N or higher, filling the gap in the mass production of large-size high-purity TaAl targets in China.

[0018] Preferably, the tantalum powder in step (1) has a purity of ≥99.99% and a particle size of ≤100μm.

[0019] Preferably, the aluminum powder in step (1) has a purity of ≥99.99% and a particle size of 20~25μm.

[0020] Preferably, the molar ratio of tantalum to aluminum in the alloy powder of step (1) is (0.5~1.5):1.

[0021] Preferably, the mixing in step (1) is carried out in a three-dimensional powder mixer.

[0022] Preferably, the mixing speed in step (1) is 13~20 rpm.

[0023] Preferably, the mixing time in step (1) is 40-50 hours.

[0024] Preferably, the flexible mold in step (2) includes a polyester sleeve, and the mold assembly process is carried out in three equal batches to control the compaction density ≥50% and the mold assembly height deviation ≤2mm.

[0025] Preferably, the pressure of cold isostatic pressing in step (2) is 200~300MPa.

[0026] Preferably, the holding time for cold isostatic pressing in step (2) is ≥15 min.

[0027] Preferably, the pressure relief rate of the cold isostatic pressing in step (2) is ≤5MPa / min.

[0028] Preferably, the metal sheath in step (3) includes a stainless steel sheath.

[0029] Preferably, the degassing temperature in step (3) is 400~500℃, and the vacuum degree is not less than 5×10⁻⁶. -3 Pa.

[0030] Preferably, the sintering densification in step (3) is carried out in a hot isostatic pressing apparatus.

[0031] Preferably, the sintering temperature for densification in step (3) is 400~600℃ and the sintering pressure is ≥100MPa.

[0032] Preferably, the thickness of the aluminum interlayer in step (5) is 0.3~0.5mm.

[0033] Preferably, the material of the back plate in step (5) includes any one of oxygen-free copper, copper alloy, molybdenum alloy or aluminum alloy.

[0034] Preferably, the solid-phase diffusion welding in step (6) is performed in a hot isostatic pressing apparatus.

[0035] Preferably, the welding temperature of the solid-phase diffusion welding in step (6) is 250~500℃.

[0036] In a second aspect, the present invention provides a large-size tantalum-aluminum alloy target assembly prepared by the preparation method described in the first aspect, comprising a tantalum-aluminum alloy target and a backplate welded together, wherein the tantalum-aluminum alloy target has a diameter ≥400mm and a purity ≥4N.

[0037] Thirdly, the present invention provides an application of a large-size tantalum-aluminum alloy target assembly as described in the second aspect, specifically for magnetron sputtering of TaAl thin films.

[0038] Compared with the prior art, the present invention has the following beneficial effects:

[0039] This invention precisely suppresses the excessive precipitation of brittle TaAl3 phase through sintering densification, significantly improving the density of the billet, resulting in a uniform microstructure without segregation or porosity, and significantly enhancing the toughness of the billet. This greatly reduces the risk of chipping and cracking during machining and transportation. Furthermore, solid-state diffusion welding achieves a tight bond between the target material and the backing plate, with welding strength far exceeding the mechanical bonding strength of indium soldering, and no defects such as delamination, voids, or microcracks. Ultimately, a tantalum-aluminum alloy target material with a diameter ≥400mm was successfully prepared, and its purity stably reached 4N or higher, filling the gap in the mass production of large-size high-purity TaAl targets in China. Detailed Implementation

[0040] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0041] One embodiment of the present invention provides a method for preparing a large-size tantalum-aluminum alloy target assembly, comprising the following steps:

[0042] (1) Tantalum powder and aluminum powder are mixed evenly to obtain alloy powder;

[0043] (2) The alloy powder is loaded into a flexible mold and cold isostatically pressed to obtain an alloy green billet;

[0044] (3) The alloy green billet is encapsulated in a metal sleeve and then subjected to vacuum degassing and sintering densification in sequence to obtain a densified billet;

[0045] (4) Remove the cladding of the densified billet, and then machine the billet to obtain a tantalum-aluminum alloy target billet of a preset size;

[0046] (5) An aluminum intermediate layer is provided between the tantalum-aluminum alloy target blank and the back plate. After assembly, the casing welding and vacuum degassing are performed in sequence.

[0047] (6) The degassed assembly is subjected to solid-phase diffusion welding, the welded casing is removed, and the large-size tantalum-aluminum alloy target assembly is obtained after machining.

[0048] The target diameter in the large-size tantalum-aluminum alloy target assembly is ≥400mm, for example, it can be 400mm, 405mm, 410mm, 415mm, 420mm, 425mm, 430mm, 435mm, 440mm, 445mm or 450mm, and the target purity is ≥4N, for example, it can be 99.99%, 99.991%, 99.992%, 99.993%, 99.994%, 99.995%, 99.996%, 99.997%, 99.998% or 99.999%, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0049] In this invention, 4N is a commonly used term to represent the purity of metals, where "N" stands for "Nines," meaning that the purity is expressed in multiples of 9. For example, 4N represents a purity of 99.99%, 4N5 represents a purity of 99.995%, and so on, so it will not be elaborated further.

[0050] This invention precisely suppresses the excessive precipitation of brittle TaAl3 phase through sintering densification, significantly improving the density of the billet, resulting in a uniform microstructure without segregation or porosity, and significantly enhancing the toughness of the billet. This greatly reduces the risk of chipping and cracking during machining and transportation. Furthermore, solid-state diffusion welding achieves a tight bond between the target material and the backing plate, with welding strength far exceeding the mechanical bonding strength of indium soldering, and no defects such as delamination, voids, or microcracks. Ultimately, a tantalum-aluminum alloy target material with a diameter ≥400mm was successfully prepared, and its purity stably reached 4N or higher, filling the gap in the mass production of large-size high-purity TaAl targets in China.

[0051] In some embodiments, the tantalum powder in step (1) has a purity ≥ 99.99%, for example, it can be 99.99%, 99.991%, 99.992%, 99.993%, 99.994%, 99.995%, 99.996%, 99.997%, 99.998% or 99.999%, and a particle size ≤ 100 μm, for example, it can be 50 μm, 55 μm, 60 μm, 65 μm, 70 μm, 75 μm, 80 μm, 85 μm, 90 μm, 95 μm or 100 μm, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0052] In some embodiments, the purity of the aluminum powder in step (1) is ≥99.99%, for example, it can be 99.99%, 99.991%, 99.992%, 99.993%, 99.994%, 99.995%, 99.996%, 99.997%, 99.998% or 99.999%, and the particle size is 20~25μm, for example, it can be 20μm, 21μm, 22μm, 23μm, 24μm or 25μm, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0053] In some embodiments, the molar ratio of tantalum to aluminum in the alloy powder of step (1) is (0.5~1.5):1, for example, it can be 0.5:1, 0.6:1, 0.7:1, 0.8:1, 0.9:1, 1.0:1, 1.1:1, 1.2:1, 1.3:1, 1.4:1 or 1.5:1, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0054] In some embodiments, the mixing in step (1) is carried out in a three-dimensional mixer.

[0055] In some embodiments, the mixing speed in step (1) is 13 to 20 rpm, for example, it can be 13 rpm, 14 rpm, 15 rpm, 16 rpm, 17 rpm, 18 rpm, 19 rpm or 20 rpm, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0056] In some embodiments, the mixing time in step (1) is 40 to 50 hours, for example, it can be 40 hours, 41 hours, 42 hours, 43 hours, 44 hours, 45 hours, 46 hours, 47 hours, 48 ​​hours, 49 hours or 50 hours, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0057] In some embodiments, the flexible mold in step (2) includes a polyester sleeve. The molding process is divided into three equal feedings to control the filling density to be ≥50%, for example, it can be 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90% or 95%, and the molding height deviation is ≤2mm, for example, it can be 0.2mm, 0.4mm, 0.6mm, 0.8mm, 1mm, 1.2mm, 1.4mm, 1.6mm, 1.8mm or 2mm, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0058] In some embodiments, the pressure of cold isostatic pressing in step (2) is 200~300MPa, for example, it can be 200MPa, 220MPa, 240MPa, 250MPa, 260MPa, 270MPa, 280MPa, 290MPa or 300MPa, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0059] In some embodiments, the holding time of cold isostatic pressing in step (2) is ≥15 min, for example, it can be 15 min, 16 min, 17 min, 18 min, 19 min, 20 min, 21 min, 22 min, 23 min, 24 min or 25 min, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0060] In some embodiments, the pressure relief rate of the cold isostatic pressing in step (2) is ≤5MPa / min, for example, it can be 0.5MPa / min, 1MPa / min, 1.5MPa / min, 2MPa / min, 2.5MPa / min, 3MPa / min, 3.5MPa / min, 4MPa / min, 4.5MPa / min or 5MPa / min, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0061] In some embodiments, the metal sheath in step (3) includes a stainless steel sheath.

[0062] In some embodiments, the degassing temperature in step (3) is 400~500℃, for example, it can be 400℃, 410℃, 420℃, 430℃, 440℃, 450℃, 460℃, 470℃, 480℃, 490℃ or 500℃, and the vacuum degree is not less than 5×10 -3 Pa, for example, could be 1×10 -4 Pa, 3×10 -4 Pa, 5×10 -4 Pa, 1×10 -3 Pa, 3×10 -3 Pa or 5×10 -3 Pa, but not limited to the listed values, applies to other unlisted values ​​within the same range.

[0063] In some embodiments, the sintering densification in step (3) is carried out in a hot isostatic pressing apparatus.

[0064] In some embodiments, the sintering temperature for densification in step (3) is 400~600℃, for example, it can be 400℃, 420℃, 440℃, 460℃, 480℃, 500℃, 520℃, 540℃, 560℃, 580℃ or 600℃, and the sintering pressure is ≥100MPa, for example, it can be 100MPa, 110MPa, 120MPa, 130MPa, 140MPa, 150MPa, 160MPa, 170MPa, 180MPa, 190MPa or 200MPa, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0065] This invention limits the sintering temperature for densification to 400~600℃. Within this temperature range, Ta and Al can diffuse in a controlled manner, significantly reducing the precipitation of hard and brittle TaAl3 intermetallic compounds, improving the overall toughness of the target blank, and reducing the risk of processing cracks and chipping. At the same time, the above temperature range is relatively mild, which can avoid abnormal grain growth, ensure the uniformity of the target blank microstructure, and result in better consistency in the thickness and resistivity of the subsequent sputtered film.

[0066] In addition, the temperature range of 400~600℃ combined with the high pressure of over 100MPa can promote the full diffusion of atoms at the powder interface without ultra-high temperature, so that the density of the blank reaches over 99%, and the internal loose pores are fully eliminated, thereby achieving full densification of the target blank.

[0067] In some embodiments, the thickness of the aluminum intermediate layer in step (5) is 0.3~0.5mm, for example, it can be 0.3mm, 0.32mm, 0.35mm, 0.38mm, 0.4mm, 0.42mm, 0.45mm, 0.48mm or 0.5mm, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0068] The present invention sets an aluminum intermediate layer as a soft transition layer between the tantalum-aluminum alloy target blank and the back plate. Its function is to compensate for the surface micro-flatness deviation between the target blank and the back plate, alleviate the welding residual stress caused by the mismatch of thermal expansion coefficients of dissimilar materials, and reduce the interface diffusion activation energy to promote low-temperature metallurgical bonding.

[0069] Furthermore, for large-sized targets with a diameter ≥400mm, due to the large welding interface area and the greater difficulty in controlling the flatness of the entire surface, this invention specifically limits the thickness of the aluminum interlayer to 0.3~0.5mm to fully ensure uniform contact at the interface and achieve complete bonding across the entire area. If the thickness is less than 0.3mm, it is difficult to completely fill the microscopic unevenness and flatness errors of the large-sized interface, which easily leads to local unbonded areas and a significant decrease in stress buffering effect; if the thickness is greater than 0.5mm, the aluminum interlayer itself becomes a weak area in mechanical properties, and the high-temperature diffusion process easily generates excessive brittle intermetallic compounds, which in turn reduces the bonding strength and high-temperature service stability of the welding interface.

[0070] In some embodiments, the material of the backplate in step (5) includes any one of oxygen-free copper, copper alloy, molybdenum alloy or aluminum alloy.

[0071] In some embodiments, the solid-phase diffusion welding in step (6) is performed in a hot isostatic pressing apparatus.

[0072] In some embodiments, the welding temperature of solid-phase diffusion welding in step (6) is 250~500℃, for example, it can be 250℃, 270℃, 300℃, 330℃, 360℃, 390℃, 420℃, 450℃, 480℃ or 500℃, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0073] This invention limits the welding temperature of solid-state diffusion welding to 250~500℃, which can not only fully activate the diffusion of aluminum atoms at the interface and form a complete metallurgical bond by relying on hot isostatic pressing to ensure a 100% interface bonding rate, but also avoid the precipitation of hard and brittle TaAl3 intermetallic compounds caused by excessive temperature, thereby maintaining the high mechanical strength of the weld interface.

[0074] In addition, the residual stress caused by the thermal expansion difference in the above temperature range is small, and large-size targets are less prone to welding warping and interface microcracks. At the same time, it avoids the coarsening of target blank grains and the deterioration of the structure caused by high temperature, and retains the uniform microstructure and high toughness of the target blank.

[0075] Furthermore, unlike traditional low-temperature indium soldering, the above solid-phase diffusion welding does not require low-melting-point brazing filler metal, the weld interface is resistant to high temperatures, and it is suitable for high-temperature sputtering equipment.

[0076] One embodiment of the present invention also provides a large-size tantalum-aluminum alloy target assembly prepared by the preparation method described in any of the above embodiments, comprising a tantalum-aluminum alloy target and a backplate welded together. The diameter of the tantalum-aluminum alloy target is ≥400mm, for example, it can be 400mm, 405mm, 410mm, 415mm, 420mm, 425mm, 430mm, 435mm, 440mm, 445mm or 450mm, and the purity is ≥4N, for example, it can be 99.99%, 99.991%, 99.992%, 99.993%, 99.994%, 99.995%, 99.996%, 99.997%, 99.998% or 99.999%, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0077] One embodiment of the present invention also provides an application of the large-size tantalum-aluminum alloy target assembly described in any of the above embodiments, specifically for magnetron sputtering of TaAl thin films.

[0078] The TaAl thin film prepared by this invention has excellent anti-reflection, corrosion resistance, high resistance, thermal stability, and copper diffusion blocking properties. It can simultaneously meet the physical vapor deposition requirements of high-end semiconductors and optoelectronic devices such as high-generation OLED display TFT electrodes, advanced logic chips, DRAM memory, and high-k gate dielectric electrodes, thus eliminating the dependence on imports of large-size TaAl targets.

[0079] The numerical range described in this invention includes not only the point values ​​listed above, but also any point values ​​within the numerical ranges not listed above. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific point values ​​included in the range.

[0080] Example 1

[0081] This embodiment provides a method for preparing a large-size tantalum-aluminum alloy target assembly, specifically including the following steps:

[0082] (1) Tantalum powder and aluminum powder are fed into a three-dimensional powder mixer, the rotation speed is set to 15 rpm, and the powder is mixed for 48 hours to obtain alloy powder; wherein, the purity of the tantalum powder is ≥99.99% and the particle size is 85 μm; the purity of the aluminum powder is ≥99.99% and the particle size is 22 μm; the molar ratio of tantalum element and aluminum element in the alloy powder is 1:1.

[0083] (2) The alloy powder is loaded into a polyester sleeve. The molding process is carried out in three equal batches, and the compaction density is controlled to be 60%. The molding height deviation is ≤2mm. Then, cold isostatic pressing is performed under a pressure of 250MPa. The holding time is controlled to be 20min. Finally, the pressure is released at a rate of 4MPa / min to obtain the alloy billet.

[0084] (3) The alloy green billet is encapsulated in a stainless steel sleeve, ensuring no air leakage, at 450°C and a vacuum degree of not less than 5×10⁻⁶. -3 The material is degassed under Pa conditions and then transferred to a hot isostatic pressing (HIP) equipment for sintering and densification at 500°C and 120 MPa to obtain a densified green body.

[0085] (4) Remove the cladding of the densified billet, and then machine the billet to obtain a tantalum-aluminum alloy target billet of a preset size;

[0086] (5) An aluminum interlayer with a thickness of 0.4 mm is provided between the tantalum-aluminum alloy target blank and the copper alloy back plate. After assembly, a sheath welding is performed, followed by a process at 450°C and a vacuum degree of not less than 5×10⁻⁶. -3 Degassing was performed under Pa conditions;

[0087] (6) The degassed assembly is transferred to a hot isostatic pressing equipment and solid-phase diffusion welding is performed at 450°C. After the welding is removed, the large-size tantalum-aluminum alloy target assembly is obtained after machining.

[0088] Testing revealed that the target diameter in the large-size tantalum-aluminum alloy target assembly obtained in this embodiment is 450mm, and the target purity is ≥4N.

[0089] Example 2

[0090] This embodiment provides a method for preparing a large-size tantalum-aluminum alloy target assembly, specifically including the following steps:

[0091] (1) Tantalum powder and aluminum powder are fed into a three-dimensional powder mixer, the rotation speed is set to 13 rpm, and the powder is mixed for 50 h to obtain alloy powder; wherein, the purity of the tantalum powder is ≥99.99% and the particle size is 100 μm; the purity of the aluminum powder is ≥99.99% and the particle size is 25 μm; the molar ratio of tantalum element to aluminum element in the alloy powder is 0.5:1.

[0092] (2) The alloy powder is loaded into a polyester sleeve. The molding process is divided into three equal feedings, the compaction density is controlled to be 50%, and the molding height deviation is ≤2mm. Then, cold isostatic pressing is performed under a pressure of 300MPa, the holding time is controlled to be 15min, and finally the pressure is released at a rate of 5MPa / min to obtain the alloy green blank.

[0093] (3) The alloy green billet is encapsulated in a stainless steel sleeve, ensuring no air leakage, at 400°C and a vacuum degree of not less than 5×10⁻⁶. -3 The material is degassed under Pa conditions and then transferred to a hot isostatic pressing (HIP) equipment for sintering and densification at 400°C and 150 MPa to obtain a densified green body.

[0094] (4) Remove the cladding of the densified billet, and then machine the billet to obtain a tantalum-aluminum alloy target billet of a preset size;

[0095] (5) An aluminum interlayer with a thickness of 0.3 mm is provided between the tantalum-aluminum alloy target blank and the molybdenum alloy back plate. After assembly, a sheath welding is performed, followed by a process at 400°C and a vacuum degree of not less than 5×10⁻⁶. -3 Degassing was performed under Pa conditions;

[0096] (6) The degassed assembly is transferred to a hot isostatic pressing equipment and solid-phase diffusion welding is performed at 250°C. After the welding is removed, the large-size tantalum-aluminum alloy target assembly is obtained after machining.

[0097] Testing revealed that the target diameter in the large-size tantalum-aluminum alloy target assembly obtained in this embodiment is 450mm, and the target purity is ≥4N.

[0098] Example 3

[0099] This embodiment provides a method for preparing a large-size tantalum-aluminum alloy target assembly, specifically including the following steps:

[0100] (1) Tantalum powder and aluminum powder are fed into a three-dimensional powder mixer, the rotation speed is set to 20 rpm, and the powder is mixed for 40 h to obtain alloy powder; wherein, the purity of the tantalum powder is ≥99.99% and the particle size is 90 μm; the purity of the aluminum powder is ≥99.99% and the particle size is 20 μm; the molar ratio of tantalum element to aluminum element in the alloy powder is 1.5:1.

[0101] (2) The alloy powder is loaded into a polyester sleeve. The molding process is divided into three equal feedings, the compaction density is controlled to be 60%, the molding height deviation is ≤2mm, and then cold isostatic pressing is performed under a pressure of 200MPa. The holding time is controlled to be 20min, and finally the pressure is released at a rate of 4MPa / min to obtain the alloy green blank.

[0102] (3) The alloy green billet is encapsulated in a stainless steel sleeve, ensuring no air leakage, at 500°C and a vacuum degree of not less than 5×10⁻⁶. -3 The material is degassed under Pa conditions and then transferred to a hot isostatic pressing (HIP) equipment for sintering and densification at 600°C and 100 MPa to obtain a densified green body.

[0103] (4) Remove the cladding of the densified billet, and then machine the billet to obtain a tantalum-aluminum alloy target billet of a preset size;

[0104] (5) An aluminum interlayer with a thickness of 0.5 mm is provided between the tantalum-aluminum alloy target blank and the aluminum alloy back plate. After assembly, a sheath welding is performed, followed by a process at 500°C and a vacuum degree of not less than 5×10⁻⁶. -3Degassing was performed under Pa conditions;

[0105] (6) The degassed assembly is transferred to a hot isostatic pressing equipment and solid-phase diffusion welding is performed at 500°C. After the welding is removed, the large-size tantalum-aluminum alloy target assembly is obtained after machining.

[0106] Testing revealed that the target diameter in the large-size tantalum-aluminum alloy target assembly obtained in this embodiment is 450mm, and the target purity is ≥4N.

[0107] Example 4

[0108] This embodiment provides a method for preparing a large-size tantalum-aluminum alloy target assembly. Except for reducing the pressure of cold isostatic pressing in step (2) to 150MPa, the other steps and conditions are the same as in embodiment 1, so they will not be described in detail here.

[0109] Testing revealed that the target diameter in the large-size tantalum-aluminum alloy target assembly obtained in this embodiment is 450mm, and the target purity is ≥4N.

[0110] Example 5

[0111] This embodiment provides a method for preparing a large-size tantalum-aluminum alloy target assembly. Except for reducing the sintering densification temperature in step (3) to 350°C, the other steps and conditions are the same as in Example 1, so they will not be repeated here.

[0112] Testing revealed that the target diameter in the large-size tantalum-aluminum alloy target assembly obtained in this embodiment is 450mm, and the target purity is ≥4N.

[0113] Example 6

[0114] This embodiment provides a method for preparing a large-size tantalum-aluminum alloy target assembly. Except for reducing the solid-phase diffusion welding temperature in step (6) to 200°C, the other steps and conditions are the same as in embodiment 1, so they will not be repeated here.

[0115] Testing revealed that the target diameter in the large-size tantalum-aluminum alloy target assembly obtained in this embodiment is 450mm, and the target purity is ≥4N.

[0116] Comparative Example 1

[0117] This comparative example provides a method for preparing a large-size tantalum-aluminum alloy target assembly. Except for the absence of an aluminum intermediate layer between the tantalum-aluminum alloy target blank and the back plate in step (5), the other steps and conditions are the same as in Example 1, so they will not be repeated here.

[0118] Comparative Example 2

[0119] This comparative example provides a method for preparing a large-size tantalum-aluminum alloy target assembly. Except that steps (5) to (6) are replaced with the traditional indium soldering process, i.e., indium solder is evenly laid between the tantalum-aluminum alloy target blank and the copper alloy back plate, the solder is heated to a molten state and then the target blank and the back plate are fastened together, and the target assembly is obtained after cooling. The remaining steps and conditions are the same as in Example 1, so they will not be described in detail here.

[0120] The target density, welding strength, and welding bonding rate of the target components obtained in Examples 1-6 and Comparative Examples 1-2 were tested respectively. The relevant test results are detailed in Table 1 below.

[0121] Table 1

[0122]

[0123] As can be seen, this invention precisely suppresses the large-scale precipitation of brittle TaAl3 phase through sintering densification, significantly improving the density of the billet, resulting in a uniform microstructure without segregation or loose pores, and significantly improving the toughness of the billet. This greatly reduces the risk of edge chipping and cracking during machining and transportation. Furthermore, solid-phase diffusion welding achieves a tight bond between the target material and the backing plate, with welding strength far exceeding the mechanical interlocking strength of indium soldering, and no defects such as delamination, voids, or microcracks. Ultimately, a tantalum-aluminum alloy target material with a diameter ≥400mm was successfully prepared, and its purity stably reached 4N or higher, filling the gap in the mass production of large-size high-purity TaAl targets in China.

[0124] 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 for preparing a large-size tantalum-aluminum alloy target assembly, characterized in that, The preparation method includes the following steps: (1) Tantalum powder and aluminum powder are mixed evenly to obtain alloy powder; (2) The alloy powder is loaded into a flexible mold and cold isostatically pressed to obtain an alloy green billet; (3) The alloy green billet is encapsulated in a metal sleeve and then subjected to vacuum degassing and sintering densification in sequence to obtain a densified billet; (4) Remove the cladding of the densified billet, and then machine the billet to obtain a tantalum-aluminum alloy target billet of a preset size; (5) An aluminum intermediate layer is provided between the tantalum-aluminum alloy target blank and the back plate. After assembly, the casing welding and vacuum degassing are performed in sequence. (6) The degassed assembly is subjected to solid-phase diffusion welding, the welded casing is removed, and the large-size tantalum-aluminum alloy target assembly is obtained after machining. The target diameter in the large-size tantalum-aluminum alloy target assembly is ≥400mm, and the target purity is ≥4N.

2. The method for preparing the large-size tantalum-aluminum alloy target assembly according to claim 1, characterized in that, The tantalum powder in step (1) has a purity ≥99.99% and a particle size ≤100μm; And / or, the aluminum powder in step (1) has a purity of ≥99.99% and a particle size of 20~25μm; And / or, the molar ratio of tantalum to aluminum in the alloy powder of step (1) is (0.5~1.5):

1.

3. The method for preparing the large-size tantalum-aluminum alloy target assembly according to claim 1 or 2, characterized in that, The mixing in step (1) is carried out in a three-dimensional powder mixer; And / or, the mixing speed in step (1) is 13~20 rpm; And / or, the mixing time in step (1) is 40~50h.

4. The method for preparing the large-size tantalum-aluminum alloy target assembly according to claim 1 or 2, characterized in that, The flexible mold in step (2) includes a polyester sleeve. The mold assembly process is carried out in three equal batches to control the compaction density ≥50% and the mold assembly height deviation ≤2mm. And / or, the pressure of cold isostatic pressing in step (2) is 200~300MPa; And / or, the holding time for cold isostatic pressing in step (2) is ≥15 min; And / or, the pressure relief rate of the cold isostatic pressing in step (2) is ≤5MPa / min.

5. The method for preparing the large-size tantalum-aluminum alloy target assembly according to claim 1 or 2, characterized in that, The metal sheath in step (3) includes a stainless steel sheath; And / or, the degassing temperature of the vacuum degassing in step (3) is 400~500℃, and the vacuum degree is not less than 5×10 -3 Pa.

6. The method for preparing the large-size tantalum-aluminum alloy target assembly according to claim 1 or 2, characterized in that, The sintering densification process described in step (3) is carried out in a hot isostatic pressing apparatus; And / or, the sintering temperature for densification in step (3) is 400~600℃ and the sintering pressure is ≥100MPa.

7. The method for preparing the large-size tantalum-aluminum alloy target assembly according to claim 1 or 2, characterized in that, The thickness of the aluminum interlayer in step (5) is 0.3~0.5mm; And / or, the material of the backplate in step (5) includes any one of oxygen-free copper, copper alloy, molybdenum alloy or aluminum alloy.

8. The method for preparing the large-size tantalum-aluminum alloy target assembly according to claim 1 or 2, characterized in that, The solid-phase diffusion welding described in step (6) is performed in a hot isostatic pressing (HIP) apparatus; And / or, the welding temperature of the solid-phase diffusion welding in step (6) is 250~500℃.

9. A large-size tantalum-aluminum alloy target assembly prepared by the method described in any one of claims 1 to 8, comprising a tantalum-aluminum alloy target and a backplate welded together, characterized in that, The tantalum-aluminum alloy target has a diameter ≥400mm and a purity ≥4N.

10. An application of the large-size tantalum-aluminum alloy target assembly as described in claim 9, characterized in that, The large-size tantalum-aluminum alloy target assembly is used for magnetron sputtering of TaAl thin films.

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