Preparation method of tantalum-aluminum alloy sputtering target material

Abstract

The invention provides a preparation method of a tantalum-aluminum alloy sputtering target material, and the preparation method comprises the following steps: sequentially carrying out cold isostatic pressing, vacuum degassing, hot isostatic pressing and machining on mixed powder obtained by mixing tantalum powder and aluminum powder to obtain the tantalum-aluminum alloy sputtering target material. According to the method, the compactness of the tantalum-aluminum green body can be improved, the phenomenon that powder is pumped out in the vacuum degassing process is avoided, meanwhile, the deformation in the hot isostatic pressing process is reduced, the machining allowance is reduced, materials are saved, particularly, the use amount of expensive tantalum powder is reduced, and the cost can be saved; by adopting the preparation method disclosed by the invention, the tantalum-aluminum alloy sputtering target material of which the density is greater than or equal to 99% can be prepared.

Description

Technical Field

[0001] The present invention relates to the technical field of tantalum-aluminum alloy sputtering targets, and particularly relates to a preparation method of a tantalum-aluminum alloy sputtering target. Background Art

[0002] Physical Vapour Deposition (PVD) refers to, under vacuum conditions, adopting an arc discharge technology with low voltage and high current, using gas discharge to evaporate the material source and ionize both the evaporated substance and the gas, and then through the acceleration of the electric field, depositing the evaporated substance and its reaction products on the workpiece to form a thin film with a special function. The PVD technology is the core technology in various industries such as semiconductor chip manufacturing, solar energy industry, and LCD manufacturing. The main methods include vacuum evaporation, arc plasma plating, ion plating, molecular beam epitaxy, and sputtering coating, etc.

[0003] Sputtering is one of the main technologies for preparing thin film materials. It uses ions generated by an ion source, which are accelerated and aggregated in a vacuum to form an ion beam with high kinetic energy, bombarding the solid surface. The ions and the atoms on the solid surface exchange kinetic energy, causing the atoms on the solid surface to leave the solid and deposit on the substrate surface. The solid being bombarded is the raw material for preparing the thin film by sputtering method, and is generally called a sputtering target.

[0004] Sputtering targets are generally obtained through a powder metallurgy sintering and forming process. Because the sputtering targets prepared by this process have unique chemical compositions and mechanical and physical properties, which cannot be obtained by traditional casting methods. The powder metallurgy sintering and forming process is divided into two methods: hot press sintering and hot isostatic pressing. Hot press sintering means filling dry powder into a mold and then heating while applying pressure from a single axial direction to complete forming and sintering simultaneously. Hot isostatic pressing means placing the product in a sealed container and then applying equal pressure in all directions while applying high temperature. Under the action of high temperature and high pressure, the product is sintered and densified.

[0005] In the fields of materials science and engineering, metal material preparation technology, and target manufacturing technology, tantalum-aluminum alloy sputtering targets are an important material and are widely used in high-tech fields such as electronics, aerospace, and military. The existing preparation method of tantalum-aluminum alloy sputtering targets is mainly to mix tantalum powder and aluminum powder, and then directly load them into a stainless steel jacket for hot isostatic pressing (HIP). This method has the following problems: 1) During the degassing process of the jacket, due to the low initial density of the powder, the powder is easily sucked away, leaving pits, resulting in uneven density of the target. After powder agglomeration and sintering, mottling appears, affecting the quality of the target; 2) Deformation is likely to occur during the HIP process. Due to the low density of the powder in the mold, the jacket shrinks greatly during the HIP process, with a risk of suction through. At the same time, the surface of the target after HIP is uneven and has a large undulation, with a flatness of 5-6 mm, requiring a large amount of machining allowance to be reserved, resulting in material waste.

[0006] CN 111945121 A discloses a tantalum-aluminum alloy sputtering target and its preparation method. The preparation method includes: mixing tantalum powder and aluminum powder, loading them into a jacket for degassing and then performing two-stage HIP treatment. After sintering, the product has a large deformation and a large machining allowance, resulting in material waste. Moreover, performing two-stage HIP consumes a large amount of energy and has a high cost, which is not conducive to large-scale production.

[0007] CN 112111714 A discloses a preparation method of a tantalum-aluminum alloy sputtering target. The preparation method includes: mixing tantalum powder and aluminum powder, then loading them into a mold and sealing it, and performing hot press sintering treatment at 1050-1150 °C, and obtaining the tantalum-aluminum alloy sputtering target through machining. However, the temperature of hot press sintering is relatively high, consuming a large amount of energy and having a high cost, which is not conducive to large-scale production.

[0008] In summary, it is necessary to develop a new preparation method for tantalum-aluminum alloy sputtering targets. Summary of the Invention

[0009] In view of the problems existing in the prior art, the present invention provides a preparation method for tantalum-aluminum alloy sputtering targets. The preparation method includes: successively performing cold isostatic pressing, vacuum degassing, hot isostatic pressing, and machining on the mixed powder after mixing tantalum powder and aluminum powder to obtain the tantalum-aluminum alloy sputtering target. By first performing cold isostatic pressing and then hot isostatic pressing, the present invention can improve the density of the tantalum-aluminum green body, avoid the phenomenon of powder being extracted during the vacuum degassing process, reduce the deformation amount during the hot isostatic pressing process, reduce the machining allowance, save materials, especially reduce the usage of expensive tantalum powder, and can save costs; using the preparation method of the present invention, a tantalum-aluminum alloy sputtering target with a density ≥ 99% can be prepared.

[0010] To achieve this purpose, the present invention adopts the following technical solutions:

[0011] The object of the present invention is to provide a method for preparing a tantalum-aluminum alloy sputtering target, and the preparation method comprises the following steps:

[0012] (1) Mix tantalum powder and aluminum powder according to a target mass ratio to obtain a mixed powder;

[0013] (2) Load the mixed powder obtained in step (1) into a mold and seal it, perform cold isostatic pressing, and obtain a green body of tantalum-aluminum alloy after demolding;

[0014] (3) Load the green body of tantalum-aluminum alloy obtained in step (2) into a jacket and seal it, successively perform vacuum degassing and hot isostatic pressing, and perform machining after removing the jacket to obtain a tantalum-aluminum alloy sputtering target.

[0015] The preparation method of the present invention includes: performing cold isostatic pressing, vacuum degassing, hot isostatic pressing, and machining on the mixed powder after mixing tantalum powder and aluminum powder in sequence to obtain a tantalum-aluminum alloy sputtering target. By first performing cold isostatic pressing and then hot isostatic pressing, the present invention can improve the density of the green body of tantalum-aluminum alloy, avoid the phenomenon that the powder is extracted during the vacuum degassing process, reduce the deformation amount during the hot isostatic pressing process, reduce the machining allowance, save materials, especially reduce the usage amount of expensive tantalum powder, and can save costs; by using the preparation method of the present invention, a tantalum-aluminum alloy sputtering target with a density ≥ 99% can be prepared.

[0016] As a preferred technical solution of the present invention, in step (1), the purity of the tantalum powder ≥ 3N5, and the particle size < 100 μm.

[0017] Preferably, in step (1), the purity of the aluminum powder ≥ 4N, and the particle size < 25 μm.

[0018] As a preferred technical solution of the present invention, in step (1), the target mass ratio is: the mass ratio of the aluminum powder is 10 - 20 wt%, such as 10 wt%, 11 wt%, 13 wt%, 15 wt%, 17 wt%, 18 wt% or 20 wt%, and the rest is tantalum powder.

[0019] As a preferred technical solution of the present invention, in step (1), the powder mixing is carried out in an argon atmosphere, and the air pressure is 0.02 - 0.09 MPa, such as 0.02 MPa, 0.03 MPa, 0.04 MPa, 0.05 MPa, 0.06 MPa, 0.07 MPa, 0.08 MPa or 0.09 MPa, etc.

[0020] Preferably, in step (1), the powder mixing time ≥ 48 h.

[0021] In the present invention, through the powder mixing operation, it can be ensured that the tantalum-aluminum alloy powder is uniformly mixed, so that the components of the product after HIP sintering are uniform.

[0022] As a preferred technical solution of the present invention, in step (2), the mold is a polyurethane rubber sleeve.

[0023] Preferably, in step (2), a pressing plate is placed on each of the upper and lower sides of the mixed powder to ensure the flatness of the obtained green tantalum-aluminum compact. Because the two pressing plates on the upper and lower surfaces of the mixed powder can simultaneously apply pressure to the mixed powder during the cold isostatic pressing process, so that the upper and lower surfaces of the mixed powder are compacted everywhere at the same time, ensuring flatness.

[0024] Preferably, the pressing plate is a stainless steel plate with a thickness of 15-25 mm, such as 15 mm, 17 mm, 18 mm, 20 mm, 21 mm, 23 mm or 25 mm, etc.

[0025] As a preferred technical solution of the present invention, in step (2), the pressure of the cold isostatic pressing is 150-250 MPa, such as 150 MPa, 170 MPa, 180 MPa, 200 MPa, 220 MPa, 230 MPa or 250 MPa, and the time is 10-25 min, such as 10 min, 12 min, 15 min, 17 min, 20 min, 23 min or 25 min, etc.

[0026] Preferably, in step (2), the density of the green tantalum-aluminum compact is 80-90%, such as 80%, 81%, 83%, 85%, 87%, 89% or 90%, etc., and the flatness < 0.5 mm.

[0027] Generally, through cold isostatic pressing, the density of the tantalum-aluminum mixed powder can be increased from the initial 40-50% to 80-90%.

[0028] As a preferred technical solution of the present invention, in step (3), the degassing temperature of the vacuum degassing is 200-350 °C, such as 200 °C, 230 °C, 250 °C, 270 °C, 300 °C, 310 °C, 330 °C or 350 °C, etc., the heat preservation time is 4-8 h, such as 4 h, 4.5 h, 5 h, 5.5 h, 6 h, 6.5 h, 7 h, 7.5 h or 8 h, etc., and the target vacuum degree is below 5.0E-3 Pa.

[0029] As a preferred technical solution of the present invention, in step (3), the hot isostatic pressing includes: first heating to 200 - 300 °C, such as 200 °C, 210 °C, 230 °C, 250 °C, 270 °C, 290 °C or 300 °C, etc., holding for 1 - 1.5 h, such as 1 h, 1.1 h, 1.2 h, 1.3 h, 1.4 h or 1.5 h, etc., then heating and pressurizing simultaneously, at 450 - 550 °C, such as 450 °C, 470 °C, 480 °C, 500 °C, 510 °C, 530 °C or 550 °C, etc., and under 90 - 170 MPa, such as 90 MPa, 100 MPa, 110 MPa, 120 MPa, 130 MPa, 140 MPa, 150 MPa, 160 MPa or 170 MPa, etc., holding for 3 - 6 h, such as 3 h, 3.5 h, 4 h, 4.5 h, 5 h, 5.5 h or 6 h, etc.

[0030] As a preferred technical solution of the present invention, in step (3), after removing the jacket and before machining, the flatness of the upper and lower surfaces of the obtained tantalum-aluminum target is < 1 mm.

[0031] Preferably, in step (3), the machining includes: through grinding and / or wire cutting, machining to the required size.

[0032] As a preferred technical solution of the present invention, the preparation method includes the following steps:

[0033] (1) Prepare tantalum powder with a purity ≥ 3N5 and a particle size < 100 μm, prepare aluminum powder with a purity ≥ 4N and a particle size < 25 μm, mix the tantalum powder and the aluminum powder according to the mass ratio of the aluminum powder being 10 - 20 wt%, control the powder mixing to be carried out in an argon atmosphere, the air pressure is 0.02 - 0.09 MPa, and the powder mixing time ≥ 48 h to obtain a mixed powder;

[0034] (2) Put the mixed powder obtained in step (1) into a polyurethane rubber sleeve, and place a stainless steel plate with a thickness of 15 - 25 mm on each of the upper and lower sides of the mixed powder to ensure the flatness of the obtained tantalum-aluminum green body, then seal and perform cold isostatic pressing, control the pressure of the cold isostatic pressing to be 150 - 250 MPa, the time is 10 - 25 min, and after demolding, obtain a tantalum-aluminum green body, the density of the tantalum-aluminum green body is 80 - 90%, and the flatness < 0.5 mm;

[0035] (3) Load the tantalum-aluminum green compact obtained in step (2) into a stainless-steel jacket and seal it by welding. Place the welded stainless-steel jacket into a heating furnace for vacuum degassing. The degassing temperature for the vacuum degassing is 200 - 350 °C, and the holding time is 4 - 8 h until the vacuum degree reaches the target vacuum degree of below 5.0E-3 Pa, then end the degassing. Load the degassed jacket into a hot isostatic pressing furnace. After cold-state pressure boosting and sintering, first heat up to 200 - 300 °C and hold for 1 - 1.5 h, then heat up and pressurize simultaneously. Hold and pressurize at 450 - 550 °C and 90 - 170 MPa for 3 - 6 h. After the holding ends, remove the jacket to obtain a tantalum-aluminum target with a flatness of the upper and lower surfaces < 1 mm. Through machining, a tantalum-aluminum alloy sputtering target with the required dimensions is obtained.

[0036] Compared with the prior art solutions, the present invention has at least the following beneficial effects:

[0037] (1) The present invention provides a method for preparing a tantalum-aluminum alloy sputtering target. The preparation method includes: subjecting the mixed powder obtained by mixing tantalum powder and aluminum powder to cold isostatic pressing, vacuum degassing, hot isostatic pressing, and machining in sequence to obtain a tantalum-aluminum alloy sputtering target. By first performing cold isostatic pressing and then hot isostatic pressing, the present invention can improve the density of the tantalum-aluminum green compact, avoid the phenomenon of powder being extracted during the vacuum degassing process, reduce the deformation amount during the hot isostatic pressing process, reduce the machining allowance, save materials, especially reduce the usage of expensive tantalum powder, and thus can save costs; by using the preparation method of the present invention, a tantalum-aluminum alloy sputtering target with a density ≥ 99% can be prepared;

[0038] (2) During the cold isostatic pressing process of the preparation method of the present invention, a pressing plate is placed on each of the upper and lower sides of the mixed powder, which can apply pressure to the mixed powder simultaneously during the cold isostatic pressing process, so that the upper and lower surfaces of the mixed powder are compacted everywhere at the same time, which can not only ensure the density but also ensure the flatness, effectively avoid the problem of powder being sucked away during the subsequent vacuum degassing process, and can also reduce the deformation amount after the subsequent hot isostatic pressing. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 is a flow chart of the method for preparing the tantalum-aluminum alloy sputtering target of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0040] The technical solution of the present invention will be further described below with reference to the drawings and through specific embodiments.

[0041] The present invention provides a method for preparing a tantalum-aluminum alloy sputtering target, as Figure 1 shown, the preparation method includes the following steps:

[0042] (1) Mix tantalum powder and aluminum powder according to the target mass ratio to obtain a mixed powder;

[0043] (2) Load the mixed powder described in step (1) into a mold and seal it, then perform cold isostatic pressing (CIP). After demolding, a tantalum-aluminum green compact is obtained;

[0044] (3) Load the tantalum-aluminum green compact obtained in step (2) into a jacket and weld it shut. Then, successively perform vacuum degassing and hot isostatic pressing (HIP). After removing the jacket, perform machining to obtain a tantalum-aluminum alloy sputtering target.

[0045] To better illustrate the present invention and facilitate understanding of its technical solution, the typical but non-limiting embodiments of the present invention are as follows:

[0046] Example 1

[0047] This example provides a method for preparing a tantalum-aluminum alloy sputtering target, and the preparation method includes the following steps:

[0048] (1) Prepare tantalum powder with a purity ≥ 3N5 and a particle size < 100 μm, and prepare aluminum powder with a purity ≥ 4N and a particle size < 25 μm. Mix the tantalum powder and aluminum powder with the mass ratio of aluminum powder being 15 wt%. Control the mixing to be carried out in an argon atmosphere with a pressure of 0.05 MPa and a mixing time of 50 h to obtain a mixed powder;

[0049] (2) Load the mixed powder described in step (1) into a polyurethane rubber sleeve, and place a 20-mm-thick stainless steel plate on each of the upper and lower sides of the mixed powder to ensure the flatness of the obtained tantalum-aluminum green compact. Then seal it and perform cold isostatic pressing. Control the pressure of the cold isostatic pressing to be 200 MPa and the time to be 15 min. After demolding, a tantalum-aluminum green compact is obtained. After testing, the density of the tantalum-aluminum green compact is 85%, and the flatness is 0.43 mm;

[0050] (3) Load the tantalum-aluminum green compact obtained in step (2) into a stainless steel jacket and seal it by welding. Place the welded stainless steel jacket in a heating furnace for vacuum degassing treatment. The degassing temperature of the vacuum degassing is 250 °C, and the holding time is 5 h until the vacuum degree reaches the target vacuum degree below 5.0E-3 Pa, and then end the degassing. Load the degassed jacket into a hot isostatic pressing furnace. After cold-state pressurized sintering, first heat up to 250 °C and hold for 1 h, then heat up and pressurize simultaneously. Hold and pressurize at 500 °C and 120 MPa for 4 h. After the holding ends, remove the jacket to obtain a tantalum-aluminum target with a flatness of 0.75 mm on both the upper and lower surfaces and a density of 99.4%. After machining, a tantalum-aluminum alloy sputtering target with required dimensions is obtained.

[0051] Example 2

[0052] This embodiment provides a method for preparing a tantalum-aluminum alloy sputtering target, and the preparation method includes the following steps:

[0053] (1) Prepare tantalum powder with a purity ≥ 3N5 and a particle size < 100 μm, and prepare aluminum powder with a purity ≥ 4N and a particle size < 25 μm. Mix the tantalum powder and the aluminum powder according to the mass ratio of the aluminum powder being 10 wt%, control the powder mixing to be carried out in an argon atmosphere, with a gas pressure of 0.02 MPa and a powder mixing time of 50 h to obtain a mixed powder;

[0054] (2) Load the mixed powder obtained in step (1) into a polyurethane rubber sleeve, and place a stainless steel plate with a thickness of 20 mm on each of the upper and lower sides of the mixed powder to ensure the flatness of the obtained tantalum-aluminum green body, and then seal it and perform cold isostatic pressing. Control the pressure of the cold isostatic pressing to be 150 MPa and the time to be 15 min. After demolding, obtain a tantalum-aluminum green body, and the density of the tantalum-aluminum green body is 80%, and the flatness is 0.60 mm;

[0055] (3) Load the tantalum-aluminum green body obtained in step (2) into a stainless steel jacket and seal it by welding. Place the welded stainless steel jacket in a heating furnace for vacuum degassing treatment. The degassing temperature of the vacuum degassing is 200 °C, and the holding time is 4 h until the vacuum degree reaches the target vacuum degree below 5.0E-3 Pa, and then end the degassing. Load the degassed jacket into a hot isostatic pressing furnace. After cold-state pressure boosting sintering, first heat up to 200 °C and hold for 1 h, then heat up and pressurize simultaneously, hold and pressurize at 450 °C and 90 MPa for 3 h. After the holding is completed, remove the jacket to obtain a tantalum-aluminum target with a flatness of 0.95 mm on both the upper and lower surfaces, a density of 99.1%. After machining, obtain a tantalum-aluminum alloy sputtering target with required dimensions.

[0056] Example 3

[0057] This embodiment provides a method for preparing a tantalum-aluminum alloy sputtering target, and the preparation method includes the following steps:

[0058] (1) Prepare tantalum powder with a purity ≥ 3N5 and a particle size < 100 μm, and prepare aluminum powder with a purity ≥ 4N and a particle size < 25 μm. Mix the tantalum powder and the aluminum powder according to the mass ratio of the aluminum powder being 20 wt%, control the powder mixing to be carried out in an argon atmosphere, with a gas pressure of 0.09 MPa and a powder mixing time of 50 h to obtain a mixed powder;

[0059] (2) Load the mixed powder obtained in step (1) into a polyurethane rubber sleeve, and place a stainless steel plate with a thickness of 20 mm on each of the upper and lower sides of the mixed powder to ensure the flatness of the obtained tantalum-aluminum green body, and then seal it and perform cold isostatic pressing. Control the pressure of the cold isostatic pressing to be 250 MPa and the time to be 15 min. After demolding, obtain a tantalum-aluminum green body, and the density of the tantalum-aluminum green body is 90%, and the flatness is 0.45 mm;

[0060] (3) Load the tantalum-aluminum green compact obtained in step (2) into a stainless-steel jacket and seal it by welding. Place the welded stainless-steel jacket in a heating furnace for vacuum degassing. The degassing temperature for the vacuum degassing is 350 °C, and the holding time is 8 h until the vacuum degree reaches the target vacuum degree of below 5.0E-3 Pa. Then, end the degassing. Place the degassed jacket in a hot isostatic pressing furnace. After cold-state pressure boosting and sintering, first heat up to 300 °C and hold for 1 h, then heat up and pressurize simultaneously. Hold and pressurize at 550 °C and 170 MPa for 6 h. After the holding ends, remove the jacket to obtain a tantalum-aluminum target with a flatness of 0.80 mm for the upper and lower surfaces, a relative density of 99.2%. After machining, a tantalum-aluminum alloy sputtering target with required dimensions is obtained.

[0061] Example 4

[0062] This example provides a method for preparing a tantalum-aluminum alloy sputtering target. Compared with Example 1, the difference is only that: the two stainless-steel plates in step (2) are completely omitted, that is, the mixed powder described in step (1) is loaded into a polyurethane rubber sleeve and directly sealed for cold isostatic pressing; after testing, the relative density of the tantalum-aluminum green compact obtained in step (2) is 84%, and the flatness is 1.20 mm. The relative density of the tantalum-aluminum target obtained in step (3) is 99.2%, and the flatness is 3.00 mm.

[0063] Example 5

[0064] This example provides a method for preparing a tantalum-aluminum alloy sputtering target. Compared with Example 1, the difference is only that: in step (3), the target temperature of hot isostatic pressing is 400 °C, that is, hold and pressurize at 400 °C and 120 MPa for 4 h. After the holding ends, remove the jacket; after testing, the relative density of the tantalum-aluminum green compact obtained in step (2) is 85%, and the flatness is 0.44 mm. The relative density of the tantalum-aluminum target obtained in step (3) is 97.8%, and the flatness is 0.80 mm.

[0065] Example 6

[0066] This example provides a method for preparing a tantalum-aluminum alloy sputtering target. Compared with Example 1, the difference is only that: in step (3), the target temperature of hot isostatic pressing is 600 °C, that is, hold and pressurize at 600 °C and 120 MPa for 4 h. After the holding ends, remove the jacket; after testing, the relative density of the tantalum-aluminum green compact obtained in step (2) is 86%, and the flatness is 0.43 mm. The relative density of the tantalum-aluminum target obtained in step (3) is 99.5%, and the flatness is 0.78 mm.

[0067] Comparative Example 1

[0068] This comparative example provides a method for preparing a tantalum-aluminum alloy sputtering target. Compared with Example 1, the only difference is that the cold isostatic pressing in step (2) is completely omitted; the specific content is as follows: The mixed powder in step (1) is directly loaded into a stainless steel jacket and sealed by welding, and then vacuum degassing treatment and hot isostatic pressing are carried out in sequence. After removing the jacket, machining is carried out to obtain a tantalum-aluminum alloy sputtering target; after testing, the density of the obtained tantalum-aluminum target is 95.0%, and the flatness is 5.20 mm.

[0069] The detection results of the density and flatness obtained from the above examples and comparative examples are summarized in Table 1.

[0070] Table 1

[0071]

[0072] Note: " / " in the table indicates that the relevant detection was not carried out.

[0073] It can be seen from Table 1 that:

[0074] (1) For the method for preparing the tantalum-aluminum alloy sputtering target of the present invention, cold isostatic pressing is carried out first, and then hot isostatic pressing, which can improve the density of the tantalum-aluminum green body, avoid the phenomenon that the powder is extracted during the vacuum degassing process, and at the same time reduce the deformation amount during the hot isostatic pressing process, reduce the machining allowance, save materials, especially reduce the consumption of expensive tantalum powder, and can save costs; by using the preparation method of the present invention, a tantalum-aluminum alloy sputtering target with a density ≥ 99% can be prepared;

[0075] (2) Comparing Example 1 with Example 4, since two stainless steel plates in step (2) are completely omitted in Example 4, that is, the mixed powder in step (1) is loaded into a polyurethane rubber sleeve and directly sealed for cold isostatic pressing. Although the density of the tantalum-aluminum green body meets the standard and a tantalum-aluminum alloy sputtering target with a density ≥ 99% can be finally prepared, during the cold isostatic pressing process, it is impossible to ensure that the upper and lower surfaces of the mixed powder are simultaneously compacted everywhere, resulting in a flatness of up to 1.20 mm for the tantalum-aluminum green body obtained by cold isostatic pressing, and the flatness of the tantalum-aluminum target obtained after hot isostatic pressing increases to 3.00 mm;

[0076] (3) Comparing Example 1 with Examples 5 and 6, since the target temperature of hot isostatic pressing in step (3) is reduced to 400 °C in Example 5, the density of the tantalum-aluminum target obtained after hot isostatic pressing is only 97.8%. Since the target temperature of hot isostatic pressing in step (3) is increased to 600 °C in Example 6, although the density is basically not affected, it will cause abnormal grain growth in the product target, and even result in poor phenomena such as the product being hard and brittle and easy to crack, and will also cause an increase in energy consumption;

[0077] (4) Comparing Example 1 with Comparative Example 1, since Comparative Example 1 completely omits cold isostatic pressing, it will not only cause the problem that the powder is extracted during vacuum degassing, but also cause the tantalum-aluminum target obtained after hot isostatic pressing to be severely deformed, with the surface of the target being uneven, having large undulations, a flatness of 5 - 6 mm, and requiring a large machining allowance, resulting in material waste.

[0078] The present invention illustrates the detailed structural features of the present invention through the above embodiments, but the present invention is not limited to the above detailed structural features, that is, it does not mean that the present invention must rely on the above detailed structural features to be implemented. Those skilled in the art should understand that any improvement to the present invention, the equivalent replacement of the components selected by the present invention, the addition of auxiliary components, and the selection of specific methods, etc., all fall within the protection scope and the disclosure scope of the present invention.

[0079] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all belong to the protection scope of the present invention.

[0080] In addition, it should be noted that, in the above specific embodiments, the various specific technical features described can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, the present invention will not separately describe various possible combination methods.

[0081] Furthermore, any combination can be made between various different embodiments of the present invention as long as it does not violate the idea of the present invention, and it should also be regarded as the content disclosed by the present invention.

Claims

1. A method for preparing a tantalum-aluminum alloy sputtering target, characterized in that: The preparation method comprises the following steps: (1) mixing tantalum powder and aluminum powder according to a target mass ratio to obtain a mixed powder; (2) placing the mixed powder described in step (1) into a mold and sealing the mold, performing cold isostatic pressing, and obtaining a tantalum-aluminum green body after demolding; (3) The tantalum-aluminum green body obtained in step (2) is placed in a package and sealed, and then subjected to vacuum degassing and hot isostatic pressing in sequence. After the package is removed, the green body is machined to obtain a tantalum-aluminum alloy sputtering target.

2. The preparation method according to claim 1, characterized in that: In step (1), the purity of the tantalum powder is ≥3N5, and the particle size is <100 μm; Preferably, in step (1), the purity of the aluminum powder is ≥4N and the particle size is <25 μm.

3. The preparation method according to claim 1 or 2, characterized in that: In step (1), the target mass ratio is: the mass proportion of aluminum powder is 10-20wt%, and the rest is tantalum powder.

4. The preparation method according to any one of claims 1 to 3, characterized in that In step (1), the powder mixing is carried out under an argon atmosphere with a pressure of 0.02-0.09 MPa; Preferably, in step (1), the mixing time of the powder is ≥ 48 h.

5. The preparation method according to any one of claims 1 to 4, characterized in that: In step (2), a pressing plate is placed above and below the mixed powder to ensure the flatness of the obtained tantalum aluminum green body; Preferably, the pressing plate is a stainless steel plate with a thickness of 15-25 mm.

6. The preparation method according to any one of claims 1 to 5, characterized in that: In step (2), the cold isostatic pressing pressure is 150-250 MPa and the time is 10-25 min; Preferably, in step (2), the density of the tantalum aluminum green body is 80-90%, and the flatness is less than 0.5 mm.

7. The preparation method according to any one of claims 1 to 6, characterized in that: In step (3), the degassing temperature of the vacuum degassing is 200-350°C, the holding time is 4-8h, and the target vacuum degree is below 5.0E-3Pa.

8. The preparation method according to any one of claims 1 to 7, characterized in that: In step (3), the hot isostatic pressing includes: first heating to 200-300°C and keeping the temperature for 1-1.5 hours, then heating and pressurizing at 450-550°C and 90-170MPa for 3-6 hours.

9. The preparation method according to any one of claims 1 to 8, characterized in that: In step (3), after removing the jacket and before machining, the flatness of the upper and lower surfaces of the obtained tantalum aluminum target is less than 1 mm; Preferably, in step (3), the machining includes: machining to a required size through grinding and / or wire cutting.

10. The preparation method according to any one of claims 1 to 9, characterized in that: The preparation method comprises the following steps: (1) preparing tantalum powder with a purity of ≥3N5 and a particle size of <100 μm, preparing aluminum powder with a purity of ≥4N and a particle size of <25 μm, mixing the tantalum powder and the aluminum powder according to the mass ratio of the aluminum powder being 10-20 wt%, controlling the mixing to be carried out under an argon atmosphere with a gas pressure of 0.02-0.09 MPa, and mixing for a time of ≥48 h to obtain a mixed powder; (2) The mixed powder of step (1) is loaded into a polyurethane rubber sleeve, and a stainless steel plate with a thickness of 15-25 mm is placed above and below the mixed powder to ensure the flatness of the obtained tantalum aluminum green body, and then the sleeve is sealed for cold isostatic pressing, and the cold isostatic pressing pressure is controlled to be 150-250 MPa, and the time is 10-25 min. After demolding, a tantalum aluminum green body is obtained, and the density of the tantalum aluminum green body is 80-90%, and the flatness is less than 0.5 mm; (3) The tantalum-aluminum green body obtained in step (2) is placed in a stainless steel sheath and sealed by welding. The welded stainless steel sheath is placed in a heating furnace for vacuum degassing. The degassing temperature of the vacuum degassing is 200-350°C and the holding time is 4-8h, until the vacuum degree reaches the target vacuum degree below 5.0E-3Pa. Then the degassing is terminated. The degassed sheath is placed in a hot isostatic pressing furnace. After cold pressurized sintering, the temperature is first increased to 200-300°C and kept warm for 1-1.5h. Then the temperature is increased while pressurized. The temperature is kept warm and the pressure is kept warm at 450-550°C and 90-170MPa for 3-6h. After the holding period is completed, the sheath is removed to obtain a tantalum-aluminum target with a flatness of less than 1mm on the upper and lower surfaces. After machining, a tantalum-aluminum alloy sputtering target with the required size is obtained.

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