Preparation method of aluminum alloy sputtering target material

Abstract

The invention relates to a preparation method of an alloy sputtering target material. The preparation method comprises the following steps: (1) carrying out suspension smelting on a mixture of metal scandium and metal aluminum in a vacuum environment, and then carrying out water cooling to obtain a cast-molded aluminum-scandium alloy ingot; and (2) carrying out solution treatment on the aluminum-scandium alloy cast ingot, sealing the aluminum-scandium alloy cast ingot into a sheath, vacuumizing the sheath, and carrying out hot rolling with the sheath. The preparation method is easy to operate and low in cost, and the prepared aluminum alloy sputtering target material is high in purity, uniform in component, high in density and good in sputtering effect.

Description

Technical Field

[0001] This invention relates to the field of alloy target preparation technology, and in particular to a method for preparing an aluminum alloy sputtering target. Background Technology

[0002] Aluminum-scandium alloy sputtering targets are key materials for preparing aluminum-scandium alloy thin films and aluminum-scandium nitride thin films, and are widely used in advanced packaging and heat dissipation, ferroelectric memory devices, and radio frequency filter chips. However, the preparation of aluminum-scandium alloy sputtering targets is prone to problems such as low purity, poor density, and uneven composition. To address these issues, researchers have been exploring various methods for preparing aluminum-scandium alloy sputtering targets.

[0003] CN110093588B discloses a fine-grained aluminum-scandium alloy target, its preparation method, and its application. The fine-grained aluminum-scandium alloy target is prepared by wet ball milling and slip casting, solving the problems of segregation and coarse grains in existing technologies. However, its powder preparation process is complex and easily introduces impurities, and the sintered target blank has problems such as lower density and higher oxygen content compared to the smelting process.

[0004] CN111455327A discloses a high-scandium-content aluminum-scandium alloy target and its preparation method. The method employs an alloying smelting-powder metallurgy-hot deformation processing process, obtaining the aluminum-scandium alloy through multiple smelting and ball milling processes, followed by pre-pressing and vacuum sintering, combined with hot forging, hot rolling, and finishing to ensure compositional uniformity and high density. This method combines multiple processes, making it complex. Furthermore, the material surface undergoes severe oxidation during hot forging and hot rolling, increasing the tendency to crack and significantly reducing the yield.

[0005] Existing technologies suffer from drawbacks such as complex powder preparation processes that easily introduce impurities, surface oxidation of materials, rolling cracking, and low density of finished target materials. Therefore, how to prepare aluminum-scandium alloy targets with high purity, uniform composition, and high density has become an urgent problem to be solved. Summary of the Invention

[0006] To address the aforementioned technical problems, this invention employs a suspension melting process to alloy aluminum and scandium, reducing the introduction of impurities. Water cooling reduces the diffusion window of scandium, minimizing segregation. Solution treatment ensures uniform distribution of precipitates, and vacuum-encapsulated hot rolling balances recrystallization and scandium diffusion. The synergistic effect of these multiple processes improves the microstructure of the aluminum-scandium alloy and enhances the overall performance of the material.

[0007] To achieve this objective, the present invention adopts the following technical solution:

[0008] In a first aspect, the present invention provides a method for preparing an aluminum alloy sputtering target, the method comprising the following steps:

[0009] (1) A mixture of metallic scandium and metallic aluminum is suspended and melted in a vacuum environment and then water-cooled to obtain a cast aluminum-scandium alloy ingot.

[0010] (2) After the aluminum-scandium alloy ingot is solution treated, it is sealed in a cladding. After the cladding is vacuumed, it is hot rolled with the cladding.

[0011] As a preferred embodiment of the present invention, the purity of the aluminum metal is ≥99.999%;

[0012] Preferably, the purity of the scandium metal is ≥99.95%.

[0013] As a preferred embodiment of the present invention, the scandium content of the aluminum-scandium alloy ingot is 10-30 wt%, for example, it can be 10 wt%, 15 wt%, 20 wt%, 25 wt%, or 30 wt%, etc.

[0014] As a preferred embodiment of the present invention, the vacuum degree of the vacuum environment in step (1) is 6×10⁻⁶. -3 -10×10 - 3 Pa, for example, could be 6 × 10 -3 Pa, 7×10 -3 Pa, 8×10 -3 Pa, 9×10 -3 Pa or 10×10 -3 Pa, etc.

[0015] As a preferred technical solution of the present invention, the suspension melting includes sequentially performing a first suspension melting and a second suspension melting.

[0016] Preferably, the suspension melting is sufficient to heat the alloy material to a molten state; no specific temperature limit is imposed on the suspension melting.

[0017] Preferably, the first suspension melting is performed by standing and refining for 5-20 minutes after the mixture has been completely melted, for example, 50 minutes, 10 minutes, 15 minutes, 18 minutes or 20 minutes.

[0018] Preferably, after the first suspension melting is completed, the mixture is cooled in the crucible and then turned into an ingot for the second suspension melting.

[0019] Preferably, the second suspension melting is carried out by standing and refining for 5-20 minutes after the mixture has been completely melted, for example, 50 minutes, 10 minutes, 15 minutes, 18 minutes or 20 minutes.

[0020] This invention employs two-stage suspension melting to further promote component diffusion, and improves the uniformity of the structure through static refining under vacuum, while removing inclusions and improving the uniformity and purity of the material.

[0021] As a preferred technical solution of the present invention, the water cooling includes rapidly pouring the second suspended smelting aluminum-scandium alloy melt into a water cooling mold.

[0022] Preferably, the material of the water-cooled mold includes copper.

[0023] Preferably, the temperature of the water-cooled mold is 20-30℃, for example, it can be 20℃, 22℃, 24℃, 26℃, 28℃ or 30℃, etc.

[0024] Preferably, the pouring speed of the rapid pouring is 100-200 L / min, for example, it can be 100 L / min, 120 L / min, 140 L / min, 160 L / min, 180 L / min or 200 L / min, etc.

[0025] Preferably, the cooling rate of the water cooling is 50-100℃ / s, for example, it can be 50℃ / s, 60℃ / s, 70℃ / s, 80℃ / s, 90℃ / s or 100℃ / s, etc.

[0026] As a preferred technical solution of the present invention, the solution treatment temperature is 500-600℃, for example, it can be 500℃, 520℃, 540℃, 560℃, 580℃ or 600℃, etc.

[0027] Preferably, the solution treatment time is 2-4 hours, for example, 2 hours, 2.5 hours, 3 hours, 3.5 hours followed by 4 hours, etc.

[0028] Preferably, the solution treatment is performed under an inert atmosphere.

[0029] The present invention further optimizes the temperature and time of the solution treatment within the above range to optimize the microstructure of the aluminum alloy sputtering target and promote the uniform distribution of the precipitated phase.

[0030] As a preferred technical solution of the present invention, step (2) involves evacuating the casing to a vacuum level of 1×10⁻⁶. -3 -5×10 -3 Pa, for example, could be 1×10 -3 Pa, 2×10 -3 Pa, 3×10 -3 Pa, 4×10 -3 Pa or 5×10 -3 Pa, etc.

[0031] The present invention uses a vacuum enclosure followed by sealing to ensure the vacuum level. The sealing method includes, but is not limited to, argon arc welding, and is not further limited here.

[0032] As a preferred technical solution of the present invention, the hot rolling temperature is 300-600℃, for example, it can be 300℃, 350℃, 400℃, 450℃, 500℃, 550℃ or 600℃, etc.

[0033] Preferably, the hot rolling process involves rotating 60° per pass, and the cumulative deformation per pass is 50%-80%, for example, it can be 50%, 55%, 60%, 65%, 70%, 75% or 80%, etc., until the target size is reached.

[0034] The hot-rolled strip of the present invention is sheathed, and the sheath is vacuum sealed, which can balance the recrystallization and scandium diffusion process, reduce the risk of surface oxidation and rolling cracking of the material, and improve the performance and yield of the prepared aluminum alloy sputtering target.

[0035] As a preferred technical solution of the present invention, the preparation method includes the following steps:

[0036] (1) Mix scandium metal with a purity ≥99.95% and aluminum metal with a purity ≥99.999%. The mixture is subjected to a first suspension melting in a vacuum environment. After complete melting, it is allowed to stand and refine for 5-20 minutes. The mixture is then cooled and turned into an ingot in a crucible for a second suspension melting. After complete melting, it is allowed to stand and refine for 5-20 minutes. The mixture is then quickly poured into a water-cooled copper mold at a temperature of 20-30℃ to obtain a cast aluminum-scandium alloy ingot. The scandium content of the aluminum-scandium alloy ingot is 10-30wt%. The pouring speed is 10-20L / min, and the cooling speed of the water-cooled mold is 50-100℃ / s.

[0037] (2) After the aluminum-scandium alloy ingot is solution treated at 500-600℃ for 2-4 hours, it is sealed in a cladding and the cladding is evacuated to a vacuum degree of 1×10⁻⁶. -3 -5×10 -3 After Pa, hot rolling with a sheath is performed at a temperature of 300-600℃; the rotation is 60° per pass, and the cumulative deformation per pass is 50%-80% until the target size is reached.

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

[0039] (1) The present invention uses a suspension melting process to alloy aluminum and scandium, which effectively reduces the introduction of impurities and significantly improves the purity and quality of aluminum-scandium alloy;

[0040] (2) By casting into a water-cooled copper mold and rapidly cooling it, the diffusion window of scandium is reduced, which effectively reduces the occurrence of segregation and improves the uniformity and density of aluminum-scandium alloy.

[0041] (3) The ingot obtained by the present invention is subjected to solid solution treatment to make the precipitated phase evenly distributed, which further improves the microstructure of aluminum scandium alloy and enhances the overall performance of the material.

[0042] (4) The present invention uses vacuum-encased hot rolling, which balances recrystallization and scandium diffusion processes, reduces the risk of material surface oxidation and rolling cracking, and adopts a multi-pass reversing hot rolling process to weaken the anisotropy of the microstructure and improve the density of the target material. Attached Figure Description

[0043] Figure 1 This is a grain structure diagram of the aluminum-scandium alloy prepared in Example 1 of the present invention. Detailed Implementation

[0044] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments. However, the following examples 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.

[0045] Example 1

[0046] This embodiment provides a method for preparing an aluminum alloy sputtering target, the method comprising the following steps:

[0047] (1) Mix scandium metal with a purity ≥99.95% and aluminum metal with a purity ≥99.999%. The mixture is subjected to a first suspension melting in a vacuum environment. After it is completely melted, it is allowed to stand and refine for 15 minutes. The mixture is then cooled and turned into an ingot in a crucible for a second suspension melting. After it is completely melted, it is allowed to stand and refine for 15 minutes. The mixture is then quickly poured into a water-cooled copper mold at a temperature of 20°C to obtain a cast aluminum-scandium alloy ingot. The scandium content of the aluminum-scandium alloy ingot is 20wt%. The pouring speed is 15L / min, and the cooling speed of the water-cooled mold is 80°C / s.

[0048] (2) After the aluminum-scandium alloy ingot is solution treated at 550℃ for 3 hours, it is sealed in a cladding and the cladding is evacuated to a vacuum degree of 1×10⁻⁶. -3 Then, hot rolling with a sheath is performed at a temperature of 500°C; the rotation is 60° per pass, and the cumulative deformation per pass is 60% until the target size is reached;

[0049] The prepared aluminum alloy sputtering target has a density of 100%, uniform composition distribution, and grain structure diagram as shown in the figure. Figure 1 As shown.

[0050] Example 2

[0051] This embodiment provides a method for preparing an aluminum alloy sputtering target, the method comprising the following steps:

[0052] (1) Mix scandium metal with a purity ≥99.95% and aluminum metal with a purity ≥99.999%. The mixture is subjected to a first suspension melting in a vacuum environment. After it is completely melted, it is allowed to stand and refine for 5 minutes. The mixture is then cooled and turned into an ingot in a crucible for a second suspension melting. After it is completely melted, it is allowed to stand and refine for 20 minutes. The mixture is then quickly poured into a water-cooled copper mold at a temperature of 30°C to obtain a cast aluminum-scandium alloy ingot. The scandium content of the aluminum-scandium alloy ingot is 30wt%. The pouring speed is 20L / min, and the cooling speed of the water-cooled mold is 50°C / s.

[0053] (2) After the aluminum-scandium alloy ingot is solution treated at 600℃ for 2 hours, it is sealed in a cladding, and the cladding is evacuated to a vacuum degree of 5×10⁻⁶. -3 Then, hot rolling with a sheath is performed at a temperature of 600°C; the rotation is 60° per pass, and the cumulative deformation per pass is 80% until the target size is reached; the resulting aluminum alloy sputtering target has a density of 100% and a uniform distribution of microstructure.

[0054] Example 3

[0055] This embodiment provides a method for preparing an aluminum alloy sputtering target, the method comprising the following steps:

[0056] (1) Mix scandium metal with a purity ≥99.95% and aluminum metal with a purity ≥99.999%. The mixture is subjected to a first suspension melting in a vacuum environment. After it is completely melted, it is allowed to stand and refine for 20 minutes. The mixture is then cooled and turned into an ingot in a crucible for a second suspension melting. After it is completely melted, it is allowed to stand and refine for 5 minutes. The mixture is then quickly poured into a water-cooled copper mold at a temperature of 25°C to obtain a cast aluminum-scandium alloy ingot. The scandium content of the aluminum-scandium alloy ingot is 10wt%. The pouring speed is 10L / min, and the cooling speed of the water-cooled mold is 100°C / s.

[0057] (2) After the aluminum-scandium alloy ingot is solution treated at 500℃ for 4 hours, it is sealed in a cladding and the cladding is evacuated to a vacuum degree of 3×10⁻⁶. -3 Then, hot rolling with a sheath is performed at a temperature of 300°C; the rotation is 60° per pass, and the cumulative deformation per pass is 50% until the target size is reached; the resulting aluminum alloy sputtering target has a density of 100% and a uniform distribution of microstructure.

[0058] Example 4

[0059] This embodiment provides a method for preparing an aluminum alloy sputtering target. Except for the first suspension melting in step (1) followed by direct casting without the second suspension melting, the preparation method is the same as in Example 1. The resulting aluminum alloy sputtering target has an uneven distribution of microstructure and composition.

[0060] Example 5

[0061] This embodiment provides a method for preparing an aluminum alloy sputtering target. Except for the solution treatment temperature of 450°C, the preparation method is the same as in Example 1. The resulting aluminum alloy sputtering target has an uneven distribution of microstructure and composition.

[0062] Example 6

[0063] This embodiment provides a method for preparing an aluminum alloy sputtering target. Except for the solution treatment temperature of 650°C, the preparation method is the same as in Example 1. During the preparation process, the aluminum elemental phase melts, resulting in an uneven distribution of the microstructure and composition of the aluminum alloy sputtering target.

[0064] Comparative Example 1

[0065] This comparative example provides a method for preparing an aluminum alloy sputtering target. The preparation method adopts the method disclosed in Example 1 of CN111455327A, and the prepared aluminum alloy sputtering target has a density of 99%.

[0066] Comparative Example 2

[0067] This comparative example provides a method for preparing an aluminum alloy sputtering target. Except for step (2), which involves hot rolling an aluminum-scandium alloy ingot without a cladding, the preparation method is the same as in Example 1. The prepared aluminum alloy sputtering target is cracked.

[0068] Comparative Example 3

[0069] This comparative example provides a method for preparing an aluminum alloy sputtering target. The preparation method is the same as in Example 1, except that the suspension melting is replaced by vacuum sintering. The prepared aluminum alloy sputtering target has a density of 95%.

[0070] (1) As can be seen from Examples 1 to 3, the present invention can improve the density of alloy sputtering target material without introducing impurities by combining suspension melting with solution treatment and vacuum hot rolling with a cladding process. This improves the sputtering effect of the target material.

[0071] (2) As can be seen from Examples 1 and 4-6, the present invention further adopts two-step suspension melting to remove impurities from the material more fully and improves the uniformity. By optimizing the temperature of the solid solution treatment, the grain structure is optimized and the density is improved.

[0072] (3) As can be seen from Example 1 and Comparative Examples 1-3, the present invention can achieve higher density than the prior art through the combination of specific processes. When vacuum sintering is used instead of suspension melting, the density of the material drops to 95%. When hot rolling is not clad, the surface of the material is severely oxidized, and the risk of rolling cracking increases.

[0073] In summary, this invention can prepare aluminum-scandium alloy targets with high purity, uniform composition, and high density by combining suspension melting with solution treatment and vacuum hot rolling with a cladding.

[0074] 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 alloy sputtering target, characterized by, The preparation method comprises the following steps: (1) a mixture of metallic scandium and metallic aluminum is subjected to suspension smelting in a vacuum environment and then water-cooled to obtain an aluminum scandium alloy ingot in a cast shape; (2) the aluminum scandium alloy ingot is subjected to solid solution treatment and then sealed in a package, the package is vacuumized and then subjected to hot rolling with the package.

2. The production method according to claim 1, characterized by, The purity of the metallic aluminum is ≥99.999%; Preferably, the purity of the metallic scandium is ≥99.95%.

3. The production method according to claim 1 or 2, characterized by, The scandium content of the aluminum scandium alloy ingot is 10-30wt%.

4. The production method according to any one of claims 1 to 3, characterized by, The vacuum degree of the vacuum environment in step (1) is 6x10 -3 -10x10 -3 Pa.

5. The method of any one of claims 1-4, wherein, The suspension smelting comprises sequentially performing first suspension smelting and second suspension smelting; Preferably, the first suspension smelting is subjected to static refining for 5-20 min after the mixture is completely melted; Preferably, the mixture is cooled in the crucible after the first suspension smelting is completed and then subjected to second suspension smelting by turning the ingot; Preferably, the second suspension smelting is subjected to static refining for 5-20 min after the mixture is completely melted.

6. The method of any one of claims 1-5, wherein, The water cooling comprises rapidly pouring the aluminum scandium alloy melt of the second suspension smelting into a water-cooled mold; Preferably, the material of the water-cooled mold comprises copper; Preferably, the temperature of the water-cooled mold is 20-30℃; Preferably, the pouring speed of the rapid pouring is 100-200 L / min; Preferably, the cooling speed of the water cooling is 50-100℃ / s.

7. The method of any one of claims 1-6, wherein, The temperature of the solid solution treatment is 500-600℃; Preferably, the time of the solid solution treatment is 2-4 h; Preferably, the solid solution treatment is performed in an inert atmosphere.

8. The method of any one of claims 1-7, wherein, The package is evacuated to a vacuum of 1 x 10 -3 -5 x 10 -3 Pa in step (2).

9. The method of any one of claims 1-8, wherein, The temperature of the hot rolling is 300-600℃; Preferably, the hot rolling is rotated by 60° per pass, and the cumulative deformation per pass is 50%-80% until the target size.

10. The method of any one of claims 1-9, wherein, The preparation method comprises the following steps: (1) metallic scandium with a purity of ≥99.95% and metallic aluminum with a purity of ≥99.999% are mixed, the mixture is subjected to first suspension smelting in a vacuum environment, subjected to static refining for 5-20 min after being completely melted, subjected to second suspension smelting by turning the ingot in the crucible, subjected to static refining for 5-20 min after being completely melted, and rapidly poured into a water-cooled copper mold with a temperature of 20-30℃ to obtain an aluminum scandium alloy ingot in a cast shape, the scandium content of the aluminum scandium alloy ingot being 10-30wt%; the pouring speed being 10-20 L / min, and the cooling speed of the water-cooled mold being 50-100℃ / s; (2) The aluminum-scandium alloy ingot is sealed in a package after solid solution treatment at 500-600 °C for 2-4 h, the package is vacuumized to a vacuum degree of 1 x 10 -3 -5 x 10 -3 Pa, and then hot-rolled with the package, the temperature of the hot-rolling is 300-600 °C; each pass is rotated by 60 °, the cumulative deformation of each pass is 50%-80%, until the target size.

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