A method for preparing a low-melting-point target material

Abstract

This invention discloses a method for preparing low-melting-point target materials. First, the original ingot is subjected to extrusion treatment. This invention combines extrusion treatment and high-temperature compression treatment. After sawing the target material billet, it is heated at high temperature and compressed downward by the pressure head of a hydraulic press to obtain the target material billet. This invention first obtains a dense structure through extrusion treatment, and at the same time obtains the accumulation of deformation, which provides a basis for subsequent compression and grain refinement. Through the subsequent high-temperature compression treatment, the deformation amount of the target material billet reaches more than 70% in 10-40s, so that the target material billet has a rapid and large deformation compression deformation process at high temperature, and the target material billet has a dynamic recrystallization process during deformation.

Description

Technical Field

[0001] This invention relates to the field of target material production methods, and in particular to a method for preparing a low-melting-point target material. Background Technology

[0002] Sputtering targets are used for sputtering coatings, and the requirements for their internal structure are extremely strict. They must be free of defects such as porosity, shrinkage cavities, cracks, and inclusions, and the grains must be fine and uniform. Current hot working methods mainly include forging and rolling. Forging often uses air hammers, utilizing high impact energy to plastically deform the target ingot. This processing method is prone to cracking. If shrinkage cavities and porosity exist in the target ingot, these defects will be amplified during forging. Although continuously increasing the forging heating temperature can alleviate this phenomenon, the rapid cooling during the forging process makes increasing the forging temperature ineffective, and the forging process is complex and energy-intensive.

[0003] The traditional manufacturing process for target blanks involves multiple forging steps, intermediate annealing, multiple rolling processes, heat treatment, and machining. This traditional method of target production is complex, inefficient, and costly.

[0004] Because the grain size requirements for sputtering targets are quite strict, the traditional forging process for forging sputtering targets requires repeated forging and rolling of the sputtering target ingot. The production process requires repeated upsetting, drawing and intermediate annealing, which consumes a lot of energy. If the deformation is not well controlled, cracks will occur, causing crack initiation and affecting the quality of the sputtering target.

[0005] In traditional target rolling processes, the primary goal is to reduce the target thickness and refine the microstructure. During rolling, the target deforms with the rolls, resulting in poor flatness of the rolled billet, necessitating repeated reshaping. Because different targets have different material properties, controlling the reshaping of targets made from different materials is extremely difficult. Furthermore, reshaping targets with high elastic modulus is particularly challenging, and reshaping brittle targets is very prone to cracking.

[0006] In actual production, in order to obtain sufficient impact energy, the target ingot is generally forged in sections. The target ingot is gradually deformed section by section. This will lead to multiple deformation concentrations in the target ingot, as well as local coarse grains and uneven grains. That is, it cannot meet the technical requirements of fine and uniform grains for the target. Therefore, it is necessary to develop a hot working method that can eliminate porosity and shrinkage cavities in the target ingot and achieve uniform deformation of the entire target. Summary of the Invention

[0007] In view of the shortcomings of the existing technology, the purpose of this invention is to provide a method for preparing low melting point target materials. The process is simple and easy to control, greatly simplifies the process, has high production efficiency, high yield, and significantly reduces energy consumption and production costs.

[0008] To achieve the above objectives, the technical solution adopted by this invention is: a method for preparing a low-melting-point target material, comprising the following steps:

[0009] Step S1: Sawing. Take the original target material ingot with a purity greater than 5N and a melting point of 200-1000℃, and saw it to obtain the original ingot in the shape of a column.

[0010] Step S2: Heating. The original ingot is heated using an ingot heating furnace at a temperature of 0-500℃.

[0011] Step S3, extrusion: The original ingot is extruded. By controlling the temperature of the extrusion outlet, the extrusion speed and the amount of deformation, the target material structure of the original ingot passing through the extrusion outlet is made to form a fibrous structure, which accumulates deformation for subsequent compression. The extrusion ratio is controlled at 8-30, the extrusion speed is controlled at 3-10 m / min, and the extrusion outlet temperature is controlled at 80-600℃. After extrusion, the target material rod is obtained.

[0012] Step S4: Cooling. Use water cooling to cool the target rod to room temperature.

[0013] Step S5: Straightening. The target bar is straightened, and the straightening rate is controlled at 0.3-1.5% to obtain the target blank.

[0014] Step S6: Cutting the billet: Cut the target billet into a cylindrical shape with a height H according to the weight of the target material.

[0015] Step S7: High-temperature heating. The target blank is heated to a high temperature of 100-800℃; and the temperature of the target blank after heat treatment is 0.6-0.8Tm, where Tm is the melting point of the material.

[0016] Step S8: Large-variable compression. The target billet, which has just been heated to a high temperature and is still in a high-temperature state, is vertically placed on the lower platform of a hydraulic press with a tonnage of ≥8000 tons. The upper part of the target billet is pressed down by the pressure head of the hydraulic press, and the target billet is continuously compressed downward by the pressure head. The force applied to the target billet by the hydraulic press is greater than the yield strength of the target billet material, so that the target billet is flattened and thinned in the height direction. Through high-temperature compression and extrusion treatment, the deformation of the target billet reaches more than 70% in 10-40s. During the downward compression of the target billet by the pressure head, the pressure head is controlled to descend at a uniform speed. The uniform descent speed of the pressure head is the compression height in the large-variable compression process of step S8 divided by the time taken for large-variable compression. Large-variable compression causes the target billet to have a rapid compression deformation process with a large amount of deformation at high temperature, and causes the target billet to have a dynamic recrystallization process during deformation.

[0017] Step S9: Cooling. After the target material with a high temperature heating temperature ≤300℃ in step S7 is compressed with large deformation, it is cooled to room temperature by air cooling. After the target material with a high temperature heating temperature >300℃ in step S7 is compressed with large deformation, it is cooled to room temperature by air cooling.

[0018] Step S10, Finished product: A target material with an average grain size of 5-55 μm and a purity greater than 5N is obtained.

[0019] In step S1, if the original ingot of the target material is a pure tin target material ingot with a purity greater than 5N, then in step S10, a pure tin target material with an average grain size of 40-55um and a purity greater than 5N is obtained.

[0020] In step S1, if the original ingot of the target material is a pure aluminum target material ingot with a purity greater than 5N, then in step S10, an aluminum target material with an average grain size of 10-25um and a purity greater than 5N will be obtained accordingly.

[0021] In step S1, if the original ingot of the target material is a pure copper target material ingot with a purity greater than 5N, then in step S10, a pure copper target material with an average grain size of 5-20um and a purity greater than 5N is obtained accordingly.

[0022] In a further technical solution, the length of the water tank is 0.8-1.2m, and the time for the rod target to pass through the water tank is controlled to be 3-5 seconds, so that the temperature of the rod target can be reduced to 20-35℃ through the water cooling method.

[0023] In a further technical solution, the flatness of the bottom surface of the pressure head and the lower platform is ≤±0.05mm / m. The flatness of the upper surface of the conductor metal target is equal to the flatness of the bottom surface of the pressure head, and the flatness of the lower surface of the conductor metal target is equal to the flatness of the top surface of the lower platform.

[0024] A further technical solution is that, in step S1, the original ingot is sawed to obtain a cylindrical shape with a diameter of 300-500mm and a length of 600-2000mm;

[0025] Step S3: After extrusion, a cylindrical rod target with a diameter of 80-150mm is obtained.

[0026] In step S4, the rod target is passed through a water tank filled with coolant and cooled using a water-cooling method.

[0027] Step S6 involves sawing to obtain a target blank in the shape of a column with a height of 80-150mm;

[0028] In step S8, a hydraulic press with a tonnage of ≥8000 tons and equipped with a circular pressure head with a diameter of 550-800 mm or a square lower platform with a side length of 550-800 mm is used to compress the target material blank. The target material blank is placed vertically in the middle of the lower platform, and the pressure head continuously and smoothly presses the target material blank downward, making the height of the target material blank smaller and the diameter larger. Through high-temperature compression and extrusion treatment, the height of the target material blank is reduced from 80-150 mm to 10-30 mm and the diameter is changed from 100-150 mm to 350-550 mm within 10-40 seconds.

[0029] The advantages of this invention compared with the prior art are as follows: This invention combines extrusion processing and high-temperature compression processing. First, a dense structure is obtained through cold extrusion or medium-temperature extrusion processing, which accumulates deformation and provides a basis for subsequent compression and grain refinement. Then, through subsequent high-temperature compression extrusion processing, the deformation of the target billet reaches more than 70% in 10-40s, so that the target billet has a rapid and large deformation compression deformation process at high temperature, and the target billet has a dynamic recrystallization process during deformation.

[0030] This invention uses a large-tonnage hydraulic press combined with a high-temperature compression extrusion process to thin the target material, replacing the traditional multiple rolling process steps, ensuring and improving the flatness of the target material, and eliminating the need for subsequent flatness processing steps.

[0031] This invention replaces the traditional forging-then-rolling process, eliminating the energy-intensive steps of repeated forging and preventing deformation-induced cracking. Furthermore, the invention utilizes a hydraulic press of ≥8000 tons for compression, enabling rapid, high-temperature, and large-deformation compression of the target material in a very short time. Compared to the traditional forging-then-rolling process, this invention increases production efficiency by tens of times. By controlling the dynamic recrystallization process through deformation temperature, deformation amount, and deformation time, a fully recrystallized structure is obtained immediately after deformation, eliminating the need for heat treatment. High temperature and short time result in better grain refinement, solving not only the problem of secondary deformation during processing but also addressing the issue of high elastic modulus making shaping impossible. This invention is particularly suitable for disc-shaped metal targets, especially disc-shaped semiconductor metal targets. Therefore, this invention not only eliminates multiple energy-intensive and time-consuming steps in traditional processes, significantly improving production efficiency and reducing energy consumption and production costs, but also produces products with finer and more uniform grains, resulting in better product quality and significantly increasing yield and productivity. Attached Figure Description

[0032] Figure 1 The metallographic structure of the high-purity tin ingot in Example 1 is formed by extrusion treatment to create a fibrous structure.

[0033] Figure 2The metallographic structure (equiaxed, average grain size around 40-50 μm) of the high-purity tin billet after compression treatment in Example 1 is shown.

[0034] Figure 3 This is the metallographic structure of the high-purity aluminum ingot formed after extrusion treatment in Example 2.

[0035] Figure 4 The metallographic structure (equiaxed, average grain size of about 10-20 μm) of the high-purity aluminum billet after compression treatment in Example 2 is shown.

[0036] Figure 5 The metallographic structure of the high-purity copper ingot formed after extrusion treatment in Example 4 is shown.

[0037] Figure 6 The metallographic structure (equiaxed, average grain size of about 5-15 μm) of the high-purity copper billet after compression treatment in Example 4 is shown. Detailed Implementation

[0038] Example 1

[0039] 5N high-purity tin target material was sawn to obtain a raw ingot of 5N high-purity tin target material with a diameter of 300mm and a length of 800mm. This ingot was then subjected to cold extrusion at an extrusion ratio of 9, an extrusion speed of 5m / min, an extrusion outlet temperature of approximately 80℃, and a straightening rate of 1%. After extrusion, a target rod with a diameter of 100mm and a length of approximately 6m was obtained. This rod was then water-cooled to room temperature, resulting in a non-recrystallized structure. This was sawn to obtain a rod (target billet) with a diameter of 100mm and a length of 125mm. The billet was then rapidly heated to 150℃, transferred to a hydraulic press, and placed upright. The rod was subjected to high-temperature rapid compression using a large-tonnage hydraulic press, compressing it to a diameter of 300mm and a thickness (height) of approximately 13.8mm within 15 seconds. After air cooling to room temperature, the average grain size was approximately 40-50um, with fine grains, good flatness, and no cracking.

[0040] Example 2

[0041] 5N5 high-purity aluminum target material was sawn to obtain original ingots with a diameter of 400mm and a length of 1000mm. These ingots were then subjected to cold extrusion at an extrusion ratio of 11.11, an extrusion speed of 5m / min, an extrusion outlet temperature of approximately 150℃, and a straightening rate of 1%. The resulting ingots had a diameter of 120mm and a length of approximately 10m (some material remained in the extrusion die). After extrusion, the ingots were water-cooled to room temperature, resulting in a non-recrystallized structure. These ingots were then sawn to obtain rods (target material billets) with a diameter of 120mm and a length of 150mm. The billets were rapidly heated to 300℃, transferred to a hydraulic press, and placed upright. The rods were then subjected to high-temperature rapid compression using a large-tonnage hydraulic press, compressing them to a diameter of 350mm and a thickness (height) of approximately 17.6mm within 20 seconds. After air cooling to room temperature, the average grain size was approximately 10-20µm, exhibiting fine grains, good flatness, and no cracking.

[0042] Example 3

[0043] 6N high-purity copper targets were cut into ingots with a diameter of 450mm and a length of 1000mm. The ingots were heated to 150℃ and then extruded at an extrusion ratio of 1:4, an extrusion speed of 5m / min, an extrusion outlet temperature of approximately 200℃, and a straightening rate of 1%. After extrusion, the ingots were obtained with a diameter of 150mm and a length of approximately 8m (some material remained in the extrusion die). After extrusion, the ingots were water-cooled to room temperature, resulting in a non-recrystallized structure. The extruded ingots were then cut into rods with a diameter of 150mm and a height of 180mm. The rods were rapidly heated to 450℃, transferred to a hydraulic press, and placed upright. The rods were subjected to high-temperature and rapid compression using a large-tonnage hydraulic press, compressing them into targets with a diameter of 450mm and a height of approximately 20mm within 25 seconds. This yielded 6N high-purity copper targets with an average grain size of 5-15um, exhibiting fine grains, good flatness, and no cracking.

Claims

1. A method for preparing a low-melting-point target material, characterized in that: Includes the following steps: Step S1: Sawing. Take the original target material ingot with a purity greater than 5N and a melting point of 200-1000℃, and saw it to obtain the original ingot in the shape of a column. Step S2: Heating. The original ingot is heated using an ingot heating furnace at a temperature of 0-500℃. Step S3, extrusion: The original ingot is extruded. By controlling the temperature of the extrusion outlet, the extrusion speed and the amount of deformation, the target material structure of the original ingot passing through the extrusion outlet is made to form a fibrous structure, which accumulates deformation for subsequent compression. The extrusion ratio is controlled at 8-30, the extrusion speed is controlled at 3-10 m / min, and the extrusion outlet temperature is controlled at 80-600℃. After extrusion, the target material rod is obtained. Step S4: Cooling. Use water cooling to cool the target rod to room temperature. Step S5: Straightening. The target bar is straightened, and the straightening rate is controlled at 0.3-1.5% to obtain the target blank. Step S6: Cutting the billet: Cut the target billet into a cylindrical shape with a height H according to the weight of the target material. Step S7: High-temperature heating. The target blank is heated at a high temperature of 100-800℃. Step S8: Large Variable Compression. The target billet, which has just been heated to a high temperature and is still in a high-temperature state, is placed vertically on the lower platform of a hydraulic press with a tonnage of ≥8000 tons. The upper part of the target billet is pressed down by the pressure head of the hydraulic press, and the target billet is continuously compressed downward by the pressure head. The force applied to the target billet by the hydraulic press is greater than the yield strength of the target billet material, so that the target billet is flattened and thinned in the height direction. Through high-temperature compression and extrusion treatment, the deformation of the target billet reaches more than 70% in 10-40s. The target billet has a rapid large deformation compression deformation process at high temperature, and the target billet has a dynamic recrystallization process during the deformation process. Step S9: Cooling. After the target material with a high temperature heating temperature ≤300℃ in step S7 is compressed with large deformation, it is cooled to room temperature by air cooling. After the target material with a high temperature heating temperature >300℃ in step S7 is compressed with large deformation, it is cooled to room temperature by air cooling. Step S10: Finished product, obtaining a target material with an average grain size of 5-55 μm and a purity greater than 5N.

2. The method for preparing a low-melting-point target material according to claim 1, characterized in that: In step S8, the pressure head is controlled to descend at a uniform speed during the downward compression of the target billet. During the large variable compression process, the downward speed of the pressure head is the compression height divided by the time used for the large variable compression. The dynamic recrystallization process is completed during the large variable compression of the target billet.

3. The method for preparing a low-melting-point target material according to claim 1, characterized in that: In step S4, the water-cooling method involves passing the rod target material through a water tank with a length of 0.8-1.2m. The time for the rod target material to pass through the water tank is controlled to be 3-5 seconds. The temperature of the rod target material is reduced to 20-35℃ by water cooling.

4. The method for preparing a low-melting-point target material according to claim 1, characterized in that: The flatness of the bottom surface of the pressure head and the lower platform is ≤±0.05mm / m, the flatness of the upper surface of the target blank is equal to the flatness of the bottom surface of the pressure head, and the flatness of the lower surface of the target blank is equal to the flatness of the top surface of the lower platform.

5. The method for preparing a low-melting-point target material according to claim 1, characterized in that: The original ingot of the target material is a pure tin target material ingot with a purity greater than 5N. Step S10 yields a pure tin target with an average grain size of 40-55 μm and a purity greater than 5N.

6. The method for preparing a low-melting-point target material according to claim 1, characterized in that: In step S1, the original target ingot is a pure aluminum target ingot with a purity greater than 5N. Step S10, the finished product, yields a pure aluminum target with an average grain size of 10-25 μm and a purity greater than 5N.

7. The method for preparing a low-melting-point target material according to claim 1, characterized in that: In step S1, the original target ingot is a pure copper target ingot with a purity greater than 5N. Step S10, the finished product, yields a high-purity copper target with an average grain size of 5-20 μm and a purity greater than 5N.

8. The method for preparing a low-melting-point target material according to claim 1, characterized in that: In step S7, the temperature of the target blank after heat treatment is 0.6-0.8Tm, where Tm is the melting point of the material.

9. A method for preparing a low-melting-point target material according to any one of claims 1 to 8, characterized in that: In step S1, the original ingot is sawed to obtain a cylindrical shape with a diameter of 300-500mm and a length of 600-2000mm. Step S3: After extrusion, a cylindrical rod target blank with a diameter of 80-150mm is obtained. In step S4, the rod target is passed through a water tank filled with coolant and cooled using a water-cooling method. Step S6 involves sawing to obtain a target blank in the shape of a column with a height of 80-150mm; In step S8, a hydraulic press with a tonnage of 8000-12000 tons and equipped with a circular pressure head with a diameter of 550-800 mm or a square lower platform with a side length of 550-800 mm is used to compress the target material blank. The target material blank is placed vertically in the middle of the lower platform, and the pressure head continuously and smoothly presses the target material blank downward, so that the height of the target material blank decreases and the diameter increases. Through high-temperature compression and extrusion treatment, the height of the target material blank is reduced from 80-150 mm to 10-30 mm and the diameter is changed from 100-150 mm to 350-550 mm within 10-40 seconds.

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