Preparation method of low-melting-point target material

Abstract

The invention discloses a preparation method of a low-melting-point target material, which comprises the following steps: firstly carrying out extrusion treatment on an original cast ingot, combining the extrusion treatment with high-temperature compression treatment, sawing a target material blank, then carrying out high-temperature heating on the target material blank, and carrying out downward compression through a pressure head of a hydraulic machine to obtain the target material blank. And meanwhile, accumulation of deformation quantity is obtained, a basis is provided for subsequent compression and grain refinement, the deformation quantity of the target material blank reaches 70% or above within 10-40 s through subsequent high-temperature compression treatment, the target material blank has the rapid large-deformation-quantity compression deformation change process at the high temperature, and the target material blank has the dynamic recrystallization process in the deformation process.

Description

Technical Field

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

[0002] The target material is used for sputtering coating. The target material has extremely strict requirements on its internal structure. It cannot have defects such as loose shrinkage cavities, cracks, inclusions, etc., and the grains must be small and uniform. Existing hot working methods are mostly forging and rolling. Forging mostly uses an air hammer, which uses high impact energy to make the target ingot plastically deform. This processing method is prone to cracking. If there are shrinkage cavities and looseness in the target ingot, these defects will be magnified during forging. Although continuously increasing the forging heating temperature can alleviate this phenomenon, the rapid cooling during the forging process results in the effect of increasing the forging temperature is not obvious, and the forging process is complex and energy-intensive.

[0003] The traditional process steps for manufacturing target material blanks are repeated forging → intermediate annealing → batch rolling → heat treatment → machining. The traditional target material production method has complicated procedures, low production efficiency and high manufacturing cost.

[0004] The target material has strict requirements on the grain size. When forging the target material using the traditional forging process, the target ingot needs to be repeatedly forged and rolled. 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 target material.

[0005] The traditional rolling process of target materials mainly aims to reduce the thickness of target materials and refine the structure. During the rolling process, the target materials will deform along with the rollers, resulting in poor flatness of the blank after rolling, which requires repeated shaping. Due to the different material properties of different target materials, the shaping of targets of different materials is extremely difficult to control. In addition, the shaping of targets with large elastic modulus is particularly difficult, and it is very easy to cause the target materials to crack when shaping targets of brittle materials.

[0006] In actual production, in order to obtain sufficient striking energy, the target ingot is generally forged in sections. The target ingot is gradually deformed section by section, which will lead to concentrated deformation in multiple places of the target ingot, and will also cause local coarse grains and uneven grains in the target ingot, that is, it cannot meet the technical requirements of the target material for fine and uniform grains. Therefore, it is necessary to develop a hot processing method that can eliminate the looseness and shrinkage holes of the target ingot and achieve uniform deformation of the target material as a whole. Summary of the invention

[0007] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a method for preparing a low melting point target material, which has a simple process and is easy to control, greatly simplifies the process, has high production efficiency, high yield rate, and greatly reduces energy consumption and production costs.

[0008] In order to achieve the above object, the technical solution adopted by the present invention is: a method for preparing a low melting point target material, comprising the following steps:

[0009] Step S1, sawing, taking an original ingot of a target material with a melting point of 200-1000° C. and a purity greater than 5N, and sawing to obtain an original ingot in the shape of a column;

[0010] Step S2, heating, using an ingot heating furnace to heat the original ingot, the heating temperature is 0-500° C.;

[0011] Step S3, extrusion, extruding the original ingot, and forming a fiber structure of the target material of the original ingot through the extrusion outlet by controlling the temperature, extrusion speed and deformation of the extrusion outlet, for subsequent compression accumulation deformation, 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° C. After extrusion treatment, a target rod is obtained;

[0012] Step S4: Cooling: cooling the target rod to room temperature by water cooling;

[0013] Step S5, straightening, straightening the target rod, controlling the straightening rate to 0.3-1.5%, to obtain a target blank;

[0014] Step S6, sawing the blank, sawing the target blank into a cylindrical shape with a height H according to the weight of the target;

[0015] Step S7, high temperature heating, heating the target material blank at a high temperature of 100-800°C; and the temperature of the target material blank after the heating treatment is 0.6-0.8Tm, where Tm is the melting point of the material;

[0016] Step S8, large variable compression, vertically placing the target material blank that has just been heated at high temperature and is still in a high temperature state on the lower platform of a hydraulic press with a tonnage of ≥8000 tons, pressing the upper part of the target material blank with the pressure head of the hydraulic press, and continuously compressing the target material blank downward with the pressure head, and the force applied to the target material blank by the hydraulic press is greater than the material yield strength of the target material blank, so that the target material blank is flattened and thinned in the height direction, and the deformation of the target material blank reaches more than 70% in 10-40s through high-temperature compression and extrusion treatment, and the pressure head is controlled to descend at a uniform speed during the process of downward compression of the target material blank, and the speed of the uniform descent of the pressure head is the compression height in the large variable compression process of step S8 divided by the time used for the large variable compression, and the large variable compression makes the target material blank have a rapid large deformation amount of compression deformation change process at high temperature, so that the target material blank has a dynamic recrystallization process during the deformation process;

[0017] Step S9, cooling, after the target material with a high temperature heating temperature of ≤300°C and a large deformation amount is compressed in step S7, an air cooling method is adopted to cool it to room temperature; after the target material with a high temperature heating temperature of >300°C and a large deformation amount is compressed in step S7, an air cooling method is adopted to cool it to room temperature;

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

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

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

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

[0022] According to a further technical solution, the length of the water tank is 0.8-1.2 m, the time for the rod target to pass through the water tank is controlled at 3-5 seconds, and the temperature of the rod target is reduced to 20-35° C. by 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 ≤±0.05 mm / m. The plane of the upper surface of the conductive metal target is equal to the flatness of the bottom surface of the pressure head, and the plane of the lower surface of the conductive metal target is equal to the flatness of the top surface of the lower platform.

[0024] According to a further technical solution, in step S1, sawing is performed to obtain an original ingot in the shape of a cylinder with a diameter of 300-500 mm and a length of 600-2000 mm;

[0025] In step S3, after extrusion treatment, a cylindrical rod target with a diameter of 80-150 mm is obtained;

[0026] Step S4: passing the rod target through a water tank filled with coolant and cooling it using a water-penetrating cooling method;

[0027] The step S6, sawing to obtain a cylindrical target blank with a height of 80-150 mm;

[0028] In step S8, the 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 for compression, and the target blank is vertically placed in the middle of the lower platform, and the target blank is continuously and smoothly pressed downward by the pressure head to reduce the height of the target blank and increase the diameter. Through high-temperature compression and extrusion treatment, the height of the target 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] Compared with the prior art, the advantages of the present invention are as follows: the present invention combines extrusion processing and high-temperature compression processing, firstly obtains a dense structure through cold extrusion processing or medium-temperature extrusion processing, obtains the accumulation of deformation and provides a basis for subsequent compression and grain refinement, and then through the subsequent high-temperature compression extrusion processing, the deformation of the target material blank reaches more than 70% in 10-40s, so that the target material blank has a rapid large deformation compression deformation change process at high temperature, and the target material blank has a dynamic recrystallization process during the deformation process.

[0030] The present invention uses a large-tonnage hydraulic press combined with a high-temperature compression and 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 subsequent flatness processing process steps;

[0031] The present invention replaces the traditional treatment process of forging first and then rolling, not only eliminating the high energy consumption process steps of repeated forging, but also preventing concentrated deformation cracking. In addition, the present invention adopts a hydraulic press of ≥8000 tons for compression so that the target material can be compressed quickly at high temperature and with large deformation in a very short time. Compared with the traditional process of forging first and then rolling, the production efficiency of the present invention is improved by dozens of times. The dynamic recrystallization process is controlled by deformation temperature, deformation amount and deformation time, so that a completely recrystallized structure can be obtained after the deformation is completed, eliminating the heat treatment process, and the high temperature and short time can better refine the grains, which not only solves the problem of secondary deformation in the processing process, but also solves the problem that the elastic modulus is large and cannot be reshaped. The present invention is particularly suitable for round cake-shaped metal targets, especially round cake-shaped semiconductor metal targets. Therefore, the present invention not only eliminates multiple high energy consumption and time-consuming process steps in the traditional process, greatly improves production efficiency, greatly reduces energy consumption and production costs, but also makes the grains of the prepared products more fine and uniform, the product quality is better, and the yield and good rate are greatly improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is the metallographic structure of the fibrous structure formed by the high-purity tin ingot of Example 1 after extrusion treatment.

[0033] Figure 2This is the metallographic image of the high-purity tin blank of Example 1 after compression treatment (equiaxed, average grain size of about 40-50um)

[0034] Figure 3 The metallographic structure of the fibrous structure formed by the high-purity aluminum ingot after extrusion treatment in Example 2

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

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

[0037] Figure 6 This is the metallographic structure of the high-purity copper blank after compression treatment in Example 4 (equiaxed, average grain size of about 5-15um) DETAILED DESCRIPTION

[0038] Embodiment 1

[0039] 5N high purity tin target material, sawing to obtain the original ingot of 5N high purity tin target material with a diameter of 300mm and a length of 800mm, and cold extrusion treatment, extrusion ratio 9, extrusion speed 5m / min, extrusion outlet about 80℃, straightening rate 1%, after extrusion to obtain a target bar with a diameter of about 100mm and a length of about 6m, after extrusion, water cooling to room temperature, after extrusion for non-recrystallized structure, sawing to obtain a bar (target blank) with a diameter of 100mm and a length of 125mm, quickly heated to 150℃, transferred to a hydraulic press and placed upright, the bar is subjected to high temperature rapid compression treatment by a large tonnage hydraulic press, and the bar is compressed to a diameter of 300mm and a thickness (height) of about 13.8mm within 15 seconds, air cooled to room temperature, the average grain size is about 40-50um, the grains are small, the flatness is good, and there is no cracking.

[0040] Embodiment 2

[0041] 5N5 high-purity aluminum target material, sawing to obtain the original ingot of 5N5 high-purity aluminum target material with a diameter of 400mm and a length of 1000mm, and cold extrusion treatment, extrusion ratio 11.11, extrusion speed 5m / min, extrusion outlet about 150℃, straightening rate 1%, after extrusion, a diameter of 120mm and a length of about 10m (some material remains in the extrusion die), water-cooled to room temperature after extrusion, unrecrystallized structure after extrusion, sawing to obtain a rod (target blank) with a diameter of 120mm and a length of 150mm, quickly heated to 300℃, transferred to a hydraulic press and placed upright, the rod is subjected to high-temperature rapid compression treatment by a large-tonnage hydraulic press, and compressed to a diameter of 350mm and a thickness (height) of about 17.6mm within 20 seconds, air-cooled to room temperature, the average grain is about 10-20um, the grain is small, the flatness is good, and there is no cracking.

[0042] Embodiment 3

[0043] 6N high-purity copper target, sawing to obtain the original ingot of high-purity copper target with a diameter of 450mm and a length of 1000mm, the original ingot is heated to 150℃ and then extruded, the extrusion ratio is 14, the extrusion speed is 5m / min, the extrusion outlet is about 200℃, the straightening rate is 1%, and the diameter of 150mm and the length of about 8m are obtained after extrusion (some material remains in the extrusion die), and the extrusion is water-cooled to room temperature after extrusion. After extrusion, it is an unrecrystallized structure, and the rod with a diameter of 150mm and a height of 180mm is sawed. The rod is quickly heated to 450℃, transferred to a hydraulic press and placed upright, and the rod is subjected to high-temperature rapid compression treatment by a large-tonnage hydraulic press, and the rod is compressed to a target with a diameter of 450mm and a height of about 20mm within 25 seconds, and a 6N high-purity copper target with an average grain size of 5-15um is obtained, the grains are fine, the flatness is good, and there is no cracking.

Claims

1. A method for preparing a low melting point target material, characterized in that: The following steps are involved: Step S1, sawing, taking an original ingot of a target material with a melting point of 200-1000° C. and a purity greater than 5N, and sawing to obtain an original ingot in the shape of a column; Step S2, heating, using an ingot heating furnace to heat the original ingot, the heating temperature is 0-500° C.; Step S3, extrusion, extruding the original ingot, and forming a fiber structure of the target material of the original ingot through the extrusion outlet by controlling the temperature, extrusion speed and deformation of the extrusion outlet, for subsequent compression accumulation deformation, 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° C. After extrusion treatment, a target rod is obtained; Step S4: Cooling: cooling the target rod to room temperature by water cooling; Step S5, straightening, straightening the target rod, controlling the straightening rate to 0.3-1.5%, to obtain a target blank; Step S6, sawing the blank, sawing the target blank into a cylindrical shape with a height H according to the weight of the target; Step S7, high temperature heating, heating the target material blank at a high temperature of 100-800°C; Step S8, large variable compression, vertically placing the target material blank that has just been heated at high temperature and is still in a high temperature state on the lower platform of a hydraulic press with a tonnage of ≥8000 tons, pressing the upper part of the target material blank with the pressure head of the hydraulic press, and continuously compressing the target material blank downward with the pressure head, and the force applied to the target material blank by the hydraulic press is greater than the material yield strength of the target material blank, so that the target material blank is flattened and thinned in the height direction, and the deformation of the target material blank reaches more than 70% in 10-40s through high temperature compression and extrusion treatment, so that the target material blank has a rapid large deformation compression deformation change process at high temperature, and the target material blank has a dynamic recrystallization process during the deformation process; Step S9, cooling, after the target material with a large deformation amount compressed at a high temperature heating temperature of ≤300°C in step S7 is cooled to room temperature by air cooling, and after the target material with a large deformation amount compressed at a high temperature heating temperature of >300°C in step S7 is cooled to room temperature by wind cooling; Step S10: Finished product: a target material with an average grain size of 5-55um and a purity greater than 5N is obtained.

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 process of compressing the target material blank downward. The downward pressing speed of the pressure head during the large variable compression process is the compression height during the large variable compression process divided by the time used for the large variable compression. The dynamic recrystallization process is completed during the large variable compression of the target material blank.

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

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 plane of the upper surface of the conductive metal target is equal to the flatness of the bottom surface of the pressure head, and the plane of the lower surface of the conductive metal target 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 target material original ingot is a pure tin target material ingot with a purity greater than 5N. In the step S10, a pure tin target material with an average grain size of 40-55 um and a purity greater than 5N is obtained.

6. The method for preparing a low melting point target material according to claim 1, characterized in that: In step S1, the target material original ingot is a pure aluminum target material ingot with a purity greater than 5N; In the step S10, the finished product is a pure aluminum target material with an average grain size of 10-25 um 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 material ingot is a pure copper target material ingot with a purity greater than 5N; In the step S10, the finished product is a high-purity copper target material with an average grain size of 5-20 um 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 the step S7, the temperature of the target material after the heating 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 according to any one of claims 1 to 9, characterized in that: The step S1, sawing to obtain an original ingot in the shape of a cylinder with a diameter of 300-500 mm and a length of 600-2000 mm; In step S3, after extrusion treatment, a cylindrical rod target blank with a diameter of 80-150 mm is obtained; Step S4: passing the rod target through a water tank filled with coolant and cooling it using a water-penetrating cooling method; The step S6, sawing to obtain a cylindrical target blank with a height of 80-150 mm; In step S8, the 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 for compression, and the target blank is vertically placed in the middle of the lower platform. The target blank is continuously and smoothly pressed downward by the pressure head to reduce the height of the target blank and increase the diameter. The height of the target 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 through high-temperature compression and extrusion treatment.

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