Welding method for high-purity aluminum target material

Abstract

The invention discloses a welding method for a high-purity aluminum target material, and belongs to the technical field of alloy target materials. The method comprises the following steps: firstly, turning a plane thread on a to-be-welded surface of a copper alloy back plate, then plating an aluminum film on the to-be-welded surface within a certain thickness range, then assembling the copper alloy back plate plated with the aluminum film and a high-purity aluminum target blank, and putting an assembled target assembly into a sheath for degassing treatment; finally, hot isostatic pressure diffusion welding is carried out under the condition that the temperature is larger than or equal to 200 DEG C; the aluminum-copper target material prepared by adopting the welding method provided by the invention has good welding bonding strength and can be better applied to sputtering at high temperature; and the high-purity aluminum target grains can be effectively prevented from abnormally growing through diffusion welding at low temperature.

Description

Technical Field

[0001] The invention belongs to the technical field of alloy target materials, and in particular relates to a welding method for a high-purity aluminum target material. Background Art

[0002] Sputtering targets have many applications in the semiconductor industry, storage media industry, and advanced display industry. High-purity aluminum targets are also a kind of metal material with special uses, and their use value and use targets are very clear. With the continuous development of magnetron sputtering technology, electronic, optical, magnetic and superconducting thin films have been developed and applied on a large scale in the field of high-tech industries, and the types of target materials and market size are also increasing.

[0003] In the existing technology, the diffusion welding of aluminum target blank and copper back plate is usually carried out at about 400°C. At this temperature, the grains of high-purity aluminum target blank are prone to recrystallization and growth, which in turn affects the sputtering effect. When diffusion welding is carried out at low temperature, it is difficult to form an effective diffusion layer between aluminum and copper atoms. Even if they can be combined, the welding strength is far from meeting the requirements for safe use. Summary of the invention

[0004] The object of the present invention is to overcome the above-mentioned deficiencies of the prior art and to provide a method for welding a high-purity aluminum target material with high welding strength and small average grain size in the high-purity aluminum target material.

[0005] To achieve the above object, in a first aspect of the present invention, the present invention provides a welding method for a high-purity aluminum target, the welding method comprising the following steps:

[0006] (1) machining a copper back plate to form an assembly groove for a high-purity aluminum target blank, then turning a thread on the surface to be welded, and then coating the surface to be welded with an aluminum film to obtain a coated copper back plate;

[0007] (2) assembling the pretreated high-purity aluminum target blank and the coated copper back plate to obtain an assembled component, and then placing the assembled component in a package for degassing and hot isostatic pressing to obtain a welded high-purity aluminum target component;

[0008] The thickness of the aluminum film is 3-7 μm;

[0009] The temperature of the hot isostatic pressing treatment is ≥200°C.

[0010] In a welding method for a high-purity aluminum target provided by the present invention, firstly, a flat thread is turned on the surface to be welded of a copper alloy back plate, and then an aluminum film is plated on the surface to be welded within a certain thickness range, then the copper alloy back plate plated with the aluminum film and the high-purity aluminum target blank are assembled, and the assembled target assembly is placed in a package for degassing treatment, and finally hot isostatic pressing diffusion welding is performed at a temperature of 200-280°C; the aluminum-copper target prepared by the welding method provided by the present invention has good welding bonding strength and can be better applied to sputtering at high temperatures; and diffusion welding at low temperatures can effectively prevent abnormal growth of high-purity aluminum target grains, so that the deposition speed of the target is faster when used, and the deposited film is more evenly distributed, that is, the deposition effect is better.

[0011] Exemplarily, the thickness of the aluminum film may be any point value or any two point range value between 3-7 μm, such as 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, etc.

[0012] The present invention has found that the introduction of an aluminum film within a specific thickness range can form a uniform solid-state connection between the copper backing plate and the aluminum target, thereby improving the welding strength of the two; especially when the thickness of the aluminum film is further selected within the above range, the obtained welding strength is even greater.

[0013] Preferably, the temperature of the hot isostatic pressing treatment is 200-280°C.

[0014] The present invention has found that when the temperature of the hot isostatic pressing treatment is further selected to be 200-280°C, the average grain size of the obtained product is smaller.

[0015] As a preferred embodiment of the welding method of the present invention, the thread pitch is 0.2-0.6 mm, and the thread depth is 0.1-0.4 mm.

[0016] For example, the thread pitch may be any point value or any range value between 0.2-0.6 mm, such as 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm, etc. The thread depth may be any point value or any range value between 0.1-0.4 mm, such as 0.1 mm, 0.2 mm, 0.3 mm, 0.4 mm, etc.

[0017] The present invention has found that turning threads on the surface of the copper back plate to be welded can effectively enhance the bonding force between the copper back plate and the aluminum target, thereby improving the welding strength between the two; especially when the thread pitch and thread depth of the turned threads are further selected within the above range, the welding strength between the copper back plate and the aluminum target is higher.

[0018] As a preferred embodiment of the welding method of the present invention, the aluminum-plated film is a vacuum magnetron sputtering aluminum-plated film, in which the current is 60-80A, the bias voltage is 60-80V, the temperature is 120-150°C, and the time is 1-3h.

[0019] The present invention has found that when vacuum magnetron sputtering is selected for aluminum coating and the parameters of vacuum magnetron sputtering for aluminum coating are selected within the above range, the uniformity of the aluminum film can be ensured, thereby effectively improving the welding strength between the copper back plate and the aluminum target.

[0020] As a preferred embodiment of the welding method of the present invention, the assembly gap is 0.2-0.5 mm.

[0021] As a preferred embodiment of the welding method of the present invention, the pressure of the hot isostatic pressing treatment is 100-150 MPa and the time is 2-3 hours.

[0022] Exemplarily, the pressure of the hot isostatic pressing treatment can be any point value or any two point range values ​​between 100-150MPa, for example, 100MPa, 110MPa, 120MPa, 130MPa, 140MPa, 150MPa, etc.; the time can be any point value or any two point range values ​​between 2-3h, for example, 2h, 2.2h, 2.4h, 2.6h, 2.8h, 3h, etc.

[0023] The present invention has found that the pressure and time during the hot isostatic pressing process will not only affect the welding strength between the copper back plate and the aluminum target, but also affect the average grain size of the prepared aluminum target; when the pressure and time of the hot isostatic pressing treatment are further selected to be within the above range, the welding strength of the obtained product copper back plate and the aluminum target is large, and the average grain size in the aluminum target is small.

[0024] As a preferred embodiment of the welding method of the present invention, the degassing is performed at 130-180°C, and the vacuum degree after degassing is less than 1.3×10 -3 Mpa.

[0025] As a preferred embodiment of the welding method of the present invention, before the aluminum film is plated on the surface to be welded, the method further includes the step of cleaning the copper back plate with a cleaning liquid and then drying it;

[0026] The cleaning solution comprises sodium molybdate, tartaric acid, sodium bisulfate and water in a volume ratio of (0.5-2):(1-2):(1-3):(5-6);

[0027] The drying is performed under vacuum at 65-75° C. for 0.5-2 h.

[0028] Preferably, after cleaning the copper back plate with a cleaning solution, the method further includes washing with pure water and ultrasonic cleaning with isopropyl alcohol.

[0029] Preferably, the ultrasonic cleaning time is 1-3 min.

[0030] As a preferred embodiment of the welding method of the present invention, the pretreatment includes cleaning with a pickling solution and then drying;

[0031] The pickling solution comprises hydrofluoric acid, nitric acid and water in a volume ratio of (1-1.5):(3-4):(4-5);

[0032] The drying is performed under vacuum at 50-75° C. for 1-2 h.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] In a welding method for a high-purity aluminum target provided by the present invention, firstly, a flat thread is turned on the surface to be welded of a copper alloy back plate, and then an aluminum film is plated on the surface to be welded within a certain thickness range, then the copper alloy back plate plated with the aluminum film and the high-purity aluminum target blank are assembled, and the assembled target material component is placed in a package for degassing treatment, and finally hot isostatic pressing diffusion welding is performed at a temperature of ≥200°C; the aluminum-copper target material prepared by the welding method provided by the present invention has good welding bonding strength and can be better applied to sputtering at high temperatures; and diffusion welding at low temperatures can effectively prevent abnormal growth of high-purity aluminum target material grains, so that the deposition speed of the target material will be faster when used, and the deposited film will be more evenly distributed, that is, the deposition effect will be better. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 This is a schematic diagram of the assembly in Example 1:

[0036] 1- Turning thread, 2- Aluminum film. DETAILED DESCRIPTION

[0037] In order to better illustrate the purpose, technical solutions and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments.

[0038] Unless otherwise specified, the reagents, methods and equipment used in the present invention are all conventional reagents, methods and equipment in the art; and unless otherwise specified, the raw materials used in parallel experiments are from the same batch of raw materials.

[0039] Example 1

[0040] An embodiment of the present invention provides a welding method for a high-purity aluminum target material, the welding method comprising the following steps:

[0041] (1) After machining the assembly groove of the high-purity aluminum target blank on the copper back plate, a thread is turned on the surface to be welded (the thread pitch is 0.2 mm and the depth is 0.15 mm), and then the copper back plate after the thread is turned is cleaned with a cleaning solution (a mixture of sodium molybdate, tartaric acid, sodium bisulfate and water in a volume ratio of 1:1:3:5). After cleaning with the cleaning solution, it is washed with pure water and ultrasonically cleaned with isopropanol for 2 minutes in sequence. After the cleaning is completed, it is placed in a vacuum dryer at 70°C for 1 hour; then a 4 μm thick aluminum film is vacuum magnetron sputtered (in the vacuum magnetron sputtering, the current is 65A, the bias voltage is 65V, the temperature is 120°C, and the time is 2 hours) to obtain a copper back plate after coating;

[0042] (2) The high-purity aluminum target blank was pickled for 2 minutes using an acid pickling solution (a mixture of hydrofluoric acid, nitric acid and water in a volume ratio of 1:4:5), and then vacuum dried at 70°C for 1 hour to obtain a pretreated high-purity aluminum target blank; the pretreated high-purity aluminum target blank and the plated copper back plate were assembled (the assembly gap was 0.3 mm, as shown in the schematic diagram). Figure 1 After assembly, the package was placed in a bag and degassed at 130°C to a vacuum degree of 1.5×10 -3 Mpa, and finally hot isostatic pressing diffusion welding for 3h at a temperature of 240℃ and a pressure of 110MPa.

[0043] Example 2

[0044] An embodiment of the present invention provides a welding method for a high-purity aluminum target material, the welding method comprising the following steps:

[0045] (1) After the assembly groove of the high-purity aluminum target blank is processed on the copper back plate, a thread is turned on the surface to be welded (the thread pitch is 0.45 mm and the depth is 0.2 mm), and then the copper back plate after the thread is turned is cleaned with a cleaning solution (a mixture of sodium molybdate, tartaric acid, sodium bisulfate and water in a volume ratio of 0.5:1.5:3:5). After cleaning with the cleaning solution, it is washed with pure water and ultrasonically cleaned with isopropanol for 2 minutes. After the cleaning, it is placed in a vacuum dryer at 70°C for 1.5 hours; then, an aluminum film with a thickness of 6 μm is vacuum magnetron sputtered (in the vacuum magnetron sputtering, the current is 70A, the bias voltage is 70V, the temperature is 130°C, and the time is 3 hours) to obtain a copper back plate after coating;

[0046] (2) The high-purity aluminum target blank was pickled for 2 min using an acid pickling solution (a mixture of hydrofluoric acid, nitric acid and water in a volume ratio of 1.5:4.5:4), and then vacuum dried at 70°C for 2 h to obtain a pretreated high-purity aluminum target blank; the pretreated high-purity aluminum target blank and the plated copper back plate were assembled (the assembly gap was 0.4 mm, as shown in the schematic diagram) Figure 1 After assembly, the package was placed in a bag and degassed at 140°C until the vacuum degree was 1.6×10 -3Mpa, and finally hot isostatic pressing diffusion welding for 2.5h at a temperature of 270℃ and a pressure of 120MPa.

[0047] Example 3

[0048] An embodiment of the present invention provides a welding method for a high-purity aluminum target material, the welding method comprising the following steps:

[0049] (1) After machining the assembly groove of the high-purity aluminum target blank on the copper back plate, a thread is turned on the surface to be welded (the thread pitch is 0.3 mm and the depth is 0.18 mm), and then the copper back plate after thread turning is cleaned with a cleaning solution (a mixture of sodium molybdate, tartaric acid, sodium bisulfate and water in a volume ratio of 1.5:2:2:4.5). After cleaning with the cleaning solution, the copper back plate is washed with pure water and ultrasonically cleaned with isopropanol for 2 minutes in sequence. After the cleaning, it is placed in a vacuum dryer at 70°C for 2 hours; then, an aluminum film with a thickness of 3.5 μm is vacuum magnetron sputtered (in the vacuum magnetron sputtering, the current is 75A, the bias voltage is 75V, the temperature is 140°C, and the time is 1 hour) to obtain a copper back plate after coating;

[0050] (2) The high-purity aluminum target blank was pickled for 2 minutes using an acid pickling solution (a mixture of hydrofluoric acid, nitric acid and water in a volume ratio of 1.5:4:4.5), and then vacuum dried at 70°C for 1.5 hours to obtain a pretreated high-purity aluminum target blank; the pretreated high-purity aluminum target blank and the plated copper back plate were assembled (the assembly gap was 0.5 mm, as shown in the schematic diagram) Figure 1 After assembly, the package was placed in a bag and degassed at 130°C until the vacuum degree was 1.7×10 -3 Mpa, and finally hot isostatic pressing diffusion welding for 2h at a temperature of 210℃ and a pressure of 130MPa.

[0051] Example 4

[0052] The embodiment of the present invention provides a welding method for a high-purity aluminum target material. The only difference between the welding method and embodiment 1 is that the thread pitch is 0.8 mm and the depth is 0.5 mm.

[0053] Example 5

[0054] The embodiment of the present invention provides a welding method for a high-purity aluminum target material. The only difference between the welding method and the embodiment 1 is that the temperature of the hot isostatic pressing treatment is 300°C.

[0055] Comparative Example 1

[0056] The comparative example of the present invention provides a welding method for a high-purity aluminum target material. The only difference between the welding method and Example 1 is that the temperature of the hot isostatic pressing treatment is 140°C.

[0057] Comparative Example 2

[0058] The comparative example of the present invention provides a welding method for a high-purity aluminum target material. The only difference between the welding method and Example 1 is that no thread turning is performed.

[0059] Comparative Example 3

[0060] The comparative example of the present invention provides a welding method for a high-purity aluminum target material. The only difference between the welding method and Example 1 is that no aluminum film is plated.

[0061] Comparative Example 4

[0062] The comparative example of the present invention provides a welding method for a high-purity aluminum target material. The only difference between the welding method and Example 1 is that the thickness of the aluminum film is 10 μm.

[0063] Effect example

[0064] The effect examples of the present invention verify the performance of the high-purity aluminum targets prepared in Examples 1-5 and Comparative Examples 1-4, including the following parts:

[0065] 1. Welding strength: tested by tensile testing machine;

[0066] 2. Average grain size of high purity aluminum target: tested using a metallographic microscope;

[0067] The obtained results are shown in Table 1;

[0068] Table 1

[0069]

[0070] It can be seen from Table 1 that the preparation method provided by the present invention can effectively improve the welding strength between the copper back plate and the aluminum target and reduce the average grain size of the aluminum target; specifically, the welding strength obtained by the welding method of the present invention is above 10MPa, and the average grain size is below 203μm;

[0071] It can be seen from Example 1 and Comparative Example 1 that when the temperature in the hot isostatic pressing treatment is too low, the obtained welding strength decreases significantly; it can be seen from Example 1 and Comparative Examples 2-3 that welding cannot be performed when the thread is not turned or the aluminum film is not plated; it can be seen from Example 1 and Comparative Example 4 that when the aluminum film is too thick, the obtained welding strength also decreases significantly.

[0072] Finally, it should be noted that the above embodiments are intended to illustrate the technical solution of the present invention rather than to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention may be modified or replaced by equivalents without departing from the essence and scope of the technical solution of the present invention.

Claims

1. A welding method for a high-purity aluminum target, characterized in that: The welding method comprises the following steps: (1) machining a copper back plate to form an assembly groove for a high-purity aluminum target blank, then turning a thread on the surface to be welded, and then coating the surface to be welded with an aluminum film to obtain a coated copper back plate; (2) assembling the pretreated high-purity aluminum target blank and the coated copper back plate to obtain an assembled component, and then placing the assembled component in a package for degassing and hot isostatic pressing to obtain a welded high-purity aluminum target component; The thickness of the aluminum film is 3-7 μm; The temperature of the hot isostatic pressing treatment is ≥200°C.

2. The welding method according to claim 1, characterized in that: The thread pitch is 0.2-0.6 mm, and the thread depth is 0.1-0.4 mm.

3. The welding method according to claim 1, characterized in that: The aluminum-plated film is a vacuum magnetron sputtering aluminum-plated film, in which the current is 60-80A, the bias voltage is 60-80V, the temperature is 120-150°C, and the time is 1-3h.

4. The welding method according to claim 1, characterized in that: The assembly gap is 0.2-0.5 mm.

5. The welding method according to claim 1, characterized in that: The hot isostatic pressing treatment is performed under a pressure of 100-150 MPa and for a time of 2-3 hours.

6. The welding method according to claim 1, characterized in that: The degassing is carried out at 130-180°C, and the vacuum degree after degassing is less than 1.3×10 -3 Mpa.

7. The welding method according to claim 1, characterized in that: Before the aluminum film is plated on the surface to be welded, the method also includes the steps of cleaning the copper back plate with a cleaning liquid and then drying it; The cleaning solution comprises sodium molybdate, tartaric acid, sodium bisulfate and water in a volume ratio of (0.5-2):(1-2):(1-3):(5-6); The drying is performed under vacuum at 65-75° C. for 0.5-2 h.

8. The welding method according to claim 1, characterized in that: The pretreatment includes washing with an acid wash solution and then drying; The pickling solution comprises hydrofluoric acid, nitric acid and water in a volume ratio of (1-1.5):(3-4):(4-5); The drying is performed under vacuum at 50-75° C. for 1-2 h.

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