Welding method for large-size tungsten-silicon alloy target material

Abstract

The invention relates to a welding method of a large-size tungsten-silicon alloy target material, which comprises the following steps: a back plate and a tungsten-silicon target material are respectively machined, the welding surface of the back plate is sequentially and concentrically provided with an assembly groove and a welding flux groove from top to bottom, the diameter of the welding flux groove is smaller than that of the target material, and a pretreated back plate and a pretreated target material are obtained; filling solder in a solder groove of the pretreated back plate, coating the solder on the welding surface of the pretreated target material, then heating the back plate and the target material to melt the solder, and then respectively performing infiltration treatment on the welding surfaces of the back plate and the target material to obtain the infiltrated back plate and target material; and the infiltrated back plate and the target material are assembled to obtain a target material assembly, the target material assembly is pressurized and then cooled, and the welded target material assembly is obtained. According to the welding method provided by the invention, the welding bonding strength of the target material and the back plate can be effectively improved, the target material assembly is prevented from being unsoldered and cracked, and deformation caused by welding is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of target materials, and in particular to a welding method for a large-size tungsten-silicon alloy target material. Background Art

[0002] In the semiconductor field, tungsten silicon targets play an important role and are widely used in gate materials and barrier layers. During the sputtering process, the target needs to undergo repeated heating, so the target must have good welding strength and low welding stress when used to avoid desoldering, cracking and other undesirable problems, thereby ensuring the stability and reliability of semiconductor devices.

[0003] However, tungsten silicon is a cemented carbide material with relatively poor toughness. It is very easy to crack during uneven heating and cooling or deformation, which makes it difficult to weld large-sized tungsten silicon targets (diameter ≥ 420mm, thickness ≤ 13mm). At present, welding methods such as brazing and diffusion welding have been widely used in the manufacture of target components, but these methods still have some limitations. Taking hot isostatic pressing welding as an example, after hot isostatic pressing welding is completed, the sheath is not easy to remove and is easy to adhere to the target component, thereby easily damaging the target component.

[0004] For example, CN104259644A discloses a tungsten-titanium alloy target welding method, which includes: first providing a tungsten-titanium alloy target and a copper alloy backing plate; forming an aluminum or aluminum alloy layer on the welding surface of the tungsten-titanium target; and then connecting the tungsten-titanium alloy target to the copper alloy backing plate by diffusion welding. Although this method can obtain a target assembly, it is difficult to further improve the welding strength, and the preparation method is complicated, which easily leads to deformation of the target assembly.

[0005] Therefore, how to solve the desoldering and cracking problems that occur during the welding process of large-size tungsten silicon targets, improve the welding strength of the target assembly, and reduce the deformation of the target assembly are technical problems that need to be solved in this field. Summary of the invention

[0006] In view of the above problems, the purpose of the present invention is to provide a welding method for large-size tungsten-silicon alloy targets. Compared with the prior art, the welding method provided by the present invention can effectively improve the welding bonding strength between the target and the backing plate, avoid desoldering and cracking of the target assembly, and reduce deformation caused by welding.

[0007] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0008] The present invention provides a welding method for a large-size tungsten-silicon alloy target, the welding method comprising the following steps:

[0009] (1) machining a back plate and a tungsten silicon target respectively, and concentrically setting an assembly groove and a solder groove on the welding surface of the back plate from top to bottom, wherein the diameter of the solder groove is less than the diameter of the target, to obtain a pre-treated back plate and a pre-treated target;

[0010] (2) filling the solder groove of the pretreated backplane obtained in step (1) with solder, coating the solder on the welding surface of the pretreated target material, then heating the backplane and the target material to melt the solder, and then performing infiltration treatment on the welding surfaces of the backplane and the target material respectively to obtain the infiltrated backplane and target material;

[0011] (3) Assembling the infiltrated backing plate and target material obtained in step (2) to obtain a target material assembly, pressurizing the target material assembly, and then cooling it to obtain a welded target material assembly.

[0012] In the preparation method provided by the present invention, by setting an assembly groove and a solder groove, the docking of the target material and the back plate is guaranteed, and sufficient solder can be filled in the solder groove to avoid the problem of insufficient solder, thereby fully wetting the welding surface, further improving the bonding strength between the solder and the welding surface, and enhancing the firmness of the welding. Subsequently, the tiny gaps in the welding process can be effectively eliminated through pressurization treatment, so that the solder can more fully fill the welding surface, further enhancing the welding strength.

[0013] Preferably, the back plate in step (1) comprises a copper-chromium alloy back plate.

[0014] Preferably, the diameter of the tungsten silicon target in step (1) is ≥420 mm, for example, it can be 420 mm, 430 mm, 440 mm or 450 mm, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0015] Preferably, the thickness of the tungsten silicon target is ≤13 mm, for example, it can be 13 mm, 12 mm, 11 mm or 10 mm, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0016] Preferably, after the machining in step (1), the surface roughness Ra of the backplate is 4-8 μm, for example, it can be 4 μm, 4.5 μm, 5 μm, 5.5 μm, 6 μm, 6.5 μm, 7 μm, 7.5 μm or 8 μm, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0017] Preferably, after machining, the surface roughness Ra of the tungsten silicon target is 7-12μm, for example, it can be 7μm, 7.5μm, 8μm, 8.5μm, 9μm, 9.5μm, 10μm, 10.5μm, 11μm, 11.5μm or 12μm, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0018] In the present invention, by preferably controlling the surface roughness of the back plate and the target material within a specific range, it can help the solder to fully and evenly wet the welding surface, so that the solder can better spread and fill the welding area, reduce welding defects, and improve welding strength.

[0019] Preferably, the difference between the diameter of the solder groove in step (1) and the diameter of the target material is 4-6 mm, for example, it can be 4 mm, 4.5 mm, 5 mm, 5.5 mm or 6 mm, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0020] In the present invention, by preferably controlling the difference between the diameter of the solder groove and the diameter of the target material within a specific range, the solder can be effectively prevented from overflowing during the welding process, ensuring that the solder is evenly distributed during the welding process, while ensuring that the contact area between the solder and the target material and the back plate is appropriate, thereby ensuring the welding strength.

[0021] Preferably, the depth of the solder groove is 2-4 mm, for example, it can be 2 mm, 2.2 mm, 2.4 mm, 2.6 mm, 2.8 mm, 3 mm, 3.2 mm, 3.4 mm, 3.6 mm, 3.8 mm or 4 mm, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0022] In the present invention, by preferably controlling the depth of the solder groove, it is possible to ensure that the solder is filled in an appropriate amount during the welding process. During the wetting treatment, the solder in the solder groove is introduced into the welding surface of the back plate, thereby improving the welding strength and avoiding excessive solder filling that causes solder escape, resulting in welding defects and affecting the welding quality; at the same time, avoiding insufficient solder filling that causes the welding gap to be unable to be filled, thereby avoiding affecting the firmness and reliability of the welding.

[0023] Preferably, the solder in step (2) comprises indium solder.

[0024] Preferably, the heating temperature rise rate is ≤10°C / min, for example, it can be 10°C / min, 9°C / min, 8°C / min, 7°C / min, 6°C / min, 5°C / min, 4°C / min, 3°C / min, 2°C / min or 1°C / min, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0025] Preferably, the terminal temperature of the heating is 190-230°C, for example, it can be 190°C, 195°C, 200°C, 205°C, 210°C, 215°C, 220°C, 225°C or 230°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0026] Preferably, the infiltration treatment in step (2) is carried out under ultrasonic conditions.

[0027] Preferably, the frequency of the ultrasound is 15-25kHz, for example, it can be 15kHz, 16kHz, 17kHz, 18kHz, 19kHz, 20kHz, 21kHz, 22kHz, 23kHz, 24kHz or 25kHz, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0028] Preferably, the amplitude of the ultrasonic wave is 5-45 μm, for example, 5 μm, 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm or 45 μm, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0029] Preferably, the power of the ultrasound is 800-2000W, for example, it can be 800W, 900W, 1000W, 1100W, 1200W, 1300W, 1400W, 1500W, 1600W, 1700W, 1800W, 1900W or 2000W, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0030] Preferably, the time for the wetting treatment of the backplane is 5-15 minutes, for example, it can be 5 minutes, 6 minutes, 8 minutes, 10 minutes, 12 minutes, 14 minutes or 15 minutes, but it is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0031] Preferably, the wetting treatment time of the tungsten silicon target is 15-25 min, for example, it can be 15 min, 16 min, 17 min, 18 min, 19 min, 20 min, 21 min, 22 min, 23 min, 24 min or 25 min, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0032] In the present invention, by preferably controlling the frequency, amplitude, power of the ultrasonic wave in the wetting process and the time of the wetting process, the solder can be spread and fill the welding gap better, thereby improving the welding strength.

[0033] Preferably, the pressure of the pressurization treatment in step (3) is 5-10 MPa, for example, it can be 5 MPa, 5.5 MPa, 6 MPa, 6.5 MPa, 7 MPa, 7.5 MPa, 8 MPa, 8.5 MPa, 9 MPa, 9.5 MPa or 10 MPa, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0034] Preferably, the pressurization treatment comprises: placing a pressing block on the upper surface of the target assembly.

[0035] Preferably, the contact area between the pressing block and the target assembly accounts for ≥ 60% of the upper surface area, for example, it can be 60%, 65%, 70%, 75%, 80%, 85% or 90%, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0036] In the present invention, by preferably controlling the pressure of the pressurization treatment and the ratio of the contact area between the pressing block and the target assembly to the upper surface area, the densification of the welding can be promoted, welding defects can be reduced, stress concentration during welding can be reduced, and excessive deformation of the target assembly can be avoided.

[0037] Preferably, the cooling rate in step (3) is ≤10°C / min, for example, it can be 10°C / min, 9°C / min, 8°C / min, 7°C / min, 6°C / min or 5°C / min, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0038] As a preferred technical solution of the present invention, the preparation method comprises the following steps:

[0039] (1) machining a copper-chromium alloy back plate and a tungsten silicon target respectively, wherein an assembly groove and a solder groove are concentrically arranged on the welding surface of the back plate from top to bottom, the depth of the solder groove is 2-4 mm, the diameter of the solder groove is less than the diameter of the target and the difference is 4-6 mm, the surface roughness Ra of the machining back plate is 4-8 μm, and the surface roughness Ra of the tungsten silicon target is 7-12 μm, thereby obtaining a pretreated back plate and a pretreated target;

[0040] (2) filling the solder groove of the pretreated backplane obtained in step (1) with indium solder, coating the welding surface of the pretreated target with indium solder, and then heating the backplane and the target at a heating rate of ≤10°C / min to an end temperature of 190-230°C to melt the solder, and then performing infiltration treatment on the welding surfaces of the backplane and the target respectively, wherein the infiltration treatment is performed under ultrasonic conditions, the frequency of the ultrasonic wave is 15-25kHz, the amplitude of the ultrasonic wave is 5-45μm, the power of the ultrasonic wave is 800-2000W, the infiltration treatment time of the backplane is 5-15min, and the infiltration treatment time of the tungsten silicon target is 15-25min, to obtain the infiltrated backplane and target;

[0041] (3) Assembling the infiltrated backing plate and target material obtained in step (2) to obtain a target material assembly, subjecting the target material assembly to a pressurization treatment at a pressure of 5-10 MPa, and then cooling at a rate of ≤10°C / min to obtain a welded target material assembly.

[0042] Compared with the prior art, the present invention has the following beneficial effects:

[0043] In the preparation method provided by the present invention, the target material and the back plate are connected by providing an assembly groove and a solder groove, and sufficient solder can be filled in the solder groove to avoid the problem of insufficient solder, thereby fully wetting the welding surface, and the small gaps in the welding process are eliminated by pressurization, so that the solder can more fully fill the welding surface, further enhance the welding strength, and prevent the target material assembly from excessive deformation. Under optimal conditions, the preparation method provided by the present invention can make the welding bonding strength of the target material assembly reach more than 20MPa and the deformation reach less than 0.1mm. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 is a schematic structural diagram of a target material assembly provided in Example 1 of the present invention;

[0045] 1-target material; 2-back plate; 3-assembly slot; 4-solder slot. DETAILED DESCRIPTION

[0046] The technical solution of the present invention is further described below by specific implementation methods. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0047] Example 1

[0048] This embodiment provides a welding method for a large-sized tungsten-silicon alloy target, and the preparation method comprises the following steps:

[0049] (1) machining a copper-chromium alloy back plate and a tungsten silicon target (with a diameter of 420 mm and a thickness of 13 mm), respectively, wherein the surface roughness Ra of the back plate after machining is 6 μm, and the surface roughness Ra of the tungsten silicon target is 10 μm, to obtain a pretreated back plate and a pretreated target;

[0050] like Figure 1 As shown, the machining also includes concentrically setting the assembly groove 3 and the solder groove 4 on the welding surface of the back plate 2 from top to bottom, the depth of the solder groove 4 is 3 mm, and the diameter of the solder groove 4 is less than the diameter of the target material 1 and the difference is 5 mm;

[0051] (2) filling the solder groove of the pretreated backplane obtained in step (1) with indium solder, coating the welding surface of the pretreated target with indium solder, and then heating the backplane and the target at a heating rate of 10°C / min to an end temperature of 210°C to melt the solder, and then performing infiltration treatment on the welding surfaces of the backplane and the target respectively, wherein the infiltration treatment is performed under ultrasonic conditions, the frequency of the ultrasonic wave is 20kHz, the amplitude of the ultrasonic wave is 25μm, the power of the ultrasonic wave is 1400W, the infiltration treatment time of the backplane is 10min, and the infiltration treatment time of the tungsten silicon target is 20min, to obtain the infiltrated backplane and target;

[0052] (3) Assembling the wetted backing plate and target material obtained in step (2) to obtain a target material assembly, placing a pressing block on the upper surface of the target material assembly for pressurization treatment, wherein the contact area between the pressing block and the target material assembly accounts for 60% of the upper surface area, and the pressure of the pressurization treatment is 8 MPa, and then cooling at a rate of 10°C / min to obtain a welded target material assembly.

[0053] Example 2

[0054] This embodiment provides a welding method for a large-sized tungsten-silicon alloy target, and the preparation method comprises the following steps:

[0055] (1) A copper-chromium alloy back plate and a tungsten silicon target (with a diameter of 420 mm and a thickness of 13 mm) were machined respectively, and an assembly groove and a solder groove were concentrically arranged on the welding surface of the back plate from top to bottom, the depth of the solder groove was 2 mm, the diameter of the solder groove was less than the diameter of the target and the difference was 4 mm, and the surface roughness Ra of the back plate after machining was 8 μm, and the surface roughness Ra of the tungsten silicon target was 7 μm, thereby obtaining a pretreated back plate and a pretreated target;

[0056] (2) filling the solder groove of the pretreated backplane obtained in step (1) with indium solder, coating the welding surface of the pretreated target with indium solder, and then heating the backplane and the target at a heating rate of 8°C / min to an end temperature of 230°C to melt the solder, and then performing infiltration treatment on the welding surfaces of the backplane and the target respectively, wherein the infiltration treatment is performed under ultrasonic conditions, the ultrasonic frequency is 15kHz, the ultrasonic amplitude is 45μm, the ultrasonic power is 800W, the infiltration treatment time of the backplane is 15min, and the infiltration treatment time of the tungsten silicon target is 15min, to obtain the infiltrated backplane and target;

[0057] (3) Assembling the wetted backing plate and target material obtained in step (2) to obtain a target material assembly, placing a pressing block on the upper surface of the target material assembly for pressurization treatment, wherein the contact area between the pressing block and the target material assembly accounts for 65% of the upper surface area, and the pressure of the pressurization treatment is 5 MPa, and then cooling at a rate of 8°C / min to obtain a welded target material assembly.

[0058] Example 3

[0059] This embodiment provides a welding method for a large-sized tungsten-silicon alloy target, and the preparation method comprises the following steps:

[0060] (1) A copper-chromium alloy back plate and a tungsten silicon target (with a diameter of 420 mm and a thickness of 13 mm) were machined respectively, and an assembly groove and a solder groove were concentrically arranged on the welding surface of the back plate from top to bottom, the depth of the solder groove was 4 mm, the diameter of the solder groove was less than the diameter of the target and the difference was 6 mm, and the surface roughness Ra of the back plate after machining was 4 μm, and the surface roughness Ra of the tungsten silicon target was 12 μm, thereby obtaining a pretreated back plate and a pretreated target;

[0061] (2) filling the solder groove of the pretreated backplane obtained in step (1) with indium solder, coating the welding surface of the pretreated target with indium solder, and then heating the backplane and the target at a heating rate of 6°C / min to an end temperature of 190°C to melt the solder, and then performing infiltration treatment on the welding surfaces of the backplane and the target respectively, wherein the infiltration treatment is performed under ultrasonic conditions, the ultrasonic frequency is 25kHz, the ultrasonic amplitude is 5μm, the ultrasonic power is 2000W, the infiltration treatment time of the backplane is 5min, and the infiltration treatment time of the tungsten silicon target is 25min, to obtain the infiltrated backplane and target;

[0062] (3) Assembling the wetted backing plate and target material obtained in step (2) to obtain a target assembly, placing a pressing block on the upper surface of the target assembly for pressurization treatment, wherein the contact area between the pressing block and the target assembly accounts for 75% of the upper surface area, and the pressure of the pressurization treatment is 10 MPa, and then cooling at a rate of 9°C / min to obtain a welded target assembly.

[0063] Example 4

[0064] This embodiment provides a welding method for a large-sized tungsten-silicon alloy target. The difference between the preparation method and the embodiment 1 is that the surface roughness Ra of the tungsten-silicon target after machining is 3 μm.

[0065] Example 5

[0066] This embodiment provides a welding method for a large-sized tungsten-silicon alloy target. The difference between the preparation method and the embodiment 1 is that the surface roughness Ra of the tungsten-silicon target after machining is 20 μm.

[0067] Example 6

[0068] This embodiment provides a welding method for a large-sized tungsten-silicon alloy target. The difference between the preparation method and the embodiment 1 is that the difference between the diameter of the solder groove and the diameter of the target is 1 mm.

[0069] Example 7

[0070] This embodiment provides a welding method for a large-sized tungsten-silicon alloy target. The difference between the preparation method and the embodiment 1 is that the difference between the diameter of the solder tank and the diameter of the target is 10 mm.

[0071] Example 8

[0072] This embodiment provides a welding method for a large-sized tungsten-silicon alloy target. The difference between the preparation method and the embodiment 1 is that the power of the ultrasonic wave is 500W.

[0073] Example 9

[0074] This embodiment provides a welding method for a large-sized tungsten-silicon alloy target. The difference between the preparation method and the embodiment 1 is that the frequency of the ultrasonic wave is 10 kHz.

[0075] Example 10

[0076] This embodiment provides a welding method for a large-sized tungsten-silicon alloy target. The difference between the preparation method and the embodiment 1 is that the pressure of the pressurization treatment is 2 MPa.

[0077] Embodiment 11

[0078] This embodiment provides a welding method for a large-sized tungsten-silicon alloy target. The difference between the preparation method and the embodiment 1 is that the pressure of the pressurization treatment is 15 MPa.

[0079] Example 12

[0080] This embodiment provides a welding method for a large-sized tungsten-silicon alloy target. The difference between the preparation method and the embodiment 1 is that the contact area between the pressing block and the target assembly accounts for 40% of the upper surface area.

[0081] Comparative Example 1

[0082] This comparative example provides a welding method for a large-sized tungsten-silicon alloy target material, which is different from Example 1 only in that no solder groove is provided, and the solder is only applied to the welding surface of the back plate.

[0083] The welding strength of the target material assemblies in Examples 1-12 and Comparative Example 1 was tested by a tensile test. The results are shown in Table 1.

[0084] The deformation of the target material assemblies in Examples 1-12 and Comparative Example 1 was tested using a three-dimensional coordinate measuring machine. The results are shown in Table 1.

[0085] Table 1

[0086] Welding strength / MPa Deformation / mm Example 1 23 0.05 Example 2 22 0.07 Example 3 20 0.08 Example 4 18 0.05 Example 5 15 0.05 Example 6 17 0.07 Example 7 12 0.05 Example 8 11 0.05 Example 9 10 0.05 Example 10 13 0.03 Embodiment 11 23 0.24 Example 12 20 0.18 Comparative Example 1 8 0.04

[0087] From the data in Table 1, we can see the following points:

[0088] (1) From the data of Examples 1-12, it can be seen that under optimal conditions, the preparation method provided by the present invention can make the welding bonding strength of the target assembly reach above 20 MPa and the deformation reach below 0.1 mm.

[0089] (2) A comprehensive comparison of the data of Example 1 and Examples 4-5 shows that the present invention can help the solder to fully and evenly wet the welding surface and improve the welding strength by preferentially controlling the surface roughness of the back plate and the target material.

[0090] (3) Comprehensive comparison of the data of Example 1, Examples 6-7 and Comparative Example 1 shows that the present invention can effectively prevent solder from overflowing during the welding process by setting a solder groove on the back plate and preferably controlling the difference between the diameter of the solder groove and the diameter of the target material, thereby ensuring that the solder is evenly distributed during the welding process and ensuring that the contact area between the solder and the target material and the back plate is appropriate, thereby ensuring the welding strength.

[0091] (4) A comprehensive comparison of the data of Example 1 and Examples 8-9 shows that the present invention can help the solder to fully and evenly wet the welding surface and improve the welding strength by optimally controlling the frequency and power of the ultrasonic wave.

[0092] (5) A comprehensive comparison of the data of Example 1 and Examples 10-12 shows that the present invention can improve the welding strength while avoiding excessive deformation of the target material by preferentially controlling the pressure of the pressurization treatment and the ratio of the contact area between the pressing block and the target material assembly to the upper surface area.

[0093] In summary, the welding method provided by the present invention can effectively improve the welding bonding strength between the target material and the back plate, avoid desoldering and cracking of the target material assembly, and reduce deformation caused by welding.

[0094] The applicant declares that the above is only a specific implementation mode 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 thought of by those skilled in the art within the technical scope disclosed by the present invention are within the protection scope and disclosure scope of the present invention.

Claims

1. A welding method for a large-size tungsten-silicon alloy target, characterized in that: The welding method comprises the following steps: (1) machining a back plate and a tungsten silicon target respectively, and concentrically setting an assembly groove and a solder groove on the welding surface of the back plate from top to bottom, wherein the diameter of the solder groove is less than the diameter of the target, to obtain a pre-treated back plate and a pre-treated target; (2) filling the solder groove of the pretreated backplane obtained in step (1) with solder, coating the solder on the welding surface of the pretreated target material, then heating the backplane and the target material to melt the solder, and then performing infiltration treatment on the welding surfaces of the backplane and the target material respectively to obtain the infiltrated backplane and target material; (3) Assembling the infiltrated backing plate and target material obtained in step (2) to obtain a target material assembly, pressurizing the target material assembly, and then cooling it to obtain a welded target material assembly.

2. The welding method according to claim 1, characterized in that: The back plate in step (1) comprises a copper-chromium alloy back plate.

3. The welding method according to claim 1 or 2, characterized in that: The diameter of the tungsten silicon target in step (1) is ≥420 mm; Preferably, the thickness of the tungsten silicon target is ≤13 mm.

4. The welding method according to any one of claims 1 to 3, characterized in that After the machining in step (1), the surface roughness Ra of the back plate is 4-8 μm; Preferably, after the machining, the surface roughness Ra of the tungsten silicon target is 7-12 μm.

5. The welding method according to any one of claims 1 to 4, characterized in that The difference between the diameter of the solder tank in step (1) and the diameter of the target material is 4-6 mm; Preferably, the depth of the solder groove is 2-4 mm.

6. The welding method according to any one of claims 1 to 5, characterized in that: The solder in step (2) comprises indium solder; Preferably, the heating rate is ≤10°C / min; Preferably, the terminal temperature of the heating is 190-230°C.

7. The welding method according to any one of claims 1 to 6, characterized in that: The infiltration treatment in step (2) is carried out under ultrasonic conditions; Preferably, the frequency of the ultrasonic wave is 15-25kHz; Preferably, the amplitude of the ultrasonic wave is 5-45 μm; Preferably, the power of the ultrasonic wave is 800-2000W; Preferably, the time for the infiltration treatment of the backplane is 5-15 minutes; Preferably, the tungsten silicon target is wetted for 15-25 minutes.

8. The preparation method according to any one of claims 1 to 7, characterized in that: The pressure of the pressurization treatment in step (3) is 5-10 MPa; Preferably, the pressurization treatment comprises: placing a pressing block on the upper surface of the target assembly; Preferably, the contact area between the pressing block and the target assembly accounts for ≥ 60% of the upper surface area.

9. The preparation method according to any one of claims 1 to 8, characterized in that: The cooling rate in step (3) is ≤10°C / min.

10. The preparation method according to any one of claims 1 to 9, characterized in that: The preparation method comprises the following steps: (1) machining a copper-chromium alloy back plate and a tungsten silicon target respectively, wherein an assembly groove and a solder groove are concentrically arranged on the welding surface of the back plate from top to bottom, the depth of the solder groove is 2-4 mm, the diameter of the solder groove is less than the diameter of the target and the difference is 4-6 mm, the surface roughness Ra of the machining back plate is 4-8 μm, and the surface roughness Ra of the tungsten silicon target is 7-12 μm, thereby obtaining a pretreated back plate and a pretreated target; (2) filling the solder groove of the pretreated backplane obtained in step (1) with indium solder, coating the welding surface of the pretreated target with indium solder, and then heating the backplane and the target at a heating rate of ≤10°C / min to an end temperature of 190-230°C to melt the solder, and then performing infiltration treatment on the welding surfaces of the backplane and the target respectively, wherein the infiltration treatment is performed under ultrasonic conditions, the frequency of the ultrasonic wave is 15-25kHz, the amplitude of the ultrasonic wave is 5-45μm, the power of the ultrasonic wave is 800-2000W, the infiltration treatment time of the backplane is 5-15min, and the infiltration treatment time of the tungsten silicon target is 15-25min, to obtain the infiltrated backplane and target; (3) Assembling the infiltrated backing plate and target material obtained in step (2) to obtain a target material assembly, subjecting the target material assembly to a pressurization treatment at a pressure of 5-10 MPa, and then cooling at a rate of ≤10°C / min to obtain a welded target material assembly.

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