Tungsten target material assembly and preparation method thereof

Abstract

The invention relates to a tungsten target material assembly and a preparation method thereof. The tungsten target material assembly sequentially comprises a tungsten target material, an aluminum middle layer and a back plate from top to bottom. The surface of the aluminum intermediate layer is provided with a porous oxide film. The porous oxidation film is arranged on the surface of the aluminum middle layer, the thickness of an element diffusion layer in tungsten and aluminum and the thickness of an element diffusion layer in aluminum and a back plate can be increased due to the existence of the porous oxidation film, the mechanical interlocking degree between every two adjacent layers is increased, and then the bonding strength of the tungsten target material assembly is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of semiconductor sputtering target materials, in particular to a tungsten target assembly and a preparation method thereof. BACKGROUND

[0002] Due to the difference in physical and metallurgical properties between tungsten and the backing plate, the interface bonding strength after welding is insufficient, and deformation, cracking of the welding interface, and even disbonding are prone to occur during sputtering, which seriously affects the stability of the sputtering process and the film quality.

[0003] CN113878221A provides a method for improving the welding bonding rate of a tungsten-containing target material, which comprises the following steps: cleaning the welding surface of the tungsten-containing target material, then coating the sputtering surface of the target material with a film by physical vapor deposition to obtain a coated target material; and welding the coated target material and the backing plate after infiltrating the solder on the welding surface to obtain a target assembly. The tungsten target material prepared by this method has a welding bonding rate of greater than 98.5%.

[0004] CN111014930A provides a two-step hot isostatic pressing diffusion welding method for a tungsten target assembly, which comprises the following steps: first, hot isostatic pressing diffusion welding of a tungsten target blank and an Al intermediate layer, and then second hot isostatic pressing diffusion welding of the tungsten target blank and the Al intermediate layer with a copper backing plate, to finally obtain a tungsten target assembly. The welding strength of the tungsten target blank-Al intermediate layer welding surface of the tungsten target assembly is ≥125MPa, the welding strength of the Al intermediate layer-copper backing plate welding surface is ≥65MPa, and the bonding rate of the two welding surfaces is >99.5%.

[0005] CN112846171A provides a powder layer for hot isostatic pressing diffusion welding of a tungsten target, which is composed of Ti, Al and Cu, and the mass fraction of each powder is Ti powder 15%-25%, Cu powder 15%-25%, and Al powder 50%-70%. The Ti and Cu components can bridge the physical property difference between the W target and the Cu backing plate; the Al component can release thermal stress and reduce the final deformation of the tungsten target, and finally obtain a welded assembly with a welding strength greater than 150MPa, a bonding rate >99.7%, and a tungsten target surface deformation <1mm.

[0006] CN113290293A provides a method for improving the brazing welding bonding rate of a tungsten target and a copper backing plate by coating a nickel film on the welding surface of the tungsten target using physical vapor deposition. The nickel film can enhance the wettability of the solder on the welding surface of the tungsten target and improve the welding bonding rate. The tungsten target prepared by this method has a welding qualification rate of ≥98%.

[0007] The existing tungsten target material welding method has the following problems: (1) the welding strength and welding bonding rate of the tungsten target material prepared by the traditional brazing method are low; (2) the thermal expansion coefficients of tungsten and copper are greatly different, and the welding interface is prone to thermal stress concentration during the welding process, and the target material is deformed after welding; (3) although the hot isostatic pressing welding can realize the element diffusion between W / Al and Al / Cu and improve the welding strength, the mechanical interlocking effect of the aluminum intermediate layer and the tungsten target blank and the copper back plate in the existing welding method is limited, and the welding strength is not obviously improved.

[0008] Therefore, it is necessary to develop a preparation method of a tungsten target material assembly, so that the tungsten target material assembly prepared has high welding strength, and the welding interface is tightly and uniformly bonded. SUMMARY

[0009] To solve the above technical problems, the present application provides a tungsten target material assembly and a preparation method thereof, wherein the intermediate layer of the tungsten target material assembly is an aluminum intermediate layer having a porous oxide film on the surface. The presence of the porous oxide film increases the thickness of the element diffusion layer between tungsten and aluminum and between aluminum and the back plate, increases the mechanical interlocking degree between the two adjacent layers, and improves the bonding strength of the tungsten target material assembly.

[0010] To achieve this purpose, the present application adopts the following technical solutions:

[0011] In a first aspect, the present application provides a tungsten target material assembly, which comprises, from top to bottom, a tungsten target material, an aluminum intermediate layer and a back plate.

[0012] The surface of the aluminum intermediate layer has a porous oxide film.

[0013] The difference in physical and metallurgical properties between tungsten and the back plate can lead to insufficient interface bonding strength after welding, and deformation, cracking of the welding interface and even disbonding are prone to occur during sputtering, which seriously affects the stability of the sputtering process and the film quality. The present application provides an aluminum intermediate layer having a porous oxide film between the tungsten target material and the back plate. The presence of the porous oxide film increases the thickness of the element diffusion layer between tungsten and aluminum and between aluminum and the back plate, increases the mechanical interlocking degree between the two adjacent layers, and improves the bonding strength of the tungsten target material assembly. At the same time, the uniformly distributed pores on the surface of the aluminum intermediate layer can effectively relieve the stress and strain concentration around the pores, reduce the thermal stress concentration at the contact interface caused by the large difference in thermal expansion coefficients between tungsten and the back plate, and effectively solve the problem of deformation of the target material assembly.

[0014] As a preferred technical solution of the present application, the two side surfaces of the aluminum intermediate layer each have a porous oxide film.

[0015] Preferably, the porous oxide film comprises an aluminum oxide film.

[0016] Preferably, the pore size of the porous oxide film is 20-100 nm, for example, it can be 20 nm, 40 nm, 60 nm, 80 nm or 100 nm, but is not limited to the listed values, and other values not listed in the above value range are also applicable.

[0017] In the present application, the pore size of the porous oxide film on the surface of the aluminum interlayer is 20-100 nm. The uniformly dispersed nanopores on the surface of the aluminum interlayer can effectively alleviate the stress and strain concentration around the pores, reduce the thermal stress concentration at the welding interface caused by the large difference in thermal expansion coefficient between tungsten and the backing plate during welding, and effectively improve the deformation problem of the tungsten target assembly after welding. If the pore size of the porous oxide film is less than 20 nm, the effective mechanical coupling between the layers during welding cannot be formed, which reduces the welding strength. If the pore size of the porous oxide film is greater than 100 nm, the tungsten element and the elements in the backing plate cannot fully diffuse into the porous oxide film, which reduces the welding strength and the welding bonding rate.

[0018] Preferably, the thickness of the porous oxide film is 10-20 μm, for example, it can be 10 μm, 12 μm, 14 μm, 16 μm, 18 μm or 20 μm, but is not limited to the listed values, and other values not listed in the above value range are also applicable.

[0019] In the present application, the thickness of the porous oxide film on the surface of the aluminum interlayer is 10-20 μm, which can effectively promote the element diffusion between tungsten and aluminum, aluminum and the backing plate, form an element diffusion layer, improve the welding strength of the tungsten target assembly, and increase the welding bonding rate. If the thickness of the porous oxide film is less than 10 μm, the element diffusion layer between tungsten and aluminum, aluminum and the backing plate will be too thin, which reduces the welding strength of the tungsten target assembly. If the thickness of the porous oxide film is greater than 20 μm, the tungsten element and the elements in the backing plate cannot fully diffuse into the porous oxide film, which is prone to cavities during welding, reducing the welding strength.

[0020] As a preferred technical solution of the present application, the diameter of the tungsten target is 200-300 mm, for example, it can be 200 mm, 220 mm, 240 mm, 260 mm, 280 mm or 300 mm, but is not limited to the listed values, and other values not listed in the above value range are also applicable.

[0021] Preferably, the thickness of the tungsten target 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 values not listed in the above value range are also applicable.

[0022] Preferably, the diameter of the aluminum intermediate layer is 200-300 mm, for example, can be 200 mm, 220 mm, 240 mm, 260 mm or 300 mm, but not limited to the listed values, other values not listed in the above range are also applicable.

[0023] Preferably, the thickness of the aluminum intermediate layer is 2-3 mm, for example, can be 2 mm, 2.2 mm, 2.4 mm, 2.6 mm, 2.8 mm or 3 mm, but not limited to the listed values, other values not listed in the above range are also applicable.

[0024] Preferably, the diameter of the back plate is 300-400 mm, for example, can be 300 mm, 320 mm, 340 mm, 360 mm or 400 mm, but not limited to the listed values, other values not listed in the above range are also applicable.

[0025] Preferably, the thickness of the back plate is 25-30 mm, for example, can be 25 mm, 26 mm, 27 mm, 28 mm, 29 mm or 30 mm, but not limited to the listed values, other values not listed in the above range are also applicable.

[0026] Preferably, the material of the back plate includes any one of copper, aluminum or stainless steel.

[0027] In a second aspect, the present application provides a preparation method of the tungsten target assembly according to the first aspect, the preparation method comprising the following steps:

[0028] (1) electrolytic treatment is performed with an aluminum plate as an anode and a lead plate as a cathode to obtain an aluminum plate with a porous oxide film on the surface;

[0029] (2) sequentially place the tungsten target material, the aluminum plate with the porous oxide film on the surface and the back plate from top to bottom, and perform hot isostatic pressing treatment to obtain the tungsten target assembly.

[0030] In the present application, the aluminum plate is used as an anode, and in the electrolytic treatment process, the anode undergoes oxidation reaction to form a porous oxide film on the surface of the aluminum plate. Then, the tungsten target material, the aluminum plate with the porous oxide film on the surface and the back plate are subjected to hot isostatic pressing treatment to form the tungsten target assembly. The porous oxide film on the surface of the aluminum plate increases the thickness of the diffusion layer of tungsten and aluminum and the diffusion layer of aluminum and the elements in the back plate during the hot isostatic pressing treatment, increases the mechanical interlocking degree between the two adjacent layers, and thus improves the welding strength of the tungsten target assembly. At the same time, the uniformly dispersed pores on the surface of the aluminum plate can effectively relieve the stress and strain concentration around the pores, reduce the welding interface thermal stress concentration caused by the large difference in thermal expansion coefficient between tungsten and the back plate during the hot isostatic pressing treatment, and effectively improve the deformation problem of the tungsten target assembly.

[0031] As a preferred technical solution of the present application, the temperature of the electrolytic treatment is 15-20℃, for example, it can be 15℃, 16℃, 17℃, 18℃, 19℃ or 20℃, but is not limited to the listed values, and other values not listed in the above value range are also applicable.

[0032] During the anodic oxidation process, a large amount of Joule heat is generated, and high temperature can cause the electrolyte to dissolve the oxide film, resulting in low film formation rate and poor film quality. Therefore, the present application controls the temperature at 15-20℃ by using water bath method, so as to form a uniform porous oxide film on the surface of the aluminum plate.

[0033] Preferably, the current density of the electrolytic treatment is 2-5A / dm 2 , for example, it can be 2A / dm 2 , 3A / dm 2 , 4A / dm 2 or 5A / dm 2 , but is not limited to the listed values, and other values not listed in the above value range are also applicable.

[0034] Preferably, the time of the electrolytic treatment is 30-60min, for example, it can be 30min, 40min, 50min or 60min, but is not limited to the listed values, and other values not listed in the above value range are also applicable.

[0035] Preferably, the electrolyte of the electrolytic treatment includes any one or a combination of at least two of sulfuric acid solution, oxalic acid solution or chromic acid solution, wherein a typical but non-limiting combination includes: a combination of sulfuric acid solution and oxalic acid solution, a combination of sulfuric acid solution and chromic acid solution, a combination of oxalic acid solution and chromic acid solution, a combination of sulfuric acid solution, oxalic acid solution and chromic acid solution.

[0036] Preferably, the mass fraction of the electrolyte is 10-30%, for example, it can be 10%, 15%, 20%, 25% or 30%, but is not limited to the listed values, and other values not listed in the above value range are also applicable.

[0037] As a preferred technical solution of the present application, the pore size of the porous oxide film on the surface of the aluminum plate is 20-100nm, for example, it can be 20nm, 40nm, 60nm, 80nm or 100nm, but is not limited to the listed values, and other values not listed in the above value range are also applicable.

[0038] Preferably, the thickness of the porous oxide film on the surface of the aluminum plate is 10-20μm, for example, it can be 10μm, 12μm, 14μm, 16μm, 18μm or 20μm, but is not limited to the listed values, and other values not listed in the above value range are also applicable.

[0039] As a preferred technical solution of the present application, the temperature of the hot isostatic pressing treatment is 300-400℃, for example, it can be 300℃, 320℃, 340℃, 360℃, 380℃ or 400℃, but is not limited to the listed values, and other values not listed in the above value range are also applicable.

[0040] The present application can realize the welding of the tungsten target assembly at 300-400℃, which is lower than the hot isostatic pressing welding temperature of the tungsten target assembly in the prior art. This is because the porous oxide film on the surface of the aluminum plate in the present application increases the thickness of the diffusion layer of tungsten and aluminum and the diffusion layer of aluminum and the elements in the back plate during the hot isostatic pressing treatment, and increases the mechanical interlocking degree between the two adjacent layers. If the temperature of the hot isostatic pressing treatment is lower than 300℃, it will lead to insufficient diffusion of aluminum and the back plate, and the interface bonding strength of the two is low. At the same time, too low temperature will lead to insufficient plastic deformation of aluminum and the back plate, which cannot compensate for the difference in thermal expansion coefficient between tungsten and the back plate. The interface of the tungsten target assembly prepared after cooling is prone to cracking. If the temperature of the hot isostatic pressing treatment is higher than 400℃, it will lead to uneven distribution of the interface composition, and the mechanical properties of the tungsten target assembly will decrease, and at the same time, it will cause waste of energy.

[0041] Preferably, the pressure of the hot isostatic pressing treatment is 150-220MPa, for example, it can be 150MPa, 170MPa, 190MPa, 210MPa or 220MPa, but is not limited to the listed values, and other values not listed in the above value range are also applicable.

[0042] Preferably, the time of the hot isostatic pressing treatment is 3-6h, for example, it can be 3h, 4h, 5h or 6h, but is not limited to the listed values, and other values not listed in the above value range are also applicable.

[0043] As a preferred technical solution of the present application, the preparation method further comprises: pretreating the aluminum plate before the electrolytic treatment.

[0044] Preferably, the pretreatment comprises alkaline cleaning, acid cleaning and water cleaning in sequence.

[0045] The present application first performs alkaline cleaning on the aluminum plate to remove dirt (industrial lubricating oil, impurities, etc.) on the surface of the aluminum plate and expose a clean surface, then performs acid cleaning to remove oxides on the surface of the aluminum plate and expose the aluminum matrix, and then performs water cleaning to remove residual acid.

[0046] Preferably, the alkaline solution used in the alkaline cleaning process comprises a sodium hydroxide solution and / or a sodium citrate solution.

[0047] Preferably, the mass fraction of the alkaline solution is 20-40%, for example, it can be 20%, 25%, 30%, 35% or 40%, but not limited to the listed values, other values not listed in the above value range are also applicable.

[0048] Preferably, the time of the alkaline cleaning is 15-20 min, for example, it can be 15 min, 16 min, 17 min, 18 min, 19 min or 20 min, but not limited to the listed values, other values not listed in the above value range are also applicable.

[0049] As a preferred technical solution of the present application, the acid solution used in the acid cleaning process includes nitric acid solution and / or hydrochloric acid solution.

[0050] Preferably, the mass fraction of the acid solution is 20-40%, for example, it can be 20%, 25%, 30%, 35% or 40%, but not limited to the listed values, other values not listed in the above value range are also applicable.

[0051] Preferably, the time of the acid cleaning is 15-20 min, for example, it can be 15 min, 16 min, 17 min, 18 min, 19 min or 20 min, but not limited to the listed values, other values not listed in the above value range are also applicable.

[0052] Preferably, the time of the water cleaning is 1-2 min, for example, it can be 1 min, 1.2 min, 1.4 min, 1.6 min, 1.8 min or 2 min, but not limited to the listed values, other values not listed in the above value range are also applicable.

[0053] As a preferred technical solution of the present application, the preparation method comprises the following steps:

[0054] (1) sequentially performing alkaline cleaning, acid cleaning and water cleaning on the aluminum plate to obtain a pretreated aluminum plate;

[0055] (2) taking the pretreated aluminum plate as an anode and taking a lead plate as a cathode to perform electrolytic treatment at a temperature of 15-20℃, a current density of 2-5 A / dm 2 , and a time of 30-60 min to obtain an aluminum plate with a porous oxide film on the surface; wherein the pore size of the porous oxide film is 20-100 nm and the thickness is 10-20 μm;

[0056] (3) sequentially placing a tungsten target material, the aluminum plate with the porous oxide film on the surface and a back plate from top to bottom and performing hot isostatic pressing treatment at a temperature of 300-400℃, a pressure of 150-220 MPa and a time of 3-6 h to obtain the tungsten target assembly.

[0057] Compared with the prior art, the present application has at least the following beneficial effects:

[0058] (1) The present application limits the intermediate layer of the tungsten target assembly to an aluminum intermediate layer with a porous oxide film on the surface. The presence of the porous oxide film increases the thickness of the tungsten and aluminum and the aluminum and the element diffusion layer in the back plate, increases the mechanical interlocking degree between the two adjacent layers, improves the bonding strength of the tungsten target assembly, and ultimately makes the welding bonding rate of the tungsten target assembly reach more than 99.98%, the welding strength reaches 200 MPa, and the flatness of the tungsten target assembly can be controlled within 0.9 mm.

[0059] (2) The present application forms a porous oxide film on the surface of the aluminum plate by anodic oxidation method, and obtains a tungsten target assembly by combining hot isostatic pressing treatment, so as to improve the welding quality of the tungsten target assembly. The preparation method provided by the present application is simple and easy to process. DETAILED DESCRIPTION

[0060] In order to facilitate the understanding of the present application, the present application is illustrated as follows. It should be understood by those skilled in the art that the examples are only to help understand the present application, and should not be regarded as a specific limitation on the present application.

[0061] Example 1

[0062] The present embodiment provides a tungsten target assembly, which comprises, from top to bottom, a tungsten target with a diameter of 300 mm and a thickness of 6 mm, an aluminum intermediate layer with a diameter of 300 mm and a thickness of 2 mm, and a copper back plate with a diameter of 400 mm and a thickness of 29 mm; both sides of the aluminum intermediate layer have a porous aluminum oxide film with a pore size of 70 nm and a thickness of 16 μm.

[0063] The present embodiment also provides a preparation method of the tungsten target assembly, which comprises the following steps:

[0064] (1) The aluminum plate is subjected to alkaline washing for 20 min using a sodium hydroxide solution with a mass fraction of 30%, then subjected to acid washing for 20 min using a nitric acid solution with a mass fraction of 30%, and then subjected to water washing for 2 min using water, to obtain a pretreated aluminum plate;

[0065] (2) The pretreated aluminum plate is used as an anode, and a lead plate is used as a cathode, and electrolytic treatment is carried out at a temperature of 18℃, a current density of 4 A / dm 2 , and a time of 50 min, and the electrolyte of the electrolytic treatment is a sulfuric acid solution with a mass fraction of 20%, to obtain an aluminum plate with a porous oxide film on the surface; wherein the porous oxide film has a pore size of 70 nm and a thickness of 16 μm;

[0066] (3) placing the tungsten target material, the aluminum plate with the porous oxide film on the surface, and the copper back plate in sequence from top to bottom, and performing hot isostatic pressing treatment at a temperature of 340°C, a pressure of 200 MPa, and a time of 5 h to obtain the tungsten target material assembly.

[0067] Example 2

[0068] The tungsten target material assembly provided in the embodiment comprises, in sequence from top to bottom, a tungsten target material with a diameter of 280 mm and a thickness of 5 mm, an aluminum intermediate layer with a diameter of 280 mm and a thickness of 2.6 mm, and an aluminum back plate with a diameter of 380 mm and a thickness of 28 mm; and both sides of the aluminum intermediate layer have a porous aluminum oxide film with a pore size of 20 nm and a thickness of 10 μm.

[0069] The embodiment also provides a preparation method of the tungsten target material assembly, and the preparation method comprises the following steps:

[0070] (1) performing alkaline washing on the aluminum plate by using a sodium hydroxide solution with a mass fraction of 20% for 20 min, then performing acid washing on the aluminum plate by using a nitric acid solution with a mass fraction of 40% for 15 min, and then performing water washing on the aluminum plate by using water for 1.5 min to obtain a pretreated aluminum plate;

[0071] (2) performing electrolytic treatment on the pretreated aluminum plate by using a lead plate as a cathode at a temperature of 15°C, a current density of 5 A / dm 2 , and a time of 30 min, wherein an electrolyte of the electrolytic treatment is a sulfuric acid solution with a mass fraction of 30% to obtain the aluminum plate with the porous oxide film on the surface; and the porous oxide film has a pore size of 20 nm and a thickness of 10 μm;

[0072] (3) placing the tungsten target material, the aluminum plate with the porous oxide film on the surface, and the aluminum back plate in sequence from top to bottom, and performing hot isostatic pressing treatment at a temperature of 300°C, a pressure of 150 MPa, and a time of 6 h to obtain the tungsten target material assembly.

[0073] Example 3

[0074] The tungsten target material assembly provided in the embodiment comprises, in sequence from top to bottom, a tungsten target material with a diameter of 270 mm and a thickness of 4 mm, an aluminum intermediate layer with a diameter of 270 mm and a thickness of 2 mm, and a stainless steel back plate with a diameter of 350 mm and a thickness of 25 mm; and both sides of the aluminum intermediate layer have a porous aluminum oxide film with a pore size of 100 nm and a thickness of 20 μm.

[0075] The embodiment also provides a preparation method of the tungsten target material assembly, and the preparation method comprises the following steps:

[0076] (1) Use a sodium citrate solution with a mass fraction of 40% to wash the aluminum plate with alkaline solution for 15 min, then use a hydrochloric acid solution with a mass fraction of 20% to wash the aluminum plate with acid for 20 min, and then use water to wash the aluminum plate for 1 min to obtain the pretreated aluminum plate.

[0077] (2) Using the pretreated aluminum plate as the anode and the lead plate as the cathode, an experiment was conducted at a temperature of 20℃ and a current density of 2A / dm². 2 An electrolytic treatment lasting 60 minutes is performed, wherein the electrolyte is a 10% sulfuric acid solution, resulting in an aluminum plate with a porous oxide film on its surface; wherein the porous oxide film has a pore size of 100 nm and a thickness of 20 μm.

[0078] (3) Place the tungsten target material, the aluminum plate with a porous oxide film on the surface and the stainless steel back plate in order from top to bottom, and perform hot isostatic pressing treatment at a temperature of 400℃, a pressure of 220MPa and a time of 3h to obtain the tungsten target material assembly.

[0079] Example 4

[0080] This embodiment provides a tungsten target assembly, which differs from Embodiment 1 only in that the pore size of the porous alumina film on the surface of the aluminum intermediate layer is adjusted from 70nm to 10nm, that is, the electrolytic treatment time in step (2) of the preparation method is adjusted from 50min to 15min. All other aspects are the same as in Embodiment 1.

[0081] Example 5

[0082] This embodiment provides a tungsten target assembly, which differs from Embodiment 1 only in that the pore size of the porous alumina film on the surface of the aluminum intermediate layer is adjusted from 70nm to 150nm, that is, the electrolytic treatment time in step (2) of the preparation method is adjusted from 50min to 120min. All other aspects are the same as in Embodiment 1.

[0083] Example 6

[0084] This embodiment provides a tungsten target assembly, which differs from Embodiment 1 only in that the thickness of the porous alumina film on the surface of the aluminum intermediate layer is adjusted from 16 μm to 5 μm, that is, the current density of the electrolytic treatment in step (2) of the preparation method is changed from 4 A / dm. 2 Adjusted to 0.5A / dm 2 Except for the above, everything else is the same as in Example 1.

[0085] Example 7

[0086] This embodiment provides a tungsten target assembly, which differs from Embodiment 1 only in that the thickness of the porous alumina film on the surface of the aluminum intermediate layer is adjusted from 16 μm to 30 μm, that is, the current density of the electrolytic treatment in step (2) of the preparation method is changed from 4 A / dm. 2 Adjusted to 8A / dm 2 Except for the above, everything else is the same as in Example 1.

[0087] Example 8

[0088] This embodiment provides a tungsten target assembly, which differs from Embodiment 1 only in that the temperature of the electrolytic treatment in step (2) is adjusted from 18°C ​​to 30°C, while the rest is the same as Embodiment 1.

[0089] Example 9

[0090] This embodiment provides a tungsten target assembly, which differs from Embodiment 1 only in that the temperature of the hot isostatic pressing process in step (3) is adjusted from 340°C to 200°C. All other aspects are the same as in Embodiment 1.

[0091] Example 10

[0092] This embodiment provides a tungsten target assembly, which differs from Embodiment 1 only in that the temperature of the hot isostatic pressing process in step (3) is adjusted from 340°C to 500°C. All other aspects are the same as in Embodiment 1.

[0093] Comparative Example 1

[0094] This comparative example provides a tungsten target assembly, which differs from Example 1 only in that the surface of the aluminum intermediate layer does not have a porous oxide film, i.e., the preparation method does not include step (2), and step (3) is adjusted to place the tungsten target, the pretreated aluminum plate and the copper back plate from top to bottom and perform hot isostatic pressing. Otherwise, it is the same as Example 1.

[0095] The welding bonding rate of the tungsten target components in Examples 1-10 and Comparative Example 1 was tested using an ultrasonic flaw detector, and the welding strength was tested using a tensile tester. At the same time, the flatness of the tungsten target components was tested using a horizontal cross and feeler gauge. The results are shown in Table 1.

[0096] Table 1

[0097]

[0098] The test results show that:

[0099] (1) As can be seen from Examples 1 to 3, the present invention forms a porous oxide film on the aluminum intermediate layer by anodizing. The presence of the porous oxide film increases the thickness of the element diffusion layer between tungsten and aluminum and between aluminum and the back plate, increases the degree of mechanical interlocking between adjacent layers, and improves the bonding strength of the tungsten target assembly. Ultimately, the welding bonding rate of the tungsten target assembly can reach more than 99.98%, the welding strength can reach 200MPa, and the flatness of the tungsten target assembly can be controlled within 0.9mm.

[0100] (2) As can be seen from Examples 1 and 4-5, in Example 1, the porous alumina film on the surface of the aluminum interlayer has a pore size of 70 nm, and the welding bonding rate of its tungsten target assembly is 100%, the welding strength is 228 MPa, and the flatness is 0.8 mm; while in Example 4, the porous alumina film on the surface of the aluminum interlayer has a pore size of 10 nm, and the welding bonding rate of its tungsten target assembly is 99.7%, the welding strength is 175 MPa, and the flatness is 1.1 mm; in Example 5, the porous alumina film on the surface of the aluminum interlayer has a pore size of 150 nm, and the welding bonding rate of its tungsten target assembly is 99.6%, the welding strength is 170 MPa, and the flatness is 1.15 mm. It can be seen that the present invention limits the pore size of the porous oxide film on the surface of the aluminum interlayer. The presence of uniformly dispersed nanopores on the surface of the aluminum interlayer can effectively alleviate the stress and strain concentration around the pores, reduce the thermal stress concentration at the welding interface caused by the large difference in thermal expansion coefficients between tungsten and the backing plate during the welding process, and effectively improve the problem of deformation of the tungsten target assembly after welding.

[0101] (3) As can be seen from Examples 1 and 6-7, in Example 1, the thickness of the porous alumina film on the surface of the aluminum intermediate layer is 16 μm, and the welding bonding rate of the tungsten target assembly is 100%, the welding strength is 228 MPa, and the flatness is 0.8 mm; while in Example 6, the thickness of the porous alumina film on the surface of the aluminum intermediate layer is 5 μm, and the welding bonding rate of the tungsten target assembly is 99.7%, the welding strength is 155 MPa, and the flatness is 1.3 mm; in Example 7, the thickness of the porous alumina film on the surface of the aluminum intermediate layer is 30 μm, and the welding bonding rate of the tungsten target assembly is 99.5%, the welding strength is 150 MPa, and the flatness is 1.2 mm. It can be seen that by limiting the thickness of the porous oxide film on the surface of the aluminum intermediate layer, the present invention can effectively promote the element diffusion between tungsten and aluminum, and between aluminum and the back plate, to form an element diffusion layer, improve the welding strength of the tungsten target assembly, increase the welding bonding rate, and reduce the flatness of the tungsten target assembly after welding.

[0102] (4) As can be seen from Examples 1 and 8, in Example 1, the electrolytic treatment temperature in step (2) is 18°C, and the welding bonding rate of the tungsten target assembly prepared there is 100%, the welding strength is 228MPa, and the flatness is 0.8mm; while in Example 8, the electrolytic treatment temperature in step (2) is 30°C, and the welding bonding rate of the tungsten target assembly prepared there is 98%, the welding strength is 80MPa, and the flatness is 1.8mm. It can be seen that by limiting the temperature of the electrolytic treatment, the present invention improves the welding bonding rate and welding strength of the tungsten target assembly and reduces the flatness of the tungsten target assembly after welding. If the temperature of the electrolytic treatment is too high, the welding bonding rate and welding strength of the tungsten target assembly will decrease, and the flatness of the tungsten target assembly after welding will increase.

[0103] (5) As can be seen from Examples 1 and 9-10, the temperature of hot isostatic pressing in step (3) of Example 1 is 340°C, and the welding bonding rate of the tungsten target assembly prepared there is 100%, the welding strength is 228MPa, and the flatness is 0.8mm; while the temperature of hot isostatic pressing in step (3) of Example 9 is 200°C, and the welding bonding rate of the tungsten target assembly prepared there is 97%, the welding strength is 60MPa, and the flatness is 1.9mm; the temperature of hot isostatic pressing in step (3) of Example 10 is 500°C, and the welding bonding rate of the tungsten target assembly prepared there is 98.5%, the welding strength is 90MPa, and the flatness is 1.7mm. It can be seen that the present invention can achieve the welding of tungsten target assembly at 300~400°C, which is lower than the hot isostatic pressing welding temperature of tungsten target assembly in the prior art. Moreover, by limiting the temperature of hot isostatic pressing, the welding bonding rate and welding strength of tungsten target assembly can be improved, and the flatness of the tungsten target assembly after welding can be reduced.

[0104] (6) As can be seen from Example 1 and Comparative Example 1, the present invention limits the intermediate layer of the tungsten target assembly to an aluminum intermediate layer with a porous oxide film on the surface. The presence of the porous oxide film increases the thickness of the element diffusion layer between tungsten and aluminum and between aluminum and the back plate, and increases the degree of mechanical interlocking between adjacent layers, so as to effectively improve the welding bonding rate and welding strength of the tungsten target and reduce the flatness of the tungsten target assembly after welding.

[0105] In summary, by limiting the intermediate layer of the tungsten target assembly to an aluminum intermediate layer with a porous oxide film on its surface, the present invention increases the bonding strength of the tungsten target assembly, so that the welding bonding rate of the tungsten target assembly can reach more than 99.98%, the welding strength can reach 200MPa, and the flatness of the tungsten target assembly can be controlled within 0.9mm.

[0106] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A tungsten target assembly, comprising: The tungsten target assembly comprises, from top to bottom, a tungsten target, an aluminum intermediate layer, and a back plate. The surface of the aluminum intermediate layer has a porous oxide film.

2. The tungsten target assembly of claim 1, wherein, Both sides of the aluminum intermediate layer have a porous oxide film. Preferably, the porous oxide film comprises an aluminum oxide film. Preferably, the pore size of the porous oxide film is 20-100 nm. Preferably, the thickness of the porous oxide film is 10-20 µm.

3. The tungsten target assembly of claim 1 or 2, wherein, The diameter of the tungsten target is 200-300 mm. Preferably, the thickness of the tungsten target is 4-6 mm. Preferably, the diameter of the aluminum intermediate layer is 200-300 mm. Preferably, the thickness of the aluminum intermediate layer is 2-3 mm. Preferably, the diameter of the back plate is 300-400 mm. Preferably, the thickness of the back plate is 25-30 mm. Preferably, the material of the back plate comprises any one of copper, aluminum, or stainless steel.

4. A method of producing a tungsten target assembly according to any one of claims 1 to 3, characterized in that, The preparation method comprises the following steps: (1) electrolytic treatment of an aluminum plate as an anode and a lead plate as a cathode to obtain an aluminum plate with a porous oxide film on the surface; (2) placing, from top to bottom, a tungsten target, the aluminum plate with a porous oxide film on the surface, and a back plate, and then performing hot isostatic pressing to obtain the tungsten target assembly.

5. The preparation method according to claim 4, characterized in that, The temperature of the electrolytic treatment is 15-20 °C. Preferably, the current density of the electrolytic treatment is between 2 and 5 A / dm 2 ; Preferably, the electrolytic treatment is performed for 30-60 min. Preferably, the electrolyte used in the electrolytic treatment comprises any one or a combination of at least two of sulfuric acid solution, oxalic acid solution, or chromic acid solution. Preferably, the mass fraction of the electrolyte is 10-30%.

6. The production method according to claim 4 or 5, characterized by, The pore size of the porous oxide film on the surface of the aluminum plate is 20-100 nm. Preferably, the thickness of the porous oxide film on the surface of the aluminum plate is 10-20 µm.

7. The method of any one of claims 4-6, wherein, The temperature of the hot isostatic pressing is 300-400 °C. Preferably, the pressure of the hot isostatic pressing is 150-220 MPa. Preferably, the hot isostatic pressing is performed for 3-6 h.

8. The method of any one of claims 4-7, wherein, The preparation method further comprises pretreating the aluminum plate before the electrolytic treatment. Preferably, the pretreatment comprises sequentially performing alkaline cleaning, acid cleaning, and water cleaning. Preferably, the alkaline solution used in the alkaline cleaning comprises sodium hydroxide solution and / or sodium citrate solution. Preferably, the mass fraction of the alkaline solution is 20-40%. Preferably, the alkaline cleaning is performed for 15-20 min.

9. The preparation method according to claim 8, characterized in that, The acid solution used in the acid cleaning comprises nitric acid solution and / or hydrochloric acid solution. Preferably, the mass fraction of the acid solution is 20-40%. Preferably, the acid cleaning is performed for 15-20 min. Preferably, the water cleaning is performed for 1-2 min.

10. The method of any one of claims 4-9, wherein, The preparation method comprises the following steps: (1) sequentially performing alkaline cleaning, acid cleaning, and water cleaning on an aluminum plate to obtain a pretreated aluminum plate; (2) electrolytic treatment is carried out at a temperature of 15-20℃, a current density of 2-5 A / dm 2 , and a time of 30-60 min, using the pretreated aluminum plate as an anode and a lead plate as a cathode, to obtain an aluminum plate with a porous oxide film on the surface; wherein the pore diameter of the porous oxide film is 20-100 nm, and the thickness is 10-20 μm; (3) placing, from top to bottom, a tungsten target, the aluminum plate with a porous oxide film on the surface, and a back plate, and then performing hot isostatic pressing at a temperature of 300-400 °C, a pressure of 150-220 MPa, and for a time of 3-6 h to obtain the tungsten target assembly.

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