Diffusion welding method of ultra-high purity copper target

Abstract

The present invention provides a diffusion welding method for an ultra-high purity copper target, the diffusion welding method comprising the following steps: (1) turning threads on the welding surface of the ultra-high purity copper target, washing with isopropyl alcohol, washing with water and washing with alcohol in sequence to obtain a pretreated target; (2) assembling the pretreated target and an aluminum alloy back plate, and then performing diffusion welding; the pitch of the thread in step (1) is 0.7-0.75 mm, and the thread depth is 0.6-0.65 mm. The diffusion welding method provided by the present invention processes threads on the welding surface of the ultra-high purity copper target, reducing tool loss in turning; and, through the specific setting of the threads, the temperature of diffusion welding can be reduced, and the welding quality can be guaranteed, so that the target assembly after diffusion welding meets the coating requirements.

Description

Technical Field

[0001] The invention belongs to the technical field of semiconductors and relates to a welding method for a target material, in particular to a diffusion welding method for an ultra-high purity copper target material. Background Art

[0002] With the rapid development of VLSI, the size of semiconductor chips has been reduced to the nanometer level. The RC delay and electromigration of metal interconnects have become the main factors affecting chip performance. Traditional aluminum and aluminum alloy interconnects can no longer meet the requirements of VLSI process. Compared with aluminum, copper has higher electromigration resistance and higher conductivity, especially ultra-high purity copper (purity ≥ 6N), which is of great significance for reducing the resistance of chip interconnects and improving their computing speed.

[0003] In actual application, it is necessary to combine a metal construction target material that meets the performance requirements with a back plate with a certain strength to form a target assembly, and then install it on the sputtering machine to effectively control the sputtering under the action of magnetic and electric fields. Due to its low hardness, the copper target material needs to be welded to a high-hardness aluminum back plate. However, if the welding temperature is high, it is easy to cause abnormal grain growth in the copper target material, resulting in coarse grain defects, which in turn affects the performance of the formed semiconductor chip.

[0004] CN110539067A discloses a diffusion welding method for a high-purity copper target, comprising the following steps: preparing a high-purity copper target and a back plate, and processing threads on the welding surface of the back plate; evenly arranging metal powder on the threaded surface of the back plate; placing the high-purity copper target and the back plate into a metal sheath after combining them, and then degassing the metal sheath, and then sealing the degassing metal sheath; hot isostatic pressing the sealed metal sheath, and then cooling it to room temperature; removing the metal sheath to complete the diffusion welding of the high-purity copper target and the back plate.

[0005] CN111304604A discloses a diffusion welding method for a copper target and an aluminum alloy back plate and a copper target assembly obtained. The diffusion welding method comprises the following steps: (1) coating a titanium film on the welding surface of the copper target, and then assembling the copper target coated with the titanium film and the aluminum alloy back plate, and then placing the whole into a sheath; (2) sealing the sheath obtained in step (1) and degassing it; (3) hot isostatic pressing the sheath after degassing in step (2), and then removing the sheath to complete the diffusion welding of the copper target and the aluminum alloy back plate. The provision of the titanium film improves the bonding degree of the welding.

[0006] CN113894401A discloses a method for low-temperature diffusion welding of an ultra-high purity copper target assembly, the method comprising the following steps: pre-treating the welding surface of the ultra-high purity copper target; threading the welding surface of the copper alloy back plate; the pitch of the thread is 0.2-0.45mm, and the depth of the thread is 0.1-0.15mm; assembling the treated ultra-high purity copper target and the copper alloy back plate, and then placing them in a bag after vacuum packaging for degassing; diffusion welding is performed after degassing, and then cooling is performed to obtain an ultra-high purity copper target assembly.

[0007] The above method turns threads on the welding surface of the back plate with higher hardness, and involves the control of thread size. However, when processing the back plate with higher hardness, the service life of the turning tool is short. If a method for setting threads on the welding surface of the target material can be provided, it will be helpful to reduce the cost of turning processing; therefore, it is necessary to provide a diffusion welding method for ultra-high purity copper target material that is helpful to reduce processing costs and ensure welding strength. Summary of the invention

[0008] The object of the present invention is to provide a diffusion welding method for an ultra-high purity copper target material, wherein the diffusion welding method processes threads on the welding surface of the ultra-high purity copper target material, thereby reducing tool loss during turning processing; moreover, through the specific setting of the threads, the temperature of the diffusion welding can be reduced, and the welding quality can be guaranteed, so that the target material assembly after diffusion welding meets the coating requirements.

[0009] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0010] In a first aspect, the present invention provides a diffusion welding method for an ultra-high purity copper target, the diffusion welding method comprising the following steps:

[0011] (1) turning threads on the welding surface of the ultra-high purity copper target, and washing with isopropanol, water and alcohol in sequence to obtain a pretreated target;

[0012] (2) assembling the pretreated target material and the aluminum alloy backing plate, and then performing diffusion welding;

[0013] The thread pitch of step (1) is 0.7-0.75 mm, and the thread depth is 0.6-0.65 mm.

[0014] The aluminum alloy back plate of the present invention is a 5 series aluminum alloy back plate, and the aluminum alloy includes but is not limited to A5083 or A5052.

[0015] The diffusion welding method provided by the present invention processes threads on the welding surface of an ultra-high purity copper target material, thereby reducing tool loss during turning processing; moreover, through the specific setting of the threads, the temperature of diffusion welding can be reduced, and the welding quality can be guaranteed, so that the target material assembly after diffusion welding meets the coating requirements.

[0016] In the diffusion welding method of the present invention, the pitch of the thread is 0.7-0.75 mm, for example, it can be 0.7 mm, 0.71 mm, 0.72 mm, 0.73 mm, 0.74 mm or 0.75 mm, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0017] In the diffusion welding method of the present invention, the thread depth is 0.6-0.65 mm, for example, it can be 0.6 mm, 0.61 mm, 0.62 mm, 0.63 mm, 0.64 mm or 0.65 mm, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0018] As one of the preferred technical solutions of the present invention, the thread angle of the thread is 55°-65°, for example, it can be 55°, 56°, 58°, 60°, 62°, 64° or 65°, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0019] As a second preferred technical solution of the present invention, on the basis that the thread angle of the thread is 55°-65°, the shape of the thread is improved; the thread of the thread includes a first boss and a first convex tooth;

[0020] The central axis of the first boss coincides with the central axis of the first protruding tooth.

[0021] The sum of the height of the first boss and the height of the first protruding tooth=the thread depth.

[0022] The diffusion welding method provided by the present invention is to turn threads on the welding surface of an ultra-high purity copper target material with relatively low hardness. In order to avoid a reduction in welding strength caused by excessive deformation of the thread during diffusion welding, the present invention improves the shape of the thread on the basis of a thread angle of 55°-65°.

[0023] The present invention makes the shape of the screw thread into a first boss and a first convex tooth. During diffusion welding, the first convex tooth first contacts the aluminum alloy back plate to achieve a preliminary invasion effect. Moreover, since the cross-sectional area of ​​the first convex tooth is small, the adverse effect of screw thread deformation on welding strength is alleviated.

[0024] Preferably, the cross-sectional shape of the first protruding tooth is triangular.

[0025] Preferably, the height of the first protruding tooth is 0.05-0.08 mm, and the bottom width is 0.12-0.18 mm.

[0026] In the present invention, the height of the first protruding teeth is 0.05-0.08 mm, for example, 0.05 mm, 0.06 mm, 0.07 mm or 0.08 mm, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0027] In the present invention, the bottom edge width of the first protruding tooth is 0.12-0.18 mm, for example, it can be 0.12 mm, 0.13 mm, 0.14 mm, 0.15 mm, 0.16 mm, 0.17 mm or 0.18 mm, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0028] As a third preferred technical solution of the present invention, the thread of the thread includes a second boss and a second convex tooth;

[0029] The central axis of the second boss coincides with the central axis of the second protruding tooth;

[0030] The sum of the height of the second boss and the height of the second convex tooth is greater than the thread depth.

[0031] The "sum of the height of the second boss and the height of the second tooth > thread depth" stated in the present invention means that there is an inverted triangular groove between the edge of the second tooth and the edge of the second boss. By setting the inverted triangular groove, the adverse effect of screw thread deformation on welding strength during diffusion welding is further alleviated.

[0032] Preferably, the second protruding tooth is in a triangular shape;

[0033] Preferably, the second protruding teeth have a height of 0.08-0.12 mm and a bottom width of 0.16-0.24 mm.

[0034] In the present invention, the height of the second protruding teeth is 0.08-0.12 mm, for example, 0.08 mm, 0.09 mm, 0.1 mm, 0.11 mm or 0.12 mm, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0035] In the present invention, the bottom edge width of the second protruding tooth is 0.16-0.24 mm, for example, it can be 0.16 mm, 0.18 mm, 0.2 mm, 0.21 mm, 0.22 mm or 0.24 mm, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0036] Preferably, the height of the second boss is 0.52-0.6 mm, for example, 0.52 mm, 0.54 mm, 0.55 mm, 0.56 mm, 0.58 mm or 0.6 mm, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0037] Preferably, the isopropanol washing time is 20-30 min, for example, it can be 20, 22, 24, 25, 27, 28 or 30, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0038] The present invention achieves the effect of degreasing by washing with isopropanol. As a further preferred technical solution, the isopropanol is: the target material after thread turning is immersed in an isopropanol tank for ultrasonic cleaning.

[0039] Preferably, the water washing time is 4-6 min, for example, 4 min, 4.5 min, 5 min, 5.5 min or 6 min, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0040] Preferably, the alcohol washing is performed using ethanol for 1.5-2.5 min, for example, 1.5 min, 1.6 min, 1.8 min, 2 min, 2.1 min, 2.4 min or 2.5 min, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0041] The diffusion welding method of the present invention further includes drying after alcohol washing. As long as the drying effect can be achieved, the present invention does not further limit the specific parameters of drying, as long as the drying effect can be achieved.

[0042] Preferably, the diffusion welding in step (2) includes heating, heat preservation, pressurization and pressure preservation in sequence.

[0043] Preferably, the terminal temperature of the heating is 200-250°C, for example, it can be 200°C, 210°C, 220°C, 230°C, 240°C or 250°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0044] Preferably, the insulation time is 10-15 min, for example, 10 min, 11 min, 12 min, 13 min, 14 min or 15 min, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0045] Preferably, the pressurized pressure is 3000-3500t, for example, 3000t, 3100t, 3200t, 3300t, 3400t or 3500t, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0046] The pressurization described in the present invention is carried out in a ton press.

[0047] Preferably, the pressure holding time is 4-6 minutes, for example, 4 minutes, 4.5 minutes, 5 minutes, 5.5 minutes or 6 minutes, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0048] As a preferred technical solution of the diffusion welding method of the present invention, the diffusion welding method comprises the following steps:

[0049] (1) turning threads on the welding surface of the ultra-high purity copper target, washing with isopropanol, water and ethanol in sequence to obtain a pretreated target; the isopropanol washing time is 20-30 minutes; the water washing time is 4-6 minutes; and the ethanol washing time is 1.5-2.5 minutes;

[0050] (2) assembling the pretreated target material and the aluminum alloy back plate, and then performing diffusion welding; the diffusion welding includes heating, heat preservation, pressurization and pressure holding in sequence; the end temperature of the heating is 200-250° C.; the heat preservation time is 10-15 minutes; the pressurization pressure is 3000-3500t; and the pressure holding time is 4-6 minutes;

[0051] The thread pitch of step (1) is 0.7-0.75 mm, and the thread depth is 0.6-0.65 mm.

[0052] Compared with the prior art, the present invention has the following beneficial effects:

[0053] (1) The diffusion welding method provided by the present invention processes threads on the welding surface of the ultra-high purity copper target material, thereby reducing tool loss during turning processing; moreover, through the specific setting of the threads, the temperature of diffusion welding can be reduced, and the welding quality can be guaranteed, so that the target material assembly after diffusion welding meets the coating requirements;

[0054] (2) In the target material assembly obtained by the diffusion welding method provided by the present invention, the grain size of the ultra-high purity copper target material is 15-20 μm, and the welding strength is ≥35 MPa, which meets the coating requirements of semiconductor integrated circuit chips. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Figure 1 Schematic diagram of the structure of the thread in Example 1, where W represents the pitch and H represents the thread depth;

[0056] Figure 2 Schematic diagram of the structure of the thread in Example 4, wherein W represents the pitch, H represents the thread depth, w1 represents the bottom width of the first convex tooth, and h1 represents the height of the first convex tooth;

[0057] Figure 3Schematic diagram of the structure of the thread in Example 7, wherein W represents the pitch, H represents the thread depth, w2 represents the bottom width of the second protruding tooth, h2 represents the height of the second protruding tooth, and h3 represents the height of the second boss. DETAILED DESCRIPTION

[0058] 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.

[0059] In order to illustrate the technical solution of the present invention, the material of the aluminum alloy back plate in the specific implementation manner is A5083. This limitation is only for better illustrating the technical solution and should not be regarded as a further limitation of the technical solution of the present invention.

[0060] Example 1

[0061] This embodiment provides a diffusion welding method for an ultra-high purity copper target material, and the diffusion welding method comprises the following steps:

[0062] (1) turning threads on the welding surface of an ultra-high purity copper target, and washing with isopropanol, water and ethanol in sequence to obtain a pretreated target; the isopropanol washing time is 25 minutes; the water washing time is 5 minutes; and the ethanol washing time is 2 minutes;

[0063] (2) assembling the pretreated target material and the aluminum alloy back plate, and then performing diffusion welding to obtain a target material assembly; the diffusion welding includes heating, heat preservation, pressurization and pressure preservation in sequence; the end temperature of the heating is 220° C.; the heat preservation time is 12 minutes; the pressurization is performed in a ton press, the pressurization pressure is 3200 tons; the pressure preservation time is 5 minutes;

[0064] The structural diagram of the thread in step (1) is as follows Figure 1 As shown, the thread pitch W is 0.72 mm, the thread depth H is 0.62 mm; the thread tooth shape is triangular, and the thread angle is 60°.

[0065] Example 2

[0066] This embodiment provides a diffusion welding method for an ultra-high purity copper target material, and the diffusion welding method comprises the following steps:

[0067] (1) turning threads on the welding surface of an ultra-high purity copper target, and washing with isopropanol, water and ethanol in sequence to obtain a pretreated target; the isopropanol washing time is 20 minutes; the water washing time is 4 minutes; and the ethanol washing time is 1.5 minutes;

[0068] (2) assembling the pretreated target material and the aluminum alloy back plate, and then performing diffusion welding to obtain a target material assembly; the diffusion welding includes heating, heat preservation, pressurization and pressure preservation in sequence; the end temperature of the heating is 200° C.; the heat preservation time is 15 minutes; the pressurization is performed in a ton press, the pressurization pressure is 3000 tons; the pressure preservation time is 6 minutes;

[0069] The thread pitch W of step (1) is 0.7 mm, and the thread depth H is 0.6 mm; the thread tooth shape is triangular, and the thread angle is 60°.

[0070] Example 3

[0071] This embodiment provides a diffusion welding method for an ultra-high purity copper target material, and the diffusion welding method comprises the following steps:

[0072] (1) turning threads on the welding surface of the ultra-high purity copper target, and washing with isopropanol, water and ethanol in sequence to obtain a pretreated target; the isopropanol washing time is 30 minutes; the water washing time is 6 minutes; and the ethanol washing time is 2.5 minutes;

[0073] (2) assembling the pretreated target material and the aluminum alloy back plate, and then performing diffusion welding to obtain a target material assembly; the diffusion welding includes heating, heat preservation, pressurization and pressure preservation in sequence; the end temperature of the heating is 250° C.; the heat preservation time is 10 minutes; the pressurization is performed in a ton press, the pressurization pressure is 3500 tons; the pressure preservation time is 4 minutes;

[0074] The thread pitch W of step (1) is 0.75 mm, and the thread depth H is 0.65 mm; the thread tooth shape is triangular, and the thread angle is 60°.

[0075] Example 4

[0076] This embodiment provides a diffusion welding method for an ultra-high purity copper target material, and the diffusion welding method comprises the following steps:

[0077] (1) turning threads on the welding surface of an ultra-high purity copper target, and washing with isopropanol, water and ethanol in sequence to obtain a pretreated target; the isopropanol washing time is 25 minutes; the water washing time is 5 minutes; and the ethanol washing time is 2 minutes;

[0078] (2) assembling the pretreated target material and the aluminum alloy back plate, and then performing diffusion welding to obtain a target material assembly; the diffusion welding includes heating, heat preservation, pressurization and pressure preservation in sequence; the end temperature of the heating is 220° C.; the heat preservation time is 12 minutes; the pressurization is performed in a ton press, the pressurization pressure is 3200 tons; the pressure preservation time is 5 minutes;

[0079] The structural diagram of the thread in step (1) is as follows Figure 2 As shown, the pitch W of the thread is 0.72mm, and the thread depth H is 0.62mm; the thread angle of the thread is 60°; the thread teeth of the thread include a first boss and a first convex tooth, the central axis of the first boss coincides with the central axis of the first convex tooth, and the sum of the height of the first boss and the height of the first convex tooth = the thread depth H; the height h1 of the first convex tooth is 0.06mm, and the bottom edge width w1 is 0.15mm.

[0080] Example 5

[0081] This embodiment provides a diffusion welding method for an ultra-high purity copper target material, and the diffusion welding method comprises the following steps:

[0082] (1) turning threads on the welding surface of an ultra-high purity copper target, and washing with isopropanol, water and ethanol in sequence to obtain a pretreated target; the isopropanol washing time is 25 minutes; the water washing time is 5 minutes; and the ethanol washing time is 2 minutes;

[0083] (2) assembling the pretreated target material and the aluminum alloy back plate, and then performing diffusion welding to obtain a target material assembly; the diffusion welding includes heating, heat preservation, pressurization and pressure preservation in sequence; the end temperature of the heating is 220° C.; the heat preservation time is 12 minutes; the pressurization is performed in a ton press, the pressurization pressure is 3200 tons; the pressure preservation time is 5 minutes;

[0084] The pitch W of the thread in step (1) is 0.72 mm, and the thread depth H is 0.62 mm; the thread angle of the thread is 60°; the thread teeth of the thread include a first boss and a first convex tooth, the central axis of the first boss coincides with the central axis of the first convex tooth, and the sum of the height of the first boss and the height of the first convex tooth = the thread depth H; the height h1 of the first convex tooth is 0.05 mm, and the bottom edge width w1 is 0.12 mm.

[0085] Example 6

[0086] This embodiment provides a diffusion welding method for an ultra-high purity copper target material, and the diffusion welding method comprises the following steps:

[0087] (1) turning threads on the welding surface of an ultra-high purity copper target, and washing with isopropanol, water and ethanol in sequence to obtain a pretreated target; the isopropanol washing time is 25 minutes; the water washing time is 5 minutes; and the ethanol washing time is 2 minutes;

[0088] (2) assembling the pretreated target material and the aluminum alloy back plate, and then performing diffusion welding to obtain a target material assembly; the diffusion welding includes heating, heat preservation, pressurization and pressure preservation in sequence; the end temperature of the heating is 220° C.; the heat preservation time is 12 minutes; the pressurization is performed in a ton press, the pressurization pressure is 3200 tons; the pressure preservation time is 5 minutes;

[0089] The pitch W of the thread in step (1) is 0.72 mm, and the thread depth H is 0.62 mm; the thread angle of the thread is 60°; the thread teeth of the thread include a first boss and a first convex tooth, the central axis of the first boss coincides with the central axis of the first convex tooth, and the sum of the height of the first boss and the height of the first convex tooth = the thread depth H; the height h1 of the first convex tooth is 0.08 mm, and the bottom edge width w1 is 0.18 mm.

[0090] Example 7

[0091] This embodiment provides a diffusion welding method for an ultra-high purity copper target material, and the diffusion welding method comprises the following steps:

[0092] (1) turning threads on the welding surface of an ultra-high purity copper target, and washing with isopropanol, water and ethanol in sequence to obtain a pretreated target; the isopropanol washing time is 25 minutes; the water washing time is 5 minutes; and the ethanol washing time is 2 minutes;

[0093] (2) assembling the pretreated target material and the aluminum alloy back plate, and then performing diffusion welding to obtain a target material assembly; the diffusion welding includes heating, heat preservation, pressurization and pressure preservation in sequence; the end temperature of the heating is 220° C.; the heat preservation time is 12 minutes; the pressurization is performed in a ton press, the pressurization pressure is 3200 tons; the pressure preservation time is 5 minutes;

[0094] The structural diagram of the thread in step (1) is as follows Figure 3 As shown, the pitch W of the thread is 0.72mm, and the thread depth H is 0.62mm; the thread angle of the thread is 60°; the thread teeth of the thread include a second boss and a second convex tooth, the central axis of the second boss coincides with the central axis of the second convex tooth, and the sum of the height of the second boss and the height of the second convex tooth is greater than the thread depth H; the height h2 of the second convex tooth is 0.1mm, and the bottom edge width w2 is 0.2mm; the height h3 of the second boss is 0.55mm.

[0095] Example 8

[0096] This embodiment provides a diffusion welding method for an ultra-high purity copper target material, and the diffusion welding method comprises the following steps:

[0097] (1) turning threads on the welding surface of an ultra-high purity copper target, and washing with isopropanol, water and ethanol in sequence to obtain a pretreated target; the isopropanol washing time is 25 minutes; the water washing time is 5 minutes; and the ethanol washing time is 2 minutes;

[0098] (2) assembling the pretreated target material and the aluminum alloy back plate, and then performing diffusion welding to obtain a target material assembly; the diffusion welding includes heating, heat preservation, pressurization and pressure preservation in sequence; the end temperature of the heating is 220° C.; the heat preservation time is 12 minutes; the pressurization is performed in a ton press, the pressurization pressure is 3200 tons; the pressure preservation time is 5 minutes;

[0099] The pitch W of the thread in step (1) is 0.72 mm, and the thread depth H is 0.62 mm; the thread angle of the thread is 60°; the thread teeth of the thread include a second boss and a second convex tooth, the central axis of the second boss coincides with the central axis of the second convex tooth, and the sum of the height of the second boss and the height of the second convex tooth is greater than the thread depth H; the height h2 of the second convex tooth is 0.12 mm, and the bottom width w2 is 0.24 mm; the height h3 of the second boss is 0.52 mm.

[0100] Example 9

[0101] This embodiment provides a diffusion welding method for an ultra-high purity copper target material, and the diffusion welding method comprises the following steps:

[0102] (1) turning threads on the welding surface of an ultra-high purity copper target, and washing with isopropanol, water and ethanol in sequence to obtain a pretreated target; the isopropanol washing time is 25 minutes; the water washing time is 5 minutes; and the ethanol washing time is 2 minutes;

[0103] (2) assembling the pretreated target material and the aluminum alloy back plate, and then performing diffusion welding to obtain a target material assembly; the diffusion welding includes heating, heat preservation, pressurization and pressure preservation in sequence; the end temperature of the heating is 220° C.; the heat preservation time is 12 minutes; the pressurization is performed in a ton press, the pressurization pressure is 3200 tons; the pressure preservation time is 5 minutes;

[0104] The pitch W of the thread in step (1) is 0.72mm, and the thread depth H is 0.62mm; the thread angle of the thread is 60°; the thread teeth of the thread include a second boss and a second convex tooth, the central axis of the second boss coincides with the central axis of the second convex tooth, and the sum of the height of the second boss and the height of the second convex tooth is greater than the thread depth H; the height h2 of the second convex tooth is 0.08mm, and the bottom width w2 is 0.16m; the height h3 of the second boss is 0.6mm.

[0105] The grain size of the target material in the target material assembly obtained in Examples 1-9 and the welding strength between the target material and the back plate were measured. The grain size was determined according to the method specified in GB / T 6394-2017; the welding strength was measured using a tensile testing machine, and the peak strength at break was the welding strength. The grain size is the average grain size, and the test results are shown in Table 1.

[0106] Table 1

[0107] Grain size (μm) Welding strength (MPa) Example 1 17.3 38.5 Example 2 15.1 35.3 Example 3 19.8 36.2 Example 4 17.3 40.3 Example 5 17.3 38.6 Example 6 17.3 38.8 Example 7 17.3 48.9 Example 8 17.3 43.7 Example 9 17.3 45.6

[0108] In summary, the diffusion welding method provided by the present invention processes threads on the welding surface of the ultra-high purity copper target material, thereby reducing tool loss in turning processing; moreover, through the specific setting of the threads, the temperature of diffusion welding can be reduced, and the welding quality is guaranteed, so that the target material assembly after diffusion welding meets the coating requirements; in the target material assembly obtained by the diffusion welding method provided by the present invention, the grain size of the ultra-high purity copper target material is 15-20μm, and the welding strength is ≥35MPa, which meets the coating requirements of semiconductor integrated circuit chips.

[0109] The above description 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 diffusion welding method for an ultra-high purity copper target, characterized in that: The diffusion welding method comprises the following steps: (1) turning threads on the welding surface of the ultra-high purity copper target, and washing with isopropanol, water and alcohol in sequence to obtain a pretreated target; (2) assembling the pretreated target material and the aluminum alloy backing plate, and then performing diffusion welding; The thread pitch of step (1) is 0.7-0.75 mm, and the thread depth is 0.6-0.65 mm; The thread angle of the thread is 55°-65°; The thread of the thread includes a first boss and a first convex tooth; the central axis of the first boss coincides with the central axis of the first convex tooth; the cross-sectional shape of the first convex tooth is a triangle; the height of the first convex tooth is 0.05-0.08 mm, and the bottom width is 0.12-0.18 mm; Alternatively, the thread of the thread includes a second boss and a second convex tooth; the central axis of the second boss coincides with the central axis of the second convex tooth; the sum of the height of the second boss and the height of the second convex tooth>the thread depth; the shape of the second convex tooth is triangular; the height of the second convex tooth is 0.08-0.12mm, and the bottom width is 0.16-0.24mm; the height of the second boss is 0.52-0.6mm.

2. The diffusion welding method according to claim 1, characterized in that: The isopropanol washing time is 20-30 minutes.

3. The diffusion welding method according to claim 1, characterized in that: The water washing time is 4-6 minutes.

4. The diffusion welding method according to claim 1, characterized in that: The alcohol washing is performed using ethanol for 1.5-2.5 min.

5. The diffusion welding method according to claim 1, characterized in that: The diffusion welding in step (2) includes heating, heat preservation, pressurization and pressure maintenance in sequence.

6. The diffusion welding method according to claim 5, characterized in that: The terminal temperature of the heating is 200-250°C.

7. The diffusion welding method according to claim 5, characterized in that: The insulation time is 10-15 minutes.

8. The diffusion welding method according to claim 5, characterized in that: The pressurized pressure is 3000-3500t.

9. The diffusion welding method according to claim 5, characterized in that: The pressure holding time is 4-6 minutes.

10. The diffusion welding method according to claim 1, characterized in that: The diffusion welding method comprises the following steps: (1) turning threads on the welding surface of the ultra-high purity copper target, washing with isopropanol, water and ethanol in sequence to obtain a pretreated target; the isopropanol washing time is 20-30 minutes; the water washing time is 4-6 minutes; and the ethanol washing time is 1.5-2.5 minutes; (2) assembling the pretreated target material and the aluminum alloy back plate, and then performing diffusion welding; the diffusion welding includes heating, heat preservation, pressurization and pressure holding in sequence; the end temperature of the heating is 200-250° C.; the heat preservation time is 10-15 minutes; the pressurization pressure is 3000-3500t; and the pressure holding time is 4-6 minutes; The thread pitch of step (1) is 0.7-0.75 mm, and the thread depth is 0.6-0.65 mm.

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