Ultra-high purity copper target welding structure and welding method

Abstract

The present invention provides an ultra-high purity copper target welding structure and a welding method. The ultra-high purity copper target welding structure is provided with threads on the welding surface of the target back plate, and the pitch of the threads is strictly controlled to be 0.15-0.25 mm, and the depth of the threads is 0.10-0.15 mm. On the basis of the prior art, the size of the threads is improved, and the welding bonding rate is greatly improved. The thread size is matched with the angle of the thread tooth tip and the surface roughness of the welding surface, and the welding bonding rate is further improved.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor technology, in particular to the field of ultra-high purity copper target material technology, and specifically to an ultra-high purity copper target material welding structure and a welding method. 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] Ultra-high purity copper target is a commonly used wire manufacturing material for semiconductor chip manufacturing due to its excellent conductivity. On the one hand, due to its low hardness (60HV~65HV), on the other hand, due to its relatively high cost, it needs to be welded with another copper alloy backplane material with relatively high strength. The copper alloy backplane plays a supporting role on the sputtering machine on the one hand, and also has excellent thermal and electrical conductivity. Due to the low recrystallization temperature of ultra-high purity copper, the grains are extremely easy to grow under high temperature and high pressure, which will have an adverse effect on the line width and uniformity of the wafer. High pressure is a sufficient condition to ensure the quality of welding, so it is necessary to weld the ultra-high purity copper target (Blank) and the copper alloy backplane (BP) at low temperature (≤300℃) and high pressure (≥100MPa). In order to achieve excellent welding of ultra-high purity copper target and copper alloy backplane at low temperature, hot isostatic pressing diffusion welding with relatively mature technology is currently used. In order to ensure the assembly accuracy and welding strength of ultra-high purity copper and copper alloy backplane, on the one hand, aluminum alloy is selected as the sheath material; on the other hand, threads are turned on the copper alloy backplane. Since the ultra-high purity copper target (Blank) and the copper alloy back plate (BP) do not form a metallurgical bond but a mechanical connection under the above-mentioned low temperature and high pressure, the thread size is crucial to the welding quality of the ultra-high purity copper target.

[0004] CN111155059A discloses a target assembly and a method for manufacturing the same. The method improves the welding effect by providing threads on the target back plate or the target welding surface, but does not specifically improve the copper target back plate with a relatively high hardness.

[0005] CN110539067A discloses a diffusion welding method for a high-purity copper target material. The method improves the welding bonding rate between the target material and the back plate by evenly arranging metal powder on the welding surface. However, the method cannot guarantee the uniformity of the target material sputtering rate and may also cause abnormal phenomena in the subsequent target material sputtering process.

[0006] CN111001921A discloses a diffusion welding method for an ultra-high purity copper target material, wherein the thread pitch is set to 0.35-0.45 mm, the depth is set to 0.2-0.3 mm, and copper powder is added to improve the welding rate. However, the addition of the copper powder also causes the problem of uneven sputtering.

[0007] Therefore, it is necessary to solve the welding quality problem of ultra-high purity copper target (Blank) and copper alloy back plate (BP) under low temperature and high pressure to ensure that the product welding strength meets the requirements, thereby ensuring the safety and reliability of the target during the sputtering process. Summary of the invention

[0008] In view of the problems existing in the prior art, the present invention provides an ultra-high purity copper target welding structure and a welding method. The welding structure strictly controls the pitch of the thread to be 0.15-0.25 mm, and the depth of the thread to be 0.10-0.15 mm. Compared with the original thread size, not only is there no need to add copper powder, but the welding bonding effect is greatly improved, and the conductivity of the final target assembly is improved. Moreover, the thread size matches the angle of the tip of the thread tooth and the surface roughness of the welding surface, which is more conducive to the welding and matching of the target back plate and the ultra-high purity copper target, further improves the welding effect, and can ensure the welding effect of the ultra-high purity copper target under high pressure and low temperature.

[0009] To achieve this object, the present invention adopts the following technical solutions:

[0010] In a first aspect, the present invention provides an ultra-high purity copper target welding structure, which comprises an ultra-high purity copper target and a target back plate welded to the ultra-high purity copper target; the target back plate comprises a welding surface, and a thread is arranged on the welding surface; the pitch of the thread is 0.15 to 0.25 mm, and the depth of the thread is 0.10 to 0.15 mm.

[0011] The welding structure of the present invention strictly controls the pitch of the thread to be 0.15-0.25 mm and the depth of the thread to be 0.10-0.15 mm. Compared with the original thread size, not only the tooth pitch is reduced to increase the welding contact area, but also the original idea that the deeper the matching depth, the better the effect is broken through, and a shallower depth is selected, which greatly improves the welding bonding rate.

[0012] The pitch of the threads in the present invention is 0.15 to 0.25 mm, for example, it can be 0.15 mm, 0.16 mm, 0.17 mm, 0.18 mm, 0.19 mm, 0.2 mm, 0.22 mm, 0.23 mm, 0.24 mm or 0.25 mm.

[0013] The depth of the thread in the present invention is 0.10-0.15 mm, for example, it can be 0.10 mm, 0.11 mm, 0.12 mm, 0.13 mm, 0.14 mm or 0.15 mm.

[0014] Preferably, the copper purity of the ultra-high purity copper target is ≥6N, for example, it can be 99.9999wt%, 99.99991wt%, 99.99992wt%, 99.99994wt% or 99.99995wt%.

[0015] Preferably, the target material backing plate is a copper alloy backing plate.

[0016] Preferably, the copper alloy back plate includes a CuZn alloy back plate or a CuCr alloy back plate.

[0017] Preferably, the thread is a toothed thread.

[0018] Preferably, the angle of the tooth tip of the tooth profile thread is 55° or 60°.

[0019] In the present invention, the tip angle of the tooth tip is strictly controlled on the basis of the thread pitch being 0.15-0.25 mm and the thread depth being 0.10-0.15 mm, which is beneficial to the matching of the target back plate and the ultra-high purity copper, avoids the occurrence of tooth tip bending, etc., and better improves the welding bonding rate.

[0020] Preferably, the roughness of the welding surface of the target material back plate is ≤0.8 μm, for example, it may be 0.8 μm, 0.7 μm, 0.6 μm, 0.5 μm, 0.45 μm, 0.4 μm, 0.35 μm, 0.3 μm, 0.25 μm or 0.2 μm.

[0021] In the present invention, the roughness of the welding surface is controlled at the same time, so that the welding surface is more tightly combined.

[0022] In a second aspect, the present invention provides a method for welding an ultra-high purity copper target material, wherein the welding method adopts the ultra-high purity copper target material welding structure described in the first aspect for welding.

[0023] Preferably, the welding method comprises the following steps:

[0024] (1) After the welding surface of the target back plate is pretreated, the target back plate and the ultra-high purity copper target are assembled and vacuum packaged to obtain a packaged target assembly;

[0025] (2) The target material assembly described in step (1) is subjected to sheath welding and hot isostatic pressing welding in sequence to obtain a welded target material assembly.

[0026] The ultra-high purity copper target welding method provided by the present invention combines the welding structure with sheath welding and hot isostatic pressing welding, and the welded target assembly is not prone to abnormal phenomena during the sputtering process.

[0027] Preferably, the pretreatment in step (1) comprises rust removal, cleaning and drying performed in sequence.

[0028] Preferably, the rust removal comprises: using a wire brush to remove rust on the thread surface along the thread turning direction.

[0029] Preferably, the cleaning comprises ultrasonic cleaning.

[0030] Preferably, the ultrasonic cleaning time is 22 to 28 minutes, for example, it can be 22 minutes, 23 minutes, 24 minutes, 25 minutes, 26 minutes, 27 minutes or 28 minutes.

[0031] Preferably, the cleaning solution comprises isopropyl alcohol.

[0032] Preferably, the drying temperature in step (1) is 62-75°C, for example, it can be 62°C, 63°C, 64°C, 65°C, 66°C, 67°C, 68°C, 69°C, 70°C, 72°C, 74°C or 75°C, etc.

[0033] Preferably, the drying time is 65 to 85 min, for example, it may be 65 min, 67 min, 68 min, 69 min, 70 min, 72 min, 75 min, 78 min, 80 min, 82 min or 85 min.

[0034] Preferably, the drying is performed under vacuum conditions.

[0035] Preferably, the drying vacuum degree is ≤0.01 Pa, for example, it may be 0.01 Pa, 0.008 Pa, 0.007 Pa, 0.005 Pa or 0.004 Pa.

[0036] Preferably, the vacuum packaging time in step (1) is ≤5 min, for example, it can be 5 min, 4.5 min, 4.2 min, 4 min, 3.8 min or 3.5 min, etc.

[0037] The present invention strictly controls the vacuum packaging time to be ≤5 minutes, and can effectively prevent the ultra-high purity copper target material from rusting.

[0038] Preferably, the sheath welding in step (2) is performed by argon arc welding.

[0039] Preferably, the material of the sheath is aluminum alloy.

[0040] Preferably, the sheath is evacuated after welding.

[0041] Preferably, the vacuum degree of the package is ≤0.001Pa, for example, it can be 0.001Pa, 0.0008Pa or 0.0005Pa.

[0042] Preferably, the time interval between the hot isostatic pressing welding and the vacuuming of the sheath in step (2) is ≤24h, for example, it can be 24h, 23h, 22h, 20h, 15h, 12h, 10h, 5h, 3h or 2h.

[0043] The present invention controls the time interval between hot isostatic pressing welding and vacuuming of the jacket, and can better improve the welding effect.

[0044] Preferably, the temperature of the hot isostatic pressing welding is 255-272°C, for example, it can be 255°C, 256°C, 258°C, 260°C, 262°C, 265°C, 268°C, 270°C or 272°C.

[0045] Preferably, the hot isostatic pressing welding pressure is 96-105 MPa, for example, it may be 96 MPa, 98 MPa, 99 MPa, 100 MPa, 101 MPa, 102 MPa, 103 MPa, 104 MPa or 105 MPa.

[0046] Preferably, the hot isostatic pressing welding time is 3.2 to 4.5 hours, for example, it may be 3.2 hours, 3.3 hours, 3.4 hours, 3.5 hours, 3.8 hours, 4.0 hours, 4.2 hours or 4.5 hours.

[0047] As a preferred technical solution of the present invention, the method comprises the following steps:

[0048] (1) After the welding surface of the target back plate is derusted, cleaned with isopropyl alcohol and dried in sequence, the target back plate and the ultra-high purity copper target are assembled and vacuum packaged within 5 minutes to obtain a packaged target assembly;

[0049] (2) After the target assembly in step (1) is welded with a sheath by argon arc welding and the sheath is evacuated to a vacuum degree of ≤0.001Pa, hot isostatic pressing is performed within 24 hours. The hot isostatic pressing temperature is 255-272°C, the pressure is 96-105MPa, and the hot isostatic pressing time is 3.2-4.5 hours. After the hot isostatic pressing is completed, the sheath is removed to obtain a welded target assembly.

[0050] Compared with the prior art, the present invention has at least the following beneficial effects:

[0051] (1) The ultra-high purity copper target welding structure provided by the present invention reduces the thread pitch and thread depth at the same time, increases the welding area, and ultimately improves the welding effect of the target assembly. The electrical conductivity of the target assembly after welding is ≥58.9MS / m;

[0052] (2) The ultra-high purity copper target welding structure provided by the present invention optimizes the sharp angle of the toothed thread and improves the assembly effect of the ultra-high purity copper target and the target assembly;

[0053] (3) The ultra-high purity copper target welding method provided by the present invention has a comprehensive improvement in welding structure and process parameters, and can obtain a firmly welded target assembly under a low temperature and high pressure environment, effectively avoiding abnormal phenomena during the subsequent target sputtering process. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] Figure 1 It is a schematic diagram of the welding structure of the ultra-high purity copper target provided in Example 1 of the present invention.

[0055] Figure 2 It is a schematic diagram of the ultra-high purity copper target in the package in Application Example 1 of the present invention.

[0056] Figure 3 It is an ultrasonic detection diagram of the target material assembly obtained by welding application examples 1, 4 to 7 and application comparison examples 1 to 3 of the present invention.

[0057] In the figure: 1-ultra-high purity copper target; 2-target backing plate; 31-upper sheath cover plate; 32-lower sheath cover plate. DETAILED DESCRIPTION

[0058] The technical solution of the present invention is further described below with reference to the accompanying drawings and through specific implementation methods.

[0059] The present invention is further described in detail below. However, the following examples are only simplified examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention shall be subject to the claims.

[0060] 1. Examples and Comparative Examples

[0061] Example 1

[0062] This embodiment provides an ultra-high purity copper target welding structure, such as Figure 1 As shown, the welding structure includes an ultra-high purity copper target 1 and a target back plate 2 welded to the ultra-high purity copper target; the copper purity of the ultra-high purity copper target 1 is 99.9999wt%, and the target back plate 2 is a CuZn alloy back plate (Cu content 61.8wt%, Zn content 36.6wt%).

[0063] The target back plate 2 includes a welding surface, on which a toothed thread is arranged; the pitch of the thread is 0.15 mm, the depth of the thread is 0.12 mm; the angle of the thread tip is 60°, and the roughness of the welding surface of the target back plate is 0.4 μm.

[0064] Example 2

[0065] The present embodiment provides an ultra-high purity copper target welding structure, which includes an ultra-high purity copper target and a target back plate welded to the ultra-high purity copper target; the copper purity of the ultra-high purity copper target is 99.99991wt%, and the target back plate is a CuCr alloy back plate (Cu content 96.8wt%, Cr content 0.5wt%).

[0066] The target material back plate comprises a welding surface, on which a toothed thread is arranged; the pitch of the thread is 0.25 mm, the depth of the thread is 0.15 mm, the angle of the thread tooth tip is 55°, and the roughness of the welding surface of the target material back plate is 0.3 μm.

[0067] Example 3

[0068] The present embodiment provides an ultra-high purity copper target welding structure, which includes an ultra-high purity copper target and a target back plate welded to the ultra-high purity copper target; the copper purity of the ultra-high purity copper target is 99.99992wt%, and the target back plate is a CuCr alloy back plate (Cu content 97.1wt%, Cr content 0.4wt%).

[0069] The target material back plate includes a welding surface, on which a toothed thread is arranged; the pitch of the thread is 0.15 mm, the depth of the thread is 0.10 mm, the angle of the thread tooth tip is 55°, and the roughness of the welding surface of the target material back plate is 0.8 μm.

[0070] Example 4

[0071] This embodiment provides an ultra-high purity copper target welding structure, which is the same as that of Embodiment 1 except that the roughness of the welding structure is 1.0 μm.

[0072] Example 5

[0073] This embodiment provides an ultra-high purity copper target welding structure, which is the same as that of Embodiment 1 except that the angle of the thread tooth tip is 50°.

[0074] Comparative Example 1

[0075] This comparative example provides an ultra-high purity copper target welding structure, which is the same as Example 1 except that the pitch of the threads is 0.3 mm.

[0076] Comparative Example 2

[0077] This comparative example provides an ultra-high purity copper target welding structure, which is the same as Example 1 except that the depth of the thread is 0.08 mm.

[0078] Comparative Example 3

[0079] This comparative example provides an ultra-high purity copper target welding structure, which is the same as Example 1 except that the depth of the thread is 0.20 mm.

[0080] 2. Application Examples and Comparative Applications

[0081] Application Example 1

[0082] This application example provides an ultra-high purity copper target welding method, which uses the ultra-high purity copper target welding structure provided in Example 1 for welding, and specifically includes the following steps:

[0083] (1) The welding surface of the target back plate is processed with a toothed thread by diamond turning, the pitch of the toothed thread is 0.15 mm, the depth of the toothed thread is 0.12 mm; the angle of the tip of the thread is 60°, and the roughness of the welding surface of the target back plate is 0.4 μm;

[0084] (2) After the welding surface of the target back plate is derusted, cleaned with isopropyl alcohol and dried in sequence, the target back plate and the ultra-high purity copper target are assembled and vacuum packaged within 5 minutes to obtain a packaged target assembly; wherein the drying is performed at 62° C. for 85 minutes under a vacuum condition of 0.01 Pa;

[0085] (3) After the target assembly in step (2) is welded with the argon arc welding sleeve and the sleeve is evacuated to a vacuum degree of 0.001 Pa, hot isostatic pressing is immediately performed. The hot isostatic pressing temperature is 260° C., the pressure is 100 MPa, and the hot isostatic pressing time is 4 h. After the hot isostatic pressing is completed, the sleeve is removed to obtain a welded target assembly, wherein the schematic diagram of the target assembly in the sleeve is as shown in Figure 2 As shown, the ultra-high purity copper target 1 is arranged above the target backing plate 2 and placed in a sheath, an upper sheath cover plate 31 is arranged on the upper part of the sheath, and a lower sheath cover plate 32 is arranged on the lower part of the sheath.

[0086] Application Example 2

[0087] This application example provides an ultra-high purity copper target welding method, which uses the ultra-high purity copper target welding structure provided in Example 2 for welding, and specifically includes the following steps:

[0088] (1) Diamond turning is used to machine tooth-shaped threads on the welding surface of the target back plate, the pitch of the tooth-shaped threads is 0.25 mm, the depth of the tooth-shaped threads is 0.15 mm, the angle of the thread tip is 55°, and the roughness of the welding surface of the target back plate is 0.3 μm;

[0089] (2) After the welding surface of the target back plate is derusted, cleaned with isopropyl alcohol and dried in sequence, the target back plate and the ultra-high purity copper target are assembled and vacuum packaged within 5 minutes to obtain a packaged target assembly; wherein the drying is drying at 75° C. for 65 minutes under a vacuum condition of 0.008 Pa;

[0090] (3) In step (2), the target assembly is welded with a sheath by argon arc welding and the sheath is evacuated to a vacuum degree of 0.0008 Pa, and then hot isostatic pressing is performed within 2 hours. The hot isostatic pressing temperature is 255°C, the pressure is 105 MPa, and the hot isostatic pressing time is 3.5 hours. After the hot isostatic pressing is completed, the sheath is removed to obtain a welded target assembly.

[0091] Application Example 3

[0092] This application example provides an ultra-high purity copper target welding method, which uses the ultra-high purity copper target welding structure provided in Example 3 for welding, and specifically includes the following steps:

[0093] (1) Diamond turning is used to machine tooth-shaped threads on the welding surface of the target back plate, the pitch of the tooth-shaped threads is 0.15 mm, the depth of the tooth-shaped threads is 0.10 mm, the angle of the thread tip is 55°, and the roughness of the welding surface of the target back plate is 0.8 μm;

[0094] (2) After the welding surface of the target back plate is derusted, cleaned with isopropyl alcohol and dried in sequence, the target back plate and the ultra-high purity copper target are assembled and vacuum packaged within 5 minutes to obtain a packaged target assembly; wherein the drying is performed at 68° C. for 70 minutes under a vacuum condition of 0.005 Pa;

[0095] (3) In step (2), the target assembly is welded with a sheath by argon arc welding and the sheath is evacuated to a vacuum degree of 0.0007 Pa, and then hot isostatic pressing is performed within 4 hours. The hot isostatic pressing temperature is 270°C, the pressure is 96 MPa, and the hot isostatic pressing time is 3.2 hours. After the hot isostatic pressing is completed, the sheath is removed to obtain a welded target assembly.

[0096] Application Example 4

[0097] This application example provides an ultra-high purity copper target welding method. The method is the same as Application Example 1 except that the ultra-high purity copper target welding structure provided in Example 4 is used for welding.

[0098] Application Example 5

[0099] This application example provides an ultra-high purity copper target welding method. The method is the same as application example 1 except that the ultra-high purity copper target welding structure provided in embodiment 5 is used for welding.

[0100] Application Example 6

[0101] This application example provides an ultra-high purity copper target welding method, which is the same as Application Example 1 except that the vacuum packaging time in step (2) is 8 minutes.

[0102] Application Example 7

[0103] This application example provides an ultra-high purity copper target welding method, which is the same as application example 1 except that hot isostatic pressing welding is performed 26 hours after the sheath is evacuated.

[0104] Application Comparative Examples 1 to 3

[0105] Comparative Examples 1 to 3 are used to provide a method for welding an ultra-high purity copper target. The method is the same as Application Example 1 except that the ultra-high purity copper target welding structures provided in Comparative Examples 1 to 3 are used for welding.

[0106] 3. Test and Results

[0107] The target assembly after welding in Example 1, Application Examples 4 to 7 and Comparative Examples 1 to 3 was subjected to ultrasonic testing, and the ultrasonic testing results are as follows: Figure 3 As shown in the figure, A is the ultrasonic detection image of the target material assembly obtained by welding in Application Example 1 of the present invention, B represents the ultrasonic detection image of the target material assembly obtained by welding in Application Example 4; C represents the ultrasonic detection image of the target material assembly obtained by welding in Application Example 5 of the present invention; D represents the ultrasonic detection image of the target material assembly obtained by welding in Application Example 6 of the present invention; E represents the ultrasonic detection image of the target material assembly obtained by welding in Application Example 7 of the present invention; F represents the ultrasonic detection image of the target material assembly obtained by welding in Application Example 1 of the present invention; G represents the ultrasonic detection image of the target material assembly obtained by welding in Application Example 2 of the present invention; H represents the ultrasonic detection image of the target material assembly obtained by welding in Application Example 3 of the present invention.

[0108] from Figure 3 As can be seen from A, in Application Example 1, by strictly controlling the thread structure dimensions and process conditions, the ultrasonic detection result is darker in color, indicating that the welding quality of the ultra-high purity target material is good under this process and the thread is fully engaged.

[0109] from Figure 3It can be seen from B that the roughness of the back plate welding surface in Application Example 4 is relatively large, resulting in a lighter grayscale in the detection result of the target assembly after welding. This shows that the roughness of the welding surface is strictly controlled in the present invention, which improves the bite effect of the thread.

[0110] from Figure 3 It can be seen from C that the test result in Application Example 5 is worse than that in Application Example 1, which shows that the present invention can effectively prevent thread deformation and improve welding effect by strictly controlling the angle of the tip of the thread tooth.

[0111] from Figure 3 As can be seen from D and E, the extended vacuum packaging time in Application Example 6 and the hot isostatic pressing welding performed after the vacuumization of the sleeve for more than 24 hours in Application Example 7 both result in a welding effect worse than that in Application Example 1. This shows that in the present invention, it is preferred to strictly control the duration of vacuum packaging and the gap time between vacuumization of the sleeve and hot isostatic pressing, which can effectively reduce the oxidation of the welding surface of the ultra-high purity copper target and the copper alloy back plate, thereby ultimately improving the thread bite and further improving the welding effect.

[0112] from Figure 3 It can be seen from F, G and H that the adjustment of the thread pitch or depth in comparative examples 1 to 3 exceeds the scope of protection of the present invention, and the welding effect is far inferior to that of application example 1. This shows that the present invention greatly improves the welding effect of ultra-high purity copper target by strictly controlling the thread pitch and thread depth.

[0113] The conductivity test was conducted on the ultra-high purity copper target assembly welded in the above application example and the application comparison, and the test results are shown in Table 1.

[0114] Table 1

[0115] Conductivity (MS / m) Application Example 1 60.5 Application Example 2 60.4 Application Example 3 59.2 Application Example 4 60.1 Application Example 5 58.9 Application Example 6 59.4 Application Example 7 59.6 Application Comparative Example 1 58.6 Application Comparative Example 2 58.0 Application Comparative Example 3 58.2

[0116] From Table 1, we can see the following points:

[0117] (1) Comprehensive application examples 1 to 7 show that in application examples 1 to 7, the pitch of the threads is controlled at 0.15 to 0.25 mm, and the depth of the threads is controlled at 0.10 to 0.15 mm, so that the welding effect of the target assembly is excellent. After welding, the conductivity of the target assembly is ≥58.9MS / m, and the conductivity is good.

[0118] (2) Comprehensively from Application Example 1 and Application Examples 4 to 7, it can be seen that factors such as the roughness of the back plate welding surface, the thread size, the drying time, and the interval time from the sheath degassing to the hot isostatic pressing welding have a significant effect on the target material conductivity. This shows that the present invention adopts a further optimized welding surface roughness of ≤0.80 μm, a thread tooth tip angle of 55° or 60°, a vacuum packaging time of less than 5 minutes, and hot isostatic pressing welding is performed immediately after the sheath degassing, which improves the welding effect of the target material and the conductivity of the target assembly after welding;

[0119] (3) It can be seen from the combined application example 1 and the application comparison examples 1 to 3 that the pitch of the toothed thread in application example 1 is 0.15 mm, and the depth of the toothed thread is 0.12 mm. Compared with the thread pitch of 0.3 mm, the thread depth of 0.08 mm, and the thread depth of 0.20 mm in application comparison examples 1 to 3, respectively, the electrical conductivity of the target assembly after welding in application example 1 is 60.5 MS / m, while the electrical conductivity of the target assembly after welding in application comparison examples 1 to 3 is only 58.6 MS / m, 58.0 MS / m, and 58.2 MS / m, respectively. This shows that the present invention greatly improves the welding effect and the electrical conductivity of the target assembly after welding by strictly controlling the size of the toothed thread.

[0120] In summary, the ultra-high purity copper target welding structure and welding method provided by the present invention greatly improve the welding bonding effect and the conductivity of the target after welding by strictly controlling the size of the thread and assisting in the coordinated control of the angle of the thread tooth tip, the surface roughness of the welding surface and the welding process. The conductivity of the target assembly after welding is ≥58.9MS / m, which can ensure that the product welding strength meets the requirements, thereby ensuring that the target is safe and reliable during the sputtering process.

[0121] The applicant declares that the present invention illustrates the detailed structural features of the present invention through the above-mentioned embodiments, but the present invention is not limited to the above-mentioned detailed structural features, that is, it does not mean that the present invention must rely on the above-mentioned detailed structural features to be implemented. Those skilled in the art should understand that any improvement of the present invention, equivalent replacement of the components selected by the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for welding an ultra-high purity copper target, characterized in that: The welding method adopts an ultra-high purity copper target welding structure for welding; The welding method comprises the following steps: (1) After the welding surface of the target back plate is pretreated, the target back plate and the ultra-high purity copper target are assembled and vacuum packaged to obtain a packaged target assembly; The vacuum packaging time is ≤5min; (2) The target assembly described in step (1) is subjected to jacket welding and hot isostatic pressing welding in sequence to obtain a welded target assembly; The ultra-high purity copper target welding structure comprises an ultra-high purity copper target and a target back plate welded to the ultra-high purity copper target; The target material back plate comprises a welding surface, and the welding surface is provided with threads; The thread is a toothed thread; the angle of the tooth tip of the toothed thread is 55° or 60°; the roughness of the welding surface of the target back plate is ≤0.8 μm; The pitch of the thread is 0.15-0.25 mm, and the depth of the thread is 0.10-0.15 mm.

2. The welding method according to claim 1, characterized in that: The copper purity of the ultra-high purity copper target material is ≥6N.

3. The welding method according to claim 1, characterized in that: The target material back plate is a copper alloy back plate.

4. The welding method according to claim 3, characterized in that: The copper alloy back plate includes a CuZn alloy back plate or a CuCr alloy back plate.

5. The welding method according to claim 1, characterized in that: The pretreatment in step (1) includes rust removal, cleaning and drying performed in sequence.

6. The welding method according to claim 5, characterized in that: The rust removal comprises: using a wire brush to remove rust on the thread surface along the thread turning direction.

7. The welding method according to claim 5, characterized in that: The cleaning includes ultrasonic cleaning.

8. The welding method according to claim 7, characterized in that: The ultrasonic cleaning time is 22 to 28 minutes.

9. The welding method according to claim 7, characterized in that: The cleaning solution includes isopropyl alcohol.

10. The welding method according to claim 5, characterized in that: The drying temperature in step (1) is 62-75°C.

11. The welding method according to claim 5, characterized in that: The drying time is 65 to 85 minutes.

12. The welding method according to claim 5, characterized in that: The drying is performed under vacuum conditions.

13. The welding method according to claim 12, characterized in that: The vacuum degree of the drying is ≤0.01Pa.

14. The welding method according to claim 1, characterized in that: The sheath welding in step (2) is performed by argon arc welding.

15. The welding method according to claim 14, characterized in that: The material of the sheath is aluminum alloy.

16. The welding method according to claim 14, characterized in that: After the sheath is welded, the sheath is evacuated.

17. The welding method according to claim 16, characterized in that: The vacuum degree of the package is ≤0.001Pa.

18. The welding method according to claim 16, characterized in that: The time interval between the hot isostatic pressing welding and the vacuuming of the sheath in step (2) is ≤24h.

19. The welding method according to claim 1, characterized in that: The temperature of the hot isostatic pressing welding is 255-272°C.

20. The welding method according to claim 1, characterized in that: The pressure of the hot isostatic pressing welding is 96-105 MPa.

21. The welding method according to claim 1, characterized in that The hot isostatic pressing welding time is 3.2 to 4.5 hours.

22. The welding method according to claim 1, characterized in that: The method comprises the following steps: (1) After the welding surface of the target back plate is derusted, cleaned with isopropyl alcohol and dried in sequence, the target back plate and the ultra-high purity copper target are assembled and vacuum packaged within 5 minutes to obtain a packaged target assembly; (2) The target assembly of step (1) is subjected to argon arc welding and the sheath is evacuated to a vacuum degree of ≤0.001Pa, and then hot isostatic pressing is performed within 24 hours. The hot isostatic pressing temperature is 255-272°C, the pressure is 96-105MPa, and the hot isostatic pressing time is 3.2-4.5 hours. After the hot isostatic pressing is completed, the sheath is removed to obtain a welded target assembly.

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