Processing method of high-purity copper target material

Abstract

The invention provides a processing method of a high-purity copper target material, which comprises the following steps of: carrying out plastic processing on a high-purity copper target blank to obtain a deformed copper target blank, sequentially carrying out first-stage annealing and second-stage annealing on the deformed copper target blank, and then machining to obtain a finished product of the high-purity copper target material. According to the machining method provided by the invention, after the copper target material is subjected to plastic machining, two-stage annealing treatment is carried out, the target material still keeps a high-quality microstructure through precise control over the annealing process and balance of internal stress of the target material, and the target material still can keep high dimensional precision, low flatness and high parallelism after being machined such as cutting; therefore, the sputtering stability of the target material is improved, and the coating quality is improved.

Description

Technical Field

[0001] This invention belongs to the field of sputtering target technology, specifically relating to a processing method for high-purity copper targets. Background Technology

[0002] Sputtering is one of the main physical vapor deposition (PVD) techniques for preparing thin film materials. This technique utilizes ions generated by an ion source, accelerated by an electric field in a vacuum environment to form a high-energy ion beam, which bombards the surface of a solid target. The ions exchange kinetic energy with the target surface, causing the atoms to detach from the original solid and deposit on the substrate surface, thus forming the desired thin film. The bombarded solid material is called the sputtering target, which is the raw material for thin film deposition. Due to its advantages such as uniform film formation, high density, and good adhesion, sputtered thin film materials have been widely used in semiconductor integrated circuits, magnetic recording media, flat panel display devices, and various functional surface coatings.

[0003] Sputtering targets, especially high-purity copper targets, are core materials for the electronics and information industries. They are mainly used in electrodes and wiring in interconnects, barrier layers, and liquid crystal displays in integrated circuits. High-purity copper (typically requiring a purity of ≥99.99%) is the preferred material for preparing high-performance conductive thin films due to its excellent electrical conductivity, thermal conductivity, and resistance to electromigration.

[0004] High-purity copper sputtering targets must meet stringent requirements in terms of microstructure, including high density, high purity, and fine grain size. In practical applications, high-purity copper sputtering targets need to be processed into large square profiles to meet the coating requirements of large-size substrates. However, these large-size and high-performance characteristics present significant challenges during the processing stage. Specifically, after processing, the gradual release of internal stress leads to irregular deformations such as warping of the workpiece, making it difficult to achieve the micron-level precision requirements for flatness and parallelism in semiconductor-grade products. Furthermore, when processing large-area, thin workpieces, workpiece vibration is easily triggered, severely damaging surface smoothness and quality.

[0005] Therefore, there is a need to provide an effective process method that can effectively guarantee the dimensional accuracy and quality of high-purity copper sputtering targets. Summary of the Invention

[0006] In view of the shortcomings of the existing technology, the purpose of this invention is to provide a processing method for high-purity copper targets, which can effectively ensure the quality and dimensional accuracy of copper targets.

[0007] To achieve this objective, the present invention adopts the following technical solution:

[0008] This invention provides a method for processing high-purity copper sputtering targets, the method comprising the following steps:

[0009] After plastic processing, a high-purity copper target blank is obtained as a deformed copper target blank. The deformed copper target blank is then subjected to a first-stage annealing and a second-stage annealing, followed by machining to obtain the finished high-purity copper target material.

[0010] The processing method provided by this invention involves performing a two-stage annealing process on the copper target material after plastic processing. Through precise control of the annealing process, the internal pressure of the target material is balanced, and the target material still maintains a high-quality microstructure. After undergoing machining, such as cutting, the target material can still maintain high dimensional accuracy, low flatness, and high parallelism, thereby improving the sputtering stability of the target material and improving the coating quality.

[0011] The "high purity" refers to a purity of ≥99.99%.

[0012] Preferably, the plastic processing includes cold rolling and calendering performed sequentially.

[0013] Preferably, the hardness of the deformed copper target blank is 80-100HV, for example, it can be 80HV, 85HV, 90HV, 95HV or 100HV, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0014] Preferably, the average grain size of the deformed copper target blank is 30-50 μm, for example, it can be 30 μm, 35 μm, 40 μm, 45 μm or 50 μm, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0015] Preferably, the flatness of the deformed copper target blank is ≤1mm, for example, it can be 0.1mm, 0.2mm, 0.3mm, 0.4mm, 0.5mm, 0.6mm, 0.7mm, 0.8mm, 0.9mm or 1mm, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0016] Preferably, in the deformed copper target blank, the orientation rate of the (111) crystal plane is 70%-90%, for example, it can be 70%, 75%, 80%, 85% or 90%, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0017] Preferably, the length of the deformed copper target blank is ≥3m, for example, it can be 3m, 3.2m, 3.5m, 3.8m, 4m, 4.5m, 5m or 6m, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0018] Preferably, the thickness of the deformed copper target blank is ≤25mm, for example, it can be 1mm, 3mm, 5mm, 8mm, 10mm, 12mm, 15mm, 18mm, 20mm, 22mm or 25mm, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0019] Preferably, the first stage annealing process includes: heating the deformed copper target blank to a first annealing temperature and holding it thereafter.

[0020] Preferably, the first heating rate is ≥2℃ / min, for example, it can be 2℃ / min, 2.1℃ / min, 2.2℃ / min, 2.3℃ / min, 2.4℃ / min, 2.5℃ / min, 2.6℃ / min, 2.7℃ / min, 2.8℃ / min, 2.9℃ / min, 3℃ / min, 4℃ / min, 5℃ / min, 8℃ / min, 10℃ / min, 12℃ / min or 15℃ / min, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0021] Preferably, the first annealing temperature is 190-210℃, for example, it can be 190℃, 192℃, 195℃, 198℃, 200℃, 202℃, 205℃, 208℃ or 210℃, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0022] Preferably, the holding time at the first annealing temperature is 25-35 minutes, for example, it can be 25 minutes, 28 minutes, 30 minutes, 32 minutes or 35 minutes, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0023] Preferably, the second-stage annealing process includes: heating the deformed copper target blank from the first-stage annealing to the second annealing temperature and holding it thereafter.

[0024] Preferably, the second heating rate is ≥1℃ / min, for example, it can be 1℃ / min, 1.1℃ / min, 1.2℃ / min, 1.3℃ / min, 1.4℃ / min, 1.5℃ / min, 1.6℃ / min, 1.7℃ / min, 1.8℃ / min, 1.9℃ / min, 2℃ / min, 2.2℃ / min, 2.5℃ / min, 2.8℃ / min, 3℃ / min, 4℃ / min, 5℃ / min, 8℃ / min, 10℃ / min, 12℃ / min or 15℃ / min, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0025] Preferably, the second annealing temperature is 250-270°C, for example, it can be 250°C, 252°C, 255°C, 258°C, 260°C, 262°C, 265°C, 268°C or 270°C, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0026] Preferably, the holding time at the second annealing temperature is 110-130 min, for example, it can be 110 min, 112 min, 115 min, 118 min, 120 min, 122 min, 125 min, 128 min or 130 min, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0027] Preferably, after the second stage of annealing is completed, air cooling is performed.

[0028] Preferably, the hardness of the finished high-purity copper target material is 80-100HV, for example, it can be 80HV, 85HV, 90HV, 95HV or 100HV, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0029] Preferably, the average grain size of the finished high-purity copper target material is 30-50 μm, for example, it can be 30 μm, 35 μm, 40 μm, 45 μm or 50 μm, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0030] Preferably, the flatness of the finished high-purity copper target material is ≤1.8mm, for example, it can be 0.1mm, 0.2mm, 0.3mm, 0.4mm, 0.5mm, 0.6mm, 0.7mm, 0.8mm, 0.9mm, 1mm, 1.5mm or 1.8mm, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0031] Preferably, the parallelism tolerance of the finished high-purity copper target material is ≤0.2mm, for example, it can be 0.2mm, 0.18mm, 0.15mm, 0.12mm, 0.1mm, 0.08mm or 0.05mm, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0032] Preferably, the orientation rate of the (111) crystal plane of the high-purity copper target product is 70%-90%, for example, it can be 70%, 75%, 80%, 85% or 90%, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0033] Preferably, the processing method further includes: sequentially welding, surface treating, cleaning and packaging the high-purity copper target material to obtain a high-purity copper target material component product.

[0034] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0035] The processing method provided by this invention involves performing a two-stage annealing process on the copper target material after plastic processing. Through precise control of the annealing process, the internal stress of the target material is balanced, and the target material still maintains a high-quality microstructure. After machining, such as cutting, the target material can still maintain high dimensional accuracy, low flatness and high parallelism, thereby improving the sputtering stability of the target material and improving the coating quality. Detailed Implementation

[0036] The technical solution of the present invention will be further illustrated below through specific embodiments.

[0037] Example 1

[0038] This embodiment provides a method for processing high-purity copper sputtering targets, the method comprising the following steps:

[0039] (1) A high-purity copper target billet with a purity of 99.999% is subjected to cold rolling and rolling in sequence. The cold rolling is carried out in two passes with a reduction rate of 15% per pass and a rolling speed of 20m / min. The rolling is carried out in two passes with a reduction rate of 1% per pass and a rolling speed of 10m / min to obtain a deformed copper target billet. The deformed copper target billet has a hardness of 90HV, an average grain size of 40μm, a flatness of 1mm, an orientation rate of 80% for the (111) crystal plane, a length of 3m, and a thickness of 25mm.

[0040] (2) The deformed copper target billet is heated to 200℃ in 90 min, that is, at a rate of 2.2℃ / min. After heating to 200℃, it is held for the first annealing for 30 min. Then, it is heated from 200℃ to 260℃ in 60 min, that is, at a rate of 1℃ / min. After heating to 260℃, it is held for the second annealing for 120 min to obtain the heat-treated high-purity copper target material.

[0041] (3) The heat-treated high-purity copper target is cut to achieve the predetermined size of the target, and the high-purity copper target product is obtained.

[0042] Example 2

[0043] This embodiment provides a method for processing high-purity copper sputtering targets, the method comprising the following steps:

[0044] (1) A high-purity copper target billet with a purity of 99.999% is subjected to cold rolling and rolling in sequence. The cold rolling is carried out in two passes with a reduction rate of 15% per pass and a rolling speed of 20m / min. The rolling is carried out in two passes with a reduction rate of 1% per pass and a rolling speed of 10m / min to obtain a deformed copper target billet. The deformed copper target billet has a hardness of 90HV, an average grain size of 40μm, a flatness of 1mm, an orientation rate of 80% for the (111) crystal plane, a length of 3m, and a thickness of 25mm.

[0045] (2) The deformed copper target billet is heated to 210°C in 70 min, that is, at a rate of 3°C / min. After heating to 210°C, it is held for the first annealing for 25 min. Then, it is heated from 210°C to 250°C in 16 min, that is, at a rate of 2.5°C / min. After heating to 250°C, it is held for the second annealing for 130 min to obtain the heat-treated high-purity copper target material.

[0046] (3) The heat-treated high-purity copper target is cut to achieve the predetermined size of the target, and the high-purity copper target product is obtained.

[0047] Example 3

[0048] This embodiment provides a method for processing high-purity copper sputtering targets, the method comprising the following steps:

[0049] (1) A high-purity copper target billet with a purity of 99.999% is subjected to cold rolling and rolling in sequence. The cold rolling is carried out in two passes with a reduction rate of 15% per pass and a rolling speed of 20m / min. The rolling is carried out in two passes with a reduction rate of 1% per pass and a rolling speed of 10m / min to obtain a deformed copper target billet. The deformed copper target billet has a hardness of 90HV, an average grain size of 40μm, a flatness of 1mm, an orientation rate of 80% for the (111) crystal plane, a length of 3m, and a thickness of 25mm.

[0050] (2) The deformed copper target billet is heated to 190°C in 38 min, that is, at a rate of 5°C / min. After heating to 190°C, it is held for the first annealing for 35 min. Then, it is heated from 190°C to 270°C in 20 min, that is, at a rate of 4°C / min. After heating to 270°C, it is held for the second annealing for 110 min to obtain the heat-treated high-purity copper target material.

[0051] (3) The heat-treated high-purity copper target is cut to achieve the predetermined size of the target, and the high-purity copper target product is obtained.

[0052] Example 4

[0053] This embodiment provides a processing method for high-purity copper target material. Compared with embodiment 1, the temperature of the first annealing in step (2) is set to 160°C, and the rest is the same as in embodiment 1.

[0054] Example 5

[0055] This embodiment provides a processing method for high-purity copper target material. Compared with embodiment 1, the temperature of the first annealing in step (2) is set to 240°C, and the rest is the same as in embodiment 1.

[0056] Example 6

[0057] This embodiment provides a processing method for high-purity copper target material. Compared with embodiment 1, the temperature of the second annealing in step (2) is set to 220°C, and the rest is the same as in embodiment 1.

[0058] Example 7

[0059] This embodiment provides a processing method for high-purity copper target material. Compared with embodiment 1, the temperature of the second annealing in step (2) is set to 300°C, and the rest is the same as in embodiment 1.

[0060] Comparative Example 1

[0061] This comparative example provides a processing method for a high-purity copper target material. Compared with Example 1, the annealing step (2) is not performed, and the rest is the same as in Example 1.

[0062] Comparative Example 2

[0063] This comparative example provides a processing method for high-purity copper target material. Compared with Example 1, the first annealing in step (2) is not performed. Instead, the deformed copper target blank is directly heated to 260°C at a rate of 1°C / min for annealing. The rest is the same as in Example 1.

[0064] The performance of the high-purity copper sputtering targets obtained in the examples and comparative examples was tested, and the results are shown in Table 1.

[0065] Table 1

[0066]

[0067] As can be seen from Table 1, the processing method for copper targets provided by the present invention can effectively maintain the high-quality microstructure of copper targets, maintain high hardness, and have a fine and uniform grain structure. Through precise control of plastic processing and annealing processes, the internal stress of the target can be effectively balanced. After machining, the target can still maintain high dimensional accuracy, low flatness, and high parallelism, which is especially suitable for large-size thin plate targets that are difficult to process.

[0068] Furthermore, compared to other embodiments, the target materials of Embodiments 1-3 are of superior quality. Compared to Embodiment 1, in Embodiments 4-7, changing the annealing temperature has a certain impact on the microstructure of the copper target material, which to some extent is detrimental to its performance improvement. In Comparative Examples 1 and 2, when a reasonable annealing process is lacking during the processing of the copper target material, the microstructure of the target material decreases, and machining significantly deteriorates the dimensional accuracy of the target material, making it unable to meet the application requirements.

[0069] In summary, the processing method provided by this invention involves a two-stage annealing process after plastic processing of the copper target material. Through precise control of the annealing process, the internal stress of the target material is balanced, and the target material still maintains a high-quality microstructure. After machining, such as cutting, the target material can still maintain high dimensional accuracy, low flatness, and high parallelism, thereby improving the sputtering stability of the target material and improving the coating quality.

[0070] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for processing high-purity copper sputtering targets, characterized in that, The processing method includes the following steps: After plastic processing, a high-purity copper target blank is obtained as a deformed copper target blank. The deformed copper target blank is then subjected to a first-stage annealing and a second-stage annealing, followed by machining to obtain the finished high-purity copper target material.

2. The processing method according to claim 1, characterized in that, The plastic processing includes cold rolling and calendering performed sequentially.

3. The processing method according to claim 1 or 2, characterized in that, The hardness of the deformed copper target blank is 80-100HV; Preferably, the average grain size of the deformed copper target blank is 30-50 μm; Preferably, the flatness of the deformed copper target blank is ≤1mm; Preferably, in the deformed copper target blank, the orientation rate of the (111) crystal plane is 70%-90%.

4. The processing method according to any one of claims 1-3, characterized in that, The length of the deformed copper target blank is ≥3m; Preferably, the thickness of the deformed copper target blank is ≤25mm.

5. The processing method according to any one of claims 1-4, characterized in that, The first stage of annealing includes: heating the deformed copper target blank to the first annealing temperature and holding it at that temperature.

6. The processing method according to claim 5, characterized in that, The rate of the first heating is ≥2℃ / min; Preferably, the first annealing temperature is 190-210℃; Preferably, the holding time at the first annealing temperature is 25-35 minutes.

7. The processing method according to any one of claims 1-6, characterized in that, The second-stage annealing process includes: heating the deformed copper target blank from the first-stage annealing to the second annealing temperature and holding it at that temperature.

8. The processing method according to claim 7, characterized in that, The second heating rate is ≥1℃ / min; Preferably, the second annealing temperature is 250-270℃; Preferably, the holding time at the second annealing temperature is 110-130 min; Preferably, after the second stage of annealing is completed, air cooling is performed.

9. The processing method according to any one of claims 1-8, characterized in that, The hardness of the finished high-purity copper target material is 80-100HV; Preferably, the average grain size of the high-purity copper target material is 30-50 μm; Preferably, the flatness of the finished high-purity copper target material is ≤1.8mm; Preferably, the parallelism tolerance of the finished high-purity copper target material is ≤0.2mm; Preferably, the orientation rate of the (111) crystal plane of the high-purity copper target product is 70%-90%.

10. The processing method according to any one of claims 1-9, characterized in that, The processing method further includes: sequentially welding, surface treating, cleaning and packaging the high-purity copper target material to obtain a high-purity copper target material component product.

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