Preparation method of copper target material

Abstract

The invention provides a preparation method of a copper target material, and belongs to the technical field of metal target material preparation. According to the preparation method of the copper target material, the copper blank is subjected to hot rolling, thick columnar crystals in an original as-cast structure of the copper blank are crushed into fine grains through hot rolling, and the grain structure is more uniform; and the total volume of gaps among crystal grains is rapidly reduced, an original loose structure is compacted into a compact structure, densification treatment of the copper blank is achieved, and the dislocation density of the copper blank is increased. And then the copper target blank is cooled to 25-40 DEG C and then is subjected to cold rolling, crystal grains in the copper target blank are further rearranged, gaps between the crystal grains are further compressed, the crystal grain structure of the copper target blank is more compact, and the dislocation density is further improved. And finally, a temperature stepped annealing process is adopted, so that internal stress generated in the hot rolling and cold rolling processes can be effectively eliminated, and the hardness of the copper target blank cannot be excessively reduced due to the annealing process.

Description

Technical Field

[0001] The invention belongs to the technical field of metal target material preparation, and particularly relates to a method for preparing a copper target material. Background Art

[0002] Copper targets are widely used in fields such as semiconductors, displays, and solar energy, requiring high purity, high hardness, and a fine crystalline structure. Traditional hot forging processes for preparing copper targets suffer from insufficient hardness and a high proportion of twins. This results in poor stability during magnetron sputtering and reduces the film formation rate of the copper target coating process.

[0003] For example, a prior art provides a method for preparing a copper target material, which uses a hot forging process to densify the copper billet, crush the coarse columnar crystals in the original cast structure of the copper ingot, and then reduce the thickness by 10 to 50% through rolling. After annealing, a copper target material is formed. However, the copper target material prepared by this prior art still has the problem that the dislocation density of the copper target material does not increase significantly, so that the hardness of the copper target material needs to be further improved. Summary of the Invention

[0004] The object of the present invention is to provide a method for preparing a copper target material. The copper target material prepared by the present invention has a high dislocation and low twin ratio, higher hardness, better stability during magnetron sputtering, and improves the film formation rate of the copper target material coating process.

[0005] In order to achieve the purpose of the present invention, the present invention provides the following technical solutions:

[0006] A method for preparing a copper target material comprises the following steps:

[0007] Provide copper billets;

[0008] The copper blank is heat-treated and then subjected to a first rolling process to obtain a copper target blank; the cumulative deformation of the first rolling process is 80-90%;

[0009] The copper target material blank is cooled to 25-40° C. and then subjected to a second rolling process, and annealed to obtain the copper target material; the cumulative deformation amount of the second rolling process is 30-55%.

[0010] Preferably, the heat treatment comprises successively keeping the temperature at 500-600° C. for 60-100 minutes and keeping the temperature at 800-900° C. for 100-180 minutes.

[0011] Preferably, the heating rate to the temperature required for heat treatment is 5 to 15° C. / min.

[0012] Preferably, the first rolling comprises multiple rolling steps; the deformation amount of the copper billet after each rolling step is 10-25%.

[0013] Preferably, the second rolling comprises multiple rolling steps; the deformation of the copper billet after each rolling step is 5-10%.

[0014] Preferably, the cooling rate of the copper target blank when cooled to 25-40° C. is 55-70° C. / min.

[0015] Preferably, the annealing comprises sequentially keeping the temperature at 200-300° C. for 90-150 minutes and keeping the temperature at 300-400° C. for 60-120 minutes.

[0016] Preferably, the heating rate to the annealing temperature is 5-15° C. / min.

[0017] The present invention provides a method for preparing a copper target material, comprising the following steps: providing a copper billet; heat-treating the copper billet and then performing a first rolling process to obtain a copper target billet; the cumulative deformation of the first rolling process is 80-90%; cooling the copper target billet to 25-40°C and then performing a second rolling process, and annealing to obtain the copper target material; the cumulative deformation of the second rolling process is 30-55%. In the present invention, the copper billet is heat-treated and then hot-rolled. The hot rolling process breaks down the coarse columnar crystals in the original cast structure of the copper billet into fine grains, making the grain structure more uniform. The total volume of the voids between the grains is rapidly reduced, and the original loose structure is compacted into a compact structure, thereby achieving densification of the copper billet and significantly increasing the dislocation density of the copper billet. The copper target material blank is then cooled to 25-40°C and then cold rolled. The grains in the copper target material blank are further rearranged, and the gaps between the grains are further compressed, thereby making the grain structure of the copper target material blank denser and further increasing the dislocation density. It has been found through testing that the hardness of the copper target material blank can be as high as 120-160HV. Furthermore, the present invention adopts a temperature step annealing process, which can effectively eliminate the internal stress generated during hot rolling and cold rolling, and fully release the internal stress formed in the copper target material blank, thereby reducing the twin ratio of the copper target material; at the same time, the temperature step annealing can ensure that the hardness of the copper target material blank is not reduced too much. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0019] Figure 1 This is the EBSD image of the copper target obtained in Example 3 of the present invention. DETAILED DESCRIPTION

[0020] The present invention provides a method for preparing a copper target, comprising the following steps:

[0021] Provide copper billets;

[0022] The copper blank is heat-treated and then subjected to a first rolling process to obtain a copper target blank; the cumulative deformation of the first rolling process is 80-90%;

[0023] The copper target material blank is cooled to 25-40° C. and then subjected to a second rolling process, and annealed to obtain the copper target material; the cumulative deformation amount of the second rolling process is 30-55%.

[0024] In the present invention, unless otherwise specified, all preparation raw materials are commercially available products well known to those skilled in the art.

[0025] In the present invention, the copper blank may be a 4N high-purity copper ingot with an oxygen content of less than 5 ppm.

[0026] The present invention heat treats a copper billet and then performs a first rolling to obtain a copper target billet; the cumulative deformation of the first rolling is 80-90%. In the present invention, the heat treatment includes sequentially keeping the temperature at 500-600°C for 60-100 minutes and keeping the temperature at 800-900°C for 100-180 minutes. In the present invention, the temperature is raised from room temperature to 500-600°C, kept at 500-600°C for 60-100 minutes, and in a specific embodiment, kept at 600°C for 90 minutes; then the temperature is raised from 500-600°C to 800-900°C, kept at 800-900°C for 100-180 minutes, and in a specific embodiment, kept at 850°C for 100 minutes; the heating rate to the required temperature for heat treatment in the present invention is 5-15°C, and in a specific embodiment, it can be 10°C / min.

[0027] In the present invention, the cumulative deformation of the first rolling is 80-90%, and in a specific embodiment, it can be 81%, 84% or 85%; the first rolling includes multiple rolling steps; the deformation of the copper billet after each rolling step is 10-25%, and in a specific embodiment, it can be 11% or 15%. The present invention has no special limitation on rolling. In a specific embodiment, a Φ750×800 two-roll reversible hot and cold rolling mill is used, with a maximum rolling force of 8000KN and a rolling speed of 5-20M / min. The present invention hot-rolls the copper billet after heat treatment and heat preservation. Hot rolling breaks the coarse columnar crystals in the original cast structure of the copper billet into fine grains, making the grain structure more uniform; and the total volume of the voids between the grains is rapidly reduced, and the original loose structure is compacted into a compact structure, thereby achieving densification of the copper billet and greatly increasing the dislocation density of the copper billet.

[0028] After obtaining the copper target blank, the present invention cools the copper target blank to 25-40°C and then performs a second rolling, and then anneals to obtain the copper target. In the present invention, the cooling rate of the copper target blank to 25-40°C is 55-70°C / min, and in a specific embodiment, it can be 60°C / min, and the cooling method can be water cooling.

[0029] In the present invention, the cumulative deformation of the second rolling is 30-55%, and in specific embodiments, can be 41.4 or 47.5%. The second rolling includes multiple rolling steps, and the deformation of the copper billet after each rolling step is 5-10%. The present invention cools the copper target billet to 25-40°C before cold rolling, which further rearranges the grains in the copper target billet and further compresses the gaps between the grains, thereby making the grain structure of the copper target billet denser and further increasing the dislocation density. The Vickers hardness of the copper target billet obtained after cold rolling according to the present invention is as high as 120-160 HV.

[0030] In the present invention, the annealing includes: heating from room temperature to 200-300°C, holding at 200-300°C for 90-150 minutes, and in a specific embodiment, holding at 260°C for 120 minutes; heating from 200-300°C to 300-400°C, and holding at 300-400°C for 60-120 minutes, and in a specific embodiment, holding at 340°C for 90 minutes. In the present invention, the heating rate to the desired annealing temperature is 5-15°C / min. The present invention adopts a temperature step annealing process, which can effectively eliminate the internal stress generated during hot rolling and cold rolling, and fully release the internal stress formed in the copper target material blank compared to conventional annealing, thereby reducing the twin ratio of the copper target material. The results of the embodiment of the present invention show that the twin ratio of the obtained copper target material is 42.90-53.44%; at the same time, the temperature step annealing can ensure that the hardness of the copper target material blank is not excessively reduced. The results of the embodiment of the present invention show that the Vickers hardness of the finally prepared copper target material is 114-138HV.

[0031] In order to further illustrate the present invention, the preparation method of the copper target provided by the present invention is described in detail below with reference to the accompanying drawings and examples, but they should not be construed as limiting the scope of protection of the present invention.

[0032] Example 1

[0033] The copper billet is placed in a resistance furnace, gradually heated from room temperature to 600°C, kept at 600°C for 90 minutes, gradually heated from 600°C to 850°C, kept at 850°C for 100 minutes, and the copper billet is taken out for hot rolling. The thickness of the copper billet is reduced by 10-25% after each rolling, until the cumulative deformation of the copper billet after rolling is 84%, that is, the thickness is reduced by 84%. After the hot rolling is completed, the copper billet is placed in a water tank and quickly cooled to room temperature before being taken out to obtain a copper target billet;

[0034] The copper target blank is cold rolled at room temperature, and the thickness of the copper target blank is reduced by 5-10% after each rolling, until the cumulative deformation of the copper target blank after cold rolling is 41.5%; the copper target blank material is placed in an annealing furnace for temperature gradient annealing, and the temperature gradient annealing treatment includes: placing the copper target blank material in the annealing furnace, gradually heating it from room temperature to 260°C, keeping it at 260°C for 120 minutes, gradually heating it from 260°C to 340°C, keeping it at 340°C for 90 minutes, and then naturally cooling it to room temperature to obtain a copper target material.

[0035] Example 2

[0036] The copper billet is placed in a resistance furnace, gradually heated from room temperature to 600°C, kept at 600°C for 90 minutes, gradually heated from 600°C to 850°C, kept at 850°C for 100 minutes, and the copper billet is taken out for hot rolling. The thickness of the copper billet is reduced by 10-25% after each rolling, until the cumulative deformation of the copper billet after rolling is 81%, that is, the thickness is reduced by 81%. After the hot rolling is completed, the copper billet is placed in a water tank and quickly cooled to room temperature before being taken out to obtain a copper target billet;

[0037] The copper target blank is cold rolled at room temperature, and the thickness of the copper target blank is reduced by 5-10% after each rolling, until the cumulative deformation of the copper target blank after cold rolling is 47.5%; the copper target blank material is placed in an annealing furnace for temperature gradient annealing, and the temperature gradient annealing treatment includes: placing the copper target blank material in the annealing furnace, gradually heating it from room temperature to 260°C, keeping it at 260°C for 120 minutes, gradually heating it from 260°C to 340°C, keeping it at 340°C for 90 minutes, and then naturally cooling it to room temperature to obtain a copper target material.

[0038] Example 3

[0039] The copper billet is placed in a resistance furnace, gradually heated from room temperature to 600°C, kept at 600°C for 90 minutes, gradually heated from 600°C to 850°C, kept at 850°C for 100 minutes, and the copper billet is taken out for hot rolling. The thickness of the copper billet is reduced by 10-25% after each rolling, until the cumulative deformation of the copper billet after rolling is 84%, that is, the thickness is reduced by 84%. After the hot rolling is completed, the copper billet is placed in a water tank and quickly cooled to room temperature before being taken out to obtain a copper target billet;

[0040] The copper target blank is cold rolled at room temperature, and the thickness of the copper target blank is reduced by 5-10% after each rolling, until the cumulative deformation of the copper target blank after cold rolling is 47.5%; the copper target blank material is placed in an annealing furnace for temperature gradient annealing, and the temperature gradient annealing treatment includes: placing the copper target blank material in the annealing furnace, gradually heating it from room temperature to 260°C, keeping it at 260°C for 120 minutes, gradually heating it from 260°C to 340°C, keeping it at 340°C for 90 minutes, and then naturally cooling it to room temperature to obtain a copper target material.

[0041] Comparative Example 1

[0042] The copper billet is placed in a resistance furnace, gradually heated from room temperature to 600°C, kept at 600°C for 90 minutes, gradually heated from 600°C to 850°C, kept at 850°C for 100 minutes, and the copper billet is taken out for hot rolling. The thickness of the copper billet is reduced by 10-25% after each rolling, until the cumulative deformation of the copper billet after rolling is 91%, that is, the thickness is reduced by 91%. After the hot rolling is completed, the copper billet is placed in a water tank and quickly cooled to room temperature before being taken out to obtain a copper target billet.

[0043] The copper target blank material is placed in an annealing furnace for temperature gradient annealing. The temperature gradient annealing treatment includes: placing the copper target blank material in the annealing furnace, gradually heating it from room temperature to 260°C, keeping it at 260°C for 120 minutes, gradually heating it from 260°C to 340°C, keeping it at 340°C for 90 minutes, and then naturally cooling it to room temperature to obtain a copper target material.

[0044] Comparative Example 2

[0045] A copper target blank was prepared according to the preparation method of Comparative Example 1, and the copper target blank was placed in an annealing furnace for annealing, gradually heated from room temperature to 400°C, kept at 400°C for 180 minutes, and then naturally cooled to room temperature to obtain a copper target.

[0046] Comparative Example 3

[0047] A copper target blank was prepared according to the preparation method of Example 3, and the copper target blank was placed in an annealing furnace for annealing, gradually heated from room temperature to 400°C, kept at 400°C for 180 minutes, and then naturally cooled to room temperature to obtain a copper target.

[0048] Test Case

[0049] The Vickers hardness, dislocation density and twin ratio of the copper targets obtained in Examples 1 to 3 and Comparative Examples 1 to 3 were tested, wherein the hardness testing equipment was a Vickers hardness tester, and the testing standard was GB / T 4340.2-2012 "Metallic Materials - Vickers Hardness Test - Part 2: Inspection and Calibration of Hardness Testers"; the dislocation density was tested using a German ZEISS Sigma 300 field emission scanning electron microscope, and the detection method was EBSD scanning test. The results are shown below.

[0050] Table 1 Performance test results of copper targets obtained in Examples 1 to 3 and Comparative Examples 1 to 3

[0051]

[0052] The results in Table 1 show that the copper target prepared by the present invention has a low twin ratio and has high dislocation density and high hardness. Figure 1 This is the EBSD image of the copper target obtained in Example 3 of the present invention. Figure 1 The results show that the copper target material has uniform grain size and uniform distribution. After coating with the copper target material, the film layer is uniform and the coating stability is improved.

[0053] Although the above embodiment provides a detailed description of the present invention, it is only a part of the embodiments of the present invention, not all of the embodiments. People can also obtain other embodiments based on this embodiment without creativity, and these embodiments all fall within the scope of protection of the present invention.

Claims

1. A method for preparing a copper target, characterized in that: The following steps are involved: Provide copper billets; The copper blank is heat-treated and then subjected to a first rolling process to obtain a copper target blank; the cumulative deformation of the first rolling process is 80-90%; The copper target material blank is cooled to 25-40° C. and then subjected to a second rolling process, and annealed to obtain the copper target material; the cumulative deformation amount of the second rolling process is 30-55%.

2. The preparation method according to claim 1, characterized in that The heat treatment comprises sequentially keeping the temperature at 500-600° C. for 60-100 minutes and keeping the temperature at 800-900° C. for 100-180 minutes.

3. The preparation method according to claim 2, characterized in that The heating rate to the temperature required for heat treatment is 5 to 15°C / min.

4. The preparation method according to claim 1, characterized in that The first rolling includes multiple rolling steps; the deformation amount of the copper billet after each rolling step is 10-25%.

5. The preparation method according to claim 1, characterized in that The second rolling comprises multiple rolling steps; the deformation of the copper billet after each rolling step is 5-10%.

6. The preparation method according to claim 1, characterized in that The cooling rate of the copper target blank when cooled to 25-40° C. is 55-70° C. / min.

7. The preparation method according to claim 1, characterized in that The annealing comprises sequentially keeping the temperature at 200-300° C. for 90-150 minutes and keeping the temperature at 300-400° C. for 60-120 minutes.

8. The preparation method according to claim 7, characterized in that The heating rate to the annealing temperature is 5 to 15°C / min.

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