Copper Single Crystal and Its Preparation Method

Abstract

This invention provides a copper single crystal and its preparation method. The preparation method includes: placing elemental copper in a heating container and then placing it in a heating furnace; evacuating the furnace and introducing an inert gas to melt the elemental copper, obtaining a copper melt; lowering the copper melt at a speed of 2-10 mm / h to grow a crystal, obtaining a copper single crystal; wherein the heating container has a conical bottom, the opening direction of the conical bottom is opposite to the direction of descent, and the inner diameter of the heating container is ≥75 mm. The preparation method of this invention can prepare large-size copper single crystals, and the single crystal is not easily detached during the preparation process. Using a heating container with a conical bottom to place the raw material elemental copper enables precise nucleation at the tip during descent, and the geometric screening of the conical surface suppresses impurities and stabilizes the solid-liquid interface, thereby significantly improving the integrity and yield of the single crystal.

Description

Technical Field

[0001] This invention relates to the field of single crystal growth technology, and more specifically, to a copper single crystal and its preparation method. Background Technology

[0002] Copper single crystals have no grain boundaries and low defect rates, resulting in excellent electrical conductivity and signal transmission properties, good plasticity, and superior corrosion resistance. They offer significant advantages in high-quality signal transmission, integrated circuit packaging, electronic devices, and power transmission. Therefore, copper single crystals have a broader application prospect than polycrystalline copper.

[0003] Currently, the main method for preparing bulk copper single crystals is the hot continuous casting method (OCC method), which typically produces copper single crystals with a diameter not exceeding 10 mm. The Czochralski method (CZ method) can produce bulk copper single crystals with a diameter greater than 10 mm. This method involves inserting a seed crystal above the melt during preparation, and through the rotation and pulling of the seed crystal, the crystal grows along a specific crystal orientation. To eliminate dislocations caused by the temperature difference between the seed crystal and the melt within the crystal, a 3-5 mm neck is usually grown through rapid CZ. However, as the size of the copper single crystal increases, this 3-5 mm diameter neck can detach due to overload. Therefore, the neck severely limits the size of the copper single crystal, and the CZ method also has a relatively slow growth rate, resulting in low production efficiency.

[0004] Chinese patent application CN113802176A discloses a single-crystal copper growth process using a crucible lowering method for sequential crystallization. The single-crystal preparation process requires heating, holding, purging with inert gas, lowering the crystal, and annealing. The crucible used is made of tungsten, and a fluxing agent is also required. This method requires a large number of auxiliary materials and has a lengthy process. Chinese patent application CN114197031A discloses a method for preparing bromine-lead-copper single crystals using a two-step method of polycrystalline material preparation and crystal growth. The resulting bromine-lead-copper single crystal has a size of 18×50mm. 3 This method requires sealing the quartz crucible with a sealing machine, has high requirements for vacuum levels, and can only produce single crystals of limited size.

[0005] Therefore, there is an urgent need to develop a method for preparing large-size, simple, and efficient copper single crystals. Summary of the Invention

[0006] The main objective of this invention is to provide a copper single crystal and its preparation method, so as to solve the problems of limited single crystal size, slow crystal growth rate and high preparation cost in the existing copper single crystal preparation methods.

[0007] To achieve the above objectives, according to one aspect of the present invention, a method for preparing copper single crystals is provided, the method comprising: step S1, placing elemental copper in a heating container and then placing it in a heating furnace, evacuating the furnace and introducing an inert gas to melt the elemental copper to obtain a copper melt; step S2, lowering the copper melt at a speed of 2~10 mm / h to grow a crystal to obtain a copper single crystal; wherein, the heating container has a conical bottom, the opening direction of the conical bottom is opposite to the direction of descent, and the inner diameter of the heating container is ≥75 mm.

[0008] Furthermore, in step S1 above, the cone angle at the bottom of the cone is 50~100°; the inner diameter of the heating container is 75~150mm.

[0009] Furthermore, in step S1 above, the heating container is a crucible, the material of the crucible is graphite or quartz, and the purity of the crucible is 99.99~99.9999%.

[0010] Furthermore, in step S1 above, the purity of elemental copper is 99.99~99.9999%.

[0011] Furthermore, in step S1 above, after evacuating to 0.1~500Pa, an inert gas with a pressure of 100000~115000Pa is introduced, and this process is repeated more than three times; and / or, the inert gas is argon.

[0012] Furthermore, in step S1 above, the melting holding temperature is 1190~1250℃, and the melting holding time is 1~5h.

[0013] Furthermore, in step S2 above, the descent speed is 2~5 mm / h, the descent time is 60~100h, and the temperature during the descent process is 1200~1220℃.

[0014] Furthermore, during the aforementioned descent process, the temperature difference along the axial direction of the heating container is ≤10℃.

[0015] According to another aspect of the present invention, a copper single crystal is provided, which is prepared by the preparation method described above.

[0016] Furthermore, the diameter of the copper single crystal is 75~150mm, and the purity of the copper single crystal is 99.99~99.9999%.

[0017] By applying the technical solution of this invention, this application achieves the preparation of large-size copper single crystals by lowering the heating container and controlling the size of the heating container within the aforementioned range. This not only effectively overcomes the shortcomings of the hot casting method for preparing copper single crystals with a diameter not exceeding 10 mm, but also overcomes the problem of single crystal detachment due to overload during the Czochralski method for preparing large-size copper single crystals. Using a heating container with a conical bottom to hold the raw material elemental copper allows for single-point nucleation at the tip during the descent. The conical geometric screening suppresses impurities and stabilizes the solid-liquid interface, thereby significantly improving the integrity and yield of the single crystal. If the descent speed is too slow, the solidification rate is too slow, causing the melt to remain in the high-temperature zone for a long time, making it easy for impurities to accumulate. It also leads to insufficient supercooling, excessively long high-temperature residence time of the crystal, increased thermal stress, and a tendency to produce polycrystalline or twinned crystals. If the descent speed is too fast, the cooling rate is too fast, the solid-liquid interface becomes unstable, and the continuity of the single crystal is easily damaged. Therefore, this application controls the descent speed of the heating container within the aforementioned range, significantly improving the speed of copper single crystal preparation compared to the Czochralski method, thereby increasing the growth rate of large-size copper single crystals and thus improving the preparation efficiency. Furthermore, this application requires no additional additives, thus reducing costs. By introducing an inert gas after vacuuming, the melting process occurs under positive pressure, which improves the purity of the copper melt and consequently, the purity of the copper single crystal. In summary, the preparation method of this application has advantages such as low cost, high efficiency, and the ability to obtain large-size copper single crystals. Attached Figure Description

[0018] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0019] Figure 1 A schematic diagram of the crucible structure in Embodiment 1 of this application is shown;

[0020] Figure 2 The X-ray diffraction pattern of the copper single crystal in Example 1 of the application is shown;

[0021] Figure 3 An electron backscattering pattern of a copper single crystal in Example 1 of the application is shown. Detailed Implementation

[0022] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0023] As analyzed in the background section of this application, the existing methods for preparing copper single crystals have problems such as limited single crystal size, slow crystal growth rate, and high preparation cost. In order to solve the above problems, this application provides a copper single crystal and its preparation method.

[0024] In a typical embodiment of this application, a method for preparing copper single crystals is provided. The method includes: step S1, placing elemental copper in a heating container and then placing it in a heating furnace, evacuating the furnace, and introducing an inert gas to melt the elemental copper to obtain copper melt; step S2, lowering the copper melt at a speed of 2~10 mm / h to grow crystals and obtain copper single crystals; wherein, the heating container has a conical bottom, the opening direction of the conical bottom is opposite to the direction of descent, and the inner diameter of the heating container is ≥75 mm.

[0025] This application achieves the preparation of large-size copper single crystals by lowering the heating container and controlling its size within the aforementioned range. This not only effectively overcomes the limitation of hot casting methods where copper single crystal diameters cannot exceed 10mm, but also overcomes the problem of single crystal detachment due to overload during the Czochralski method for preparing large-size copper single crystals. Using a heating container with a conical bottom to hold the raw material elemental copper allows for single-point nucleation at the tip during the descent. The conical geometry suppresses impurities and stabilizes the solid-liquid interface, significantly improving the integrity and yield of the single crystal. If the descent speed is too slow, the solidification rate is too slow, causing the melt to remain in the high-temperature zone for an extended period, leading to impurity accumulation and insufficient supercooling. This results in excessively long high-temperature residence time for the crystal, increasing thermal stress and potentially causing polycrystalline or twinned crystals. If the descent speed is too fast, the cooling rate is too rapid, causing instability at the solid-liquid interface and disrupting the continuity of the single crystal. Therefore, this application controls the descent speed of the heating container within the aforementioned range, significantly increasing the speed of copper single crystal preparation compared to the Czochralski method, thereby improving the growth rate of large-size copper single crystals and ultimately increasing the preparation efficiency. Furthermore, this application requires no additional additives, thus reducing costs. By introducing an inert gas after vacuuming, the melting process occurs under positive pressure, which improves the purity of the copper melt and consequently, the purity of the copper single crystal. In summary, the preparation method of this application has advantages such as low cost, high efficiency, and the ability to obtain large-size copper single crystals.

[0026] In one embodiment of this application, in step S1 above, the cone angle of the cone bottom is 50~100°; the inner diameter of the heating container is 75~150mm.

[0027] Preferably controlling the cone angle at the bottom of the cone within the above range helps to form a stable heat flow and solute diffusion field in the early stage of solidification, guiding the melt to nucleate at a single point along the central axis and extend in a directional manner, thereby reducing lateral dendrite germination and polycrystalline competitive growth. This angle range makes the curvature of the solid-liquid interface moderate, reducing both local undercooling and heterogeneous nucleation caused by small cone angles and interface diffusion disorder caused by large cone angles, achieving single crystal growth with highly consistent orientation

[111] . Preferably controlling the inner diameter of the heating container within the above range helps to adapt to the heating furnace while obtaining copper single crystals with a diameter of 75~150mm.

[0028] In one embodiment of this application, in step S1 above, the heating container is a crucible, the material of the crucible is graphite or quartz, and the purity of the crucible is 99.99~99.9999%.

[0029] Using a crucible of the aforementioned material and purity in the preferred heating vessel helps reduce the dissolution of impurities, thereby reducing the impact of impurities on the copper melt, and further reducing heterogeneous nucleation and grain boundary defects.

[0030] In one embodiment of this application, in step S1 above, the purity of elemental copper is 99.99~99.9999%.

[0031] Preferred control of the purity of elemental copper within the above range helps to reduce the content of oxygen, sulfur, phosphorus, nitrogen and metallic impurities, thereby reducing impurity segregation and heterogeneous nucleation during the high-temperature melting stage, and thus keeping the solidification interface stable and allowing single crystals to grow preferentially along

[111] .

[0032] In one embodiment of this application, in step S1 above, after evacuating to 0.1~500Pa, an inert gas with a pressure of 100000~115000Pa is introduced, and this process is repeated three or more times; and / or, the inert gas is argon.

[0033] After placing elemental copper in a heating container, it is placed in a heating furnace. The heating furnace is evacuated to 0.1~500 Pa and then an inert gas with a pressure within the above range is introduced. This process is repeated more than three times to help remove residual oxygen, water vapor and organic volatiles in the heating container and furnace cavity, thereby reducing their reaction with molten copper at high temperature to form non-metallic inclusions or porosity defects. If only a single evacuation is performed, residual impurities may still induce heterogeneous nucleation, leading to an increase in grain boundaries and orientation disorder. Repeating the evacuation operation more than three times can keep the residual oxygen content in the system stable below 1 ppm, thereby improving the purity of the melt and providing a clean environment for the pollution-free growth of single crystals. It is preferable to introduce slightly positive pressure argon gas, which helps to isolate air and reduce oxidation, thereby promoting the preferred growth of

[111] crystal orientation. The heating furnace is preferably a vacuum high-temperature descent furnace.

[0034] In one embodiment of this application, in step S1 above, the melting holding temperature is 1190~1250℃, and the melting holding time is 1~5h.

[0035] The power is turned on for heating, and the elemental copper in the heating container is melted. This melt is then held at the aforementioned temperature and time to obtain a copper molten body. If the holding temperature is too low, unmelted particles will remain in the melt, easily leading to heterogeneous nucleation and disrupting the continuity of the single crystal. If the holding temperature is too high, carbon and oxygen in the heating container will dissolve more readily, increasing the risk of impurity contamination and inducing the precipitation of grain boundary oxides. If the holding time is too short, impurities will not float sufficiently, and gas inclusions will remain. If the holding time is too long, it not only increases energy consumption but may also cause abnormal crystal growth or crucible structure deterioration due to prolonged high temperatures. Therefore, it is preferable to control the holding temperature and time within the aforementioned ranges to ensure complete melting of the copper raw material, which is beneficial for subsequent crystal growth.

[0036] In one embodiment of this application, in step S2 above, the descent speed is 2~5 mm / h, the descent time is 60~100h, and the temperature during the descent process is 1200~1220℃.

[0037] Precisely controlling the descent rate, time, and temperature within the aforementioned range helps stabilize the solid-liquid interface morphology, rationally control crystallization undercooling and growth stress, thereby reducing polycrystalline, twinned, dislocation, and cracking defects, ensuring stable single-crystal orientation and uniform composition, and further improving the integrity of single crystals, product consistency, and finished product yield.

[0038] In one embodiment of this application, the temperature difference along the axial direction of the heating container during the descent is ≤10°C.

[0039] Ideally, the temperature difference along the axial direction of the heating container during the descent process should be within the aforementioned range. This helps to form a stable heat flow at the solid-liquid interface, which is beneficial for the continuous growth of copper single crystals in a planar solidification mode.

[0040] In another typical embodiment of this application, a copper single crystal is provided, which is prepared by the preparation method described above.

[0041] The copper single crystals obtained by the above preparation method can achieve large size, highly uniform crystal orientation, and high purity.

[0042] In one embodiment of this application, the diameter of the copper single crystal is 75~150mm, and the purity of the copper single crystal is 99.99~99.9999%.

[0043] Preferentially controlling the diameter and purity of copper single crystals within the above-mentioned range helps to achieve synergistic optimization of large size and high purity, thereby better meeting the requirements of single crystal volume and current-carrying cross section for high-power devices and other scenarios.

[0044] The crystal orientation of copper single crystal is mainly (111), and the area ratio of Cu (111) plane is ≥90%. The crystal growth rate is 2~10 mm / h.

[0045] The beneficial effects of this application will be further illustrated below with reference to the embodiments.

[0046] Example 1

[0047] 99.999% pure elemental copper is placed in a graphite crucible heating container with a purity of 99.999% and an inner diameter of 76 mm. Its structure is as follows: Figure 1 As shown, the graphite crucible has an inverted conical bottom with a cone angle of 60°, and the opening of the crucible faces upward, opposite to the downward direction.

[0048] Place the crucible containing elemental copper into a vacuum high-temperature lowering furnace, evacuate the furnace to a vacuum level of 200 Pa, then fill it with argon gas to make the furnace pressure 105000 Pa. Repeat this step 5 times.

[0049] The power supply is turned on to heat the crucible, and the elemental copper in the crucible is melted. The mixture is then kept at 1200℃ for 4 hours to obtain copper melt.

[0050] Turn on the crucible lowering button to lower the crucible at a constant speed of 3 mm / h at 1200℃ for 80 hours. During the descent, the temperature difference along the axial direction of the crucible is 5℃. Crystal growth is carried out to obtain a large copper single crystal with a diameter of 76 mm.

[0051] Example 2

[0052] The difference from Example 1 is that the raw material elemental copper with a purity of 99.9999% is placed in a graphite crucible heating container with a purity of 99.9999% and an inner diameter of 80mm. The graphite crucible has an inverted conical bottom with a cone angle of 50°, and the opening of the crucible faces upward, opposite to the downward direction.

[0053] Place the crucible containing elemental copper into a vacuum high-temperature lowering furnace, evacuate the furnace to a vacuum level of 1 Pa, then fill it with argon gas to make the furnace pressure 100,000 Pa. Repeat this step 5 times.

[0054] The power supply is turned on to heat the crucible, and the elemental copper in the crucible is melted. The mixture is then kept at 1200℃ for 5 hours to obtain copper melt.

[0055] Turn on the crucible lowering button to lower the crucible at a constant speed of 2 mm / h at 1210℃ for 100 hours. During the descent, the temperature difference along the axial direction of the crucible is 10℃, and crystal growth is carried out to obtain a large copper single crystal with a diameter of 80 mm.

[0056] Example 3

[0057] The difference from Example 1 is that the raw material elemental copper with a purity of 99.99% is placed in a graphite crucible heating container with a purity of 99.99% and an inner diameter of 150mm. The graphite crucible has an inverted conical bottom with a cone angle of 90°, and the opening of the crucible faces upward, opposite to the downward direction.

[0058] Place the crucible containing elemental copper into a vacuum high-temperature lowering furnace, evacuate the furnace to a vacuum level of 500 Pa, then fill it with argon gas to make the furnace pressure 105000 Pa. Repeat this step 5 times.

[0059] The power is turned on to heat the crucible, and the elemental copper in the crucible is melted. The mixture is then kept at 1200℃ for 2 hours to obtain copper melt.

[0060] Turn on the crucible lowering button and lower the crucible at a constant speed of 8 mm / h at 1220℃ for 65 hours. During the descent, the temperature difference along the axial direction of the crucible is 1℃. Crystal growth is carried out to obtain a large copper single crystal with a diameter of 150 mm.

[0061] Example 4

[0062] The difference from Example 1 is that the crucible was lowered at a constant speed of 5 mm / h at 1220°C for 100 hours, and the temperature difference along the axial direction of the crucible was 10°C during the descent to grow a large copper single crystal.

[0063] Example 5

[0064] The difference from Example 1 is that the crucible was lowered at a constant speed of 10 mm / h at 1240°C for 50 hours, and the temperature difference along the axial direction of the crucible was 15°C during the descent to grow a large copper single crystal.

[0065] Example 6

[0066] The difference from Example 1 is that the cone angle at the bottom of the cone is 100°, which ultimately yields a large-size copper single crystal.

[0067] Example 7

[0068] The difference from Example 1 is that the cone angle at the bottom of the cone is 40°, which ultimately yields a large-size copper single crystal.

[0069] Example 8

[0070] The difference from Example 1 is that the crucible containing elemental copper is placed in a vacuum high-temperature lowering furnace, and after the vacuum degree inside the furnace reaches 300 Pa, argon gas is introduced to make the pressure inside the furnace 115000 Pa. This step is repeated 5 times to finally obtain a large-size copper single crystal.

[0071] Example 9

[0072] The difference from Example 1 is that the crucible containing elemental copper is placed in a vacuum high-temperature lowering furnace, and after the vacuum degree inside the furnace reaches 600 Pa, argon gas is introduced to make the pressure inside the furnace 118000 Pa. This step is not repeated, and finally large-size copper single crystals are obtained.

[0073] Comparative Example 1

[0074] The difference from Example 1 is that the crucible containing elemental copper is placed in a vacuum high-temperature lowering furnace, and a vacuum is drawn to achieve a vacuum level of 1×10⁻⁶. -3 Pa, the crucible cone angle is 30°, and the diameter is 30mm. The crucible is lowered at 1150℃ at a rate of 1.0mm / h for 120h to obtain single crystal copper.

[0075] Comparative Example 2

[0076] The difference from Example 1 is that the crucible was lowered at a constant speed of 1 mm / h for 120 h to grow crystals and obtain large-size copper single crystals.

[0077] Comparative Example 3

[0078] The difference from Example 1 is that the crucible was lowered at a constant speed of 12 mm / h for 50 h to grow crystals and obtain large-size copper single crystals.

[0079] Test method:

[0080] Purity testing of copper single crystals: Tested according to GDMS.

[0081] Area ratio test of Cu(111) plane of copper single crystal: Tested according to EBSD.

[0082] Macroscopic testing of crystal orientation: Tested using metallographic etching method.

[0083] The test results are shown in Table 1.

[0084] Table 1

[0085]

[0086] As can be seen from the above, the single crystal size of Comparative Example 1 is smaller, requiring a higher vacuum level. The descent rate of Comparative Example 2 is too slow, resulting in a decrease in the purity of the copper single crystal, a decrease in the proportion of (111) crystal plane orientation, and the presence of obvious grain boundaries from the edge to the center. The descent rate of Comparative Example 3 is too fast, resulting in a slight decrease in the purity of the single crystal, a significant decrease in the proportion of (111) crystal plane, and the presence of obvious grain boundaries from the edge to the center. In contrast, the copper single crystal prepared in Example 1 has no grain boundaries after etching.

[0087] in, Figure 2 This is the X-ray diffraction (XRD) pattern of the copper single crystal in Example 1. Figure 2As can be seen from this, the crystal growth direction of copper single crystal is (111).

[0088] Figure 3 This is the electron backscattering (EBSD) pattern of the copper single crystal in Example 1. Figure 3 As can be seen from the image, 001, 101 and 111 represent crystal orientations. According to this color comparison card, the surface crystal orientation of copper single crystals is Cu (111).

[0089] As can be seen from the above description, the embodiments of the present invention achieve the following technical effects:

[0090] This application achieves the preparation of large-size copper single crystals by lowering the heating container and controlling its size within the aforementioned range. This not only effectively overcomes the limitation of hot casting methods where copper single crystal diameters cannot exceed 10mm, but also overcomes the problem of single crystal detachment due to overload during the Czochralski method for preparing large-size copper single crystals. Using a heating container with a conical bottom to hold the raw material elemental copper allows for single-point nucleation at the tip during the descent. The conical geometry suppresses impurities and stabilizes the solid-liquid interface, significantly improving the integrity and yield of the single crystal. If the descent speed is too slow, the solidification rate is too slow, causing the melt to remain in the high-temperature zone for an extended period, leading to impurity accumulation and insufficient supercooling. This results in excessively long high-temperature residence time for the crystal, increasing thermal stress and potentially causing polycrystalline or twinned crystals. If the descent speed is too fast, the cooling rate is too rapid, causing instability at the solid-liquid interface and disrupting the continuity of the single crystal. Therefore, this application controls the descent speed of the heating container within the aforementioned range, significantly increasing the speed of copper single crystal preparation compared to the Czochralski method, thereby improving the growth rate of large-size copper single crystals and ultimately increasing the preparation efficiency. Furthermore, this application requires no additional additives, thus reducing costs. By introducing an inert gas after vacuuming, the melting process occurs under positive pressure, which improves the purity of the copper melt and consequently, the purity of the copper single crystal. In summary, the preparation method of this application has advantages such as low cost, high efficiency, and the ability to obtain large-size copper single crystals.

[0091] The above are merely embodiments of the present invention and are not intended to limit the invention. Those skilled in the art will recognize that the present invention can have various modifications and variations. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing copper single crystals, characterized in that, The preparation method includes: Step S1: After placing elemental copper in a heating container, it is placed in a heating furnace. After evacuation, inert gas is introduced to melt the elemental copper and obtain copper melt. Step S2: The copper melt is lowered at a speed of 2~10 mm / h to grow crystals and obtain copper single crystals; The heating container has a conical bottom, the opening direction of the conical bottom is opposite to the downward direction, and the inner diameter of the heating container is ≥75mm.

2. The preparation method according to claim 1, characterized in that, In step S1, the cone angle of the cone bottom is 50~100°; the inner diameter of the heating container is 75~150mm.

3. The preparation method according to claim 1, characterized in that, In step S1, the heating container is a crucible, the material of the crucible is graphite or quartz, and the purity of the crucible is 99.99~99.9999%.

4. The preparation method according to claim 1, characterized in that, In step S1, the purity of the elemental copper is 99.99~99.9999%.

5. The preparation method according to any one of claims 1 to 4, characterized in that, In step S1, after evacuating to 0.1~500Pa, the inert gas with a pressure of 100000~115000Pa is introduced, and this process is repeated more than three times; and / or, the inert gas is argon.

6. The preparation method according to any one of claims 1 to 4, characterized in that, In step S1, the melting temperature is 1190~1250℃ and the melting time is 1~5h.

7. The preparation method according to any one of claims 1 to 4, characterized in that, In step S2, the descent speed is 2~5 mm / h, the descent time is 60~100h, and the temperature during the descent process is 1200~1220℃.

8. The preparation method according to any one of claims 1 to 4, characterized in that, During the descent, the temperature difference along the axial direction of the heating container is ≤10℃.

9. A copper single crystal, characterized in that, The copper single crystal is prepared by the preparation method according to any one of claims 1 to 8.

10. The copper single crystal according to claim 9, characterized in that, The copper single crystal has a diameter of 75~150mm and a purity of 99.99~99.9999%.

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