Method for reducing particulate matters in high-purity metal material

Abstract

The invention provides a method for reducing particulate matters in a high-purity metal material. The method comprises the following steps: (1) placing a plurality of metal sheets in a partitioned heating device to form a stack; wherein the zoning heating device comprises a first temperature zone and a second temperature zone which are sequentially distributed from top to bottom; one part of the stacked body is located in the first temperature zone, and the other part of the stacked body is located in the second temperature zone; (2) the stacked body is sequentially subjected to first-section partition heating and second-section partition heating, and the high-purity metal material is obtained; wherein the target temperature of the first temperature zone is higher than the target temperature of the second temperature zone in the first section of zone heating process. According to the invention, the stacked body formed by the plurality of metal sheets is subjected to two-section partitioned heating, and in the process of one-section partitioned heating, melting starts to occur from the upper part of the stacked body, so that the probability that the metal sheets slide down when being melted can be reduced, and particulate matters in high-purity metal materials are reduced.

Description

Technical Field

[0001] The invention belongs to the field of semiconductor technology and relates to a method for reducing particles in high-purity metal materials. Background Art

[0002] Metal targets are consumables for chip manufacturing. + When the target is bombarded, metal atoms will fall onto the wafer, thus forming a very thin metal layer. Metal targets are usually made of high-purity metal materials, and particles of other components are not allowed in high-purity metal materials. Otherwise, during the target sputtering process, these particles will fall directly onto the wafer to form particles. Particles refer to abnormal particles that fall onto the wafer, which can cause chip circuit short circuits, etc.

[0003] However, existing high-purity metal materials often contain granular substances of other components, such as C particles, Mg x O y Particles or Al x O y Particles, etc., some of which come from the inner wall of the melting crucible. When preparing high-purity metal materials, the metal sheets need to be molten. At a temperature of 1250-1550°C, the bottom of the stacked metal sheets will melt first. At this time, the metal sheets on the top are very likely to slide down. The sliding metal sheets will rub against the inner wall of the crucible, thereby scraping off particles and mixing them into the high-purity metal melt, thereby increasing the particles in the high-purity metal material.

[0004] Therefore, there is an urgent need to provide a solution that can reduce the probability of metal sheets slipping when they are melted, reduce the generation of scraped particles, and thus reduce the particles in high-purity metal materials. Summary of the invention

[0005] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a method for reducing particulate matter in high-purity metal materials. The present invention performs two-stage zone heating on a stack formed by multiple metal sheets so that the stack is completely melted. During the process of zone heating, since the target temperature of the first temperature zone is higher than the target temperature of the second temperature zone, a part of the stack located in the first temperature zone is melted, while another part located in the second temperature zone is not melted, that is, the melting starts from the upper part of the stack in the present invention, which can reduce the probability of the metal sheet sliding off when it melts, reduce the generation of scraped-off particles, and thus reduce the particulate matter in the high-purity metal material.

[0006] To achieve this object, the present invention adopts the following technical solutions:

[0007] In a first aspect, the present invention provides a method for reducing particulate matter in a high-purity metal material, the method comprising:

[0008] (1) Placing a plurality of metal sheets in a zoned heating device to form a stack; wherein the zoned heating device comprises a first temperature zone and a second temperature zone sequentially distributed from top to bottom; a portion of the stack is located in the first temperature zone, and another portion is located in the second temperature zone.

[0009] (2) The stacked body is subjected to first-stage zone heating and second-stage zone heating in sequence to obtain a high-purity metal material; wherein, during the first-stage zone heating, the target temperature of the first temperature zone is greater than the target temperature of the second temperature zone.

[0010] It should be noted that (1) the "multiple" mentioned above means at least 2, such as 2, 5, 10, 20, 50 or 100, but is not limited to the listed values. Other values ​​not listed in the numerical range are also applicable. (2) The "high purity" in the high-purity metal material refers to a purity ≥ 5N.

[0011] The present invention provides a method for reducing particulate matter in high-purity metal materials, wherein a stack formed by multiple metal sheets is subjected to two-stage zone heating so that the stack is completely melted, wherein during one stage of zone heating, since the target temperature of the first temperature zone is higher than the target temperature of the second temperature zone, a part of the stack located in the first temperature zone is melted, while another part located in the second temperature zone is not melted, that is, in the present invention, melting starts from the upper part of the stack, which can reduce the probability of metal sheets sliding off when melting, reduce the generation of scraped-off particles, and thus reduce the particulate matter in the high-purity metal material.

[0012] Preferably, the metal sheet comprises a copper sheet.

[0013] Preferably, the purity of the metal sheet is ≥5N, for example, it can be 5N, 6N or 7N, etc., but it is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0014] Preferably, the zoned heating device comprises a crucible for containing a plurality of metal sheets, and the outer side wall of the crucible is wound with a first heating wire and a second heating wire in sequence from top to bottom, thereby dividing the crucible into a first temperature zone and a second temperature zone.

[0015] It should be noted that the first heating wire and the second heating wire are independently controlled.

[0016] In the present invention, the temperature of the first temperature zone is regulated by adjusting the temperature of the first heating wire; and the temperature of the second temperature zone is regulated by adjusting the temperature of the second heating wire.

[0017] Preferably, the first heating wire includes at least 2 turns of heating wire arranged from top to bottom, for example, it can be 2 turns, 3 turns, 4 turns, 5 turns, 8 turns, 10 turns or 15 turns, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0018] Preferably, the second heating wire includes at least 2 turns of heating wire arranged from top to bottom, for example, it can be 2 turns, 3 turns, 4 turns, 5 turns, 8 turns, 10 turns or 15 turns, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0019] Preferably, a part of the stack located in the first temperature zone is recorded as a first sub-stack, and the other part located in the second temperature zone is recorded as a second sub-stack, and the height ratio of the first sub-stack to the second sub-stack is (1-3):(1-3), wherein the selection range (1-3) of the first sub-stack can be, for example, 1, 2 or 3, and the selection range (1-3) of the second sub-stack can be, for example, 1, 2 or 3, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0020] Preferably, in the process of said zoned heating, the target temperature of the first temperature zone is 1250-1400°C, for example, it can be 1250°C, 1260°C, 1280°C, 1300°C, 1320°C, 1350°C, 1380°C or 1400°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0021] In the present invention, when performing zone heating, the first temperature zone is heated to the target temperature and then kept at the same temperature for heating. When the target temperature of the first temperature zone meets 1250-1400° C., the stacked body in the first temperature zone can be melted.

[0022] Preferably, in the process of the zoned heating, the target temperature of the second temperature zone is 1000-1200°C, for example, it can be 1000°C, 1020°C, 1050°C, 1080°C, 1100°C, 1120°C, 1150°C, 1180°C or 1200°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0023] In the present invention, when performing a zone heating, the second temperature zone is heated to the target temperature and then kept at the same temperature for heating. When the target temperature of the second temperature zone meets 1000-1200° C., it can be ensured that the stacked body in the second temperature zone does not melt.

[0024] Preferably, during a section of zoned heating, the temperatures of the various coils of heating wire in the first heating wire remain consistent; and the temperatures of the various coils of heating wire in the second heating wire remain consistent.

[0025] Preferably, the specific process of one-stage zone heating is: the first temperature zone is heated to 1250-1400° C. and kept warm, while the second temperature zone is heated to 1000-1200° C. and kept warm.

[0026] Preferably, the stack is heated in one section until the top of the stack begins to melt, and then heated in two sections.

[0027] It should be noted that the top of the stack refers to the uppermost part of the stack, which is located in the first temperature zone.

[0028] Preferably, in the process of the two-stage zone heating, the first temperature zone is a constant temperature zone, and the temperature of the constant temperature zone is 1250-1400°C, for example, it can be 1250°C, 1260°C, 1280°C, 1300°C, 1320°C, 1350°C, 1380°C or 1400°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0029] Preferably, the temperature of the constant temperature zone is the same as the target temperature of the first temperature zone during one-stage zone heating.

[0030] Preferably, during the two-stage zone heating process, the temperatures of the various coils of heating wire in the first heating wire remain consistent.

[0031] Preferably, during the two-stage zone heating, the second temperature zone is heated in a manner that: the second heating wire is heated circle by circle along a direction from top to bottom.

[0032] It should be noted that (1) during the two-stage zone heating process, the second heating wire is heated with the target temperature of the first zone heating as the initial temperature. (2) Each circle of metal wire in the second heating wire is independently controlled. (3) The second heating wire is heated circle by circle from top to bottom, specifically: the first circle of heating wire at the top of the second heating wire is heated to the target temperature first, and then the second circle of heating wire is heated until it reaches the target temperature, and so on, until the last circle of heating wire at the bottom is heated to the target temperature; after each circle of heating wire is heated to the target temperature, it enters the insulation state.

[0033] When the present invention performs two-stage zone heating, the first temperature zone is set as a constant temperature zone, and the second heating wire is heated circle by circle along the direction from top to bottom, so that the stack formed by multiple metal sheets can be slowly melted from top to bottom, which can further reduce the probability of the metal sheets slipping when melting, further reduce the generation of scraped particles, and thus further reduce the particles in the high-purity metal material.

[0034] The present invention, through the coordinated cooperation of the first-stage zone heating and the second-stage zone heating, minimizes the probability of metal sheets slipping when they are melted, and can simply and efficiently reduce the risk of particles introduced during the melting process, thereby effectively reducing the particles in the high-purity metal material.

[0035] Preferably, during the two-stage zone heating process, the time interval for heating the second heating wire circle by circle is 5-10 minutes, for example, it can be 5 minutes, 6 minutes, 7 minutes, 8 minutes or 10 minutes, etc., but it is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0036] In the present invention, the time interval of heating up the heating wires one by one refers to the time difference between the moment when one circle of heating wires is heated up to the target temperature and the moment when the next circle of heating wires starts to heat up.

[0037] Preferably, during the two-stage zoned heating process, the heating rate of each coil of the second heating wire is the same.

[0038] Preferably, in the process of the two-stage zoned heating, the heating target temperature of each circle of the second heating wire is independently 1250-1400°C, for example, it can be 1250°C, 1260°C, 1280°C, 1300°C, 1320°C, 1350°C, 1380°C or 1400°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0039] Preferably, during the two-stage zoned heating process, the heating target temperature of each coil of the second heating wire is the same.

[0040] Preferably, the specific process of two-stage zone heating is: set the first temperature zone as a constant temperature zone, and heat at a constant temperature; set the second heating wire to heat up circle by circle from top to bottom, and enter the insulation state after heating to the target temperature, and perform insulation heating at the target temperature until multiple metal sheets are completely melted.

[0041] As a preferred technical solution of the present invention, the method comprises the following steps:

[0042] (I) A zoned heating device is provided, the zoned heating device comprising a crucible, the outer wall of the crucible is wound with a first heating wire and a second heating wire in sequence from top to bottom, thereby dividing the crucible into a first temperature zone and a second temperature zone in sequence from top to bottom; the first heating wire comprises at least two turns of heating wire arranged in sequence from top to bottom; the second heating wire comprises at least two turns of heating wire arranged in sequence from top to bottom.

[0043] (II) placing a plurality of metal sheets in a crucible to form a stack; wherein the metal sheets are copper sheets, and the purity of the copper sheets is ≥5N; a portion of the stack is located in a first temperature zone, and another portion is located in a second temperature zone.

[0044] (III) adjusting the first heating wire to raise the temperature of the first temperature zone to 1250-1400°C and keep it warm, and at the same time adjusting the second heating wire to raise the temperature of the second temperature zone to 1000-1200°C and keep it warm, thereby performing one-stage zone heating on the stacked body; after the top of the stacked body begins to melt, the temperature of the first temperature zone is maintained unchanged, and the second heating wire is set to raise the temperature to 1250-1400°C in a circle from top to bottom and keep it warm, so as to perform two-stage zone heating; after multiple metal sheets are completely melted, a high-purity metal material is obtained.

[0045] The numerical range described in the present invention not only includes the point values ​​listed above, but also includes any point values ​​between the above numerical ranges that are not listed. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0046] Compared with the prior art, the present invention has the following beneficial effects:

[0047] The present invention provides a method for reducing particulate matter in a high-purity metal material, wherein a stack formed by a plurality of metal sheets is heated in two sections so that the stack is completely melted, wherein during the heating process of one section, since the target temperature of the first temperature zone is higher than the target temperature of the second temperature zone, a part of the stack located in the first temperature zone is melted, while another part located in the second temperature zone is not melted, that is, the melting starts from the upper part of the stack in the present invention, which can reduce the probability of the metal sheet sliding off when it melts, reduce the generation of scraped-off particulate matter, and thus reduce the particulate matter in the high-purity metal material. The high-purity metal material obtained by the present invention is used to prepare a target material, which can reduce the probability of the target material Praticle. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 A schematic diagram of the structure of a zoned heating device provided in Example 1 of the present invention;

[0049] Figure 2 This is a schematic structural diagram of the zoned heating device provided in Comparative Example 1 of the present invention.

[0050] Among them, 1-crucible; 2-first heating wire; 3-second heating wire. DETAILED DESCRIPTION

[0051] The technical solution of the present invention is further illustrated below through specific implementation methods.

[0052] Example 1

[0053] This embodiment provides a method for reducing particulate matter in a high-purity metal material, comprising the following steps:

[0054] (1) Provide zone heating devices, such as Figure 1 As shown, the zoned heating device includes a crucible 1, and the outer wall of the crucible 1 is wound with a first heating wire 2 and a second heating wire 3 in sequence from top to bottom, and the first heating wire 2 and the second heating wire 3 are independently controlled, so that the crucible 1 is divided into a first temperature zone and a second temperature zone distributed in sequence from top to bottom; the first heating wire 2 includes two circles of heating wire arranged in sequence from top to bottom; the second heating wire 3 includes three circles of heating wire arranged in sequence from top to bottom, and each circle of heating wire is independently controlled.

[0055] (2) 20 copper sheets with a purity of 6N are placed in a crucible 1 to form a stack; a portion of the stack is located in the first temperature zone, and the other portion is located in the second temperature zone. The portion of the stack located in the first temperature zone is recorded as a first sub-stack, and the other portion located in the second temperature zone is recorded as a second sub-stack. The height ratio of the first sub-stack to the second sub-stack is 2:3.

[0056] (3) adjusting the first heating wire 2, wherein the temperature of each circle of the heating wire is kept consistent, so that the first temperature zone is heated to 1300°C at a heating rate of 10°C / min and kept warm, and at the same time adjusting the second heating wire 3, wherein the temperature of each circle of the heating wire is kept consistent, so that the second temperature zone is heated to 1050°C at a heating rate of 10°C / min and kept warm, thereby performing one-stage zone heating on the stacked body; after the top of the stacked body begins to melt as observed by the naked eye, the temperature of the first temperature zone is maintained unchanged, and the second heating wire 3 is set to heat to 1300°C at a heating rate of 10°C / min from top to bottom and keep warm, so as to perform two-stage zone heating; after all the copper sheets are completely melted, cooling is performed to obtain a high-purity metal material with a purity of 6N (gas content ≤1ppm).

[0057] Example 2

[0058] This embodiment provides a method for reducing particulate matter in a high-purity metal material, comprising the following steps:

[0059] (1) A zoned heating device is provided, the zoned heating device comprising a crucible, the outer wall of the crucible is wound with a first heating wire and a second heating wire in sequence from top to bottom, the first heating wire and the second heating wire are independently controlled, so as to divide the crucible into a first temperature zone and a second temperature zone distributed in sequence from top to bottom; the first heating wire comprises two turns of heating wire arranged in sequence from top to bottom; the second heating wire comprises three turns of heating wire arranged in sequence from top to bottom, wherein each turn of heating wire is independently controlled.

[0060] (2) 20 copper sheets with a purity of 6N are placed in a crucible to form a stack; a portion of the stack is located in a first temperature zone, and the other portion is located in a second temperature zone. The portion of the stack located in the first temperature zone is recorded as a first sub-stack, and the other portion located in the second temperature zone is recorded as a second sub-stack. The height ratio of the first sub-stack to the second sub-stack is 2:3.

[0061] (3) adjusting the first heating wire, wherein the temperature of each circle of the heating wire is kept consistent, so that the first temperature zone is heated to 1350°C at a heating rate of 10°C / min and kept warm, and at the same time adjusting the second heating wire, wherein the temperature of each circle of the heating wire is kept consistent, so that the second temperature zone is heated to 1150°C at a heating rate of 10°C / min and kept warm, thereby performing one-stage zone heating on the stacked body; after the top of the stacked body begins to melt as observed by the naked eye, the temperature of the first temperature zone is maintained unchanged, and the second heating wire is set to heat up to 1350°C at a heating rate of 10°C / min from top to bottom and keep warm, so as to perform two-stage zone heating; after all the copper sheets are completely melted, cooling is performed to obtain a high-purity metal material with a purity of 6N (gas content ≤1ppm).

[0062] Example 3

[0063] The difference between this embodiment and embodiment 1 is that in step (3), during the two-stage zone heating process, each circle of the second heating wire is set to heat up to 1300° C. at a heating rate of 10° C. / min at the same time.

[0064] The remaining conditions and parameters are the same as those in Example 1.

[0065] Example 4

[0066] The difference between this embodiment and embodiment 1 is that in step (3), during a zone heating process, the target temperature of the second temperature zone is 950°C.

[0067] The remaining conditions and parameters are the same as those in Example 1.

[0068] Example 5

[0069] The difference between this embodiment and embodiment 1 is that in step (3), during a zone heating process, the target temperature of the second temperature zone is 1250°C.

[0070] The remaining conditions and parameters are the same as those in Example 1.

[0071] Comparative Example 1

[0072] This comparative example provides a method for preparing a high-purity metal material, comprising the following steps:

[0073] (1) Provide a heating device, such as Figure 2As shown, the heating device comprises a crucible 1, and the outer wall of the crucible 1 is wound with 5 turns of heating wire.

[0074] (2) 20 copper sheets with a purity of 6N are placed in a crucible 1 to form a stack.

[0075] (3) Adjusting 5 circles of heating wires, wherein the temperature of each circle of heating wires is kept consistent, so that the temperature inside the crucible 1 is raised to 1300° C. at a heating rate of 10° C. / min and kept warm, wherein the entire stack is in the same temperature zone, and after being kept warm until all the copper sheets are completely melted, cooling is performed to obtain a high-purity metal material.

[0076] Test: The number of particles with a particle size of 0.5 μm or more in the high-purity metal materials obtained in the above embodiments and comparative examples was detected by a liquid particle analyzer (LPC). The results are shown in Table 1.

[0077] Table 1

[0078] Number of particles larger than 0.5μm (particles) Example 1 2790 Example 2 3316 Example 3 11673 Example 4 3859 Example 5 10557 Comparative Example 1 13411

[0079] analyze:

[0080] It can be seen from Examples 1-2 that the present invention performs two-stage zone heating on a stack formed by multiple metal sheets so that the stack is completely melted; wherein, during the process of one-stage zone heating, the target temperature of the first temperature zone is set higher than the target temperature of the second temperature zone, so that melting starts from the top of the stack, which can reduce the probability of the copper sheet slipping and reduce the generation of rubbed-off particles, thereby reducing the particulate matter in the high-purity metal material; and when the present invention performs two-stage zone heating, the first temperature zone is maintained unchanged, and the second heating wire is set to heat up circle by circle from top to bottom, so that the copper sheet stack can be slowly melted from top to bottom, which can further reduce the probability of the copper sheet slipping and further reduce the generation of rubbed-off particles, thereby further reducing the particulate matter in the high-purity metal material; in summary, the number of particles in the high-purity copper metal material obtained by the method of the present invention is relatively low.

[0081] It can be seen from Examples 1 and 3 that during the two-stage zone heating process, if each circle of the second heating wire is heated to the target temperature at the same time, the second sub-stack located in the second temperature zone will melt as a whole, and the melted copper sheet at the bottom will increase the risk of the upper copper sheet sliding off, thereby increasing the number of particles of the high-purity metal material finally obtained.

[0082] It can be seen from Example 1 and Examples 4-5 that if the heating target temperature of the second temperature zone is low during the first-stage zone heating, the heating time required for the second-stage zone heating is long, which increases the risk of particles on the inner wall of the crucible falling off, resulting in an increase in the number of particles of the high-purity metal material. If the heating target temperature of the second temperature zone is high during the first-stage zone heating, the second sub-stack located in the second temperature zone may melt, thereby increasing the risk of the copper sheet sliding off, causing the copper sheet to fall and scrape the inner wall of the crucible, resulting in an increase in the number of particles of the high-purity metal material finally obtained.

[0083] It can be seen from Example 1 and Comparative Example 1 that when the entire stack formed by copper sheets is heated in the same temperature zone, the copper sheets at the bottom of the stack will also melt, causing the copper sheets above to slide off. After sliding off, the copper sheets rub against the inner wall of the crucible, thereby scraping off particles and mixing into the high-purity metal melt, thereby increasing the number of particles in the high-purity metal material finally obtained.

[0084] The above description is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention are within the protection scope and disclosure scope of the present invention.

Claims

1. A method for reducing particulate matter in high-purity metal materials, characterized in that: The method comprises: (1) placing a plurality of metal sheets in a zoned heating device to form a stack; wherein the zoned heating device comprises a first temperature zone and a second temperature zone sequentially arranged from top to bottom; a portion of the stack is located in the first temperature zone, and another portion is located in the second temperature zone; (2) The stacked body is subjected to first-stage zone heating and second-stage zone heating in sequence to obtain a high-purity metal material; wherein, during the first-stage zone heating, the target temperature of the first temperature zone is greater than the target temperature of the second temperature zone.

2. The method according to claim 1, characterized in that The metal sheet comprises a copper sheet; Preferably, the purity of the metal sheet is ≥5N.

3. The method according to claim 1 or 2, characterized in that: The zoned heating device comprises a crucible for holding a plurality of metal sheets, and the outer wall of the crucible is wound with a first heating wire and a second heating wire in sequence from top to bottom, thereby dividing the crucible into a first temperature zone and a second temperature zone.

4. The method according to claim 3, characterized in that The first heating wire comprises at least two coils of heating wire arranged sequentially from top to bottom; Preferably, the second heating wire comprises at least two turns of heating wire arranged sequentially from top to bottom.

5. The method according to any one of claims 1 to 4, characterized in that: During the one-stage zone heating process, the target temperature of the first temperature zone is 1250-1400°C.

6. The method according to any one of claims 1 to 5, characterized in that: During the one-stage zone heating process, the target temperature of the second temperature zone is 1000-1200°C.

7. The method according to any one of claims 1 to 6, characterized in that: The stack is heated in one section until the top of the stack begins to melt, and then heated in two sections.

8. The method according to any one of claims 1 to 7, characterized in that: In the process of the two-stage zone heating, the first temperature zone is a constant temperature zone, and the temperature of the constant temperature zone is 1250-1400°C.

9. The method according to any one of claims 3 to 8, characterized in that: In the process of the two-stage zone heating, the second temperature zone is heated in a manner that: the second heating wire is heated in a circle from top to bottom; Preferably, during the two-stage zoned heating process, the target temperature of each coil of the second heating wire is independently 1250-1400°C.

10. The method according to any one of claims 1 to 9, characterized in that: The method comprises the following steps: (I) providing a zoned heating device, the zoned heating device comprising a crucible, the outer wall of the crucible being wound with a first heating wire and a second heating wire in sequence from top to bottom, so as to divide the crucible into a first temperature zone and a second temperature zone in sequence from top to bottom; the first heating wire comprises at least two turns of heating wire arranged in sequence from top to bottom; the second heating wire comprises at least two turns of heating wire arranged in sequence from top to bottom; (II) placing a plurality of metal sheets in a crucible to form a stack; wherein the metal sheets are copper sheets, and the purity of the copper sheets is ≥5N; a portion of the stack is located in a first temperature zone, and another portion is located in a second temperature zone; (III) adjusting the first heating wire to raise the temperature of the first temperature zone to 1250-1400°C and keep it warm, and at the same time adjusting the second heating wire to raise the temperature of the second temperature zone to 1000-1200°C and keep it warm, thereby performing one-stage zone heating on the stacked body; after the top of the stacked body begins to melt, the temperature of the first temperature zone is maintained unchanged, and the second heating wire is set to raise the temperature to 1250-1400°C in a circle from top to bottom and keep it warm, so as to perform two-stage zone heating; after multiple metal sheets are completely melted, a high-purity metal material is obtained.

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