A method for reducing particulate matter in high-purity metal materials
By using a zoned heating device to heat high-purity metal materials in two stages, the problem of particulate matter generated during the melting process of metal sheets is solved, achieving efficient reduction of particulate matter and improving the quality of chip manufacturing.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- KONFOONG MATERIALS INTERNATIONAL CO LTD
- Filing Date
- 2024-10-10
- Publication Date
- 2026-05-26
AI Technical Summary
Existing high-purity metal materials contain particulate matter, especially when metal sheets slide down and rub against the inner wall of the crucible during the melting process, resulting in particle formation during chip manufacturing and affecting chip quality.
A zoned heating device is used to heat the stack of multiple metal sheets in two zones. The temperature of the first zone is higher than that of the second zone. Melting starts from the top of the stack. The temperature of the second zone is adjusted in turn to make the metal sheets melt slowly from top to bottom, reducing the probability of slippage.
It effectively reduces particulate matter in high-purity metal materials, lowers the risk of particle formation, and improves the reliability of chip manufacturing.
Smart Images
Figure CN119287323B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of semiconductor technology and relates to a method for reducing particulate matter in high-purity metal materials. Background Technology
[0002] Metal sputtering targets are consumables used in chip manufacturing, and are produced using Ar... + When a target is bombarded, metal atoms fall onto the wafer, creating a very thin metal layer. Metal targets are typically made of high-purity metal materials, which are not allowed to contain any other particles. Otherwise, during the sputtering process, these particles would fall directly onto the wafer, forming particles that can cause short circuits in the chip circuitry.
[0003] However, existing high-purity metal materials often contain other particulate substances, such as C particles and Mg particles. x O y Particles or Al x O y Particles, among other things, originate partly from the inner wall of the molten crucible. When preparing high-purity metal materials, the metal sheets need to be molten. At temperatures of 1250-1550℃, the bottom of the stacked metal sheets melts first. At this point, the metal sheets at the top are prone to slipping off. These slipping metal sheets rub against the inner wall of the crucible, causing particles to be rubbed off and mixed into the molten high-purity metal, thus increasing the particulate matter content 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 during melting, reduce the generation of rubbed particles, and thus reduce particulate matter in high-purity metal materials. Summary of the Invention
[0005] To address the shortcomings of existing technologies, the present invention aims to provide a method for reducing particulate matter in high-purity metal materials. The present invention involves heating a stack of multiple metal sheets in two separate sections, causing the stack to completely melt. During the heating process in one section, because the target temperature of the first temperature zone is higher than that of the second temperature zone, a portion of the stack located in the first temperature zone melts, while the portion located in the second temperature zone remains unmelted. In other words, melting in this invention begins from the top of the stack. This reduces the probability of the metal sheets slipping during melting, minimizing the generation of rubbed-off particles, thereby reducing particulate matter in the high-purity metal material.
[0006] To achieve this objective, the present invention adopts the following technical solution:
[0007] In a first aspect, the present invention provides a method for reducing particulate matter in high-purity metal materials, the method comprising:
[0008] (1) Multiple metal sheets are placed in a partitioned heating device to form a stack; wherein the partitioned heating device includes a first temperature zone and a second temperature zone distributed from top to bottom; a part of the stack is located in the first temperature zone and another part is located in the second temperature zone.
[0009] (2) The stacked body is subjected to a first-stage partition heating and a second-stage partition heating in sequence to obtain a high-purity metal material; wherein, during the first-stage partition heating process, 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) "multiple" refers to at least 2, such as 2, 5, 10, 20, 50 or 100, etc., but is not limited to the listed values. Other unlisted values within this range are also applicable. (2) "High purity" in the high purity metal material refers to a purity ≥ 5N.
[0011] This invention provides a method for reducing particulate matter in high-purity metal materials. The method involves heating a stack of multiple metal sheets in two separate sections until the stack is completely melted. During the heating process in one section, because the target temperature of the first temperature zone is higher than that of the second temperature zone, a portion of the stack located in the first temperature zone melts, while the portion located in the second temperature zone does not melt. In other words, melting begins from the top of the stack in this invention. This reduces the probability of the metal sheets slipping during melting, decreasing the generation of rubbed-off particles and thus reducing 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, but it is not limited to the listed values. Other unlisted values within this range are also applicable.
[0014] Preferably, the partitioned heating device includes a crucible for holding multiple metal sheets, and the outer wall of the crucible is wound with a first heating wire and a second heating wire 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 controlled independently.
[0016] In this invention, the temperature of the first temperature zone is controlled by adjusting the temperature of the first heating wire; and the temperature of the second temperature zone is controlled by adjusting the temperature of the second heating wire.
[0017] Preferably, the first heating wire includes at least two turns of heating wire arranged sequentially from top to bottom, such as 2 turns, 3 turns, 4 turns, 5 turns, 8 turns, 10 turns or 15 turns, etc., but is not limited to the listed values. Other unlisted values within this range are also applicable.
[0018] Preferably, the second heating wire includes at least two turns of heating wire arranged sequentially from top to bottom, such as 2 turns, 3 turns, 4 turns, 5 turns, 8 turns, 10 turns or 15 turns, etc., but is not limited to the listed values. Other unlisted values within this range are also applicable.
[0019] Preferably, a portion of the stack located within the first temperature zone is designated as the first sub-stack, and another portion located within the second temperature zone is designated as the second sub-stack. The height ratio of the first sub-stack to the second sub-stack is (1-3):(1-3). The selection range (1-3) for the first sub-stack can be, for example, 1, 2, or 3, and the selection range (1-3) for the second sub-stack can be, for example, 1, 2, or 3, but is not limited to the listed values. Other unlisted values within this range are also applicable.
[0020] Preferably, during the process of heating in one zone, the target temperature of the first temperature zone is 1250-1400℃, for example, it can be 1250℃, 1260℃, 1280℃, 1300℃, 1320℃, 1350℃, 1380℃ or 1400℃, etc., but it is not limited to the listed values. Other unlisted values within this range are also applicable.
[0021] In this invention, during a segmented heating process, the first temperature zone is heated to the target temperature and then kept at a constant temperature. When the target temperature of the first temperature zone is 1250-1400℃, the stacked material located in the first temperature zone can melt.
[0022] Preferably, during the heating process of the first zone, the target temperature of the second temperature zone is 1000-1200℃, such as 1000℃, 1020℃, 1050℃, 1080℃, 1100℃, 1120℃, 1150℃, 1180℃ or 1200℃, etc., but it is not limited to the listed values. Other unlisted values within this range are also applicable.
[0023] In this invention, during a phased heating process, the second temperature zone is heated to the target temperature and then kept at a constant temperature. When the target temperature of the second temperature zone is 1000-1200℃, it can be ensured that the stacked body located in the second temperature zone will not melt.
[0024] Preferably, during a segmented heating process, the temperature of each coil of heating wire in the first heating wire remains consistent; the temperature of each coil of heating wire in the second heating wire remains consistent.
[0025] Preferably, the specific process of a single-zone heating is as follows: the first temperature zone is heated to 1250-1400℃ and kept at that temperature, while the second temperature zone is heated to 1000-1200℃ and kept at that temperature.
[0026] Preferably, the stack is subjected to a first-stage zone heating until the top of the stack begins to melt, and then a second-stage zone heating is performed.
[0027] It should be noted that the top of the stack refers to the uppermost part of the stack, which is located within the first temperature zone.
[0028] Preferably, during the two-stage zone heating process, the first temperature zone is a constant temperature zone, and the temperature of the constant temperature zone is 1250-1400℃, for example, it can be 1250℃, 1260℃, 1280℃, 1300℃, 1320℃, 1350℃, 1380℃ or 1400℃, etc., but it is not limited to the listed values. Other unlisted values within this 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 a segmented heating process.
[0030] Preferably, during the two-stage zone heating process, the temperature of each coil of heating wire in the first heating wire remains consistent.
[0031] Preferably, during the two-stage zone heating process, the heating method of the second temperature zone includes: the second heating wire heating up in turns from top to bottom.
[0032] It should be noted that (1) during the two-stage heating process, the second heating wire is heated to the initial temperature of the target temperature during the first-stage heating. (2) Each coil of metal wire in the second heating wire is independently controlled. (3) The second heating wire is heated coil by coil from top to bottom: the first coil of heating wire at the top of the second heating wire is heated to the target temperature first, then the second coil of heating wire is heated until the target temperature is reached, and so on, until the last coil of heating wire at the bottom is heated to the target temperature; after each coil of heating wire is heated to the target temperature, it enters the heat preservation state.
[0033] In the two-stage zone heating process of this invention, the first temperature zone is set as a constant temperature zone, and the second heating wire is heated in circles from top to bottom. This allows the stack of multiple metal sheets to melt slowly from top to bottom, which can further reduce the probability of the metal sheets slipping when melting, further reduce the generation of rubbed particles, and thus further reduce the particulate matter in high-purity metal materials.
[0034] This invention, through the synergistic combination of single-stage and two-stage heating, minimizes the probability of metal sheets slipping during melting, thus simply and efficiently reducing the risk of particulate matter introduction during the melting process and effectively reducing particulate matter in high-purity metal materials.
[0035] Preferably, during the two-stage heating process, the time interval for the second heating wire to heat up in turns is 5-10 minutes, for example, it can be 5 minutes, 6 minutes, 7 minutes, 8 minutes or 10 minutes, but it is not limited to the listed values. Other unlisted values within this range are also applicable.
[0036] In this invention, the time interval for heating in each ring refers to the time difference between the moment when one ring of heating wire reaches the target temperature and the moment when the next ring of heating wire begins to heat up.
[0037] Preferably, during the two-stage heating process, the heating rate of each coil of the second heating wire is the same.
[0038] Preferably, during the two-stage zone heating process, the target temperature for each coil of the second heating wire is independently 1250-1400℃, for example, it can be 1250℃, 1260℃, 1280℃, 1300℃, 1320℃, 1350℃, 1380℃ or 1400℃, etc., but it is not limited to the listed values. Other unlisted values within this range are also applicable.
[0039] Preferably, during the two-stage heating process, the target temperature for each turn of the second heating wire is the same.
[0040] Preferably, the specific process of two-stage zone heating is as follows: the first temperature zone is set as a constant temperature zone and heated at a constant temperature; the second heating wire is set to heat up in circles from top to bottom, and after reaching the target temperature, it enters the heat preservation state and heats up at the target temperature until multiple metal sheets are completely melted.
[0041] As a preferred technical solution of the present invention, the method includes the following steps:
[0042] (I) A partitioned heating device is provided, the partitioned heating device includes a crucible, the outer wall of the crucible is wound with a first heating wire and a second heating wire from top to bottom, thereby dividing the crucible into a first temperature zone and a second temperature zone distributed from top to bottom; the first heating wire includes at least two turns of heating wire arranged from top to bottom; the second heating wire includes at least two turns of heating wire arranged from top to bottom.
[0043] (II) A plurality of metal sheets are placed in a crucible to form a stack; wherein the metal sheets are copper sheets with a purity ≥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) Adjust the first heating wire to raise the temperature of the first temperature zone to 1250-1400℃ and maintain the temperature, while simultaneously adjusting the second heating wire to raise the temperature of the second temperature zone to 1000-1200℃ and maintain the temperature, thereby performing a section heating of the stacked body; after the top of the stacked body begins to melt, maintain the temperature of the first temperature zone unchanged, and set the second heating wire to raise the temperature to 1250-1400℃ in a circle from top to bottom and maintain the temperature, so as to perform a two-stage section heating; after multiple metal sheets have completely melted, a high-purity metal material is obtained.
[0045] The numerical range described in this invention includes not only the point values listed above, but also any point values within the numerical ranges not listed above. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific point values included in the range.
[0046] Compared with the prior art, the beneficial effects of the present invention are as follows:
[0047] This invention provides a method for reducing particulate matter in high-purity metal materials. The method involves heating a stack of multiple metal sheets in two separate sections until the stack is completely melted. During the first section of heating, because the target temperature of the first temperature zone is higher than that of the second temperature zone, a portion of the stack within the first temperature zone melts, while the portion within the second temperature zone remains unmelted. In other words, melting begins from the top of the stack. This reduces the probability of the metal sheets slipping during melting, minimizing the generation of rubbed-off particles and thus reducing particulate matter in the high-purity metal material. Using the high-purity metal material obtained by this invention to prepare targets can reduce the probability of target particle formation. Attached Figure Description
[0048] Figure 1 This is a schematic diagram of the partitioned heating device provided in Embodiment 1 of the present invention;
[0049] Figure 2 This is a schematic diagram of the partitioned heating device provided in Comparative Example 1 of the present invention.
[0050] Wherein, 1-crucible; 2-first heating wire; 3-second heating wire. Detailed Implementation
[0051] The technical solution of the present invention will be further illustrated below through specific embodiments.
[0052] Example 1
[0053] This embodiment provides a method for reducing particulate matter in high-purity metal materials, including the following steps:
[0054] (1) Provide zoned heating devices, such as Figure 1 As shown, the partitioned heating device includes a crucible 1. The outer wall of the crucible 1 is wound with a first heating wire 2 and a second heating wire 3 from top to bottom. The first heating wire 2 and the second heating wire 3 are independently controlled, thereby dividing the crucible 1 into a first temperature zone and a second temperature zone distributed from top to bottom. The first heating wire 2 includes two coils of heating wire arranged from top to bottom. The second heating wire 3 includes three coils of heating wire arranged from top to bottom, wherein each coil of heating wire is independently controlled.
[0055] (2) Place 20 copper sheets with a purity of 6N in crucible 1 to form a stack; a part of the stack is located in the first temperature zone and another part is located in the second temperature zone. The part of the stack located in the first temperature zone is called the first sub-stack, and the other part located in the second temperature zone is called the second sub-stack. The height ratio of the first sub-stack and the second sub-stack is 2:3.
[0056] (3) Adjust the first heating wire 2, wherein the temperature of each coil 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 held at that temperature. At the same time, adjust the second heating wire 3, wherein the temperature of each coil 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 held at that temperature, thereby performing a first-stage partitioned heating of the stack. After the top of the stack is observed to begin to melt, keep the temperature of the first temperature zone constant, and set the second heating wire 3 to heat to 1300°C in turn from top to bottom at a heating rate of 10°C / min and hold at that temperature, so as to perform a second-stage partitioned heating. After all the copper sheets have completely melted, cool them 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 high-purity metal materials, including the following steps:
[0059] (1) A partitioned heating device is provided, the partitioned heating device includes a crucible, the outer wall of the crucible is wound with a first heating wire and a second heating wire from top to bottom, the first heating wire and the second heating wire are independently controlled, thereby dividing the crucible into a first temperature zone and a second temperature zone distributed from top to bottom; the first heating wire includes 2 coils of heating wire arranged from top to bottom; the second heating wire includes 3 coils of heating wire arranged from top to bottom, wherein each coil of heating wire is independently controlled.
[0060] (2) Place 20 copper sheets with a purity of 6N in a crucible to form a stack; a part of the stack is located in a first temperature zone and another part is located in a second temperature zone. The part of the stack located in the first temperature zone is called the first sub-stack, and the other part located in the second temperature zone is called the second sub-stack. The height ratio of the first sub-stack and the second sub-stack is 2:3.
[0061] (3) Adjust the first heating wire, wherein the temperature of each coil 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 held at that temperature. At the same time, adjust the second heating wire, wherein the temperature of each coil 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 held at that temperature, thereby performing a first-stage partitioned heating of the stack. After the top of the stack is observed to begin to melt, the temperature of the first temperature zone is kept constant, and the second heating wire is set to heat the stack in a downward direction, coil by coil, at a heating rate of 10°C / min to 1350°C and held at that temperature, so as to perform a second-stage partitioned heating. After all the copper sheets have completely melted, they are cooled 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 partitioned heating process, each coil of the second heating wire is set to heat up to 1300°C at a heating rate of 10°C / min.
[0064] The remaining conditions and parameters are the same as in Example 1.
[0065] Example 4
[0066] The difference between this embodiment and embodiment 1 is that in step (3), during a partitioned heating process, the target temperature of the second temperature zone is 950°C.
[0067] The remaining conditions and parameters are the same as in Example 1.
[0068] Example 5
[0069] The difference between this embodiment and embodiment 1 is that in step (3), during a partitioned heating process, the target temperature of the second temperature zone is 1250℃.
[0070] The remaining conditions and parameters are the same as in Example 1.
[0071] Comparative Example 1
[0072] This comparative example provides a method for preparing high-purity metallic materials, including the following steps:
[0073] (1) Provide a heating device, such as Figure 2As shown, the heating device includes a crucible 1, and five turns of heating wire are wound around the outer wall of the crucible 1.
[0074] (2) Place 20 copper sheets with a purity of 6N in crucible 1 to form a stack.
[0075] (3) Adjust the 5 heating wires, with the temperature of each heating wire being consistent, so that the inside of crucible 1 is heated to 1300℃ at a heating rate of 10℃ / min and kept at that temperature, with the entire stacked body in the same temperature zone. After the temperature is kept at that temperature until all the copper sheets are completely melted, cool it to obtain high-purity metal material.
[0076] Test: The number of particles with a diameter greater than 0.5 μm in the high-purity metal materials obtained in the above examples and comparative examples was detected by 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] As shown in Examples 1-2, the present invention performs two-stage partitioned heating on a stack of multiple metal sheets, causing the stack to completely melt. During the first-stage partitioned heating process, the target temperature of the first temperature zone is set higher than the target temperature of the second temperature zone, causing melting to begin from the top of the stack. This reduces the probability of copper sheets slipping, decreases the generation of rubbed particles, and thus reduces particulate matter in the high-purity metal material. Furthermore, during the two-stage partitioned heating, the first temperature zone is kept constant, and the second heating wire is set to heat up gradually from top to bottom, allowing the copper sheet stack to melt slowly from top to bottom. This further reduces the probability of copper sheets slipping, further decreases the generation of rubbed particles, and further reduces particulate matter in the high-purity metal material. In summary, the high-purity copper metal material obtained using the method of the present invention has a lower number of particulate matter.
[0081] As can be seen from Examples 1 and 3, during the two-stage zone heating process, if each coil of the second heating wire is heated to the target temperature simultaneously, the entire second sub-stack in the second temperature zone will melt. The melted copper sheet at the bottom will increase the risk of the upper copper sheet slipping, resulting in an increase in the number of particles in the final high-purity metal material.
[0082] As can be seen from Examples 1 and 4-5, if the target temperature of the second temperature zone is low during the first-stage partitioned heating, the heating time required for the second-stage partitioned heating is longer, increasing the risk of particles falling off the inner wall of the crucible and resulting in a higher number of particles in the high-purity metal material. If the target temperature of the second temperature zone is high during the first-stage partitioned heating, the second sub-stack in the second temperature zone may melt, increasing the risk of copper sheets slipping off and scraping against the inner wall of the crucible, resulting in a higher number of particles in the final high-purity metal material.
[0083] As can be seen from Example 1 and Comparative Example 1, when the entire stack of copper sheets is heated in the same temperature zone, the copper sheets at the bottom of the stack will also melt, causing the upper copper sheets to slide off. After sliding off, the copper sheets rub against the inner wall of the crucible, thereby rubbing off particulate matter and mixing it into the high-purity metal melt, which increases the number of particulate matter in the final high-purity metal material.
[0084] The above description is only a specific embodiment 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 conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection 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 includes: (1) Multiple metal sheets are placed in a partitioned heating device to form a stack; wherein the partitioned heating device includes a first temperature zone and a second temperature zone distributed from top to bottom; a part of the stack is located in the first temperature zone and another part is located in the second temperature zone; the metal sheets include copper sheets; the partitioned heating device includes a crucible for holding multiple metal sheets, and the outer wall of the crucible is wound with a first heating wire and a second heating wire from top to bottom, thereby dividing the crucible into a first temperature zone and a second temperature zone; (2) The stacked body is subjected to a first-stage partition heating and a second-stage partition heating in sequence to obtain a high-purity metal material; wherein, during the first-stage partition heating process, the target temperature of the first temperature zone is greater than the target temperature of the second temperature zone; The stack is heated in one section until the top of the stack begins to melt, and then heated in two sections. During the first-stage zone heating process, the target temperature of the first temperature zone is 1250-1400℃; the target temperature of the second temperature zone is 1000-1200℃; during the second-stage zone heating process, the first temperature zone is a constant temperature zone, and the temperature of the constant temperature zone is 1250-1400℃. During the two-stage zone heating process, the heating method of the second temperature zone includes: the second heating wire is heated in turns from top to bottom; the time interval between turns of the second heating wire is 5-10 minutes. During the two-stage zone heating process, the target temperature of each coil of the second heating wire is independently 1250-1400℃.
2. The method according to claim 1, characterized in that, The purity of the metal sheet is ≥5N.
3. The method according to claim 1, characterized in that, The first heating wire includes at least two turns of heating wire arranged sequentially from top to bottom.
4. The method according to claim 1, characterized in that, The second heating wire includes at least two turns of heating wire arranged sequentially from top to bottom.
5. The method according to claim 1, characterized in that, The method includes the following steps: (I) A partitioned heating device is provided, the partitioned heating device including a crucible, wherein a first heating wire and a second heating wire are wound sequentially from top to bottom on the outer wall of the crucible, thereby dividing the crucible into a first temperature zone and a second temperature zone distributed sequentially from top to bottom; the first heating wire includes at least two turns of heating wire arranged sequentially from top to bottom; the second heating wire includes at least two turns of heating wire arranged sequentially from top to bottom; (II) A plurality of metal sheets are placed in a crucible to form a stack; wherein the metal sheets are copper sheets with a purity ≥5N; a portion of the stack is located in a first temperature zone and another portion is located in a second temperature zone; (III) Adjust the first heating wire to raise the temperature of the first temperature zone to 1250-1400℃ and keep it at that temperature. At the same time, adjust the second heating wire to raise the temperature of the second temperature zone to 1000-1200℃ and keep it at that temperature, thereby performing a section heating of the stacked body. After the top of the stacked body begins to melt, keep the temperature of the first temperature zone constant and set the second heating wire to raise the temperature to 1250-1400℃ in a circle from top to bottom and keep it at that temperature to perform a two-stage section heating. The time interval for the second heating wire to raise the temperature in a circle is 5-10 minutes. After the multiple metal sheets have completely melted, a high-purity metal material is obtained.