Czochralski method crystal growth device
The combination of a rising and falling rotating insulation cylinder and multiple heating elements solves the problems of temperature gradient changes and uneven axial heating in crystal growth by the Czochralski method, achieving high-quality crystal growth with low cracking risk and improving the yield rate.
Patent Information
- Application Number
- CN202422678761.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-04
- Publication Date
- 2025-10-10
- Estimated Expiration
- 2034-11-04
AI Technical Summary
The temperature gradient during the existing Czochralski method of crystal growth varies greatly, leading to crystal defects and polycrystalline problems. After the growth is completed, uneven axial heating can easily lead to crystal cracking.
A lifting and rotating insulation cylinder structure is adopted, and multiple heating elements are combined to heat the insulation cylinder and crucible. The first driving element controls the relative position of the melt melting surface and the heating element to remain unchanged. The second heating element reduces the temperature difference after the crystal growth is completed. The weighing element and the driving element are used to ensure the growth quality.
It effectively reduces the temperature gradient change and axial heating unevenness during the crystal growth process, reduces the risk of crystal cracking, and improves the quality and yield of the crystal product.
Smart Images
Figure CN223422812U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of crystal growth, in particular to a Czochralski crystal growth device. Background Art
[0002] The Czochralski method is a commonly used growth method for YCOB crystals. The commonly used heating method is induction heating, and the induction heating coils are mostly fixed. During the crystal growth process, because the positions of the crucible and the heating element are fixed, the position of the melt surface will gradually decrease as the crystal grows, resulting in large changes in the temperature gradient of the crystal and the solid-liquid interface during the growth process, which is prone to defects, polycrystalline and other problems.
[0003] To address this issue, the prior art typically employs a mobile crucible method, allowing the crucible to move as the crystal grows, ensuring that the relative position of the melt surface and the heating element remains unchanged, thereby reducing temperature gradient changes during growth. However, as the crucible moves, it gradually escapes from the insulation, further increasing the temperature gradient changes to a certain extent. Furthermore, after crystal growth is completed, the prior art device detaches from the melt surface, and the temperature below is higher than that above. This creates a risk of cracking along the crystal's axis due to uneven heating. Utility Model Content
[0004] The utility model aims to provide a Czochralski crystal growing device to solve the problems in the prior art of large temperature gradient variation during the growth process and uneven axial heating after the growth.
[0005] The utility model provides a Czochralski crystal growth device, comprising a furnace shell, a seed crystal rod, a first driving member and a heating assembly. A heat preservation tube and a partition are provided in the furnace shell. The partition is provided with an opening, and the heat preservation tube passes through the opening. The heat preservation tube comprises an upper cylinder and a lower cylinder, and the upper cylinder and the lower cylinder are buckled together to form a growth space. A crucible for holding a melt is embedded in the bottom of the growth space. The lower end of the seed crystal rod is located in the growth space and contacts with the melted part of the melt. The first driving member is used to drive the heat preservation tube to rise and fall and rotate. The heating assembly comprises a first heating member and a second heating member located along the axis of the heat preservation tube and on both sides of the partition respectively. The first heating member is used to heat the melt, and the second heating member is used to heat the heat preservation tube.
[0006] Also included is a second driving member, the second driving member is used to drive the seed rod to rise and fall and rotate;
[0007] The weighing element is electrically connected to the second driving element, and the weighing element is used to measure the weight of the seed rod;
[0008] The first driving member and the second driving member are electrically connected.
[0009] As an optimal technical solution for the Czochralski crystal growth device, the second heating element is provided in plurality, and the plurality of second heating elements are provided outside the insulation tube and distributed at intervals along the circumference of the insulation tube, and the second heating element is provided at intervals from the insulation tube along the radial direction of the insulation tube.
[0010] As an optimal technical solution for the Czochralski crystal growth device, it also includes multiple heat-insulating components, which are arranged in an arc-shaped structure. The multiple heat-insulating components are connected end to end to form a ring structure and are covered on the outside of the second heating component.
[0011] As a preferred technical solution of the Czochralski crystal growing device, the second heating element is a resistance heating rod.
[0012] As a preferred technical solution of the Czochralski crystal growing device, the heat-insulating component is made of mullite.
[0013] As an optimal technical solution for the Czochralski crystal growth device, the top and bottom of the furnace shell are respectively provided with an upper connecting hole and a lower connecting hole, the lower end of the seed rod passes through the upper connecting hole and the upper cylinder, the first driving member drives the insulation cylinder through a support member, and the support member passes through the lower connecting hole and is connected to the first driving member.
[0014] As a preferred technical solution of the Czochralski crystal growing device, the first driving member is connected to the furnace shell via a first bellows, and the second driving member is connected to the furnace shell via a second bellows.
[0015] The first heating element is configured as an electromagnetic induction coil, and the electromagnetic induction coil is coaxial with the crucible.
[0016] The beneficial effects of the utility model are:
[0017] The utility model provides a crystal growth device using the Czochralski method, which embeds a crucible in the bottom of a growth space formed by an upper cylinder and a lower cylinder. When a first driving member drives a heat-insulating cylinder to rise and fall, the crucible will not separate from the heat-insulating cylinder, thereby ensuring that the temperature gradient changes slightly during the crystal growth process. A second heating member is provided to heat the heat-insulating cylinder, so that after the crystal growth is completed, the temperature difference between the upper and lower ends thereof is small, thereby reducing uneven axial heating of the crystal and thereby reducing the risk of cracking. BRIEF DESCRIPTION OF THE DRAWINGS
[0018] Figure 1 This is a schematic structural diagram of the Czochralski crystal growth device in a first use state according to an embodiment of the present invention;
[0019] Figure 2 This is a schematic structural diagram of the Czochralski crystal growth device in a second use state according to an embodiment of the present invention;
[0020] Figure 3 Schematic diagram of the positional relationship between the heat-insulating component and the heat-insulating cylinder in an embodiment of the present utility model.
[0021] In the picture:
[0022] 1. Furnace shell; 11. Upper connecting hole; 12. Lower connecting hole; 2. Insulation tube; 21. Upper cylinder; 22. Lower cylinder; 31. First heating element; 32. Second heating element; 41. Support member; 42. Partition; 5. Crucible; 6. Insulation element; 7. Temperature measuring element; 8. Seed rod; 91. Second driving element; 911. Second bellows; 92. First driving element; 921. First bellows;
[0023] 100, melt; 200, growth space; 300, crystal. DETAILED DESCRIPTION
[0024] The following is a clear and complete description of the technical solution of the present invention in conjunction with the accompanying drawings. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.
[0025] In the description of the present invention, it should be noted that the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and are not intended to indicate or imply that the devices or elements referred to must have a specific position, be constructed and operated in a specific position, and therefore should not be understood as limiting the present invention. In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance. Among them, the terms "first position" and "second position" are two different positions, and the first feature being "above", "above" and "above" the second feature includes the first feature being directly above and obliquely above the second feature, or simply means that the first feature is at a higher level than the second feature. The first feature being "below", "below" and "below" the second feature includes the first feature being directly below and obliquely below the second feature, or simply means that the first feature is at a lower level than the second feature.
[0026] In the description of this utility model, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integral connections; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and internal communication between two components. Those skilled in the art will understand the specific meanings of these terms in this utility model based on the specific circumstances.
[0027] The following describes embodiments of the present invention in detail. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended only to explain the present invention and are not to be construed as limiting the present invention.
[0028] like Figure 1-Figure 3 As shown, the present invention provides a Czochralski crystal growth device for reducing the change in temperature gradient during the growth of a crystal 300, and reducing the axial heating unevenness of the crystal 300 after the growth of the crystal 300 is completed, thereby reducing the risk of cracking. The Czochralski crystal growth device includes a furnace shell 1, a seed crystal rod 8, a first drive member 92, and a heating assembly. An insulation cylinder 2 and a partition 42 are provided in the furnace shell 1. The partition 42 is fixedly connected to the inner wall of the furnace shell 1. An opening is provided in the middle of the partition 42. The insulation cylinder 2 passes through the opening of the partition 42 and can be raised and lowered and rotated relative to the partition 42. The insulation cylinder 2 is configured as a cylindrical structure, including an upper cylinder 21 and a lower cylinder 22. The openings of the upper cylinder 21 and the lower cylinder 22 are arranged facing each other. The upper cylinder 21 and the lower cylinder 22 are buckled together to form a growth space 200 for the crystal 300. A crucible 5 for holding the melt 100 is embedded in the bottom of the growth space 200. The lower end of the seed rod 8 is located in the growth space 200 and contacts the melted part of the melt 100. As the crystal 300 grows, the seed rod 8 is pulled upward, and the seed rod 8 and the insulation cylinder 2 are rotated at the same time until the growth of the crystal 300 is completed. The grown crystal 300 is placed in the growth space 200 and annealed for a period of time to obtain a finished crystal 300. The specific production process is the prior art in this field and will not be described in detail here. The first driving member 92 is used to drive the insulation cylinder 2 to rise and fall and rotate. The heating assembly includes a first heating member 31 and a second heating member 32 along the axis of the insulation cylinder 2 and located on both sides of the partition 42. The first heating member 31 is used to heat the melt 100, and the second heating member 32 is used to heat the insulation cylinder 2. Please refer to Figure 1-Figure 2As shown, the second heating element 32 is located above the first heating element 31. During the growth of the crystal 300, the melting surface of the melt 100 gradually decreases. The first driving member 92 drives the insulation cylinder 2 upward to ensure that the relative position of the melting surface of the melt 100 and the first heating element 31 remains unchanged. During this process, the insulation cylinder 2 and the crucible 5 rise synchronously, which can prevent the crucible 5 from detaching from the insulation cylinder 2, thereby reducing the temperature gradient and ensuring the quality of the crystal 300 during the growth process. At the same time, the first driving member 92 can be used to synchronously drive the insulation cylinder 2 to rotate as needed to adjust the eddy current, improve the solid-liquid interface between the crystal 300 and the melt 100, and further ensure the quality of the crystal 300. After the growth of the crystal 300 is completed, the second heating element 32 heats the insulation cylinder 2. Specifically, after the growth of the crystal 300 is completed, it is located in the upper middle part of the growth space 200, that is, inside the upper cylinder 21. The second heating element 32 mainly heats the upper cylinder 21, thereby reducing the axial temperature difference of the upper cylinder 21. Therefore, the axial temperature difference in the growth space 200 is small, reducing the uneven heating of the crystal 300 along the axial direction and reducing the risk of cracking.
[0029] For details, please refer to Figure 1-Figure 3 As shown, the second heating element 32 is provided in plurality, and the plurality of second heating elements 32 are provided on the outside of the heat-insulating tube 2 and are spaced apart along the circumference of the heat-insulating tube 2. The second heating element 32 can be provided in 2-4 numbers and evenly distributed along the circumference of the heat-insulating tube 2. In this embodiment, the second heating element 32 is provided in three numbers, and the three second heating elements 32 are evenly distributed along the circumference of the heat-insulating tube 2. The second heating element 32 is spaced apart from the heat-insulating tube 2 in the radial direction of the heat-insulating tube 2, so as to heat the heat-insulating tube 2 by means of heat convection and heat radiation, and avoid direct contact with the heat-insulating tube 2 causing local overheating of the heat-insulating tube 2. In order to further enhance the heating effect of the second heating element 32 and reduce heating energy consumption, the Czochralski crystal growth device in this embodiment further includes a plurality of heat-insulating elements 6, which are provided in an arc-shaped structure. The plurality of heat-insulating elements 6 are connected end to end to form a ring structure and are coated on the outside of the second heating element 32. The heat-insulating element 6 and the second heating element 32 are both mounted on the partition 42, and the height of the heat-insulating element 6 is higher than the height of the second heating element 32. By providing the insulation member 6, the heat on the side of the second heating member 32 facing away from the insulation tube 2 is prevented from being directly dissipated into the interior space of the furnace shell 1, and the heat is concentrated between the insulation member 6 and the insulation tube 2, thereby enhancing the heating effect on the insulation tube 2 and reducing energy consumption. Specifically, the second heating member 32 is configured as a resistance heating rod, preferably a U-shaped resistance silicon-molybdenum heating rod, and the insulation member 6 is an arc-shaped mullite with a thickness of 3-5 cm. In other embodiments, the second heating member 32 can also use other types of heating sources, and the insulation member 6 can also be made of materials of different materials and thicknesses. This can be determined according to actual project needs and will not be listed here.
[0030] Optionally, in order to obtain the temperature at each stage of the growth process for further temperature control operation, the Czochralski crystal growth device is further provided with a temperature measuring member 7 for temperature measurement. The temperature measuring member 7 is preferably a thermocouple and is arranged at the gap between the second heating member 32 and the insulation cylinder 2. The temperature measuring member 7 is arranged to measure the temperature at the crucible 5 in the insulation cylinder 2, so as to ensure that the temperature during the growth process is controllable. The method for measuring the temperature in the insulation cylinder 2 by the temperature measuring member 7 is known in the art and will not be described in detail here. For example, the temperature measuring member 7 can be calibrated to measure the temperature.
[0031] Specifically, the first heating member 31 is an electromagnetic induction coil which is coaxially arranged with the crucible 5 to uniformly heat the melt 100 in the crucible 5. In order to avoid the high temperature affecting the comprehensive performance of the electromagnetic induction coil, cooling liquid can be introduced into the electromagnetic induction coil to cool it. Similarly, in order to avoid the temperature of the furnace shell 1 being too high, a cooling channel can be arranged inside the furnace shell 1 and cooling liquid can be introduced into the cooling channel to cool it, or a forced cooling method such as spraying and blowing can be used outside the furnace shell 1.
[0032] Further, since the temperature inside the furnace shell 1 is high during the growth of the crystal 300, in order to avoid affecting the operation of the first driving member 92 and the normal operation of the seed rod 8 operating device, the top and bottom of the furnace shell 1 are respectively provided with an upper connecting hole 11 and a lower connecting hole 12. The lower end of the seed rod 8 passes through the upper connecting hole 11 and the top of the upper cylinder 21 and enters the growth space 200 to perform the related operations of crystal 300 growth and annealing. The first driving member 92 is arranged outside the furnace shell 1 and below the lower connecting hole 12, and drives the insulation cylinder 2 through the support member 41. The support member 41 passes through the lower connecting hole 12 and is connected with the first driving member 92. The first driving member 92 is selected to be a device that has both rotary drive and linear drive, such as a two-degree-of-freedom motor in the prior art. The Czochralski crystal growth device further comprises a second driving member 91 which is the seed rod 8 operating device and is arranged outside the furnace shell 1 and above the upper connecting hole 11. The second driving member 91 is connected with the upper end of the seed rod 8 and is used to drive the seed rod 8 to ascend and rotate to meet the process requirements during the growth of the crystal 300. Similarly, the second driving member 91 is also selected to be a device that has both rotary drive and linear drive, such as a two-degree-of-freedom motor.
[0033] Since both the first and second drive members 92, 91 are located outside the furnace shell 1, in order to achieve connection between the first and second drive members 92, 91 and the furnace shell 1 and to allow for relative movement between the first and second drive members 92, 91 and the furnace shell 1, the first drive member 92 is connected to the furnace shell 1 via a first bellows 921, and the second drive member 91 is connected to the furnace shell 1 via a second bellows 911. Both the first and second bellows 921, 911 are preferably metal bellows, which provide support while also being capable of axial compression or extension, thereby satisfying the movement requirements of the first and second drive members 92, 91.
[0034] Optionally, the growth process of the crystal 300 cannot be directly observed. Therefore, to avoid defects such as excessive crystal 300 due to abnormalities during the growth process, a weighing element (not shown) is also installed on the second driving member 91. The weighing element is electrically connected to the second driving member 91. Specifically, the weighing element is electrically connected to the controller of the second driving member 91. The weighing element is used to measure the weight of the seed rod 8. Furthermore, the first driving member 92 is electrically connected to the second driving member 91. Specifically, the controller of the first driving member 92 is electrically connected to the controller of the second driving member 91. The weighing element measures the total weight of the seed rod 8 and the crystal 300 at its lower end. During the growth process, the controller of the second driving member 91 feeds the weighing result of the weighing element back to the first driving member 92 in real time. The first driving member 92 adjusts its rotation speed and lifting speed based on the weighing result of the weighing element to maintain the relative position of the melting surface of the melt 100 and the first heating element 31 unchanged, thereby ensuring the quality of the crystal 300 during growth. After the growth of the crystal 300 is completed, the weighing result measured by the weighing piece reaches the target value, and then in-situ annealing and other subsequent operations are carried out in a timely manner. The relevant structure and method of the weighing piece for weighing the seed crystal rod 8 are conventional technical means in this field and will not be described in detail here. As the existing technology in this field, the controller can be selected as a separate single-chip microcomputer or an integrated single-chip microcomputer, which runs a control program in the existing technology. The measurement result of the weighing piece is transmitted to the controller, and the controller issues further instructions to the relevant actuators, thereby changing the rotation speed and lifting speed of the second drive member 91.
[0035] When using the Czochralski crystal growth apparatus of this embodiment to grow crystal 300, raw materials are first placed in crucible 5. Insulation tube 2 is assembled and furnace shell 1 is sealed. First heating element 31 is applied for heating, and seed rod 8 is operated to contact the melting surface of melt 100. Crystal 300 is produced according to the prior art process of seeding, shouldering, equalizing diameters, and end-to-end. During this process, first drive element 92 adaptively drives insulation tube 2 to rise and rotate, while second drive element 91 adaptively drives seed rod 8 to rise and rotate. After crystal 300 is grown, in-situ annealing is performed, during which second heating element 32 provides heating, thereby reducing circumferential heating unevenness of crystal 300 and lowering the risk of cracking.
[0036] The use of the Czochralski crystal growth device in this embodiment can ensure that the temperature gradient of the crystal 300 during the growth process changes little, and can also ensure that the risk of cracking of the crystal 300 during the annealing process after the growth is completed is reduced, thereby ensuring the quality and yield of the finished product.
[0037] Obviously, the above embodiments of the present invention are merely examples for the purpose of clearly illustrating the present invention, and are not intended to limit the implementation methods of the present invention. Those skilled in the art will appreciate that other variations or modifications can be made based on the above description. It is not necessary and impossible to enumerate all implementation methods here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the claims of the present invention.
Claims
1. A Czochralski crystal growth device, characterized in that: include: A furnace shell (1), wherein a heat-insulating cylinder (2) and a partition (42) are provided in the furnace shell (1), the partition (42) is provided with an opening, the heat-insulating cylinder (2) passes through the opening, the heat-insulating cylinder (2) comprises an upper cylinder (21) and a lower cylinder (22), the upper cylinder (21) and the lower cylinder (22) are buckled together to form a growth space (200), and a crucible (5) for holding a melt (100) is embedded in the bottom of the growth space (200); a seed rod (8), the lower end of the seed rod (8) being located in the growth space (200) and in contact with the melted portion of the melt (100); A first driving member (92), the first driving member (92) is used to drive the heat preservation cylinder (2) to rise, fall and rotate; A heating assembly, the heating assembly comprising a first heating element (31) and a second heating element (32) respectively located on both sides of the partition (42) along the axis of the heat-insulating cylinder (2), the first heating element (31) being used to heat the melt (100), and the second heating element (32) being used to heat the heat-insulating cylinder (2); It also includes a second driving member (91), which is used to drive the seed rod (8) to rise and fall and rotate; A weighing element is installed on the second driving member (91), the weighing element is electrically connected to the second driving member (91), and the weighing element is used to measure the weight of the seed rod (8); The first driving member (92) and the second driving member (91) are electrically connected.
2. The Czochralski crystal growth device according to claim 1, characterized in that: The second heating element (32) is provided in plurality, and the plurality of second heating elements (32) are provided outside the heat-insulating cylinder (2) and are distributed at intervals along the circumference of the heat-insulating cylinder (2), and the second heating element (32) is provided at intervals from the heat-insulating cylinder (2) along the radial direction of the heat-insulating cylinder (2).
3. The Czochralski crystal growth device according to claim 1, characterized in that: It also includes a plurality of heat-insulating components (6), wherein the heat-insulating components (6) are configured as an arc-shaped structure, and the plurality of heat-insulating components (6) are connected end to end to form a ring-shaped structure and are wrapped around the outside of the second heating component (32).
4. The Czochralski crystal growth device according to claim 2, characterized in that: The second heating element (32) is a resistance heating rod.
5. The Czochralski crystal growth device according to claim 3, characterized in that: The thermal insulation component (6) is made of mullite.
6. The Czochralski crystal growth device according to claim 2, characterized in that: The top and bottom of the furnace shell (1) are respectively provided with an upper connecting hole (11) and a lower connecting hole (12); the lower end of the seed rod (8) passes through the upper connecting hole (11) and the upper cylinder (21); the first driving member (92) drives the heat-insulating cylinder (2) through a supporting member (41); the supporting member (41) passes through the lower connecting hole (12) and is connected to the first driving member (92).
7. The Czochralski crystal growth device according to claim 1, characterized in that: The first driving member (92) is connected to the furnace shell (1) via a first bellows (921), and the second driving member (91) is connected to the furnace shell (1) via a second bellows (911).
8. The Czochralski crystal growth device according to any one of claims 1 to 7, characterized in that: The first heating element (31) is configured as an electromagnetic induction coil, and the electromagnetic induction coil is coaxial with the crucible (5).