A growth apparatus for the Czochralski method of single crystal production
By combining the conductive disk and the sensor, the problem of uneven heating at the bottom of the crucible was solved, enabling more efficient single crystal growth and improving crystal quality and the lifespan of the device.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- GUANGDONG YUEKE JINGNENG TECHNOLOGY CO LTD
- Filing Date
- 2025-08-27
- Publication Date
- 2026-07-21
AI Technical Summary
Existing Chuklaski single crystal growth apparatuses fail to ensure that the bottom of the crucible receives the necessary high-frequency current heating, resulting in a high radial temperature gradient in the melt region near the bottom of the crucible. This leads to problems such as a drop in melt level, a sharp downward bend in the crystallization front, and crystal cracking during crystal growth.
The design combines a conductive disk and an inductor. The conductive disk is located at the bottom of the crucible, and heating is achieved through heat transfer between the conductive disk and the ceramic support. The inductor generates a high-frequency electromagnetic field that induces a current in the conductive disk, improving the heating uniformity at the bottom of the crucible. Heat flow is managed through a thermal shield to ensure heating uniformity and stability.
It improves the quality and efficiency of crystal growth, reduces the radial temperature gradient, reduces the risk of crystal cracking, and increases the utilization rate of melt and the service life of the device.
Smart Images
Figure CN224531114U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the technical field of single crystal growth, and in particular to a growth apparatus for producing single crystals using the Chuklaski method. Background Technology
[0002] The Chuklaski method single crystal growth apparatus is a complex system engineering device integrating high-temperature melting, precision pulling and rotation, precise temperature control, accurate diameter control, and highly clean atmosphere environment control. Specifically, in existing single crystal growth apparatuses, a device for growing single crystals from melt using the Chuklaski method is included. It comprises a heating unit, a platinum crucible mounted on a first ceramic support, a pull rod for pulling the single crystal, a rotatable and vertically movable seed crystal holder fixed to the pull rod, a cylindrical spiral inductor located outside the crucible, and an induction heating source. During crystal growth, the inductor heats the crucible. However, this single crystal growth apparatus fails to ensure that the bottom of the crucible receives the necessary high-frequency current heating, resulting in a high radial temperature gradient in the melt region near the bottom of the crucible. This causes the crystallization front to bend sharply downwards when the melt level drops by 70% during growth, until the crystal touches the bottom of the crucible, preventing further crystal growth. Simultaneously, the high radial gradient generates thermal stress in the crystal, leading to cracking. Utility Model Content
[0003] The technical problem to be solved by this invention is to provide a growth apparatus for single crystal fabrication using the Chuklaski method.
[0004] To achieve the above objectives, this utility model discloses a growth apparatus for single crystal fabrication using the Chuklaski method, comprising a first ceramic support, a first heating element, a crucible, a pull rod, a seed crystal holder, and a conductive disk. The first heating element is used to heat the crucible and is cylindrical in shape. The bottom surface of the first heating element is connected to the top surface of the first ceramic support, and the crucible is located inside the first heating element. The seed crystal holder is connected to the lower part of the pull rod. The pull rod and the seed crystal holder are arranged to move back and forth toward the crucible. The first ceramic support is located between the crucible and the conductive disk, and the conductive disk is connected to the crucible for heat transfer through the first ceramic support.
[0005] It also includes a sensor for heat transfer to the first thermal unit, the sensor being an electromagnetic sensor, which is located on the outside of the first thermal unit and near its lower side.
[0006] It also includes a heat shield, which is cylindrical in shape and located on the outside of the pull rod. The first heat unit is located on the outside of the heat shield.
[0007] It also includes a second thermal unit, which is located inside the first thermal unit and outside the crucible and the thermal shield.
[0008] It also includes a third heating element, which is connected to the top surface of the first heating element and covers the upper opening of the first heating element.
[0009] It also includes a second ceramic support, with the bottom surface of the conductive disk connected to the top surface of the second ceramic support.
[0010] The heat shield has an extension on its top surface, which protrudes from the side of the heat shield and surrounds the side of the heat shield.
[0011] The top surface of the first ceramic support is flat, and the top surface of the first ceramic support is connected to the bottom surface of the crucible.
[0012] The bottom surface of the first ceramic support is planar, the top surface of the conductive disk is planar, and the bottom surface of the first ceramic support and the top surface of the conductive disk are connected.
[0013] Compared with the prior art, the beneficial effects of this utility model are as follows: the conductive disk is located on the bottom side of the first ceramic support, and the conductive disk and the crucible are heat-transferred through the first ceramic support. The top surface of the first ceramic support and the bottom surface of the crucible are connected, which increases the heat conduction efficiency. The first ceramic support is made of ceramic material, and the uniformity of thermal conductivity of ceramic material can improve the heating uniformity of the crucible, thereby improving the heating uniformity of the melt and improving the quality of crystal growth. By setting the conductive disk, the degree of sufficient heating of the bottom of the crucible during crystal growth is improved, reducing the risk of high radial temperature gradients in the melt area near the bottom of the crucible and increasing the crystal growth ratio in the melt.
[0014] The high-frequency electromagnetic field generated by the sensor induces a current in the conductive disk, further enhancing the degree of heating of the crucible bottom during crystal growth. The heat generated by the conductive disk is transferred to the bottom of the crucible through the first ceramic support, thereby improving the uniformity of melt heating and reducing the impact of thermal condition changes caused by the drop in melt level during growth, further increasing the crystal growth ratio in the melt. The heat shield manages heat flow, protects the external structure, and maintains the stable thermal environment required internally, reflecting most of the radiant heat back to the internal high-temperature zone, reducing the loss of heat from the crucible to the outer layer. Attached Figure Description
[0015] Figure 1 This is a schematic diagram of the structure of this utility model; Figure 2 This is a front view of the present invention in a semi-sectional state; Figure 3 This is a front view of the present invention in a semi-sectional state; Figure 4 This is a schematic diagram of the structure of this utility model in a semi-sectional state.
[0016] Markings: 11. First thermal unit; 12. Second thermal unit; 13. Third thermal unit; 2. First ceramic support; 3. Crucible; 4. Thermal shield; 5. Pull rod; 6. Seed crystal holder; 7. Sensor; 8. Conductive disk; 9. Second ceramic support. Detailed Implementation
[0017] To make the objectives, technical solutions, and advantages of this utility model clearer, the following will be combined with Figure 1-4 The state shown will be described in terms of orientation and structure. The following will combine... Figure 1-4 The accompanying drawings provide a further detailed description of this utility model.
[0018] This invention relates to a single crystal growth apparatus for the Chuklaski method, comprising a first ceramic support 2, a first heating element 11, a crucible 3, a pull rod 5, a seed crystal holder 6, and a conductive disk 8. The pull rod 5 is used to pull the single crystal. The seed crystal holder 6 is fixed to the pull rod 5 and is located at the lower part of the pull rod 5. The seed crystal holder 6 is rotatable and vertically movable. The first heating element 11 is used to heat the crucible 3. The first heating element 11 is cylindrical and is fixedly connected to the top surface of the first ceramic support 2. The crucible 3 is located at the first ceramic support 2. Inside the heating unit 11, the crucible 3 is mounted on the upper side of the first ceramic support 2. The top and bottom surfaces of the first ceramic support 2 are both planar, and the bottom surface of the crucible 3 is also planar. The top surface of the first ceramic support 2 and the bottom surface of the crucible 3 are connected. The top surface of the conductive disk 8 is planar, and the bottom surface of the first ceramic support 2 and the top surface of the conductive disk 8 are connected. The first ceramic support 2 is made of ceramic material. The pull rod 5 and the seed crystal holder 6 can be raised and lowered towards the crucible 3. The conductive disk 8 is located on the bottom side of the first ceramic support 2, and the conductive disk 8 and the crucible 3 are heat-transferred through the first ceramic support 2.
[0019] In this embodiment, the diameter of the conductive disk 8 is 1.20-1.25 times the diameter of the crucible 3, and the thickness of the conductive disk 8 is 5-40 mm. The diameter of the first ceramic support 2 is greater than or equal to the diameter of the conductive disk 8. By setting the conductive disk 8, the degree of sufficient heating of the bottom of the crucible 3 during crystal growth is improved, and the radial temperature gradient in the melt is reduced. The conductive disk 8 with the above-mentioned diameter and thickness can reduce the following risks: if the diameter of the conductive disk 8 is less than 1.20 times the diameter of the crucible 3 and the thickness of the conductive disk 8 is less than 5 mm, it is impossible to ensure that the bottom of the crucible 3 receives the necessary heating; if the diameter of the conductive disk 8 is greater than 1.25 times the diameter of the crucible 3 and the thickness of the conductive disk 8 is greater than 40 mm, it will cause the bottom of the crucible 3 to overheat and destroy the stable growth of the crystal.
[0020] In the method of growing single crystals from melt using the Chuklaski method and this apparatus, the material is melted in crucible 3, and the seed crystal is pulled by rotating pull rod 5 and seed crystal holder 6 to grow the upper conical portion of the crystal to a predetermined diameter, followed by the growth of the cylindrical portion of the crystal. The lower defect portion of the crystal is separated by increasing the pulling speed and then slowly cooled. Specifically, after the upper conical portion is grown to the predetermined diameter, the crystal rotation speed is reduced to half of W0, where W0 is the initial rotation speed for a specific type of crystal, and the cylindrical portion of the crystal is grown. Then, the crystal rotation speed is increased to 0.85 times W0, and the pulling speed is increased to twice V0, where V0 is the initial pulling speed for a specific type of crystal, to grow the lower defect portion of the crystal in order to separate the lower defect portion of the crystal.
[0021] After growing the upper conical portion of the crystal to a predetermined diameter, the crystal rotation speed is reduced to half of W0, enabling the growth of a single crystal with a diameter 0.85 times that of crucible 3. This eliminates turbulence and the appearance of unrelated regions in the melt, which are regions generated when the radial gradient is reduced by increasing the rotation speed of the grown crystal. Since a smaller crucible 3 can be used, the cost of growing crystals of a specified diameter can be significantly reduced.
[0022] Increasing the crystal rotation speed to 0.85 times W0 during the growth of the lower defect portion of the crystal enables the growth of a lower defect region with lower mechanical stress. This significantly reduces the radial temperature gradient and eliminates the increase in the downward curvature of the crystallization front when the melt level drops, resulting in a flatter crystallization front. This reduces mechanical stress and effectively absorbs the wall radiation of crucible 3 to heat the defect region of the high-quality part. Since the crystal does not bear high thermal stress, the risk of crystal cracking during separation and cooling to room temperature is reduced.
[0023] Therefore, the use of a cold-bottomed conductive disk 8 reduces the impact on crystal growth; and when growing the lower defect portion, the crystal rotation speed is increased to 0.85 times W0 to ensure a flat crystallization front, so that the crystal growth process can continue to the bottom of the crucible 3, that is, to grow a crystal with a mass of 95-97% of the initial raw material mass. This improves the utilization rate of the raw material in the crucible 3 during the growth process and also extends the service life of the crucible 3.
[0024] Increasing the pulling speed to twice V0 during the growth of the lower defect portion of the crystal can reduce the non-productive time in the crystal growth process. The non-productive time is the period during which the high-quality commercial portion of the crystal does not grow.
[0025] This invention also includes an inductor 7 for heat transfer to the first heating element 11. The inductor 7 is a coil inductor, located outside and near the bottom of the first heating element 11, and also outside the crucible 3. The inductor 7 is arranged in a cylindrical spiral shape. The conductive disk 8 is located inside the inductor 7. The high-frequency electromagnetic field generated by the inductor 7 induces a current in the conductive disk 8, further enhancing the heating of the bottom of the crucible 3 during crystal growth. The heat generated by the conductive disk 8 is transferred to the bottom of the crucible 3 through the first ceramic support 2, and the top surface of the first ceramic support 2 is surface-connected to the bottom surface of the crucible 3, increasing the heat transfer efficiency. The high thermal conductivity and the fact that the first ceramic support 2 is made of ceramic material, combined with the fact that the top surface of the first ceramic support 2 is connected to the bottom surface of the crucible 3, can improve the heating uniformity of the crucible 3, thereby improving the heating uniformity of the melt and improving the quality of crystal growth. At the same time, the connection between the bottom surface of the first ceramic support 2 and the top surface of the conductive disk 8 can improve the heat transfer efficiency between the conductive disk 8 and the first ceramic support 2, thereby improving the heating uniformity of the melt and reducing the impact of the change in thermal conditions caused by the drop in melt level during the growth process. This allows for an increase in the proportion of high-quality parts of the grown crystal in the raw material mass.
[0026] This utility model also includes a heat shield 4, which is cylindrical in shape and located outside the pull rod 5. The first thermal unit 11 is located outside the heat shield 4. The heat shield 4 is cylindrical in shape and located above the crucible 3. The heat shield 4 manages heat flow, protects the external structure, and maintains the stable thermal environment required inside, reflecting most of the radiant heat back to the internal high-temperature zone, thereby reducing the loss of heat from the crucible 3 to the outer layer.
[0027] The present invention also includes a second heating element 12, which is located inside the first heating element 11 and outside the crucible 3 and the heat shield 4. By setting the second heating element 12, the uniformity of the melt heating is improved.
[0028] This utility model also includes a second ceramic support 9, the bottom surface of the conductive disk 8 is connected to the top surface of the second ceramic support 9, and the diameter of the conductive disk 8 is less than or equal to the diameter of the second ceramic support 9. The above arrangement helps to reduce the heat loss of the conductive disk 8.
[0029] The present invention also includes a third heating element 13, the bottom surface of which is connected to the top surface of the first heating element 11, the third heating element 13 covers the upper opening of the first heating element 11, and the top surface of the second heating element 12 and the third heating element 13 are spaced apart. By setting the third heating element 13, the uniformity of melt heating is further improved.
[0030] The top surface of the heat shield 4 is provided with an extension portion 41, which protrudes from the side of the heat shield 4 and surrounds the side of the heat shield 4. The bottom surface of the extension portion 41 is fixedly connected to the top surface of the second heat unit 12, and the top surface of the extension portion 41 is spaced apart from the bottom surface of the third heat unit 13.
[0031] Examples of the methods for growing three types of crystals using the Chuklaski method with the apparatus of this invention are as follows: First example: Growth of bismuth germanate single crystals.
[0032] When growing bismuth germanate crystals using the classic Chuklaski method, a rotational speed of 35-45 rpm and a pulling speed of 0.5-2 mm / h are used. In this example, W0 = 40 rpm and V0 = 1 mm / h are selected.
[0033] 6000 grams of bismuth germanate raw material, specifically furnace charge or crystal fragments, is placed into a platinum crucible 3 with a diameter of 96 mm and a height of 130 mm. A crystallization unit is assembled, and the power of the induction heating source is increased to melt the raw material and bring it to the seeding temperature. A bismuth germanate seed crystal with a rotation speed of 40 rpm is immersed in the melt using a moving pull rod 5. While continuously pulling at a speed of 1 mm / h, the crystal is grown to a diameter of 75 mm by adjusting the power of the induction heating source. The rotation speed is then reduced to 20 rpm to grow the high-quality cylindrical portion until a mass of 4200-4500 grams is reached. The rotation speed and growth speed are then increased to 34 rpm and 2 mm / h respectively to grow the defective portions of the crystal until a mass of 5700-5850 grams is reached. The crystal is then separated from the melt by accelerating the moving pull rod 5, and the heating power is reduced to gradually lower the temperature to room temperature before the crystal is removed.
[0034] Second example: Growth of gadolinium silicate single crystals.
[0035] When growing gadolinium silicate crystals using the classic Chuklaski method, a rotational speed of 30-35 rpm and a pulling speed of 1-2 mm / h are used. In this example, W0 = 30 rpm and V0 = 1 mm / h are selected.
[0036] 3200 grams of gadolinium silicate raw material, specifically furnace charge or crystal fragments, was placed into an iridium crucible 3 with a diameter of 86 mm and a height of 90 mm. A crystallization unit was assembled, and the power of the induction heating source was increased to melt the raw material and bring it to the seeding temperature. Using a moving pull rod 5, a gadolinium silicate seed crystal rotating at 30 rpm was immersed in the melt and continuously pulled at a speed of 1.5 mm / h. Simultaneously, the crystal was grown to a diameter of 65 mm by adjusting the power of the induction heating source. The rotation speed was then reduced to 15 rpm to grow a high-quality cylindrical portion until a mass of 2300-2400 grams was reached. The rotation speed and growth rate were then increased to 25.5 rpm and 2 mm / h, respectively, to grow the defective portions of the crystal until a mass of 3050-3100 grams was reached. The crystal was then separated from the melt by accelerating the moving pull rod 5, and the heating power was reduced to gradually lower the temperature to room temperature before the crystal was removed.
[0037] Third example: Growth of sodium iodide crystals.
[0038] When growing sodium iodide crystals using the classic Chuklaski method, a rotational speed of 15-25 rpm and a pulling speed of 1-3 mm / h are used. In this example, W0 = 20 rpm and V0 = 1 mm / h are selected.
[0039] 2000 grams of sodium iodide raw material is placed into a platinum crucible 3 with a diameter of 86 mm and a height of 100 mm. A crystallization unit is assembled. The raw material is either furnace charge or crystal fragments. The power of the induction heating source is increased to melt the raw material and bring it to the crystal-taking temperature. Using a moving pull rod 5, a sodium iodide seed crystal with a rotation speed of 20 rpm is immersed into the melt and continuously pulled at a speed of 1 mm / h. At the same time, the power of the induction heating source is adjusted to grow the crystal to a diameter of 68 mm. Then, the rotation speed is reduced to 10 rpm to grow the high-quality cylindrical part until the mass reaches 1400-1450 grams. The rotation speed and growth speed are then increased to 17 rpm and 2 mm / h, respectively, to grow the defective part of the crystal until the mass reaches 1900-1950 grams. Then, the crystal is separated from the melt by accelerating the moving pull rod 5. The heating power is then reduced, and the temperature is gradually lowered to room temperature. The crystal is then removed.
[0040] The technical solutions proposed in the above three examples allow for the growth of single crystals from melts using the classical Chuklaski method, with the quality of the high-quality portion increasing to 70% of the raw material mass. This is because heating the crucible 3 from the bottom significantly reduces the impact of thermal changes during melt level drops, which can lead to the growth of defective crystals. Using the conductive disk 8 to heat the bottom of the crucible 3 does not complicate the device control, as there is no need to introduce current into the conductive disk 8, and the control of the heating power of the conductive disk 8 is synchronized with the power control of the induction heating source.
[0041] Therefore, by heating the bottom of crucible 3, reducing the crystal rotation speed before the growth of the crystal cylinder, and increasing the rotation and pulling speed after the growth of the crystal cylinder, it is possible to grow a high-quality single crystal with a diameter 0.85 times that of crucible 3. This reduces non-productive time during crystal growth, improves the utilization rate of raw materials in crucible 3, reduces the cost required for crystal growth, and extends the service life of crucible 3 by 2-3 times by reducing the crystallization and cooling of raw materials in crucible 3.
[0042] Of course, the above embodiments are only for illustrating the technical concept and features of this utility model. Their purpose is to enable those skilled in the art to understand the content of this utility model and implement it accordingly. They cannot be used to limit the protection scope of this utility model. All modifications made in accordance with the spirit of the main technical solution of this utility model should be covered within the protection scope of this utility model.
Claims
1. A growth apparatus for single crystal fabrication using the Chuklaski method, characterized in that, The device includes a first ceramic support (2), a first heating element (11), a crucible (3), a pull rod (5), a seed crystal holder (6), and a conductive disk (8). The first heating element (11) is used to heat the crucible (3). The first heating element (11) is cylindrical. The bottom surface of the first heating element (11) is connected to the top surface of the first ceramic support (2). The crucible (3) is located inside the first heating element (11). The seed crystal holder (6) is connected to the lower part of the pull rod (5). The pull rod (5) and the seed crystal holder (6) are arranged to move up and down towards the crucible (3). The conductive disk (8) is located on the bottom side of the crucible (3). The first ceramic support (2) is located between the crucible (3) and the conductive disk (8). The conductive disk (8) is connected to the crucible (3) through the first ceramic support (2) for heat transfer.
2. The growth apparatus for single crystal fabrication using the Chuklaski method according to claim 1, characterized in that, It also includes an inductor (7) for heat transfer to the first thermal unit (11), the inductor (7) being an electromagnetic inductor (7) located on the outside and near the bottom of the first thermal unit (11).
3. The growth apparatus for single crystal fabrication using the Chuklaski method according to claim 1, characterized in that, It also includes a heat shield (4), which is cylindrical in shape and located outside the pull rod (5). The first heat unit (11) is located outside the heat shield (4).
4. A growth apparatus for single crystal fabrication using the Chuklaski method according to claim 3, characterized in that, It also includes a second thermal unit (12), which is located inside the first thermal unit (11) and outside the crucible (3) and the thermal shield (4).
5. A growth apparatus for single crystal fabrication using the Chuklaski method according to claim 1, characterized in that, It also includes a third heating element (13), which is connected to the top surface of the first heating element (11) and covers the upper opening of the first heating element (11).
6. A growth apparatus for single crystal fabrication using the Chuklaski method according to claim 1, characterized in that, It also includes a second ceramic support (9), the bottom surface of the conductive disk (8) being connected to the top surface of the second ceramic support (9).
7. A growth apparatus for single crystal fabrication using the Chuklaski method according to claim 3, characterized in that, The heat shield (4) has an extension portion on its top surface. The extension portion protrudes from the side of the heat shield (4) and is arranged around the side of the heat shield (4).
8. A growth apparatus for single crystal fabrication using the Chuklaski method according to claim 1, characterized in that, The top surface of the first ceramic support (2) is a plane, and the top surface of the first ceramic support (2) is connected to the bottom surface of the crucible (3).
9. A growth apparatus for single crystal fabrication using the Chuklaski method according to claim 8, characterized in that, The bottom surface of the first ceramic support (2) is flat, the top surface of the conductive disk (8) is flat, and the bottom surface of the first ceramic support (2) and the top surface of the conductive disk (8) are connected.