TWI890441B - Single crystal growth device - Google Patents

Abstract

A single crystal growth device, and relates to the technical field of crystal growth. The single crystal growth device includes a furnace body, a supporting assembly, a lifting driving mechanism, a flow stabilizing plate and a cooling ring. The furnace body forms a furnace cavity, and a heating assembly is disposed at an inner side of the furnace body. The supporting assembly includes an objective table and a supporting shaft, where the objective table is located in the furnace cavity and used for the placement of a crucible. The lifting driving mechanism is used for driving the furnace body and/or the supporting assembly to lift the furnace body relative to the supporting assembly. A cooling ring is communicated with an exterior of the furnace body through a first pipeline and a second pipeline. The temperature field in the furnace cavity can be effectively controlled by the cooling ring, so that an appropriate temperature gradient is provided for crystal growth and the quality of crystal growth is ensured. Due to the arrangement of the flow stabilizing plate, the gas convection is reduced, which is beneficial to ensuring the crystal quality; the power required for the temperature of the space where the crucible is located is reduced.

Description

Single crystal growth equipment

The present invention relates to the field of crystal growth technology, and more particularly, to a single crystal growth device.

To produce large crystals, single crystal growth equipment using the descending method requires creating a temperature field with a defined temperature gradient within the furnace. The crucible containing the molten raw material is then slowly lowered, moving from a high-temperature zone to a low-temperature zone to achieve crystallization. Existing single crystal growth equipment, due to its irrational structure, poorly controls the temperature field, resulting in a wide distribution of impurities in the grown crystals and poor quality, making it difficult to produce large crystals.

In view of this, the present invention is proposed.

The present invention aims to provide a single crystal growth apparatus that has good quality of grown crystals and is advantageous for growing large-sized crystals.

The embodiment of the present invention can be implemented as follows:

The present invention provides a single crystal growth device, comprising:

A furnace body forms a furnace cavity, and a heating component is provided on the inner side of the furnace body;

The support assembly includes a loading platform and a support shaft. The loading platform is located in the furnace cavity and is used to place the crucible. One end of the support shaft is connected to the bottom of the loading platform, and the other end extends out of the furnace cavity from the lower end of the furnace body.

A lifting drive mechanism is used to drive the furnace body and/or the support assembly to lift the furnace body relative to the support assembly;

A flow stabilizing plate is located in the furnace cavity and is spaced apart above the loading platform. The flow stabilizing plate can be raised and lowered relative to the furnace body along with the loading platform; and

The cooling ring is arranged in the furnace cavity. A through hole is formed in the middle of the cooling ring for the carrier and the support shaft to pass through. A cooling channel for the flow of refrigerant is formed inside the cooling ring. The cooling ring is connected to the outside of the furnace body through the first pipeline and the second pipeline.

In an optional embodiment, the single crystal growth equipment includes a cooling source connected to the first pipeline.

In an optional embodiment, the cooling source forms a cooling circuit through the first pipeline, the second pipeline and the cooling ring.

In an optional embodiment, the refrigerant can be water, and the cooling source includes a chiller.

In an optional embodiment, the heating assembly includes a first heating assembly and a second heating assembly, the first heating assembly is arranged above the second heating assembly at an interval, and the cooling ring is arranged between the first heating assembly and the second heating assembly.

In an optional embodiment, a first insulation member is provided in the furnace body, the first insulation member protrudes from the inner wall of the furnace cavity, and extends along the circumference of the furnace cavity to form a ring shape. A through hole is formed in the middle of the first insulation member for the loading platform and the supporting shaft to pass through. The first insulation member is located between the first heating component and the second heating component in the vertical direction, the cooling ring is located at the lower end of the first heating component, the first insulation member is located at the upper end of the second heating component, and the cooling ring is arranged at intervals above the first insulation member.

In an optional embodiment, a second insulation member is provided in the furnace body, the second insulation member protrudes from the inner wall of the furnace cavity and extends along the circumference of the furnace cavity to form a ring shape, a through hole is formed in the middle of the second insulation member for the loading platform and the support shaft to pass through, and the second insulation member is arranged below the second heating assembly.

In an optional embodiment, the diameter of the through hole of the second thermal insulation component is adjustable.

In an optional embodiment, the outer peripheral side of the flow plate is slidably connected to the inner wall of the furnace body so that the flow plate can be raised and lowered relative to the furnace body.

In an optional embodiment, the single crystal growth apparatus further includes a rotation drive mechanism, which is operatively connected to the support shaft and is used to drive the support shaft to rotate.

The beneficial effects of the embodiments of the present invention include, for example:

The single crystal growth equipment provided by the present invention includes a furnace body, a support assembly, a lifting drive mechanism, a flow stabilizing plate, and a cooling ring. The furnace body forms a furnace cavity, and a heating assembly is provided on the inner side of the furnace body. The support assembly includes a loading platform and a supporting shaft. The loading platform is located in the furnace cavity and is used to place the crucible. One end of the supporting shaft is connected to the bottom of the loading platform, and the other end extends out of the furnace cavity from the lower end of the furnace body. The lifting drive mechanism is used to drive the furnace body and/or the support assembly to lift the furnace body relative to the support assembly. The flow stabilizing plate is located in the furnace cavity and is arranged at intervals above the loading platform. It can be lifted and lowered relative to the furnace body along with the loading platform. The cooling ring is installed within the furnace cavity. A through-hole is formed in the center of the ring for the stage and support shaft to pass through. A cooling channel is formed within the ring for the refrigerant to flow through. The cooling ring is connected to the exterior of the furnace via a first and second pipeline. Refrigerant is introduced into the cooling ring through the first pipeline, removing heat before exiting the furnace through the second pipeline. This creates a temperature gradient within the furnace cavity, which is controlled by controlling the refrigerant flow rate. The single crystal growth equipment of the present invention can effectively control the temperature field in the furnace chamber, providing a suitable temperature gradient for crystal growth. Therefore, the crystallization rate can be kept within a reasonable range rather than being too fast, which is conducive to the discharge of impurities to the top of the crystal and ensuring the quality of crystal growth. Therefore, the single crystal growth equipment provided by the present invention is conducive to the preparation of large-sized crystals. In addition, since a stabilizing plate that can move with the stage is provided, when the stage descends, the stabilizing plate can descend with the stage, so that the space above the crucible is not too large, reducing air flow, and thus the temperature field is more stable, which is conducive to reducing the distribution range of impurities in the crystal, improving the quality of crystal growth, and creating good conditions for the growth of large-sized crystals. In addition, the installation of a flow stabilizing plate reduces gas convection, thereby reducing the power required to maintain the temperature of the crucible space, which helps reduce the energy consumption of the single crystal growth equipment.

To further clarify the objectives, technical solutions, and advantages of the embodiments of the present invention, the following will provide a clear and complete description of the technical solutions of the embodiments of the present invention, in conjunction with the accompanying drawings. Obviously, the described embodiments are only some of the embodiments of the present invention, not all of them. Generally, the components of the embodiments of the present invention described and illustrated in the drawings herein can be arranged and designed in a variety of different configurations.

Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without inventive effort are also within the scope of protection of the present invention.

It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, it does not need to be further defined or explained in the subsequent drawings.

In the description of the present invention, it should be noted that if the terms "upper", "lower", "inside", "outside", etc. appear to indicate directions or positional relationships, they are based on the directions or positional relationships shown in the accompanying drawings, or the directions or positional relationships in which the product of the present invention is usually placed when in use. These are merely for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or component referred to must have a specific direction, be constructed and operate in a specific direction. Therefore, they should not be understood as limitations on the present invention.

In addition, the terms "first", "second", etc. are only used to distinguish the description and should not be understood as indicating or implying relative importance.

It should be noted that, without conflict, the features of the embodiments of the present invention can be combined with each other.

During the crystal growth process, if the growth temperature gradient is inappropriate or growth acceleration occurs, the crystal is prone to excessive inclusions and poor impurity removal. However, the current descent method single crystal growth equipment in related technologies cannot effectively control the temperature gradient of crystal growth. Therefore, it often requires very high purity of the raw materials and cannot have too many impurities, resulting in high costs. In the middle and late stages of the preparation of large-sized single crystals, the crystallization gradient often becomes smaller due to the increased thermal conductivity of the crystal itself, or even overcooling, resulting in growth acceleration. Therefore, existing equipment and methods make it difficult to produce high-quality large-sized single crystals. In addition, as the crucible descends, the top space gradually increases, and the air convection becomes more intense, resulting in an unstable temperature field. Crystal growth requires a stable temperature field, while an unstable temperature field can easily lead to poor crystal growth quality, such as widespread impurity distribution. Furthermore, as the furnace cavity space above the crucible increases, the equipment power required to maintain the appropriate temperature increases, resulting in higher energy consumption in single crystal growth equipment used in related technologies.

To address at least one of the shortcomings of the aforementioned related technologies, an embodiment of the present invention provides a single crystal growth apparatus. By adding a cooling ring and a flow stabilizing plate within the furnace chamber, a suitable temperature field is formed within the furnace chamber, improving the stability of the flow field, thereby enhancing the quality of crystal growth and providing favorable conditions for the preparation of large-sized crystals.

Figure 1 is a schematic diagram of a single crystal growth apparatus 010 according to an embodiment of the present invention; Figure 2 is a cross-sectional view of the single crystal growth apparatus 010 according to an embodiment of the present invention. As shown in Figures 1 and 2, the single crystal growth apparatus 010 provided in this embodiment of the present invention includes a furnace body, a support assembly 200, a lifting drive mechanism 300, a flow stabilizing plate 170, and a cooling ring 140. The furnace body forms a furnace cavity, and a heating assembly is disposed inside the furnace body. The support assembly 200 includes a stage 210 and a support shaft 220. The stage 210 is located within the furnace cavity and is used to place the crucible 020. One end of the support shaft 220 is connected to the bottom of the stage 210, and the other end extends from the bottom end of the furnace body out of the furnace cavity. The lifting drive mechanism 300 is used to drive the furnace body and/or support assembly 200, raising and lowering the furnace body relative to the support assembly 200. A cooling ring 140 is located within the furnace cavity. A through-hole is formed in the center of the cooling ring 140 for the stage 210 and support shaft 220 to pass through. A cooling channel is formed within the cooling ring 140 for the flow of refrigerant. The cooling ring 140 is connected to the exterior of the furnace body via a first pipeline and a second pipeline. A flow stabilizing plate 170 is located within the furnace cavity and spaced apart above the stage 210, allowing it to be raised and lowered relative to the furnace body.

In this embodiment, the furnace body comprises an upper furnace body 110 and a lower furnace body 120. The upper and lower furnace bodies 110 and 120 are axially connected to form a furnace cavity. The lower furnace body 120 has an opening at its bottom end, through which the lower end of the support shaft 220 extends. Both the upper and lower furnace bodies 110 and 120 contain insulation material to maintain the temperature within the furnace cavity.

In this embodiment, the heating assembly includes a first heating assembly 111 and a second heating assembly 121, with the first heating assembly 111 spaced apart above the second heating assembly 121. Both the first heating assembly 111 and the second heating assembly 121 include multiple heating elements spaced apart circumferentially, thereby creating a uniform temperature field. The heating elements in the first heating assembly 111 and the second heating assembly 121 can be either induction coils or resistors.

Optionally, cooling ring 140 is positioned vertically between first heating assembly 111 and second heating assembly 121. The cooling ring can be annular, with its central axis coinciding with the central axis of the furnace cavity. Specifically, cooling ring 140 is positioned at the lower end of first heating assembly 111. The raw material in crucible 020 is heated to a molten state by first heating assembly 111. The molten raw material in crucible 020 begins to crystallize as it descends near cooling ring 140. A refrigerant is continuously supplied to cooling ring 140 via first pipeline 141. The refrigerant absorbs heat from the furnace cavity and then flows out of the furnace cavity via second pipeline 142. By controlling the flow of the refrigerant, the temperature near the cooling ring 140 in the furnace cavity can be controlled, creating a suitable temperature field for crystallization. The refrigerant can be a gas or a liquid, for example, nitrogen, air, water, or oil.

Optionally, single crystal growth apparatus 010 further includes a cooling source (not shown), which is connected to the first pipeline, thereby continuously providing refrigerant to cooling ring 140 through the first pipeline. Optionally, the cooling source forms a cooling circuit through the first pipeline, the second pipeline, and the cooling ring. The cooling source can be a device that provides cold water, such as a chiller. In one embodiment, the chiller forms a cooling circuit through first pipeline 141, cooling ring 140, and second pipeline 142. The chiller cools water and pumps it through first pipeline 141 to cooling ring 140. The cold water absorbs heat and rises in temperature, then returns to the chiller through second pipeline 142. The chiller cools the water and pumps it back to cooling ring 140, forming a refrigerant circulation loop. By adjusting the cooling power of the chiller and the circulation rate of the refrigerant, the efficiency of the cooling loop 140 in absorbing heat can be adjusted, thereby adjusting the temperature field and further adjusting the temperature gradient of the crystallization.

In alternative embodiments, the cooling source may be connected only to the first pipe 141. After absorbing heat through the cooling ring 140, the refrigerant is released directly through the second pipe 142, thus eliminating the need for a cooling loop. Alternatively, the cooling source may be a faucet, connected only to the first pipe 141. Adjusting the faucet opening adjusts the cooling intensity of the cooling ring 140.

In an optional embodiment, the cooling ring 140 can also be set to be adjustable in up and down positions, such as by achieving height adjustment through a motor and a related transmission structure.

Furthermore, a first insulation member 150 is disposed within the furnace body. The first insulation member 150 protrudes from the inner wall of the furnace cavity and extends circumferentially around the cavity, forming a ring. A through-hole is formed in the center of the first insulation member 150, through which the loading platform 210 and the support shaft 220 pass. The first insulation member 150 is vertically positioned between the first heating assembly 111 and the second heating assembly 121. The central axis of the first insulation member 150 coincides with the central axis of the furnace cavity. In this embodiment, the first insulation member 150 is positioned above the second heating assembly 121, and the cooling ring 140 is intermittently positioned above the first insulation member 150.

As can be seen, the cooling ring 140 and the first insulation element 150 roughly divide the furnace cavity into three zones. The area above the cooling ring 140 is the high-temperature zone, whose temperature is controlled by the first heating assembly 111. The area between the cooling ring 140 and the first insulation element 150 is the transition zone, where the temperature is lower than the high-temperature zone. Typically, molten material begins to crystallize after entering this zone. Below the first insulation element 150 is the annealing zone, whose temperature is controlled by the second heating assembly 121. This zone is used to anneal the crystal to relieve internal stress. Compared to the high-temperature zone, the temperatures in the transition and annealing zones are relatively low.

Furthermore, a second insulation member 160 is installed within the furnace body. This member protrudes from the inner wall of the furnace cavity and extends along the circumference of the furnace cavity, forming a ring. A through-hole is formed in the center of the second insulation member 160 for the loading platform 210 and support shaft 220 to pass through. The second insulation member 160 is positioned below the second heating assembly 121. The annealing zone is located between the first insulation member 150 and the second insulation member 160. Alternatively, the second insulation member 160 is positioned at the opening of the lower furnace body 120.

In this embodiment, the diameter of the through-hole of the second heat-insulating element 160 is adjustable. Since the lower end of the through-hole of the second heat-insulating element 160 is connected to the external environment, adjusting the diameter of the second heat-insulating element 160 can adjust the temperature field in the annealing zone to a certain extent, thereby controlling the annealing process. A smaller diameter can reduce convection between the external air and the air inside the furnace, which is conducive to increasing the annealing temperature; a larger diameter can facilitate the removal of crucible 020.

Both the first insulation member 150 and the second insulation member 160 can be made of insulation bricks. The second insulation member 160 can be composed of multiple separate components to achieve adjustable caliber. For example, the second insulation member 160 can be designed as a multi-piece structure similar to an aperture.

In this embodiment of the present invention, a plurality of thermocouples are provided on the furnace body for detecting the temperature in the furnace cavity.

Specifically, the plurality of thermocouples include, from top to bottom, a high-temperature monitoring thermocouple 131, a high-temperature control thermocouple 132, a first crystallization monitoring thermocouple 133, a second crystallization monitoring thermocouple 134, an annealing monitoring thermocouple 135, and an annealing control thermocouple 136. In this embodiment, the high-temperature control thermocouple 132 is located in the middle of the high-temperature zone. By comparing the set high-temperature zone target temperature with the detected temperature of the high-temperature control thermocouple 132, the first heating assembly 111 is controlled to regulate the temperature of the high-temperature zone. In other words, whether the high-temperature zone reaches the target temperature is determined by the temperature feedback from the high-temperature control thermocouple 132. First and second crystallization monitoring thermocouples 133 and 134 are located on the upper and lower sides of cooling ring 140, respectively, to monitor crystallization temperature conditions. Crystallization of the melt begins near cooling ring 140. The second heating assembly 121 regulates the annealing zone temperature by comparing the set annealing zone target temperature with the temperature detected by annealing temperature-control thermocouple 136. In other words, whether the annealing zone has reached the target temperature is determined by the temperature feedback from annealing temperature-control thermocouple 136. Annealing monitoring thermocouple 135 is located on the lower side of second heating assembly 121. By detecting the temperature at different positions of the entire furnace cavity through various thermocouples, the temperature field of the furnace cavity can be effectively monitored.

In this embodiment, the lifting drive mechanism 300 is operatively connected to the furnace body and is used to drive the furnace body up and down relative to the support assembly 200. By driving the furnace body to move, the crucible 020 on the stage 210 is placed in a more stable state, thereby ensuring better crystallization. In alternative embodiments, the lifting drive mechanism 300 can also be operatively connected to the support assembly 200, while the furnace body remains stationary. The crucible 020 can be raised and lowered relative to the furnace body by driving the support assembly 200 up and down.

Optionally, the lifting drive mechanism 300 includes a drive member 310 and a transmission assembly 320, which connects the drive member 310 to the furnace body. The drive member 310 can be a motor, such as a stepper motor. The transmission assembly 320 can include a screw-nut assembly to achieve the lifting and lowering of the furnace body.

Furthermore, single crystal growth apparatus 010 includes a rotary drive mechanism 230, which is rotatably connected to support shaft 220 and is used to drive support shaft 220 to rotate. By rotating crucible 020 with stage 210 before crystallization, the raw materials are fully melted, thereby more effectively distributing impurities on the crystal surface.

In this embodiment, the flow stabilizing plate 170 is capable of moving up and down relative to the furnace body. During the crystal growth process, it can rise and fall synchronously with the crucible 020 relative to the furnace body. Specifically, the movement range of the flow stabilizing plate 170 relative to the furnace body is limited to the high-temperature zone, namely, the area between the top of the furnace cavity and the cooling ring 140. The flow stabilizing plate 170 moves with the crucible 020 during the crystal growth process. Therefore, before it reaches the cooling ring 140, the space above the crucible 020 does not expand due to the crucible 020 descending relative to the furnace body. Therefore, there is no significant air convection, which is beneficial to the stability of the temperature field near the crucible 020. At the same time, according to the law of conservation of energy, due to the insulating effect of the flow stabilizing plate 170, the heat required to maintain a stable temperature field near the crucible 020 is relatively small (compared to the case where there is no flow stabilizing plate 170 and the space above the crucible 020 is larger), which is beneficial to reducing the energy consumption of the equipment.

Optionally, the outer periphery of the flow stabilizing plate 170 is slidably connected to the inner wall of the furnace body, allowing the flow stabilizing plate 170 to be raised and lowered relative to the furnace body. For example, a slider is provided on the outer periphery of the flow stabilizing plate 170, and a chute is provided on the inner wall of the furnace body. The lower surface of the flow stabilizing plate 170 abuts the top of the crucible 020, allowing the flow stabilizing plate 170 to rise and fall with the crucible 020. Alternatively, the flow stabilizing plate 170 can be circular, maintaining a gap between it and the inner wall of the furnace body. In other optional embodiments, the flow stabilizing plate 170 can also be connected to a drive assembly, which drives the flow stabilizing plate 170 to rise and fall relative to the furnace body.

The method of using the single crystal growth apparatus 010 provided in the embodiment of the present invention is as follows:

First, place a seed crystal at the bottom of crucible 020, then load the raw material into crucible 020, secure the lid, and place crucible 020 on stage 210. Based on the normal crystal growth temperature, the first heating assembly 111 raises the high-temperature zone to the target temperature to completely melt the raw material. During the early stages of crystal growth, the rotation drive mechanism 230 can be controlled to maintain a rotation speed of 0-30 rpm in crucible 020 to fully melt the raw material. Once crystal growth begins, rotation is stopped to keep crucible 020 stable.

After the raw materials are fully melted, the lifting drive mechanism 300 is controlled to slowly move the furnace upward at the set growth rate. Crucible 020 then slowly descends relative to the furnace, and refrigerant is continuously introduced into the cooling ring 140. When the temperature field has an appropriate temperature gradient, the furnace body is moved upward, allowing the top of the seed crystal to slowly contact the melt through the solid-liquid interface. By moving the furnace body upward, the melt passes through the cooling ring 140. During this process, the flow plate 170 simultaneously descends with the crucible 020, preventing rapid heat dissipation due to the upward movement of the furnace body, which would increase equipment power and cause temperature fluctuations due to the increased convection space in the furnace cavity. The crystallization temperature can be monitored by the first crystallization monitoring thermocouple 133 and the second crystallization monitoring thermocouple 134. By controlling the refrigerant flow of the cooling ring 140, a suitable crystallization temperature gradient is always formed. The cooling ring 140 can also be appropriately adjusted up and down according to the required crystal growth length.

When crucible 020 enters below first heat preservation part 150, the crystal enters annealing zone. Annealing monitoring thermocouple 135 can monitor whether the temperature of annealing zone is suitable for crystal annealing. At the same time, annealing temperature control thermocouple 136 and second heating assembly 121 can adjust the annealing temperature.

The diameter of the second heat-insulating element 160 can be adjusted based on the annealing temperature. Optionally, during the initial descent of the crucible 020, the distance between the inner edge of the through-hole of the second heat-insulating element 160 and the support shaft 220 is less than 10 mm. After the annealing temperature reaches the set point, the distance between the inner edge of the through-hole of the second heat-insulating element 160 and the support shaft 220 is controlled to be between 10 and 30 mm. This distance can be adjusted based on the difference between the actual temperature and the annealing temperature.

Optionally, according to production needs, the single crystal growth equipment 010 of the present invention can be made into an array of multiple stations for batch production.

The single crystal growth apparatus 010 provided in this embodiment of the present invention can effectively meet the temperature gradient required by various crystals by adjusting the amount of heat removed by the cooling ring 140, thereby producing high-quality crystals. By adjusting the cooling ring 140, the temperature gradient required in the early, middle, and late stages of crystal growth can be effectively adjusted, effectively removing impurities, and thus producing large-sized crystals. Due to the flow stabilizing plate 170 installed in the furnace chamber, it can stabilize the temperature field during the growth process of large-sized crystals, especially in the middle and late stages, providing a stable temperature field for crystal growth, thereby enabling the production of large-sized crystals. Because flow stabilizing plate 170 provides a stable temperature field during crystal preparation, it facilitates impurity removal and improves crystal quality. During the raw material melting process, the effective rotation of the rotary support shaft 220 ensures that the raw material is fully melted, effectively distributing impurities on the crystal surface. Furthermore, during the growth process, the stable temperature field provided by flow stabilizing plate 170 allows impurities to be more effectively discharged to the top of the crystal. The installation of flow stabilizing plate 170 also effectively reduces excessive energy consumption in the later stages of crystal preparation.

The following two experimental examples illustrate the effectiveness of the cooling ring 140 and the flow stabilizing plate 170 in the single crystal growth equipment 010 of the embodiment of the present invention.

1. Take the preparation of CNGS (Ca3NbGa3Si2O14) crystals as an example. Crucible 020 is 300mm long, the furnace chamber is 400mm high, the crystal growth length is 180mm, and the growth temperature is 1330°C (i.e., high-temperature thermocouple 132 is set to 1387°C, ensuring the inoculation temperature is 50°C above the melting point).

The measured data when the cooling ring 140 is not installed (it is replaced by insulation bricks) and the flow plate 170 is as follows:

During the crystallization stage, the temperature measured by the high-temperature monitoring thermocouple 131 was 1487°C, the temperature measured by the first crystallization monitoring thermocouple 133 was 1380°C, and the temperature measured by the second crystallization monitoring thermocouple 134 was 1243°C. The power was 2.46KW.

When the crystal grew to 80 mm, the temperature measured by high-temperature monitoring thermocouple 131 was 1492°C, the temperature of the first crystal monitoring thermocouple 133 was 1367°C, and the temperature of the second crystal monitoring thermocouple 134 was 1252°C. The power was 2.67 kW. Macroscopically, the crystal was crystal clear and showed no abnormalities. Laser observation of the interior of the crystal revealed no optical path, indicating that the crystal had good impurity removal.

When the crystal grew to 130 mm, the temperature measured by high-temperature monitoring thermocouple 131 was 1513°C, the temperature of the first crystal monitoring thermocouple 133 was 1356°C, and the temperature of the second crystal monitoring thermocouple 134 was 1263°C. The power was 3.12 kW. Laser observation of the interior of the crystal revealed tiny bubbles starting at 116 mm, but these bubbles were primarily distributed on the outer surface.

When the crystal grew to 180 mm, the temperature measured by high-temperature monitoring thermocouple 131 was 1532°C, the temperature of the first crystal monitoring thermocouple 133 was 1338°C, and the temperature of the second crystal monitoring thermocouple 134 was 1275°C. The power was 3.98 kW. Laser observation of the interior of the crystal revealed that impurities gradually expanded toward the center of the crystal from 142 mm. Bubbles on the outer surface of the crystal and impurities within the crystal were more obvious.

Figure 3 shows a CNGS crystal grown without the cooling ring 140 and the flow stabilizing plate 170. As shown in Figure 3, impurities are more noticeable at the top of the crystal (the boxed area in Figure 3).

After installing the cooling ring 140 and the stabilizing plate 170, the measured data are as follows:

During the crystallization stage, the temperature measured by the high-temperature monitoring thermocouple 131 was 1483°C, the temperature of the first crystallization monitoring thermocouple 133 was 1376°C, the temperature of the second crystallization monitoring thermocouple 134 was 1196°C, and the power was 2.31KW.

When the crystal grew to 80 mm, the temperature measured by high-temperature monitoring thermocouple 131 was 1485°C, the temperature of the first crystal monitoring thermocouple 133 was 1373°C, and the temperature of the second crystal monitoring thermocouple 134 was 1193°C. The power was 2.38 kW. Laser observation of the interior of the crystal revealed no optical path, indicating that the crystal's impurity removal was effective and indistinguishable from that obtained without the cooling ring and flow stabilizer.

When the crystal grew to 130 mm, the temperature measured by high-temperature monitoring thermocouple 131 was 1489°C, the temperature of the first crystal monitoring thermocouple 133 was 1367°C, and the temperature of the second crystal monitoring thermocouple 134 was 1187°C. The power was 2.52 kW. Laser observation of the interior of the crystal also revealed no impurities.

When the crystal grew to 180 mm, the temperature measured by high-temperature monitoring thermocouple 131 was 1492°C, the temperature of the first crystallization monitoring thermocouple 133 was 1362°C, and the temperature of the second crystallization monitoring thermocouple 134 was 1183°C. The power was 2.78 kW. Laser observation showed that bubbles and impurities began to appear above 173 mm in the crystal. Below 173 mm, no impurities or bubbles were found inside the crystal, indicating that the overall growth quality of the crystal was good and the decontamination effect was significant.

Figure 4 shows a CNGS crystal grown using single crystal growth apparatus 010 according to an embodiment of the present invention. As shown in Figure 4, some impurities only appear above 173 mm (the area within the square and circular boxes in Figure 4).

From the above data comparison, it can be seen that when the cooling ring 140 and the stabilizing plate 170 are not provided, the power increases as the length of the crystal growth increases, and energy consumption increases. At the same time, as the space in the high-temperature zone becomes larger and larger, heat is continuously dissipated upward, and spatial convection is enhanced. The temperature measured in the high-temperature zone is a dynamic temperature, so the temperature is relatively high. During the crystal growth and crystallization process, the first crystal monitoring thermocouple 133 will increase thermal conductivity as the crystal growth length increases, and the temperature gradually decreases. At the same time, the second crystal monitoring thermocouple 134 is located in the area where the crystal is located after crystallization. Due to the diffusion of the crystal's own latent heat, the temperature of this area gradually increases, which ultimately leads to a smaller gradient and a poorer impurity removal ability.

In contrast, with cooling ring 140 and stabilizing plate 170 installed, power is lower during the crystal formation phase because cooling ring 140 removes some heat. However, as crystal growth gradually begins, power becomes more stable, with less fluctuation. In the high-temperature zone, stabilizing plate 170 reduces convection within the furnace cavity, resulting in less temperature fluctuation in the thermocouples. Furthermore, the first and second crystal monitoring thermocouples 133 and 134 maintain relatively low temperatures during the initial stages of crystal formation due to the cooling ring 140, but experience relatively less fluctuation in the later stages. From a gradient perspective, although the installation of cooling ring 140 and stabilizing plate 170 resulted in some fluctuations in the gradient in the later stages of crystal preparation, these fluctuations were minimal and acceptable compared to the previous stage. This effective control of the gradient during crystal growth, ensuring a stable state, is crucial for producing large-scale crystals.

2. Take the preparation of TeO2 crystals as an example. Crucible 020 is 300mm long, the furnace chamber is 400mm high, the crystal growth length is 180mm, and the growth temperature is 733°C (high temperature control thermocouple 132 is set to 780°C).

The measured data without the cooling ring 140 (replaced with insulation bricks) and the flow plate 170 are as follows:

During the crystallization stage, the temperature measured by the high-temperature monitoring thermocouple 131 was 865°C, the temperature of the first crystallization monitoring thermocouple 133 was 772°C, the temperature of the second crystallization monitoring thermocouple 134 was 618°C, and the power was 1.92KW.

When the crystal grew to 80 mm, the temperature measured by high-temperature monitoring thermocouple 131 was 876°C, the temperature of the first crystal monitoring thermocouple 133 was 765°C, and the temperature of the second crystal monitoring thermocouple 134 was 624°C. The power was 2.13 kW. Laser observation of the crystal revealed no impurities or bubbles.

When the crystal grew to 130 mm, the temperature measured by high-temperature monitoring thermocouple 131 was 891°C, the temperature of the first crystallization monitoring thermocouple 133 was 753°C, and the temperature of the second crystallization monitoring thermocouple 134 was 633°C. The power was 2.36 kW. Laser observation of the crystal revealed tiny bubbles starting at 123 mm, forming on the crystal surface.

When the crystal grew to 180 mm, the temperature measured by high-temperature monitoring thermocouple 131 was 904°C, the temperature of the first crystal monitoring thermocouple 133 was 741°C, and the temperature of the second crystal monitoring thermocouple 134 was 645°C. The power was 2.84 kW. Laser observation of the interior of the crystal revealed a faint optical path starting at 156 mm. At 159 mm, bubbles began to appear on the outer surface of the crystal, along with internal impurities. The impurities were concentrated within 10 mm below the top of the crystal.

Figure 5 shows a _TeO2 crystal grown without the cooling ring 140 and the stabilizing plate 170. As shown in Figure 5, impurities begin to appear in the crystal at and above 159 mm (the area within the box in Figure 5).

After installing the cooling ring 140 and the flow stabilizing plate 170, the measured data are as follows:

During the crystallization stage, the temperature measured by the high-temperature monitoring thermocouple 131 was 863°C, the temperature of the first crystallization monitoring thermocouple 133 was 776°C, the temperature of the second crystallization monitoring thermocouple 134 was 626°C, and the power was 1.81KW.

When the crystal grew to 80 mm, the temperature measured by high-temperature monitoring thermocouple 131 was 865°C, the temperature of the first crystallization monitoring thermocouple 133 was 774°C, and the temperature of the second crystallization monitoring thermocouple 134 was 624°C. The power was 1.89 kW. Laser observation of the crystal revealed no impurities or bubbles.

When the crystal grew to 130 mm, the temperature measured by high-temperature monitoring thermocouple 131 was 867°C, the temperature of the first crystal monitoring thermocouple 133 was 772°C, and the temperature of the second crystal monitoring thermocouple 134 was 622°C. The power was 2.11 kW. Laser observation of the interior of the crystal revealed no impurities.

When the crystal grew to 180 mm, the temperature measured by high-temperature monitoring thermocouple 131 was 871°C, the temperature of the first crystal monitoring thermocouple 133 was 771°C, and the temperature of the second crystal monitoring thermocouple 134 was 621°C. The power was 2.35 kW. Laser observation of the interior of the crystal revealed a faint optical path starting at 173 mm. Single-wire cutting of the crystal revealed bubbles. A large amount of impurities appeared from 175 mm to the top of the crystal.

Figure 6 shows a _TeO2 crystal grown using the single crystal growth apparatus 010 according to an embodiment of the present invention. As shown in Figure 6, impurities begin to appear in the crystal at and above 175 mm (the area within the box in Figure 6).

As can be seen from the above data comparison, the single crystal growth apparatus provided by the present invention is equally effective in producing TeO2 crystals. Due to the relatively low temperature required, the energy savings are not as significant as those achieved with high-temperature crystals. However, the impurity removal effects demonstrated in producing large-scale crystals are equally crucial and important.

The two experimental examples above show that when using insulation bricks instead of cooling rings 140 and without stabilizing plates 170, the crystal growth rate remains relatively stable during the initial growth phase. However, as the crystal grows to approximately 140 mm, impurities on the surface of the crystal increase due to the crystal's inherent impurity removal capabilities becoming increasingly poor and, due to factors such as the crystal's own thermal conductivity, the crystal's surface impurities become increasingly numerous. This limits the size of the produced crystals, making it impossible to produce high-quality, large-sized crystals. Using cooling rings 140, the temperature gradient required by the crystal type can be effectively adjusted through cooling rings 140, ensuring that the desired temperature gradient is achieved in the early, middle, and late stages of crystal growth. This facilitates the production of large, high-quality single crystals. As the crystal grows to 80 mm, the furnace cavity space becomes larger and the fluidity caused by air convection becomes stronger, causing the temperature measured by high-temperature monitoring thermocouple 131 to gradually rise. Because the temperature setting of high-temperature control thermocouple 132 is constant, according to the law of conservation of energy, the equipment needs to provide higher power to maintain this temperature balance, so energy consumption gradually increases in the later stages of growth. With the flow stabilizing plate 170 in place, the temperature of the furnace cavity high-temperature monitoring thermocouple 131 does not fluctuate much during the initial crystal growth stage because the top space is limited. The data reveals that while the temperature of high-temperature monitoring thermocouple 131 rose slightly at the 80mm, 130mm, and 180mm crystal growth stages, the relatively poor air flow at the top of the furnace chamber due to the presence of flow stabilizer 170 above crucible 020 led to smaller temperature fluctuations compared to when flow stabilizer 170 was not in place. Comparing the power changes on the control equipment's power meter reveals that with flow stabilizer 170 in place, power consumption was lower in the middle and late stages of crystal growth.

The above are merely specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications or substitutions that a person skilled in the art could easily conceive of within the technical scope disclosed herein should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be based on the scope of protection of the patent application.

010: Single Crystal Growth Equipment 020: Crucible 110: Upper Furnace 111: First Heating Assembly 120: Lower Furnace 121: Second Heating Assembly 131: High-Temperature Monitoring Thermocouple 132: High-Temperature Control Thermocouple 133: First Crystallization Monitoring Thermocouple 134: Second Crystallization Monitoring Thermocouple 135: Annealing Monitoring Thermocouple 136: Annealing Control Thermocouple 140: Cooling Ring 141: First Pipeline 142: Second Pipeline 150: First Insulation Component 160: Second Insulation Component 170: Flow Stabilizer 200: Support Assembly 210: Stage 220: Support shaft 230: Rotary drive mechanism 300: Lifting drive mechanism 310: Drive element 320: Transmission assembly

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without any creative effort.

Figure 1 is a schematic diagram of a single crystal growth apparatus in an embodiment of the present invention; Figure 2 is a cross-sectional view of the single crystal growth apparatus in an embodiment of the present invention; Figure 3 shows a CNGS crystal grown without a cooling ring and a stabilizing plate; Figure 4 shows a CNGS crystal grown by the single crystal growth apparatus in an embodiment of the present invention; Figure 5 shows a _TeO2 crystal grown without a cooling ring and a stabilizing plate; and Figure 6 shows a _TeO2 crystal grown by the single crystal growth apparatus in an embodiment of the present invention.

020: Crucible

110: Upper furnace body

111: First heating component

120: Lower furnace body

121: Second heating component

131: High temperature monitoring thermocouple

132: High temperature control thermocouple

133: First crystal monitoring thermocouple

134: Second crystal monitoring thermocouple

135: Annealing monitoring thermocouple

136: Annealing temperature control thermocouple

140: Cooling Ring

141: First pipeline

142: Second pipeline

150: First insulation component

160: Second insulation component

170: Flow stabilizer

200: Support assembly

210: Stage

220: Support shaft

230: Rotary drive mechanism

300: Lifting drive mechanism

310: Drive parts

320: Transmission components

Claims (10)

A single crystal growth apparatus is characterized by comprising: a furnace body, the furnace body forming a furnace cavity, a heating assembly disposed inside the furnace body; a support assembly, comprising a carrier and a support shaft, the carrier being located within the furnace cavity and used to place a crucible, one end of the support shaft being connected to the bottom of the carrier and the other end extending out of the furnace cavity from the lower end of the furnace body; a lifting drive mechanism for driving the furnace body and/or the support assembly to cause the furnace body to rise and fall relative to the support assembly; a flow stabilizing plate, located within the furnace cavity and spaced apart above the carrier, the flow stabilizing plate being capable of rising and falling relative to the furnace body along with the carrier; and A cooling ring is disposed within the furnace cavity. A through hole is formed in the center of the cooling ring for the stage and the support shaft to pass through. A cooling channel is formed inside the cooling ring for the flow of refrigerant. The cooling ring is connected to the outside of the furnace body through a first pipeline and a second pipeline. The single crystal growth apparatus as described in claim 1 is characterized in that the single crystal growth apparatus includes a cooling source connected to the first pipeline. The single crystal growth apparatus as described in claim 2 is characterized in that the cooling source forms a cooling circuit through the first pipeline, the second pipeline and the cooling ring. The single crystal growth apparatus as described in claim 3 is characterized in that the refrigerant is water and the cooling source includes a chiller. The single crystal growth device as described in claim 1 is characterized in that the heating component includes a first heating component and a second heating component, the first heating component is arranged above the second heating component at intervals, and the cooling ring is arranged between the first heating component and the second heating component. The single crystal growth equipment as described in claim 5 is characterized in that a first heat-insulating member is provided in the furnace body, the first heat-insulating member is protruded from the inner wall of the furnace cavity and extends along the circumference of the furnace cavity to form a ring shape, a through hole is formed in the middle of the first heat-insulating member for the worktable and the support shaft to pass through, the first heat-insulating member is located between the first heating component and the second heating component in the vertical direction, the cooling ring is located at the lower end of the first heating component, the first heat-insulating member is located at the upper end of the second heating component, and the cooling ring is arranged at intervals above the first heat-insulating member. The single crystal growth equipment as described in claim 6 is characterized in that a second thermal insulation member is provided in the furnace body, the second thermal insulation member is protruded from the inner wall of the furnace cavity and extends along the circumference of the furnace cavity to form a ring shape, a through hole is formed in the middle of the second thermal insulation member for the worktable and the support shaft to pass through, and the second thermal insulation member is arranged below the second heating assembly. The single crystal growth apparatus as described in claim 7 is characterized in that the diameter of the through hole of the second heat-insulating member is adjustable. The single crystal growth apparatus as claimed in claim 1 is characterized in that the outer peripheral side of the flow stabilizing plate is slidably connected to the inner wall of the furnace body so that the flow stabilizing plate can be raised and lowered relative to the furnace body. The single crystal growth apparatus as described in claim 1 is characterized in that the single crystal growth apparatus further includes a rotation drive mechanism, which is transmission-connected to the support shaft and is used to drive the support shaft to rotate.