A crystal growth method, apparatus and crystal

Abstract

The application discloses a crystal growth method, a device and a crystal, relates to the technical field of crystal growth, and solves the problem of macro defects such as inclusions, cloud layers and bubbles in a crystal caused by temperature gradient change in the process of growing the crystal by using a pulling method in the prior art. The crystal growth method comprises the following steps: in the process of growing the crystal by using the pulling method, the relative downward movement of an induction coil to a crucible is controlled, and the relative downward movement of the induction coil to the crucible is controlled, and the movement is carried out at different speeds. The scheme can smoothly adjust the relative position of the crucible and the induction coil, adjust the temperature change above the melt liquid level in the crucible, make the temperature gradient of the crystal growth interface consistent with the initial state, provide a continuous and stable temperature field environment for the crystal growth, avoid defects in the process of growing the crystal, greatly improve the yield of the blank and the material utilization rate, and thus reduce the cost of related products.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of crystal growth, in particular to a crystal growth method, device and crystal. BACKGROUND

[0002] The Czochralski method is a traditional melt growth method, which is often used to grow crystal materials with high melting point but not easy to volatilize. The main process includes the following steps: 1, melting, the metal crucible is heated by the eddy current effect of the intermediate frequency current coil, so that the raw materials in the crucible are melted into a melt; 2, seeding, inserting a directional seed crystal into the melt to guide the directionality of the melt crystallization; 3, shoulder, accelerating the crystal crystallization rate by heating power control or melt temperature control, so that the diameter of the crystal is gradually enlarged; 4, equal diameter, controlling the growth rate of the crystal so that the crystal blank is a uniform cylinder; 5, finishing, after the equal diameter part is grown, the crystal growth rate is reduced, so that the diameter of the blank is reduced until it is separated from the melt, and the crystal blank is taken out after cooling.

[0003] In the process of crystal growth, a relatively stable temperature field condition is required, and if there is a large change, macroscopic defects such as inclusions, clouds, bubbles, etc. will appear in the crystal. However, as the melt in the crucible is continuously converted into a crystal blank, the liquid level of the melt will gradually decrease, and the crystallization interface and temperature gradient of the crystal growth will naturally change. The common phenomenon is that the quality of the finishing section of the crystal blank is significantly worse than that of the shoulder section, and the above-mentioned macroscopic defects are more likely to occur.

[0004] In view of this problem, some existing technologies use a crucible micro-motion rising scheme, although it has the intention to alleviate internal defects, but since the crucible directly contains liquid melt, the inevitable vibration during the movement will directly affect the interface of the crystal growth, which makes the quality of the crystal blank worse. SUMMARY

[0005] The embodiments of the present application provide a crystal growth method, device and crystal, which can solve the problem of macroscopic defects such as inclusions, clouds, bubbles, etc. in the crystal caused by the change of temperature gradient in the process of growing the crystal by the Czochralski method.

[0006] In a first aspect, a crystal growth method is provided, comprising:

[0007] In the process of growing the crystal by the Czochralski method, the induction coil is controlled to move downward relative to the crucible, and during the process of moving the induction coil downward relative to the crucible, the induction coil is controlled to move at different speeds.

[0008] Optionally, the step of controlling the induction coil to move at different speeds during the process of moving the induction coil downward relative to the crucible comprises:

[0009] controlling the inductive coil to move downward relative to the crucible in a gradually increasing speed trend.

[0010] Optionally, the step of controlling the inductive coil to move downward relative to the crucible in a gradually increasing speed trend comprises:

[0011] controlling the inductive coil to move uniformly with a preset acceleration.

[0012] Optionally, the step of controlling the inductive coil to move downward relative to the crucible in a gradually increasing speed trend comprises:

[0013] controlling the inductive coil to increase in speed when a distance or a time of movement of the inductive coil relative to the crucible reaches a preset condition.

[0014] Optionally, the step of controlling the inductive coil to increase in speed when a distance or a time of movement of the inductive coil relative to the crucible reaches a preset condition comprises:

[0015] controlling the inductive coil to increase in speed by a preset increment when a distance or a time of movement of the inductive coil relative to the crucible increases by a preset threshold; or

[0016] controlling the inductive coil to move at a speed corresponding to a target interval when a distance or a time of movement of the inductive coil relative to the crucible reaches the target interval, wherein the distance or the time of movement of the inductive coil relative to the crucible is divided into a plurality of target intervals in advance, each target interval corresponds to a different speed, and a speed corresponding to a target interval arranged at a rear position is greater than a speed corresponding to a target interval arranged at a front position; or

[0017] controlling the inductive coil to move uniformly with an acceleration corresponding to a target interval when a distance or a time of movement of the inductive coil relative to the crucible reaches the target interval, wherein the distance or the time of movement of the inductive coil relative to the crucible is divided into a plurality of target intervals in advance, each target interval corresponds to a different acceleration, and an acceleration corresponding to a target interval arranged at a rear position is greater than an acceleration corresponding to a target interval arranged at a front position.

[0018] Optionally, in the process of growing a crystal by using the Czochralski method, the step of controlling the inductive coil to move downward relative to the crucible comprises:

[0019] controlling the inductive coil to move downward relative to the crucible when the crystal grown by using the Czochralski method enters an equal-diameter stage.

[0020] stopping the movement of the inductive coil when the crystal growth reaches a set length.

[0021] Optionally, the speed of the inductive coil moving relative to the crucible is greater than or equal to 0.001 mm / h and less than or equal to 0.1 mm / h.

[0022] In a second aspect, a crystal growth apparatus is provided, comprising:

[0023] a growth furnace having a growth furnace cavity therein;

[0024] a crucible disposed in the growth furnace cavity, the crucible being capable of containing a crystal raw material;

[0025] an inductive coil disposed in the growth furnace cavity and surrounding an outer portion of the crucible;

[0026] an inductive coil driving mechanism connected to the inductive coil, the inductive coil driving mechanism being capable of driving the inductive coil to move downward relative to the crucible at different speeds during crystal growth.

[0027] Optionally, the inductive coil driving mechanism comprises a support, a micro-motion platform, and a motion mechanism.

[0028] The support is disposed below the inductive coil, one end of the support being connected to the inductive coil and the other end of the support passing through an opening in a bottom portion of the growth furnace and being connected to the micro-motion platform, wherein the bottom portion of the growth furnace is provided with the opening for the support to pass through.

[0029] The micro-motion platform is disposed below the growth furnace, one side of the micro-motion platform being connected to the support and the other side of the micro-motion platform being connected to the motion mechanism.

[0030] The motion mechanism is disposed below the micro-motion platform and is capable of moving the micro-motion platform, and when the micro-motion platform moves, the support and the inductive coil connected to the support are moved.

[0031] Optionally, the motion mechanism and the micro-motion platform are connected through a transmission mechanism.

[0032] Optionally, the crystal growth apparatus further comprises:

[0033] a holding furnace cavity disposed in the growth furnace cavity, the crucible being disposed in the holding furnace cavity, and the inductive coil surrounding an outer portion of the holding furnace cavity.

[0034] In a third aspect, a crystal grown using the crystal growth method described above is provided.

[0035] In the embodiments of the present application, in the process of growing the crystal by using the pulling method, the relative position between the metal crucible and the induction coil is adjusted smoothly by controlling the downward movement of the induction coil relative to the crucible, so as to adjust the temperature change above the melt liquid surface in the crucible, and the temperature gradient of the crystal growth interface can be kept consistent with the initial state. In the process of controlling the downward movement of the induction coil relative to the crucible, the induction coil is moved at different speeds, so as to adapt to the temperature difference change at different positions in the crucible, and the temperature gradient required for the crystal growth can be kept during the initial stage of the melt liquid surface in the crucible and when the melt liquid surface drops to the middle and bottom of the crucible, so as to avoid defects in the process of crystal growth. The crystal blank grown by using the method of the embodiments of the present application is complete and transparent, and there are no obvious inclusions, cloud layers, bubbles and other defects in the interior, which greatly improves the yield of the blank and the material utilization rate, thereby reducing the cost of related products. BRIEF DESCRIPTION OF DRAWINGS

[0036] Figure 1 A flowchart of a crystal growth method provided by the embodiments of the present application is shown;

[0037] Figure 2 A schematic diagram of the magnetic field line distribution of the induction coil is shown;

[0038] Figure 3 A schematic diagram of the longitudinal temperature distribution in the crucible is shown;

[0039] Figure 4 A schematic diagram of the structure of a crystal growth device provided by the embodiments of the present application is shown;

[0040] Figure 5 A schematic diagram of the movement of the induction coil in the crystal growth device provided by the embodiments of the present application is shown. DETAILED DESCRIPTION

[0041] As described in the background, the inventors found that as the melt in the crucible is continuously converted into a crystal blank, the liquid level of the melt will gradually decrease, and the crystallization interface and the temperature gradient of the crystal growth will gradually change, which is mainly caused by the eddy current induction principle and the magnetic field line distribution of the induction coil. As shown in FIG. 1, the magnetic field lines of the induction coil are sparse at both ends and dense in the middle, and the eddy current induction generated by the metal in the region where the magnetic field lines are denser is more intense, and the temperature is also higher. In the general process of the pulling method of crystal growth, the relative position between the crucible and the induction coil is fixed and unchanged, and the crucible as a whole is located in the upper middle part of the induction coil. Because the magnetic field lines of the induction coil are dense in the middle region and sparse upward, the metal crucible will produce an uneven temperature field distribution at different positions in the induction coil, and generally speaking, the temperature of the middle and bottom of the crucible located in the dense magnetic field line region is higher, and the temperature of the top of the crucible located in the sparse magnetic field line region is slightly lower. Figure 2

[0042] ​As the crystal growth process progresses, the liquid level of the melt in the crucible gradually decreases. This decrease causes changes in the initial temperature field conditions. Specifically, the temperature above the liquid surface increases significantly as the liquid level decreases, while the temperature below the liquid surface remains basically unchanged. This results in a smaller and smaller temperature gradient for crystal growth, leading to an increase in defects in the crystal blank.

[0043] To address this issue, the inventors attempted to use a crucible micro-movement lifting method. While this was intended to mitigate internal defects, the inevitable vibrations during the movement of the crucible, which directly contained the liquid melt, would affect the crystal growth interface, thus making the crystal blank even worse.

[0044] To address this, the inventors attempted to lower the induction coil at a predetermined speed. While this method avoided the vibration of the melt caused by the movement of the crucible and improved the quality of the resulting crystal blank, it still could not achieve a truly ideal result.

[0045] The inventors further discovered that, for the same height difference, there are significant differences in temperature at different locations within the crucible, such as... Figure 3 As shown, the temperature change when the height of the crucible drops by 10 mm from the top is significantly greater than the temperature change when the height of the crucible drops by 10 mm from the middle or bottom. The overall longitudinal temperature distribution within the crucible exhibits a parabolic shape. While the molten surface in the crucible typically descends at a uniform speed, due to the characteristics of the magnetic field lines and the temperature distribution within the crucible, a relatively large temperature gradient can be maintained at the beginning of the descent. Only when the surface descends to the middle or bottom of the crucible does it significantly affect the temperature gradient required for crystal growth. If the induction coil descends at a predetermined speed, the temperature above the molten surface will drop too quickly at the beginning of the descent (a small height difference at the top of the crucible will cause a large temperature change), disrupting the original temperature gradient. Alternatively, the temperature above the molten surface may drop too slowly when the surface descends to the middle or bottom of the crucible (a small height difference at the middle or bottom of the crucible will not cause a significant temperature change), failing to achieve the temperature gradient required for crystal growth. The temperature gradient refers to the magnitude of the temperature difference between two points in space, generally referring to the temperature difference within a 1 cm distance; it is a core parameter in the crystal growth process.

[0046] Based on the above research, this application proposes a crystal growth method and apparatus, in which an induction coil moves downward relative to the crucible at different speeds as the liquid level falls, thereby adapting to the temperature difference changes at different positions inside the crucible. This ensures that the temperature gradient required for crystal growth is maintained at the initial stage of the molten liquid level's descent, as well as when it reaches the middle and bottom of the crucible, thus avoiding defects during the crystal growth process.

[0047] With reference to the drawings and embodiments of the present application, the technical solutions in the embodiments of the present application will be clearly described. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art belong to the scope of protection of the present application.

[0048] The terms "first", "second", and the like in the specification and claims of the present application are used to distinguish similar objects, and are not used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged under appropriate circumstances, so that the embodiments of the present application can be implemented in an order other than that illustrated or described herein, and the objects distinguished by "first", "second" are generally of a kind and do not limit the number of objects, for example, the first object can be one or more. In addition, "and / or" in the specification and claims indicates at least one of the connected objects, and the character " / " generally indicates that the front and rear associated objects are in an "or" relationship.

[0049] Referring to Figure 1 The crystal growth method of the embodiments of the present application comprises:

[0050] Step 101: In the process of growing a crystal using the Czochralski method, the inductive coil is controlled to move downward relative to the crucible, and during the process of moving the inductive coil downward relative to the crucible, the inductive coil is controlled to move at different speeds.

[0051] The crystal growth method of the embodiments of the present application, in the process of growing a crystal using the Czochralski method, controls the inductive coil to move downward relative to the crucible, which can smoothly adjust the relative position of the metal crucible and the inductive coil to adjust the temperature change above the melt surface in the crucible, so that the temperature gradient of the crystal growth interface can remain consistent with the initial state. And during the process of moving the inductive coil downward relative to the crucible, the inductive coil is controlled to move at different speeds, which can adapt to the temperature difference changes at different positions in the crucible, so that the melt surface in the crucible can maintain the required temperature gradient during the initial stage of descending and when descending to the middle and bottom of the crucible, avoiding defects in the crystal growth process. The crystal blank grown by the method of the embodiments of the present application is complete and transparent, and has no obvious inclusions, cloud layers, bubbles and other defects in the interior, greatly improving the yield rate of the blank and the material utilization rate, thereby reducing the cost of related products.

[0052] Generally, in order to meet the required temperature gradient for crystal growth, the crucible is located in the upper middle part of the inductive coil, at which time the longitudinal temperature distribution in the crucible changes as a whole in a parabolic shape, as described above. In order to ensure that the melt surface can maintain the required temperature gradient during the initial stage of descending and when descending to the middle and bottom of the crucible, preferably, the above step 101 comprises:

[0053] Step 1011: controlling the inductive coil to move at a gradually increasing speed during the process of moving downward relative to the crucible.

[0054] At this time, the temperature above the melt surface does not increase significantly in the initial stage of the melt surface descending, that is, the top region of the crucible, and this stage can still maintain a temperature gradient close to the initial state, and the small height difference in this stage will cause a large temperature change in the crucible. Therefore, controlling the inductive coil to move downward at a relatively small speed can avoid the temperature above the melt surface from decreasing too fast, thereby maintaining a temperature gradient close to the initial state. When the melt surface descends to the middle or bottom of the crucible, the temperature above the melt surface has been significantly increased, and the small height difference in this stage will not cause a large temperature change. Therefore, increasing the speed of the inductive coil moving downward in time can reduce the temperature above the melt surface to meet the temperature gradient required for crystal growth. In this way, by controlling the inductive coil to move downward at a gradually increasing speed, the temperature gradient required for crystal growth can be maintained in the initial stage of the melt surface descending and when the melt surface descends to the middle and bottom of the crucible, thereby avoiding defects in the crystal growth process.

[0055] When the crucible is not located in the upper middle of the inductive coil, the longitudinal temperature distribution trend in the crucible will change. At this time, the inductive coil can be controlled to move at different speeds during the process of moving downward relative to the crucible according to the actual temperature distribution trend in the crucible, so as to ensure that the temperature gradient close to the initial state is maintained during the melt surface descending process, thereby avoiding defects in the crystal growth process.

[0056] The following describes several implementation manners of the step 1011 of controlling the inductive coil to move at a gradually increasing speed.

[0057] As an optional implementation manner, the step 1011 includes:

[0058] Step 10111: controlling the inductive coil to move at a preset acceleration.

[0059] At this time, the inductive coil can be controlled to move at a gradually increasing speed by moving at a preset acceleration, thereby ensuring that the melt surface in the crucible can maintain the temperature gradient required for crystal growth in the initial stage of descending and when descending to the middle and bottom of the crucible, so that the temperature field in the crystal growth process is continuously stable, and defects in the crystal growth process are avoided.

[0060] The preset acceleration a can be set to any reasonable value according to requirements, which is not limited herein.

[0061] Specifically, when the inductive coil moves at a preset acceleration a, the calculation formula of the movement displacement S is as follows:

[0062] S = 1 / 2at 2 ;

[0063] Wherein, S represents motion displacement, a represents acceleration, and t represents time.

[0064] As another optional implementation, the step 1011 comprises:

[0065] Step 10112: When the distance or time of the movement of the induction coil relative to the crucible reaches a preset condition, the speed of the induction coil is controlled to increase.

[0066] At this time, the speed of the induction coil can also be controlled according to the distance or time of the movement of the induction coil, and when the distance or time of the movement of the induction coil reaches a preset condition, the speed of the induction coil is controlled to increase, which can also ensure that the temperature gradient required for crystal growth can be maintained when the melt liquid level in the crucible is in the initial stage of falling and when the melt liquid level falls to the middle and bottom of the crucible, so that the temperature field in the crystal growth process is continuously stable, and defects in the crystal growth process are avoided.

[0067] Specifically, the step 10112 can comprise:

[0068] When the distance or time of the movement of the induction coil relative to the crucible increases by a preset threshold value each time, the speed of the induction coil is controlled to increase by a preset increment.

[0069] Here, the distance or time of the movement of the induction coil relative to the crucible can be monitored, and when the distance or time of the movement of the induction coil relative to the crucible increases by a preset threshold value each time, the speed of the induction coil is controlled to increase by a preset increment, so that the speed of the induction coil is gradually increased to adapt to the change of the temperature difference at different positions of the crucible, so that the temperature field in the crystal growth process is continuously stable, and defects in the crystal growth process are avoided.

[0070] Wherein, the preset threshold value and the preset increment can be set to any reasonable value according to requirements, which is not limited here.

[0071] Or the step 10112 can comprise:

[0072] When the distance or time of the movement of the induction coil relative to the crucible reaches a target interval, the induction coil is controlled to move at a speed corresponding to the target interval, wherein the distance or time of the movement of the induction coil relative to the crucible is divided into a plurality of target intervals in advance, each target interval corresponds to a different speed, and the speed corresponding to a target interval arranged at the rear is greater than the speed corresponding to a target interval arranged at the front.

[0073] Here, the distance or time of the inductive coil moving relative to the crucible can also be divided into multiple target intervals according to the total distance or total time of the inductive coil moving relative to the crucible, and the speed of the inductive coil moving to a later target interval is greater. In this way, the speed of the inductive coil moving to a later target interval is greater, and the speed of the inductive coil is gradually increased to adapt to the temperature difference change of the crucible at different positions, so that the temperature field of the crystal growth process is continuously stable, and defects are avoided in the crystal growth process.

[0074] In the embodiments of the present application, the division manner of the target intervals and the speed corresponding to each target interval are not limited, and can be set according to actual application requirements. For example, the distance of the inductive coil moving relative to the crucible can be divided into three target intervals, the speed corresponding to the first target interval is set to 0.001 mm / h, the speed corresponding to the second target interval is set to 0.05 mm / h, and the speed corresponding to the third target interval is set to 0.1 mm / h. Of course, this division manner is only for illustration, and the implementation manner of the embodiments of the present application is not limited thereto.

[0075] Or the above step 10112 can include:

[0076] When the distance or time of the inductive coil moving relative to the crucible reaches a target interval, the inductive coil is controlled to move at a uniform acceleration corresponding to the target interval, wherein the distance or time of the inductive coil moving relative to the crucible is divided into multiple target intervals in advance, each target interval corresponds to a different acceleration, and the acceleration corresponding to a later target interval is greater than the acceleration corresponding to an earlier target interval.

[0077] Here, the inductive coil can also be controlled to always move at a uniform acceleration, but the acceleration is gradually changed. Specifically, the distance or time of the inductive coil moving relative to the crucible can be divided into multiple target intervals according to the total distance or total time of the inductive coil moving relative to the crucible, and different target intervals correspond to different accelerations, and the acceleration corresponding to a later target interval is greater. In this way, the inductive coil always moves at a uniform acceleration, and the acceleration is greater when the inductive coil moves to a later target interval. In this way, the speed of the inductive coil is gradually increased to adapt to the temperature difference change of the crucible at different positions, so that the temperature field of the crystal growth process is continuously stable, and defects are avoided in the crystal growth process.

[0078] In the embodiments of the present application, the division manner of the target intervals and the acceleration corresponding to each target interval are not limited, and can be set according to actual application requirements.

[0079] Optionally, the above step 101 includes:

[0080] controlling the inductive coil to move downward relative to the crucible when the crystal grown by the Czochralski method enters an isodiametric stage;

[0081] stopping the movement of the inductive coil when the crystal growth reaches a set length.

[0082] At this time, when the crystal enters the isodiametric stage, the melt surface will begin to drop obviously, at which time the inductive coil is controlled to move downward relative to the crucible, thereby relieving the change in temperature gradient caused by the drop in the melt surface, keeping the crystal growth conditions stable, and avoiding the generation of inclusions, clouding, bubbles and other defects in the crystal. When the crystal growth reaches a set length, the movement of the inductive coil is stopped, and after the crystal is taken out, the inductive coil can be restored to the initial position for standby.

[0083] Optionally, the speed at which the inductive coil moves relative to the crucible is greater than or equal to 0.001 mm / h and less than or equal to 0.1 mm / h.

[0084] At this time, the inductive coil can be controlled to move at a speed in the range of 0.001 mm / h to 0.1 mm / h, so as to keep the temperature field stable during crystal growth.

[0085] The crystal grown by the crystal growth method of the embodiments of the present application can include YAG, YVO4, LSO, LYSO, RGBS, BGO, GAGG, LiNbO3, LiTaO3, etc., but is not limited thereto.

[0086] The crystal growth method of the embodiments of the present application, in the process of growing a crystal by the Czochralski method, controls the inductive coil to move downward relative to the crucible, which can smoothly adjust the relative position of the metal crucible and the inductive coil, so as to adjust the temperature change above the melt surface in the crucible, and in the process of controlling the inductive coil to move downward relative to the crucible, the inductive coil is moved at different speeds, so that the temperature gradient of the crystal growth interface can be kept consistent with the initial state when the melt surface in the crucible drops at the initial stage and when the melt surface drops to the middle and bottom of the crucible, thereby adapting to the temperature difference change at different positions in the crucible, providing a continuously stable temperature field condition for crystal growth, and avoiding the generation of defects in the process of crystal growth. The crystal blank grown by the method of the embodiments of the present application is complete and transparent, and has no obvious inclusions, clouding, bubbles and other defects in the interior, greatly improving the yield rate of the blank and the material utilization rate, thereby reducing the cost of related products.

[0087] Referring to Figure 4 The embodiments of the present application also provide a crystal growth device, which comprises:

[0088] a growth furnace 41, wherein the growth furnace 41 has a growth furnace cavity 411;

[0089] A crucible 43 is arranged in the growth furnace chamber 411, and the crucible 43 can hold crystal raw materials;

[0090] An induction coil 44 is arranged in the growth furnace chamber 411 and surrounds the outside of the crucible 43;

[0091] An induction coil driving mechanism 45 is connected with the induction coil 44, and can drive the induction coil 44 to move downwards at different speeds relative to the crucible 43 during the crystal growth process.

[0092] The crystal growth equipment of the embodiment provides a driving mechanism for the induction coil 44, which can drive the induction coil 44 to move downwards at different speeds relative to the crucible 43 during the crystal growth process, thereby smoothly adjusting the relative position of the crucible 43 and the induction coil 44, achieving the purpose of adjusting the temperature change above the melt liquid surface in the crucible 43, so that the temperature gradient of the crystal growth interface can be kept consistent with the initial state when the melt liquid surface in the crucible 43 is in the initial stage of falling and when it falls to the middle and bottom of the crucible 43, thereby adapting to the temperature difference change at different positions in the crucible 43, providing continuous and stable temperature field conditions for crystal growth, and avoiding defects in the crystal growth process. The crystal blank grown by the equipment of the embodiment is complete and transparent, and has no obvious inclusions, cloud layers, bubbles and other defects, greatly improving the yield rate of the blank and the material utilization rate, thereby reducing the cost of related products.

[0093] Optionally, the induction coil driving mechanism 45 includes a support 451, a micro-motion platform 452 and a motion mechanism 453;

[0094] The support 451 is arranged below the induction coil 44, one end of which is connected with the induction coil 44, and the other end of which passes through the bottom of the growth furnace 41 and is connected with the micro-motion platform 452; wherein the bottom of the growth furnace 41 is provided with an opening for the support 451 to pass through;

[0095] The micro-motion platform 452 is arranged below the growth furnace 41, one side of which is connected with the support 451, and the other side of which is connected with the motion mechanism 453;

[0096] The motion mechanism 453 is arranged below the micro-motion platform 452 and can drive the micro-motion platform 452 to move, and when the micro-motion platform 452 moves, it can drive the support 451 and the induction coil 44 connected with the support 451 to move.

[0097] At this time, as Figure 5As shown, when the moving mechanism 453 moves, the micro-motion platform 452 is driven to move simultaneously, and the induction coil 44 is also moved, so that the induction coil 44 is driven by the moving mechanism 453 to move downward at different speeds relative to the crucible 43 with the falling of the liquid surface, so as to adapt to the temperature difference change at different positions in the crucible 43, so that the temperature gradient required for crystal growth can be maintained when the melt liquid surface in the crucible 43 is in the initial stage of falling and falls to the middle and bottom of the crucible 43, and defects in the crystal growth process are avoided.

[0098] Wherein, the moving mechanism 453 can drive the induction coil 44 to move downward relative to the crucible 43, and the moving process can be moved according to the gradually increasing trend of the speed, so as to provide a continuous and stable temperature field environment for crystal growth. For related embodiments, refer to the description of the crystal growth method embodiment part, which will not be repeated here.

[0099] Wherein, the moving speed of the micro-motion platform 452 can be set to be greater than or equal to 0.001 mm / h and less than or equal to 0.1 mm / h, so that the induction coil 44 is controlled to move in the speed range of 0.001 mm / h-0.1 mm / h, and the temperature field is continuously and stably realized in the crystal growth process. And the micro-motion platform 452 can bear a certain weight to support the bracket 451 and the induction coil 44.

[0100] Optionally, the moving mechanism 453 and the micro-motion platform 452 are connected through a transmission mechanism 454.

[0101] At this time, the moving mechanism 453 can drive the micro-motion platform 452 and the induction coil 44 to move through the transmission mechanism 454.

[0102] Optionally, the crystal growth device further comprises:

[0103] The heat preservation furnace 42 is arranged in the growth furnace chamber 411, the crucible 43 is arranged in the heat preservation furnace 42, and the induction coil 44 is arranged outside the heat preservation furnace 42.

[0104] At this time, the heat preservation furnace 42 is fixed in the growth furnace chamber 411, which can play a role of heat insulation and heat preservation. The crucible 43 is placed in the heat preservation furnace 42, which is a heating element of the crystal growth furnace 41 and a container for loading crystal raw materials. The induction coil 44 is located outside the heat preservation furnace, and is fixedly connected with the bracket and can move downward relative to the crucible 43.

[0105] Optionally, a fixed structure is arranged at a predetermined position in the heat preservation furnace 42, and the crucible 43 is fixed in the heat preservation furnace 42 through the fixed structure.

[0106] At this time, the crucible 43 is placed in a fixed position in the holding furnace 42, and is kept stable during the crystal growth process to avoid shaking and affecting the crystal growth quality.

[0107] Optionally, the crucible 43 is a metal crucible.

[0108] At this time, the metal crucible can generate eddy current effect in the magnetic field of the induction coil 44 to generate heat and realize crystal growth.

[0109] The crystal growth process using the crystal growth method and the growth equipment of the present application is described below. The process includes the following steps:

[0110] Furnace loading: the furnace is loaded according to the operation process and structure layout of the conventional pulling method for growing crystals, except that the induction coil 44 needs to be fixedly connected to the bracket 451, and the bracket 451 is fixedly connected to the micro-motion platform 452, and the stability during movement is ensured.

[0111] Material melting: the intermediate frequency alternating current is passed through the induction coil 44, the crucible 43 is inductively heated, and the raw material is gradually melted and forms a melt;

[0112] Crystal seeding: the seed crystal is inserted into the melt, slowly pulled and the melt temperature is adjusted, so that the melt gradually crystallizes along the direction of the seed crystal to start growing.

[0113] Shoulder expansion: the melt temperature is further adjusted to accelerate the crystal crystallization speed, so that the diameter of the crystal is gradually expanded to a set value.

[0114] Constant diameter: when the crystal enters the constant diameter stage, the melt surface will start to drop obviously, at this time, the micro-motion platform 452 is started to drive the induction coil 44 to gradually decrease according to the increasing speed through the bracket 451, and the decreasing speed range is 0.001mm / h-0.1mm / h, so that the temperature gradient change caused by the decrease of the liquid surface can be relieved, and the crystal growth conditions can be kept stable.

[0115] Finishing: when the crystal growth reaches the set length, the movement of the micro-motion platform 452 is stopped, the melt temperature is adjusted, the crystal growth rate is reduced, and the diameter of the blank is reduced until it is separated from the melt.

[0116] Cooling: after slowly cooling to room temperature, the crystal blank is taken out, and the micro-motion platform 452 is restored to the initial position for standby.

[0117] The crystal growth method and the crystal growth device provided in the embodiments of the present application can ensure that the temperature gradient required for crystal growth is maintained during the initial stage of the liquid surface drop in the crucible 43 and when the liquid surface drops to the middle and bottom of the crucible, and can provide a continuous and stable temperature field for crystal growth, thereby solving the defects such as inclusions, cloud layers, and bubbles in the crystal. The crystal blank grown by the above process is complete and transparent, and has no obvious defects in the interior, thereby greatly improving the yield of the blank and the material utilization rate, and reducing the cost of related products.

[0118] It should be noted that the crystal growth device provided in the embodiments of the present application can realize the various processes realized by the crystal growth method embodiments, and can achieve the same technical effects. To avoid repetition, the above device embodiments are not described again.

[0119] The embodiments of the present application also provide a crystal grown by using the crystal growth method described in the above embodiments.

[0120] It should be noted that the crystal provided in the embodiments of the present application is grown by using the method provided in the crystal growth method embodiments, and can achieve the same technical effects of the crystal growth method embodiments. To avoid repetition, the above crystal embodiments are not described again.

[0121] It should be noted that in this document, the terms "comprise", "contain" or any other variant thereof are intended to cover non-exclusive inclusion, so that processes, methods, articles or devices that include a series of elements not only include those elements, but also include other elements not explicitly listed or inherent to such processes, methods, articles or devices. Without more limitations, the element defined by the statement "comprises a" does not exclude the presence of additional identical elements in the process, method, article or device that includes the element. In addition, it should be noted that the scope of the methods and devices in the embodiments of the present application is not limited to the order of performing the functions shown or discussed, but can also include performing the functions in a substantially simultaneous manner or in reverse order, for example, the described method can be performed in an order different from that described, and various steps can also be added, omitted or combined. In addition, the features described with reference to certain examples can be combined in other examples.

[0122] The embodiments of the present application are described above in combination with the drawings, but the present application is not limited to the above specific embodiments, and the above specific embodiments are only illustrative and not limiting. Those skilled in the art can make many forms under the inspiration of the present application without departing from the scope of the present application and the scope protected by the claims.

Claims

1. A crystal growth method, characterized in that, The crystals include, but are not limited to, YAG, YVO4, LSO, LYSO, RGBS, BGO, GAGG, LiNbO3, and LiTaO3, and the crystal growth method includes: During the crystal growth process using the Czochralski method, once the crystal enters the constant diameter stage, the induction coil is controlled to move downward relative to the crucible. During the downward movement of the induction coil relative to the crucible, the induction coil is controlled to move at a preset acceleration, or the induction coil is controlled to move at a constant acceleration, with the acceleration gradually changing. The induction coil moves at a speed greater than or equal to 0.001 mm / h and less than or equal to 0.1 mm / h relative to the crucible.

2. The crystal growth method according to claim 1, characterized in that, The steps of controlling the induction coil to move downward relative to the crucible, while controlling the induction coil to always undergo uniform acceleration with the acceleration gradually changing, include: When the distance or time the induction coil moves relative to the crucible reaches the target interval, the induction coil is controlled to move with uniform acceleration according to the acceleration corresponding to the target interval. The distance or time the induction coil moves relative to the crucible is divided into multiple target intervals in advance. Each target interval corresponds to a different acceleration, and the acceleration corresponding to the later target intervals is greater than the acceleration corresponding to the earlier target intervals.

3. The crystal growth method according to any one of claims 1 to 2, characterized in that, Once the crystal has grown to the set length, the movement of the induction coil is stopped.

4. A crystal growth apparatus for implementing the crystal growth method as described in any one of claims 1 to 3, characterized in that, The device includes: A growth furnace, wherein the growth furnace has a growth furnace cavity; A crucible is placed inside the growth furnace chamber, and the crucible can hold crystal raw materials. An induction coil is disposed inside the growth furnace cavity and surrounds the outside of the crucible; An induction coil drive mechanism, connected to the induction coil, can control the induction coil to move downward relative to the crucible during the crystal growth process, after the crystal enters the constant diameter stage. During the downward movement of the induction coil relative to the crucible, the mechanism controls the induction coil to move with uniform acceleration according to a preset acceleration, or controls the induction coil to always move with uniform acceleration, and the acceleration is gradually changing. The speed at which the induction coil moves relative to the crucible is greater than or equal to 0.001 mm / h and less than or equal to 0.1 mm / h.

5. The crystal growth apparatus according to claim 4, characterized in that, The induction coil driving mechanism includes: a support, a micro-motion platform, and a motion mechanism; The support is positioned below the induction coil, with one end connected to the induction coil and the other end passing through the bottom of the growth furnace and connected to the micro-motion platform; wherein, the bottom of the growth furnace is provided with an opening for the support to pass through; The micro-motion platform is located below the growth furnace, with one side connected to the support and the other side connected to the motion mechanism; The motion mechanism is located below the micro-motion platform and can drive the micro-motion platform to move. When the micro-motion platform moves, it can drive the bracket and the induction coil connected to the bracket to move.

6. The crystal growth apparatus according to claim 5, characterized in that, The motion mechanism and the micro-motion platform are connected by a transmission mechanism.

7. The crystal growth apparatus according to any one of claims 4 to 6, characterized in that, The crystal growth apparatus also includes: A heat-insulating furnace chamber is disposed within the growth furnace cavity, the crucible is disposed within the heat-insulating furnace chamber, and the induction coil is surrounded around the outside of the heat-insulating furnace chamber.

8. A crystal grown using the crystal growth method as described in any one of claims 1 to 3.

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