CN222684839U

CN222684839U - Crystal and crucible separating device and induction heating coil thereof

Info

Publication number: CN222684839U
Application number: CN202421226050.7U
Authority: CN
Inventors: 周国清
Original assignee: Jiangsu Third Generation Semiconductor Research Institute Co Ltd
Current assignee: Jiangsu Third Generation Semiconductor Research Institute Co Ltd
Priority date: 2024-05-31
Filing date: 2024-05-31
Publication date: 2025-03-28
Anticipated expiration: 2034-05-31

Abstract

The utility model discloses a device for separating a crystal from a crucible and an induction heating coil thereof. The crucible comprises a side wall and a bottom plate, the crystal is bonded in the crucible before separation and is in direct contact with the bottom plate, the induction heating coil comprises a side coil and a bottom coil, the side coil and the side wall are profiled, the bottom coil and the bottom plate are profiled, and a containing space formed by encircling the side coil and the bottom coil can be profiled to contain the crucible. The separation scheme provided by the utility model is a mode of nondestructively separating the crystal from the crucible by an induction heating mode, can realize complete separation of the crystal ingot and repeated recycling of the crucible, and can remarkably reduce the crucible cost consumed when the crystal such as sapphire, spinel and yttrium aluminum garnet grows by a heat treatment method such as a heat exchange method, a crucible descent method and a temperature gradient method.

Description

Crystal and crucible separating device and induction heating coil thereof

Technical Field

The utility model relates to the technical field of crystal growth, in particular to a device for separating a crystal from a crucible and an induction heating coil thereof.

Background

Various compound crystals are widely applied in various fields of semiconductors, optics, electricity and the like, for example, sapphire crystals have high optical transmittance, mechanical strength, high temperature resistance (melting point reaches 2050 ℃), small thermal expansion coefficient, large thermal conductivity, good chemical stability, radiation resistance and other excellent physical and chemical properties, and are widely applied to the fields of national defense, aerospace and LEDs.

The heat exchange method is an important method for growing high-quality sapphire crystals, has the advantages of high growth speed, few crystal defects, stable temperature field, adjustable temperature gradient in a crucible, high automation degree and the like, has important markets on the growth of the high-quality optical-grade sapphire crystals, but has the defects that in the growth process, raw materials are seriously adhered to the crucible after all crystals are crystallized into crystals, the crucible is required to be physically destroyed in order to obtain the complete sapphire crystals, the crucible is made of a high-temperature-resistant molybdenum material, the crucible with a specific shape required by the growth of the heat exchange method is prepared by a high-temperature spinning technology, the cost is high, for example, the cost of a spinning molybdenum crucible with the diameter of 380mm and the height of 380mm is 11000-12000 yuan, the cost of a spinning molybdenum crucible with the diameter of 440mm and the height of 450mm is higher than 15000-18000 yuan, and in addition, the cost of the spinning molybdenum crucible or the tungsten crucible prepared by a powder metallurgy method is higher.

The crucible can only be used once in the existing heat exchange crystal growth technology is the biggest technical bottleneck, which hinders the popularization of the method, and results in high crystal growth cost, and the crucible cost in the heat exchange method accounts for 30-40% of the sapphire crystal cost through practical tests.

Meanwhile, the same phenomenon that crystals such as sapphire, spinel and yttrium aluminum garnet are seriously adhered to a crucible exists in the crystals grown by a crucible descent method and a temperature gradient method, and the crucible can only be damaged to obtain an ingot, so that the same problem is faced.

In addition, when abnormal conditions are encountered in the crystal growth process or the process parameters can not meet the condition of crystallization of crystals, poor quality of crystals in the crucible can be caused, various defects, cracking of crystals, scrapping of crystals, even non-crystallization of raw materials and the like occur, unfinished products are formed in the crucible, and at the moment, the crucible is also required to be physically damaged (molybdenum crucible fragments have recovery value) or discarded, so that the production cost is remarkably increased.

Disclosure of utility model

In view of the shortcomings of the prior art, the utility model aims to provide a device for separating a crystal from a crucible and an induction heating coil thereof.

In order to achieve the purpose of the utility model, the technical scheme adopted by the utility model comprises the following steps:

In a first aspect, the utility model provides an induction heating coil for separating a crystal from a crucible, the crucible comprising a side wall and a bottom plate, the crystal being bonded in the crucible prior to separation and being in direct contact with the bottom plate, the induction heating coil comprising a side coil and a bottom coil, the side coil being profiled with the side wall, the bottom coil being profiled with the bottom plate, and a receiving space formed around the side coil and the bottom coil being profiled to receive the crucible.

Further, the side coil is a coil spring, and the bottom coil is a planar spiral.

Further, the side coils and the bottom coils are connected in series.

Further, the side coil and the bottom coil are of an integrated coil structure formed by bending an integrated hollow metal tube.

Further, both ends of the hollow metal tube are respectively provided with a cooling medium inlet and a cooling medium outlet.

Further, the turn density of the side coil is 1.5-2.5 times of the turn density of the bottom coil

In a second aspect, the utility model also provides a device for separating a crystal from a crucible by induction heating, wherein the crystal is adhered to the inner wall of the crucible before separation, and the device comprises:

The induction heating coil is arranged in a copying way with the crucible, and the induction heating coil surrounds the crucible when induction heating is carried out;

A carrying structure for carrying the crucible and the crystal inside the crucible at the time of induction heating;

And a high-frequency power supply unit for supplying a high-frequency alternating current to the induction heating coil to achieve the induction heating.

Based on the technical scheme, compared with the prior art, the utility model has the beneficial effects that:

The separation method provided by the utility model is a method for nondestructively separating crystals from a crucible in an induction heating mode, can realize complete separation of crystal ingots and repeated recycling of the crucible, and can remarkably reduce crucible cost consumed when the crystals such as sapphire, spinel and yttrium aluminum garnet are grown by heat treatment methods such as a heat exchange method, a crucible descent method and a temperature gradient method.

The above description is only an overview of the technical solutions of the present utility model, and in order to enable those skilled in the art to more clearly understand the technical means of the present utility model, the present utility model may be implemented according to the content of the specification, and the following description is given of the preferred embodiments of the present utility model with reference to the detailed drawings.

Drawings

FIG. 1 is a schematic diagram showing the combination of a crystal and a crucible according to an exemplary embodiment of the present utility model;

FIG. 2a is a schematic diagram showing the front view of an induction heating coil in a separating apparatus according to an exemplary embodiment of the present invention;

FIG. 2b is a schematic top view of an induction heating coil in a separator according to an exemplary embodiment of the present invention;

FIG. 3 is a schematic view showing a combination of an induction heating coil and a crucible in a separation apparatus according to an exemplary embodiment of the present utility model;

FIG. 4 is a schematic diagram showing the overall construction of a separation device according to an exemplary embodiment of the present utility model.

The reference numerals are 1, crystal, 2, crucible, 3, outer wall surface, 4, inner wall surface, 5, outer bottom surface, 6, inner bottom surface, 7, bottom coil, 8, side coil, 9, protection cavity, 10, bearing table, 11, slide rail, 12, power supply, 13, control system, 14, mechanical pump, 15, diffusion pump, 16, inflation valve, 17, pressure gauge, 18 and transformer.

Detailed Description

In view of the shortcomings in the prior art, the inventor of the present utility model has long studied and practiced in a large number of ways to propose the technical scheme of the present utility model. The technical scheme, the implementation process, the principle and the like are further explained as follows.

In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present utility model, but the present utility model may be practiced otherwise than as described herein, and therefore the scope of the present utility model is not limited to the specific embodiments disclosed below.

Moreover, relational terms such as "first" and "second", and the like, may be used solely to distinguish one from another component or method step having the same name, without necessarily requiring or implying any actual such relationship or order between such components or method steps.

Referring to fig. 1-3, an embodiment of the present utility model provides a method for separating a crystal from a crucible, wherein the crystal is adhered to an inner wall of the crucible before separation, the crucible is a conductor, and the separation method includes the following steps:

The inner wall of the crucible 2, which is in contact with the crystal 1, is heated by induction heating, so that at least part of the surface of the crystal 1, which is in contact with the inner wall, is melted, and the crystal 1 is separated from the crucible 2.

The method designs an induction heating coil for separating the crystal 1 from the crucible 2, wherein the crucible 2 comprises a side wall and a bottom plate, the crystal is adhered in the crucible before separation and is in direct contact with the bottom plate, the induction heating coil comprises a side coil 8 and a bottom coil 7, the side coil 8 is profiled with the side wall, the bottom coil 7 is profiled with the bottom plate, and a containing space formed by the periphery of the side coil 8 and the bottom coil 7 can be profiled to contain the crucible 2.

The above crystal 1 is usually a compound having remarkable crystallization characteristics, such as a sapphire, spinel and yttrium aluminum garnet ingot grown by a heat exchange method, a crucible lowering method, a temperature gradient method, or the like. Specifically, for example, the sapphire material is a typical single crystal 1 material, has anisotropic crystal 1 characteristics, has a melting point of 2050 ℃, and requires a special method for separating the sapphire material from the crucible 2 material used in the growth production process, and other crystals 1 are similar thereto.

More specifically, for example, a heat exchange method is an important method for mass production of large-size high-quality sapphire crystals 1, and has the advantages of high optical quality, high optical uniformity, 380-500mm diameter, good stability of a growth technology, high repeatability, capability of stably producing 100Kg-200Kg of optical-grade sapphire crystals 1 in batches, a growth period of about 20 days and a growth temperature of 2150 ℃ at the highest, and a high-temperature-resistant molybdenum crucible 2 (the melting point of a molybdenum material of 2623 ℃) is required in the growth process to load aluminum oxide raw materials required for growing the sapphire, and is characterized in that all the raw materials in the crucible 2 are crystallized into the sapphire crystals 1, and the raw material utilization rate reaches 100 percent.

The method provided by the utility model utilizes a high-frequency induction heating principle, utilizes a unique special-shaped induction heating coil to carry out induction heating on a conductor crucible 2 (including but not limited to a molybdenum crucible 2, a tungsten crucible 2 or a tungsten-molybdenum alloy crucible 2, and of course, a graphite crucible 2 also belongs to the conductor crucible 2), the heat of the inner wall of the crucible 2 is conducted onto the crystal 1 in a conduction mode, the crystal 1 is heated, the surface temperature is continuously increased, the physical change from a solid phase to a liquid phase occurs when the temperature is increased to the melting point of the crystal 1 or raw materials, the crucible 2 is separated under the action of the separating force, and the internal temperature of the crystal 1 is not obviously increased due to the obviously lower heat conductivity of the crystal 1, so that the performance of the crystal 1 is not influenced.

The basic technical concept of the utility model is that the crucible 2 is instantaneously heated to a temperature above the melting point of the crystal 1 in a short time by adopting the skin effect of induction heating, and the high-temperature crucible 2 conducts heat to the surface of the crystal 1 material in a conduction mode, because the general thermal conductivity of the crystal 1 material is obviously lower than that of metal, when the crystal 1 material in the contact part with the crucible 2 reaches the melting point, the crystal 1 is converted into a melt with fluidity, and can leave the crucible 2.

In order to ensure good utilization of the crystal 1 and reduce the influence of the residual of the crystal 1 on the crucible 2, it is generally required that sapphire be intact after being separated from the crucible 2, and no defects such as cracking exist.

The induction heating has the characteristics of skin effect, the surface part of the heated material is heated instantly only by the existence of eddy current, the heating speed is high, and the heat efficiency is high, so that the heating mode is found to be the most favorable mode for demolding the crystal 1 through practical experiments, while other heating modes such as resistance wire heating have low efficiency, long time is needed to heat the temperature to a proper temperature, the inside of the crystal 1 is heated even if the proper temperature can be reached, the structure of the crystal 1 is changed from the original crystal 1 structure to an amorphous 1 structure once the inside is heated and then cooled again, and the material property is changed and cannot be used.

Therefore, selecting an induction heating mode with skin effect to locally heat the contact surface of the crystal 1 and the crucible 2 is a key to achieve demolding while avoiding affecting the internal structure of the crystal 1. In addition, in some preferred embodiments, the depth of the perceived heating should also be controlled so as to be concentrated near the contact surface, thereby achieving more accurate heating.

In addition to the heat-stripping of the finished product of the complete crystal, some unfinished product is also easily produced during actual production and preparation, whereby, in some embodiments, the crystal 1 comprises the complete crystal formed by growth or the unfinished product formed during the growth of the complete crystal. This means that the technical solution provided by the utility model not only enables separation of the finished product, but also of the unfinished product. Of course, the separation of the unfinished product will generally require less heating area than the finished crystal 1, which is generally not required to avoid affecting the internal crystal 1 structure of the unfinished product.

And more particularly, in some embodiments, the separation process may specifically include the following detailed steps:

While the induction heating is performed, the crystal 1 is continuously subjected to a resultant force in a direction away from the bottom of the crucible 2 until at least part of the surface of the crystal 1 melts and is detached.

With respect to the manner of applying the resultant force described above, in some embodiments, the crucible 2 is in a state where the opening is oriented in the direction of gravity when the induction heating is performed, and the crystal 1 is peeled off from the crucible 2 in the direction of gravity when melting of at least part of the surface of the crystal 1 occurs.

Of course, various alternatives to gravity disengagement may be employed, such as negative pressure traction, centrifugal force, and the like.

To avoid oxidation of the crucible 2, in some embodiments, the induction heating is performed in a vacuum and/or protective atmosphere.

Regarding specific structural features of the crystal 1 and the crucible 2, in some embodiments, the crystal 1 is a cylindrical body having a side wall surface and an end surface, the crucible 2 has an inner wall surface 4 and an inner bottom surface 6, the side wall surface and the inner wall surface 4 are adhered, the end surface and the inner bottom surface 6 are adhered, and a draft angle of greater than 90 ° is formed between the inner wall surface 4 and the inner bottom surface 6. Specifically, in the figure, the general θ is 93-95 degrees. The wall thickness of the crucible 2 is 2-5mm.

It is generally believed that maintaining a uniform power density for each location allows for different locations to reach the melting temperature simultaneously, thus achieving simultaneous demolding, as the heating rate is related to the power density. However, the inventors of the present utility model have found in practice that this method can obtain a relatively good separation effect for crystals 1 having a relatively small volume, for example, crystals 1 having a diameter and a height of 100mm or less, but can cause an uneven demolding of the side wall surfaces and the end surfaces in some cases when crystals 1 having a size exceeding the above-mentioned size (either the diameter or the height exceeds the above-mentioned range).

This is probably because the side wall surface and the inner wall surface 4 are separated by sliding, and the end surface and the inner bottom surface 6 are separated by plane, and the separation modes are different, so that when the melting temperature is reached, whether or not the large contact surface is separated is also different at a certain timing. In addition, the lattice structure of the different surfaces of the crystal 1 is also liable to be affected, and especially in the case of the single crystal 1 having an orientation, the crystal faces of the side wall surface and the bottom surface are different, which also causes a difference in the rate of temperature rise per se at the same power density, or a difference in the adhesion between the different crystal faces and the surface of the crucible 2, and various factors cause a phenomenon of asynchronous demolding when heating with a uniform power density.

Specifically, when the end surface at the bottom of the crucible 2 reaches the demolding condition, the side wall surface is further heated until the temperature of the side crystal 1 reaches the melting point, more sapphire crystals 1 are further melted into a high-temperature melt at the bottom of the crucible 2, and the crystals 1 can be separated from the crucible 2, which results in the reduction of the height of the crystals 1 and the reduction of the utilization rate of the crystals 1, and in addition, the adhesion deposition of the melted crystals 1 at the bottom of the crucible 2, which affects the secondary utilization of the crucible 2.

Under the condition that the side wall surface reaches the demoulding condition, the end surface of the crystal 1 at the bottom of the crucible 2 is continuously heated until the temperature reaches the melting point, the crystal 1 can be separated from the crucible 2, and at the moment, the crystal 1 can deform or even crack due to the fact that the side wall surface is excessively heated and the heat is concentrated based on the density skin effect of induction heating, and the crystal 1 is scrapped and has no value in use due to the fact that the temperature gradient is large.

Therefore, in order to increase the utilization and yield of the whole crystals as much as possible and to avoid excessive residue of the melted crystals 1 on the surface of the crucible 2, in some embodiments, the power densities of the inner wall surface 4 and the inner bottom surface 6 are modulated to be different when the induction heating is performed, so that the side wall surface and the end surface are simultaneously brought into a melted state.

Based on the actual experience of the inventors of the present utility model, it mainly occurs that the bottom end face reaches the mold release condition first for most of the crystals 1, and therefore, for most of the crystals 1, for example, sapphire, spinel, yttrium aluminum garnet, and the like, it is generally necessary to set the power density corresponding to the side wall face higher than that corresponding to the end face, especially for a crystal form having a strong orientation, such as a single crystal.

It is of course not excluded that for different crystals 1, it may happen that the side reaches the demolding condition first, based on the technical idea disclosed in the utility model, the emphasis is on the indicated implementation means of regulating the different power densities of the side and the bottom, and the regulation is performed in combination with the actual phenomenon.

With respect to specific tuning ratios, in some embodiments, the inner bottom surface 6 corresponds to a power density of 40-60% of the power density of the inner wall surface 4, particularly for crystals such as sapphire, spinel, and yttrium aluminum garnet, particularly for crystals with relatively strong anisotropies, such as single crystals.

The side and bottom surfaces are precisely controlled to be melted simultaneously by modulating the power density, so that the integrity of the crystal 1 can be ensured, in addition, the minimum thermal stress and mechanical stress to each part of the crucible 2 in the induction heating and sapphire separating process can be ensured, the deformation of the crucible 2 is minimum, the recycling frequency is improved, and the process control of the next round of crystal 1 growth and the quality of the crystal 1 are also facilitated.

In addition to the proportional relationship of the power densities of different surfaces, the numerical range of the power density is also important for obtaining a better separation effect, and experiments show that the heating power density is a key parameter affecting whether the crystal and the crucible can be well separated, and through a plurality of experiments, a reasonable heating power density range can be found, wherein the minimum value of the power density is 20 watts per cubic centimeter, the maximum value of the power density is 120W/cm ³, and the optimal value is 50-80W/cm ³. When the power density is less than 20W/cm ³, the heating efficiency is low, the temperature rise is slow, and the number of the ingot melting parts is large, so that the ingot utilization rate is low. Under the condition that the power density is higher than 120W/cm ³, on one hand, the requirement on heating equipment is high, the cost is high, on the other hand, the too fast heating can cause the phenomenon of heat stress concentration in the ingot, the heat stress and the residual stress in the ingot growing process can lead to the local cracking of the ingot under the combined action, and the utilization rate of the ingot can be lowered.

It can be seen that in some embodiments, the power density ranges from 20 to 120W/cm ³. In this range, the actual power densities of the different surfaces may be adjusted based on the above-described proportional relationship.

With continued reference to fig. 1-3 and combined reference to fig. 4, corresponding to the above separation method, a second aspect of the embodiment of the present utility model further provides a separation device for separating a crystal 1 from a crucible 2 by induction heating, wherein the crystal 1 is adhered to an inner wall of the crucible 2 before separation, and the separation device comprises:

And the induction heating coil is arranged in a profiling way with the crucible 2, and the induction heating coil surrounds the crucible 2 when induction heating is carried out.

And a carrying structure for carrying the crucible 2 and the crystal 1 inside the crucible 2 at the time of induction heating.

In some embodiments, the separation device may further comprise a protective chamber 9, the induction heating coil and the carrying structure being both arranged in the protective chamber 9, the protective chamber 9 being capable of being evacuated and/or replaced with a protective atmosphere.

With respect to the specific structure and the matching relationship of the crucible 2 and the induction coil, in some embodiments, the crucible 2 has an outer wall surface 3 and an outer bottom surface 5, the induction heating coil includes a bottom coil 7 and a side coil 8, the bottom coil 7 is in a planar spiral shape corresponding to the profiling of the outer bottom surface 5, the side coil 8 is in a spiral spring shape corresponding to the profiling of the outer wall surface 3, and the bottom coil 7 and the side coil 8 are spaced equally from the outer wall surface 3 or the outer bottom surface 5.

Further to the refined power density regulation method described above, in some embodiments, to create the above-described difference in power density, the bottom coil 7 and the side coil 8 are connected in series, and the turn density of the side coil 8 is 1.5-2.5 times higher than the turn density of the bottom coil 7, so that the power density of the side wall face is greater.

In general, however, suitable turn densities range from a minimum of 1 turn per cm to a maximum of 15 turns per cm, with an optimum in the range of 5-12 turns per cm. Naturally, even if the difference is different from this, the corresponding function can be realized by properly designing the crucible size and other conditions.

Of course, the mode of forming the difference of the power density can be various, the mode belongs to a preferred mode which is convenient to implement and relatively accurate to control, in addition, two independent bottom coils 7 and side coils 8 can be arranged, the power of the two coils can be respectively controlled electrically, the power density of the two coils can be further controlled to show the proportional relation, and therefore the effect that the side wall surface and the end surface of the crystal 1 synchronously reach the separation condition can be achieved.

As some typical examples of the above technical solutions, the general coil used in the present utility model may be formed by processing a copper tube, and is composed of two parts, namely a side coil 8 and a bottom coil, wherein the side coil 8 heats the side of the crucible 2, the bottom coil heats the bottom of the crucible 2, the side height H3 of the coil is greater than the height H1 of the crystal 1, and the diameter C of the bottom of the coil is greater than the diameter a of the crucible 2, as shown in fig. 2a, 2b and 3.

The number of turns of the side coil 8 is related to the coil height and copper tube diameter, side turns = height divided by copper tube diameter. The bottom 7 turns of the coil is related to the coil diameter and copper tube diameter, bottom turns = coil diameter/(coil copper tube diameter x 2)

Specifically, taking an induction heating diameter of 380mm, a height of 380mm, a diameter of 375mm for molybdenum crucible 2 and crystal 1, and a height of 260mm as an example, a circular copper tube diameter of 10mm, a coil bottom diameter of 400mm, and a bottom turns=400 (10×2) =20 turns was used. Coil height 300mm, side turns = 300/10 = 30 turns.

Of course, if it is desired to control the side and bottom surfaces to have different turn densities to achieve different power densities, the spacing of the side or bottom surfaces may be adjusted appropriately to adjust the number of turns.

The relative position relationship between the induction coil and the crucible 2 is that the side coil 8 of the induction coil is kept at a distance of 5-10mm from the wall of the crucible 2, and the distances between the left side and the right side are equal. The bottom coil 7 is kept at a distance of 5-10mm from the bottom of the crucible 2, and the bottom coil 7 and the side coil 8 are usually kept at equal distances from the corresponding crucible 2.

The method is suitable for a crucible 2 and a crystallized crystal 1 used in a plurality of crystal 1 growth methods such as a heat exchange method, a crucible descending method, a temperature gradient method and the like, and is characterized in that the crucible 2 is made of conductive materials, the crystal 1 and the crucible 2 are in a blocking state, and the device is suitable for the situation that the crystal 1 is complete and the crystal 1 is cracked. The device of the utility model can also be suitable for the raw materials and the crucible 2 which are not crystallized even because of the growth failure of the crystal 1 caused by various reasons, and is characterized in that the raw materials and the crucible 2 are in an adhesion state, in order to recycle the crucible 2, the method is suitable for taking the raw materials which are not crystallized out of the crucible 2 to obtain the complete crucible 2, and the crucible 2 can be continuously used for a second time after relevant treatment, so that the use cost of the crucible 2 is reduced.

As an example of a separation method, the separation method is carried out by using a separation apparatus as shown in fig. 4, and the specific steps include:

The first step is to invert the molybdenum crucible 2 adhered with the sapphire crystal 1 on a carrying table 10 which can move up and down, namely the top of the crucible 2 is downward, and the bottom of the crucible 2 is upward.

And secondly, slowly moving the sliding rail 11 upwards, and moving the bearing table 10 fixedly connected with the sliding rail 11 upwards to place the crucible 2 inside the induction coil, wherein the gap between the bottom of the crucible 2 and the bottom of the induction coil is adjusted to be 5-10mm, and the gap between the side of the crucible 2 and the side of the coil is adjusted to be 5-10mm as shown in figure 3.

And thirdly, sealing and vacuumizing a protection chamber 9 provided with an induction coil and the crucible 2, wherein a vacuum system consists of a mechanical pump 14 and a diffusion pump 15 or a molecular pump secondary system, firstly starting the mechanical pump 14 to pump vacuum of less than 5Pa, then starting the diffusion pump 15 or the molecular pump to pump high vacuum of less than 3X 10 ^-3 Pa, filling high-purity 99.99% argon or nitrogen into the protection chamber 9 through an inflation valve 16, and closing the inflation valve 16 when the pressure gauge 17 of the protection chamber 9 shows that the pressure in the furnace is positive pressure, and is generally 0.01-0.05 Mpa. The purpose of the argon or nitrogen filling is to prevent oxidation during induction heating due to the elevated temperature of the molybdenum crucible 2.

And fourthly, opening water inlet of an induction coil, controlling the water inlet temperature to be 15-25 ℃ and the flow to be 5-10L/min, starting a device power supply 12 through a control system 13 and applying current through a transformer 18, wherein the induction coil can generate vortex in the crucible 2, instantly heating molybdenum materials at the bottom and the side surface of the crucible 2, the melting point of the sapphire crystal 1 is 2050 ℃, when the temperature of the molybdenum materials reaches 2050 ℃, the sapphire crystal 1 adhered to the inner side wall of the crucible 2 and the inner wall of the bottom of the crucible 2 can become melt due to heating, and the whole sapphire crystal 1 is separated from the molybdenum crucible 2 and falls on a bearing table 10 under the action of gravity due to the existence of a cavity H2 (figure 1) at the openings of the crystal 1 and the crucible 2 in the crucible 2. That is, in some embodiments, the support structure includes a horizontally disposed support table 10, the crucible can be supported on a surface of the support table, and the opening is directed in the direction of gravity. Of course, even if the crystal 1 is slightly inclined, the falling of the crystal 1 is not affected, and the crystal 1 is pulled and separated in a non-gravitational direction by a suction cup or the like, which is equivalent.

And fifthly, cutting off the power supply 12, filling normal-temperature and normal-pressure air into the protection cavity 9 through the inflation valve 16 until the internal and external pressure are balanced, opening the protection cavity 9, moving down the bearing table 10, and taking out the sapphire crystal 1.

In the technical scheme, the induction heating frequency is closely related to the wall thickness of the crucible 2, and the frequency range used by the utility model is usually 10KHz-62.5KHz. According to the induction heating principle, the induction heating depth d and the induction frequency f have the following relation formula:

Wherein f is frequency in Hz, d is heating depth in millimeters (mm).

When f=10khz, the heating depth d=5mm is suitable for the molybdenum or tungsten crucible 2 with the wall thickness of 5mm, the crystal 1 in the crucible 2 is not heated by induction due to non-conduction, only the heat conduction from the inner wall of the crucible 2 to the crystal 1 exists, the temperature of the surface (including the bottom side surface) of the crystal 1 rises due to short heating time, and the temperature of the rest of the crystal 1 is unchanged.

When f=62.5 KHz, the heating depth d=2 mm, which is applicable to a molybdenum or tungsten crucible 2 having a wall thickness of 2mm, the crystal 1 in the crucible 2 is not inductively heated due to non-conduction. Only the inner wall of the crucible 2 conducts heat to the crystal 1, and the surface (including the bottom side) of the crystal 1 rises in temperature due to the short heating time, and the temperature of the rest of the crystal 1 does not change.

While to ensure full heating, the coil height H1 is typically greater than the ingot thickness H2, h1—h2=20-30 mm.

As a further application of the above technical solution, the embodiment of the present utility model further provides a crystal growth method, which includes the following steps:

the crystal 1 is formed in the crucible 2 by means of heat treatment.

The crystal 1 is separated from the crucible 2 by induction heating using the separation method provided in any of the above embodiments, and the independent crystal 1 and crucible 2 are obtained.

The crystal 1 may be, for example, a complete crystal, which is separated and used for slicing, and the like, or may be a non-applicable product generated when the complete crystal is grown, for example, a product which is not applicable and is generated by poor crystallization, unexpected interruption of a process, or the like, and the crucible 2 which can be reused is obtained by realizing detachment in the above-described manner.

After the physical separation of the crystal 1 and the crucible 2 is realized, the inner wall of the crucible 2 is polished by diamond paper, and raw materials required by the growth of the crystal 1 can be loaded again after the soaking, cleaning and drying by weak acid, so that the second cycle use can be started, and the cost of the crucible 2 consumed by a single crystal 1 is reduced. According to experience, the conductive crucible 2 with the adhered crystals 1, which is separated by the method provided by the utility model, can be recycled at least 2-5 times.

The technical scheme of the utility model is further described in detail below through a plurality of embodiments and with reference to the accompanying drawings. However, the examples are chosen to illustrate the utility model only and are not intended to limit the scope of the utility model.

Example 1

This embodiment exemplifies a separation process of a sapphire crystal 1, and is specifically as follows:

The first step is to invert a molybdenum crucible 2 (crucible 2 diameter 380mm, height 380 mm) with single crystal sapphire crystal 1 (crystal 1 diameter 375mm, height 235mm, weight 100 Kg) grown by heat exchange method on a carrying table 10 which can move up and down, i.e. the top of crucible 2 is downward and the bottom of crucible 2 is upward.

And secondly, slowly moving the sliding rail 11 upwards, and arranging the crucible 2 in the induction coil by moving the bearing table 10 fixedly connected with the sliding rail 11 upwards, wherein the induction coil is 390mm in diameter at the bottom and 260mm in height, the diameter of a copper pipe forming the induction coil is 10mm, the number of turns of the side coil 8 is 26, the number of turns of the bottom coil 7 is 19, the gap between the bottom of the crucible 2 and the bottom of the induction coil is 5mm, and the gap between the side part of the crucible 2 and the side part of the coil is 5mm as shown in fig. 3.

And thirdly, sealing and vacuumizing a protection chamber 9 provided with an induction coil and the crucible 2, wherein a vacuum system consists of a mechanical pump 14 and a diffusion pump 15, firstly starting the mechanical pump 14 to vacuumize to 4Pa, then starting the diffusion pump 15 to vacuumize to 2×10 ^-3 Pa, filling high-purity 99.99% argon into the protection chamber 9 through an inflation valve 16, and closing the inflation valve 16 when a furnace pressure gauge 17 displays that the furnace pressure is positive pressure and the pressure is 0.01 Mpa. Argon is filled to prevent oxidation during induction heating due to the elevated temperature of the molybdenum crucible 2.

And fourthly, opening the water inlet of an induction coil, wherein the water inlet temperature is 15 ℃, the flow is 5L/min, starting a power supply 12 of equipment, the induction coil can generate vortex in the crucible 2, the molybdenum material at the bottom and the side surface of the crucible 2 is instantaneously heated, the melting point of the sapphire crystal 1 is 2050 ℃, when the temperature of the molybdenum material reaches 2050 ℃, the sapphire crystal 1 adhered to the inner side wall of the crucible 2 and the inner wall of the bottom of the crucible 2 can become melt due to heating, and the whole sapphire crystal 1 is separated from the molybdenum crucible 2 under the action of gravity and falls on the bearing table 10.

And fifthly, cutting off the power supply 12, filling normal-temperature and normal-pressure air into the furnace body through the charging valve 16 until the internal and external pressure are balanced, opening the furnace body, slowly moving down the bearing table 10, taking out the complete sapphire crystal 1, and weighing 100Kg.

Comparative example 1

This comparative example is substantially the same as example 1, with the main difference that:

The induction coil is removed and replaced with a resistance wire of the same winding pattern, and the resistance wire is closely contacted with the crucible 2 to achieve heat conduction. The heating speed of the resistance wire is slow, the highest temperature of the heating is far lower than the melting point 2050 ℃ of the sapphire, and the temperature of the resistance wire is generally only hundreds of degrees, so that the sapphire can not be melted to become power to be separated from the crucible.

Finally, the obtained sapphire crystal 1 has a problem that sapphire cannot be taken out from the crucible, and even if forcibly taken down, a problem that macrocracks are generated on the surface of sapphire is caused.

Comparative example 2

The number of turns of the bottom coil 7 is raised to 39 turns, at which time the turns density of the bottom coil 7 and the side coil 8 is close to 1:1.

Finally, the obtained sapphire crystal 1 has the problem that the bottom is remarkably melted, the melting depth is about 13cm, the utilization rate of the sapphire is reduced, and the crucible 2 can be reused after the crystalline material remained at the bottom of the crucible 2 after melting still needs to be removed.

Example 2

The first step is to invert a molybdenum crucible 2 (the diameter of the crucible 2 is 440mm, the height is 450 mm) which is grown by a heat exchange method and is adhered with a sapphire crystal 1 (the diameter of the crystal 1 is 430mm, the height is 280mm, and the weight is 160 Kg), on a bearing table 10 which can move up and down, namely, the top of the crucible 2 is downward, and the bottom of the crucible 2 is upward.

And secondly, slowly moving the sliding rail 11 upwards, and placing the crucible 2 in the induction coil by the upward displacement of the bearing table 10 fixedly connected with the sliding rail 11, wherein the induction coil is 460mm in bottom diameter and 350mm in height, the diameter of a copper pipe forming the induction coil is 10mm, the number of turns of the side coil 8 is 35, the number of turns of the bottom coil is 23, the gap between the bottom of the crucible 2 and the bottom of the induction coil is adjusted to be 10mm, and the gap between the side part of the crucible 2 and the side part of the coil is adjusted to be 10mm, as shown in fig. 3.

And thirdly, sealing and vacuumizing a protection chamber 9 provided with an induction coil and the crucible 2, wherein a vacuum system consists of a mechanical pump 14 and a diffusion pump 15, firstly starting the mechanical pump 14 to vacuumize to 5Pa, then starting the diffusion pump 15 to vacuumize to 3×10 ^-3 Pa, filling high-purity 99.99% nitrogen into the protection chamber 9 through an inflation valve 16, and closing the inflation valve 16 when a furnace pressure gauge 17 displays that the furnace pressure is positive pressure and the pressure is 0.03 Mpa. The nitrogen gas is filled in order to prevent oxidation due to the temperature rise of the molybdenum crucible 2 during the induction heating.

And fourthly, opening the induction coil to feed water at the temperature of 18 ℃ and the flow rate of 8L/min, starting the equipment power supply 12, enabling the induction coil to generate vortex in the crucible 2, heating the molybdenum material at the bottom and the side surface of the crucible 2 instantly, enabling the melting point of the sapphire crystal 1 to be 2050 ℃, enabling the sapphire crystal 1 adhered to the inner side wall of the crucible 2 and the inner wall of the bottom of the crucible 2 to become melt due to heating when the temperature of the molybdenum material reaches 2050 ℃, separating the whole sapphire crystal 1 from the molybdenum crucible 2 under the action of gravity, and landing on the bearing table 10.

And fifthly, cutting off the power supply 12, filling normal-temperature and normal-pressure air into the furnace body through the charging valve 16 until the internal and external pressure are balanced, opening the furnace body, slowly moving down the bearing table 10, taking out the complete sapphire crystal 1, and weighing 160Kg.

Example 3

The first step is to invert a molybdenum crucible 2 (the diameter of the crucible 2 is 500mm, the height is 450 mm) which is grown by a heat exchange method and is adhered with a doped titanium sapphire crystal 1 (the diameter of the crystal 1 is 490mm, the height is 270mm, and the weight is 202 Kg), on a bearing table 10 which can move up and down, namely, the top of the crucible 2 is downward, and the bottom of the crucible 2 is upward.

And secondly, slowly moving the sliding rail 11 upwards, and placing the crucible 2 in the induction coil by the upward displacement of the bearing table 10 fixedly connected with the sliding rail 11, wherein the induction coil is 520mm in diameter at the bottom and 350mm in height, the diameter of a copper pipe forming the induction coil is 15mm, the number of turns 24 of the side coil 8, the number of turns 23 of the bottom coil 7, the gap between the bottom of the crucible 2 and the bottom of the induction coil is adjusted to be 10mm, and the gap between the side part of the crucible 2 and the side part of the coil is adjusted to be 10mm, as shown in figure 3.

And thirdly, sealing and vacuumizing a protection chamber 9 provided with an induction coil and the crucible 2, wherein a vacuum system consists of a mechanical pump 14 and a diffusion pump 15, firstly starting the mechanical pump 14 to vacuumize to 5Pa, then starting the diffusion pump 15 to vacuumize to 2×10 ^-3 Pa, filling high-purity 99.99% nitrogen into the protection chamber 9 through an inflation valve 16, and closing the inflation valve 16 when a furnace pressure gauge 17 displays that the furnace pressure is positive pressure and the pressure is 0.05 Mpa. The nitrogen gas is filled in order to prevent oxidation due to the temperature rise of the molybdenum crucible 2 during the induction heating.

And fourthly, opening water inlet of an induction coil, wherein the water inlet temperature is 20 ℃, the flow is 10L/min, a power supply 12 of equipment is started, the induction coil can generate vortex in the crucible 2, molybdenum materials at the bottom and the side face of the crucible 2 are instantaneously heated, the melting point of the doped titanium sapphire crystal 1 is 2050 ℃, when the temperature of the molybdenum materials reaches 2050 ℃, the doped titanium sapphire crystal 1 adhered to the inner side wall of the crucible 2 and the inner wall of the bottom of the crucible 2 can become melt due to heating, and the whole doped titanium sapphire crystal 1 is separated from the molybdenum crucible 2 under the action of gravity and falls on a bearing table 10.

And fifthly, cutting off the power supply 12, filling normal-temperature and normal-pressure air into the furnace body through the charging valve 16 until the internal and external pressure are balanced, opening the furnace body, slowly moving down the bearing table 10, and taking out the complete titanium-doped sapphire crystal 1, wherein the weight is 202Kg.

In addition, the utility model also carries out the same separation test on other various methods, such as sapphire crystals prepared by a crucible descent method and other crystals prepared by the same heat treatment method, such as spinel, yttrium aluminum garnet and the like, and obtains the same technical effect.

And the power density difference between the side surface and the bottom surface of the crystal with larger size has a similar rule, but the optimal proportion which can be corresponding to different crystals 1 is different.

Based on the above examples and comparative examples, it is clear that the separation method provided by the embodiment of the present utility model is a method for nondestructively separating a crystal from a crucible by an induction heating method, which can achieve complete separation of an ingot and multiple recycling of the crucible, and can significantly reduce crucible costs consumed when growing crystals such as sapphire, spinel, and yttrium aluminum garnet by heat treatment methods such as a heat exchange method, a crucible descent method, and a temperature gradient method.

It should be understood that the above embodiments are merely for illustrating the technical concept and features of the present utility model, and are intended to enable those skilled in the art to understand the present utility model and implement the same according to the present utility model without limiting the scope of the present utility model. All equivalent changes or modifications made in accordance with the spirit of the present utility model should be construed to be included in the scope of the present utility model.

Claims

1. An induction heating coil for a separation device of a crystal and a crucible, wherein the crucible comprises a side wall and a bottom plate, the crystal is bonded in the crucible before separation and is in direct contact with the bottom plate, and the induction heating coil is characterized by comprising a side coil and a bottom coil, the side coil is profiled with the side wall, the bottom coil is profiled with the bottom plate, and a containing space formed by the surrounding of the side coil and the bottom coil can be profiled to contain the crucible.

2. The induction heating coil of claim 1, wherein said side coils are coil springs and said bottom coils are planar spirals.

3. The induction heating coil of claim 2, wherein said side coils and bottom coils are connected in series.

4. The induction heating coil of claim 3, wherein said side coils and bottom coils are of unitary coil construction formed by bending a unitary hollow metal tube.

5. The induction heating coil of claim 4, wherein both ends of the hollow metal tube are provided with a cooling medium inlet and a cooling medium outlet, respectively.

6. An induction heating coil according to claim 3, characterized in that the turn density of the side coils is 1.5-2.5 times the turn density of the bottom coils.

7. A device for separating a crystal from a crucible by induction heating, the crystal being adhered to the inner wall of the crucible prior to separation; characterized in that the separation device comprises:

The induction heating coil of any one of claims 1-6, said induction heating coil being contoured around said crucible when induction heating is performed;

8. The separation device of claim 7, further comprising a protective chamber in which the induction heating coil and the load bearing structure are both disposed;

The protective chamber can be evacuated and/or replaced with a protective atmosphere.

9. The separation device of claim 7, wherein the side coils of the induction heating coil are equidistant from the side walls of the crucible and the bottom coils of the crucible and the bottom plate of the crucible.

10. The separation device of claim 7, wherein the carrier structure comprises a horizontally disposed carrier, the crucible is capable of being carried on a surface of the carrier, and the opening is directed in a direction of gravity.