CN116575114A - Seeding method - Google Patents

Seeding method Download PDF

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Publication number
CN116575114A
CN116575114A CN202310863980.7A CN202310863980A CN116575114A CN 116575114 A CN116575114 A CN 116575114A CN 202310863980 A CN202310863980 A CN 202310863980A CN 116575114 A CN116575114 A CN 116575114A
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China
Prior art keywords
cone
crystal
base
seeding
vertex angle
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CN116575114B (en
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曹建伟
欧阳鹏根
宋建军
石刚
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Ningxia Xinjingsheng Electronic Material Co ltd
Inner Mongolia Jinghuan Electronic Materials Co ltd
Zhejiang Jingsheng Mechanical and Electrical Co Ltd
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Ningxia Xinjingsheng Electronic Material Co ltd
Inner Mongolia Jinghuan Electronic Materials Co ltd
Zhejiang Jingsheng Mechanical and Electrical Co Ltd
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Publication of CN116575114A publication Critical patent/CN116575114A/en
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    • C—CHEMISTRY; METALLURGY
    • C30—CRYSTAL GROWTH
    • C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
    • C30B17/00—Single-crystal growth onto a seed which remains in the melt during growth, e.g. Nacken-Kyropoulos method
    • C—CHEMISTRY; METALLURGY
    • C30—CRYSTAL GROWTH
    • C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
    • C30B29/00—Single crystals or homogeneous polycrystalline material with defined structure characterised by the material or by their shape
    • C30B29/10—Inorganic compounds or compositions
    • C30B29/16—Oxides
    • C30B29/20—Aluminium oxides

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Inorganic Chemistry (AREA)
  • Crystals, And After-Treatments Of Crystals (AREA)

Abstract

The invention relates to a seeding method, which comprises the following steps: controlling seed crystal to carry out seeding to form a crystal junction; when the bottom cone of the crystal grows, controlling the bottom cone to move at the molten liquid level so as to change the radius of the cross section of the bottom cone at the molten liquid level; acquiring three data of the radius of the cross section of the bottom cone at the molten liquid level before moving, the radius of the cross section of the bottom cone at the molten liquid level after moving, the moving distance of the crystal and the change amount of the weighing value of the crystal before and after moving; obtaining the vertex angle value of the bottom cone based on the obtained three data; and adjusting control parameters in the seeding process based on the vertex angle value of the bottom cone. The invention solves the problem that the vertex angle value of the bottom cone cannot be detected below the molten liquid level.

Description

Seeding method
Technical Field
The invention relates to the field of sapphire preparation processes, in particular to a seeding method.
Background
The currently mainstream sapphire crystal growth process in the world is the kyropoulos method, which is to contact a chilled seed crystal with the melt to initiate the growth of the seed crystal. Seeding is a key step in the growth of crystals by the kyropoulos method, and aims to enable a tip cone and a base cone to grow on a seed crystal, and the following base cone grows into a crystal gradually in a melt. Suitable seeding can exclude dislocations and defects in the seed crystal, so that the crystal starts to grow from a perfect initial state, and thus the seeding quantity is largely related to the crystal quality.
However, since the base cone is positioned below the molten liquid surface when the kyropoulos method is adopted for sapphire crystal growth, the observation is difficult, the control of seeding quality is very difficult, the operation level and the experience value of technicians are very high, and correspondingly, some large-size sapphire crystals are difficult to obtain.
Disclosure of Invention
Accordingly, it is necessary to provide a seeding method for solving the problem that the seeding amount is difficult to control.
A seeding method, comprising:
controlling seed crystal to carry out seeding to form a crystal junction;
when the bottom cone of the crystal grows, controlling the bottom cone to move at the molten liquid level so as to change the radius of the cross section of the bottom cone at the molten liquid level;
acquiring any three data of the radius of the cross section of the bottom cone at the molten liquid level before moving, the radius of the cross section of the bottom cone at the molten liquid level after moving, the moving distance of the crystal and the change of the weighing value of the crystal before and after moving;
obtaining the vertex angle value of the bottom cone based on the obtained three data;
and adjusting control parameters in the seeding process based on the vertex angle value of the bottom cone.
The three data obtained by the invention are the radius of the cross section of the bottom cone at the molten liquid level before moving, the moving distance of the crystal and the change quantity of the weighing value of the crystal before and after moving.
The moving process of the bottom cone at the molten liquid level is that the bottom cone leaves the molten liquid, and after the bottom cone moves, the cross section of the bottom cone at the molten liquid level before moving is determined based on the position of the molten liquid level and the moving distance of the crystal, so that the radius of the cross section of the bottom cone at the molten liquid level before moving is obtained.
The invention moves the bottom cone for a plurality of times along the same direction so as to obtain the vertex angle value of the bottom cone for a plurality of times.
A seeding method, comprising:
controlling seed crystal to carry out seeding to form a crystal junction;
acquiring the gravity after the growth of the tip cone is completed;
after the bottom cone of the crystal grows, at least obtaining the bottom surface diameter of the bottom cone and the weighing value of the crystal;
obtaining a vertex angle value of the bottom cone at least based on a weighing value of the crystal, the gravity after the growth of the top cone is completed and the bottom surface diameter of the bottom cone;
and adjusting control parameters in the seeding process based on the vertex angle value of the bottom cone.
The method for judging whether the basal cone of the crystal grows or not comprises the following steps: and obtaining the bottom surface diameter of the tip cone at least twice in the crystal growth process, wherein if the bottom surface diameter of the tip cone is increased, the bottom cone does not start to grow, and if the bottom surface diameter of the tip cone stops increasing, the bottom cone starts to grow.
The invention obtains the resultant force of the bottom cone under the action of gravity and buoyancy based on the weighing value of the crystal and the gravity of the top cone, obtains the volume of the bottom cone based on the resultant force of the bottom cone under the action of gravity and buoyancy, and obtains the vertex angle value of the bottom cone based on the volume of the bottom cone and the bottom surface diameter of the bottom cone.
The invention obtains the volume of the bottom cone based on the resultant force of the bottom cone under the action of gravity and buoyancy, and comprises the following steps: and obtaining the density difference between the molten mass used in the seeding process and the bottom cone, and obtaining the volume of the bottom cone based on the density difference, the gravity acceleration and the resultant force of the bottom cone under the action of gravity and buoyancy.
The method comprises the steps of presetting a vertex angle threshold of a bottom cone, obtaining a buoyancy threshold of the bottom cone based on the vertex angle threshold of the bottom cone, setting the buoyancy borne by the bottom cone based on the buoyancy threshold of the bottom cone, so as to obtain the gravity of the bottom cone, obtaining the density of the bottom cone, and obtaining the volume of the bottom cone based on the gravity and the density of the bottom cone.
The two vertex angle thresholds of the base cone are respectively a vertex angle upper limit threshold and a vertex angle lower limit threshold, wherein the vertex angle lower limit threshold is 35 degrees, and the vertex angle upper limit threshold is 60 degrees.
The beneficial effects of the invention at least comprise one of the following:
1. when the bottom cone is moved, the buoyancy change and the lifting height of the bottom cone can be known, and the geometrical characteristics of the bottom cone are utilized to calculate the vertex angle value of the bottom cone, so that the problem that the vertex angle value of the bottom cone cannot be detected below the molten liquid level is solved;
2. if the bottom cone does not move, the vertex angle value of the bottom cone is reversely pushed by utilizing the gravity data and the geometric characteristics of the bottom cone, and the problem that the vertex angle value of the bottom cone cannot be detected below the molten liquid level is solved;
3. the apex angle value of the bottom cone is detected to guide the regulation and control of the seeding process parameters, so that the seeding quality is improved, and a foundation is laid for growing large-size crystals by adopting a kyropoulos method;
4. the seeding method can be further transferred to the crystal shouldering and crystal growing stages, and lays a foundation for the full-automatic crystal growing process.
Drawings
FIG. 1 is a schematic diagram of a device corresponding to step S1, step A1, and step B1 in the embodiment of the present invention;
fig. 2 is a schematic structural diagram of a corresponding device in step S2, step A2, and step B2 in the embodiment of the present invention;
FIG. 3 is a schematic diagram of a device corresponding to step S3, step A3, and step B3 in the embodiment of the present invention;
fig. 4 is a schematic diagram of a second device corresponding to step S4, step A4, and step B4 in the embodiment of the present invention;
FIG. 5 is a schematic diagram of the structure of the corresponding device in step S4 and step B4 according to the embodiment of the present invention;
FIG. 6 is a schematic diagram of a crystal structure according to an embodiment of the present invention;
FIG. 7 is a schematic diagram of a corresponding device in step A4 according to an embodiment of the present invention;
fig. 8 is a schematic diagram of a second structure of the corresponding device in step A4 according to an embodiment of the present invention.
Reference numerals:
1. a lifting rod; 2. seed crystal; 21. a tip cone; 22. a bottom cone; 3. a crucible; 4. a molten mass; 41. the melt level.
Detailed Description
In order that the above objects, features and advantages of the invention will be readily understood, a more particular description of the invention will be rendered by reference to the appended drawings. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. The present invention may be embodied in many other forms than described herein and similarly modified by those skilled in the art without departing from the spirit of the invention, whereby the invention is not limited to the specific embodiments disclosed below.
In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings are merely for convenience in describing the present invention and simplifying the description, and do not indicate or imply that the device or element being referred to must have a specific orientation, be configured and operated in a specific orientation, and therefore should not be construed as limiting the present invention.
Furthermore, the terms "first," "second," and the like, are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include at least one such feature. In the description of the present invention, the meaning of "plurality" means at least two, for example, two, three, etc., unless specifically defined otherwise.
In the present invention, unless explicitly specified and limited otherwise, the terms "mounted," "connected," "secured," and the like are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally formed; can be mechanically or electrically connected; either directly or indirectly, through intermediaries, or both, may be in communication with each other or in interaction with each other, unless expressly defined otherwise. The specific meaning of the above terms in the present invention can be understood by those of ordinary skill in the art according to the specific circumstances.
In the present invention, unless expressly stated or limited otherwise, a first feature "up" or "down" a second feature may be the first and second features in direct contact, or the first and second features in indirect contact via an intervening medium. Moreover, a first feature being "above," "over" and "on" a second feature may be a first feature being directly above or obliquely above the second feature, or simply indicating that the first feature is level higher than the second feature. The first feature being "under", "below" and "beneath" the second feature may be the first feature being directly under or obliquely below the second feature, or simply indicating that the first feature is less level than the second feature.
It will be understood that when an element is referred to as being "fixed" or "disposed" on another element, it can be directly on the other element or intervening elements may also be present. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and the like are used herein for illustrative purposes only and are not meant to be the only embodiment.
The traditional seeding method comprises the following steps:
step S1: referring to fig. 1, a seed crystal 2 is arranged at the bottom of a lifting rod 1, a crucible 3 is arranged below the seed crystal 2, a molten mass 4 formed after a material required for crystallization is melted is arranged in the crucible 3, wherein the distance between the seed crystal 2 and a molten liquid surface 41 (namely, the liquid surface of the molten mass 4) is 100mm, then the lifting rod 1 drives the seed crystal 2 to descend at a speed of 20mm/min until the seed crystal 2 reaches the molten liquid surface 41, and meanwhile, a temperature detection device or equipment is used for detecting the central temperature of the molten mass 4, and power is adjusted to enable the central temperature of the molten mass 4 to reach a target value.
Step S2: referring to fig. 2, the pulling rod 1 drives the seed crystal 2 to descend below the molten liquid surface 41 at a speed of not more than 5mm/min until the seed crystal 2 is inserted 40mm below the molten liquid surface 41, and then controls the seed crystal 2 to rotate at a rotational speed of 30rpm or more so that volatiles on the surface of the seed crystal 2 are removed.
Step S3: referring to fig. 3-4, the seed crystal 2 is pulled by the pulling rod 1 during rotation, the seed crystal 2 gradually leaves the melt 4, and in the process, the rotation speed and the pulling speed of the seed crystal 2 are regulated to obtain regulation control, so that the tip cone 21 grows gradually on the seed crystal 2 until the tip cone 21 is positioned at the melt level 41, and when the seed crystal 2 is completely positioned above the melt level 41, the tip cone 21 is conical, and the tip cone 21 is small at the top and large at the bottom, namely, the tip cone 21 is an upright cone. In which the volume of the seed crystal 2 is small, it is considered that the shape of the tip cone 21 is not affected.
Step S4: referring to fig. 5, the pulling rod 1 controls the seed crystal 2 to rotate, so that the lower part of the tip cone 21 is gradually crystallized to form a base cone 22, the base cone 22 is in a conical shape, but the base cone 22 is in an inverted conical shape with the upper part being small, and the base cone 22 and the tip cone 21 share the bottom surface, so that the bottom radii of the base cone 22 and the tip cone 21 are the same. The seed crystal 2 is merely rotated in this process, and is not lifted up or moved down. The seed crystal 2, the bottom cone 22 and the top cone 21 together form a crystal junction.
The bottom cone 22 is located below the molten liquid surface 41, and after the seeding of the bottom cone 22 is finished, sapphire crystals are further crystallized below the molten liquid surface 41, so that the seeding effect of the bottom cone 22 is important for the subsequent sapphire crystal generation process. In particular, referring to fig. 6, the apex angle value α of the base cone 22 is an important factor for evaluating the seeding quality of the base cone 22, and α corresponds to an apex angle threshold, specifically includes an apex angle upper limit threshold and an apex angle lower limit threshold, and the seeding effect of the base cone 22 can be considered to be good as long as the value α is between the apex angle upper limit threshold and the apex angle lower limit threshold. Empirically, the upper corner threshold is typically 60 ° and the lower corner threshold is typically 35 °.
The growth process of the base cone 22 is understood to be a process in which the radius of the bottom surface is constant and the apex angle α is changed, and since the growth process of the base cone 22 is performed below the molten liquid surface 41, the change state of the apex angle α is difficult to be directly observed.
Example 1:
aiming at the problem that the vertex angle value alpha is difficult to obtain, the embodiment provides a seeding method, which comprises the following steps:
step A1: referring to fig. 1 as well, a seed crystal 2 is arranged at the bottom of a lifting rod 1, a crucible 3 is arranged below the seed crystal 2, a molten mass 4 formed after a material required for crystallization is melted is arranged in the crucible 3, wherein the distance between the seed crystal 2 and the molten mass surface 41 (namely, the liquid surface of the molten mass 4) is 100mm, then the lifting rod 1 drives the seed crystal 2 to descend at a speed of 20mm/min until the seed crystal 2 reaches the molten mass surface 41, and meanwhile, a temperature detection device or equipment is used for detecting the central temperature of the molten mass 4, and power is adjusted to enable the central temperature of the molten mass 4 to reach a target value.
Step A2: referring also to fig. 2, the pull rod 1 drives the seed crystal 2 to descend below the molten liquid surface 41 at a speed of not more than 5mm/min until the seed crystal 2 is inserted 40mm below the molten liquid surface 41, and then the seed crystal 2 is controlled to rotate at a rotational speed of 30rpm or more so that volatiles on the surface of the seed crystal 2 are removed.
Step A3: referring to fig. 3-4, the seed crystal 2 is pulled by the pulling rod 1 during rotation, the seed crystal 2 gradually leaves the melt 4, and in the process, the rotation speed and the pulling speed of the seed crystal 2 are regulated to obtain regulation control, so that the tip cone 21 grows gradually on the seed crystal 2 until the tip cone 21 is positioned at the melt level 41, when the seed crystal 2 is completely positioned above the melt level 41, the tip cone 21 is conical, and the tip cone 21 is small at the top and large at the bottom, namely, the tip cone 21 is an upright cone.
Step A4: referring to fig. 7-8, the pulling rod 1 controls the seed crystal 2 to rotate, so that the lower part of the tip cone 21 is gradually crystallized to form the base cone 22, and after the base cone 22 grows for a period of time, the crystal is pulled by the pulling rod 1, so that the base cone 22 moves at the molten liquid level 41, and accordingly, the radius of the cross section of the base cone 22 at the molten liquid level 41 is changed.
Wherein the radius of the cross section of the base cone 22 at the melt level 41 before moving is r 1 The radius of the cross section of the base cone 22 at the melt level 41 after movement is r 2 . The movement distance of the crystal is h.
The lifting rod 1 has a weighing function, which provides a pulling force to the crystal, and the weighing value of the lifting rod 1 reflects the pulling force provided by the lifting rod and can also be regarded as the weighing value obtained by weighing the crystal. The stress analysis of the crystal (seed crystal 2, base cone 22 and tip cone 21) shows that the crystal is subjected to the pulling force of the pulling rod 1, the gravity of the pulling rod and the buoyancy of the melt 4. Before and after the movement, only the bottom cone 22 is in the melt 4, and the top cone 21 is always above the melt surface 41, so that the buoyancy of the crystals is only obtained by the cooperation of the bottom cone 22 and the melt 4. Before and after the movement of the crystals, the volume of the base cone 22 in the melt 4 is changed, and the buoyancy of the corresponding crystals is also changed, so that the weighing value obtained by weighing the crystals by the lifting rod 1 is also changed, and the change amount of the weighing value is delta G.
In this embodiment, only r is acquired 1 、r 2 Three data in h and δg are sufficient. Need to obtain r 1 The crystal can be obtained by a thermal imager before being pulled, or can be obtained by finding the corresponding part from the crystal by the thermal imager after being pulled. Need to obtain r 2 When the crystal is pulled, the crystal can be obtained by a thermal imager. h can be obtained by a control program of the lifting rod 1, and can also be obtained by a thermal imagerAnd (5) comparing the images to obtain the image. δg can be obtained by comparing the weighing values of the lifting rod 1 before and after the crystal is lifted.
Step A51: if only r is obtained in step A4 1 、r 2 H, δg is not obtained, sin (α/2) = (r) based on geometric relationship 1 -r 2 ) And/h, thereby directly solving for the value of alpha.
Step A52: if δG is obtained in step A4, r is not obtained 1 、r 2 And h, solving the value of alpha through the step. Specifically, δG is equal to the buoyancy change of the crystal before and after being pulled, that is, ρ Melting gV Row of rows Wherein ρ is Melting For the density of the melt 4, which is a known constant, g is the gravitational acceleration, V Row of rows The volume of the portion of the crystal newly exposed above the melt surface 41 after being pulled is the truncated cone shape. Thus V can be calculated from δG Row of rows Is a numerical value of (2). Based on the geometric relationship, V Row of rows =π×h×(r 1 2 +r 1 r 2 +r 2 2 ) 3, from which r can be solved 1 、r 2 Data not obtained in h. Then based on sin (α/2) = (r) 1 -r 2 ) And/h, solving to obtain the value of alpha.
Step A6: if the α value obtained by solving in step a51 or step a52 is outside the upper limit threshold and the lower limit threshold of the top angle, that is, greater than 60 ° or less than 35 °, the crystal needs to continue sinking, so that the base cone 22 returns to the position below the molten liquid surface 41 again to further accelerate seeding growth, and the seeding process is coordinated with adjusting control parameters, such as the rotation speed of the crystal, or the seeding needs to be stopped after the crystal returns to the position below the molten liquid surface 41. If the alpha value is between the upper limit threshold value and the lower limit threshold value, that is, greater than 35 degrees and less than 60 degrees, the crystal can continue seeding after returning to the position below the molten liquid level 41, or the seeding can be stopped.
In other embodiments, the crystal may be pulled first, then the base cone 22 is moved down below the melt level 41, and r is obtained during the downward movement 1 、r 2 Three data in h and δGThus calculating the value of α, the process should be regarded as an equivalent of the present embodiment.
Example 2:
this example further optimizes step a52 based on example 1, wherein r is obtained in step a52 1 Delta G and h.
The temperature at the melt level is high, and it is difficult to accurately obtain r by a thermal imager 2 Is an accurate value of (a). And after the crystal is pulled, the bottom cone corresponds to r 1 Has a distance h from the melt level, i.e. r can be determined based on h and the melt level position 1 The corresponding cross section of the bottom cone is obtained by the thermal imager at the moment 1 The numerical accuracy is high. h and δG can be obtained by a control program of the lifting rod and a weighing device.
Further, r 1 And r 2 The acquisition modes of the system are all through a thermal imager, and the data precision of the thermal imager is lower than the numerical control precision on the lifting rod, so that the detection data precision and the accuracy of delta G and h are higher than r 1 And r 2 Thereby r 1 And r 2 In which only r is used 1 The numerical calculation of alpha is participated, and the result accuracy of alpha is higher.
Example 3:
the present embodiment differs from embodiment 1 in that steps A4, a51 and a52 are repeated a plurality of times so that the crystals are pulled a plurality of times. Based on the actual production situation, the base cone may not be a strictly regular cone, so that an α value can be calculated after each crystal is pulled, an average value is obtained for all the calculated α values, and based on the average value of the apex angle values α, the control parameters in seeding are controlled in step A6.
Example 4:
aiming at the problem that the vertex angle value alpha is difficult to obtain in the prior art, the embodiment also provides a seeding method, which comprises the following steps:
step B1: referring to fig. 1 as well, a seed crystal 2 is arranged at the bottom of a lifting rod 1, a crucible 3 is arranged below the seed crystal 2, a molten mass 4 formed after a material required for crystallization is melted is arranged in the crucible 3, wherein the distance between the seed crystal 2 and the molten mass surface 41 (namely, the liquid surface of the molten mass 4) is 100mm, then the lifting rod 1 drives the seed crystal 2 to descend at a speed of 20mm/min until the seed crystal 2 reaches the molten mass surface 41, and meanwhile, a temperature detection device or equipment is used for detecting the central temperature of the molten mass 4, and power is adjusted to enable the central temperature of the molten mass 4 to reach a target value.
In this step, the pulling force of the pull rod 1 is equal to the gravity of the seed crystal 2.
Step B2: referring also to fig. 2, the pull rod 1 drives the seed crystal 2 to descend below the molten liquid surface 41 at a speed of not more than 5mm/min until the seed crystal 2 is inserted 40mm below the molten liquid surface 41, and then the seed crystal 2 is controlled to rotate at a rotational speed of 30rpm or more so that volatiles on the surface of the seed crystal 2 are removed.
Step B3: referring to fig. 3-4, the seed crystal 2 is pulled by the pulling rod 1 during rotation, the seed crystal 2 gradually leaves the melt 4, and in the process, the rotation speed and the pulling speed of the seed crystal 2 are regulated to obtain regulation control, so that the tip cone 21 grows gradually on the seed crystal 2 until the tip cone 21 is positioned at the melt level 41, when the seed crystal 2 is completely positioned above the melt level 41, the tip cone 21 is conical, and the tip cone 21 is small at the top and large at the bottom, namely, the tip cone 21 is an upright cone.
In this step, when the seed crystal 2 is completely located above the melt level 41, the pulling force of the pull rod 1 is equal to the sum of the weight of the seed crystal 2 and the weight of the tip cone 21, and the weight G of the tip cone 21 can be obtained from the weight of the seed crystal 2 obtained in step B1 1 And the bottom surface radius R of the tip cone 21 can be obtained by a thermal imager.
Step B4: referring to fig. 5, the pull rod 1 controls rotation of the seed crystal 2 so that the lower part of the tip cone 21 is gradually crystallized to form the base cone 22. The bottom cone 22 is also conical, has a large upper part and a small lower part, is an inverted cone, and the bottom cone 22 and the top cone 21 share the bottom surface, so that the bottom radii of the bottom cone 22 and the top cone 21 are the same, and are both R. At this time, the pulling force value of the pulling rod 1 (i.e., the weighing value of the crystal) subtracts the weight of the seed crystal 2 obtained in step B1 and the weight of the tip cone 21 obtained in step B3, i.e., the weighing value of the base cone 22.
Step B51: taking into account the buoyancy of the melt 4 on the base cone 22As can be seen from the stress analysis of the crystals, the weighing value of the bottom cone 22 is equal to the weight of the bottom cone 22 minus the buoyancy of the bottom cone 22, i.e. the weighing value of the bottom cone 22 is the resultant of the weight of the bottom cone 22 and the buoyancy. The weighing value of the base cone 22 is F, then f= (ρ) Bottom cone -ρ Melting ）gV Bottom cone Wherein ρ is Melting For the density of the melt 4 ρ Bottom cone The density of the base cone 22, g is gravity acceleration, V Bottom cone Is the volume of the base cone 22.ρ Melting And ρ Bottom cone Are all known constants, therefore ρ Bottom cone -ρ Melting The values of (2) are known. Thus V can be calculated from F Bottom cone . According to the conical volume formula, V Bottom cone =πR 2 H/3, where H is the height of the base cone 22, tan (α/2) =h/R, whereby the value of α can be solved.
Step B52: the bottom cone 22 has a gravity ρ of itself Bottom cone gV Bottom cone The buoyancy of the buoyancy is ρ Melting gV Bottom cone Due to ρ Bottom cone Is generally much larger than ρ Melting The buoyancy experienced by the base cone 22 is therefore also approximately negligible. Whereby the weighing value F of the base cone 22 is approximately equal to the self-gravity ρ of the base cone 22 Bottom cone gV Bottom cone From this calculation V Bottom cone . According to the conical volume formula, V Bottom cone =πR 2 H/3, where H is the height of the base cone 22, tan (α/2) =h/R, whereby the value of α can be solved.
Step B53: the weighing value F of the bottom cone 22 is equal to the gravity of the bottom cone 22 minus the buoyancy born by the bottom cone 22, and the self gravity of the bottom cone 22 is ρ Bottom cone gV Bottom cone Thus f=f Floating device +ρ Bottom cone gV Bottom cone ，F Floating device Is subject to buoyancy by the base cone 22. F (F) Floating device =ρ Melting gV Bottom cone Due to ρ Melting Much smaller than ρ Bottom cone Thus F Floating device /(ρ Bottom cone gV Bottom cone ) Is very small, thus F Floating device Comparison ρ Bottom cone gV Bottom cone Can be considered as a certain value. F (F) Floating device A fixed value can be selected to calculate V in coordination with the weighing value F of the base cone 22 Bottom cone According to the conical volume formula, V Bottom cone =πR 2 H/3, where H is the height of the base cone 22, tan (α/2) =h/R, whereby the value of α can be solved. F (F) Floating device The specific value of (c) may be selected empirically.
Step B6: and (3) according to the alpha value obtained by solving in the step B51, the step B52 or the step B53, adjusting control parameters in the seeding process, such as the rotating speed of the base cone 22, so as to control the seeding state and the seeding progress of the base cone 22.
Example 5:
this embodiment further provides an F based on step B53 in embodiment 4 Floating device The method for taking the value of (a) specifically comprises the following steps:
step B531: two vertex angle thresholds of the base cone are preset, wherein one vertex angle threshold is a vertex angle upper limit threshold, the vertex angle upper limit threshold in the embodiment is 60 degrees, the other vertex angle threshold is a vertex angle lower limit threshold, and the vertex angle lower limit threshold in the embodiment is 35 degrees, namely alpha is assumed to be between 35 degrees and 60 degrees.
Step B532: based on the bottom radii R and tan (α/2) =h/R of the resulting base cone, a range of values of high H of the base cone can be obtained, whereby the volume V of the base cone can be obtained Bottom cone Based on F Floating device =ρ Melting gV Bottom cone It can be known that the threshold value of the buoyancy of the base cone corresponds to two vertex angle threshold values (upper vertex angle threshold value and lower vertex angle threshold value), F Floating device There are also two corresponding buoyancy thresholds (upper buoyancy threshold and lower buoyancy threshold), corresponding to F Floating device Any value between the upper buoyancy threshold and the lower buoyancy threshold may be selected.
Example 6:
the present embodiment provides a method of judging whether or not the formation of the under cone is started, which is performed between step B3 and step B4 of embodiment 4.
The method specifically comprises the steps of lifting the top cone so that the lower bottom surface of the top cone moves to be above the molten liquid level, detecting the bottom surface radius R of the top cone through a thermal imaging instrument, and then moving the top cone downwards to the molten liquid level again. The pulling action of the tip cone is repeated at least 2 times to perform at least 2 detections of R. If R continues to increase, it is indicated that the tip cone is still seeding and the corresponding base cone has not yet begun to grow. If R stops increasing, the end cone is finished seeding, and the corresponding bottom cone starts seeding growth. Thus, the weighing value of the base cone can also be obtained.
The technical features of the above-described embodiments may be arbitrarily combined, and all possible combinations of the technical features in the above-described embodiments are not described for brevity of description, however, as long as there is no contradiction between the combinations of the technical features, they should be considered as the scope of the description.
The above examples illustrate only a few embodiments of the invention, which are described in detail and are not to be construed as limiting the scope of the invention. It should be noted that it will be apparent to those skilled in the art that several variations and modifications can be made without departing from the spirit of the invention, which are all within the scope of the invention. Accordingly, the scope of protection of the present invention is to be determined by the appended claims.

Claims (10)

1. A method of seeding, comprising:
controlling seed crystal to carry out seeding to form a crystal junction;
when the bottom cone of the crystal grows, controlling the bottom cone to move at the molten liquid level so as to change the radius of the cross section of the bottom cone at the molten liquid level;
acquiring any three data of the radius of the cross section of the bottom cone at the molten liquid level before moving, the radius of the cross section of the bottom cone at the molten liquid level after moving, the moving distance of the crystal and the change of the weighing value of the crystal before and after moving;
obtaining the vertex angle value of the bottom cone based on the obtained three data;
and adjusting control parameters in the seeding process based on the vertex angle value of the bottom cone.
2. The seeding method according to claim 1, wherein the three data obtained are a radius of a cross section of the base cone at the molten liquid surface before moving, a moving distance of the crystal, and a change amount of a weighing value of the crystal before and after moving.
3. The seeding method according to claim 1, wherein the movement of the base cone at the melt level is away from the melt, and wherein after the movement of the base cone, a cross section of the base cone at the melt level before the movement is determined based on the melt level position and the movement distance of the crystal, thereby obtaining a radius of the cross section of the base cone at the melt level before the movement.
4. The seeding method according to claim 1, wherein the base cone is moved multiple times in the same direction to obtain the apex angle value of the base cone multiple times.
5. A method of seeding, comprising:
controlling seed crystal to carry out seeding to form a crystal junction;
acquiring the gravity after the growth of the tip cone is completed;
after the bottom cone of the crystal grows, at least obtaining the bottom surface diameter of the bottom cone and the weighing value of the crystal;
obtaining a vertex angle value of the bottom cone at least based on a weighing value of the crystal, the gravity after the growth of the top cone is completed and the bottom surface diameter of the bottom cone;
and adjusting control parameters in the seeding process based on the vertex angle value of the bottom cone.
6. The seeding method according to claim 5, wherein the method for judging whether the basal cone of the crystal starts to grow comprises: and obtaining the bottom surface diameter of the tip cone at least twice in the crystal growth process, wherein if the bottom surface diameter of the tip cone is increased, the bottom cone does not start to grow, and if the bottom surface diameter of the tip cone stops increasing, the bottom cone starts to grow.
7. The seeding method according to claim 5, wherein a resultant force of the base cone under the action of gravity and buoyancy is obtained based on a weighing value of the crystal and a gravity of the tip cone, a volume of the base cone is obtained based on the resultant force of the base cone under the action of gravity and buoyancy, and a vertex angle value of the base cone is obtained based on the volume of the base cone and a bottom surface diameter of the base cone.
8. The seeding method according to claim 7, wherein obtaining the volume of the base cone based on the resultant force of the base cone under the action of gravity and buoyancy comprises: and obtaining the density difference between the molten mass used in the seeding process and the bottom cone, and obtaining the volume of the bottom cone based on the density difference, the gravity acceleration and the resultant force of the bottom cone under the action of gravity and buoyancy.
9. The seeding method according to claim 7, wherein a vertex angle threshold of the base cone is preset, a buoyancy threshold of the base cone is obtained based on the vertex angle threshold of the base cone, buoyancy to which the base cone is subjected is set based on the buoyancy threshold of the base cone, so as to obtain gravity of the base cone, density of the base cone is obtained, and volume of the base cone is obtained based on the gravity and density of the base cone.
10. The seeding method according to claim 9, wherein the number of the vertex angle thresholds of the base cone is two, namely a vertex angle upper limit threshold and a vertex angle lower limit threshold, the vertex angle lower limit threshold is 35 degrees, and the vertex angle upper limit threshold is 60 degrees.
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