JP4276497B2 - Single crystal manufacturing method and apparatus - Google Patents

Description

  The present invention relates to a method and an apparatus for producing a single crystal such as an oxide.

Currently, various oxide single crystals are industrially applied as optical devices and acoustic devices. These oxides are mainly produced by a method called the Czochralski method (CZ method). The CZ method is a method for obtaining a large, high-quality bulk single crystal at a low cost for the same material, for example, Si, LiNbO ₃ , LiTaO _3, etc., in which the melt and the crystal composition deposited from the melt are the same. This is a very important single crystal manufacturing method. In particular, when producing oxide single crystals, the high-frequency heating system has a large heat capacity and low thermal conductivity compared to metals, and therefore has a high-frequency heating method that tends to have a relatively large temperature gradient in the crystal growth atmosphere in the production apparatus. There are many examples using manufacturing equipment.

  However, many industrially useful oxide single crystals have a large anisotropy and have a problem that defects such as cracks are likely to occur due to thermal stress caused by a large temperature gradient. On the other hand, under a small temperature gradient, the solidification latent heat generated at the crystal growth interface and the heat transferred from the melt cannot be dissipated, and the crystal is twisted or bent, so that only a short single crystal can be obtained. There is also a problem.

  Therefore, in order to solve these problems, each company that manufactures oxide single crystals repeats trial and error for the structure of the structure around the crucible independently of the single crystal material to be manufactured.

  The factor that makes it difficult to produce a long single crystal by the CZ method is that the temperature gradient near the interface of crystal growth, which has a great influence on the occurrence of cracks and twists, is the initial and late stages of single crystal growth. It changes during the production of crystals. This is because the melt surface decreases as the crystal grows, and when the exposed portion of the high-frequency induction heated crucible wall increases, the exposed crucible wall acts as an after heater, and as a result, the temperature just above the melt. This is to reduce the gradient. In other words, if the initial stage of growth is maintained at an appropriate temperature gradient, the temperature gradient immediately above the melt decreases as crystallization progresses, and the solidification radiant heat during crystallization cannot be sufficiently dissipated in the later stage of crystallization. Appears as a twist of crystal. On the other hand, if the crystal is grown at a later stage in which the twist does not occur, the temperature gradient in the initial stage of the growth becomes too large, which causes a disadvantage that the crystal is cracked.

  Therefore, in recent years, for the purpose of solving this problem, for example, a method of manufacturing by changing the relative position of the crucible and the high frequency coil according to the progress of crystal manufacturing (Patent Documents 1 to 3), radiation that can be raised and lowered in the crucible There have been proposed a method of manufacturing a heat reflector by raising the crucible upward as the pulling length increases (Patent Document 4) and a method of manufacturing using a seed holder having a high thermal conductivity (Patent Document 5).

  When these methods are classified, according to the progress of crystal production, (1) a method of changing the calorific value distribution of the crucible (Patent Documents 1 to 3) or (2) a method of changing the amount of radiant heat from the crystal (Patent Document 4). And (3) a method of increasing the amount of heat transfer from the crystal throughout the production of the crystal (Patent Document 5).

However, when the crystal has absorption of infrared and visible light, the amount of radiant heat absorbed is significantly increased by lengthening the grown crystal itself, and the above methods (1) to (3) are sufficiently long. There was a case that could not be performed.
Japanese Patent Publication No.58-25078 Japanese Examined Patent Publication No. 61-05440 Japanese Patent Publication No.61-26519 Japanese Patent Laid-Open No. 08-175896 JP 11-278984 A

  An object of the present invention is to provide a single crystal manufacturing method and apparatus capable of manufacturing a high-quality single crystal that can be lengthened even when the crystal has absorption of infrared and visible light. That is.

  The present inventor pays attention to the radiant heat transfer to the crystal directly emitted from the crucible, which is not considered in the inventions of (1) to (3), and by providing a specific structure at a predetermined position in the apparatus. Further, even when the conditions are set so that the initial stage of growth is maintained at an appropriate temperature gradient, it has been found that relaxation of the temperature gradient immediately above the melt can be suppressed during crystal growth, particularly in the later stage of growth. Was completed.

According to the manufacturing method, ie the first aspect of the present invention,
A method for producing a single crystal in which a seed crystal is brought into contact with a melt in a crucible and pulled up, and a single crystal is grown on the lower end of the seed crystal,
A structure (radiant heat transfer suppressing structure) that suppresses the movement of radiant heat between the inner wall of the crucible and the single crystal that grows at the lower end of the seed crystal and does not contact the melt in the crucible. There is provided a method for producing a single crystal, characterized in that the single crystal is produced using an apparatus provided.

  In the first aspect, the arrangement of the radiant heat transfer suppressing structure in the apparatus is not particularly limited, and may be provided so as to be movable as the single crystal grows, or may be fixed in the apparatus. It may be provided. From the viewpoint of increasing the temperature gradient immediately above the melt, it is preferable that the temperature gradient is provided as the crystal grows.

That is, according to the second aspect,
A method for producing a single crystal in which a seed crystal is brought into contact with a melt in a crucible and pulled up, and a single crystal is grown on the lower end of the seed crystal,
Using an apparatus in which a radiant heat transfer suppression structure is provided movably between the inner wall of the crucible and the single crystal grown on the lower end of the seed crystal and at a position not in contact with the melt in the crucible, There is provided a method for producing a single crystal, wherein the single crystal is produced while moving the radiant heat transfer suppressing structure in conjunction with the growth of the single crystal attached to the lower end of the seed crystal.

  In the second aspect, the method of moving the radiant heat transfer suppressing structure is not particularly limited, and may be moved so as to keep the distance from the melt liquid surface constant, or the distance may not be kept constant. You may move it like this. It is the crystal growth interface that has the greatest influence on defects such as crystal twist and cracks. This crystal growth interface is lowered by the amount of crystallized unless the melt as a raw material is continuously supplied during crystal growth. If no allowance is provided for this reduced amount, the effect (increasing the temperature gradient immediately above the melt) obtained when the radiant heat transfer suppressing structure is provided may not be fully enjoyed. Therefore, in the present invention, it is preferable to move the radiant heat transfer suppressing structure so that the distance from the melt surface is kept constant in accordance with the decrease in the melt surface during growth.

That is, according to the third aspect,
A method for producing a single crystal in which a seed crystal is brought into contact with a melt in a crucible and pulled up, and a single crystal is grown on the lower end of the seed crystal,
Using an apparatus in which a radiant heat transfer suppression structure is provided movably between the inner wall of the crucible and the single crystal grown on the lower end of the seed crystal and at a position not in contact with the melt in the crucible, The single crystal is manufactured while moving the radiant heat transfer suppressing structure so as to maintain a constant distance from the melt surface in conjunction with the growth of the single crystal attached to the lower end of the seed crystal. A method for producing a single crystal is provided.

  The distance held between the melt and the liquid surface is preferably 2 to 8 mm, more preferably 3 to 7 mm, and still more preferably 4 to 6 mm. By moving the radiant heat transfer suppressing structure while maintaining such a distance, the temperature gradient immediately above the melt can be effectively increased.

  The method of the present invention described above can be realized by, for example, the following apparatus.

Manufacturing apparatus According to the present invention,
An apparatus for producing a single crystal in which a seed crystal is brought into contact with the melt in the crucible and pulled up, and a single crystal is grown on the lower end of the seed crystal,
A first movement axis for pulling up the seed crystal;
Radiation heat transfer suppression structure provided between the inner wall of the crucible and the single crystal growing on the lower end of the seed crystal, and at a position not in contact with the melt in the crucible,
There is provided a single crystal manufacturing apparatus having a second movement axis that moves the radiant heat transfer suppressing structure in conjunction with the growth of the single crystal attached to the lower end of the seed crystal.

Common Items Preferably, the radiant heat transfer suppressing structure is made of a platinum group metal alone or an alloy thereof.

  Preferably, a melt heated by high frequency induction heating is used.

  Preferably, the melt and the single crystal are oxides. That is, the present invention is particularly suitable for the production of oxide single crystals.

  According to the present invention, since it is possible to suppress the relaxation of the temperature gradient immediately above the melt during crystal growth, even if the crystal has absorption of infrared and visible light, it can be made long and has high quality. Single crystal can be produced.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  Here, FIG. 1 is a schematic cross-sectional view showing an apparatus for producing a single crystal according to an embodiment of the present invention, FIG. 2 is a cross-sectional view taken along line II-II in FIG. 1, FIG. 3, FIG. 4B, FIG. 5 and FIG. 6 are perspective views showing one aspect of the radiant heat transfer suppressing structure used in the present embodiment. FIG. 7 shows which radiant heat transfer suppressing structure used in the present embodiment has a temperature gradient. It is a graph which shows whether it has such an influence.

  In the present embodiment, first, the configuration of an apparatus capable of realizing the method for manufacturing a single crystal according to the present invention will be described, and then a method for manufacturing a single crystal using this apparatus will be described.

Single Crystal Manufacturing Apparatus As shown in FIG. 1, a single crystal manufacturing apparatus 2 according to this embodiment includes a crucible 4. The crucible 4 is arranged in a recess 62 formed in a substantially central portion of the heat insulating material 6. The heat insulating material 6 is covered with a cylindrical first refractory structure 8 so as to cover the crucible 4. The heat insulating material 6 and the first refractory structure 8 are covered with a cylindrical second refractory structure (housing) 10.

  Openings 82 and 102 are formed at substantially the center positions of the top walls of the first refractory structure 8 and the second refractory structure 10, respectively. Inserted into the openings 82 and 102 is a first moving shaft 12 that is movable at a predetermined speed upward (in a direction away from the crucible 4) while rotating at a predetermined rotation speed. A seed crystal 122 is attached to the lower end of the first moving shaft 12. A power source (not shown) is connected to the upper end of the first moving shaft 12.

  Openings 84 and 104 are formed at positions separated from the center of the top wall of the first refractory structure 8 and the second refractory structure 10 by a predetermined distance, respectively. In the present embodiment, the second moving shaft 13 that is movable downward (in the direction toward the crucible 4) at a predetermined speed is inserted into the openings 84 and 104. A radiant heat shielding structure 132 is attached to the lower end of the second moving shaft 13. A power source (not shown) different from the power source (not shown) connected to the upper end of the first moving shaft 12 is connected to the upper end of the second moving shaft 13.

As shown in FIGS. 1 and 2, the radiant heat shield structure 132, between the single crystal 124 is grown on the inner wall and the lower end of the seed crystal 122 of the crucible 4, and contact with the melt 42 in the crucible 4 It is provided in a position that does not.

The effect obtained by providing the radiant heat shielding structure 132 at the predetermined position will be described. First, the radiant heat transfer amount q per unit area between the infinite planes A and B whose temperatures are T ₁ and T ₂ , respectively, is given by q = σ ( T ₁ ⁴ −T ₂ ⁴ )... In the formula (1), σ is a Stefan-Boltzmann constant.

  Further, consider a case where an infinite flat plate C having an infinitesimal thickness and an emissivity of ε is inserted between the infinite flat planes A and B in parallel with the infinite flat plates A and B.

Since the thickness of the infinite flat plate C is infinitely small, both surface temperatures of the infinite plane C can be regarded as T ₃ . Here, the amount of radiant heat transfer q ₁ per unit area between the infinite flat plates A and C is q ₁ = εσ (T ₁ ⁴ −T ₃ ⁴ ) Equation (2).

Similarly, the amount of radiant heat transfer q ₂ per unit area between the infinite flat plates B and C is q ₂ = εσ (T ₃ ⁴ −T ₂ ⁴ ) (3).

The amount of radiant heat transfer q ′ per unit area between the infinite planes A and B due to the insertion of the infinite plane C satisfies q ′ = q ₁ = q ₂ Equation (4). from _{q 1 = q 2, εσ (} T 1 4 -T 3 4) = εσ (T 3 4 -T 2 4) ... (5) is obtained.

The expression Ipushironshiguma both sides of ^{_{(5) (T 3 4 -T}} 2 4) By ^{_{adding, εσ (T 1 4 -T 2}} 4) = 2εσ (T 3 4 -T 2 4) ... Equation (6) Become.

  From this equation (6) and equations (1), (3), and (4), q ′ = εq / 2 (7) is obtained, which is a heat transfer amount relational expression before and after the infinite flat plate C is inserted. .

  As can be seen from this equation (7), the amount of radiant heat transfer is reduced from q to εq / 2 by inserting a flat plate, and the smaller the emissivity ε of the inserted flat plate C, the higher the heat insulation effect.

  Therefore, the radiant heat transfer suppressing structure 132 is thin (for example, about 0.1 to 2 mm), and even if its thermal conductivity is large, a heat insulating effect can be obtained. As shown in the equation (7), It can be seen that the smaller the emissivity, the more effective.

  The radiant heat transfer suppressing structure 132 needs to be stable with respect to the atmosphere and temperature during single crystal growth. For this reason, it is preferable that the structure 132 is comprised, for example by platinum group single-piece | units, such as platinum or Ir, Rh, or those alloys. Platinum has a low emissivity of 0.2 or less at high temperatures, and is stable with respect to the crystal growth atmosphere and temperature of oxides and the like.

  As described above, the structure 132 is effective even if it is thin. For this reason, examples of the shape of the structure 132 include a cylindrical shape shown in FIG. 3 and a truncated cone shape shown in FIGS. In addition, even when the structure 132 is shielded by the crucible 4 and the structure 132 itself is a conductor, induction heating by the high frequency magnetic field is very small, but a slit 132a is provided as shown in FIG. May be completely suppressed. That is, the current flowing in the circumferential direction of the structure body 132 can be suppressed by the slit 132a. Furthermore, in order to suppress discontinuity in the amount of radiant heat transfer between the portion hidden by the structure 132 and the portion not hidden, an oblique slit 132b as shown in FIG. 6 may be provided at the end of the structure 132. .

  The thickness of the structure 132 is usually about 0.1 to 5 mm, preferably about 0.5 to 2 mm.

  If the structure 132 is a) a ring as shown in FIGS. 3, 5 and 6, for example, its inner diameter is b) a truncated cone as shown in FIGS. 4A and 4B, for example. In the case of the shape, the smaller inner diameter is preferably about 1.2 to 1.5 times the outer diameter of the intended straight body of the single crystal.

  If the difference between the inner diameter of the structure 132 and the outer diameter of the straight body portion of the target single crystal is too small, there may be inconveniences such as cracks occurring in the obtained single crystal.

  In the present embodiment, a high-frequency induction coil 14 as a high-frequency oscillator is wound around the outer periphery of the second refractory structure 10, and the crucible 4 is induction-heated by passing a high-frequency current through the coil 14, and as a result, The melt 42 in the crucible 4 is maintained at a predetermined temperature.

Method for producing a single crystal Next, using the production apparatus 2 of the single crystal mentioned above, a method of manufacturing a single crystal. In this embodiment, a case where an oxide single crystal having the composition formula Ca ₃ Nb _1.7 Ga _3.3 O ₁₂ is manufactured will be described as an example.

First, for example, an oxide or carbonate of an element constituting the composition formula Ca ₃ Nb _1.7 Ga _3.3 O ₁₂ (for example, CaCO ₃ , Nb ₂ O ₅ , Ga ₂ O _3, etc.) is predetermined in a powder form. After being mixed so as to have an atomic ratio of and compressed into a cylindrical shape, the sintered body is obtained by sintering at 1000 to 1400 ° C. in the atmosphere.

  Next, after the obtained sintered body is accommodated in the crucible 4 of the manufacturing apparatus 2 that is kept airtight, the sintered body is melted in a nitrogen atmosphere containing a small amount of oxygen to obtain a melt 42. And

Then, by moving the second moving shaft 13 downward, while the radiant heat transfer suppressing structure 132 attached to its lower end, a single crystal 124 is grown on the inner wall and the lower end of the seed crystal 122 of the crucible 4 And at a position that does not contact the melt 42 in the crucible 4. Specifically, the radiant heat transfer restraining structure 132 is arranged at the above position so that the distance from the liquid surface of the melt 42 in the crucible 4 is preferably about 2 to 8 mm.

  Next, by moving the first moving shaft 12 downward, the seed crystal 122 attached to the lower end thereof is brought into contact with the melt 42 in the crucible 4.

Further, this point will be described with reference to FIG. The data shown in FIG. 7 uses a crucible 4 having a diameter of 100 mm. Example in which structure 132 is not provided The chain line in FIG. 7 is compared with the example in FIG. 7 in which a radiant heat transfer suppressing structure 132 having a height of 10 mm and a diameter of 80 mm (see FIG. 3) is provided. , at the position of + 5 mm to + 15 mm from right above the melt 42, not possible to suppress the radiant heat transfer towards the inner wall or et central portion of the crucible 4 of the crucible 4, a temperature gradient immediately above the result in melt 42 It is getting smaller.

On the other hand, when the structure 132 is provided so that the lower end thereof is positioned at +5 mm from directly above the melt 42, the inside of the crucible 4 is compared with the case where the structure 132 is not provided. and it can suppress the radiant heat transfer towards the central portion of the wall or al crucible 4, as a result, the temperature gradient immediately above the melt 42 is increased.

  Next, by pulling upward while rotating the first moving shaft 12, the melt 42 adhering to the lower end of the seed crystal 122 is crystallized while solidifying to grow a single crystal 124. The growth conditions of the single crystal 124 are not particularly limited, but the crystal rotation speed is usually 1 to 100 rpm, preferably 5 to 50 rpm, and the pulling speed of the seed crystal 122 is usually 0.1 to 10 mm / hr, preferably 0. 5 to 5 mm / hr.

  In the present embodiment, the second moving shaft 13 is moved in conjunction with the growth of the single crystal 124 attached to the lower end of the seed crystal 122. As a result, the radiant heat transfer suppressing structure 132 is moved as the single crystal 124 grows.

  In the present embodiment, the radiant heat transfer suppressing structure 132 is held during crystal growth at a position that effectively acts on the solid-liquid interface (the liquid level of the melt 42). As one of the measures for that purpose, preferably, an operation profile that always keeps the same position from the melt surface in accordance with the lowering speed of the melt 42 can be considered. That is, in this embodiment, the radiant heat transfer suppressing structure 132 can be moved so as to keep the distance from the liquid surface of the melt 42 constant according to the decrease in the liquid surface of the melt 42 being grown. preferable.

Here, when the rate of decrease of the melt 42 is v _l , the weight of the single crystal 124 to be grown is W _c , and dW _c / dt = ρ _m · π · R ² · v _l (8) In the formula (8), the [rho _m the density of the melt 42, R is an inner radius of the crucible 4. As W _c used here, it is conceivable to use a weight actually measured by a weight sensor such as a load cell. However, in order to avoid fluctuations in the speed of the structure 132 caused by a weight measurement error or the like, for example, v _l = v _p · ρ _c · r ² / (ρ _m · R ² −ρ _c · r ² )... The speed calculated by the equation (9) can be used. In equation (9), ρ _c is the density of the single crystal 124, r is the radius of the single crystal 124, and v _p is the pulling speed (the moving speed of the first moving shaft 12).

Further, when the shape of the grown single crystal 124 is a truncated cone having radii r ₁ and r ₂ , v _l = v _p · ρ _c · (r ₁ ² + r ₁ · r ₂ + r ₂ ² ) / { 3 · ρ _m · R ² −ρ _c · (r ₁ ² + r ₁ · r ₂ + r ₂ ² )}...

  By using either of these two formulas, the radiant heat transfer suppressing structure 132 can be moved in accordance with a pre-programmed crystal shape.

  The moving speed of the second moving shaft 13 is, for example, about 0.1 to 6 mm / hr, preferably about 0.2 to 3 mm / hr.

  The single crystal 124 manufactured in this way is long and high quality without cracks or twists. The single crystal 124 is suitable for use as a substrate material for Viscos substituted rare earth iron garnet, for example.

  In the present embodiment, the specific manufacturing apparatus 2 is used to move the radiant heat transfer suppressing structure 132 in conjunction with the growth of the single crystal 124. For this reason, relaxation of the temperature gradient immediately above the melt 42 during crystal growth can be suppressed. As a result, even when the obtained single crystal 124 absorbs infrared and visible light, there is no crack or twist, and a high-quality single crystal 124 that can be elongated is manufactured.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to such embodiment at all, Of course, in the range which does not deviate from the summary of this invention, it can implement in various aspects. .

  Next, the present invention will be described in more detail with reference to examples that further embody the embodiment of the present invention. However, the present invention is not limited to these examples.

Example 1
In this example, the single crystal manufacturing apparatus 2 shown in FIG. 1 was used. A high frequency oscillator having a frequency of 70 kHz was used. As the crucible 4, an Ir crucible having a diameter of 100 mm, a height of 100 mm, and a thickness of 2.5 mm was used. About 2200 g of Ca ₃ Nb _1.7 Ga _3.3 O ₁₂ reaction powder was inserted into the crucible 4.

  Further, as the radiant heat transfer suppressing structure 132, a cylindrical ring made of Ir as shown in FIG. 3 having a height of 20 mm, a thickness of 1 mm, a diameter of 80 mm was used. This ring was fixed by a second moving shaft 13 connected to a power source (not shown).

Then, by moving the second moving shaft 13 downward, while the radiant heat transfer suppressing structure 132 attached to its lower end, a single crystal 124 is grown on the inner wall and the lower end of the seed crystal 122 of the crucible 4 And it is the position which is not in contact with the melt 42 in the crucible 4 and is further arranged so that the distance from the liquid surface of the melt 42 in the crucible 4 is 5 mm.

Using the apparatus 2 configured as described above, a seed crystal 122 composed of a [111] -oriented Ca ₃ Nb _1.7 Ga _3.3 O ₁₂ single crystal in an atmosphere in which 1 vol% O ₂ is mixed in N ₂ The crystal was grown by bringing it into contact with the melt 42 in the crucible 4 and pulling it up at a speed of 0.5 mm / hr. As the crystal grows, the liquid level of the melt 42 decreases, and in conjunction with this crystal growth, the radiant heat transfer suppressing structure 132 is moved downward at a speed that maintains a distance of +5 mm from the liquid level of the melt 42. Moved towards.

As a result, a transparent and crack-free Ca ₃ Nb _1.7 Ga _3.3 O ₁₂ single crystal having a diameter of 56 mmφ and a length of the straight body portion of 100 mm was obtained.

  As a result of pulverizing a part of the crystal and performing phase identification by powder X-ray diffraction, all the diffraction peaks can be indexed as phases having a garnet structure, and other heterogeneous peaks are not recognized at all and are single phase. It could be confirmed. The surface state of the crystal is smooth and glossy, and no adhesion of foreign substances is observed. Macroscopic defects such as bubbles, cracks, torsion, and inclusions were not observed in the crystal, and it was confirmed that the crystal was a uniform single crystal from an orthoscopic image obtained by a polarizing microscope.

  The single crystal obtained in this example has almost the same hardness as quartz and is chemically and physically stable near room temperature. In addition, it was confirmed that the crystal can be cut and polished under the usual processing conditions used for quartz and the like, without problems such as cracks, and the crystal is easy to handle.

Comparative Example 1
Single crystal growth was performed under the same conditions as in Example 1 except that the radiant heat transfer suppressing structure 132 was not used. As a result, twisting of the crystal started from a straight cylinder length of 55 mm, and a crystal having a long straight cylinder part was not obtained. Thereby, the superiority of Example 1 was confirmed.

  In addition, in Comparative Example 1 together with Example 1 above, the presence or absence of the start of twisting of the crystal is twisted when the outer shape of the crystal is photographed by means of a photograph or the like and an outward direction of 2% or more of the crystal diameter is recognized, It was done by judging.

FIG. 1 is a schematic sectional view showing an apparatus for producing a single crystal according to an embodiment of the present invention, FIG. 2 is a sectional view taken along line II-II in FIG. FIG. 3 is a perspective view showing one aspect of the radiant heat transfer suppressing structure used in the present embodiment. FIG. 4A and FIG. 4B are perspective views showing one aspect of the radiant heat transfer suppressing structure used in this embodiment. FIG. 5 is a perspective view showing one aspect of the radiant heat transfer suppressing structure used in the present embodiment. FIG. 6 is a perspective view showing an aspect of the radiant heat transfer suppressing structure used in the present embodiment. FIG. 7 is a graph showing how the radiant heat transfer suppressing structure used in this embodiment affects the temperature gradient.

Explanation of symbols

2 ... Single crystal manufacturing apparatus 4 ... Crucible 42 ... Melt 6 ... Heat insulating material 62 ... Recess 8 ... First refractory structure 82, 84 ... Opening 10 ... Second refractory structure 102, 104 ... Opening 12 ... 1st moving shaft 122 ... Seed crystal 124 ... Single crystal 13 ... 2nd moving shaft 132 ... Radiation heat transfer suppressing structure 132a ... Slit 132b ... Diagonal slit 14 ... High frequency induction coil

Claims (8)

A method for producing a single crystal in which a seed crystal is brought into contact with a melt in a crucible and pulled up, and a single crystal is grown on the lower end of the seed crystal,
Between the growing single crystal at the lower end of the seed crystal and the inner wall of the crucible, and a position not in contact with the melt in the crucible, suppress radiant heat transfer suppressing structure movement release Inetsu is movable The temperature gradient of the single crystal immediately above the melt is moved while the radiant heat transfer suppressing structure is moved in conjunction with the growth of the single crystal adhering to the lower end of the seed crystal. A method for producing a single crystal , comprising producing the single crystal so as to be larger than a case where there is no movement suppressing structure .   2. The method for producing a single crystal according to claim 1, wherein the single crystal is produced while moving the radiant heat transfer suppressing structure so as to maintain a constant distance from the melt surface. 3.   The method for producing a single crystal according to claim 2, wherein the distance to be held between the melt and the liquid surface is 2 to 8 mm.   The manufacturing method of the single crystal in any one of Claims 1-3 with which the structure which suppresses the movement of the said radiant heat is comprised with the platinum group metal single-piece | unit or its alloy.   The manufacturing method of the single crystal in any one of Claims 1-4 using the melt heated by the high frequency induction heating.   The method for producing a single crystal according to claim 1, wherein the melt and the single crystal are oxides.   The method for producing a single crystal according to claim 1, wherein the radiant heat transfer suppressing structure has a height of 10 to 20 mm. An apparatus for producing a single crystal in which a seed crystal is brought into contact with the melt in the crucible and pulled up, and a single crystal is grown on the lower end of the seed crystal,
A first movement axis for pulling up the seed crystal;
A radiation heat transfer suppressing structure which kicked set in, and a position not in contact with the melt in the crucible between the growing single crystal at the lower end of the seed crystal and the inner wall of the crucible,
And a second moving axis to move to the radiant heat transfer suppressing structure in conjunction with the growth of the single crystal to be attached to the lower end of the seed crystal, possess,
The radiant heat transfer suppressing structure is a single crystal manufacturing apparatus provided to increase the temperature gradient of the single crystal directly above the melt as compared to the case where the radiant heat transfer suppressing structure is not provided .

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