JP2021059465A - Monocrystal growth apparatus - Google Patents

Monocrystal growth apparatus Download PDF

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JP2021059465A
JP2021059465A JP2019183449A JP2019183449A JP2021059465A JP 2021059465 A JP2021059465 A JP 2021059465A JP 2019183449 A JP2019183449 A JP 2019183449A JP 2019183449 A JP2019183449 A JP 2019183449A JP 2021059465 A JP2021059465 A JP 2021059465A
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single crystal
crucible
heat insulating
refractory container
crystal growing
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JP7308715B2 (en
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阿部　淳
Atsushi Abe
淳 阿部
隼 森山
Hayato Moriyama
隼 森山
由則 桑原
Yoshinori Kuwabara
由則 桑原
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Shin Etsu Chemical Co Ltd
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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
    • C30B15/00—Single-crystal growth by pulling from a melt, e.g. Czochralski method

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Abstract

To provide a monocrystal growth apparatus that can reduce the temperature gradient of monocrystals and prevents a sudden deterioration in the yield of monocrystals due to the mixing of impurities.SOLUTION: A monocrystal growth apparatus 90 grows monocrystals 13 from melt 12 of raw material in a crucible 1 by a pulling-up method and has: an upper refractory container 10b that covers space 16 above the crucible 1; a thermal insulating structure 14 that covers the periphery of the upper refractory container 10b; and an insulating ceramic material 15 that covers the periphery of the thermal insulating structure 14.SELECTED DRAWING: Figure 1

Description

本発明は、引き上げ法によって単結晶を育成する単結晶育成装置に関する。 The present invention relates to a single crystal growing device for growing a single crystal by a pulling method.

引き上げ法はチョクラルスキー法とも呼ばれ、原料をるつぼ内で加熱融解して融液の状態にした後、種子結晶を融液に接触させ、回転しながら引き上げることによって単結晶を育成する方法である。
この方法は、単結晶がるつぼと接触せず、るつぼによる機械的歪が発生しないので、高品質で大口径の結晶を作製しやすいという利点がある。
このため、半導体シリコン（Ｓｉ）、化合物半導体のヒ化ガリウム（ＧａＡｓ）、リン化ガリウム（ＧａＰ）、リン化インジウム（ＩｎＰ）、酸化物結晶のイットリウム・アルミニウム・ガーネット（Ｙ３Ａｌ５Ｏ１２；ＹＡＧ）、サファイア（Ａｌ２Ｏ３）、ニオブ酸リチウム（ＬｉＮｂＯ３；ＬＮ）、タンタル酸リチウム（ＬｉＴａＯ３；ＬＴ）、ゲルマニウム酸ビスマス（Ｂｉ４Ｇｅ３Ｏ１２；ＢＧＯ）等、種々の結晶がこの方法により製造されている。
これらの中で、ニオブ酸リチウム（ＬＮ）及びタンタル酸リチウム（ＬＴ）は、電子デバイス用や光デバイス用として重要な単結晶材料であり、特に、弾性表面波（Ｓｕｒｆａｃｅ Ａｃｏｕｓｔｉｃ Ｗａｖｅ；ＳＡＷ）デバイスに広く使用されている。
特許文献１には引上げ法によるタンタル酸リチウム単結晶の製造方法が記載されている。特許文献１に記載の単結晶引き上げ装置は、原料を入れ該原料を融解した融液を保持するるつぼ、原料を加熱するための加熱装置を構成するワークコイル、種子結晶が取り付けられる保持棒を含む引き上げ機構等から構成される。単結晶引き上げ装置は、育成する単結晶の種類に応じて設計されている。
単結晶の引き上げ装置の加熱装置として、結晶育成温度が約１２００℃未満の場合には、抵抗加熱ヒータが用いられるが、１２００℃以上では通常、高周波誘導加熱が用いられる。この場合、ワークコイル内部に、白金（Ｐｔ）やイリジウム（Ｉｒ）等の貴金属製のるつぼが置かれ、るつぼ自体が発熱体となる。ニオブ酸リチウム（ＬＮ）及びタンタル酸リチウム（ＬＴ）の結晶育成においても、通常、この高周波誘導加熱が用いられる。
また、単結晶の引き上げ装置では、一般的に結晶重量の変化を測り、ヒータ出力又は高周波出力にフィードバックをかけて単結晶の直径制御が行われている。 The pulling method is also called the Czochralski method, which is a method of growing a single crystal by heating and melting the raw material in a crucible to make it into a melt, then bringing the seed crystal into contact with the melt and pulling it while rotating. is there.
This method has an advantage that high quality and large diameter crystals can be easily produced because the single crystal does not come into contact with the crucible and mechanical strain due to the crucible does not occur.
For this reason, semiconductor silicon (Si), compound semiconductor gallium arsenide (GaAs), gallium phosphide (GaP), indium phosphide (InP), and oxide crystals of lithium aluminum garnet (Y 3 Al 5 O 12 ; Various crystals such as YAG), sapphire (Al 2 O 3 ), lithium niobate (LiNbO 3 ; LN), lithium tantalate (LiTaO 3 ; LT), bismuth germanium (Bi 4 Ge 3 O 12 ; BGO), etc. It is manufactured by this method.
Among these, lithium niobate (LN) and lithium tantalate (LT) are important single crystal materials for electronic devices and optical devices, and are particularly suitable for surface acoustic wave (SAW) devices. Widely used.
Patent Document 1 describes a method for producing a lithium tantalate single crystal by a pulling method. The single crystal pulling device described in Patent Document 1 includes a crucible for holding a melt in which a raw material is put and melted, a work coil constituting a heating device for heating the raw material, and a holding rod to which a seed crystal is attached. It consists of a pulling mechanism and the like. The single crystal pulling device is designed according to the type of single crystal to be grown.
As a heating device for the single crystal pulling device, a resistance heating heater is used when the crystal growth temperature is less than about 1200 ° C., but high frequency induction heating is usually used when the crystal growth temperature is 1200 ° C. or higher. In this case, a crucible made of a precious metal such as platinum (Pt) or iridium (Ir) is placed inside the work coil, and the crucible itself becomes a heating element. This high frequency induction heating is also usually used in the crystal growth of lithium niobate (LN) and lithium tantalate (LT).
Further, in a single crystal pulling device, a change in crystal weight is generally measured, and feedback is applied to a heater output or a high frequency output to control the diameter of the single crystal.

特開２０１２−２５０８７４号公報Japanese Unexamined Patent Publication No. 2012-250874

単結晶を育成する際、急峻な温度勾配下では単結晶に歪みが発生するおそれがある。このため、るつぼの上方で、育成した単結晶の温度勾配を低減する必要がある。例えば、単結晶の温度勾配を低減する方法として、るつぼや保持棒等を収容する耐火物容器の上側の外周を断熱材で覆う方法が挙げられる。るつぼの上方は保温されるので、るつぼの上方で育成した単結晶の温度勾配を低減することができる。さらに、断熱材は耐火物容器の外側に存在するので、断熱材からるつぼの中へ不純物が直接入り込むことも防止できる。
しかしながら、このようにるつぼの上方を保温した状態で、ニオブ酸リチウム（ＬＮ）及びタンタル酸リチウム（ＬＴ）のような単結晶を引き上げ法により育成する場合に、不純物混入により歩留りが急激に悪化傾向になることがある。
本発明は、上記事情に鑑みなされたもので、単結晶の温度勾配を低減できるとともに不純物混入による単結晶の歩留りの急激悪化を防ぐ単結晶育成装置を提供することを目的とする。 When growing a single crystal, the single crystal may be distorted under a steep temperature gradient. Therefore, it is necessary to reduce the temperature gradient of the grown single crystal above the crucible. For example, as a method of reducing the temperature gradient of a single crystal, there is a method of covering the upper outer circumference of a refractory container for accommodating a pot, a holding rod, or the like with a heat insulating material. Since the upper part of the crucible is kept warm, the temperature gradient of the single crystal grown above the crucible can be reduced. Further, since the heat insulating material exists on the outside of the refractory container, it is possible to prevent impurities from directly entering the crucible from the heat insulating material.
However, when single crystals such as lithium niobate (LN) and lithium tantalate (LT) are grown by the pulling method while keeping the temperature above the crucible in this way, the yield tends to deteriorate sharply due to the inclusion of impurities. May become.
The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a single crystal growing apparatus capable of reducing the temperature gradient of a single crystal and preventing a rapid deterioration of the yield of the single crystal due to the inclusion of impurities.

単結晶の不純物混入源は、原料、るつぼ、耐火物容器、セラミック繊維断熱材等の単結晶育成系を取り巻くすべてのモノが原因になる可能性がある。当初は、外周を断熱材で覆われたことに関連して、何らかの原因で耐火物容器が単結晶の不純物混入源になったと考えていた。そして、るつぼは耐火物容器に囲まれているので、断熱材は、単結晶の主な不純物混入源とはなり得ないと考えていた。しかしながら、本発明者らは、鋭意検討の結果、断熱材が、単結晶の主な不純物混入源であることを見出した。そして、本発明者らは、このような不純物の混入を抑制するために、さらに鋭意検討した結果、本発明に至った。すなわち、
［１］引き上げ法によってるつぼ内の原料の融液から単結晶を育成する単結晶育成装置において、るつぼの上方の空間を覆う上部耐火物容器と、上部耐火物容器の外周を覆う断熱保温構造と、断熱保温構造の外周を覆う絶縁性セラミック材料とを備える単結晶育成装置。
［２］るつぼ内の原料は、るつぼの外周を囲む加熱コイルを使用した高周波誘導加熱方式で加熱されて融液となり、絶縁性セラミック材料は円筒形状であり、絶縁性セラミック材料の外径は加熱コイルの内径よりも小さい上記［１］に記載の単結晶育成装置。
［３］単結晶が、タンタル酸リチウムの単結晶またはニオブ酸リチウムの単結晶である上記［１］または［２］に記載の単結晶育成装置。 The source of impurities in the single crystal may be caused by everything surrounding the single crystal growth system, such as raw materials, crucibles, refractory containers, and ceramic fiber insulation. Initially, it was thought that the refractory container became a source of impurities in the single crystal for some reason in connection with the fact that the outer circumference was covered with heat insulating material. And since the crucible is surrounded by a refractory container, I thought that the heat insulating material could not be the main source of impurities in the single crystal. However, as a result of diligent studies, the present inventors have found that the heat insulating material is the main source of impurities mixed in the single crystal. Then, the present inventors have reached the present invention as a result of further diligent studies in order to suppress the mixing of such impurities. That is,
[1] In a single crystal growing device for growing a single crystal from a melt of a raw material in a crucible by a pulling method, an upper refractory container covering the space above the crucible and a heat insulating and heat insulating structure covering the outer periphery of the upper refractory container. , A single crystal growing device including an insulating ceramic material that covers the outer periphery of a heat insulating and heat insulating structure.
[2] The raw material in the crucible is heated by a high-frequency induction heating method using a heating coil surrounding the outer circumference of the crucible to form a melt. The insulating ceramic material has a cylindrical shape, and the outer diameter of the insulating ceramic material is heated. The single crystal growing device according to the above [1], which is smaller than the inner diameter of the coil.
[3] The single crystal growing apparatus according to the above [1] or [2], wherein the single crystal is a single crystal of lithium tantalate or a single crystal of lithium niobate.

本発明によれば、単結晶の温度勾配を低減できるとともに不純物混入による単結晶の歩留りの急激悪化を防ぐ単結晶育成装置を提供することができる。 According to the present invention, it is possible to provide a single crystal growing apparatus capable of reducing the temperature gradient of a single crystal and preventing a rapid deterioration of the yield of the single crystal due to the inclusion of impurities.

図１は、本発明の一実施形態の単結晶育成装置を示す模式図である。FIG. 1 is a schematic view showing a single crystal growing apparatus according to an embodiment of the present invention. 図２は、従来の単結晶育成装置の一例を示す模式図である。FIG. 2 is a schematic view showing an example of a conventional single crystal growing apparatus.

［単結晶育成装置］
図１を参照して、本発明の一実施形態の単結晶育成装置を説明する。図１は、本発明の一実施形態の単結晶育成装置を示す模式図である。本発明の一実施形態の単結晶育成装置９０は、引き上げ法によってるつぼ１内の原料の融液１２から単結晶１３を育成する単結晶育成装置９０において、るつぼ１の上方の空間１６を覆う上部耐火物容器１０ｂと、上部耐火物容器１０ｂの外周を覆う断熱保温構造１４と、断熱保温構造１４の外周を覆う絶縁性セラミック材料１５とを備える。これにより、単結晶の温度勾配を低減できるとともに不純物混入による単結晶の歩留りの急激悪化を防ぐことができる。 [Single crystal growing device]
A single crystal growing apparatus according to an embodiment of the present invention will be described with reference to FIG. FIG. 1 is a schematic view showing a single crystal growing apparatus according to an embodiment of the present invention. The single crystal growing device 90 according to the embodiment of the present invention is an upper portion covering the space 16 above the crucible 1 in the single crystal growing device 90 that grows the single crystal 13 from the melt 12 of the raw material in the crucible 1 by the pulling method. It includes a refractory container 10b, a heat insulating and heat insulating structure 14 that covers the outer periphery of the upper refractory container 10b, and an insulating ceramic material 15 that covers the outer periphery of the heat insulating and heat insulating structure 14. As a result, the temperature gradient of the single crystal can be reduced, and the yield of the single crystal can be prevented from rapidly deteriorating due to the inclusion of impurities.

本発明の一実施形態の単結晶育成装置９０の上記構成により、不純物混入による単結晶の歩留りの急激悪化を防ぐことができるのは、以下の理由によるものと考えられる。しかし、以下説明する理由は本発明を限定しない。
耐火物容器の外周を断熱保温構造で覆っており、断熱保温構造の外周を覆っていない単結晶育成装置では、結晶育成中、ルツボと加熱コイルが相対的に移動すると、加熱コイルと断熱保温構造はクリアランスがないと擦れてしまう。そのため、断熱保温構造は、単結晶の育成を複数回行っている間に毛羽立ち、塵が発生したと考えられる。そして、その塵は、耐火物容器の隙間を通って、るつぼの中へ侵入し、単結晶に不純物として混入したものと考えられる。しかし、本発明の一実施形態の単結晶育成装置９０では、絶縁性セラミック材料１５が断熱保温構造１４の外周を覆っているので、断熱保温構造１４からの塵の発生を抑制することができる。その結果、単結晶への不純物混入が抑制されたと考えられる。 It is considered that the above-mentioned configuration of the single crystal growing apparatus 90 according to the embodiment of the present invention can prevent the rapid deterioration of the yield of the single crystal due to the mixing of impurities for the following reasons. However, the reasons described below do not limit the present invention.
In a single crystal growing device in which the outer circumference of the refractory container is covered with a heat insulating and heat insulating structure and the outer circumference of the heat insulating and heat insulating structure is not covered, when the crucible and the heating coil move relatively during crystal growth, the heating coil and the heat insulating and heat insulating structure are formed. Will rub if there is no clearance. Therefore, it is considered that the heat insulating and heat insulating structure was fluffed and dust was generated during the growth of the single crystal a plurality of times. Then, it is considered that the dust entered the crucible through the gap of the refractory container and was mixed as an impurity in the single crystal. However, in the single crystal growing apparatus 90 of the embodiment of the present invention, since the insulating ceramic material 15 covers the outer periphery of the heat insulating and heat insulating structure 14, it is possible to suppress the generation of dust from the heat insulating and heat insulating structure 14. As a result, it is considered that the mixing of impurities into the single crystal was suppressed.

本発明の一実施形態の単結晶育成装置９０により育成する単結晶１３には、例えば、半導体シリコン（Ｓｉ）、化合物半導体のヒ化ガリウム（ＧａＡｓ）、リン化ガリウム（ＧａＰ）、リン化インジウム（ＩｎＰ）、酸化物結晶のイットリウム・アルミニウム・ガーネット（Ｙ３Ａｌ５Ｏ１２；ＹＡＧ）、サファイア（Ａｌ２Ｏ３）、ニオブ酸リチウム（ＬｉＮｂＯ３；ＬＮ）、タンタル酸リチウム（ＬｉＴａＯ３；ＬＴ）、ゲルマニウム酸ビスマス（Ｂｉ４Ｇｅ３Ｏ１２；ＢＧＯ）等が挙げられる。これらの中で、酸化物単結晶の育成に本発明の一実施形態の単結晶育成装置９０は好適であり、断熱保温構造を劣化させて塵の発生を促進するアルカリ金属化合物の蒸気が発生するおそれのあるタンタル酸リチウムの単結晶及びニオブ酸リチウムの単結晶の育成に本発明の一実施形態の単結晶育成装置９０は特に好適である。 The single crystal 13 grown by the single crystal growing apparatus 90 according to the embodiment of the present invention includes, for example, semiconductor silicon (Si), gallium arsenide (GaAs) of compound semiconductor, gallium arsenide (GaP), and indium phosphide ( InP), yttrium aluminum garnet of oxide crystals (Y 3 Al 5 O 12 ; YAG), sapphire (Al 2 O 3 ), lithium niobate (LiNbO 3 ; LN), lithium tantalate (LiTaO 3 ; LT) , Bismus germaniumate (Bi 4 Ge 3 O 12 ; BGO) and the like. Among these, the single crystal growing device 90 of the embodiment of the present invention is suitable for growing an oxide single crystal, and vapor of an alkali metal compound that deteriorates the heat insulating and heat insulating structure and promotes the generation of dust is generated. The single crystal growing apparatus 90 of the embodiment of the present invention is particularly suitable for growing a single crystal of lithium tantalate and a single crystal of lithium niobate, which may occur.

上部耐火物容器１０ｂは、耐食性に優れ、耐熱性及び耐衝撃性に優れ、機械的強度が大きなものであれば、特に限定されない。上部耐火物容器１０ｂには、例えば、アルミナ質磁器、ジルコニア質磁器、ジルコン質磁器、コーディエライト質磁器、シリカ質磁器、ムライト式磁器等が挙げられる。上部耐火物容器１０ｂの形状は、例えば、円筒形状である。上部耐火物容器１０ｂは、るつぼ１の上方の空間１６を覆うことにより、るつぼ１の中への不純物の侵入を抑制する。また、上部耐火物容器１０ｂは、るつぼ１の上方の空間１６を覆うことにより、るつぼ１の上方の温度勾配を低減することができる。その結果、単結晶の温度勾配を低減できる。 The upper refractory container 10b is not particularly limited as long as it is excellent in corrosion resistance, heat resistance and impact resistance, and has high mechanical strength. Examples of the upper refractory container 10b include alumina porcelain, zirconia porcelain, zircon porcelain, cordierite porcelain, silica porcelain, and mullite porcelain. The shape of the upper refractory container 10b is, for example, a cylindrical shape. The upper refractory container 10b covers the space 16 above the crucible 1 to suppress the invasion of impurities into the crucible 1. Further, the upper refractory container 10b can reduce the temperature gradient above the crucible 1 by covering the space 16 above the crucible 1. As a result, the temperature gradient of the single crystal can be reduced.

断熱保温構造１４は、好ましくは、熱的及び化学的に安定なセラミックスの繊維から構成されるセラミック繊維断熱材である。セラミック繊維断熱材には、例えば、アルミナ繊維断熱材、シリカ繊維断熱材、アルミナ−シリカ繊維断熱材等が挙げられる。耐熱性の観点から、アルミナ繊維断熱材が好ましい。セラミック繊維断熱材は、多くの空気を含有することができるので、高い断熱性能を有する。 The heat insulating and heat insulating structure 14 is preferably a ceramic fiber heat insulating material composed of thermally and chemically stable ceramic fibers. Examples of the ceramic fiber heat insulating material include an alumina fiber heat insulating material, a silica fiber heat insulating material, and an alumina-silica fiber heat insulating material. From the viewpoint of heat resistance, an alumina fiber heat insulating material is preferable. Since the ceramic fiber heat insulating material can contain a large amount of air, it has high heat insulating performance.

絶縁性セラミック材料１５は、板厚を薄くでき（例えば、板厚が５ｍｍ以下）、絶縁性を有するセラミック材料であれば、特に限定されない。絶縁性セラミック材料１５には、例えば、石英ガラス、緻密質アルミナ等が挙げられる。これらの中で、好ましい絶縁性セラミック材料１５は石英ガラスである。石英ガラスは、実質的にＳｉＯ２からなるガラスであり、耐熱性及び耐化学性に優れている。石英ガラスは、例えば、溶融法、バイコール法、ＣＶＤ（Ｃｈｅｍｉｃａｌ Ｖａｐｏｒ Ｄｅｐｏｓｉｔｉｏｎ）法、ＶＡＤ（Ｖａｐｏｒ−ｐｈａｓｅ Ａｘｉａｌ Ｄｅｐｏｓｉｔｉｏｎ）法、ゾルゲル法等で製造することができる。 The insulating ceramic material 15 is not particularly limited as long as it can be made thin (for example, the plate thickness is 5 mm or less) and has insulating properties. Examples of the insulating ceramic material 15 include quartz glass and dense alumina. Among these, the preferred insulating ceramic material 15 is quartz glass. Quartz glass is a glass substantially composed of SiO 2 , and is excellent in heat resistance and chemical resistance. Quartz glass can be produced by, for example, a melting method, a bicol method, a CVD (Chemical Vapor Deposition) method, a VAD (Vapor-phase Axial Deposition) method, a sol-gel method, or the like.

本発明の一実施形態の単結晶育成装置９０では、るつぼ１内の原料は、るつぼの外周を囲む加熱コイル２を使用した高周波誘導加熱方式で加熱されて融液となることが好ましい。また、絶縁性セラミック材料１５は円筒形状であり、絶縁性セラミック材料１５の外径は加熱コイル２の内径よりも小さいことが好ましい。これにより、るつぼ１の上方に貴金属製のアフターヒータ７を設けた場合、加熱コイル２を用いた誘導加熱によりアフターヒータ７を加熱することができる。そして、アフターヒータ７から発生した熱を断熱保温構造１４によって保温できるとともに、絶縁性セラミック材料１５により、断熱保温構造１４からの塵の発生を抑制することができる。なお、アフターヒータ７により、るつぼ１の上方の温度勾配をさらに低減することができる。 In the single crystal growing apparatus 90 of the embodiment of the present invention, it is preferable that the raw material in the crucible 1 is heated by a high frequency induction heating method using a heating coil 2 surrounding the outer circumference of the crucible to become a melt. Further, it is preferable that the insulating ceramic material 15 has a cylindrical shape, and the outer diameter of the insulating ceramic material 15 is smaller than the inner diameter of the heating coil 2. As a result, when the afterheater 7 made of precious metal is provided above the crucible 1, the afterheater 7 can be heated by induction heating using the heating coil 2. The heat generated from the afterheater 7 can be retained by the heat insulating and heat insulating structure 14, and the insulating ceramic material 15 can suppress the generation of dust from the heat insulating and heat insulating structure 14. The after-heater 7 can further reduce the temperature gradient above the crucible 1.

本発明の一実施形態の単結晶育成装置９０は、さらに以下の構成を有してもよい。
本発明の一実施形態の単結晶育成装置９０は、供給された原料を融解した融液１２を保持するるつぼ１と、るつぼ１の周囲に設けられる保温構造（るつぼ台５、保温材６）と、保温材６を囲むように加熱コイル２を配置して、るつぼ１を誘導加熱する不図示の高周波誘導加熱装置と、種子結晶１１を保持する保持棒３とを備えてもよい。そして、本発明の一実施形態の単結晶育成装置９０は、種子結晶１１を用いて育成する単結晶１３の不図示の引き上げ機構と、上記加熱装置の出力を調整してるつぼ１内の原料を融解して融液１２とするとともに、育成する単結晶１３の直径を制御する不図示の出力制御部とをさらに備えてもよい。 The single crystal growing device 90 according to the embodiment of the present invention may further have the following configuration.
The single crystal growing device 90 according to the embodiment of the present invention includes a crucible 1 that holds a melt 12 in which the supplied raw materials are melted, and a heat insulating structure (crucible stand 5, heat insulating material 6) provided around the crucible 1. A high-frequency induction heating device (not shown) that induces and heats the crucible 1 by arranging the heating coil 2 so as to surround the heat insulating material 6 and a holding rod 3 that holds the seed crystal 11 may be provided. Then, the single crystal growing device 90 of the embodiment of the present invention uses a pulling mechanism (not shown) of the single crystal 13 grown using the seed crystal 11 and a raw material in the crucible 1 for adjusting the output of the heating device. In addition to melting to form the melt 12, an output control unit (not shown) that controls the diameter of the single crystal 13 to be grown may be further provided.

ここで、原料を融解した融液１２を保持するるつぼ１は白金（Ｐｔ）、イリジウム（Ｉｒ）等の貴金属製である。保温構造を構成する保温材を兼ねたるつぼ台５の上に、るつぼ底１ｂがるつぼ台５に接するように、るつぼ１は設置される。また、るつぼ外周面１ａには保温構造を構成する保温材６が設けられる。るつぼ台５及び保温材６としてはジルコニア、アルミナ等の耐熱材料が用いられる。るつぼ台５の内部にジルコニア、アルミナ等の耐熱材料の保温材が充填されている。るつぼ底１ｂの中央には熱電対４が設けられている。るつぼ底１ｂの温度変化は、この熱電対４によって測定することができる。 Here, the crucible 1 that holds the melt 12 in which the raw material is melted is made of a precious metal such as platinum (Pt) or iridium (Ir). The crucible 1 is installed on the crucible stand 5 which also serves as a heat insulating material constituting the heat insulating structure so that the crucible bottom 1b is in contact with the crucible stand 5. Further, a heat insulating material 6 constituting a heat insulating structure is provided on the outer peripheral surface 1a of the crucible. Heat-resistant materials such as zirconia and alumina are used as the crucible stand 5 and the heat insulating material 6. The inside of the crucible stand 5 is filled with a heat insulating material such as zirconia or alumina. A thermocouple 4 is provided in the center of the crucible bottom 1b. The temperature change of the crucible bottom 1b can be measured by this thermocouple 4.

さらに、本発明の一実施形態の単結晶育成装置９０は、るつぼ１の上部にドーナツ型円盤状の熱反射板であるリフレクター８、リフレクター８の上部に円筒状の熱反射板であるアフターヒータ７、及びアフターヒータ７の蓋であるアフターヒータ蓋９を備えてもよい。 Further, the single crystal growing device 90 according to the embodiment of the present invention has a reflector 8 which is a donut-shaped disk-shaped heat reflector on the upper part of the crucible 1, and an afterheater 7 which is a cylindrical heat reflector on the upper part of the reflector 8. , And the afterheater lid 9 which is the lid of the afterheater 7 may be provided.

上記るつぼ１、融液１２、るつぼ台５、保温材６、リフレクター８、アフターヒータ７、及びアフターヒータ蓋９は、石英やアルミナ等からなる下部耐火物容器１０ａ又は上部耐火物容器１０ｂ内に設置されてもよい。例えば、下部耐火物容器１０ａは、るつぼ１、るつぼ台５、及び保温材６を収容する円筒状の耐火物容器であってもよい。また、上部耐火物容器１０ｂは、リフレクター８、アフターヒータ７、アフターヒータ蓋９を収容する耐火物容器であってもよい。上部耐火物容器１０ｂの外周をアルミナ製ブランケット等の断熱保温構造１４で覆うことにより、さらに断熱性をアップさせる工夫がされてもよい。なお、下部耐火物容器１０ａ及び上部耐火物容器１０ｂを一つの耐火物容器で構成してもよい。 The crucible 1, the melt 12, the crucible stand 5, the heat insulating material 6, the reflector 8, the afterheater 7, and the afterheater lid 9 are installed in the lower refractory container 10a or the upper refractory container 10b made of quartz, alumina, or the like. May be done. For example, the lower refractory container 10a may be a cylindrical refractory container that houses the crucible 1, the crucible stand 5, and the heat insulating material 6. Further, the upper refractory container 10b may be a refractory container accommodating the reflector 8, the afterheater 7, and the afterheater lid 9. By covering the outer periphery of the upper refractory container 10b with a heat insulating and heat insulating structure 14 such as an alumina blanket, a device may be devised to further improve the heat insulating property. The lower refractory container 10a and the upper refractory container 10b may be composed of one refractory container.

断熱保温構造１４の周囲は絶縁性セラミック材料１５で覆われている。また、本発明の一実施形態の単結晶育成装置９０は、耐火物容器１０ａ，１０ｂの周囲に設けられた加熱コイル２及び出力制御部を有する不図示の高周波誘導加熱装置を備えてもよい。この加熱装置の高周波誘導加熱によりるつぼ１を誘導加熱し、るつぼ１内の原料を融解して融液１２を調製可能となる。 The periphery of the heat insulating and heat insulating structure 14 is covered with the insulating ceramic material 15. Further, the single crystal growing device 90 according to the embodiment of the present invention may include a high frequency induction heating device (not shown) having a heating coil 2 and an output control unit provided around the refractory containers 10a and 10b. The crucible 1 is induced and heated by the high frequency induction heating of this heating device, and the raw material in the crucible 1 is melted to prepare the melt 12.

リフレクター８及びアフターヒータ蓋９の中央に設けられた開口部を通して保持棒３に取り付けられた種子結晶１１がるつぼ１内に挿入される。種子結晶１１は、融液１２に浸漬した後、所定の回転数及び引き上げ速度で引き上げられるようになっている。 The seed crystal 11 attached to the holding rod 3 is inserted into the crucible 1 through the opening provided in the center of the reflector 8 and the afterheater lid 9. The seed crystal 11 is soaked in the melt 12 and then pulled up at a predetermined rotation speed and pulling speed.

加熱装置の出力は出力制御部により調整され、結晶育成中に随時変動するものである。加熱装置の出力を変動させることによって、単結晶１３の直径を制御して肩部１３ａや直胴部１３ｂを形成する。このとき、引き上げ機構は単結晶１３の重量の変化を測り、出力制御部にフィードバックし、出力制御部はその結果を受けて高周波出力を調整して単結晶１３の直径制御が行われる。 The output of the heating device is adjusted by the output control unit and fluctuates at any time during crystal growth. By varying the output of the heating device, the diameter of the single crystal 13 is controlled to form the shoulder portion 13a and the straight body portion 13b. At this time, the pulling mechanism measures the change in the weight of the single crystal 13 and feeds it back to the output control unit, and the output control unit adjusts the high frequency output in response to the result to control the diameter of the single crystal 13.

本発明の一実施形態の単結晶育成装置９０では、絶縁性セラミック材料１５により断熱保温構造１４からの発塵を抑制し、るつぼ内への塵の混入を防げ、不純物混入による歩留りの急激悪化を抑制できる。また、絶縁性セラミック材料１５により引上雰囲気のＬｉ２Ｏ蒸気下による高温アルカリ雰囲気に直接断熱保温構造１４が晒されることがなくなり、また、断熱保温構造１４が加熱コイル２と接触したり、断熱保温構造１４のセット時のハンドリングで作業者が断熱保温構造１４に接触することがなくなったりするため、断熱保温構造１４の断熱性能の劣化を防止することができる。これにより、断熱保温構造１４の交換の頻度を低減することができる。 In the single crystal growing apparatus 90 of the embodiment of the present invention, the insulating ceramic material 15 suppresses dust generation from the heat insulating and heat insulating structure 14, prevents dust from being mixed into the crucible, and rapidly deteriorates the yield due to the mixing of impurities. Can be suppressed. Further, the insulating ceramic material 15 prevents the heat insulating and heat insulating structure 14 from being directly exposed to the high temperature alkaline atmosphere under the Li 2 O steam in the pulling atmosphere, and the heat insulating and heat insulating structure 14 comes into contact with the heating coil 2 and insulates. Since the operator does not come into contact with the heat insulating structure 14 during the handling when the heat insulating structure 14 is set, deterioration of the heat insulating performance of the heat insulating structure 14 can be prevented. Thereby, the frequency of replacement of the heat insulating and heat insulating structure 14 can be reduced.

以上の説明はあくまで一例であり、本発明の単結晶育成装置は、上記の実施形態に何ら限定されるものではない。 The above description is merely an example, and the single crystal growing apparatus of the present invention is not limited to the above embodiment.

以下に実施例及び比較例を挙げて、本発明をさらに具体的に説明するが、本発明はこれら実施例に限定されるものではない。 Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples.

［実施例１］
図１に示す単結晶育成装置９０のような単結晶育成装置を用いて実施例１のタンタル酸リチウム単結晶を作製した。
ここで、加熱コイル２の直径（内径）は２８０ｍｍであり、加熱コイル２の高さは２８０ｍｍであった。また、るつぼ１はイリジウム製るつぼであり、るつぼ１の外径は１５０ｍｍであり、高さは１５０ｍｍであり、外周部肉厚は２ｍｍであり、底部肉厚は２ｍｍであった。さらに、リフレクター８には、外径１６０ｍｍ、内径１２０ｍｍ、厚さ２ｍｍのイリジウム製のドーナツ板状のものを用いた。リフレクター８の上方に設置したアフターヒータ７には、外径１５０ｍｍ、高さ１８０ｍｍのイリジウム製の円筒状のものを用いた。
るつぼ１の外周面側には、るつぼ１の外周面と下部耐火物容器１０ａとの間に、保温材６としてジルコニア製中空バブル（中空粒子）を充填した。また、るつぼ台５の内部にもジルコニア製中空バブル（中空粒子）を詰め込んだ。
加熱コイル２よりも上側の上部耐火物容器１０ｂには断熱性能を良くする目的でアルミナ製ブランケット１４を巻き付け、その外側に石英ガラス製カバー１５を取り付けた。そして、これらを取り付けた上部耐火物容器１０ｂを下部耐火物容器１０ａ上に配置した。 [Example 1]
The lithium tantalate single crystal of Example 1 was prepared using a single crystal growth apparatus such as the single crystal growth apparatus 90 shown in FIG.
Here, the diameter (inner diameter) of the heating coil 2 was 280 mm, and the height of the heating coil 2 was 280 mm. Further, the crucible 1 was an iridium crucible, and the outer diameter of the crucible 1 was 150 mm, the height was 150 mm, the outer peripheral wall thickness was 2 mm, and the bottom wall thickness was 2 mm. Further, as the reflector 8, an iridium donut plate having an outer diameter of 160 mm, an inner diameter of 120 mm, and a thickness of 2 mm was used. As the afterheater 7 installed above the reflector 8, a cylindrical iridium having an outer diameter of 150 mm and a height of 180 mm was used.
The outer peripheral surface side of the crucible 1 was filled with zirconia-made hollow bubbles (hollow particles) as a heat insulating material 6 between the outer peripheral surface of the crucible 1 and the lower refractory container 10a. Further, hollow bubbles (hollow particles) made of zirconia were also packed inside the crucible stand 5.
An alumina blanket 14 was wound around the upper refractory container 10b above the heating coil 2 for the purpose of improving heat insulation performance, and a quartz glass cover 15 was attached to the outside thereof. Then, the upper refractory container 10b to which these were attached was arranged on the lower refractory container 10a.

［比較例１］
図２に示す単結晶育成装置９０Ａのような単結晶育成装置を用いて比較例１のタンタル酸リチウム単結晶を作製した。
比較例１のタンタル酸リチウム単結晶の作製に用いた単結晶育成装置は、石英ガラス製カバーを取り付けなかった以外は、実施例１のタンタル酸リチウム単結晶の作製に用いた単結晶育成装置と実質的に同一であった。 [Comparative Example 1]
A lithium tantalate single crystal of Comparative Example 1 was prepared using a single crystal growing device such as the single crystal growing device 90A shown in FIG.
The single crystal growing device used for producing the lithium tantalate single crystal of Comparative Example 1 was the same as the single crystal growing device used for producing the lithium tantalate single crystal of Example 1 except that the quartz glass cover was not attached. It was substantially the same.

［評価結果］
実施例１のタンタル酸リチウム単結晶及び比較例１のタンタル酸リチウム単結晶の結晶育成を繰り返した結果、実施例１のタンタル酸リチウム単結晶の方が比較例１のタンタル酸リチウム単結晶に比べて歩留りが１０％程高かった。比較例１のタンタル酸リチウム単結晶の作製に用いた単結晶育成装置では、アルミナ製ブランケットはむき出しになって結晶育成中のＬｉ２Ｏ蒸気下による高温アルカリ雰囲気にアルミナ製ブランケットが晒されることにより発塵し、比較例１のタンタル酸リチウム単結晶に不純物が混入したと考えられる。
また、比較例１のタンタル酸リチウム単結晶の作製に用いた単結晶育成装置では、タンタル酸リチウム単結晶の作製を１０回実施した段階でアルミナ製ブランケットは毛羽立ち、断熱性能の劣化がみられたため、アルミナ製ブランケットの交換が必要となった。一方、実施例１のタンタル酸リチウム単結晶の作製に用いた単結晶育成装置では、タンタル酸リチウム単結晶の作製を５０回実施した段階でもアルミナ製ブランケットに毛羽立ち等の異常は見られず、断熱性能にも問題がなかったので、アルミナ製ブランケットをさらに継続して使用することが可能であった。
比較例１のタンタル酸リチウム単結晶の作製に用いた単結晶育成装置では、アルミナ製ブランケットはむき出しになって結晶育成中のＬｉ２Ｏ蒸気下による高温アルカリ雰囲気にさらされること、また、原料のセット、結晶取出し時等で作業者がアルミナ製ブランケットに接触することにより、アルミナ製ブランケットが劣化してアルミナ製ブランケットの断熱性能が悪化すると考えられる。 [Evaluation results]
As a result of repeating the crystal growth of the lithium tantalate single crystal of Example 1 and the lithium tantalate single crystal of Comparative Example 1, the lithium tantalate single crystal of Example 1 was compared with the lithium tantalate single crystal of Comparative Example 1. The yield was about 10% higher. In the single crystal growing apparatus used for producing the lithium tantalate single crystal of Comparative Example 1, the alumina blanket was exposed and the alumina blanket was exposed to a high temperature alkaline atmosphere under Li 2 O steam during crystal growth. It is considered that dust was generated and impurities were mixed in the lithium tantalate single crystal of Comparative Example 1.
Further, in the single crystal growing apparatus used for producing the lithium tantalate single crystal of Comparative Example 1, the alumina blanket was fluffed and the heat insulating performance was deteriorated at the stage where the lithium tantalate single crystal was produced 10 times. , It was necessary to replace the alumina blanket. On the other hand, in the single crystal growing apparatus used for producing the lithium tantalate single crystal of Example 1, no abnormality such as fluffing was observed in the alumina blanket even at the stage where the lithium tantalate single crystal was produced 50 times, and heat insulation was performed. Since there was no problem in performance, it was possible to continue using the alumina blanket.
In the single crystal growing apparatus used for producing the lithium tantalate single crystal of Comparative Example 1, the alumina blanket was exposed and exposed to a high temperature alkaline atmosphere under Li 2 O steam during crystal growth, and the raw material was used. It is considered that when the operator comes into contact with the alumina blanket during setting, crystal removal, etc., the alumina blanket deteriorates and the heat insulating performance of the alumina blanket deteriorates.

１ るつぼ
１ａ るつぼ外周面
１ｂ るつぼ底
２ 加熱コイル
３ 保持棒
４ 熱電対
５ るつぼ台
６ 保温材
７ アフターヒータ
８ リフレクター
９ アフターヒータ蓋
１０ａ 下部耐火物容器
１０ｂ 上部耐火物容器
１１ 種子結晶
１２ 融液
１３ 単結晶
１３ａ 肩部
１３ｂ 直胴部
１４ 断熱保温構造（アルミナ製ブランケット）
１５ 絶縁性セラミック材料（石英ガラス製カバー）
１６ るつぼの上方の空間
９０，９０Ａ 単結晶育成装置 1 Crucible 1a Crucible outer surface 1b Crucible bottom 2 Heating coil 3 Holding rod 4 Thermoelectric pair 5 Crucible stand 6 Heat insulating material 7 Afterheater 8 Reflector 9 Afterheater lid 10a Lower refractory container 10b Upper refractory container 11 Seed crystal 12 Melt 13 Single crystal 13a Shoulder 13b Straight body 14 Insulation and heat insulation structure (alumina blanket)
15 Insulating ceramic material (quartz glass cover)
16 Space above the crucible 90, 90A Single crystal growing device

Claims (3)

引き上げ法によってるつぼ内の原料の融液から単結晶を育成する単結晶育成装置において、
前記るつぼの上方の空間を覆う上部耐火物容器と、
前記上部耐火物容器の外周を覆う断熱保温構造と、
前記断熱保温構造の外周を覆う絶縁性セラミック材料とを備える単結晶育成装置。 In a single crystal growing device that grows a single crystal from the melt of the raw material in the crucible by the pulling method
An upper refractory container that covers the space above the crucible,
A heat insulating and heat insulating structure that covers the outer circumference of the upper refractory container,
A single crystal growing device including an insulating ceramic material that covers the outer periphery of the heat insulating and heat insulating structure. 前記るつぼ内の前記原料は、前記るつぼの外周を囲む加熱コイルを使用した高周波誘導加熱方式で加熱されて前記融液となり、
前記絶縁性セラミック材料は円筒形状であり、
前記絶縁性セラミック材料の外径は前記加熱コイルの内径よりも小さい請求項１に記載の単結晶育成装置。 The raw material in the crucible is heated by a high-frequency induction heating method using a heating coil surrounding the outer circumference of the crucible to become the melt.
The insulating ceramic material has a cylindrical shape and has a cylindrical shape.
The single crystal growing apparatus according to claim 1, wherein the outer diameter of the insulating ceramic material is smaller than the inner diameter of the heating coil. 前記単結晶が、タンタル酸リチウムの単結晶またはニオブ酸リチウムの単結晶である請求項１または２に記載の単結晶育成装置。 The single crystal growing apparatus according to claim 1 or 2, wherein the single crystal is a single crystal of lithium tantalate or a single crystal of lithium niobate.
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CN1272475C (en) * 2000-02-24 2006-08-30 东芝株式会社 Method and equipment for producing single crystal of oxides
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JPS54128989A (en) * 1978-03-31 1979-10-05 Toshiba Corp Preparation of oxide single crystal
JPS6278197A (en) * 1985-09-27 1987-04-10 アメリカン　テレフォン　アンド　テレグラフ　カムパニー Manufacture of homogeneous lithium niobate
JPH0812487A (en) * 1994-06-29 1996-01-16 Shin Etsu Chem Co Ltd Manufacturing of oxide single crystal
JP2005001934A (en) * 2003-06-11 2005-01-06 Daiichi Kiden:Kk Apparatus for pulling and growing sapphire single crystal
JP2017007884A (en) * 2015-06-18 2017-01-12 住友金属鉱山株式会社 Production method of single crystal

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