JP2017024946A - Single crystal growth method and apparatus therefor - Google Patents
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本発明は、単結晶成長方法およびその装置に関し、より詳細には、チタン酸バリウムストロンチウム単結晶のように２次の電気光学効果を利用した光学素子として使用される単結晶の成長方法およびその装置に関する。 The present invention relates to a method for growing a single crystal and an apparatus therefor, and more particularly, a method for growing a single crystal used as an optical element utilizing a secondary electro-optic effect such as a barium strontium titanate single crystal and an apparatus therefor. About.
電界の１乗または２乗に比例して屈折率が変化する電気光学効果を有する物質は、光変調器を構成する材料として、光通信、レーザー光による機械加工の分野などに広く用いられている。電界の１乗に比例して屈折率が変化する電気光学効果はポッケルス効果、電界の２乗に比例して屈折率が変化する電気光学効果はカー効果と呼ばれている。ポッケルス効果を利用した光変調器に用いられる物質として、ニオブ酸リチウム（ＬｉＮｂＯ3：ＬＮ）、タンタル酸リチウム（ＬｉＴａＯ3：ＬＴ）が挙げられ、また、カー効果を利用する物質として、ニオブ酸タンタル酸カリウム（ＫＴａ1-xＮｂxＯ3：ＫＴＮ）、チタン酸ジルコン酸ランタン鉛（（Ｐｂ1-xＬａx）（ＺｒyＴｉ1-y）1-x/4Ｏ3：ＰＬＺＴ）が挙げられる。光変調器として利用する際には、これらの電気光学効果を有する物質を、溶液から結晶成長させ、単結晶のバルク材料を作製し、所望のサイズに加工する。 Substances having an electro-optic effect whose refractive index changes in proportion to the first or second power of an electric field are widely used as materials constituting optical modulators in the fields of optical communication, machining with laser light, and the like. . The electro-optic effect in which the refractive index changes in proportion to the first power of the electric field is called the Pockels effect, and the electro-optic effect in which the refractive index changes in proportion to the second power of the electric field is called the Kerr effect. Examples of the material used in the optical modulator using the Pockels effect include lithium niobate (LiNbO 3 : LN) and lithium tantalate (LiTaO 3 : LT), and examples of the material using the Kerr effect include tantalum niobate. potassium acid (KTa 1-x Nb x O 3: KTN), lead lanthanum zirconate titanate ((Pb 1-x La x ) (Zr y Ti 1-y) 1-x / 4 O 3: PLZT) include It is done. When used as an optical modulator, these substances having an electro-optic effect are crystal-grown from a solution to produce a single crystal bulk material and processed into a desired size.
ポッケルス効果を利用するＬＮ、ＬＴは、共に固溶体である。単結晶成長を行う際、溶融体の組成と単結晶として取り出したときの組成とが一致する一致溶融を示す（融液成長）。このため、単結晶成長の間に組成が変動しにくく、また、単結晶内で組成が分布することもなく、均一な組成の単結晶を製造することが可能である（例えば、非特許文献１参照）。ただし、以下に述べるカー効果を利用した材料に比べると、電気光学効果が小さく、光変調器を構成したときに、必要とされる屈折率変化量を得るには、単結晶材料に大きな印加電圧が必要とされる。 Both LN and LT using the Pockels effect are solid solutions. When single crystal growth is performed, coincident melting in which the composition of the melt coincides with the composition when taken out as a single crystal (melt growth). For this reason, it is difficult to change the composition during single crystal growth, and it is possible to manufacture a single crystal having a uniform composition without the composition being distributed within the single crystal (for example, Non-Patent Document 1). reference). However, compared to materials using the Kerr effect described below, the electro-optic effect is small, and a large applied voltage is applied to a single crystal material in order to obtain the required amount of refractive index change when an optical modulator is configured. Is needed.
カー効果を示すＫＴＮは、タンタル酸カリウム（ＫＴａＯ3：ＫＴ）とニオブ酸カリウム（ＫＮｂＯ3：ＫＮ）の固溶体であるが、単結晶成長を行う際、溶融体の組成と異なる組成の単結晶が晶出する（溶液成長）。このため、単結晶成長に伴って溶融体の組成も変化し、さらに、それに伴って晶出する単結晶の組成も連続的に変化していく。従って、均一な組成の単結晶を製造することが難しい。均一な組成の単結晶を製造するために、単結晶成長の間に組成が変動しないように、単結晶を引き上げながら原料を加えて成長させる方法が提案されている（例えば、特許文献１参照）。 KTN showing the Kerr effect is a solid solution of potassium tantalate (KTaO 3 : KT) and potassium niobate (KNbO 3 : KN). When single crystal growth is performed, a single crystal having a composition different from the composition of the melt is produced. Crystallize (solution growth). For this reason, the composition of the melt changes with the growth of the single crystal, and the composition of the single crystal that crystallizes continuously changes accordingly. Therefore, it is difficult to produce a single crystal having a uniform composition. In order to manufacture a single crystal having a uniform composition, a method of growing by adding a raw material while pulling up the single crystal has been proposed so that the composition does not fluctuate during single crystal growth (see, for example, Patent Document 1). .
しかしながら、ＫＴＮの成長過程においては、溶液組成と単結晶組成とが異なることに加えて、成長中に、その１成分であるカリウムが蒸発し、単結晶成長に使用する装置の耐火物に付着するという問題があった。カリウムの付着により耐火物を劣化させ、その耐用期間を短くするのみならず、蒸発して耐火物に付着したカリウムが溶液中に落下し、単結晶の品質劣化の原因となることがある。 However, in the growth process of KTN, in addition to the difference between the solution composition and the single crystal composition, potassium, which is one component, evaporates during the growth and adheres to the refractory of the apparatus used for the single crystal growth. There was a problem. The adhesion of potassium not only degrades the refractory and shortens its useful life, but also the potassium that evaporates and adheres to the refractory falls into the solution and may cause deterioration of the quality of the single crystal.
カリウムの蒸発を抑制する手段として、単結晶を引き上げながら成長させる単結晶成長装置内の温度分布の勾配を緩やかにすることが有効である。しかしながら、成長中の単結晶と溶液が接している界面での温度勾配も緩やかになるため、結晶品質の劣化の原因となる組成的過冷却が生じやすくなる。この組成的過冷却を回避するためには、単位時間あたりに成長させる単結晶の体積を抑制することが必要となり、その結果、所望の大きさの単結晶を製造するのに必要とする時間が長くなる。 As a means for suppressing the evaporation of potassium, it is effective to moderate the temperature distribution gradient in the single crystal growth apparatus that grows while pulling up the single crystal. However, since the temperature gradient at the interface where the growing single crystal is in contact with the solution also becomes gentle, compositional supercooling that causes deterioration of crystal quality is likely to occur. In order to avoid this compositional supercooling, it is necessary to suppress the volume of the single crystal grown per unit time, and as a result, the time required to produce a single crystal of a desired size is required. become longer.
カリウムの蒸発を考慮せず、また、界面における温度勾配を急峻にしても、単結晶の成長が可能な方法として、垂直ブリッジマン法がある（例えば、非特許文献２参照）。しかしながら、溶液および単結晶を保持する白金のるつぼを、単結晶を取り出す度に切断する必要があるので、白金のるつぼを改鋳し、再利用するのにコストがかかる。 There is a vertical Bridgman method as a method capable of growing a single crystal even if the evaporation of potassium is not taken into account and the temperature gradient at the interface is steep (see, for example, Non-Patent Document 2). However, since it is necessary to cut the platinum crucible holding the solution and the single crystal every time the single crystal is taken out, it is costly to recast and reuse the platinum crucible.
一方、蒸発しやすいカリウムを含まず、大きなカー効果を示す材料としてチタン酸バリウムストロンチウム（Ｂａ1-xＳｒxＴｉＯ3，０≦ｘ≦１：ＢＳＴ）がある。ＢＳＴ単結晶の結晶成長においては、結晶成長が進行するに従ってファセット面が出現し、四角い結晶が晶出し、結晶の肩拡げ過程が進行するとともに、溶液の深さ方向へもその形状を反映した直胴部が形成されていく（例えば、非特許文献３参照）。肩拡げ過程における単結晶の水平方向の幅は、成長が速い場合には溶液の冷却速度を下げ、成長が遅い場合には溶液の冷却速度を上げることにより制御することができる。このような結晶成長の手順は、ＫＴＮと同様であるが、蒸発しやすいカリウムを含まないため、カリウムの蒸発に起因する単結晶の品質の劣化を回避しつつ、大きなカー効果を有する単結晶を作製することが可能である。 On the other hand, there is barium strontium titanate (Ba 1-x Sr x TiO 3 , 0 ≦ x ≦ 1: BST) as a material which does not contain easily evaporated potassium and shows a large Kerr effect. In crystal growth of a BST single crystal, facet faces appear as crystal growth progresses, square crystals crystallize, the crystal shoulder expansion process proceeds, and the shape is also reflected in the depth direction of the solution. A trunk | drum is formed (for example, refer nonpatent literature 3). The horizontal width of the single crystal in the shoulder expansion process can be controlled by decreasing the solution cooling rate when the growth is fast, and increasing the solution cooling rate when the growth is slow. Such a crystal growth procedure is the same as that of KTN, but does not include potassium that easily evaporates. Therefore, a single crystal having a large Kerr effect is avoided while avoiding deterioration of the quality of the single crystal due to evaporation of potassium. It is possible to produce.
しかしながら、ＢＳＴ単結晶の結晶成長においても、肩拡げ過程を行った結晶は、例えば、ある方向にのみ優先的に成長するなどして、結晶を所望の幅の直方体に制御するのが困難である。加えて、このように優先的な結晶成長が生じた場合に、その成長結晶を支える種結晶には不均等な荷重がかかってしまう。このため、成長中に結晶が落下するなど生産性の向上に支障が出るのみならず、仮に落下しなくても結晶品質が不均一になるという問題があった。 However, even in the crystal growth of a BST single crystal, it is difficult to control a crystal in a desired rectangular width by, for example, preferentially growing a crystal that has undergone a shoulder expansion process only in a certain direction. . In addition, when such preferential crystal growth occurs, an uneven load is applied to the seed crystal that supports the grown crystal. For this reason, there is a problem that the crystal quality is not uniform even if it does not drop, as well as the improvement of productivity such as the crystal falling during growth.
本発明の目的は、ＢＳＴ単結晶の結晶成長において、結晶を所望の寸法の直方体に制御することができる単結晶成長方法およびその装置を提供することにある。 An object of the present invention is to provide a single crystal growth method and apparatus capable of controlling a crystal into a rectangular parallelepiped having a desired size in the growth of a BST single crystal.
本発明は、このような目的を達成するために、一実施態様は、炉内に設置されたるつぼ内の原料溶融体の表面に、種子結晶を接触させ、前記原料溶融体を冷却することにより、前記種子結晶を核として結晶を成長させる単結晶成長装置であって、前記るつぼは、直方体の形状を有し、炉内の温度を一定に保つ均熱管と、前記原料溶融体を昇温溶融するためのヒータとが、前記るつぼの中心軸を共有する直方体形状であることを特徴とする。 In order to achieve the above object, according to one embodiment of the present invention, a seed crystal is brought into contact with the surface of a raw material melt in a crucible installed in a furnace, and the raw material melt is cooled. A single crystal growth apparatus for growing a crystal using the seed crystal as a nucleus, wherein the crucible has a rectangular parallelepiped shape, a soaking tube that keeps the temperature in the furnace constant, and the raw material melt is heated and melted The heater for performing is a rectangular parallelepiped shape sharing the central axis of the crucible.
加えて、前記種子結晶が取り付けられる引き上げ軸と前記るつぼとは、結晶成長中に回転しないことを特徴とする。 In addition, the pulling shaft to which the seed crystal is attached and the crucible do not rotate during crystal growth.
以上説明したように、本発明によれば、るつぼ、均熱管およびヒータが直方体の形状を有するので、るつぼを満たしている原料溶融体の表面温度の等高線は四回対称性を有し、等高線を反映した方形の結晶幅を有する単結晶を成長させることができ、ＢＳＴ単結晶の結晶成長において、結晶を所望の寸法の直方体に制御することができる。 As described above, according to the present invention, since the crucible, the heat equalizing tube and the heater have a rectangular parallelepiped shape, the contour line of the surface temperature of the raw material melt filling the crucible has fourfold symmetry, A single crystal having a reflected square crystal width can be grown, and the crystal can be controlled to a rectangular parallelepiped having a desired dimension in the crystal growth of the BST single crystal.
最初に、従来の単結晶成長装置の構成を説明し、次に、本発明の実施形態について詳細に説明する。 First, the configuration of a conventional single crystal growth apparatus will be described, and then embodiments of the present invention will be described in detail.
図１に、従来の単結晶成長装置を示す。単結晶製造装置は、ヒータ４によって温度制御可能な電気炉５を有し、電気炉５内のるつぼ台２に原料溶融体８を入れたるつぼ１を設置している。電気炉５は、炉体ふた１０により密閉され、内面に設置された均熱管３により、炉内の温度が一定に保たれるようになっている。このような構成において、引き上げ軸６の先端に取り付けられた種子結晶７を、溶融した原料溶融体８に浸して、成長結晶９を育成する。 FIG. 1 shows a conventional single crystal growth apparatus. The single crystal manufacturing apparatus has an electric furnace 5 whose temperature can be controlled by a heater 4, and a crucible 1 in which a raw material melt 8 is placed in a crucible base 2 in the electric furnace 5. The electric furnace 5 is hermetically sealed by a furnace body lid 10, and the temperature inside the furnace is kept constant by a soaking tube 3 installed on the inner surface. In such a configuration, the seed crystal 7 attached to the tip of the pulling shaft 6 is immersed in the melted raw material melt 8 to grow the growth crystal 9.
秤量した素原料が充填されたるつぼ１を、電気炉５内に設置されたるつぼ台２上に設置する。ヒータ４を加熱することで、原料を昇温溶融し、原料溶融体８を準備する。種子結晶７が先端に取り付けられた引き上げ軸６を電気炉５に導入し、原料溶融体８に接触させ、結晶育成を開始する。 The crucible 1 filled with the weighed raw material is placed on the crucible base 2 installed in the electric furnace 5. By heating the heater 4, the raw material is heated and melted to prepare the raw material melt 8. The pulling shaft 6 with the seed crystal 7 attached to the tip is introduced into the electric furnace 5 and brought into contact with the raw material melt 8 to start crystal growth.
種子結晶７を原料溶融体８の表面に接触させる、すなわち種子付け過程では、原料溶融体８の温度を調整し、種子結晶７が溶融せずかつ結晶成長も生じない状態を実現する。その後、引き上げ軸６を回転しながら引き上げると同時に、加熱量の調整により原料溶融体８を冷却して行く。この冷却により、原料溶融体８は、過冷却または過飽和状態となる。結晶成長に十分な過冷却または過飽和状態が原料溶融体８に実現すると、種子結晶７の先端に結晶が析出し始め、結晶成長が始まる。そして、種子付け、肩拡げ、定径部と順に成長過程を進行させる。 The seed crystal 7 is brought into contact with the surface of the raw material melt 8, that is, in the seeding process, the temperature of the raw material melt 8 is adjusted to realize a state in which the seed crystal 7 does not melt and crystal growth does not occur. Thereafter, the raw material melt 8 is cooled by adjusting the heating amount at the same time as the pulling shaft 6 is pulled up while rotating. By this cooling, the raw material melt 8 becomes supercooled or supersaturated. When a supercooled or supersaturated state sufficient for crystal growth is realized in the raw material melt 8, crystal starts to precipitate at the tip of the seed crystal 7, and crystal growth starts. Then, the growth process proceeds in the order of seeding, shoulder expansion, and constant diameter portion.
成長中は、結晶の成長状態を形状センサまたは重量センサを用いて検出し、成長速度が早い場合には昇温、成長速度が遅い場合には冷却の微調整を加えて、成長結晶９の直径制御を行う。成長速度を調整するために、昇温・冷却の微調整を加えずに、引き上げ軸６の引き上げ速度を微調整することにより、成長結晶９の直径制御を行ってもよい。 During the growth, the growth state of the crystal is detected by using a shape sensor or a weight sensor. When the growth rate is fast, the temperature is increased, and when the growth rate is slow, the cooling is finely adjusted. Take control. In order to adjust the growth rate, the diameter of the growth crystal 9 may be controlled by finely adjusting the pulling rate of the pulling shaft 6 without making fine adjustments of temperature rise and cooling.
従来の単結晶製造装置は、図２の模式図に示したように、引き上げ軸６および種子結晶７の設置位置を中心軸とした縦型管状炉であり、円筒形状のるつぼ１の周りに、同心円状に円筒形状の均熱管３およびヒータ４が配置されている。そして、円筒形状のるつぼ１の中心軸において、種子結晶７を原料溶融体８の表面に接触させる。 As shown in the schematic diagram of FIG. 2, the conventional single crystal manufacturing apparatus is a vertical tubular furnace having the installation position of the pulling shaft 6 and the seed crystal 7 as a central axis, and around the cylindrical crucible 1, A cylindrical soaking tube 3 and a heater 4 are arranged concentrically. Then, the seed crystal 7 is brought into contact with the surface of the raw material melt 8 at the central axis of the cylindrical crucible 1.
このとき、るつぼ１に関して言えば、最も高温な部分は、均熱管３に最も近いるつぼ壁である。るつぼ１を満たしている原料溶融体８の表面温度の等高線２１は、図３（ａ）に示したように、るつぼ壁が最も高く、るつぼ１の中心軸が最も低くなる。原料溶融体８は、るつぼ壁で熱せられ、るつぼ中心部にある原料溶融体８と比較すると相対的に高温になる。相対的に高温の溶融体は密度も相対的に小さくなるため、るつぼ１の内壁に沿って上昇した後、るつぼ１の中心部へ向かって流れる。るつぼ１の底では、るつぼ１の中央から内壁に向かって、相対的に低温の溶液が流れ込み、るつぼ壁で加熱されて、再び内壁に沿って上昇する。この対流２２の様子を図３（ｂ）に示す。 At this time, with regard to the crucible 1, the hottest portion is the crucible wall closest to the soaking tube 3. As shown in FIG. 3A, the contour line 21 of the surface temperature of the raw material melt 8 filling the crucible 1 has the highest crucible wall and the lowest central axis of the crucible 1. The raw material melt 8 is heated by the crucible wall and becomes relatively high in temperature as compared with the raw material melt 8 in the center of the crucible. Since the relatively hot melt has a relatively small density, it rises along the inner wall of the crucible 1 and then flows toward the center of the crucible 1. At the bottom of the crucible 1, a relatively cool solution flows from the center of the crucible 1 toward the inner wall, is heated by the crucible wall, and rises again along the inner wall. The state of the convection 22 is shown in FIG.
種子結晶７を引き上げる上下方向（垂直方向）の温度勾配が急峻な場合、種子結晶７と原料溶融体８とが接触する表面では、加熱された溶液が溶液表面に連続的に出現し、相対的に低温の溶液となって、るつぼ１の底へ下降し、中央から内壁に向かって対流する。このとき、種子結晶７と原料溶融体８とが接触する部分を、過冷却または過飽和状態となるように、炉内の温度を制御することにより、結晶成長が始まる。 When the temperature gradient in the vertical direction (vertical direction) for pulling up the seed crystal 7 is steep, the heated solution continuously appears on the solution surface on the surface where the seed crystal 7 and the raw material melt 8 are in contact with each other. It becomes a low-temperature solution, descends to the bottom of the crucible 1, and convects from the center toward the inner wall. At this time, crystal growth starts by controlling the temperature in the furnace so that the portion where the seed crystal 7 and the raw material melt 8 are brought into a supercooled or supersaturated state.
なお、種子結晶７と原料溶融体８とが接触する部分の温度を、精度よく制御するために、種子結晶７と原料溶融体８とが接触する部分からの脱熱を促す機構を設けてもよい。具体的には、引き上げ軸６を、白金またはアルミナ材料で作製し、種子結晶７の熱を炉外に放熱できるようにする。また、引き上げ軸６の内部に外気の通気孔を設け、種子結晶７からの脱熱を促す機構を設けてもよい。均熱管３およびヒータ４による炉内の温度制御に加えて、局所的な温度制御を、容易に行うことができる。 In order to accurately control the temperature of the portion where the seed crystal 7 and the raw material melt 8 are in contact, a mechanism for promoting heat removal from the portion where the seed crystal 7 and the raw material melt 8 are in contact may be provided. Good. Specifically, the pulling shaft 6 is made of platinum or alumina material so that the heat of the seed crystal 7 can be dissipated out of the furnace. Further, a mechanism for promoting the heat removal from the seed crystal 7 by providing a vent hole for the outside air inside the pulling shaft 6 may be provided. In addition to temperature control in the furnace by the soaking tube 3 and the heater 4, local temperature control can be easily performed.
さらに、図３（ｂ）に示した対流を促し、原料溶融体８の組成が均一になるようにするために、るつぼ１の内部に原料溶融体８を攪拌する手段を備えてもよい。具体的には、プロペラ形状の撹拌羽であって、攪拌羽の回転軸は、るつぼ１の上部から底部まで、上下
方向に移動可能なように設置する。攪拌羽を原料溶融体８の液面下におき、上記の対流を促す方向に回転軸を設定して、原料溶融体８を攪拌する。
Furthermore, in order to promote the convection shown in FIG. 3B and make the composition of the raw material melt 8 uniform, a means for stirring the raw material melt 8 may be provided inside the crucible 1. Specifically, it is a propeller-shaped stirring blade, and the rotation shaft of the stirring blade is installed so as to be movable in the vertical direction from the top to the bottom of the crucible 1. The stirring blade is placed below the liquid surface of the raw material melt 8 and the raw material melt 8 is stirred by setting the rotation axis in a direction that promotes the convection.
図４に、本発明の一実施形態にかかる単結晶成長装置を示す。本実施形態の単結晶成長装置は、引き上げ軸６および種子結晶７の設置位置を中心軸とした縦型管状炉であるが、るつぼ１１が直方体の形状を有し、中心軸を共有する直方体形状の均熱管１３およびヒータ１４が配置されている。るつぼ１１の水平方向の断面形状は、正方形として説明するが、所望の形状の結晶を得るために、長方形または四角形としたり、角丸四角形としてもよい。 FIG. 4 shows a single crystal growth apparatus according to an embodiment of the present invention. The single crystal growth apparatus of the present embodiment is a vertical tubular furnace having a central axis at the installation position of the pulling shaft 6 and the seed crystal 7, but the crucible 11 has a rectangular parallelepiped shape and shares a central axis. The soaking tube 13 and the heater 14 are arranged. The cross-sectional shape in the horizontal direction of the crucible 11 is described as a square. However, in order to obtain a crystal having a desired shape, it may be a rectangle or a rectangle, or a rounded rectangle.
このとき、るつぼ１１を満たしている原料溶融体８の表面温度の等高線２３は、図５に示したように、四回対称性を有し、るつぼ壁が最も高く、るつぼ１１の中心軸が最も低くなる。るつぼ１１の内部で生ずる対流は、るつぼ１１の中心軸を通る断面では、図３（ｂ）と同じである。原料溶融体８の表面温度の等高線が正方形を描くようにした状態で、種子結晶７と原料溶融体８とが接触する部分の温度を、過冷却または過飽和状態となるように、炉内の温度を制御することにより、結晶成長が始まる。 At this time, the contour line 23 of the surface temperature of the raw material melt 8 filling the crucible 11 has fourfold symmetry, the crucible wall is the highest, and the central axis of the crucible 11 is the highest. Lower. Convection generated inside the crucible 11 is the same as that in FIG. 3B in a cross section passing through the central axis of the crucible 11. In the state where the contour line of the surface temperature of the raw material melt 8 draws a square, the temperature in the furnace is set so that the temperature of the portion where the seed crystal 7 and the raw material melt 8 come into contact is supercooled or supersaturated. By controlling the above, crystal growth starts.
従来の単結晶製造装置は、上述したように、結晶成長中は、種子結晶７および育成結晶が取り付けられた引き上げ軸６、またはるつぼ１およびるつぼ台２を回転させ、溶液の撹拌を行いながら結晶成長を行う。一方、本実施形態では、このような攪拌を行わず、結晶の引上げ方向の温度勾配を急峻にすることにより、図３（ｂ）に示したような自然対流を生じさせ、この自然対流のみを利用して溶液を撹拌する。 As described above, the conventional single crystal manufacturing apparatus rotates the pulling shaft 6 to which the seed crystal 7 and the grown crystal are attached, or the crucible 1 and the crucible base 2 during the crystal growth, while stirring the solution. Do growth. On the other hand, in this embodiment, such agitation is not performed, and the temperature gradient in the pulling direction of the crystal is made steep, thereby generating natural convection as shown in FIG. Utilize the solution to stir.
成長中は、結晶の成長状態を形状センサまたは重量センサを用いて検出し、成長速度が早い場合には昇温、成長速度が遅い場合には冷却の微調整を加えて、成長結晶９の直径制御を行う。このような構成により、原料溶融体８の表面温度の正方形の等高線を反映し、正方形に結晶幅が制御された結晶を育成することができる。 During the growth, the growth state of the crystal is detected by using a shape sensor or a weight sensor. When the growth rate is fast, the temperature is increased, and when the growth rate is slow, the cooling is finely adjusted. Take control. With such a configuration, it is possible to grow a crystal whose crystal width is controlled to a square reflecting the square contour line of the surface temperature of the raw material melt 8.
［実施例］
チタン酸バリウムストロンチウム（Ｂａ1-xＳｒxＴｉＯ3，０≦ｘ≦１：ＢＳＴ）の単結晶を成長させる場合の具体例を説明する。ＢＳＴの原料であるチタン酸バリウム（ＢａＴｉＯ3）、チタン酸ストロンチウム（ＳｒＴｉＯ3）を所望の組成で秤量し、るつぼ１１に混合し充填する。原料を充填したるつぼ１１は、水平方向の断面形状が１辺４インチの正方形である直方体である。るつぼ１１を、縦型管状炉内に設置されたるつぼ台２上に設置する。ヒータ１４を加熱することにより、原料を昇温溶融し、原料溶融体８を準備する。このとき、原料溶融体８の表面温度の等高線は、図５に示した通り、四回対称性を有する。
[Example]
A specific example in the case of growing a single crystal of barium strontium titanate (Ba 1-x Sr x TiO 3 , 0 ≦ x ≦ 1: BST) will be described. Barium titanate (BaTiO 3 ) and strontium titanate (SrTiO 3 ), which are BST raw materials, are weighed in a desired composition, mixed in a crucible 11 and filled. The crucible 11 filled with the raw material is a rectangular parallelepiped having a horizontal cross-sectional shape of a square having a side of 4 inches. The crucible 11 is installed on the crucible base 2 installed in the vertical tubular furnace. By heating the heater 14, the raw material is heated and melted to prepare the raw material melt 8. At this time, the contour line of the surface temperature of the raw material melt 8 has four-fold symmetry as shown in FIG.
種子結晶７が先端に取り付けられた引き上げ軸６を電気炉５に導入し、原料溶融体８の表面に接触させ、結晶育成を開始する。種子結晶７を原料溶融体８に接触させる際、すなわち種子付け過程では、原料溶融体８の温度を調整し、種子結晶７が溶融せずかつ結晶成長も生じない状態を実現する。その後、引き上げ軸６を回転させずに、加熱量の調整により原料溶融体８を冷却して行く。この冷却により、原料溶融体８は過飽和状態となり、脱熱されている引き上げ軸６により冷却され原料溶融体８中で最も温度の低い種子結晶７の先端に結晶が析出し始め、結晶成長が始まる。 The pulling shaft 6 with the seed crystal 7 attached to the tip is introduced into the electric furnace 5 and brought into contact with the surface of the raw material melt 8 to start crystal growth. When the seed crystal 7 is brought into contact with the raw material melt 8, that is, in the seeding process, the temperature of the raw material melt 8 is adjusted to realize a state in which the seed crystal 7 does not melt and crystal growth does not occur. Thereafter, the raw material melt 8 is cooled by adjusting the heating amount without rotating the pulling shaft 6. By this cooling, the raw material melt 8 becomes supersaturated, and cooled by the deheated pulling shaft 6, crystals begin to precipitate at the tip of the seed crystal 7 having the lowest temperature in the raw material melt 8, and crystal growth begins. .
一定の冷却速度でヒータ１４の出力を低下させて、原料溶融体８の冷却を継続することにより、成長結晶９の幅が増加し、成長結晶９の肩拡げ工程を行う。１辺２インチの肩拡げ成長過程後、定径部過程に移り、直胴部の結晶成長を開始する。成長中は、結晶の成長状態を形状センサまたは重量センサを用いて検出し、成長速度が早い場合には昇温、成長速度が遅い場合には冷却の微調整を加えて、成長結晶９の直径制御を行う。 By reducing the output of the heater 14 at a constant cooling rate and continuing to cool the raw material melt 8, the width of the growth crystal 9 is increased and the shoulder expansion process of the growth crystal 9 is performed. After the shoulder expansion growth process of 2 inches per side, the process proceeds to the constant diameter part process, and crystal growth of the straight body part is started. During the growth, the growth state of the crystal is detected by using a shape sensor or a weight sensor. When the growth rate is fast, the temperature is increased, and when the growth rate is slow, the cooling is finely adjusted. Take control.
所望の大きさの成長結晶が得られた時点で、成長結晶９を原料溶融体８から切り離し、ヒータ１４の出力を下げ、縦型管状炉を室温まで冷却する。成長したＢＳＴ単結晶は、ほぼ１辺２インチの立方体に制御されており、欠陥発生も見られない。 When a growth crystal of a desired size is obtained, the growth crystal 9 is separated from the raw material melt 8, the output of the heater 14 is lowered, and the vertical tubular furnace is cooled to room temperature. The grown BST single crystal is controlled to be a cube having a side of approximately 2 inches, and no defect is observed.
従来の単結晶成長装置では、円筒形状のるつぼ１において肩拡げ過程を行った結晶は、ある方向にのみ優先的に成長するため、種子結晶７に不均等な荷重がかかってしまい、結晶成長１０回のうち５回は、成長結晶９が落下していた。本実施形態の単結晶成長装置は、肩拡げ過程と定径部過程の間に、原料溶融体８の表面温度の正方形の等高線を反映したＢＳＴ単結晶が析出するので、結晶成長１０回のうち１回も成長結晶９が落下することなく、結晶成長を終えることができる。また、単結晶成長中に溶液から蒸発する物質もないため、耐火物の劣化もなくなり、単結晶成長装置の耐用期間が５倍になる。 In the conventional single crystal growth apparatus, the crystal that has undergone the shoulder expansion process in the cylindrical crucible 1 grows preferentially only in a certain direction, so that an uneven load is applied to the seed crystal 7 and the crystal growth 10 Five times of the times, the growing crystal 9 was falling. In the single crystal growth apparatus of the present embodiment, the BST single crystal reflecting the square contours of the surface temperature of the raw material melt 8 is precipitated between the shoulder expansion process and the constant diameter part process. Crystal growth can be completed without the growth crystal 9 falling once. In addition, since there is no substance that evaporates from the solution during single crystal growth, there is no deterioration of the refractory, and the lifetime of the single crystal growth apparatus is increased five times.
以上説明したように、本実施形態によれば、ＢＳＴ単結晶の結晶成長において、溶液を入れるるつぼとるつぼを囲う均熱管とを直方体とし、かつ、種子結晶を回転しないことにより、ＢＳＴ単結晶を所望の寸法の直方体に成長させることができる。これにより、大きな２次の電気光学効果を有する材料を、安価な原料で高品質に作製することができる。 As described above, according to the present embodiment, in the crystal growth of the BST single crystal, the soaking tube that encloses the crucible and the crucible surrounding the solution is used as a rectangular parallelepiped, and the seed crystal is not rotated. A rectangular parallelepiped having a desired size can be grown. As a result, a material having a large secondary electro-optic effect can be manufactured with a high quality from an inexpensive raw material.
１，１１ るつぼ
２ るつぼ台
３，１３ 均熱管
４，１４ ヒータ
５ 電気炉
６ 引き上げ軸
７ 種子結晶
８ 原料溶融体
９ 成長結晶
１０ 炉体ふた
1,11 crucible 2 crucible base 3,13 soaking tube 4,14 heater 5 electric furnace 6 pulling shaft 7 seed crystal 8 raw material melt 9 grown crystal 10 furnace body lid
Claims (8)
前記るつぼは、直方体の形状を有し、
炉内の温度を一定に保つ均熱管と、前記原料溶融体を昇温溶融するためのヒータとが、前記るつぼの中心軸を共有する直方体形状であることを特徴とする単結晶成長装置。 A single crystal growth apparatus for growing a crystal using the seed crystal as a nucleus by bringing a seed crystal into contact with the surface of the raw material melt in a crucible installed in a furnace and cooling the raw material melt,
The crucible has a rectangular parallelepiped shape,
A single crystal growth apparatus characterized in that a soaking tube for keeping the temperature in the furnace constant and a heater for heating and melting the raw material melt have a rectangular parallelepiped shape sharing the central axis of the crucible.
前記るつぼは、直方体の形状を有し、前記るつぼの中心軸を共有する直方体形状である、炉内の温度を一定に保つ均熱管および前記原料溶融体を昇温溶融するためのヒータを制御して、前記るつぼを満たしている前記原料溶融体の表面温度の等高線が四回対称性を有するようにし、
前記種子結晶が前記原料溶融体と接触する部分の温度を、過冷却または過飽和状態となるように制御し、
単結晶の成長に伴って、前記種子結晶を引き上げながら炉内の温度を降下させて単結晶を成長させることを特徴とする単結晶成長方法。 A single crystal growth method in which a seed crystal is brought into contact with the surface of a raw material melt in a crucible installed in a furnace, and the raw material melt is cooled to grow a crystal using the seed crystal as a nucleus,
The crucible has a rectangular parallelepiped shape and is a rectangular parallelepiped shape that shares the central axis of the crucible, and controls a soaking tube that keeps the temperature in the furnace constant and a heater for heating and melting the raw material melt. The contour line of the surface temperature of the raw material melt that fills the crucible has a four-fold symmetry,
Controlling the temperature of the portion where the seed crystals come into contact with the raw material melt so as to be supercooled or supersaturated,
A method for growing a single crystal, wherein the single crystal is grown by lowering the temperature in the furnace while pulling up the seed crystal as the single crystal grows.
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Citations (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5138284A (en) * | 1974-09-30 | 1976-03-30 | Tokyo Shibaura Electric Co | Itajotanketsushono seizohoho |
| JPS63159284A (en) * | 1986-12-24 | 1988-07-02 | Mitsubishi Electric Corp | Single crystal pulling up device |
| JPH06321699A (en) * | 1993-05-11 | 1994-11-22 | Murata Mfg Co Ltd | Production of barium strontium titanate single crystal |
| JP2005119955A (en) * | 2003-09-25 | 2005-05-12 | Canon Inc | Method for continuously manufacturing crystal silicon and apparatus therefor |
| JP2006143489A (en) * | 2004-11-16 | 2006-06-08 | Nippon Telegr & Teleph Corp <Ntt> | Crystal growth device and method |
| JP2009155182A (en) * | 2007-12-27 | 2009-07-16 | Nippon Telegr & Teleph Corp <Ntt> | Crystal growth method and apparatus therefor |
| JP2013184842A (en) * | 2012-03-07 | 2013-09-19 | Jx Nippon Mining & Metals Corp | Silicon single crystal manufacturing device and method of manufacturing the same |
| JP2013189354A (en) * | 2012-03-15 | 2013-09-26 | Jx Nippon Mining & Metals Corp | Apparatus and method for producing silicon single crystal |
-
2015
- 2015-07-23 JP JP2015145950A patent/JP6401673B2/en active Active
Patent Citations (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5138284A (en) * | 1974-09-30 | 1976-03-30 | Tokyo Shibaura Electric Co | Itajotanketsushono seizohoho |
| JPS63159284A (en) * | 1986-12-24 | 1988-07-02 | Mitsubishi Electric Corp | Single crystal pulling up device |
| JPH06321699A (en) * | 1993-05-11 | 1994-11-22 | Murata Mfg Co Ltd | Production of barium strontium titanate single crystal |
| JP2005119955A (en) * | 2003-09-25 | 2005-05-12 | Canon Inc | Method for continuously manufacturing crystal silicon and apparatus therefor |
| JP2006143489A (en) * | 2004-11-16 | 2006-06-08 | Nippon Telegr & Teleph Corp <Ntt> | Crystal growth device and method |
| JP2009155182A (en) * | 2007-12-27 | 2009-07-16 | Nippon Telegr & Teleph Corp <Ntt> | Crystal growth method and apparatus therefor |
| JP2013184842A (en) * | 2012-03-07 | 2013-09-19 | Jx Nippon Mining & Metals Corp | Silicon single crystal manufacturing device and method of manufacturing the same |
| JP2013189354A (en) * | 2012-03-15 | 2013-09-26 | Jx Nippon Mining & Metals Corp | Apparatus and method for producing silicon single crystal |
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