JPH0631200B2 - Single crystal growth method - Google Patents
Single crystal growth methodInfo
- Publication number
- JPH0631200B2 JPH0631200B2 JP61132173A JP13217386A JPH0631200B2 JP H0631200 B2 JPH0631200 B2 JP H0631200B2 JP 61132173 A JP61132173 A JP 61132173A JP 13217386 A JP13217386 A JP 13217386A JP H0631200 B2 JPH0631200 B2 JP H0631200B2
- Authority
- JP
- Japan
- Prior art keywords
- crystal
- solid
- liquid interface
- single crystal
- growing
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
Description
【発明の詳細な説明】 ［産業上の利用分野］ 本発明は、光学素子や弾性表面波素子として有望なリチ
ウムテトラボレート（Ｌｉ２Ｂ４Ｏ７）の単結晶をチョ
クラルスキー法（以下、ＣＺ法という）により育成する
方法に関する。DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a Czochralski method (hereinafter, referred to as “Crystalski method”) in which a lithium tetraborate (Li 2 B 4 O 7 ) single crystal, which is promising as an optical element or a surface acoustic wave element, is used. The CZ method).
［従来の技術］ リチウムテトラボレート単結晶は、実用上、光の透過率
が高く、光の散乱を引き起こす巨視的な欠陥を含まない
ことが必要である。[Prior Art] A lithium tetraborate single crystal is required to have a high light transmittance in practical use and to be free from macroscopic defects that cause light scattering.
従来、ＣＺ法によりビスマス・ユーリタイト族化合物の
単結晶を育成する方法として、成長結晶の直径をＤ、こ
の結晶の固液界面の凸出高さをＨとしたときに、Ｈ／Ｄ
の値が−０．２〜０．２の範囲内になるように成長結晶
の回転速度を選ぶ方法が知られている（特公昭58-4951
7）。この方法によれば、結晶内の気泡の数を減少して
歩留りを高めることができる。Conventionally, as a method for growing a single crystal of a bismuth-eulytite group compound by the CZ method, when the diameter of the grown crystal is D and the protrusion height of the solid-liquid interface of this crystal is H, H / D
There is known a method of selecting the rotational speed of the grown crystal so that the value of is in the range of -0.2 to 0.2 (Japanese Patent Publication No. 58-4951).
7). According to this method, the number of bubbles in the crystal can be reduced and the yield can be increased.
しかし、この種の単結晶の高品質化は、Ｈ／Ｄの一要因
の制御だけでは気泡を減少させることはできても、完全
になくすことはできない。この点を改良した従来のＣＺ
法によるリチウムテトラボレート単結晶の育成方法は、
上記Ｈ／Ｄの値に加えて育成速度である種結晶の引上げ
速度や、成長結晶の固液界面直下の温度勾配を、単結晶
の高品質化の制御要因にしている。However, the improvement of the quality of this kind of single crystal can reduce the bubbles only by controlling one factor of H / D, but cannot completely eliminate it. Conventional CZ which improved this point
The method of growing a lithium tetraborate single crystal by the method is
In addition to the above H / D value, the pulling rate of the seed crystal, which is the growth rate, and the temperature gradient immediately below the solid-liquid interface of the growing crystal are control factors for improving the quality of the single crystal.
この改良した従来の育成方法は、単結晶の巨視的な欠陥
を完全になくすため、高純度の結晶原料を用いた上で、
育成速度を０．６ｍｍ／ｈｒ以下の極めて低い速度に抑
え、Ｈ／Ｄの値が０．０５〜０．１の範囲内になるよう
に成長結晶の回転速度を設定し、更に固液界面直下の温
度勾配を２０〜３０℃／ｃｍ程度にしていた。This improved conventional growing method completely eliminates macroscopic defects of a single crystal, therefore, after using a high-purity crystal raw material,
The growth rate is suppressed to an extremely low rate of 0.6 mm / hr or less, the rotation rate of the grown crystal is set so that the H / D value is in the range of 0.05 to 0.1, and the growth rate is set just below the solid-liquid interface. The temperature gradient was about 20 to 30 ° C./cm.
［発明が解決しようとする問題点］ しかし、従来の育成方法は巨視的な欠陥のない優れた単
結晶が得られる反面、その成長が極めて遅い問題点があ
った。この点を解消するために育成速度を高める試みが
なされた。しかし、単に育成速度を高めると、成長結晶
の固液界面から融液に吐き出された固溶ガスを主成分と
する不純物が融液内に十分に拡散されず、気泡になって
結晶内に取り込まれる不具合があった。[Problems to be Solved by the Invention] However, while the conventional growth method can obtain an excellent single crystal without macroscopic defects, it has a problem that its growth is extremely slow. Attempts have been made to increase the growth rate in order to eliminate this point. However, if the growth rate is simply increased, the impurities mainly composed of the solid solution gas discharged into the melt from the solid-liquid interface of the grown crystal are not sufficiently diffused into the melt and become bubbles and are taken into the crystal. There was a problem that was.
第３図に示すように、ここでＬｉ２Ｂ４Ｏ７結晶10の回
転速度Ｖ１が低い場合には、Ｌｉ２Ｂ４Ｏ７融液11は図
外の高周波加熱装置による熱対流12によって固液界面10
aを凸にするため、不純物13は固液界面10aの中心に寄せ
集められる。集まった不純物13は結晶コア部に気泡14と
なって残る。As shown in FIG. 3, when the rotation speed V 1 of the Li 2 B 4 O 7 crystal 10 is low, the Li 2 B 4 O 7 melt 11 is heated by a convection 12 by a high frequency heating device (not shown). Solid-liquid interface 10
In order to make a convex, the impurities 13 are gathered at the center of the solid-liquid interface 10a. The collected impurities 13 remain in the crystal core as bubbles 14.
また第４図に示すように、ここでＬｉ２Ｂ４Ｏ７結晶10
の回転速度Ｖ２が高い場合には、融液11の遠心力による
強制対流16が熱対流12に打ち勝って固液界面10aは平坦
又は凹になる。このため結晶中心の気泡はなくなるが、
不純物13が成長結晶10の引上げ方向に垂直に、言い換え
れば結晶10の半径方向に広がるドーナツ状の不透明リン
グ（ｏｐａｑｕｅｒｉｎｇ）17として残る問題点があっ
た。Further, as shown in FIG. 4, here, the Li 2 B 4 O 7 crystal 10 is used.
When the rotation speed V 2 is high, the forced convection 16 due to the centrifugal force of the melt 11 overcomes the thermal convection 12, and the solid-liquid interface 10a becomes flat or concave. Therefore, the bubbles at the center of the crystal disappear,
There is a problem that the impurity 13 remains as a donut-shaped opaque ring 17 that extends in a direction perpendicular to the pulling direction of the grown crystal 10, that is, in the radial direction of the crystal 10.
本発明の目的は、従来の２倍程度の高い育成速度で、結
晶内部に気泡、不透明リング、クラック等の巨視的な欠
陥のないリチウムテトラボレートの単結晶を育成する方
法を提供することにある。It is an object of the present invention to provide a method for growing a lithium tetraborate single crystal having a macroscopic defect such as a bubble, an opaque ring, or a crack inside the crystal at a growth rate that is twice as high as that of the conventional one. .
［問題点を解決するための手段］ 本発明者らは、巨視的な欠陥の一つである不透明リング
を微視的に観察したところ、そこには金属や半導体の結
晶に良く見られるセル（細胞）と呼ばれる小区域の結晶
が存在し、その中に微小な空洞を数多く発見した。光は
この空洞で乱反射し結晶を不透明にしていることが分っ
た。そしてこのセルは成長結晶の固液界面における不純
物の組成的過冷却（ｃｏｓｔｉｔｕｔｉｏｎａｌ ｓｕ
ｐｅｒｃｏｏｌｉｎｇ）によって成長することを見出
し、この組成的過冷却を解消することによって本発明を
完成するに至った。[Means for Solving Problems] The present inventors microscopically observed an opaque ring, which is one of macroscopic defects, and found that cells (commonly found in crystals of metal or semiconductor) There is a small area of crystals called cells, and we found many microscopic cavities in them. It was found that light diffusely reflected in this cavity, making the crystal opaque. Then, this cell has a compositional supercooling of impurities at the solid-liquid interface of the grown crystal.
The present invention has been completed by finding out that it grows by percooling) and eliminating this compositional supercooling.
本発明は、第１図のＬｉ２Ｂ４Ｏ７結晶10の形状におい
て、この結晶10の直径をＤ、この結晶10の固液界面10a
の凸出高さをＨとしたときに、Ｈ／Ｄの値が−０．１〜
０の範囲内になようにこの結晶の回転速度を選び、かつ
前記固液界面直下の温度勾配を５０℃／ｃｍ〜１００℃
／ｃｍの範囲内になるように加熱装置の鉛直方向位置を
選んだことを特徴とする。ここで、Ｈ／Ｄが負の値のと
きは固液界面10aが凹であり、零のときは固液界面10aが
平坦であることを表す。In the present invention, in the shape of the Li 2 B 4 O 7 crystal 10 in FIG. 1, the diameter of this crystal 10 is D, and the solid-liquid interface 10a of this crystal 10 is
When the protruding height of is H, the value of H / D is -0.1
The rotation speed of this crystal is selected so that it falls within the range of 0, and the temperature gradient immediately below the solid-liquid interface is 50 ° C./cm to 100 ° C.
It is characterized in that the vertical position of the heating device is selected so as to be within the range of / cm. Here, when H / D is a negative value, the solid-liquid interface 10a is concave, and when H / D is zero, the solid-liquid interface 10a is flat.
［作 用］ 第２図に示すように、Ｈ／Ｄの値が−０．１〜０の範囲
内になるようにＬｉ２Ｂ４Ｏ７結晶10の回転速度を選ぶ
と、回転遠心力による強制対流16が図外の加熱装置によ
る熱対流12に打ち勝って固液界面10aのＬｉ２Ｂ４Ｏ７
融液11をるつぼの壁面20に押しやる。そのため固液界面
10aから融液11に吐き出された不純物13もこの強制対流1
6に乗って固液界面10aから外方に飛ばされる。同時に成
長結晶10の固液界面直下の温度勾配を５０℃／ｃｍ〜１
００℃／ｃｍの範囲内になるようにすることにより、育
成速度を上げて不純物13を多量に発生させても、この固
液界面10aの組成的過冷却は防止される。[Operation] As shown in FIG. 2, when the rotation speed of the Li 2 B 4 O 7 crystal 10 is selected so that the H / D value falls within the range of −0.1 to 0, the rotation centrifugal force causes The forced convection 16 overcomes the thermal convection 12 due to the heating device (not shown), and Li 2 B 4 O 7 at the solid-liquid interface 10a
Push the melt 11 onto the wall 20 of the crucible. Therefore, the solid-liquid interface
Impurities 13 discharged from the melt 10a into the melt 11 also cause forced convection 1
It gets on board 6 and flies outward from the solid-liquid interface 10a. At the same time, the temperature gradient immediately below the solid-liquid interface of the grown crystal 10 is set to 50 ° C./cm to 1
By setting the temperature in the range of 00 ° C./cm, compositional supercooling of the solid-liquid interface 10a is prevented even if the growth rate is increased and a large amount of impurities 13 are generated.
Ｈ／Ｄの値が−０．１未満であると、固液界面10aの形
状が凹になり過ぎ、結晶10にクラックが入り易くなる。
またＨ／Ｄの値が０を越えるときは、熱対流の方が強制
対流より強いため、不純物が結晶の中心に集中し、コア
部に気泡が残存する。When the value of H / D is less than -0.1, the shape of the solid-liquid interface 10a becomes too concave, and the crystal 10 is likely to be cracked.
When the value of H / D exceeds 0, thermal convection is stronger than forced convection, so that impurities are concentrated in the center of the crystal and bubbles remain in the core.
また成長結晶の固液界面直下の温度勾配が５０℃／ｃｍ
未満であると、固液界面において組成的過冷却が生じ、
不透明リングが作られる。更に１００℃／ｃｍを越える
と、結晶体にクラックが入り易くなる。Further, the temperature gradient just below the solid-liquid interface of the grown crystal is 50 ° C / cm.
When it is less than 1, compositional supercooling occurs at the solid-liquid interface,
An opaque ring is created. Further, if it exceeds 100 ° C./cm, cracks easily occur in the crystal body.
［発明の効果］ 以上述べたように、本発明によれば、成長結晶の固液界
面の融液の流れを固液界面の外方に向うようにすること
により、気泡が結晶コア部に全く残らない。また成長結
晶の固液界面直下の温度勾配を高めることにより、この
固液界面から発生する不純物の量が増えてもこの固液界
面の組成的過冷却を防止して、不透明リングが形成され
ないため、巨視的な欠陥をつくることなく、育成速度を
上昇させることができる。[Effects of the Invention] As described above, according to the present invention, by causing the flow of the melt at the solid-liquid interface of the growing crystal to be directed to the outside of the solid-liquid interface, the bubbles are completely eliminated from the crystal core portion. It does not remain. In addition, by increasing the temperature gradient just below the solid-liquid interface of the grown crystal, compositional overcooling of this solid-liquid interface is prevented even if the amount of impurities generated from this solid-liquid interface increases, and an opaque ring is not formed. , The growth rate can be increased without creating macroscopic defects.
［実施例］ 次に本発明を実施例と比較例により詳しく説明する。[Examples] Next, the present invention will be described in detail with reference to Examples and Comparative Examples.
直径５０ｍｍの白金るつぼを用い、ＣＺ法により、直径
２５ｍｍのＬｉ２Ｂ４Ｏ７単結晶を育成した。熱電対を
用いて、固液界面の中心の鉛直方向の温度勾配ｄＴ／ｄ
ｚが次表の値になるように高周波加熱装置の鉛直方向位
置を選んだ。次いで引上げ軸に種結晶を取付け、この軸
を次表の育成速度で引上げながら、次表の回転速度で回
転させ、成長結晶のＨ／Ｄの値が次表の値になるように
した。Using a platinum crucible having a diameter of 50 mm, a Li 2 B 4 O 7 single crystal having a diameter of 25 mm was grown by the CZ method. Using a thermocouple, the temperature gradient dT / d in the vertical direction at the center of the solid-liquid interface
The vertical position of the high frequency heating device was selected so that z was the value in the following table. Then, a seed crystal was attached to the pulling shaft, and this shaft was rotated at the rotating speed shown in the following table while being pulled up at the growing speed shown in the following table so that the H / D value of the grown crystal would become the value shown in the following table.
育成条件と結晶体の目視による結果を次表に示す。The following table shows the growth conditions and the results of visual observation of crystals.
表から明らかなように、温度勾配又は結晶の回転速度の
一方又は双方を上げた中で実施例１〜３だけが、不透明
リング、結晶コア部の気泡及びクラックのない単結晶と
なった。 As is clear from the table, only one of Examples 1 to 3 was a single crystal having no opaque ring, bubbles in the crystal core portion, and cracks while increasing one or both of the temperature gradient and the rotation speed of the crystal.
第１図は本発明の単結晶の外形を示す要部正面図。 第２図は本発明の単結晶の育成状況を示す図。 第３図は従来例の単結晶コア部に気泡が出現する状況を
示す図。 第４図は従来例の単結晶内部に不透明リングが出現する
状況を示す図。 10……Ｌｉ２Ｂ４Ｏ７結晶、10a……固液界面、 11……Ｌｉ２Ｂ４Ｏ７融液、20……るつぼの壁面。FIG. 1 is a front view of an essential part showing the outer shape of a single crystal of the present invention. FIG. 2 is a view showing a growing state of the single crystal of the present invention. FIG. 3 is a view showing a situation in which bubbles appear in a single crystal core portion of a conventional example. FIG. 4 is a view showing a situation in which an opaque ring appears inside a single crystal of a conventional example. 10 …… Li 2 B 4 O 7 crystal, 10a …… solid-liquid interface, 11 …… Li 2 B 4 O 7 melt, 20 …… crucible wall.
───────────────────────────────────────────────────── フロントページの続き (56)参考文献 特開 昭61−127698（ＪＰ，Ａ) 特開 昭58−20797（ＪＰ，Ａ) ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-61-127698 (JP, A) JP-A-58-20797 (JP, A)
Claims (1)
ボレートの単結晶を育成する方法において、成長結晶の
直径をＤ、この結晶の固液界面の凸出高さをＨとしたと
きに、Ｈ／Ｄの値が−０．１〜０の範囲内になるように
この結晶の回転速度を選び、かつ前記固液界面直下の温
度勾配を５０℃／ｃｍ〜１００℃／ｃｍの範囲内になる
ように加熱装置の鉛直方向位置を選んだことを特徴とす
る単結晶の育成方法。1. A method for growing a single crystal of lithium tetraborate by the Czochralski method, where H / D, where D is the diameter of the grown crystal and H is the protrusion height of the solid-liquid interface of the crystal. The rotation speed of the crystal is selected so that the value of is within the range of -0.1 to 0, and the temperature gradient immediately below the solid-liquid interface is within the range of 50 ° C / cm to 100 ° C / cm. A method for growing a single crystal, characterized in that a vertical position of a heating device is selected.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP61132173A JPH0631200B2 (en) | 1986-06-07 | 1986-06-07 | Single crystal growth method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP61132173A JPH0631200B2 (en) | 1986-06-07 | 1986-06-07 | Single crystal growth method |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS62288195A JPS62288195A (en) | 1987-12-15 |
| JPH0631200B2 true JPH0631200B2 (en) | 1994-04-27 |
Family
ID=15075078
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP61132173A Expired - Lifetime JPH0631200B2 (en) | 1986-06-07 | 1986-06-07 | Single crystal growth method |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0631200B2 (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP4622326B2 (en) * | 2004-06-11 | 2011-02-02 | 日立化成工業株式会社 | Single crystal manufacturing method |
| DE102009024473B4 (en) * | 2009-06-10 | 2015-11-26 | Siltronic Ag | A method for pulling a single crystal of silicon and then produced single crystal |
| JP5574645B2 (en) * | 2009-09-07 | 2014-08-20 | Ｓｕｍｃｏ Ｔｅｃｈｘｉｖ株式会社 | Method for producing single crystal silicon |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS503270A (en) * | 1973-05-11 | 1975-01-14 |
-
1986
- 1986-06-07 JP JP61132173A patent/JPH0631200B2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| JPS62288195A (en) | 1987-12-15 |
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