JP6719718B2

JP6719718B2 - Si ingot crystal manufacturing method and manufacturing apparatus thereof

Info

Publication number: JP6719718B2
Application number: JP2018117476A
Authority: JP
Inventors: 中嶋　一雄; 一雄中嶋; 春正伊藤
Original assignee: Dai Ichi Kiden Co Ltd
Current assignee: Dai Ichi Kiden Co Ltd
Priority date: 2018-06-20
Filing date: 2018-06-20
Publication date: 2020-07-08
Anticipated expiration: 2038-06-20
Also published as: TW202001016A; TWI737997B; JP2019218245A

Description

本発明は、Ｓｉインゴット結晶の製造方法及びその製造装置に関する。 The present invention relates to a method for producing a Si ingot crystal and an apparatus for producing the same.

太陽電池を地球規模で本格的に普及させるためには、最も安全で環境にやさしく地球上に資源が豊富なＳｉ原料を用いて作製できる、Ｓｉインゴット結晶から切り出したＳｉ結晶ウェハーを用いた太陽電池を本格的に普及させる必要がある。そのためには、高効率の太陽電池を、安全なＳｉ資源を用いて低コストで生産できる、高品質で高均質な大面積のＳｉインゴット単結晶の製造技術を開発する必要がある。 Solar cells using Si crystal wafers cut from Si ingot crystals, which can be produced using the most safe, environmentally friendly, and resource-rich Si raw materials for the full-scale spread of solar cells on a global scale. Need to be popularized in earnest. For that purpose, it is necessary to develop a technology for producing a high-quality, highly-homogeneous large-area Si ingot single crystal capable of producing a high-efficiency solar cell using safe Si resources at a low cost.

また、各種電子装置に幅広く使用されている半導体デバイスをさらに安価に大量に普及させるためにも、安全なＳｉ資源を用いて低コストで生産できる、高品質で高均質な大面積のＳｉインゴット単結晶の製造技術を開発する必要がある。
本発明により得られるＳｉインゴット結晶の要件は、太陽電池結晶でも半導体結晶でも同じなので、本明細書では太陽電池を対象として説明を行う。 In order to popularize semiconductor devices widely used in various electronic devices at low cost in large quantities, high-quality, high-homogeneity, large-area Si ingots that can be produced at low cost using safe Si resources. It is necessary to develop crystal manufacturing technology.
Since the requirements for the Si ingot crystal obtained by the present invention are the same for the solar cell crystal and the semiconductor crystal, the description will be given for the solar cell in this specification.

（チョクラルスキー成長法）
現在、高効率太陽電池や半導体デバイス用のＳｉインゴット単結晶の大部分は、チョクラルスキー成長法（ＣＺ法）で作製されている。しかし、図９の（ａ）図に示すように、ＣＺ法では結晶成長時の成長界面は、Ｓｉ融液表面の上部にあり、成長界面を形成しているＳｉ融液は、主に表面から表面張力で盛り上がった薄く体積の小さな融液からなっている。このため、徴妙な融液内での温度分布や勾配の制御が難しい。 (Czochralski growth method)
Currently, most of the Si ingot single crystals for high efficiency solar cells and semiconductor devices are produced by the Czochralski growth method (CZ method). However, as shown in FIG. 9A, in the CZ method, the growth interface during crystal growth is located above the Si melt surface, and the Si melt forming the growth interface is mainly from the surface. It consists of a thin melt with a small volume that rises due to surface tension. For this reason, it is difficult to control the temperature distribution and the gradient in the melt that are unique.

また、結晶はこの融液の外に向かつて引き上げ成長され、成長時に発生する潜熱は、主に種結晶軸からの抜熱及びインゴット結晶表面からの放熱により取り除かれるため、成長界面が成長方向に向かって凹型になっており、歪みや結晶欠陥を結晶内部に引き込む形状になる。 Further, the crystal is pulled up and grown toward the outside of this melt, and the latent heat generated during the growth is removed mainly by the heat removal from the seed crystal axis and the heat radiation from the ingot crystal surface, so that the growth interface is oriented in the growth direction. The shape is concave toward the inside, and the shape is such that distortions and crystal defects are drawn into the crystal.

さらに、融液の対流が大きいため石英ルツボとＳｉ融液との反応が激しく、酸素がルツボからＳｉ融液に融解し成長結晶中の酸素濃度を上げる可能性がある。特に、成長界面がＳｉ融液表面の上部にあるため、常に急冷凝固に近い成長条件となり、成長界面で空孔や格子間原子が発生しやすい環境となる。 Further, since the convection of the melt is large, the reaction between the quartz crucible and the Si melt is vigorous, and oxygen may be melted from the crucible into the Si melt to increase the oxygen concentration in the grown crystal. In particular, since the growth interface is located above the surface of the Si melt, the growth conditions are always close to those of rapid solidification, which creates an environment in which vacancies and interstitial atoms are easily generated at the growth interface.

（キャスト成長法）
太陽電池用結晶の実用的な主要材料であるＳｉインゴット多結晶を、低コストで製造する技術であるキャスト成長法では、石英ルツボの内壁に離型剤（Ｓｉ₃Ｎ₄）を塗るため酸素濃度の上昇を抑制できる。 (Cast growth method)
In the cast growth method, which is a technology for manufacturing the Si ingot polycrystal, which is a practical main material for crystals for solar cells, at low cost, the inner wall of the quartz crucible is coated with a release agent (Si ₃ N ₄ ) so that the oxygen concentration is high. Can be suppressed.

しかし、図１０の（ａ）図に示すように、Ｓｉ結晶がルツボ壁に直接触れながらＳｉ融液から凝固するため、凝固成長時の膨張による歪みがＳｉインゴット結晶内部に生じ、多量の転位が発生し結晶品質を劣化させている。また、離型剤は、Ｆｅ（鉄）等の不純物を含むため、インゴット結晶の純度や電気的性質を劣化させている。 However, as shown in FIG. 10A, since the Si crystal solidifies from the Si melt while directly contacting the crucible wall, strain due to expansion during solidification growth occurs inside the Si ingot crystal, and a large amount of dislocations are generated. It occurs and deteriorates the crystal quality. Further, since the release agent contains impurities such as Fe (iron), it deteriorates the purity and electrical properties of the ingot crystal.

（従来の成長法の問題点）
発明者らは、ルツボを用いた太陽電池用Ｓｉインゴット結晶の成長に関する長年の研究により、ルツボ内に入れたＳｉ融液が凝固成長する時に起こる結晶の膨張により、結晶内に大きな歪みが発生し、多量の転位生成の原因になるため、ルツボに入れたＳｉ融液から結晶を成長させる時には、ルツボ壁に触れないで成長させる重要性に気づいた。 (Problems of the conventional growth method)
The inventors have conducted many years of research on the growth of a Si ingot crystal for a solar cell using a crucible, and a large strain occurs in the crystal due to the expansion of the crystal that occurs when the Si melt contained in the crucible solidifies and grows. However, since it causes the generation of a large amount of dislocations, when growing a crystal from the Si melt placed in the crucible, we have noticed the importance of growing the crystal without touching the crucible wall.

また、Ｓｉインゴット単結晶の成長技術であるＣＺ法は、結晶成長時の成長界面がＳｉ融液の上部にあり、主に表面から表面張力で盛り上がった薄く体積の小さな融液において結晶成長しているため、微妙な融液内での温度分布や勾配の制御が難しく、また成長界面が成長方向に向かって凹型になっており、歪を内部に引き込む形状であるといった課題があることが判った。 In the CZ method, which is a technique for growing a Si ingot single crystal, the growth interface during crystal growth is located above the Si melt, and crystal growth occurs mainly in a thin and small volume melt that rises from the surface due to surface tension. Since it is difficult to control the temperature distribution and gradient in the melt delicately, and the growth interface has a concave shape toward the growth direction, and it has been found that there is a problem that the shape draws strain into the inside. ..

さらに、融液の対流が大きく石英ルツボとＳｉ融液との反応が激しく、酸素がルツボからＳｉ融液に融解し成長結晶中の酸素濃度を上げるという課題もあった。これに加えて、成長界面がＳｉ融液表面の上部にあるため、常に急冷凝固に近い成長条件となり、成長界面で空孔や格子間原子が発生しやすい環境となる本質的な課題があった。 Further, there is a problem that the convection of the melt is large and the reaction between the quartz crucible and the Si melt is vigorous, and oxygen is melted from the crucible into the Si melt to increase the oxygen concentration in the grown crystal. In addition to this, since the growth interface is located above the surface of the Si melt, the growth conditions are always close to those of rapid solidification, and there is an essential problem that an environment in which vacancies and interstitial atoms are likely to occur at the growth interface. ..

（ＮＯＣ成長法）
これらの課題を解決するために、非特許文献１ないし４に示すような、ルツボ壁に触れないでＳｉインゴット結晶をＳｉ融液の内部で成長できるＮＯＣ成長法（Noncontact Crucible Method）を考案した。
図１０の（ｂ）図に示すように、このＮＯＣ成長法では、Ｓｉ融液内に設けた大きな低温領域を活用して、Ｓｉインゴット結晶をＳｉ融液内で成長させる。 (NOC growth method)
In order to solve these problems, the NOC growth method (Noncontact Crucible Method) which can grow a Si ingot crystal inside a Si melt without touching a crucible wall was devised as shown in Non-Patent Documents 1 to 4.
As shown in FIG. 10B, in this NOC growth method, a large low temperature region provided in the Si melt is utilized to grow a Si ingot crystal in the Si melt.

このため、Ｓｉ種結晶を用いて成長初期にＳｉ融液表面で成長核を作り、ここから融液表面で結晶を広げると同時に低温領域内部に向けて結晶を成長させる。インゴット結晶がある程度大きく融液内部で成長した後、インゴット結晶をさらに引き上げながら成長させる。 Therefore, a growth seed is formed on the surface of the Si melt at the initial stage of growth using the Si seed crystal, and the crystal is spread from there on the surface of the melt and at the same time the crystal is grown toward the inside of the low temperature region. After the ingot crystal has grown to a large extent inside the melt, the ingot crystal is grown while being further pulled up.

この時、Ｓｉ融液内部には低温領域が存在するため、引き上げ成長中も低温領域で結晶が成長し、融液内成長の状態は保存される。また成長界面も図９の（ｂ）図に示すように、成長方向に対して凸型をしているために、歪みや転位等の結晶欠陥を外部に吐き出す形状である。 At this time, since a low temperature region exists inside the Si melt, crystals grow in the low temperature region even during pulling growth, and the state of in-melt growth is preserved. Further, as shown in FIG. 9B, the growth interface has a convex shape with respect to the growth direction, and thus has a shape in which crystal defects such as strain and dislocation are discharged to the outside.

ＮＯＣ成長法の最大の特徴は、Ｓｉ融液内部に周りの融液温度よりも低い低温領域を意識的に設定することにある。この低温領域は、Ｓｉ融液内部でインゴット結晶をルツボ壁に触れないで成長させるためには不可欠の要素である。 The greatest feature of the NOC growth method is that the low temperature region lower than the surrounding melt temperature is intentionally set inside the Si melt. This low temperature region is an essential element for growing the ingot crystal inside the Si melt without touching the crucible wall.

（ＮＯＣ成長法と従来の成長法との対比）
太陽電池用のインゴット結晶の製造技術として、インゴット単結晶では高品質結晶が得られるＣＺ法が使われており、またインゴット多結晶では量産がし易く低コストのキャスト成長法が使われている。
ＣＺ法では、凝固成長時にルツボからの膨張歪みを受けるといった影響は無いが、インゴット結晶をＳｉ融液表面の表面張力を利用してＳｉ融液外へ引き上げながら成長する方法であるため、引き上げ速度によって決まる人工的な速度でインゴット結晶を成長している。 (Comparison between NOC growth method and conventional growth method)
As a technique for manufacturing an ingot crystal for a solar cell, a CZ method is used for an ingot single crystal to obtain a high quality crystal, and a low cost cast growth method is used for an ingot polycrystal because mass production is easy.
The CZ method has no effect of being subjected to expansion strain from the crucible during solidification growth, but since it is a method of growing while pulling the ingot crystal out of the Si melt by utilizing the surface tension of the surface of the Si melt, the pulling rate The ingot crystal is growing at an artificial speed determined by.

このため、成長界面は常に表面張力でＳｉ融液表面から持ち上がった位置に存在し、成長界面は成長方向に向かって凹型となり、また融液内の徴妙な温度分布の制御が難しくなる。また、このため、自然に結晶界面が融液内で移動して結晶が成長する融液内成長よりも熱歪みや結晶欠陥が結晶中に入り易いという弱点を持つ。 For this reason, the growth interface always exists at a position lifted from the surface of the Si melt by surface tension, the growth interface becomes concave toward the growth direction, and it becomes difficult to control the definite temperature distribution in the melt. For this reason, there is a weak point that thermal strains and crystal defects are more likely to enter the crystal than in-melt growth in which the crystal interface naturally moves in the melt to grow the crystal.

一方キャスト成長法は、ルツボの中で凝固する成長法であるため、Ｓｉ結晶が凝固する時の膨張歪みやルツボとの接触によるルツボ歪み、さらにはルツボ壁からの不純物拡散による汚染の影響を強く受け、転位等の結晶欠陥や不純物が結晶中に入りやすいという難点がある。
このため、Ｓｉ結晶で高い品質を得るには、ルツボ成長によるＳｉ結晶の各種歪みや、人工的に形成された成長界面による熱歪み等の影響を無くした成長技術の開発が必要となる。 On the other hand, since the cast growth method is a growth method that solidifies in the crucible, it is strongly affected by expansion strain when Si crystal solidifies, crucible strain due to contact with the crucible, and contamination by impurity diffusion from the crucible wall. However, there is a problem that crystal defects such as dislocations and dislocations and impurities easily enter the crystal.
Therefore, in order to obtain high quality with the Si crystal, it is necessary to develop a growth technique that eliminates the effects of various strains of the Si crystal due to crucible growth and thermal strain due to an artificially formed growth interface.

特開２０１１−２３０９５１号公報.Japanese Patent Laid-Open No. 2011-230951.

K. Nakajima et al, J. Crystal Growth, 344, 6-11（2012）.K. Nakajima et al, J. Crystal Growth, 344, 6-11 (2012). K. Nakajima et al, Jpn. J. Appl. Phys., 54, 015504-1-015504-7（2015）.K. Nakajima et al, Jpn. J. Appl. Phys., 54, 015504-1-015504-7 (2015). “Growth of Si ingots for solar cells with 33 cm diameter using a small crucible with 40 cm diameter by Noncontact crucible method”K.Nakajima, S.Ono, R.Murai, Y.Kaneko, F.Jay, Y.Veschetti, A.Jouini in PVSEC-25, BEXCO, Busan, Korea, November 15-20 (2015).“Growth of Si ingots for solar cells with 33 cm diameter using a small crucible with 40 cm diameter by Noncontact crucible method” K.Nakajima, S.Ono, R.Murai, Y.Kaneko, F.Jay, Y.Veschetti, A .Jouini in PVSEC-25, BEXCO, Busan, Korea, November 15-20 (2015). K. Nakajima, S. Ono, Y. Kaneko, R. Murai1, K. Shirasawa, T. Fukuda, H. Takato, S. Castellanos, M. A. Jensen, A. Youssef, T. Buonassisi, F. Jay, Y. Veschetti, and A. Jouini, “Applications based on novel effects derived to the Si bulk crystal growth inside Si melt without contact to crucible wall using noncontact crucible method”, in The 18th International Conference on Crystal Growth and Epitaxy (ICCGE-18), Nagoya, Japan, August 7-12 (2016).K. Nakajima, S. Ono, Y. Kaneko, R. Murai1, K. Shirasawa, T. Fukuda, H. Takato, S. Castellanos, MA Jensen, A. Youssef, T. Buonassisi, F. Jay, Y. Veschetti , and A. Jouini, “Applications based on novel effects derived to the Si bulk crystal growth inside Si melt without contact to crucible wall using noncontact crucible method”, in The 18th International Conference on Crystal Growth and Epitaxy (ICCGE-18), Nagoya , Japan, August 7-12 (2016).

このような課題を克服するＳｉインゴット結晶の成長方法としてＮＯＣ成長法を開発したが、このＮＯＣ成長法では、Ｓｉ融液内に大きく明確な低温領域を形成する必要があり、通常のルツボ底に低温材料を接触させて熱を取る技術では、Ｓｉ融液底部の温度が下がり、Ｓｉ融液の上部から成長することを基本とするＮＯＣ成長法には使いにくいことが判った。 The NOC growth method has been developed as a method for growing a Si ingot crystal to overcome such a problem. In this NOC growth method, it is necessary to form a large and clear low-temperature region in the Si melt, and a normal crucible bottom is formed. It has been found that the technique of bringing the low-temperature material into contact with the heat to lower the temperature of the bottom of the Si melt makes it difficult to use for the NOC growth method based on growing from the top of the Si melt.

太陽電池などの電子素子に用いるＳｉ結晶の高品質化には多くの研究がなされてきたが、最後まで残った重要課題がインゴット結晶内部の歪みの低減と歪みによる転位等の結晶欠陥の発生である。この歪みがインゴット結晶に与える影響は、一般的に考えられているよりもはるかに大きいことを見出し、この知見に基づき本発明のベースとなるＮＯＣ成長法が生まれた。 Although much research has been done to improve the quality of Si crystals used in electronic devices such as solar cells, the remaining important issue is to reduce the strain inside the ingot crystal and to generate crystal defects such as dislocation due to strain. is there. It was found that the influence of this strain on the ingot crystal is much larger than generally thought, and based on this finding, the NOC growth method which is the basis of the present invention was born.

本発明は、これまで述べた背景技術並びに本発明者らの知見を踏まえ、ＮＯＣ成長法を発展させて、低歪み、低転位、低酸素濃度の種々の形状のＳｉインゴット結晶が得られるＳｉインゴット結晶の製造方法及びＳｉインゴット結晶の製造装置を提供することを課題とする。 Based on the background art described above and the knowledge of the present inventors, the present invention develops the NOC growth method to obtain Si ingot crystals of various shapes with low strain, low dislocation, and low oxygen concentration. An object of the present invention is to provide a crystal manufacturing method and a Si ingot crystal manufacturing apparatus.

本発明の課題を解決するための手段は、次のとおりである。
（１）Ｓｉ融液を入れたルツボ底の中央部への入熱を阻害することにより、Ｓｉ融液の上部中央から下部中央にかけて周りの融液温度よりも低い低温領域をＳｉ融液内に形成し、低温領域を利用してＳｉインゴット結晶をルツボ壁に触れないようにＳｉ融液内で成長させることを特徴とするＮＯＣ成長法によるＳｉインゴット単結晶の製造方法。
（２）Ｓｉ融液を入れたルツボ底にヒータのような発熱体を配置するとともに、ルツボ底の中央部への発熱体からの入熱を阻害することにより、Ｓｉ融液の上部中央から下部中央にかけて周りの融液温度よりも低い低温領域をＳｉ融液内に形成し、低温領域を利用してＳｉインゴット結晶をルツボ壁に触れないようにＳｉ融液内で成長させることを特徴とするＮＯＣ成長法によるＳｉインゴット単結晶の製造方法。
（３）熱伝導度の悪い材料からなる板を、Ｓｉ融液を入れたルツボ底の中央部に配置して、ルツボ底の中央部への入熱を阻害し、Ｓｉ融液の上部中央から下部中央にかけて周りの融液温度よりも低い低温領域をＳｉ融液内に形成し、低温領域を利用してＳｉインゴット結晶をルツボ壁に触れないようにＳｉ融液内で成長させることを特徴とするＮＯＣ成長法によるＳｉインゴット単結晶の製造方法。
（４）ルツボを用いたＳｉインゴット結晶のＳｉ融液内において、熱伝導度の悪い材料からなる板と熱伝導度の良い材料からなる板とを幾何学的に平面的に組み合わせた構造の合成板を用意し、合成板を、Ｓｉ融液を入れたルツボ底に配置して、熱伝導度の悪い板によりルツボ底の中央部への入熱を阻害し、Ｓｉ融液の上部中央から下部中央にかけて周りの融液温度よりも低い低温領域を融液内に形成し、低温領域を利用してＳｉインゴット結晶をルツボ壁に触れないようにＳｉ融液内で成長させることを特徴とするＮＯＣ成長法によるＳｉインゴット単結晶の製造方法。
（５）Ｓｉ融液を入れたルツボ底の中央部への入熱を阻害することにより、Ｓｉ融液の上部中央から下部中央にかけて周りの融液温度よりも低い低温領域をＳｉ融液内に形成し、低温領域を利用してＳｉインゴット結晶をルツボ壁に触れないようにＳｉ融液内で成長することを特徴とするＮＯＣ成長法によるＳｉインゴット単結晶の製造方法であって、
融液内に設けた低温領域を利用して、Ｓｉ種結晶をＳｉ融液表面に接触させて結晶成長を開始した後、Ｓｉ融液表面に沿って又は融液内部に向かってインゴット結晶を成長し、成長したインゴット結晶の一部を融液内から融液と分離しない程度に引き上げる第１の工程と、再度融液内に残った結晶から、Ｓｉ融液の表面に沿って又は内部に向かってインゴット結晶を成長し、再度成長したインゴット結晶の一部を融液内からＳｉ融液と分離しない程度に引き上げる第２の工程とを、順次繰り返してインゴット結晶を成長させることを特徴とするＮＯＣ成長法によるＳｉインゴット単結晶の製造方法。
（６）Ｓｉインゴット結晶の引き上げ成長を開始した後に、上記Ｓｉ融液全体の温度を下げて低温領域を大きくして結晶を融液内部に大きく広げる際に、降温と引き上げを断続的又は連続的に行うことを特徴とする（１）ないし（５）のいずれかに記載のＮＯＣ成長法によるＳｉインゴット単結晶の製造方法。
（７）Ｓｉ種結晶に回転又は右左の繰り返し反復回転を与えることを特徴とする（５）又は（６）に記載のＮＯＣ成長法によるＳｉインゴット単結晶の製造方法。
（８）Ｓｉ融液を入れるルツボを囲む側面ヒータ及び底面ヒータを備え、底面ヒータとルツボ底部との間に、熱伝導度の悪い材料からなる板を、ルツボ底の中央部に配置してルツボ底の中央部への入熱を阻害し、Ｓｉ融液の上部中央から下部中央にかけて周りの融液温度よりも低い低温領域をＳｉ融液内に形成し、低温領域を利用してＳｉインゴット結晶をルツボ壁に触れないようにＳｉ融液内で成長させることを特徴とするＮＯＣ成長法によるＳｉインゴット単結晶の製造装置。
（９）Ｓｉ融液を入れるルツボを囲む側面ヒータ及び底面ヒータを備え、底面ヒータとルツボ底部との間に、熱伝導度の悪い材料からなる板と熱伝導度の良い材料からなる板を幾何学的に平面的に組み合わせた構造の合成板を配置して、熱伝導度の悪い材料からなる板によりルツボ底の中央部への入熱を阻害し、Ｓｉ融液の上部中央から下部中央にかけて周りの融液温度よりも低い低温領域をＳｉ融液内に形成し、低温領域を利用してＳｉインゴット結晶をルツボ壁に触れないようにＳｉ融液内で成長させることを特徴とするＮＯＣ成長法によるＳｉインゴット単結晶の製造装置。
（１０）上記熱伝導度の悪い材料の熱伝導度をＳｉの融点近傍で０．６Ｗ／ｍ・ｋ以下とし、上記熱伝導度の良い材料の熱伝導度をＳｉの融点近傍で２０−６０Ｗ／ｍ・ｋとすることを特徴とする（９）に記載のＮＯＣ成長法によるＳｉインゴット単結晶の製造装置。
（１１）上記熱伝導度の悪い材料の熱伝導度をＳｉの融点近傍で０．１５−０．５５Ｗ／ｍ・ｋとすることを特徴とする（１０）に記載のＮＯＣ成長法によるＳｉインゴット単結晶の製造装置。
（１２）上記熱伝導度の悪い材料からなる板の材質をグラファイト製の断熱材とし、上記熱伝導度の良い材料からなる板の材質をグラファイト材料とすることを特徴とする（９）に記載のＮＯＣ成長法によるＳｉインゴット単結晶の製造装置。
（１３）ルツボ底の中央部への入熱を阻害するためにルツボ底に配置する上記熱伝導度の悪い材料からなる板の形状を、円形、四角形、多角形、星形、線状又は惰円形とし、上記熱伝導度の良い材料からなる板をその周りに幾何学的に平面的に配置して組み合わせた構造の合成板としたことを特徴とする（９）ないし（１２）のいずれかに記載のＮＯＣ成長法によるＳｉインゴット単結晶の製造装置。
（１４）上記合成板の下側に冷却体を配置したことを特徴とする（１３）に記載のＮＯＣ成長法によるＳｉインゴット単結晶の製造装置。
（１５）Ｓｉ種結晶に回転又は右左の繰り返し反復回転を与える機構をさらに備えたことを特徴とする（８）ないし（１４）のいずれかに記載のＮＯＣ成長法によるＳｉインゴット単結晶の製造装置。
（１６）上記Ｓｉ融液を入れるルツボとこれを囲む側面ヒータ及び底面ヒータとの間に、該ルツボを囲むカーボン製熱保持具を備えたことを特徴とする（８）ないし（１５）のいずれかに記載のＮＯＣ成長法によるＳｉインゴット単結晶の製造装置。 Means for solving the problems of the present invention are as follows.
(1) By inhibiting the heat input to the central part of the crucible bottom containing the Si melt, a low temperature region lower than the surrounding melt temperature from the upper center to the lower center of the Si melt is contained in the Si melt. A method for producing a Si ingot single crystal by the NOC growth method , which comprises forming and growing a Si ingot crystal in a Si melt so as not to touch a crucible wall by utilizing a low temperature region.
(2) A heating element such as a heater is arranged at the bottom of the crucible containing the Si melt, and heat input from the heating element to the central portion of the crucible bottom is obstructed, so that the upper portion of the Si melt is lowered to the lower portion. A low temperature region lower than the surrounding melt temperature is formed in the Si melt toward the center, and the Si ingot crystal is grown in the Si melt by utilizing the low temperature region so as not to touch the crucible wall. A method for producing a Si ingot single crystal by the NOC growth method.
(3) A plate made of a material having poor thermal conductivity is placed in the center of the bottom of the crucible containing the Si melt to prevent heat input to the center of the bottom of the crucible. A low temperature region lower than the surrounding melt temperature is formed in the Si melt toward the center of the lower part, and the Si ingot crystal is grown in the Si melt using the low temperature region so as not to touch the crucible wall. A method for manufacturing a Si ingot single crystal by the NOC growth method.
(4) Synthesis of a structure in which a plate made of a material having poor thermal conductivity and a plate made of a material having good thermal conductivity are geometrically combined in a plane in a Si melt of a Si ingot crystal using a crucible Prepare a plate, place the synthetic plate on the bottom of the crucible containing the Si melt, and prevent the heat input to the center of the crucible bottom by the plate with poor thermal conductivity, and from the top center to the bottom of the Si melt. A NOC characterized in that a low temperature region lower than the surrounding melt temperature is formed in the melt toward the center, and a Si ingot crystal is grown in the Si melt so as not to touch the crucible wall by utilizing the low temperature region. A method for producing a Si ingot single crystal by a growth method.
(5) By inhibiting the heat input to the central part of the crucible bottom containing the Si melt, a low temperature region lower than the surrounding melt temperature from the upper center to the lower center of the Si melt is contained in the Si melt. A method for producing a Si ingot single crystal by the NOC growth method, which comprises forming and growing a Si ingot crystal in a Si melt so as not to touch a crucible wall by utilizing a low temperature region,
Using the low temperature region provided in the melt, the Si seed crystal is brought into contact with the Si melt surface to start crystal growth, and then an ingot crystal is grown along the Si melt surface or toward the inside of the melt. Then, the first step of pulling up a part of the grown ingot crystal from the melt to such an extent that it is not separated from the melt, and from the crystal remaining in the melt again, along the surface of the Si melt or toward the inside. NOC characterized in that the ingot crystal is grown by repeating a second step of growing an ingot crystal by a method of pulling a part of the regrown ingot crystal from the melt to a degree not separating from the Si melt. A method for producing a Si ingot single crystal by a growth method.
(6) After starting the pulling growth of the Si ingot crystal, when the temperature of the entire Si melt is lowered to enlarge the low temperature region and the crystal is widely spread inside the melt, the temperature drop and pulling are intermittent or continuous. The method for producing a Si ingot single crystal by the NOC growth method according to any one of (1) to (5), characterized in that
(7) The method for producing a Si ingot single crystal by the NOC growth method according to (5) or (6), wherein the Si seed crystal is subjected to rotation or right and left repeated repetitive rotation.
(8) A crucible is provided with a side heater and a bottom heater surrounding the crucible for containing the Si melt, and a plate made of a material having poor thermal conductivity is placed in the center of the crucible between the bottom heater and the bottom of the crucible. A low temperature region lower than the surrounding melt temperature is formed in the Si melt from the upper center to the lower center of the Si melt by inhibiting heat input to the center of the bottom, and the Si ingot crystal is utilized by utilizing the low temperature region. An apparatus for producing a Si ingot single crystal by the NOC growth method , characterized in that the Si is grown in a Si melt so as not to touch the crucible wall.
(9) A side heater and a bottom heater surrounding the crucible containing the Si melt are provided, and a plate made of a material having poor thermal conductivity and a plate made of a material having good thermal conductivity are geometrically provided between the bottom heater and the bottom of the crucible. By arranging a synthetic plate with a structurally planar combination, heat input to the center of the crucible bottom is blocked by a plate made of a material with poor thermal conductivity, and from the upper center to the lower center of the Si melt. NOC growth characterized in that a low-temperature region lower than the surrounding melt temperature is formed in the Si melt, and the low-temperature region is used to grow the Si ingot crystal in the Si melt without touching the crucible wall. Si ingot single crystal manufacturing apparatus by the method .
(10) The material having poor thermal conductivity has a thermal conductivity of 0.6 W/m·k or less near the melting point of Si, and the material having good thermal conductivity has a thermal conductivity of 20-60 W near the melting point of Si. /M·k, The apparatus for producing a Si ingot single crystal by the NOC growth method according to (9).
(11) The Si ingot produced by the NOC growth method according to (10), wherein the material having poor thermal conductivity has a thermal conductivity of 0.15-0.55 W/m·k near the melting point of Si. Single crystal manufacturing equipment.
(12) The material of the plate made of the material having poor thermal conductivity is a graphite heat insulating material, and the material of the plate made of the material having good thermal conductivity is graphite material. Si ingot single crystal production apparatus by NOC growth method of .
(13) The shape of the plate made of the material having poor thermal conductivity, which is arranged on the crucible bottom in order to inhibit heat input to the central portion of the crucible bottom, is a circle, a quadrangle, a polygon, a star, a line, or a coast. Any one of (9) to (12), characterized in that it is a circular shape, and is a composite plate having a structure in which plates made of the above-mentioned material having good thermal conductivity are geometrically arranged in a plane around them and combined. An apparatus for producing a Si ingot single crystal by the NOC growth method described in 1.
(14) The apparatus for producing a Si ingot single crystal by the NOC growth method according to (13), wherein a cooling body is arranged below the synthetic plate.
(15) The apparatus for producing a Si ingot single crystal by the NOC growth method according to any one of (8) to (14), further comprising a mechanism for rotating the Si seed crystal or rotating the Si seed crystal repeatedly. ..
(16) Any one of (8) to (15), characterized in that a carbon heat holder that surrounds the crucible is provided between the crucible containing the Si melt and the side heater and the bottom heater surrounding the crucible. An apparatus for producing a Si ingot single crystal by the NOC growth method described in 1.

本発明によれば、Ｓｉ融液を入れたルツボ底の中央部への入熱を阻害することにより、Ｓｉ融液の上部中央から下部中央にかけて周りの融液温度よりも低い低温領域をＳｉ融液内に形成し、該低温領域を利用してＳｉインゴット結晶をルツボ壁に触れないようにＳｉ融液内で成長させるため、低歪み、低転位、低酸素濃度の種々の形状のＳｉインゴット結晶の製造方法及びＳｉインゴット結晶の製造装置が実現できる。 According to the present invention, by inhibiting the heat input to the central part of the crucible bottom containing the Si melt, the low temperature region lower than the surrounding melt temperature from the upper center to the lower center of the Si melt is melted. Since it is formed in the liquid and the Si ingot crystal is grown in the Si melt so as not to touch the crucible wall by utilizing the low temperature region, the Si ingot crystal of various shapes with low strain, low dislocation and low oxygen concentration is formed. The manufacturing method and the Si ingot crystal manufacturing apparatus can be realized.

従来のＳｉインゴット結晶の製造装置と本発明に係るＳｉインゴット結晶の製造装置との、Ｓｉ融液への熱の流れの制御を示す比較説明図である。It is a comparison explanatory view which shows the control of the flow of the heat to Si melt of the conventional Si ingot crystal manufacturing apparatus and the Si ingot crystal manufacturing apparatus which concerns on this invention. Kyropoulos法とＮＯＣ成長法とのコンセプトの違いを説明する図面である。It is a drawing explaining the difference in concept between the Kyropoulos method and the NOC growth method. 中央の円形部分に熱伝導度の悪いグラファイト製の材料からなる板を配置し、その周りの円環部分に熱伝導度の良いグラファイト製の材料からなる板を幾何学的に平面的に組み合わせた構造の合成板の写真である。A plate made of a graphite material with poor thermal conductivity is placed in the central circular part, and a plate made of a graphite material with good thermal conductivity is geometrically combined in a plane around the annular part around it. It is a photograph of a synthetic plate of the structure. Ｓｉインゴット結晶の製造装置のルツボ底面に配置した合成板の一例を示す図面である。It is drawing which shows an example of the synthetic|combination board arrange|positioned at the crucible bottom face of the manufacturing apparatus of Si ingot crystal. ＮＯＣ成長法を用い、実施例１に基づいて成長した円形のｎ型大口径Ｓｉインゴット単結晶の写真である。3 is a photograph of a circular n-type large-diameter Si ingot single crystal grown based on Example 1 using a NOC growth method. ＮＯＣ成長法を用い、実施例２に基づいて成長した四角形のｎ型Ｓｉインゴット単結晶の写真である。5 is a photograph of a square n-type Si ingot single crystal grown based on Example 2 using the NOC growth method. 成長初期に、過冷却をかけながら結晶をＳｉ融液表面に沿って広げる成長をしている時期に、この広がった結晶を融液から急速に引き上げて成長を強制的に終了させ、その時点での成長界面の形状を示した写真である。At the beginning of the growth, while the crystal is growing while being supercooled along the surface of the Si melt, the spread crystal is rapidly pulled out from the melt to forcibly terminate the growth. 3 is a photograph showing the shape of the growth interface of the. 成長したインゴット結晶の最大直径と断熱材（熱伝導度の悪い材料からなる板）との直径の相関を示す図面である。It is drawing which shows the correlation of the maximum diameter of the grown ingot crystal and the diameter of a heat insulating material (plate made of a material with poor thermal conductivity). チョクラルスキー（ＣＺ）成長法とＮＯＣ成長法（Noncontact Crucible Method）との成長界面形状の比較図である。It is a comparison figure of the growth interface shape of Czochralski (CZ) growth method and NOC growth method (Noncontact Crucible Method). キャスト成長法とＮＯＣ成長法との成長形態の比較図である。It is a comparison figure of the growth form of a cast growth method and a NOC growth method.

（本発明の要旨）
本発明は、Ｓｉ融液内に大きな安定した低温領域を、制御しながら設定する方法に関するものである。
最も重要なポイントは、側面ヒータと底面ヒータからＳｉ融液内に流入する熱の流れを制御することにある。このために、熱伝導度の悪い材料からなる板（断熱板）を中央に配置し、熱伝導度の良い材料からなる板をその周りに配置し、これらを幾何学的に平面的に組み合わせた構造の合成板を活用し、Ｓｉ融液への熱の流れを制御して低温領域を設定することである。 (Summary of the present invention)
TECHNICAL FIELD The present invention relates to a method for controlling and setting a large stable low temperature region in a Si melt.
The most important point is to control the flow of heat flowing from the side heater and the bottom heater into the Si melt. For this purpose, a plate (insulating plate) made of a material with poor thermal conductivity is placed in the center, a plate made of a material with good thermal conductivity is placed around it, and these are combined geometrically in a plane. By utilizing the synthetic plate of the structure, the flow of heat to the Si melt is controlled to set the low temperature region.

図１の（ｂ）図に示すように、この合成板をルツボ底に配置して、熱伝導度の悪い材料からなる板により、底面ヒータからルツボ底の中央部を通してＳｉ融液内部へ熱が流入する（入熱）ことを阻害し、熱伝導度の良い材料からなる板を敷いたルツボ底の周囲部では入熱を促進させる。
熱伝導度の悪い材料からなる板と熱伝導度の良い材料からなる板とは、幾何学的に平面的に組み合わせた構造の合成板を構成している。 As shown in FIG. 1(b), the synthetic plate is placed at the bottom of the crucible, and a plate made of a material having poor thermal conductivity allows heat to flow from the bottom heater to the inside of the Si melt through the central portion of the crucible bottom. Inflow (heat input) is obstructed, and heat input is promoted at the periphery of the crucible bottom covered with a plate made of a material having good thermal conductivity.
A plate made of a material having a poor thermal conductivity and a plate made of a material having a good thermal conductivity constitute a synthetic plate having a structure in which they are geometrically combined in a plane.

これにより、Ｓｉ融液内の上部中央から下部中央にかけて大きな低温領域を形成できる。この合成板の構造には種々の形状・形態が考えられ、低温領域のサイズを制御するために使い分けることができる。
比較のために、このような合成板がない通常の成長炉の熱の流れを、図１の（ａ）図に示す。 As a result, a large low temperature region can be formed from the upper center to the lower center in the Si melt. Various shapes and forms can be considered for the structure of the composite plate, and the composite plate can be selectively used to control the size of the low temperature region.
For comparison, the heat flow of a normal growth furnace without such a synthetic plate is shown in FIG.

この低温領域の形成を行うためにルツボ底を冷却すると、Ｓｉ融液の下部温度が下がりデンドライト結晶がルツボ底面から発生する。このため、低温領域の設定には、一般に使われている冷却手法を用いることはできない。Ｓｉ融液内に低温領域を形成する手法に対する本発明の主眼は、ルツボ下部中央からの入熱を阻害し、Ｓｉ融液中央部の温度を下げる点である。 When the crucible bottom is cooled in order to form this low temperature region, the lower temperature of the Si melt lowers and dendrite crystals are generated from the crucible bottom surface. Therefore, a commonly used cooling method cannot be used to set the low temperature region. The main object of the present invention for the method of forming a low temperature region in the Si melt is to inhibit heat input from the lower center of the crucible and lower the temperature of the Si melt center.

（本発明に近い従来例の特徴と問題点）
キャスト成長法の一つとしてデンドライト結晶利用成長法で、デンドライト結晶をルツボ底面に沿って一方向に配列するために、断熱材料の組み合わせ板が報告されている（特許文献１）。この方法ではインゴット多結晶がルツボ底面から成長を開始しメルトの上部へ向かって成長が進行するので、本発明のベースとなる成長法であるＮＯＣ成長法とは温度分布や構成が逆になっている。 (Characteristics and Problems of Conventional Example Close to the Present Invention)
As one of the cast growth methods, a growth method using a dendrite crystal has been reported as a combination plate of heat insulating materials for arranging the dendrite crystals in one direction along the bottom surface of the crucible (Patent Document 1). In this method, the ingot polycrystal starts to grow from the bottom surface of the crucible and progresses toward the upper part of the melt. Therefore, the temperature distribution and structure are reversed from those of the NOC growth method which is the growth method which is the base of the present invention. There is.

すなわち、デンドライト結晶利用成長法では、Ｓｉ融液の下部の温度が上部の温度よりも低く設定されている。デンドライト結晶をルツボ底面の端部から底面に沿って一方向に発現させるために、Ｓｉ融液底部の端部位置の局所領域近傍の過冷却度を大きくする必要がある。このため、この端部の局所部分に熱伝導度の良い材料よりなる板を配置してルツボ内の融液から外部への熱の逃げを促進し、ルツボ底面の中央には熱伝導度の悪い材料を配置してメルトから熱が逃げないようにしている。 That is, in the dendrite crystal utilization growth method, the temperature of the lower portion of the Si melt is set lower than the temperature of the upper portion. In order to develop the dendrite crystals in one direction from the end of the bottom of the crucible along the bottom, it is necessary to increase the degree of supercooling near the local region at the end of the Si melt bottom. For this reason, a plate made of a material with good thermal conductivity is arranged at a local portion of this end portion to promote heat escape from the melt in the crucible to the outside, and a poor thermal conductivity at the center of the bottom surface of the crucible. The material is placed so that heat does not escape from the melt.

本発明とは異なり、ルツボ底面の中央部では、融液からの熱の逃げを抑制することに主眼を置いており、これによりメルト中央部分の温度を高く保っている。このため、この配置ではＳｉ融液内に低温領域はできない。
一方本発明では、Ｓｉ融液の下部の温度が上部の温度よりも高く設定されている状態を基本にしている。この状態で、Ｓｉ融液内部の上部中央から底部にかけて、周りの融液温度よりはるかに低温になっている低温領域を設けるために、熱伝導度の悪い断熱材料によりルツボ底の中央部への入熱を阻害し、その周りを逆に熱伝導度の良い材料で囲い、熱が融液中に入り易いように工夫している。 Unlike the present invention, the central part of the bottom surface of the crucible is focused on suppressing the escape of heat from the melt, whereby the temperature of the central part of the melt is kept high. Therefore, in this arrangement, a low temperature region cannot be formed in the Si melt.
On the other hand, the present invention is based on the condition that the lower temperature of the Si melt is set higher than the upper temperature. In this state, in order to provide a low temperature region that is much lower than the surrounding melt temperature from the upper center to the bottom inside the Si melt, a heat insulating material with poor thermal conductivity is used to connect the center of the crucible bottom. The heat input is obstructed, and the area around it is surrounded by a material with good thermal conductivity so that heat easily enters the melt.

本発明では、Ｓｉ融液内部の上部中央から底部にかけて、周りの融液温度よりはるかに低温になっている低温領域を設けるために、熱伝導度の悪い断熱材料によりルツボ底の中央部への入熱を阻害し、その周りには逆に熱伝導度の良い材料で囲って、ルツボ内のＳｉ融液への入熱を促進する発想を用いる。これによりＳｉ融液内部の上部中央から下部中央にかけて大きな低温領域が形成できる。 In the present invention, in order to provide a low temperature region, which is much lower than the surrounding melt temperature, from the center to the bottom of the inside of the Si melt, a heat insulating material having poor thermal conductivity is applied to the center of the crucible bottom. The idea is to inhibit heat input, and conversely surround it with a material having good thermal conductivity to promote heat input to the Si melt in the crucible. Thereby, a large low temperature region can be formed from the upper center to the lower center inside the Si melt.

融液内成長法としてKyropoulos法と呼ばれる方法がある。この方法と本発明に係るＮＯＣ成長法との違いを図２で説明する。
図２の（ａ）図に示すように、Kyropoulos法では、基本的には凝固潜熱は主に種結晶を固定した軸を通して放熱される。同時にルツボ底面からも放熱が行われ、熱はＳｉ融液の底部から外に流れる方向になるため、融液内には大きな低温領域を作ることができない。 There is a method called Kyropoulos method as a melt growth method. The difference between this method and the NOC growth method according to the present invention will be described with reference to FIG.
As shown in FIG. 2A, in the Kyropoulos method, basically, the latent heat of solidification is mainly radiated through the shaft on which the seed crystal is fixed. At the same time, heat is also radiated from the bottom surface of the crucible, and heat flows in a direction from the bottom of the Si melt to the outside, so that a large low temperature region cannot be created in the melt.

図２の（ｂ）図に示すように、本発明に係るＮＯＣ成長法では、ルツボ底面中央からの熱の流入を阻害し、ルツボ底面の周りからの熱の流入を強めるためＳｉ融液の中央に大きな低温領域を形成できる。
このように低温領域を作るための基本コンセプトが異なり、Kyropoulos法には融液内に意識的に低温領域を設定する発想はなく、十分な大きさの低温領域を融液内に設定することができない。このため、Ｓｉ結晶のような潜熱の大きな結晶の成長には無理があり、Ｓｉ融液内でルツボ壁に触れないでＳｉインゴット結晶を成長した報告は一切無い。 As shown in FIG. 2(b), in the NOC growth method according to the present invention, in order to prevent heat from flowing in from the center of the bottom of the crucible and strengthen heat inflow from around the bottom of the crucible, the center of the Si melt is increased. A large low temperature region can be formed.
In this way, the basic concept for creating a low-temperature region is different, and the Kyropoulos method has no idea of intentionally setting a low-temperature region in the melt, and it is possible to set a sufficiently low-temperature region in the melt. Can not. Therefore, it is impossible to grow a crystal having large latent heat such as a Si crystal, and there is no report of growing a Si ingot crystal in the Si melt without touching the crucible wall.

それに比べて本発明では、明確で大きな低温領域を熱伝導度が異なる材料からなる板を組み合わせた構造の合成板を活用して実現できており、図２の（ｂ）図に示すようなＳｉインゴット単結晶が極めて容易に成長でき、その効果は抜群である。 On the contrary, in the present invention, a clear and large low temperature region can be realized by utilizing a synthetic plate having a structure in which plates made of materials having different thermal conductivities are combined, and as shown in FIG. An ingot single crystal can be grown extremely easily, and its effect is outstanding.

（本発明の実施形態）
Ｓｉ融液内の上部中央に大きな低温領域を形成する技術として、熱伝導度の悪い材料からなる板と熱伝導度の良い材料からなる板を幾何学的に平面的に組み合わせた構造の合成板を用意し、この板をルツボ底に配置して、熱伝導度の悪い材料からなる板によりルツボ底の中央部への入熱を阻害し、Ｓｉ融液の上部中央から下部中央にかけて周りの融液温度よりも低い低温領域を融液内に形成する方法が最も効果的であることを見出した。 (Embodiment of the present invention)
As a technique for forming a large low temperature region in the upper center of the Si melt, a synthetic plate having a structure in which a plate made of a material having poor thermal conductivity and a plate made of a material having good thermal conductivity are geometrically combined in a plane. This plate is placed on the bottom of the crucible, and the plate made of a material with poor thermal conductivity inhibits heat input to the center of the crucible bottom. It was found that the method of forming a low temperature region lower than the liquid temperature in the melt is the most effective.

この合成板には種々の形状が考えられ、目的に応じて使い分ける。
中央の円形部分に熱伝導度の悪いグラファイト製の材料からなる板と、その周りの円環部分に熱伝導度の良いグラファイト製の材料からなる板とを幾何学的に平面的に組み合わせた構造の合成板の例を図３に示す。 Various shapes are conceivable for this composite plate, and they are used properly according to the purpose.
A structure in which a plate made of a graphite material with poor thermal conductivity in the central circular part and a plate made of a graphite material with good thermal conductivity in the surrounding ring part are combined geometrically in a plane. An example of the composite plate of is shown in FIG.

この実施形態では、中央に円形の熱伝導度の悪い材料からなる板を配置したが、この板の形状が四角形、多角形、星形、線状、楕円形などになっていてもよく、成長させたいインゴット結晶の形状に合わせて自在に選ぶことが可能である。 In this embodiment, a circular plate made of a material having poor thermal conductivity is arranged in the center, but the plate may have a rectangular shape, a polygonal shape, a star shape, a linear shape, an elliptical shape, or the like. It can be freely selected according to the shape of the ingot crystal to be made.

Ｓｉインゴット結晶の製造装置のルツボ底面に配置した合成板の一例を図４に示す。この合成板をルツボ底面に沿って配置すると、Ｓｉ融液下部中央への入熱を阻害でき、さらにルツボ壁近くのＳｉ融液への入熱を促進できるため、Ｓｉ融液内に大きな低温領域を安定して設けることができる。
ルツボの大きさによっては、この合成板を通した入熱を効果的に障害する目的で、この合成板の下側に冷却体を配置してもよい。
冷却体としては、良導体の材料からなる円柱棒やその中を水冷した円柱管などが考えられるが、この限りではない。 FIG. 4 shows an example of a synthetic plate arranged on the bottom surface of the crucible of the Si ingot crystal manufacturing apparatus. If this synthetic plate is placed along the bottom surface of the crucible, heat input to the lower center of the Si melt can be inhibited and heat input to the Si melt near the crucible wall can be promoted. Can be stably provided.
Depending on the size of the crucible, a cooling body may be arranged below the synthetic plate in order to effectively impede heat input through the synthetic plate.
As the cooling body, a cylindrical rod made of a material of a good conductor or a cylindrical pipe having water cooled therein can be considered, but it is not limited to this.

このようにしてＳｉ融液内に形成された低温領域を用いて、次に示すようにＮＯＣ成長法を用いて大きなインゴット結晶を成長する。
Ｓｉ融液は、融液上部よりも下部の方が高温となる温度分布を有するようにし、Ｓｉ種結晶を用いてＳｉ融液表面に核形成させ、まずここからＳｉ融液の表面に沿って結晶を低温領域内で大きく広げる。 Using the low temperature region thus formed in the Si melt, a large ingot crystal is grown by the NOC growth method as shown below.
The Si melt has a temperature distribution in which the lower part has a higher temperature than the upper part of the melt and nucleates on the surface of the Si melt using a Si seed crystal. The crystal spreads greatly in the low temperature region.

Ｓｉ融液全体の温度をＳｉの融点以下に大きく下げて低温領域を大きくするほど、大きな結晶が融液表面に沿って成長できる。
この時、低温領域に内部に向かってもインゴット結晶が成長するため、成長界面は下に凸型を有するようになる。 Larger crystals can be grown along the surface of the melt as the temperature of the entire Si melt is greatly lowered below the melting point of Si to enlarge the low temperature region.
At this time, since the ingot crystal grows inward in the low temperature region, the growth interface has a downward convex shape.

さらに、Ｓｉ融液全体の温度を下げながら、成長したインゴット結晶の一部を融液内から融液と分離しない程度に引き上げ、再度融液内に残った結晶からＳｉ融液の表面に沿って又は内部に向かってインゴット結晶を成長し、再度成長したインゴット結晶の一部を融液内から融液と分離しない程度に引き上げる、といった手順を繰り返してインゴット結晶を成長する。 Further, while lowering the temperature of the entire Si melt, a part of the grown ingot crystal is pulled up from the melt to such an extent that it is not separated from the melt, and the crystals remaining in the melt are re-allocated along the surface of the Si melt. Alternatively, the ingot crystal is grown by repeating the procedure of growing the ingot crystal toward the inside and pulling a part of the regrown ingot crystal from the inside of the melt to such an extent that it is not separated from the melt.

引き上げ成長を開始した時は、Ｓｉ融液の冷却と引き上げを断続的に行ってもよく、又は連続的に行つてもよい。
実際の結晶成長の状況に合わせて、目的とするインゴット結晶のサイズや形状に応じて適宜決めればよい。 When the pull-up growth is started, the cooling and pulling of the Si melt may be performed intermittently or continuously.
It may be appropriately determined according to the size and shape of the target ingot crystal in accordance with the actual state of crystal growth.

（低温領域の形成）
Ｓｉ融液をルツボに入れてＳｉインゴット結晶を製造する際に、まずＳｉ融液の上部中央から下部にかけて、その周囲の融液温度よりも低く、より大きな過冷却度を有する、円形、四角形、多角形、星形、線状、楕円形の低温領域を設ける。これによりＳｉ結晶を融液内成長させる際に、ルツボ壁に触れないで結晶成長が可能になる。しかも、この低温領域のサイズを自在に制御することにより、成長するインゴット結晶の形状・大きさを自在に制御できるようになる。 (Formation of low temperature region)
When manufacturing a Si ingot crystal by putting the Si melt in a crucible, first from the upper center to the lower part of the Si melt, lower than the melt temperature of its surroundings, having a greater degree of supercooling, circular, square, Provide polygonal, star-shaped, linear, and elliptical low-temperature regions. This enables crystal growth without touching the crucible wall when growing the Si crystal in the melt. Moreover, by freely controlling the size of this low temperature region, the shape and size of the growing ingot crystal can be freely controlled.

このような低温領域をＳｉ融液内に設けるため、熱伝導度の異なる材料からなる板を、幾何学的に平面的に組み合わせた構造の合成板を用いる。具体的には、ルツボ底面に円形、四角形、多角形、星形、線状、楕円形の熱伝導度の悪い材料からなる板を配置する。同時にこの熱伝導度の悪い材料の板を取り囲むように、熱伝導度の良い材料からなる板を配置する。
ここで、熱伝導度の悪い材料の熱伝導度を、Ｓｉの融点近傍で０．６Ｗ／ｍ・ｋ以下とする。さらに好ましくは、０．１５−０．５５Ｗ／ｍ・ｋとする。
また、熱伝導度の良い材料の熱伝導度を、Ｓｉの融点近傍で２０−６０Ｗ／ｍ・ｋとする。 In order to provide such a low temperature region in the Si melt, a synthetic plate having a structure in which plates made of materials having different thermal conductivities are geometrically combined in a plane is used. Specifically, a plate made of a material having a poor thermal conductivity, such as a circle, a quadrangle, a polygon, a star, a line, or an ellipse, is arranged on the bottom surface of the crucible. At the same time, a plate made of a material having good thermal conductivity is arranged so as to surround the plate made of a material having poor thermal conductivity.
Here, the thermal conductivity of the material having poor thermal conductivity is set to 0.6 W/m·k or less near the melting point of Si. More preferably, it is 0.15-0.55 W/m·k.
The thermal conductivity of a material having good thermal conductivity is set to 20-60 W/m·k near the melting point of Si.

この合成板により、Ｓｉ融液底部への入熱を局所的に制御（ルツボ底中央部では入熱を阻害し、ルツボ底の周囲では入熱を促進）し、Ｓｉ融液内に目的のサイズの低温領域を効果的に設ける。
低温領域を大きくするには、融液点下に融液を降温し、低温領域内の過冷却度を増す必要がある。過冷却度は８０ｋ以上付けることが可能である。 This synthetic plate locally controls the heat input to the bottom of the Si melt (blocks the heat input at the center of the crucible bottom and promotes the heat input at the periphery of the crucible bottom) to achieve the desired size in the Si melt. Effectively provides a low temperature region.
In order to increase the low temperature region, it is necessary to lower the temperature of the melt below the melt point to increase the degree of supercooling in the low temperature region. The degree of supercooling can be 80 k or more.

この過冷却度の大きさを自在に制御することにより、低温領域のサイズや温度勾配も変化し、この中で成長できるインゴット結晶の大きさ・形状も変わってくる。
本発明を活用した、具体的なｎ型Ｓｉインゴット単結晶の成長の実施例を実施例１及び実施例２として以下に示す。 By freely controlling the magnitude of this supercooling degree, the size and temperature gradient of the low temperature region also change, and the size and shape of the ingot crystal that can grow in this change.
Examples of specific growth of an n-type Si ingot single crystal utilizing the present invention are shown below as Example 1 and Example 2.

（実施例１）
実施例１では、ルツボの大きさを５０ｃｍ径とし、ドーパントとしてＰを加えたＳｉ原料の重さを３５．３２ｋｇとする。この時、Ｓｉ融液の深さは７ｃｍとなる。
窒化珪素粉未を塗布しない石英ルツボにＳｉ原料を充填し、インゴット結晶の製造装置内の所定の位置にセットする。
この時、ルツボ底の下側には、直径４０ｃｍのグラファィト製の熱伝導度の悪い円形の板とその周りに熱伝導度の良い材料の円環状の板を組み合わせた構造の合成板（直径６０ｃｍ）をあらかじめ配置しておく。 (Example 1)
In Example 1, the crucible size was 50 cm in diameter, and the weight of the Si raw material to which P was added as a dopant was 35.32 kg. At this time, the depth of the Si melt is 7 cm.
A quartz crucible not coated with silicon nitride powder is filled with a Si raw material and set at a predetermined position in an ingot crystal manufacturing apparatus.
At this time, under the bottom of the crucible, a composite plate (diameter 60 cm, which has a structure in which a circular plate made of graphite with a diameter of 40 cm and having poor thermal conductivity and an annular plate of a material having good thermal conductivity are combined around the plate. ) Is placed in advance.

その後、アルゴン(Ａｒ)ガス雰囲気中で約１４５０℃に昇温し、Ｓｉ原料を完全に融解させた。次に、ルツボの温度をＳｉの融点温度以下１．５ｋまで下げ、Ｓｉ種結晶をＳｉ融液表面に持ち浸して接触させて種づけをした。
引き上げ成長を開始する前に、融液全体の温度を下げて低温領域を大きくし、結晶を融液表面に沿って大きく広げた。 After that, the temperature was raised to about 1450° C. in an argon (Ar) gas atmosphere to completely melt the Si raw material. Next, the temperature of the crucible was lowered to 1.5 k or lower than the melting point temperature of Si, and the Si seed crystal was immersed in and brought into contact with the surface of the Si melt for seeding.
Before the pull-up growth was started, the temperature of the entire melt was lowered to enlarge the low temperature region, and the crystals were spread widely along the surface of the melt.

この後、Ｓｉ融液の温度を０．２ｍｍ／ｍｉｎの冷却速度で下げながら、０．１−０．５ｍｍ／ｍｉｎの引き上げ速度で種結晶からインゴット結晶を継続して成長させた。
この時、降温と引き上げを連続的に行ったり、断続的に行ったりすることにより、インゴット結晶のサイズを調整した。 Then, while the temperature of the Si melt was lowered at a cooling rate of 0.2 mm/min, an ingot crystal was continuously grown from the seed crystal at a pulling rate of 0.1-0.5 mm/min.
At this time, the size of the ingot crystal was adjusted by continuously lowering and raising the temperature or intermittently.

また、この成長では、冷却を中断するプロセスをある周期で導入した。種結晶とルツボは同軸方向に回転して、対流の発生を抑制した。成長中は観察窓を通してインゴット結晶の端を常に観察し、インゴット結晶がルツボ壁に触れないようにした。
温度降下幅は５５．１ｋであり、全成長時間は６３０分となった。 In addition, in this growth, a process of interrupting cooling was introduced in a certain cycle. The seed crystal and the crucible rotated coaxially to suppress the generation of convection. During growth, the edge of the ingot crystal was constantly observed through the observation window so that the ingot crystal did not touch the crucible wall.
The temperature drop width was 55.1 k, and the total growth time was 630 minutes.

インゴット結晶が所定の大きさになった時、成長したインゴット結晶を融液から分離するために１０ｍｍ／ｍｉｎの高速で引き上げ、成長を終了した。この時、ルツボを引き下げて成長したインゴット結晶が融液から分離することを助けた。 When the ingot crystal became a predetermined size, the grown ingot crystal was pulled up at a high speed of 10 mm/min to separate it from the melt, and the growth was completed. At this time, the ingot crystal grown by pulling down the crucible helped to separate from the melt.

成長したＳｉインゴット単結晶の写真を図５に示す。Ｓｉインゴット単結晶は、円錐形をしており、重量は２２．７ｋｇ、厚さは１３．０ｃｍ、最大直径は４５．０ｃｍ、直径比は０．９であった。これにより、ルツボ径（５０ｃｍ）の９０％の口径のインゴット単結晶が成長できた。 A photograph of the grown Si ingot single crystal is shown in FIG. The Si ingot single crystal had a conical shape, the weight was 22.7 kg, the thickness was 13.0 cm, the maximum diameter was 45.0 cm, and the diameter ratio was 0.9. As a result, an ingot single crystal having a diameter of 90% of the crucible diameter (50 cm) could be grown.

（実施例２）
実施例２では、ルツボの大きさを１５ｃｍ径とし、ドーパントとしてＰを加えたＳｉ原料の重さを１．６６ｋｇとするとこの時、Ｓｉ融液の深さは４ｃｍとなる。
窒化珪素粉末を塗布しない石英ルツボにＳｉ原料を充填し、インゴット結晶の製造装置内の所定の位置にセットする。この時、ルツボ底の下側には、直径１０ｃｍのグラファイト製の熱伝導度の悪い円形の板とその周りに熱伝導度の良い材料の円環状の板を組み合わせた構造の合成板(直径２０ｃｍ)をあらかじめ配置しておく。 (Example 2)
In Example 2, assuming that the crucible has a diameter of 15 cm and the weight of the Si raw material added with P as a dopant is 1.66 kg, the depth of the Si melt becomes 4 cm.
A quartz crucible to which silicon nitride powder is not applied is filled with a Si raw material and set at a predetermined position in an ingot crystal manufacturing apparatus. At this time, below the bottom of the crucible, a composite plate (diameter 20 cm, which has a structure in which a circular plate made of graphite having a diameter of 10 cm and having poor thermal conductivity and an annular plate made of a material having good thermal conductivity are combined therearound. ) Is placed in advance.

その後、Ａｒガス雰囲気中で約１４５０℃に昇温し、Ｓｉ原料を完全に融解させた。
次に、ルツボの温度をＳｉの融点温度以下１．５ｋまで下げ、Ｓｉ種結晶をＳｉ融液表面に持ち浸して接触させ種づけする。
この後、１ｍｍ／ｍｉｎの引き上げ速度で５−８ｍｍ径の細い種結晶を成長しネッキングを行う。成長した種結晶が約１４ｃｍの長さになった時、引き上げ成長を終了する。 After that, the temperature was raised to about 1450° C. in an Ar gas atmosphere to completely melt the Si raw material.
Next, the temperature of the crucible is lowered to 1.5 k or lower than the melting point of Si, and the Si seed crystal is immersed in and brought into contact with the surface of the Si melt for seeding.
Thereafter, a thin seed crystal having a diameter of 5-8 mm is grown at a pulling rate of 1 mm/min to perform necking. When the grown seed crystal has a length of about 14 cm, the pulling growth is terminated.

この後、０．２ｋ／ｍｉｎの降温速度で融液を冷却し、１５ｋの過冷却度を融液にかけ、融液の中央上部から融液底部にかけて低温領域を形成すると同時に融液表面に沿って結晶を大きく広げる。
引き続き、０．２ｍｍ／ｍｉｎの速度で引き上げ成長を開始し、１時間４３分成長を行う。
この後、１０ｍｍ／ｍｉｎの高速で成長したインゴット結晶を融液から引き上げ、成長を終了した。 After that, the melt is cooled at a temperature lowering rate of 0.2 k/min, and the supercooling degree of 15 k is applied to the melt to form a low temperature region from the center upper part of the melt to the melt bottom, and at the same time along the melt surface. Widen the crystal.
Subsequently, pull-up growth is started at a speed of 0.2 mm/min, and growth is performed for 1 hour and 43 minutes.
Then, the ingot crystal grown at a high speed of 10 mm/min was pulled out from the melt, and the growth was completed.

成長したＳｉインゴット単結晶の写真を図６に示す。インゴット結晶の重量は５２０ｇ、厚さは２．５ｃｍ、一辺が９．４×９．７ｃｍの４角形の形状をしており、対角線の長さは１３．７ｃｍになり、ルツボ直径が１５ｃｍなので、ルツボ径の９１％の大きさのｎ型のＳｉインゴット単結晶が成長できた。 A photograph of the grown Si ingot single crystal is shown in FIG. The ingot crystal has a weight of 520 g, a thickness of 2.5 cm, and a square shape with a side of 9.4 x 9.7 cm. The diagonal length is 13.7 cm, and the crucible diameter is 15 cm. An n-type Si ingot single crystal having a size of 91% of the crucible diameter could be grown.

（実施例の具体的作用）
図５、図６を見て明らかなように、これらのインゴット結晶は、ルツボ壁に触れることなく成長している。このことは、本発明により、Ｓｉ融液内部に大きな低温領域が形成できていることを示している。
特に、ルツボ壁の内面近傍の温度を高温に保持したまま、融液中央部をＳｉ融点以下の５５ｋもの大きさに冷却できたことを、ルツボ壁からの核形成と結晶成長が無かったことから示しており、融液内に低温領域がしっかりとできていることを現している。 (Specific action of the embodiment)
As is apparent from FIGS. 5 and 6, these ingot crystals grow without touching the crucible wall. This indicates that a large low temperature region can be formed inside the Si melt by the present invention.
In particular, it was possible to cool the central part of the melt to a size as large as 55 k below the Si melting point while maintaining the temperature near the inner surface of the crucible wall at a high temperature, because there was no nucleation and crystal growth from the crucible wall. The figure shows that a low temperature region is firmly formed in the melt.

Ｓｉ原料内に低温領域ができていることを、次のようにして実験的に確認した。
インゴット結晶の成長初期に、過冷却をかけながらＳｉ融液表面に沿って結晶を広げながら大きく成長する。この結晶成長時に、この広がった結晶を融液から急速に引き上げて成長を強制的に終了させ、その時点での成長界面の形状を確認した。融液内に低温領域が大きく広がっておれば、成長界面は下に凸型の形状をしているはずである。 It was experimentally confirmed that a low temperature region was formed in the Si raw material as follows.
At the beginning of the growth of the ingot crystal, the crystal grows greatly while spreading the crystal along the surface of the Si melt while applying supercooling. During this crystal growth, the spread crystal was rapidly pulled out from the melt to forcibly terminate the growth, and the shape of the growth interface at that time was confirmed. If the low-temperature region is largely spread in the melt, the growth interface should have a downward convex shape.

図７（ｃ）図に示すように、このように強制的に融液から引き上げて取り出したインゴット結晶を側面から観ると、明らかに下に凸型の形状をしていることが判る。
図７（ａ）図は、このようにして取り出したインゴット結晶の上面を示す。種結晶を中心に円形のインゴット結晶が得られている。
図７（ｂ）図は、インゴット結晶が融液表面だけでなく低温領域内で下方に成長して広がっている概念図を示す。 As shown in FIG. 7C, when the ingot crystal thus forcibly pulled out of the melt and taken out is viewed from the side, it is apparent that it has a downward convex shape.
FIG. 7A shows the upper surface of the ingot crystal thus taken out. A circular ingot crystal is obtained centering on the seed crystal.
FIG. 7B shows a conceptual diagram in which the ingot crystal grows downward and spreads not only on the surface of the melt but also in the low temperature region.

このように、成長初期にＳｉ融液表面に沿って結晶を広げている時期に、すでにＳｉ融液内には大きな低温領域ができ、この低温領域内でインゴット結晶が、下に凸型（成長方向に対して凸型）に成長していたことが判る。
さらに、図８に示すように、成長したインゴット結晶の最大直径は断熱材（熱伝導度の悪い材料からなる板）の直径と強い相関があり、断熱材の直径が大きくなるほどインゴット結晶の最大直径が大きくなっている。このことは、断熱材がＳｉインゴット結晶の大口径化に極めて有効であることを実証している。 As described above, when the crystal is spread along the surface of the Si melt in the early stage of growth, a large low temperature region is already formed in the Si melt, and the ingot crystal has a downward convex shape (growth) in this low temperature region. It can be seen that it had grown convexly with respect to the direction.
Further, as shown in FIG. 8, the maximum diameter of the grown ingot crystal has a strong correlation with the diameter of the heat insulating material (a plate made of a material having poor thermal conductivity), and the larger the diameter of the heat insulating material, the larger the maximum diameter of the ingot crystal. Is getting bigger. This demonstrates that the heat insulating material is extremely effective in increasing the diameter of the Si ingot crystal.

（実施例の構成に基づく特有の効果）
本発明は、高効率な太陽電池を作製するためのＳｉインゴット結晶の製造方法に関するもので、歪み、転位密度、酸素濃度の少ない種々の形状の高品質Ｓｉインゴット結晶、その中でも特にＳｉインゴット単結晶を製造する技術に関するものである。
特に、本発明のベースとなる結晶成長技術であるＮＯＣ成長法に適用した時、大きな効果を発揮することができる。 (Specific effects based on the configuration of the embodiment)
The present invention relates to a method for producing a Si ingot crystal for producing a highly efficient solar cell, which is a high-quality Si ingot crystal with various shapes having low strain, dislocation density, and oxygen concentration, and in particular, a Si ingot single crystal. The present invention relates to a technology for manufacturing.
In particular, when applied to the NOC growth method which is the crystal growth technique which is the base of the present invention, a great effect can be exhibited.

なお、本明細書ではＳｉ太陽電池結晶を対象として説明したが、Ｓｉ半導体結晶に対しても同様の効果を発揮できる。
ルツボ底面に配置する熱伝準度の悪い材料からなる板の形状を四角形、多角形、星形、線状、楕円形などに変えることによって、Ｓｉ融液内に設けた低温領域の形状も微妙に変化させることができる。
目的とするＳｉインゴット結晶の形状に合わせた低温領域の設定を使用することができる。 It should be noted that, although the description has been made in this specification with respect to the Si solar cell crystal, the same effect can be exerted also on the Si semiconductor crystal.
The shape of the low-temperature region provided in the Si melt is also subtle by changing the shape of the plate made of a material with poor heat transfer coefficient placed on the bottom of the crucible to a quadrangle, polygon, star, line, ellipse, etc. Can be changed to.
It is possible to use the setting of the low temperature region according to the shape of the desired Si ingot crystal.

本発明によらないで、ルツボ底面を冷却した場合には、下部温度が下がりデンドライト結晶ができる。このため、一般に使われている冷却手法を用いることはできない。この点が本発明の主眼である。
実際に本発明により、ルツボ内に入れたＳｉ融液の表面付近から底部にかけて周囲より融液温度が低く、より大きな過冷却度を有する円形の低温領域を融液内部に局所的に設けた場合、低温領域よりも融液温度が高いルツボ壁近傍の領域から低温領域に向けてデンドライト等の結晶が発現しないことを見出している。このように本発明は、極めて高く強力な効果を発揮する。 When the bottom surface of the crucible is cooled without using the present invention, the lower temperature is lowered and dendrite crystals are formed. For this reason, generally used cooling methods cannot be used. This is the main point of the present invention.
Actually, according to the present invention, when the melt temperature is lower than the surroundings from the vicinity of the surface of the Si melt placed in the crucible to the bottom, and a circular low temperature region having a larger degree of supercooling is locally provided inside the melt. It has been found that crystals such as dendrite do not appear from the region near the crucible wall where the melt temperature is higher than in the low temperature region toward the low temperature region. As described above, the present invention exerts an extremely high and powerful effect.

本発明によれば、低歪み、低転位、低酸素濃度の種々の形状のＳｉインゴット単結晶が得られる。特に、四角形のＳｉインゴット単結晶は、太陽電池用ウェハーを作製する時に、四角形にカッティングする必要が無く、材料のロスが大幅に低減でき、低コスト化に顕著な効果を発揮する。 According to the present invention, various shapes of Si ingot single crystals having low strain, low dislocation and low oxygen concentration can be obtained. In particular, a quadrangular Si ingot single crystal does not need to be cut into a quadrangle when a solar cell wafer is produced, material loss can be significantly reduced, and a remarkable effect can be achieved in cost reduction.

また、Ｓｉ融液内成長を行うと、ルツボ径の８０−９０％の大きさのインゴット結晶を製造できるため、同じサイズのルツボを使った場合、インゴット単結晶の大口径化に大きな効力を発揮できる。
このため、本発明は太陽電池の大幅な普及に大きく貢献できる技術である。この効果は、同時に大口径半導体結晶の普及にも大きな効果を発揮できる。 In addition, since in-crystal growth of Si melt can produce an ingot crystal with a size of 80-90% of the crucible diameter, using a crucible of the same size is very effective in increasing the diameter of an ingot single crystal. it can.
Therefore, the present invention is a technique that can greatly contribute to the widespread use of solar cells. At the same time, this effect can exert a great effect on the spread of large-diameter semiconductor crystals.

（産業上の利用分野）
高効率太陽電池を作製できる高品質・高均質なＳｉインゴット結晶の製造方法及びその製造装置に関する発明であり、現在主流のＳｉ結晶太陽電池の分野に革新的な技術を供与できる。
さらに、半導体デバイスを作製できる大口径・高品質なＳｉインゴット結晶の製造方法及びその製造装置にも適用可能な発明であり、小さな装置を用いて大口径のＳｉインゴット単結晶を製造できる革新的な技術を供与できる。 (Industrial application field)
The present invention relates to a method for producing a high-quality and highly homogeneous Si ingot crystal capable of producing a high-efficiency solar cell and an apparatus for producing the same, and can provide an innovative technology to the field of the Si crystal solar cell, which is currently the mainstream.
Further, it is an invention applicable to a manufacturing method of a large-diameter and high-quality Si ingot crystal capable of manufacturing a semiconductor device and an apparatus for manufacturing the same, and an innovative method capable of manufacturing a large-diameter Si ingot single crystal using a small apparatus. Can provide technology.

なお、本明細書に開示した実施例は、本発明の理解を容易にするために例示したものであって、本発明はこれに限定されない。
すなわち、本発明は、特許請求の範囲を逸脱しない限り、Ｓｉインゴット結晶の製造方法及びその製造装置について、適宜の設計変更が可能であることは言うまでもないことである。 It should be noted that the embodiments disclosed in the present specification are merely examples for facilitating the understanding of the present invention, and the present invention is not limited thereto.
That is, it goes without saying that the present invention can appropriately change the design of the manufacturing method of the Si ingot crystal and the manufacturing apparatus thereof, without departing from the scope of the claims.

Claims

By inhibiting heat input to the central part of the crucible bottom containing the Si melt, a low temperature region lower than the surrounding melt temperature is formed in the Si melt from the upper center to the lower center of the Si melt. Then, a method for producing a Si ingot single crystal by the NOC growth method , characterized in that the Si ingot crystal is grown in the Si melt so as not to touch the crucible wall by utilizing the low temperature region.

A heating element is arranged at the bottom of the crucible containing the Si melt, and heat input from the heating element to the central part of the crucible bottom is obstructed, so that the surroundings from the upper center to the lower center of the Si melt are surrounded. NOC growth characterized in that a low temperature region lower than the melt temperature is formed in the Si melt, and the low temperature region is used to grow the Si ingot crystal in the Si melt without touching the crucible wall. A method for producing a Si ingot single crystal by the method.

A plate made of a material having poor thermal conductivity is placed at the center of the bottom of the crucible containing the Si melt to prevent heat input to the center of the crucible bottom, and the center of the Si melt to the bottom center of the melt. Characterized in that a low temperature region lower than the surrounding melt temperature is formed in the Si melt, and the Si ingot crystal is grown in the Si melt using the low temperature region so as not to touch the crucible wall. A method for manufacturing a Si ingot single crystal by the NOC growth method.

In a Si melt of a Si ingot crystal using a crucible, a synthetic plate having a structure in which a plate made of a material having poor thermal conductivity and a plate made of a material having good thermal conductivity are geometrically combined in a plane is prepared. Then, the synthetic plate is placed at the bottom of the crucible containing the Si melt, and the plate having poor thermal conductivity inhibits heat input to the central part of the crucible bottom, and the Si melt melts from the upper center to the lower center. NOC characterized in that a low temperature region lower than the surrounding melt temperature is formed in the melt over the period of time, and the Si ingot crystal is grown in the Si melt by utilizing the low temperature region so as not to touch the crucible wall. A method for producing a Si ingot single crystal by a growth method.

By inhibiting heat input to the center of the crucible bottom containing the Si melt, a low temperature region lower than the surrounding melt temperature from the upper center to the lower center of the Si melt is formed in the Si melt, A method for producing a Si ingot single crystal by the NOC growth method, which comprises utilizing the low temperature region to grow a Si ingot crystal in a Si melt without touching a crucible wall,
Utilizing the low temperature region provided in the melt, after initiating crystal growth by contacting the Si seed crystal with the Si melt surface, ingot crystal along the Si melt surface or toward the inside of the melt And a first step of pulling up a part of the grown ingot crystal from the melt to such an extent that it is not separated from the melt, and from the crystal remaining in the melt again, along the surface of the Si melt or A second step of growing an ingot crystal toward the inside and pulling a part of the regrown ingot crystal from the melt to such an extent that it is not separated from the Si melt, is sequentially repeated to grow the ingot crystal. A method for producing a Si ingot single crystal by the characteristic NOC growth method.

After starting the pulling growth of the Si ingot crystal, when lowering the temperature of the entire Si melt to enlarge the low temperature region and greatly expanding the crystal inside the melt, the temperature is lowered and the pulling is performed intermittently or continuously. The method for producing a Si ingot single crystal by the NOC growth method according to any one of claims 1 to 5.

The method for producing a Si ingot single crystal by the NOC growth method according to claim 5 or 6, wherein the Si seed crystal is subjected to rotation or repeated right and left repeated rotations.

A crucible surrounding the crucible containing the Si melt is provided with a side heater and a bottom heater, and a plate made of a material having poor thermal conductivity is placed between the bottom heater and the bottom of the crucible at the center of the crucible bottom to form the center of the crucible bottom. A low temperature region lower than the surrounding melt temperature is formed in the Si melt from the upper center to the lower center of the Si melt, and the Si ingot crystal is utilized in the crucible. An apparatus for producing a Si ingot single crystal by the NOC growth method, which is characterized in that it is grown in a Si melt without touching a wall.

A side heater and a bottom heater surrounding the crucible for containing the Si melt are provided, and a plate made of a material having poor thermal conductivity and a plate made of a material having good thermal conductivity are geometrically provided between the bottom heater and the bottom of the crucible. By arranging a synthetic plate having a structure combined in a plane, a plate made of a material with poor thermal conductivity inhibits heat input to the central part of the crucible bottom, and melts the Si melt from the upper center to the lower center. According to the NOC growth method, a low temperature region lower than the liquid temperature is formed in the Si melt, and the low temperature region is used to grow the Si ingot crystal in the Si melt without touching the crucible wall. Si ingot single crystal manufacturing equipment.

The material having poor thermal conductivity has a thermal conductivity of 0.6 W/m·k or less near the melting point of Si, and the material having good thermal conductivity has a thermal conductivity of 20-60 W/m·k near the melting point of Si. The apparatus for producing a Si ingot single crystal by the NOC growth method according to claim 9, wherein k is k.

11. The Si ingot single crystal produced by the NOC growth method according to claim 10, wherein the material having poor thermal conductivity has a thermal conductivity of 0.15-0.55 W/m·k near the melting point of Si. manufacturing device.

10. The NOC growth according to claim 9, wherein the material of the plate made of a material having poor thermal conductivity is a graphite heat insulating material, and the material of the plate made of a material having good thermal conductivity is a graphite material. Si ingot single crystal manufacturing apparatus by the method .

The shape of the plate made of a material having poor thermal conductivity, which is arranged in the crucible bottom in order to inhibit heat input to the center of the crucible bottom, is a circle, a quadrangle, a polygon, a star, a line, or a circle, and 13. A synthetic plate having a structure in which the plates made of a material having a high thermal conductivity are geometrically arranged in a plane around the plates to form a combined plate. An apparatus for producing a Si ingot single crystal by the described NOC growth method .

The apparatus for producing a Si ingot single crystal by the NOC growth method according to claim 13, wherein a cooling body is arranged below the synthetic plate.

The apparatus for producing a Si ingot single crystal by the NOC growth method according to any one of claims 8 to 14, further comprising a mechanism for imparting rotation or right and left repeated repetitive rotation to the Si seed crystal.

16. A carbon heat holder that surrounds the crucible is provided between the crucible for containing the Si melt and the side heaters and the bottom heater that surround the crucible. An apparatus for producing a Si ingot single crystal by the NOC growth method described in 1.