JP2016088812A

JP2016088812A - Method and apparatus for manufacturing silicon carbide single crystal ingot

Info

Publication number: JP2016088812A
Application number: JP2014225952A
Authority: JP
Inventors: 弘志柘植; Hiroshi Tsuge; 藤本　辰雄; Tatsuo Fujimoto; 辰雄藤本; 勝野　正和; Masakazu Katsuno; 正和勝野; 小桃谷; Komomo Tani; 昌史牛尾; Masashi Ushio
Original assignee: Nippon Steel and Sumitomo Metal Corp
Current assignee: Nippon Steel Corp
Priority date: 2014-11-06
Filing date: 2014-11-06
Publication date: 2016-05-23
Anticipated expiration: 2034-11-06
Also published as: JP6501494B2

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a silicon carbide single crystal ingot, capable of efficiently sublimating a raw material charged in a crucible during the growth of a silicon carbide single crystal and suitable for the manufacture of a silicon carbide single crystal ingot having a long size and a large diameter.SOLUTION: The method for manufacturing a silicon carbide single crystal ingot, capable of growing a silicon carbide single crystal by a sublimation recrystallization method for recrystallizing a sublimation gas generated by heating a silicon carbide raw material charged in the crucible on a silicon carbide seed crystal arranged to face each other in the crucible includes heating a central portion of the silicon carbide raw material (the raw material in the crucible) charged in the crucible from the lower side through a central portion of the bottom wall part of the crucible.SELECTED DRAWING: Figure 2

Description

この発明は、種結晶を用いた昇華再結晶法によって炭化珪素単結晶を成長させる炭化珪素単結晶インゴットの製造方法及び製造装置に関する。 The present invention relates to a silicon carbide single crystal ingot manufacturing method and a manufacturing apparatus for growing a silicon carbide single crystal by a sublimation recrystallization method using a seed crystal.

高熱伝導率を持ち、バンドギャップの大きい炭化珪素単結晶は、高温で用いられる電子材料や、高耐圧の求められる電子材料の基板として有用な材料である。
そして、このような炭化珪素単結晶の作製法の一つとして、昇華再結晶法(レーリー法)が知られている。この昇華再結晶法は、２０００℃を超える高温において原料の炭化珪素粉末を昇華させ、生成したその昇華ガス（原料ガス）を低温部に再結晶化させることにより、炭化珪素単結晶を製造する方法である。また、このレーリー法において、炭化珪素単結晶からなる種結晶を用いて炭化珪素単結晶を製造する方法は、特に改良レーリー法と呼ばれ（非特許文献１）、バルク状の炭化珪素単結晶インゴットの製造に利用されている。 A silicon carbide single crystal having high thermal conductivity and a large band gap is a useful material as a substrate for electronic materials used at high temperatures and electronic materials that require high breakdown voltage.
As one method for producing such a silicon carbide single crystal, a sublimation recrystallization method (Rayleigh method) is known. In this sublimation recrystallization method, a silicon carbide single crystal is produced by sublimating a raw material silicon carbide powder at a high temperature exceeding 2000 ° C. and recrystallizing the generated sublimation gas (raw material gas) to a low temperature part. It is. Further, in this Rayleigh method, a method of producing a silicon carbide single crystal using a seed crystal composed of a silicon carbide single crystal is called an improved Rayleigh method (Non-patent Document 1), and is a bulk silicon carbide single crystal ingot. It is used for manufacturing.

この改良レーリー法においては、種結晶を用いているために結晶の核形成過程を最適化することができ、また、不活性ガスによる雰囲気圧力を１０Paから１５kPa程度にすることにより、炭化珪素単結晶の成長速度等の再現性を良くすることができる。このため、一般に、原料と結晶との間で適切な温度差を設け、種結晶の上に炭化珪素単結晶を成長させることが行われている。また、得られた炭化珪素単結晶（炭化珪素単結晶インゴット）については、電子材料の基板としての規格の形状にするために、研削、切断、研磨といった加工が施されて利用されている。 In this improved Rayleigh method, since a seed crystal is used, the nucleation process of the crystal can be optimized, and by adjusting the atmospheric pressure by an inert gas to about 10 Pa to 15 kPa, a silicon carbide single crystal The reproducibility of the growth rate and the like can be improved. For this reason, generally, an appropriate temperature difference is provided between the raw material and the crystal, and a silicon carbide single crystal is grown on the seed crystal. Further, the obtained silicon carbide single crystal (silicon carbide single crystal ingot) is used after being subjected to processing such as grinding, cutting, and polishing in order to obtain a standard shape as a substrate of an electronic material.

ここで、図６を用いて、改良レーリー法の原理を説明する。炭化珪素原料３として炭化珪素結晶粉末〔通常、アチソン(Acheson)法で作製された炭化珪素結晶粉末を洗浄・前処理したものが使用される。〕が用いられ、また、種結晶２としては炭化珪素単結晶が用いられる。前記炭化珪素原料粉末からなる原料３は黒鉛製の坩堝１内の下部、原料装填部に装填され、また、前記炭化珪素単結晶からなる種結晶２は坩堝１の蓋部材1aの内面側に支持（装着）される。アルゴン等の不活性ガス雰囲気中（10Pa〜15kPa）で原料３を昇華させるために、原料３は２４００℃以上に加熱される。この際、坩堝１内には、原料３側に比べて種結晶２側がやや低温になるように、温度勾配が設定される。原料３は、加熱されて昇華した後、濃度勾配（温度勾配により形成される）により種結晶２方向へ拡散し、輸送される。炭化珪素単結晶の成長は、種結晶２に到着した原料ガスがこの種結晶２上で再結晶化し、単結晶インゴット４となることにより実現される。なお、図２中、符号５は断熱材である。 Here, the principle of the improved Rayleigh method will be described with reference to FIG. As the silicon carbide raw material 3, silicon carbide crystal powder [usually, a silicon carbide crystal powder produced by the Acheson method is washed and pretreated is used. In addition, as the seed crystal 2, a silicon carbide single crystal is used. The raw material 3 made of the silicon carbide raw material powder is loaded into the lower portion of the graphite crucible 1 and the raw material loading portion, and the seed crystal 2 made of the silicon carbide single crystal is supported on the inner surface side of the lid member 1a of the crucible 1. (Installed). In order to sublimate the raw material 3 in an inert gas atmosphere such as argon (10 Pa to 15 kPa), the raw material 3 is heated to 2400 ° C. or higher. At this time, a temperature gradient is set in the crucible 1 so that the seed crystal 2 side is slightly cooler than the raw material 3 side. After being heated and sublimated, the raw material 3 is diffused in the direction of the seed crystal 2 by a concentration gradient (formed by a temperature gradient) and transported. The growth of the silicon carbide single crystal is realized by recrystallizing the source gas arriving at the seed crystal 2 on the seed crystal 2 to form a single crystal ingot 4. In addition, in FIG. 2, the code | symbol 5 is a heat insulating material.

ところで、電子デバイスを作製するために使用される炭化珪素単結晶製の基板については、その口径を大きくする大口径化が求められており、また同時に、基板の製造時に１つのインゴットから多数の基板を製造して切断加工や研削加工等の生産性をより高めることができるように、結晶成長により得られるインゴットの長さを大きくする長尺化が求められている。 By the way, about the board | substrate made from a silicon carbide single crystal used for producing an electronic device, the enlargement to enlarge the diameter is calculated | required, and simultaneously many substrates from one ingot at the time of manufacture of a board | substrate are calculated | required. Is required to increase the length of the ingot obtained by crystal growth so that the productivity of cutting and grinding can be further increased.

しかしながら、前記の炭化珪素単結晶インゴットの製造方法においては、炭化珪素単結晶の結晶を成長させる際に、原料を黒鉛製の坩堝の中に装填して加熱する方法が用いられているため、原料を結晶成長の途中で追加することが困難である。そこで、大口径かつ長尺の炭化珪素単結晶インゴットを作製するためには、小口径の結晶成長に比べて、坩堝の原料装填部に原料粉末を多量に装填する必要がある。しかるに、原料の装填量を増大させるためには、原料装填部の深さを深くすることや、坩堝の径を大きくすることが必要になり、しかも、このように多量に装填した原料を結晶成長の際に効率的に利用するためには、原料装填部内の原料全体の温度を昇華温度まで効率良く加熱することが必要である。 However, in the above method for producing a silicon carbide single crystal ingot, when growing a silicon carbide single crystal crystal, a method is used in which the raw material is charged in a graphite crucible and heated. Is difficult to add during the crystal growth. Therefore, in order to produce a large-diameter and long-sized silicon carbide single crystal ingot, it is necessary to load a large amount of raw material powder in the raw material loading portion of the crucible as compared with the small-diameter crystal growth. However, in order to increase the loading amount of the raw material, it is necessary to increase the depth of the raw material loading part and increase the diameter of the crucible, and crystal growth of the raw material loaded in such a large amount In order to use it efficiently in this case, it is necessary to efficiently heat the temperature of the entire raw material in the raw material loading section to the sublimation temperature.

そして、坩堝を加熱する方法としては、一般に、坩堝の側壁部側方にこの側壁部を取り囲むように高周波誘導加熱手段の誘導加熱コイルを配設し、高周波誘導加熱により黒鉛製の坩堝を発熱させ、この発熱した坩堝を介して坩堝内の炭化珪素原料を加熱し、坩堝内に前述の温度勾配を形成することが行われている。また、この高周波誘導加熱では、誘導される高周波電流が高周波の浸透深さに依存しているため、坩堝の形状によって規定された発熱分布を持ち、坩堝側面の表面近傍で強い発熱が生じ、この熱は熱伝導若しくは熱輻射により原料部分に伝達され、これによって原料部分が加熱される。上記のように高周波誘導加熱を行った場合、坩堝の側面に誘導電流が誘起されるが、特に、坩堝のような外形が円柱形状（以下、「外形円柱状」という。）の被加熱物を誘導加熱した場合には、外形円柱状の上端と下端に近い側壁部の側面が強く誘導加熱される。これに伴い、坩堝の上端部側面や、下端の底壁部側面での発熱が他の側面部分に比べて大きくなるという特徴がある。 As a method of heating the crucible, generally, an induction heating coil of high frequency induction heating means is disposed on the side of the side wall of the crucible so as to surround the side wall, and the graphite crucible is heated by high frequency induction heating. The silicon carbide raw material in the crucible is heated through the heated crucible to form the above-described temperature gradient in the crucible. In addition, in this high frequency induction heating, since the induced high frequency current depends on the penetration depth of the high frequency, it has a heat generation distribution defined by the shape of the crucible, and a strong heat generation occurs near the surface of the crucible side surface. Heat is transferred to the raw material portion by heat conduction or heat radiation, thereby heating the raw material portion. When high-frequency induction heating is performed as described above, an induction current is induced on the side surface of the crucible. In particular, an object to be heated having a cylindrical shape (hereinafter referred to as an “external cylindrical shape”) like a crucible is used. In the case of induction heating, the side surface of the side wall near the upper end and the lower end of the outer cylindrical shape is strongly induction heated. Along with this, there is a feature that heat generation on the side surface of the upper end portion of the crucible and the side surface of the bottom wall portion of the lower end becomes larger than that of other side surface portions.

このようにして原料装填部内の原料が加熱されると、原料内部の高温部から昇華ガスが発生し、結晶成長が生じるが、原料内部には不可避的に温度分布が生じ、原料内部の高温部で昇華した原料ガスの一部は原料内部の低温部で再結晶化を起こし、結晶成長に寄与しない場合がある。そして、この低温部の温度を高温化しその部分にある原料を昇華させるためには、誘導電流の電流値を大きくして坩堝の側壁部の温度をより高温に加熱する必要があるが、一方で、坩堝の側壁部の温度を高温にすると、坩堝全体が高温になり、種結晶と接している部分の坩堝の温度も高温になり、種結晶や成長中の単結晶の温度も高くなって、温度勾配に基づいた結晶成長の駆動力が小さくなり、結晶成長が途中で停止する結晶成長停止の問題が発生する。 When the raw material in the raw material charging part is heated in this way, sublimation gas is generated from the high temperature part inside the raw material and crystal growth occurs, but temperature distribution inevitably occurs inside the raw material, and the high temperature part inside the raw material Some of the source gas sublimated in step 1 may recrystallize at a low temperature inside the source material and may not contribute to crystal growth. And in order to raise the temperature of this low temperature part and sublimate the raw material in that part, it is necessary to increase the current value of the induced current and heat the temperature of the side wall part of the crucible to a higher temperature. When the temperature of the side wall of the crucible is increased, the temperature of the entire crucible is increased, the temperature of the crucible in contact with the seed crystal is also increased, and the temperature of the seed crystal and the growing single crystal is increased. The driving force for crystal growth based on the temperature gradient is reduced, and there is a problem of crystal growth stop that stops crystal growth in the middle.

そこで、従来においても、坩堝の原料装填部内に装填された原料を加熱する方法について幾つかの提案がされている。
例えば、特許文献１においては、坩堝内の底壁部にこの底壁部と密着する断熱層を設け、これによって坩堝の底壁部での温度低下を防止し、原料の下部における再結晶を抑制し、効率的に原料を加熱する方法が開示されている。また、特許文献２においては、原料を加熱する部分の坩堝の側壁の形状を制御し、原料内部の温度分布を均一化する方法が開示されている。 Thus, several proposals have been made in the past regarding methods for heating the raw material loaded in the raw material loading portion of the crucible.
For example, in Patent Document 1, a heat insulating layer that is in close contact with the bottom wall portion is provided on the bottom wall portion in the crucible, thereby preventing a temperature drop at the bottom wall portion of the crucible and suppressing recrystallization at the bottom of the raw material. In addition, a method for efficiently heating a raw material is disclosed. Further, Patent Document 2 discloses a method of controlling the shape of the side wall of the crucible at the part where the raw material is heated to make the temperature distribution inside the raw material uniform.

また、特許文献３においては、坩堝の底壁部の外側に底壁部側加熱コイルを設置し、坩堝内に装填された原料を坩堝の底壁部側からも加熱できるようにした方法が開示されている。更に、特許文献４においては、坩堝の側壁部の下方に坩堝の底壁部を超えて延びる側壁部分を延設し、この側壁部分での発熱により原料下部の発熱を増大させ、断熱材に形成された測温孔部分での温度の低下を抑制する方法が開示されている。更にまた、特許文献５においては、原料を装填する坩堝の底部の電気伝導率を側部（側壁部）よりも高くして底部での発熱を増大させ、これによって原料の底部に接する部分での温度を高くし、原料を残さず昇華させる方法が開示されている。 Patent Document 3 discloses a method in which a bottom wall side heating coil is installed outside the bottom wall portion of the crucible so that the raw material charged in the crucible can be heated also from the bottom wall portion side of the crucible. Has been. Furthermore, in Patent Document 4, a side wall portion extending beyond the bottom wall portion of the crucible is extended below the side wall portion of the crucible, and heat generation at the lower portion of the raw material is increased by heat generation at the side wall portion, thereby forming a heat insulating material. A method for suppressing a decrease in temperature at the temperature measuring hole portion is disclosed. Furthermore, in Patent Document 5, the electric conductivity of the bottom part of the crucible loaded with the raw material is made higher than that of the side part (side wall part) to increase the heat generation at the bottom part, thereby the part in contact with the bottom part of the raw material. A method of increasing the temperature and sublimating without leaving a raw material is disclosed.

特開2010-76,990号公報JP 2010-76,990 特開2007-230,846号公報JP 2007-230,846 特開2013-216,549号公報JP 2013-216,549 特開2012-206,876号公報JP 2012-206,876 特開2012-171,832号公報JP 2012-171,832

Yu. M. Tairov and V. F. Tsvetkov, Journal of Crystal Growth, 52 (1981) pp.146Yu. M. Tairov and V. F. Tsvetkov, Journal of Crystal Growth, 52 (1981) pp.146

しかしながら、特許文献１の方法では、高周波誘導加熱により発熱する部分は依然として坩堝の側壁部に限られ、原料の中心部分の温度が低下するという問題が残り、大口径化のために口径を増大させた坩堝の中心部の原料を効率良く加熱する目的のためには採用し難いという問題がある。また、特許文献２の方法では、坩堝の側壁部での発熱分布が変化することに伴い、成長している結晶部分近傍での発熱分布も変化する。結晶成長は等温線に沿って進むと考えられるので、発熱分布が変化することにより、成長する結晶の成長面形状も影響を受け、原料部分での均温化と成長結晶部分での温度の最適化とを両立させることが必要になるが、この最適化に時間がかかる、若しくは、最適化ができないという問題がある。 However, in the method of Patent Document 1, the portion that generates heat by high-frequency induction heating is still limited to the side wall portion of the crucible, and there remains a problem that the temperature of the central portion of the raw material decreases, and the diameter is increased to increase the diameter. There is a problem that it is difficult to adopt for the purpose of efficiently heating the raw material in the center of the crucible. Further, in the method of Patent Document 2, the heat generation distribution in the vicinity of the growing crystal portion also changes as the heat generation distribution in the side wall portion of the crucible changes. Since crystal growth is thought to proceed along an isotherm, the change in the heat generation distribution also affects the shape of the growth surface of the growing crystal, so that temperature equalization at the raw material portion and temperature optimization at the growing crystal portion are optimal. However, there is a problem that this optimization takes time or cannot be optimized.

また、特許文献３の方法では、坩堝の底壁部を直接加熱することができるが、装置の構造が複雑になると同時に、坩堝の側壁部側を加熱する側壁部側加熱コイルと坩堝の底壁部側を加熱する底壁部側加熱コイルとの間に相互作用があり、それぞれの誘導加熱コイルに流す電流の最適化が難しくなり、最適化に時間がかかる、若しくは最適化ができないという問題がある。更に、特許文献４の方法では、坩堝の側壁部に近い部分での発熱を増大させているため、依然として、原料の温度がその中心部より外周部で高くなるという問題は残り、この原料の外周部と中心部との間の温度差に起因して、原料の中心部で再結晶化の問題が発生し、装填した原料を有効に昇華させることができないという問題がある。 In the method of Patent Document 3, the bottom wall of the crucible can be directly heated. However, the structure of the apparatus becomes complicated, and at the same time, the side wall heating coil for heating the side wall of the crucible and the bottom wall of the crucible There is an interaction with the bottom wall side heating coil that heats the part side, it becomes difficult to optimize the current flowing through each induction heating coil, and it takes time for optimization or it can not be optimized is there. Furthermore, in the method of Patent Document 4, since the heat generation in the portion close to the side wall portion of the crucible is increased, there still remains a problem that the temperature of the raw material is higher in the outer peripheral portion than in the central portion. Due to the temperature difference between the central part and the central part, there is a problem of recrystallization at the central part of the raw material, and the charged raw material cannot be sublimated effectively.

更にまた、特許文献５の方法では、誘導電流は坩堝の側部（側壁部）を流れるために原料の中心部に近い部分を効果的に加熱することはできず、また、坩堝の底部と原料との配置は結晶成長中に変化することがないため、原料の底部に接する部分での温度を上げるためには系全体の温度を上げる必要がある。そして、系全体の温度を上げた場合には、成長している結晶部分の温度が高くなり、成長した結晶が高温になって結晶自身が昇華する場合があり、その部分に欠陥が発生し、良質の結晶が得られない場合がある。このため、この特許文献５の方法を用いても、中心部近傍の原料を有効に加熱することは難しく、多量の昇華ガスを必要とするインゴットの大口径化、長尺化には不向きである。 Furthermore, in the method of Patent Document 5, since the induced current flows through the side part (side wall part) of the crucible, the portion near the center part of the raw material cannot be effectively heated, and the bottom part of the crucible and the raw material Therefore, the temperature of the entire system needs to be raised in order to raise the temperature at the portion in contact with the bottom of the raw material. And when the temperature of the whole system is raised, the temperature of the growing crystal part becomes high, the grown crystal becomes high temperature and the crystal itself may sublimate, a defect occurs in that part, There are cases where good quality crystals cannot be obtained. For this reason, even if the method of this patent document 5 is used, it is difficult to effectively heat the raw material in the vicinity of the center, and it is not suitable for increasing the diameter and length of an ingot that requires a large amount of sublimation gas. .

本発明は、かかる観点に鑑みて創案させたものであり、炭化珪素単結晶の成長中に坩堝内に装填した炭化珪素原料を効率良く昇華させ、大口径かつ長尺の炭化珪素単結晶インゴットを製造するのに適した炭化珪素単結晶インゴットの製造方法を提供することを目的とする。 The present invention was devised in view of such a viewpoint, and efficiently sublimates a silicon carbide raw material charged in a crucible during the growth of a silicon carbide single crystal, thereby producing a large-diameter and long-sized silicon carbide single crystal ingot. It aims at providing the manufacturing method of a silicon carbide single crystal ingot suitable for manufacture.

本発明者らは、高周波誘導加熱を用いて、大口径かつ長尺の炭化珪素単結晶インゴットを製造する場合に、黒鉛製の坩堝内に装填した炭化珪素原料（坩堝内原料）を効率良く昇華させることができる方法について鋭意検討した。その結果、坩堝の底壁部の中央部分をその外面側から加熱することにより、坩堝内原料の中央部を効率良く昇華させ、大口径かつ長尺の炭化珪素単結晶インゴットを製造することができることを見出し、本発明を完成した。 The present inventors efficiently sublimate a silicon carbide raw material (raw material in a crucible) loaded in a graphite crucible when producing a large-diameter and long silicon carbide single crystal ingot using high-frequency induction heating. The method which can be made was examined earnestly. As a result, by heating the central portion of the bottom wall portion of the crucible from the outer surface side, the central portion of the raw material in the crucible can be efficiently sublimated, and a large-diameter and long silicon carbide single crystal ingot can be manufactured. The present invention has been completed.

すなわち、本発明の要旨は次の通りである。
〔１〕炭化珪素原料を黒鉛製の坩堝の下部に装填し、坩堝の下部を高周波誘導加熱手段で加熱し、前記炭化珪素原料を間接的に加熱して昇華ガスを発生させ、坩堝の上部に対向配置した炭化珪素の種結晶上に炭化珪素を再結晶させる昇華再結晶法により、炭化珪素単結晶を成長させて炭化珪素単結晶インゴットを製造する方法において、前記坩堝内に装填された炭化珪素原料（坩堝内原料）の中央部を、前記坩堝の底壁部中央部分を介して下方側から加熱することを特徴とする炭化珪素単結晶インゴットの製造方法。
〔２〕前記坩堝の底壁部中央部分の外面側に発熱部材を接触させて配置し、この発熱部材を高周波誘導加熱手段で加熱することを特徴とする前記〔１〕に記載の炭化珪素単結晶インゴットの製造方法。
〔３〕前記坩堝の底壁部の外径(Ｄb)に対して、その外面側から熱を供給するために配置された発熱部材が接触する前記底壁部中央部分の直径(Ｄc)の加熱部比率（Ｄc／Ｄb）が、０．３以上０．８以下であることを特徴とする前記〔２〕に記載の炭化珪素単結晶インゴットの製造方法。
〔４〕前記坩堝内の上部に種結晶を配置すると共に下部に炭化珪素原料を装填し、前記坩堝内に装填された炭化珪素原料（坩堝内原料）を高周波誘導加熱手段により加熱し、炭化珪素を昇華させて前記種結晶上に再結晶させることにより、炭化珪素単結晶インゴットを製造する装置において、前記坩堝の底壁部中央部分の外面側に発熱部材を接触させて設けると共に、この発熱部材を取り囲むように前記高周波誘導加熱手段の誘導加熱コイルを配置したことを特徴とする炭化珪素単結晶インゴットの製造装置。
〔５〕前記坩堝の底壁部の外径(Ｄb)に対して、その外面側から熱を供給するために配置された発熱部材が接触する前記底壁部中央部分の直径(Ｄc)の加熱部比率（Ｄc／Ｄb）が、０．３以上０．８以下であることを特徴とする前記〔４〕に記載の炭化珪素単結晶インゴットの製造装置。 That is, the gist of the present invention is as follows.
[1] A silicon carbide raw material is loaded in the lower part of a graphite crucible, the lower part of the crucible is heated by high-frequency induction heating means, and the silicon carbide raw material is indirectly heated to generate sublimation gas. In a method for producing a silicon carbide single crystal ingot by growing a silicon carbide single crystal by a sublimation recrystallization method in which silicon carbide is recrystallized on a seed crystal of silicon carbide arranged oppositely, silicon carbide loaded in the crucible A method for producing a silicon carbide single crystal ingot, comprising heating a central portion of a raw material (raw material in a crucible) from a lower side through a central portion of a bottom wall portion of the crucible.
[2] A silicon carbide single unit as described in [1] above, wherein a heating member is disposed in contact with the outer surface of the central portion of the bottom wall of the crucible, and the heating member is heated by high-frequency induction heating means. A method for producing a crystal ingot.
[3] Heating the diameter (Dc) of the central portion of the bottom wall where the heat generating member arranged to supply heat from the outer surface side contacts the outer diameter (Db) of the bottom wall of the crucible Part ratio (Dc / Db) is 0.3 or more and 0.8 or less, The method for producing a silicon carbide single crystal ingot according to [2] above.
[4] A seed crystal is disposed in the upper part of the crucible and a silicon carbide raw material is charged in the lower part, and the silicon carbide raw material (raw material in the crucible) charged in the crucible is heated by high-frequency induction heating means to obtain silicon carbide. In the apparatus for producing a silicon carbide single crystal ingot by sublimating and recrystallizing on the seed crystal, a heating member is provided in contact with the outer surface side of the central portion of the bottom wall of the crucible, and the heating member An induction heating coil of the high-frequency induction heating means is disposed so as to surround the silicon carbide single crystal ingot manufacturing apparatus.
[5] Heating of the diameter (Dc) of the central portion of the bottom wall portion in contact with the outer diameter (Db) of the bottom wall portion of the crucible with a heating member arranged to supply heat from the outer surface side Part ratio (Dc / Db) is 0.3 or more and 0.8 or less, The manufacturing apparatus of the silicon carbide single crystal ingot as described in said [4] characterized by the above-mentioned.

本発明の炭化珪素単結晶インゴットの製造方法によれば、大口径かつ長尺の炭化珪素単結晶インゴットを成長させる際に、坩堝内原料について、その中心部の温度を外周部の温度と比較して、同じ、若しくは、より高くして加熱することが可能であり、従来、低温である原料中心部での原料の再結晶化を防ぎ、装填した原料を有効に昇華させること、すなわち炭化珪素原料の結晶化率〔＝(成長した炭化珪素単結晶インゴットの重量)／（装填した炭化珪素原料の重量）〕を高くすることができる。 According to the method for producing a silicon carbide single crystal ingot of the present invention, when growing a large-diameter and long silicon carbide single crystal ingot, the temperature in the center of the raw material in the crucible is compared with the temperature in the outer periphery. Can be heated at the same or higher temperature, preventing recrystallization of the raw material at the center of the raw material, which has been conventionally low, and effectively sublimating the loaded raw material, that is, silicon carbide raw material The crystallization rate [= (weight of grown silicon carbide single crystal ingot) / (weight of loaded silicon carbide raw material)] can be increased.

このことにより、結晶成長面に昇華ガスが効率的かつ安定的に供給されるようになり、結晶成長中に昇華ガスの供給が変動することに起因する欠陥の発生を抑制することができ、高品質の炭化珪素インゴットを製造することができ、また、この高品質の炭化珪素単結晶インゴットを用いて電子材料用の炭化珪素単結晶基板を製造すれば、炭化珪素原料に対して製造される基板の歩留まりが向上し、炭化珪素単結晶基板のコスト低減を図ることができる。 As a result, the sublimation gas can be efficiently and stably supplied to the crystal growth surface, and generation of defects due to fluctuations in the supply of sublimation gas during crystal growth can be suppressed. A quality silicon carbide ingot can be manufactured, and if a silicon carbide single crystal substrate for an electronic material is manufactured using this high quality silicon carbide single crystal ingot, the substrate manufactured for the silicon carbide raw material Yield can be improved, and the cost of the silicon carbide single crystal substrate can be reduced.

図１は、本発明の炭化珪素単結晶インゴットの製造方法の実施例で用いる炭化珪素単結晶インゴットの製造装置の全体を示す説明図である。FIG. 1 is an explanatory view showing the entire apparatus for producing a silicon carbide single crystal ingot used in an embodiment of the method for producing a silicon carbide single crystal ingot of the present invention. 図２は、図１の要部を説明するための説明図である。FIG. 2 is an explanatory diagram for explaining a main part of FIG. 図３は、本発明の実施例１で用いられた坩堝の底壁部中央部分を加熱するための構成を示す説明図である。FIG. 3 is an explanatory diagram showing a configuration for heating the central portion of the bottom wall portion of the crucible used in Example 1 of the present invention. 図４は、本発明の実施例２で用いられた坩堝の底壁部中央部分を加熱するための構成を示す説明図である。FIG. 4 is an explanatory diagram showing a configuration for heating the central portion of the bottom wall of the crucible used in Example 2 of the present invention. 図５は、本発明の実施例３で用いられた坩堝の底壁部中央部分を加熱するための構成を示す説明図である。FIG. 5 is an explanatory diagram showing a configuration for heating the central portion of the bottom wall portion of the crucible used in Example 3 of the present invention. 図６は、改良レーリー法の原理を説明するための説明図である。FIG. 6 is an explanatory diagram for explaining the principle of the improved Rayleigh method.

以下、添付図面に示す炭化珪素単結晶インゴットの製造装置を用いて、本発明の炭化珪素単結晶インゴットの製造方法の実施の形態を具体的に説明する。 Embodiments of a method for manufacturing a silicon carbide single crystal ingot according to the present invention will be specifically described below using a silicon carbide single crystal ingot manufacturing apparatus shown in the accompanying drawings.

図１は、炭化珪素単結晶インゴットの製造装置の全体を説明するためのものであり、この製造装置において、二重石英管13内には黒鉛製の坩堝１（以下、「坩堝」と略す。）とこの坩堝１を取り囲むように覆う黒鉛製の断熱材５とが配設されており、また、前記坩堝１には、その上部に黒鉛製の蓋部材1aが配設されている。更に、前記二重石英管13の外側には発熱部材として機能する前記坩堝１を発熱させる高周波誘導加熱手段の誘導加熱コイル17が設置されている。 FIG. 1 is a diagram for explaining the entire manufacturing apparatus for a silicon carbide single crystal ingot. In this manufacturing apparatus, a graphite crucible 1 (hereinafter referred to as “crucible”) is placed in a double quartz tube 13. ) And a graphite heat insulating material 5 covering the crucible 1 so as to surround the crucible 1, and the crucible 1 is provided with a graphite lid member 1a. Further, an induction heating coil 17 of high frequency induction heating means for heating the crucible 1 functioning as a heat generating member is installed outside the double quartz tube 13.

なお、坩堝１内には、その下部（原料装填部）に炭化珪素結晶粉末からなる炭化珪素原料３（以下、「坩堝内原料」と略す。）が装填されており、また、その内部上方〔蓋部材（黒鉛製の坩堝蓋）1a〕には、炭化珪素単結晶からなる種結晶２が取り付けられている。また、図１において、符号６は切欠き孔、符号10は坩堝支持体、符号14は真空排気装置、符号15はArガス配管、符号16はArガス用マスフローコントローラをそれぞれ示し、前記誘導加熱コイル17には高周波電流を流すための図示外の高周波電源が取り付けられている。 In addition, in the crucible 1, a silicon carbide raw material 3 made of silicon carbide crystal powder (hereinafter abbreviated as “raw material in the crucible”) is loaded in the lower part (raw material loading part), and the inside upper part [ A seed crystal 2 made of a silicon carbide single crystal is attached to a lid member (graphite crucible lid) 1a]. In FIG. 1, reference numeral 6 denotes a notch, reference numeral 10 denotes a crucible support, reference numeral 14 denotes a vacuum exhaust device, reference numeral 15 denotes an Ar gas pipe, reference numeral 16 denotes an Ar gas mass flow controller, and the induction heating coil A high-frequency power source (not shown) for supplying a high-frequency current is attached to 17.

この製造装置において、二重石英管13内部は、真空排気装置14により高真空排気（10^-3Pa以下）することができ、かつArガス配管15とArガス用マスフローコントローラ16を用いて、内部雰囲気をArガスにより圧力制御することができるようになっている。そして、坩堝１の温度の計測は、坩堝１の上下部を覆う黒鉛製の断熱材５の中央部にそれぞれ光路を設け、坩堝１の上部（蓋部材1a）及び下部（底壁部）からの光を取り出し、二色温度計を用いて行い、坩堝1下部（底壁部）の温度を原料温度とし、坩堝１上部（蓋部材1a）の温度から種結晶２の温度を判断する。 In this manufacturing apparatus, the inside of the double quartz tube 13 can be evacuated to a high vacuum (10 ⁻³ Pa or less) by the vacuum exhaust device 14, and the Ar gas pipe 15 and the Ar gas mass flow controller 16 are used to The pressure of the atmosphere can be controlled with Ar gas. Then, the temperature of the crucible 1 is measured by providing an optical path at the center of the graphite heat insulating material 5 covering the upper and lower portions of the crucible 1, and from the upper part (lid member 1a) and the lower part (bottom wall part) of the crucible 1. The light is extracted and the temperature is measured using a two-color thermometer. The temperature at the lower part of the crucible 1 (bottom wall) is used as the raw material temperature, and the temperature of the seed crystal 2 is determined from the temperature at the upper part of the crucible 1 (lid member 1a).

種結晶２上に炭化珪素単結晶の結晶成長をさせるためには、坩堝1内部の上下方向に温度勾配を形成し、坩堝内原料３部分の温度を高くし、種結晶２の結晶成長部分の温度を相対的に低くして再結晶させる必要がある。つまり、坩堝1の中では坩堝内原料３から種結晶２に向かう熱の流れを形成する必要がある。 In order to grow a silicon carbide single crystal on the seed crystal 2, a temperature gradient is formed in the vertical direction inside the crucible 1, the temperature of the raw material 3 portion in the crucible is increased, and the crystal growth portion of the seed crystal 2 is increased. It is necessary to recrystallize at a relatively low temperature. That is, in the crucible 1, it is necessary to form a heat flow from the raw material 3 in the crucible toward the seed crystal 2.

ここで、従来の方法では、坩堝１の側壁部で高周波誘導により発生した熱を、坩堝内原料３の内部へ伝達させ、次に種結晶２を経由させて系外へと放出させているが、坩堝内原料３では、その外周部（坩堝の側壁部近傍の部分）の温度が高く、中心部（坩堝の中心軸近傍の部分）に向かって温度が低下し、更に、種結晶２に向かって温度勾配が発生する。そして、このような高周波誘導加熱では、発熱部材である黒鉛製の坩堝1の側壁部は加熱され易いが、坩堝１内に装填された坩堝内原料３の中心部は、坩堝１の側壁部に近い外周部に比べて加熱され難く、坩堝１の底壁部1bの中央部分近傍を効果的に加熱することは難しい。 Here, in the conventional method, heat generated by high frequency induction at the side wall portion of the crucible 1 is transmitted to the inside of the raw material 3 in the crucible, and then released to the outside through the seed crystal 2. In the raw material 3 in the crucible, the temperature of the outer peripheral portion (portion near the side wall of the crucible) is high, the temperature decreases toward the central portion (portion near the central axis of the crucible), and further toward the seed crystal 2. Temperature gradient occurs. In such high-frequency induction heating, the side wall portion of the graphite crucible 1 which is a heat generating member is easily heated, but the central portion of the raw material 3 in the crucible loaded in the crucible 1 is placed on the side wall portion of the crucible 1. It is difficult to heat compared to the near outer peripheral portion, and it is difficult to effectively heat the vicinity of the central portion of the bottom wall portion 1b of the crucible 1.

そこで、本発明においては、坩堝１の側壁部を高周波誘導加熱手段で加熱するだけでなく、坩堝１の底壁部1b中央部分をその外面側から加熱することにより、種結晶２上での結晶成長に必要な温度勾配を維持しつつ、従来は困難であった、坩堝１の底壁部1b中央部分に接する坩堝内原料３の中央部を効率的に昇華させることにその特徴がある。
そして、本発明において、前記坩堝１の底壁部1b中央部分をその外側から加熱する手段については、特に制限されるものではなく、坩堝１の底壁部1b中央部分を効率的に加熱できれば如何なる加熱手段でもよいが、設備の変更が最少で済む高周波誘導加熱手段であることが最も好ましい。そして、この高周波誘導加熱手段で坩堝１の底壁部1b中央部分をその外面側から加熱することができるように、坩堝１の底壁部1b中央部分の外面側には高周波誘導加熱で発熱する発熱部材20を接触させて配置し、この発熱部材20を高周波加熱することにより、坩堝１の底壁部1b中央部分をその外面側から加熱するのがよい。 Therefore, in the present invention, not only the side wall portion of the crucible 1 is heated by the high frequency induction heating means, but also the center portion of the bottom wall portion 1b of the crucible 1 is heated from the outer surface side, thereby crystal on the seed crystal 2 It is characterized by efficiently sublimating the central portion of the raw material 3 in the crucible that is in contact with the central portion of the bottom wall portion 1b of the crucible 1, while maintaining a temperature gradient necessary for growth.
In the present invention, the means for heating the central portion of the bottom wall portion 1b of the crucible 1 is not particularly limited, and any means can be used as long as the central portion of the bottom wall portion 1b of the crucible 1 can be efficiently heated. Although a heating means may be used, it is most preferable to be a high-frequency induction heating means that requires minimal equipment change. And so that the center part of the bottom wall 1b of the crucible 1 can be heated from the outer surface side by this high frequency induction heating means, heat is generated by high frequency induction heating on the outer surface side of the center part of the bottom wall 1b of the crucible 1. It is preferable to heat the heat generating member 20 in contact with the heat generating member 20 and heat the heat generating member 20 at a high frequency to heat the central portion of the bottom wall 1b of the crucible 1 from the outer surface side.

また、本発明において、前記発熱部材20については、その機能が達成されれば特に材質が限定されるものではないが、昇華再結晶法を行うために必要な高温で機能する材料であって、成長する炭化珪素単結晶の不純物とならない材料であることから、黒鉛材料で形成されることが望ましい。この発熱部材20として坩堝１とは異なる電気抵抗の黒鉛材料を用いることは、誘導電流により引き起こされる発熱部材20の周縁部での発熱を制御することができ、特に坩堝１より低い電気抵抗率の発熱部材20を用いて発熱部材20の周縁部での発熱をより高くすることは有効である。 In the present invention, the heat generating member 20 is not particularly limited as long as the function is achieved, but is a material that functions at a high temperature necessary for performing the sublimation recrystallization method, Since it is a material that does not become an impurity of the growing silicon carbide single crystal, it is preferably formed of a graphite material. The use of a graphite material having an electric resistance different from that of the crucible 1 as the heat generating member 20 can control the heat generation at the peripheral edge of the heat generating member 20 caused by the induced current, and in particular, has an electric resistivity lower than that of the crucible 1. It is effective to increase the heat generation at the peripheral edge of the heat generating member 20 by using the heat generating member 20.

本発明において、坩堝１の底壁部1b中央部分を加熱するための発熱部材20については、底壁部1b中央部分のみを効果的に加熱するために、好ましくは、図２に示すように、坩堝１の底壁部1bと発熱部材20との間に加熱補助部21を設け、高周波誘導加熱により発熱部材20で発生した熱が、この加熱補助部21を経由して底壁部1b中央部分に効果的に伝達されると共に、底壁部1bの周縁部にはできるだけ伝達されないようにするのが望ましい。このような構成にすることで、従来加熱され易かった坩堝内原料３の外周部下部に伝達される熱を可及的に抑制し、この坩堝内原料３の外周部での高温化を抑制すると同時に、発熱部材20の周縁部での発熱を坩堝１の底壁部1b中央部分に効率的に伝達し、坩堝内原料３の中心部に多くの熱が流れるような加熱状態を形成することができ、結晶成長に必要な温度勾配を維持しつつ、坩堝内原料３の外周部から中心部にかけての温度をより均一化し、有効に原料ガスを昇華させることができる。 In the present invention, the heating member 20 for heating the central portion of the bottom wall portion 1b of the crucible 1 is preferably as shown in FIG. 2 in order to effectively heat only the central portion of the bottom wall portion 1b. A heating auxiliary portion 21 is provided between the bottom wall portion 1b of the crucible 1 and the heat generating member 20, and the heat generated in the heat generating member 20 by high-frequency induction heating passes through the heating auxiliary portion 21 to the central portion of the bottom wall portion 1b. It is desirable to transmit to the peripheral edge of the bottom wall 1b as much as possible. By adopting such a configuration, heat transmitted to the lower part of the outer periphery of the crucible raw material 3 that has been easily heated in the past is suppressed as much as possible, and high temperature at the outer peripheral part of the raw material 3 in the crucible is suppressed. At the same time, the heat generated at the peripheral edge of the heat generating member 20 can be efficiently transmitted to the central portion of the bottom wall 1b of the crucible 1 to form a heating state in which a large amount of heat flows through the central portion of the raw material 3 in the crucible. In addition, while maintaining the temperature gradient necessary for crystal growth, the temperature from the outer peripheral part to the central part of the raw material 3 in the crucible can be made more uniform, and the raw material gas can be sublimated effectively.

そして、上記の加熱補助部21については、坩堝１の底壁部1b及び発熱部材20と別体に形成してこれら坩堝１の底壁部1b及び発熱部材20の間に配設してもよく、また、坩堝１の底壁部1bと一体に形成したり、発熱部材20と一体に形成したり、あるいは、厚さ方向に２分割してその一方を坩堝１の底壁部1bと一体に形成すると共に他方を発熱部材20と一体に形成してもよい。また、この加熱補助部21については、坩堝１の底壁部1b及び／又は発熱部材20と同じ材料で形成することができるほか、耐熱性及び熱伝導性に優れた別の材料で形成してもよく、特に熱伝導性に優れた材料で形成することは、発熱用部材20で発生した熱を底壁部1b中央部分に効果的に伝達し、坩堝内原料３の中心部に効率的に伝導する上で有効である。 The heating auxiliary portion 21 may be formed separately from the bottom wall portion 1b of the crucible 1 and the heat generating member 20 and disposed between the bottom wall portion 1b of the crucible 1 and the heat generating member 20. Further, it is formed integrally with the bottom wall portion 1b of the crucible 1, formed integrally with the heat generating member 20, or divided into two in the thickness direction and one of them is integrated with the bottom wall portion 1b of the crucible 1. The other may be formed integrally with the heat generating member 20. The auxiliary heating portion 21 can be formed of the same material as the bottom wall portion 1b and / or the heat generating member 20 of the crucible 1, and is formed of another material having excellent heat resistance and thermal conductivity. In particular, the formation of a material having excellent thermal conductivity effectively transfers the heat generated by the heat generating member 20 to the central portion of the bottom wall portion 1b, and efficiently to the central portion of the raw material 3 in the crucible. It is effective in conducting.

また、前記坩堝１の底壁部1bと発熱部材20との間において発熱部材20の外周面側に形成される空隙部には、図２に示すように、発熱部材20で発生した熱が坩堝１の底壁部1bの周縁部を介して坩堝内原料３の外周部底壁部側に直接伝達しないように、坩堝１の底壁部1bの周縁部下面と発熱部材20の周縁部上面との間に、前記加熱補助部21の外周面を取り囲むように断熱材5ｂを設置し、これらの間を熱的に分離すると共に、発熱部材20で発生した熱が坩堝内原料３の中心部底壁部側に集中的に伝達するような構造とすることが更に好ましい。そして、坩堝１の底壁部1bと発熱部材20との間に配設される加熱補助部21については、その厚さＴにより前記断熱材5ｂの厚さが決まるので、この断熱材5ｂにより坩堝１の底壁部1b周縁部下面と発熱部材20の周縁部上面との間を効果的に断熱するため、好ましくは１０mm以上、より好ましくは２０mm以上６０mm以下の範囲の大きさにするのがよい。 Further, in the gap formed on the outer peripheral surface side of the heat generating member 20 between the bottom wall portion 1b of the crucible 1 and the heat generating member 20, as shown in FIG. The lower surface of the peripheral edge of the bottom wall 1b of the crucible 1 and the upper surface of the peripheral edge of the heating member 20 are not directly transmitted to the outer peripheral bottom wall of the crucible raw material 3 through the peripheral edge of the bottom wall 1b. In between, the heat insulating material 5b is installed so as to surround the outer peripheral surface of the auxiliary heating portion 21 and the space between them is thermally separated, and the heat generated by the heating member 20 is the bottom of the central portion of the raw material 3 in the crucible. It is further preferable to adopt a structure in which transmission is concentrated on the wall side. And about the heating auxiliary | assistant part 21 arrange | positioned between the bottom wall part 1b of the crucible 1 and the heat generating member 20, since the thickness of the said heat insulating material 5b is decided by the thickness T, this crucible 5b uses this heat insulating material 5b. In order to effectively insulate between the bottom surface of the bottom wall 1b and the upper surface of the peripheral portion of the heat generating member 20, the size is preferably 10 mm or more, more preferably 20 mm or more and 60 mm or less. .

更に、本発明において、前記坩堝１内に装填された坩堝内原料３の中央部をその下方から加熱するために、坩堝１の底壁部1bの外面側に配置された前記発熱部材20が接触する底壁部1bの中央部分の大きさ（坩堝内原料の加熱部比率）については、この底壁部1b中央部分の外面側形状が円形状であるとして、坩堝１の底壁部1bの外径（すなわち、坩堝１の外径）(Ｄb)に対して前記底壁部1b中央部分の直径(Ｄc)の加熱部比率（Ｄc／Ｄb）が０．３以上０．８以下であるのがよい。この坩堝内原料３の加熱部比率（Ｄc／Ｄb）が０．３よりも小さい場合には、坩堝内原料３の中心部に十分な熱を伝達することができず、坩堝１の側壁部での発熱の寄与が坩堝1の底壁部1b中央部分を通して供給される熱に比べて大きくなり、反対に、この加熱部比率（Ｄc／Ｄb）が０．８よりも大きい場合には、底壁部1b中央部分以外の部分にも熱が供給されるため、坩堝内原料３の中心部のみに熱を供給することができず、従来と同様に坩堝内原料３の外周部底壁部側の温度が高くなり、坩堝内原料３の中心部の温度が外周部の温度に比べて低くなり、本発明の効果が得られなくなる場合がある。 Further, in the present invention, the heating member 20 arranged on the outer surface side of the bottom wall portion 1b of the crucible 1 is brought into contact with the crucible 1 in order to heat the central portion of the raw material 3 in the crucible 1 loaded from below. As for the size of the central portion of the bottom wall portion 1b to be heated (ratio of the heated portion of the raw material in the crucible), the outer surface side shape of the central portion of the bottom wall portion 1b is assumed to be circular. The heating portion ratio (Dc / Db) of the diameter (Dc) of the center portion of the bottom wall portion 1b to the diameter (that is, the outer diameter of the crucible 1) (Db) is 0.3 to 0.8. Good. When the heating portion ratio (Dc / Db) of the raw material 3 in the crucible is smaller than 0.3, sufficient heat cannot be transmitted to the central portion of the raw material 3 in the crucible, and the side wall portion of the crucible 1 If the heating part ratio (Dc / Db) is larger than 0.8, the contribution of the heat generated in the crucible 1 is larger than the heat supplied through the center part of the bottom wall part 1b of the crucible 1. Since heat is also supplied to parts other than the central part of the part 1b, heat cannot be supplied only to the central part of the raw material 3 in the crucible, and on the bottom wall side of the outer peripheral part of the raw material 3 in the crucible as in the past. The temperature increases, the temperature of the central portion of the raw material 3 in the crucible becomes lower than the temperature of the outer peripheral portion, and the effect of the present invention may not be obtained.

高周波誘導加熱においては、発熱部材20の周縁部において誘導電流が最も多く流れ、発熱が大きくなる。このことから、発熱部材20の直径を大きくし、誘導加熱コイルの径に近づけるほど発熱が大きくなる。発熱部材20の発熱を増やし、その熱を坩堝内原料３の中心部に伝達する効果をより発現させるためには、発熱部材20の直径を坩堝１に比べてより大きくすることが有効である。しかしながら、この発熱部材20の直径を大きくした場合には、誘導加熱コイルの径を大きくすることが必要になり、装置の大型化が必要になる。このため、装置の大型化を抑制しつつ本発明の効果を高めるために、発熱部材20の直径については、坩堝１の直径の１倍以上１．５倍以下の範囲に設定することが好ましい。 In the high-frequency induction heating, the induced current flows most in the peripheral portion of the heat generating member 20, and the heat generation increases. From this, the heat generation becomes larger as the diameter of the heat generating member 20 is increased and closer to the diameter of the induction heating coil. In order to increase the heat generation of the heat generating member 20 and to exhibit the effect of transmitting the heat to the central part of the raw material 3 in the crucible, it is effective to make the diameter of the heat generating member 20 larger than that of the crucible 1. However, when the diameter of the heat generating member 20 is increased, it is necessary to increase the diameter of the induction heating coil, and it is necessary to increase the size of the apparatus. For this reason, in order to increase the effect of the present invention while suppressing an increase in the size of the apparatus, the diameter of the heat generating member 20 is preferably set in the range of 1 to 1.5 times the diameter of the crucible 1.

また、坩堝1内部の温度勾配は熱の流れの方向と同じである。従って、発熱部材20で発生した熱は、坩堝１の中心部に流れ、坩堝内原料３を通り、生成した炭化珪素単結晶インゴット４、種結晶２を通り、坩堝１の蓋部材1aから系外に放出される。このとき、坩堝内原料３から炭化珪素単結晶インゴット４、種結晶２の向きに坩堝１内部の温度勾配が形成される。詳細に見ると、坩堝１の側壁部での誘導電流による発熱は、坩堝内原料３を通り、炭化珪素単結晶インゴット４、種結晶２の向きに流れており、坩堝内原料３の部分では坩堝内原料３の外周部からその中心部に向かって温度が低下する温度勾配を形成する熱の流れがある。この熱の流れを制御し、坩堝内原料３内部の径方向の温度勾配を小さくするために、坩堝１で発生した熱が、坩堝１の側壁部に配置された断熱材５を通じて、系外に放出される熱量を増大させることが有効である。このことから、本発明においては、坩堝１の側壁部を覆う断熱材５の厚さが前記発熱部材20の側面を覆う断熱材の厚さの０．６倍以上１倍以下であることが望ましい。 The temperature gradient inside the crucible 1 is the same as the direction of heat flow. Accordingly, the heat generated in the heat generating member 20 flows to the center of the crucible 1, passes through the raw material 3 in the crucible, passes through the generated silicon carbide single crystal ingot 4 and seed crystal 2, and is removed from the lid member 1 a of the crucible 1. To be released. At this time, a temperature gradient in the crucible 1 is formed from the raw material 3 in the crucible toward the silicon carbide single crystal ingot 4 and the seed crystal 2. More specifically, the heat generated by the induced current in the side wall of the crucible 1 passes through the raw material 3 in the crucible and flows in the direction of the silicon carbide single crystal ingot 4 and the seed crystal 2. There is a heat flow that forms a temperature gradient in which the temperature decreases from the outer peripheral portion of the inner raw material 3 toward the central portion thereof. In order to control this heat flow and reduce the temperature gradient in the radial direction inside the raw material 3 in the crucible, the heat generated in the crucible 1 passes through the heat insulating material 5 disposed on the side wall of the crucible 1 to the outside of the system. It is effective to increase the amount of heat released. Therefore, in the present invention, it is desirable that the thickness of the heat insulating material 5 covering the side wall portion of the crucible 1 is not less than 0.6 times and not more than 1 time the thickness of the heat insulating material covering the side surface of the heat generating member 20. .

本発明の製造方法で成長高さが４０mm以上２００mm以下の炭化珪素単結晶インゴットを製造した場合には、坩堝1内に装填した坩堝内原料３を有効に利用することができ、また、結晶成長中の結晶成長速度の変動が小さくなって高品質の炭化珪素単結晶を得ることができる。このため、電子材料用の炭化珪素単結晶を効率良く作製することが可能な炭化珪素単結晶インゴットをより安価に製造することができる。 When a silicon carbide single crystal ingot having a growth height of 40 mm or more and 200 mm or less is manufactured by the manufacturing method of the present invention, the raw material 3 in the crucible loaded in the crucible 1 can be used effectively, and the crystal growth The fluctuation of the crystal growth rate therein becomes small, and a high-quality silicon carbide single crystal can be obtained. For this reason, the silicon carbide single crystal ingot which can produce the silicon carbide single crystal for electronic materials efficiently can be manufactured more cheaply.

〔実施例１〕
図３に示すように、黒鉛製の坩堝１の底壁部1bには、その中央部分の下面側に加工を施し、坩堝内原料３が坩堝１の底壁部1b中央部分を介して下方側から加熱される坩堝内原料３の加熱部比率〔坩堝１の底壁部1b中央部分の直径（Ｄc）／坩堝１の底壁部1bの外径（Ｄb）〕が０．５であって厚さが１５mmである加熱補助部21を形成した。また、前記坩堝1と同じ黒鉛材料を用い、坩堝１の直径の１．２倍の直径を有する発熱部材20を形成し、前記加熱補助部21の下面とこの発熱部材20の中央部上面とが接触するように配置して密着させた。また、断熱材５については、その外形が坩堝１と発熱部材20の側部において同じ径となるように形成すると共に、坩堝1の底壁部1bと発熱部材20との間において加熱補助部21の外周面側に形成される空隙部内には断熱材5bを充填した。 [Example 1]
As shown in FIG. 3, the bottom wall 1 b of the graphite crucible 1 is processed on the lower surface side of the central portion thereof, and the raw material 3 in the crucible is placed on the lower side through the central portion of the bottom wall 1 b of the crucible 1. The ratio of the heated portion of the raw material 3 in the crucible heated from [the diameter (Dc) of the central portion of the bottom wall portion 1b of the crucible 1 / the outer diameter (Db) of the bottom wall portion 1b of the crucible 1] is 0.5 and is thick A heating auxiliary portion 21 having a length of 15 mm was formed. Further, the same graphite material as that of the crucible 1 is used to form a heat generating member 20 having a diameter that is 1.2 times the diameter of the crucible 1, and the lower surface of the heating auxiliary portion 21 and the upper surface of the central portion of the heat generating member 20 are formed. It arranged so that it might contact and it stuck. Further, the heat insulating material 5 is formed so that the outer shape thereof has the same diameter at the side portions of the crucible 1 and the heat generating member 20, and the heating auxiliary portion 21 is provided between the bottom wall portion 1 b of the crucible 1 and the heat generating member 20. A heat insulating material 5b was filled in the gap formed on the outer peripheral surface side of the inner surface.

この実施例１の製造装置において、坩堝１の容器内下部には、アチソン法により作製された炭化珪素結晶粉末からなる炭化珪素原料３．０kgを装填し、坩堝内原料３とした。また、坩堝１の蓋部材1aには、種結晶２として口径１０５mmの(0001)面を有する４Ｈポリタイプの炭化珪素単結晶ウェハを配置した。 In the manufacturing apparatus of Example 1, 3.0 kg of a silicon carbide raw material made of silicon carbide crystal powder produced by the Atchison method was loaded in the lower part of the crucible 1 in the container, and the raw material 3 in the crucible was obtained. In addition, a 4H polytype silicon carbide single crystal wafer having a (0001) plane having a diameter of 105 mm was disposed as a seed crystal 2 on the lid member 1a of the crucible 1.

このようにして準備された坩堝１等からなる部材を、図１に示すように、二重石英管13の内部に設置し、前記手順で常法に従って炭化珪素単結晶の結晶成長を行った。すなわち、原料温度を目標温度である２３００℃まで上昇させた後、二重石英管13内のＡrの圧力を成長圧力１．３kPaまで３０分かけて減圧し、炭化珪素単結晶の成長を開始させ、加熱を１４０時間継続して炭化珪素単結晶を成長させた。 The member composed of the crucible 1 and the like prepared in this manner was placed inside a double quartz tube 13 as shown in FIG. 1, and a silicon carbide single crystal was grown according to a conventional method according to the above procedure. That is, after raising the raw material temperature to the target temperature of 2300 ° C., the pressure of Ar in the double quartz tube 13 is reduced to a growth pressure of 1.3 kPa over 30 minutes to start the growth of the silicon carbide single crystal. The heating was continued for 140 hours to grow a silicon carbide single crystal.

その結果、成長速度は約０．５mm／時であって、炭化珪素単結晶の口径が１０５mm程度であり、かつ、高さが７０mm程度の単結晶インゴットが得られた。坩堝1内の炭化珪素原料の残渣を観察したところ、坩堝内原料３の中心部近傍においても原料が効率良く昇華したことが認められ、高周波誘導加熱の際に坩堝内原料３に対する加熱温度を効果的に制御することができ、結果として中心部近傍の炭化珪素原料も効率良く加熱できたことが判明した。また、得られた単結晶インゴットの重量は１．９kg程度であり、結晶化率は６５%であった。 As a result, a single crystal ingot having a growth rate of about 0.5 mm / hour, a silicon carbide single crystal diameter of about 105 mm, and a height of about 70 mm was obtained. When the residue of the silicon carbide raw material in the crucible 1 was observed, it was found that the raw material was efficiently sublimated even in the vicinity of the center of the raw material 3 in the crucible, and the heating temperature for the raw material 3 in the crucible was effective during high frequency induction heating. As a result, it was found that the silicon carbide raw material in the vicinity of the center could be heated efficiently. Further, the weight of the obtained single crystal ingot was about 1.9 kg, and the crystallization rate was 65%.

更に、得られた炭化珪素単結晶インゴットについて、Ｘ線回折及びラマン散乱により分析したところ、４Ｈの単一ポリタイプからなるインゴットであり、また、マイクロパイプ等の結晶欠陥が少ない極めて高品質であることが確認された。
このインゴットから切り出された炭化珪素単結晶基板は、電子デバイスを作製するための基板として有用である。 Furthermore, when the obtained silicon carbide single crystal ingot was analyzed by X-ray diffraction and Raman scattering, it was an ingot consisting of a single polytype of 4H, and it was extremely high quality with few crystal defects such as micropipes. It was confirmed.
The silicon carbide single crystal substrate cut out from the ingot is useful as a substrate for manufacturing an electronic device.

〔実施例２〕
実施例２においては、上記実施例１の場合とは異なり、図４に示すように、黒鉛製の坩堝１の底壁部1bには加工を施すことなく、黒鉛材料で形成された発熱部材20側に加工を施し、坩堝内原料３の加熱部比率〔坩堝１の底壁部1b中央部分の直径（Ｄc）／坩堝１の底壁部1bの外径（Ｄb）〕が０．４であって厚さが３０mmである加熱補助部21を形成した。そして、この発熱部材20については、坩堝１より電気抵抗率の低い黒鉛材料を用いて、坩堝1の直径の1.３倍の大きさに形成し、その加熱補助部21の上面が坩堝１の底壁部1b中央部分の下面に接するように配設し密着させた。また、断熱材５については、その外形が坩堝１と発熱部材20の側部において同じ径となるように形成すると共に、坩堝1の底壁部1bと発熱部材20との間において加熱補助部21の外周面側に形成される空隙部内には断熱材5bを充填した。 [Example 2]
In the second embodiment, unlike the first embodiment, as shown in FIG. 4, the bottom wall portion 1b of the graphite crucible 1 is not processed, and the heating member 20 made of a graphite material is used. The ratio of the heated portion of the raw material 3 in the crucible [the diameter (Dc) of the central portion of the bottom wall 1b of the crucible 1 / the outer diameter (Db) of the bottom wall 1b of the crucible 1] of 0.4 was 0.4. Thus, the heating auxiliary part 21 having a thickness of 30 mm was formed. The heating member 20 is formed to be 1.3 times the diameter of the crucible 1 using a graphite material having a lower electrical resistivity than the crucible 1, and the upper surface of the heating auxiliary portion 21 is the crucible 1. The bottom wall portion 1b was disposed and brought into close contact with the lower surface of the central portion. Further, the heat insulating material 5 is formed so that the outer shape thereof has the same diameter at the side portions of the crucible 1 and the heat generating member 20, and the heating auxiliary portion 21 is provided between the bottom wall portion 1 b of the crucible 1 and the heat generating member 20. A heat insulating material 5b was filled in the gap formed on the outer peripheral surface side of the inner surface.

この実施例２の製造装置において、坩堝１の容器内下部には、アチソン法により作製された炭化珪素結晶粉末からなる炭化珪素原料６．１kgを装填し、坩堝内原料３とした。また、坩堝１の蓋部材1aには、種結晶２として口径１５５mmの(0001)面を有する４Ｈポリタイプの炭化珪素単結晶ウェハを配置した。 In the manufacturing apparatus of Example 2, 6.1 kg of silicon carbide raw material made of silicon carbide crystal powder produced by the Atchison method was loaded in the lower part of the crucible 1 in the container, and the raw material 3 in the crucible was obtained. In addition, a 4H polytype silicon carbide single crystal wafer having a (0001) plane having a diameter of 155 mm was disposed as a seed crystal 2 on the lid member 1a of the crucible 1.

その結果、成長速度は約０．５mm／時であって、結晶の口径が１５５mm程度であり、かつ、高さが７０mm程度の炭化珪素単結晶インゴットが得られた。坩堝1内の炭化珪素原料の残渣を観察したところ、坩堝内原料３の中心部近傍においても炭化珪素原料が効率良く昇華したことが認められ、高周波誘導加熱の際に坩堝内原料３に対する加熱温度を効果的に制御することができ、結果として中心部近傍の炭化珪素原料も効率良く加熱できたことが判明した。また、得られた単結晶インゴットの重量は４．２kg程度であり、結晶化率は７０%であった。 As a result, a silicon carbide single crystal ingot having a growth rate of about 0.5 mm / hour, a crystal diameter of about 155 mm, and a height of about 70 mm was obtained. When the residue of the silicon carbide raw material in the crucible 1 was observed, it was found that the silicon carbide raw material was efficiently sublimated even in the vicinity of the center of the raw material 3 in the crucible, and the heating temperature for the raw material 3 in the crucible during high frequency induction heating As a result, it was found that the silicon carbide raw material in the vicinity of the center could also be heated efficiently. Further, the weight of the obtained single crystal ingot was about 4.2 kg, and the crystallization rate was 70%.

〔実施例３〕
実施例３においては、上記実施例１の場合とは異なり、図５に示すように、黒鉛製の坩堝１の底壁部1bにはその中央部分の下面側に加工を施して坩堝１より熱伝導率の高い黒鉛材料製の加熱補助部21の一部を形成し、また、坩堝１と同じ黒鉛材料で形成された発熱部材20側に加工を施して坩堝１より熱伝導率の高い黒鉛材料製の加熱補助部21の一部を形成し、これら坩堝１の底壁部1b中央部分の下面側に形成された加熱補助部21の一部と発熱部材20側に形成された加熱補助部21の一部とが接するように配置して密着させ、坩堝１の底壁部1bと発熱部材20との間に坩堝１より熱伝導率の高い加熱補助部21が形成されるようにした。ここで、前記加熱補助部21は、その坩堝内原料３の加熱部比率〔坩堝１の底壁部1b中央部分の直径（Ｄc）／坩堝１の底壁部1bの外径（Ｄb）〕が０．７であって厚さが４０mmであるように形成し、また、前記発熱部材20は、その直径が坩堝1の直径の１．１倍の大きさに形成し、更に、断熱材５については、その厚さが坩堝１の側壁部と発熱部材20の側部とにおいて同じ厚さとなるように形成すると共に、坩堝1の底壁部1bと発熱部材20との間において加熱補助部21の外周面側に形成される空隙部内には断熱材5bを充填した。 Example 3
In the third embodiment, unlike the first embodiment, as shown in FIG. 5, the bottom wall 1b of the graphite crucible 1 is processed on the lower surface side of the center portion to heat the bottom wall 1b from the crucible 1. A part of the heating auxiliary portion 21 made of a graphite material having a high conductivity is formed, and a graphite material having a heat conductivity higher than that of the crucible 1 by processing the heat generating member 20 side made of the same graphite material as the crucible 1 A part of the heating auxiliary part 21 is formed, and a part of the heating auxiliary part 21 formed on the lower surface side of the central part of the bottom wall 1b of the crucible 1 and the heating auxiliary part 21 formed on the heating member 20 side are formed. The heating auxiliary portion 21 having a higher thermal conductivity than the crucible 1 is formed between the bottom wall portion 1 b of the crucible 1 and the heat generating member 20. Here, the heating auxiliary part 21 has a heating part ratio of the raw material 3 in the crucible [diameter (Dc) of the central part of the bottom wall 1b of the crucible 1 / outer diameter (Db) of the bottom wall 1b of the crucible 1]. The heat generating member 20 is formed to have a diameter 1.1 times the diameter of the crucible 1, and the heat insulating material 5 is further formed. Is formed so that the thickness thereof is the same in the side wall portion of the crucible 1 and the side portion of the heating member 20, and between the bottom wall portion 1 b of the crucible 1 and the heating member 20, A heat insulating material 5b was filled in the gap formed on the outer peripheral surface side.

この実施例３の製造装置において、坩堝１の容器内下部には、アチソン法により作製された炭化珪素結晶粉末からなる炭化珪素原料８．８kgを装填し、坩堝内原料３とした。また、坩堝１の蓋部材1aには、種結晶２として口径１５５mmの(0001)面を有する４Ｈポリタイプの炭化珪素単結晶ウェハを配置した。 In the manufacturing apparatus of Example 3, 8.8 kg of a silicon carbide raw material made of silicon carbide crystal powder produced by the Atchison method was charged in the lower part of the crucible 1 in the container, and the raw material 3 in the crucible was obtained. In addition, a 4H polytype silicon carbide single crystal wafer having a (0001) plane having a diameter of 155 mm was disposed as a seed crystal 2 on the lid member 1a of the crucible 1.

このようにして準備された坩堝１等からなる部材を、図１に示すように、二重石英管13の内部に設置し、前記手順で常法に従って炭化珪素単結晶の結晶成長を行った。すなわち、原料温度を目標温度である２３００℃まで上昇させた後、二重石英管13内のＡrの圧力を成長圧力１．３kPaまで３０分かけて減圧し、結晶の成長を開始させ、加熱を２２０時間継続して結晶を成長させた。 The member composed of the crucible 1 and the like prepared in this manner was placed inside a double quartz tube 13 as shown in FIG. 1, and a silicon carbide single crystal was grown according to a conventional method according to the above procedure. That is, after raising the raw material temperature to the target temperature of 2300 ° C., the pressure of Ar in the double quartz tube 13 is reduced to a growth pressure of 1.3 kPa over 30 minutes to start crystal growth and heating. Crystals were grown for 220 hours continuously.

その結果、成長速度は約０．５mm／時であって、結晶の口径が１５５mm程度であり、かつ、高さが１１０mm程度の炭化珪素単結晶インゴットが得られた。坩堝１内の炭化珪素原料の残渣を観察したところ、坩堝内原料３の中心部近傍においても炭化珪素原料が効率良く昇華したことが認められ、高周波誘導加熱の際に坩堝内原料３に対する加熱温度を効果的に制御することができ、結果として中心部近傍の炭化珪素原料も効率良く加熱できたことが判明した。また、得られた単結晶インゴットの重量は６．６kg程度であり、結晶化率は７５%であった。 As a result, a silicon carbide single crystal ingot having a growth rate of about 0.5 mm / hour, a crystal diameter of about 155 mm, and a height of about 110 mm was obtained. When the residue of the silicon carbide raw material in the crucible 1 was observed, it was found that the silicon carbide raw material was efficiently sublimated even in the vicinity of the center of the raw material 3 in the crucible, and the heating temperature for the raw material 3 in the crucible during high frequency induction heating As a result, it was found that the silicon carbide raw material in the vicinity of the center could also be heated efficiently. Moreover, the weight of the obtained single crystal ingot was about 6.6 kg, and the crystallization rate was 75%.

〔比較例１〕
実施例１と比較するために、坩堝１の底壁部1b中央部分の加工や、発熱部材20の使用を行わずに、従来と同じ製造装置を用いて、実施例１と同じ操業条件にて炭化珪素単結晶インゴットの製造を行った。
その結果、結晶の口径が１０５mm程度であり、かつ、高さが２０mm程度のインゴットが得られた。坩堝1内の炭化珪素原料の残渣を観察したところ、坩堝内原料３の中心部で炭化珪素原料の再結晶が観察された。これは、坩堝内原料３の中心部の炭化珪素原料が有効に加熱されなかったために、坩堝内原料３の外周部で昇華した原料ガスが結晶成長に利用されずに、坩堝内原料３の中心部で再結晶化したものと考えられる。 [Comparative Example 1]
In order to compare with Example 1, without processing the bottom wall 1b center part of the crucible 1 and using the heat generating member 20, using the same manufacturing equipment as in the past, under the same operating conditions as in Example 1. A silicon carbide single crystal ingot was manufactured.
As a result, an ingot having a crystal diameter of about 105 mm and a height of about 20 mm was obtained. When the residue of the silicon carbide raw material in the crucible 1 was observed, recrystallization of the silicon carbide raw material was observed at the center of the raw material 3 in the crucible. This is because the silicon carbide raw material at the center of the raw material 3 in the crucible was not heated effectively, so that the raw material gas sublimated at the outer periphery of the raw material 3 in the crucible was not used for crystal growth, and the center of the raw material 3 in the crucible It is thought that it was recrystallized in part.

この坩堝内原料３の中心部での昇華ガスの再結晶のため、結晶成長の途中で原料ガスの供給が途絶え、成長した結晶の成長面が昇華し、成長面が炭化した。そのため、インゴットの結晶化率は１９%と低い値であった。また、得られた炭化珪素単結晶インゴットは、インゴット高さが低く、電子デバイス作製時における基板切出しの歩留まりが低いだけでなく、装填した原料に対してインゴットの重量が小さく、上記各実施例１〜３の場合と比較して炭化珪素原料を有効に利用できなかった。 Due to recrystallization of the sublimation gas at the center of the raw material 3 in the crucible, the supply of the raw material gas was interrupted during the crystal growth, the growth surface of the grown crystal was sublimated, and the growth surface was carbonized. Therefore, the crystallization rate of the ingot was a low value of 19%. In addition, the obtained silicon carbide single crystal ingot not only has a low ingot height and a low substrate cutting yield when manufacturing an electronic device, but also has a small ingot weight relative to the loaded raw materials. As compared with the case of ~ 3, the silicon carbide raw material could not be effectively used.

１…坩堝、1a…坩堝の蓋部材、1b…坩堝の底壁部、２…種結晶、３…炭化珪素原料、４…炭化珪素単結晶インゴット、５…断熱材、６…切欠き孔、10…坩堝支持体、13…二重石英管、14…真空排気装置、15…Arガス配管、16…Arガス用マスフローコントローラ、17…誘導加熱コイル、20…発熱部材、21…加熱補助部。 DESCRIPTION OF SYMBOLS 1 ... Crucible, 1a ... Crucible lid member, 1b ... Crucible bottom wall part, 2 ... Seed crystal, 3 ... Silicon carbide raw material, 4 ... Silicon carbide single crystal ingot, 5 ... Insulating material, 6 ... Notched hole, 10 ... crucible support, 13 ... double quartz tube, 14 ... vacuum exhaust device, 15 ... Ar gas piping, 16 ... mass flow controller for Ar gas, 17 ... induction heating coil, 20 ... heating member, 21 ... heating auxiliary part.

Claims

A silicon carbide raw material is loaded in the lower part of a graphite crucible, the lower part of the crucible is heated by high-frequency induction heating means, the silicon carbide raw material is indirectly heated to generate sublimation gas, and is arranged opposite to the upper part of the crucible. In a method of producing a silicon carbide single crystal ingot by growing a silicon carbide single crystal by a sublimation recrystallization method of recrystallizing silicon carbide on a silicon carbide seed crystal,
A method for producing a silicon carbide single crystal ingot, comprising: heating a central portion of a silicon carbide raw material (raw crucible raw material) charged in the crucible from below through a central portion of a bottom wall portion of the crucible.

2. A silicon carbide single crystal ingot according to claim 1, wherein a heat generating member is disposed in contact with an outer surface of a central portion of the bottom wall of the crucible, and the heat generating member is heated by high frequency induction heating means. Method.

The heating part ratio (Dc) of the diameter (Dc) of the center part of the bottom wall part where the heating member arranged to supply heat from the outer surface side contacts the outer diameter (Db) of the bottom wall part of the crucible ( The method for producing a silicon carbide single crystal ingot according to claim 2, wherein Dc / Db) is 0.3 or more and 0.8 or less.

A seed crystal is arranged in the upper part of the crucible and a silicon carbide raw material is charged in the lower part, and the silicon carbide raw material (raw material in the crucible) charged in the crucible is heated by high frequency induction heating means to sublimate silicon carbide. In an apparatus for producing a silicon carbide single crystal ingot by recrystallization on the seed crystal,
A silicon carbide single crystal ingot characterized in that a heating member is provided in contact with the outer surface side of the central portion of the bottom wall of the crucible, and an induction heating coil of the high-frequency induction heating means is disposed so as to surround the heating member. Manufacturing equipment.

The heating part ratio (Dc) of the diameter (Dc) of the center part of the bottom wall part where the heating member arranged to supply heat from the outer surface side contacts the outer diameter (Db) of the bottom wall part of the crucible ( The apparatus for producing a silicon carbide single crystal ingot according to claim 4, wherein Dc / Db) is 0.3 or more and 0.8 or less.