JP3087065B1 - Method for growing liquid phase of single crystal SiC - Google Patents
Method for growing liquid phase of single crystal SiCInfo
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- JP3087065B1 JP3087065B1 JP11058254A JP5825499A JP3087065B1 JP 3087065 B1 JP3087065 B1 JP 3087065B1 JP 11058254 A JP11058254 A JP 11058254A JP 5825499 A JP5825499 A JP 5825499A JP 3087065 B1 JP3087065 B1 JP 3087065B1
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- sic
- single crystal
- powder
- crucible
- sio
- Prior art date
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Abstract
【要約】
【課題】 マイクロパイプ欠陥や結晶欠陥等の発生が少
ないとともに、Ｓｉ塊の封じ込みによる多結晶化もな
く、非常に高品質高性能で、かつ、バルク状の単結晶Ｓ
ｉＣを効率よく育成できるようにする。
【解決手段】 Ｃ原子を含む坩堝１内の底部に種結晶と
なるα−ＳｉＣ単結晶基板５を配置し、このα−ＳｉＣ
単結晶基板５の上面を覆うようにＳｉＯ2 粉末６を充填
するとともに、さらにその上部にＳｉＯ2 粉末とＳｉＣ
粉末の混合粉末７を充填した状態で、底部側が低温とな
るように上下の温度差を保ちながら不活性雰囲気中で加
熱し両粉末を分解させて得られるＣ原子を過剰に含むＳ
ｉ融液中にＳｉＣ単結晶基板５を所定時間に亘り浸漬保
持させることにより、ＳｉＣ単結晶基板５の表面に単結
晶を育成させる。Abstract: PROBLEM TO BE SOLVED: To produce micropipe defects, crystal defects, etc. with little occurrence, not to be polycrystallized by enclosing a Si lump, to have very high quality and high performance, and to obtain a bulk single crystal S
To be able to grow iC efficiently. SOLUTION: An α-SiC single crystal substrate 5 serving as a seed crystal is arranged at the bottom in a crucible 1 containing C atoms, and the α-SiC
SiO 2 powder 6 is filled so as to cover the upper surface of single crystal substrate 5, and SiO 2 powder and SiC
In a state where the mixed powder 7 of the powders is filled, the mixture is heated in an inert atmosphere while maintaining a temperature difference between the upper and lower sides so that the bottom side is at a low temperature, and an excess of C atoms obtained by decomposing both powders is obtained.
By immersing and holding the SiC single crystal substrate 5 in the i melt for a predetermined time, a single crystal is grown on the surface of the SiC single crystal substrate 5.
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、単結晶ＳｉＣの液
晶育成方法に関するもので、詳しくは、発光ダイオード
やＸ線光学素子、高温半導体電子素子の基板ウエハなど
として用いられる単結晶ＳｉＣの液相育成方法に関する
ものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for growing a liquid crystal of single crystal SiC, and more particularly, to a liquid phase of single crystal SiC used as a substrate wafer of a light emitting diode, an X-ray optical element, a high temperature semiconductor electronic element, and the like. It relates to the breeding method.
【０００２】[0002]
【従来の技術】ＳｉＣ（炭化珪素）は、耐熱性および機
械的強度に優れているだけでなく、放射線にも強く、さ
らに不純物の添加によって電子や正孔の価電子制御が容
易である上、広い禁制帯幅を持つ（因みに、６Ｈ型のＳ
ｉＣ単結晶で約３．０ｅＶ、４Ｈ型のＳｉＣ単結晶で
３．２６ｅＶ）ために、Ｓｉ（シリコン）やＧａＡｓ
（ガリウムヒ素）などの既存の半導体材料では実現する
ことができない高温、高周波、耐電圧、耐環境性を実現
することが可能で、次世代のパワーデバイス用半導体材
料として注目され、かつ期待されている。2. Description of the Related Art SiC (silicon carbide) is not only excellent in heat resistance and mechanical strength, but also resistant to radiation. In addition, it is easy to control valence electrons and holes by adding impurities. Has a wide forbidden band (By the way, 6H type S
about 3.0 eV for an iC single crystal and 3.26 eV for a 4H type SiC single crystal), such as Si (silicon) or GaAs.
(Gallium arsenide) and other high-temperature, high-frequency, withstand voltage, and environmental resistance that cannot be realized with existing semiconductor materials. I have.
【０００３】この種の単結晶ＳｉＣの育成方法として、
従来、黒鉛坩堝内の低温側に種結晶を固定配置し、高温
側に原料となるＳｉＣ粉末を挿入配置して黒鉛坩堝内を
不活性雰囲気中で２１００〜２４００℃の高温に加熱す
ることによって、上記ＳｉＣ粉末を昇華させて低温側の
種結晶の表面上で再結晶させて単結晶の育成を行なう昇
華再結晶法（改良レーリー法）が一般的に知られてい
る。As a method for growing this kind of single crystal SiC,
Conventionally, a seed crystal is fixedly arranged on the low-temperature side in a graphite crucible, SiC powder as a raw material is inserted and arranged on the high-temperature side, and the graphite crucible is heated to a high temperature of 2100 to 2400 ° C. in an inert atmosphere, A sublimation recrystallization method (improved Rayleigh method) in which the SiC powder is sublimated and recrystallized on the surface of a seed crystal on a low temperature side to grow a single crystal is generally known.
【０００４】しかし、上記の昇華再結晶法により製造さ
れた単結晶ＳｉＣには多種の欠陥が存在し、性能的にも
品質的にも安定した単結晶が得られないという問題があ
る。その理由は次のとおりである。すなわち、昇華の
際、ＳｉＣ粉末はいったんＳｉ，ＳｉＣ2 ，Ｓｉ2 Ｃに
分解されて気化し、さらに坩堝の構成元素である黒鉛の
一部も昇華するために、温度変化によって種結晶の表面
に到達するガスの種類が異なり、これらの分圧を化学量
論的に正確に制御することは技術的に非常に困難であ
り、そのために不純物が混入しやすく、その混入した不
純物や熱に起因する歪みの影響で結晶欠陥やマイクロパ
イプ欠陥等を発生しやすい。また、昇華再結晶法では成
長条件の変化に伴い結晶の多形転移を生じやすいという
欠点もある。However, the single crystal SiC produced by the above-described sublimation recrystallization method has various kinds of defects, and there is a problem that a single crystal having stable performance and quality cannot be obtained. The reason is as follows. That is, at the time of sublimation, the SiC powder is once decomposed into Si, SiC 2 , and Si 2 C and vaporized, and a part of graphite, which is a constituent element of the crucible, is also sublimated. The types of gases that reach the target are different, and it is technically very difficult to precisely control these partial pressures stoichiometrically. Therefore, impurities are liable to be mixed, which is caused by the mixed impurities and heat. Crystal defects, micropipe defects, and the like are likely to occur due to the influence of distortion. In addition, the sublimation recrystallization method has a disadvantage that polymorph transition of a crystal is likely to occur with a change in growth conditions.
【０００５】このような昇華再結晶法による単結晶Ｓｉ
Ｃの育成方法のもつ問題を解消するものとして、Ｓｉ液
相エピタキシャルによる単結晶ＳｉＣ育成方法（以下、
ＬＰＥ法という）が提案されている。このＬＰＥ法は、
Ｃを含む坩堝内に収容されたシリコン（Ｓｉ）融液中に
坩堝の構成元素であるＣとの反応により生成したＳｉＣ
を溶解させ、ホルダで支持したＳｉＣ単結晶基板をＳｉ
融液の低温域に浸漬させることにより、該ＳｉＣ単結晶
基板の表面上にＳｉＣ単結晶を成長させる方法である。[0005] Single crystal Si obtained by such a sublimation recrystallization method
As a solution to the problem of the C growing method, a single crystal SiC growing method by Si liquid phase epitaxy (hereinafter, referred to as “SiC growing method”) will be described.
LPE method) has been proposed. This LPE method
SiC generated by a reaction with C, a constituent element of the crucible, in a silicon (Si) melt contained in a crucible containing C
Is dissolved, and the SiC single crystal substrate supported by the holder is
This is a method of growing a SiC single crystal on the surface of the SiC single crystal substrate by immersing it in a low temperature region of the melt.
【０００６】[0006]
【発明が解決しようとする課題】上記したＬＰＥ法によ
り製造された単結晶ＳｉＣは、昇華再結晶法でみられる
ようなマイクロパイプ欠陥や結晶欠陥などが少なく、か
つ、多形転移の発生もなく、昇華再結晶法で製造される
単結晶ＳｉＣに比べて品質的に優れている反面、育成速
度が１０μ／ｈｒ．と遅くて単結晶ＳｉＣの生産性が低
く、生産コストが非常に高価なものになる。その上、バ
ルク状の単結晶ＳｉＣを得ようとして長時間に亘る単結
晶成長を行なうと、坩堝の低温部や、Ｓｉ融液の低温域
に浸漬されたＳｉＣ単結晶基板を支持するためのホルダ
に多くの多結晶が成長し、この多結晶の成長によって単
結晶の成長が妨げられるために、バルク状の単結晶が得
られない。したがって、このＬＰＥ法はＳｉＣ単結晶基
板上に極く薄い単結晶ＳｉＣを形成する液相エピタキシ
ャル成長に適用できるに過ぎず、バルク状単結晶ＳｉＣ
の育成には適用できない。The single-crystal SiC produced by the above-mentioned LPE method has few micropipe defects and crystal defects as observed in the sublimation recrystallization method, and has no polymorphic transition. Although it is superior in quality to single crystal SiC manufactured by the sublimation recrystallization method, the growth rate is 10 μ / hr. Therefore, the productivity of single crystal SiC is low, and the production cost becomes very expensive. In addition, when single crystal growth is performed for a long time in order to obtain bulk single crystal SiC, a holder for supporting a low temperature part of a crucible or a SiC single crystal substrate immersed in a low temperature region of a Si melt. Many polycrystals grow, and the growth of the polycrystals hinders the growth of single crystals, so that bulk single crystals cannot be obtained. Therefore, this LPE method can be applied only to liquid phase epitaxial growth for forming an extremely thin single crystal SiC on a SiC single crystal substrate, and can be applied to a bulk single crystal SiC.
It cannot be applied to the training of children.
【０００７】また、ＬＰＥ法ではＳｉＣの成長温度がＳ
ｉの融点よりも３００℃程度高温であるために、Ｓｉの
気化によりＳｉ融液中のＳｉＣ濃度が上がって過飽和に
なりやすく、その結果、Ｓｉ塊が育成されるＳｉＣ単結
晶間に封じ込まれて多結晶化しやすいという問題があ
り、これらのことが既述のようにＳｉやＧａＡｓなどの
既存の半導体材料に比べて多くの優れた特徴を有しなが
らも、その実用化を阻止する要因になっている。In the LPE method, the growth temperature of SiC is S
Since the temperature is higher than the melting point of i by about 300 ° C., the SiC concentration in the Si melt increases due to the vaporization of Si, which tends to cause supersaturation. As a result, the Si mass is trapped between the grown SiC single crystals. As described above, these have many excellent characteristics as compared with existing semiconductor materials such as Si and GaAs, but they are factors that hinder their practical use. Has become.
【０００８】本発明は上記実情に鑑みてなされたもの
で、マイクロパイプ欠陥や結晶欠陥等の発生が少ないと
ともに、Ｓｉ塊の封じ込みによる多結晶化もなく、非常
に高品質高性能で、かつ、バルク状の単結晶ＳｉＣを効
率よく育成することができ、半導体材料としての実用化
を促進できる単結晶ＳｉＣの液相育成方法を提供するこ
とを目的としている。[0008] The present invention has been made in view of the above-described circumstances, has a low occurrence of micropipe defects and crystal defects, has no polycrystallization due to the sealing of Si lumps, has very high quality and high performance. It is another object of the present invention to provide a liquid crystal growth method of single crystal SiC that can efficiently grow bulk single crystal SiC and can promote practical use as a semiconductor material.
【０００９】[0009]
【課題を解決するための手段】上記目的を達成するため
に、本発明に係る単結晶ＳｉＣの液相育成方法は、少な
くともＣ原子を含む坩堝内の底部に種結晶となるＳｉＣ
単結晶基板を配置し、このＳｉＣ単結晶基板の上面を覆
うように坩堝内にＳｉＯ2 粉末を充填するとともに、さ
らにその上部にＳｉＯ2 粉末とＳｉＣ粉末の混合粉末を
充填した状態で、底部側が低温となるように上下の温度
差を保ちながら不活性雰囲気中で加熱して両粉末を溶解
させ、その融液中に上記ＳｉＣ単結晶基板を所定時間に
亘り浸漬保持させることにより、ＳｉＣ単結晶基板の表
面に単結晶を育成させることを特徴とするものである。In order to achieve the above object, a method for growing a single crystal SiC in a liquid phase according to the present invention comprises a method of forming a seed crystal at least at a bottom portion in a crucible containing C atoms.
A single crystal substrate is arranged, and the crucible is filled with SiO 2 powder so as to cover the upper surface of the SiC single crystal substrate, and a mixed powder of SiO 2 powder and SiC powder is further filled on the upper portion thereof. By heating in an inert atmosphere while maintaining the upper and lower temperature differences so that the temperature becomes low, the two powders are dissolved, and the above-mentioned SiC single crystal substrate is immersed and held in the melt for a predetermined time to obtain a SiC single crystal. The method is characterized in that a single crystal is grown on the surface of the substrate.
【００１０】上記のような本発明によれば、加熱に伴い
下層のＳｉＯ2 粉末が酸化珪素（ＳｉＯ）とＯ2 に分解
されるとともに、その上層の混合粉末がＳｉ原子，Ｃ原
子，ＳｉＯおよびＯ2 にそれぞれ分解され、かつ、Ｓｉ
が溶融されてＳｉ融液が形成される。このとき、ＳｉＯ
2 粉末単独からなる下層とＳｉＣを含む混合粉末からな
る上層とでは、ＳｉＯ2 とＳｉＣとの熱伝導率の差によ
り下層側の方が上層よりも低温になり、このような温度
勾配の形成に伴うＳｉ融液の拡散、対流によってＣ原子
がＳｉ融液中の低温域に輸送される。一方、坩堝内の底
部に配置されたＳｉＣ単結晶基板は融液中の低温域に浸
漬保持されているために、その表面の運動エネルギーは
比較的小さい状態に保たれており、輸送されてきたＳｉ
原子とＣ原子は運動エネルギーの小さいＳｉＣ単結晶基
板の表面上で速やかに反応し、該表面にＳｉＣエピタキ
シャル層が成長されることになる。According to the present invention as described above, the lower layer of SiO 2 powder is decomposed into silicon oxide (SiO) and O 2 by heating, and the upper layer of the mixed powder is formed of Si atoms, C atoms, SiO and Decomposed into O2 and Si
Is melted to form a Si melt. At this time, SiO
2 In the lower layer composed of the powder alone and the upper layer composed of the mixed powder containing SiC, the lower layer has a lower temperature than the upper layer due to the difference in thermal conductivity between SiO 2 and SiC. C atoms are transported to a low temperature region in the Si melt by the accompanying diffusion and convection of the Si melt. On the other hand, since the SiC single crystal substrate disposed at the bottom in the crucible is immersed and held in a low temperature region in the melt, the kinetic energy of its surface is kept relatively small and has been transported. Si
The atoms and C atoms react quickly on the surface of the SiC single crystal substrate having a small kinetic energy, and a SiC epitaxial layer is grown on the surface.
【００１１】また、上記のようなＳｉＣエピタキシャル
成長時において、高温域の融液により加熱された坩堝か
らもＣが分解されてＳｉ融液中に溶け込み、上層の混合
粉末から分解されたＣ原子と相俟ってＳｉ融液中のＣ原
子が過剰になり、その結果、ＳｉＣ濃度が過飽和になっ
て、Ｓｉ塊が育成され、これがＳｉＣ単結晶間に封じ込
まれて多結晶化しやすくなる。Further, during the SiC epitaxial growth as described above, C is also decomposed from the crucible heated by the melt in the high-temperature region and melts into the Si melt, and the C atoms and the C atoms decomposed from the mixed powder in the upper layer are decomposed. In addition, the amount of C atoms in the Si melt becomes excessive, and as a result, the SiC concentration becomes supersaturated, and a Si lump grows, which is sealed between the SiC single crystals and easily crystallized.
【００１２】ところが、その過剰Ｃ原子を含むＳｉ融液
が上記の温度勾配に伴う拡散、対流によって低温域に輸
送される際、下層のＳｉＯ2 粉末から分解されたＳｉＯ
によりＣ原子がふるい（フィルター）にかけられること
になり、過剰なＣ原子と分解したＯ2 との反応によりＣ
ＯあるいはＣＯ2 にガス化されて融液の上方（系外）へ
排出されるとともに、適正量のＣ原子が低温域に輸送さ
れてＳｉＣ単結晶基板の表面に供給される。したがっ
て、Ｃ原子の過剰に伴うＳｉＣ濃度の過飽和に起因して
Ｓｉ塊が育成され、それがＳｉＣ単結晶間に封じ込まれ
ることによる多結晶化を生じることもなく、液相エピタ
キシャル成長であることによるマイクロパイプ欠陥など
の発生防止と相俟って、高品質高性能で、かつ、バルク
状の単結晶ＳｉＣを育成させることが可能である。However, when the Si melt containing excess C atoms is transported to a low-temperature region by diffusion and convection due to the above-mentioned temperature gradient, the SiO 2 powder decomposed from the lower SiO 2 powder is removed.
Causes C atoms to be sieved (filtered), and the reaction of excess C atoms with decomposed O2 causes C
It is gasified to O or CO 2 and discharged above the melt (outside the system), and an appropriate amount of C atoms is transported to a low temperature region and supplied to the surface of the SiC single crystal substrate. Therefore, the Si mass is grown due to the supersaturation of the SiC concentration due to the excess of C atoms, and polycrystalline crystallization is not caused by the inclusion of the Si mass between the SiC single crystals. It is possible to grow high-quality, high-performance and bulk single-crystal SiC in combination with prevention of generation of micropipe defects and the like.
【００１３】本発明に係る単結晶ＳｉＣの液相育成方法
において、上層の混合粉末におけるＳｉＯ2 粉末とＳｉ
Ｃ粉末の混合割合としては、１：１０〜１０：１の範囲
であればよいが、最も好ましい混合割合は、後述の実施
例でも説明するように４：１である。In the method for growing a single crystal SiC in a liquid phase according to the present invention, the SiO 2 powder and the Si
The mixing ratio of the C powder may be in the range of 1:10 to 10: 1, but the most preferable mixing ratio is 4: 1 as described in Examples below.
【００１４】また、本発明に係る単結晶ＳｉＣの液相育
成方法における加熱温度としては、上下両粉末層の温度
差を１０〜１００℃の範囲に保ちながら、坩堝内の上部
温度が２０００〜２２００℃まで昇温される程度が好ま
しい。The heating temperature in the method for growing a single crystal SiC in the liquid phase according to the present invention is such that the temperature difference between the upper and lower powder layers is kept in the range of 10 to 100 ° C. It is preferable that the temperature be raised to ° C.
【００１５】また、本発明に係る単結晶ＳｉＣの液相育
成方法に使用する坩堝としては、構成元素としてＣ原子
を含むものであればよい。具体的には、黒鉛製の坩堝や
Ｃ，ＳｉＣまたはＳｉＣと窒化アルミニウムとの混合物
の焼結体などからなる坩堝を用いればよい。また、坩堝
の内面にＳｉＣもしくは焼結ＳｉＣのコーティングを施
したものを使用してもよい。The crucible used in the single crystal SiC liquid phase growing method according to the present invention may be any crucible that contains C atoms as constituent elements. Specifically, a crucible made of graphite or a crucible made of a sintered body of C, SiC or a mixture of SiC and aluminum nitride may be used. Alternatively, a crucible whose inner surface is coated with SiC or sintered SiC may be used.
【００１６】[0016]
【発明の実施の形態】以下、本発明の実施の形態を図面
にもとづいて説明する。図１は本発明に係る単結晶Ｓｉ
Ｃの液相育成方法の実施に際し使用される育成装置の概
略断面図である。この育成装置は、底内径４０ｍｍ、上
部口径６０ｍｍ、深さ６０ｍｍのカーボン製坩堝１の内
面に熱化学的蒸着法（熱ＣＶＤ法）によって約１００μ
ｍ厚さのＳｉＣコーティング層２を施している。この坩
堝１の底部外周および上部外周にはそれぞれ高周波誘導
コイルからなる加熱ヒーター３および４が配設されてい
る。Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a single crystal Si according to the present invention.
It is a schematic sectional drawing of the growing apparatus used when implementing the liquid phase growing method of C. This growing apparatus has a bottom inner diameter of 40 mm, an upper diameter of 60 mm, and a depth of 60 mm.
An m-thick SiC coating layer 2 is applied. Heaters 3 and 4 each composed of a high-frequency induction coil are disposed on the outer periphery at the bottom and the outer periphery at the upper portion of the crucible 1, respectively.
【００１７】そして、上記坩堝１内の底部に、昇華法に
より直径２０ｍｍ、厚さ０．４ｍｍの大きさに作製され
た種結晶、例えば６Ｈ型のα−ＳｉＣ単結晶基板５をそ
のＣ軸方向の（０００１）面が上面となるように配置
し、このα−ＳｉＣ単結晶基板５の上面を覆うように粒
径が１μｍ以下のＳｉＯ2 粉末６を約１ｍｍ厚さで坩堝
１内に充填するとともに、さらにその上部に、ＳｉＯ2
粉末とＳｉＣ粉末とが１：４の割合に混合された混合粉
末７を約４０ｍｍの厚さで坩堝１内に充填した上、坩堝
１の上部開口をカーボン製の蓋８で閉鎖する。Then, a seed crystal, for example, a 6H-type α-SiC single crystal substrate 5 made to a size of 20 mm in diameter and 0.4 mm in thickness by sublimation is placed on the bottom of the crucible 1 in the C-axis direction. Is placed so that the (0001) plane is the upper surface, and the crucible 1 is filled with SiO 2 powder 6 having a particle size of 1 μm or less to a thickness of about 1 mm so as to cover the upper surface of the α-SiC single crystal substrate 5. With SiO 2
A mixed powder 7 in which the powder and the SiC powder are mixed at a ratio of 1: 4 is filled into the crucible 1 with a thickness of about 40 mm, and the upper opening of the crucible 1 is closed with a lid 8 made of carbon.
【００１８】この状態で、加熱ヒーター３および４に高
周波電流を通して坩堝１をそれの上下で２０〜５０℃の
温度差が保たれ、かつ、不活性ガス雰囲気中で坩堝１の
上部が２２００℃に昇温されるように誘導加熱すること
によって、図２のモデル図に示すたように、坩堝１内部
の上層に充填された混合粉末７のＳｉＯ2 がＳｉＯとＯ
2 に、かつ、ＳｉＣがＳｉ原子とＣ原子にそれぞれ分解
され、その分解されたＳｉが溶融されてＳｉ融液が形成
されるとともに、坩堝１内部の下層に充填されたＳｉＯ
2 粉末６がＳｉＯとＯ2 に分解される。In this state, a high-frequency current is passed through the heaters 3 and 4 to keep the crucible 1 at a temperature difference of 20 to 50 ° C. above and below the crucible 1 and to raise the temperature of the crucible 1 to 2200 ° C. in an inert gas atmosphere. By induction heating so as to raise the temperature, as shown in the model diagram of FIG. 2, SiO 2 of the mixed powder 7 filled in the upper layer inside the crucible 1 becomes SiO 2 and O 2.
The SiC is decomposed into Si atoms and C atoms, and the decomposed Si is melted to form a Si melt, and the SiO filled in the lower layer inside the crucible 1 is formed.
2 The powder 6 is decomposed into SiO and O 2 .
【００１９】上記の加熱時において、ＳｉＯ2 粉末６単
独からなる下層とＳｉＣを含む混合粉末７からなる上層
とでは、ＳｉＯ2 とＳｉＣとの熱伝導率の差により下層
側の方が上層よりも低温となるような温度勾配が形成さ
れることになり、このような温度勾配の形成に伴うＳｉ
融液の拡散、対流によってＣ原子がＳｉ融液中の低温域
に輸送される。一方、α−ＳｉＣ単結晶基板５はＳｉ融
液中の低温域に浸漬保持されていることから、その表面
の運動エネルギーは比較的小さい状態に保たれており、
低温域に輸送されてきたＣ原子は運動エネルギーの小さ
いα−ＳｉＣ単結晶基板５の表面上で速やかにＳｉと反
応し、該表面にＳｉＣエピタキシャル層が成長されるこ
とになる。At the time of the above-mentioned heating, the lower layer of the lower layer is more than the upper layer of the lower layer composed of the SiO 2 powder 6 alone and the upper layer composed of the mixed powder 7 containing SiC due to the difference in thermal conductivity between SiO 2 and SiC. A temperature gradient is formed such that the temperature becomes low.
C atoms are transported to a low temperature region in the Si melt by diffusion and convection of the melt. On the other hand, since the α-SiC single crystal substrate 5 is immersed and held in the low temperature region in the Si melt, the kinetic energy of its surface is kept relatively small,
The C atoms transported to the low-temperature region quickly react with Si on the surface of the α-SiC single crystal substrate 5 having a small kinetic energy, and a SiC epitaxial layer is grown on the surface.
【００２０】上記のごときＳｉＣエピタキシャル成長時
において、加熱ヒーター３および４ならびに高温域のＳ
ｉ融液により加熱された坩堝１内面のＳｉＣコーティン
グ層２からもＣが分解されてＳｉ融液中に溶け込むため
に、混合粉末７から分解されたＣ原子と相俟ってＳｉ融
液中のＣ原子は過剰になる。During the SiC epitaxial growth as described above, the heaters 3 and 4 and the S
C is also decomposed from the SiC coating layer 2 on the inner surface of the crucible 1 heated by the i melt and melts into the Si melt, so that the C atoms decomposed from the mixed powder 7 are combined with C atoms in the Si melt. C atoms become excessive.
【００２１】ところで、その過剰Ｃ原子を含むＳｉ融液
が上記の温度勾配に伴う拡散、対流によって低温域に輸
送される際、下層のＳｉＯ2 粉末６から分解されたＳｉ
ＯによりＣ原子がフィルターにかけられることになり、
過剰なＣ原子と分解したＯ2との反応によりＣＯあるい
はＣＯ2 にガス化されてＳｉ融液の上方の空間に至り、
かつ、カーボン製蓋８に形成されているガス抜き孔（図
示省略する）から坩堝１外へ排出され、適正量のＣ原子
が低温域に輸送されてα−ＳｉＣ単結晶基板５の表面に
供給されることになって、Ｃ原子の過剰に伴うＳｉＣ濃
度の過飽和に起因してＳｉ塊が育成され、それがＳｉＣ
単結晶間に封じ込まれることによる多結晶化の発生が起
こらない。By the way, when the Si melt containing excess C atoms is transported to a low temperature region by diffusion and convection due to the above-mentioned temperature gradient, the Si melt decomposed from the lower SiO 2 powder 6
O will filter the C atoms,
The reaction between the excess C atoms and the decomposed O 2 gasifies into CO or CO 2 and reaches the space above the Si melt,
In addition, the gas is discharged out of the crucible 1 through a gas vent hole (not shown) formed in the carbon lid 8, and an appropriate amount of C atoms is transported to a low temperature region and supplied to the surface of the α-SiC single crystal substrate 5. As a result, Si lump grows due to supersaturation of SiC concentration due to excess of C atoms,
Polycrystallization does not occur due to sealing between single crystals.
【００２２】このように多結晶化の発生がないことと、
液相エピタキシャル成長であることによるマイクロパイ
プ欠陥などの発生がないことが相俟って、α−ＳｉＣ単
結晶基板５の表面に高品質高性能で、かつ、厚みの大き
い単結晶ＳｉＣを育成させることが可能である。As described above, there is no occurrence of polycrystallization,
In combination with the fact that there is no generation of micropipe defects due to liquid phase epitaxial growth, single crystal SiC of high quality and high performance and having a large thickness is grown on the surface of α-SiC single crystal substrate 5. Is possible.
【００２３】因みに、上述のように、坩堝１の上部を誘
導加熱によって２２００℃に昇温させた状態を４時間保
持した後に冷却して坩堝１からα−ＳｉＣ単結晶基板５
を取り出し、その表面のガラス層をダイヤモンド製のワ
イヤーカッターにより切除した後、弗酸でＳｉＯ2 層を
除去してみたところ、α−ＳｉＣ単結晶基板５の表面に
約５０μｍの単結晶ＳｉＣが育成されていることが確認
された。Incidentally, as described above, the state in which the upper portion of the crucible 1 was heated to 2200 ° C. by induction heating was maintained for 4 hours, then cooled, and the α-SiC single crystal substrate 5 was removed from the crucible 1.
After removing the glass layer on the surface with a diamond wire cutter and removing the SiO 2 layer with hydrofluoric acid, single-crystal SiC of about 50 μm was grown on the surface of the α-SiC single-crystal substrate 5. It was confirmed that it was.
【００２４】なお、上記実施の形態では、上記α−Ｓｉ
Ｃ単結晶基板５として６Ｈ型のものを用いたが、４Ｈ型
のものを使用してもよい。In the above embodiment, the α-Si
Although a 6H type substrate is used as the C single crystal substrate 5, a 4H type substrate may be used.
【００２５】[0025]
【発明の効果】以上のように、請求項１及び請求項４に
記載の発明によれば、坩堝内の上下にＳｉＯ2 粉末及び
ＳｉＣ粉末の混合粉末とＳｉＯ2 粉末単独とを層状に充
填した状態での加熱処理を採用することにより、種結晶
となるＳｉＣ単結晶基板の表面の運動エネルギーが小さ
い状態となるような温度勾配を形成することができると
ともに、液相成長では避けられない過剰なＣ原子の一部
をガス化（ＣＯあるいはＣＯ2 ）し系外へ排出させつ
つ、常に適正量のＣ原子をＳｉ融液の低温域に配置され
たＳｉＣ単結晶基板の表面に供給させるようなフィルタ
ー作用を生起してＣ原子の過剰に伴うＳｉＣ濃度の過飽
和に起因してＳｉ塊が育成され、これがＳｉＣ単結晶間
に封じ込まれることを防止することができる。したがっ
て、Ｓｉ融液による液相エピタキシャル成長であること
によるマイクロパイプ欠陥や結晶欠陥等の発生が少ない
ことと、Ｓｉ塊の封じ込みによる多結晶化がないことと
の相乗によって、非常に高品質高性能で、かつ、厚みの
あるバルク状の単結晶ＳｉＣを効率よく育成することが
でき、これによって、Ｓｉ（シリコン）やＧａＡｓ（ガ
リウムヒ素）などの既存の半導体材料に比べて高温、高
周波、耐電圧、耐環境性に優れパワーデバイス用半導体
材料として期待されている単結晶ＳｉＣの実用化を促進
することができるという効果を奏する。As described above, according to the first and fourth aspects of the present invention, a mixed powder of SiO 2 powder and SiC powder and a single powder of SiO 2 are filled up and down in a crucible. By adopting the heat treatment in the state, it is possible to form a temperature gradient such that the kinetic energy of the surface of the SiC single crystal substrate serving as a seed crystal is small, and to use an excessively unavoidable liquid phase growth. While a part of C atoms is gasified (CO or CO 2 ) and discharged out of the system, an appropriate amount of C atoms is always supplied to the surface of the SiC single crystal substrate arranged in the low temperature region of the Si melt. It is possible to prevent a Si lump from growing due to supersaturation of the SiC concentration caused by an excess of C atoms due to a filter effect, and to be trapped between SiC single crystals. Therefore, extremely high quality and high performance are obtained by synergistically that the occurrence of micropipe defects and crystal defects due to the liquid phase epitaxial growth by the Si melt is small and that there is no polycrystallization due to the sealing of the Si mass. In addition, it is possible to efficiently grow a bulk single crystal SiC having a high thickness, thereby achieving a higher temperature, a higher frequency, and a higher withstand voltage than existing semiconductor materials such as Si (silicon) and GaAs (gallium arsenide). This has the effect of promoting the practical use of single crystal SiC, which has excellent environmental resistance and is expected as a semiconductor material for power devices.
【図１】本発明に係る単結晶ＳｉＣの液相育成方法の実
施に際し使用される育成装置の概略断面図である。FIG. 1 is a schematic cross-sectional view of a growth apparatus used for carrying out a liquid crystal growth method for single crystal SiC according to the present invention.
【図２】同上育成装置による単結晶ＳｉＣの育成モデル
図である。FIG. 2 is a model diagram of growing single-crystal SiC by the same growing apparatus.
１ 坩堝 ２ コーティング層 ５ α−ＳｉＣ単結晶基板（種結晶） ６ ＳｉＯ2 粉末 ７ 混合粉末（ＳｉＯ2 粉末＋ＳｉＣ粉末）Reference Signs List 1 crucible 2 coating layer 5 α-SiC single crystal substrate (seed crystal) 6 SiO 2 powder 7 mixed powder (SiO 2 powder + SiC powder)
───────────────────────────────────────────────────── フロントページの続き (56)参考文献 特開 昭63−156095（ＪＰ，Ａ) (58)調査した分野(Int.Cl.7，ＤＢ名) C30B 1/00 - 35/00 ＣＡ（ＳＴＮ) 特許ファイル（ＰＡＴＯＬＩＳ)────────────────────────────────────────────────── (5) References JP-A-63-156095 (JP, A) (58) Fields investigated (Int. Cl. 7 , DB name) C30B 1/00-35/00 CA (STN ) Patent file (PATOLIS)
Claims (4)
の底部に種結晶となる炭化珪素（ＳｉＣ）単結晶基板を
配置し、このＳｉＣ単結晶基板の上面を覆うように坩堝
内に二酸化珪素（ＳｉＯ2 ）粉末を充填するとともに、
さらにその上部にＳｉＯ2 粉末とＳｉＣ粉末の混合粉末
を充填した状態で、底部側が低温となるように上下の温
度差を保ちながら不活性雰囲気中で加熱して両粉末を溶
解させ、その融液中に上記ＳｉＣ単結晶基板を所定時間
に亘り浸漬保持させることにより、ＳｉＣ単結晶基板の
表面に単結晶を育成させることを特徴とする単結晶Ｓｉ
Ｃの液相育成方法。1. A silicon carbide (SiC) single crystal substrate serving as a seed crystal is arranged at the bottom of a crucible containing at least carbon (C) atoms, and silicon dioxide is placed in the crucible so as to cover an upper surface of the SiC single crystal substrate. (SiO 2 ) powder and
Further, in a state where the mixed powder of the SiO 2 powder and the SiC powder is filled in the upper part, the two powders are dissolved by heating in an inert atmosphere while maintaining the upper and lower temperature differences so that the bottom side is at a low temperature. A step of dipping and holding the SiC single crystal substrate therein for a predetermined time to grow a single crystal on the surface of the SiC single crystal substrate.
C liquid phase growing method.
ｉＣ粉末の混合割合は、１：１０〜１０：１の範囲であ
る請求項１に記載の単結晶ＳｉＣの液相育成方法。2. The mixed powder of SiO 2 powder and S
The method of growing a single crystal SiC according to claim 1, wherein the mixing ratio of the iC powder is in the range of 1:10 to 10: 1.
０〜１００℃の範囲に保ちながら坩堝内の上部を２００
０〜２２００℃まで加熱昇温させる請求項１または２に
記載の単結晶ＳｉＣの液相育成方法。3. The temperature difference between the two powders during the heating is 1
Keep the upper part of the crucible in 200
The method for growing a single-crystal SiC liquid phase according to claim 1, wherein the temperature is increased to 0 to 2200 ° C. 4.
の内面にＳｉＣもしくは焼結ＳｉＣのコーティング層を
施した坩堝を使用する請求項１ないし３のいずれかに記
載の単結晶ＳｉＣの液相育成方法。4. The method for growing a single crystal SiC liquid phase according to claim 1, wherein a graphite crucible or a crucible having an inner surface coated with SiC or sintered SiC is used as said crucible. .
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| JP11058254A JP3087065B1 (en) | 1999-03-05 | 1999-03-05 | Method for growing liquid phase of single crystal SiC |
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| JP2000256091A JP2000256091A (en) | 2000-09-19 |
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| KR101567524B1 (en) | 2013-12-16 | 2015-11-10 | 서동철 | Gear Module Plaything Set |
| CN115627522A (en) * | 2022-12-12 | 2023-01-20 | 北京青禾晶元半导体科技有限责任公司 | Method for improving crystal growth quality |
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| JP5049590B2 (en) | 2004-12-28 | 2012-10-17 | パナソニック株式会社 | Method for producing silicon carbide (SiC) single crystal |
| JP2007126335A (en) * | 2005-11-04 | 2007-05-24 | Toyota Motor Corp | Manufacturing facility for manufacturing silicon carbide single crystal by means of solution method |
| KR101003075B1 (en) | 2008-04-15 | 2010-12-21 | 네오세미테크 주식회사 | Method and Apparatus for growth of silicon carbide single crystal |
| JP5218348B2 (en) * | 2009-09-03 | 2013-06-26 | 新日鐵住金株式会社 | Method for producing silicon carbide single crystal |
| KR101316689B1 (en) * | 2011-06-10 | 2013-10-10 | 한국에너지기술연구원 | Silicon melting reactor with excellent prevention effect of impurities inflow and manufacturing apparatus of silicon substrate including the same |
| KR101549597B1 (en) | 2013-10-30 | 2015-09-03 | 한국세라믹기술원 | The Manufacturing Method of SiC Single Crystal Using the Crucible coated with SiC |
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Cited By (2)
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|---|---|---|---|---|
| KR101567524B1 (en) | 2013-12-16 | 2015-11-10 | 서동철 | Gear Module Plaything Set |
| CN115627522A (en) * | 2022-12-12 | 2023-01-20 | 北京青禾晶元半导体科技有限责任公司 | Method for improving crystal growth quality |
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