WO2020121526A1 - SEMI-INSULATING GaAs SUBSTRATE AND METHOD FOR PRODUCING GaAs SUBSTRATE - Google Patents

SEMI-INSULATING GaAs SUBSTRATE AND METHOD FOR PRODUCING GaAs SUBSTRATE Download PDF

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WO2020121526A1
WO2020121526A1 PCT/JP2018/046154 JP2018046154W WO2020121526A1 WO 2020121526 A1 WO2020121526 A1 WO 2020121526A1 JP 2018046154 W JP2018046154 W JP 2018046154W WO 2020121526 A1 WO2020121526 A1 WO 2020121526A1
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control member
gaas substrate
heat control
gaas
semi
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石川　幸雄
良明 羽木
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住友電気工業株式会社
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Priority to TW108128710A priority patent/TW202022177A/en
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    • C—CHEMISTRY; METALLURGY
    • C30—CRYSTAL GROWTH
    • C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
    • C30B11/00—Single-crystal growth by normal freezing or freezing under temperature gradient, e.g. Bridgman-Stockbarger method
    • C—CHEMISTRY; METALLURGY
    • C30—CRYSTAL GROWTH
    • C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
    • C30B29/00—Single crystals or homogeneous polycrystalline material with defined structure characterised by the material or by their shape
    • C30B29/10—Inorganic compounds or compositions
    • C30B29/40—AIIIBV compounds wherein A is B, Al, Ga, In or Tl and B is N, P, As, Sb or Bi
    • C30B29/42—Gallium arsenide

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  • Materials Engineering (AREA)
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  • Inorganic Chemistry (AREA)
  • Crystals, And After-Treatments Of Crystals (AREA)

Abstract

A semi-insulating GaAs substrate exhibiting a principal surface orientation which is the (100) plane and having a disc shape which exhibits a diameter of at least 150mm, wherein the difference between measured values of dislocation density measured at a first measurement point, a second measurement point and a third measurement point is within 2,000cm-2, when the first measurement point is the center of the principal surface, the second measurement point is the center of a first line segment extending from the first measurement point in the [010] direction to the outer-circumference of the semi-insulating GaAs substrate, and the third measurement point is a point located 10mm to the inside from the outer-circumference along the first line segment.

Description

半絶縁性ＧａＡｓ基板およびＧａＡｓ基板の製造方法Semi-insulating GaAs substrate and method for manufacturing GaAs substrate
　本開示は、半絶縁性ＧａＡｓ基板およびＧａＡｓ基板の製造方法に関する。 The present disclosure relates to a semi-insulating GaAs substrate and a method for manufacturing a GaAs substrate.
　従来より無線通信、光通信などの技術分野において、送受信、信号処理などを担うデバイスの材料として半絶縁性ＧａＡｓ基板が汎用されている。たとえば、特開平０２－１０７５９８号公報（特許文献１）、特開平０２－１９２５００号公報（特許文献２）、非特許文献１、非特許文献２などにおいて、この種のデバイスの品質および歩留の向上を目的として、上記基板の面内における電気特性のバラツキを抑える技術が記載されている。 Conventionally, semi-insulating GaAs substrates have been widely used as materials for devices that perform transmission/reception, signal processing, etc. in technical fields such as wireless communication and optical communication. For example, in Japanese Unexamined Patent Publication No. 02-107598 (Patent Document 1), Japanese Unexamined Patent Publication No. 02-192500 (Patent Document 2), Non-Patent Document 1, Non-Patent Document 2, etc., the quality and yield of this type of device are shown. For the purpose of improvement, a technique for suppressing variations in the electrical characteristics within the surface of the substrate is described.
特開平０２－１０７５９８号公報JP-A-02-107598 特開平０２－１９２５００号公報JP-A-02-192500
　本開示に係る半絶縁性ＧａＡｓ基板は、主面の面方位が（１００）面である半絶縁性ＧａＡｓ基板であって、上記半絶縁性ＧａＡｓ基板は、直径が１５０ｍｍ以上である円盤状の形状を有し、上記半絶縁性ＧａＡｓ基板は、上記主面の中心を第１測定点とし、上記第１測定点から［０１０］方向に沿って上記半絶縁性ＧａＡｓ基板の外周に至る第１線分の中点を第２測定点とし、上記第１線分上の上記外周から１０ｍｍ内側となる点を第３測定点とし、上記第１測定点、上記第２測定点および上記第３測定点で転位密度を測定した場合、これらの測定値の差が２０００ｃｍ-2以内である。 A semi-insulating GaAs substrate according to the present disclosure is a semi-insulating GaAs substrate whose main surface has a (100) plane orientation, and the semi-insulating GaAs substrate has a disk-like shape with a diameter of 150 mm or more. The semi-insulating GaAs substrate has a first measurement point at the center of the main surface, and a first line extending from the first measurement point along the [010] direction to the outer periphery of the semi-insulating GaAs substrate. The midpoint of the minute is the second measurement point, and the point on the first line segment that is 10 mm inside from the outer circumference is the third measurement point, and the first measurement point, the second measurement point, and the third measurement point. When the dislocation density is measured by, the difference between these measured values is within 2000 cm -2 .
　本開示に係るＧａＡｓ基板の製造方法は、主面の面方位が（１００）面であるＧａＡｓ基板の製造方法であって、ＧａＡｓ種結晶が底部に収容され、上記ＧａＡｓ種結晶上にＧａＡｓ融液が収容された坩堝と、上記坩堝の外周に沿って配設された発熱体と、上記坩堝および上記発熱体の間に配設された調熱部材とを備えた単結晶成長装置を準備する工程と、上記単結晶成長装置において、上記調熱部材を通過した上記発熱体からの熱で上記ＧａＡｓ種結晶および上記ＧａＡｓ融液を加熱することにより、上記ＧａＡｓ種結晶からＧａＡｓ単結晶を成長させる工程と、上記ＧａＡｓ単結晶を、その成長方向に対して垂直に切出すことにより、上記主面の面方位が（１００）面であるＧａＡｓ基板を得る工程とを含み、上記調熱部材は、上記成長方向に沿って第１調熱部材、第２調熱部材および第３調熱部材の順に分割され、上記第２調熱部材は、波長２μｍ以上３μｍ以下の範囲の光線透過率が、上記第１調熱部材の上記光線透過率および上記第３調熱部材の上記光線透過率に対し２倍以上５倍以下であり、成長中の上記ＧａＡｓ単結晶と上記ＧａＡｓ融液との界面は、上記第２調熱部材を通過した上記発熱体からの熱で加熱される。 A method of manufacturing a GaAs substrate according to the present disclosure is a method of manufacturing a GaAs substrate in which a main surface has a (100) plane orientation, in which a GaAs seed crystal is accommodated in a bottom portion, and a GaAs melt is formed on the GaAs seed crystal. A step of preparing a single crystal growth apparatus comprising a crucible containing the above, a heating element arranged along the outer periphery of the crucible, and a heat control member arranged between the crucible and the heating element. And a step of growing a GaAs single crystal from the GaAs seed crystal by heating the GaAs seed crystal and the GaAs melt with heat from the heating element that has passed through the heat control member in the single crystal growth apparatus. And a step of cutting the GaAs single crystal perpendicularly to the growth direction thereof to obtain a GaAs substrate having a main surface whose plane orientation is the (100) plane. The first heat control member, the second heat control member, and the third heat control member are divided in this order along the growth direction, and the second heat control member has a light transmittance in the range of wavelengths of 2 μm or more and 3 μm or less. The light transmittance of the first heat control member and the light transmittance of the third heat control member are 2 times or more and 5 times or less, and the interface between the growing GaAs single crystal and the GaAs melt is It is heated by the heat from the heating element that has passed through the second heat regulation member.
図１は、本開示に係る半絶縁性ＧａＡｓ基板について、面方位が（１００）面である主面の中心から［０１０］方向を含む等価な４方向、および主面の中心から［０１１］を含む等価な４方向を表した模式図である。FIG. 1 shows the equivalent four directions including the [010] direction from the center of the main surface whose plane orientation is the (100) plane and the [011] from the center of the main surface of the semi-insulating GaAs substrate according to the present disclosure. It is a schematic diagram showing equivalent four directions including. 図２は、図１の半絶縁性ＧａＡｓ基板を製造する製造方法に用いる単結晶成長装置の概略構成の一例を示す断面図である。FIG. 2 is a sectional view showing an example of a schematic configuration of a single crystal growth apparatus used in the manufacturing method for manufacturing the semi-insulating GaAs substrate of FIG. 図３は、図１の半絶縁性ＧａＡｓ基板を製造する製造方法に用いる単結晶成長装置の概略構成の他の一例を示す断面図である。FIG. 3 is a cross-sectional view showing another example of the schematic configuration of the single crystal growth apparatus used in the manufacturing method for manufacturing the semi-insulating GaAs substrate of FIG. 図４は、図１の半絶縁性ＧａＡｓ基板を製造する製造方法に用いる単結晶成長装置の概略構成のさらに他の一例を示す断面図である。FIG. 4 is a sectional view showing still another example of the schematic configuration of the single crystal growth apparatus used in the manufacturing method for manufacturing the semi-insulating GaAs substrate of FIG.
　［本開示が解決しようとする課題］
　半絶縁性ＧａＡｓ基板では、デバイスの性能向上に直結する構造の微細化および複雑化に資するため、基板表面（たとえば主面）上の結晶欠陥の一種である転位の密度（以下、「転位密度」とも記す）の分布を均一とすることが求められている。具体的には、たとえば上記基板を構成する単結晶のすべての結晶方位において転位密度にバラツキがなく、かつ同じ結晶方位上の複数箇所においても転位密度にバラツキがないことが求められている。しかしながら、上記特許文献１～２および上記非特許文献１～２では、特定の結晶方位の転位密度等について言及する限りであって、すべての結晶方位で転位密度の分布が均一となるか否かについては検討されていない。したがって、未だ基板表面のすべての結晶方位において転位密度が均一な半絶縁性ＧａＡｓ基板は実現されておらず、その開発が切望されている。 [Problems to be solved by the present disclosure]
The semi-insulating GaAs substrate contributes to the miniaturization and complexity of the structure directly connected to the improvement of the device performance. Therefore, the density of dislocations, which is a kind of crystal defects on the substrate surface (for example, the main surface) (hereinafter, “dislocation density”) (Also referred to as )) is required to be uniform. Specifically, for example, it is required that the dislocation density does not vary in all the crystal orientations of the single crystal that constitutes the substrate, and that the dislocation density does not vary in a plurality of locations on the same crystal orientation. However, the above-mentioned Patent Documents 1 and 2 and Non-Patent Documents 1 and 2 only mention dislocation density in a specific crystal orientation, and whether or not the distribution of dislocation density is uniform in all crystal orientations. Has not been considered. Therefore, a semi-insulating GaAs substrate having a uniform dislocation density in all crystal orientations on the substrate surface has not yet been realized, and its development is earnestly desired.
　以上の点に鑑み、本開示は、基板表面のすべての結晶方位において転位密度が均一な半絶縁性ＧａＡｓ基板およびＧａＡｓ基板の製造方法を提供することを目的とする。 In view of the above points, the present disclosure aims to provide a semi-insulating GaAs substrate having a uniform dislocation density in all crystal orientations of the substrate surface and a method for manufacturing the GaAs substrate.
　［本開示の効果］
　本開示によれば、基板表面のすべての結晶方位において転位密度が均一な半絶縁性ＧａＡｓ基板およびＧａＡｓ基板の製造方法を提供することができる。 [Effect of the present disclosure]
According to the present disclosure, it is possible to provide a semi-insulating GaAs substrate having a uniform dislocation density in all crystal orientations on the substrate surface and a method for manufacturing the GaAs substrate.
　［実施形態の概要］
　本発明者らは、上記課題を解決するために鋭意検討を重ね、本開示を完成させた。具体的には、垂直ブリッジマン法および垂直温度傾斜凝固法に共通する縦型円筒容器内結晶成長法、所謂垂直ボート法（以下、「ＶＢ法」とも記す）を用いてＧａＡｓ単結晶を成長させる場合において、ＧａＡｓ単結晶の成長方向に沿って所定の温度勾配を付した加熱操作（以下、「温度プロファイル」とも記す）で、結晶成長方向の温度制御だけでなく、ＧａＡｓ単結晶の円周方向の温度差も軽減することに着目した。上記温度プロファイルを採用することにより、ＶＢ法を用いてＧａＡｓ単結晶を歩留良く成長させることができる。 [Outline of Embodiment]
The present inventors have earnestly studied in order to solve the above problems and completed the present disclosure. Specifically, a GaAs single crystal is grown using a vertical cylindrical in-container crystal growth method common to the vertical Bridgman method and the vertical temperature gradient solidification method, a so-called vertical boat method (hereinafter, also referred to as “VB method”). In this case, not only the temperature control in the crystal growth direction but also the circumferential direction of the GaAs single crystal by the heating operation with a predetermined temperature gradient along the growth direction of the GaAs single crystal (hereinafter also referred to as “temperature profile”). We paid attention to reducing the temperature difference. By adopting the above temperature profile, a GaAs single crystal can be grown with a high yield by using the VB method.
　ＶＢ法では、従来より線状発熱体により所定の温度プロファイルを生成し、この温度プロファイルに基づいてＧａＡｓ単結晶およびＧａＡｓ融液を加熱している。しかしながら線状発熱体は、坩堝の周囲を単結晶の成長方向にらせん状に包囲しているため、本質的にＧａＡｓ単結晶の円周方向に温度差（以下、「円周方向温度差」とも記す）が発生しやすい。さらに線状発熱体の熱膨張によって発熱体自体の相対的な位置が変化することなどによって円周方向温度差がより大きくなる場合がある。円周方向温度差によって成長中のＧａＡｓ単結晶には熱応力が発生するため、円周方向温度差は、ＧａＡｓ単結晶の転位密度を増加させる一因となることが知られている。このため一般的な工業炉で線状発熱体を用いる場合、公知の方法としてアルミナ、ムライトなどの材料からなる汎用の炉芯管を用いることにより、被加熱物（たとえばＧａＡｓ単結晶）の円周方向温度差の軽減が図られている。 In the VB method, a linear heating element has conventionally generated a predetermined temperature profile, and the GaAs single crystal and the GaAs melt are heated based on this temperature profile. However, since the linear heating element spirally surrounds the circumference of the crucible in the growth direction of the single crystal, it essentially has a temperature difference in the circumferential direction of the GaAs single crystal (hereinafter, also referred to as "circumferential temperature difference"). Note) is likely to occur. Further, the thermal expansion of the linear heating element may change the relative position of the heating element itself, which may increase the circumferential temperature difference. Since thermal stress is generated in the growing GaAs single crystal due to the temperature difference in the circumferential direction, it is known that the temperature difference in the circumferential direction is one of the factors that increase the dislocation density of the GaAs single crystal. For this reason, when a linear heating element is used in a general industrial furnace, by using a general-purpose furnace core tube made of a material such as alumina or mullite as a known method, the circumference of the object to be heated (for example, GaAs single crystal) is The difference in directional temperature is reduced.
　しかしながら上記炉芯管は、赤外線に対して不透明である。上記炉芯管は、５ｍｍ程度の厚みを有し、かつ材料であるアルミナ、ムライトが多結晶体であるので結晶粒界そのもの、あるいは結晶粒界に存在するガラス相によって光散乱が生じるからである。これにより炉芯管自体の長手方向の伝熱伝導が発生し、長手方向の温度勾配が鈍化するため、望まれる温度プロファイルを生成することが難しくなる。そこで本発明者らは、炉芯管に代えて、部位によって赤外線の２～３μｍの波長に対する光線透過率が異なる調熱部材を準備し、それを単結晶の成長方向に沿って配置することにより、線状発熱体に起因した円周方向温度差の軽減を図りつつ、所望の温度プロファイルを生成することを想到した。 However, the furnace core tube is opaque to infrared rays. This is because the furnace core tube has a thickness of about 5 mm, and since the materials alumina and mullite are polycrystals, light scattering occurs due to the crystal grain boundaries themselves or the glass phase existing at the crystal grain boundaries. .. As a result, heat transfer is generated in the longitudinal direction of the furnace core tube itself, and the temperature gradient in the longitudinal direction becomes dull, making it difficult to generate the desired temperature profile. Therefore, the present inventors prepared a heat control member having a different light transmittance for infrared rays of 2 to 3 μm depending on the site, instead of the furnace core tube, and arranging it along the growth direction of the single crystal. , It has been conceived to generate a desired temperature profile while reducing the circumferential temperature difference caused by the linear heating element.
　これにより、円周方向温度差の軽減を図りつつ、所望の温度プロファイルによってＧａＡｓ単結晶を成長させることができ、もってＧａＡｓ単結晶の面内温度分布をより均一とすることに到達した。その結果、ＧａＡｓ単結晶から（１００）面を主面として切出したＧａＡｓ基板において、その主面のすべての結晶方位において転位密度が均一となることを知見した。 This has made it possible to grow a GaAs single crystal with a desired temperature profile while reducing the temperature difference in the circumferential direction, thus achieving a more uniform in-plane temperature distribution of the GaAs single crystal. As a result, it was found that, in a GaAs substrate cut out from a GaAs single crystal with the (100) plane as the main surface, the dislocation density is uniform in all crystal orientations of the main surface.
　最初に本開示の実施態様を列記して説明する。
　［１］本開示の一態様に係る半絶縁性ＧａＡｓ基板は、主面の面方位が（１００）面である半絶縁性ＧａＡｓ基板であって、上記半絶縁性ＧａＡｓ基板は、直径が１５０ｍｍ以上である円盤状の形状を有し、上記半絶縁性ＧａＡｓ基板は、上記主面の中心を第１測定点とし、上記第１測定点から［０１０］方向に沿って上記半絶縁性ＧａＡｓ基板の外周に至る第１線分の中点を第２測定点とし、上記第１線分上の上記外周から１０ｍｍ内側となる点を第３測定点とし、上記第１測定点、上記第２測定点および上記第３測定点で転位密度を測定した場合、これらの測定値の差が２０００ｃｍ-2以内である。このような特徴を備えた半絶縁性ＧａＡｓ基板は、主面のすべての結晶方位において転位密度を均一とすることができる。 First, embodiments of the present disclosure will be listed and described.
[1] A semi-insulating GaAs substrate according to an aspect of the present disclosure is a semi-insulating GaAs substrate having a main surface having a (100) plane orientation, and the semi-insulating GaAs substrate has a diameter of 150 mm or more. The semi-insulating GaAs substrate has a disk-like shape, and the center of the main surface is the first measurement point, and the semi-insulating GaAs substrate of the semi-insulation GaAs substrate is along the [010] direction from the first measurement point. The midpoint of the first line segment reaching the outer circumference is defined as the second measurement point, and the point on the first line segment that is 10 mm inside from the outer circumference is defined as the third measurement point, and the first measurement point and the second measurement point are defined. When the dislocation density is measured at the third measurement point, the difference between these measured values is within 2000 cm -2 . The semi-insulating GaAs substrate having such characteristics can have a uniform dislocation density in all crystal orientations of the main surface.
　［２］上記半絶縁性ＧａＡｓ基板は、上記第１測定点から［０１１］方向に沿って上記半絶縁性ＧａＡｓ基板の外周に至る第２線分の中点を第４測定点とし、上記第２測定点および上記第４測定点で転位密度を測定した場合、これらの測定値の差が１７００ｃｍ-2以内であることが好ましい。これにより、主面のすべての結晶方位における転位密度をより均一とすることができる。 [2] In the semi-insulating GaAs substrate, the midpoint of the second line segment from the first measuring point to the outer periphery of the semi-insulating GaAs substrate along the [011] direction is the fourth measuring point. When the dislocation density is measured at two measurement points and the fourth measurement point, the difference between these measured values is preferably within 1700 cm -2 . This makes it possible to make the dislocation density more uniform in all crystal orientations of the main surface.
　［３］上記半絶縁性ＧａＡｓ基板は、上記第１測定点から［０１１］方向に沿って上記半絶縁性ＧａＡｓ基板の外周に至る第２線分の中点を第４測定点とし、上記第２線分上の上記外周から１０ｍｍ内側となる点を第５測定点とし、上記第１測定点、上記第４測定点および上記第５測定点で転位密度を測定した場合、これらの測定値の差が３８００ｃｍ-2以内であることが好ましい。これにより、主面のすべての結晶方位における転位密度をより均一とすることができる。 [3] In the semi-insulating GaAs substrate, the midpoint of the second line segment from the first measuring point to the outer periphery of the semi-insulating GaAs substrate along the [011] direction is the fourth measuring point, and When the point on the two line segments that is 10 mm inside from the outer circumference is the fifth measurement point and the dislocation density is measured at the first measurement point, the fourth measurement point, and the fifth measurement point, these measured values are The difference is preferably within 3800 cm -2 . This makes it possible to make the dislocation density in all the crystal orientations of the main surface more uniform.
　［４］上記半絶縁性ＧａＡｓ基板は、上記第３測定点で転位密度を測定した場合、この測定値が１００００ｃｍ-2以下であることが好ましい。これにより、主面のすべての結晶方位における転位密度をより均一とすることができる。 [4] When the dislocation density of the semi-insulating GaAs substrate is measured at the third measurement point, the measured value is preferably 10,000 cm -2 or less. This makes it possible to make the dislocation density in all the crystal orientations of the main surface more uniform.
　［５］上記半絶縁性ＧａＡｓ基板は、上記第１測定点から［０１１］方向に沿って上記半絶縁性ＧａＡｓ基板の外周に至る第２線分上の上記外周から１０ｍｍ内側となる点を第５測定点とし、上記第５測定点で転位密度を測定した場合、この測定値が１００００ｃｍ-2以下であることが好ましい。これにより、主面のすべての結晶方位における転位密度をより均一とすることができる。 [5] The semi-insulating GaAs substrate has a point 10 mm inside from the outer circumference on a second line segment extending from the first measurement point to the outer circumference of the semi-insulating GaAs substrate along the [011] direction. When the dislocation density is measured at the 5th measurement point and the 5th measurement point, the measured value is preferably 10000 cm -2 or less. This makes it possible to make the dislocation density in all the crystal orientations of the main surface more uniform.
　［６］本開示の一態様に係るＧａＡｓ基板の製造方法は、主面の面方位が（１００）面であるＧａＡｓ基板の製造方法であって、ＧａＡｓ種結晶が底部に収容され、上記ＧａＡｓ種結晶上にＧａＡｓ融液が収容された坩堝と、上記坩堝の外周に沿って配設された発熱体と、上記坩堝および上記発熱体の間に配設された調熱部材とを備えた単結晶成長装置を準備する工程と、上記単結晶成長装置において、上記調熱部材を通過した上記発熱体からの熱で上記ＧａＡｓ種結晶および上記ＧａＡｓ融液を加熱することにより、上記ＧａＡｓ種結晶からＧａＡｓ単結晶を成長させる工程と、上記ＧａＡｓ単結晶を、その成長方向に対して垂直に切出すことにより、上記主面の面方位が（１００）面であるＧａＡｓ基板を得る工程とを含み、上記調熱部材は、上記成長方向に沿って第１調熱部材、第２調熱部材および第３調熱部材の順に分割され、上記第２調熱部材は、波長２μｍ以上３μｍ以下の範囲の光線透過率が、上記第１調熱部材の上記光線透過率および上記第３調熱部材の上記光線透過率に対し２倍以上５倍以下であり、成長中の上記ＧａＡｓ単結晶と上記ＧａＡｓ融液との界面は、上記第２調熱部材を通過した上記発熱体からの熱で加熱される。このような特徴を備えたＧａＡｓ基板の製造方法は、成長中のＧａＡｓ単結晶とＧａＡｓ融液との界面を、その円周方向温度差について軽減を図りつつ所望の温度プロファイルで加熱することができ、もって円周方向温度差に起因する転位密度の増加を抑制することができる。これにより、主面のすべての結晶方位で転位密度が均一となるＧａＡｓ基板を製造することができる。 [6] A method of manufacturing a GaAs substrate according to an aspect of the present disclosure is a method of manufacturing a GaAs substrate in which a main surface has a (100) plane orientation, and a GaAs seed crystal is accommodated in a bottom portion of the GaAs seed crystal. A single crystal comprising a crucible containing a GaAs melt on the crystal, a heating element arranged along the outer periphery of the crucible, and a heat control member arranged between the crucible and the heating element. A step of preparing a growth apparatus, and heating the GaAs seed crystal and the GaAs melt by the heat from the heating element that has passed through the heat control member in the single crystal growth apparatus, thereby changing the GaAs seed crystal to GaAs The method includes the steps of growing a single crystal, and cutting the GaAs single crystal perpendicularly to its growth direction to obtain a GaAs substrate having a main surface with a (100) plane orientation. The heat control member is divided into a first heat control member, a second heat control member, and a third heat control member in this order along the growth direction, and the second heat control member has a wavelength of 2 μm or more and 3 μm or less. The transmittance is 2 to 5 times the light transmittance of the first heat control member and the light transmittance of the third heat control member, and the growing GaAs single crystal and the GaAs melt. The interface between and is heated by the heat from the heating element that has passed through the second heat regulation member. The GaAs substrate manufacturing method having such characteristics can heat the interface between the growing GaAs single crystal and the GaAs melt with a desired temperature profile while reducing the circumferential temperature difference. Therefore, the increase in dislocation density due to the temperature difference in the circumferential direction can be suppressed. This makes it possible to manufacture a GaAs substrate in which the dislocation density is uniform in all crystal orientations of the main surface.
　ここで上記第２調熱部材の上記光線透過率が、上記第１調熱部材の上記光線透過率および上記第３調熱部材の上記光線透過率に対し２倍未満である場合、所望の温度プロファイルを生成することが困難となる。一方、上記第２調熱部材の上記光線透過率が、上記第１調熱部材の上記光線透過率および上記第３調熱部材の上記光線透過率に対し５倍を超えるような調熱部材（第１調熱部材、第２調熱部材および第３調熱部材）は、これを準備することが現実的に困難である。 Here, when the light transmittance of the second heat control member is less than twice the light transmittance of the first heat control member and the light transmittance of the third heat control member, a desired temperature is obtained. It becomes difficult to generate a profile. On the other hand, a heat regulation member in which the light transmittance of the second heat regulation member exceeds five times the light transmittance of the first heat regulation member and the light transmittance of the third heat regulation member ( It is practically difficult to prepare the first heat control member, the second heat control member, and the third heat control member.
　［７］上記第２調熱部材は、上記光線透過率が３０％以上であることが好ましい。これにより所望の温度プロファイルを容易に生成し、かつ成長中のＧａＡｓ単結晶とＧａＡｓ融液との界面において円周方向温度差を軽減することができる。上記光線透過率を上げる手段としては、たとえば高純度原料を使用することによって粒界ガラス相の存在を低減したり、焼結条件を改善することによって結晶粒径を粗大化したりすることなどが挙げられる。 [7] The light transmittance of the second heat regulation member is preferably 30% or more. This makes it possible to easily generate a desired temperature profile and reduce the circumferential temperature difference at the interface between the growing GaAs single crystal and the GaAs melt. Examples of means for increasing the light transmittance include reducing the presence of a grain boundary glass phase by using a high-purity raw material, and coarsening the crystal grain size by improving the sintering conditions. Be done.
　［８］上記第１調熱部材、上記第２調熱部材および上記第３調熱部材は、それぞれムライト、ジルコニア、スピネル、カーボン、アルミナおよびサファイアからなる群より選ばれるいずれかを含むことが好ましい。これにより所望の温度プロファイルを容易に生成し、かつ成長中のＧａＡｓ単結晶とＧａＡｓ融液との界面において円周方向温度差を軽減することができる。 [8] It is preferable that the first heat control member, the second heat control member, and the third heat control member each include any one selected from the group consisting of mullite, zirconia, spinel, carbon, alumina, and sapphire. .. This makes it possible to easily generate a desired temperature profile and reduce the circumferential temperature difference at the interface between the growing GaAs single crystal and the GaAs melt.
　［９］上記第２調熱部材は、ムライト、アルミナおよびサファイアからなる群より選ばれるいずれかを含むことが好ましい。これにより所望の温度プロファイルを容易に生成し、かつ成長中のＧａＡｓ単結晶とＧａＡｓ融液との界面において円周方向温度差を軽減することができる。 [9] The second heat control member preferably contains any one selected from the group consisting of mullite, alumina and sapphire. This makes it possible to easily generate a desired temperature profile and reduce the circumferential temperature difference at the interface between the growing GaAs single crystal and the GaAs melt.
　［１０］上記第２調熱部材は、上記成長方向と平行方向の長さが上記坩堝の内径に対し４０％以上６０％以下であることが好ましい。これにより所望の温度プロファイルを容易に生成し、かつ成長中のＧａＡｓ単結晶とＧａＡｓ融液との界面において円周方向温度差を軽減することができる。 [10] The second heat regulation member preferably has a length in the direction parallel to the growth direction of 40% or more and 60% or less of the inner diameter of the crucible. This makes it possible to easily generate a desired temperature profile and reduce the circumferential temperature difference at the interface between the growing GaAs single crystal and the GaAs melt.
　［１１］上記第１調熱部材および上記第３調熱部材は、表面粗さＲａが２μｍ以上３μｍ以下であることが好ましい。これにより上記第１調熱部材および上記第３調熱部材の表面粗さを、ＧａＡｓの融点である１２３８℃での輻射光の波長ピーク（２～３μｍ）と一致させることができ、上記第１調熱部材および上記第３調熱部材の光線透過率を適切に制御することができる。 [11] The surface roughness Ra of the first heat control member and the third heat control member is preferably 2 μm or more and 3 μm or less. As a result, the surface roughness of the first heat control member and the third heat control member can be made to coincide with the wavelength peak (2 to 3 μm) of the radiated light at 1238° C., which is the melting point of GaAs. The light transmittances of the heat control member and the third heat control member can be appropriately controlled.
　ここで第１調熱部材１１１および第３調熱部材１１３の表面粗さＲａが３μｍを超える場合、上記波長の範囲の光線透過率が過度に低下する傾向がある。第１調熱部材１１１および第３調熱部材１１３の表面粗さＲａを２μｍ未満とした場合、これらの表面粗さＲａが２μｍ以上３μｍ以下である場合と効果において差がなく、加工コストの観点から不経済となる傾向がある。 Here, if the surface roughness Ra of the first heat control member 111 and the third heat control member 113 exceeds 3 μm, the light transmittance in the above wavelength range tends to be excessively reduced. When the surface roughness Ra of the first heat control member 111 and the third heat control member 113 is less than 2 μm, there is no difference in effect from the case where the surface roughness Ra is 2 μm or more and 3 μm or less, and the processing cost is considered. Tends to be uneconomical.
　［１２］上記界面は、その形状が上記成長方向に凸な弧状であることが好ましい。これにより成長中のＧａＡｓ単結晶とＧａＡｓ融液との界面の面内温度分布をより均一にすることができる。 [12] It is preferable that the shape of the interface is an arc shape that is convex in the growth direction. As a result, the in-plane temperature distribution at the interface between the growing GaAs single crystal and the GaAs melt can be made more uniform.
　［１３］上記ＧａＡｓ基板は、半絶縁性であることが好ましい。これにより、比抵抗が１ＭΩｃｍ以上１０００ＭΩｃｍ以下の高抵抗を示す半絶縁性ＧａＡｓ基板を得ることができる。 [13] The GaAs substrate is preferably semi-insulating. As a result, a semi-insulating GaAs substrate having a high specific resistance of 1 MΩcm or more and 1000 MΩcm or less can be obtained.
　［１４］上記第２調熱部材は、その厚みが上記第１調熱部材および上記第３調熱部材に対し０．２倍以上０．５倍以下であることが好ましい。これにより所望の温度プロファイルを容易に生成し、かつ成長中のＧａＡｓ単結晶とＧａＡｓ融液との界面において円周方向温度差を軽減することができる。 [14] The thickness of the second heat regulation member is preferably 0.2 times or more and 0.5 times or less that of the first heat regulation member and the third heat regulation member. This makes it possible to easily generate a desired temperature profile and reduce the circumferential temperature difference at the interface between the growing GaAs single crystal and the GaAs melt.
　ここで上記第２調熱部材の厚みが上記第１調熱部材および上記第３調熱部材の厚みに対し０．５倍を超える場合、所望の温度プロファイルを容易に生成することが困難となる恐れがある。一方、上記第２調熱部材の厚みが上記第１調熱部材および上記第３調熱部材の厚みに対し０．２倍未満となる調熱部材（第１調熱部材、第２調熱部材および第３調熱部材）は、これを準備することが現実的に困難となる恐れがある。 Here, if the thickness of the second heat control member exceeds 0.5 times the thickness of the first heat control member and the third heat control member, it becomes difficult to easily generate a desired temperature profile. There is a fear. On the other hand, the thickness of the second heat regulation member is less than 0.2 times the thickness of the first heat regulation member and the third heat regulation member (first heat regulation member, second heat regulation member). And the third heat regulation member) may be difficult to prepare.
　［１５］上記第１調熱部材、上記第２調熱部材および上記第３調熱部材は、その材質が同一であることが好ましい。これにより所望の温度プロファイルを容易に生成し、かつ成長中のＧａＡｓ単結晶とＧａＡｓ融液との界面において円周方向温度差を軽減することができる。 [15] It is preferable that the first heat regulation member, the second heat regulation member, and the third heat regulation member are made of the same material. This makes it possible to easily generate a desired temperature profile and reduce the circumferential temperature difference at the interface between the growing GaAs single crystal and the GaAs melt.
　［１６］上記第２調熱部材と、上記第１調熱部材および上記第３調熱部材とは、その材質が異なることが好ましい。これにより所望の温度プロファイルを容易に生成し、かつ成長中のＧａＡｓ単結晶とＧａＡｓ融液との界面において円周方向温度差を軽減することができる。 [16] It is preferable that the second heat regulation member and the first heat regulation member and the third heat regulation member are made of different materials. This makes it possible to easily generate a desired temperature profile and reduce the circumferential temperature difference at the interface between the growing GaAs single crystal and the GaAs melt.
　［実施形態の詳細］
　以下、本開示の実施形態（以下「本実施形態」とも記す）についてさらに詳細に説明するが、本実施形態はこれに限定されるものではない。以下では図面を参照しながら説明するが、本明細書および図面において同一または対応する要素に同一の符号を付すものとし、それらについて同じ説明は繰り返さない。 [Details of Embodiment]
Hereinafter, an embodiment of the present disclosure (hereinafter also referred to as “the present embodiment”) will be described in more detail, but the present embodiment is not limited to this. Although the following description will be given with reference to the drawings, the same or corresponding elements in the present specification and the drawings will be denoted by the same reference numerals, and the same description will not be repeated.
　本明細書において「Ａ～Ｂ」という形式の表記は、範囲の上限下限（すなわちＡ以上Ｂ以下）を意味し、Ａにおいて単位の記載がなく、Ｂにおいてのみ単位が記載されている場合、Ａの単位とＢの単位とは同じである。 In the present specification, the notation of the form “AB” means the upper and lower limits of the range (that is, A or more and B or less), and when A does not have a unit and B only has a unit, A The unit of B and the unit of B are the same.
　≪半絶縁性ＧａＡｓ基板≫
　本実施形態に係る半絶縁性ＧａＡｓ基板は、図１に示すように、主面の面方位が（１００）面である半絶縁性ＧａＡｓ基板１である。半絶縁性ＧａＡｓ基板１は、直径が１５０ｍｍ以上である円盤状の形状を有する。さらに半絶縁性ＧａＡｓ基板１は、主面の中心を第１測定点１１とし、第１測定点１１から［０１０］方向に沿って半絶縁性ＧａＡｓ基板１の外周に至る第１線分の中点を第２測定点１２とし、上記第１線分上の上記外周から１０ｍｍ内側となる点を第３測定点１３とし、第１測定点１１、第２測定点１２および第３測定点１３で転位密度を測定した場合、これらの測定値の差が２０００ｃｍ-2以内である。このような特徴を備えた半絶縁性ＧａＡｓ基板１は、主面のすべての結晶方位において転位密度を均一とすることができる。 <<Semi-insulating GaAs substrate>>
The semi-insulating GaAs substrate according to the present embodiment is a semi-insulating GaAs substrate 1 whose main surface has a plane orientation of (100) as shown in FIG. The semi-insulating GaAs substrate 1 has a disk shape having a diameter of 150 mm or more. Further, in the semi-insulating GaAs substrate 1, the center of the main surface is the first measurement point 11, and the first line segment extending from the first measurement point 11 to the outer periphery of the semi-insulating GaAs substrate 1 along the [010] direction The point is the second measurement point 12, the point on the first line segment that is 10 mm inside from the outer circumference is the third measurement point 13, and the first measurement point 11, the second measurement point 12 and the third measurement point 13 are When the dislocation density is measured, the difference between these measured values is within 2000 cm -2 . In the semi-insulating GaAs substrate 1 having such characteristics, the dislocation density can be made uniform in all the crystal orientations of the main surface.
　本明細書において「半絶縁性ＧａＡｓ基板」の「半絶縁性」とは、比抵抗が１ＭΩｃｍ以上１０００ＭΩｃｍ以下の高抵抗を示す性質をいう。したがって本明細書において「半絶縁性ＧａＡｓ基板」とは、比抵抗が１ＭΩｃｍ以上１０００ＭΩｃｍ以下の高抵抗を示すＧａＡｓ基板を意味する。 In the present specification, the “semi-insulating property” of the “semi-insulating GaAs substrate” refers to the property of exhibiting a high specific resistance of 1 MΩcm to 1000 MΩcm. Therefore, in the present specification, the “semi-insulating GaAs substrate” means a GaAs substrate having a high specific resistance of 1 MΩcm or more and 1000 MΩcm or less.
　＜主面および形状＞
　本実施形態に係る半絶縁性ＧａＡｓ基板１は、主面の面方位が（１００）面である半絶縁性ＧａＡｓ基板である。半絶縁性ＧａＡｓ基板１は、その製造方法については本開示の効果が得られる限り制限されるべきではない。たとえば半絶縁性ＧａＡｓ基板１は、後述する製造方法を用いることにより得た半絶縁性ＧａＡｓ単結晶から、その（１００）面を主面として切出すことにより製造することができる。 <Main surface and shape>
The semi-insulating GaAs substrate 1 according to the present embodiment is a semi-insulating GaAs substrate whose main surface has a (100) plane orientation. The method of manufacturing the semi-insulating GaAs substrate 1 should not be limited as long as the effects of the present disclosure can be obtained. For example, the semi-insulating GaAs substrate 1 can be manufactured by cutting a semi-insulating GaAs single crystal obtained by using the manufacturing method described later with its (100) plane as the main surface.
　上記半絶縁性ＧａＡｓ基板１は、直径が１５０ｍｍ以上である円盤状の形状を有する。半絶縁性ＧａＡｓ基板１は、一般に大型であるとされる直径が１５０ｍｍ以上の大きさであっても、主面のすべての結晶方位において転位密度を均一とすることができる。半絶縁性ＧａＡｓ基板１の直径の上限は、製造設備の制約などの理由から２００ｍｍである。本明細書において「直径が１５０ｍｍ」の半絶縁性ＧａＡｓ基板には、６インチの半絶縁性ＧａＡｓ基板を含むものとする。「直径が２００ｍｍ」の半絶縁性ＧａＡｓ基板には、８インチの半絶縁性ＧａＡｓ基板を含むものとする。 The semi-insulating GaAs substrate 1 has a disc shape with a diameter of 150 mm or more. Even if the semi-insulating GaAs substrate 1 has a diameter of 150 mm or more, which is generally considered to be large, the dislocation density can be made uniform in all crystal orientations of the main surface. The upper limit of the diameter of the semi-insulating GaAs substrate 1 is 200 mm because of restrictions on manufacturing equipment. In the present specification, the semi-insulating GaAs substrate having a diameter of 150 mm includes a 6-inch semi-insulating GaAs substrate. The semi-insulating GaAs substrate having a diameter of 200 mm includes a semi-insulating GaAs substrate of 8 inches.
　＜転位密度＞
　半絶縁性ＧａＡｓ基板１は、上述のとおり、主面の中心を第１測定点１１とし、第１測定点１１から［０１０］方向に沿って半絶縁性ＧａＡｓ基板１の外周に至る第１線分の中点を第２測定点１２とし、上記第１線分上の上記外周から１０ｍｍ内側となる点を第３測定点１３とし、第１測定点１１、第２測定点１２および第３測定点１３で転位密度を測定した場合、これらの測定値の差が２０００ｃｍ-2以内である。さらに半絶縁性ＧａＡｓ基板１は、第１測定点１１から［０１１］方向に沿って半絶縁性ＧａＡｓ基板１の外周に至る第２線分の中点を第４測定点１４とし、上記第２線分上の上記外周から１０ｍｍ内側となる点を第５測定点１５とし、第１測定点１１、第４測定点１４および第５測定点１５で転位密度を測定した場合、これらの測定値の差が３８００ｃｍ-2以内であることが好ましい。 <Dislocation density>
As described above, the semi-insulating GaAs substrate 1 has the center of the main surface as the first measurement point 11, and the first line extending from the first measurement point 11 to the outer periphery of the semi-insulating GaAs substrate 1 along the [010] direction. The midpoint of the minute is the second measurement point 12, the point on the first line segment that is 10 mm inside from the outer circumference is the third measurement point 13, and the first measurement point 11, the second measurement point 12, and the third measurement point. When the dislocation density is measured at point 13, the difference between these measured values is within 2000 cm -2 . Further, in the semi-insulating GaAs substrate 1, the midpoint of the second line segment from the first measuring point 11 to the outer periphery of the semi-insulating GaAs substrate 1 along the [011] direction is defined as the fourth measuring point 14, and the second measuring point When the point on the line segment that is 10 mm inside from the outer circumference is the fifth measurement point 15 and the dislocation density is measured at the first measurement point 11, the fourth measurement point 14 and the fifth measurement point 15, The difference is preferably within 3800 cm -2 .
　半絶縁性ＧａＡｓ基板１は、第１測定点１１、第２測定点１２および第３測定点１３における転位密度の測定値の差が２０００ｃｍ-2以内である場合、これに加えて好ましくは第１測定点１１、第４測定点１４および第５測定点１５における転位密度の測定値の差が３８００ｃｍ-2以内である場合において、主面のすべての結晶方位において転位密度が均一であると判断される理由は、次のとおりである。 In the semi-insulating GaAs substrate 1, in addition to this, when the difference in the measured values of the dislocation density at the first measurement point 11, the second measurement point 12 and the third measurement point 13 is within 2000 cm −2, it is preferable that When the difference between the measured dislocation densities at the measurement point 11, the fourth measurement point 14 and the fifth measurement point 15 is within 3800 cm -2, it is determined that the dislocation density is uniform in all the crystal orientations of the main surface. The reason for this is as follows.
　一般に、半絶縁ＧａＡｓ基板の転位密度が大きくなる理由は、上記基板を構成する単結晶の結晶成長中および冷却中において面内に温度差が生じることにより、熱応力によって転位が導入されるとともに、それが増殖するためであると考えられている。結晶成長中および冷却中の単結晶において熱応力は、その絶対値が単結晶の中央部と外周部とで大きくなり、径方向の中央付近で小さくなることが知られている。このため、転位密度も単結晶の中央部と外周部とで大きく、径方向の中央付近で小さくなる傾向がある。 In general, the reason why the dislocation density of a semi-insulating GaAs substrate is high is that dislocations are introduced by thermal stress due to a temperature difference in the plane during crystal growth and cooling of the single crystal forming the substrate, and It is believed that it is due to proliferation. It is known that the absolute value of the thermal stress in a single crystal during crystal growth and cooling increases in the central portion and the outer peripheral portion of the single crystal and decreases in the vicinity of the radial center. Therefore, the dislocation density also tends to be high in the central portion and the outer peripheral portion of the single crystal and small in the vicinity of the radial center.
　上記の傾向が半絶縁ＧａＡｓ基板に現れることにより、半絶縁ＧａＡｓ基板は、主面の面方位が（１００）面である場合、ＧａＡｓ単結晶の特性上、［０１０］方向の外周部（たとえば、半絶縁性ＧａＡｓ基板１の第３測定点１３）で転位密度が最大となりやすく、［０１１］方向の径方向の中点付近（たとえば、半絶縁性ＧａＡｓ基板１の第４測定点１４）で転位密度が最小となりやすいことが知られている。このため、これらの特徴的な２方向（［０１０］方向および［０１１］方向）において転位密度の均一性を評価することにより、主面における転位密度の総合的な均一性を判断することができると考えられる。特に、主面の面方位が（１００）面である半絶縁ＧａＡｓ基板において転位密度の均一性を求める場合、転位密度が最大となりやすい［０１０］方向の外周部での転位密度を抑えることがより重要となる。 Due to the above tendency appearing in the semi-insulating GaAs substrate, the semi-insulating GaAs substrate, when the main surface has a plane orientation of (100), is characterized by the characteristics of the GaAs single crystal. The dislocation density is likely to be maximized at the third measurement point 13) of the semi-insulating GaAs substrate 1, and the dislocation is near the midpoint in the radial direction of the [011] direction (for example, the fourth measurement point 14 of the semi-insulating GaAs substrate 1). It is known that the density tends to be the minimum. Therefore, by evaluating the uniformity of the dislocation density in these two characteristic directions ([010] direction and [011] direction), it is possible to determine the overall uniformity of the dislocation density on the main surface. it is conceivable that. In particular, in the case of obtaining the uniformity of dislocation density in a semi-insulating GaAs substrate whose main surface has a (100) plane orientation, it is more preferable to suppress the dislocation density at the outer peripheral portion in the [010] direction where the dislocation density is likely to be maximum. It becomes important.
　そして半絶縁性ＧａＡｓ基板１は、第１測定点１１、第２測定点１２および第３測定点１３における転位密度の測定値の差が２０００ｃｍ-2以内である場合、主面の中心から［０１０］方向において転位密度のバラツキが抑えられていると評価される。これにより、主面の中心から［０１０］方向において転位密度が均一であると判断することができる。半絶縁性ＧａＡｓ基板１において、主面の中心から［０１０］方向、［００－１］方向、［０－１０］方向および［００１］方向は、等価な４方向である。したがって、主面の中心から［０１０］方向において転位密度が均一であると判断することができる場合、半絶縁性ＧａＡｓ基板１は、これらの等価な４方向においても転位密度が均一であると判断することができる。 In the semi-insulating GaAs substrate 1, when the difference between the measured dislocation densities at the first measurement point 11, the second measurement point 12 and the third measurement point 13 is within 2000 cm -2 , [010 It is evaluated that variations in dislocation density are suppressed in the [] direction. This makes it possible to determine that the dislocation density is uniform in the [010] direction from the center of the main surface. In the semi-insulating GaAs substrate 1, the [010] direction, the [00-1] direction, the [0-10] direction, and the [001] direction are four equivalent directions from the center of the main surface. Therefore, when it can be determined that the dislocation density is uniform in the [010] direction from the center of the main surface, the semi-insulating GaAs substrate 1 is determined to have uniform dislocation density also in these four equivalent directions. can do.
　さらに半絶縁性ＧａＡｓ基板１は、第１測定点１１、第４測定点１４および第５測定点１５における転位密度の測定値の差が３８００ｃｍ-2以内であることが好ましい。この場合、半絶縁性ＧａＡｓ基板１は、主面の中心から［０１１］方向において転位密度のバラツキが抑えられていると評価される。これにより、主面の中心から［０１１］方向においても転位密度が均一であると判断することができる。半絶縁性ＧａＡｓ基板１において、主面の中心から［０１１］方向、［０１－１］方向、［０－１－１］方向および［０－１１］方向は、等価な４方向である。したがって、主面の中心から［０１１］方向において転位密度が均一であると判断することができる場合、半絶縁性ＧａＡｓ基板１は、これらの等価な４方向においても転位密度が均一であると判断することができる。 Further, in the semi-insulating GaAs substrate 1, it is preferable that the difference between the measured dislocation densities at the first measurement point 11, the fourth measurement point 14 and the fifth measurement point 15 is within 3800 cm -2 . In this case, it is estimated that the semi-insulating GaAs substrate 1 has suppressed dislocation density variation in the [011] direction from the center of the main surface. This makes it possible to determine that the dislocation density is uniform even in the [011] direction from the center of the main surface. In the semi-insulating GaAs substrate 1, the [011] direction, the [01-1] direction, the [0-1-1] direction, and the [0-11] direction from the center of the main surface are four equivalent directions. Therefore, when it can be judged that the dislocation density is uniform in the [011] direction from the center of the main surface, the semi-insulating GaAs substrate 1 is judged to have uniform dislocation density also in these four equivalent directions. can do.
　次に半絶縁性ＧａＡｓ基板１において、主面の中心から［０１０］方向およびこの方向を含む等価な４方向、ならびに主面の中心から［０１１］方向およびこの方向を含む等価な４方向を除いた他の結晶方位における転位密度のバラツキは、これらの合計８方向における転位密度のバラツキよりも小さくなることが知られている。したがって半絶縁性ＧａＡｓ基板１は、主面の中心から［０１０］方向、および主面の中心から［０１１］方向において転位密度が均一であると判断することができる場合、他の結晶方位における転位密度はより均一であると推定することができる。 Next, in the semi-insulating GaAs substrate 1, the [010] direction from the center of the main surface and four equivalent directions including this direction, and the [011] direction from the center of the main surface and four equivalent directions including this direction are excluded. It is known that variations in dislocation density in other crystal orientations are smaller than those in total 8 directions. Therefore, in the semi-insulating GaAs substrate 1, when it can be judged that the dislocation density is uniform in the [010] direction from the center of the main surface and in the [011] direction from the center of the main surface, dislocations in other crystal orientations are obtained. The density can be estimated to be more uniform.
　以上から、半絶縁性ＧａＡｓ基板１は、第１測定点１１、第２測定点１２および第３測定点１３における転位密度の測定値の差が２０００ｃｍ-2以内である場合、これに加えて好ましくは第１測定点１１、第４測定点１４および第５測定点１５における転位密度の測定値の差が３８００ｃｍ-2以内である場合、主面のすべての結晶方位において転位密度が均一であると判断することができる。 From the above, the semi-insulating GaAs substrate 1 is preferable in addition to this when the difference in the measured values of the dislocation density at the first measurement point 11, the second measurement point 12 and the third measurement point 13 is within 2000 cm -2. Indicates that when the difference between the measured dislocation densities at the first measurement point 11, the fourth measurement point 14 and the fifth measurement point 15 is within 3800 cm −2 , the dislocation density is uniform in all crystal orientations of the main surface. You can judge.
　ここで「主面の中心」とは、図１に示すような半絶縁性ＧａＡｓ基板１の主面を円であると仮定した場合において、その円の中心を指す。図１においてＯＦはオリエンテーションフラットを意味し、ＩＦはインデックスフラットを意味する。半絶縁性ＧａＡｓ基板１は、（１００）面を主面とした場合、ＯＦは［０－１－１］方向に設けられ、ＩＦは［０－１１］方向に設けられるのが一般的である。このＯＦとＩＦとの位置関係により、半絶縁性ＧａＡｓ基板１を構成している単結晶の結晶方位が明らかにされる。ＯＦとＩＦとの位置関係により、基板の表面および裏面も判別することができる。 Here, the "center of the main surface" means the center of the circle, assuming that the main surface of the semi-insulating GaAs substrate 1 as shown in FIG. 1 is a circle. In FIG. 1, OF means orientation flat and IF means index flat. In the semi-insulating GaAs substrate 1, when the (100) plane is the main surface, OF is generally provided in the [0-1-1] direction and IF is generally provided in the [0-11] direction. .. The positional relationship between OF and IF clarifies the crystal orientation of the single crystal forming the semi-insulating GaAs substrate 1. The front surface and the back surface of the substrate can also be discriminated from the positional relationship between OF and IF.
　図１において、上述した「主面の中心から［０１０］方向を含む等価な４方向」は、「≪」の印を付した放射状の線により模式的に示されている。さらに図１において、上述した「主面の中心から［０１１］方向を含む等価な４方向」は、「＜」の印を付した放射状の線により模式的に示されている。結晶方位を表記する際に表わす「－」は本来、数字の頭上に表わされるもので「バー」と読まれる。たとえば、［０１－１］は、「ゼロ・イチ・イチ・バー」と読まれる。 In FIG. 1, the above-mentioned “equivalent four directions including the [010] direction from the center of the principal surface” are schematically shown by radial lines marked with “<<”. Further, in FIG. 1, the “equivalent four directions including the [011] direction from the center of the main surface” described above is schematically shown by radial lines marked with “<”. The "-" that is shown when describing the crystal orientation is originally shown above the number and is read as a "bar". For example, [01-1] is read as "zero-ichi-bar".
　本実施形態に係る半絶縁性ＧａＡｓ基板１は、第１測定点１１、第２測定点１２および第３測定点１３における転位密度の測定値の差は、１０００ｃｍ-2以内であることが好ましい。これらの測定点での転位密度の測定値の差は、０（ゼロ）が下限値である。さらに第１測定点１１、第４測定点１４および第５測定点１５での転位密度の測定値の差は、２０００ｃｍ-2以内であることがより好ましい。これらの測定点での転位密度の測定値の差は、０（ゼロ）が下限値である。これにより、主面のすべての結晶方位において転位密度をより均一とすることができる。 In the semi-insulating GaAs substrate 1 according to this embodiment, it is preferable that the difference in the measured values of dislocation density at the first measurement point 11, the second measurement point 12, and the third measurement point 13 is within 1000 cm −2 . The lower limit of the difference between the dislocation density measurement values at these measurement points is 0 (zero). Further, it is more preferable that the difference between the measured values of the dislocation density at the first measurement point 11, the fourth measurement point 14, and the fifth measurement point 15 is within 2000 cm -2 . The lower limit of the difference between the dislocation density measurement values at these measurement points is 0 (zero). As a result, the dislocation density can be made more uniform in all crystal orientations of the main surface.
　半絶縁性ＧａＡｓ基板１は、第１測定点１１から［０１１］方向に沿って半絶縁性ＧａＡｓ基板１の外周に至る第２線分の中点を第４測定点１４とし、上記第２測定点１２および第４測定点１４で転位密度を測定した場合、これらの測定値の差が１７００ｃｍ-2以内であることが好ましい。第２測定点１２および第４測定点１４での転位密度の測定値の差は、１０００ｃｍ-2以内であることがより好ましい。これらの測定点での転位密度の測定値の差は、０（ゼロ）が下限値である。これにより、主面のすべての結晶方位において転位密度をより均一とすることができる。 In the semi-insulating GaAs substrate 1, the midpoint of the second line segment from the first measuring point 11 to the outer periphery of the semi-insulating GaAs substrate 1 along the [011] direction is defined as the fourth measuring point 14, and the second measuring When the dislocation density is measured at the point 12 and the fourth measurement point 14, the difference between these measured values is preferably within 1700 cm −2 . The difference between the measured dislocation densities at the second measurement point 12 and the fourth measurement point 14 is more preferably within 1000 cm -2 . The lower limit of the difference between the dislocation density measurement values at these measurement points is 0 (zero). As a result, the dislocation density can be made more uniform in all crystal orientations of the main surface.
　半絶縁性ＧａＡｓ基板１は、第３測定点１３で転位密度を測定した場合、この測定値が１００００ｃｍ-2以下であることが好ましい。半絶縁性ＧａＡｓ基板１は、第１測定点１１から［０１１］方向に沿って半絶縁性ＧａＡｓ基板１の外周に至る第２線分上の上記外周から１０ｍｍ内側となる点を第５測定点１５とし、第５測定点１５で転位密度を測定した場合、この測定値が１００００ｃｍ-2以下であることが好ましい。第３測定点１３および第５測定点１５における転位密度の測定値は、各々８０００ｃｍ-2以下であることがより好ましい。第３測定点１３および第５測定点１５における転位密度の測定値は、基板使用時の昇温によって転位密度が増加することを抑制する観点から、それぞれ３０００ｃｍ-2以上であることが好ましい。半絶縁性ＧａＡｓ基板１は、これらの数値範囲を満たすことにより、主面のすべての結晶方位において転位密度をより均一とすることができる。 When the dislocation density of the semi-insulating GaAs substrate 1 is measured at the third measuring point 13, the measured value is preferably 10000 cm -2 or less. The semi-insulating GaAs substrate 1 is located at a point 10 mm inside from the outer circumference on the second line segment from the first measuring point 11 to the outer circumference of the semi-insulating GaAs substrate 1 along the [011] direction. When the dislocation density is measured at the fifth measurement point 15, the measured value is preferably 10000 cm -2 or less. The measured values of dislocation density at the third measurement point 13 and the fifth measurement point 15 are more preferably 8000 cm -2 or less. The measured values of the dislocation density at the third measurement point 13 and the fifth measurement point 15 are each preferably 3000 cm -2 or more from the viewpoint of suppressing the increase of the dislocation density due to the temperature rise during use of the substrate. By satisfying these numerical ranges, the semi-insulating GaAs substrate 1 can have a more uniform dislocation density in all crystal orientations of the main surface.
　＜転位密度の測定方法＞
　転位密度は、半絶縁性ＧａＡｓ基板１の主面をエッチング液などによりエッチングし、エッチピット密度を測定することにより求めることができる。エッチピット密度は、学術的には転位密度と同義ではないが、本技術分野において転位密度と等価なものとして捉えられている。エッチピット密度は、半絶縁性ＧａＡｓ基板１の主面をピットサイズが５０～１００μｍの範囲となるようにエッチングし、このエッチングした主面を顕微鏡により１００倍に拡大し、この顕微鏡像中の１ｍｍ□視野内におけるエッチピット数をカウントすることにより求めることができる。半絶縁性ＧａＡｓ基板１のエッチングに用いるエッチング液としては、熔融水酸化カリウムを用いることができる。 <Measurement method of dislocation density>
The dislocation density can be obtained by etching the main surface of the semi-insulating GaAs substrate 1 with an etching solution or the like and measuring the etch pit density. The etch pit density is not synonymous with the dislocation density academically, but is regarded as equivalent to the dislocation density in this technical field. The etch pit density is 1 mm in the microscope image obtained by etching the main surface of the semi-insulating GaAs substrate 1 so that the pit size is in the range of 50 to 100 μm, and enlarging the etched main surface 100 times with a microscope. □ It can be obtained by counting the number of etch pits in the visual field. Molten potassium hydroxide can be used as an etching solution for etching the semi-insulating GaAs substrate 1.
　本実施形態における転位密度の測定値、およびその差の具体的な算出方法は次のとおりである。すなわち、たとえば後述するＧａＡｓ基板の製造方法により、まず半絶縁性ＧａＡｓ基板１を３枚得る。この３枚の半絶縁性ＧａＡｓ基板１の各々に対し、上述した測定方法を用いることにより、第１測定点１１、第２測定点１２、第３測定点１３、第４測定点１４および第５測定点１５においてエッチピット密度を測定する。次いで、各測定点で測定したエッチピット密度に基づき、第１測定点１１、第２測定点１２および第３測定点１３での測定値の差、第１測定点１１、第４測定点１４および第５測定点１５での測定値の差、第２測定点１２および第４測定点１４での測定値の差を、転位密度の測定に用いた半絶縁性ＧａＡｓ基板１ごとに求める。最後に、これらの測定値の差を、転位密度の測定に用いた半絶縁性ＧａＡｓ基板１の３枚で平均値化することにより、この平均値を転位密度の測定値の差として求めることができる。第３測定点１３および第５測定点１５での転位密度の測定値については、転位密度の測定に用いた半絶縁性ＧａＡｓ基板１ごとに求めた第３測定点１３および第５測定点１５での測定値を平均値化することにより、この平均値を第３測定点１３および第５測定点１５の転位密度の測定値として求めることができる。これにより半絶縁性ＧａＡｓ基板１において、その主面のすべての結晶方位において転位密度が均一であるか否かを判断することができる。 The measured values of dislocation density and the specific method of calculating the difference in the present embodiment are as follows. That is, for example, three semi-insulating GaAs substrates 1 are first obtained by the method of manufacturing a GaAs substrate described later. By using the above-described measuring method for each of the three semi-insulating GaAs substrates 1, the first measuring point 11, the second measuring point 12, the third measuring point 13, the fourth measuring point 14, and the fifth measuring point 11. At the measurement point 15, the etch pit density is measured. Then, based on the etch pit density measured at each measurement point, the difference between the measurement values at the first measurement point 11, the second measurement point 12 and the third measurement point 13, the first measurement point 11, the fourth measurement point 14 and The difference between the measured values at the fifth measuring point 15 and the difference between the measured values at the second measuring point 12 and the fourth measuring point 14 are obtained for each semi-insulating GaAs substrate 1 used for measuring the dislocation density. Finally, by averaging the difference between these measured values for the three semi-insulating GaAs substrates 1 used for measuring the dislocation density, this average value can be obtained as the difference between the measured dislocation density values. it can. Regarding the measured values of the dislocation density at the third measurement point 13 and the fifth measurement point 15, the measured values of the dislocation density at the third measurement point 13 and the fifth measurement point 15 obtained for each semi-insulating GaAs substrate 1 used for measuring the dislocation density By averaging the measured values of, the average value can be obtained as the measured value of the dislocation density at the third measurement point 13 and the fifth measurement point 15. This makes it possible to determine whether or not the dislocation density is uniform in all crystal orientations of the main surface of the semi-insulating GaAs substrate 1.
　＜作用＞
　以上より、本実施形態に係る半絶縁性ＧａＡｓ基板は、面方位が（１００）面である主面のすべての結晶方位において転位密度を均一とすることができる。 <Action>
As described above, in the semi-insulating GaAs substrate according to this embodiment, the dislocation density can be made uniform in all the crystal orientations of the main surface whose plane orientation is the (100) plane.
　≪ＧａＡｓ基板の製造方法≫
　本実施形態に係るＧａＡｓ基板の製造方法は、主面の面方位が（１００）面であるＧａＡｓ基板の製造方法である。ＧａＡｓ基板の製造方法は、たとえば図２に示すように、ＧａＡｓ種結晶Ｓが底部に収容され、ＧａＡｓ種結晶Ｓ上にＧａＡｓ融液Ｌが収容された坩堝１０１と、坩堝１０１の外周に沿って配設された発熱体１０２と、坩堝１０１および発熱体１０２の間に配設された調熱部材１１０とを備えた単結晶成長装置を準備する工程（第１工程）と、上記単結晶成長装置において、調熱部材１１０を通過した発熱体１０２からの熱でＧａＡｓ種結晶ＳおよびＧａＡｓ融液Ｌを加熱することにより、ＧａＡｓ種結晶ＳからＧａＡｓ単結晶Ｃを成長させる工程（第２工程）と、ＧａＡｓ単結晶Ｃを、その成長方向に対して垂直に切出すことにより、主面の面方位が（１００）面であるＧａＡｓ基板を得る工程（第３工程）とを含む。坩堝１０１内のＧａＡｓ種結晶ＳおよびＧａＡｓ融液Ｌの上には、ＧａＡｓの飛散を防止するため液体封止材Ｅが配置されることが好ましい。液体封止材Ｅの材料としては、たとえば酸化ホウ素（Ｂ2Ｏ3）を用いることができる。 <<Method for manufacturing GaAs substrate>>
The method for manufacturing a GaAs substrate according to this embodiment is a method for manufacturing a GaAs substrate in which the plane orientation of the main surface is the (100) plane. As shown in FIG. 2, for example, a GaAs substrate is manufactured by a crucible 101 in which a GaAs seed crystal S is housed in the bottom and a GaAs melt L is housed on the GaAs seed crystal S, and along the outer circumference of the crucible 101. A step (first step) of preparing a single crystal growth apparatus provided with the heating element 102 provided and a heat control member 110 provided between the crucible 101 and the heating element 102; In step (2), the GaAs seed crystal S and the GaAs melt L are heated by the heat from the heating element 102 that has passed through the heat control member 110 to grow a GaAs single crystal C from the GaAs seed crystal S (second step). , GaAs single crystal C is cut out perpendicularly to its growth direction to obtain a GaAs substrate having a main surface with a (100) plane orientation (third step). A liquid sealing material E is preferably disposed on the GaAs seed crystal S and the GaAs melt L in the crucible 101 in order to prevent GaAs from scattering. As a material of the liquid sealing material E, for example, boron oxide (B 2 O 3 ) can be used.
　調熱部材１１０は、上記成長方向に沿って（図２において下側から）第１調熱部材１１１、第２調熱部材１１２および第３調熱部材１１３の順に分割されている。第２調熱部材１１２は、波長２μｍ以上３μｍ以下の範囲の光線透過率が、第１調熱部材１１１の上記光線透過率および第３調熱部材１１３の上記光線透過率に対し２倍以上５倍以下である。成長中のＧａＡｓ単結晶ＣとＧａＡｓ融液Ｌとの界面Ｉは、第２調熱部材１１２を通過した発熱体１０２からの熱で加熱される。このような特徴を備えたＧａＡｓ基板の製造方法は、成長中のＧａＡｓ単結晶ＣとＧａＡｓ融液Ｌとの界面Ｉを、その円周方向温度差について軽減を図りつつ所望の温度プロファイルで加熱することができ、もって上記界面の面内温度分布を均一とすることができる。これにより、主面のすべての結晶方位で転位密度が均一となるＧａＡｓ基板を製造することができる。 The heat control member 110 is divided along the growth direction (from the lower side in FIG. 2) in the order of the first heat control member 111, the second heat control member 112, and the third heat control member 113. The light transmittance of the second heat control member 112 in the wavelength range of 2 μm or more and 3 μm or less is twice or more the light transmittance of the first heat control member 111 and the light transmittance of the third heat control member 113. It is less than twice. The interface I between the growing GaAs single crystal C and the GaAs melt L is heated by the heat from the heating element 102 that has passed through the second heat control member 112. In the method of manufacturing a GaAs substrate having such characteristics, the interface I between the growing GaAs single crystal C and the GaAs melt L is heated with a desired temperature profile while reducing the temperature difference in the circumferential direction. Therefore, the in-plane temperature distribution of the interface can be made uniform. This makes it possible to manufacture a GaAs substrate in which the dislocation density is uniform in all crystal orientations of the main surface.
　ここで本明細書においてＧａＡｓ単結晶の「成長方向」とは、ＧａＡｓ種結晶が、これを起点にＧａＡｓ融液を材料としてＧａＡｓ単結晶に成長していく方向をいい、通常、ＧａＡｓ種結晶とＧａＡｓ融液とが接触する接触面に対して垂直な方向をいう。したがって、たとえばＧａＡｓ種結晶とＧａＡｓ融液との接触面の面方位が（１００）面である場合、ＧａＡｓ単結晶の「成長方向」は［１００］方向となる。 Here, in the present specification, the "growth direction" of a GaAs single crystal means a direction in which a GaAs seed crystal grows into a GaAs single crystal using a GaAs melt as a starting material. The direction perpendicular to the contact surface with which the GaAs melt contacts. Therefore, for example, when the plane orientation of the contact surface between the GaAs seed crystal and the GaAs melt is the (100) plane, the “growth direction” of the GaAs single crystal is the [100] direction.
　上述のように、上記製造方法により得られるＧａＡｓ基板は、主面の面方位が（１００）面である。このＧａＡｓ基板は、半絶縁性であることが好ましい。すなわち上記製造方法により、比抵抗が１ＭΩｃｍ以上１０００ＭΩｃｍ以下の高抵抗を示す半絶縁性ＧａＡｓ基板を得ることができる。 As described above, the principal plane of the GaAs substrate obtained by the above manufacturing method is the (100) plane. This GaAs substrate is preferably semi-insulating. That is, according to the above manufacturing method, a semi-insulating GaAs substrate having a high specific resistance of 1 MΩcm or more and 1000 MΩcm or less can be obtained.
　＜第１工程＞
　第１工程は、ＧａＡｓ種結晶Ｓが底部に収容され、ＧａＡｓ種結晶Ｓ上にＧａＡｓ融液Ｌが収容された坩堝１０１と、坩堝１０１の外周に沿って配設された発熱体１０２と、坩堝１０１および発熱体１０２の間に配設された調熱部材１１０とを備えた単結晶成長装置を準備する工程である。すなわち第１工程は、図２～図４に例示されるような単結晶成長装置を準備する工程である。このため以下の説明においては、図２～図４に基づいてさらに第１工程を詳述する。 <First step>
In the first step, a crucible 101 having a GaAs seed crystal S accommodated in its bottom and a GaAs melt L accommodated on the GaAs seed crystal S, a heating element 102 arranged along the outer periphery of the crucible 101, and a crucible. This is a step of preparing a single crystal growth apparatus provided with a heat control member 110 disposed between 101 and a heating element 102. That is, the first step is a step of preparing a single crystal growth apparatus as exemplified in FIGS. Therefore, in the following description, the first step will be further described in detail with reference to FIGS.
　（単結晶成長装置）
　単結晶成長装置は、たとえば図２～図４に示すように、ＧａＡｓ種結晶Ｓが底部に収容され、ＧａＡｓ種結晶Ｓ上にＧａＡｓ融液Ｌが収容された坩堝１０１と、坩堝１０１の外周に沿って配設された発熱体１０２と、坩堝１０１および発熱体１０２の間に配設された調熱部材１１０とを備える。 (Single crystal growth equipment)
The single crystal growth apparatus is, for example, as shown in FIGS. 2 to 4, a crucible 101 in which a GaAs seed crystal S is accommodated at the bottom and a GaAs melt L is accommodated on the GaAs seed crystal S, and an outer periphery of the crucible 101. The heating element 102 is provided along the heating element 102, and the heat control member 110 is provided between the crucible 101 and the heating element 102.
　（坩堝）
　坩堝１０１は、底部が下端に向かってテーパ状に縮閉する円筒状形状を有し、上記底部にＧａＡｓ種結晶Ｓが収容される。ＧａＡｓ種結晶Ｓ上にはＧａＡｓ融液Ｌが収容される。これらＧａＡｓ種結晶ＳおよびＧａＡｓ融液Ｌの上には、ＧａＡｓの飛散を防止するため酸化ホウ素（Ｂ2Ｏ3）などからなる液体封止材Ｅが配置されることが好ましい。ＧａＡｓ種結晶Ｓは、主面の面方位が（１００）面であるＧａＡｓ基板を得る目的で、ＧａＡｓ融液Ｌとの接触面の面方位が（１００）面となるように、坩堝１０１の底部に収容されることが好ましい。ここで図２～図４では、ＧａＡｓ種結晶ＳとＧａＡｓ融液Ｌとの間に、後述する第２工程を行なうことによって形成される成長中のＧａＡｓ単結晶Ｃが表されている。さらに図２～図４では、ＧａＡｓ種結晶ＳとＧａＡｓ単結晶Ｃとが説明の便宜のために別々の結晶のように界面を有して表されている。しかしながらＧａＡｓ単結晶Ｃは、ＧａＡｓ種結晶Ｓを起点として成長するため、これらの間に界面は存在しない。 (crucible)
The crucible 101 has a cylindrical shape in which the bottom is tapered and closed toward the lower end, and the GaAs seed crystal S is accommodated in the bottom. The GaAs melt L is contained on the GaAs seed crystal S. A liquid encapsulant E made of boron oxide (B 2 O 3 ) or the like is preferably disposed on the GaAs seed crystal S and the GaAs melt L to prevent GaAs from scattering. The GaAs seed crystal S has a bottom surface of the crucible 101 so that the surface orientation of the contact surface with the GaAs melt L is the (100) surface for the purpose of obtaining a GaAs substrate having the main surface orientation of the (100) surface. Is preferably housed in Here, FIGS. 2 to 4 show a growing GaAs single crystal C formed between the GaAs seed crystal S and the GaAs melt L by performing a second step described later. Further, in FIGS. 2 to 4, the GaAs seed crystal S and the GaAs single crystal C are shown as having separate interfaces for convenience of description. However, since the GaAs single crystal C grows starting from the GaAs seed crystal S, there is no interface between them.
　坩堝１０１の内径は、成長中のＧａＡｓ単結晶Ｃの直径に相当し、すなわちＧａＡｓ基板の直径に相当する。このため坩堝１０１の内径は１５０～２００ｍｍであることが好ましい。坩堝１０１は、本開示の効果を奏する限り、１２３８℃に耐熱可能かつ熱衝撃に耐える材料である限り、従来公知のあらゆる種類の材料により構成することができる。坩堝１０１の材料としては、たとえばカーボン、窒化硼素（ＢＮ）、石英などを例示することができる。 The inner diameter of the crucible 101 corresponds to the diameter of the growing GaAs single crystal C, that is, the diameter of the GaAs substrate. Therefore, the inner diameter of the crucible 101 is preferably 150 to 200 mm. As long as the effect of the present disclosure is exhibited, the crucible 101 can be made of any conventionally known material as long as it is a material that can withstand heat at 1238° C. and can withstand thermal shock. Examples of the material of the crucible 101 include carbon, boron nitride (BN), and quartz.
　ＧａＡｓ種結晶Ｓは、従来公知の方法により製造したＧａＡｓ単結晶を用いることができる。たとえばＧａＡｓ種結晶Ｓは、ＶＢ法、液体封止チョクラルスキー（ＬＥＣ）法、蒸気圧制御チョクラルスキー（ＶＣＺ）法および水平ブリッジマン（ＨＢ）法などに基づいて製造することができる。ＧａＡｓ種結晶Ｓに対し、カーボン、ホウ素、酸素などの不純物をドーパントとしてドープ（添加）することができる。 As the GaAs seed crystal S, a GaAs single crystal manufactured by a conventionally known method can be used. For example, the GaAs seed crystal S can be manufactured based on the VB method, the liquid sealed Czochralski (LEC) method, the vapor pressure controlled Czochralski (VCZ) method, the horizontal Bridgman (HB) method, and the like. Impurities such as carbon, boron, and oxygen can be doped (added) into the GaAs seed crystal S as dopants.
　ＧａＡｓ融液Ｌも、従来公知の方法により製造することができる。たとえば、まず所定の合成炉内に液体のＧａと固体のＡｓとをモル比で１：１となる量それぞれ準備する。次にＡｓを６６０℃以上に加熱することにより昇華させて気体とする。この気体となったＡｓを注入法によりＧａの液体中に送り込み、ＧａとＡｓとを反応させた後、これを固化して固体のＧａＡｓを得る。最後に、この固体のＧａＡｓを坩堝１０１に投入し、坩堝１０１内で再加熱することによってＧａＡｓ融液Ｌを得ることができる。ＧａＡｓ融液Ｌに対しても、カーボン、ホウ素、酸素などの不純物をドーパントとしてドープ（添加）することができる。 The GaAs melt L can also be manufactured by a conventionally known method. For example, first, liquid Ga and solid As are prepared in predetermined synthesis furnaces in an amount of 1:1 in molar ratio. Next, As is heated to 660° C. or higher to be sublimated into gas. The gasified As is fed into the Ga liquid by an injection method to react Ga with As and then solidified to obtain solid GaAs. Finally, this solid GaAs is put into the crucible 101 and reheated in the crucible 101 to obtain the GaAs melt L. It is possible to dope (add) impurities such as carbon, boron and oxygen into the GaAs melt L as a dopant.
　（発熱体）
　発熱体１０２は、坩堝１０１の外周に沿って配設される。発熱体１０２は、線状発熱体であって、坩堝１０１の外周面をＧａＡｓ単結晶Ｃの成長方向に沿ってらせん状に包囲するように配設される。発熱体１０２は、らせん状の形状を上方から平面視することにより現れる円が、坩堝１０１を上方から平面視することにより現れる円との関係において同心円となることが好ましい。たとえば坩堝１０１と発熱体１０２とは、坩堝１０１の外周面から発熱体１０２までの最短距離が１０～１５ｃｍの同心円となる関係であることが好ましい。 (Heating element)
The heating element 102 is arranged along the outer periphery of the crucible 101. The heating element 102 is a linear heating element and is arranged so as to spirally surround the outer peripheral surface of the crucible 101 along the growth direction of the GaAs single crystal C. In the heating element 102, it is preferable that a circle that appears when the spiral shape is viewed from above in a plan view is concentric with the circle that appears when the crucible 101 is viewed from above in a plan view. For example, it is preferable that the crucible 101 and the heating element 102 have a concentric relationship with the shortest distance from the outer peripheral surface of the crucible 101 to the heating element 102 being 10 to 15 cm.
　発熱体１０２は、本開示の効果を奏する限り、従来公知のあらゆる種類の材料により構成することができる。なかでも発熱体１０２は、１０００℃以上の高温となるので、たとえばＦｅ－Ｃｒ－Ａｌ系発熱体、ＭｏＳｉ2系発熱体、カーボン、モリブデンなどの耐熱材料を好適に用いることができる。 The heating element 102 can be made of all kinds of conventionally known materials as long as the effects of the present disclosure are exhibited. Among them, since the heating element 102 has a high temperature of 1000° C. or higher, a heat-resistant material such as Fe—Cr—Al-based heating element, MoSi 2 -based heating element, carbon or molybdenum can be preferably used.
　（調熱部材）
　調熱部材１１０は、坩堝１０１および発熱体１０２の間に配設される。調熱部材１１０は、ＧａＡｓ単結晶Ｃの成長方向に沿って第１調熱部材１１１、第２調熱部材１１２および第３調熱部材１１３の順に分割されている。調熱部材１１０は、円筒形状を有する。調熱部材１１０は、上方から平面視することにより現れる円と、発熱体１０２を上方から平面視することにより現れる円と、坩堝１０１を上方から平面視することにより現れる円との関係において同心円となることが好ましい。特に、調熱部材１１０は、坩堝１０１および発熱体１０２の間において坩堝１０１に近接させて配設されることが好ましい。成長中のＧａＡｓ単結晶ＣとＧａＡｓ融液Ｌとの界面Ｉの面内温度分布をより容易に調整することができるからである。たとえば坩堝１０１の外周面から調熱部材１１０（第１調熱部材１１１、第２調熱部材１１２および第３調熱部材１１３のいずれか）までの最短距離は、２～４ｃｍに設定されることが好ましい。 (Heat control member)
The heat control member 110 is arranged between the crucible 101 and the heating element 102. The heat control member 110 is divided in the order of a first heat control member 111, a second heat control member 112, and a third heat control member 113 along the growth direction of the GaAs single crystal C. The heat control member 110 has a cylindrical shape. The heat control member 110 is a concentric circle in the relationship between a circle that appears when viewed in plan from above, a circle that appears when viewed in plan from the heating element 102, and a circle that appears when viewed in plan from the crucible 101 from above. It is preferable that In particular, it is preferable that the heat control member 110 is disposed between the crucible 101 and the heating element 102 so as to be close to the crucible 101. This is because the in-plane temperature distribution of the interface I between the growing GaAs single crystal C and the GaAs melt L can be adjusted more easily. For example, the shortest distance from the outer peripheral surface of the crucible 101 to the heat control member 110 (any one of the first heat control member 111, the second heat control member 112, and the third heat control member 113) should be set to 2 to 4 cm. Is preferred.
　本開示では、発熱体１０２として上述のような線状発熱体を使用する場合がある。この場合、発熱体１０２間の電気的短絡を防止するため、所定の間隔で発熱体１０２を離間させて配置している。このため被加熱物（ＧａＡｓ単結晶ＣおよびＧａＡｓ融液Ｌなど）の円周方向には温度差（円周方向温度差）が発生しやすい。発熱体１０２自体が加熱によって熱膨張を起こすため、発熱体１０２間の距離も使用するごとに変化しやすく、円周方向温度差が大きくなる場合がある。この円周方向温度差は、ＧａＡｓ単結晶Ｃの転位密度を増加させる一因として知られる。一方、円周方向温度差の影響を緩和するため、たとえば坩堝１０１と発熱体１０２との間に汎用の炉芯管を配置する場合があるが、この場合、汎用の炉芯管が赤外線に対して不透明であるので、良好なＧａＡｓ単結晶Ｃを成長させるために必要な長手方向の温度プロファイルを生成すること、すなわちＧａＡｓ単結晶Ｃの成長方向に沿った所定の温度勾配を付した加熱操作が困難となる。このため本開示では、１０００℃を超える温度において坩堝１０１を加熱する場合、輻射熱が支配的となることを利用し、坩堝１０１近傍に赤外線の２～３μｍの波長に対する光線透過率が異なる部分を有する調熱部材１１０（第１調熱部材１１１、第２調熱部材１１２および第３調熱部材１１３）を設置した。これにより、発熱体１０２によって発生しやすい円周方向温度差の影響を軽減しつつ、ＧａＡｓ単結晶Ｃの成長方向に沿った所定の温度勾配を付した加熱操作（温度プロファイル）で成長中のＧａＡｓ単結晶ＣとＧａＡｓ融液Ｌとの界面Ｉを加熱し、もって界面Ｉの面内温度分布をより容易に調整することを実現した。 In the present disclosure, the linear heating element as described above may be used as the heating element 102. In this case, in order to prevent an electrical short circuit between the heat generating elements 102, the heat generating elements 102 are arranged at predetermined intervals. Therefore, a temperature difference (circumferential temperature difference) is likely to occur in the circumferential direction of the object to be heated (GaAs single crystal C, GaAs melt L, etc.). Since the heating element 102 itself causes thermal expansion due to heating, the distance between the heating elements 102 is likely to change with each use, and the circumferential temperature difference may increase. This temperature difference in the circumferential direction is known as one of the causes for increasing the dislocation density of the GaAs single crystal C. On the other hand, in order to reduce the influence of the temperature difference in the circumferential direction, for example, a general-purpose furnace core tube may be arranged between the crucible 101 and the heating element 102. In this case, the general-purpose furnace core tube is used for infrared rays. Since it is opaque, it is possible to generate a longitudinal temperature profile necessary for growing a good GaAs single crystal C, that is, a heating operation with a predetermined temperature gradient along the growth direction of the GaAs single crystal C. It will be difficult. Therefore, in the present disclosure, when the crucible 101 is heated at a temperature higher than 1000° C., the fact that radiant heat is dominant is utilized, and there is a portion in the vicinity of the crucible 101 having a different light transmittance with respect to a wavelength of 2 to 3 μm of infrared rays. The heat control member 110 (the first heat control member 111, the second heat control member 112, and the third heat control member 113) was installed. As a result, the influence of the temperature difference in the circumferential direction, which is likely to be generated by the heating element 102, is reduced, and the GaAs being grown by the heating operation (temperature profile) with a predetermined temperature gradient along the growth direction of the GaAs single crystal C. It has been realized that the interface I between the single crystal C and the GaAs melt L is heated so that the in-plane temperature distribution of the interface I can be adjusted more easily.
　第２調熱部材１１２は、波長２μｍ以上３μｍ以下の範囲の光線透過率が、第１調熱部材１１１の波長２μｍ以上３μｍ以下の範囲の光線透過率および第３調熱部材１１３の波長２μｍ以上３μｍ以下の範囲の光線透過率に対し２倍以上５倍以下である。第２調熱部材１１２の上記光線透過率が、第１調熱部材１１１の上記光線透過率および第３調熱部材１１３の上記光線透過率に対し２倍未満である場合、所望の温度プロファイルを生成することが困難となる。一方、第２調熱部材１１２の上記光線透過率が、第１調熱部材１１１の上記光線透過率および第３調熱部材１１３の上記光線透過率に対し５倍を超えるような調熱部材１１０（第１調熱部材１１１、第２調熱部材１１２および第３調熱部材１１３）は、これを調製し、準備することが現実的に困難である。 The second heat regulation member 112 has a light transmittance in a wavelength range of 2 μm or more and 3 μm or less, a light transmittance in a wavelength range of 2 μm or more and 3 μm or less of the first heat regulation member 111, and a wavelength of 2 μm or more in the third heat regulation member 113. It is 2 times or more and 5 times or less with respect to the light transmittance in the range of 3 μm or less. When the light transmittance of the second heat adjustment member 112 is less than twice the light transmittance of the first heat adjustment member 111 and the light transmittance of the third heat adjustment member 113, a desired temperature profile is obtained. Difficult to generate. On the other hand, the heat adjustment member 110 in which the light transmittance of the second heat adjustment member 112 exceeds five times the light transmittance of the first heat adjustment member 111 and the light transmittance of the third heat adjustment member 113. (First heat control member 111, second heat control member 112, and third heat control member 113) is practically difficult to prepare and prepare.
　第２調熱部材１１２は、波長２μｍ以上３μｍ以下の範囲の光線透過率が３０％以上であることが好ましい。第２調熱部材１１２は、上記光線透過率が４０％以上であることがより好ましい。上記光線透過率の上限は１００％である。さらに第１調熱部材１１１、第２調熱部材１１２および第３調熱部材１１３は、それぞれムライト、ジルコニア、スピネル、カーボン、アルミナおよびサファイアからなる群より選ばれるいずれかを含むことが好ましい。第１調熱部材１１１、第２調熱部材１１２および第３調熱部材１１３は、これらの物質から選ばれるいずれかからなることがより好ましい。特に、第２調熱部材１１２は、ムライト、アルミナおよびサファイアからなる群より選ばれるいずれかを含むことが好ましく、これらの物質からなる群より選ばれるいずれかからなることがより好ましい。これらの特徴により、本実施形態に係るＧａＡｓ基板の製造方法は、所望の温度プロファイルをより容易に生成し、かつ成長中のＧａＡｓ単結晶ＣとＧａＡｓ融液Ｌとの界面Ｉの円周方向温度差を軽減することができる。なお、波長２μｍ以上３μｍ以下の範囲の光線透過率を高くするには、上述した材料の高純度原料を使用したり、該原料の結晶粒径を制御したりすることが便宜である。さらに経済的な観点から、第１調熱部材１１１、第２調熱部材１１２および第３調熱部材１１３のうち、第２調熱部材１１２のみを上述した材料により構成しても好ましく、この場合であっても本開示の効果を奏することができる。 The second heat control member 112 preferably has a light transmittance of 30% or more in a wavelength range of 2 μm or more and 3 μm or less. The second heat regulation member 112 more preferably has the light transmittance of 40% or more. The upper limit of the light transmittance is 100%. Further, the first heat control member 111, the second heat control member 112, and the third heat control member 113 preferably each include any one selected from the group consisting of mullite, zirconia, spinel, carbon, alumina, and sapphire. More preferably, the first heat control member 111, the second heat control member 112, and the third heat control member 113 are made of any of these substances. In particular, the second heat regulation member 112 preferably contains any one selected from the group consisting of mullite, alumina and sapphire, and more preferably any one selected from the group consisting of these substances. Due to these features, the method for manufacturing a GaAs substrate according to the present embodiment more easily generates a desired temperature profile, and the circumferential temperature of the interface I between the growing GaAs single crystal C and the GaAs melt L. The difference can be reduced. In order to increase the light transmittance in the wavelength range of 2 μm or more and 3 μm or less, it is convenient to use a high-purity raw material of the above-mentioned material or to control the crystal grain size of the raw material. From an economical point of view, it is preferable that only the second heat control member 112 of the first heat control member 111, the second heat control member 112, and the third heat control member 113 is made of the above-mentioned material. Even in this case, the effect of the present disclosure can be achieved.
　第２調熱部材１１２は、ＧａＡｓ単結晶Ｃの成長方向と平行方向の長さが坩堝１０１の内径に対し４０％以上６０％以下であることが好ましい。第２調熱部材１１２は、ＧａＡｓ単結晶Ｃの成長方向と平行方向の長さが坩堝１０１の内径に対し４５％以上５５％以下であることがより好ましい。たとえば、１５０ｍｍのＧａＡｓ基板を製造する場合、第２調熱部材１１２におけるＧａＡｓ単結晶Ｃの成長方向と平行方向の長さは、６０～９０ｍｍとすることができる。これにより成長中のＧａＡｓ単結晶ＣとＧａＡｓ融液Ｌとの界面Ｉを、常に第２調熱部材１１２を通過した発熱体１０２からの熱によって加熱することができ、もって所望の温度プロファイルをより容易に生成し、かつ成長中のＧａＡｓ単結晶ＣとＧａＡｓ融液Ｌとの界面Ｉにおいて円周方向温度差を軽減することができる。 The second heat regulation member 112 preferably has a length in the direction parallel to the growth direction of the GaAs single crystal C that is 40% or more and 60% or less of the inner diameter of the crucible 101. More preferably, the length of the second heat control member 112 in the direction parallel to the growth direction of the GaAs single crystal C is 45% or more and 55% or less with respect to the inner diameter of the crucible 101. For example, when manufacturing a 150 mm GaAs substrate, the length of the second heat control member 112 in the direction parallel to the growth direction of the GaAs single crystal C can be set to 60 to 90 mm. As a result, the interface I between the growing GaAs single crystal C and the GaAs melt L can be always heated by the heat from the heating element 102 that has passed through the second heat control member 112, and thus a desired temperature profile can be obtained. It is possible to easily reduce the temperature difference in the circumferential direction at the interface I between the GaAs single crystal C that is generated and is growing and the GaAs melt L.
　さらに第１調熱部材１１１および第３調熱部材１１３は、表面粗さＲａが２μｍ以上３μｍ以下であることが好ましい。第１調熱部材１１１および第３調熱部材１１３は、表面粗さＲａが２．５μｍ以上３μｍ以下であることがより好ましい。これにより、坩堝１０１中のＧａＡｓ単結晶ＣおよびＧａＡｓ融液Ｌを加熱する熱に対し、所望の温度プロファイルをより容易に生成し、かつ成長中のＧａＡｓ単結晶ＣとＧａＡｓ融液Ｌとの界面Ｉにおいて円周方向温度差を軽減することができる。第１調熱部材１１１および第３調熱部材１１３の表面粗さＲａが３μｍを超える場合、光線透過率の低下によって上記温度勾配を適切に制御することが困難となる傾向がある。第１調熱部材１１１および第３調熱部材１１３の表面粗さＲａを２μｍ未満としても、２μｍ以上３μｍ以下の場合と効果において有利ではないので、加工コストの観点から不経済となる傾向がある。 Further, the surface roughness Ra of the first heat control member 111 and the third heat control member 113 is preferably 2 μm or more and 3 μm or less. The surface roughness Ra of the first heat control member 111 and the third heat control member 113 is more preferably 2.5 μm or more and 3 μm or less. As a result, a desired temperature profile can be generated more easily with respect to the heat of heating the GaAs single crystal C and the GaAs melt L in the crucible 101, and the interface between the growing GaAs single crystal C and the GaAs melt L is increased. In I, the temperature difference in the circumferential direction can be reduced. When the surface roughness Ra of the 1st heat regulation member 111 and the 3rd heat regulation member 113 exceeds 3 micrometers, there exists a tendency for it to become difficult to control the said temperature gradient appropriately by the fall of light transmittance. Even if the surface roughness Ra of the first heat control member 111 and the third heat control member 113 is less than 2 μm, it is not advantageous in the effect in the case of 2 μm or more and 3 μm or less, so that it tends to be uneconomical from the viewpoint of processing cost. ..
　ここで第２調熱部材１１２は、その厚みが第１調熱部材１１１および第３調熱部材１１３と異なることが好ましい。たとえば図２および図４に示す単結晶成長装置では、第２調熱部材１１２は、その厚みが第１調熱部材１１１および第３調熱部材１１３と異なる。さらに第１調熱部材１１１、第２調熱部材１１２および第３調熱部材１１３は、その材質が同一であることが好ましい。たとえば図２に示す単結晶成長装置では、第１調熱部材１１１、第２調熱部材１１２および第３調熱部材１１３は、その材質が同一である。この場合において第１調熱部材１１１、第２調熱部材１１２および第３調熱部材１１３は、上述のとおりムライト、ジルコニア、スピネル、カーボン、アルミナおよびサファイアからなる群より選ばれるいずれかを含むことが好ましく、これらの物質からなる群より選ばれるいずれかからなることがより好ましい。 Here, it is preferable that the thickness of the second heat regulation member 112 is different from that of the first heat regulation member 111 and the third heat regulation member 113. For example, in the single crystal growth apparatus shown in FIGS. 2 and 4, the second heat regulation member 112 is different in thickness from the first heat regulation member 111 and the third heat regulation member 113. Furthermore, it is preferable that the first heat control member 111, the second heat control member 112, and the third heat control member 113 are made of the same material. For example, in the single crystal growth apparatus shown in FIG. 2, the first heat control member 111, the second heat control member 112, and the third heat control member 113 are made of the same material. In this case, the first heat control member 111, the second heat control member 112, and the third heat control member 113 include any one selected from the group consisting of mullite, zirconia, spinel, carbon, alumina, and sapphire as described above. Are preferred, and it is more preferred that they are composed of any one selected from the group consisting of these substances.
　第２調熱部材１１２の厚みが第１調熱部材１１１および第３調熱部材１１３の厚みと異なる場合、第２調熱部材１１２は、その厚みが第１調熱部材１１１および第３調熱部材１１３に対し０．２倍以上０．５倍以下であることが好ましい。より具体的には、第２調熱部材１１２の厚みが４～６ｍｍであって、第１調熱部材１１１および第３調熱部材１１３の厚みが８～２０ｍｍであることが好ましい。これにより、所望の温度プロファイルをより容易に生成し、かつ成長中のＧａＡｓ単結晶ＣとＧａＡｓ融液Ｌとの界面Ｉにおいて円周方向温度差を軽減することができる。 When the thickness of the 2nd heat regulation member 112 differs from the thickness of the 1st heat regulation member 111 and the 3rd heat regulation member 113, the 2nd heat regulation member 112 has the thickness of the 1st heat regulation member 111 and the 3rd heat regulation member. It is preferably 0.2 times or more and 0.5 times or less that of the member 113. More specifically, it is preferable that the second heat control member 112 has a thickness of 4 to 6 mm, and the first heat control member 111 and the third heat control member 113 have a thickness of 8 to 20 mm. This makes it possible to more easily generate a desired temperature profile and reduce the circumferential temperature difference at the interface I between the growing GaAs single crystal C and the GaAs melt L.
　ただし、図２に示す単結晶成長装置のように、第２調熱部材１１２と第１調熱部材１１１および第３調熱部材１１３の材質とが同一である場合、第２調熱部材１１２の厚みが第１調熱部材１１１および第３調熱部材１１３の厚みに対し０．５倍を超えると、所望の温度プロファイルを容易に生成することが困難となる傾向がある。一方、第２調熱部材１１２の厚みが第１調熱部材１１１および第３調熱部材１１３の厚みに対し０．２倍未満となる調熱部材１１０（第１調熱部材１１１、第２調熱部材１１２および第３調熱部材１１３）は、これを調製し、準備することが現実的に困難となる傾向がある。 However, as in the single crystal growth apparatus shown in FIG. 2, when the materials of the second heat regulation member 112 and the first heat regulation member 111 and the third heat regulation member 113 are the same, If the thickness exceeds 0.5 times the thickness of the first heat control member 111 and the third heat control member 113, it tends to be difficult to easily generate a desired temperature profile. On the other hand, the thickness of the second heat control member 112 is less than 0.2 times the thickness of the first heat control member 111 and the third heat control member 113 (the first heat control member 111, the second heat control member 111). The heat member 112 and the third heat adjusting member 113) tend to be practically difficult to prepare and prepare.
　第２調熱部材１１２と、第１調熱部材１１１および第３調熱部材１１３とは、その材質が異なることも好ましい。たとえば図４に示す単結晶成長装置では、第２調熱部材１１２と、第１調熱部材１１１および第３調熱部材１１３とは、その材質が異なる。さらに上述のように、図４に示す単結晶成長装置は、第２調熱部材１１２と、第１調熱部材１１１および第３調熱部材１１３とは、その厚みも異なる。 It is also preferable that the second heat regulation member 112 and the first heat regulation member 111 and the third heat regulation member 113 are made of different materials. For example, in the single crystal growth apparatus shown in FIG. 4, the second heat control member 112 and the first heat control member 111 and the third heat control member 113 are made of different materials. Further, as described above, in the single crystal growth apparatus shown in FIG. 4, the second heat regulation member 112 and the first heat regulation member 111 and the third heat regulation member 113 also have different thicknesses.
　第２調熱部材１１２の材質と、第１調熱部材１１１および第３調熱部材１１３の材質とが異なる場合、第２調熱部材１１２は、ムライト、アルミナおよびサファイアからなる群より選ばれるいずれかを含むことが好ましく、これらの物質からなる群より選ばれるいずれかからなることがより好ましい。これにより第２調熱部材１１２において、波長２μｍ以上３μｍ以下の範囲の光線透過率を容易に３０％以上とすることが可能となり、もって所望の温度プロファイルをより容易に生成することができる。図４に示す単結晶成長装置において、第２調熱部材１１２の材質は、ムライト、アルミナおよびサファイアからなる群より選ばれるいずれかからなる。 When the material of the second heat control member 112 is different from the material of the first heat control member 111 and the third heat control member 113, the second heat control member 112 is selected from the group consisting of mullite, alumina, and sapphire. It is preferable to include or, more preferably, any one selected from the group consisting of these substances. Thereby, in the second heat control member 112, the light transmittance in the wavelength range of 2 μm or more and 3 μm or less can be easily set to 30% or more, and thus a desired temperature profile can be generated more easily. In the single crystal growth apparatus shown in FIG. 4, the material of the second heat control member 112 is any material selected from the group consisting of mullite, alumina and sapphire.
　ここで図３に示す単結晶成長装置は、第２調熱部材１１２の厚みが、第１調熱部材１１１および第３調熱部材１１３の厚みと同一である一方、第２調熱部材１１２の材質が、第１調熱部材１１１および第３調熱部材１１３の材質と異なる。さらに第２調熱部材１１２は、ムライト、アルミナおよびサファイアからなる群より選ばれるいずれかからなる。この場合であっても、第２調熱部材１１２の波長２μｍ以上３μｍ以下の範囲の光線透過率を容易に３０％以上とすることができ、もって所望の温度プロファイルをより容易に生成することができる。 Here, in the single crystal growth apparatus shown in FIG. 3, the thickness of the second heat control member 112 is the same as the thickness of the first heat control member 111 and the third heat control member 113, while the second heat control member 112 has the same thickness. The material is different from that of the first heat control member 111 and the third heat control member 113. Further, the second heat control member 112 is made of any one selected from the group consisting of mullite, alumina and sapphire. Even in this case, the light transmittance of the second heat control member 112 in the wavelength range of 2 μm or more and 3 μm or less can be easily set to 30% or more, and thus a desired temperature profile can be generated more easily. it can.
　＜第２工程＞
　第２工程は、上記単結晶成長装置において、調熱部材１１０を通過した発熱体１０２からの熱でＧａＡｓ種結晶ＳおよびＧａＡｓ融液Ｌを加熱することにより、ＧａＡｓ種結晶ＳからＧａＡｓ単結晶Ｃを成長させる工程である。第２工程において、成長中のＧａＡｓ単結晶ＣとＧａＡｓ融液Ｌとの界面Ｉは、第２調熱部材１１２を通過した発熱体１０２からの熱で加熱される。界面Ｉは、その形状がＧａＡｓ単結晶Ｃの成長方向に凸な弧状であることが好ましい。第２工程では、特に制限されるべきではないが、ＶＢ法に基づいてＧａＡｓ種結晶ＳからＧａＡｓ単結晶Ｃを成長させることが好ましい。 <Second step>
In the second step, in the single crystal growth apparatus, the GaAs seed crystal S and the GaAs melt L are heated by the heat from the heating element 102 that has passed through the heat control member 110, so that the GaAs seed crystal S to the GaAs single crystal C are heated. Is a step of growing. In the second step, the interface I between the growing GaAs single crystal C and the GaAs melt L is heated by the heat from the heating element 102 that has passed through the second heat control member 112. The interface I preferably has an arc shape whose shape is convex in the growth direction of the GaAs single crystal C. In the second step, although not particularly limited, it is preferable to grow the GaAs single crystal C from the GaAs seed crystal S based on the VB method.
　本実施形態に係るＧａＡｓ基板の製造方法では、第１工程において、第１調熱部材１１１、第２調熱部材１１２および第３調熱部材１１３の材質、厚みおよび波長２μｍ以上３μｍ以下の範囲の光線透過率、ならびに第２調熱部材１１２のＧａＡｓ単結晶Ｃの成長方向と平行方向の長さ、第１調熱部材１１１および第３調熱部材の表面粗さＲａなどについて、上述した特徴を有する調熱部材１１０が準備される。これにより第２工程において、ＧａＡｓ単結晶Ｃの成長方向に沿って所定の温度勾配を付した加熱操作でＧａＡｓ種結晶ＳおよびＧａＡｓ融液Ｌを加熱することができる。すなわち第２工程では、上述の調熱部材１１０によって所望の温度プロファイルをより容易に生成することができ、かつ成長中のＧａＡｓ単結晶ＣとＧａＡｓ融液Ｌとの界面Ｉにおいて円周方向温度差を軽減することができる。これにより成長中のＧａＡｓ単結晶ＣとＧａＡｓ融液Ｌとの界面の面内温度分布を均一とすることができる。具体的には、成長中のＧａＡｓ単結晶ＣとＧａＡｓ融液Ｌとの界面の面内温度分布を、その最大温度と最低温度との差を２℃以内とした状態で、ＧａＡｓ種結晶ＳからＧａＡｓ単結晶Ｃを成長させることができる。 In the method of manufacturing a GaAs substrate according to the present embodiment, in the first step, the material, thickness, and wavelength of the first heat control member 111, the second heat control member 112, and the third heat control member 113 are in the range of 2 μm to 3 μm. Regarding the light transmittance, the length of the second heat control member 112 in the direction parallel to the growth direction of the GaAs single crystal C, the surface roughness Ra of the first heat control member 111 and the third heat control member, and the like, The heat regulation member 110 which has is prepared. Thereby, in the second step, the GaAs seed crystal S and the GaAs melt L can be heated by a heating operation with a predetermined temperature gradient along the growth direction of the GaAs single crystal C. That is, in the second step, a desired temperature profile can be more easily generated by the heat control member 110, and the temperature difference in the circumferential direction at the interface I between the growing GaAs single crystal C and the GaAs melt L is increased. Can be reduced. As a result, the in-plane temperature distribution at the interface between the growing GaAs single crystal C and the GaAs melt L can be made uniform. Specifically, from the GaAs seed crystal S, the in-plane temperature distribution at the interface between the growing GaAs single crystal C and the GaAs melt L is set within a difference of 2° C. between the maximum temperature and the minimum temperature. GaAs single crystal C can be grown.
　さらに第２工程では、ＧａＡｓ単結晶Ｃの成長方向に沿った温度勾配として、成長中のＧａＡｓ単結晶ＣとＧａＡｓ融液Ｌとの界面Ｉを、第２調熱部材１１２を通過した発熱体１０２からの熱で１２３６～１２３８℃に加熱することが好ましい。坩堝１０１の底部に収容されたＧａＡｓ種結晶Ｓに対しては、発熱体１０２からの熱で１２１５～１２４５℃に加熱することが好ましい。ＧａＡｓ融液ＬのＧａＡｓ単結晶Ｃとの界面Ｉとは反対側となる表面部に対しては、発熱体１０２からの熱で１２４０～１２６０℃に加熱することが好ましい。このような温度プロファイルを用い、ＧａＡｓ種結晶Ｓ、成長中のＧａＡｓ単結晶ＣおよびＧａＡｓ融液Ｌなどを加熱する。これにより、界面Ｉの形状をＧａＡｓ単結晶Ｃの成長方向に凸な弧状、換言すればＧａＡｓ単結晶Ｃの成長方向に凸な放物面とし、もって成長中のＧａＡｓ単結晶ＣとＧａＡｓ融液Ｌとの界面の面内温度分布をより均一にすることができる。 Further, in the second step, as a temperature gradient along the growth direction of the GaAs single crystal C, the heating element 102 that has passed through the second heat regulation member 112 at the interface I between the growing GaAs single crystal C and the GaAs melt L. It is preferable to heat to 1236 to 1238° C. with heat from The GaAs seed crystal S housed in the bottom of the crucible 101 is preferably heated to 1215 to 1245° C. by the heat from the heating element 102. The surface of the GaAs melt L opposite to the interface I with the GaAs single crystal C is preferably heated to 1240 to 1260° C. by the heat from the heating element 102. Using such a temperature profile, the GaAs seed crystal S, the growing GaAs single crystal C, the GaAs melt L, etc. are heated. As a result, the shape of the interface I is an arc shape convex in the growth direction of the GaAs single crystal C, in other words, a parabolic surface convex in the growth direction of the GaAs single crystal C, so that the GaAs single crystal C and the GaAs melt which are growing The in-plane temperature distribution at the interface with L can be made more uniform.
　＜第３工程＞
　第３工程は、ＧａＡｓ単結晶Ｃを、その成長方向に対して垂直に切出すことにより、主面の面方位が（１００）面であるＧａＡｓ基板を得る工程である。 <Third step>
The third step is a step of cutting the GaAs single crystal C perpendicularly to the growth direction thereof to obtain a GaAs substrate having a main surface whose plane orientation is the (100) plane.
　第３工程では、従来公知の方法を用いることにより、ＧａＡｓ単結晶Ｃを切出すことができる。その後、必要に応じてミラー加工などを行うことによりＧａＡｓ基板を得ることができる。この場合において、主面の面方位が（１００）面であるＧａＡｓ基板を得るためには、坩堝１０１の底部に収容したＧａＡｓ種結晶ＳのＧａＡｓ融液Ｌとの接触面の面方位を（１００）面とすることが好ましい。これにより、第２工程において成長したＧａＡｓ単結晶Ｃを、その成長方向（すなわち［１００］方向）に対して垂直に切出すことにより、主面の面方位が（１００）面であるＧａＡｓ基板を容易に得ることができる。 In the third step, the GaAs single crystal C can be cut out by using a conventionally known method. After that, a GaAs substrate can be obtained by performing mirror processing or the like if necessary. In this case, in order to obtain a GaAs substrate whose main surface has a (100) surface orientation, the surface orientation of the contact surface of the GaAs seed crystal S housed in the bottom of the crucible 101 with the GaAs melt L is (100). ) Surface is preferable. As a result, the GaAs single crystal C grown in the second step is cut out perpendicularly to its growth direction (that is, the [100] direction) to obtain a GaAs substrate whose principal plane is the (100) plane. Can be easily obtained.
　＜作用＞
　上述の製造方法により得たＧａＡｓ基板は、その主面において転位密度を測定した場合、任意の結晶方位において転位密度のバラツキが抑えられ、もって任意の結晶方位において転位密度が均一であると判断され得る。したがって、本実施形態に係るＧａＡｓ基板の製造方法により、主面のすべての結晶方位で転位密度が均一となるＧａＡｓ基板を製造することができる。 <Action>
When the dislocation density is measured on the main surface of the GaAs substrate obtained by the above-described manufacturing method, the dislocation density variation is suppressed in any crystal orientation, and it is determined that the dislocation density is uniform in any crystal orientation. obtain. Therefore, the GaAs substrate manufacturing method according to the present embodiment makes it possible to manufacture a GaAs substrate having a uniform dislocation density in all crystal orientations of the main surface.
　以下、実施例を挙げて本開示をより詳細に説明するが、本発明はこれらに限定されるものではない。 Hereinafter, the present disclosure will be described in more detail with reference to Examples, but the present invention is not limited thereto.
　≪半絶縁性ＧａＡｓ基板の製造≫
　＜実施例１：面１および面２＞
　（第１工程）
　図２に示す単結晶成長装置を準備した。この単結晶成長装置は、上述した特徴を有する坩堝１０１、発熱体１０２および調熱部材１１０を備える。具体的には、調熱部材１１０（第１調熱部材１１１、第２調熱部材１１２および第３調熱部材１１３）の材質としてムライトを用い、第２調熱部材１１２の厚みを４ｍｍとし、第１調熱部材１１１および第３調熱部材１１３の厚みを８ｍｍとした。第２調熱部材１１２の波長２μｍ以上３μｍ以下の範囲の光線透過率は、４０％であり、第１調熱部材１１１および第３調熱部材１１３の上記光線透過率の２倍とした。第１調熱部材１１１および第３調熱部材１１３の表面粗さＲａを２．５μｍとした。第２調熱部材１１２におけるＧａＡｓ単結晶Ｃの成長方向と平行方向の長さは、坩堝１０１の内径（１５０ｍｍ）に対する５０％の長さである７５ｍｍとした。 << Manufacture of semi-insulating GaAs substrate >>
<Example 1: Surface 1 and surface 2>
(First step)
The single crystal growth apparatus shown in FIG. 2 was prepared. This single crystal growth apparatus includes the crucible 101, the heating element 102, and the heat control member 110 having the above-described characteristics. Specifically, mullite is used as the material of the heat control member 110 (the first heat control member 111, the second heat control member 112, and the third heat control member 113), and the thickness of the second heat control member 112 is 4 mm, The thickness of the 1st heat regulation member 111 and the 3rd heat regulation member 113 was 8 mm. The light transmittance of the second heat control member 112 in the wavelength range of 2 μm or more and 3 μm or less is 40%, which is twice the light transmittance of the first heat control member 111 and the third heat control member 113. The surface roughness Ra of the first heat control member 111 and the third heat control member 113 was set to 2.5 μm. The length of the second heat regulation member 112 in the direction parallel to the growth direction of the GaAs single crystal C was 75 mm, which was 50% of the inner diameter (150 mm) of the crucible 101.
　さらに、カーボンドープされたＧａＡｓの単結晶からなるＧａＡｓ種結晶ＳをＶＢ法を用いて作製し、これを坩堝１０１の底部に、上記融液Ｌとの接触面の面方位が（１００）面となるようにして収容した。このＧａＡｓ種結晶Ｓ上には上述した方法により合成した固体のＧａＡｓを投入し、これをＧａＡｓの融点以上の温度で加熱することによりＧａＡｓ融液Ｌとした。 Further, a GaAs seed crystal S made of a carbon-doped GaAs single crystal was produced by the VB method, and this was formed on the bottom of the crucible 101 so that the plane of the contact surface with the melt L was the (100) plane. It was housed as follows. Onto this GaAs seed crystal S, solid GaAs synthesized by the above-mentioned method was put, and this was heated at a temperature higher than the melting point of GaAs to obtain a GaAs melt L.
　（第２工程）
　上述した単結晶成長装置を用いることにより、ＧａＡｓ種結晶Ｓから直径１５０ｍｍのＧａＡｓ単結晶Ｃを成長させた。このとき、成長中のＧａＡｓ単結晶ＣとＧａＡｓ融液Ｌとの界面Ｉは、その形状がＧａＡｓ単結晶Ｃの成長方向に凸な弧状であった。 (Second step)
The GaAs single crystal C having a diameter of 150 mm was grown from the GaAs seed crystal S by using the above-described single crystal growth apparatus. At this time, the interface I between the growing GaAs single crystal C and the GaAs melt L had an arcuate shape which was convex in the growth direction of the GaAs single crystal C.
　（第３工程）
　上記ＧａＡｓ単結晶Ｃを、その成長方向に対して垂直に切出すとともに、ミラー加工を施すことによって、主面の面方位が（１００）面である実施例１の半絶縁性ＧａＡｓ基板（厚み１ｍｍ）を得た。実施例１の半絶縁性ＧａＡｓ基板の主面において、ＧａＡｓ種結晶Ｓ側を面１とし、面１とは反対側を面２とした。 (Third step)
The GaAs single crystal C is cut out perpendicularly to its growth direction and subjected to mirror processing to obtain a semi-insulating GaAs substrate (thickness: 1 mm) of the main surface whose plane orientation is the (100) plane. ) Got. In the main surface of the semi-insulating GaAs substrate of Example 1, the GaAs seed crystal S side was the surface 1 and the opposite side to the surface 1 was the surface 2.
　＜実施例２：面３および面４＞
　（第１工程）
　図３に示す単結晶成長装置を準備した。この単結晶成長装置は、上述した特徴を有する坩堝１０１、発熱体１０２および調熱部材１１０を備える。具体的には、調熱部材１１０に関し、第１調熱部材１１１および第３調熱部材１１３の材質としてムライトを用い、第２調熱部材１１２の材質としてアルミナを用いた。第１調熱部材１１１、第２調熱部材１１２および第３調熱部材１１３の厚みは同一であり、８ｍｍとした。第２調熱部材１１２の波長２μｍ以上３μｍ以下の範囲の光線透過率は、６０％であり、第１調熱部材１１１および第３調熱部材１１３の上記光線透過率の３倍とした。第１調熱部材１１１および第３調熱部材１１３の表面粗さＲａを２．５μｍとした。第２調熱部材１１２におけるＧａＡｓ単結晶Ｃの成長方向と平行方向の長さは、坩堝１０１の内径（１５０ｍｍ）に対する５０％の長さである７５ｍｍとした。 <Example 2: Surface 3 and surface 4>
(First step)
The single crystal growth apparatus shown in FIG. 3 was prepared. This single crystal growth apparatus includes the crucible 101, the heating element 102, and the heat control member 110 having the above-described characteristics. Specifically, regarding the heat control member 110, mullite was used as the material of the first heat control member 111 and the third heat control member 113, and alumina was used as the material of the second heat control member 112. The first heat control member 111, the second heat control member 112, and the third heat control member 113 have the same thickness and are set to 8 mm. The light transmittance of the second heat control member 112 in the wavelength range of 2 μm or more and 3 μm or less is 60%, which is three times the light transmittance of the first heat control member 111 and the third heat control member 113. The surface roughness Ra of the first heat control member 111 and the third heat control member 113 was set to 2.5 μm. The length of the second heat regulation member 112 in the direction parallel to the growth direction of the GaAs single crystal C was 75 mm, which was 50% of the inner diameter (150 mm) of the crucible 101.
　ＧａＡｓ種結晶ＳおよびＧａＡｓ融液Ｌについては、実施例１の半絶縁性ＧａＡｓ基板の製造方法における第１工程で作製したＧａＡｓ種結晶ＳおよびＧａＡｓ融液Ｌと同じものを用いた。 As the GaAs seed crystal S and the GaAs melt L, the same ones as the GaAs seed crystal S and the GaAs melt L produced in the first step in the method of manufacturing the semi-insulating GaAs substrate of Example 1 were used.
　（第２工程および第３工程）
　実施例１の半絶縁性ＧａＡｓ基板の製造方法における第２工程および第３工程と同じ工程を行なうことにより実施例２の半絶縁性ＧａＡｓ基板（厚み１ｍｍ）を得た。実施例１の半絶縁性ＧａＡｓ基板の主面において、ＧａＡｓ種結晶Ｓ側を面３とし、面３とは反対側を面４とした。 (Second step and third step)
A semi-insulating GaAs substrate (thickness 1 mm) of Example 2 was obtained by performing the same steps as the second step and the third step in the method of manufacturing a semi-insulating GaAs substrate of Example 1. In the main surface of the semi-insulating GaAs substrate of Example 1, the GaAs seed crystal S side was the surface 3 and the side opposite to the surface 3 was the surface 4.
　＜実施例３：面５および面６＞
　（第１工程）
　図４に示す単結晶成長装置を準備した。この単結晶成長装置は、上述した特徴を有する坩堝１０１、発熱体１０２および調熱部材１１０を備える。具体的には、調熱部材１１０に関し、第１調熱部材１１１および第３調熱部材１１３の材質としてムライトを用い、第２調熱部材１１２の材質としてアルミナを用いた。さらに第２調熱部材１１２の厚みを４ｍｍとし、第１調熱部材１１１および第３調熱部材１１３の厚みを８ｍｍとした。第２調熱部材１１２の波長２μｍ以上３μｍ以下の範囲の光線透過率は、８０％であり、第１調熱部材１１１および第３調熱部材１１３の上記光線透過率の４倍とした。第１調熱部材１１１および第３調熱部材１１３の表面粗さＲａを２．５μｍとした。第２調熱部材１１２におけるＧａＡｓ単結晶Ｃの成長方向と平行方向の長さは、坩堝１０１の内径（１５０ｍｍ）に対する５０％の長さである７５ｍｍとした。 <Example 3: Surface 5 and surface 6>
(First step)
The single crystal growth apparatus shown in FIG. 4 was prepared. This single crystal growth apparatus includes the crucible 101, the heating element 102, and the heat control member 110 having the above-described characteristics. Specifically, regarding the heat control member 110, mullite was used as the material of the first heat control member 111 and the third heat control member 113, and alumina was used as the material of the second heat control member 112. Furthermore, the thickness of the 2nd heat regulation member 112 was 4 mm, and the thickness of the 1st heat regulation member 111 and the 3rd heat regulation member 113 was 8 mm. The light transmittance of the second heat control member 112 in the wavelength range of 2 μm or more and 3 μm or less is 80%, which is four times the light transmittance of the first heat control member 111 and the third heat control member 113. The surface roughness Ra of the first heat control member 111 and the third heat control member 113 was set to 2.5 μm. The length of the second heat regulation member 112 in the direction parallel to the growth direction of the GaAs single crystal C was 75 mm, which was 50% of the inner diameter (150 mm) of the crucible 101.
　ＧａＡｓ種結晶ＳおよびＧａＡｓ融液Ｌについては、実施例１の半絶縁性ＧａＡｓ基板の製造方法における第１工程で作製したＧａＡｓ種結晶ＳおよびＧａＡｓ融液Ｌと同じものを用いた。 As the GaAs seed crystal S and the GaAs melt L, the same ones as the GaAs seed crystal S and the GaAs melt L produced in the first step in the method of manufacturing the semi-insulating GaAs substrate of Example 1 were used.
　（第２工程および第３工程）
　実施例１の半絶縁性ＧａＡｓ基板の製造方法における第２工程および第３工程と同じ工程を行なうことにより実施例３の半絶縁性ＧａＡｓ基板（厚み１ｍｍ）を得た。実施例３の半絶縁性ＧａＡｓ基板の主面において、ＧａＡｓ種結晶Ｓ側を面５とし、面５とは反対側を面６とした。 (Second step and third step)
A semi-insulating GaAs substrate (thickness 1 mm) of Example 3 was obtained by performing the same steps as the second step and the third step in the method of manufacturing the semi-insulating GaAs substrate of Example 1. In the main surface of the semi-insulating GaAs substrate of Example 3, the GaAs seed crystal S side was the surface 5, and the side opposite to the surface 5 was the surface 6.
　＜実施例４：面７および面８＞
　（第１工程）
　内径が２０２ｍｍである坩堝１０１を用い、これに伴って調熱部材１１０および発熱体１０２の内径を調整したこと以外は、図４に示す単結晶成長装置と同じ構成とした単結晶成長装置を準備した。第２調熱部材１１２におけるＧａＡｓ単結晶Ｃの成長方向と平行方向の長さは、坩堝１０１の内径（２０２ｍｍ）に対する約４０％の長さである８２ｍｍとした。 <Example 4: Surface 7 and surface 8>
(First step)
A single crystal growth apparatus having the same configuration as the single crystal growth apparatus shown in FIG. 4 was prepared, except that the crucible 101 having an inner diameter of 202 mm was used and the inner diameters of the heat control member 110 and the heating element 102 were adjusted accordingly. did. The length of the second heat regulation member 112 in the direction parallel to the growth direction of the GaAs single crystal C was 82 mm, which was about 40% of the inner diameter (202 mm) of the crucible 101.
　ＧａＡｓ種結晶ＳおよびＧａＡｓ融液Ｌについては、実施例１の半絶縁性ＧａＡｓ基板の製造方法における第１工程で作製したＧａＡｓ種結晶ＳおよびＧａＡｓ融液Ｌと同じものを用いた。 As the GaAs seed crystal S and the GaAs melt L, the same ones as the GaAs seed crystal S and the GaAs melt L produced in the first step in the method of manufacturing the semi-insulating GaAs substrate of Example 1 were used.
　（第２工程および第３工程）
　実施例１の半絶縁性ＧａＡｓ基板の製造方法における第２工程および第３工程と同じ工程を行なうことにより実施例４の半絶縁性ＧａＡｓ基板（厚み１ｍｍ）を得た。実施例４の半絶縁性ＧａＡｓ基板の主面において、種結晶Ｓ側を面７とし、面７とは反対側を面８とした。 (Second step and third step)
A semi-insulating GaAs substrate (thickness: 1 mm) of Example 4 was obtained by performing the same steps as the second step and the third step in the method of manufacturing the semi-insulating GaAs substrate of Example 1. In the main surface of the semi-insulating GaAs substrate of Example 4, the seed crystal S side was the surface 7, and the side opposite to the surface 7 was the surface 8.
　＜比較例１：面Ａおよび面Ｂ＞
　（第１工程～第３工程）
　図２に示す単結晶成長装置を、調熱部材１１０を備えることなく準備したこと以外は、実施例１の半絶縁性ＧａＡｓ基板の製造方法における第１工程、第２工程および第３工程と同じ工程を行なうことにより比較例１の半絶縁性ＧａＡｓ基板（厚み１ｍｍ）を得た。比較例１の半絶縁性ＧａＡｓ基板の主面において、ＧａＡｓ種結晶Ｓ側を面Ａとし、面Ａとは反対側を面Ｂとした。 <Comparative Example 1: Surface A and surface B>
(First step to third step)
2 is the same as the first step, the second step and the third step in the method for manufacturing a semi-insulating GaAs substrate of Example 1 except that the single crystal growth apparatus shown in FIG. By performing the steps, a semi-insulating GaAs substrate (thickness 1 mm) of Comparative Example 1 was obtained. In the main surface of the semi-insulating GaAs substrate of Comparative Example 1, the GaAs seed crystal S side was set as the surface A and the side opposite to the surface A was set as the surface B.
　≪転位密度の測定≫
　実施例１～実施例４および比較例１の各面に対し、上述した測定方法により第１測定点１１、第２測定点１２、第３測定点１３、第４測定点１４および第５測定点１５での転位密度を上述の方法を用いることにより測定した。その測定結果を表１に示す。表１中、各測定点における転位密度の測定値は、単位を「ｃｍ-2」に換算して示した。 <<Measurement of dislocation density>>
For each surface of Examples 1 to 4 and Comparative Example 1, the first measurement point 11, the second measurement point 12, the third measurement point 13, the fourth measurement point 14 and the fifth measurement point were measured by the above-described measurement method. The dislocation density at 15 was measured by using the method described above. The measurement results are shown in Table 1. In Table 1, the measured value of the dislocation density at each measuring point is shown by converting the unit into “cm −2 ”.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
　≪考察≫
　表１によれば、実施例１～実施例４の各面（面１～面８）において第１測定点１１、第２測定点１２および第３測定点１３での転位密度の測定値の差は、２０００ｃｍ-2以内であり、第２測定点１２および第４測定点１４での転位密度の測定値の差は、１７００ｃｍ-2以内であり、第１測定点１１、第４測定点１４および第５測定点１５での転位密度の測定値の差は、３８００ｃｍ-2以内であった。面１～面８において第３測定点１３および第５測定点１５での転位密度の測定値は、いずれも１００００ｃｍ-2以下であった。 ≪Consideration≫
According to Table 1, the difference in the measured values of the dislocation density at the first measurement point 11, the second measurement point 12 and the third measurement point 13 on each surface (surface 1 to surface 8) of Example 1 to Example 4 Is within 2000 cm -2 , the difference between the measured dislocation densities at the second measurement point 12 and the fourth measurement point 14 is within 1700 cm -2 , and the first measurement point 11, the fourth measurement point 14 and The difference between the measured dislocation densities at the fifth measurement point 15 was within 3800 cm -2 . The measured dislocation densities at the third measurement point 13 and the fifth measurement point 15 on the surfaces 1 to 8 were all 10000 cm -2 or less.
　一方、比較例１の面Ａおよび面Ｂでは、第１測定点１１、第２測定点１２および第３測定点１３での転位密度の測定値の差は２０００ｃｍ-2を超え、第１測定点１１、第４測定点１４および第５測定点１５での転位密度の測定値の差も３８００ｃｍ-2を超えた。面Ａおよび面Ｂにおいて第３測定点１３での転位密度の測定値は、いずれも１００００ｃｍ-2を超えた。面Ｂの第５測定点１５での転位密度の測定値は、１００００ｃｍ-2を超えた。 On the other hand, in the surface A and the surface B of Comparative Example 1, the difference in the dislocation density measured values at the first measurement point 11, the second measurement point 12 and the third measurement point 13 exceeds 2000 cm −2 , and the first measurement point The difference between the measured dislocation densities at 11, the fourth measurement point 14 and the fifth measurement point 15 also exceeded 3800 cm -2 . The measured values of the dislocation density at the third measurement point 13 on the surface A and the surface B both exceeded 10000 cm -2 . The measured dislocation density at the fifth measurement point 15 on the surface B exceeded 10000 cm -2 .
　以上から、実施例１～実施例４の半絶縁性ＧａＡｓ基板は、すべての結晶方位において転位密度が均一であると判断することができる。 From the above, it can be judged that the semi-insulating GaAs substrates of Examples 1 to 4 have a uniform dislocation density in all crystal orientations.
　以上のように本開示の実施形態および実施例について説明を行なったが、上述の各実施形態および実施例の構成を適宜組み合わせることも当初から予定している。 Although the embodiments and examples of the present disclosure have been described above, it is also planned from the beginning to appropriately combine the configurations of the above-described embodiments and examples.
　今回開示された実施の形態はすべての点で例示であって、制限的なものではないと考えられるべきである。本発明の範囲は上記した実施の形態ではなく請求の範囲によって示され、請求の範囲と均等の意味、および範囲内でのすべての変更が含まれることが意図される。 The embodiments disclosed this time are to be considered as illustrative in all points and not restrictive. The scope of the present invention is shown not by the above-described embodiments but by the scope of claims, and is intended to include meanings equivalent to the scope of claims and all modifications within the scope.
　１　半絶縁性ＧａＡｓ基板、１１　第１測定点、１２　第２測定点、１３　第３測定点、１４　第４測定点、１５　第５測定点、１０１　坩堝、１０２　発熱体、１１０　調熱部材、１１１　第１調熱部材、１１２　第２調熱部材、１１３　第３調熱部材、Ｃ　ＧａＡｓ単結晶、Ｓ　ＧａＡｓ種結晶、Ｌ　ＧａＡｓ融液、Ｉ　界面、Ｅ　液体封止材。 1 semi-insulating GaAs substrate, 11 1st measurement point, 12 2nd measurement point, 13 3rd measurement point, 14 4th measurement point, 15 5th measurement point, 101 crucible, 102 heating element, 110 heat control member, 111 First heat control member, 112 second heat control member, 113 third heat control member, C GaAs single crystal, S GaAs seed crystal, L GaAs melt, I interface, E liquid encapsulant.

Claims (16)

  1. 　主面の面方位が（１００）面である半絶縁性ＧａＡｓ基板であって、
    　前記半絶縁性ＧａＡｓ基板は、直径が１５０ｍｍ以上である円盤状の形状を有し、
    　前記半絶縁性ＧａＡｓ基板は、前記主面の中心を第１測定点とし、前記第１測定点から［０１０］方向に沿って前記半絶縁性ＧａＡｓ基板の外周に至る第１線分の中点を第２測定点とし、前記第１線分上の前記外周から１０ｍｍ内側となる点を第３測定点とし、前記第１測定点、前記第２測定点および前記第３測定点で転位密度を測定した場合、これらの測定値の差が２０００ｃｍ-2以内である、半絶縁性ＧａＡｓ基板。     A semi-insulating GaAs substrate whose main surface has a (100) plane orientation,
    The semi-insulating GaAs substrate has a disk shape with a diameter of 150 mm or more,
    The semi-insulating GaAs substrate has a center of the main surface as a first measurement point, and a midpoint of a first line segment from the first measurement point to the outer periphery of the semi-insulating GaAs substrate along the [010] direction. As a second measurement point, and a point on the first line segment which is located 10 mm inside from the outer circumference as a third measurement point, and the dislocation density at the first measurement point, the second measurement point and the third measurement point. A semi-insulating GaAs substrate in which the difference between these measured values is within 2000 cm -2 when measured.
  2. 　前記半絶縁性ＧａＡｓ基板は、前記第１測定点から［０１１］方向に沿って前記半絶縁性ＧａＡｓ基板の外周に至る第２線分の中点を第４測定点とし、前記第２測定点および前記第４測定点で転位密度を測定した場合、これらの測定値の差が１７００ｃｍ-2以内である、請求項１に記載の半絶縁性ＧａＡｓ基板。 In the semi-insulating GaAs substrate, the midpoint of the second line segment from the first measuring point to the outer periphery of the semi-insulating GaAs substrate along the [011] direction is the fourth measuring point, and the second measuring point. The semi-insulating GaAs substrate according to claim 1, wherein, when the dislocation density is measured at the fourth measurement point, the difference between these measured values is within 1700 cm -2 .
  3. 　前記半絶縁性ＧａＡｓ基板は、前記第１測定点から［０１１］方向に沿って前記半絶縁性ＧａＡｓ基板の外周に至る第２線分の中点を第４測定点とし、前記第２線分上の前記外周から１０ｍｍ内側となる点を第５測定点とし、前記第１測定点、前記第４測定点および前記第５測定点で転位密度を測定した場合、これらの測定値の差が３８００ｃｍ-2以内である、請求項１または請求項２に記載の半絶縁性ＧａＡｓ基板。 In the semi-insulating GaAs substrate, the midpoint of the second line segment from the first measurement point to the outer periphery of the semi-insulating GaAs substrate along the [011] direction is the fourth measurement point, and the second line segment is If the dislocation density is measured at the first measurement point, the fourth measurement point, and the fifth measurement point, the point that is 10 mm inside from the outer circumference is the fifth measurement point, and the difference between these measurement values is 3800 cm. The semi-insulating GaAs substrate according to claim 1 or 2, which is within -2 .
  4. 　前記半絶縁性ＧａＡｓ基板は、前記第３測定点で転位密度を測定した場合、この測定値が１００００ｃｍ-2以下である、請求項１～請求項３のいずれか１項に記載の半絶縁性ＧａＡｓ基板。 The semi-insulating GaAs substrate according to any one of claims 1 to 3, wherein when the dislocation density is measured at the third measuring point, the measured value is 10,000 cm -2 or less. GaAs substrate.
  5. 　前記半絶縁性ＧａＡｓ基板は、前記第１測定点から［０１１］方向に沿って前記半絶縁性ＧａＡｓ基板の外周に至る第２線分上の前記外周から１０ｍｍ内側となる点を第５測定点とし、前記第５測定点で転位密度を測定した場合、この測定値が１００００ｃｍ-2以下である、請求項１～請求項４のいずれか１項に記載の半絶縁性ＧａＡｓ基板。 The semi-insulating GaAs substrate has a fifth measurement point at a point 10 mm inside from the outer circumference on a second line segment extending from the first measurement point to the outer circumference of the semi-insulating GaAs substrate along the [011] direction. The semi-insulating GaAs substrate according to any one of claims 1 to 4, wherein, when the dislocation density is measured at the fifth measurement point, the measured value is 10000 cm -2 or less.
  6. 　主面の面方位が（１００）面であるＧａＡｓ基板の製造方法であって、
    　ＧａＡｓ種結晶が底部に収容され、前記ＧａＡｓ種結晶上にＧａＡｓ融液が収容された坩堝と、前記坩堝の外周に沿って配設された発熱体と、前記坩堝および前記発熱体の間に配設された調熱部材とを備えた単結晶成長装置を準備する工程と、
    　前記単結晶成長装置において、前記調熱部材を通過した前記発熱体からの熱で前記ＧａＡｓ種結晶および前記ＧａＡｓ融液を加熱することにより、前記ＧａＡｓ種結晶からＧａＡｓ単結晶を成長させる工程と、
    　前記ＧａＡｓ単結晶を、その成長方向に対して垂直に切出すことにより、前記主面の面方位が（１００）面であるＧａＡｓ基板を得る工程とを含み、
    　前記調熱部材は、前記成長方向に沿って第１調熱部材、第２調熱部材および第３調熱部材の順に分割され、
    　前記第２調熱部材は、波長２μｍ以上３μｍ以下の範囲の光線透過率が、前記第１調熱部材の前記光線透過率および前記第３調熱部材の前記光線透過率に対し２倍以上５倍以下であり、
    　成長中の前記ＧａＡｓ単結晶と前記ＧａＡｓ融液との界面は、前記第２調熱部材を通過した前記発熱体からの熱で加熱される、ＧａＡｓ基板の製造方法。     A method for manufacturing a GaAs substrate having a main surface having a (100) plane orientation,
    A GaAs seed crystal is accommodated at the bottom, a crucible in which the GaAs melt is accommodated on the GaAs seed crystal, a heating element arranged along the outer periphery of the crucible, and a heating element disposed between the crucible and the heating element. A step of preparing a single crystal growth apparatus having a heat control member provided,
    In the single crystal growth apparatus, a step of growing a GaAs single crystal from the GaAs seed crystal by heating the GaAs seed crystal and the GaAs melt with heat from the heating element that has passed through the heat control member,
    Cutting the GaAs single crystal perpendicular to its growth direction to obtain a GaAs substrate having a main surface whose plane orientation is a (100) plane.
    The heat regulation member is divided in the order of a first heat regulation member, a second heat regulation member and a third heat regulation member along the growth direction,
    The light transmittance of the second heat control member in a wavelength range of 2 μm or more and 3 μm or less is at least twice as high as the light transmittance of the first heat control member and the light transmittance of the third heat control member. Less than twice
    A method of manufacturing a GaAs substrate, wherein an interface between the growing GaAs single crystal and the GaAs melt is heated by heat from the heating element that has passed through the second heat control member.
  7. 　前記第２調熱部材は、前記光線透過率が３０％以上である、請求項６に記載のＧａＡｓ基板の製造方法。 The method for manufacturing a GaAs substrate according to claim 6, wherein the light transmittance of the second heat control member is 30% or more.
  8. 　前記第１調熱部材、前記第２調熱部材および前記第３調熱部材は、それぞれムライト、ジルコニア、スピネル、カーボン、アルミナおよびサファイアからなる群より選ばれるいずれかを含む、請求項６または請求項７に記載のＧａＡｓ基板の製造方法。 7. The first heat control member, the second heat control member and the third heat control member each include any selected from the group consisting of mullite, zirconia, spinel, carbon, alumina and sapphire. Item 8. A method for manufacturing a GaAs substrate according to Item 7.
  9. 　前記第２調熱部材は、ムライト、アルミナおよびサファイアからなる群より選ばれるいずれかを含む、請求項６～請求項８のいずれか１項に記載のＧａＡｓ基板の製造方法。 The method for manufacturing a GaAs substrate according to any one of claims 6 to 8, wherein the second heat control member contains any one selected from the group consisting of mullite, alumina and sapphire.
  10. 　前記第２調熱部材は、前記成長方向と平行方向の長さが前記坩堝の内径に対し４０％以上６０％以下である、請求項６～請求項９のいずれか１項に記載のＧａＡｓ基板の製造方法。 10. The GaAs substrate according to claim 6, wherein the second heat regulation member has a length in a direction parallel to the growth direction of 40% or more and 60% or less of an inner diameter of the crucible. Manufacturing method.
  11. 　前記第１調熱部材および前記第３調熱部材は、表面粗さＲａが２μｍ以上３μｍ以下である、請求項６～請求項１０のいずれか１項に記載のＧａＡｓ基板の製造方法。 The method for manufacturing a GaAs substrate according to any one of claims 6 to 10, wherein the first heat control member and the third heat control member have a surface roughness Ra of 2 μm or more and 3 μm or less.
  12. 　前記界面は、その形状が前記成長方向に凸な弧状である、請求項６～請求項１１のいずれか１項に記載のＧａＡｓ基板の製造方法。 The method for manufacturing a GaAs substrate according to any one of claims 6 to 11, wherein the interface has an arc shape having a convex shape in the growth direction.
  13. 　前記ＧａＡｓ基板は、半絶縁性である、請求項６～請求項１２のいずれか１項に記載のＧａＡｓ基板の製造方法。 The method for manufacturing a GaAs substrate according to any one of claims 6 to 12, wherein the GaAs substrate is semi-insulating.
  14. 　前記第２調熱部材は、その厚みが前記第１調熱部材および前記第３調熱部材に対し０．２倍以上０．５倍以下である、請求項６～請求項１３のいずれか１項に記載のＧａＡｓ基板の製造方法。 14. The second heat control member according to claim 6, wherein a thickness of the second heat control member is 0.2 times or more and 0.5 times or less that of the first heat control member and the third heat control member. A method of manufacturing a GaAs substrate according to item.
  15. 　前記第１調熱部材、前記第２調熱部材および前記第３調熱部材は、その材質が同一である、請求項６～請求項１４のいずれか１項に記載のＧａＡｓ基板の製造方法。 The method for manufacturing a GaAs substrate according to any one of claims 6 to 14, wherein the first heat control member, the second heat control member, and the third heat control member are made of the same material.
  16. 　前記第２調熱部材と、前記第１調熱部材および前記第３調熱部材とは、その材質が異なる、請求項６～請求項１４のいずれかに記載のＧａＡｓ基板の製造方法。 15. The method of manufacturing a GaAs substrate according to claim 6, wherein the second heat control member is different from the first heat control member and the third heat control member in material.
PCT/JP2018/046154 2018-12-14 2018-12-14 SEMI-INSULATING GaAs SUBSTRATE AND METHOD FOR PRODUCING GaAs SUBSTRATE WO2020121526A1 (en)

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JP2004277267A (en) * 2003-03-19 2004-10-07 Hitachi Cable Ltd Apparatus for manufacturing compound semiconductor single crystal
JP2006232574A (en) * 2005-02-22 2006-09-07 Sumitomo Electric Ind Ltd Compound semiconductor single crystal and its manufacturing method
JP2007182361A (en) * 2005-01-31 2007-07-19 Hitachi Cable Ltd Semi-insulating galium-arsenic wafer and its manufacturing method
WO2010084878A1 (en) * 2009-01-20 2010-07-29 住友電気工業株式会社 Electrically conductive gaas crystal, electrically conductive gaas crystal substrate, and processes for producing those materials

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2004083301A (en) * 2002-08-23 2004-03-18 Hitachi Cable Ltd Single crystal manufacturing apparatus
JP2004277267A (en) * 2003-03-19 2004-10-07 Hitachi Cable Ltd Apparatus for manufacturing compound semiconductor single crystal
JP2007182361A (en) * 2005-01-31 2007-07-19 Hitachi Cable Ltd Semi-insulating galium-arsenic wafer and its manufacturing method
JP2006232574A (en) * 2005-02-22 2006-09-07 Sumitomo Electric Ind Ltd Compound semiconductor single crystal and its manufacturing method
WO2010084878A1 (en) * 2009-01-20 2010-07-29 住友電気工業株式会社 Electrically conductive gaas crystal, electrically conductive gaas crystal substrate, and processes for producing those materials

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