JP2013159510A

JP2013159510A - Apparatus and method for producing single crystal

Info

Publication number: JP2013159510A
Application number: JP2012021229A
Authority: JP
Inventors: Hiroyuki Kamata; 弘之鎌田; Tomohisa Kato; 智久加藤; Tomonori Miura; 知則三浦
Original assignee: Fujikura Ltd; National Institute of Advanced Industrial Science and Technology AIST
Current assignee: Fujikura Ltd; National Institute of Advanced Industrial Science and Technology AIST
Priority date: 2012-02-02
Filing date: 2012-02-02
Publication date: 2013-08-19

Abstract

PROBLEM TO BE SOLVED: To provide an apparatus and a method for producing an aluminum nitride single crystal capable of producing a high-quality aluminum nitride single crystal under a stable crystal growth condition by suppressing deposition of an aluminum nitride polycrystal in a gas discharge port.SOLUTION: This apparatus 1 for producing a single crystal includes a crystal growth vessel 2, a raw material container 3, a seed crystal 6, a gas introduction port 9, a gas discharge port 10, and heating means 11a-11d disposed on the outer periphery of the crystal growth vessel 2. A raw material 5 stored in the raw material container 3 is heated to generate sublimation gas, and the sublimation gas is condensed on the seed crystal 6 to grow a single crystal 7, then, gas passing through the seed crystal 6 is discharged from the gas discharge port 10. In the crystal growth vessel 2, a low-temperature region having a lower temperature than a temperature of a crystal growth position at a crystal growth time is provided, which is larger than the sectional area of the gas discharge port 10, in a gas passage R3 on the furthermore downstream side than a position where a crystal is grown with respect to the seed crystal 6, among gas passages R1-R3 reaching the gas discharge port 10 side including the seed crystal 6.

Description

本発明は、単結晶製造装置および単結晶の製造方法に関する。 The present invention relates to a single crystal manufacturing apparatus and a single crystal manufacturing method.

近年、青色発光素子に端を発し、窒化ガリウム系半導体に関する研究開発は目覚しい進展をみせている。窒化ガリウム系半導体素子は、成長基板上に有機金属気相成長法（Metal-Organic Vapor Phase Epitaxy、ＭＯＶＰＥ）により製造されており、現在、成長基板としては、サファイア、炭化珪素（ＳｉＣ）、珪素（Ｓｉ）が用いられている。しかしながら、これらの基板は、窒化ガリウムとの格子不整合が大きいため、この上に成長させた窒化ガリウム層において高密度に転位が発生してしまうという問題がある。高密度の転位は、窒化ガリウムを発光素子やパワーデバイスに用いた場合に、その性能や寿命に悪影響を及ぼす。このため、窒化ガリウムとの格子不整合がより小さい基板材料が求められ、そのような材料として窒化アルミニウム単結晶が注目されている。
窒化アルミニウム単結晶は、窒化ガリウムと全率固溶し、窒化ガリウムとの格子不整合が２．４％と小さい。また、その熱伝導率は２９０Ｗｍ^−１Ｋ^−１と高く、放熱性に優れる。このため、窒化アルミニウム単結晶は、窒化ガリウム系、特に、より格子不整合の小さいＡｌＧａＮ系半導体の基板材料として期待されている。 In recent years, research and development on gallium nitride semiconductors have made remarkable progress, starting with blue light-emitting elements. Gallium nitride semiconductor devices are manufactured on a growth substrate by metal-organic vapor phase epitaxy (MOVPE). Currently, growth substrates include sapphire, silicon carbide (SiC), silicon ( Si) is used. However, since these substrates have a large lattice mismatch with gallium nitride, there is a problem that dislocations occur at high density in the gallium nitride layer grown thereon. High-density dislocations adversely affect the performance and life when gallium nitride is used in light-emitting elements and power devices. For this reason, a substrate material having a smaller lattice mismatch with gallium nitride is required, and aluminum nitride single crystal has attracted attention as such a material.
The aluminum nitride single crystal is completely dissolved in gallium nitride and has a small lattice mismatch with gallium nitride of 2.4%. Further, its thermal conductivity is as high as ^290Wm ^{-1 K} -1, excellent heat dissipation. For this reason, the aluminum nitride single crystal is expected as a substrate material for a gallium nitride-based, particularly an AlGaN-based semiconductor having a smaller lattice mismatch.

窒化アルミニウム単結晶の製造方法としては、溶液法ではフラックス法、気相法ではＭＯＶＰＥ法、水素化物気相堆積法（Hydride Vapor Phase Epitaxy、ＨＶＰＥ）、昇華法などがある。これらの中でも、昇華法は、一般的に成長速度が速いため、バルク結晶の作製に対して有力な方法である。この昇華法とは、原料である窒化アルミニウムを昇華させ、それを昇華温度より低い温度域である析出部において再凝縮させることにより単結晶を作製する方法である。 As a method for producing an aluminum nitride single crystal, there are a flux method for a solution method, an MOVPE method for a vapor phase method, a hydride vapor phase epitaxy (HVPE) method, a sublimation method, and the like. Among these, the sublimation method is a powerful method for producing a bulk crystal because the growth rate is generally high. This sublimation method is a method for producing a single crystal by sublimating aluminum nitride as a raw material and re-condensing it in a precipitation part which is a temperature range lower than the sublimation temperature.

昇華法を用いた窒化アルミニウム単結晶の製造装置としては、例えば特許文献１に記載された製造装置が提案されている。
図２は、特許文献１に記載された窒化アルミニウム単結晶の製造装置を模式的に示す概略構成図である。
図２に示す窒化アルミニウム単結晶の製造装置１０１は、加熱炉本体（結晶成長容器）１０３と、加熱炉本体１０３の内底部に配置された黒鉛るつぼ（原料容器）１０４と、加熱炉本体１０３の天井部に取り付けられたサセプタ１０８を備えて構成されている。黒鉛るつぼ１０４内には窒化アルミニウム粉末などの原料１０９が収納され、サセプタ１０８の下面には原料１０９と対峙するように種結晶（種結晶）１０７が貼り付けられている。 As an apparatus for manufacturing an aluminum nitride single crystal using a sublimation method, for example, a manufacturing apparatus described in Patent Document 1 has been proposed.
FIG. 2 is a schematic configuration diagram schematically showing an apparatus for producing an aluminum nitride single crystal described in Patent Document 1. As shown in FIG.
An aluminum nitride single crystal manufacturing apparatus 101 shown in FIG. 2 includes a heating furnace body (crystal growth vessel) 103, a graphite crucible (raw material container) 104 disposed on the inner bottom of the heating furnace body 103, and a heating furnace body 103. A susceptor 108 attached to the ceiling is provided. A raw material 109 such as aluminum nitride powder is stored in the graphite crucible 104, and a seed crystal (seed crystal) 107 is attached to the lower surface of the susceptor 108 so as to face the raw material 109.

また、加熱炉本体１０３の底部には、窒素ガスなどのガス供給装置に接続されたガス流入口１０５が形成され、加熱炉本体１０３の天井部には、真空ポンプなどの減圧装置に接続されたガス排出口１０６が形成されている。この減圧装置の作動により、加熱炉本体１０３の内部を所定のガス圧力に調整できるようになっている。また、加熱炉本体１０３の外側には、その外周に沿って、加熱炉本体１０３内部に配された原料１０９、サセプタ１０８、種結晶１０７を加熱する誘導加熱方式の加熱手段１０２が設けられている。 A gas inlet 105 connected to a gas supply device such as nitrogen gas is formed at the bottom of the heating furnace main body 103, and a ceiling portion of the heating furnace main body 103 is connected to a decompression device such as a vacuum pump. A gas discharge port 106 is formed. By operating the decompression device, the inside of the heating furnace main body 103 can be adjusted to a predetermined gas pressure. In addition, an induction heating type heating means 102 for heating the raw material 109, the susceptor 108, and the seed crystal 107 disposed inside the heating furnace main body 103 is provided along the outer periphery of the heating furnace main body 103. .

窒化アルミニウム単結晶の作製に際し、ガス排出口１０６を介し加熱炉本体１０３内を真空排気した後、ガス流入口１０５を介して窒素ガスなどのプロセスガスを加熱炉本体１０３内に導入し、圧力を調整する。続いて加熱炉本体１０３の内部に配された原料１０９、サセプタ１０８、種結晶１０７を加熱する。
加熱によって原料１０９から昇華した昇華ガスは、ガス流入口１０５から導入した窒素ガスと混合され、上方に流れる。そして、上方に流れた昇華ガスの一部は、種結晶１０７付近の低温領域（成長部）で冷却されて凝縮し、種結晶１０７上に窒化アルミニウム単結晶として結晶成長する。一方、余剰の昇華ガスは、窒素ガスとともに、さらに上方に流れ、ガス排出口１０６から外部に排出される。 When producing the aluminum nitride single crystal, the inside of the heating furnace body 103 is evacuated through the gas discharge port 106, and then a process gas such as nitrogen gas is introduced into the heating furnace body 103 through the gas inlet 105, and the pressure is increased. adjust. Subsequently, the raw material 109, the susceptor 108, and the seed crystal 107 disposed inside the heating furnace main body 103 are heated.
The sublimation gas sublimated from the raw material 109 by heating is mixed with nitrogen gas introduced from the gas inlet 105 and flows upward. A part of the sublimation gas flowing upward is cooled and condensed in a low temperature region (growth part) in the vicinity of the seed crystal 107, and crystal grows as an aluminum nitride single crystal on the seed crystal 107. On the other hand, surplus sublimation gas flows further upward along with nitrogen gas, and is discharged to the outside from the gas discharge port 106.

特許第３９７０７８９号公報Japanese Patent No. 3970789

図２に示す窒化アルミニウム単結晶の製造装置１０１にあっては、ガス排出口１０６が種結晶１０７よりも上部側であって、加熱手段１０２が主に加熱する領域から離れた位置に形成されているので、ガス排出口１０６は窒化アルミニウムの結晶成長温度よりも低い温度にされている。
このため、ガス排出口１０６に到達した昇華ガスは、ガス排出口１０６でさらに冷却され、その内壁面に窒化アルミニウム多結晶となって析出する。そして、時間経過とともにこの窒化アルミニウム多結晶の堆積量が増大する結果、ガス排出口が閉塞する問題がある。この現象により、加熱炉本体内の圧力制御が困難になり、結晶の成長条件が変化し、得られる窒化アルミニウム単結晶の品質に悪影響が及ぼされるおそれがあった。 In the aluminum nitride single crystal manufacturing apparatus 101 shown in FIG. 2, the gas discharge port 106 is on the upper side of the seed crystal 107, and the heating means 102 is mainly formed at a position away from the heating area. Therefore, the gas outlet 106 is set to a temperature lower than the crystal growth temperature of aluminum nitride.
For this reason, the sublimation gas that has reached the gas discharge port 106 is further cooled at the gas discharge port 106, and is deposited on the inner wall surface as polycrystalline aluminum nitride. As a result, the amount of deposited aluminum nitride polycrystal increases with time, resulting in a problem that the gas outlet is blocked. This phenomenon makes it difficult to control the pressure in the heating furnace body, changes the crystal growth conditions, and may adversely affect the quality of the resulting aluminum nitride single crystal.

本発明は、このような従来の実情に鑑みなされたものであり、窒化アルミニウム単結晶などの単結晶成長過程において、ガス排出口側における多結晶の析出を抑制し、安定な結晶成長条件で良質な単結晶を製造することができる単結晶製造装置および単結晶の製造方法を提供することを目的とする。 The present invention has been made in view of such a conventional situation, and suppresses the precipitation of polycrystals on the gas outlet side in a single crystal growth process such as an aluminum nitride single crystal, and provides high quality under stable crystal growth conditions. An object of the present invention is to provide a single crystal manufacturing apparatus and a single crystal manufacturing method capable of manufacturing a single crystal.

上記課題を解決するため、本発明の単結晶製造装置は、結晶成長容器と、該結晶成長容器の内底部に配置された原料容器と、前記結晶成長容器内の前記原料容器の上方に、前記原料容器と対向するように支持された種結晶と、前記結晶成長容器において結晶成長位置よりも下方に設けられたガス導入口と、前記結晶成長容器において結晶成長位置よりも上方に設けられたガス排出口と、前記結晶成長容器の外周に配設された加熱手段とを備え、前記原料容器内に収容された原料を加熱して昇華ガスを発生させ、該昇華ガスを前記種結晶上で凝縮させることで単結晶を成長させ、前記種結晶を通過したガスを前記ガス排出口から排出する単結晶製造装置であって、前記結晶成長容器に前記ガス排出口の断面積よりも大きく、前記種結晶を含み前記ガス排出口側に至るガス流路を設け、該ガス流路のうち、前記種結晶に対し結晶を成長させる位置よりも下流側のガス流路に、結晶成長時に前記結晶成長位置の温度よりも低温度とする低温領域を設けたことを特徴とする。 In order to solve the above problems, a single crystal production apparatus of the present invention includes a crystal growth container, a raw material container disposed on an inner bottom portion of the crystal growth container, and above the raw material container in the crystal growth container, A seed crystal supported to face the raw material container, a gas inlet provided below the crystal growth position in the crystal growth container, and a gas provided above the crystal growth position in the crystal growth container A discharge port and a heating means disposed on the outer periphery of the crystal growth vessel are provided, the raw material stored in the raw material vessel is heated to generate sublimation gas, and the sublimation gas is condensed on the seed crystal. A single crystal manufacturing apparatus that grows a single crystal and discharges the gas that has passed through the seed crystal from the gas outlet, wherein the crystal growth vessel has a cross-sectional area that is larger than a cross-sectional area of the gas outlet. Including crystals before A gas flow path leading to the gas discharge port side is provided, and in the gas flow path, a gas flow path on the downstream side of the position where the crystal is grown on the seed crystal is lower than the temperature of the crystal growth position during crystal growth. A low temperature region for providing a low temperature is provided.

本発明によれば、ガス排出口の断面積よりも大きく、種結晶を含みガス排出口に至るガス流路を設け、結晶成長位置よりも下流側に低温領域を設けたので、結晶成長位置を通過した昇華ガスは、この低温領域において多結晶体の堆積をなす。これにより、ガス排出口側において多結晶体の堆積が抑制されるので、ガス排出口が閉塞もしくは狭小化することがない。また、ガス流路はガス排出口よりも大きく、多結晶体が堆積しても閉塞することがない。従って、長時間の運転であっても、ガスの流れを安定化することができ、安定な結晶成長条件で良質な単結晶を製造する装置を提供できる。 According to the present invention, since the gas flow path that is larger than the cross-sectional area of the gas discharge port and includes the seed crystal and reaches the gas discharge port is provided, and the low temperature region is provided downstream of the crystal growth position, the crystal growth position is The sublimation gas that has passed forms a polycrystalline body in this low temperature region. Thereby, since the deposition of the polycrystalline body is suppressed on the gas discharge port side, the gas discharge port is not blocked or narrowed. Further, the gas flow path is larger than the gas discharge port, so that it does not block even if a polycrystal is deposited. Accordingly, the gas flow can be stabilized even during long-time operation, and an apparatus for producing a high-quality single crystal under stable crystal growth conditions can be provided.

本発明において、前記ガス流路のうち、前記結晶成長位置よりも下流側の前記結晶成長位置に近い領域に、結晶成長時に前記結晶成長位置の温度と同等か、もしくはそれよりも温度を高くする高温領域を設け、前記ガス流路のうち、前記結晶成長位置よりも下流側の前記結晶位置から遠い領域に、結晶成長時に前記結晶成長位置の温度よりも低温度とする低温領域を設けたことを特徴とすることが好ましい。
高温領域を結晶成長位置下流側の結晶成長位置に近いガス流路に設けることで、この高温領域のガス流路において多結晶体の堆積を抑制し、低温領域を結晶成長位置下流側の結晶成長位置から遠い領域に設けることで結晶成長位置から離れたガス流路に多結晶体の堆積を促進する。高温領域と低温領域をこのように配置することで結晶成長位置下流側の結晶成長位置に近いガス流路とガス排出口側での多結晶体の堆積を抑制できる。このため、長時間の運転であっても、ガスの流れを安定化することができ、安定な結晶成長条件で良質な単結晶を製造する装置を提供できる。 In the present invention, in the gas flow path, in the region close to the crystal growth position downstream from the crystal growth position, the temperature is equal to or higher than the temperature of the crystal growth position during crystal growth. A high temperature region is provided, and a low temperature region that is lower than the temperature of the crystal growth position during crystal growth is provided in a region of the gas flow channel that is farther from the crystal position downstream of the crystal growth position. Is preferably characterized.
By providing a high temperature region in the gas flow path near the crystal growth position downstream of the crystal growth position, the deposition of polycrystals is suppressed in the gas flow path in the high temperature area, and the low temperature region is grown downstream of the crystal growth position. By providing it in a region far from the position, the deposition of the polycrystalline body is promoted in the gas flow path away from the crystal growth position. By arranging the high temperature region and the low temperature region in this way, it is possible to suppress the deposition of polycrystals on the gas flow path near the crystal growth position on the downstream side of the crystal growth position and on the gas discharge port side. For this reason, the gas flow can be stabilized even during long-time operation, and an apparatus for producing a high-quality single crystal under stable crystal growth conditions can be provided.

本発明において、前記ガス流路のうち、前記結晶成長位置よりも下流側に、その横断面積が下流側に向かって徐々に大きくされる領域を設けることが好ましい。
結晶成長位置を通過したガスがガス流路に多結晶体を堆積させるおそれがあるが、結晶成長位置よりも下流側のガス流路に下流側に向かって徐々に広くなる領域を設けておくと、この領域に多結晶体が堆積しても、流路断面積が大きいのでガス流路の流れが妨げられるおそれがない。このため、長時間の運転であっても、ガスの流れを安定化することができ、安定な結晶成長条件で良質な単結晶を製造する装置を提供できる。 In this invention, it is preferable to provide the area | region where the cross-sectional area is gradually enlarged toward the downstream from the said crystal growth position among the said gas flow paths.
There is a risk that the gas that has passed through the crystal growth position may deposit a polycrystal in the gas flow path, but if the gas flow path downstream from the crystal growth position is provided with a region that gradually widens toward the downstream side, Even if a polycrystal is deposited in this region, the flow passage of the gas flow passage is not hindered because the flow passage cross-sectional area is large. For this reason, the gas flow can be stabilized even during long-time operation, and an apparatus for producing a high-quality single crystal under stable crystal growth conditions can be provided.

本発明の単結晶の製造方法は、先のいずれかに記載の単結晶製造装置を用い、種結晶を基にして単結晶を製造する方法であって、結晶成長位置よりも下流側のガス流路を加熱して前記結晶成長位置の温度と同等か、もしくはそれよりも温度を高くして高温領域を生成し、該高温領域のガス流路周りにおける多結晶の析出を防止しつつ結晶成長を行うことを特徴とする。
上述の単結晶の製造方法によれば、結晶成長容器内の結晶成長位置とガス排出口との間にガス流路を形成し、単結晶の結晶成長時に、結晶成長位置よりも下流側の領域を、結晶成長位置の温度以上の高温領域とすることにより、この高温領域における多結晶体の堆積を防止しつつ結晶成長できる。この高温領域の下流側に低温領域を生成するので、この低温領域のガス流路に多結晶体の堆積を行うことができ、ガス排出口側と結晶成長位置側に多結晶体の堆積を防止しつつ長時間結晶成長できる方法を提供できる。
このため、安定な結晶成長条件で良質な単結晶を製造することが可能となる。 A method for producing a single crystal according to the present invention is a method for producing a single crystal based on a seed crystal using any of the single crystal production apparatuses described above, wherein the gas flow downstream of the crystal growth position is produced. The channel is heated to generate a high-temperature region that is equal to or higher than the temperature of the crystal growth position, and crystal growth is prevented while preventing precipitation of polycrystals around the gas flow path in the high-temperature region. It is characterized by performing.
According to the above-described method for producing a single crystal, a gas flow path is formed between the crystal growth position in the crystal growth vessel and the gas discharge port, and a region on the downstream side of the crystal growth position when the single crystal is grown. Is set to a high temperature region equal to or higher than the temperature of the crystal growth position, crystal growth can be achieved while preventing the deposition of polycrystals in this high temperature region. Since a low temperature region is generated downstream of the high temperature region, polycrystals can be deposited in the gas flow path of the low temperature region, and polycrystals are prevented from being deposited on the gas outlet side and the crystal growth position side. In addition, a method capable of growing crystals for a long time can be provided.
For this reason, it becomes possible to manufacture a high-quality single crystal under stable crystal growth conditions.

本発明によれば、種結晶の上方にガス排出口を有する結晶成長容器内で、昇華法によって単結晶を製造する単結晶製造装置であって、結晶成長容器内の種結晶とガス排出口との間にガス流路を有し、単結晶の結晶成長時に、このガス流路の少なくとも一部の領域を種結晶の温度よりも低温領域としているため、結晶成長位置を通過した昇華ガスが低温領域に優先的に多結晶体を堆積させる結果、ガス排出口とその近傍において多結晶体を堆積させることなく単結晶の成長ができる。
このため、ガス排出口側のガス流路が、多結晶体の析出によって狭小化もしくは閉塞することを防止でき、安定な結晶成長条件で良質な単結晶を製造することが可能となる。 According to the present invention, there is provided a single crystal manufacturing apparatus for manufacturing a single crystal by a sublimation method in a crystal growth vessel having a gas discharge port above a seed crystal, the seed crystal and the gas discharge port in the crystal growth vessel, Since a gas flow path is provided between them and at least a part of the area of the gas flow path is lower than the temperature of the seed crystal during single crystal growth, the sublimation gas that has passed through the crystal growth position has a low temperature. As a result of preferentially depositing polycrystals in the region, single crystals can be grown without depositing polycrystals at and near the gas outlet.
For this reason, it is possible to prevent the gas flow path on the gas discharge port side from being narrowed or clogged due to the precipitation of the polycrystalline body, and it is possible to manufacture a high-quality single crystal under stable crystal growth conditions.

本発明の実施形態に係る単結晶製造装置の一例を模式的に示す概略構成図である。It is a schematic structure figure showing typically an example of a single crystal manufacturing device concerning an embodiment of the present invention. 従来の単結晶製造装置の一例を模式的に示す概略構成図である。It is a schematic block diagram which shows typically an example of the conventional single crystal manufacturing apparatus.

以下、図面を参照しながら、本発明について詳細に説明する。
図１は本発明の実施形態に係る単結晶製造装置の一例を模式的に示す概略構成図である。
本発明の単結晶製造装置１は、結晶成長容器２と、その内底部に配された原料容器３と、結晶成長容器２の上部側に設けられた種結晶保持部材４と、該種結晶保持部材４の下端部に保持された種結晶６を備えて構成され、昇華法により単結晶を製造する装置である。
なお、以下の説明では、単結晶として窒化アルミニウム単結晶を製造する場合を例にする。
結晶成長容器２は、内部の気密を保持し得る耐熱性容器である。結晶成長容器２は、全体として有底筒状をなし、下側から順に、小径部２１、拡径部２２、大径部２３により構成されている。これらのうち小径部２１および大径部２３は、それぞれ略一定の内径を有し、大径部２３の内径が小径部２１の内径より大きくされている。また、拡径部２２は、下端部から上端部に向かって徐々に内径が拡大する形状をなし、下端部が小径部２１と略同一の内径、上端部が大径部２３と略同一の内径とされている。これら各部２１、２２、２３は、互いに内部が連通されている。 Hereinafter, the present invention will be described in detail with reference to the drawings.
FIG. 1 is a schematic configuration diagram schematically showing an example of a single crystal manufacturing apparatus according to an embodiment of the present invention.
A single crystal production apparatus 1 according to the present invention includes a crystal growth vessel 2, a raw material vessel 3 arranged on the inner bottom thereof, a seed crystal holding member 4 provided on the upper side of the crystal growth vessel 2, and the seed crystal holding It is an apparatus that includes a seed crystal 6 held at the lower end of the member 4 and produces a single crystal by a sublimation method.
In the following description, an example in which an aluminum nitride single crystal is manufactured as a single crystal is taken as an example.
The crystal growth vessel 2 is a heat-resistant vessel that can maintain the internal airtightness. The crystal growth vessel 2 has a bottomed cylindrical shape as a whole, and includes a small diameter portion 21, an enlarged diameter portion 22, and a large diameter portion 23 in order from the lower side. Among these, the small diameter portion 21 and the large diameter portion 23 each have a substantially constant inner diameter, and the inner diameter of the large diameter portion 23 is larger than the inner diameter of the small diameter portion 21. The enlarged diameter portion 22 has a shape in which the inner diameter gradually increases from the lower end portion toward the upper end portion, the lower end portion has substantially the same inner diameter as the small diameter portion 21, and the upper end portion has substantially the same inner diameter as the large diameter portion 23. It is said that. These parts 21, 22, and 23 are in communication with each other.

小径部２１の内底部には、原料容器３が配置され、該原料容器３の内部に窒化アルミニウム粉末などの原料５が収納されている。
原料容器３の上方には、種結晶支持部材４が配設されている。種結晶支持部材４は、円柱状をなした管体であり、下端面が原料５と対向するように軸方向を鉛直方向として設けられている。種結晶支持部材４には、図示しない移動駆動機構および回転駆動機構が取り付けられており、これらの作動によって、原料５に対する進行方向および退行方向に移動駆動されるとともに軸回りに回転駆動されるようになっている。 A raw material container 3 is disposed on the inner bottom of the small diameter portion 21, and a raw material 5 such as aluminum nitride powder is accommodated in the raw material container 3.
A seed crystal support member 4 is disposed above the raw material container 3. The seed crystal support member 4 is a cylindrical tube body, and is provided with the axial direction as the vertical direction so that the lower end surface faces the raw material 5. The seed crystal support member 4 is provided with a movement drive mechanism and a rotation drive mechanism (not shown). By these operations, the seed crystal support member 4 is driven to move in the advancing direction and the retreat direction with respect to the raw material 5 and is driven to rotate about the axis. It has become.

種結晶支持部材４の下端面には原料５と対向するように種結晶６が担持されている。種結晶６は、窒化アルミニウム単結晶７を成長させる際、移動駆動機構による種結晶保持部材４の移動操作により、小径部２１内の上方（後述する成長部２ｃ）に位置するように位置調整される。
結晶成長用の種結晶６は、例えば、板状又は円板状のＳｉＣ単結晶、ＡｌＮ単結晶、ＡｌＮ／ＳｉＣ単結晶（ＳｉＣ単結晶上に膜厚２００〜５００μｍ程度のＡｌＮ単結晶膜をヘテロ成長させた単結晶）である。 A seed crystal 6 is supported on the lower end surface of the seed crystal support member 4 so as to face the raw material 5. When the aluminum nitride single crystal 7 is grown, the position of the seed crystal 6 is adjusted so that the seed crystal 6 is positioned above the small-diameter portion 21 (a growth portion 2c described later) by the movement operation of the seed crystal holding member 4 by the movement driving mechanism. The
The seed crystal 6 for crystal growth is, for example, a plate-like or disc-like SiC single crystal, AlN single crystal, AlN / SiC single crystal (an AlN single crystal film having a thickness of about 200 to 500 μm is heterogeneously formed on the SiC single crystal. Single crystal grown).

小径部２１内の原料５と種結晶６との間には、仕切部材８が配設されている。仕切部材８は、小径部２１の内径と略同じ外径を有するドーナツ板状の円環部８ａと、この円環部８ａの内側から立設された円筒部８ｂとからなり、円環部８ａの外周端面が小径部２１の内壁面に固着されている。円筒部８ｂは、その内径が種結晶６の外径よりも大きくされており、その下部開口が原料５側に向き、上部開口が種結晶６側に向くように配されている。このような仕切部材８を設けることにより、原料５からの昇華ガスを仕切部材８より外側に分散することを抑え、昇華ガスを種結晶６付近に効率良く供給できる。このため、種結晶６上に、窒化アルミニウム単結晶７を効率良く成長できる。 A partition member 8 is disposed between the raw material 5 and the seed crystal 6 in the small diameter portion 21. The partition member 8 includes a donut plate-like annular portion 8a having an outer diameter substantially the same as the inner diameter of the small-diameter portion 21, and a cylindrical portion 8b provided upright from the inner side of the annular portion 8a. Is fixed to the inner wall surface of the small diameter portion 21. The cylindrical portion 8b has an inner diameter that is larger than the outer diameter of the seed crystal 6, and is arranged so that its lower opening faces the raw material 5 side and its upper opening faces the seed crystal 6 side. By providing such a partition member 8, it is possible to suppress the sublimation gas from the raw material 5 from being dispersed outside the partition member 8 and to efficiently supply the sublimation gas to the vicinity of the seed crystal 6. For this reason, the aluminum nitride single crystal 7 can be efficiently grown on the seed crystal 6.

また、小径部２１の周壁には、原料容器３の開口部近傍に臨むガス導入口９が形成されている。ガス導入口９は、窒素ガスなどのガス供給装置に接続されており、ガス導入口９から窒素ガスなどのプロセスガスを導入することにより、結晶成長容器２の内部にプロセスガスを満たすことができるようになっている。一方、大径部２３の上部（後述する第２下流部２ｅに対応する部分）の周壁には、真空ポンプなどの減圧装置に接続されたガス排出口１０が形成されており、結晶成長容器２の内部を所定のガス圧に調整できるようになっている。 In addition, a gas inlet 9 facing the vicinity of the opening of the raw material container 3 is formed in the peripheral wall of the small diameter portion 21. The gas introduction port 9 is connected to a gas supply device such as nitrogen gas. By introducing a process gas such as nitrogen gas from the gas introduction port 9, the inside of the crystal growth vessel 2 can be filled with the process gas. It is like that. On the other hand, a gas discharge port 10 connected to a decompression device such as a vacuum pump is formed on the peripheral wall of the upper portion of the large-diameter portion 23 (a portion corresponding to a second downstream portion 2e described later). The inside can be adjusted to a predetermined gas pressure.

なお、以下の説明では、結晶成長容器２の内部空間のうち、原料容器３が収容されている領域を原料部２ａ、窒化アルミニウム単結晶７を結晶成長させる際の種結晶６の設置領域と窒化アルミニウム単結晶７を成長させる領域とを合わせた領域（小径部２１の内側の上方領域）を成長部２ｃ、原料部２ａと成長部２ｃとの間の領域を中間部２ｂと称する。さらに、種結晶６の設置領域よりも上側の領域（空間）のうち、拡径部２２の内側の領域を第１下流部２ｄ、大径部２３の内側の領域を第２下流部２ｅと称する。ここで、大径部２３の内径が小径部２１の内径よりも大きいことにより、第１下流部２ｄおよび第２下流部２ｅの横断面積は、それより下方の原料部２ａ、中間部２ｂ、成長部２ｃの個々の横断面積よりも大きくされている。なお、ここで言う「横断面」とは、水平断面を示す。 In the following description, in the internal space of the crystal growth vessel 2, the region in which the raw material vessel 3 is accommodated is the raw material portion 2 a, and the installation region of the seed crystal 6 when the aluminum nitride single crystal 7 is grown is nitrided A region combined with a region in which the aluminum single crystal 7 is grown (an upper region inside the small diameter portion 21) is referred to as a growth portion 2c, and a region between the raw material portion 2a and the growth portion 2c is referred to as an intermediate portion 2b. Further, of the region (space) above the region where the seed crystal 6 is placed, the region inside the enlarged diameter portion 22 is called the first downstream portion 2d, and the region inside the large diameter portion 23 is called the second downstream portion 2e. . Here, since the inner diameter of the large-diameter portion 23 is larger than the inner diameter of the small-diameter portion 21, the cross-sectional areas of the first downstream portion 2d and the second downstream portion 2e are lower than the raw material portion 2a, the intermediate portion 2b, and the growth. It is made larger than each cross-sectional area of the part 2c. The “cross section” referred to here indicates a horizontal section.

以上のような結晶成長容器２、種結晶保持部材４、仕切部材８は、黒鉛、窒化硼素、窒化アルミニウム、窒化ガリウム、炭化珪素、窒化珪素、モリブデン、タングステン、タンタル、炭化モリブデン、炭化ジルコニウム、炭化タングステン、炭化タンタル、窒化モリブデン、窒化ジルコニウム、窒化タングステン、窒化タンタルのうち少なくとも一種類から形成されている。これらの材料は、窒化アルミニウム単結晶の結晶成長時の２０００℃程度の高温での熱的耐性を有し、昇華ガスに対する耐腐食性に優れるため、結晶成長容器２、種結晶保持部材４、仕切部材８の構成材料として好ましい。なお、これらの材料よりなる各部分には、耐腐食性等を付与するために表面処理が施されていてもよい。
また、結晶成長容器２の内部において、種結晶６が設置される位置、換言すると成長部２ｃの位置から、第１下流部２ｄ、第２下流部２ｅを経てガス排出口１０の位置までガス流路が形成されている。本実施形態では便宜的に成長部２ｃのガス流路を第１のガス流路Ｒ１、第１下流部２ｄのガス流路を第２のガス流路Ｒ２、第２下流部２ｅのガス流路を第３のガス流路Ｒ３と呼称する。図１の装置では、第１のガス流路Ｒ１の中央部に種結晶保持部材４の先端部が配置され、種結晶保持部材４の周囲の空間はガス流路とされている。 The crystal growth container 2, seed crystal holding member 4, and partition member 8 as described above are composed of graphite, boron nitride, aluminum nitride, gallium nitride, silicon carbide, silicon nitride, molybdenum, tungsten, tantalum, molybdenum carbide, zirconium carbide, and carbonized carbon. It is formed from at least one of tungsten, tantalum carbide, molybdenum nitride, zirconium nitride, tungsten nitride, and tantalum nitride. Since these materials have thermal resistance at a high temperature of about 2000 ° C. during crystal growth of an aluminum nitride single crystal and are excellent in corrosion resistance against sublimation gas, the crystal growth vessel 2, seed crystal holding member 4, partition It is preferable as a constituent material of the member 8. In addition, each part which consists of these materials may be surface-treated in order to provide corrosion resistance etc.
Further, in the inside of the crystal growth vessel 2, the gas flow from the position where the seed crystal 6 is installed, in other words, from the position of the growth part 2c to the position of the gas outlet 10 through the first downstream part 2d and the second downstream part 2e. A road is formed. In the present embodiment, for convenience, the gas flow path of the growth part 2c is the first gas flow path R1, the gas flow path of the first downstream part 2d is the second gas flow path R2, and the gas flow path of the second downstream part 2e. Is referred to as a third gas flow path R3. In the apparatus of FIG. 1, the tip of the seed crystal holding member 4 is disposed at the center of the first gas flow path R1, and the space around the seed crystal holding member 4 is a gas flow path.

前記結晶成長容器２の外側には、その外周に沿って、結晶成長容器２内の各内部空間（原料部２ａ、中間部２ｂ、成長部２ｃ、第１下流部２ｄ）を加熱するための加熱手段１１ａ、１１ｂ、１１ｃ、１１ｄが設けられている。これらの加熱手段１１ａ〜１１ｄは、特に限定されるものではないが、高周波誘導加熱装置または抵抗加熱ヒータといった、従来公知のものを用いることができる。
加熱手段は、具体的には、原料部２ａを取り囲むように小径部２１の周囲に設けられた第１加熱手段１１ａと、中間部２ｂを取り囲むように小径部２１の周囲に設けられた第２加熱手段１１ｂと、成長部２ｃを取り囲むように小径部２１の周囲に設けられた第３加熱手段１１ｃと、第１下流部２ｄを取り囲むように拡径部２２の周囲に設けられた第４加熱手段１１ｄとから構成されている。 On the outside of the crystal growth vessel 2, heating for heating each internal space (the raw material portion 2a, the intermediate portion 2b, the growth portion 2c, and the first downstream portion 2d) in the crystal growth vessel 2 along the outer periphery thereof. Means 11a, 11b, 11c, 11d are provided. Although these heating means 11a-11d are not specifically limited, Conventionally well-known things, such as a high frequency induction heating apparatus or a resistance heater, can be used.
Specifically, the heating means includes a first heating means 11a provided around the small-diameter portion 21 so as to surround the raw material portion 2a, and a second heating means provided around the small-diameter portion 21 so as to surround the intermediate portion 2b. The heating means 11b, the third heating means 11c provided around the small diameter part 21 so as to surround the growth part 2c, and the fourth heating provided around the enlarged diameter part 22 so as to surround the first downstream part 2d. And means 11d.

このように第１〜第４加熱手段１１ａ〜１１ｄが設けられていることにより、原料部２ａ、中間部２ｂ、成長部２ｃ、第１下流部２ｄの温度を、独立に制御可能とされている。
ここで、第１〜第４加熱手段１１ａ〜１１ｄによる結晶成長容器２内の温度分布の一例を、図１の結晶成長容器２の右側に示す。この例では、原料部２ａの温度は原料５の昇華温度以上、中間部２ｂの温度は原料部２ａの温度より若干高く、成長部２ｃの温度は原料部２ａの温度より低く、第１下流部２ｄの温度は成長部２ｃの温度以上の高温領域とされており、第２下流部２ｅは、上方側（下流側）に向かって温度が徐々に下降して成長部２ｃの温度より徐々に低くなる温度勾配を有する低温領域とされている。よって、第１下流部２ｄの内部のガス流路Ｒ２は高温領域とされ、第２下流部２ｅの内部のガス流路Ｒ３は低温領域とされる。 Thus, by providing the 1st-4th heating means 11a-11d, the temperature of the raw material part 2a, the intermediate part 2b, the growth part 2c, and the 1st downstream part 2d can be independently controlled. .
Here, an example of the temperature distribution in the crystal growth vessel 2 by the first to fourth heating means 11a to 11d is shown on the right side of the crystal growth vessel 2 in FIG. In this example, the temperature of the raw material part 2a is equal to or higher than the sublimation temperature of the raw material 5, the temperature of the intermediate part 2b is slightly higher than the temperature of the raw material part 2a, the temperature of the growth part 2c is lower than the temperature of the raw material part 2a, The temperature of 2d is a high temperature region equal to or higher than the temperature of the growth part 2c, and the second downstream part 2e gradually decreases toward the upper side (downstream side) and gradually lower than the temperature of the growth part 2c. The low temperature region has a temperature gradient. Therefore, the gas flow path R2 inside the first downstream portion 2d is a high temperature region, and the gas flow path R3 inside the second downstream portion 2e is a low temperature region.

本実施形態の単結晶製造装置１は、結晶成長容器２内をこのような温度分布とすると、原料５を昇華させて昇華ガスを発生させることができ、この昇華ガスを円筒部８ｂに沿って上方に導き種結晶６に接触させ、この昇華ガスの少なくとも一部を種結晶６上で凝縮することによって、窒化アルミニウム単結晶７を結晶成長できる。
一方、種結晶６上で結晶成長に供されなった余剰の昇華ガスと結晶成長に利用された使用済みガスの混合ガスは、窒化アルミニウム単結晶７と種結晶６の周囲の空間である第１のガス流路Ｒ１を通過して上方に流れ、第１下流部２ｄの第２ガス流路Ｒ２に移行する。ここで、第１下流部２ｄの温度は成長部２ｃの温度と同等か若干高い温度であるため、混合ガスの大部分はガス状態を維持しつつ上方に流れ、第２下流部２ｅの第３のガス流路Ｒ３に移行する。
第３のガス流路Ｒ３では、上方に向かって温度が徐々に下降して成長部２ｃの温度より低温の領域となるため、第３のガス流路Ｒ３に移行しようとする混合ガスにより拡径部２２の下流端側（上端側）と大径部２３の内壁面に窒化アルミニウム多結晶体が堆積する。混合ガスからの窒化アルミニウム多結晶体の析出は混合ガスの流速が低下し温度が下がることで、混合ガス中に含まれている過飽和になった窒化アルミニウムが多結晶体として析出することによるので、拡径部２２の下流端側から大径部２３側にかけて主に析出がなされる。更に、窒化アルミニウムの多結晶体が主に析出する拡径部２２の下流端側から大径部２３側は、ガス排出口１０よりも流路断面積が大きいので、これらの領域に窒化アルミニウムの多結晶体が多少析出しても、ガス流路Ｒ２、Ｒ３のガスの流れに影響は生じない。
また、ガス排出口１０は成長部２ｃと距離が離れており、このガス排出口１０に至る間に混合ガスの温度は十分に降下されているので、ガス排出口１０とその近傍において窒化アルミニウム多結晶体が析出するおそれは少ない。
このため、結晶成長を長時間行った場合であっても、ガス排出口１０を窒化アルミニウム多結晶体などの析出物によって狭小化もしくは閉塞することを回避できる。これにより、長時間単結晶成長を行っても結晶成長容器２内の圧力制御を正確に行うことができ、種結晶６上で良質な窒化アルミニウム単結晶を連続成長させることができる。 The single crystal manufacturing apparatus 1 of the present embodiment can generate a sublimation gas by sublimating the raw material 5 along the cylindrical portion 8b when the temperature inside the crystal growth vessel 2 is such a temperature distribution. The aluminum nitride single crystal 7 can be grown by guiding it upward and bringing it into contact with the seed crystal 6 and condensing at least a part of the sublimation gas on the seed crystal 6.
On the other hand, the mixed gas of the surplus sublimation gas used for crystal growth on the seed crystal 6 and the used gas used for crystal growth is a first space that is a space around the aluminum nitride single crystal 7 and the seed crystal 6. Passes through the gas flow path R1 and flows upward, and moves to the second gas flow path R2 of the first downstream portion 2d. Here, since the temperature of the first downstream portion 2d is equal to or slightly higher than the temperature of the growth portion 2c, most of the mixed gas flows upward while maintaining the gas state, and the third downstream portion 2e has a third temperature. To the gas flow path R3.
In the third gas flow path R3, the temperature gradually decreases upward and becomes a region lower than the temperature of the growth portion 2c, so that the diameter of the gas is expanded by the mixed gas that is going to move to the third gas flow path R3. An aluminum nitride polycrystal is deposited on the downstream end side (upper end side) of the portion 22 and the inner wall surface of the large diameter portion 23. The precipitation of aluminum nitride polycrystals from the mixed gas is due to the fact that the supersaturated aluminum nitride contained in the mixed gas precipitates as a polycrystal because the flow rate of the mixed gas decreases and the temperature decreases. Precipitation is mainly performed from the downstream end side of the enlarged diameter portion 22 to the larger diameter portion 23 side. Furthermore, since the flow passage cross-sectional area is larger than the gas discharge port 10 from the downstream end side to the large diameter portion 23 side where the polycrystalline body of aluminum nitride mainly precipitates, the aluminum nitride is formed in these regions. Even if the polycrystalline body is precipitated to some extent, the gas flow in the gas flow paths R2 and R3 is not affected.
Further, since the gas discharge port 10 is separated from the growth portion 2c, and the temperature of the mixed gas is sufficiently lowered while reaching the gas discharge port 10, a large amount of aluminum nitride is formed in the gas discharge port 10 and the vicinity thereof. There is little possibility that a crystal precipitates.
For this reason, even when the crystal growth is performed for a long time, it is possible to avoid narrowing or closing the gas discharge port 10 with precipitates such as aluminum nitride polycrystal. Thereby, even if single crystal growth is performed for a long time, the pressure in the crystal growth vessel 2 can be accurately controlled, and a good quality aluminum nitride single crystal can be continuously grown on the seed crystal 6.

本実施形態において、大径部２３の内径を結晶成長容器２の他の部分の内径よりも大きくしていることにより、原料５から上昇してくる昇華ガスの流速が第２下流部２ｅで低下し、第２下流部２ｅでは昇華ガスの過飽和度が高くなる。このため、大径部２３の内壁面に、昇華ガスが窒化アルミニウム多結晶体として析出し、その分、ガス排出口１０での窒化アルミニウム多結晶の析出量を低減できる。一方、大径部２３の内径が大きいので、第１のガス流路Ｒ１よりも第３のガス流路Ｒ３の横断面積が大きく、長時間の運転により窒化アルミニウム多結晶体が多量に析出したとしても大径部２３において十分に広いガス流路を確保でき、ガスの流れは阻害されないので結晶成長条件への悪影響は生じない。また、仮に、拡径部２２の下流端側に窒化アルミニウム多結晶の析出がなされたとしても、拡開部２２の下流端側は大径部２３と同等かそれに近い大きな内径を有しているので、長時間の運転により窒化アルミニウム多結晶が多量に析出したとしても拡径部２２において十分に広いガス流路を確保でき、ガスの流れは阻害されないので結晶成長条件への悪影響は生じない。 In the present embodiment, the flow velocity of the sublimation gas rising from the raw material 5 is reduced at the second downstream portion 2e by making the inner diameter of the large diameter portion 23 larger than the inner diameter of the other portion of the crystal growth vessel 2. However, the supersaturation degree of the sublimation gas becomes high in the second downstream portion 2e. For this reason, the sublimation gas is precipitated as an aluminum nitride polycrystal on the inner wall surface of the large diameter portion 23, and the amount of aluminum nitride polycrystal deposited at the gas discharge port 10 can be reduced accordingly. On the other hand, since the inner diameter of the large-diameter portion 23 is large, the cross-sectional area of the third gas flow path R3 is larger than that of the first gas flow path R1, and a large amount of aluminum nitride polycrystal is precipitated over a long period of operation. However, a sufficiently wide gas flow path can be secured in the large-diameter portion 23, and the gas flow is not hindered, so there is no adverse effect on the crystal growth conditions. Further, even if aluminum nitride polycrystal is deposited on the downstream end side of the enlarged diameter portion 22, the downstream end side of the expanded portion 22 has a large inner diameter that is equal to or close to the large diameter portion 23. Therefore, even if a large amount of aluminum nitride polycrystal is precipitated by long-time operation, a sufficiently wide gas flow path can be secured in the enlarged diameter portion 22 and the gas flow is not hindered, so that there is no adverse effect on crystal growth conditions.

次に、上述の単結晶製造装置１を用いた窒化アルミニウム単結晶７の製造方法について更に説明する。
原料５を原料容器３内にセットし、種結晶６を種結晶支持部材４に配した後、種結晶支持部材４を移動駆動機構によって移動操作し、種結晶６を成長部２ｃの位置に調整した後、回転駆動機構によって種結晶６を回転させる。
次に、結晶成長容器２内を真空排気した後、ガス導入口９を介し窒素ガスなどのプロセスガスを結晶成長容器２内に導入して、圧力を調整する。ここでの圧力は一例として１〜１０００Ｔｏｒｒ、より好ましくは１０〜５００Ｔｏｒｒに設定できる。 Next, the manufacturing method of the aluminum nitride single crystal 7 using the above-described single crystal manufacturing apparatus 1 will be further described.
After the raw material 5 is set in the raw material container 3 and the seed crystal 6 is arranged on the seed crystal support member 4, the seed crystal support member 4 is moved by a movement drive mechanism, and the seed crystal 6 is adjusted to the position of the growth part 2c. After that, the seed crystal 6 is rotated by the rotation drive mechanism.
Next, after evacuating the inside of the crystal growth vessel 2, a process gas such as nitrogen gas is introduced into the crystal growth vessel 2 through the gas inlet 9 to adjust the pressure. The pressure here can be set to 1 to 1000 Torr, more preferably 10 to 500 Torr as an example.

そして、図１の右側に示す温度分布となるように加熱手段１１ａ〜１１ｄを制御する。
ここで、原料部２ａの温度は１７５０〜２４５０℃、より好ましくは１８００〜２４００℃に設定することができ、中間部２ｂの温度は１７５０〜２５００℃、より好ましくは１８００〜２４５０℃に設定することができ、成長部２ｃの温度は１７００〜２４００℃、より好ましくは１７５０〜２３５０℃に設定することができる。さらに、結晶成長容器２内の中間部２ｂと成長部２ｃの温度差は、１０〜３００℃の範囲とすることが好ましく、５０〜２５０℃の範囲とすることがより好ましい。中間部２ｂと成長部２ｃの温度差を前記範囲とすることにより、成長部２ｃにおいて急激に温度が低下するため、原料部２ａで加熱され分解気化された成分を良好な成長速度で種結晶上に結晶成長させることが可能となる。
また、第１下流部２ｄの温度は、１７５０℃〜２４５０℃に、より好ましくは１７５０℃〜２４００℃に設定することができる。 And the heating means 11a-11d are controlled so that it may become the temperature distribution shown on the right side of FIG.
Here, the temperature of the raw material portion 2a can be set to 1750 to 2450 ° C, more preferably 1800 to 2400 ° C, and the temperature of the intermediate portion 2b is set to 1750 to 2500 ° C, more preferably 1800 to 2450 ° C. The temperature of the growth part 2c can be set to 1700 to 2400 ° C, more preferably 1750 to 2350 ° C. Furthermore, the temperature difference between the intermediate part 2b and the growth part 2c in the crystal growth vessel 2 is preferably in the range of 10 to 300 ° C, more preferably in the range of 50 to 250 ° C. By setting the temperature difference between the intermediate portion 2b and the growth portion 2c within the above range, the temperature rapidly decreases in the growth portion 2c, so that the components heated and decomposed and vaporized in the raw material portion 2a can be deposited on the seed crystal at a good growth rate. It is possible to grow crystals.
Moreover, the temperature of the 1st downstream part 2d can be set to 1750 to 2450 degreeC, More preferably, it can be set to 1750 to 2400 degreeC.

以上の温度分布により、第１下流部２ｄの下流側と第２下流部２ｅに窒化アルミニウム多結晶体を堆積させ、成長部２ｃと第１下流部２ｄの上流側に窒化アルミニウム多結晶の堆積を防止し、成長部２ｃにおける窒化アルミニウム単結晶７の結晶成長条件を乱すことなく結晶成長できる効果がある。なお、種結晶６の下に成長した窒化アルミニウム単結晶７は徐々に成長して大きくなるので、成長した窒化アルミニウム単結晶７の先端が成長部２ｃに位置するように種結晶保持部材４を図１の矢印方向（上方）に徐々に移動させながら窒化アルミニウム単結晶７を成長させることとする。種結晶保持部材４が徐々に上昇するので種結晶６の上に堆積した窒化アルミニウム単結晶７の先端位置が結晶成長位置に相当する。
結晶成長容器２内の原料部２ａ、中間部２ｂ、成長部２ｃ、第１下流部２ｄおよび第２下流部２ｅの温度制御は、結晶成長容器２の各部分の外壁の温度を図示しない放射温度計で測定しながら加熱手段１１ａ〜１１ｄの個々の出力を調整することにより行うことができる。
以上、本発明の単結晶製造装置および単結晶の製造方法について説明したが、上記実施形態において、単結晶製造装置を構成する各部、単結晶の製造方法の各工程は一例であって、本発明の範囲を逸脱しない範囲で適宜変更することが可能である。 With the above temperature distribution, the polycrystalline aluminum nitride is deposited on the downstream side of the first downstream portion 2d and the second downstream portion 2e, and the polycrystalline aluminum nitride is deposited on the upstream side of the growth portion 2c and the first downstream portion 2d. This has the effect of preventing the crystal growth without disturbing the crystal growth conditions of the aluminum nitride single crystal 7 in the growth portion 2c. Since the aluminum nitride single crystal 7 grown under the seed crystal 6 grows and grows gradually, the seed crystal holding member 4 is illustrated so that the tip of the grown aluminum nitride single crystal 7 is located in the growth portion 2c. The aluminum nitride single crystal 7 is grown while gradually moving in the direction of the arrow 1 (upward). Since the seed crystal holding member 4 gradually rises, the tip position of the aluminum nitride single crystal 7 deposited on the seed crystal 6 corresponds to the crystal growth position.
The temperature control of the raw material portion 2a, the intermediate portion 2b, the growth portion 2c, the first downstream portion 2d and the second downstream portion 2e in the crystal growth vessel 2 is performed by adjusting the temperature of the outer wall of each part of the crystal growth vessel 2 to an unillustrated radiation temperature. This can be done by adjusting the individual outputs of the heating means 11a to 11d while measuring with a meter.
The single crystal manufacturing apparatus and the single crystal manufacturing method of the present invention have been described above. However, in the above embodiment, each part constituting the single crystal manufacturing apparatus and each process of the single crystal manufacturing method are examples, and the present invention It is possible to make appropriate changes without departing from the above range.

以下、実施例を示して本発明をさらに詳細に説明するが、本発明は以下の実施例に限定されるものではない。
（実施例１〜４）
図１に示す単結晶製造装置を用いて、窒化アルミニウム単結晶を製造した。原料５として窒化アルミニウム粉末を使用し、種結晶６として窒化アルミニウム単結晶を使用した。また、ガス導入口９からプロセスガスとして窒素ガスを導入した。単結晶製造装置において、種結晶の外径は５０．８ｍｍ、小径部の外径は１５０ｍｍ、大径部の外径は２５０ｍｍであり、ガス排出口の位置は種結晶の位置から５００ｍｍ上方の位置に設けた。
なお、結晶成長条件は、以下の通りであり、第１下流部の温度は表１に示すように変化させた。結晶成長容器内圧力：１５０Ｔｏｒｒ、結晶成長時間：３００時間、窒素ガス流量：１０００ｓｃｃｍ、原料部温度：２２００℃、中間部温度：２２５０℃、成長部温度：２１００℃。 EXAMPLES Hereinafter, although an Example is shown and this invention is demonstrated further in detail, this invention is not limited to a following example.
(Examples 1-4)
An aluminum nitride single crystal was manufactured using the single crystal manufacturing apparatus shown in FIG. Aluminum nitride powder was used as the raw material 5, and aluminum nitride single crystal was used as the seed crystal 6. Further, nitrogen gas was introduced as a process gas from the gas inlet 9. In the single crystal manufacturing apparatus, the outer diameter of the seed crystal is 50.8 mm, the outer diameter of the small diameter portion is 150 mm, the outer diameter of the large diameter portion is 250 mm, and the position of the gas outlet is a position 500 mm above the position of the seed crystal. Provided.
The crystal growth conditions were as follows, and the temperature of the first downstream portion was changed as shown in Table 1. Crystal growth vessel internal pressure: 150 Torr, crystal growth time: 300 hours, nitrogen gas flow rate: 1000 sccm, raw material part temperature: 2200 ° C., intermediate part temperature: 2250 ° C., growth part temperature: 2100 ° C.

（比較例１）
図２に示す単結晶製造装置（従来の単結晶製造装置）を用いて、窒化アルミニウム単結晶を製造した。原料および種結晶は、前記実施例１と同様のものを使用した。図２に示す単結晶製造装置において、加熱炉本体の外径は２００ｍｍ、種結晶の外径は５０．８ｍｍ、加熱炉本体の天井部の外周部に直径１２．７ｍｍのガス排出口を設けた構造とした。 (Comparative Example 1)
An aluminum nitride single crystal was manufactured using the single crystal manufacturing apparatus (conventional single crystal manufacturing apparatus) shown in FIG. The same raw materials and seed crystals as those used in Example 1 were used. In the single crystal manufacturing apparatus shown in FIG. 2, the outer diameter of the heating furnace body is 200 mm, the outer diameter of the seed crystal is 50.8 mm, and a gas discharge port having a diameter of 12.7 mm is provided on the outer periphery of the ceiling part of the heating furnace body. The structure.

（評価）
各実施例および各比較例について、得られた窒化アルミニウム単結晶のＸ線回折によるＡｌＮ（０００２）回折のロッキングカーブ半値幅（ＦＷＨＭ）、およびガス排出口等における析出物の発生状況を調べた。その結果を表１に示す。なお、析出物の発生状況において、特に問題のないレベルである場合は「−」で表示した。 (Evaluation)
About each Example and each comparative example, the rocking curve half value width (FWHM) of the AlN (0002) diffraction by X-ray diffraction of the obtained aluminum nitride single crystal, and the generation | occurrence | production condition of the deposit in a gas exhaust port etc. were investigated. The results are shown in Table 1. In addition, in the generation | occurrence | production state of the precipitate, when it was a level with no problem in particular, it displayed by "-".

各実施例では、ガス排出口および成長部直上（拡径部の内壁面や種結晶支持部材の周面）での窒化アルミニウム多結晶の堆積を抑制することができ、長時間安定して連続運転することができた。このため、表１のＦＷＨＭの値からわかるように、得られた窒化アルミニウム単結晶は、いずれも良好な結晶性を有していた。
これらに対して、種結晶とガス排出口との間に内部空間を形成していない結晶成長装置を用いて結晶成長させた比較例１では、ガス排出口近傍で多結晶堆積が顕著に認められ、ガスの流通経路が狭くなることで結晶成長条件が変化してしまった。このため、得られた窒化アルミニウム単結晶は、表１のＦＷＨＭの値から判断できるように結晶性の低いものであった。 In each embodiment, deposition of aluminum nitride polycrystals on the gas outlet and directly above the growth part (inner wall surface of the enlarged diameter part and the peripheral surface of the seed crystal support member) can be suppressed, and the operation can be performed stably for a long time. We were able to. For this reason, as can be seen from the FWHM values in Table 1, all of the obtained aluminum nitride single crystals had good crystallinity.
In contrast, in Comparative Example 1 in which crystal growth was performed using a crystal growth apparatus in which no internal space was formed between the seed crystal and the gas discharge port, polycrystalline deposition was remarkably observed in the vicinity of the gas discharge port. The crystal growth conditions have changed due to the narrow gas flow path. For this reason, the obtained aluminum nitride single crystal had low crystallinity as can be judged from the FWHM values in Table 1.

本発明により得られる単結晶は、深紫外〜青色の発光ダイオードおよびレーザーダイオード等の形成に用いられる成長基板や、高耐圧パワーデバイス、高周波電子デバイス等の基板に利用することができる。 The single crystal obtained by the present invention can be used for growth substrates used for forming deep ultraviolet to blue light emitting diodes, laser diodes, and the like, and substrates for high voltage power devices, high frequency electronic devices and the like.

１…単結晶製造装置、２…結晶成長容器、２１…小径部、２２…拡径部、２３…大径部、２ａ…原料部、２ｂ…中間部、２ｃ…成長部、２ｄ…第1下流部（空間）、２ｅ…第２下流部（空間）、３…原料容器、４…種結晶保持部材、５…原料、６…種結晶、６…窒化アルミニウム単結晶（単結晶）、９…ガス導入口、１０…ガス排出口、１１ａ…第1加熱手段（加熱手段）、１１ｂ…第２加熱手段（加熱手段）、１１ｃ…第３加熱手段（加熱手段）、１１ｄ…第４加熱手段（加熱手段）、Ｒ１…第一のガス流路、Ｒ２…第２のガス流路、Ｒ３…第３のガス流路。 DESCRIPTION OF SYMBOLS 1 ... Single crystal manufacturing apparatus, 2 ... Crystal growth container, 21 ... Small diameter part, 22 ... Large diameter part, 23 ... Large diameter part, 2a ... Raw material part, 2b ... Middle part, 2c ... Growth part, 2d ... 1st downstream Part (space), 2e ... 2nd downstream part (space), 3 ... Raw material container, 4 ... Seed crystal holding member, 5 ... Raw material, 6 ... Seed crystal, 6 ... Aluminum nitride single crystal (single crystal), 9 ... Gas Inlet 10, gas outlet 11 a first heating means (heating means) 11 b second heating means (heating means) 11 c third heating means (heating means) 11 d fourth heating means (heating) Means), R1... First gas flow path, R2... Second gas flow path, R3.

Claims

A crystal growth container, a raw material container disposed at an inner bottom of the crystal growth container, a seed crystal supported above the raw material container in the crystal growth container so as to face the raw material container, and the crystal A gas introduction port provided below the crystal growth position of the growth vessel, a gas discharge port provided above the crystal growth location of the crystal growth vessel, and heating provided on the outer periphery of the crystal growth vessel Means and
The raw material contained in the raw material container is heated to generate a sublimation gas, the sublimation gas is condensed on the seed crystal to grow a single crystal, and the gas that has passed through the seed crystal is passed through the gas outlet. A single crystal production apparatus for discharging from
The crystal growth vessel is provided with a gas flow path that is larger than a cross-sectional area of the gas discharge port and includes the seed crystal and reaches the gas discharge port side, and the crystal is grown on the seed crystal in the gas flow path. An apparatus for producing a single crystal, characterized in that a low temperature region is provided in a gas flow path downstream of the position at a temperature lower than the temperature at the crystal growth position during crystal growth.

A high temperature region that is equal to or higher than the temperature of the crystal growth position at the time of crystal growth is provided in a region near the crystal growth position downstream of the crystal growth position in the gas flow path. A low temperature region that is lower than the temperature of the crystal growth position during crystal growth is provided in a region farther from the crystal growth position downstream of the crystal growth position in the gas flow path. The single crystal manufacturing apparatus according to claim 1.

3. The gas flow path according to claim 1, wherein a region in which the cross-sectional area is gradually increased toward the downstream side is provided downstream of the crystal growth position in the gas flow path. Single crystal manufacturing equipment.

A method for producing a single crystal based on a seed crystal using the single crystal production apparatus according to any one of claims 1 to 3, wherein a gas flow path downstream of a crystal growth position is heated. Generating a high-temperature region at a temperature equal to or higher than the temperature of the crystal growth position, and performing crystal growth while preventing the precipitation of polycrystals around the gas flow path in the high-temperature region. A method for producing a single crystal.