JP3614282B2 - Pyrolytic boron nitride container and manufacturing method thereof - Google Patents

Description

【００４４】
これは物質としての吸光係数が１．２と２．２であるＰＢＮの表面を、ＣＶＤ反応で析出させたままのもの（アズデポ）、＃３２０の粗いＡｌ_２ Ｏ_３ ペーパーで磨いたもの、＃１２００の細かいＡｌ_２ Ｏ_３ ペーパーで磨いたものとで、みかけ上の光の透過率、吸光係数がどのように変わるかを示したものである。
【００４５】
表１から明らかなように、アズデポでは物質固有の吸光係数と、みかけの吸光係数との差が小さく、その表面における光の散乱は余り起こっていないものと思われる。一方、表面を粗い＃３２０のペーパーで磨いたものは、その表面が粗いために光の散乱量が多く、みかけの吸光係数が著しく大きくなり、透過率が下がる。また、表面を＃１２００のペーパーで磨いたものは、その表面が＃３２０のものより細かくなるので、光の散乱量が減少し、みかけの吸光係数が下がり、透過率が上がっている。
【００４６】
このように表面粗さを調整することにより、透過率を変化させることができることから、例えば熱分解窒化ホウ素容器の外表面の開口部側を＃３２０のぺーパーで磨き、底部側はアズデポのままとし、その中間は＃１２００のペーパーで磨けば、容器の外表面は開口部側で粗く、底部側できめ細かいものとなり、その透過率の分布としては、底部側からその反対側である開口部側に向けて、段階的にまたは漸次に小さくなるものとすることができる。
【００４７】
（３）ＰＢＮに元素をドープする方法
これはＣＶＤ反応によりＰＢＮを蒸着する場合に、ドープガスを導入し、ＰＢＮに所望元素をドープすることによって、簡単かつ確実にＰＢＮ容器に透過率または反射率分布を付けることができる方法である。
【００４８】
この場合、ドープする元素としては、ＰＢＮのＩＲ透過率または反射率を変更することができるものであれば原則としてどれを用いてもよいが、ドープガスにより簡単にドープすることが可能である等の点から、Ｂ，Ｎ，Ｓｉ，Ｃ，Ａｌから選択される１以上の元素とすればよい。
そして、ＣＶＤ反応により心金上にＰＢＮを蒸着する際に、ドープガスとして例えば、ＢＦ_３ ，Ｎ_２ Ｈ_４ ，ＳｉＣｌ_４ ，ＣＨ_４ ，Ａｌ（ＣＨ_３ ）_３ 等のドープ元素を含むガスを導入することによって、ＰＢＮ中にこれらの元素をドープしたドープ層を形成することができる。
【００４９】
このドープ層は、ＰＢＮ容器のどの位置に形成することも可能であり、例えば容器内表面に形成してもよいが、内表面に形成すると容器内に収容される原料融液を汚染する恐れがあるため、容器内表面にドープ層が露出しないようにするのが良い。したがって、容器の外表面で形成するか、またはＰＢＮ中で形成されるようにすれば、原料融液がこれらの元素によって汚染される心配もなくなる。
【００５０】
そして、このドープ層の厚さ、面積、ドープ濃度を調整することによって、ＰＢＮ容器の２６００ｃｍ^−１〜６５００ｃｍ^−１の光の透過率または反射率の分布を自在にコントロールすることができる。
例えば、ＰＢＮ容器の開口部側は厚くあるいはドープ濃度を濃く、形成面積を広くし、底部側は薄く、形成面積を狭く、あるいは形成しないものとすれば、光の透過率または反射率を底部側から開口部側に向けて、段階的にまたは漸次に変更することができる。
【００５１】
このドープ層の厚さを制御するには、例えばＣＶＤ反応中にドープガスを導入する時間を調整すれば良いし、ドープ濃度の制御は、導入されるガス中のドープガスの濃度を調整することによって簡単に行うことができる。また、ドープ層の厚さや面積に分布をつけるには、ドープ反応終了後ドープ層を機械的に研磨する等の操作によって簡単に行うことができる。
【００５２】
【発明の実施の形態】
次に、本発明の実施の形態を実施例により説明するが、本発明はこれらに限定されるものではない。
【００５３】
【実施例】
以下、本発明の実施例および比較例を示す。
（実施例１、比較例１）
黒鉛製円筒型ＣＶＤ反応炉内に、グラファイト製の心金を、実施例１ではＭＢＥ法による容器の開口部側の密度が高くなるように、容器の開口部側が低圧力側とし、底部側が原料ガス供給側となるように配置し（図１（Ａ））、比較例１では容器全体が均一な密度分布となるように、すなわち容器の側部が原料ガス供給側となるように配置した（図１（Ｂ））上、これを回転させながらＰＢＮの析出を行うこととした。
【００５４】
これに三塩化ホウ素２Ｌ／ｍｉｎ，アンモニア５Ｌ／ｍｉｎを供給し、炉の中心における平均圧力２Ｔｏｒｒ（２×１３３．３２２４Ｐａ）、１８５０℃の条件で反応させて、厚さが０．８〜１．３ｍｍで直径２０ｍｍ、高さ１５０ｍｍの開口部に鍔を有するＭＢＥ法用ＰＢＮ容器を製造した。この時、ＣＶＤ反応炉の原料ガス供給側は、約４Ｔｏｒｒ（４×１３３．３２２４Ｐａ），排気側は約２Ｔｏｒｒ（２×１３３．３２２４Ｐａ）であった。反応終了後、ＰＢＮと心金を分離し、その後加工を施し最終形状のＰＢＮ容器を作製した。
【００５５】
こうして得られたＰＢＮ容器の底部側、容器中央部、および開口部側の２６００ｃｍ^−１〜６５００ｃｍ^−１における吸光量ＡをＩＲスペクトルメータ（ＦＴＩＲ−７１０ ＮＩＣＯＬＥＴ社製）で測定し、下記の（２）（３）（４）式から、それぞれ４８００ｃｍ^−１の吸光係数Ｂを求めたところ、表２に示した通りの結果が得られた。
吸光量（Ａ）＝Ｌｏｇ_１０（Ｉ_ｏ ／Ｉ） ・・・（２）
（ここで、Ｉ_ｏ は入射光、Ｉは透過光である。）
吸光係数（Ｂ）＝Ａ／ｔ ・・・・（３）
（ここで、ｔは厚さである。）
透過率（Ｔ）＝Ｉ／Ｉ_ｏ ・・・・（４）
【００５６】
【表２】

【００５７】
表２の結果を見れば明らかなように、実施例１の容器では、底部側の吸光係数が小さく、逆に開口部側では吸光係数が大きいことから、この容器をＭＢＥ法に用いれば、開口部側でより輻射光が吸収されるために、容器上部の温度が低下せず、この部分での原料の付着、あるいは原料の這い上がり現象を効果的に抑制することが期待されるのに対し、比較例１の容器では、容器全体の吸光係数が均一であるので、原料のない容器上部の温度が低下し、この部分への原料の付着、這い上がり現象が激しいものとなる。
【００５８】
（実施例２）
次に、上記比較例１と同様な方法で、容器全体の吸光係数、透過率の均一な容器を作製した。この場合、炉内の平均圧力を４Ｔｏｒｒ（４×１３３．３２２４Ｐａ）とし、全体の吸光係数が下がるようにした。こうしてできたＰＢＮ容器の各部の４８００ｃｍ^-1の光の吸光係数、透過率を予め測定しておいた。
【００５９】
次に、図２のように、このＰＢＮ容器の開口部側の外表面を＃３２０、中央部約５ｃｍを＃１２００のアルミナサンドペーパーで表面処理を行い、底部側はアズデポのままとした。こうして表面処理したＰＢＮ容器の各部の４８００ｃｍ^−１の光の透過率を再度測定し、これらの結果を表３に示した。
【００６０】
【表３】

【００６１】
表３の結果を見れば明らかなように、表面処理を施した実施例２の容器では、開口部側の表面が粗いために光がその表面で散乱し透過率が小さくなるのに対し、逆に底部側ではアズデポのままであるために光の透過率が高く、この容器をＭＢＥ法に用いれば、開口部側で輻射熱が透過しにくいために、容器内に理想的な温度勾配を形成し、容器上部での原料の付着、這い上がり現象を有効に防止することが期待される。
【００６２】
（実施例３）
次に、上記比較例１と同様な方法で、容器全体の吸光係数、透過率の均一な容器を作製した。この場合、炉内の平均圧力を４Ｔｏｒｒ（４×１３３．３２２４Ｐａ）とし、全体の吸光係数が下がるようにした。こうしてできたＰＢＮ容器の各部の４８００ｃｍ^-1の光の吸光係数、透過率を予め測定しておいた。
【００６３】
次に、このＰＢＮ容器を再びＣＶＤ炉にセットし、１Ｔｏｒｒ（１３３．３２２４Ｐａ）の減圧下、１６００℃に昇温し、これにメタンガスを５ＳＬＭ、三塩化ホウ素２Ｌ／ｍｉｎ、アンモニア５Ｌ／ｍｉｎで供給し、ＰＢＮにカーボンをドープしたドープ層を形成した。これを冷却後取り出し、図３のように、底部側約半分はすべて機械的研磨によりドープ層を除去し、開口部側の半分はそのままカーボンドープ層を残した。さらにこの表面処理を行ったＰＢＮ容器を再びＣＶＤ炉にセットし、その最表面に約１００μｍのＰＢＮ層を析出させ、前記ドープ層を埋め込んだ。
こうしてカーボンドープ層を形成したＰＢＮ容器の４８００ｃｍ^-1の光の透過率を再度測定し、これらの結果を表４に示した。
【００６４】
【表４】

【００６５】
表４の結果を見れば明らかなように、カーボンをドープした実施例３の容器では、開口部側ではカーボン元素が光を吸収するためにその透過率が非常に小さくなるのに対し、逆に底部側ではドープ層がなく、ＰＢＮはアズデポのままであるために光の透過率が高い。したがって、この容器をＭＢＥ法に用いれば、開口部側でより輻射光が吸収されるために、容器上部の温度が低下せず、この部分での原料の付着、あるいは原料の這い上がり現象を効果的に抑制することが期待される。
【００６６】
なお、本実施例においては、透過率の測定等のため、ＣＶＤ反応を中断し一旦生成容器を取り出した後、さらにドープ層を形成したが、通常は連続してＣＶＤ反応をし、所望時にドープガスを導入すればよい。
【００６７】
（比較例２）
上記比較例１と同様にしてＰＢＮ容器を作製した後、再びＣＶＤ炉にセットし、１Ｔｏｒｒ（１３３．３２２４Ｐａ）の減圧下、１７５０℃に昇温し、これにメタンガスを５ＳＬＭで供給し、ＰＢＮの表面に５０μｍ厚のカーボン層を形成した。これを冷却後取り出し、底部外表面と内表面はすべて機械的研磨によりカーボン層を除去した。さらにこの表面処理を行ったＰＢＮ容器を再びＣＶＤ炉にセットし、その最表面に約１００μｍのＰＢＮ層を析出させ、前記カーボン層を埋め込んだ複合容器を作製した。
ところが、このものは冷却後複合した各層がはがれて破損してしまい、使用不能なものとなった。
【００６８】
次に、上記実施例１〜実施例３、比較例１で得られたＰＢＮ容器を使用し、実際にＭＢＥ法でＧａＡｌＡｓのエピタキシャル膜を育成してみた。
エピタキシャル膜の成長は、雰囲気圧力を１０^-10 Ｔｏｒｒ（１０ ^-10 ×１３３．３２２４Ｐａ）、加熱温度は１０００℃とし、各例ともＰＢＮ容器をＧａ充填用容器として用いた。
育成されたエピタキシャル膜の表面を光学顕微鏡により観察し、その表面欠陥密度を測定した。その結果を表５に示した。
【００６９】
【表５】

【００７０】
表５からわかるように、実施例のＰＢＮ容器を用いた場合には、育成されるエピタキシャル膜の表面欠陥密度が少なく、容器上部での原料付着が少ないために、付着原料が滴下して液滴が飛散するような問題が抑制されていることがわかる。
一方、比較例１のＰＢＮ容器を用いた場合は、容器上部の温度が低く、この部分での原料付着が激しいために、育成されるエピタキシャル膜の表面欠陥が多いものとなっている。
【００７１】
（実施例４）［反射率に分布をつけた容器］
黒鉛製円筒型のＣＶＤ反応炉内にグラファイト製の心金を設置して回転させ、ここに２Ｌ／ｍｉｎのＢＣｌ3 と５Ｌ／ｍｉｎのＮＨ3 を供給し、炉内の平均圧力を２Ｔｏｒｒ（２×１３３．３２２４Ｐａ）、１８５０℃の条件で１０時間反応を行ってＰＢＮ層を形成した後、上記原料ガスに５Ｌ／ｍｉｎのＣＨ4 を混合し、２０分間反応を行って、厚さ３０μｍのＰＢＮにカーボンをドープしたドープ層で被覆された厚さ１ｍｍ、直径２０ｍｍ、高さ１００ｍｍのＰＢＮ容器を製造した。さらに容器底部から６５ｍｍの範囲を機械的研磨によって除去し、開口部から３５ｍｍの範囲のみにカーボンドープ層を残した。
この容器について、カーボンドープ層の最外表面の波長２３００ｎｍ（１０００℃でのλmax ）、２０００ｎｍ（１２００℃でのλmax ）および１７００ｎｍ（１４００℃でのλmax ）の光の容器外表面反射率を測定した結果は夫々、１０％、１２％および８％であった。
【００７２】
（比較例３）
黒鉛製円筒型のＣＶＤ反応炉内にグラファイト製の心金を設置して回転させ、ここに２Ｌ／ｍｉｎのＢＣｌ3 と５Ｌ／ｍｉｎのＮＨ3 を供給し、炉内の平均圧力を２Ｔｏｒｒ（２×１３３．３２２４Ｐａ）、１８５０℃の条件で１０時間反応を行い、厚さ１ｍｍ、直径２０ｍｍ、高さ１００ｍｍのＰＢＮの単体容器を製造した。
この容器について、ＰＢＮ層の最外表面の波長２３００ｎｍ（１０００℃でのλmax ）、２０００ｎｍ（１２００℃でのλmax ）および１７００ｎｍ（１４００℃でのλmax ）の光の容器外表面反射率を測定した結果は夫々、６０％、５５％および４７％であった。
【００７３】
（比較例４）
比較例３で作製したＰＢＮ容器を再びＣＶＤ反応炉内に設置し、ここに５Ｌ／ｍｉｎのＣＨ4 を供給し、炉内の平均圧力を２Ｔｏｒｒ（２×１３３．３２２４Ｐａ）、１６５０℃の条件で３時間反応を行って、容器最表面に厚さ３０μｍの熱分解グラファイト（ＰＧ）の被覆層を析出させた。さらに容器底部から６５ｍｍの範囲のＰＧの被覆層を機械的研磨によって除去し、開口部から３５ｍｍの範囲のみＰＧの被覆層を残した。
この容器について、ＰＧ層の最外表面の波長２３００ｎｍ（１０００℃でのλmax ）、２０００ｎｍ（１２００℃でのλmax ）および１７００ｎｍ（１４００℃でのλmax ）の光の容器外表面反射率を測定した結果は夫々、６０％、６０％および４５％であった。
【００７４】
次に、実施例４、比較例３および比較例４によって得られたＰＢＮ容器にＡｌを入れ、これを１１００℃に加熱し、実際に分子線エピタキシャル法によって、ＧａＡｌＡｓのエピタキシャル膜を育成した結果を表６に示した。
【００７５】
表６からわかるように、実施例４のカーボンドープＰＢＮ容器を用いた場合には、容器内の温度勾配が理想的なものとなるため、開口部側でのＡｌのドロップ発生が少なく、ディフェクト密度の小さい極めて安定したエピタキシャル膜を育成することができた。
【００７６】
一方、比較例３と比較例４のＰＢＮ容器を用いた場合には、開口部付近でのドロップ発生が激しく、表６に示したように、ディフェクトの多い結果となった。また、容器表面でヒーターからの輻射光が反射され易いため、ヒーターの消費電力も実施例４のＰＢＮ容器を用いた場合よりも大きくなった。
【００７７】
【表６】

【００７８】
なお、本発明は、上記実施形態に限定されるものではない。上記実施形態は、例示であり、本発明の特許請求の範囲に記載された技術的思想と実質的に同一な構成を有し、同様な作用効果を奏するものは、いかなるものであっても本発明の技術的範囲に包含される。
【００７９】
例えば、上記説明では容器に透過率の分布をつける方法として、三つの方法を挙げ、それぞれ個別に説明したが、これらの方法は同時に実施してもよく、よりきめ細やかな透過率分布を形成することも可能である。
【００８０】
【発明の効果】
本発明によれば、分子線エピタキシャル法で用いられる熱分解窒化ホウ素容器の、２６００ｃｍ^−１〜６５００ｃｍ^−１の光の透過率または反射率に容器の高さ方向に変化する分布を付けたので、容器内の温度分布を理想的なものとし、容器上部への原料の付着、這い上がり現象を有効に防止出来る熱分解窒化ホウ素容器を、簡単かつ低コストで提供することができる。
従って、これを用いてＭＢＥ法によって、エピタキシャル膜の製造を行えば、表面欠陥の少ない良質のエピタキシャル膜を育成することが出来る。
【図面の簡単な説明】
【図１】ＣＶＤ反応によりＭＢＥ法のＰＢＮ容器を作製する場合の断面概略図である。
（Ａ） グラファイト製の心金を、容器の底部側が原料ガス供給側となるように配置した場合（実施例１）、
（Ｂ） グラファイト製の心金を、容器の側部が原料ガス供給側となるように配置した場合（比較例１、実施例２、実施例３、比較例２）。
【図２】開口部側を＃３２０、中央部約５ｃｍを＃１２００のアルミナサンドペーパーで表面処理を行い、底部側はアズデポのままとしたＰＢＮ容器の断面概略図である（実施例２）。
【図３】カーボンをドープしたＰＢＮ容器の断面概略図である（実施例３）。
【符号の説明】
１…ＣＶＤ炉、 ２…グラファイト製心金、
３…ＰＢＮ容器、 ４…カーボンドープ層。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a pyrolytic boron nitride container, and more particularly to a pyrolytic boron nitride container used for a container (molecular beam source container) that accommodates a molecular beam source in a molecular beam epitaxy (hereinafter abbreviated as MBE) method. It is.
[0002]
[Prior art]
The MBE method uses 10 thin film growth chambers.^-6-10^-11 Torr(10 ^-6 -10 ^-11 × 1333.3224Pa)By heating the container filled with the raw material to be a molecular beam source to, for example, 500 ° C. to 1600 ° C. and hitting the molecular beam generated from the molten raw material on the heated substrate, the atomic layer level It is a manufacturing method of the thin film which can control. In particular, it is widely used for the production of an epitaxial film of a compound semiconductor such as GaAs. The material of the molecular beam source container is chemical vapor deposition (hereinafter abbreviated as CVD) in terms of purity, heat resistance, strength, and the like. ) Pyrolytic boron nitride (PBN) by reaction is widely used.
[0003]
Conventionally, in such an MBE method, when operated for a long time, the raw metal crawls up along the inner wall surface of the container due to a capillary phenomenon or the like, leaks out of the container, and adheres to the heater or other heating member or furnace member. As a result, troubles such as corrosion, alteration, damage or short-circuiting of the heater occurred. In particular, the evaporated and scattered raw metal tends to adhere to the upper part of the inner wall of the low temperature container, and the material adhering to the upper part of the container crawls along the inner wall of the container over time and leaks directly out of the container. Or it may fall into the raw material melt and sprinkle the raw material droplets.
[0004]
If this happens, the life of these components will be shortened, resulting in increased costs and unstable operation, as well as scattered droplets flying to the substrate and forming defects in the epitaxial film. It will also be.
[0005]
In order to solve such problems, there has been proposed one in which a carbon film having a high infrared (IR) absorption rate is applied to the outer surface or inner surface of a pyrolytic boron nitride container and a radiation absorption layer is provided (special feature). (See Kaihei 2-204391, JP-B-7-2617). When the PBN composite container provided with this radiation light absorption layer is heated, radiation light from the heater is absorbed by this absorption layer, so that the efficiency of heating and the overall soaking can be improved. Therefore, it is possible to suppress the adhesion of the raw material metal at this portion.
[0006]
However, graphite and refractory metals are generally preferred as the radiation-absorbing layer, but these may be scattered in the furnace and mixed into the epitaxial film, and since these are conductive, the container There is also a risk of causing a short circuit when it comes into contact with a heater for heating.
[0007]
Furthermore, in order to solve this problem, proposals have also been made to coat pyrolytic boron nitride on the graphite light absorption layer (see Japanese Patent Application Laid-Open Nos. 5-105557 and 4-231459). However, in such a method, since a composite with a different material is used, the manufacturing process is long and the cost is high, and the composite film is peeled off during use.
[0008]
[Problems to be solved by the invention]
The present invention has been made in view of such problems, and even when operated for a long time, the raw material crawls up from the inner wall surface of the container, or can prevent the scattered raw material from adhering to the upper part of the container, Moreover, the main purpose is to provide a pyrolytic boron nitride container that can be used stably and at low cost, to stabilize the molecular beam epitaxy operation and to improve the quality of the epitaxial film.
[0009]
[Means for Solving the Problems]
In order to solve such problems, the present inventionIsIn a pyrolytic boron nitride container used as a molecular beam source container for molecular beam epitaxy, the wave number is 2600 cm.^-1~ 6500cm^-1The pyrolytic boron nitride container is characterized by having a distribution in which the transmittance of light changes in the height direction of the container.
[0010]
Thus, by providing a distribution in the IR transmittance of a pyrolytic boron nitride container used as a molecular beam source container for molecular beam epitaxy, the temperature distribution of the container can be controlled to a desired distribution, The creeping phenomenon and the adhesion of the raw material on the upper part of the container can be effectively suppressed.
[0011]
The transmittance distribution is a distribution that gradually or gradually decreases from the bottom side to the opening side of the container.,Or a distribution that increases stepwise or gradually from the bottom side to the opening side of the container,Can be.
[0012]
In this way, by providing a distribution of IR transmittance from the bottom side of the container toward the opening (in the height direction of the container), the temperature of the upper part of the container is increased, and the raw material adheres to this part. The creeping phenomenon can be suppressed. Also, depending on the type of raw material, the wettability with pyrolytic boron nitride is different, so lowering the temperature at the top of the container may suppress the creeping phenomenon. The rate may be increased.
[0013]
In the present invention, the wave number of the pyrolytic boron nitride container is 2600 cm.^-1~ 6500cm^-1The distribution of the light transmittance was changed by changing the extinction coefficient of pyrolytic boron nitride..
And as a manufacturing method of such a pyrolytic boron nitride container,,In a method for producing a pyrolytic boron nitride container used as a molecular beam source container for molecular beam epitaxy, wherein a product formed by CVD reaction is deposited on a graphite mandrel and then separated from the mandrel to obtain a molded body of the container. By changing the extinction coefficient of the pyrolytic boron nitride produced by placing the mandrel according to the pressure distribution in the CVD furnace,^-1~ 6500cm^-1The light transmittance may be given a distribution that changes in the height direction of the container.
[0014]
In this way, by changing the physical properties of pyrolytic boron nitride, if the distribution of transmittance is given, problems such as contamination by impurities and peeling of the composite film, as in the case of composite with other materials, are caused. In addition to being able to solve this problem, a high-quality pyrolytic boron nitride container can be produced with a simple and low-cost manufacturing process.
[0015]
In addition, the present inventionSaidThe pyrolytic boron nitride container is characterized in that a distribution is imparted to the light transmittance by changing the roughness of the outer surface of the pyrolytic boron nitride container.
And the present inventionIsBy distributing the roughness of the outer surface of the pyrolytic boron nitride container and adjusting the amount of light scattering on the surface, 2600 cm of the container^-1~ 6500cm^-1A method for producing a pyrolytic boron nitride container having a distribution in the light transmittance, wherein the light transmittance is distributed.
[0016]
As described above, a pyrolytic boron nitride container having a distribution in IR transmittance can be manufactured by distributing the roughness of the outer surface of the container and changing the amount of scattered radiation.
Also in this case, since the pyrolytic boron nitride container itself has an IR transmittance distribution, it is possible to solve the problems such as contamination by impurities and peeling of the composite film, as in the case of composite with other materials, and manufacturing. A high-quality pyrolytic boron nitride container can be produced with a simple process and low cost.
[0017]
Next, the present inventionSaidThe pyrolytic boron nitride container is characterized in that the pyrolytic boron nitride is doped with an element, and the thickness, area, and doping concentration of the doped layer are changed to give a distribution to the light transmittance. To do.
In addition, the present inventionIsIn the method for producing a pyrolytic boron nitride container, a product of the CVD reaction is vapor-deposited on a graphite mandrel and then separated from the mandrel, so that a dope gas is introduced into the furnace at least during the CVD reaction. A step of forming a doped layer in pyrolytic boron nitride by introducing, and adjusting the thickness, area, and concentration of the doped layer to 2600 cm of the container.^-1~ 6500cm^-1A method for producing a pyrolytic boron nitride container having a distribution in the light transmittance, wherein the light transmittance is distributed.
[0018]
Thus, a pyrolytic boron nitride container having a distribution in IR transmittance is also produced by forming a dope layer by introducing a dope gas and adjusting it when the pyrolytic boron nitride is generated by CVD reaction. can do.
In this case as well, IR transmittance distribution is imparted by changing the physical properties of pyrolytic boron nitride. Therefore, as in the case of compounding with other materials, there are problems such as contamination by impurities and peeling of the composite film. In addition to being able to solve this problem, a high-quality pyrolytic boron nitride container can be produced with a simple and low-cost manufacturing process.
[0019]
in this case,If the doped layer doped with the element is not exposed to the inner surface of the container, the raw material melt is not contaminated by the dopant.
And as an element doped to such pyrolytic boron nitride, what is necessary is just to set it as 1 or more selected from B, N, Si, C, and Al..
However, the doping elements that can be used in the present invention are not limited to these.
[0020]
Furthermore, the present inventionIsIn a pyrolytic boron nitride container used as a molecular beam source container for molecular beam epitaxy, the wave number is 2600 cm.^-1~ 6500cm^-1The pyrolytic boron nitride container is characterized by having a distribution in which the reflectance of light changes in the height direction of the container.
[0021]
In this way, since the distribution of the IR reflectance of the pyrolytic boron nitride container wall used as the molecular beam source container for molecular beam epitaxy can be controlled, the temperature distribution of the container can be controlled to a desired distribution. The creeping phenomenon and the adhesion of the raw material on the upper part of the container can be effectively suppressed.
[0022]
And the IR reflectance of the container wall is 25% or less on the entire outer surface of the container or partially.,A distribution in which the reflectance distribution decreases stepwise or gradually from the bottom side to the opening side of the container.,Or a distribution that increases stepwise or gradually from the bottom side to the opening side of the container,Can be.
[0023]
Thus, the IR reflectance of the container wall is set to 25% or less on the entire outer surface of the container or partially, and this reflectance distribution is directed from the bottom side of the container toward the opening side (the height of the container). In the vertical direction), by providing a reflectance distribution, the temperature of the upper part of the container can be increased, and the adhesion of the raw material to this portion or the creeping phenomenon can be suppressed. Also, depending on the type of raw material, the wettability with pyrolytic boron nitride is different, so lowering the temperature at the top of the container may suppress the creeping phenomenon, so the reflection on the opening side of the container The rate may be increased.
[0024]
Next, the present inventionSaidThe pyrolytic boron nitride container is characterized in that the pyrolytic boron nitride is doped with an element, and the thickness, area, and doping concentration of the doped layer are changed to give a distribution to the reflectance of the light. To do.
In addition, the present inventionIsIn the method for manufacturing a pyrolytic boron nitride container, in which a product of the CVD reaction is deposited on a graphite mandrel and then separated from the mandrel, a molded body of the container is obtained. A step of forming a doped layer in pyrolytic boron nitride by introducing, and adjusting the thickness, area, and concentration of the doped layer to 2600 cm of the container.^-1~ 6500cm^-1A method for producing a pyrolytic boron nitride container having a distribution in the light reflectance, wherein a distribution is imparted to the light reflectance.
[0025]
Thus, a pyrolytic boron nitride container having a distribution in IR reflectivity is produced by forming a dope layer by introducing a dope gas and adjusting it when the pyrolytic boron nitride is generated by CVD reaction. be able to.
In this case as well, IR reflectance distribution is imparted by changing the physical properties of pyrolytic boron nitride, so that there are problems such as contamination by impurities and peeling of the composite film as in the case of composite with other materials. In addition to being able to solve this problem, a high-quality pyrolytic boron nitride container can be produced with a simple and low-cost manufacturing process.
[0026]
Hereinafter, the present invention will be described in more detail, but the present invention is not limited thereto.
As a result of various investigations to suppress the creeping phenomenon of the raw material melt in the MBE method and the adhesion at the upper part of the container, the present inventors have found that the radiation transmittance or reflectance of the pyrolytic boron nitride container itself is The inventors have found that it is effective to attach a distribution, and completed the present invention. That is, according to the present invention, the radiation transmittance or reflectance of the pyrolytic boron nitride container is distributed in the height direction of the container, for example, the temperature on the bottom side is lowered, and the opening side that is the opposite side thereof. This creates a temperature distribution in which the temperature is high, and makes it possible to grow an epitaxial film by the MBE method in an ideal temperature environment.
[0027]
If the pyrolytic boron nitride container itself has a distribution of IR transmittance or reflectance, impurity contamination, heater short circuit, or composite film as in the case of coating the above-described composite film to form a PBN composite container In addition to solving the problem of peeling of the container, the manufacturing process of the container is simple, and the cost can be reduced.
[0028]
The present inventors first examined the wave number of radiation to be transmitted or reflected in an MBE container. The temperature range used to generate the beam source by the MBE method is about 500 to 1600 ° C., and more practically 800 to 1600 ° C. The maximum energy heat transfer wavelength λmax at this time is as follows: (1).
λmax = 2,898 (μm · K) / T (1)
(Where T is the absolute temperature)
Therefore, when λmax is obtained from the equation (1) for the above temperature region, it is 3750 nm to 1550 nm, more practically 2700 nm to 1550 nm, and 2600 cm when converted to wave number.^-1~ 6500cm^-1More practically 3700cm^-1~ 6500cm^-1Is obtained. Therefore, this 2600cm^-1~ 6500cm^-1By assigning a distribution to the light transmittance or reflectance, it is possible to control the temperature distribution of the raw material melt and each part of the container.
[0029]
For example, when a resistance heating method such as a tantalum heater arranged so as to surround the container as a heat source is used, heat is supplied from the outside of the container by radiant heat, and this radiation is the container. When permeated without being absorbed by pyrolytic boron nitride, only the bottom side of the container with the raw material is heated, and the temperature of the upper part of the container is lowered. Therefore, 2600cm of pyrolytic boron nitride container^-1~ 6500cm^-1If the light transmittance is distributed in a stepwise or gradually decreasing manner from the bottom side to the opening side on the opposite side, the opening side can be heated more efficiently and selectively. The temperature at the top of the container can be kept high, and the adhesion of the raw material metal at this portion can be suppressed.
[0030]
Pyrolytic boron nitride and pyrolytic graphite are 2600cm in wave number.^-1~ 6500cm^-1Since the reflectance of the radiation light is as high as 30 to 70%, most of the radiation light is reflected without being absorbed by the molecular beam source container wall, and only the bottom side of the container with the raw material is heated. And the temperature of the upper part of the container is lowered. Therefore, 2600 cm of the outer surface of the pyrolytic boron nitride container^-1~ 6500cm^-1If the light reflectance of the entire surface is partially or gradually decreased from the bottom side to the opposite opening side so as to be 25% or less, the opening side is reduced. Since heating can be performed more efficiently and selectively, the temperature of the upper portion of the container can be kept high, and adhesion of the raw material metal at this portion can be suppressed.
[0031]
In this case, it is desirable that the desired temperature distribution to be formed in the pyrolytic boron nitride container used in the MBE method is as low as possible in order to prevent the raw material from adhering to the upper part of the container. However, the phenomenon that the raw material rises along the inner wall of the container is not necessarily suppressed by raising the temperature of the upper part of the container.
This is presumably because so-called wettability with pyrolytic boron nitride differs depending on the type of raw material used. Therefore, in such a case, the IR transmittance is distributed gradually or gradually from the bottom side of the container to the opposite opening side, or the transmittance of a region having a specific height is increased. Alternatively, it is sufficient to take appropriate measures such as changing the reflectance.
[0032]
The inventors of the present invention used 2600 cm in the pyrolytic boron nitride container itself used in this MBE method.^-1~ 6500cm^-1The following three methods have been developed as a method of providing a distribution in which the light transmittance changes. The method (1) is a method of changing the density of pyrolytic boron nitride (PBN) and changing the light absorption coefficient, and the method (2) is to change the roughness of the outer surface of the PBN and change the amount of light scattering. (3) is a method of doping PBN with an element and changing the thickness, area and doping concentration of the doped layer, and this method has a distribution in which the reflectance changes. It can also be applied to.
[0033]
Hereinafter, each of these methods will be described in detail, but here, as an example, mainly the case where the IR transmittance at the upper part (opening side) of the container is lowered or the reflectance is lowered to raise the temperature at the upper part of the container. explain.
(1) Method of changing the light absorption coefficient of PBN
Regarding the optical characteristics of boron nitride (BN), the band gap (Eg) is 5.8 eV (see Research Report No. 27, P26 of Inorganic Materials Laboratory), and this IR absorption is 1,380 cm.^-1810cm^-1(See DN Bose, HK Henisch, J. Am. Cer. Soc. 53, page 281 (1970)). Therefore, the 2600 cm^-1~ 6500cm^-1However, pyrolytic boron nitride (PBN) actually has a certain amount of absorption even in the wavenumber region due to the disorder of the crystal and the mixing of turbo static crystals. It has become a thing.
[0034]
The PBN conventionally used in the MBE method has a high degree of orientation close to the theoretical density of 2.25 with a density of 2.1 to 2.2, and is highly uniform throughout the container. Thus, the high orientation degree PBN is 2600 cm.^-1~ 6500cm^-1An extinction coefficient of about 2.0 is measured for the light of. Therefore, in the present invention, it is desirable to make the extinction coefficient on the opening side as large as possible, effectively absorb the radiant heat, and make the extinction coefficient as small as possible on the bottom side, preferably 1.7 or less.
[0035]
And in order to make a distribution that makes a difference in the extinction coefficient between the bottom side and the opening side, transmits the radiant heat on the bottom side, absorbs it on the opening side, and sufficiently raises the temperature of the upper part of the container It is desirable that at least the difference in extinction coefficient is 0.5 or more, preferably 1.0 or more.
[0036]
Now, a method for manufacturing a PBN container having a distribution in which the extinction coefficient is small on the bottom side and the extinction coefficient is large on the opening side as in the present invention will be described.
In general, a PBN container is manufactured by a method in which a molded product of a container is obtained by vapor-depositing a product by a CVD reaction on a graphite mold (core metal) and then separating the product from the core metal.
[0037]
For example, 10 Torr using boron halide and ammonia as raw materials(10 x 133.3224 Pa)Under the following pressure, a pyrolytic boron nitride film is deposited to a required film thickness by a CVD reaction on a graphite core having a desired shape at a high temperature of 1600 ° C. to 2000 ° C., and then cooled to room temperature. The PBN container can be manufactured by removing the graphite mandrel and processing it into a final shape.
[0038]
However, as a result of an experimental study by the present inventors, the PBN of 2600 cm^-1~ 6500cm^-1It has been found that the light transmittance and the extinction coefficient depend on the conditions during the vapor deposition of the PBN by the CVD reaction, in particular, the pressure conditions.
That is, when the CVD reaction is performed under relatively high pressure conditions, the density of precipitated PBN tends to be low, the transmittance increases, and the extinction coefficient decreases. On the other hand, it has been found that when the CVD reaction is carried out under a relatively low pressure, the opposite result tends to be obtained.
[0039]
Although the detailed theory of such a phenomenon is unknown, since the density of the produced PBN tends to decrease when the CVD reaction is performed under a relatively high pressure, vitrification occurs in a part of the precipitated PBN. Resulting in 2600cm^-1~ 6500cm^-1It is considered that the transparency of light will progress.
[0040]
By utilizing this phenomenon, it is possible to reduce the light absorption coefficient on the bottom side of the container and conversely increase it on the opening side, thereby causing a difference in the absorption coefficient between the bottom side and the opening side. It becomes.
That is, as described above, since the PBN container is manufactured by a CVD reaction under reduced pressure, the raw material gas is supplied while sucking the inside of the reaction furnace with a pump. Accordingly, the pressure distribution in the reactor is generally such that the pressure on the raw material gas supply side is high and the pressure on the pump suction side is low. Therefore, the placement of the graphite core at the time of the CVD reaction is such that the portion corresponding to the bottom side of the PBN container is on the side where the source gas is supplied, that is, the high pressure side, and the opening side of the PBN container is on the pump side, If vapor deposition is performed so as to be on the low pressure side, the light absorption coefficient of the PBN container obtained can be distributed to be small on the bottom side and large on the opening side.
[0041]
In particular, when it is desired to increase the difference in absorption coefficient and transmittance between the bottom side and the opening side of the container, the pressure difference between the position where the bottom side is disposed and the position where the opening side is disposed may be increased. Therefore, in this case, it is necessary to increase the so-called pressure loss in the CVD reactor and to make the gradient of the pressure distribution steep. This is generally done by adjusting the supply amount of the source gas and the pumping capacity of the pump, the shape of the CVD reactor or a baffle plate in the CVD reactor so that a pressure loss is forcibly generated. Can be easily implemented.
[0042]
(2) A method of changing the amount of light scattering by changing the roughness of the outer surface of the PBN container.
2600cm of PBN container^-1~ 6500cm^-1The distribution of the light transmittance and the extinction coefficient can also be performed by adjusting the surface state of the PBN, that is, the surface roughness.
For example, the surface roughness of PBN and 2600 cm^-1~ 6500cm^-1Table 1 shows the results of investigating the relationship between the light transmittance and the extinction coefficient.
[0043]
[Table 1]

[0044]
This is because the surface of PBN having an extinction coefficient of 1.2 and 2.2 is left as deposited by CVD reaction (as-deposited), # 320 coarse Al₂  O₃  Polished with paper, # 1200 fine Al₂  O₃  It shows how the apparent light transmittance and extinction coefficient change when polished with paper.
[0045]
As is apparent from Table 1, the difference between the intrinsic extinction coefficient of the substance and the apparent extinction coefficient is small in AS Depot, and it seems that light scattering on the surface does not occur much. On the other hand, when the surface is polished with # 320 paper, the surface is rough, so the amount of light scattering is large, the apparent extinction coefficient is remarkably increased, and the transmittance is lowered. Further, when the surface is polished with # 1200 paper, the surface becomes finer than that of # 320, so that the amount of light scattering decreases, the apparent extinction coefficient decreases, and the transmittance increases.
[0046]
Since the transmittance can be changed by adjusting the surface roughness in this way, for example, the opening side of the outer surface of the pyrolytic boron nitride container is polished with # 320 paper, and the bottom side is left as is. If the middle is polished with # 1200 paper, the outer surface of the container is rough on the opening side and finer on the bottom side, and the transmittance distribution is from the bottom side to the opening side on the opposite side. Towards, it can be reduced stepwise or gradually.
[0047]
(3) Method of doping PBN with elements
In this method, when PBN is vapor-deposited by a CVD reaction, a doping gas is introduced and a desired element is doped into the PBN, so that the transmittance or reflectance distribution can be easily and reliably attached to the PBN container.
[0048]
In this case, any element can be used as a doping element as long as it can change the IR transmittance or reflectance of PBN, but it can be easily doped with a doping gas, etc. In view of this, it may be one or more elements selected from B, N, Si, C, and Al.
And when depositing PBN on the mandrel by CVD reaction, for example, BF₃  , N₂  H₄  , SiCl₄  , CH₄  , Al (CH₃  )₃  By introducing a gas containing a doping element such as, a doped layer doped with these elements in PBN can be formed.
[0049]
This dope layer can be formed at any position in the PBN container. For example, the dope layer may be formed on the inner surface of the container, but if formed on the inner surface, there is a risk of contaminating the raw material melt contained in the container. Therefore, it is preferable that the dope layer is not exposed on the inner surface of the container. Therefore, if it is formed on the outer surface of the container or in PBN, there is no concern that the raw material melt is contaminated by these elements.
[0050]
And by adjusting the thickness, area and dope concentration of this dope layer, 2600 cm of the PBN container^-1~ 6500cm^-1The light transmittance or reflectance distribution can be freely controlled.
For example, if the opening side of the PBN container is thick or thick, the formation area is widened, the bottom side is thin and the formation area is narrow or not formed, the light transmittance or reflectance is reduced to the bottom side. Can be changed stepwise or gradually toward the opening side.
[0051]
In order to control the thickness of the doped layer, for example, the time for introducing the doping gas during the CVD reaction may be adjusted, and the doping concentration can be easily controlled by adjusting the concentration of the doping gas in the introduced gas. Can be done. In addition, the distribution of the thickness and area of the doped layer can be easily performed by an operation such as mechanically polishing the doped layer after the completion of the doping reaction.
[0052]
DETAILED DESCRIPTION OF THE INVENTION
Next, embodiments of the present invention will be described by way of examples, but the present invention is not limited to these.
[0053]
【Example】
Examples of the present invention and comparative examples are shown below.
(Example 1, Comparative Example 1)
In the graphite cylindrical CVD reactor, a graphite mandrel is used, and in Example 1, the opening side of the vessel is set to a low pressure side and the bottom side is a raw material so that the density on the opening side of the vessel is increased by the MBE method. Arranged so as to be on the gas supply side (FIG. 1 (A)), and in Comparative Example 1, it was arranged so that the entire container had a uniform density distribution, that is, the side of the container was on the source gas supply side ( In FIG. 1 (B)), PBN was deposited while rotating this.
[0054]
This was supplied with boron trichloride 2 L / min, ammonia 5 L / min, and an average pressure 2 Torr at the center of the furnace.(2 x 133.3224 Pa)The MBE method PBN container having a thickness of 0.8 to 1.3 mm, a diameter of 20 mm, and a height of 150 mm was prepared by reacting at 1850 ° C. At this time, the source gas supply side of the CVD reactor is about 4 Torr.(4 x 133.3224 Pa)The exhaust side is about 2 Torr(2 x 133.3224 Pa)Met. After the reaction was completed, PBN and mandrel were separated and then processed to produce a final shape PBN container.
[0055]
2600 cm on the bottom side, the container center, and the opening side of the PBN container thus obtained.^-1~ 6500cm^-1Is measured with an IR spectrum meter (manufactured by FTIR-710 NICOLET), and from the following formulas (2), (3) and (4), 4800 cm respectively.^-1When the extinction coefficient B was determined, the results shown in Table 2 were obtained.
Absorbance (A) = Log₁₀(I_o  / I) (2)
(Where I_o  Is incident light and I is transmitted light. )
Absorption coefficient (B) = A / t (3)
(Where t is the thickness)
Transmittance (T) = I / I_o              .... (4)
[0056]
[Table 2]

[0057]
As is clear from the results in Table 2, the container of Example 1 has a small extinction coefficient on the bottom side, and conversely a large extinction coefficient on the opening side. Since the radiation is absorbed more on the part side, the temperature of the upper part of the container does not decrease, and it is expected to effectively suppress the adhesion of the raw material or the creeping phenomenon of the raw material in this part In the container of Comparative Example 1, since the extinction coefficient of the entire container is uniform, the temperature of the upper part of the container without the raw material is lowered, and the adhesion of the raw material to this part and the creeping phenomenon become severe.
[0058]
(Example 2)
Next, a container with uniform absorption coefficient and transmittance of the entire container was produced by the same method as in Comparative Example 1 above. In this case, the average pressure in the furnace is 4 Torr.(4 x 133.3224 Pa)And the overall extinction coefficient was lowered. 4800cm of each part of the PBN container made in this way^-1The light extinction coefficient and transmittance were measured in advance.
[0059]
Next, as shown in FIG. 2, the outer surface of the PBN container on the opening side was subjected to surface treatment with # 320, and the central portion of about 5 cm was treated with # 1200 alumina sandpaper, and the bottom side was left as-deposited. 4800cm of each part of the surface-treated PBN container^-1The light transmittance was measured again, and the results are shown in Table 3.
[0060]
[Table 3]

[0061]
As apparent from the results in Table 3, in the container of Example 2 subjected to the surface treatment, the surface on the opening side is rough, so that light is scattered on the surface and the transmittance is reduced. On the bottom side, it remains as-deposited, so the light transmittance is high. If this container is used for the MBE method, it is difficult to transmit radiant heat on the opening side, so an ideal temperature gradient is formed in the container. It is expected to effectively prevent the adhesion of the raw material and the creeping phenomenon at the upper part of the container.
[0062]
(Example 3)
Next, a container with uniform absorption coefficient and transmittance of the entire container was produced by the same method as in Comparative Example 1 above. In this case, the average pressure in the furnace is 4 Torr.(4 x 133.3224 Pa)And the overall extinction coefficient was lowered. 4800cm of each part of the PBN container thus made^-1The light extinction coefficient and transmittance were measured in advance.
[0063]
Next, this PBN container is set again in the CVD furnace and 1 Torr.(1333.324 Pa)Under reduced pressure, the temperature was raised to 1600 ° C., methane gas was supplied thereto at 5 SLM, boron trichloride 2 L / min, and ammonia 5 L / min to form a doped layer in which PBN was doped with carbon. This was taken out after cooling, and as shown in FIG. 3, the dope layer was removed by mechanical polishing at about half of the bottom side, and the carbon dope layer was left as it was at the half of the opening side. Further, the PBN container subjected to the surface treatment was set again in the CVD furnace, and a PBN layer of about 100 μm was deposited on the outermost surface, and the dope layer was embedded.
4800cm of the PBN container with the carbon doped layer thus formed^-1The light transmittance was measured again, and the results are shown in Table 4.
[0064]
[Table 4]

[0065]
As is apparent from the results of Table 4, in the container of Example 3 doped with carbon, the transmittance is very small because the carbon element absorbs light on the opening side, whereas conversely, Since there is no doped layer on the bottom side and PBN remains as-deposited, the light transmittance is high. Therefore, if this container is used for the MBE method, radiation is absorbed more at the opening side, so the temperature at the upper part of the container does not decrease, and the adhesion of the raw material or the creeping phenomenon of the raw material at this part is effective. Is expected to be suppressed.
[0066]
In this example, for the measurement of the transmittance, the CVD reaction was interrupted and the production vessel was once taken out, and then a dope layer was formed. Should be introduced.
[0067]
(Comparative Example 2)
After producing a PBN container in the same manner as in Comparative Example 1, it was set in the CVD furnace again and 1 Torr.(1333.324 Pa)The temperature was raised to 1750 ° C. under reduced pressure, and methane gas was supplied thereto at 5 SLM to form a carbon layer having a thickness of 50 μm on the surface of PBN. This was taken out after cooling, and the carbon layer was removed from the bottom outer surface and inner surface by mechanical polishing. Further, the PBN container subjected to the surface treatment was set again in the CVD furnace, and a PBN layer of about 100 μm was deposited on the outermost surface thereof, thereby producing a composite container in which the carbon layer was embedded.
However, this was unusable because the combined layers were peeled off after cooling and were damaged.
[0068]
Next, using the PBN containers obtained in Examples 1 to 3 and Comparative Example 1, an epitaxial film of GaAlAs was actually grown by the MBE method.
The growth of the epitaxial film is carried out with an atmospheric pressure of 10^-Ten Torr(10 ^-Ten × 1333.3224Pa)The heating temperature was 1000 ° C., and in each case, a PBN container was used as a Ga filling container.
The surface of the grown epitaxial film was observed with an optical microscope, and the surface defect density was measured. The results are shown in Table 5.
[0069]
[Table 5]

[0070]
As can be seen from Table 5, when the PBN container of the example is used, the surface defect density of the epitaxial film to be grown is small, and the material adhesion on the top of the container is small. It can be seen that the problem of scattering is suppressed.
On the other hand, when the PBN container of Comparative Example 1 is used, the temperature of the upper part of the container is low, and the adhesion of the raw material in this part is intense, so that the epitaxial film to be grown has many surface defects.
[0071]
(Example 4) [Container with distribution of reflectance]
A graphite mandrel is placed and rotated in a graphite cylindrical CVD reactor, 2 L / min of BCl3 and 5 L / min of NH3 are supplied thereto, and the average pressure in the furnace is 2 Torr.(2 x 133.3224 Pa)After forming a PBN layer by reacting at 1850 ° C. for 10 hours, the source gas is mixed with 5 L / min of CH 4 and reacted for 20 minutes to dope carbon doped into 30 μm thick PBN. A PBN container with a thickness of 1 mm, a diameter of 20 mm and a height of 100 mm coated with a layer was produced. Further, the range of 65 mm from the bottom of the container was removed by mechanical polishing, leaving the carbon doped layer only in the range of 35 mm from the opening.
For this container, the outer surface reflectance of the light of the wavelength 2300 nm (λmax at 1000 ° C.), 2000 nm (λmax at 1200 ° C.) and 1700 nm (λmax at 1400 ° C.) of the outermost surface of the carbon-doped layer was measured. The results were 10%, 12% and 8%, respectively.
[0072]
(Comparative Example 3)
A graphite mandrel is placed and rotated in a graphite cylindrical CVD reactor, 2 L / min of BCl3 and 5 L / min of NH3 are supplied thereto, and the average pressure in the furnace is 2 Torr.(2 x 133.3224 Pa)The reaction was carried out at 1850 ° C. for 10 hours to produce a single PBN container having a thickness of 1 mm, a diameter of 20 mm, and a height of 100 mm.
As a result of measuring the outer surface reflectance of the PBN layer with respect to light of wavelengths 2300 nm (λmax at 1000 ° C.), 2000 nm (λmax at 1200 ° C.) and 1700 nm (λmax at 1400 ° C.) of the outermost surface of the PBN layer. Were 60%, 55% and 47%, respectively.
[0073]
(Comparative Example 4)
The PBN container prepared in Comparative Example 3 was placed in the CVD reactor again, 5 L / min of CH4 was supplied thereto, and the average pressure in the furnace was 2 Torr.(2 x 133.3224 Pa)The reaction was carried out at 1650 ° C. for 3 hours to deposit a coating layer of pyrolytic graphite (PG) having a thickness of 30 μm on the outermost surface of the container. Further, the PG coating layer in the range of 65 mm from the bottom of the container was removed by mechanical polishing, leaving the PG coating layer in the range of 35 mm from the opening.
As a result of measuring the outer surface reflectance of the PG layer on the outermost surface of the PG layer at wavelengths of 2300 nm (λmax at 1000 ° C.), 2000 nm (λmax at 1200 ° C.) and 1700 nm (λmax at 1400 ° C.). Were 60%, 60% and 45%, respectively.
[0074]
Next, Al was put into the PBN container obtained in Example 4, Comparative Example 3 and Comparative Example 4, and this was heated to 1100 ° C., and the result of actually growing an epitaxial film of GaAlAs by molecular beam epitaxy was shown. Table 6 shows.
[0075]
As can be seen from Table 6, when the carbon-doped PBN container of Example 4 is used, the temperature gradient in the container becomes ideal, so there is little Al drop generation on the opening side, and the defect density. An extremely stable epitaxial film having a small thickness can be grown.
[0076]
On the other hand, when the PBN containers of Comparative Example 3 and Comparative Example 4 were used, drops were generated in the vicinity of the opening, resulting in many defects as shown in Table 6. In addition, since the radiation from the heater is easily reflected on the surface of the container, the power consumption of the heater is larger than when the PBN container of Example 4 is used.
[0077]
[Table 6]

[0078]
The present invention is not limited to the above embodiment. The above-described embodiment is an exemplification, and the present invention has substantially the same configuration as the technical idea described in the claims of the present invention, and any device that exhibits the same function and effect is the present invention. It is included in the technical scope of the invention.
[0079]
For example, in the above description, three methods are given as methods for imparting the transmittance distribution to the container, and each method has been described individually. However, these methods may be performed at the same time to form a finer transmittance distribution. It is also possible.
[0080]
【The invention's effect】
According to the present invention, a pyrolytic boron nitride container used in molecular beam epitaxy is 2600 cm.^-1~ 6500cm^-1Because the distribution of the light transmittance or reflectance of the container changes in the height direction of the container, the temperature distribution inside the container is ideal, effectively preventing the adhesion of raw materials to the top of the container and the creeping phenomenon. A pyrolytic boron nitride container can be provided easily and at low cost.
Therefore, if an epitaxial film is manufactured by MBE using this, a good quality epitaxial film with few surface defects can be grown.
[Brief description of the drawings]
FIG. 1 is a schematic cross-sectional view when an MBE PBN container is manufactured by a CVD reaction.
(A) When the mandrel made of graphite is arranged so that the bottom side of the container is the raw material gas supply side (Example 1),
(B) When the mandrel made of graphite is arranged so that the side portion of the container is on the source gas supply side (Comparative Example 1, Example 2, Example 3, Comparative Example 2).
FIG. 2 is a schematic cross-sectional view of a PBN container in which the opening side is surface treated with # 320 alumina center paper of about 5 cm in the central part, and the bottom is left as-deposited (Example 2).
FIG. 3 is a schematic sectional view of a carbon-doped PBN container (Example 3).
[Explanation of symbols]
1 ... CVD furnace, 2 ... graphite core,
3 ... PBN container, 4 ... carbon doped layer.

Claims (17)

In pyrolytic boron nitride container used as a molecular beam epitaxy for molecular beam source container, the light transmittance of the heat wave number decomposition boron nitride container itself 2600cm ^-1 ~6500cm ^-1 is stage in the height direction of the container Pyrolytic boron nitride container characterized by having a distribution that changes periodically or gradually . 2. The pyrolytic boron nitride container according to claim 1, wherein the light transmittance is distributed in a stepwise or gradually decreasing manner from the bottom side to the opening side of the container. 2. The pyrolytic boron nitride container according to claim 1, wherein the light transmittance is a distribution that increases stepwise or gradually from the bottom side to the opening side of the container. The pyrolytic boron nitride container according to any one of claims 1 to 3, wherein a distribution is given to the light transmittance by changing an absorption coefficient of pyrolytic boron nitride. The pyrolytic nitriding according to any one of claims 1 to 4, wherein a distribution of the light transmittance is given by changing a roughness of an outer surface of the pyrolytic boron nitride container. Boron container. 6. The pyrolytic boron nitride is doped with an element, and the thickness, area, and doping concentration of the doped layer are changed to give a distribution to the light transmittance. The pyrolytic boron nitride container described in any one of the items. The pyrolytic boron nitride container according to claim 6, wherein the doped layer doped with the element is not exposed to the inner surface of the container. The pyrolytic boron nitride according to claim 6 or 7, wherein the element doped into the pyrolytic boron nitride is at least one element selected from B, N, Si, C, and Al. container. In a method for producing a pyrolytic boron nitride container used as a molecular beam source container for molecular beam epitaxy, in which a product of a CVD reaction is deposited on a graphite mandrel and then separated from the mandrel to obtain a molded body of the container By arranging the mandrel according to the pressure distribution in the CVD furnace, the extinction coefficient of the pyrolytic boron nitride to be generated is changed, and the light transmittance of 2600 cm ^{-1 to} 6500 cm ^-1 of the container is increased. A method for producing a pyrolytic boron nitride container, characterized by providing a distribution that changes stepwise or gradually in the vertical direction. By distributing the roughness of the outer surface of the pyrolytic boron nitride container and adjusting the amount of light scattering on the outer surface, the light transmittance of 2600 cm ^{−1 to} 6500 cm ⁻¹ of the container is adjusted to the height of the container. A method for producing a pyrolytic boron nitride container having a distribution in the light transmittance, characterized by providing a distribution that changes stepwise or gradually in a direction . In the method of manufacturing a pyrolytic boron nitride container in which a product of the CVD reaction is deposited on a graphite mandrel and then separated from the mandrel, a dope gas is introduced into the furnace at least during the CVD reaction. A step of forming a doped layer in the pyrolytic boron nitride, and adjusting the thickness, area, and doping concentration of the doped layer, thereby allowing light to pass through the container at 2600 cm ^{−1 to} 6500 cm ^−1. A method for producing a pyrolytic boron nitride container having a distribution in the light transmittance, wherein a distribution that changes stepwise or gradually in the height direction of the container is given to the rate. In pyrolytic boron nitride container used as a molecular beam epitaxy for molecular beam source container, the light reflectance of the wavenumber 2600cm ^-1 ~6500cm ^-1 in the outer surface of the container itself, stepwise in the height direction of the container Or a pyrolytic boron nitride container characterized by having a gradually changing distribution. The pyrolytic boron nitride container according to claim 12, wherein the light reflectance is 25% or less on the entire outer surface of the container or partially. 14. The pyrolytic boron nitride according to claim 12, wherein the light reflectance is a distribution that decreases stepwise or gradually from the bottom side to the opening side of the container. container. The pyrolytic boron nitride according to claim 12 or 13, wherein the light reflectance is a distribution that increases stepwise or gradually from the bottom side to the opening side of the container. container. 13. The pyrolytic boron nitride is doped with an element, and the light reflectance is distributed by changing the thickness of the doped layer, the area of the doped layer, and the doping concentration. Item 15. The pyrolytic boron nitride container according to any one of Items 15. In the method of manufacturing a pyrolytic boron nitride container in which a product of the CVD reaction is vapor-deposited on a graphite mandrel and then separated from the mandrel, a dope gas is introduced into the furnace at least during the CVD reaction. A step of forming a doped layer in pyrolytic boron nitride, and adjusting the thickness of the doped layer, the area of the doped layer, and the doping concentration, thereby adjusting the wave number of the vessel from 2600 cm ^{−1 to} 6500 cm ^−1. A method for producing a pyrolytic boron nitride container having a distribution in the light reflectance, wherein a distribution that changes stepwise or gradually in the height direction of the container is imparted to the light reflectance.

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