JP3736322B2 - Vapor growth equipment - Google Patents

Vapor growth equipment Download PDF

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JP3736322B2
JP3736322B2 JP2000283556A JP2000283556A JP3736322B2 JP 3736322 B2 JP3736322 B2 JP 3736322B2 JP 2000283556 A JP2000283556 A JP 2000283556A JP 2000283556 A JP2000283556 A JP 2000283556A JP 3736322 B2 JP3736322 B2 JP 3736322B2
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flow path
raw material
material supply
vapor phase
phase growth
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JP2002016010A (en
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隆 宇田川
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Showa Denko KK
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Showa Denko KK
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    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
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    • C23C16/00—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes
    • C23C16/44—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the method of coating
    • C23C16/455—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the method of coating characterised by the method used for introducing gases into reaction chamber or for modifying gas flows in reaction chamber
    • C23C16/45561—Gas plumbing upstream of the reaction chamber
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    • C23C16/00—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes
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    • C23C16/455—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the method of coating characterised by the method used for introducing gases into reaction chamber or for modifying gas flows in reaction chamber
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    • C30B25/00—Single-crystal growth by chemical reaction of reactive gases, e.g. chemical vapour-deposition growth
    • C30B25/02—Epitaxial-layer growth
    • C—CHEMISTRY; METALLURGY
    • C30—CRYSTAL GROWTH
    • C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
    • C30B25/00—Single-crystal growth by chemical reaction of reactive gases, e.g. chemical vapour-deposition growth
    • C30B25/02—Epitaxial-layer growth
    • C30B25/14—Feed and outlet means for the gases; Modifying the flow of the reactive gases
    • C—CHEMISTRY; METALLURGY
    • C30—CRYSTAL GROWTH
    • C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
    • C30B29/00—Single crystals or homogeneous polycrystalline material with defined structure characterised by the material or by their shape
    • C30B29/10—Inorganic compounds or compositions
    • C30B29/46—Sulfur-, selenium- or tellurium-containing compounds
    • C30B29/48—AIIBVI compounds wherein A is Zn, Cd or Hg, and B is S, Se or Te
    • H—ELECTRICITY
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    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
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    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
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    • H01L33/00—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
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    • H01L33/0062—Processes for devices with an active region comprising only III-V compounds
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Abstract

A vapor deposition apparatus comprises a first run line for mixing vapor deposition source(s) with carrier gas, a second run line for supplying source mixture to vapor deposition region, vent lines for detouring source mixture away from the deposition region and for exhausting the source mixture, and a line-switching mechanism for switching the flow of source mixture. A vapor deposition apparatus comprises first and second run lines (27, 28), vent lines (29, 29a), and line-switching mechanism. The first run line combines vapor deposition source(s) with carrier gas in advance and passes the resultant source mixture. The second run line supplies the source mixture to a vapor deposition region (39), and the vent line allows the source mixture to detour away from the vapor deposition region and exhausts the source mixture. The line-switching mechanism switches the flow of the source mixture from the first run line to either the second run line or the vent line. An Independent claim is also included for vapor-growing a stacked layer structure utilizing the above apparatus.

Description

【０００１】
【発明の属する技術分野】
本発明は、特に、半導体積層構造体を形成するための気相成長装置に関し、更に詳しくは、急峻な半導体ヘテロ（異種）接合界面組成を形成するのに適した気相成長装置に関する。また、本発明は、上記気相成長装置を用いた気相成長方法、該方法により形成された積層構造体、該積層構造体から構成された電界効果型トランジスタ、半導体ホール素子及び半導体発光素子に関する。
【０００２】
【従来の技術】
従来より、シングルヘテロ（英略称：ＳＨ）或いはダブルヘテロ（英略称：ＤＨ）構造発光素子、或いは、２次元電子電界効果型トランジスタ（ＴＥＧＦＥＴ）用途のエピタキシャル（ｅｐｉｔａｘｉａｌ）積層構造体等は有機金属熱分解化学的堆積（ＭＯＣＶＤ）法等の気相成長手段に依り形成されている（Ｓｏｌｉｄ Ｓｔａｔｅ Ｅｌｅｃｔｒｏｎ．，第４３巻（１９９９）、１５７７〜１５８９頁参照）。この場合、特に、ＴＥＧＦＥＴ用途積層構造体の形成では、２次元電子（ｔｗｏ−ｄｅｍｅｎｓｉｏｎａｌ ｅｌｅｃｔｒｏｎ ｇａｓ：ＴＥＧ）による効果を効率よく発現させるためにヘテロ接合界面での組成変化の急峻性が要求されている（日本物理学会編、「半導体超格子の物理と応用」、初版第４刷、昭和６１年９月３０日、（株）培風館発行、１３９〜１４５頁参照）。
【０００３】
ＭＯＣＶＤ法により半導体結晶、例えば、ＩＩＩ−Ｖ族化合物半導体結晶層を気相成長させる従来の気相成長装置では、ＩＩＩ族構成元素の原料或いはＶ族構成元素の原料を、結晶層の成長に必要であるか否かに拘わらず、定常的に流通できる配管系は備えられてはいなかった（▲１▼Ｊ．Ｃｒｙｓｔａｌ Ｇｒｏｗｔｈ、第５５巻（１９８１）、６４〜７３頁、▲２▼同誌同巻、９２〜１０６頁、▲３▼同誌同巻、１６４〜１７２頁、及び▲４▼同誌同巻、２１３〜２２２頁参照）。即ち、従来の気相成長装置では、構成元素原料或いはドーピング源は、必要時にのみ気相反応領域に供給する配管構成となっており、結晶層の気相成長に一時的に不要となった原料気体は、バルブ操作により、一時的に供給を停止していた。
【０００４】
このような従来の気相成長装置の配管系では、原料気体が再び必要となった際には、バルブを開状態とし、再び、その原料気体を気相成長領域に流通させる必要がある。ところが、遮断された状態から再び、流通を開始した暫時において、バルブの開状態への移行に伴う配管系内の圧力変動により流量が過渡的に変動する不具合や、原料気体が配管内に封止或いは滞留していたことに伴う純度の低下が生じていた。このような原料気体の流量の過渡的変動や純度の低下は、結晶層を構成する元素間の組成変動を招き、組成の急峻性に優れた接合界面の形成を困難としていた。そのため、従来の配管系を用いた気相成長装置では、例えば急峻なヘテロ接合界面を必須とするＴＥＧＦＥＴ用途の積層構造体の気相成長には不適となっているのが現状であった。
【０００５】
このような気相成長装置の配管系の欠点を補完し、組成の急峻性に優れる半導体接合界面を形成するため、原料気体を常時流通でき、且つ気相成長領域に流入させる原料気体を瞬時に切換える機構を有する、ベント（ｖｅｎｔ）／ラン（ｒｕｎ）方式と呼称される原料気体の供給配管系が発案されている（▲１▼Ｊ．Ｃｒｙｓｔａｌ Ｇｒｏｗｔｈ、第６８巻（１９８４）、４１２〜４２１頁、▲２▼同誌同巻、４６６〜４７３頁、及び赤崎 勇編著、「ＩＩＩ−Ｖ族化合物半導体」（（株）培風館、１９９４年５月２０日発行初版）、６８〜７０頁参照）。ベント流路（排気系流路）は、目的とする結晶層の気相成長に必要、不要に拘わらず、原料ガスを気相反応領域の外部へ予め継続して流通し、原料気体の安定した流れを創出しておくために設けられる流路である。またラン流路（原料供給流路）は、目的とする結晶層の気相成長時に必要とされる原料気体を排気系流路から切換えて気相反応領域に直結する流路である。即ち、ベント／ラン方式は、従来の原料供給流路のみの配管系と異なり、原料気体を常時流通させるための排気系流路を設けた構成となっている。
【０００６】
図１にベント／ラン方式からなる原料気体供給配管系を例示する。気体原料或いは原料の蒸気を随伴する気体からなる原料気体１０、１１、１２を流通させるための原料気体流路１３、１４，１５は、原料気体１０〜１２の種別毎に配備されている。原料気体流路１３〜１５に流通する原料気体１０〜１２の流量は流量計１６、１７、１８によって調整される。原料気体に対応して設けた原料気体流路１３〜１５は従来では、２方バルブ（ｔｗｏ−ｗａｙ ｖａｌｖｅ）１９〜２４を介して、原料供給流路２５と排気系流路２６とに接続されている。
２方バルブとは、単一の流路において流体を流通させるか遮断するかを弁体の開閉操作で行うものである。原料供給系２５は結晶層の堆積を行う気相反応領域に直結されている。また排気系流路２６は気相反応領域を迂回して排気処理を行う排気系に直結されている。
【０００７】
原料供給流路２５から排気系流路２６への原料気体１０〜１２の切換え、或いはその逆の切換えは、原料気体流路１３〜１５の各々に設置された流路切換え用弁１９〜２４の開閉操作により行われる。例えば、原料気体流路１３に流通される原料気体１０を、排気系流路２６より切換えて原料供給流路２５に流通させるには、２方バルブ２２を閉状態とするのに同期させて２方バルブ１９を開状態とすることにより行う。ここで、２方バルブ１９と２２は定常的に同時に開状態となる場合はなく、２方バルブ２０と２３、２１と２４においても同様である。
【０００８】
【発明が解決しようとする課題】
従来のベント／ラン方式の供給系は唯一の原料供給流路２５と、唯一の排気系流路２６との組合わせからなる配管系から構成されている。例えば、この様な一組の組合わせからなるベント／ラン方式（単一ベント／ラン方式：ｓｉｎｇｌｅｖｅｎｔ−ｒｕｎ））において、排気系流路２６から変更して原料供給流路２５に瞬時に原料気体を流通させた後の暫時において、原料気体の流量に周期的な変動が発生する。この流量の変動は、原料気体が原料供給流路２５内を気相反応領域へと移送される間に緩和されるものの、依然として気相反応領域に於ける原料気体の供給量の変動は残存する。原料気体の供給量の変動は、結晶層の層厚の増加方向に於ける組成比率等の変動を引き起こし、また例えば、ヘテロ接合界面における組成の急峻的な変化を妨げる不具合を引き起こす。
【０００９】
具体的に従来の単一ベント／ラン方式の原料供給配管系の問題点を図１を利用して説明する。例えば、２種の気体原料１０、１１が原料気体流路１３，１４を介して既に安定な流量で原料供給流路２５に流通させて結晶層を気相成長させた後、継続して今度は３種の原料気体１０〜１２を利用した混晶層を気相成長させる場合を仮定する。この状態において、混晶層を成長させるには、更に原料気体１２を排気系流路２６から原料供給流路２５に２方バルブ２１，２４の開閉動作により流路を切換る必要がある。この切換えの瞬時において原料気体１２の流量は周期的に変動し不安定となる。この原料気体１２の流量の不安定性により原料気体１２に係わる混晶の構成元素の組成は不安定となる。特に、接合界面領域に於ける組成の急峻性を得るのに難を来しているのが現状である。
【００１０】
従来の単一ベント／ラン方式の原料供給配管系（図１参照）で３種類の原料気体１０〜１２を利用して混晶層を気相成長させるのに際し、原料気体１０〜１２の流路を排気系流路２６から原料供給流路２５に同時に切換えたとしても、原料供給流路２５の内部に流量変動を生ずる。これは、原料気体流路２５と２６との間において、圧力差を０にすることが困難だからである。このため、排気系流路から原料供給流路の切換えに伴い、原料供給流路２５内の各気体原料の流量が変動してしてしまう問題点がある。この様な流量変化を生じた原料気体を反応領域に供給したところで安定した混晶層の気相成長が実現できないという問題が生じている。
【００１１】
これらの問題点は、従来の単一ベント／ラン方式の原料供給系の流路の切換え時において、原料気体の流量の変動並びに原料気体の混合比の不安定性が発生することに起因する。これを解決することが本発明の目的である。
【００１２】
【課題を解決するための手段】
本発明者は上記課題を解決すべく鋭意努力検討した結果、原料気体の混合比率が一定となった段階で、この混合された原料気体の流路を瞬時に切換えて気相成長領域に供給する配管構造とすれば、組成の急峻性に優れる接合界面を安定的に形成することが可能となることを見出し本発明を完成した。即ち本発明は、
［１］基板材料上に半導体の結晶層を積層した積層構造体を形成するための気相成長装置において、１種または複数の気相成長原料を予め搬送用気体に混合させて流通させるための第１の原料供給流路と、当該混合された気相成長原料を気相成長反応領域に導入するための第２の原料供給流路と、該気相成長反応領域を迂回して排気するための排気系流路とが少なくとも具備され、且つ、第１の原料供給流路に流通される前記の混合された気相成長原料の流路を、第２の原料供給流路または排気系流路の何れかに切り換るための流路切換機構が備えられていることを特徴とする気相成長装置、
［２］排気系流路が搬送用気体を流入させる機構を有するものである［１］に記載の気相成長装置、
［３］第１の原料供給流路が、第２の原料供給流路または排気系流路の何れかに切り換えるための流路切換機構を２系列以上有するものである［１］または［２］に記載の気相成長装置、
［４］第１の原料供給流路または第２の原料供給流路と、排気系流路との間の差圧を測定する装置が備えられていることを特徴とする［１］乃至［３］の何れか１項に記載の気相成長装置、
［５］気相成長原料に、第Ｖ族または第ＶＩ族元素の水素化物を含むことを特徴とする［１］乃至［４］の何れか１項に記載の気相成長装置、
［６］第１の原料供給流路内で予め混合された気相成長原料の混合比率を一定とした後、該気相成長原料の流路を、排気系流路から第２の原料供給流路に切り換えることを特徴とする［１］乃至［５］の何れか１項に記載の気相成長装置を用いた積層構造体の気相成長方法、
［７］第１の原料供給流路内で予め混合された気相成長原料の流路を排気系流路より第２の原料供給流路に切り換えるに際し、第１の原料供給流路と第２の原料供給流路との間の差圧を５×１０2パスカル（Ｐａ）以下の状態として切り換えることを特徴とする［１］乃至［５］の何れか１項に記載の気相成長装置を用いた積層構造体の気相成長方法、
［８］有機金属熱分解気相成長方法に依り、積層構造体を形成することを特徴とする［６］または［７］に記載の気相成長方法、
［９］［６］乃至［８］の何れか１項に記載の気相成長方法に依り形成されたことを特徴とする積層構造体、
［１０］積層構造体を、ヘテロ（異種）接合構造を有する多層積層構造体とすることを特徴とする［９］に記載の積層構造体、
［１１］積層構造体を、電界効果型トランジスタ用途の多層積層構造体とすることを特徴とする［１０］に記載の積層構造体、
［１２］電界効果型トランジスタ用途の多層積層構造体を、リン化ガリウム・インジウム（組成式ＧａXＩｎ1-XＰ：０≦Ｘ≦１）と砒化ガリウム・インジウム（組成式ＧａYＩｎ1-YＡｓ：０≦Ｙ≦１）とのヘテロ接合を有する多層構造体とすることを特徴とする［１１］に記載の積層構造体、
［１３］電界効果型トランジスタ用途の多層積層構造体を、砒化アルミニウム・インジウム（組成式ＡｌXＩｎ1-XＡｓ：０≦Ｘ≦１）と砒化ガリウム・インジウム（組成式ＧａYＩｎ1-YＡｓ：０≦Ｙ≦１）とのヘテロ接合を有する多層構造体とすることを特徴とする［１１］に記載の積層構造体、
［１４］積層構造体を、ＩＩＩ−Ｖ族化合物半導体ホール素子用途の多層構造体とすることを特徴とする［１０］に記載の積層構造体、
［１５］ 積層構造体を、リン化インジウム（化学式：ＩｎＰ）と砒化ガリウム・インジウム（組成式ＧａYＩｎ1-YＡｓ：０≦Ｙ≦１）とのヘテロ接合を有する多層構造体とすることを特徴とする［１４］に記載の積層構造体、
［１６］積層構造体を、ＩＩＩ族窒化物半導体発光素子用途の多層構造体とする、ことを特徴とする［１０］に記載の積層構造体、
［１７］積層構造体を、窒化アルミニウム・ガリウム（組成式ＡｌXＧａ1-XＮ：０≦Ｘ≦１）と窒化アルミニウム・ガリウム・インジウム（組成式（ＡｌXＧａ1-X）YＩｎ1-YＮ：０≦Ｘ≦１、０≦Ｙ＜１）とのヘテロ接合を有する多層構造体とすることを特徴とする［１６］に記載の積層構造体、
［１８］［１１］に記載の積層構造体を用いたことを特徴とする電界効果型トランジスタ、
［１９］砒化ガリウム・インジウム（組成式ＧａYＩｎ1-YＡｓ）を活性層として備えた積層構造体から構成したことを特徴とする［１８］に記載の電界効果型トランジスタ、
［２０］［１４］に記載の積層構造体を用いたことを特徴とするＩＩＩ−Ｖ族化合物半導体ホール素子、
［２１］［１５］に記載の積層構造体から構成したことを特徴とする［２０］に記載のＩＩＩ−Ｖ族化合物半導体ホール素子、
［２２］［１６］に記載の積層構造体を用いたことを特徴とするＩＩＩ族窒化物半導体発光素子、
［２３］［１７］に記載の積層構造体から構成したことを特徴とする［２２］に記載のＩＩＩ族窒化物半導体発光素子に関する。
【００１３】
【発明の実施の形態】
本発明の構成からなる流路の例を図２に模式的に示す。本発明に係わる流路配管系の特徴は、第１及び第２の複数の原料供給流路（第１及び第２の原料供給流路）２７、２８と各々の原料供給流路２７、２８に対応して設けた第１及び第２の複数の排気系流路（第１及び第２の排気系流路）２９、２９ａから構成されていることにある。換言すれば、従来の単一のベント／ラン方式ではなく、二重のベント／ラン（Ｄｏｕｂｌｅ Ｖｅｎｔ−Ｒｕｎ）方式の機構を具備しているのが特徴である。本発明の配管機構に依れば、原料気体は２段階に組まれた原料供給流路２７、２８を介して気相反応領域３９に供給されることとなる。本発明に係わる二重のベント／ラン方式の機構は例えば、減圧或いは常圧（略大気圧）ＭＯＣＶＤ法やハロゲン（ｈａｌｏｇｅｎ）或いはハイドライド（ｈｙｄｒｉｄｅ）ＶＰＥ法によるＩＩＩ−Ｖ族またはＩＩ−ＶＩ族化合物半導体結晶等の気相成長装置に好適に用いることができる。また、珪素（元素記号：Ｓｉ）・ゲルマニウム（元素記号：Ｇｅ）混晶の気相成長装置にも好適に用いることができる。
【００１４】
第１の原料供給流路２７は、結晶層を構成する元素に係わる原料気体を予め一括して集合させて流通させるために設置する流路である。第１の原料供給流路２７には、例えば４方バルブ３０〜３２及びそれらと同期して動作する３方バルブ３３〜３５の開閉操作により第１の排気系流路２９より流路を切換えて、結晶層の気相成長に必要とされる全ての原料気体を予め流通させる。４方（ｆｏｕｒ−ｗａｙまたはｃｒｏｓｓ）バルブとは、２つの流路間での切り換えができるバルブである。弁体を開状態とすれば、一流路と別の流路とを導通でき、逆に、弁体を閉とすれば２つの流路を導通を遮断できるバルブである。３方（ｔｈｒｅｅ−ｗａｙ）バルブとは、所謂、三叉バルブであって、一方向に流通する流路へ流体を添加して流通できる機構を有するバルブである。開状態の３方バルブでは、一流路とそれに交差する流路とが導通されている。閉状態では、交差する流路内に流通している流体は一流路に流通されない。例えば、砒化アルミニウム・ガリウム混晶（組成式ＡｌXＧａ1-XＡｓ：０＜Ｘ＜１）を、例えばＭＯＣＶＤ法により気相成長させるに際し、構成元素であるアルミニウム（元素記号：Ａｌ）、ガリウム（元素記号：Ｇａ）、砒素（元素記号：Ａｓ）の原料気体１０、１１、１２を、所望のアルミニウム組成比（＝Ｘ）となる流量混合比をもって予め第１の原料供給流路２７に流通させる。この際、４方バルブ３０、３１、３２を開状態とし、３方バルブ３３、３４、３５を閉として第１の排気系系流路２９から第１の原料供給流路２７への流路の切換えに伴い流量の周期的変動が発生するが、この混合比が不安定な混合ガスは４方バルブ３６を閉とし、３方バルブ３７を閉として気相成長領域３９へは供給せずに第２の排気系流路２９ａへと導き排気処理設備４０によって排気する。
【００１５】
本発明では、予め混合された原料気体の流路２７を気相成長領域の流路２８から排気系流路２９ａへと切り換える機構が付加されているため、第１の原料供給流路２７内に一括して集合されて流通される各々の原料気体の流量変動等が解消された段階で、３方バルブ３７を閉とし、４方バルブ３６を開とし原料気体が流通する原料供給流路２７を第２の排気系流路２９ａから第２の原料供給流路２８へと切換え、原料気体を気相反応領域３９に供給できる。この切り換えに伴い、第１の原料供給流路２７に流通される原料気体の流量は瞬時に変動を被るが、本発明の第１の原料供給流路２７には既に混合比率の安定した原料気体が流通されているため、原料気体の全てが一括して等価に変動を被るに過ぎず、成膜される混晶の組成比の変動は引き起こさない。また、二重のベント／ラン方式に依れば、第２の原料供給流路の効用に依り、第１の原料供給流路に装着する順序に拘わりなく混合比率の安定した原料気体を気相成長領域３９に送出できる。好ましくは、沸点の高い原料程、気相成長領域３９への経路が短くなる原料供給流路の位置に原料を装着する。
【００１６】
上記の二重のベント／ラン方式の配管系を具備する気相成長装置は例えば、硫化セレン化亜鉛・マグネシウム（組成式ＺｎXＭｇ1-XＳ1-YＳｅY：０＜Ｘ，Ｙ＜１）等のＩＩ−ＶＩ族化合物半導体結晶層の気相成長に利用することができる。特に、第ＶＩ族構成元素の原料気体として例えば、沸点が低く室温で気体のセレン化水素（分子式：Ｈ2Ｓｅ）や硫化水素（分子式：Ｈ2Ｓ）を利用すれば、配管系内での原料気体の凝縮を防止できるため、所望の組成比の混晶層を得るに好適に応用できる。
【００１７】
図２の中で、第１の排気系流路２９は結晶層の気相成長には不要の原料気体を流通させておくために、第１の原料供給流路２７に対応させて設置した排気用途の配管である。また、第２の排気系流路２９ａは、第１の排気系流路２９に一括して流通される気相成長には不要の原料気体を集合して排気するために、第２の原料供給流路２８に対応させて設置した排気用途の配管である。第２の原料供給流路２８は気相反応領域（容器）３９に直結させる。一方、第２の排気系流路２９ａは気相反応領域３９には接続されておらず、気相反応領域３９を迂回して直接、排気処理を行う設備４０に接続する構成とする。排気処理設備４０は、燃焼式或いは吸着式除害装置などから構成できる。第１の排気系流路２９と第２の排気系流路２９ａとを接続させる構成とすれば、双方の排気系流路２９、２９ａ内の圧力は均等となる。例えば、３方バルブ３８を開としておけば、排気系流路２９、２９ａ間の圧力差（差圧）を解消できる。また、第１または第２の排気系流路２９、２９ａの内部圧力と、第１または第２の原料供給流路２７、２８との内部圧力を相互に等価とするために、排気系流路に搬送用気体を流入できる機構を設けることが好ましい。例えば、図２において排気系流路２９ａに設けられた搬送用ガス配管４６、および排気系流路２９に設けられた搬送用ガス配管４２がこれにあたり、搬送用ガス配管４６から流入されるガス流量をガス流量計４８により調節して調節することにより、第２の原料供給流路２８及び第２の排気系流路２９ａの内部圧力を互いに均等とすることができ、第１の原料供給流路２７に流通された原料気体を第２の排気系流路２９ａから第２の原料供給流路２８へと流路を変更して流通させるに際し、流量の過渡的変動を抑制するのに効果が挙げられる。
【００１８】
本発明は上述したように、第１の原料供給流路２７を、上記の第２の原料供給流路２８から切り替えて、第２の排気系流路２９ａに接続させる機構を付加させることを特徴とする。第１の原料供給流路２７を第２の排気系流路２９ａに接続する構成とすれば、原料の不要時または原料の混合比が不安定な時に、原料気体を気相反応領域３９を通過させることなく、即ち、気相堆積反応に関与させることなく流通させておくことができる。従って、本発明の配管系統を用いることにより原料ガスの安定した流れを気相反応領域に流入させることができる利点がある。第１の原料供給流路２７の、第２の原料供給流路２８から第２の排気系流路２９ａへの、或いはその逆の流路の変更は、バルブ３６、３７の開閉により行う。バルブ３６を閉状態とし、バルブ３７を開状態とすれば、流路を第２の原料供給流路２８から第２の排気系流路２９ａへと切り換えられる。原料気体の「澱み」を少なくして流路を変更するには、例えば、第２の原料供給流路２８に係わるバルブ３６には圧空動作方式の４方バルブが好適に利用できる。また、第２の排気系流路２９ａに係わるバルブ３７、３８には、３方バルブが好適に利用できる。
【００１９】
本発明では、第１の原料供給流路２７及び第１の排気系流路２９の上流には、各流路２７、２９に個別に搬送ガスを流入させるための流路４１、４２を接続し、且つ、流入させる搬送ガスの流量を独立して制御するための流量制御装置４３、４４を設けて原料気体の供給配管系を構成する（図２参照）。第１の原料供給流路２７及び第１の排気系流路２９に各々、専用に制御された流量をもって搬送用途の気体（搬送ガス）を流入できる配管構成とすることにより、第１の原料供給流路２７と第１の排気系流路２９との間の内部圧力を均等とするに好都合となる。図２に示す配管構成を利用して説明する。例えば、第１の原料供給流路２７及び第１の排気系流路２９に専用に設けた流量計４３、４４により各流路に流通する搬送用途の気体の流量を独立に適宣、調整して両流路２７、２９間の内部の圧力を等価とできる。両流路間２７、２９の内部圧力の均衡を保持することにより、第１の原料供給流路２７から第１の排気系流路２９への、或いはその逆の流路変更時に於ける原料気体の過渡的変動が抑制できる。両流路間２７、２９の圧力差を５×１０2パスカル（Ｐａ）以下とすると過渡的変動を抑制するのに特に効果を奏する。搬送用途の気体は上記の原料の蒸気を随伴する気体と必ずしも同一種とする必要はない。搬送用途として利用できる気体には水素（分子式：Ｈ2）、窒素（分子式：Ｎ2）またはアルゴン（元素記号：Ａｒ）が例示できる。
【００２０】
また本発明では、第１の原料供給流路２７及び第１の排気系流路２９に加えて、第１の流路系統２７、２９に接続する第２の原料供給流路２８及び第２の排気系流路２９ａの上流にも各流路に個別に搬送ガスを流入するための流路４５、４６を接続し、且つ、流入させる搬送ガスの流量を独立して制御するための流量制御装置４７、４８を具備させることが好ましい。図２に例示する如く、第２の原料供給流路２８と第２の排気系流路２９ａとを各々、専用に設けられた流量計４７、４８をもって搬送ガスの流量を独立に調整し制御すれば、両流路間２８、２９ａの内部圧力をより安定させて等価とできる。
【００２１】
例えば、バルブ３６、３７の操作により、２７の流路が２９ａに接続され、４５の流路が２８に接続されている場合、両流路間２８、２９ａの内部圧力の差異を５×１０2パスカル（Ｐａ）以下に保てば、第２の流路２８、２９ａ間の切換え、即ち２７の流路を２８に、４５の流路を閉状態または２９ａに接続する際の、流量の過渡的変動を抑制するのに効果が奏される。搬送用途の気体は上記の原料の蒸気を随伴する気体並びに第１の流路系統とは必ずしも同一種とする必要はなく、水素（Ｈ2）、窒素（Ｎ2）またはアルゴン（Ａｒ）等が利用できる。
【００２２】
本発明の実施の形態をより詳しく例示する。図３にリン化ガリウム・インジウム（組成式ＧａXＩｎ1-XＰ：０≦Ｘ≦１）系結晶層のＭＯＣＶＤ成長に好都合であり、特に、２次元電子電界効果型トランジスタや高感度ホール素子等の高い電子移動度特性の発現に必須の急峻なヘテロ接合界面の形成に好適な原料供給配管系の構成を例示する。本構成例では、第ＩＩＩ族構成元素の原料である有機ＩＩＩ族化合物と第Ｖ族元素源の会合に因る複合体（ポリマー）化反応を回避する目的で、第ＩＩＩ族元素原料供給用途の配管系４９とは別にホスフィン（分子式：ＰＨ3）等の第Ｖ族元素源（図３に図示せず）を供給するための配管系５０を別個に配置している。第ＩＩＩ族及び第Ｖ族構成元素源に係わる配管系４９、５０は何れもベント／ラン方式により構成されている。第ＩＩＩ族源及び第Ｖ族源を別々に個別に供給配管系４９、５０を設置することにより各源相互の会合反応を回避できるに併せて、各原料気体を過渡的な流量の変動を抑制しつつ供給できる。これにより、組成変動が少なく、且つ表面粗さが小さく平滑な結晶層をもって、組成の急峻性に優れるエピタキシャルヘテロ接合構造の気相成長が達成される。本構成例に依ってもたらされるヘテロ接合界面の急峻性の良好さは、例えば、透過型電子顕微鏡（英略称：ＴＥＭ）を利用した電子線干渉フリンジ法（ＣＡＴ法）（外村 彰編、「電子顕微鏡技術」（丸善（株）、平成元年８月３１日発行）、８３〜９０頁参照）等の評価手段により測定することができる。
【００２３】
図３の原料供給配管系は、本発明の図２の原料供給配管系を２系列有する構造（Ｄｕｐｌｉｃａｔｅ Ｖｅｎｔ−Ｒｕｎ構造）である。本発明に依るヘテロ接合界面を急峻とできる効果は、具備する原料供給配管系の数量により損なわれることはない。複数の原料供給配管系が具備されている場合であっても、本発明が記載するところの第２のベント／ラン機構により瞬時に原料気体の流路を変更できるからである。また、気相成長領域３９との相対的配置において、例えば、第ＩＩＩ族と第Ｖ族との元素原料供給用途の配管系の配置の順序に特に規定はない。ＩＩＩ−Ｖ族化合物半導体結晶層をＭＯＣＶＤ装置にあって、原料とする第ＩＩＩ族元素の有機金属化合物は第Ｖ族元素源とする第Ｖ族元素の水素化物に比較して融点、沸点が共に高い。例えば、トリメチルアルミニウム（（ＣＨ3）3Ａｌ）の融点が約１５℃であるのに対し、アルシン（ＡｓＨ3）の融点は約−１１７℃である。従って、原料供給流路内での凝縮を抑制するためには、沸点のより高い原料を付帯する原料供給系を気相成長領域により近接して配置するのが好ましい。また、通常、室温あるいはそれ以上の温度に保持されるＩＩＩ−Ｖ族或いはＩＩ−ＶＩ族化合物半導体用途の気相成長装置の配管系にあって、第Ｖ族或いは第ＶＩ族の水素化物は沸点が室温より遙かに低いために、凝縮に因る供給量の低下或いは濃度減少を来さずに気相成長領域に効率的に送出できる。このため、第Ｖ族或いは第ＶＩ族元素の蒸発に因る化合物半導体結晶層の表面状態の劣化を防止するに効果が奏される。
【００２４】
図４は本発明の他の実施形態を示す原料供給配管系統の概略図である。本例の配管系の特徴は原料の種別、例えば、ＩＩＩ族元素原料とＶ族構成元素原料の種別に拘わらず、一括して集合して原料気体を反応領域３９に流入できることにある。第１の原料供給流路２７には、例えば、第ＩＩＩ族元素原料１０、１１と第Ｖ族元素原料５１とが一括して予め流通できる構成となっている。第１の原料供給流路２７に対応して、原料を排気するために第１の排気系流路２９が配備されている。第１の原料供給流路２７はその内部を流れる原料気体を一括して気相反応領域３９に供給するための第２の原料供給流路２８が接続されている。第１の排気系流路２９は第２の排気系流路２９ａに直接、接続されている。この配管系は例えば、原料相互の複合体化反応が比較的穏やかである砒化ガリウム・インジウム（組成式ＧａXＩｎ1-XＡｓ：０≦Ｘ≦１）等のアルシン（分子式：ＡｓＨ3）を砒素（Ａｓ）源とするＩＩＩ−Ｖ族化合物半導体結晶層の気相成長に好適である。特に、界面急峻性に優れるヘテロ接合構造が要求される例えば、砒化アルミニウム・インジウム（組成式ＡｌXＩｎ1-XＡｓ：０≦Ｘ≦１）／ＧａXＩｎ1-XＡｓ（０≦Ｘ≦１）系ＴＥＧＦＥＴ用途のエピタキシャル積層構造体の気相成長に適する。
【００２５】
図５に示すのは、図４に例示した配管系の一変形例であって、特に、揮発性に富む構成元素を含む化合物半導体結晶層の気相成長に好適な配管系である。例えば、図５に例示する原料気体配管系には、図４の基本的な配管系に加えて、揮発性の高い構成元素源を第２の原料供給流路２８または第２の排気系流路２９ａに流通させるための配管系５２が新たに配備されている。第２の原料供給流路２８と第２の排気系流路２９ａと切換えはバルブ５３、５４の開閉操作により行う。例えば、原料気体を第１の原料供給流路２７及び第２の原料供給流路２８を介して流通して第１の結晶層の気相成長を終了させた後、原料気体の流路を第２の原料供給流路２８から第２の排気系流路２９ａへと変更する。然る後、第１の原料供給流路２７に第２の結晶層を気相成長させるに必要な原料気体を改めて集合させて流通させる。定常流となすために暫時、原料気体を第１の原料供給流路２７に流通させている間において、新たに設けた配管系５２を利用して揮発性構成元素の気体原料を第２の原料供給流路２８を介して気相成長反応領域３９に流入させる。第２の結晶層を気相成長させるための原料気体の流れが定常的になるのを見計らった後、揮発性構成元素の気体原料を第２の原料供給流路２８より第２の排気系流路２９ａに切換えるに合わせて、第２の結晶層を気相成長させるための原料気体を第１及び第２の原料供給流路２７、２８を介して気相反応領域に供給する。
【００２６】
これにより、第１の結晶層の気相成長終了後、第２の結晶層の気相成長が開始されるに至る間の第１の結晶層の表面からの揮発性構成元素の揮散を抑制する作用が発揮される。この作用により、第１の結晶層の表面状態は良好に保持され、しいては、その上層として表面状態に優れる第２の結晶層の気相成長が達成される効果が挙げられる。この様な作用、効果は例えば、約１０００℃近傍の高温での気相成長に因り窒素（元素記号：Ｎ）の揮散が顕著に発生する窒化ガリウム・インジウム（組成式ＧａXＩｎ1-XＮ：０≦Ｘ≦１）系結晶層の気相成長に好適に用いられる。
【００２７】
本発明に係わる気相成長装置及びその気相成長装置を用いる成膜方法に依れば、上述の如く組成の急峻性に優れる半導体接合界面がもたらされる。また、優れた組成急峻性をもって接合された半導体接合構造を内包する積層構造体からは優れた電気的特性を発揮する例えば、ショットキー（Ｓｃｈｏｔｔｋｙ）接合型電界効果型トランジスタ（ＭＥＳＦＥＴ）やヘテロ接合バイポーラトランジスタ（ＨＢＴ）等の半導体素子が構成できる効果がある。
【００２８】
例えば、マイクロ波或いはミリ波帯域の高周波帯域で動作可能な高周波半導体素子の一例として、砒化アルミニウム・ガリウム（ＡｌXＧａ1-XＡｓ：一般には、０．２≦Ｘ≦０．４）からなるスペーサ層或いは電子供給層と、砒化ガリウム・インジウム（ＧａXＩｎ1-XＡｓ：一般には、０．７≦Ｘ≦０．９）からなるチャネル層とのヘテロ接合構造を内包する歪超格子型ＴＥＧＦＥＴがある。このプシュードモーフィック（ｐｓｅｕｄｏｍｏｒｐｈｉｃ）型ＴＥＧＦＥＴ用途の積層構造体を得るに際しても、本発明の気相成長装置及び成膜方法に依れば、アルミニウム（Ａｌ）組成並びにインジウム（Ｉｎ）組成が急峻に変化させられる。このため、ＡｌXＧａ1-XＡｓ／ＧａXＩｎ1-XＡｓヘテロ接合界面において、ＣＡＴ像上に電子線干渉縞（フリンジ）の曲折を発生させない急峻なヘテロ接合界面が形成できる。電子供給層或いはスペーサ層とチャネル層とのヘテロ接合界面の急峻性の向上は、同ヘテロ接合界面近傍の領域に於ける低次元電子の局在を促すと共に、高い電子移動度をもたらすに寄与できる。
【００２９】
本発明の手段に依る電子移動度の向上の効果は例えば、砒化アルミニウム・ガリウムと砒化ガリウムとの格子整合系ヘテロ接合構造を具備するＴＥＧＦＥＴ用途積層構造体においても顕現される。例えば、シートキャリア（ｓｈｅｅｔ ｃａｒｒｉｅｒ）濃度を約１．２×１０12ｃｍ-3とする積層構造体の７７ケルビン（Ｋ；液体窒素温度）に於ける電子移動度は従来例では約７０，０００ｃｍ2／Ｖ・ｓから約１００，０００ｃｍ2／Ｖ・ｓの間で変動を来すのに対し、本発明に依れば、約１００，０００ｃｍ2／Ｖ・を越える高い２次元電子に係わる移動度が安定して顕現される。歪超格子積層系或いは格子整合積層系に拘わらず、高電子移動度を顕現できる急峻な例えば、スペーサ層等とチャネル層とのヘテロ接合界面構造を内包する積層構造体からは、例えば、相互コンダクタンス（ｇｍ）（古川 静二郎他著、「電子デバイス工学」（１９９５年１０月１６日、（株）森北出版発行、第１版第８刷）、７５〜７７頁参照）に優れ、従って、雑音指数の小さな低雑音電界効果型トランジスタが構成できる利点がある。
【００３０】
本発明の気相成長装置並びに成膜方法に依り安定的に達成される急峻なヘテロ接合界面を保有するＡｌXＧａ1-XＡｓ／ＧａＡｓ格子整合積層系、ＡｌXＩｎ1-XＡｓ／ＧａXＩｎ1-XＡｓ格子整合積層系またはＡｌXＧａ1-XＡｓ／ＧａXＩｎ1-XＡｓ歪超格子積層系からなるＦＥＴ用途積層構造体から構成される特に、雑音指数（英略称：ＮＦ）に優れる低雑音ＴＥＧＦＥＴは例えば、Ｌ帯（慣用的に１．０〜２．６ＧＨｚ帯）ローノイズ（ｌｏｗ−ｎｏｉｓｅ）増幅器、１２ギガヘルツ（ＧＨｚ）及び１８ＧＨｚ帯低雑音増幅器、また、４５ＧＨｚ帯ミリ波低雑音増幅器、１００ＧＨｚ帯基地局用ミリ波発信（局発）用の通信機器等を構成するに有効に利用することができる。また、本発明に依り達成されるヘテロ接合界面の急峻化に依って、ヘテロ室温において６、０００ｃｍ2／Ｖ・ｓを越え、また、液体窒素温度（７７Ｋ）で３０，０００ｃｍ2／Ｖ・ｓを越え、更に温度１．６Ｋにおいて１５０、０００ｃｍ2／Ｖ・ｓを越える高い電子移動度を発現する２次元電子雲（ｔｗｏ−ｄｉｍｅｎｓｉｏｎａｌ ｅｌｅｃｔｒｏｎ ｇａｓ）を内包するＧａXＩｎ1-XＰ／ＧａXＩｎ1-XＡｓ系積層構造体（Ｔｈｅ Ｔｅｎｔｈ Ｉｎｔｅｒｎａｔｉｏｎａｌ Ｃｏｎｆｅｒｅｎｃｅ ｏｎ Ｍｅｔａｌｏｒｇａｎｉｃ Ｖａｐｏｒ Ｐｈａｓｅ Ｅｐｉｔａｘｙ（ＩＣＭＯＶＰＥーＸ）（Ｊｕｎｅ ５−９，２０００）、Ｗｏｒｋｂｏｏｋ、Ｗｅ−Ｐ２０、２３６頁参照）から構成される低雑音或いは電力（ｐｏｗｅｒ）ＴＥＧＦＥＴは、例えば、Ｌ帯高周波低雑音増幅器或いはマイクロ波帯域及びミリ波帯域の高周波発信器を構成するに有効に利用できる。
【００３１】
また、本発明の気相成長装置並びに成膜方法を利用して形成した急峻なヘテロ接合界面を備え、高い電子移動度が付与されている積層構造体からは、例えば、高い積感度（ｐｒｏｄｕｃｔ−ｓｅｎｓｉｔｉｖｉｔｙ）を発現するホール（Ｈａｌｌ）素子が構成できる。例えば、リン化インジウム（化学式：ＩｎＰ）と砒化ガリウム・インジウム（Ｇａ0.47Ｉｎ0.53Ａｓ）との格子整合系単一ヘテロ接合構造を具備するホール素子において（Ｊ．Ｅｌｃｔｒｏｎ．Ｍａｔｅｒ．，Ｖｏｌ．２５，Ｎｏ．３（１９９６）、４０７〜４０９頁参照）、本発明の気相成長装置並びに成膜方法を利用すれば、ガリウム（Ｇａ）組成、砒素（Ａｓ）組成及びリン（Ｐ）組成が急峻に変化したヘテロ接合界面が構成できるため、室温において９、０００ｃｍ2／Ｖ・ｓを越える高い電子移動度が安定して顕現される。特に、ハロゲンＶＰＥ成長法やＭＢＥ成長法に比較して、リンを構成元素とするＩＩＩ−Ｖ族化合物半導体層の成長に好適であるＭＯＣＶＤ法にあって、本発明に係わる気相成長装置並びに成膜方法を利用するＭＯＣＶＤ成長手段に依れば、高い電子移動度を安定して顕現できるヘテロ接合構造を得るに優位となる（１９９２年（平成４年）秋季第５３回応用物理学会学術講演会予稿集第１分冊（Ｅｘｔｅｎｄｅｄ Ａｂｓｔｒａｃｔｓ（Ｔｈｅ ５３ｒｄ Ａｕｔｕｍｎ Ｍｅｅｔｉｎｇ、１９９２）；Ｔｈｅ Ｊａｐａｎ Ｓｏｃｉｅｔｙ ｏｆ Ａｐｐｌｉｅｄ Ｐｈｙｓｉｃｓ Ｎｏ．１）（１９９２年９月１６日、（社）応用物理学会発行）、１８ａ−ＺＥ−３、２８３頁参照）。高い電子移動度が安定して獲得できることにより、室温に於ける積感度にして８００Ｖ／Ａ・Ｔ（ボルト／アンペア・テスラ）を越える高感度のＧａ0.47Ｉｎ0.53Ａｓ／ＩｎＰヘテロ接合ホール素子（上記のＪ．Ｅｌｃｔｒｏｎ．Ｍａｔｅｒ．，Ｖｏｌ．２５，（１９９６）参照）が安定してもたらされる利点がある
また、本発明の気相成長装置並びに成膜方法に依り安定的に達成される急峻なヘテロ接合界面の発現は接合界面近傍の領域に於けるキャリア（ｃａｒｒｉｅｒ）の局在化を促進させるに効果を奏する。局在化した電子（２次元電子）の高移動度特性を利用するホール素子、例えば、ＡｌXＧａ1-XＡｓ／ＧａＡｓ或いはＧａXＩｎ1-XＡｓ／ＩｎＰ格子整合積層系からなる２次元電子ホール素子からは、その高感度特性によって、例えば、磁場強度測定器、地磁気測定器、回転計、距離計などの磁電変換素子としてのホール素子の特徴を生かしたセンサー等が構成できる（ＩＥＥＥ Ｔｒａｎｓ．Ｅｌｅｃｔｒｏｎ Ｄｅｖ．，ＥＤ−４１（３）（１９９４）、３１５頁参照）。特に、ヘテロ接合界面の急峻化が達成されてなるホール素子、例えば、Ｇａ0.47Ｉｎ0.53Ａｓ／ＩｎＰ系２次元電子ホール素子は、単位動作電流、単位磁場強度下においてホール（Ｈａｌｌ）電圧が大である、所謂、積感度が従来例の７６０Ｖ／Ａ・Ｔ（上記のＩＥＥＥ Ｔｒａｎｓ．Ｅｌｅｃｔｒｏｎ Ｄｅｖ．、ＥＤ−４１（３）参照）に比較して改善されていることから（上記の▲１▼Ｊ．Ｅｌｃｔｒｏｎ．Ｍａｔｅｒ．，Ｖｏｌ．２５（１９９６）、４０７〜４０９頁参照）及び▲２▼Ｅｘｔｅｎｄｅｄ Ａｂｓｔｒａｃｔｓ（Ｔｈｅ ５３ｒｄ Ａｕｔｕｍｎ Ｍｅｅｔｉｎｇ、１９９２参照）、計測器の測定感度の向上が帰結され、高感度の計測器が提供できる効果がある。
【００３２】
また、本発明の気相成長装置並びに成膜方法を利用すれば、多重ヘテロ構造の接合構造を良好な急峻性をもって構成することができる。例えば、良好なインジウム（Ｉｎ）組成の急峻性をもって、窒化ガリウム（化学式：ＧａＮ）と窒化ガリウム・インジウム（組成式ＧａXＩｎ1-XＮ：０＜Ｘ＜１）との単一又は二重ヘテロ接合構造、歪超格子（ｓｔｒａｉｎｅｄ−ｌａｙｅｒ ｓｕｐｅｒ−ｌａｔｔｉｃｅ）構造または単一（ｓｉｎｇｌｅ−）及び多重量子（ｍｕｌｔｉ−ｑｕａｎｔｕｍ ｗｅｌｌ）構造が形成できる。例えば、ＧａXＩｎ1-XＮ／ＧａＮヘテロ接合構造からなる発光部を具備する窒化ガリウム・インジウム系発光ダイオード（英略称：ＬＥＤ）またはレーザーダイオード（英略称：ＬＤ）にあって、ヘテロ接合界面の急峻性は発光（出射光）の単色性に影響を及ぼす重要な因子である（特開平１０−１６８２４１号公報参照）。量子井戸（ｑｕａｎｔｕｍ ｗｅｌｌ）構造にあって、井戸（ｗｅｌｌ）層と障壁（ｂａｒｒｉｅｒ）層とのヘテロ接合界面に於けるインジウム（Ｉｎ）組成の急峻性が良好であり、且つ急峻性が均一であると優れた単色性の発光を帰結するに寄与できる。本発明の気相成長装置及び成膜方法に依れば、単一量子井戸（英略称：ＳＱＷ）或いは多重量子井戸（英略称：ＭＱＷ）構造も良好なヘテロ接合界面の急峻性をもって安定して形成することができる。従って、これより、発光の単色性に優れる窒化ガリウム・インジウム系青色ＬＥＤや青色ＬＤが構成できる利点がある。
【００３３】
【実施例】
（実施例１）
リン化ガリウム・インジウム（組成式Ｇａ0.51Ｉｎ0.49Ｐ）／Ｇａ0.80Ｉｎ0.20Ａｓヘテロ接合系高移動度電界効果型トランジスタ用途のエピタキシャル積層構造体の気相成長装置を例にして本発明を具体的に説明する。
【００３４】
本実施例に於ける配管系の概略を図６に示す。配管は２重のベント／ラン方式（Ｄｕａｌ Ａｌｌｉｇｎ Ｖｅｎｔ−Ｒｕｎ方式）を基本として構成されている。第１の原料供給流路２７には、ガリウム（Ｇａ）源１０としてトリメチルガリウム（分子式：（ＣＨ3）3Ｇａ）、及びインジウム（Ｉｎ）源１１としてトリメチルインジウム（分子式：（ＣＨ3）3Ｉｎ）が配備されている。上記の第ＩＩＩ族元素源１０〜１１には、それらの原料の蒸気を随伴して搬送するための水素ガスを供給するための配管が各原料１０〜１１に個別に設けられている。各原料１０〜１１の蒸気を随伴する水素ガスは必要に応じて第１の原料供給流路２７または第１の排気系流路２９かに選択されて流通される。第１の排気系流路２９は３方バルブ３８を介して第２の排気系流路２９ａに接続されている。
【００３５】
第１の原料供給流路２７には上記のＩＩＩ族原料に加えて砒素（Ａｓ）源５１とするアルシン（ＡｓＨ3）を流入できる構成としてある。また、アルシンを供給するための配管は中途で分岐させて（配管５２）、第２の原料供給流路２８または第２の排気系流路２９ａの何れかの流路に圧空動作式バルブ５３、５４の開閉操作により切換える。バルブ５３、５４へは電磁弁を介して圧縮ガスが送気され、弁体の開閉が操作される。第１の原料供給流路２７内に流通される原料気体は第２の原料供給流路２８、または第２の排気系流路２９ａの何れかにバルブ３６、３７の切換えにより流通できる構成となっている。第２の原料供給流路２８は気相成長領域３９に直結されている。第２の排気系流路２９ａの下流には原料気体を除害するための除害設備４０が配備されている。
【００３６】
第１の原料供給流路２７、排気系流路２９及び第２の原料供給流路２８、排気系流路２９ａの双方の配管系の上流側には、流路内部の圧力を同一となすための搬送ガス配管と電子式質量流量計（英略称：ＭＦＣ）４３、４４、４７、４８が配置してある。気相反応領域３９に原料気体を直接、流入させる第２の原料供給流路２８内の流量は、一般には、第１の原料供給流路２７内の流量よりも多量とする。また、原料供給流路２７、２８と排気系流路２９、２９ａとの差圧を解消して、気体原料の流路を変更時に両流路間の圧力差に起因して発生する原料気体の流量変動を抑制する目的で、第１の原料供給流路２７と第１の排気系流路２９との間の圧力差を計測するための差圧計５５を設ける。また、同一の目的で第２の原料供給流路２８と第２の排気系流路２９ａの間にも差圧計５６を配置する。
【００３７】
上記の配管を具備したＭＯＣＶＤ装置を利用してＧａ0.51Ｉｎ0.49Ｐ／Ｇａ0.80Ｉｎ0.20Ａｓ２次元電子電界効果型トランジスタ用途のエピタキシャル積層構造体を気相成長させる場合を例にして配管系の操作手段を詳述する。先ず、第１の原料供給流路２７及び第１の排気系流路２９の内部圧力を略同等となすために、ＭＦＣ４３、４４により毎分３〜５リットル程度に流量を制御して水素ガスを流通させる。同じく第２の原料供給流路２８及び第２の排気系流路２９ａ間の差圧を解消すべく、各々の流路について毎分約５リットル〜約２０リットル程度の流量に独立に制御された水素ガスを予め流通させておく。原料供給流路２７、２８と排気系流路２９、２９ａとの差圧は差圧計５５、５６をもって約５×１０2パスカル（単位Ｐａ）、好ましくは約２×１０2Ｐａ以内に抑制しておく。この条件下において、気相反応炉内の気相成長反応領域３９に載置した｛１００｝２゜オフ砒化ガリウム（ＧａＡｓ）単結晶基板５９の表面に配管５２を利用してアルシンを供給しつつ、ＧａＡｓ単結晶基板５９の温度を約６００℃〜約７００℃程度のエピタキシャル成長温度に加熱する。
【００３８】
次に、基板５９をエピタキシャル温度に暫時、保持して基板５９の温度を安定させている間に、アンドープＧａＡｓからなる高抵抗の緩衝層６０を気相成長させるために必要な、水素ガスに随伴されるガリウム源（トリメチルガリウム）を第１の排気系配管２９に流通させておく。また、ＭＦＣにより所定の流量に制御された砒素源（アルシン）５１を第１の排気系配管２９に予め流通させておく。基板５９の温度が安定し、また、ガリウム源及び砒素源の流量が安定するのを見計らって、両原料気体の流路を第１の排気系配管２９に設けられいる３方バルブ３３、３４を閉状態とし、それに同期させて第１の原料供給流路２７の４方バルブ３０、３１を開状態とし、第１の原料供給流路２７へ流路を変更する。これより、ガリウム源及び砒素源を第１の反応流路２７を介して第２の排気系流路２９ａに流通させておく。次に、原料気体の流路を、第２の排気系流路２９ａに付属する３方バルブ３７を閉とし、同時に第２の原料供給流路２８に付属する４方バルブ３６を開とし、ＧａＡｓ緩衝層６０の気相成長を開始する。所定の層厚の緩衝層が気相成長する迄、気相反応領域への原料気体の供給を継続する。然る後、原料気体の流路をバルブ３６、３７の開閉状態を逆転させて第２の原料供給流路２８より第２の排気系流路２９ａへと変更して、ＧａＡｓ緩衝層６０の気相成長を終了する。
【００３９】
ＧａＡｓ緩衝層６０の成長終了後においても、ＧａＡｓ緩衝層６０の表面からの砒素の揮散を防止するために、アルシンガスは配管５２を介して継続して気相反応領域に供給し続けて、ＧａＡｓ緩衝層６０の表面状態を良好に保持する。その間に、Ｇａ0.80Ｉｎ0.20Ａｓ電子走行層（ｃｈａｎｎｅｌ層）６１を成長するために、予め第１の排気系流路２７に定常的に流通させていたトリメチルインジウムの蒸気を随伴する水素ガスをインジウム源１１用配管に専用に設けられた３方バルブ３４を閉とし、同期させて４方バルブ３１を開として第１の原料供給流路２７に流通させる。併せて、第１の原料供給流路２７に既に流通させているガリウムの原料気体の流量をガリウム組成比が０．８０となる様に調整し、制御する。所望の組成比に見合う様に流量比率を予め、制御された原料気体の混合気体を第１の原料供給流路２７を介して第２の排気系流路２９ａに流通させる。暫時、流通して安定な流通とした後、３方バルブ３７を閉とし、逆に４方バルブ３６を開として、流路を第２の原料供給流路２８に切換える。これより、Ｇａ0.80Ｉｎ0.20Ａｓチャネル層６１の気相成長を開始する。アンドープチャネル層６１の層厚が数十ナノメータ（ｎｍ）程度となった時点で、原料気体の流路を再び、第２の原料供給流路２８から第２の排気系流路２９ａに戻してチャネル層の気相成長を終了する。チャネル層６１の終了後も配管５２からアルシンガスの供給を継続して、砒素の揮散に因るチャネル層６１の表面状態を劣化を防止しておく。
【００４０】
砒素源を配管５２を利用して流通している間にガリウム源１０及びインジウム源１１の第１の原料供給流路２７に流通する流量をＭＦＣによりガリウム組成比を０．５１とするｎ形Ｇａ0.51Ｉｎ0.49Ｐ層を成長できる流量をもって流通し始める。この混合した原料気体を第１の原料供給流路２７を介して第２の排気系流路２９ａに流通させる状態としておく。次に、配管５２を通しての砒素源（アルシン）の気相反応領域３９への供給を停止する。それと同時或いは数秒を経過した後に、別の配管５７を介してリン（Ｐ）源（図６に図示せず）とするホスフィン（ＰＨ3）を気相反応領域３９に供給し始める。所望の流量のリン源の過渡的な流量の変動が解消する迄暫時、経過させた後、原料気体の流路を第２の排気系流路２９ａより第２の原料供給流路２８に切換えて、ｎ形のＧａ0.51Ｉｎ0.49Ｐ層を電子供給層６２として気相成長させる。ｎ形のＧａ0.51Ｉｎ0.49Ｐ電子供給層の形成にあたり、珪素（Ｓｉ）等のドーピング源（図６に図示せず）を専用の配管５８を利用して供給する。ｎ形ドーピングガスの流量は一般には、電子供給層６２の室温近傍でのキャリア濃度が大凡、約１×１０18ｃｍ-3〜約３×１０18ｃｍ-3となる様に設定する。原料気体の流路を第２の排気流路２９ａから第２の原料供給流路２８に変更し、約２０ｎｍから約３０ｎｍ程度の層厚の電子供給層６２の成長を行う。成長終了後はリン源の供給を暫く継続してＧａ0.51Ｉｎ0.49Ｐ電子供給層６２の表面からのリンの揮散を抑制して同層６２の表面を良好に保持する。
【００４１】
ｎ形Ｇａ0.51Ｉｎ0.49Ｐ電子供給層６２の表面に更に、例えば、アンドープの高抵抗Ｇａ0.51Ｉｎ0.49Ｐからなるショットキー（Ｓｃｈｏｔｔｋｙ）ゲート（ｇａｔｅ）形成層やｎ形ＧａＡｓキャップ（ｃａｐ）層等を気相成長させる際にも、上記の流路変更手段に基づき同様に実行する。即ち、所望の結晶層を得るのに必要とされる原料気体を、一旦第１の反応流路２７に予め集合させた後、改めて第２の原料供給流路、排気系流路での流路の変更により、一括して気相反応領域に供給する手段をもって気相成長を果たす。図７は本発明に記載の手段に則り気相成長させたＧａ0.51Ｉｎ0.49Ｐ／Ｇａ0.80Ｉｎ0.20Ａｓヘテロ接合系ＴＥＧＦＥＴ用途の積層構造体のチャネル層６１／電子供給層６２ヘテロ接合界面６４の急峻性の一例を示すＣＡＴ（ｃｏｎｔｒａｓｔ ａｎｌｙｓｉｓ ｂｙ ｔｈｉｃｋｎｅｓｓ ｆｒｉｎｇｅ）像の模写図である。図７に示する如く本発明に係わる２重のベント／ラン方式の配管系を具備する気相成長装置に依れば、界面急峻性に優れるヘテロ接合構造が得られる。
【００４２】
急峻化が果たされたＧａ0.51Ｉｎ0.49Ｐ／Ｇａ0.80Ｉｎ0.20Ａｓヘテロ接合構造では、図８に例示する如くのホール（Ｈａｌｌ）電圧に関するシュブニコフ−ド・ハース（Ｓｈｕｂｎｉｋｏｖ−ｄｅ Ｈａａｓ：ＳｄＨ）振動が観測される。また、本実施例に記載の手段により成長されたＴＥＧＦＥＴ用途の積層構造体では、例えば、室温でシート（ｓｈｅｅｔ）キャリア濃度（ｎs：単位ｃｍ-2）約１．４×１０12ｃｍ-2において約６，３００（ｃｍ2／Ｖ・ｓ）の高い移動度（μ：単位ｃｍ2／Ｖ・ｓ）が帰結される。また、７７ケルビン（Ｋ）ではｎs＝１．４×１０12ｃｍ-2でμ＝３１，６００ｃｍ2／Ｖ・ｓの高移動度が発現される。更に低温の１．６Ｋでは約２００，０００ｃｍ2／Ｖ・ｓの高電子移動度が得られる。従って、本発明に係わる構成からなる配管系を備えた気相成長装置に依れば、２次元電子を顕現できる接合界面の急峻性に優れるヘテロ接合エピタキシャル構造体を気相成長できる。
【００４３】
（比較例）
図１に例示する従来の単一のベント／ラン方式の配管系を具備したＭＯＣＶＤ装置により実施例と同一の流量条件でＧａ0.51Ｉｎ0.49Ｐ／Ｇａ0.80Ｉｎ0.20Ａｓ電界効果型トランジスタ用途の積層構造体を形成した。図９にこの従来の流路の変更手段を利用した積層構造体のＣＡＴ像の模写図を掲示する。
【００４４】
本比較例に従来のベント／ラン方式により原料気体を流通させる方式では、上記の実施例の如く集合させて流通させている気体原料を気相反応領域に一遍に流通できない。新たに必要となった原料気体を単発的に原料供給流路にその都度、混入させる必要がある。このため、例えば、ＧａＡｓ緩衝層の気相成長後にＧａ0.80Ｉｎ0.20Ａｓチャネル層の気相成長を開始するために、新たにインジウム源を原料供給流路に混入させる必要がある。既に、定常的な流通となっているガリウム源及び砒素源に対し、新たに添加されたインジウム源の流量は過渡的に変動する。所定の流量に保持されたインジウム源を、予め排気系流路に流通しておき、原料供給流路に瞬時に流路を切換えたところで、流路の変更に伴う流量の周期的な変動を完全に回避できるのは極めて希有である。且つ、原料供給流路は気相成長流路に直結しているため、インジウム源の過渡的な流量の変動は、気相反応領域に於けるインジウム源とガリウム源との流量混合比を不安定とする。図９のＣＡＴ像のＧａＡｓ緩衝層６０とＧａ0.80Ｉｎ0.20Ａｓチャネル層６１とのヘテロ接合界面６３よりチャネル層６１側の内部に於ける電子線干渉縞６５上の曲折部の発生は、この原料気体相互の混合比率の不安定性により混晶組成に変動を来していることを示している。
【００４５】
Ｇａ0.80Ｉｎ0.20Ａｓチャネル層上にＧａ0.51Ｉｎ0.49Ｐ電子供給層を成長させるに際しても従来の配管系では同様の流量の過渡的変動が発生する。この場合、ガリウム組成比を０．５１とするＧａ0.51Ｉｎ0.49Ｐ層を得るべく所定の流量をもって混合されたガリウム源とインジウム源とを、気相反応領域に直結する原料供給流路に同時に流通させる必要がある。即ち、複数の構成元素の原料気体を同時に原料供給流路に導入させる必要が生ずる。第ＩＩＩ族構成元素の双方を唯一の原料供給流路に、しかも同一時期に導入すると、双方の気体原料の流量の変動は多大となる。このため、Ｇａ0.80Ｉｎ0.20Ａｓチャネル層／Ｇａ0.51Ｉｎ0.49Ｐ電子供給層とのヘテロ接合界面に於ける組成の急峻性は尚一層、劣るものとなる。図９のＣＡＴ像には、緩衝層６０／チャネル層６１の接合界面６３に於けるよりも、チャネル層６１／電子供給層６２とのヘテロ接合界面６４に於ける組成の急峻性がより劣悪であることを如実に示している。
【００４６】
また、この様な急峻性に欠けるＧａ0.80Ｉｎ0.20Ａｓ／Ｇａ0.51Ｉｎ0.49Ｐヘテロ接合界面構造からは、例えば、図１０に例示する様に、量子ホール効果測定において２次元電子の実在を表すホール（Ｈａｌｌ）抵抗の振動はさして明瞭ではない。このため、得られる室温移動度も例えば、ｎs＝１．４×１０12ｃｍ-2において、平均して約４，０００ｃｍ2／Ｖ・ｓから約５，０００ｃｍ2／Ｖ・ｓ程度に留まってしまう。即ち、従来の配管構成からなる気相成長装置では、本発明に係わる気相成長装置に依る得られたような、ヘテロ接合界面の急峻性及び移動度特性に優れた積層構造体は得られない。
【００４７】
（実施例２）
本発明の気相成長装置を利用して得たリン化ガリウム・インジウム（Ｇａ0.51Ｉｎ0.49Ｐ）／Ｇａ0.80Ｉｎ0.20Ａｓ系ヘテロ接合積層構造体から高移動度電界効果型トランジスタを構成する場合を例にして本発明を具体的に説明する。
【００４８】
本実施例に係わる２次元電子電界効果型トランジスタ（ＴＥＧＦＥＴ）６６の断面構造を図１１に模式的に示す。同図において実施例１に記載と同一の構成要素には同一の図番を付してその説明を省略する。
【００４９】
ＴＥＧＦＥＴ６６用途の積層構造体６７は、実施例１に記載の手法及び手順に従い構成した。本実施例では、キャリア濃度を５×１０15ｃｍ-3以下とし、層厚を１０ｎｍとするアンドープでｎ形Ｇａ0.80Ｉｎ0.20Ａｓ成長層をチャネル層６１とした。また、キャリア濃度を５×１０18ｃｍ-3とし、層厚を１５ｎｍとする珪素（Ｓｉ）ドープｎ形Ｇａ0.51Ｉｎ0.49Ｐ成長層を電子供給層６２とした。更に、Ｇａ0.51Ｉｎ0.49Ｐ電子供給層６２の表面上には、キャリア濃度を２×１０16ｃｍ-3とし、層厚を１０ｎｍとするアンドープＧａ0.51Ｉｎ0.49Ｐ成長層をゲート（ｇａｔｅ）コンタクト層７２として積層した。同層７２の表面上には、キャリア濃度を３×１０18ｃｍ-3とし、層厚を４０ｎｍとするＳｉドープＧａＡｓ成長層をオーミックコンタクト層６８として積層した。
【００５０】
特に、Ｇａ0.80Ｉｎ0.20Ａｓチャネル層６１とＧａ0.51Ｉｎ0.49Ｐ電子供給層６２とのヘテロ接合界面を確実に急峻となすために、チャネル層６１の成長終了後、電子供給層６２の成長を開始する以前に原料供給流路２７、２９間の差圧を改めて同一とする措置を施した（図６参照）。具体的には、第１の原料供給流路２７と第１の排気系流路２９との間の差圧計５５で計測される差圧を１×１０2Ｐａとした。また、第２の原料気体流路２８と第２の排気系流路２９ａとの差圧計５６で計測される差圧を同じく１×１０2Ｐａとした。第１の排気系流路２９と第２の排気系流路２９ａの内部圧力は、３方開閉バルブ３８を開状態として双方の流路２９，２９ａを導通させて同等としてある。これにより、同等の内部圧力の排気系流路２９、２９ａに対する、第１及び第２の原料供給流路２７、２８の差圧を上記の如く同一に設定することで、両原料供給流路２７，２８間の内部圧力は同一に保持した。
【００５１】
また、Ｇａ0.51Ｉｎ0.49Ｐ電子供給層６２の成長にあたっては、第１の原料供給流路２７内に流通するガリウム源１０及びインジウム源１１の混合比率がインジウム組成比を０．４９とするＧａ0.51Ｉｎ0.49Ｐ成長層を帰結するに充分な一定の混合比率に至る迄、待機した。混合比率は各々、流量計１６、１７により計測できるガリウム源１０及びインジウム源１１の流量の変動の消失をもって安定したとした。具体的には、第１の原料供給流路２７内へのガリウム源１０及びインジウム源１１の流量が安定する迄、５秒間に亘り双方の原料１０、１１の流通を継続した後、３方バルブ３７を閉とし、同時に４方バルブ３６を開状態として、第１の原料供給流路２７内で予め充分に混合させてある原料気体の流路を第２の排気系流路２９ａから第２の原料供給流路２８に切り換えてＧａ0.51Ｉｎ0.49Ｐ電子供給層６２の成長を開始した。
【００５２】
積層構造体６７の形成を終了した後、通常のホール効果法により測定した。室温の移動度は６，３００ｃｍ2／Ｖ・ｓ（シートキャリア濃度＝１．３×１０12ｃｍ-2）、液体窒素温度（７７Ｋ）での移動度は３５，０００ｃｍ2／Ｖ・ｓの高値となった。また、ＣＡＴ法に依れば、Ｇａ0.80Ｉｎ0.20Ａｓチャネル層６１／Ｇａ0.51Ｉｎ0.49Ｐ電子供給層６２とのヘテロ接合界面に於ける干渉フリンジには緩慢な屈曲は認めらず、高い２次元電子移動度を与えるに充分な急峻な接合界面が形成されているのが示された。
【００５３】
最表層をなすオーミックコンタクト層６８上には、周知の真空蒸着及びフォトリソグラフィー（写真食刻）等の一般的なプロセス技術手段を利用してソース（ｓｏｕｒｃｅ）電極６９及びドレイン（ｄｒａｉｎ）電極７０を形成した。両オーミック電極６９、７０は、上表面を金（Ａｕ）層とする金・ゲルマニウム（Ａｕ・Ｇｅ）／ニッケル（Ｎｉ）／金（Ａｕ）の３層構造から構成した。ソース及びドレイン電極６９、７０の平面形状は何れも長さを１３０μｍとし、幅を４５０μｍとする長方形とした。次に、ソース電極６９及びドレイン電極７０の中間のゲート（ｇａｔｅ）電極７１を形成するための長さ約５μｍに亘る領域にあるＧａＡｓコンタクト層６８を周知のフォトリソグラフィー技術に依る選択パターニング技術及び湿式エッチング手段を利用して選択的に除去した。然る後、ＧａＡｓコンタククト層６８を除去した領域に露呈したＧａ0.51Ｉｎ0.49Ｐゲートコンタクト層７２の表層部を約２ｎｍ程度、塩酸（化学式：ＨＣｌ）系水溶液を用いて除去して、リセス（ｒｅｃｅｓｓ）構造となした。引き続き、周知の電子ビームフォトリソグラフィー技術を駆使してゲート電極７１部を選択的にパターニングした。次ぎに、電子ビーム蒸着手段等を利用して、ゲートコンタクト層７２に接する側から、チタン（元素記号：Ｔｉ）、モリブデン（元素記号：Ｍｏ）及び金（Ａｕ）を順次、蒸着した。その後、周知のリフトオフ（ｌｉｆｔ−ｏｆｆ）技法を利用して、ゲート長を約０．２５μｍとするＴｉ／Ｍｏ／Ａｕ３層構造からなるショットキー（Ｓｃｈｏｔｔｋｙ）ゲート電極７１を構成した。
【００５４】
ソース／ドレイン電極６９、７０間に２Ｖのドレイン電圧（略称：Ｖds）を印可した際のＴＥＧＦＥＴ６６の飽和ドレイン電流（略称：Ｉdss）は約７０ミリアンペア（ｍＡ）で、ゲートピンチオフ（ｇａｔｅ ｐｉｎｃｈ−ｏｆｆ）電圧は約−０．８Ｖとなった。また、相互コンダクタンス（ｇm）は、電子移動度の高さを反映して約２５０ｍＳ／ｍｍ（ミリジーメンス／ミリメートル）となり、例えば、Ｌ帯からミリ波帯域で動作させる低雑音電界効果型トランジスタとして好適な性能を有するＧａＩｎＰ系ＴＥＧＦＥＴが提供された。
【００５５】
（実施例３）
砒化アルミニウム・インジウム（組成式Ａｌ0.48Ｉｎ0.52Ａｓ）／Ｇａ0.47Ｉｎ0.53Ａｓ格子整合系高移動度電界効果型トランジスタ用途のエピタキシャル積層構造体の気相成長装置を例にして本発明を具体的に説明する。
【００５６】
実施例１と同様の配管系（図６参照）を具備した図１２に示す常圧（略大気圧）ＭＯＶＰＥ装置を利用してＡｌ0.48Ｉｎ0.52Ａｓ／Ｇａ0.47Ｉｎ0.53Ａｓヘテロ接合系積層構造体７３を形成した。図１３に積層構造体７３の断面構造を模式的に示す。
【００５７】
配管系は本発明に係わる２重のベント／ラン（Ｄｕａｌ Ｖｅｎｔ−Ｒｕｎ）方式から構成した。ガリウム（Ｇａ）源１０にはトリメチルガリウム（（ＣＨ3）3Ｇａ）、及びインジウム（Ｉｎ）源１１には結合価を１価とするシクロペンタジエニルインジウム（分子式：Ｃ5Ｈ5Ｉｎ）（▲１▼日本国特許第２０９８３８８号（特公平８−１７１６０号）、及び▲２▼Ｊ．Ｃｒｙｓｔａｌ Ｇｒｏｗｔｈ、１０７（１９９１）、３６０〜３６４頁参照）を用いた。また、アルミニウム（Ａｌ）源１２には、トリメチルアルミニウム（（ＣＨ3）3Ａｌ）を用いた。上記の第ＩＩＩ族元素源１０〜１２には、それらの原料の蒸気を随伴して搬送するための水素ガスを供給する配管を各原料１０〜１２に個別に設けた（図１２に図示せず）。各原料１０〜１２の蒸気を随伴する水素ガスは必要に応じて第１の原料供給流路２７または第１の排気系流路２９の何れかに選択して流通させた。第１の排気系流路２９は３方バルブ３８を開として第２の排気系流路２９ａに導通させた。
【００５８】
また、第１の原料供給流路２７または第１の排気系流路２９の何れかに砒素（Ａｓ）源５１とするアルシン（ＡｓＨ3）をバルブ３２、３５の開閉操作で流入できる構成とした。また、アルシン５１を供給するための配管の中途より配管系５２を分岐して設けて、圧空動作式バルブ５３、５４の開閉操作により、別途に第２の原料供給流路２８または第２の排気系流路２９ａの何れかの流通できる構成とした。第１の原料供給流路２７内で予め、混合した第ＩＩＩ族及び第Ｖ族の原料ガスの流路はバルブ３６、３７の切換えにより第２の原料供給流路２８、または第２の排気系流路２９ａの何れかに切り換えられる構成とした。第２の原料供給流路２８は常圧（略大気圧）ＭＯＶＰＥ成長を実施する気相成長領域３９に直結した。第２の排気系流路２９ａの下流には原料気体を除害するための除害設備４０を配備した。
【００５９】
第１の原料供給流路２７と第１の排気系流路２９との間には、圧力差（差圧）を計測するための差圧計５５を設けた。また、第２の原料供給流路２８と第２の排気系流路２９ａの間にも差圧計５６を配置した。第１のベント／ラン配管２７、２９及び第２のベント／ラン配管２８、２９ａの双方の配管系の上流側には流路間の差圧を解消するために通流する搬送ガスの流量を調整するための電子式質量流量計（英略称：ＭＦＣ）４３、４４、４７、４８を配置した。第１の原料供給流路２７及び第１の排気系流路２９の内部圧力を２×１０2Ｐａ以下となすために流量計（ＭＦＣ）４３、４４には毎分３〜５リットル程度の水素ガスを流通させた。また、第２の原料供給流路２８及び第２の排気系流路２９ａ間の差圧を２×１０2Ｐａ以下となすために、各々の流路について毎分約５リットル〜約８リットル程度の水素ガスを予め流通させた。
【００６０】
次に、気相成長反応領域３９に載置した、面方位を｛１００｝２゜オフ（ｏｆｆ）とする半絶縁性のリン化インジウム（ＩｎＰ）単結晶基板７４の表面に配管系５７を利用して５０ｃｃ／分の流量のホスフィンを供給しつつ、ＩｎＰ基板７４の温度を６４０℃のエピタキシャル成長温度に加熱した。
【００６１】
基板７４の温度を安定させている間に、アンドープのリン化インジウム（ＩｎＰ）からなる高抵抗の緩衝層７５の成長に備えて、水素ガスに随伴されるインジウム源１１の流量を流量計１７をもって６０ｃｃ／分に制御して第１の排気系流路２９に予め、流通させた。インジウム源１１は第１の原料供給流路２７を介して第２の排気系流路２９ａに流通させておいた。
【００６２】
基板７４の温度が安定した後、配管系５７に流通するホスフィンガスの流量を２５０ｃｃ／分に増量した。
【００６３】
次に、インジウム源１１を随伴する水素ガスの流路を第１の排気系配管２９に設けられいる３方バルブ３４を閉状態とし、それに同期させて第１の原料供給流路２７の４方バルブ３１を開状態とし、第１の原料供給流路２７へ流路を変更した。流路を変更して、３秒間待機した後、原料気体の流路を、第２の排気系流路２９ａに付属する３方バルブ３７を閉とし、同時に第２の原料供給流路２８に付属する４方バルブ３６を開として、ＩｎＰ緩衝層７５の成長を開始した。約１０ｎｍの層厚のＩｎＰ緩衝層７５の気相成長が終了する迄、気相反応領域３９へのインジウム源１１及びホスフィンの供給を継続した。然る後、インジウム源１１の流路をバルブ３６、３７の開閉状態を逆転させて第２の原料供給流路２８より第２の排気系流路２９ａへと変更してＩｎＰ緩衝層７５の成長を終了した。
【００６４】
ＩｎＰ緩衝層７５の成長終了後も、ホスフィンガスを配管系５７を介して継続して気相反応領域３９に供給し続けて、表面からのリン（Ｐ）の揮散に因る緩衝層７５の表面状態の劣化を抑制した。
【００６５】
次に、Ｇａ0.47Ｉｎ0.53Ａｓ電子走行層（ｃｈａｎｎｅｌ層）７６を成長するために、予め第１の排気系流路２９に定常的に流通させていたトリメチルガリウムの蒸気を随伴する水素ガスをガリウム源１０用途の配管系１３に専用に設けられた３方バルブ３３を閉とし、同期させて４方バルブ３０を開として第１の原料供給流路２７に流通させた。併せて、第１の原料供給流路２７に既に流通させているインジウム源１１の供給流量をインジウム組成比を０．５３とするＧａ0.47Ｉｎ0.53Ａｓ層が得られる様に調整した。また、流量計（図１２に図示せず）により２５０ｃｃ／分の流量に制御したアルシン５１を第１の原料供給流路２７に流通させた。予め、混合させておいた第ＩＩＩ族元素及び砒素の原料気体は第１の原料供給流路２７を介して第２の排気系流路２９ａに流通させた。
【００６６】
ホスフィン５７の流路を第１の原料供給流路２８から第２の排気系流路２９ａへ切り替えた。また、同時に配管系５２を利用して予め、第２の排気系流路２９ａに流通していた５０ｃｃ／分の流量のアルシン５１の流路を第２の原料供給流路２８へ切り換えた。
【００６７】
予め、混合させておいた上記の第ＩＩＩ族元素及び砒素の原料気体を第２の排気系流路２９ａに５秒間流通させて定常流となした後、３方バルブ３７を閉とし、逆に４方バルブ３６を開として、流路を第２の原料供給流路２８に切換えた。これより、Ｇａ0.47Ｉｎ0.53Ａｓチャネル層７６の気相成長を開始した。アンドープのチャネル層７６の層厚が４００ｎｍとなった時点で、原料気体の流路を再び、第２の原料供給流路２８から第２の排気系流路２９ａに戻してチャネル層７６の気相成長を終了した。
【００６８】
チャネル層７６の終了後も配管系５２を利用してアルシンガス５１の気相成長領域３９への供給を継続して、砒素の揮散に因るチャネル層７６の表面状態を劣化を防止した。
【００６９】
次に、第１の排気系流路２９に以前より流通させていたアルミニウム源１２の蒸気を随伴する水素ガスの流路をバルブＡ２を閉とし、逆にバルブＡ１を開として第１の原料供給流路２７に変更した。その後、ｎ形砒化アルミニウム・インジウム混晶（組成式Ａｌ0.48Ｉｎ0.52Ａｓ）からなるスペーサ（ｓｐａｃｅｒ）層７７及び電子供給層７８の成長に備えて、水素ガスに随伴されるインジウム源１１及びアルミニウム源１２の供給流量を、上記の混晶比が得られる様に流量計１７、Ａ１８で調節し、第１の原料供給流路２７に流通させた。また、第１の原料供給流路２７に流通させるアルシン５１の流量を２００ｃｃ／分とした。スペーサ層７７の成長が開始される迄、予め混合した原料気体を第２の排気系流路２９ａに流通させた。
【００７０】
また、珪素のドーピング源５８として用いたジシラン−水素混合ガス（Ｓｉ2Ｈ6１０体積ｐｐｍー水素混合ガス）を第２の排気系流路２９ａに流通させておいた。
【００７１】
予め混合した原料気体の流路を第２の排気系流路２９ａに変更してから３秒間待機した後、第２の排気系流路２９ａに付属する３方バルブ３７を閉とし、同時に第２の原料供給流路２８に付属する４方バルブ３６を開として、アンドープのＡｌ0.48Ｉｎ0.52Ａｓからなるスペーサ層７７の成長を開始した。
【００７２】
アンドープＡｌ0.48Ｉｎ0.52Ａｓ層７７の層厚が４ｎｍに達した時点で、上記のジシランガス５８の流路を第２の排気系流路２９ａから第１の原料供給流路２８へ変更した。上記の第ＩＩＩ族及び砒素源に加えて、窒化物半導体気相成長領域３９へのジシランガスの供給をもって、Ｓｉドープｎ形Ａｌ0.48Ｉｎ0.52Ａｓ層７８の成長を開始した。これより、キャリア濃度を２×１０18ｃｍ-3とするＳｉドープｎ形Ａｌ0.48Ｉｎ0.52Ａｓ層からなる電子供給層７８を成長した。層厚を１０ｎｍとする電子供給層７８の成長が終了する迄、気相反応領域３９への第ＩＩＩ族及び第Ｖ族原料気体並びにドーピング源５８の供給を継続した。然る後、原料気体の流路をバルブ３６、３７の開閉状態を逆転させて第２の原料供給流路２８より第２の排気系流路２９ａへと変更して、Ａｌ0.48Ｉｎ0.52Ａｓ電子供給層７８の成長を終了した。また、ジシランの流路を第２の原料供給流路２８から第２の排気系流路２９ａへ変更した。
【００７３】
その後、配管系５２を利用して気相成長領域３９にアルシンガス５１を供給して、電子供給層７８の表面からの砒素（Ａｓ）の揮散を抑制しつつ、ＩｎＰ基板７４の温度を降温した。
【００７４】
通常のホール効果法により測定された積層構造体７３の室温に於ける移動度は９、２００ｃｍ2／Ｖ・ｓとなった。室温でのシートキャリア濃度（ｎs）は７．４×１０11ｃｍ-2であった。また、液体窒素温度（７７Ｋ）に於ける移動度は６４、０００ｃｍ2／Ｖ・ｓでシートキャリア濃度は７．９×１０11ｃｍ-2であった。
【００７５】
また、温度４．２Ｋで測定した磁気抵抗（Ｒ）の２階微分値（ｄ2Ｒ／ｄＢ2）の磁場強度（Ｂ）の逆数（１／Ｂ）に対する依存性を図１４に例示する。図１４に示す如く、高い電子移動度が顕現されていることを反映して大きな振幅の磁気抵抗のシュブニコフ・ド ハース（Ｓｈｕｂｎｉｋｏｖ ｄｅ Ｈａａｓ：ＳｄＨ）振動が観測され、本発明に依れば、２次元電子を局在させるに充分な急峻性を有するＧａ0.47Ｉｎ0.53Ａｓチャネル層７６／Ａｌ0.48Ｉｎ0.52Ａｓスペーサ層７７とのヘテロ接合界面が形成されることが示された。上記のｄ2Ｒ／ｄＢ2値のピーク（ｐｅａｋ）位置を利用して算出したシートキャリア濃度は７．６×１０11ｃｍ-2となり、上記の液体窒素温度に於けるシートキャリア濃度と良好な一致を示した。
【００７６】
図１５にフィリングファクター（ｆｉｌｌｉｎｇ ｆａｃｔｏｒ：ｉ）と磁場強度（Ｂ：単位テスラ（Ｔ））の逆数（１／Ｂ）との相関を示す。フィリングファクターはサイクロトロン半径をｌcとして、ｎs・２π・ｌc 2で与えられる。本発明の配管系を具備する気相成長装置によって形成されたＧａ0.47Ｉｎ0.53Ａｓ／Ａｌ0.48Ｉｎ0.52Ａｓ系ＴＥＧＦＥＴ用途の積層構造体７３にあっては、１／Ｂ（単位：１／Ｔ）＝０．０３２・ｉの関係が得られた。
【００７７】
また、図１６には、ホール電圧（ＲH）の磁場強度依存性を示す。ＳｄＨ振動の様相は、一種類の電子系によると思量されるＡｌＧａＡｓ／ＧａＡｓＴＥＧＦＥＴ用途ヘテロ接合構造体の場合とは異なり、より複雑な２次元電子系に起因するものと判断された。
【００７８】
（実施例４）
本実施例では、砒化ガリウム・インジウム（組成式Ｇａ0.47Ｉｎ0.53Ａｓ）／リン化インジウム（ＩｎＰ）ヘテロ接合構造を具備した積層構造体から高い積感度のホール（Ｈａｌｌ）素子を得る場合を例にして、本発明を説明する。
【００７９】
本実施例では、複合体化反応を生じ易い原料を用いてヘテロ接合構造を形成しているために、ＩＩＩ族構成元素原料及びＶ族構成元素原料を個別に供給できる図１７に示す多重のベント／ラン（Ｍｕｌｔｉｐｌｅ Ｖｅｎｔ−Ｒｕｎ）配管系を具備する気相成長装置を利用した。本実施例で使用した気相成長装置は図３に例示したと類似しているため、図３に示したと同一の構成要素には同一の符号を付して掲示する。配管系４９は第ＩＩＩ族構成元素原料の供給用の配管系である。原料気体流路１３−１はガリウム（Ｇａ）源１０とするトリメチルガリウム（（ＣＨ3）3Ｇａ）を供給するための配管系である。原料気体流路１４−１はインジウム（Ｉｎ）源１１とするトリメチルインジウム（（ＣＨ3）3Ｉｎ）を供給するための配管系である。原料気体流路１３−１、１４−１は、第１の原料供給流路２７−１または第１の排気系流路２９−１の何れかの流路に圧空動作式バルブ３０−１、３３−１及びバルブ３１−１、３４−１の開閉操作により切換えられる構成となっている。更に、第１の原料供給流路２７−１内で予め混合されて流通される原料気体は第２の原料供給流路２８−１、または第２の排気系流路２９ａの何れかにバルブ３６−１、３７−１の切換えにより流通できる構成となっている。第２の原料供給流路２７−１は、第Ｖ族原料用の第２の原料供給流路２７−２とは接続せずに別個に気相成長領域３９に直結されている。第ＩＩＩ族原料供給用途の配管系４９に於ける第１の排気系流路２９−１は、原料供給領域３９を迂回して除害設備４０に通ずる第２の排気系流路２９ａに合流にする構成としてある。第ＩＩＩ族原料供給用途の配管系４９には、第１の原料供給流路２７−１と第１の排気系流路２９−１（第１のベント／ラン配管系）流路内部の圧力を同一となすための搬送ガスの流量を制御する電子式質量流量計（英略称：ＭＦＣ）４３−１、４４−１を配置した。
【００８０】
また、本実施例の気相成長装置では、第Ｖ族構成元素原料を供給するための配管系５０を上記の第ＩＩＩ族原料用の配管系４９とは別個に設けた。原料気体流路１３−２は砒素（Ａｓ）源５１−１とするアルシン（ＡｓＨ3）を供給するための配管系である。原料気体流路１４−２はリン（Ｐ）源５１−２とするホスフィン（ＰＨ3）を供給するための配管系である。アルシン及びホスフィン原料ガスを供給するために利用した原料気体流路１３−２、１４−２は、第１の原料供給流路２７−２または第１の排気系流路２９−２の何れかの流路に圧空動作式４方バルブ３０−２、３１−２及び３方バルブ３３−２、３４−２の開閉操作により切換える構成とした。第１の原料供給流路２７−２内で予め混合されて流通される原料気体は第２の原料供給流路２８−２、または第２の排気系流路２９ａの何れかにバルブ３６−２、３７−２の切換えにより流通できる構成となっている。第２の原料供給流路２８−２は気相成長領域３９に直結した。また、第１の原料供給流路２７−２と第２の排気系流路２９−２（第２のベント／ラン配管系）の双方の配管系の上流側には、流路内部の圧力を同一となすための搬送ガスの流量を制御する電子式質量流量計（英略称：ＭＦＣ）４３−２、４４−２を配置した。
【００８１】
上記の配管を具備したＭＯＣＶＤ装置を利用して、鉄（元素記号：Ｆｅ）をドーピングした比抵抗を３×１０6Ω・ｃｍとする半絶縁性の（１００）−リン化インジウム（ＩｎＰ）単結晶基板７９上にアンドープのｎ形ＩｎＰ層を成長させた。ＩｎＰ層の成長にあたっては、先ず、第ＩＩＩ族及び第Ｖ族原料供給配管系４９、５０共々、第１の原料供給流路系２７−１，−２及び第１の排気系流路系２９−１、−２の内部圧力を略同等となすために、ＭＦＣ４３−１，４３−２、４４−１，４４−２により流量を制御した水素ガスを流通させた。同じく第２の原料供給流路系２８及び第２の排気系流路系２９ａ間の差圧を解消すべく、各々の流路について流量計４７−１，４７−２、４８で流量を制御した水素ガスを予め流通した。これより、第１の原料供給流路系２７−１，２７−２と第１の排気系流路２９−１，２９−２との差圧は差圧計５５−１、５５−２をもって各々、約５×１０2Ｐａ以内に抑制した。これより、第１の原料供給流路２７−１，２７−２と第１の排気系流路２９−１，２９−２の内部圧力を略同等とした。第１と第２の排気系流路２９−１，２９−２、２９ａとは開閉バルブ３８−１，３８−２を開状態として導通させ、第１と第２の排気系流路２９−１、２９−２、２９ａ内部の圧力を同等とした。従って、第１または第２の排気系流路２９−１，２９−２、２９ａに対する差圧を同等とすることにより、第１及び第２の原料供給流路２７−１，２７−２、２８の内部圧力を等価にした。
【００８２】
上記の設定条件下において、流量計１７−２によって４０ｃｃ／分の流量に制御されたリン（Ｐ）源５１−２のホスフィン（ＰＨ3１０体積％−Ｈ2９０体積％混合気体）をバルブ３１−２を開とし、３４−２を閉とした状態で気体原料流路１４−２を介して、第１の原料供給流路２７−２に流通し、流量計４３−２で毎分５リットルの流量に制御された搬送（キャリア）ガスの水素と合流させた。ホスフィンを含む水素キャリアガスはバルブ３６−２を開とし、バルブ３７−２を閉とする状態で第２の原料供給流路２８−２を介して略大気圧に保持されている気相反応炉内の気相成長反応領域３９に流通させた。気相成長反応領域３９内に載置したＩｎＰ単結晶基板７９の表面へホスフィンを含む水素ガスの供給を継続しつつ、ＩｎＰ基板７９の温度を６１０℃に加熱した。
【００８３】
ＩｎＰ単結晶基板７９の温度が安定する間に、第ＩＩＩ族原料供給用の配管系４９において、アンドープのｎ形ＩｎＰからなる緩衝層８０を気相成長させるためにインジウム源１１の蒸気を随伴する水素ガスをバルブ３１−１を開とし、バルブ３４−１を閉とした状態で第１の原料供給流路２７−１に流通させておく。本実施例では、４０℃の恒温に保持されたインジウム源１１の蒸気を随伴する水素ガスの流量は７０ｃｃ／分とした。流量計４３−１により毎分１リットルの流量に制御された水素搬送ガスと共に第１の原料供給流路２７−１内を流通するインジウム源１１の蒸気を随伴する水素ガスは、バルブ３６−１を閉とし、バルブ３７−１を開として第２の排気系流路２９ａに排出しておいた。
【００８４】
その後、第Ｖ族原料供給用の配管系５０において、上記の如く従前より第２の原料供給流路２７−２を介して流通させてあるホスフィンの流量を流量計１７−２により３２０ｃｃ／分に増量した。
【００８５】
インジウム源１１を随伴する水素ガスの流量が安定したのを確認して、バルブ３７−１を閉状態とし、それに同期させてバルブ３６−１を開状態とし、原料気体の流路を第２の排気系流路２９ａから第２の原料供給流路２８−１へと変更した。これより、１５ｎｍの層厚のＩｎＰ緩衝層８０の気相成長を終了する迄、気相反応領域３９への原料気体の供給を継続した。然る後、第ＩＩＩ族原料気体を流通させる流路をバルブ３６−１、３７−１の開閉状態を逆転させて第２の原料供給流路２８−１より第２の排気系流路２９ａへと変更して、ＩｎＰ緩衝層８０の気相成長を終了した。
【００８６】
ＩｎＰ緩衝層８０の成長終了後においても、ＩｎＰ緩衝層８０の表面からのリンの揮散を防止するために、ホスフィンガス５１−２は第２の原料供給流路２８−２を介して気相反応領域３９に供給し続けた。
【００８７】
その間に、アンドープｎ形Ｇａ0.47Ｉｎ0.53Ａｓ層８１の成長に備え、第ＩＩＩ族原料供給用途の配管系４９において、予め第１の排気系流路２９−１に定常的に流通させていたガリウム源１０の蒸気を随伴する水素ガスを、ガリウム源１０の原料気体流路１３−１に専用に設けられたバルブ３３−１を閉とし、同期させてバルブ３０−１を開として第１の原料供給流路２７−１に流通させた。これより、第１の原料供給流路２７−１に既に流通させているインジウム源１１の蒸気と予め混合させ、バルブ３６−１を閉状態とし、バルブ３７−１を開状態に維持したままで、混合気体を第１の原料供給流路２７−１を介して第２の排気系流路２９ａに排出しておいた。
【００８８】
一方、第Ｖ族原料の供給配管系５０にあっては、原料気体流路１４−２により流通させていたホスフィン５１−２の流路を、流路１４−２に係わるバルブ３１−２を閉とし、逆にバルブ３４−２を開として、第１の原料供給流路２７−２から第１の排気系流路２９−２へ切換えた。即ち、第１及び第２の原料供給流路２７−２、２８−２を介しての気相成長領域３９へのホスフィン５１−２の供給を停止した。代替に、原料気体流路１３−２に設けられた流量計１６−２で毎分２８０ｃｃの流量に制御された砒素源５１−１としたアルシン（ＡｓＨ3１０体積％−水素９０体積％）の流路をバルブ３０−２を開とし、バルブ３３−２を閉として第１の原料供給流路２７−２へ切り換えた。
【００８９】
直後に、第ＩＩＩ族元素の原料供給系４９において、第１の原料供給流路２７−１内で予め混合して流通していたガリウム源１０とインジウム源１１の混合ガスの流路を、バルブ３６−１を開とし、バルブ３７−１を閉として第２の排気系流路２９ａより第２の原料供給流路２７−１へと変更した。これより、第ＩＩＩ族元素の原料１０、１１を気相反応領域３９に供給して、層厚を約３００ｎｍとするアンドープｎ形Ｇａ0.47Ｉｎ0.53Ａｓ層８１の成長を開始した。第ＩＩＩ族元素の原料１０、１１の流路を第２の原料供給流路２８−１から第２の排気系流路２９ａと再び戻してＧａ0.47Ｉｎ0.53Ａｓ層８１の成長を終了させた。
【００９０】
その後、基板７９の温度を降下させた。アルシン（ＡｓＨ3）５１−１は基板７２の温度が約４５０℃に低下する迄、気相成長領域３９への流入を継続し、砒素（Ａｓ）の揮散に因るＧａ0.47Ｉｎ0.53Ａｓ層８１の表面状態の劣化を防止した。
【００９１】
半絶縁性ＩｎＰ基板７９上に上記の手段により形成されたアンドープＩｎＰ層８０とアンドープＧａ0.47Ｉｎ0.53Ａｓ層８１との単一ヘテロ接合を備えた積層構造体において、通常のホ−ル効果法に依り測定されるシートキャリア濃度は７．１×１０11ｃｍ-2であり、シート抵抗は７６７Ω／□であった。また、室温移動度は１１、５００ｃｍ2／Ｖ・ｓの高値となった。
【００９２】
また、図１７に記載の本実施例の気相成長装置により、半絶縁性ＩｎＰ基板７２上に上記と同様の手段により形成されたＩｎＰ／Ｇａ0.47Ｉｎ0.53Ａｓとの単一ヘテロ接合を備えた積層構造体の室温移動度とキャリア濃度との関係を示す。本発明に依れば、１×１０16ｃｍ-3〜４×１０16ｃｍ-3のキャリア濃度の範囲で９、０００ｃｍ2／Ｖ・ｓを越える高い電子移動度を発現するヘテロ接合構造が安定して帰結されることが示されている。
【００９３】
（実施例５）
上記の実施例３に記載の手段に則り、半絶縁性ＩｎＰ基板７９上にアンドープＩｎＰ層８０とアンドープＧａ0.47Ｉｎ0.53Ａｓ層８１との単一ヘテロ接合を備えた積層構造体８２を形成した。
【００９４】
キャリア濃度を８．１×１０16ｃｍ-3とし、室温で１１、３００ｃｍ2／Ｖ・ｓの高移動度を呈する積層構造体８２を用いて、ＩｎＰ／Ｇａ0.47Ｉｎ0.53Ａｓヘテロ接合ホール素子８３を形成した。形成したホール素子８３の断面模式図を図１８に示す。ホ−ル素子８３はアンドープＩｎＰ層８０とＧａ0.47Ｉｎ0.53Ａｓ８１を湿式エッチングによりメサ（ｍｅｓａ）型に加工した感磁部を利用して構成した（特開平７−９９３４９号公報参照）。動作電源入力用及びホール電圧出力用のオーミック電極８４は何れも金（元素記号：Ａｕ）−ゲルマニウム（元素記号：Ｇｅ）合金から構成した。
【００９５】
ホール素子８３の入力抵抗１４００Ωとなり、積感度は８８０Ｖ／Ａ・Ｔとなった。この積感度は、入力抵抗（ｉｎｐｕｔ ｒｅｓｉｓｔａｎｃｅ）を２．５ｋΩ未満とする従来のＩｎＰ／Ｇａ0.47Ｉｎ0.53Ａｓヘテロ接合ホ−ル素子の積感度（＝７６０Ｖ／Ａ・Ｔ）（上記のＩＥＥＥ Ｔｒａｎｓ．ＥｌｅｃｔｒｏｎＤｅｖ．、ＥＤ−４１（３）参照）を約１５％を越えて上回る高値となった。
【００９６】
（実施例６）
実施例３に記載の成長手段に則り形成した種々のキャリア濃度及び移動度を有するＩｎＰ／Ｇａ0.47Ｉｎ0.53Ａｓ積層構造体に、実施例４と同様の加工を施して（特開平６−２６８２７７号公報参照）ヘテロ接合ホール素子８３を構成した。
【００９７】
キャリア濃度と移動度の各々が異なるために種々の入力抵抗を呈することとなったホ−ル素子８３を利用して磁界強度測定用途の測定子（プローブ：ｐｒｏｂｅ）を構成した。図１９に磁界強度測定用プローブ８４の平面模式図を示す。
【００９８】
図２０にはプローブの入力抵抗と積感度との相関を示す。また、同図には、比較のために感磁部をＧａＡｓとする従来のＧａＡｓホール素子（例えば、Ｓｅｎｃｏｒｓ ａｎｄ Ａｃｔｕａｔｏｒｓ Ａ、３２（１９９２）、６５１〜６５５頁参照）を用いたプローブの感度を併せて例示する。
【００９９】
本発明に依るヘテロ接合ホール素子８３を用いたプローブ８４では、入力抵抗の如何に拘わらず、従来のＧａＡｓホール素子を用いたプローブに比較して高感度となっているのが明かとなった。従って、本発明に依れば、例えば、入力抵抗が５００Ωと同一であっても、従来のＧａＡｓホール素子に比較して約２．５倍の高い感度な磁界強度測定用のプローブが提供できる。
【０１００】
（実施例７）
本発明の気相成長装置を利用して得た窒化ガリウム・インジウム（ＧａＩｎＮ）／ＧａＮ系ダブルヘテロ接合構造の発光部を備えた積層構造体から短波長可視発光ダイオ−ド（ＬＥＤ）を構成する場合を例にして本発明を具体的に説明する。
【０１０１】
本実施例に係わるＧａＩｎＮ系ＬＥＤ８５の断面構造を図２１に模式的に示す。
【０１０２】
ＬＥＤ８５用途の積層構造体８６は、２重のベント／ラン（Ｄｏｕｂｌｅ Ｖｅｎｔ−Ｒｕｎ）方式の図２２に記載の気相成長装置を利用して形成した。本実施例で利用した気相成長装置は図１７に掲示した配管系に、図５に例示した如くの揮発性に富む第Ｖ族構成元素源を気相成長領域に随時供給できる配管系を付加した構成とした。
【０１０３】
窒素（元素記号：Ｎ）源５１−１にはアンモニア（分子式：ＮＨ3）を使用した。アンモニアガスを流通させる原料気体流路１３−２の中途には、流量計１６−２を介して、アンモニアガスを随時、第２の原料供給流路２８−２または第２の排気系流路２９ａの何れかに選択して流通させるための配管系５２を設けた。また、第Ｖ族構成元素源を供給するための配管系５０において、原料気体流路１４−２には、珪素（元素記号：Ｓｉ）のド−ピングガスとしてジシラン−水素混合ガス（Ｓｉ2Ｈ6５体積ｐｐｍ）５１−３を装着した。
【０１０４】
第ＩＩＩ族構成元素の原料を供給するための配管系４９には、ガリウム（Ｇａ）源１０としてトリメチルガリウム（（ＣＨ3）3Ｇａ）を、インジウム（Ｉｎ）源１１としてトリメチルインジウム（（ＣＨ3）3Ｉｎ）を各々、使用した。ＩＩＩ族元素源１０、１１は何れも水素ガスに随伴されて原料気体流路１３−１、１４−１を介して原料供給流路２７−１，２８−１または排気系流路２９−１、２９ａの何れかに流通できる構成とした。
【０１０５】
低温緩衝層８８を成長させる以前には、原料気体流路１３−２内に流通するアンモニアガス５１の流量を毎分０．５リットルに流量計１６−２で調整して第１の原料供給流路２７−２及び第２の原料供給流路２８−２を通じて、サファイア基板８１を載置した気相成長領域３９に供給しておいた。併せて、流量計１６−３により毎分０．５リットルの流量に調整されたアンモニアガス５１を配管系５２及び第１の原料供給流路２８−２を介して流通させた。第２の原料供給流路２８−２には、流量計４７−２により毎分５リットルの流量に調整された水素ガスを流通させておいた。また、第２の排気系流路２９ａ内には、差圧計５６で計測される第２の原料供給流路２８−２との差圧が２×１０2Ｐａ以下となる様に流量計４８で流量が調節された水素ガスを流通させた。水素ガスとアンモニアガスとを流通させた状態でサファイア基板８７の温度を４２０℃に上昇させた。
【０１０６】
基板８７の温度が±１℃の範囲で安定するを見計らった後、所定の流量をもって第１の排気系流路２９−１に予め流通していたトリメチルガリウム１０の蒸気を含む水素ガスの流路を第１の排気系流路２９−１から第１の原料供給流路２７−１へとバルブ３０−１、３３−１の開閉操作により切り替えた。引き続き、バルブ３６−１、３７−１の開閉操作により、ガリウム源１０の蒸気を含む水素ガスの流路を、第２の排気系流路２９ａから第２の原料供供給流路２８−１へと切り換えた。これより、８分間に亘り、気相成長領域３９へガリウム源１０とアンモニアガス５１−１の供給を継続して、層厚を１７ｎｍとするアンドープのＧａＮ低温緩衝層８８を成長した。本発明者の発明（日本国特許第３０３１２５５号参照）に記載の結晶組織構成を備えた低温緩衝層８８の成長は、ガリウム源１０を含むガスの流路を第２の原料供給流路２８−１から第２の排気系流路２９ａに変換して終了させた。
【０１０７】
第１の原料供給流路２７−２へのアンモニアガスの流通は、４方バルブ３０−２を閉とし、３方バルブ３３−２を閉として一旦、停止した。一方で、アンモニアガス５１−１は配管系５２を介して気相成長領域３９に通流し続けた。気相成長領域３９をアンモニアを含む雰囲気とした状態で、基板８７の温度を４２０℃から１０８０℃に約１分間で昇温した。
【０１０８】
基板８７の温度が１０８０℃に到達する間に、流路１３−２内を流通させるアンモニアガス５１−１の流量を流量計１６−２で毎分８リットルに調整し、第２の排気系流路２９ａに流入させておいた。
【０１０９】
また、基板８７の温度が１０８０℃±２℃の範囲に安定する間に、０℃の恒温に保持されたガリウム源１０を随伴するための水素ガスの流量を２０ｃｃ／分に増量して、第１の原料供給流路２７−１を介して第２の排気系流路２９ａに予め流通させた。
【０１１０】
また、ドーピングガス源５１−３より原料気体流路１４−２を経由して、流量計１７−２により毎分１０ｃｃに流量を調整されたジシランガスを第１の原料供給流路２７−２に流入した。
【０１１１】
アンモニア及びジシランを含む水素ガスの流路を第２の排気系流路２９ａから第２の原料供給流路２８−２へと変更した。約８×１０3Ｐａに減圧された気相成長領域８９に、第２の原料供給流路２８−２を介してアンモニアガス（流量８ｌ／ｍｉｎ．）とジシランガス（１０ｃｃ／ｍｉｎ．）と水素ガス（流量５ｌ／ｍｉｎ．）との混合ガスを流通させた状態で、上記のガリウム源１０を含む水素ガスの流路を第２の排気系流路２９ａより第２の原料系流路２８−１に変更して、低温緩衝層８８上にＳｉをドーピングしたｎ形のＧａＮからなる下部クラッド層８３を堆積した。下部クラッド層８９のキャリア濃度は３．２×１０18ｃｍー3とし、層厚は約３．０μｍとした。 ＧａＮ下部クラッド層８９の成長は、ガリウム源１０を含む原料気体の流路を第２の原料供給流路２８−１から第２の排気系流路２９ａへと変更して終了した。
【０１１２】
同時に、第２の原料供給流路２８−２を介して流通していたアンモニアガス（流量８ｌ／ｍｉｎ．）５１−１とジシランガス（１０ｃｃ／ｍｉｎ．）５１−３と水素ガス（流量５ｌ／ｍｉｎ．）との混合ガスの流路を第２の原料供給流路２８−２より第２の排気系流路２９ａへと切り換えた。次に、ジシランガスの流路を第１の原料供給流路２７−２から第１の排気系流路２９−２へと変更した。
【０１１３】
一方、アンモニアガス５１−１は配管系５２を通じて気相成長領域３９へ継続して流通させて、成長中断時に於けるＧａＮ層８９からの窒素（Ｎ）の蒸発を抑制した。同時にサファイア基板８７の温度を１０８０℃から８９０℃に約１分間で降温した。
【０１１４】
基板８７の温度を降温する間に、予め、第１の排気系流路２９−１に所定の流量をもって流通していたインジウム源１１の蒸気を随伴する水素ガスの流路を第１の原料供給流路２７−１へと変更した。これより、第１の原料供給流路２７−１の内部において、平均的なインジウム（Ｉｎ）組成比が０．１２の窒化ガリウム・インジウム（組成式Ｇａ0.88Ｉｎ0.12Ｎ）が得られる様にガリウム源１０とインジウム源１１とを予め混合させて流通させた。インジウム源１１の蒸気を随伴する水素ガスを第１の原料供給流路２７−１に合流させてから５秒を経過する迄、第２の排気系流路２９ａに通流し、混合比率の安定した定常流とした。
【０１１５】
また、アンモニアガス５１−１の流路を第１の排気系流路２９−２から第１の原料供給流路２７−２へと切り換えると共に、流量を８リットル／分に調整したアンモニアガス５１−１を第２の原料供給流路２８−２から再び気相成長領域３９に供給した。上記の予め混合された第ＩＩＩ族原料ガスの流路を第２の排気系流路２９ａから第２の原料供給流路２８−１に変更してＧａ0.88Ｉｎ0.12Ｎ発光層９０の成長を開始した。Ｇａ0.88Ｉｎ0.12Ｎ発光層９０の結晶組織構造は、本発明者の発明に開示されている、インジウム組成比を相違する複数の相（ｐｈａｓｅ）からなる多相（ｍｕｌｔｉｐｈａｓｅ）構造とした（▲１▼英国特許ＧＢ２３１６２２６Ｂ号、▲２▼米国特許ＵＳ５，８８６、３６７号、及び▲３▼中華民国（台湾）特許第０９９６７２号参照）。層厚を１０ｎｍとするＧａ0.88Ｉｎ0.12Ｎ発光層９０の成長を、ガリウム源１０とインジウム源１１との混合ガスの気相成長領域３９への供給を停止して終了した。
【０１１６】
アンモニアガス５１−１は第１の原料供給流路２７−２及び配管系５２より第２の原料供給流路２８−２を経由して気相成長領域３９へ流通し続けて、多相構造のＧａ0.88Ｉｎ0.12Ｎの昇華に因る発光層９０の損失を防止した。この状態でサファイア基板８７の温度を８９０℃から１０５０℃に昇温した。
【０１１７】
昇温中に、インジウム源１１の蒸気を随伴する水素ガスを、バルブ３１−１を開より閉とし、バルブ３４−１を閉から開状態として第１の排気系流路２９−１に排出させた。併せて、ガリウム源１０の蒸気を含む水素ガスの流量を変更して第１の原料供給流路２７−１より第２の排気系流路２９ａへと流通し始めた。また、原料気体流路１５−１を利用して、予め、第１の排気系流路２９−１及び第２の排気系流路２９ａを介して排出していたｐ形ドーパントとしてのビスシクロペンタジエニルインジウム（ｂｉｓ−（Ｃ5Ｈ5）2Ｍｇ）１２’を随伴した水素ガスの流路を３方バルブ３５−１を閉とし、４方バルブ３２−１を開として第１の排気系流路２９−１から第１の原料気体流路２７−１へ切り換えた。
【０１１８】
次に、第１の原料気体流路２７−１に予め、混合させて流通させておいた上記のガリウム源１０及びマグシウム（元素記号：Ｍｇ）源１２’の混合ガスの流路を第２の排気系流路２９ａから第２の原料供給流路２８−１へと変換した。これより、既に、第２の原料気体流路２８−２を介してアンモニアガス５１−１が供給されている気相成長領域３９へのガリウム源１０及びマグネシウム源１２’を供給し、Ｍｇドープｐ形ＧａＮ層９１の成長を開始した。所定の時間、原料ガスの流通を継続して、キャリア濃度を３×１０17ｃｍー3とし、層厚を１０ｎｍとするｐ形ＧａＮ層９１を成長させた。ｐ形ＧａＮ層９１の成長は、上記のガリウム源１０及びマグネシウム源１２’の流路を第２の原料供給流路２８−１から第２の排気系流路２９ａへ切り換えることをもって終了した。
【０１１９】
成長を終了して１分経過後、第２の原料供給流路２８−２を通して流通させていたアンモニアガス５１−１の流路を第２の排気系流路２９ａへ変更した。気相成長領域３９へは、配管系５２を通じて介してアンモニアガス５１−１の供給を継続しつつ、サファイア基板８７の温度を１０５０℃から９５０℃に毎分５０℃の速度で降温した。引き続き、６５０℃に毎分１５℃の速度で降温した。基板８７の温度が６５０℃未満となった時点で、バルブ３６−２を閉とし、バルブ３７−２を開として配管系５２を通じてのアンモニアガス５１−１の供給を停止した。その後、自然放冷により形成された積層構造体８６を室温迄、冷却した。
【０１２０】
積層構造体８６のダブルヘテロ接合構造からなる発光部８６ａは、上記のＳｉドープｎ形ＧａＮ層からなる下部クラッド層８９、インジウム組成に関する多相構造のＧａ0.88Ｉｎ0.12Ｎからなる発光層９０、及びＭｇドープｐ形ＧａＮ層からなる上部クラッド層９１とから構成した。一般的な２次イオン質量分析法（英略称：ＳＩＭＳ）に依れば、発光層９０と上部クラッド層９１との接合界面から上部クラッド層９１の内部方向へのインジウム原子濃度の遷移距離（特開平１１−１６８２４１号公報参照）は約１０ｎｍであり、本発明者の開示による高強度の短波長発光をもたらすに必要とされる組成急峻性を充分に満たすものとなった（上記の特開平１１−１６８２４１号公報参照）。
【０１２１】
また、多相構造の発光層９０を主体的に構成する母体相（ｍａｔｒｉｘ ｐｈａｓｅ）はインジウム組成比の小ささから略ＧａＮで構成されるものとなり、従って、発光層９０と下部クラッド層８９とは、高強度の発光をもたらすために本発明者により開示されている伝導帯側のバンド不連続性或いは接合様式を満足するヘテロ接合構造となった（日本国特許第２９９２９３３号参照）。
【０１２２】
積層構造体８６の一部の領域に一般的なプラズマエッチング加工を施して、ｎ形オーミック電極９２を形成する予定の領域の上部クラッド層９１及び発光層９０を除去した。ｐ形オーミック電極９３は上部クラッド層９１の表面上に形成してＬＥＤ８５となした（特開平１０−１０７３１５号公報参照）。
【０１２３】
ＬＥＤ８５からは２０ｍＡの順方向電流の通流時に波長を約４６０ｎｍとする青色の発光が放射された。順方向電流を２０ｍＡとした際の順方向電圧は３．８Ｖとなった。図２３に発光スペクトルを示す。発光層９０と上部クラッド層９１との接合界面の急峻性を反映して、発光スペクトルの半値幅（ＦＷＨＭ）は１０ｎｍと優れたものとなった。ＬＥＤ８５のチップ（ｃｈｉｐ）を一般的な半導体素子封止用のエポキシ樹脂で封止した状態での発光輝度は約１．２カンデラ（ｃｄ）であった。本発明に依れば発光スペクトルの半値幅の狭い、即ち、発光の単色性に優れ、且つ、高発光強度のＧａＩｎＮ系発光素子が提供されることとなった。
【０１２４】
【発明の効果】
本発明の構成の原料供給流路を備えた気相成長装置に依れば、混合比の変動の少ない原料ガスを気相成長領域内へと導入できるため、組成の急峻性に優れる半導体接合界面をもたらすことができる。
【０１２５】
特に、排気系流路に搬送用気体を流入させる機構を設け、更に排気系流路と原料供給流路間に差圧計を設けた気相成長装置に依れば、原料供給流路と気相成長領域への流路間の圧力差を低減できるため、流路切り替え時の原料ガスの流量変動を減少させられ、急峻な半導体接合界面を安定して形成することができる。
【０１２６】
また、原料気体の流路を気相成長領域に直結する原料供給流路と排気系流路とに切り替える機構を２系列以上具備した気相成長装置に依れば、会合反応性の高い複雑な組み合わせの原料種とする場合にあっても、組成の安定性に優れ、且つ急峻性に優れる半導体接合界面が形成できる。
【０１２７】
特に、複数の原料供給配管系を具備した気相成膜装置にあって、沸点の低い第Ｖ族または第ＶＩ族元素の水素化物を原料気体とすれば、気相成長領域より遠方に第Ｖ族または第ＶＩ族源を配置しても配管系内での凝縮を回避できるため、組成が安定し、且つ急峻性に優れるＩＩＩ−Ｖ族化合物半導体混晶を成膜することができる。また、凝縮を回避できるため、揮発性に富む構成元素源を気相成長領域に安定して供給でき、表面状態に優れる成長層を得るに効果がある。
【０１２８】
本発明の気相成膜装置に依れば、急峻なヘテロ接合界面を備えた形成でき、高い電子移動度を顕現する積層構造体がもたらされるため、相互コンダクタンスに優れる例えば、ＧａＩｎＰ／ＧａＩｎＡｓ系２次元電子電界効果型トランジスタが得られる効果がある。また、高電子移動度が得られるＩｎＰ／ＧａＩｎＡｓ系ヘテロ接合積層構造体からは、積感度の大きな高感度のヘテロ接合系ホール素子がもたらされる効果がある。更に、本発明に係る積感度の高いＩｎＰ／ＧａＩｎＡｓ系ホール素子を利用すれば高感度の磁界強度定用の測定子（プローブ）が構成できる。
【０１２９】
また、本発明の成長方法により形成された急峻な接合界面を内包する積層構造体を利用すれば、発光の単色性に優れる発光素子が得られる効果がある。例えば、発光スペクトルが挟帯化されたＧａＩｎＮ系短波長可視ＬＥＤが構成できる効果がある。
【図面の簡単な説明】
【図１】従来の単一のベント／ラン方式の配管系の概略構成図を示す。バルブ１９と２２、２０と２３、２１と２４は、各々を同時に開状態とすることはない。
【図２】本発明に係わる配管系の概略構成図を示す。
【図３】本発明に係わる別の配管系の概略構成図を示す。
【図４】本発明に係わる他の配管系の概略構成図を示す。
【図５】図４に示す配管系の一変形例を示す模式図である。
【図６】実施例に記載の配管系を備えた気相成長装置の概略図である。
【図７】実施例に記載の手段により成長された積層構造体のＣＡＴ像である。
【図８】比較例に記載の手段により成長した積層構造体のホール抵抗の磁場強度依存性を示す図である。
【図９】比較例に記載の手段により成長された積層構造体のＣＡＴ像である。
【図１０】比較例に記載の手段により成長した積層構造体のホール抵抗の磁場強度依存性を示す図である。
【図１１】２次元電子電界効果型トランジスタ（ＴＥＧＦＥＴ）の断面模式図である。
【図１２】実施例３に記載の気相成長装置の配管系統を示す概略図である。
【図１３】実施例３に記載のＡｌＩｎＡｓ／ＧａＩｎＡｓ積層構造体の断面模式図である。
【図１４】磁気抵抗（２階微分値）の磁場強度依存性を示す図である。
【図１５】フィリングファクターと磁場強度の逆数値との相関を示す図である。
【図１６】ホール電圧の磁場強度依存性を示す図である。
【図１７】実施例４に記載の気相成長装置の配管系を示す概略図である。
【図１８】ＩｎＰ／ＧａＩｎＡｓヘテロ接合ホール素子の断面模式図である。
【図１９】磁界強度測定用のホール素子プローブの平面模式図である。
【図２０】ホール素子プローブの入力抵抗と積感度との相関を示す図である。英字ＧａＩｎＡｓは本発明に係わるＩｎＰ／ＧａＩｎＡｓホール素子を備えたプローブの、また英字ＧａＡｓは従来のＧａＡｓホール素子プローブを各々示す。
【図２１】ＧａＩｎＮ系ＬＥＤの断面模式図である。
【図２２】実施例７に記載の気相成長装置の配管系を示す概略図である。
【図２３】実施例７に記載のＧａＩｎＮ系ＬＥＤの発光スペクトルを示す図である。
【符号の説明】
１０ 第ＩＩＩ族構成元素源
１１ 第ＩＩＩ族構成元素源
１２ 第ＩＩＩ族構成元素源
１２’ドーピング用有機金属源
１３ 原料気体流路
１３−１ 原料気体流路
１３−２ 原料気体流路
１４ 原料気体流路
１４−１ 原料気体流路
１４−２ 原料気体流路
１５ 原料気体流路
１６ 流量計
１６−１ 流量計
１６−２ 流量計
１７ 流量計
１７−１ 流量計
１７−２ 流量計
１８ 流量計
１９ ２方バルブ
２０ ２方バルブ
２１ ２方バルブ
２２ ２方バルブ
２３ ２方バルブ
２４ ２方バルブ
２５ 原料供給（ラン）流路
２６ 排気系（ベント）流路
２７ 第１の原料供給流路
２７−１ 第１の原料供給流路
２７−２ 第１の原料供給流路
２８ 第２の原料供給流路
２８−１ 第２の原料供給流路
２８−２ 第２の原料供給流路
２９ 第１の排気系流路
２９−１ 第１の排気系流路
２９−２ 第１の排気系流路
２９ａ 第２の排気系流路
３０ バルブ
３０−１ バルブ
３０−２ バルブ
３１ バルブ
３１−１ バルブ
３１−２ バルブ
３２ バルブ
３２−１ バルブ
３３ バルブ
３３−１ バルブ
３３−２ バルブ
３４ バルブ
３４−１ バルブ
３４−２ バルブ
３５ バルブ
３５−１ バルブ
３６ バルブ
３６−１ バルブ
３６−２ バルブ
３７ バルブ
３７−１ バルブ
３７−２ バルブ
３８ 第１及び第２の排気系流路を接続するバルブ
３９ 気相反応領域
４０ 排気処理設備
４１ 第１の原料供給流路上流の搬送ガス用配管
４２ 第１の排気系流路上流の搬送ガス用配管
４３ 第１の原料供給流路用流量計
４３−１ 第１の原料供給流路用流量計
４３−２ 第１の原料供給流路用流量計
４４ 第１の排気系流路用流量計
４４−１ 第１の排気系流路用流量計
４４−２ 第１の排気系流路用流量計
４５ 第２の原料供給流路上流の搬送ガス用配管
４６ 第２の排気系流路上流の搬送ガス用配管
４７ 第２の原料供給流路用流量計
４７−１ 第２の原料供給流路用流量計
４７−２ 第２の原料供給流路用流量計
４８ 第２の排気系流路用流量計
４９ 第ＩＩＩ族構成元素源供給用配管系
５０ 第Ｖ族構成元素源供給用配管系
５１ 第Ｖ族構成元素源
５１−１ 第Ｖ族構成元素源
５１−２ 第Ｖ族構成元素源
５１−３ ドーピング源
５２ 揮発性構成元素供給用配管
５３ 揮発性構成元素供給用配管に付帯するバルブ
５４ 揮発性構成元素供給用配管に付帯するバルブ
５５ 差圧計
５５−１ 差圧計
５５−２ 差圧計
５６ 差圧計
５７ Ｖ族構成元素源用配管
５８ ドーピング源供給用配管
５９ ＧａＡｓ単結晶基板
６０ ＧａＡｓ緩衝層
６１ ＧａＩｎＡｓチャネル層
６２ ＧａＩｎＰ電子供給層
６３ 緩衝層／チャネルヘテロ接合界面
６４ チャネル層／電子走行層ヘテロ接合界面
６５ 電子線干渉縞
６６ ２次元電子電界効果型トランジスタ（ＴＥＧＦＥＴ）
６７ ＴＥＧＦＥＴ用途積層構造体
６８ オーミックコンタクト層
６９ ソース電極
７０ ドレイン電極
７１ ゲート電極
７２ ゲートコンタクト層
７３ ＡｌＩｎＡｓ／ＧａＩｎＡｓヘテロ接合系積層構造体
７４ ＩｎＰ単結晶基板
７５ 高抵抗ＩｎＰ緩衝層
７６ ＧａＩｎＡｓ電子走行層
７７ ＡｌＩｎＡｓスペーサ層
７８ ＡｌＩｎＡｓ電子供給層
７９ ＩｎＰ単結晶基板
Ａ１ アルミニウム源流路用４方バルブ
Ａ２ アルミニウム源流路用３方バルブ
Ａ１８ アルミニウム源用流量計
８０ ｎ形ＩｎＰ緩衝層
８１ Ｇａ0.47Ｉｎ0.53Ａｓ層
８２ ＩｎＰ／ＧａＩｎＡｓ積層構造体
８３ ＩｎＰ／ＧａＩｎＡｓヘテロ接合ホール素子
８３ａ オーミック電極
８４ ＩｎＰ／ＧａＩｎＡｓヘテロ接合ホール素子プローブ
８５ ＧａＩｎＮ系ＬＥＤ
８７ サファイア基板
８８ 緩衝層
８９ ｎ形ＧａＮ下部クラッド層
９０ ＧａＩｎＮ発光層
９１ ｐ形ＧａＮ層上部クラッド層[0001]
BACKGROUND OF THE INVENTION
More particularly, the present invention relates to a vapor phase growth apparatus suitable for forming a steep semiconductor hetero (heterogeneous) junction interface composition. The present invention also relates to a vapor phase growth method using the vapor phase growth apparatus, a laminated structure formed by the method, a field effect transistor composed of the laminated structure, a semiconductor Hall element, and a semiconductor light emitting element. .
[0002]
[Prior art]
Conventionally, single-hetero (English abbreviation: SH) or double-hetero (abbreviation: DH) structure light-emitting elements, epitaxial layered structures for two-dimensional electron field effect transistors (TEGFET), etc. It is formed by vapor phase growth means such as decomposition chemical deposition (MOCVD) method (see Solid State Electron., Vol. 43 (1999), pages 1577 to 1589). In this case, in particular, in the formation of a laminated structure for TEGFET use, steepness of composition change at the heterojunction interface is required in order to efficiently express the effect of two-dimensional electrons (TEG). (Refer to Physics Society of Japan, “Physics and Applications of Semiconductor Superlattices”, 4th edition, first edition, September 30, 1986, published by Baifukan Co., Ltd., pages 139-145).
[0003]
In a conventional vapor phase growth apparatus for vapor phase growth of a semiconductor crystal, for example, a III-V group compound semiconductor crystal layer, by MOCVD, a group III constituent element source or a group V constituent element source is required for the growth of the crystal layer. (1) J. Crystal Growth, Vol. 55 (1981), pp. 64-73, (2) The same volume of the same magazine. Pp. 92-106, (3) ibid, ibid, pages 164-172, and (4) ibid, ibid, pages 213-222). That is, in the conventional vapor phase growth apparatus, the constituent element material or doping source has a piping configuration that supplies the vapor phase reaction region only when necessary, and the material that is temporarily unnecessary for the vapor phase growth of the crystal layer. The supply of gas was temporarily stopped by valve operation.
[0004]
In the piping system of such a conventional vapor phase growth apparatus, when the raw material gas is needed again, it is necessary to open the valve and circulate the raw material gas again into the vapor phase growth region. However, for a while when the flow is started again from the blocked state, the flow rate changes transiently due to the pressure fluctuation in the piping system accompanying the transition to the open state of the valve, and the raw material gas is sealed in the piping. Or the fall of the purity accompanying the staying had arisen. Such a transient change in the flow rate of the raw material gas and a decrease in the purity caused a compositional change between the elements constituting the crystal layer, making it difficult to form a bonding interface having excellent composition steepness. For this reason, the conventional vapor phase growth apparatus using a piping system is currently unsuitable for vapor phase growth of a laminated structure for TEGFET that requires a steep heterojunction interface, for example.
[0005]
In order to compensate for the shortcomings of the piping system of such a vapor phase growth apparatus and form a semiconductor junction interface with excellent composition steepness, the raw material gas can be constantly circulated and the raw material gas flowing into the vapor phase growth region can be instantaneously supplied. A feed gas supply piping system called a vent / run system having a switching mechanism has been proposed (1) J. Crystal Growth, Vol. 68 (1984), pages 412 to 421. , (2) the same volume, pp. 466-473, and Akazaki Isao, “III-V Group Compound Semiconductor” (Baifukan Co., Ltd., first published on May 20, 1994), pages 68-70). The vent channel (exhaust system channel) allows the source gas to continuously flow outside the gas phase reaction region in advance, regardless of whether or not it is necessary for the vapor phase growth of the target crystal layer. It is a flow path provided to create a flow. The run flow path (raw material supply flow path) is a flow path that directly connects to the gas phase reaction region by switching the raw material gas required for vapor phase growth of the target crystal layer from the exhaust system flow path. In other words, the vent / run system is different from the conventional piping system having only the raw material supply flow path, and has an exhaust system flow path for constantly flowing the raw material gas.
[0006]
FIG. 1 illustrates a raw material gas supply piping system having a vent / run system. The raw material gas flow paths 13, 14, and 15 for distributing the raw material gases 10, 11, and 12 made of a gas accompanying the gas raw material or the vapor of the raw material are provided for each type of the raw material gases 10 to 12. The flow rates of the source gases 10 to 12 flowing through the source gas channels 13 to 15 are adjusted by flow meters 16, 17 and 18. Conventionally, the raw material gas flow paths 13 to 15 provided corresponding to the raw material gas are connected to the raw material supply flow path 25 and the exhaust system flow path 26 via two-way valves 19 to 24. ing.
A two-way valve is a valve body opening / closing operation that determines whether a fluid flows or is blocked in a single flow path. The raw material supply system 25 is directly connected to a gas phase reaction region where a crystal layer is deposited. Further, the exhaust system flow path 26 is directly connected to an exhaust system that performs an exhaust process bypassing the gas phase reaction region.
[0007]
Switching of the source gases 10 to 12 from the source supply channel 25 to the exhaust system channel 26 or vice versa is performed by the channel switching valves 19 to 24 installed in the source gas channels 13 to 15, respectively. This is done by opening and closing operations. For example, in order to switch the raw material gas 10 circulated through the raw material gas flow path 13 from the exhaust system flow path 26 to flow through the raw material supply flow path 25, the two-way valve 22 is synchronized with the closed state. This is done by opening the one-way valve 19. Here, the two-way valves 19 and 22 do not always open at the same time, and the same applies to the two-way valves 20 and 23 and 21 and 24.
[0008]
[Problems to be solved by the invention]
A conventional vent / run type supply system is constituted by a piping system comprising a combination of a single raw material supply flow path 25 and a single exhaust system flow path 26. For example, in a vent / run system (single vent-run system) composed of such a combination, the material gas is instantaneously supplied to the material supply channel 25 by changing from the exhaust system channel 26. During a period of time after circulating the gas, periodic fluctuations occur in the flow rate of the raw material gas. Although the fluctuation of the flow rate is alleviated while the raw material gas is transferred to the gas phase reaction region in the raw material supply channel 25, the fluctuation of the supply amount of the raw material gas in the gas phase reaction region still remains. . Variations in the supply amount of the source gas cause variations in the composition ratio and the like in the increasing direction of the crystal layer thickness, and, for example, cause problems that prevent abrupt changes in the composition at the heterojunction interface.
[0009]
Specifically, the problems of the conventional single vent / run type material supply piping system will be described with reference to FIG. For example, after two kinds of gas raw materials 10 and 11 have already flowed through the raw material gas passages 13 and 14 to the raw material supply passage 25 at a stable flow rate to vapor-phase grow the crystal layer, this time, It is assumed that a mixed crystal layer using three kinds of source gases 10 to 12 is vapor-phase grown. In this state, in order to grow the mixed crystal layer, it is necessary to further switch the flow path of the raw material gas 12 from the exhaust system flow path 26 to the raw material supply flow path 25 by opening and closing the two-way valves 21 and 24. At the instant of switching, the flow rate of the raw material gas 12 periodically varies and becomes unstable. Due to the instability of the flow rate of the raw material gas 12, the composition of the constituent elements of the mixed crystal related to the raw material gas 12 becomes unstable. In particular, it is difficult to obtain the steepness of the composition in the bonding interface region.
[0010]
In the conventional single vent / run type material supply piping system (see FIG. 1), when the mixed crystal layer is vapor-phase grown using three kinds of material gases 10-12, the flow path of the material gases 10-12 Even if the exhaust system flow path 26 and the raw material supply flow path 25 are simultaneously switched, the flow rate fluctuates inside the raw material supply flow path 25. This is because it is difficult to make the pressure difference zero between the raw material gas flow paths 25 and 26. For this reason, there is a problem that the flow rate of each gaseous raw material in the raw material supply flow path 25 fluctuates with switching of the raw material supply flow path from the exhaust system flow path. There is a problem that stable vapor phase growth of the mixed crystal layer cannot be realized when the raw material gas having such a flow rate change is supplied to the reaction region.
[0011]
These problems are caused by fluctuations in the flow rate of the raw material gas and instability in the mixing ratio of the raw material gas when the flow path of the conventional single vent / run type raw material supply system is switched. It is an object of the present invention to solve this.
[0012]
[Means for Solving the Problems]
As a result of diligent efforts to solve the above problems, the present inventor switched the mixed source gas flow path instantaneously and supplies it to the vapor phase growth region when the mixing ratio of the source gas became constant. The present invention has been completed by finding that a pipe structure can stably form a bonding interface having excellent compositional steepness. That is, the present invention
[1] In a vapor phase growth apparatus for forming a laminated structure in which a semiconductor crystal layer is laminated on a substrate material, one or a plurality of vapor phase growth raw materials are mixed with a carrier gas in advance and distributed. A first raw material supply channel, a second raw material supply channel for introducing the mixed vapor phase growth raw material into the vapor phase growth reaction region, and for exhausting the vapor phase growth reaction region. And the mixed vapor phase growth raw material flow path which is circulated through the first raw material supply flow path is used as the second raw material supply flow path or the exhaust system flow path. A vapor phase growth apparatus comprising a flow path switching mechanism for switching to any of the above,
[2] The vapor phase growth apparatus according to [1], wherein the exhaust system flow path has a mechanism for introducing a transfer gas.
[3] The first source supply channel has two or more channel switching mechanisms for switching to either the second source supply channel or the exhaust system channel [1] or [2] The vapor phase growth apparatus according to
[4] An apparatus for measuring a differential pressure between the first material supply channel or the second material supply channel and the exhaust system channel is provided [1] to [3] ] The vapor phase growth apparatus according to any one of
[5] The vapor phase growth apparatus according to any one of [1] to [4], wherein the vapor phase growth material contains a hydride of a group V or group VI element,
[6] After the mixing ratio of the vapor phase growth raw material previously mixed in the first raw material supply flow path is made constant, the vapor growth raw material flow path is connected to the second raw material supply flow from the exhaust system flow path. A vapor phase growth method of a laminated structure using the vapor phase growth apparatus according to any one of [1] to [5],
[7] When the flow path of the vapor phase growth raw material previously mixed in the first raw material supply flow path is switched from the exhaust system flow path to the second raw material supply flow path, the first raw material supply flow path and the second raw material supply flow path The differential pressure between the raw material supply flow path is 5 × 102The vapor phase growth method for a stacked structure using the vapor phase growth apparatus according to any one of [1] to [5], wherein the state is switched to a state of Pascal (Pa) or lower,
[8] The vapor phase growth method according to [6] or [7], wherein a laminated structure is formed according to the organometallic pyrolysis vapor phase growth method,
[9] A laminated structure formed by the vapor phase growth method according to any one of [6] to [8],
[10] The multilayer structure according to [9], wherein the multilayer structure is a multilayer multilayer structure having a hetero (heterogeneous) junction structure,
[11] The multilayer structure according to [10], wherein the multilayer structure is a multilayer multilayer structure for field effect transistors.
[12] A multilayer laminated structure for a field effect transistor is formed using a gallium phosphide-indium (composition formula GaXIn1-XP: 0 ≦ X ≦ 1) and gallium arsenide / indium (composition formula Ga)YIn1-YA multilayer structure according to [11], wherein the multilayer structure has a heterojunction with As: 0 ≦ Y ≦ 1),
[13] A multilayer laminated structure for a field effect transistor is made of aluminum arsenide / indium (compositional formula AlXIn1-XAs: 0 ≦ X ≦ 1) and gallium arsenide / indium (composition formula Ga)YIn1-YA multilayer structure according to [11], wherein the multilayer structure has a heterojunction with As: 0 ≦ Y ≦ 1),
[14] The multilayer structure according to [10], wherein the multilayer structure is a multilayer structure for III-V compound semiconductor Hall element use,
[15] A stacked structure is formed by using indium phosphide (chemical formula: InP) and gallium arsenide / indium (composition formula Ga).YIn1-YA multilayer structure according to [14], wherein the multilayer structure has a heterojunction with As: 0 ≦ Y ≦ 1),
[16] The multilayer structure according to [10], wherein the multilayer structure is a multilayer structure for use in a group III nitride semiconductor light-emitting device.
[17] The laminated structure is made of aluminum nitride gallium (composition formula AlXGa1-XN: 0 ≦ X ≦ 1) and aluminum nitride, gallium, indium (composition formula (AlXGa1-X)YIn1-YN: a multilayer structure having a heterojunction of 0 ≦ X ≦ 1, 0 ≦ Y <1), and the multilayer structure according to [16],
[18] A field effect transistor using the laminated structure according to [11],
[19] Indium gallium arsenide (composition formula GaYIn1-YA field effect transistor according to [18], wherein the field effect transistor is composed of a stacked structure including As) as an active layer;
[20] A III-V compound semiconductor Hall element using the multilayer structure according to [14],
[21] A group III-V compound semiconductor Hall element according to [20], comprising the laminated structure according to [15],
[22] A group III nitride semiconductor light-emitting device using the multilayer structure according to [16],
[23] The group III nitride semiconductor light-emitting device according to [22], comprising the laminated structure according to [17].
[0013]
DETAILED DESCRIPTION OF THE INVENTION
An example of a flow path having the configuration of the present invention is schematically shown in FIG. The flow path piping system according to the present invention is characterized by the first and second plurality of raw material supply channels (first and second raw material supply channels) 27 and 28 and the respective raw material supply channels 27 and 28. The first and second exhaust system flow paths (first and second exhaust system flow paths) 29 and 29a are provided correspondingly. In other words, a double vent / run (Double Vent-Run) mechanism is provided instead of the conventional single vent / run system. According to the piping mechanism of the present invention, the raw material gas is supplied to the gas phase reaction region 39 through the raw material supply channels 27 and 28 assembled in two stages. The double vent / run type mechanism according to the present invention is, for example, a group III-V or II-VI compound by a reduced pressure or atmospheric pressure (substantially atmospheric pressure) MOCVD method or a halogen or hydride VPE method. It can be suitably used for a vapor phase growth apparatus such as a semiconductor crystal. Further, it can also be suitably used for a vapor phase growth apparatus of silicon (element symbol: Si) / germanium (element symbol: Ge) mixed crystal.
[0014]
The first raw material supply flow path 27 is a flow path that is installed in order to collect and circulate the raw material gases related to the elements constituting the crystal layer in advance. The first raw material supply flow path 27 is switched from the first exhaust system flow path 29 by, for example, opening and closing operations of the four-way valves 30 to 32 and the three-way valves 33 to 35 that operate in synchronization therewith. All raw material gases required for the vapor phase growth of the crystal layer are circulated in advance. A four-way or cross valve is a valve that can be switched between two flow paths. If the valve body is in an open state, the valve can conduct one channel and another channel, and conversely, if the valve body is closed, the valve can shut off the two channels. A three-way valve is a so-called three-way valve having a mechanism that allows a fluid to be added to a flow path that flows in one direction. In the open three-way valve, one flow path and a flow path intersecting with the flow path are electrically connected. In the closed state, the fluid flowing in the intersecting flow paths is not flowed in one flow path. For example, aluminum arsenide / gallium mixed crystal (composition formula AlXGa1-XWhen As: 0 <X <1) is vapor-phase grown by, for example, the MOCVD method, source gases of constituent elements such as aluminum (element symbol: Al), gallium (element symbol: Ga), and arsenic (element symbol: As) 10, 11, and 12 are circulated through the first raw material supply channel 27 in advance at a flow rate mixing ratio that provides a desired aluminum composition ratio (= X). At this time, the four-way valves 30, 31, 32 are opened, the three-way valves 33, 34, 35 are closed, and the flow path from the first exhaust system flow path 29 to the first raw material supply flow path 27 is closed. Although the flow rate periodically varies with the switching, the mixed gas having an unstable mixing ratio is closed without closing the four-way valve 36 and the three-way valve 37 and supplying the gas phase growth region 39 without being supplied. 2 to the exhaust system flow path 29a and exhausted by the exhaust treatment facility 40.
[0015]
In the present invention, since a mechanism for switching the premixed raw material gas flow path 27 from the vapor phase growth region flow path 28 to the exhaust system flow path 29 a is added, At the stage where the flow rate fluctuations of the respective raw material gases collected and circulated are eliminated, the three-way valve 37 is closed, the four-way valve 36 is opened, and the raw material supply passage 27 through which the raw material gas flows is provided. The source gas can be supplied to the gas phase reaction region 39 by switching from the second exhaust system channel 29 a to the second source supply channel 28. Along with this switching, the flow rate of the raw material gas flowing through the first raw material supply channel 27 instantaneously fluctuates, but the first raw material supply channel 27 of the present invention already has a stable mixing ratio. Therefore, all of the raw material gases are only subjected to equivalent fluctuations at a time, and the composition ratio of the mixed crystals to be formed is not changed. Further, according to the double vent / run system, depending on the utility of the second raw material supply flow path, the raw material gas having a stable mixing ratio is supplied to the gas phase regardless of the order of mounting to the first raw material supply flow path. It can be delivered to the growth area 39. Preferably, the higher the boiling point of the raw material, the raw material is mounted at the position of the raw material supply flow path where the path to the vapor phase growth region 39 becomes shorter.
[0016]
The vapor phase growth apparatus having the above double vent / run type piping system is, for example, zinc selenide / magnesium sulfide (composition formula ZnXMg1-XS1-YSeY: 0 <X, Y <1), etc., can be used for vapor phase growth of II-VI compound semiconductor crystal layers. In particular, as a source gas of a Group VI constituent element, for example, hydrogen selenide (molecular formula: H2Se) and hydrogen sulfide (molecular formula: H2If S) is used, condensation of the raw material gas in the piping system can be prevented, so that it can be suitably applied to obtain a mixed crystal layer having a desired composition ratio.
[0017]
In FIG. 2, the first exhaust system flow path 29 is an exhaust installed corresponding to the first raw material supply flow path 27 in order to circulate a raw material gas unnecessary for the vapor phase growth of the crystal layer. This is a pipe for use. Further, the second exhaust system flow passage 29a is configured to supply a second raw material in order to collect and exhaust raw material gases unnecessary for vapor phase growth that are circulated through the first exhaust system flow passage 29 collectively. This is a pipe for exhaust use installed corresponding to the flow path 28. The second raw material supply channel 28 is directly connected to a gas phase reaction region (container) 39. On the other hand, the second exhaust system flow path 29a is not connected to the gas phase reaction region 39, and is configured to bypass the gas phase reaction region 39 and directly connect to the facility 40 that performs exhaust processing. The exhaust treatment facility 40 can be composed of a combustion type or adsorption type abatement device. If the first exhaust system flow path 29 and the second exhaust system flow path 29a are connected, the pressures in both the exhaust system flow paths 29 and 29a become equal. For example, if the three-way valve 38 is opened, the pressure difference (differential pressure) between the exhaust flow paths 29 and 29a can be eliminated. In order to make the internal pressure of the first or second exhaust system flow path 29, 29a and the internal pressure of the first or second raw material supply flow path 27, 28 equivalent to each other, the exhaust system flow path It is preferable to provide a mechanism for allowing the transfer gas to flow in. For example, the transfer gas pipe 46 provided in the exhaust system flow path 29a and the transfer gas pipe 42 provided in the exhaust system flow path 29 in FIG. By adjusting the gas flow meter 48 with the gas flow meter 48, the internal pressures of the second raw material supply channel 28 and the second exhaust system flow channel 29a can be made equal to each other, and the first raw material supply channel When the flow of the raw material gas circulated in the flow passage 27 is changed from the second exhaust system flow passage 29a to the second raw material supply flow passage 28 and is circulated, it is effective in suppressing transient fluctuations in the flow rate. It is done.
[0018]
As described above, the present invention is characterized in that a mechanism for switching the first raw material supply flow path 27 from the second raw material supply flow path 28 and connecting it to the second exhaust system flow path 29a is added. And If the first raw material supply flow path 27 is connected to the second exhaust system flow path 29a, the raw material gas passes through the gas phase reaction region 39 when the raw materials are unnecessary or when the mixing ratio of the raw materials is unstable. Without being involved, that is, without being involved in the vapor deposition reaction. Therefore, by using the piping system of the present invention, there is an advantage that a stable flow of the source gas can flow into the gas phase reaction region. Changing the flow path of the first raw material supply flow path 27 from the second raw material supply flow path 28 to the second exhaust system flow path 29a or vice versa is performed by opening and closing valves 36 and 37. If the valve 36 is closed and the valve 37 is opened, the flow path can be switched from the second raw material supply flow path 28 to the second exhaust system flow path 29a. In order to change the flow path by reducing the “stagnation” of the raw material gas, for example, a pressure-operated four-way valve can be suitably used as the valve 36 related to the second raw material supply flow path 28. A three-way valve can be suitably used for the valves 37 and 38 related to the second exhaust system flow passage 29a.
[0019]
In the present invention, flow paths 41 and 42 for individually feeding the carrier gas into the flow paths 27 and 29 are connected upstream of the first raw material supply flow path 27 and the first exhaust system flow path 29. In addition, flow rate control devices 43 and 44 for independently controlling the flow rate of the inflowing carrier gas are provided to constitute a raw material gas supply piping system (see FIG. 2). The first raw material supply flow path 27 and the first exhaust system flow path 29 each have a piping configuration capable of flowing a gas for use in conveyance (carrier gas) at a flow rate controlled exclusively for the first raw material supply passage. This is convenient for equalizing the internal pressure between the flow path 27 and the first exhaust system flow path 29. This will be described using the piping configuration shown in FIG. For example, the flow rate of the gas used for conveyance flowing through each flow path is independently appropriately adjusted and adjusted by flow meters 43 and 44 dedicated to the first raw material supply flow path 27 and the first exhaust system flow path 29. Thus, the internal pressure between the flow paths 27 and 29 can be equivalent. By maintaining the balance of the internal pressure between the two flow paths 27, 29, the raw material gas when changing the flow path from the first raw material supply flow path 27 to the first exhaust system flow path 29 or vice versa. The transient fluctuation of can be suppressed. The pressure difference between the two flow paths 27, 29 is 5 × 102When it is less than Pascal (Pa), it is particularly effective in suppressing transient fluctuations. The gas used for transportation does not necessarily need to be of the same type as the gas accompanying the above-mentioned raw material vapor. The gas that can be used for transportation is hydrogen (molecular formula: H2), Nitrogen (molecular formula: N2) Or argon (element symbol: Ar).
[0020]
In the present invention, in addition to the first raw material supply flow path 27 and the first exhaust system flow path 29, the second raw material supply flow path 28 and the second second supply flow path 28 connected to the first flow path systems 27 and 29 are provided. A flow rate control device for connecting flow channels 45 and 46 for individually introducing the carrier gas into each flow channel upstream of the exhaust system flow channel 29a and for independently controlling the flow rate of the carrier gas to be introduced. 47 and 48 are preferably provided. As illustrated in FIG. 2, the second raw material supply flow path 28 and the second exhaust system flow path 29a are individually adjusted and controlled by the flow meters 47 and 48 provided exclusively for the carrier gas. In this case, the internal pressure between the two flow paths 28 and 29a can be made more stable and equivalent.
[0021]
For example, when 27 channels are connected to 29a and 45 channels are connected to 28 by operating the valves 36 and 37, the difference in internal pressure between the channels 28 and 29a is 5 × 10 5.2If the pressure is kept below Pascal (Pa), the flow rate is transient when switching between the second flow paths 28 and 29a, that is, when 27 flow paths are connected to 28 and 45 flow paths are closed or 29a. This is effective in suppressing fluctuations. The gas used for transportation does not necessarily need to be the same species as the gas accompanying the vapor of the raw material and the first flow path system.2), Nitrogen (N2) Or argon (Ar).
[0022]
The embodiment of the present invention will be illustrated in more detail. FIG. 3 shows gallium phosphide indium (composition formula GaXIn1-XP: 0 ≦ X ≦ 1) Convenient for MOCVD growth of crystalline layers, especially steep heterojunction interfaces essential for high electron mobility characteristics such as two-dimensional electron field effect transistors and high sensitivity Hall elements The structure of the raw material supply piping system suitable for formation of is illustrated. In this configuration example, for the purpose of avoiding a complex (polymer) reaction caused by association of an organic group III compound, which is a group III constituent element material, and a group V element source, Separately from the piping system 49, phosphine (molecular formula: PHThreeA piping system 50 for supplying a group V element source (not shown in FIG. 3) such as) is separately arranged. The piping systems 49 and 50 relating to the Group III and Group V constituent element sources are both configured by a vent / run system. By installing supply piping systems 49 and 50 separately for Group III sources and Group V sources, it is possible to avoid association reactions between the sources, and to suppress fluctuations in the flow rate of each source gas. However, it can be supplied. This achieves vapor phase growth of an epitaxial heterojunction structure having a smooth composition with little composition variation and small surface roughness and excellent compositional steepness. The steepness of the heterojunction interface brought about by this configuration example is, for example, the electron beam interference fringe method (CAT method) using a transmission electron microscope (abbreviation: TEM) (Akira Tonomura, “ It can be measured by an evaluation means such as “Electron Microscope Technology” (see Maruzen Co., Ltd., issued on August 31, 1989), pages 83 to 90).
[0023]
The raw material supply piping system of FIG. 3 has a structure (Duplicate Vent-Run structure) having two series of the raw material supply piping system of FIG. 2 of the present invention. The effect of steepening the heterojunction interface according to the present invention is not impaired by the number of raw material supply piping systems provided. This is because, even when a plurality of raw material supply piping systems are provided, the flow path of the raw material gas can be instantaneously changed by the second vent / run mechanism described in the present invention. Further, in the relative arrangement with respect to the vapor phase growth region 39, for example, there is no particular restriction on the arrangement order of the piping systems for the group III and group V element material supply applications. A group III-V compound semiconductor crystal layer is in an MOCVD apparatus, and a group III element organometallic compound as a raw material has both a melting point and a boiling point as compared with a group V element hydride as a group V element source. high. For example, trimethylaluminum ((CHThree)ThreeAl) has a melting point of about 15 ° C., whereas arsine (AsH)Three) Has a melting point of about −117 ° C. Therefore, in order to suppress condensation in the raw material supply flow path, it is preferable to dispose a raw material supply system accompanying a raw material having a higher boiling point closer to the vapor phase growth region. Further, in a piping system of a vapor phase growth apparatus for III-V or II-VI compound semiconductors, which is usually kept at room temperature or higher, the hydride of Group V or Group VI has a boiling point. Is much lower than room temperature, so that it can be efficiently delivered to the vapor phase growth region without causing a decrease in supply amount or a decrease in concentration due to condensation. For this reason, it is effective in preventing deterioration of the surface state of the compound semiconductor crystal layer due to evaporation of the Group V or Group VI element.
[0024]
FIG. 4 is a schematic view of a raw material supply piping system showing another embodiment of the present invention. The feature of the piping system of this example is that the raw material gas can be collected and flow into the reaction region 39 regardless of the type of raw material, for example, the type of group III element raw material and group V constituent element raw material. In the first raw material supply channel 27, for example, the group III element raw materials 10 and 11 and the group V element raw material 51 can be distributed in advance in a lump. Corresponding to the first raw material supply flow path 27, a first exhaust system flow path 29 is provided to exhaust the raw material. The first raw material supply flow path 27 is connected to a second raw material supply flow path 28 for supplying the raw material gases flowing through the first raw material supply flow path 27 to the gas phase reaction region 39 all at once. The first exhaust system flow path 29 is directly connected to the second exhaust system flow path 29a. This piping system is, for example, a gallium arsenide / indium (composition formula Ga) in which a complexing reaction between raw materials is relatively gentle.XIn1-XArsine (molecular formula: AsH) such as As: 0 ≦ X ≦ 1)Three) Is suitable for vapor phase growth of III-V compound semiconductor crystal layers using arsenic (As) sources. In particular, a heterojunction structure having excellent interface sharpness is required.XIn1-XAs: 0 ≦ X ≦ 1) / GaXIn1-XIt is suitable for vapor phase growth of an epitaxial laminated structure for use in an As (0 ≦ X ≦ 1) -based TEGFET.
[0025]
FIG. 5 shows a modification of the piping system illustrated in FIG. 4, and is particularly a piping system suitable for vapor phase growth of a compound semiconductor crystal layer containing a constituent element rich in volatility. For example, in the source gas piping system illustrated in FIG. 5, in addition to the basic piping system of FIG. 4, a highly volatile constituent element source is supplied as the second source supply channel 28 or the second exhaust system channel. A piping system 52 is newly provided for distribution to 29a. Switching between the second raw material supply channel 28 and the second exhaust system channel 29 a is performed by opening and closing valves 53 and 54. For example, after the source gas is circulated through the first source supply channel 27 and the second source supply channel 28 and the vapor phase growth of the first crystal layer is completed, the source gas channel is changed to the first source channel. The second raw material supply flow path 28 is changed to the second exhaust system flow path 29a. Thereafter, the raw material gases necessary for vapor phase growth of the second crystal layer are collected in the first raw material supply channel 27 and circulated. While the raw material gas is circulated through the first raw material supply channel 27 for a while to obtain a steady flow, the gas material of the volatile constituent element is converted into the second raw material using the newly provided piping system 52. The gas is allowed to flow into the vapor phase growth reaction region 39 through the supply channel 28. After observing that the flow of the raw material gas for vapor phase growth of the second crystal layer becomes steady, the gaseous material of the volatile constituent element is supplied from the second raw material supply channel 28 to the second exhaust system flow. Along with switching to the path 29a, a raw material gas for vapor phase growth of the second crystal layer is supplied to the vapor phase reaction region via the first and second raw material supply channels 27 and 28.
[0026]
This suppresses the volatilization of volatile constituent elements from the surface of the first crystal layer after the vapor phase growth of the first crystal layer is completed until the vapor phase growth of the second crystal layer is started. The effect is demonstrated. By this action, the surface state of the first crystal layer is well maintained, and there is an effect that the vapor phase growth of the second crystal layer having an excellent surface state as the upper layer is achieved. Such actions and effects are, for example, gallium nitride and indium (compositional formula Ga) in which volatilization of nitrogen (element symbol: N) occurs remarkably due to vapor phase growth at a high temperature around 1000 ° C.XIn1-XN: 0 ≦ X ≦ 1) It is suitably used for vapor phase growth of a crystal layer.
[0027]
According to the vapor phase growth apparatus and the film forming method using the vapor phase growth apparatus according to the present invention, a semiconductor junction interface having an excellent compositional steepness as described above is provided. In addition, a stacked structure including a semiconductor junction structure bonded with excellent composition steepness exhibits excellent electrical characteristics. For example, a Schottky junction field effect transistor (MESFET) or a heterojunction bipolar. There is an effect that a semiconductor element such as a transistor (HBT) can be configured.
[0028]
For example, as an example of a high-frequency semiconductor element that can operate in a microwave or millimeter-wave band, aluminum gallium arsenide (AlXGa1-XAs: Generally, a spacer layer or an electron supply layer made of 0.2 ≦ X ≦ 0.4) and gallium arsenide / indium (Ga)XIn1-XAs: Generally, there is a strained superlattice TEGFET that includes a heterojunction structure with a channel layer of 0.7 ≦ X ≦ 0.9). When obtaining a stacked structure for pseudomorphic TEGFETs, the aluminum (Al) composition and the indium (In) composition change sharply according to the vapor phase growth apparatus and film forming method of the present invention. Be made. For this reason, AlXGa1-XAs / GaXIn1-XAt the As heterojunction interface, a steep heterojunction interface that does not cause bending of electron beam interference fringes (fringe) can be formed on the CAT image. Improvement of the steepness of the heterojunction interface between the electron supply layer or the spacer layer and the channel layer can promote the localization of low-dimensional electrons in the vicinity of the heterojunction interface and contribute to high electron mobility. .
[0029]
The effect of improving the electron mobility by means of the present invention is also manifested in, for example, a TEGFET stacked structure having a lattice matching heterojunction structure of aluminum gallium arsenide and gallium arsenide. For example, the sheet carrier concentration is about 1.2 × 1012cm-3The electron mobility at 77 Kelvin (K; liquid nitrogen temperature) of the laminated structure is about 70,000 cm in the conventional example.2/ V · s to about 100,000cm2/ V · s, but according to the present invention, about 100,000 cm2Mobility relating to high two-dimensional electrons exceeding / V · is manifested stably. Regardless of the strained superlattice stack or lattice matched stack, a steep structure that can manifest high electron mobility, for example, a stacked structure including a heterojunction interface structure between a spacer layer and a channel layer, for example, has a mutual conductance. (Gm) (refer to Shizujiro Furukawa et al., “Electronic Device Engineering” (October 16, 1995, published by Morikita Publishing Co., Ltd., first edition, eighth edition), pages 75-77) There is an advantage that a low-noise field-effect transistor with a small exponent can be configured.
[0030]
Al having a steep heterojunction interface that is stably achieved by the vapor phase growth apparatus and film forming method of the present inventionXGa1-XAs / GaAs lattice matched stacked system, AlXIn1-XAs / GaXIn1-XAs lattice matching laminated system or AlXGa1-XAs / GaXIn1-XIn particular, a low noise TEGFET having an excellent noise figure (abbreviation: NF) composed of an As-strained superlattice multilayer structure is used as an L band (usually 1.0 to 2.6 GHz band). Low-noise amplifier, 12 GHz (GHz) and 18 GHz band low noise amplifier, 45 GHz band millimeter wave low noise amplifier, 100 GHz band base station communication equipment for millimeter wave transmission (local transmission), etc. Can be used effectively. Also, due to the sharpening of the heterojunction interface achieved in accordance with the present invention, the heterogeneous room temperature is 6,000 cm.2/ V · s, and 30,000cm at liquid nitrogen temperature (77K)2/ V · s and 150,000cm at a temperature of 1.6K2/ Ga containing two-dimensional electron gas that expresses high electron mobility exceeding V · sXIn1-XP / GaXIn1-XLow noise or power consisting of an As-based laminated structure (see The Tenth International Conference on Metallic Vapor Phase Epitaxy (ICMOVPE-X) (June 5-9, 2000), Workbook, We-P20, page 236) The TEGFET can be effectively used to construct, for example, an L-band high-frequency low-noise amplifier or a microwave band and a millimeter-wave band high-frequency transmitter.
[0031]
In addition, from a stacked structure having a steep heterojunction interface formed by using the vapor phase growth apparatus and the film forming method of the present invention and imparted with high electron mobility, for example, high product sensitivity (product- A Hall element that develops sensitivity can be configured. For example, indium phosphide (chemical formula: InP) and gallium arsenide-indium (Ga0.47In0.53In a Hall element having a lattice-matched single heterojunction structure with As) (see J. Elctron. Mater., Vol. 25, No. 3 (1996), pages 407 to 409), the vapor phase growth of the present invention. By using the apparatus and the film forming method, a heterojunction interface in which the gallium (Ga) composition, the arsenic (As) composition, and the phosphorus (P) composition are abruptly changed can be formed.2High electron mobility exceeding / V · s is manifested stably. In particular, compared with the halogen VPE growth method and the MBE growth method, the MOCVD method is suitable for growing a III-V compound semiconductor layer containing phosphorus as a constituent element. According to the MOCVD growth means using the film method, it is advantageous to obtain a heterojunction structure capable of stably manifesting high electron mobility (the 1993 (Heisei 4) 53rd academic conference of the Japan Society of Applied Physics) Proceedings Vol. 1 (Extended Abstracts (The 53rd Automatic Meeting, 1992); The Japan Society of Applied Physics No. 1) (Applied Physics Society, September 16, 1992, E) See page 283). A high electron mobility can be obtained stably, so that the product sensitivity at room temperature is higher than 800V / A · T (volt / ampere tesla).0.47In0.53There is an advantage that an As / InP heterojunction Hall element (see J. Elctron. Mater., Vol. 25, (1996) above) is stably provided.
In addition, the steep heterojunction interface that is stably achieved by the vapor phase growth apparatus and the film forming method of the present invention is effective in promoting the localization of carriers in the vicinity of the junction interface. Play. Hall elements that use the high mobility characteristics of localized electrons (two-dimensional electrons), for example, AlXGa1-XAs / GaAs or GaXIn1-XFrom the two-dimensional electron Hall element composed of an As / InP lattice-matched stacked system, the high sensitivity characteristics of the Hall element as a magnetoelectric conversion element such as a magnetic field strength measuring device, a geomagnetic measuring device, a tachometer, a distance meter, etc. (See IEEE Trans. Electron Dev., ED-41 (3) (1994), p. 315). In particular, a Hall element in which the sharpening of the heterojunction interface is achieved, for example, Ga0.47In0.53The As / InP-based two-dimensional electron Hall element has a large Hall voltage under a unit operating current and a unit magnetic field strength, so-called product sensitivity is 760 V / A · T (the above-mentioned IEEE Trans. Electron). (See Dev., ED-41 (3)) (see (1) J. Elctron. Mater., Vol. 25 (1996), pages 407-409, above) and (2). ▼ Extended Abstracts (see The 53rd Automatic Meeting, 1992), improvement of the measurement sensitivity of the measuring instrument, resulting in the effect of providing a highly sensitive measuring instrument.
[0032]
Further, by using the vapor phase growth apparatus and the film forming method of the present invention, a multi-heterostructure junction structure can be formed with good steepness. For example, with the steepness of a good indium (In) composition, gallium nitride (chemical formula: GaN) and gallium nitride indium (composition formula Ga)XIn1-XSingle or double heterojunction structure with N: 0 <X <1, strained-layer super-lattice structure or single- and multi-quantum well structure formed it can. For example, GaXIn1-XIn a gallium nitride / indium-based light emitting diode (abbreviation: LED) or laser diode (abbreviation: LD) having a light emitting portion having an N / GaN heterojunction structure, the steepness of the heterojunction interface is emitted (emitted light). ) Is an important factor affecting the monochromaticity (see JP-A-10-168241). In the quantum well structure, the steepness of the indium (In) composition at the heterojunction interface between the well layer and the barrier layer is good and the steepness is uniform. And can contribute to excellent monochromatic light emission. According to the vapor phase growth apparatus and the film forming method of the present invention, a single quantum well (English abbreviation: SQW) or multiple quantum well (English abbreviation: MQW) structure is also stable with a good heterojunction interface steepness. Can be formed. Therefore, there is an advantage that a gallium nitride / indium blue LED or a blue LD having excellent monochromaticity of light emission can be configured.
[0033]
【Example】
(Example 1)
Gallium phosphide indium (composition formula Ga0.51In0.49P) / Ga0.80In0.20The present invention will be described in detail by taking as an example a vapor phase growth apparatus for an epitaxial laminated structure for use in an As heterojunction high mobility field effect transistor.
[0034]
An outline of the piping system in the present embodiment is shown in FIG. The piping is configured based on a double vent / run system (Dual Allign Vent-Run system). In the first raw material supply channel 27, trimethylgallium (molecular formula: (CHThree)ThreeGa) and trimethylindium (molecular formula: (CHThree)ThreeIn) is deployed. The group III element sources 10 to 11 are individually provided with pipes for supplying hydrogen gas for transporting the raw material vapor accompanying the raw materials 10 to 11. Hydrogen gas accompanying the vapors of the respective raw materials 10 to 11 is selected and circulated in the first raw material supply flow path 27 or the first exhaust system flow path 29 as necessary. The first exhaust system flow path 29 is connected to the second exhaust system flow path 29 a via a three-way valve 38.
[0035]
In the first raw material supply channel 27, arsine (AsH) serving as an arsenic (As) source 51 in addition to the above group III raw materials.Three). Also, a pipe for supplying arsine is branched in the middle (pipe 52), and a pneumatic operation valve 53 is provided in either the second raw material supply flow path 28 or the second exhaust system flow path 29a. 54 is switched by opening / closing operation. Compressed gas is supplied to the valves 53 and 54 via an electromagnetic valve, and opening and closing of the valve body is operated. The raw material gas circulated in the first raw material supply passage 27 can be circulated by switching the valves 36 and 37 to either the second raw material supply passage 28 or the second exhaust system passage 29a. ing. The second raw material supply channel 28 is directly connected to the vapor phase growth region 39. A detoxification facility 40 for detoxifying the source gas is disposed downstream of the second exhaust system flow path 29a.
[0036]
In order to make the pressure inside the flow path the same on the upstream side of both the first raw material supply flow path 27, the exhaust system flow path 29 and the second raw material supply flow path 28, and the exhaust system flow path 29a. Carrier gas piping and electronic mass flowmeter (abbreviation: MFC) 43, 44, 47, 48 are arranged. In general, the flow rate in the second raw material supply channel 28 through which the raw material gas flows directly into the gas phase reaction region 39 is larger than the flow rate in the first raw material supply channel 27. Further, the pressure difference between the raw material supply channels 27, 28 and the exhaust system channels 29, 29a is eliminated, and the source gas generated due to the pressure difference between the two channels when the gas source channel is changed. In order to suppress the flow rate fluctuation, a differential pressure gauge 55 for measuring the pressure difference between the first raw material supply flow path 27 and the first exhaust system flow path 29 is provided. For the same purpose, a differential pressure gauge 56 is also arranged between the second raw material supply channel 28 and the second exhaust system channel 29a.
[0037]
Using the MOCVD apparatus equipped with the above piping, Ga0.51In0.49P / Ga0.80In0.20The operation means of the piping system will be described in detail by taking as an example the case of vapor phase growth of an epitaxial multilayer structure for use in an As two-dimensional electron field effect transistor. First, in order to make the internal pressures of the first raw material supply channel 27 and the first exhaust system channel 29 substantially the same, the flow rate is controlled to about 3 to 5 liters per minute by the MFCs 43 and 44, and hydrogen gas is supplied. Circulate. Similarly, in order to eliminate the differential pressure between the second raw material supply channel 28 and the second exhaust system channel 29a, each channel was independently controlled to a flow rate of about 5 liters to about 20 liters per minute. Hydrogen gas is circulated in advance. The differential pressure between the raw material supply channels 27, 28 and the exhaust system channels 29, 29a is about 5 × 10 with differential pressure gauges 55, 56.2Pascal (unit Pa), preferably about 2 × 102Suppressed within Pa. Under this condition, arsine is supplied to the surface of the {100} 2 ° off gallium arsenide (GaAs) single crystal substrate 59 placed in the vapor phase growth reaction region 39 in the vapor phase reactor using the pipe 52. The temperature of the GaAs single crystal substrate 59 is heated to an epitaxial growth temperature of about 600 ° C. to about 700 ° C.
[0038]
Next, while the substrate 59 is held at the epitaxial temperature for a while and the temperature of the substrate 59 is stabilized, the high temperature buffer layer 60 made of undoped GaAs is accompanied by hydrogen gas necessary for vapor phase growth. The gallium source (trimethylgallium) to be supplied is circulated through the first exhaust system pipe 29. In addition, an arsenic source (arsine) 51 controlled to a predetermined flow rate by the MFC is circulated through the first exhaust system pipe 29 in advance. In view of the stabilization of the temperature of the substrate 59 and the stabilization of the flow rates of the gallium source and the arsenic source, the three-way valves 33 and 34 provided in the first exhaust system pipe 29 are provided with the flow paths of both source gases. The four-way valves 30 and 31 of the first raw material supply flow path 27 are opened in synchronization with the closed state, and the flow path is changed to the first raw material supply flow path 27. Thus, the gallium source and the arsenic source are circulated through the first reaction channel 27 to the second exhaust system channel 29a. Next, in the raw material gas flow path, the three-way valve 37 attached to the second exhaust system flow path 29a is closed, and at the same time, the four-way valve 36 attached to the second raw material supply flow path 28 is opened, and GaAs The vapor phase growth of the buffer layer 60 is started. The supply of the source gas to the gas phase reaction region is continued until the buffer layer having a predetermined layer thickness is vapor grown. Thereafter, the flow path of the raw material gas is changed from the second raw material supply flow path 28 to the second exhaust system flow path 29a by reversing the open / close state of the valves 36 and 37, and the gas flow of the GaAs buffer layer 60 is changed. End phase growth.
[0039]
Even after the growth of the GaAs buffer layer 60 is completed, in order to prevent arsenic from volatilizing from the surface of the GaAs buffer layer 60, the arsine gas is continuously supplied to the gas phase reaction region via the pipe 52, and the GaAs buffer layer is continuously supplied. The surface state of the layer 60 is kept good. In the meantime, Ga0.80In0.20In order to grow the As electron transit layer (channel layer) 61, the hydrogen gas accompanied by the vapor of trimethylindium previously circulated in the first exhaust system flow path 27 in advance is dedicated to the pipe for the indium source 11. The provided three-way valve 34 is closed, and the four-way valve 31 is opened in synchronism with the first raw material supply flow path 27 to be circulated. In addition, the flow rate of the gallium source gas already circulated through the first source supply channel 27 is adjusted and controlled so that the gallium composition ratio becomes 0.80. The mixed gas of the raw material gas whose flow rate ratio is controlled in advance so as to meet the desired composition ratio is circulated to the second exhaust system flow passage 29a via the first raw material supply flow passage 27. After a certain period of distribution and stable distribution, the three-way valve 37 is closed, and conversely, the four-way valve 36 is opened, and the flow path is switched to the second raw material supply flow path 28. From this, Ga0.80In0.20The vapor phase growth of the As channel layer 61 is started. When the layer thickness of the undoped channel layer 61 reaches about several tens of nanometers (nm), the flow path of the source gas is returned from the second source supply path 28 to the second exhaust system path 29a to form a channel. End the vapor phase growth of the layer. Even after the channel layer 61 is finished, the arsine gas is continuously supplied from the pipe 52 to prevent the surface state of the channel layer 61 from being deteriorated due to volatilization of arsenic.
[0040]
While the arsenic source is circulated using the pipe 52, the flow rate of the gallium source 10 and the indium source 11 flowing through the first raw material supply channel 27 is changed to n-type Ga with a gallium composition ratio of 0.51 by MFC.0.51In0.49Distribution begins with a flow rate that allows growth of the P layer. The mixed source gas is circulated through the first source supply channel 27 to the second exhaust system channel 29a. Next, the supply of the arsenic source (arsine) to the gas phase reaction region 39 through the pipe 52 is stopped. At the same time or after several seconds, phosphine (PH) as a phosphorus (P) source (not shown in FIG. 6) is provided via another pipe 57.Three) Begins to be supplied to the gas phase reaction zone 39. After a lapse of a while until the transient flow rate fluctuation of the desired flow rate of phosphorus source is resolved, the flow path of the raw material gas is switched from the second exhaust system flow path 29a to the second raw material supply flow path 28. N-type Ga0.51In0.49The P layer is vapor-grown as the electron supply layer 62. n-type Ga0.51In0.49In forming the P electron supply layer, a doping source (not shown in FIG. 6) such as silicon (Si) is supplied using a dedicated pipe 58. As for the flow rate of the n-type doping gas, the carrier concentration of the electron supply layer 62 near room temperature is generally about 1 × 10.18cm-3~ About 3 × 1018cm-3Set to be. The source gas channel is changed from the second exhaust channel 29a to the second source supply channel 28, and the electron supply layer 62 having a thickness of about 20 nm to about 30 nm is grown. After the growth is completed, supply of phosphorus source is continued for a while.0.51In0.49The volatilization of phosphorus from the surface of the P electron supply layer 62 is suppressed, and the surface of the layer 62 is favorably retained.
[0041]
n-type Ga0.51In0.49Further, for example, an undoped high resistance Ga is formed on the surface of the P electron supply layer 62.0.51In0.49When vapor-phase-growing a Schottky gate formation layer, an n-type GaAs cap (cap) layer, or the like made of P, the same process is performed based on the flow path changing means. That is, the raw material gas required to obtain a desired crystal layer is once gathered in the first reaction flow path 27 in advance, and then again in the second raw material supply flow path and the exhaust system flow path. As a result of this change, vapor phase growth is achieved by means for supplying the gas phase reaction region all at once. FIG. 7 shows Ga vapor-grown in accordance with the means described in the present invention.0.51In0.49P / Ga0.80In0.20It is a copy of a CAT (contrast anisy by thickness fringe) image showing an example of steepness of the channel layer 61 / electron supply layer 62 heterojunction interface 64 of the laminated structure for use in an As heterojunction TEGFET. As shown in FIG. 7, according to the vapor phase growth apparatus having a double vent / run type piping system according to the present invention, a heterojunction structure having excellent interface steepness can be obtained.
[0042]
Steepened Ga0.51In0.49P / Ga0.80In0.20In the As heterojunction structure, a Shubnikov-De Haas (SdH) oscillation related to the Hall voltage as illustrated in FIG. 8 is observed. Further, in the laminated structure for TEGFET grown by the means described in the present embodiment, for example, a sheet carrier concentration (ns: Unit cm-2) About 1.4 × 1012cm-2About 6,300 (cm2/ V · s) high mobility (μ: cm2/ V · s). In 77 Kelvin (K), ns= 1.4 × 1012cm-2And μ = 31,600cm2A high mobility of / V · s is developed. Furthermore, at a low temperature of 1.6 K, it is about 200,000 cm.2A high electron mobility of / V · s is obtained. Therefore, according to the vapor phase growth apparatus provided with the piping system having the configuration according to the present invention, the heterojunction epitaxial structure which is excellent in the steepness of the junction interface capable of manifesting two-dimensional electrons can be vapor phase grown.
[0043]
(Comparative example)
The MOCVD apparatus provided with the conventional single vent / run type piping system illustrated in FIG.0.51In0.49P / Ga0.80In0.20A laminated structure for an As field effect transistor was formed. FIG. 9 shows a copy of a CAT image of a laminated structure using this conventional flow path changing means.
[0044]
In the present comparative example, in the method in which the raw material gas is circulated by the conventional vent / run method, the gaseous raw materials that are gathered and circulated as in the above-described embodiment cannot be circulated uniformly in the gas phase reaction region. It is necessary to mix the newly required raw material gas into the raw material supply channel each time. For this reason, for example, after vapor phase growth of a GaAs buffer layer, Ga0.80In0.20In order to start the vapor phase growth of the As channel layer, it is necessary to newly mix an indium source into the raw material supply channel. The flow rate of the newly added indium source fluctuates transiently with respect to the gallium source and the arsenic source that have already been in steady flow. An indium source maintained at a predetermined flow rate is distributed in advance to the exhaust system flow path, and when the flow path is instantly switched to the raw material supply flow path, periodic fluctuations in the flow rate due to the flow path change are completely eliminated. It is extremely rare that it can be avoided. Moreover, since the raw material supply channel is directly connected to the vapor phase growth channel, the transient flow rate fluctuation of the indium source causes the flow rate mixing ratio of the indium source and the gallium source to be unstable in the gas phase reaction region. And GaAs buffer layer 60 and Ga in the CAT image of FIG.0.80In0.20The occurrence of a bent portion on the electron beam interference fringe 65 inside the heterojunction interface 63 with the As channel layer 61 on the side of the channel layer 61 changes the mixed crystal composition due to the instability of the mixing ratio of the source gases. It shows that it is coming.
[0045]
Ga0.80In0.20Ga on As channel layer0.51In0.49Even when the P electron supply layer is grown, the same transient fluctuation of the flow rate occurs in the conventional piping system. In this case, Ga having a gallium composition ratio of 0.51.0.51In0.49In order to obtain the P layer, it is necessary to simultaneously distribute the gallium source and the indium source mixed at a predetermined flow rate to the raw material supply channel directly connected to the gas phase reaction region. That is, it is necessary to simultaneously introduce a plurality of constituent element source gases into the source supply channel. If both of the Group III constituent elements are introduced into a single raw material supply channel at the same time, the flow rates of both gaseous raw materials will vary greatly. For this reason, Ga0.80In0.20As channel layer / Ga0.51In0.49The steepness of the composition at the heterojunction interface with the P electron supply layer becomes even worse. In the CAT image of FIG. 9, the steepness of the composition at the heterojunction interface 64 with the channel layer 61 / electron supply layer 62 is worse than at the junction interface 63 between the buffer layer 60 / channel layer 61. It clearly shows that there is.
[0046]
Moreover, Ga lacking such steepness0.80In0.20As / Ga0.51In0.49From the P heterojunction interface structure, for example, as illustrated in FIG. 10, the oscillation of the Hall resistance indicating the existence of two-dimensional electrons in the quantum Hall effect measurement is not clear. For this reason, the room temperature mobility obtained is, for example, ns= 1.4 × 1012cm-2In, about 4,000cm on average2/ V · s about 5,000cm2/ V · s. In other words, the conventional vapor phase growth apparatus having the piping configuration cannot provide a laminated structure excellent in the steepness and mobility characteristics of the heterojunction interface as obtained by the vapor phase growth apparatus according to the present invention. .
[0047]
(Example 2)
Gallium phosphide indium (Ga) obtained using the vapor phase growth apparatus of the present invention0.51In0.49P) / Ga0.80In0.20The present invention will be specifically described with reference to an example in which a high mobility field effect transistor is formed from an As-based heterojunction stacked structure.
[0048]
FIG. 11 schematically shows a cross-sectional structure of a two-dimensional electron field effect transistor (TEGFET) 66 according to this embodiment. In the figure, the same component numbers as those described in the first embodiment are designated by the same reference numerals, and the description thereof is omitted.
[0049]
The laminated structure 67 for TEGFET 66 was constructed according to the method and procedure described in Example 1. In this embodiment, the carrier concentration is 5 × 10.15cm-3And undoped n-type Ga with a layer thickness of 10 nm0.80In0.20The As growth layer was the channel layer 61. Also, the carrier concentration is 5 × 1018cm-3And silicon (Si) doped n-type Ga with a layer thickness of 15 nm0.51In0.49The P growth layer was used as the electron supply layer 62. Furthermore, Ga0.51In0.49On the surface of the P electron supply layer 62, the carrier concentration is 2 × 10.16cm-3And undoped Ga with a layer thickness of 10 nm0.51In0.49A P growth layer was stacked as a gate contact layer 72. On the surface of the layer 72, the carrier concentration is 3 × 10.18cm-3Then, an Si-doped GaAs growth layer having a layer thickness of 40 nm was stacked as the ohmic contact layer 68.
[0050]
In particular, Ga0.80In0.20As channel layer 61 and Ga0.51In0.49In order to ensure that the heterojunction interface with the P electron supply layer 62 is sharp, the differential pressure between the source supply channels 27 and 29 is increased after the growth of the channel layer 61 and before the growth of the electron supply layer 62 is started. The same measures were taken again (see Fig. 6). Specifically, the differential pressure measured by the differential pressure gauge 55 between the first raw material supply channel 27 and the first exhaust system channel 29 is 1 × 10.2Pa. Further, the differential pressure measured by the differential pressure gauge 56 between the second source gas flow path 28 and the second exhaust system flow path 29a is also 1 × 10.2Pa. The internal pressures of the first exhaust system flow path 29 and the second exhaust system flow path 29a are the same when the three-way opening / closing valve 38 is opened and both the flow paths 29, 29a are conducted. As a result, the differential pressures of the first and second raw material supply channels 27, 28 with respect to the exhaust system flow channels 29, 29a having the same internal pressure are set to be the same as described above, whereby both the raw material supply channels 27 , 28 were kept the same.
[0051]
Ga0.51In0.49In the growth of the P electron supply layer 62, the mixing ratio of the gallium source 10 and the indium source 11 flowing in the first raw material supply channel 27 is such that the indium composition ratio is 0.49.0.51In0.49Waited until a constant mixing ratio sufficient to result in a P-grown layer was reached. The mixing ratio was stabilized with the disappearance of fluctuations in the flow rates of the gallium source 10 and the indium source 11 that could be measured by the flow meters 16 and 17, respectively. Specifically, after the flow of both raw materials 10 and 11 is continued for 5 seconds until the flow rates of the gallium source 10 and the indium source 11 into the first raw material supply channel 27 become stable, the three-way valve 37 is closed, and at the same time, the four-way valve 36 is opened, and the flow path of the raw material gas that has been sufficiently mixed in the first raw material supply flow path 27 from the second exhaust system flow path 29a to the second Switch to the raw material supply channel 28 and switch to Ga0.51In0.49The growth of the P electron supply layer 62 was started.
[0052]
After the formation of the multilayer structure 67 was completed, measurement was performed by a normal Hall effect method. Mobility at room temperature is 6,300cm2/ V · s (sheet carrier concentration = 1.3 × 1012cm-2) Mobility at liquid nitrogen temperature (77K) is 35,000cm2/ V · s was high. According to the CAT method, Ga0.80In0.20As channel layer 61 / Ga0.51In0.49The interference fringes at the heterojunction interface with the P electron supply layer 62 showed no slow bending, indicating that a steep junction interface sufficient to give high two-dimensional electron mobility was formed. .
[0053]
A source electrode 69 and a drain electrode 70 are formed on the ohmic contact layer 68 which is the outermost layer using a general process technology means such as well-known vacuum deposition and photolithography (photoetching). Formed. Both ohmic electrodes 69 and 70 are composed of a three-layer structure of gold / germanium (Au · Ge) / nickel (Ni) / gold (Au) whose upper surface is a gold (Au) layer. The planar shapes of the source and drain electrodes 69 and 70 are all rectangular with a length of 130 μm and a width of 450 μm. Next, a selective patterning technique based on a well-known photolithography technique and a wet process are used to form a GaAs contact layer 68 in a region over a length of about 5 μm for forming a gate electrode 71 between the source electrode 69 and the drain electrode 70. It removed selectively using the etching means. Thereafter, Ga exposed in the region where the GaAs contact layer 68 is removed.0.51In0.49The surface layer portion of the P gate contact layer 72 was removed by using a hydrochloric acid (chemical formula: HCl) aqueous solution of about 2 nm to form a recess structure. Subsequently, the gate electrode 71 was selectively patterned using a well-known electron beam photolithography technique. Next, titanium (element symbol: Ti), molybdenum (element symbol: Mo), and gold (Au) were sequentially deposited from the side in contact with the gate contact layer 72 using an electron beam deposition means or the like. Thereafter, a Schottky gate electrode 71 having a Ti / Mo / Au three-layer structure having a gate length of about 0.25 μm was formed by using a known lift-off technique.
[0054]
A drain voltage (abbreviation: V) between the source / drain electrodes 69 and 70 is 2V.ds) When the saturation drain current (abbreviation: I) of the TEGFET 66 is applied.dss) Was about 70 milliamperes (mA), and the gate pinch-off voltage was about -0.8V. The mutual conductance (gm) Is about 250 mS / mm (milli Siemens / millimeter) reflecting the high electron mobility, and for example, GaInP-based having a suitable performance as a low noise field effect transistor operated from the L band to the millimeter wave band. A TEGFET was provided.
[0055]
(Example 3)
Aluminum arsenide / indium (compositional formula Al0.48In0.52As) / Ga0.47In0.53The present invention will be described in detail by taking as an example a vapor phase growth apparatus for an epitaxial laminated structure for use in an As lattice matching high mobility field effect transistor.
[0056]
The atmospheric pressure (substantially atmospheric pressure) MOVPE apparatus shown in FIG. 12 equipped with the same piping system as in Example 1 (see FIG. 6) was used for Al.0.48In0.52As / Ga0.47In0.53An As heterojunction laminated structure 73 was formed. FIG. 13 schematically shows a cross-sectional structure of the laminated structure 73.
[0057]
The piping system was composed of a dual vent / run system according to the present invention. The gallium (Ga) source 10 includes trimethylgallium ((CHThree)ThreeGa) and indium (In) source 11 includes cyclopentadienyl indium having a valence of 1 (molecular formula: CFiveHFiveIn) (1) Japanese Patent No. 2098388 (Japanese Patent Publication No. 8-17160) and (2) J. Crystal Growth, 107 (1991), pages 360 to 364) were used. The aluminum (Al) source 12 includes trimethylaluminum ((CHThree)ThreeAl) was used. The group III element sources 10 to 12 are individually provided with pipes for supplying hydrogen gas for transporting the vapors of those raw materials accompanying the respective raw materials 10 to 12 (not shown in FIG. 12). ). The hydrogen gas accompanying the vapors of the respective raw materials 10 to 12 was selected and circulated in either the first raw material supply flow path 27 or the first exhaust system flow path 29 as necessary. The first exhaust system flow path 29 is opened to the second exhaust system flow path 29a by opening the three-way valve 38.
[0058]
Arsine (AsH) serving as an arsenic (As) source 51 is provided in either the first raw material supply flow path 27 or the first exhaust system flow path 29.Three) Can be introduced by opening and closing the valves 32 and 35. Further, a piping system 52 is branched from the middle of the piping for supplying the arsine 51, and the second raw material supply channel 28 or the second exhaust is separately provided by opening / closing the pneumatic operation valves 53 and 54. It was set as the structure which can distribute | circulate any of the system flow paths 29a. The group III and group V source gas channels mixed in advance in the first source supply channel 27 are switched to the second source supply channel 28 or the second exhaust system by switching valves 36 and 37. It was set as the structure switched to either of the flow paths 29a. The second raw material supply channel 28 was directly connected to a vapor phase growth region 39 in which normal pressure (substantially atmospheric pressure) MOVPE growth was performed. A detoxification facility 40 for detoxifying the raw material gas is disposed downstream of the second exhaust system flow path 29a.
[0059]
A differential pressure gauge 55 for measuring a pressure difference (differential pressure) was provided between the first raw material supply channel 27 and the first exhaust system channel 29. Further, a differential pressure gauge 56 is also disposed between the second raw material supply channel 28 and the second exhaust system channel 29a. On the upstream side of both the first vent / run pipes 27 and 29 and the second vent / run pipes 28 and 29a, the flow rate of the carrier gas flowing in order to eliminate the differential pressure between the flow paths is set. Electronic mass flow meters (English abbreviation: MFC) 43, 44, 47, and 48 for adjustment were arranged. The internal pressure of the first raw material supply channel 27 and the first exhaust system channel 29 is set to 2 × 10.2In order to achieve Pa or less, hydrogen gas of about 3 to 5 liters per minute was passed through the flow meters (MFC) 43 and 44. The differential pressure between the second raw material supply channel 28 and the second exhaust system channel 29a is 2 × 10.2In order to make it Pa or less, hydrogen gas of about 5 liters to about 8 liters per minute was circulated in advance for each channel.
[0060]
Next, a piping system 57 is used on the surface of a semi-insulating indium phosphide (InP) single crystal substrate 74 placed in the vapor phase growth reaction region 39 and having a plane orientation of {100} 2 ° off. The InP substrate 74 was heated to an epitaxial growth temperature of 640 ° C. while supplying phosphine at a flow rate of 50 cc / min.
[0061]
While the temperature of the substrate 74 is stabilized, the flow rate of the indium source 11 accompanying the hydrogen gas is adjusted with a flow meter 17 in preparation for the growth of the high-resistance buffer layer 75 made of undoped indium phosphide (InP). The flow rate was controlled in advance to 60 cc / min, and was circulated through the first exhaust system flow path 29 in advance. The indium source 11 was circulated to the second exhaust system flow passage 29 a via the first raw material supply flow passage 27.
[0062]
After the temperature of the substrate 74 was stabilized, the flow rate of the phosphine gas flowing through the piping system 57 was increased to 250 cc / min.
[0063]
Next, the flow path of hydrogen gas accompanied by the indium source 11 is closed in the three-way valve 34 provided in the first exhaust system pipe 29, and the four directions of the first raw material supply flow path 27 are synchronized therewith. The valve 31 was opened, and the flow path was changed to the first raw material supply flow path 27. After changing the flow path and waiting for 3 seconds, the raw material gas flow path is closed with the three-way valve 37 attached to the second exhaust system flow path 29a and at the same time attached to the second raw material supply flow path 28. Then, the four-way valve 36 was opened, and the growth of the InP buffer layer 75 was started. The indium source 11 and phosphine were continuously supplied to the gas phase reaction region 39 until the vapor phase growth of the InP buffer layer 75 having a thickness of about 10 nm was completed. Thereafter, the InP buffer layer 75 is grown by changing the flow path of the indium source 11 from the second raw material supply flow path 28 to the second exhaust system flow path 29a by reversing the open / close state of the valves 36 and 37. Ended.
[0064]
Even after the growth of the InP buffer layer 75 is completed, the phosphine gas is continuously supplied to the gas phase reaction region 39 through the piping system 57, and the surface of the buffer layer 75 due to the volatilization of phosphorus (P) from the surface. The deterioration of the state was suppressed.
[0065]
Next, Ga0.47In0.53In order to grow the As electron traveling layer (channel layer) 76, the hydrogen gas accompanied by the vapor of trimethylgallium, which has been steadily circulated through the first exhaust system flow path 29 in advance, is connected to the piping system 13 for the gallium source 10. The three-way valve 33 provided exclusively for is closed and synchronized, and the four-way valve 30 is opened and circulated through the first raw material supply channel 27. In addition, the supply flow rate of the indium source 11 already circulated through the first raw material supply flow path 27 is set to Ga with an indium composition ratio of 0.53.0.47In0.53It adjusted so that an As layer might be obtained. Further, the arsine 51 controlled to a flow rate of 250 cc / min by a flow meter (not shown in FIG. 12) was circulated through the first raw material supply channel 27. The group III element and arsenic source gases mixed in advance were circulated through the first source supply channel 27 to the second exhaust system channel 29a.
[0066]
The flow path of phosphine 57 was switched from the first raw material supply flow path 28 to the second exhaust system flow path 29a. At the same time, the flow path of the arsine 51 having a flow rate of 50 cc / min that had been circulated through the second exhaust system flow path 29 a was switched to the second raw material supply flow path 28 in advance using the piping system 52.
[0067]
The above-mentioned group III element and arsenic source gas mixed in advance is circulated through the second exhaust system flow passage 29a for 5 seconds to obtain a steady flow, and then the three-way valve 37 is closed and conversely The four-way valve 36 was opened, and the flow path was switched to the second raw material supply flow path 28. From this, Ga0.47In0.53The vapor phase growth of the As channel layer 76 was started. When the layer thickness of the undoped channel layer 76 reaches 400 nm, the flow path of the raw material gas is returned from the second raw material supply flow path 28 to the second exhaust system flow path 29a, and the gas phase of the channel layer 76 is returned. Finished growth.
[0068]
Even after the completion of the channel layer 76, the supply of the arsine gas 51 to the vapor phase growth region 39 was continued using the piping system 52 to prevent the surface state of the channel layer 76 from being deteriorated due to volatilization of arsenic.
[0069]
Next, the valve A2 is closed in the hydrogen gas flow path accompanying the vapor of the aluminum source 12 that has been circulated through the first exhaust system flow path 29, and the valve A1 is opened, and the first raw material is supplied. The channel 27 was changed. After that, n-type aluminum arsenide / indium mixed crystal (composition formula Al0.48In0.52In preparation for the growth of the spacer layer 77 made of As) and the electron supply layer 78, the supply flow rates of the indium source 11 and the aluminum source 12 accompanying the hydrogen gas are set so as to obtain the above mixed crystal ratio. The total was adjusted by 17 and A18, and was circulated through the first raw material supply channel 27. The flow rate of the arsine 51 flowing through the first raw material supply channel 27 was 200 cc / min. Until the growth of the spacer layer 77 was started, the raw material gas mixed in advance was passed through the second exhaust system flow passage 29a.
[0070]
Further, a disilane-hydrogen mixed gas (Si) used as the silicon doping source 58 is used.2H610 vol ppm-hydrogen mixed gas) was allowed to flow through the second exhaust system flow passage 29a.
[0071]
After changing the pre-mixed source gas flow path to the second exhaust system flow path 29a and waiting for 3 seconds, the three-way valve 37 attached to the second exhaust system flow path 29a is closed, and the second Open the four-way valve 36 attached to the raw material supply flow path 28 of the undoped Al0.48In0.52The growth of the spacer layer 77 made of As was started.
[0072]
Undoped Al0.48In0.52When the layer thickness of the As layer 77 reached 4 nm, the flow path of the disilane gas 58 was changed from the second exhaust system flow path 29 a to the first raw material supply flow path 28. In addition to the group III and arsenic sources described above, with the supply of disilane gas to the nitride semiconductor vapor phase growth region 39, Si doped n-type Al0.48In0.52The growth of the As layer 78 was started. From this, the carrier concentration is 2 × 10.18cm-3Si-doped n-type Al0.48In0.52An electron supply layer 78 made of an As layer was grown. The group III and group V source gases and the doping source 58 were continuously supplied to the gas phase reaction region 39 until the growth of the electron supply layer 78 with a layer thickness of 10 nm was completed. Thereafter, the flow path of the raw material gas is changed from the second raw material supply flow path 28 to the second exhaust system flow path 29a by reversing the open / close state of the valves 36 and 37, and Al0.48In0.52The growth of the As electron supply layer 78 was completed. The disilane flow path was changed from the second raw material supply flow path 28 to the second exhaust system flow path 29a.
[0073]
Thereafter, the arsine gas 51 was supplied to the vapor phase growth region 39 using the piping system 52, and the temperature of the InP substrate 74 was lowered while suppressing volatilization of arsenic (As) from the surface of the electron supply layer 78.
[0074]
The mobility at room temperature of the laminated structure 73 measured by the usual Hall effect method is 9,200 cm.2/ V · s. Sheet carrier concentration at room temperature (ns) Is 7.4 × 1011cm-2Met. The mobility at liquid nitrogen temperature (77K) is 64,000cm.2The sheet carrier concentration is 7.9 × 10 at / V · s.11cm-2Met.
[0075]
Further, the second-order differential value (d) of the magnetic resistance (R) measured at a temperature of 4.2K.2R / dB2) For the reciprocal (1 / B) of the magnetic field strength (B) is illustrated in FIG. As shown in FIG. 14, a large amplitude magnetoresistive Shubnikov de Haas (SdH) oscillation is observed reflecting the manifestation of high electron mobility. According to the present invention, 2 Ga with steepness sufficient to localize dimensional electrons0.47In0.53As channel layer 76 / Al0.48In0.52It was shown that a heterojunction interface with the As spacer layer 77 is formed. D above2R / dB2The sheet carrier concentration calculated using the peak position of the value is 7.6 × 1011cm-2Thus, the sheet carrier concentration at the above liquid nitrogen temperature was in good agreement.
[0076]
FIG. 15 shows the correlation between the filling factor (i) and the reciprocal (1 / B) of the magnetic field strength (B: unit Tesla (T)). Filling factor is the cyclotron radiuscNs・ 2π ・ lc 2Given in. Ga formed by a vapor phase growth apparatus provided with the piping system of the present invention.0.47In0.53As / Al0.48In0.52In the laminated structure 73 for As-based TEGFET use, a relationship of 1 / B (unit: 1 / T) = 0.032 · i was obtained.
[0077]
FIG. 16 shows the Hall voltage (RH) Shows the magnetic field strength dependence. Unlike the case of the AlGaAs / GaAs TEGFET heterojunction structure, which is considered to be due to one type of electronic system, the aspect of SdH vibration was judged to be caused by a more complicated two-dimensional electronic system.
[0078]
(Example 4)
In this example, gallium arsenide indium (composition formula Ga0.47In0.53The present invention will be described by taking as an example the case of obtaining a high-product-sensitivity Hall element from a laminated structure having an As) / indium phosphide (InP) heterojunction structure.
[0079]
In this example, since the heterojunction structure is formed using the raw materials that are likely to cause the complexing reaction, the multiple vents shown in FIG. 17 can be supplied individually, and the group III constituent element raw materials and the group V constituent element raw materials can be supplied. A vapor phase growth apparatus equipped with a / Vent (Multi Vent-Run) piping system was used. Since the vapor phase growth apparatus used in the present embodiment is similar to that illustrated in FIG. 3, the same components as those shown in FIG. 3 are denoted by the same reference numerals. The piping system 49 is a piping system for supplying Group III constituent element materials. The source gas flow path 13-1 is trimethylgallium ((CHThree)ThreeIt is a piping system for supplying Ga). The source gas channel 14-1 is trimethylindium ((CHThree)ThreeIt is a piping system for supplying In). The raw material gas flow paths 13-1 and 14-1 are compressed air operated valves 30-1 and 33 in either the first raw material supply flow path 27-1 or the first exhaust system flow path 29-1. -1 and valves 31-1, 34-1 can be switched by opening and closing operations. Furthermore, the raw material gas premixed and circulated in the first raw material supply channel 27-1 is supplied to the valve 36 in either the second raw material supply channel 28-1 or the second exhaust system channel 29a. -1, 37-1 can be distributed. The second raw material supply channel 27-1 is not directly connected to the second raw material supply channel 27-2 for the Group V raw material and is directly connected to the vapor phase growth region 39 separately. The first exhaust system flow path 29-1 in the piping system 49 for the group III raw material supply application is joined to the second exhaust system flow path 29 a that bypasses the raw material supply area 39 and leads to the detoxification facility 40. It is as composition to do. The piping system 49 for Group III raw material supply uses the pressure inside the first raw material supply flow path 27-1 and the first exhaust system flow path 29-1 (first vent / run piping system) flow path. Electronic mass flow meters (English abbreviation: MFC) 43-1 and 44-1 for controlling the flow rate of the carrier gas to be the same are arranged.
[0080]
Further, in the vapor phase growth apparatus of the present embodiment, the piping system 50 for supplying the Group V constituent element material is provided separately from the above-described Group III material piping system 49. The source gas channel 13-2 is an arsine (AsH) source which is an arsenic (As) source 51-1.Three). The source gas flow path 14-2 is a phosphine (PH) used as a phosphorus (P) source 51-2.Three). The source gas channels 13-2 and 14-2 used for supplying the arsine and phosphine source gases are either the first source supply channel 27-2 or the first exhaust system channel 29-2. It was set as the structure switched by opening / closing operation of the pneumatic operation type | formula four-way valve 30-2, 31-2 and three-way valve 33-2, 34-2 to a flow path. The raw material gas premixed and circulated in the first raw material supply channel 27-2 is a valve 36-2 in either the second raw material supply channel 28-2 or the second exhaust system channel 29a. , 37-2 can be distributed by switching. The second raw material supply channel 28-2 was directly connected to the vapor phase growth region 39. In addition, the pressure inside the flow path is set on the upstream side of both the first raw material supply flow path 27-2 and the second exhaust system flow path 29-2 (second vent / run piping system). Electronic mass flow meters (English abbreviation: MFC) 43-2 and 44-2 for controlling the flow rate of the carrier gas to be the same are arranged.
[0081]
Using the MOCVD apparatus provided with the above-mentioned piping, the specific resistance doped with iron (element symbol: Fe) is 3 × 106An undoped n-type InP layer was grown on a semi-insulating (100) -indium phosphide (InP) single crystal substrate 79 of Ω · cm. In the growth of the InP layer, first, the Group III and Group V material supply piping systems 49, 50, the first material supply channel systems 27-1, -2 and the first exhaust system channel system 29- are used. In order to make the internal pressures of 1 and -2 substantially equal, hydrogen gas whose flow rate was controlled by MFCs 43-1, 43-2, 44-1, and 44-2 was circulated. Similarly, in order to eliminate the differential pressure between the second raw material supply flow path system 28 and the second exhaust system flow path system 29a, the flow rate was controlled by the flow meters 47-1, 47-2, and 48 for each flow path. Hydrogen gas was circulated in advance. Thus, the differential pressures between the first raw material supply flow path systems 27-1 and 27-2 and the first exhaust system flow paths 29-1 and 29-2 are respectively measured by differential pressure gauges 55-1 and 55-2. About 5 × 102Suppressed within Pa. Thus, the internal pressures of the first raw material supply channels 27-1 and 27-2 and the first exhaust system channels 29-1 and 29-2 were made substantially equal. The first and second exhaust system flow paths 29-1, 29-2, 29a are made conductive by opening the on-off valves 38-1, 38-2, and the first and second exhaust system flow paths 29-1. 29-2, 29a, and the internal pressures were made equal. Therefore, the first and second raw material supply channels 27-1, 27-2, 28 are made equal by equalizing the differential pressure with respect to the first or second exhaust system channels 29-1, 29-2, 29a. The internal pressure of was made equivalent.
[0082]
Under the above setting conditions, the phosphine (PH) of the phosphorus (P) source 51-2 controlled to a flow rate of 40 cc / min by the flow meter 17-2.Three10% by volume-H290 volume% mixed gas) is circulated to the first raw material supply flow path 27-2 through the gas raw material flow path 14-2 with the valve 31-2 open and 34-2 closed. It was made to merge with hydrogen of carrier gas controlled to a flow rate of 5 liters per minute by a total of 43-2. The hydrogen carrier gas containing phosphine is a gas phase reactor in which the valve 36-2 is opened and the valve 37-2 is closed, and is maintained at substantially atmospheric pressure via the second raw material supply channel 28-2. It was made to distribute | circulate to the inside vapor phase growth reaction area | region 39. FIG. While continuing the supply of hydrogen gas containing phosphine to the surface of the InP single crystal substrate 79 placed in the vapor phase growth reaction region 39, the temperature of the InP substrate 79 was heated to 610 ° C.
[0083]
While the temperature of the InP single crystal substrate 79 is stabilized, the vapor of the indium source 11 accompanies the vapor phase growth of the buffer layer 80 made of undoped n-type InP in the piping system 49 for supplying the group III material. Hydrogen gas is circulated through the first raw material supply channel 27-1 with the valve 31-1 opened and the valve 34-1 closed. In this example, the flow rate of hydrogen gas accompanying the vapor of the indium source 11 held at a constant temperature of 40 ° C. was 70 cc / min. The hydrogen gas accompanying the vapor of the indium source 11 flowing in the first raw material supply flow path 27-1 together with the hydrogen carrier gas controlled to a flow rate of 1 liter per minute by the flow meter 43-1 is supplied from the valve 36-1. Was closed, and the valve 37-1 was opened and discharged to the second exhaust system flow passage 29a.
[0084]
Thereafter, in the piping system 50 for supplying the Group V raw material, the flow rate of the phosphine circulated through the second raw material supply channel 27-2 as described above is set to 320 cc / min by the flow meter 17-2. Increased the amount.
[0085]
After confirming that the flow rate of the hydrogen gas accompanying the indium source 11 is stable, the valve 37-1 is closed, the valve 36-1 is opened in synchronism with it, and the flow path of the source gas is set to the second state. The exhaust system flow path 29a was changed to the second raw material supply flow path 28-1. Thus, the supply of the source gas to the gas phase reaction region 39 was continued until the vapor phase growth of the InP buffer layer 80 having a layer thickness of 15 nm was completed. Thereafter, the opening and closing states of the valves 36-1 and 37-1 are reversed in the flow path for allowing the Group III source gas to flow, and the second raw material supply flow path 28-1 to the second exhaust system flow path 29a. Thus, the vapor phase growth of the InP buffer layer 80 was completed.
[0086]
Even after the growth of the InP buffer layer 80 is completed, in order to prevent the volatilization of phosphorus from the surface of the InP buffer layer 80, the phosphine gas 51-2 undergoes a gas phase reaction via the second raw material supply channel 28-2. Feeding to area 39 continued.
[0087]
Meanwhile, undoped n-type Ga0.47In0.53In preparation for the growth of the As layer 81, the hydrogen gas accompanying the vapor of the gallium source 10 previously steadily circulated in the first exhaust system flow path 29-1 in the piping system 49 for supplying the Group III raw material is used. The valve 33-1 provided exclusively for the raw material gas flow path 13-1 of the gallium source 10 is closed, and the valve 30-1 is opened in synchronization to be circulated through the first raw material supply flow path 27-1. . From this, it is preliminarily mixed with the vapor of the indium source 11 already circulated through the first raw material supply channel 27-1, the valve 36-1 is closed, and the valve 37-1 is kept open. The mixed gas was discharged to the second exhaust system flow path 29a through the first raw material supply flow path 27-1.
[0088]
On the other hand, in the group V raw material supply piping system 50, the flow path of the phosphine 51-2 circulated by the raw material gas flow path 14-2 is closed with the valve 31-2 related to the flow path 14-2. On the contrary, the valve 34-2 was opened, and the first raw material supply flow path 27-2 was switched to the first exhaust system flow path 29-2. That is, the supply of phosphine 51-2 to the vapor phase growth region 39 through the first and second raw material supply channels 27-2 and 28-2 was stopped. Alternatively, arsine (AsH) as the arsenic source 51-1 controlled to a flow rate of 280 cc / min with a flow meter 16-2 provided in the source gas flow path 13-2.Three10% by volume−90% by volume of hydrogen) was switched to the first raw material supply channel 27-2 by opening the valve 30-2 and closing the valve 33-2.
[0089]
Immediately after that, in the group III element source supply system 49, the channel of the mixed gas of the gallium source 10 and the indium source 11 previously mixed and circulated in the first source supply channel 27-1 is connected to the valve. 36-1 was opened, and the valve 37-1 was closed, and the second exhaust system flow path 29a was changed to the second raw material supply flow path 27-1. Thus, the undoped n-type Ga having a layer thickness of about 300 nm is supplied by supplying the Group III element materials 10 and 11 to the gas phase reaction region 39.0.47In0.53The growth of the As layer 81 was started. The flow path of the Group III element raw materials 10 and 11 is returned from the second raw material supply flow path 28-1 to the second exhaust system flow path 29a again.0.47In0.53The growth of the As layer 81 was terminated.
[0090]
Thereafter, the temperature of the substrate 79 was lowered. Arsine (AsHThree) 51-1 continues to flow into the vapor phase growth region 39 until the temperature of the substrate 72 is lowered to about 450 ° C., and Ga due to volatilization of arsenic (As).0.47In0.53Degradation of the surface state of the As layer 81 was prevented.
[0091]
An undoped InP layer 80 formed on the semi-insulating InP substrate 79 by the above means and an undoped GaP0.47In0.53In the laminated structure having a single heterojunction with the As layer 81, the sheet carrier concentration measured by the usual Hall effect method is 7.1 × 10.11cm-2And the sheet resistance was 767 Ω / □. The room temperature mobility is 11,500 cm.2/ V · s was high.
[0092]
Further, the InP / Ga formed on the semi-insulating InP substrate 72 by the same means as described above by the vapor phase growth apparatus of this example shown in FIG.0.47In0.53The relationship between the room temperature mobility and carrier concentration of the laminated structure provided with the single heterojunction with As is shown. According to the present invention, 1 × 1016cm-3~ 4x1016cm-3In the range of carrier concentration of 9,000 cm2It has been shown that a heterojunction structure that exhibits a high electron mobility exceeding / V · s is stably obtained.
[0093]
(Example 5)
In accordance with the means described in Example 3 above, an undoped InP layer 80 and an undoped GaP on a semi-insulating InP substrate 79.0.47In0.53A laminated structure 82 having a single heterojunction with the As layer 81 was formed.
[0094]
Carrier concentration is 8.1 × 1016cm-311,300cm at room temperature2Using the stacked structure 82 exhibiting high mobility of / V · s, InP / Ga0.47In0.53An As heterojunction Hall element 83 was formed. A schematic cross-sectional view of the formed Hall element 83 is shown in FIG. The hole element 83 includes an undoped InP layer 80 and Ga.0.47In0.53A magnetically sensitive part obtained by processing As81 into a mesa type by wet etching was used (see Japanese Patent Laid-Open No. 7-99349). The ohmic electrodes 84 for operating power supply input and Hall voltage output were both made of a gold (element symbol: Au) -germanium (element symbol: Ge) alloy.
[0095]
The input resistance of the Hall element 83 was 1400Ω, and the product sensitivity was 880 V / A · T. This product sensitivity is the result of conventional InP / Ga with an input resistance of less than 2.5 kΩ.0.47In0.53The product sensitivity (= 760 V / A · T) of the As heterojunction hole element (see IEEE Trans. Electron Dev., ED-41 (3) above) was higher than about 15%.
[0096]
(Example 6)
InP / Ga having various carrier concentrations and mobility formed in accordance with the growth means described in Example 30.47In0.53The As laminated structure was processed in the same manner as in Example 4 (see Japanese Patent Laid-Open No. 6-268277) to form a heterojunction Hall element 83.
[0097]
A measuring element (probe) for use in measuring magnetic field strength was constructed using the Hall element 83 that exhibited various input resistances because of different carrier concentrations and mobility. FIG. 19 is a schematic plan view of the magnetic field strength measurement probe 84.
[0098]
FIG. 20 shows the correlation between the input resistance of the probe and the product sensitivity. For comparison, the sensitivity of a probe using a conventional GaAs Hall element in which the magnetosensitive part is GaAs (for example, Sencors and Actuators A, 32 (1992), pages 651 to 655) is also shown. To illustrate.
[0099]
It has been clarified that the probe 84 using the heterojunction Hall element 83 according to the present invention has higher sensitivity than the probe using the conventional GaAs Hall element regardless of the input resistance. Therefore, according to the present invention, even if the input resistance is the same as 500Ω, for example, a probe for measuring the magnetic field strength can be provided that is about 2.5 times as high as the conventional GaAs Hall element.
[0100]
(Example 7)
A short wavelength visible light emitting diode (LED) is formed from a laminated structure having a light emitting portion of a gallium nitride / indium (GaInN) / GaN double heterojunction structure obtained by using the vapor phase growth apparatus of the present invention. The present invention will be described specifically with reference to cases.
[0101]
FIG. 21 schematically shows a cross-sectional structure of the GaInN-based LED 85 according to this example.
[0102]
The laminated structure 86 for use in the LED 85 was formed using the vapor phase growth apparatus shown in FIG. 22 of a double vent / run (Double Vent-Run) system. The vapor phase growth apparatus used in this example is added to the piping system shown in FIG. 17 with a piping system capable of supplying a volatile group V constituent element source as shown in FIG. The configuration was as follows.
[0103]
The nitrogen (element symbol: N) source 51-1 includes ammonia (molecular formula: NHThree)It was used. In the middle of the raw material gas flow path 13-2 through which the ammonia gas is circulated, the second raw material supply flow path 28-2 or the second exhaust system flow path 29a is supplied with the ammonia gas at any time via the flow meter 16-2. A piping system 52 is provided to select and distribute any of the above. Further, in the piping system 50 for supplying the group V constituent element source, a disilane-hydrogen mixed gas (Si) is provided as a doping gas of silicon (element symbol: Si) in the raw material gas flow path 14-2.2H65 vol ppm) 51-3 was attached.
[0104]
The piping system 49 for supplying the raw material of the group III constituent element has trimethylgallium ((CH) as the gallium (Ga) source 10.Three)ThreeGa) is used as an indium (In) source 11 for trimethylindium ((CHThree)ThreeIn) were each used. The group III element sources 10 and 11 are accompanied by hydrogen gas, and the raw material supply flow channels 27-1 and 28-1 or the exhaust system flow channel 29-1 through the raw material gas flow channels 13-1 and 14-1. It was set as the structure which can distribute | circulate to any of 29a.
[0105]
Before growing the low temperature buffer layer 88, the flow rate of the ammonia gas 51 flowing in the raw material gas flow path 13-2 is adjusted to 0.5 liters per minute by the flow meter 16-2, and the first raw material supply flow It was supplied to the vapor phase growth region 39 on which the sapphire substrate 81 was placed through the path 27-2 and the second raw material supply flow path 28-2. In addition, the ammonia gas 51 adjusted to a flow rate of 0.5 liters per minute by the flow meter 16-3 was circulated through the piping system 52 and the first raw material supply channel 28-2. Hydrogen gas adjusted to a flow rate of 5 liters per minute by the flow meter 47-2 was circulated through the second raw material supply channel 28-2. Further, in the second exhaust system flow path 29a, the differential pressure with respect to the second raw material supply flow path 28-2 measured by the differential pressure gauge 56 is 2 × 10.2Hydrogen gas whose flow rate was adjusted by a flow meter 48 was circulated so as to be equal to or lower than Pa. The temperature of the sapphire substrate 87 was raised to 420 ° C. while hydrogen gas and ammonia gas were circulated.
[0106]
After assuming that the temperature of the substrate 87 is stabilized in the range of ± 1 ° C., a flow path of hydrogen gas containing the vapor of trimethyl gallium 10 previously circulated through the first exhaust system flow path 29-1 at a predetermined flow rate. Was switched from the first exhaust system flow path 29-1 to the first raw material supply flow path 27-1 by opening and closing the valves 30-1 and 33-1. Subsequently, by opening and closing the valves 36-1 and 37-1, the flow path of the hydrogen gas containing the vapor of the gallium source 10 is changed from the second exhaust system flow path 29a to the second raw material supply flow path 28-1. And switched. As a result, the supply of the gallium source 10 and the ammonia gas 51-1 to the vapor phase growth region 39 was continued for 8 minutes to grow an undoped GaN low-temperature buffer layer 88 having a layer thickness of 17 nm. The growth of the low-temperature buffer layer 88 having the crystal structure described in the inventor's invention (see Japanese Patent No. 3031255) is performed by changing the gas flow path containing the gallium source 10 to the second raw material supply flow path 28-. Conversion from 1 to the second exhaust system flow path 29a was completed.
[0107]
The flow of ammonia gas to the first raw material supply channel 27-2 was temporarily stopped by closing the four-way valve 30-2 and closing the three-way valve 33-2. On the other hand, the ammonia gas 51-1 continued to flow through the piping system 52 to the vapor phase growth region 39. With the vapor phase growth region 39 in an atmosphere containing ammonia, the temperature of the substrate 87 was raised from 420 ° C. to 1080 ° C. in about 1 minute.
[0108]
While the temperature of the substrate 87 reaches 1080 ° C., the flow rate of the ammonia gas 51-1 flowing through the flow path 13-2 is adjusted to 8 liters per minute by the flow meter 16-2, and the second exhaust system flow It was allowed to flow into the passage 29a.
[0109]
Further, while the temperature of the substrate 87 is stabilized in the range of 1080 ° C. ± 2 ° C., the flow rate of hydrogen gas for accompanying the gallium source 10 held at a constant temperature of 0 ° C. is increased to 20 cc / min, The first exhaust gas flow channel 29a was preliminarily circulated through one raw material supply flow channel 27-1.
[0110]
Further, disilane gas whose flow rate is adjusted to 10 cc per minute by the flow meter 17-2 flows into the first raw material supply flow channel 27-2 from the doping gas source 51-3 via the raw material gas flow channel 14-2. did.
[0111]
The flow path of hydrogen gas containing ammonia and disilane was changed from the second exhaust system flow path 29a to the second raw material supply flow path 28-2. About 8 × 10ThreeIn the vapor phase growth region 89 depressurized to Pa, ammonia gas (flow rate 8 l / min.), Disilane gas (10 cc / min.), And hydrogen gas (flow rate 5 l / min) are passed through the second raw material supply channel 28-2. .)), The hydrogen gas flow path containing the gallium source 10 is changed from the second exhaust system flow path 29a to the second raw material flow path 28-1. On the low-temperature buffer layer 88, a lower cladding layer 83 made of n-type GaN doped with Si was deposited. The carrier concentration of the lower cladding layer 89 is 3.2 × 1018cm-3The layer thickness was about 3.0 μm. The growth of the GaN lower cladding layer 89 was completed by changing the flow path of the source gas containing the gallium source 10 from the second raw material supply flow path 28-1 to the second exhaust system flow path 29a.
[0112]
At the same time, ammonia gas (flow rate 8 l / min.) 51-1, disilane gas (10 cc / min.) 51-3 and hydrogen gas (flow rate 5 l / min) that were circulated through the second raw material supply channel 28-2. .) Is switched from the second raw material supply flow path 28-2 to the second exhaust system flow path 29a. Next, the flow path of the disilane gas was changed from the first raw material supply flow path 27-2 to the first exhaust system flow path 29-2.
[0113]
On the other hand, the ammonia gas 51-1 was continuously circulated through the piping system 52 to the vapor phase growth region 39 to suppress the evaporation of nitrogen (N) from the GaN layer 89 when the growth was interrupted. At the same time, the temperature of the sapphire substrate 87 was lowered from 1080 ° C. to 890 ° C. in about 1 minute.
[0114]
While lowering the temperature of the substrate 87, the first raw material supply is made to the hydrogen gas flow path accompanied by the vapor of the indium source 11 that has been circulated in the first exhaust system flow path 29-1 in advance at a predetermined flow rate. It changed into the flow path 27-1. Thus, in the first raw material supply channel 27-1, gallium nitride indium having an average indium (In) composition ratio of 0.12 (composition formula Ga)0.88In0.12In order to obtain N), the gallium source 10 and the indium source 11 were mixed and circulated in advance. The hydrogen gas accompanying the vapor of the indium source 11 is passed through the second exhaust system flow passage 29a until 5 seconds have passed after the first gas supply flow passage 27-1 is merged, and the mixing ratio is stabilized. A steady flow was assumed.
[0115]
Further, the ammonia gas 51-1 is switched from the first exhaust system flow channel 29-2 to the first raw material supply flow channel 27-2 and the flow rate is adjusted to 8 liters / minute. 1 was again supplied to the vapor phase growth region 39 from the second raw material supply channel 28-2. The premixed Group III source gas channel is changed from the second exhaust system channel 29a to the second source supply channel 28-1, and Ga0.88In0.12The growth of the N light emitting layer 90 was started. Ga0.88In0.12The crystal structure of the N light emitting layer 90 is a multiphase structure composed of a plurality of phases having different indium composition ratios disclosed in the inventors' invention (1) British Patent GB2316226B No. (2) U.S. Pat. No. 5,886,367 and (3) Taiwan (Taiwan) Patent No. 099672). Ga with a layer thickness of 10 nm0.88In0.12The growth of the N light emitting layer 90 was terminated by stopping the supply of the mixed gas of the gallium source 10 and the indium source 11 to the vapor phase growth region 39.
[0116]
The ammonia gas 51-1 continues to flow from the first raw material supply channel 27-2 and the piping system 52 to the vapor phase growth region 39 via the second raw material supply channel 28-2, and has a multiphase structure. Ga0.88In0.12Loss of the light emitting layer 90 due to N sublimation was prevented. In this state, the temperature of the sapphire substrate 87 was raised from 890 ° C. to 1050 ° C.
[0117]
During the temperature increase, the hydrogen gas accompanying the vapor of the indium source 11 is discharged from the closed valve 31-1 to the first exhaust system flow path 29-1 with the valve 34-1 closed and opened. It was. At the same time, the flow rate of the hydrogen gas containing the vapor of the gallium source 10 was changed and started to flow from the first raw material supply flow path 27-1 to the second exhaust system flow path 29a. Further, biscyclopenta as a p-type dopant previously discharged through the first exhaust system flow path 29-1 and the second exhaust system flow path 29a using the source gas flow path 15-1. Dienylindium (bis- (CFiveHFive)2The gas flow path of hydrogen gas accompanied by Mg) 12 ′ is closed by closing the three-way valve 35-1, and the four-way valve 32-1 is opened, from the first exhaust system flow path 29-1 to the first source gas flow path. Switched to 27-1.
[0118]
Next, the flow path of the mixed gas of the gallium source 10 and the magnesium (element symbol: Mg) source 12 ′ previously mixed and circulated through the first source gas flow path 27-1 The exhaust system flow path 29a was converted into the second raw material supply flow path 28-1. Thus, the gallium source 10 and the magnesium source 12 ′ are supplied to the vapor phase growth region 39 to which the ammonia gas 51-1 has already been supplied via the second source gas channel 28-2, and the Mg-doped p The growth of the GaN layer 91 started. Continue to circulate the source gas for a predetermined time, and set the carrier concentration to 3 × 1017cm-3A p-type GaN layer 91 having a layer thickness of 10 nm was grown. The growth of the p-type GaN layer 91 was completed by switching the flow path of the gallium source 10 and the magnesium source 12 'from the second raw material supply flow path 28-1 to the second exhaust system flow path 29a.
[0119]
One minute after the completion of the growth, the flow path of the ammonia gas 51-1 that was circulated through the second raw material supply flow path 28-2 was changed to the second exhaust system flow path 29a. To the vapor phase growth region 39, the temperature of the sapphire substrate 87 was lowered from 1050 ° C. to 950 ° C. at a rate of 50 ° C. per minute while continuing to supply the ammonia gas 51-1 through the piping system 52. Subsequently, the temperature was lowered to 650 ° C. at a rate of 15 ° C. per minute. When the temperature of the substrate 87 became less than 650 ° C., the valve 36-2 was closed, the valve 37-2 was opened, and the supply of the ammonia gas 51-1 through the piping system 52 was stopped. Thereafter, the laminated structure 86 formed by natural cooling was cooled to room temperature.
[0120]
The light emitting portion 86a having a double heterojunction structure of the laminated structure 86 includes a lower clad layer 89 made of the Si-doped n-type GaN layer, a multiphase Ga related to indium composition0.88In0.12The light emitting layer 90 made of N and the upper cladding layer 91 made of an Mg-doped p-type GaN layer were used. According to general secondary ion mass spectrometry (abbreviation: SIMS), the transition distance of the indium atom concentration from the junction interface between the light emitting layer 90 and the upper cladding layer 91 to the inside of the upper cladding layer 91 (special No. 11-168241) is about 10 nm, which sufficiently satisfies the composition steepness required to bring about high-intensity short-wavelength light emission disclosed by the present inventor (see the above-mentioned Japanese Patent Application Laid-Open No. 11-168241). No. 168241).
[0121]
Further, the matrix phase that mainly constitutes the light emitting layer 90 having a multiphase structure is composed of substantially GaN because of its small indium composition ratio. Therefore, the light emitting layer 90 and the lower cladding layer 89 are separated from each other. Thus, a heterojunction structure satisfying the band discontinuity or junction mode on the conduction band side disclosed by the present inventor in order to bring about high-intensity light emission was obtained (see Japanese Patent No. 2992933).
[0122]
A general plasma etching process was applied to a partial region of the laminated structure 86 to remove the upper cladding layer 91 and the light emitting layer 90 in a region where the n-type ohmic electrode 92 is to be formed. A p-type ohmic electrode 93 was formed on the surface of the upper cladding layer 91 to form an LED 85 (see Japanese Patent Application Laid-Open No. 10-107315).
[0123]
The LED 85 emitted blue light having a wavelength of about 460 nm when a forward current of 20 mA was passed. The forward voltage was 3.8 V when the forward current was 20 mA. FIG. 23 shows an emission spectrum. Reflecting the steepness of the junction interface between the light emitting layer 90 and the upper clad layer 91, the half width (FWHM) of the emission spectrum was as excellent as 10 nm. The light emission luminance in the state where the chip of the LED 85 was sealed with a general epoxy resin for sealing a semiconductor element was about 1.2 candela (cd). According to the present invention, a GaInN-based light emitting device having a narrow emission spectrum half width, that is, excellent monochromaticity of light emission and high emission intensity is provided.
[0124]
【The invention's effect】
According to the vapor phase growth apparatus provided with the raw material supply flow path of the configuration of the present invention, a raw material gas having a small mixing ratio can be introduced into the vapor phase growth region, so that the semiconductor junction interface having excellent compositional steepness Can bring.
[0125]
In particular, according to the vapor phase growth apparatus provided with a mechanism for flowing the carrier gas into the exhaust system flow path, and further provided with a differential pressure gauge between the exhaust system flow path and the raw material supply flow path, the raw material supply flow path Since the pressure difference between the flow paths to the growth region can be reduced, fluctuations in the flow rate of the source gas when switching the flow paths can be reduced, and a steep semiconductor junction interface can be stably formed.
[0126]
Further, according to the vapor phase growth apparatus having two or more mechanisms for switching the raw material gas flow channel to the raw material supply flow channel and the exhaust system flow channel directly connected to the vapor phase growth region, a complex reaction with high association reactivity is achieved. Even when the raw material species are combined, it is possible to form a semiconductor junction interface having excellent composition stability and steepness.
[0127]
In particular, in a vapor deposition apparatus equipped with a plurality of raw material supply piping systems, if a hydride of a group V or group VI element having a low boiling point is used as a raw material gas, the V Condensation in the piping system can be avoided even when a group III or group VI source is arranged, so that a III-V compound semiconductor mixed crystal having a stable composition and excellent steepness can be formed. Further, since condensation can be avoided, a constituent element source rich in volatility can be stably supplied to the vapor phase growth region, which is effective in obtaining a growth layer having an excellent surface state.
[0128]
According to the vapor deposition apparatus of the present invention, it is possible to form with a steep heterojunction interface and to provide a laminated structure that exhibits high electron mobility. For example, GaInP / GaInAs 2 There is an effect that a three-dimensional electron field effect transistor can be obtained. In addition, the InP / GaInAs heterojunction multilayer structure that provides high electron mobility has the effect of providing a highly sensitive heterojunction Hall element with high product sensitivity. Furthermore, if the InP / GaInAs Hall element with high product sensitivity according to the present invention is used, a highly sensitive measuring element (probe) for determining the magnetic field strength can be configured.
[0129]
Further, if a laminated structure including a steep bonding interface formed by the growth method of the present invention is used, there is an effect that a light emitting element having excellent monochromaticity of light emission can be obtained. For example, there is an effect that a GaInN-based short wavelength visible LED having an emission spectrum banded can be configured.
[Brief description of the drawings]
FIG. 1 shows a schematic configuration diagram of a conventional single vent / run type piping system. Valves 19 and 22, 20 and 23, and 21 and 24 are not opened simultaneously.
FIG. 2 is a schematic configuration diagram of a piping system according to the present invention.
FIG. 3 is a schematic configuration diagram of another piping system according to the present invention.
FIG. 4 is a schematic configuration diagram of another piping system according to the present invention.
FIG. 5 is a schematic diagram showing a modification of the piping system shown in FIG. 4;
FIG. 6 is a schematic view of a vapor phase growth apparatus provided with the piping system described in the examples.
FIG. 7 is a CAT image of a laminated structure grown by the means described in Examples.
FIG. 8 is a diagram showing the magnetic field strength dependence of the Hall resistance of the laminated structure grown by the means described in the comparative example.
FIG. 9 is a CAT image of a laminated structure grown by the means described in the comparative example.
FIG. 10 is a diagram showing the magnetic field strength dependence of the Hall resistance of the laminated structure grown by the means described in the comparative example.
FIG. 11 is a schematic cross-sectional view of a two-dimensional electron field effect transistor (TEGFET).
12 is a schematic view showing a piping system of the vapor phase growth apparatus described in Example 3. FIG.
13 is a schematic cross-sectional view of an AlInAs / GaInAs laminated structure described in Example 3. FIG.
FIG. 14 is a diagram showing the magnetic field strength dependence of magnetoresistance (second-order differential value).
FIG. 15 is a diagram showing a correlation between a filling factor and an inverse value of magnetic field strength.
FIG. 16 is a diagram showing the magnetic field strength dependence of the Hall voltage.
17 is a schematic view showing a piping system of a vapor phase growth apparatus described in Example 4. FIG.
FIG. 18 is a schematic cross-sectional view of an InP / GaInAs heterojunction Hall element.
FIG. 19 is a schematic plan view of a Hall element probe for measuring magnetic field strength.
FIG. 20 is a diagram showing a correlation between input resistance of a Hall element probe and product sensitivity. The letter GaInAs indicates a probe having an InP / GaInAs Hall element according to the present invention, and the letter GaAs indicates a conventional GaAs Hall element probe.
FIG. 21 is a schematic sectional view of a GaInN-based LED.
22 is a schematic view showing a piping system of the vapor phase growth apparatus described in Example 7. FIG.
23 is a graph showing an emission spectrum of the GaInN-based LED described in Example 7. FIG.
[Explanation of symbols]
10 Group III constituent element sources
11 Group III constituent element sources
12 Group III source
Organometallic source for 12 'doping
13 Raw material gas flow path
13-1 Raw material gas flow path
13-2 Raw material gas flow path
14 Raw material gas flow path
14-1 Raw material gas flow path
14-2 Raw material gas flow path
15 Raw material gas flow path
16 Flow meter
16-1 Flow meter
16-2 Flow meter
17 Flow meter
17-1 Flow meter
17-2 Flow meter
18 Flow meter
19 Two-way valve
20 2-way valve
21 Two-way valve
22 Two-way valve
23 2-way valve
24 2-way valve
25 Raw material supply (run) flow path
26 Exhaust system (vent) flow path
27 First raw material supply channel
27-1 First raw material supply channel
27-2 First raw material supply channel
28 Second raw material supply channel
28-1 Second raw material supply channel
28-2 Second raw material supply channel
29 First exhaust system flow path
29-1 First exhaust system flow path
29-2 First exhaust system flow path
29a Second exhaust system flow path
30 valves
30-1 Valve
30-2 Valve
31 Valve
31-1 Valve
31-2 Valve
32 valves
32-1 Valve
33 Valve
33-1 Valve
33-2 Valve
34 Valve
34-1 Valve
34-2 Valve
35 valves
35-1 Valve
36 Valve
36-1 Valve
36-2 Valve
37 Valve
37-1 Valve
37-2 Valve
38 Valve for connecting the first and second exhaust system flow paths
39 Gas phase reaction zone
40 Exhaust treatment equipment
41 Pipe for carrier gas upstream of first raw material supply channel
42 Pipe for carrier gas upstream of first exhaust system flow path
43 Flowmeter for the first raw material supply channel
43-1 Flowmeter for First Material Supply Channel
43-2 Flowmeter for first raw material supply channel
44 First exhaust system flow meter
44-1 Flowmeter for the first exhaust system flow path
44-2 Flowmeter for the first exhaust system flow path
45 Pipe for carrier gas upstream of second raw material supply channel
46 Pipe for carrier gas upstream of second exhaust system flow path
47 Flowmeter for second raw material supply channel
47-1 Flowmeter for Second Material Supply Channel
47-2 Flowmeter for Second Material Supply Flow Channel
48 Second exhaust system flow meter
49 Group III constituent element source supply piping system
50 Piping system for group V element source supply
51 Group V constituent element sources
51-1 Group V element source
51-2 Group V element source
51-3 Doping Source
52 Piping for supplying volatile constituent elements
53 Valve attached to piping for supplying volatile constituent elements
54 Valve attached to piping for supplying volatile constituent elements
55 Differential pressure gauge
55-1 Differential pressure gauge
55-2 Differential pressure gauge
56 Differential pressure gauge
57 Group V element source piping
58 Doping source supply piping
59 GaAs single crystal substrate
60 GaAs buffer layer
61 GaInAs channel layer
62 GaInP electron supply layer
63 Buffer layer / channel heterojunction interface
64 channel layer / electron transit layer heterojunction interface
65 Electron interference fringes
66 Two-dimensional electron field effect transistor (TEGFET)
67 TEGFET laminated structure
68 Ohmic contact layer
69 Source electrode
70 Drain electrode
71 Gate electrode
72 Gate contact layer
73 AlInAs / GaInAs heterojunction laminated structure
74 InP single crystal substrate
75 High resistance InP buffer layer
76 GaInAs electron transit layer
77 AlInAs Spacer Layer
78 AlInAs electron supply layer
79 InP single crystal substrate
A1 4-way valve for aluminum source flow path
A2 3-way valve for aluminum source flow path
A18 Flow meter for aluminum source
80 n-type InP buffer layer
81 Ga0.47In0.53As layer
82 InP / GaInAs laminated structure
83 InP / GaInAs heterojunction Hall element
83a Ohmic electrode
84 InP / GaInAs heterojunction Hall element probe
85 GaInN LED
87 Sapphire substrate
88 Buffer layer
89 n-type GaN lower cladding layer
90 GaInN light emitting layer
91 p-type GaN layer upper cladding layer

Claims (13)

基板材料上に半導体の結晶層を積層した積層構造体を形成するための気相成長装置において、
１種または複数の気相成長原料を予め搬送用気体と混合させて流通させるための第１の原料供給流路と、
気相成長原料を、第１の原料供給流路に流通させずに個別に排気するための第１の排気系流路と、
第１の原料供給流路に流通させる混合された気相成長原料を、気相成長装置内の気相成長反応領域に導入するための第２の原料供給流路と、
第１の原料供給流路に流通させる混合された気相成長原料を気相成長反応領域を迂回して排気するための迂回排気流路と、
第１の排気系流路と迂回排気流路に流通する気体を排気する第２の排気系流路と、
第１の原料供給流路に流通される混合された気相成長原料を、第２の原料供給流路、または迂回排気流路を介した第２の排気系流路の何れかに切り替えて流通させるための流路切替機構と、
第２の原料供給流路および第２の排気系流路の内部圧力を均等とするために、第２の原料供給流路または第２の排気系流路に、第１の原料供給流路または第１の排気系流路を介さずに搬送用気体を流入する機構が備えられていることを特徴とする気相成長装置。In a vapor phase growth apparatus for forming a laminated structure in which a semiconductor crystal layer is laminated on a substrate material,
A first raw material supply channel for allowing one or a plurality of vapor phase growth raw materials to be mixed and distributed in advance with a carrier gas;
A first exhaust system flow path for individually evacuating the vapor phase growth raw material without flowing through the first raw material supply flow path;
A second raw material supply channel for introducing the mixed vapor phase growth raw material to be circulated through the first raw material supply channel into the vapor phase growth reaction region in the vapor phase growth apparatus ;
A detour exhaust flow path for exhausting the mixed vapor phase growth raw material flowing through the first raw material supply flow path, bypassing the vapor phase growth reaction region;
A second exhaust system flow path for exhausting gas flowing through the first exhaust system flow path and the bypass exhaust flow path;
The mixed vapor phase growth raw material distributed in the first raw material supply flow channel is switched to either the second raw material supply flow channel or the second exhaust system flow channel via the bypass exhaust flow channel. A flow path switching mechanism for
In order to equalize the internal pressures of the second raw material supply flow path and the second exhaust system flow path, the first raw material supply flow path or the second exhaust system flow path is connected to the first raw material supply flow path or the second exhaust system flow path. A vapor phase growth apparatus comprising a mechanism for introducing a transfer gas without passing through a first exhaust system flow path . 第２の排気系流路が、第１の排気系流路および迂回排気流路を一括して排気する流路であることを特徴とする請求項１に記載の気相成長装置。 Second exhaust-side passage is, vapor deposition apparatus according to claim 1, characterized in that collectively the first exhaust-side passage and bypass exhaust path is a flow path for exhausting. 流路切換機構が、第１の原料供給流路を４方バルブを用いて第２の原料供給流路に接続し、かつ第１の原料供給流路の４方バルブを経た流路を３方バルブを介して第２の排気系流路に接続した構造であることを特徴とする請求項１または２に記載の気相成長装置。  The flow path switching mechanism connects the first raw material supply flow path to the second raw material supply flow path using a four-way valve, and the first flow path through the four-way valve of the first raw material supply flow path is three-way The vapor phase growth apparatus according to claim 1 or 2, wherein the vapor phase growth apparatus has a structure connected to the second exhaust system flow path via a valve. 第１の排気系流路および第２の排気系流路の内部圧力を等価とするために、排気系流路に搬送用気体を流入できる機構を有することを特徴とする請求項１〜３の何れか１項に記載の気相成長装置。  4. The apparatus according to claim 1, further comprising a mechanism that allows a carrier gas to flow into the exhaust system flow path in order to equalize the internal pressures of the first exhaust system flow path and the second exhaust system flow path. The vapor phase growth apparatus of any one. 第１の原料供給流路または第２の原料供給流路と、排気系流路との間の差圧を測定する装置が備えられていることを特徴とする請求項１〜４の何れか１項に記載の気相成長装置。A first raw material supply flow path or the second raw material supply passage, claim 1-4, characterized in that differential pressure measuring device is provided between the exhaust-side passage 1 The vapor phase growth apparatus according to item. 第１の原料供給流路を２系列以上有し、各々の第１の原料供給流路は、その流路を第２の原料供給流路または排気系流路に切り換えるための流路切換機構を有することを特徴とする請求項１〜５の何れか１項に記載の気相成長装置。There are two or more first raw material supply flow paths, and each first raw material supply flow path has a flow path switching mechanism for switching the flow path to the second raw material supply flow path or the exhaust system flow path. vapor deposition apparatus according to any one of claim 1 to 5, characterized in that it has. ＩＩＩ族構成元素原料及びＶ族構成元素原料を供給する第１の原料供給流路を、それぞれ別の系列とすることを特徴とする請求項６に記載の気相成長装置。The vapor phase growth apparatus according to claim 6 , wherein the first raw material supply flow paths for supplying the group III constituent element raw material and the group V constituent element raw material are different from each other. ＩＩＩ族構成元素原料及びＶ族構成元素原料を供給する原料供給流路を、気相成長領域に至るまで、それぞれ別の流路とすることを特徴とする請求項６または７に記載の気相成長装置。The vapor phase according to claim 6 or 7 , wherein the raw material supply flow path for supplying the group III constituent element raw material and the group V constituent element raw material is a separate flow path until reaching the vapor phase growth region. Growth equipment. 原料が、結晶層を構成する元素またはドーピングする元素を含むことを特徴とする請求項１〜８の何れか１項に記載の気相成長装置。The vapor phase growth apparatus according to any one of claims 1 to 8 , wherein the raw material contains an element constituting the crystal layer or an element to be doped. 気相成長原料に、第Ｖ族または第ＶＩ族元素の水素化物を含むことを特徴とする請求項１〜９の何れか１項に記載の気相成長装置。The vapor phase growth apparatus according to any one of claims 1 to 9 , wherein the vapor phase growth material contains a hydride of a group V or group VI element. 第１の原料供給流路内で予め混合された気相成長原料の混合比率を一定とした後、該気相成長原料の流路を、排気系流路から第２の原料供給流路に切り換えることを特徴とする請求項１〜１０の何れか１項に記載の気相成長装置を用いた積層構造体の気相成長方法。After the mixing ratio of the vapor phase growth raw material previously mixed in the first raw material supply flow path is made constant, the flow path of the vapor growth raw material is switched from the exhaust system flow path to the second raw material supply flow path. A vapor phase growth method of a laminated structure using the vapor phase growth apparatus according to any one of claims 1 to 10 . 第１の原料供給流路内で予め混合された気相成長原料の流路を排気系流路より第２の原料供給流路に切り換えるに際し、第１の原料供給流路と第２の原料供給流路との間の差圧を５×１０２パスカル（Ｐａ）以下の状態として切り換えることを特徴とする請求項１〜１０の何れか１項に記載の気相成長装置を用いた積層構造体の気相成長方法。When switching the flow path of the vapor phase growth raw material premixed in the first raw material supply flow path from the exhaust system flow path to the second raw material supply flow path, the first raw material supply flow path and the second raw material supply flow The laminated structure using the vapor phase growth apparatus according to any one of claims 1 to 10 , wherein the differential pressure between the flow paths is switched to a state of 5 x 10 2 Pascal (Pa) or less. Vapor phase growth method. 有機金属熱分解気相成長方法に依り、積層構造体を形成することを特徴とする請求項１１または１２に記載の気相成長方法。13. The vapor phase growth method according to claim 11 or 12 , wherein a laminated structure is formed according to a metal organic pyrolysis vapor phase growth method.
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