【０００１】[0001]
【発明の属する技術分野】本発明は、特にＧａＮ系結晶
の成長に用いるのに適した結晶基板、および、基体上に
ＧａＮ系結晶膜を製造する方法に関する。The present invention relates to a crystal substrate particularly suitable for use in growing a GaN-based crystal, and a method for producing a GaN-based crystal film on a substrate.
【０００２】[0002]
【従来の技術】ＧａＮ系化合物は、様々な電子デバイス
に適用されている半導体材料であるが、バルク単結晶を
得ることが困難なため、従前より、異種材料基板上への
エピタキシャル成長により製造されていた。しかしなが
ら、このようにして得られたエピタキシャル成長結晶膜
は、１０9〜１０10ｃｍ-2程度もの欠陥密度を持つもの
であり、必ずしも十分な結晶品質が得られるわけではな
かった。よって、電子デバイスの高性能化のために、高
晶質のＧａＮ単結晶基板を工業的に得ることが切望され
ていた。2. Description of the Related Art A GaN-based compound is a semiconductor material applied to various electronic devices. However, since it is difficult to obtain a bulk single crystal, it has been conventionally manufactured by epitaxial growth on a substrate of a different material. Was. However, the epitaxially grown crystal film thus obtained has a defect density of about 109 to 1010 cm−2 , and does not necessarily provide sufficient crystal quality. Therefore, it has been desired to industrially obtain a high-crystalline GaN single-crystal substrate for improving the performance of electronic devices.
【０００３】図７は、このような目的で開発された、第
５８回応用物理学会学術講演会講演予稿集２ｐ−Ｑ−１
４，Ｎｏ．１（１９９７）ｐ．２６５に報告された、第
１の従来例である。図７を参照すると、基体７０は、サ
ファイア基板７１と、サファイア基板７１の上に形成さ
れたＳｉＯ2膜パターン７２とを有する。Ｓｉ０2膜パタ
ーン７２には開口部７３が設けられている。基体７０上
の全面には、ＭＯＶＰＥ法で形成されたＧａＮ結晶７４
が形成されている。第１の従来例においては、開口部７
３から結晶成長が開始されるようなＳｉＯ2膜パターン
による成長制御を用いたことにより、ＳｉＯ2上のＧａ
Ｎ結晶７５において、欠陥密度１０5〜１０6ｃｍ-2が得
られた。これは、従前得られていた結晶よりも、欠陥密
度が４桁程度低減した結晶である。FIG. 7 is a summary of the proceedings of the 58th Annual Meeting of the Japan Society of Applied Physics, 2p-Q-1 developed for this purpose.
4, No. 1 (1997) p. 265 is a first conventional example. Referring to FIG. 7, a base 70 has a sapphire substrate 71 and a SiO2 film pattern 72 formed on the sapphire substrate 71. An opening 73 is provided in the SiO2 film pattern 72. A GaN crystal 74 formed by the MOVPE method is formed on the entire surface of the base 70.
Are formed. In the first conventional example, the opening 7
By using the growth control by the SiO2 film pattern such that the crystal growth starts from Step 3, Ga on the SiO2
In the N crystal 75, a defect density of 105 to 106 cm−2 was obtained. This is a crystal in which the defect density is reduced by about four orders of magnitude as compared with a conventionally obtained crystal.
【０００４】また、図８は、第５８回応用物理学会学術
講演会講演予稿集２ｐ−Ｑ−１５，Ｎｏ．１（１９９
７）ｐ．２６６に報告された、同様の目的で開発された
第２の従来例である。図８を参照すると、基体８０は、
サファイア基板８１と、ＭＯＣＶＤ法で形成されたＧａ
Ｎ単結晶膜８２と、ＳｉＯ2膜パターン８３とを有す
る。ＳｉＯ2膜パターンには開口部８４が設けられてい
る。基体８０上の全面には、Ｈｙｄｒｉｄｅ−ＶＰＥ法
で形成されたＧａＮ結晶８５が形成されている。第２の
従来例もまた、Ｈｙｄｒｉｄｅ−ＶＰＥ法でＧａＮ結晶
８５を形成する際に、ＳｉＯ2パターンによる成長制御
を用いられており、その結果、Ｈｙｄｒｉｄｅ−ＶＰＥ
法で形成されたＧａＮ結晶８５の表面付近において、欠
陥密度６×１０7ｃｍ-2が得られた。これは、従前得ら
れていた結晶よりも、欠陥密度が３桁程度低減した結晶
である。FIG. 8 is a summary of the 58th Japan Society of Applied Physics Academic Lectures 2p-Q-15, No. 1 (199
7) p. 266 is a second prior art example developed for a similar purpose. Referring to FIG. 8, the base 80 is
Sapphire substrate 81 and Ga formed by MOCVD
It has an N single crystal film 82 and a SiO2 film pattern 83. An opening 84 is provided in the SiO2 film pattern. A GaN crystal 85 formed by the hydride-VPE method is formed on the entire surface of the base 80. Also in the second conventional example, when the GaN crystal 85 is formed by the hydride-VPE method, the growth control by the SiO2 pattern is used. As a result, the hydride-VPE
Near the surface of the GaN crystal 85 formed by the method, a defect density of 6 × 107 cm−2 was obtained. This is a crystal in which the defect density is reduced by about three orders of magnitude as compared with a conventionally obtained crystal.
【０００５】このような、従来例に示されたＧａＮ単結
晶膜をＧａＮ系半導体デバイスの成長用基板として使用
すれば、電子デバイスが高性能化されることが期待され
ていた。When such a GaN single crystal film shown in the conventional example is used as a substrate for growing a GaN-based semiconductor device, it has been expected that the performance of an electronic device will be improved.
【０００６】[0006]
【発明が解決しようとする課題】しかしながら、上述の
従来例によって得られたＧａＮ単結晶基板の品質は、今
だ十分なものではなかった。例えば、半導体レーザデバ
イスでは、発光領域付近に欠陥が存在しなければ、製品
寿命に革新的な向上がもたらされるが、そのためには、
欠陥密度１０-5ｃｍ-2未満が要求される。この意味にお
いて、上述の従来の技術による結晶欠陥の低減は不十分
であった。望ましくは、ＧａＡｓ等の、他のＩＩＩ−Ｖ
族半導体基板と同様の、欠陥密度１０-4ｃｍ-2未満が求
められている。However, the quality of the GaN single-crystal substrate obtained by the above-mentioned conventional example has not been sufficient yet. For example, in semiconductor laser devices, the absence of defects near the light-emitting area can lead to innovative improvements in product life,
A defect density of less than 10−5 cm−2 is required. In this sense, the reduction of crystal defects according to the above-described conventional technique is insufficient. Preferably, another III-V such as GaAs.
A defect density of less than 10−4 cm−2 , which is similar to that of a group III semiconductor substrate, is required.
【０００７】第１の従来例においては、欠陥密度の低減
された高品質結晶は、ＳｉＯ2膜パターン上に限られ、
その他の領域は従前同様の結晶品質であったので、結晶
成長用基板としては、使いにくいものであった。In the first conventional example, a high quality crystal having a reduced defect density is limited on the SiO2 film pattern.
Since the other regions had the same crystal quality as before, they were difficult to use as substrates for crystal growth.
【０００８】第２の従来例においては、Ｈｙｄｒｉｄｅ
−ＶＰＥ法により、エピタキシャル成長結晶膜としては
比較的厚い、数１０μｍの膜が形成された。その結果、
その表面付近ではＳｉＯ2パターンの影響が緩和されて
欠陥が均一に分布するので、第１の従来例のような問題
が無いが、欠陥密度の点からは、第１の従来例に劣って
いた。In the second conventional example, a hybrid
By the -VPE method, a relatively thick film of several tens of μm was formed as an epitaxially grown crystal film. as a result,
In the vicinity of the surface, the influence of the SiO2 pattern is alleviated and the defects are uniformly distributed, so there is no problem as in the first conventional example, but the defect density is inferior to the first conventional example. .
【０００９】本発明は、このような従来の問題点を解消
することを目的とする。An object of the present invention is to solve such a conventional problem.
【００１０】[0010]
【課題を解決するための手段】本発明は、基体上に、複
数の、昇華再結晶法により形成された島状のＧａＮ系結
晶と、その上に形成されたＧａＮ系結晶連続膜とを有す
る、結晶基板を提供する。According to the present invention, there are provided, on a substrate, a plurality of island-shaped GaN-based crystals formed by a sublimation recrystallization method and a GaN-based crystal continuous film formed thereon. Provide a crystal substrate.
【００１１】本発明はまた、アンモニアを含む雰囲気中
で、Ｇａを含む原料を昇華させて、複数の開口部を有す
るＧａＮ結晶の成長を抑制する膜が表面に設けられた基
体上の、該開口部に、ＧａＮ系化合物を選択的に結晶化
させることにより、基体上に、複数の島状のＧａＮ系結
晶を得る第１の結晶成長工程と、該基体上に、該複数の
島状のＧａＮ系結晶を成長核として、ＧａＮ系結晶を形
成することにより、ＧａＮ系結晶の連続膜を得る第２の
結晶成長工程とを含むことを特徴とする、ＧａＮ系結晶
膜の製造方法を提供する。The present invention also provides a method for sublimating a Ga-containing material in an atmosphere containing ammonia to suppress the growth of a GaN crystal having a plurality of openings. A first crystal growth step of selectively crystallizing a GaN-based compound in a portion to obtain a plurality of island-shaped GaN-based crystals on a base; and forming a plurality of island-shaped GaN on the base. And a second crystal growth step of forming a GaN-based crystal by using the base crystal as a growth nucleus to obtain a continuous film of the GaN-based crystal.
【００１２】好適な実施態様では、上記基体は、ＧａＮ
系結晶成長用基板と、その上面にＧａＮ系化合物のエピ
タキシャル成長結晶膜とを有することを特徴とする。In a preferred embodiment, the substrate is GaN
A substrate for system-based crystal growth and an epitaxially grown crystal film of a GaN-based compound on an upper surface thereof.
【００１３】好適な実施態様では、上記基体は、ＧａＮ
系結晶成長用基板と、その上面にＧａＮ系化合物、Ａｌ
Ｎ系化合物、ＺｎＯ系化合物のいずれかの多結晶膜を有
することを特徴とする。In a preferred embodiment, the substrate is GaN
Base crystal growth substrate and GaN compound, Al
It is characterized by having a polycrystalline film of either an N-based compound or a ZnO-based compound.
【００１４】好適な実施態様では、上記基体は、サファ
イアを有することを特徴とする。In a preferred embodiment, the substrate has sapphire.
【００１５】本発明はさらに、多層構造からなり、複数
の開口部を有するＧａＮ系結晶の成長を抑制する膜が表
面に設けられた基体上の、該開口部に、ＧａＮ系化合物
を選択的に結晶化させることにより、基体上に、複数の
島状のＧａＮ系結晶を得る第１の結晶成長工程と、次
に、該多層構造からなるＧａＮ系結晶の成長を抑制する
膜のうち、最下層を残して、上層を除去する工程と、そ
の後、該基体上に、該複数の島状のＧａＮ系結晶を成長
核として、ＧａＮ系結晶を形成することにより、ＧａＮ
系結晶の連続膜を得る第２の結晶成長工程とを含むこと
を特徴とする、ＧａＮ系結晶膜の製造方法を提供する。The present invention further provides a substrate having a multilayer structure having a plurality of openings on which a film for suppressing the growth of a GaN-based crystal is provided on a surface thereof, wherein a GaN-based compound is selectively applied to the openings. A first crystal growth step of obtaining a plurality of island-shaped GaN-based crystals on the substrate by crystallization; and a lowermost layer of a film for suppressing the growth of the GaN-based crystal having the multilayer structure. By removing the upper layer, and then forming a GaN-based crystal on the substrate using the plurality of island-shaped GaN-based crystals as growth nuclei.
And a second crystal growth step of obtaining a continuous film of a base crystal.
【００１６】なお、本明細書において、ＧａＮ系化合物
／結晶とは、ＩＩＩ族元素とＶ族元素よりなる化合物／
結晶であって、ＩＩＩ族元素としてＧａを、Ｖ族元素と
してＮを含むものを表わす。In this specification, a GaN-based compound / crystal is a compound composed of a group III element and a group V element.
It represents a crystal that contains Ga as a group III element and N as a group V element.
【００１７】本明細書において、ＡｌＮ系化合物とは、
ＩＩＩ族元素とＶ族元素よりなる化合物であって、ＩＩ
Ｉ族元素としてＡｌを、Ｖ族元素としてＮを含むものを
表わす。In the present specification, the AlN compound is
A compound comprising a group III element and a group V element,
A material containing Al as a Group I element and N as a Group V element is shown.
【００１８】本明細書において、ＺｎＯ系化合物とは、
ＩＩ族元素とＶＩ族元素よりなる化合物であって、ＩＩ
族元素としてＺｎを、ＶＩ族元素としてＯを含むものを
表わす。In the present specification, the ZnO-based compound is
A compound comprising a group II element and a group VI element,
A compound containing Zn as a group IV element and O as a group VI element is shown.
【００１９】本明細書において、昇華再結晶法とは、ア
ンモニアを含む雰囲気中で、Ｇａを含む原料を昇華さ
せ、所定の基体上に結晶化させることにより、ＧａＮ系
結晶を得る結晶成長方法のことを表す。In this specification, the sublimation recrystallization method is a crystal growth method for obtaining a GaN-based crystal by sublimating a Ga-containing material in an atmosphere containing ammonia and crystallizing the material on a predetermined substrate. It represents that.
【００２０】本明細書において、昇華とは、固相原料
が、そのままの分子形態で気化する厳密な意味での昇華
のみを指すものではなく、固相原料が分解／結合されて
気化する場合、液相原料が蒸発、分解／結合されて気化
する場合も含むものである。In the present specification, the sublimation does not refer only to the strict sense of sublimation in which a solid-phase raw material is vaporized in an intact molecular form. This includes the case where the liquid phase raw material is evaporated, decomposed / combined and vaporized.
【００２１】本明細書において、Ｇａを含む原料とは、
金属ガリウムもしくはＧａ化合物、または、そのいずれ
かを含む混合物からなる原料のことを表している。In the present specification, the raw material containing Ga is:
It indicates a raw material composed of metal gallium or a Ga compound, or a mixture containing either of them.
【００２２】本明細書において、島状の結晶とは、図２
（ｃ）もしくは図５（ｃ）に示されるように、個々の島
が完全に分離される場合のみを指すものではなく、各島
の一部がつながっていてもよいものとする。In the present specification, the island-shaped crystal is referred to as FIG.
As shown in FIG. 5 (c) or FIG. 5 (c), this does not mean only the case where the individual islands are completely separated, and some of the islands may be connected.
【００２３】本明細書において、エピタキシャル成長法
とは、ＶＰＥ（気相エピタキシャル）成長法、ＣＶＤ
（化学気相デポジション）成長法、ＭＯＶＰＥ（有機金
属化学気相エピタキシャル）成長法、ＭＯＣＶＤ（有機
金属化学気相デポジション）成長法、Ｈａｌｉｄｅ−Ｖ
ＰＥ（ハロゲン化物気相エピタキシャル）成長法、Ｈｙ
ｄｒｉｄｅ−ＶＰＥ（水素化物気相エピタキシャル）成
長法、ＭＢＥ（分子線エピタキシャル）成長法、ＭＯＭ
ＢＥ（有機金属分子線エピタキシャル）成長法、ＧＳＭ
ＢＥ（ガスソース分子線エピタキシャル）成長法、ＣＢ
Ｅ（化学ビームエピタキシャル）成長法を含む。In this specification, the epitaxial growth method means a VPE (vapor phase epitaxial) growth method, a CVD method, or the like.
(Chemical vapor deposition) growth method, MOVPE (metal organic chemical vapor deposition) growth method, MOCVD (metal organic chemical vapor deposition) growth method, Halide-V
PE (halide vapor phase epitaxial) growth method, Hy
Dride-VPE (hydride vapor phase epitaxial) growth method, MBE (molecular beam epitaxial) growth method, MOM
BE (organic metal molecular beam epitaxy) growth method, GSM
BE (gas source molecular beam epitaxial) growth method, CB
E (chemical beam epitaxial) growth method is included.
【００２４】[0024]
【発明の実施の形態】（実施の形態１）図１は、本発明
に係わる第１の実施の形態の結晶基板を示す断面模式図
である。図１に示すように、基体１０は、サファイア１
０１とその表面に順次設けられたＧａＮバッファ層１０
２、エピタキシャル成長ＧａＮ層１０３，ＳｉＯ2膜１
０４を有する。ＳｉＯ2膜１０４には開口部１０５が設
けられている。基体１０上のＳｉＯ2膜の開口部１０５
には昇華再結晶ＧａＮ結晶１１が形成されており、さら
に基体１０上の全面に、ＧａＮ結晶連続膜１２が設けら
れている。(Embodiment 1) FIG. 1 is a schematic sectional view showing a crystal substrate according to a first embodiment of the present invention. As shown in FIG. 1, the base 10 is made of sapphire 1
01 and a GaN buffer layer 10 sequentially provided on the surface thereof
2. Epitaxially grown GaN layer 103, SiO2 film 1
04. An opening 105 is provided in the SiO2 film 104. Opening 105 of SiO2 film on substrate 10
A sublimation recrystallized GaN crystal 11 is formed on the substrate 10, and a GaN crystal continuous film 12 is provided on the entire surface of the substrate 10.
【００２５】次に、図２（ａ）〜（ｃ）を参照して、本
実施の形態の結晶基板の作製方法および、本発明のＧａ
Ｎ系半導体膜の製造方法について説明する。Next, with reference to FIGS. 2A to 2C, a method of manufacturing a crystal substrate according to the present embodiment and a Ga substrate according to the present invention will be described.
A method for manufacturing an N-based semiconductor film will be described.
【００２６】始めに、図２（ａ）に示すように、Ｃ面を
表面とするサファイア基板１０１上に、公知の手法に
て、ＧａＮバッファ層１０２（厚さ５０ｎｍ）、ＭＯＶ
ＰＥ成長法によるエピタキシャル成長ＧａＮ層１０３
（厚さ４μｍ）を順次形成する。ここで、ＧａＮバッフ
ァ層１０２としては、ＭＯＶＰＥ成長法にてＧａＮ層１
０３よりも低い成長温度で形成された層や、その他のエ
ピタキシャル成長法で形成された層、スパッタにて形成
された層、真空蒸着法にて形成された層、イオンプレー
ティングにて形成された層などを用いることができる。
これらＧａＮバッファ層１０２を用いることにより、比
較的高品質のＭＯＶＰＥ成長法によるエピタキシャル成
長ＧａＮ層１０３を得ることができた。このような、サ
ファイア基板上に、ＭＯＶＰＥ法によってＧａＮ結晶層
を得る技術は公知であるので、その詳細は省略する。こ
こでＣ面サファイアに変えてＡ面あるいは、Ｒ面あるい
はＭ面サファイアを用いてもよい。First, as shown in FIG. 2A, a GaN buffer layer 102 (thickness: 50 nm) and an MOV
Epitaxially grown GaN layer 103 by PE growth method
(Thickness: 4 μm) are sequentially formed. Here, as the GaN buffer layer 102, the GaN layer 1 is formed by MOVPE growth.
Layers formed at a growth temperature lower than 03, layers formed by other epitaxial growth methods, layers formed by sputtering, layers formed by vacuum evaporation, layers formed by ion plating Etc. can be used.
By using these GaN buffer layers 102, a relatively high quality epitaxially grown GaN layer 103 by MOVPE growth could be obtained. Since a technique for obtaining a GaN crystal layer on a sapphire substrate by the MOVPE method is known, details thereof are omitted. Here, A-plane, R-plane, or M-plane sapphire may be used instead of C-plane sapphire.
【００２７】次いで、図２（ｂ）に示すように、ＧａＮ
層１０３の表面に、複数の開口部１０５を持つ、ＳｉＯ
2膜１０４（厚さ０．２μｍ）を形成する。このような
ＳｉＯ2膜１０４は、真空蒸着法、ＣＶＤ法、スパッタ
法などの成膜技術と、選択エッチング法もしくはリフト
オフ法を適宜用いて形成できることは、当業者にとって
周知の事実であるので、その詳細な作製方法の記載は省
略する。ここで、ＳｉＯ2膜１０４のパターンは、Ｇａ
Ｎ〈１−１００〉方向に沿った、線幅０．１〜３０μｍ
のストライプ状の開口部１０５が、ピッチ３〜２００μ
ｍで配置されるように形成すればよい。開口部１０５
の、線幅は２μｍ、ピッチは１０μｍとする。こうし
て、複数の開口部１０５を持つＧａＮ系結晶の成長を抑
制する膜１０４を表面に備える基体１０が得られる。Next, as shown in FIG.
SiO 2 having a plurality of openings 105 on the surface of the layer 103
Two films 104 (0.2 μm in thickness) are formed. It is well known to those skilled in the art that such an SiO2 film 104 can be formed by using a film forming technique such as a vacuum evaporation method, a CVD method, or a sputtering method and a selective etching method or a lift-off method as appropriate. A detailed description of the manufacturing method is omitted. Here, the pattern of the SiO2 film 104 is Ga
Line width 0.1-30 μm along N <1-100> direction
Are formed in a pitch of 3 to 200 μm.
What is necessary is just to form so that it may be arrange | positioned at m. Opening 105
Has a line width of 2 μm and a pitch of 10 μm. In this way, the base body 10 having the film 104 having the plurality of openings 105 for suppressing the growth of the GaN-based crystal on the surface is obtained.
【００２８】次いで、図２（ｃ）に示すように、昇華再
結晶法により、基体１０表面に、該開口部１０５にのみ
選択的に昇華再結晶法ＧａＮ結晶１１を形成する。Then, as shown in FIG. 2 (c), a sublimation recrystallization GaN crystal 11 is selectively formed only on the opening 105 on the surface of the substrate 10 by sublimation recrystallization.
【００２９】ここで、ＧａＮ結晶の昇華再結晶法につい
て、図３の断面図に示される成長装置を参照しつつ、詳
細に説明する。図３に示すように、この昇華再結晶法成
長装置１３０は、内部に密閉可能なチャンバーを有する
成長装置の本体１３７と、加熱装置１３１と、ガス導入
ライン１３４と、排気ライン１３５を備える。使用時に
は、昇華再結晶成長装置本体１３７のチャンバーの中
に、ＧａＮ粉末１３３が充填されたボート１３２が配置
され、そして、複数の開口部１０５を有するＳｉＯ2膜
１０４が表面に形成された基体１０（図２（ｂ））が、
そのＳｉＯ2膜面がボート１３２に向かい合うように配
置される。ガス導入ライン１３４からは、アンモニアと
窒素の混合ガス１３６が装置１３０内部に供給される。
このような構成において、加熱装置１３１でボート１３
２が９００〜１２００℃に加熱されることにより、Ｇａ
Ｎ粉末１３３が昇華によりもしくは分解されて昇華さ
れ、装置内部に連続的に供給されるアンモニアと窒素の
混合ガス雰囲気中で、基体１０表面に輸送される。ここ
で、基体１０は加熱装置１３１により８００〜１１００
℃に保たれており、その表面にてＧａＮ単結晶が再結晶
化される。再結晶化の駆動カを得るために、ボートより
も基体の方が低温に保たれることが望ましい。なお、Ｇ
ａＮ単結晶の再結晶化は、基体表面にＳｉＯ2膜１０４
が形成されているために、その開口部１０５でのみ選択
的に生じ、結果として、島状のＧａＮ単結晶が形成され
た。得られた島状のＧａＮ結晶は、例えば、幅２〜６μ
ｍ、高さ２〜６μｍのサイズであり、このようなサイズ
のＧａＮ結晶を得るのに要した時間は、０．０５〜１時
間であった。また、結晶の外形は、（１１−２０）面お
よび（０００１）面の発達した、断面が矩型の形態であ
った。なお、装置内に導入されるアンモニアと窒素の混
合ガスとしては、アンモニア：窒素＝１：１〜１５の体
積比で混合されたものが好ましい。Here, the sublimation recrystallization method of a GaN crystal will be described in detail with reference to a growth apparatus shown in a sectional view of FIG. As shown in FIG. 3, the sublimation recrystallization growth apparatus 130 includes a main body 137 of a growth apparatus having a chamber that can be hermetically sealed therein, a heating apparatus 131, a gas introduction line 134, and an exhaust line 135. In use, a boat 132 filled with GaN powder 133 is arranged in a chamber of the sublimation recrystallization apparatus main body 137, and a substrate 10 having a surface on which a SiO2 film 104 having a plurality of openings 105 is formed. (FIG. 2B)
The SiO2 film surface is arranged so as to face the boat 132. From the gas introduction line 134, a mixed gas 136 of ammonia and nitrogen is supplied into the device 130.
In such a configuration, the boat 13 is
2 is heated to 900 to 1200 ° C. so that Ga
The N powder 133 is sublimated by sublimation or decomposed, and transported to the surface of the substrate 10 in a mixed gas atmosphere of ammonia and nitrogen continuously supplied into the apparatus. Here, the substrate 10 is heated to 800 to 1100 by the heating device 131.
C., and the GaN single crystal is recrystallized on the surface. In order to obtain a driving force for recrystallization, it is desirable that the temperature of the substrate is kept lower than that of the boat. Note that G
The recrystallization of the aN single crystal is performed by forming the SiO2 film 104 on the substrate surface.
Is formed only selectively at the opening 105, and as a result, an island-like GaN single crystal is formed. The obtained island-shaped GaN crystal has, for example, a width of 2 to 6 μm.
m, a size of 2 to 6 μm in height, and a time required to obtain a GaN crystal of such a size was 0.05 to 1 hour. Further, the outer shape of the crystal was a rectangular form in which the (11-20) plane and the (0001) plane were developed. The mixed gas of ammonia and nitrogen introduced into the apparatus is preferably a mixture of ammonia and nitrogen at a volume ratio of 1: 1 to 15.
【００３０】その後、図２（ｃ）に示される基体１０を
酸洗浄または／およびアルカリ洗浄して、表面に付着し
た余分のＧａＮ微結晶やＧａ金属（図には示されない）
を除去し、次いでＭＯＶＰＥ成長法を用いて、さらに、
ＧａＮ結晶を成長したところ、昇華再結晶法により形成
された島状のＧａＮ結晶を成長核として、ＧａＮ結晶の
成長が進行し、最終的に、図１に示されるような連続膜
が得られた。このとき、ＩＩＩ族原料としてトリメチル
ガリウムを用い、Ｖ族原料としてアンモニアを用い、そ
してキャリアガスとして水素を用いた。成長に先だっ
て、ＭＯＶＰＥ装置内部で、基体表面をアンモニアを含
む気流中、１１５０℃で処理を行うことが望ましく、ま
た、結晶の成長温度としては、９５０〜１１５０℃の範
囲が好ましく、特に１１００℃程度の比較的高温が望ま
しかった。このとき、島状結晶の（１１−２０）面から
横方向の成長が優先的に進行し、結果として図１のよう
な連続膜が得られた。成長時間１〜３時間で、ＳｉＯ2
膜１０４より上方に、厚さ４〜１５μｍのＧａＮ単結晶
連続膜１２が得られた。Thereafter, the substrate 10 shown in FIG. 2 (c) is washed with an acid and / or an alkali to remove extra GaN microcrystals and Ga metal (not shown) attached to the surface.
And then using the MOVPE growth method,
When the GaN crystal was grown, the growth of the GaN crystal progressed using the island-like GaN crystal formed by the sublimation recrystallization method as a growth nucleus, and finally a continuous film as shown in FIG. 1 was obtained. . At this time, trimethylgallium was used as a group III raw material, ammonia was used as a group V raw material, and hydrogen was used as a carrier gas. Prior to the growth, it is desirable that the surface of the substrate is treated at 1150 ° C. in a gas flow containing ammonia inside the MOVPE apparatus, and the crystal growth temperature is preferably in the range of 950 to 1150 ° C., and particularly about 1100 ° C. A relatively high temperature was desirable. At this time, growth in the lateral direction proceeded preferentially from the (11-20) plane of the island crystal, and as a result, a continuous film as shown in FIG. 1 was obtained. With a growth time of 1 to 3 hours, SiO2
A continuous GaN single crystal film 12 having a thickness of 4 to 15 μm was obtained above the film 104.
【００３１】このような、膜の晶質をＴＥＭ（透過電子
顕微鏡）で評価したところ、表面付近では、欠陥密度３
×１０-3ｃｍ-2程度であり、従来の技術と比較して、向
上が見られた。また、ＳｉＯ2膜１０４の開口部１０５
位置と、欠陥密度との間にはほとんど相関がなく、面内
でほぼ一様に高品質膜を得ることができた。そのため、
本発明の結晶基板をＧａＮ系半導体を用いた電子デバイ
スの結晶成長用基板に用いれば、基板上の種々の位置に
形成した電子デバイスの性能を均一にできる。また、例
えば、発光ダイオードのように、大きい（２００μｍ×
２００μｍ程度）発光部を有するデバイスを作製して
も、発光部に、結晶品質の差による発光ムラが生じてし
まうような問題が起こらない。さらに、結晶基板自身の
品質が高いので、その上に形成される電子デバイスの特
性を向上できる。When the crystal quality of such a film was evaluated by a TEM (transmission electron microscope), the defect density was 3 near the surface.
It is about × 10−3 cm−2, which is an improvement as compared with the conventional technology. The opening 105 of the SiO2 film 104
There was almost no correlation between the position and the defect density, and a high-quality film could be obtained almost uniformly in the plane. for that reason,
When the crystal substrate of the present invention is used as a substrate for crystal growth of an electronic device using a GaN-based semiconductor, the performance of electronic devices formed at various positions on the substrate can be made uniform. In addition, for example, as in the case of a light emitting diode, it is large (200 μm ×
Even if a device having a light-emitting portion is manufactured, there is no problem that light-emitting unevenness occurs due to a difference in crystal quality in the light-emitting portion. Further, since the quality of the crystal substrate itself is high, the characteristics of an electronic device formed thereon can be improved.
【００３２】従来の技術よりも高品質の結晶が得られる
理由を、本発明者らは、以下のように推測している。 （１）第１の結晶成長で得られた島状結晶の結晶品質が
良好なことによる：選択成長を用いた昇華再結晶法によ
り欠陥密度１０-5ｃｍ-2程度の高品質な島状結晶が得ら
れた。これにより、第２の結晶成長における成長核の品
質が高く、ここで得られる連続膜の結晶品質が向上す
る。 （２）第１の結晶成長で得られた島状結晶の形状によ
る：基体１０上にＳｉＯ2膜１０４が突出しており、第
２の結晶成長の際に、横方向への結晶成長が容易に起こ
る。これにより、従来の技術において、基体との界面よ
り上方に延伸し、結晶表面にまで達していた欠陥が見ら
れなくなった。 （３）第１の結晶成長で得られた島状結晶の結晶面によ
る：基体１０の表面に垂直な面である（１１−２０）面
が発達しており、第２の結晶成長の初期過程では、この
ような面が常に表出するような結晶成長モードとなっ
て、導入される欠陥が少なくなる。The present inventors speculate as to the reason why a crystal having higher quality than that of the conventional technique can be obtained as follows. (1) Due to good crystal quality of the island crystal obtained by the first crystal growth: high quality island crystal having a defect density of about 10−5 cm−2 by sublimation recrystallization using selective growth. was gotten. Thereby, the quality of the growth nucleus in the second crystal growth is high, and the crystal quality of the continuous film obtained here is improved. (2) Depends on the shape of the island-like crystal obtained by the first crystal growth: the SiO2 film 104 protrudes on the substrate 10, and the crystal growth in the lateral direction is easy during the second crystal growth. Occur. As a result, in the prior art, the defect extending above the interface with the substrate and reaching the crystal surface was not observed. (3) According to the crystal plane of the island-shaped crystal obtained by the first crystal growth: the (11-20) plane, which is a plane perpendicular to the surface of the substrate 10, has been developed, and the initial stage of the second crystal growth In such a case, the crystal growth mode is such that such a surface is always exposed, and defects introduced are reduced.
【００３３】なお、本実施の形態における昇華再結晶法
により形成された島状結晶１１は、図２（ｃ）に示され
るように、個々の島が完全に分離している必要はなく、
島の一部がつながったようなパターン（例えば、全体と
して、格子状の形態をした結晶）であってもよく、この
ような場合においても、本発明の効果が損なわれるもの
ではない。 （実施の形態２）図４は、本発明に係わる第２の実施の
形態の結晶基板を示す断面模式図である。図４に示すよ
うに、基体２０は、ＳｉＣ基板２０１とその表面に順次
設けられたＡｌＮバッファ層２０２，およびＳｉＮx膜
２０３を有する。ＳｉＮx膜２０３には開口部２０５が
設けられている。基体２０上の膜の開口部２０５には昇
華再結晶ＧａＮ結晶２１が形成されており、さらに基体
２０上の全面に、ＧａＮ結晶連続膜２２が設けられてい
る。The island-like crystal 11 formed by the sublimation recrystallization method in the present embodiment does not need to have individual islands completely separated as shown in FIG.
A pattern in which a part of the islands are connected (for example, a crystal having a lattice shape as a whole) may be used, and even in such a case, the effect of the present invention is not impaired. (Embodiment 2) FIG. 4 is a schematic sectional view showing a crystal substrate according to a second embodiment of the present invention. As shown in FIG. 4, the base 20 has a SiC substrate 201, an AlN buffer layer 202 and a SiNx film 203 which are sequentially provided on the surface thereof. An opening 205 is provided in the SiNx film 203. A sublimation recrystallized GaN crystal 21 is formed in the opening 205 of the film on the substrate 20, and a GaN crystal continuous film 22 is provided on the entire surface of the substrate 20.
【００３４】次に、図５（ａ）〜（ｃ）を参照して、本
実施の形態の結晶基板の作製方法および、本実施の形態
のＧａＮ系半導体膜の製造方法について説明する。Next, with reference to FIGS. 5A to 5C, a method for manufacturing a crystal substrate according to the present embodiment and a method for manufacturing a GaN-based semiconductor film according to the present embodiment will be described.
【００３５】始めに、図５（ａ）に示すように、（００
０１）面を表面とするＳｉＣ基板２０１上に、基板温度
３００℃にて、スパッタ法にてＡｌＮバッファ層２０２
（厚さ２００ｎｍ）を形成する。なお、スパッタ法にか
えて、エピタキシャル成長法、真空蒸着法にて形成され
た層、イオンプレーティング法等も用いることが可能で
あるが、ここでは、生産性の良好な点から、スパッタ法
を選択した。First, as shown in FIG.
The AlN buffer layer 202 is formed on a SiC substrate 201 having a surface 01) by sputtering at a substrate temperature of 300 ° C.
(Thickness: 200 nm). Note that, instead of the sputtering method, a layer formed by an epitaxial growth method, a vacuum evaporation method, an ion plating method, or the like can also be used. Here, the sputtering method is selected from the viewpoint of good productivity. did.
【００３６】次いで、図５（ｂ）に示すように、ＡｌＮ
バッファ層２０２の表面に、複数の開口部２０５を有す
る、ＳｉＮx膜２０３（厚さ０．３μｍ）、ＳｉＯ2２０
４（厚さ０．２μｍ）からなる多層膜を形成した。この
ようなＳｉＮx膜２０３、ＳｉＯ2２０５は、真空蒸発
法、ＣＶＤ法スパッタ法などの成膜技術と、選択エッチ
ング法もしくはリフトオフ法を適宜用いて形成できるこ
とは当業者にとって周知の事実であるので、その詳細な
作製方法の記載は省略する。ここで、該多層からなるＧ
ａＮ系結晶の成長を抑制する膜に形成されるパターン
は、円形の開口部２０５が多数設けられているものとし
た。開口部の大きさをΦ０．１〜３０μｍ、中心間隔を
３〜２００μｍとなるように配置すればよい。開口部２
０５の、開口Φは１０μｍ、中心間隔は１００μｍとし
た。こうして、多層構造からなり、複数の開口部２０５
を有するＧａＮ系結晶の成長を抑制する膜を備える、基
体２０が得られた。Next, as shown in FIG.
On the surface of the buffer layer 202, a SiNx film 203 (thickness: 0.3 μm) having a plurality of openings 205, SiO2 20
4 (0.2 μm thick) was formed. It is well known to those skilled in the art that such a SiNx film 203 and SiO2 205 can be formed by appropriately using a film forming technique such as a vacuum evaporation method or a CVD sputtering method and a selective etching method or a lift-off method. The description of the detailed manufacturing method is omitted. Here, the G
The pattern formed on the film for suppressing the growth of the aN-based crystal had a large number of circular openings 205. The openings may be arranged so that the size of the openings is Φ0.1 to 30 μm and the center interval is 3 to 200 μm. Opening 2
05, the opening Φ was 10 μm, and the center interval was 100 μm. Thus, a plurality of openings 205 having a multilayer structure are formed.
The substrate 20 provided with a film for suppressing the growth of a GaN-based crystal having the following.
【００３７】次いで、図５（ｃ）に示すように、昇華再
結晶法により、基体２０表面に、該開口部２０５にのみ
選択的に昇華再結晶法ＧａＮ結晶２１を形成した。この
工程については、実施の形態１と同様であるので、その
詳細は省略する。こうして、島状のＧａＮ単結晶が形成
され、得られた結晶は、例えば、直径２０〜６０μｍ、
高さ２０〜６０μｍのサイズであり、このようなサイズ
のＧａＮ結晶を得るのに要した時間は、０．５〜２時間
であった。また、結晶の外形は、｛１０−１０｝面およ
び（０００１）面の発達した、六角柱形態であった。Next, as shown in FIG. 5 (c), a sublimation recrystallization GaN crystal 21 was selectively formed only on the opening 205 on the surface of the substrate 20 by sublimation recrystallization. Since this step is the same as that of the first embodiment, the details are omitted. Thus, an island-like GaN single crystal is formed, and the obtained crystal has a diameter of, for example, 20 to 60 μm.
The size was 20 to 60 μm in height, and the time required to obtain a GaN crystal of such a size was 0.5 to 2 hours. The crystal had a hexagonal prism shape with developed {10-10} planes and (0001) planes.
【００３８】その後、図５（ｃ）に示された基体２０
を、ＨＦ液で洗浄したところ、表面に付着した余分のＧ
ａＮ微結晶やＧａ金属（図には示されない）が、ＳｉＯ
2膜２０４と共に完全に除去された。さらに、Ｈｙｄｒ
ｉｄｅ−ＶＰＥ成長法を用いて、さらに、ＧａＮ結晶を
成長したところ、昇華再結晶法により形成された島状の
ＧａＮ結晶を成長核として、ＧａＮ結晶が成長し、最終
的には、図４に示される連続膜２２が得られた。このと
き、ＩＩＩ族原料として金属ガリウムを用い、Ｇａ原料
の輸送担体として塩化水素を用い、Ｖ族原料としてアン
モニアを用い、そしてキャリアガスとして水素を用い
た。成長温度としては、９５０〜１１５０℃の範囲がよ
く、特に１１００℃程度の比較的高温が望ましかった。
このとき、島状結晶の｛１０−１０｝面から横方向の成
長が進行し、結果として図４に示すような連続膜２２が
得られた。成長時間を１〜３時間とし、ＳｉＮx膜２０
３の上方に、厚さ１００〜３００μｍのＧａＮ単結晶連
続膜２２が得られた。Thereafter, the substrate 20 shown in FIG.
Was washed with HF solution, and extra G adhered to the surface
aN microcrystals and Ga metal (not shown)
2 Completely removed together with the film 204. In addition, Hydr
When the GaN crystal was further grown using the ide-VPE growth method, the GaN crystal grew using the island-like GaN crystal formed by the sublimation recrystallization method as a growth nucleus. The resulting continuous film 22 was obtained. At this time, metallic gallium was used as a group III raw material, hydrogen chloride was used as a carrier for transporting a Ga raw material, ammonia was used as a group V raw material, and hydrogen was used as a carrier gas. The growth temperature is preferably in the range of 950 to 1150 ° C, and particularly, a relatively high temperature of about 1100 ° C has been desired.
At this time, the lateral growth of the island-shaped crystal proceeded from the {10-10} plane, and as a result, a continuous film 22 as shown in FIG. 4 was obtained. The growth time is set to 1 to 3 hours, and the SiNx film 20 is formed.
Above 3, a GaN single crystal continuous film 22 having a thickness of 100 to 300 μm was obtained.
【００３９】このような、膜の品質をＴＥＭで評価した
ところ、表面付近では、欠陥密度５×１０-3ｃｍ-2程度
であり、従来の技術と比較して、向上が見られた。ま
た、ＳｉＮx膜２０３の開口部２０５位置と、欠陥密度
との間には相関がなく、面内で一様に高品質膜を得るこ
とができた。このように、実施の形態１と同様に、従来
の技術と比較して、高品質の結晶基板が得られた。When the quality of the film was evaluated by TEM, the defect density near the surface was about 5 × 10−3 cm−2 , which was an improvement as compared with the prior art. In addition, there was no correlation between the position of the opening 205 of the SiNx film 203 and the defect density, and a high-quality film could be uniformly obtained in the plane. Thus, as in the first embodiment, a high-quality crystal substrate was obtained as compared with the conventional technique.
【００４０】また、本実施の形態においては、昇華再結
晶法で島状結晶を形成する工程において表面に付着した
余分のＧａＮ微結晶やＧａ金属が、ＳｉＯ2膜２０４と
ともに、完全に除去された。従って、連続結晶膜２２を
得るための結晶成長工程では、結晶は、そのような島状
結晶を成長核として結晶が成長するので、得られる連続
結晶膜の品質の低下が防止された。 （実施の形態３）図６は、本発明に係わる第３の実施の
形態の結晶基板を示す断面模式図である。図６に示すよ
うに、基体３０は、表面に凹凸が設けられたＡ面サファ
イア基板３０１と、その表面に設けられたＳｉＮｘ膜３
０２を有する。ＳｉＮx膜３０２には開口部３０３が設
けられている。基体３０上のＳｉＮx膜の開口部３０３
には昇華再結晶ＧａＮ結晶３１が形成されており、さら
に基体３０上の全面に、ＧａＮ結晶連続膜３２が設けら
れている。In the present embodiment, extra GaN microcrystals and Ga metal adhering to the surface in the step of forming island-shaped crystals by sublimation recrystallization are completely removed together with the SiO2 film 204. . Therefore, in the crystal growth step for obtaining the continuous crystal film 22, the crystal grows using such an island-shaped crystal as a growth nucleus, so that the quality of the obtained continuous crystal film is prevented from being deteriorated. (Embodiment 3) FIG. 6 is a schematic sectional view showing a crystal substrate according to a third embodiment of the present invention. As shown in FIG. 6, a substrate 30 includes an A-plane sapphire substrate 301 having irregularities on its surface and a SiNx film 3 formed on the surface.
02. An opening 303 is provided in the SiNx film 302. Opening 303 of SiNx film on substrate 30
A sublimated recrystallized GaN crystal 31 is formed on the substrate 30, and a GaN crystal continuous film 32 is provided on the entire surface of the substrate 30.
【００４１】本実施の形態は、実施の形態２の変形例で
あり、基体の構成が異なる他は、実施の形態２と同様で
ある。本実施の形態は、表面に凹凸が設けられたＡ面サ
ファイアを用いる点で実施の形態２と異なる。ここで、
サファイア基板３０表面に設けられた凹凸は、昇華再結
晶成長におけるＧａＮ結晶成長開始の成長核となる。そ
の結果、実施の形態１におけるエピタキシャル成長Ｇａ
Ｎ層１０３、または実施の形態２におけるＡｌＮバッフ
ァ層２０２のような特別な層を設けなくても、良好な選
択性をもって、ＳｉＮx膜３０２の開口部３０３にのみ
に島状結晶を形成し得る。ここで、凹凸の形状は、凹凸
の平方二乗平均値（ＲＭＳ）にして５０ｎｍ、平均ピッ
チ５０ｎｍ程度であった。本実施の形態の結晶基板の作
製方法およびＧａＮ系半導体膜の製造方法については、
実施の形態１もしくは２を参照して容易に推測できるの
で、その詳細な説明は省略する。This embodiment is a modification of the second embodiment, and is the same as the second embodiment except that the structure of the base is different. The present embodiment is different from the second embodiment in that an A-plane sapphire having an uneven surface is used. here,
The unevenness provided on the surface of the sapphire substrate 30 becomes a growth nucleus at the start of GaN crystal growth in sublimation recrystallization growth. As a result, the epitaxially grown Ga
Even if the N layer 103 or the special layer such as the AlN buffer layer 202 in the second embodiment is not provided, an island crystal can be formed only in the opening 303 of the SiNx film 302 with good selectivity. . Here, the shape of the concavities and convexities was about 50 nm in terms of the root mean square value (RMS) of the concavities and convexities, and the average pitch was about 50 nm. Regarding the method for manufacturing a crystal substrate and the method for manufacturing a GaN-based semiconductor film of this embodiment,
Since it can be easily inferred with reference to the first or second embodiment, a detailed description thereof will be omitted.
【００４２】本実施の形態で得られたＧａＮ連続成長膜
の品質をＴＥＭで評価したところ、表面付近において、
欠陥密度は７ｘ１０-3ｃｍ-2程度であり、従来の技術と
比較して、向上が見られた。また、ＳｉＮx膜３０２の
開口部３０３位置と、欠陥密度との間には相関がなく、
面内で一様にこのような高品質膜を得ることができた。
このように、実施の形態１もしくは２と同様に本実施の
形態においても、従来の技術よりも、高品質の結晶基板
を得ることができた。The quality of the GaN continuous growth film obtained in the present embodiment was evaluated by TEM.
The defect density was about 7 × 10−3 cm−2 , which was an improvement as compared with the conventional technology. Further, there is no correlation between the position of the opening 303 of the SiNx film 302 and the defect density,
Such a high quality film could be uniformly obtained in the plane.
As described above, in the present embodiment as well as in the first or second embodiment, a crystal substrate having higher quality than that of the conventional technique can be obtained.
【００４３】以上、実施の形態１ないし３により、本発
明の実施様態を特定の例について説明したが、本発明の
適用はこれに限定されるものでもなく、本発明の趣旨を
逸脱しない範囲で、変更できる。例えば、実施の形態１
ないし３の各構成要素／各工程は、互いに他の実施の形
態に示された、対応する構成要素／工程に置換できる。
本発明における、基体表面に設けられたＧａＮ結晶、
昇華再結晶法により形成されるＧａＮ島状結晶、連続結
晶膜を構成するＧａＮ結晶は、それぞれ、その他のＧａ
Ｎ系化合物結晶に置換することが可能である。例えば、
構成元素の一部を、Ｂ，Ａｌ，Ｉｎ，Ｔｌ，Ｐ，Ａｓ，
Ｓｂ，Ｂｅ，Ｍｇ，Ｃｄ，Ｚｎ，Ｃ，Ｓｉ，Ｇｅ，Ｓ
ｎ，Ｏ，Ｓ，Ｓｅ，Ｔｅ，Ｈ，Ｓｃ，Ｔｉ，Ｖ，Ｃｒ，
Ｙ，Ｚｒ，Ｎｂ，ランタノイド，等で置換したり、もし
くはこれらの一部を添加することにより、ＧａＮ系化合
物結晶の、格子定数、エネルギーバンド構造、光吸収特
性、導電型、導電率、単結晶成長温度を適宜調整するこ
とができる。As described above, the embodiments of the present invention have been described with reference to the specific examples by the first to third embodiments. However, the application of the present invention is not limited to this, and the present invention is not limited thereto. , Can be changed. For example, Embodiment 1
Each of the components / steps 3 to 3 can be replaced with the corresponding components / steps described in the other embodiments.
In the present invention, a GaN crystal provided on a substrate surface,
The GaN island-shaped crystal formed by the sublimation recrystallization method and the GaN crystal forming the continuous crystal film are each other Ga
It is possible to substitute N-based compound crystals. For example,
Some of the constituent elements are B, Al, In, Tl, P, As,
Sb, Be, Mg, Cd, Zn, C, Si, Ge, S
n, O, S, Se, Te, H, Sc, Ti, V, Cr,
By substituting with Y, Zr, Nb, lanthanoid, or adding some of them, the lattice constant, energy band structure, light absorption characteristics, conductivity type, conductivity, and single crystal of the GaN-based compound crystal are obtained. The growth temperature can be adjusted appropriately.
【００４４】また、各実施の形態における基体は、任意
の結晶面を表面とするＧａＮ系結晶成長用基板の上面
に、直接、もしくはその表面を、バッファ層および／ま
たはエピタキシャル成長ＧａＮ系結晶で被覆したものの
上面に、ＧａＮ系結晶の成長を抑制する膜を形成したも
のである。ここで、ＧａＮ系結晶基板は、Ｓｉ，Ｇｅ，
ＳｉＣ，ＧａＮ，ＧａＰ，ＧａＡｓ，ＩｎＮ，ＩｎＰ，
ＩｎＡｓ，ＺｎＯ，ＺｎＳｅ，ＺｎＳ，ＭｇＡｌ2Ｏ4，
ＭｇＧａ2Ｏ4，ＬｉＧａＯ2，ＬｉＡｌＯ2，サファイ
ア、ルビー等で置換してもよく、そしてバッファ層は、
ＡｌＮ，ＩｎＮ，ＧａＡｌＮ，ＩｎＧａＮ，ＩｎＡｌ
Ｎ，ＩｎＧａＡｌＮ，ＺｎＯ，ＭｇＦ等で置換してもよ
い。In each of the embodiments, the substrate is such that the upper surface of a GaN-based crystal growth substrate having an arbitrary crystal plane as a surface is directly or covered with a buffer layer and / or an epitaxially grown GaN-based crystal. A film for suppressing the growth of a GaN-based crystal is formed on the upper surface of the object. Here, the GaN-based crystal substrate is made of Si, Ge,
SiC, GaN, GaP, GaAs, InN, InP,
InAs, ZnO, ZnSe, ZnS, MgAl2 O4 ,
MgGa2 O4 , LiGaO2 , LiAlO2 , sapphire, ruby and the like may be substituted, and the buffer layer
AlN, InN, GaAlN, InGaN, InAl
It may be replaced with N, InGaAlN, ZnO, MgF or the like.
【００４５】各実施の形態におけるＧａＮ系結晶の成長
を抑制する膜は、ＳｉＮx，ＳｉＯy，ＳｉＯＮ，Ｃ，Ｓ
ｉ，Ｇｅ等やこれらを含む混合物材料に置換できる。ま
た、そのパターンの形状・サイズ等は適宜変更してよ
い。The film for suppressing the growth of the GaN-based crystal in each embodiment is made of SiNx , SiOy , SiON, C, S
It can be replaced with i, Ge, etc. or a mixture material containing these. Further, the shape, size, and the like of the pattern may be appropriately changed.
【００４６】各実施の形態における昇華再結晶によるＧ
ａＮ系結晶成長において、原料はＧａＮの粉末に限られ
るものではなく、針状結晶、エピタキシャル成長ＧａＮ
結晶、表面窒化Ｇａ金属、その他の形態をしたものでも
よいことはいうまでもなく、Ｇａ金属その他のＧａ化合
物を混合した原料としてもよい。また、供給される雰囲
気ガスは上述のものに限られるわけではなく、アルゴン
やヘリウムなどの他の不活性ガスを混合してもよく、ま
た、Ｇａ原料の昇華を促進するために、水素などのガス
を混合してもよい。さらには、ＧａＮに添加・混合され
る種々の材料の原料ガス、例えば、シランガスやトリメ
チルガリウム、トリメチルアルミニウム等を混合しても
よい。さらに、雰囲気ガスは、図３に示したように、装
置外部から連続的に供給されるものである必要はなく、
あらかじめ装置内部に封じ込めた、いわゆる閉管法を用
いてもよい。また、図３において、原料を充填するボー
トと基体との間に、気流を制御するためのオリフィスを
設けて対流を抑止する工夫を行うと、島状結晶が高品質
化され得る。さらに、昇華再結晶成長装置は、図３に示
されたように縦型である必要はなく、原料、基体が水平
に配置されたもの（いわゆる、横型）であってもよい。G by sublimation recrystallization in each embodiment
In the aN-based crystal growth, the raw material is not limited to GaN powder, but may be needle-like crystals, epitaxially grown GaN.
Needless to say, it may be a crystal, a surface-nitride Ga metal, or another form, and may be a raw material in which Ga metal or another Ga compound is mixed. In addition, the supplied atmosphere gas is not limited to the above-described one, and another inert gas such as argon or helium may be mixed.In order to promote the sublimation of the Ga raw material, hydrogen or the like is used. Gases may be mixed. Further, source gases of various materials added to and mixed with GaN, for example, silane gas, trimethylgallium, trimethylaluminum, and the like may be mixed. Further, the atmosphere gas does not need to be continuously supplied from the outside of the apparatus as shown in FIG.
A so-called closed tube method, which is previously sealed inside the device, may be used. In FIG. 3, if an orifice for controlling the airflow is provided between the boat for filling the raw material and the base to suppress the convection, the island crystal can be improved in quality. Furthermore, the sublimation recrystallization growth apparatus does not need to be a vertical type as shown in FIG. 3, but may be a type in which raw materials and substrates are horizontally arranged (so-called horizontal type).
【００４７】さらに、各実施の形態におけるＧａＮ連続
結晶を得るための成長法は、それぞれ、他のエピタキシ
ャル成長法に置換することができる。Further, the growth method for obtaining a GaN continuous crystal in each embodiment can be replaced with another epitaxial growth method.
【００４８】[0048]
【発明の効果】本発明の結晶基板をＧａＮ系半導体デバ
イス形成用基板として用いることにより、デバイスの性
能を向上することができる。また、本発明のＧａＮ系結
晶膜の製造方法によれば、欠陥密度が小さく、また、欠
陥密度に面内の分布の無い、高晶質のＧａＮ系結晶連続
膜を得ることができる。By using the crystal substrate of the present invention as a substrate for forming a GaN-based semiconductor device, the performance of the device can be improved. Further, according to the method for producing a GaN-based crystal film of the present invention, it is possible to obtain a highly crystalline GaN-based crystal continuous film having a small defect density and no in-plane distribution of the defect density.
【図１】本発明の第１の実施の形態におけるＧａＮ系結
晶基板を示す断面模式図である。FIG. 1 is a schematic sectional view showing a GaN-based crystal substrate according to a first embodiment of the present invention.
【図２】本発明の第１の実施の形態における、ＧａＮ系
結晶膜の製造方法を説明するための図である。FIG. 2 is a diagram for explaining a method of manufacturing a GaN-based crystal film according to the first embodiment of the present invention.
【図３】本発明の第１の実施の形態における、昇華再結
晶成長装置を示す模式図である。FIG. 3 is a schematic diagram showing a sublimation recrystallization growth apparatus according to the first embodiment of the present invention.
【図４】本発明の第２の実施の形態におけるＧａＮ系結
晶基板を示す断面模式図である。FIG. 4 is a schematic sectional view showing a GaN-based crystal substrate according to a second embodiment of the present invention.
【図５】本発明の第２の実施の形態における、ＧａＮ系
結晶膜の製造方法を説明するための図である。FIG. 5 is a view for explaining a method of manufacturing a GaN-based crystal film according to a second embodiment of the present invention.
【図６】本発明の第２の実施の形態におけるＧａＮ系結
晶基板を示す断面模式図である。FIG. 6 is a schematic sectional view showing a GaN-based crystal substrate according to a second embodiment of the present invention.
【図７】第１の従来技術のＧａＮ系結晶基板を示す断面
模式図である。FIG. 7 is a schematic cross-sectional view illustrating a GaN-based crystal substrate according to a first prior art.
【図８】第２の従来技術のＧａＮ系結晶基板を示す断面
模式図である。FIG. 8 is a schematic sectional view showing a GaN-based crystal substrate according to a second conventional technique.
１０，２０，３０ 基体 １１，２１，３１ 昇華再結晶法ＧａＮ島状結晶 １２，２２，３２ ＧａＮ結晶連続膜 １０１ Ｃ面サファイア １０２ ＧａＮバッファ層 １０３ エピタキシャル成長ＧａＮ層 １０４，２０４ ＳｉＯ2膜 １０５，２０５ 開口部 ２０１ ＳｉＣ ２０２ ＡｌＮバッファ層 ２０３，３０２ ＳｉＮｘ膜 ３０１ Ａ面サファイア ３０３ 開口部 １３０ 昇華再結晶法成長装置10, 20, 30 Substrate 11, 21, 31 Sublimation recrystallization GaN island crystal 12, 22, 32 GaN crystal continuous film 101 C-plane sapphire 102 GaN buffer layer 103 Epitaxially grown GaN layer 104, 204 SiO2 film 105, 205 Opening Unit 201 SiC 202 AlN buffer layer 203, 302 SiNx film 301 A-plane sapphire 303 Opening 130 Sublimation recrystallization growth apparatus
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP13577698AJP4390090B2 (en) | 1998-05-18 | 1998-05-18 | GaN crystal film manufacturing method |
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP13577698AJP4390090B2 (en) | 1998-05-18 | 1998-05-18 | GaN crystal film manufacturing method |
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2009101474ADivisionJP4964271B2 (en) | 2009-04-17 | 2009-04-17 | GaN crystal film manufacturing method |
| Publication Number | Publication Date |
|---|---|
| JPH11329971Atrue JPH11329971A (en) | 1999-11-30 |
| JPH11329971A5 JPH11329971A5 (en) | 2005-10-06 |
| JP4390090B2 JP4390090B2 (en) | 2009-12-24 |
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP13577698AExpired - Fee RelatedJP4390090B2 (en) | 1998-05-18 | 1998-05-18 | GaN crystal film manufacturing method |
| Country | Link |
|---|---|
| JP (1) | JP4390090B2 (en) |
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