JP2013187489A - Compound semiconductor substrate and manufacturing method of the same - Google Patents

Compound semiconductor substrate and manufacturing method of the same Download PDF

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JP2013187489A
JP2013187489A JP2012053445A JP2012053445A JP2013187489A JP 2013187489 A JP2013187489 A JP 2013187489A JP 2012053445 A JP2012053445 A JP 2012053445A JP 2012053445 A JP2012053445 A JP 2012053445A JP 2013187489 A JP2013187489 A JP 2013187489A
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compound semiconductor
semiconductor layer
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gaas
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JP6050595B2 (en
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Hirotaka Toga
寛崇 外賀
Tadashi Morohara
理 諸原
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Asahi Kasei Corp
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Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method which can easily achieve a compound semiconductor substrate including on an Si substrate, GaAsSb which has good crystallinity and excellent surface flatness.SOLUTION: A manufacturing method of a present embodiment is a manufacturing method of compound semiconductor substrate in which a first compound semiconductor layer and a second compound semiconductor layer are alternately stacked on an Si substrate. A process of forming the second compound semiconductor layer is a process of simultaneously exposing a Ga material, an As material and an Sb material. A ratio of a molecular beam intensity of the Sb material to a molecular beam intensity of the Ga material, which is necessary for making a formation speed of the second compound semiconductor layer be 1 μm per one hour is not less than 1.

Description

本発明は、化合物半導体基板及びその製造方法に関する。より詳細には、Ｓｉ基板上に形成されたＧａＡｓＳｂ層を備えた化合物半導体基板及びその製造方法に関する。   The present invention relates to a compound semiconductor substrate and a manufacturing method thereof. More specifically, the present invention relates to a compound semiconductor substrate having a GaAsSb layer formed on a Si substrate and a method for manufacturing the same.

ＧａＡｓに代表される化合物半導体は、Ｓｉでは得ることのできない特性を発現することができるため、ＨＥＭＴ（Ｈｉｇｈ Ｅｌｅｃｔｒｏｎ Ｍｏｂｉｌｉｔｙ Ｔｒａｎｓｉｓｔｏｒ）やＨＢＴ（Ｈｅｔｅｒｏｊｕｎｃｔｉｏｎ Ｂｉｐｏｌａｒ Ｔｒａｎｓｉｓｔｏｒ）などの高速電子デバイスや、ＬＥＤ（Ｌｉｇｈｔ Ｅｍｉｔｔｅｄ Ｄｉｏｄｅ）、ＬＤ（Ｌａｓｅｒ Ｄｉｏｄｅ）などの光デバイス、高効率の太陽電池、磁気センサなど多岐に渡るデバイスへの応用が進められている。   Since compound semiconductors typified by GaAs can exhibit characteristics that cannot be obtained with Si, high-speed electronic devices such as HEMT (High Electron Mobility Transistor) and HBT (Heterojunction Bipolar Transistor), and LED (Light Emitter). ), Optical devices such as LD (Laser Diode), high-efficiency solar cells, magnetic sensors, etc., are being applied to a wide variety of devices.

これらのデバイスにおいて、良好な特性、信頼性を得るためには、その上にデバイス層を形成するための基板上に、結晶欠陥が少なく、表面が平坦な化合物半導体層を形成する技術が重要である。基板材料としてＧａＡｓやＩｎＰなどの単結晶からなる化合物半導体を基板として用いると、Ｓｉを用いた場合よりも比較的容易に結晶欠陥が少なく、表面が平坦な化合物半導体を形成することができるため、基板材料としては、化合物半導体が良く用いられている。   In these devices, in order to obtain good characteristics and reliability, it is important to have a technology that forms a compound semiconductor layer with few crystal defects and a flat surface on the substrate on which the device layer is to be formed. is there. When a compound semiconductor made of a single crystal such as GaAs or InP is used as a substrate material, a compound semiconductor with fewer crystal defects and a flat surface can be formed relatively easily than when Si is used. A compound semiconductor is often used as a substrate material.

しかしながら、化合物半導体を用いた場合、一般的に大型の単結晶を得るのが難しく、基板の大口径化がＳｉよりも難しい。またＧａＡｓやＩｎＰは、Ｓｉと比較すると、脆くて割れやすい上、価格の上でも高価である。   However, when a compound semiconductor is used, it is generally difficult to obtain a large single crystal, and it is more difficult to increase the substrate diameter than Si. GaAs and InP are more brittle and easier to break than Si, and are expensive in terms of price.

そこで、安価で割れにくく、大口径化が容易なＳｉ基板の上に化合物半導体層を形成した化合物半導体基板が注目されている。高品質の化合物半導体層をＳｉ基板上に形成することができれば、優れた特徴をもつ化合物半導体のデバイスと、Ｓｉ上の大規模な信号処理回路とを融合させたＯＥＩＣ（Ｏｐｔｏ−Ｅｌｅｃｔｒｏｎｉｃ Ｉｎｔｅｇｒａｔｅｄ Ｃｉｒｃｕｉｔ）などについても利用が可能となる。   Thus, a compound semiconductor substrate in which a compound semiconductor layer is formed on an Si substrate that is inexpensive, difficult to crack, and easy to increase in diameter has attracted attention. If a high-quality compound semiconductor layer can be formed on a Si substrate, an OEIC (Opto-Electronic Integrated Circuit) in which a compound semiconductor device having excellent characteristics and a large-scale signal processing circuit on Si are fused. Etc. can be used.

しかしながら、Ｓｉ基板上に化合物半導体層を形成する場合、格子定数や熱膨張係数が大きく異なるため、これに起因したミスフイットが生じてしまい、結晶欠陥が多く発生してしまう。例えば、ＳｉとＧａＡｓとの間では、格子定数は約４％の差が存在し、線膨張係数は３倍もの差がある。従って、Ｓｉ基板上に、結晶欠陥が少なく、表面が平坦なＧａＡｓを形成するのは容易ではない。   However, when the compound semiconductor layer is formed on the Si substrate, the lattice constant and the thermal expansion coefficient are greatly different, so that misfit due to this occurs, and many crystal defects are generated. For example, there is a difference of about 4% in lattice constant between Si and GaAs, and the linear expansion coefficient is 3 times different. Therefore, it is not easy to form GaAs with few crystal defects and a flat surface on the Si substrate.

Ｓｉ基板上に、結晶欠陥が少なく、表面が平坦な化合物半導体薄膜を形成するためには、Ｓｉ基板表面の自然酸化膜除去、表面処理の工程が重要となる。   In order to form a compound semiconductor thin film with few crystal defects and a flat surface on the Si substrate, a process of removing a natural oxide film on the surface of the Si substrate and a surface treatment are important.

例えば、特許文献１によると、Ｓｉ基板上にＡｓを含む化合物半導体を設けた化合物半導体基板において、Ｓｉ基板と、化合物半導体層との界面に、化合物半導体層よりもＡｓの濃度が高い物質を島状に存在させる方法が提案されている。   For example, according to Patent Document 1, in a compound semiconductor substrate in which a compound semiconductor containing As is provided on an Si substrate, a substance having a higher As concentration than the compound semiconductor layer is formed at the interface between the Si substrate and the compound semiconductor layer. The method of making it exist in a shape is proposed.

国際公開公報第２００９／０３５０７９号パンフレットInternational Publication No. 2009/035079 Pamphlet

特許文献１に開示された技術によれば、Ｓｉ基板上に結晶性が良く、且つ、表面が平坦なＧａＡｓを形成することができる。   According to the technique disclosed in Patent Document 1, GaAs having good crystallinity and a flat surface can be formed on a Si substrate.

しかしながら、Ｓｉ基板上に結晶性が良く、且つ、表面が平坦なＧａＡｓを形成するのは容易ではない。すなわち、Ａｓは蒸気圧が高く再蒸発しやすいため、Ｓｉ基板上にＧａＡｓを形成する場合、ＧａＡｓ表面の被覆性が十分でなくＧａＡｓは３次元成長してしまう。そのため、表面の平坦性を得にくい。   However, it is not easy to form GaAs with good crystallinity and a flat surface on the Si substrate. That is, As has a high vapor pressure and easily re-evaporates, when GaAs is formed on a Si substrate, the coverage of the GaAs surface is not sufficient and GaAs grows three-dimensionally. Therefore, it is difficult to obtain surface flatness.

十分な平坦性を得るためには、極端に過剰なＡｓ原料の供給が必要となる。極端に過剰なＡｓ原料の供給は、成長装置チャンバの真空度悪化及びそれに伴う真空ポンプへの負荷、或いは成長装置のチャンバの汚染、さらにはＡｓ原料の消費を著しく早めてしまう等の問題があり、改善が要求される。   In order to obtain sufficient flatness, an extremely excessive supply of As material is required. Supplying an extremely excessive amount of As raw material has problems such as deterioration of the vacuum degree of the growth apparatus chamber and the accompanying load on the vacuum pump, contamination of the growth apparatus chamber, and further rapid consumption of the As raw material. Improvement is required.

さらにＳｉ基板上に化合物半導体層としてＧａＡｓ層を形成した化合物半導体基板を用いた場合、化合物半導体基板のＧａＡｓ層上に形成されるデバイス層としての積層体の設計自由度は限定される。例えば、ＧａＡｓは２成分の化合物半導体なので組成率を制御することができない。そのため、ＧａＡｓ層を光デバイスの発光層、受光層に用いる場合、ＧａＡｓのエネルギーバンドギャップと異なる発光、吸収波長帯が必要となる場合に対応することができない。また、ＧａＡｓ層上にＧａＡｓと格子定数が大きく異なる材料を形成する場合は、格子不整合による欠陥が発生してしまい対応が困難である。   Further, when a compound semiconductor substrate in which a GaAs layer is formed as a compound semiconductor layer on a Si substrate is used, the degree of freedom in designing a stacked body as a device layer formed on the GaAs layer of the compound semiconductor substrate is limited. For example, since GaAs is a two-component compound semiconductor, the composition ratio cannot be controlled. Therefore, when the GaAs layer is used for the light emitting layer and the light receiving layer of the optical device, it cannot cope with a case where light emission and absorption wavelength bands different from the energy band gap of GaAs are required. Further, when a material having a lattice constant significantly different from that of GaAs is formed on the GaAs layer, defects due to lattice mismatch are generated and it is difficult to cope with it.

すなわち、ＧａＡｓを用いる場合、当然のことながらエネルギーバンドギャップ、格子定数の制約を受け、設計自由度に乏しい。   That is, when GaAs is used, it is naturally limited by the energy band gap and lattice constant, and the degree of freedom in design is poor.

一方、ＧａＡｓ1-yＳｂy層はＳｂ組成ｙを変えることで、所望のエネルギーバンドギャップ、格子定数の値を得ることができるので、その上に形成されるデバイス層としての積層体の設計自由度が広がるという観点から、化合物半導体基板の化合物半導体層として好ましい。 Meanwhile, GaAs 1-y Sb y layer is by changing the Sb composition y, the desired energy band gap, it is possible to obtain a value of the lattice constant, the design freedom of the stack as the device layer to be formed thereon From the viewpoint of widening the degree, it is preferable as the compound semiconductor layer of the compound semiconductor substrate.

しかし従来知られている方法では、Ｓｉ基板上に結晶性が良く、且つ、表面が平坦なＧａＡｓ1-yＳｂyを形成するのは容易ではない。すなわち、Ｓｂ組成ｙを増加させるにつれて結晶性が悪化してしまい、Ｓｂ組成がわずかに０．０５程度でも結晶性は相当悪化してしまう。また、Ｓｂ組成ｙをわずかに増加させる際、ＧａＡｓ1-yＳｂyを形成中にＧａ、Ａｓに加えて微量のＳｂ原料を供給するが、Ｓｉ基板上にＧａＡｓを形成する場合と同様に、ＧａＡｓ1-yＳｂyは３次元成長してしまい、表面の平坦性を十分に得ることができない。 However, in the conventionally known methods may crystallinity on the Si substrate, and the surface it is not easy to form a flat GaAs 1-y Sb y. That is, as the Sb composition y is increased, the crystallinity deteriorates, and even if the Sb composition is only about 0.05, the crystallinity is considerably deteriorated. Further, when increasing the Sb composition y slightly, as if Ga during formation of GaAs 1-y Sb y, supplies Sb raw material in addition to the As traces, forming a GaAs on a Si substrate, GaAs 1-y Sb y is would grow three-dimensionally, it is impossible to obtain a flatness of the surface sufficiently.

すなわち本発明は、Ｓｉ基板上に、結晶性が良く、且つ、表面の平坦性に優れたＧａＡｓＳｂを化合物半導体層として備えた化合物半導体基板を容易に実現可能な製造方法を提供することを目的とする。   That is, an object of the present invention is to provide a manufacturing method capable of easily realizing a compound semiconductor substrate having GaAsSb as a compound semiconductor layer having good crystallinity and excellent surface flatness on a Si substrate. To do.

本発明は、Ｓｉ基板上に第１の化合物半導体層を形成する工程と、第１の化合物半導体層上に、第１の化合物半導体層を形成するときよりも高温で、第２の化合物半導体層を形成する工程とを備える化合物半導体基板の製造方法であって、第１の化合物半導体層は、ＧａＡｓ1-xＳｂx（０≦ｘ≦０．１）層であり、第２の化合物半導体層は、ＧａＡｓ1-yＳｂy（０＜ｙ≦０．１）層であり、第２の化合物半導体層を形成する工程は、Ｇａ原料とＡｓ原料とＳｂ原料とを同時に照射する工程であり、第２の化合物半導体層を形成する工程において、Ｓｂ原料の分子線強度と、第２の化合物半導体層の形成速度が１時間当たり１μｍとなるために必要なＧａ原料の分子線強度との比が１以上であることを特徴とする。 The present invention includes a step of forming a first compound semiconductor layer on a Si substrate, and a second compound semiconductor layer at a higher temperature than when forming the first compound semiconductor layer on the first compound semiconductor layer. The first compound semiconductor layer is a GaAs 1-x Sb x (0 ≦ x ≦ 0.1) layer, and the second compound semiconductor layer is GaAs 1-y Sb y (0 <y ≦ 0.1) layer, forming a second compound semiconductor layer is a step of irradiating the Ga raw material and as raw material and Sb raw material and at the same time, In the step of forming the second compound semiconductor layer, the ratio between the molecular beam intensity of the Sb material and the molecular beam intensity of the Ga material necessary for the formation rate of the second compound semiconductor layer to be 1 μm per hour is It is 1 or more.

本発明の一実施形態において、第１の化合物半導体層は、ＧａＡｓ層であることを特徴とする。   In one embodiment of the present invention, the first compound semiconductor layer is a GaAs layer.

本発明の一実施形態において、第２の化合物半導体層の形成速度は、１時間当たり０．０５μｍ以上０．３μｍ以下であることを特徴とする。   In one embodiment of the present invention, the formation rate of the second compound semiconductor layer is 0.05 μm or more and 0.3 μm or less per hour.

本発明の一実施形態において、Ａｓ原料は、Ａｓ2分子であることを特徴とする。 In one embodiment of the present invention, the As raw material is an As 2 molecule.

本発明の一実施形態において、Ａｓ原料は、Ａｓ4分子をクラッキングすることにより生成されることを特徴とする。 In one embodiment of the present invention, the As raw material is produced by cracking As 4 molecules.

本発明は、Ｓｉ基板と、Ｓｉ基板上に形成された、第１の化合物半導体層と、第１の化合物半導体層上に形成された、第２の化合物半導体層とを備えた化合物半導体基板であって、第１の化合物半導体層は、ＧａＡｓ1-xＳｂx（０≦ｘ≦０．１）層であり、第２の化合物半導体層は、ＧａＡｓ1-yＳｂy（０＜ｙ≦０．１）層であり、第２の化合物半導体層の、Ｓｉ基板の面方位と同じ面に対応するＸ線回折ピークのロッキングカーブの、ＦＷＨＭ値は、７００秒以下であり、且つ第２の化合物半導体層の１０μｍ四方の領域における、表面粗さの二乗平均値Ｒｒｍｓ値は、３ｎｍ以下であることを特徴とする。 The present invention is a compound semiconductor substrate comprising a Si substrate, a first compound semiconductor layer formed on the Si substrate, and a second compound semiconductor layer formed on the first compound semiconductor layer. there, the first compound semiconductor layer, a GaAs 1-x Sb x (0 ≦ x ≦ 0.1) layer, the second compound semiconductor layer, GaAs 1-y Sb y ( 0 <y ≦ 0 .1) The FWHM value of the rocking curve of the X-ray diffraction peak corresponding to the same plane as the plane direction of the Si substrate of the second compound semiconductor layer is 700 seconds or less, and the second compound The root mean square value Rrms value of the surface roughness in a 10 μm square region of the semiconductor layer is 3 nm or less.

本発明の一実施形態において、第１の化合物半導体層は、ＧａＡｓ層であり、第２の化合物半導体層の、Ｓｉ基板の面方位と同じ面に対応するＸ線回折ピークのロッキングカーブの、ＦＷＨＭ値は、６００秒以下であり、且つ第２の化合物半導体層の１０μｍ四方の領域における、表面粗さの二乗平均値Ｒｒｍｓ値は、３ｎｍ以下であることを特徴とする。   In one embodiment of the present invention, the first compound semiconductor layer is a GaAs layer, and the FWHM of the rocking curve of the X-ray diffraction peak corresponding to the same plane as the plane orientation of the Si substrate of the second compound semiconductor layer. The value is 600 seconds or less, and the root mean square value Rrms value of the surface roughness in the 10 μm square region of the second compound semiconductor layer is 3 nm or less.

本発明の一実施形態において、第１の化合物半導体層は、ＧａＡｓ層であり、第２の化合物半導体層の、Ｓｉ基板の面方位と同じ面に対応するＸ線回折ピークのロッキングカーブの、ＦＷＨＭ値は、５００秒以下であり、且つ第２の化合物半導体層の１０μｍ四方の領域における、表面粗さの二乗平均値Ｒｒｍｓ値は、２ｎｍ以下であることを特徴とする。   In one embodiment of the present invention, the first compound semiconductor layer is a GaAs layer, and the FWHM of the rocking curve of the X-ray diffraction peak corresponding to the same plane as the plane orientation of the Si substrate of the second compound semiconductor layer. The value is 500 seconds or less, and the root mean square value Rrms value of the surface roughness in a 10 μm square region of the second compound semiconductor layer is 2 nm or less.

本発明の化合物半導体基板の製造方法によれば、Ｓｉ基板上に、結晶性が良く、且つ、表面の平坦性に優れたＧａＡｓＳｂ層を含む化合物半導体層を備えた化合物半導体基板を容易に実現することができる。   According to the method for manufacturing a compound semiconductor substrate of the present invention, a compound semiconductor substrate including a compound semiconductor layer including a GaAsSb layer having good crystallinity and excellent surface flatness on a Si substrate is easily realized. be able to.

本発明による化合物半導体基板の断面図である。It is sectional drawing of the compound semiconductor substrate by this invention. Ｓｂ分子線強度とＧａＡｓＳｂ表面粗さの二乗平均値Ｒｒｍｓ値との関係を示すグラフである。It is a graph which shows the relationship between the Sb molecular beam intensity and the root mean square value Rrms value of GaAsSb surface roughness.

図１は、本発明による化合物半導体基板１０の断面図である。Ｓｉ基板１０１の上に、第１の化合物半導体層１０２、第２の化合物半導体層１０３が順次積層されている。   FIG. 1 is a cross-sectional view of a compound semiconductor substrate 10 according to the present invention. On the Si substrate 101, a first compound semiconductor layer 102 and a second compound semiconductor layer 103 are sequentially stacked.

この化合物半導体基板は、各種の成膜方法を用いて形成される。例えば、分子線エピタキシー（ＭＢＥ）法や有機金属気相エピタキシー（ＭＯＶＰＥ）法などは好ましい方法である。これらの方法を用いて、化合物半導体基板を形成する。   This compound semiconductor substrate is formed using various film forming methods. For example, a molecular beam epitaxy (MBE) method or a metal organic vapor phase epitaxy (MOVPE) method is a preferable method. Using these methods, a compound semiconductor substrate is formed.

本発明により形成した化合物半導体基板は、基板を形成した成膜装置から一旦、大気中に取り出しても良い。大気中に取り出した基板は、そのままエッチング、電極形成するなどして半導体デバイスを作製しても良いし、基板を形成したのと同一の成膜装置、或いは別の成膜装置に再度導入し、基板上に新たにデバイス層としての化合物半導体の積層体を形成しても良い。   The compound semiconductor substrate formed according to the present invention may be temporarily taken out into the atmosphere from the film forming apparatus on which the substrate is formed. The substrate taken out into the atmosphere may be used as it is to form a semiconductor device by etching, electrode formation, etc., or it may be introduced again into the same film forming apparatus that formed the substrate, or another film forming apparatus, A compound semiconductor laminate as a device layer may be newly formed on the substrate.

また、本発明により化合物半導体基板を形成した後、基板を形成したのと同一の成膜装置において引き続き、或いは真空を保持したまま別の成膜装置に搬送した後、基板上に新たに化合物半導体の積層体を形成しても良い。   In addition, after the compound semiconductor substrate is formed according to the present invention, the compound semiconductor substrate is newly formed on the substrate after it is continuously transferred to another film forming apparatus while maintaining the vacuum in the same film forming apparatus in which the substrate is formed. A laminate of the above may be formed.

本発明により形成した化合物半導体基板上に、新たに形成する化合物半導体の積層体に用いる材料は、特に制限されない。例えば、ＧａＡｓ、ＩｎＡｓ、ＩｎＳｂ、ＩｎＧａＰなどが挙げられる。   The material used for the stack of compound semiconductors newly formed on the compound semiconductor substrate formed according to the present invention is not particularly limited. For example, GaAs, InAs, InSb, InGaP, and the like can be given.

以下に図１に示す各層の説明をする。
［Ｓｉ基板］
Ｓｉ基板は、一般に単結晶を成長できるものであれば特に制限されず、Ｓｉの単結晶基板が好ましく用いられる。単結晶基板は、半絶縁性基板であっても良いし、ドナー不純物やアクセプタ不純物によって、ｎ型やｐ型にドーピングされた導電性基板であっても良い。 Hereinafter, each layer shown in FIG. 1 will be described.
[Si substrate]
The Si substrate is not particularly limited as long as it can generally grow a single crystal, and a Si single crystal substrate is preferably used. The single crystal substrate may be a semi-insulating substrate or a conductive substrate doped n-type or p-type with donor impurities or acceptor impurities.

単結晶基板の面方位は特に制限はないが、（１００）、（１１１）、（１１０）等が好ましい。また、これらの面方位に対して１°から５°傾けた面方位を用いることもある。   The plane orientation of the single crystal substrate is not particularly limited, but (100), (111), (110) and the like are preferable. Further, a plane orientation inclined by 1 ° to 5 ° with respect to these plane orientations may be used.

基板表面は、真空中で加熱して酸化膜除去しても良いし、有機物、金属等の汚染物質を除去した後、濃度１．０ｗｔ％のフッ化水素水溶液を用いて表面の酸化膜を除去して、水素終端処理を行っても良い。   The substrate surface may be heated in vacuum to remove the oxide film, or after removing contaminants such as organic substances and metals, the surface oxide film is removed using a hydrogen fluoride aqueous solution having a concentration of 1.0 wt%. Then, hydrogen termination treatment may be performed.

［第１の化合物半導体層］
本実施形態において、第１の化合物半導体層はＧａＡｓ1-xＳｂx（０≦ｘ≦１）層である。 [First compound semiconductor layer]
In the present embodiment, the first compound semiconductor layer is a GaAs 1-x Sb x (0 ≦ x ≦ 1) layer.

第１の化合物半導体層は、結晶性が良く、且つ、表面の平坦性に優れた第２の化合物半導体層を形成するための、バッファ層としての役割を果たす。当然のことながら、バッファ層としての第１の化合物半導体層自体も、結晶性が良く、且つ、表面の平坦性も優れていることが好ましい。   The first compound semiconductor layer serves as a buffer layer for forming the second compound semiconductor layer having good crystallinity and excellent surface flatness. As a matter of course, it is preferable that the first compound semiconductor layer itself as the buffer layer also has good crystallinity and excellent surface flatness.

第１の化合物半導体層は、高温で形成すると、表面の凹凸が激しくなり、十分な平坦性を確保することができなくなるため、比較的低温で形成することが多い。形成時の温度は、結晶性の観点から１５０度以上であることが好ましい。また、形成時の温度は、平坦性確保の観点から３５０度以下であることが好ましい。   When the first compound semiconductor layer is formed at a high temperature, the unevenness of the surface becomes severe and sufficient flatness cannot be ensured. Therefore, the first compound semiconductor layer is often formed at a relatively low temperature. The temperature during formation is preferably 150 ° C. or more from the viewpoint of crystallinity. Moreover, it is preferable that the temperature at the time of formation is 350 degrees or less from a viewpoint of ensuring flatness.

第１の化合物半導体層は、低温で形成した場合、表面の平坦性は十分であるが、結晶性は必ずしも良くなくなってしまう。但し、第１の化合物半導体層を形成後に、第１の化合物半導体層の温度を上昇させ保持すると、アニール効果によって結晶性、表面の平坦性いずれも改善することができる。例えば、低温で第１の化合物半導体層を形成した後、温度をアニール効果が発現する程度に上昇させて保持した後、高温で第１の化合物半導体層上に第２の化合物半導体層を形成することが多い。   When the first compound semiconductor layer is formed at a low temperature, the flatness of the surface is sufficient, but the crystallinity is not always good. However, if the temperature of the first compound semiconductor layer is raised and maintained after the first compound semiconductor layer is formed, both the crystallinity and the surface flatness can be improved by the annealing effect. For example, after the first compound semiconductor layer is formed at a low temperature, the temperature is raised and maintained so as to exhibit the annealing effect, and then the second compound semiconductor layer is formed on the first compound semiconductor layer at a high temperature. There are many cases.

第１の化合物半導体層の膜厚は、結晶性の確保及び被覆性の観点から５ｎｍ以上であることが好ましい。また、第１の化合物半導体層の膜厚は、結晶性やアニール効果による改善効果の観点から５０ｎｍ以下であることが好ましい。   The film thickness of the first compound semiconductor layer is preferably 5 nm or more from the viewpoint of ensuring crystallinity and covering properties. Further, the film thickness of the first compound semiconductor layer is preferably 50 nm or less from the viewpoint of the improvement effect due to the crystallinity and the annealing effect.

第１の化合物半導体層のＳｂ組成ｘは、結晶性の観点から、０以上０．１以下が好ましい。特に、ｘ＝０、すなわち、第１の化合物半導体層がＧａＡｓのとき、結晶性が非常に良く好ましい。   The Sb composition x of the first compound semiconductor layer is preferably 0 or more and 0.1 or less from the viewpoint of crystallinity. In particular, when x = 0, that is, when the first compound semiconductor layer is GaAs, the crystallinity is very good and preferable.

第１の化合物半導体層は、ノンドープでも良いし、ドナー不純物やアクセプタ不純物によって、ｎ型やｐ型にドーピングしても良い。   The first compound semiconductor layer may be non-doped or may be doped n-type or p-type with a donor impurity or an acceptor impurity.

また、有機物、金属等の汚染物質を除去した後、濃度１．０ｗｔ％のフッ化水素水溶液を用いて表面の酸化膜を除去して、水素終端処理を行ったＳｉ基板と、第１の化合物半導体層との間に、Ａｓを先行照射させることで、第１の化合物半導体層よりもＡｓ濃度の高い物質を島状に存在させると、結晶性が良く、優れた表面の平坦性が得られるので好ましい。   In addition, after removing contaminants such as organic matter and metal, the surface oxide film is removed using a hydrogen fluoride aqueous solution having a concentration of 1.0 wt%, and a hydrogen-terminated Si substrate and the first compound When a substance having an As concentration higher than that of the first compound semiconductor layer is present in an island shape by pre-irradiating As between the semiconductor layer and the semiconductor layer, crystallinity is good and excellent surface flatness is obtained. Therefore, it is preferable.

［第２の化合物半導体層］
本実施形態において、第２の化合物半導体層は、ＧａＡｓ1-yＳｂy（０＜ｙ≦１）層である。 [Second Compound Semiconductor Layer]
In the present embodiment, the second compound semiconductor layer is GaAs 1-y Sb y (0 <y ≦ 1) layer.

第２の化合物半導体層は、第１の化合物半導体層上にＧａ、Ａｓ、Ｓｂ原料を同時照射することで形成される。   The second compound semiconductor layer is formed by simultaneously irradiating Ga, As, and Sb raw materials on the first compound semiconductor layer.

図２は、基板温度を５８０℃とし、ＧａとＡｓ原料の分子線強度をそれぞれ一定にした条件下において、Ｓｂ分子線強度を変化させながら第２の化合物半導体層を形成したときの、Ｓｂ分子線強度と、第２の化合物半導体層の表面粗さの二乗平均値Ｒｒｍｓとの関係を示したグラフである。   FIG. 2 shows the Sb molecules when the second compound semiconductor layer is formed while changing the Sb molecular beam intensity under the condition that the substrate temperature is 580 ° C. and the molecular beam intensities of the Ga and As raw materials are constant. It is the graph which showed the relationship between line strength and the root mean square value Rrms of the surface roughness of a 2nd compound semiconductor layer.

Ｓｂの分子線強度が７×１０-7Ｔｏｒｒ以上で、Ｒｒｍｓが急激に減少し、優れた表面の平坦性が得られることが理解される。Ｓｂの分子線強度が７×１０-7Ｔｏｒｒ以上であるということは、Ｓｂ原料の分子線強度と、第２の化合物半導体層の形成速度が１時間当たり１μｍとなるために必要なＧａ原料の分子線強度との比とで言い換えると、その比が１以上であることに相当している。 It is understood that when the molecular beam intensity of Sb is 7 × 10 −7 Torr or more, Rrms decreases rapidly and excellent surface flatness is obtained. That the molecular beam intensity of Sb is 7 × 10 −7 Torr or more means that the molecular beam intensity of the Sb material and the formation rate of the second compound semiconductor layer are 1 μm per hour. In other words, the ratio to the molecular beam intensity corresponds to a ratio of 1 or more.

すなわち、優れた表面の平坦性を得るためには、Ｓｂ原料の分子線強度と、第２の化合物半導体層の形成速度が１時間当たり１μｍとなるために必要なＧａ原料の分子線強度との比（以下、換算Ｓｂ／Ｇａ分子線強度比と称することがある）が１以上であることが好ましい。   That is, in order to obtain excellent surface flatness, the molecular beam intensity of the Sb raw material and the molecular beam intensity of the Ga raw material necessary for the formation rate of the second compound semiconductor layer to be 1 μm per hour The ratio (hereinafter sometimes referred to as a converted Sb / Ga molecular beam intensity ratio) is preferably 1 or more.

換算Ｓｂ／Ｇａ分子線強度比が１以上であるような、Ｓｂ原料の分子線強度は、例えば、ＧａＡｓ基板上にＩｎＳｂ、ＧａＳｂ、ＡｌＳｂ、ＡｌＧａＳｂなどの、Ｖ族元素がＳｂのみからなる半導体薄膜を形成する場合、結晶性が良く、優れた平坦性を容易に得るのに、十分なＳｂ原料の分子線強度である。   The molecular beam intensity of the Sb raw material having a converted Sb / Ga molecular beam intensity ratio of 1 or more is, for example, a semiconductor thin film in which a group V element such as InSb, GaSb, AlSb, and AlGaSb is made of only Sb on a GaAs substrate. In the case of forming, the molecular beam intensity of the Sb raw material is sufficient to easily obtain crystallinity and excellent flatness.

第２の化合物半導体層のＳｂ組成ｙは、結晶性確保の観点から０．１以下が好ましい。換算Ｓｂ／Ｇａ分子線強度比が１以上であり、且つ、Ａｓ原料がＡｓ4分子の場合、Ａｓ4分子は反応性や付着係数がＳｂに比べて低いため、Ｓｂ組成ｙは大きくなってしまう場合がある。そのため、Ａｓ原料は反応性や付着係数が高いＡｓ2分子であることが好ましい。Ａｓ2分子は反応性や付着係数が高いため、Ｓｂ組成ｙはそれほど大きくならず、Ｓｂ組成０．１以下の第２の化合物半導体を容易に形成することができる。反応性や付着係数の高いＡｓ2分子は、例えばＡｓ4分子を加熱等によりクラッキングすることにより生成することが可能である。 The Sb composition y of the second compound semiconductor layer is preferably 0.1 or less from the viewpoint of ensuring crystallinity. When the converted Sb / Ga molecular beam intensity ratio is 1 or more and the As raw material is As 4 molecules, the As 4 molecules have a lower reactivity and adhesion coefficient than Sb, so the Sb composition y becomes large. There is a case. Therefore, the As raw material is preferably an As 2 molecule having high reactivity and adhesion coefficient. Since the As 2 molecule has a high reactivity and adhesion coefficient, the Sb composition y does not become so large, and a second compound semiconductor having an Sb composition of 0.1 or less can be easily formed. As 2 molecules having high reactivity and adhesion coefficient can be generated, for example, by cracking As 4 molecules by heating or the like.

第２の化合物半導体層の形成時の温度は、結晶性及び表面平坦性の観点から、５５０度以上が好ましい。また、第２の化合物半導体層の形成時の温度は、Ｖ族元素であるＡｓ，Ｓｂの再蒸発を防止して、結晶性及び表面平坦性を確保する観点から７００度以下であることが好ましい。   The temperature at the time of forming the second compound semiconductor layer is preferably 550 ° C. or higher from the viewpoint of crystallinity and surface flatness. Further, the temperature at the time of forming the second compound semiconductor layer is preferably 700 ° C. or less from the viewpoint of preventing re-evaporation of the group V elements As and Sb and ensuring crystallinity and surface flatness. .

第２の化合物半導体層は、ノンドープでも良いし、ドナー不純物やアクセプタ不純物によって、ｎ型やｐ型にドーピングしても良い。   The second compound semiconductor layer may be non-doped or may be doped n-type or p-type with a donor impurity or an acceptor impurity.

第２の化合物半導体層の膜厚は、十分な結晶性確保の観点から０．３μｍ以下が好ましい。また、第２の化合物半導体層の膜厚は、形成時間の観点から５μｍ以下が好ましい。   The film thickness of the second compound semiconductor layer is preferably 0.3 μm or less from the viewpoint of ensuring sufficient crystallinity. The film thickness of the second compound semiconductor layer is preferably 5 μm or less from the viewpoint of formation time.

第２の化合物半導体層の形成速度は、結晶性確保の観点から１．５μｍ／ｈ以下が好ましく、０．３μｍ／ｈ以下がより好ましい。また、第２の化合物半導体層の形成速度は、形成時間の観点から、０．０５μｍ／ｈ以上が好ましく、０．１μｍ／ｈ以上がより好ましい。第２の化合物半導体層の形成速度は、所望の結晶性、形成時間に応じて、適宜決めることができる。   The formation rate of the second compound semiconductor layer is preferably 1.5 μm / h or less, and more preferably 0.3 μm / h or less from the viewpoint of ensuring crystallinity. In addition, the formation rate of the second compound semiconductor layer is preferably 0.05 μm / h or more, and more preferably 0.1 μm / h or more from the viewpoint of formation time. The formation rate of the second compound semiconductor layer can be appropriately determined according to desired crystallinity and formation time.

以下、本発明を実施例に基づいて詳細に説明するが、本発明は、下記実施例に限定されるものではなく、その発明の主旨を逸脱しない範囲において、種々変更可能であることは言うまでもない。   Hereinafter, the present invention will be described in detail based on examples, but the present invention is not limited to the following examples, and it is needless to say that various modifications can be made without departing from the spirit of the invention. .

［実施例１］
まず、Ｓｉ（１１１）基板の表面の有機物、金属等の汚染物質を除去した後、濃度１．０ｗｔ％のフッ化水素水溶液を用いて表面の酸化膜を除去して、水素終端処理を行った。 [Example 1]
First, after removing contaminants such as organic substances and metals on the surface of the Si (111) substrate, the surface oxide film was removed using a hydrogen fluoride aqueous solution having a concentration of 1.0 wt%, and hydrogen termination treatment was performed. .

これを直ちにＭＢＥ装置内に導入し、１×１０-6Ｔｏｒｒ（１．３３３×１０-6Ｐａ）以下の真空中で、基板温度が３００℃になるまで加熱し、温度が一定になったところでＡｓを照射した。 This was immediately introduced into the MBE apparatus, heated in a vacuum of 1 × 10 −6 Torr (1.333 × 10 −6 Pa) or less until the substrate temperature reached 300 ° C., and when the temperature became constant As was irradiated.

引き続き、分子線強度が７×１０-8ＴｏｒｒのＧａと、分子線強度が３×１０-5ＴｏｒｒのＡｓ4分子をクラッキングすなわち加熱して生成したＡｓ2分子と、分子線強度が１．７６×１０-6ＴｏｒｒのＳｂとを同時に照射することにより、膜厚２０ｎｍの第１の化合物半導体層（ＧａＡｓ1-xＳｂx層）を、１時間当たり０．１μｍの形成速度で形成した。 Subsequently, an As 2 molecule generated by cracking, ie heating, Ga having a molecular beam intensity of 7 × 10 −8 Torr and an As 4 molecule having a molecular beam intensity of 3 × 10 −5 Torr, and a molecular beam intensity of 1.76. A first compound semiconductor layer (GaAs 1-x Sb x layer) having a thickness of 20 nm was formed at a formation rate of 0.1 μm per hour by simultaneously irradiating Sb of × 10 −6 Torr.

その後、基板温度が６６０℃になるまで加熱し、温度が一定になったところで、分子線強度が７×１０-7ＴｏｒｒのＧａと、分子線強度が３×１０-5ＴｏｒｒのＡｓ4分子をクラッキングすなわち加熱して生成したＡｓ2分子と、分子線強度が１．７６×１０-6ＴｏｒｒのＳｂとを同時に照射することにより、膜厚９８０ｎｍの第２の化合物半導体層（ＧａＡｓ1-yＳｂy層）を、１時間当たり１μｍの形成速度で形成した。このとき、Ｓｂ原料の分子線強度と、第２の化合物半導体層の形成速度が１時間当たり１μｍとなるために必要なＧａ原料の分子線強度との比（換算Ｓｂ／Ｇａ分子線強度比）は２．５１である。 Thereafter, the substrate temperature is heated to 660 ° C., and when the temperature becomes constant, Ga having a molecular beam intensity of 7 × 10 −7 Torr and As 4 molecules having a molecular beam intensity of 3 × 10 −5 Torr are obtained. By simultaneously irradiating cracked or heated As 2 molecules and Sb having a molecular beam intensity of 1.76 × 10 −6 Torr, a second compound semiconductor layer having a thickness of 980 nm (GaAs 1-y Sb y layer) was formed at a formation rate of 1 μm per hour. At this time, the ratio between the molecular beam intensity of the Sb raw material and the molecular beam intensity of the Ga raw material necessary for the formation rate of the second compound semiconductor layer to be 1 μm per hour (converted Sb / Ga molecular beam intensity ratio) Is 2.51.

第２の化合物半導体層の（１１１）面に対応するＸ線回折ピークをＸ線回折装置（ＰＨＩＬＩＰＳ社製、ＰＷ１８３０）を用いて解析したところ、Ｓｂ組成ｙは０．０３２であった。また、第２の化合物半導体層の、（１１１）面に対応するＸ線回折ピークのロッキングカーブのＦＷＨＭ値は６１０秒であった。さらに、第２の化合物半導体層の１０μｍ四方の領域における表面粗さの二乗平均値Ｒｒｍｓを原子間力顕微鏡（ＡＦＭ）で評価したところ、１．８ｎｍであった。   When the X-ray diffraction peak corresponding to the (111) plane of the second compound semiconductor layer was analyzed using an X-ray diffraction apparatus (PW1830, manufactured by PHILIPS), the Sb composition y was 0.032. Further, the FWHM value of the rocking curve of the X-ray diffraction peak corresponding to the (111) plane of the second compound semiconductor layer was 610 seconds. Furthermore, when the root mean square value Rrms of the surface roughness in the 10 μm square region of the second compound semiconductor layer was evaluated with an atomic force microscope (AFM), it was 1.8 nm.

すなわち、第２の化合物半導体層の、Ｓｉ基板の面方位と同じ面に対応するＸ線回折ピークのロッキングカーブのＦＷＨＭ値が７００秒以下であり、且つ、第２の化合物半導体層の１０μｍ四方の領域における表面粗さの二乗平均値Ｒｒｍｓが３ｎｍ以下である化合物半導体基板を実現した。   In other words, the FWHM value of the rocking curve of the X-ray diffraction peak corresponding to the same plane as the plane direction of the Si substrate of the second compound semiconductor layer is 700 seconds or less, and 10 μm square of the second compound semiconductor layer A compound semiconductor substrate in which the root mean square value Rrms of the surface roughness in the region was 3 nm or less was realized.

［実施例２］
まず、実施例１と同様に、Ｓｉ（１１１）基板の表面の有機物、金属等の汚染物質を除去した後、濃度１．０ｗｔ％のフッ化水素水溶液を用いて表面の酸化膜を除去して、水素終端処理を行った。 [Example 2]
First, as in Example 1, after removing contaminants such as organic substances and metals on the surface of the Si (111) substrate, the surface oxide film was removed using a hydrogen fluoride aqueous solution having a concentration of 1.0 wt%. Then, hydrogen termination treatment was performed.

これを直ちにＭＢＥ装置内に導入し、１×１０-6Ｔｏｒｒ（１．３３３×１０-6Ｐａ）以下の真空中で、基板温度が３００℃になるまで加熱し、温度が一定になったところでＡｓを照射した。 This was immediately introduced into the MBE apparatus, heated in a vacuum of 1 × 10 −6 Torr (1.333 × 10 −6 Pa) or less until the substrate temperature reached 300 ° C., and when the temperature became constant As was irradiated.

引き続き、分子線強度が７×１０-8ＴｏｒｒのＧａと、分子線強度が３×１０-5ＴｏｒｒのＡｓ4分子をクラッキングすなわち加熱して生成したＡｓ2分子と、分子線強度が２．８×１０-6ＴｏｒｒのＳｂとを同時に照射することにより、膜厚２０ｎｍの第１の化合物半導体層を、１時間当たり０．１μｍの形成速度で形成した。 Subsequently, an As 2 molecule generated by cracking, ie heating, Ga having a molecular beam intensity of 7 × 10 −8 Torr and an As 4 molecule having a molecular beam intensity of 3 × 10 −5 Torr, and a molecular beam intensity of 2.8. By simultaneously irradiating Sb of × 10 −6 Torr, a first compound semiconductor layer having a thickness of 20 nm was formed at a formation rate of 0.1 μm per hour.

その後、基板温度が６６０℃になるまで加熱し、温度が一定になったところで、分子線強度が７×１０-7ＴｏｒｒのＧａと、分子線強度が３×１０-5ＴｏｒｒのＡｓ4分子をクラッキングすなわち加熱して生成したＡｓ2分子と、分子線強度が２．８×１０-6ＴｏｒｒのＳｂとを同時に照射することにより、膜厚９８０ｎｍの第２の化合物半導体層を、１時間当たり１μｍの形成速度で形成した。このとき、換算Ｓｂ／Ｇａ分子線強度比は４である。 Thereafter, the substrate temperature is heated to 660 ° C., and when the temperature becomes constant, Ga having a molecular beam intensity of 7 × 10 −7 Torr and As 4 molecules having a molecular beam intensity of 3 × 10 −5 Torr are obtained. By simultaneously irradiating cracked or heated As 2 molecules generated by heating and Sb having a molecular beam intensity of 2.8 × 10 −6 Torr, a second compound semiconductor layer having a thickness of 980 nm is formed at 1 μm per hour. Formed at a rate of At this time, the converted Sb / Ga molecular beam intensity ratio is 4.

第２の化合物半導体層の（１１１）面に対応するＸ線回折ピークを解析したところ、Ｓｂ組成ｙは０．０５２であった。また、第２の化合物半導体層の、（１１１）面に対応するＸ線回折ピークのロッキングカーブの、ＦＷＨＭ値は６６０秒であった。さらに、第２の化合物半導体層の１０μｍ四方の領域における、表面粗さの二乗平均値、Ｒｒｍｓ値を原子間力顕微鏡（ＡＦＭ）で評価したところ、１．６ｎｍであった。   When the X-ray diffraction peak corresponding to the (111) plane of the second compound semiconductor layer was analyzed, the Sb composition y was 0.052. Further, the FWHM value of the rocking curve of the X-ray diffraction peak corresponding to the (111) plane of the second compound semiconductor layer was 660 seconds. Furthermore, when the mean square value of the surface roughness and the Rrms value in a 10 μm square region of the second compound semiconductor layer were evaluated by an atomic force microscope (AFM), it was 1.6 nm.

すなわち、第２の化合物半導体層の、Ｓｉ基板の面方位と同じ面に対応するＸ線回折ピークのロッキングカーブのＦＷＨＭ値が７００秒以下であり、且つ、第２の化合物半導体層の１０μｍ四方の領域における、表面粗さの二乗平均値Ｒｒｍｓが３ｎｍ以下である化合物半導体基板を実現した。   In other words, the FWHM value of the rocking curve of the X-ray diffraction peak corresponding to the same plane as the plane direction of the Si substrate of the second compound semiconductor layer is 700 seconds or less, and 10 μm square of the second compound semiconductor layer A compound semiconductor substrate in which the root mean square value Rrms of the surface roughness in the region was 3 nm or less was realized.

［実施例３］
まず、実施例１と同様に、Ｓｉ（１１１）基板の表面の有機物、金属等の汚染物質を除去した後、濃度１．０ｗｔ％のフッ化水素水溶液を用いて表面の酸化膜を除去して、水素終端処理を行った。 [Example 3]
First, as in Example 1, after removing contaminants such as organic substances and metals on the surface of the Si (111) substrate, the surface oxide film was removed using a hydrogen fluoride aqueous solution having a concentration of 1.0 wt%. Then, hydrogen termination treatment was performed.

これを直ちにＭＢＥ装置内に導入し、１×１０-6Ｔｏｒｒ（１．３３３×１０-6Ｐａ）以下の真空中で、基板温度が３００℃になるまで加熱し、温度が一定になったところでＡｓを照射した。 This was immediately introduced into the MBE apparatus, heated in a vacuum of 1 × 10 −6 Torr (1.333 × 10 −6 Pa) or less until the substrate temperature reached 300 ° C., and when the temperature became constant As was irradiated.

引き続き、分子線強度が７×１０-8ＴｏｒｒのＧａと、分子線強度が３×１０-5ＴｏｒｒのＡｓ4分子をクラッキングすなわち加熱して生成したＡｓ2分子とを同時に照射することにより、膜厚２０ｎｍの第１の化合物半導体層であるＧａＡｓ層を、１時間当たり０．１μｍの形成速度で形成した。 Subsequently, the film is irradiated by simultaneously irradiating Ga having a molecular beam intensity of 7 × 10 −8 Torr and As 2 molecules generated by cracking, ie heating, As 4 molecules having a molecular beam intensity of 3 × 10 −5 Torr. A GaAs layer, which is a first compound semiconductor layer having a thickness of 20 nm, was formed at a formation rate of 0.1 μm per hour.

その後、基板温度が６６０℃になるまで加熱し、温度が一定になったところで、分子線強度が７×１０-7ＴｏｒｒのＧａと、分子線強度が３×１０-5ＴｏｒｒのＡｓ4分子をクラッキングすなわち加熱して生成したＡｓ2分子と、分子線強度が１．６６×１０-6ＴｏｒｒのＳｂとを同時に照射することにより、膜厚９８０ｎｍの第２の化合物半導体層を、１時間当たり１μｍの形成速度で形成した。このとき、換算Ｓｂ／Ｇａ分子線強度比は２．３７である。 Thereafter, the substrate temperature is heated to 660 ° C., and when the temperature becomes constant, Ga having a molecular beam intensity of 7 × 10 −7 Torr and As 4 molecules having a molecular beam intensity of 3 × 10 −5 Torr are obtained. By simultaneously irradiating cracked or heated As 2 molecules and Sb having a molecular beam intensity of 1.66 × 10 −6 Torr, the second compound semiconductor layer having a thickness of 980 nm is 1 μm per hour. Formed at a rate of At this time, the converted Sb / Ga molecular beam intensity ratio is 2.37.

第２の化合物半導体層の（１１１）面に対応するＸ線回折ピークを解析したところ、Ｓｂ組成ｙは０．０３３であった。また、第２の化合物半導体層の、（１１１）面に対応するＸ線回折ピークのロッキングカーブのＦＷＨＭ値は５５０秒であった。さらに、第２の化合物半導体層の１０μｍ四方の領域における、表面粗さの二乗平均値、Ｒｒｍｓ値を原子間力顕微鏡（ＡＦＭ）で評価したところ、２．２ｎｍであった。   When the X-ray diffraction peak corresponding to the (111) plane of the second compound semiconductor layer was analyzed, the Sb composition y was 0.033. Further, the FWHM value of the rocking curve of the X-ray diffraction peak corresponding to the (111) plane of the second compound semiconductor layer was 550 seconds. Furthermore, when the mean square value of surface roughness and the Rrms value in a 10 μm square region of the second compound semiconductor layer were evaluated by an atomic force microscope (AFM), they were 2.2 nm.

すなわち、第２の化合物半導体層の、Ｓｉ基板の面方位と同じ面に対応するＸ線回折ピークのロッキングカーブの、ＦＷＨＭ値が６００秒以下であり、且つ、第２の化合物半導体層の１０μｍ四方の領域における、表面粗さの二乗平均値、Ｒｒｍｓ値が３ｎｍ以下である化合物半導体基板を実現した。   That is, the rocking curve of the X-ray diffraction peak corresponding to the same plane as the plane direction of the Si substrate of the second compound semiconductor layer has a FWHM value of 600 seconds or less and the 10 μm square of the second compound semiconductor layer In this region, a compound semiconductor substrate having a surface roughness root mean square value and an Rrms value of 3 nm or less was realized.

［実施例４］
まず、実施例１と同様に、Ｓｉ（１１１）基板の表面の有機物、金属等の汚染物質を除去した後、濃度１．０ｗｔ％のフッ化水素水溶液を用いて表面の酸化膜を除去して、水素終端処理を行った。 [Example 4]
First, as in Example 1, after removing contaminants such as organic substances and metals on the surface of the Si (111) substrate, the surface oxide film was removed using a hydrogen fluoride aqueous solution having a concentration of 1.0 wt%. Then, hydrogen termination treatment was performed.

これを直ちにＭＢＥ装置内に導入し、１×１０-6Ｔｏｒｒ（１．３３３×１０-6Ｐａ）以下の真空中で、基板温度が３００℃になるまで加熱し、温度が一定になったところでＡｓを照射した。 This was immediately introduced into the MBE apparatus, heated in a vacuum of 1 × 10 −6 Torr (1.333 × 10 −6 Pa) or less until the substrate temperature reached 300 ° C., and when the temperature became constant As was irradiated.

引き続き、分子線強度が７×１０-8ＴｏｒｒのＧａと、分子線強度が３×１０-5ＴｏｒｒのＡｓ4分子をクラッキングすなわち加熱して生成したＡｓ2分子とを同時に照射することにより、膜厚２０ｎｍの第１の化合物半導体層であるＧａＡｓ層を、１時間当たり０．１μｍの形成速度で形成した。 Subsequently, the film is irradiated by simultaneously irradiating Ga having a molecular beam intensity of 7 × 10 −8 Torr and As 2 molecules generated by cracking, ie heating, As 4 molecules having a molecular beam intensity of 3 × 10 −5 Torr. A GaAs layer, which is a first compound semiconductor layer having a thickness of 20 nm, was formed at a formation rate of 0.1 μm per hour.

その後、基板温度が６６０℃になるまで加熱し、温度が一定になったところで、分子線強度が７×１０-7ＴｏｒｒのＧａと、分子線強度が３×１０-5ＴｏｒｒのＡｓ4分子をクラッキングすなわち加熱して生成したＡｓ2分子と、分子線強度が８×１０-7ＴｏｒｒのＳｂとを同時に照射することにより、膜厚９８０ｎｍの第２の化合物半導体層を、１時間当たり１μｍの形成速度で形成した。このとき、換算Ｓｂ／Ｇａ分子線強度比は１．１４である。 Thereafter, the substrate temperature is heated to 660 ° C., and when the temperature becomes constant, Ga having a molecular beam intensity of 7 × 10 −7 Torr and As 4 molecules having a molecular beam intensity of 3 × 10 −5 Torr are obtained. By simultaneously irradiating cracked or heated As 2 molecules generated and Sb having a molecular beam intensity of 8 × 10 −7 Torr, a second compound semiconductor layer having a thickness of 980 nm is formed at 1 μm per hour. Formed at speed. At this time, the converted Sb / Ga molecular beam intensity ratio is 1.14.

第２の化合物半導体層の（１１１）面に対応するＸ線回折ピークを解析したところ、Ｓｂ組成ｙは０．０１５であった。また、第２の化合物半導体層の、（１１１）面に対応するＸ線回折ピークのロッキングカーブのＦＷＨＭ値は５９０秒であった。さらに、第２の化合物半導体層の１０μｍ四方の領域における、表面粗さの二乗平均値Ｒｒｍｓを原子間力顕微鏡（ＡＦＭ）で評価したところ、２．９ｎｍであった。   When the X-ray diffraction peak corresponding to the (111) plane of the second compound semiconductor layer was analyzed, the Sb composition y was 0.015. Moreover, the FWHM value of the rocking curve of the X-ray diffraction peak corresponding to the (111) plane of the second compound semiconductor layer was 590 seconds. Furthermore, when the root mean square value Rrms of the 10 μm square region of the second compound semiconductor layer was evaluated with an atomic force microscope (AFM), it was 2.9 nm.

すなわち、第２の化合物半導体層の、Ｓｉ基板の面方位と同じ面に対応するＸ線回折ピークのロッキングカーブの、ＦＷＨＭ値が６００秒以下であり、且つ、第２の化合物半導体層の１０μｍ四方の領域における、表面粗さの二乗平均値Ｒｒｍｓが３ｎｍ以下である化合物半導体基板を実現した。   That is, the rocking curve of the X-ray diffraction peak corresponding to the same plane as the plane direction of the Si substrate of the second compound semiconductor layer has a FWHM value of 600 seconds or less and the 10 μm square of the second compound semiconductor layer In this region, a compound semiconductor substrate having a surface roughness root mean square value Rrms of 3 nm or less was realized.

［比較例１］
実施例３、４に対する比較例１について述べる。 [Comparative Example 1]
Comparative Example 1 for Examples 3 and 4 will be described.

まず、実施例１と同様に、Ｓｉ（１１１）基板の表面の有機物、金属等の汚染物質を除去した後、濃度１．０ｗｔ％のフッ化水素水溶液を用いて表面の酸化膜を除去して、水素終端処理を行った。   First, as in Example 1, after removing contaminants such as organic substances and metals on the surface of the Si (111) substrate, the surface oxide film was removed using a hydrogen fluoride aqueous solution having a concentration of 1.0 wt%. Then, hydrogen termination treatment was performed.

これを直ちにＭＢＥ装置内に導入し、１×１０-6Ｔｏｒｒ（１．３３３×１０-6Ｐａ）以下の真空中で、基板温度が３００℃になるまで加熱し、温度が一定になったところでＡｓを照射した。 This was immediately introduced into the MBE apparatus, heated in a vacuum of 1 × 10 −6 Torr (1.333 × 10 −6 Pa) or less until the substrate temperature reached 300 ° C., and when the temperature became constant As was irradiated.

引き続き、分子線強度が７×１０-8ＴｏｒｒのＧａと、分子線強度が３×１０-5ＴｏｒｒのＡｓ4分子をクラッキングすなわち加熱して生成したＡｓ2分子とを同時に照射することにより、膜厚２０ｎｍの第１の化合物半導体層であるＧａＡｓ層を、１時間当たり０．１μｍの形成速度で形成した。 Subsequently, the film is irradiated by simultaneously irradiating Ga having a molecular beam intensity of 7 × 10 −8 Torr and As 2 molecules generated by cracking, ie heating, As 4 molecules having a molecular beam intensity of 3 × 10 −5 Torr. A GaAs layer, which is a first compound semiconductor layer having a thickness of 20 nm, was formed at a formation rate of 0.1 μm per hour.

その後、基板温度が５８０℃になるまで加熱し、温度が一定になったところで、分子線強度が７×１０-7ＴｏｒｒのＧａと、分子線強度が３×１０-5ＴｏｒｒのＡｓ4分子をクラッキングすなわち加熱して生成したＡｓ2分子とを同時に照射することにより、膜厚９８０ｎｍの第２の化合物半導体層をであるＧａＡｓ層を、１時間当たり１μｍの形成速度で形成した。このとき、換算Ｓｂ／Ｇａ分子線強度比は、第２の化合物半導体層の形成時にＳｂを同時照射していないので、当然のことながら０である。 Then, the substrate temperature is heated to 580 ° C., and when the temperature becomes constant, Ga having a molecular beam intensity of 7 × 10 −7 Torr and As 4 molecules having a molecular beam intensity of 3 × 10 −5 Torr are obtained. By simultaneously irradiating cracked or heated As 2 molecules, a GaAs layer, which is a second compound semiconductor layer having a thickness of 980 nm, was formed at a formation rate of 1 μm per hour. At this time, the converted Sb / Ga molecular beam intensity ratio is naturally 0 since Sb is not simultaneously irradiated when the second compound semiconductor layer is formed.

第２の化合物半導体層の（１１１）面に対応するＸ線回折ピークを解析したところ、Ｓｂ組成ｙは、第２の化合物半導体層の形成時にＳｂを同時照射していないので、当然のことながら０である。また、第２の化合物半導体層の、（１１１）面に対応するＸ線回折ピークのロッキングカーブのＦＷＨＭ値は５２０秒であった。さらに、第２の化合物半導体層の１０μｍ四方の領域における、表面粗さの二乗平均値Ｒｒｍｓを原子間力顕微鏡（ＡＦＭ）で評価したところ、２０．５ｎｍであった。   When the X-ray diffraction peak corresponding to the (111) plane of the second compound semiconductor layer is analyzed, the Sb composition y is naturally not simultaneously irradiated with Sb when the second compound semiconductor layer is formed. 0. Further, the FWHM value of the rocking curve of the X-ray diffraction peak corresponding to the (111) plane of the second compound semiconductor layer was 520 seconds. Furthermore, when the root mean square value Rrms of the 10 μm square region of the second compound semiconductor layer was evaluated with an atomic force microscope (AFM), it was 20.5 nm.

実施例３、４と比較した場合、Ｒｒｍｓ値が圧倒的に大きくなってしまうことがわかる。第２の化合物半導体層の形成時にＳｂを同時照射していない場合、第２の化合物半導体層は３次元成長してしまう。この状態で、Ｒｒｍｓ値を下げるためには、第２の化合物半導体層形成時の基板温度を下げなければならないが、そうすると結晶性は悪化し、ＦＷＨＭ値は増大してしまう。   When compared with Examples 3 and 4, it can be seen that the Rrms value is overwhelmingly large. If Sb is not simultaneously irradiated when forming the second compound semiconductor layer, the second compound semiconductor layer grows three-dimensionally. In this state, in order to lower the Rrms value, the substrate temperature at the time of forming the second compound semiconductor layer must be lowered. However, in this case, the crystallinity deteriorates and the FWHM value increases.

すなわち、第２の化合物半導体層の形成時にＳｂを同時照射していない場合、第２の化合物半導体層の、Ｓｉ基板の面方位と同じ面に対応するＸ線回折ピークのロッキングカーブのＦＷＨＭ値が７００秒以下であり、且つ、第２の化合物半導体層の１０μｍ四方の領域における、表面粗さの二乗平均値Ｒｒｍｓが３ｎｍ以下である化合物半導体基板を実現することはできない。   That is, when Sb is not simultaneously irradiated when forming the second compound semiconductor layer, the FWHM value of the rocking curve of the X-ray diffraction peak corresponding to the same plane as the plane orientation of the Si substrate of the second compound semiconductor layer is A compound semiconductor substrate having a surface roughness root mean square value Rrms of 3 nm or less in a 10 μm square region of the second compound semiconductor layer for 700 seconds or less cannot be realized.

［比較例２］
実施例３、４に対する比較例２について述べる。 [Comparative Example 2]
Comparative example 2 with respect to Examples 3 and 4 will be described.

比較例１では、実施例３、４と比較した場合、Ｒｒｍｓ値が圧倒的に大きくなってしまう。Ｒｒｍｓ値を小さくするためには、第二の化合物半導体層を、より低温で形成しなければならない。そこで、比較例１よりも低温で第二の化合物半導体層を形成した例を、比較例２として述べる。   In Comparative Example 1, when compared with Examples 3 and 4, the Rrms value is overwhelmingly large. In order to reduce the Rrms value, the second compound semiconductor layer must be formed at a lower temperature. Therefore, an example in which the second compound semiconductor layer is formed at a lower temperature than Comparative Example 1 will be described as Comparative Example 2.

まず、実施例１と同様に、Ｓｉ（１１１）基板の表面の有機物、金属等の汚染物質を除去した後、濃度１．０ｗｔ％のフッ化水素水溶液を用いて表面の酸化膜を除去して、水素終端処理を行った。   First, as in Example 1, after removing contaminants such as organic substances and metals on the surface of the Si (111) substrate, the surface oxide film was removed using a hydrogen fluoride aqueous solution having a concentration of 1.0 wt%. Then, hydrogen termination treatment was performed.

これを直ちにＭＢＥ装置内に導入し、１×１０-6Ｔｏｒｒ（１．３３３×１０-6Ｐａ）以下の真空中で、基板温度が３００℃になるまで加熱し、温度が一定になったところでＡｓを照射した。 This was immediately introduced into the MBE apparatus, heated in a vacuum of 1 × 10 −6 Torr (1.333 × 10 −6 Pa) or less until the substrate temperature reached 300 ° C., and when the temperature became constant As was irradiated.

引き続き、分子線強度が７×１０-8ＴｏｒｒのＧａと、分子線強度が３×１０-5ＴｏｒｒのＡｓ4分子をクラッキングすなわち加熱して生成したＡｓ2分子とを同時に照射することにより、膜厚２０ｎｍの第１の化合物半導体層であるＧａＡｓ層を、１時間当たり０．１μｍの形成速度で形成した。 Subsequently, the film is irradiated by simultaneously irradiating Ga having a molecular beam intensity of 7 × 10 −8 Torr and As 2 molecules generated by cracking, ie heating, As 4 molecules having a molecular beam intensity of 3 × 10 −5 Torr. A GaAs layer, which is a first compound semiconductor layer having a thickness of 20 nm, was formed at a formation rate of 0.1 μm per hour.

その後、基板温度が４２０℃になるまで加熱し、温度が一定になったところで、分子線強度が７×１０-7ＴｏｒｒのＧａと、分子線強度が３×１０-5ＴｏｒｒのＡｓ4分子をクラッキングすなわち加熱して生成したＡｓ2分子とを同時に照射することにより、膜厚９８０ｎｍの第２の化合物半導体層をであるＧａＡｓ層を、１時間当たり１μｍの形成速度で形成した。このとき、換算Ｓｂ／Ｇａ分子線強度比は、第２の化合物半導体層の形成時にＳｂを同時照射していないので、当然のことながら０である。 Thereafter, the substrate is heated to 420 ° C., and when the temperature becomes constant, Ga having a molecular beam intensity of 7 × 10 −7 Torr and As 4 molecules having a molecular beam intensity of 3 × 10 −5 Torr are obtained. By simultaneously irradiating cracked or heated As 2 molecules, a GaAs layer, which is a second compound semiconductor layer having a thickness of 980 nm, was formed at a formation rate of 1 μm per hour. At this time, the converted Sb / Ga molecular beam intensity ratio is naturally 0 since Sb is not simultaneously irradiated when the second compound semiconductor layer is formed.

第２の化合物半導体層の（１１１）面に対応するＸ線回折ピークを解析したところ、Ｓｂ組成ｙは、第２の化合物半導体層の形成時にＳｂを同時照射していないので、当然のことながら０である。また、第２の化合物半導体層の、（１１１）面に対応するＸ線回折ピークのロッキングカーブのＦＷＨＭ値は１０４０秒であった。さらに、第２の化合物半導体層の１０μｍ四方の領域における、表面粗さの二乗平均値Ｒｒｍｓを原子間力顕微鏡（ＡＦＭ）で評価したところ、２．０ｎｍであった。   When the X-ray diffraction peak corresponding to the (111) plane of the second compound semiconductor layer is analyzed, the Sb composition y is naturally not simultaneously irradiated with Sb when the second compound semiconductor layer is formed. 0. Further, the FWHM value of the rocking curve of the X-ray diffraction peak corresponding to the (111) plane of the second compound semiconductor layer was 1040 seconds. Furthermore, when the root mean square value Rrms of the 10 μm square region of the second compound semiconductor layer was evaluated with an atomic force microscope (AFM), it was 2.0 nm.

比較例１と比較すると、Ｒｒｍｓ値は小さくなったものの、ＦＷＨＭ値が大きくなってしまった。実施例３、４と比較した場合においても、ＦＷＨＭ値が圧倒的に大きくなってしまうことがわかる。   Compared with Comparative Example 1, although the Rrms value was small, the FWHM value was large. Even when compared with Examples 3 and 4, it can be seen that the FWHM value is overwhelmingly large.

すなわち、第２の化合物半導体層の形成時にＳｂを同時照射していない場合、第２の化合物半導体層の、Ｓｉ基板の面方位と同じ面に対応するＸ線回折ピークのロッキングカーブのＦＷＨＭ値が７００秒以下であり、且つ、第２の化合物半導体層の１０μｍ四方の領域における、表面粗さの二乗平均値Ｒｒｍｓが３ｎｍ以下である化合物半導体基板を実現することはできない。   That is, when Sb is not simultaneously irradiated when forming the second compound semiconductor layer, the FWHM value of the rocking curve of the X-ray diffraction peak corresponding to the same plane as the plane orientation of the Si substrate of the second compound semiconductor layer is A compound semiconductor substrate having a surface roughness root mean square value Rrms of 3 nm or less in a 10 μm square region of the second compound semiconductor layer for 700 seconds or less cannot be realized.

［比較例３］
実施例３、４に対する比較例３について述べる。 [Comparative Example 3]
A comparative example 3 relative to the examples 3 and 4 will be described.

まず、実施例１と同様に、Ｓｉ（１１１）基板の表面の有機物、金属等の汚染物質を除去した後、濃度１．０ｗｔ％のフッ化水素水溶液を用いて表面の酸化膜を除去して、水素終端処理を行った。   First, as in Example 1, after removing contaminants such as organic substances and metals on the surface of the Si (111) substrate, the surface oxide film was removed using a hydrogen fluoride aqueous solution having a concentration of 1.0 wt%. Then, hydrogen termination treatment was performed.

これを直ちにＭＢＥ装置内に導入し、１×１０-6Ｔｏｒｒ（１．３３３×１０-6Ｐａ）以下の真空中で、基板温度が３００℃になるまで加熱し、温度が一定になったところでＡｓを照射した。 This was immediately introduced into the MBE apparatus, heated in a vacuum of 1 × 10 −6 Torr (1.333 × 10 −6 Pa) or less until the substrate temperature reached 300 ° C., and when the temperature became constant As was irradiated.

引き続き、分子線強度が７×１０-8ＴｏｒｒのＧａと、分子線強度が３×１０-5ＴｏｒｒのＡｓ4分子をクラッキングすなわち加熱して生成したＡｓ2分子とを同時に照射することにより、膜厚２０ｎｍの第１の化合物半導体層であるＧａＡｓ層を、１時間当たり０．１μｍの形成速度で形成した。 Subsequently, the film is irradiated by simultaneously irradiating Ga having a molecular beam intensity of 7 × 10 −8 Torr and As 2 molecules generated by cracking, ie heating, As 4 molecules having a molecular beam intensity of 3 × 10 −5 Torr. A GaAs layer, which is a first compound semiconductor layer having a thickness of 20 nm, was formed at a formation rate of 0.1 μm per hour.

その後、基板温度が５８０℃になるまで加熱し、温度が一定になったところで、分子線強度が７×１０-7ＴｏｒｒのＧａと、分子線強度が３×１０-5ＴｏｒｒのＡｓ4分子をクラッキングすなわち加熱して生成したＡｓ2分子と、分子線強度が３．５×１０-7ＴｏｒｒのＳｂとを同時に照射することにより、膜厚９８０ｎｍの第２の化合物半導体層を、１時間当たり１μｍの形成速度で形成した。このとき、換算Ｓｂ／Ｇａ分子線強度比は０．５である。 Then, the substrate temperature is heated to 580 ° C., and when the temperature becomes constant, Ga having a molecular beam intensity of 7 × 10 −7 Torr and As 4 molecules having a molecular beam intensity of 3 × 10 −5 Torr are obtained. By simultaneously irradiating cracked or heated As 2 molecules generated by heating and Sb having a molecular beam intensity of 3.5 × 10 −7 Torr, a second compound semiconductor layer having a thickness of 980 nm is formed at 1 μm per hour. Formed at a rate of At this time, the converted Sb / Ga molecular beam intensity ratio is 0.5.

第２の化合物半導体層の（１１１）面に対応するＸ線回折ピークを解析したところ、Ｓｂ組成ｙは０．０２６であった。また、第２の化合物半導体層の、（１１１）面に対応するＸ線回折ピークのロッキングカーブのＦＷＨＭ値は６７０秒であった。さらに、第２の化合物半導体層の１０μｍ四方の領域における、表面粗さの二乗平均値Ｒｒｍｓを原子間力顕微鏡（ＡＦＭ）で評価したところ、２０．３ｎｍであった。   When the X-ray diffraction peak corresponding to the (111) plane of the second compound semiconductor layer was analyzed, the Sb composition y was 0.026. Further, the FWHM value of the rocking curve of the X-ray diffraction peak corresponding to the (111) plane of the second compound semiconductor layer was 670 seconds. Furthermore, the root mean square value Rrms of the 10 μm square region of the second compound semiconductor layer was evaluated by an atomic force microscope (AFM) to be 20.3 nm.

実施例３、４と比較した場合、Ｒｒｍｓ値が圧倒的に大きくなってしまうことがわかる。第２の化合物半導体層の形成時にＳｂを同時照射していても、その量が少ない場合、すなわち、換算Ｓｂ／Ｇａ分子線強度比が１以下の場合、第２の化合物半導体層は比較例１の場合と同様に３次元成長してしまう。この状態で、Ｒｒｍｓ値を下げるためには、第２の化合物半導体層形成時の基板温度を下げなければならないが、そうすると結晶性は悪化し、ＦＷＨＭ値は増大してしまう。   When compared with Examples 3 and 4, it can be seen that the Rrms value is overwhelmingly large. Even if Sb is simultaneously irradiated when forming the second compound semiconductor layer, if the amount is small, that is, if the converted Sb / Ga molecular beam intensity ratio is 1 or less, the second compound semiconductor layer is Comparative Example 1. As in the case of, the three-dimensional growth occurs. In this state, in order to lower the Rrms value, the substrate temperature at the time of forming the second compound semiconductor layer must be lowered. However, in this case, the crystallinity deteriorates and the FWHM value increases.

すなわち、第２の化合物半導体層の形成時にＳｂを同時照射していても、その量が少ない場合、すなわち、換算Ｓｂ／Ｇａ分子線強度比が１以下の場合、第２の化合物半導体層の、Ｓｉ基板の面方位と同じ面に対応するＸ線回折ピークのロッキングカーブのＦＷＨＭ値が７００秒以下であり、且つ、第２の化合物半導体層の１０μｍ四方の領域における、表面粗さの二乗平均値Ｒｒｍｓが３ｎｍ以下である化合物半導体基板を実現することはできない。   That is, even when Sb is simultaneously irradiated at the time of forming the second compound semiconductor layer, when the amount is small, that is, when the converted Sb / Ga molecular beam intensity ratio is 1 or less, The FWHM value of the rocking curve of the X-ray diffraction peak corresponding to the same plane as the plane direction of the Si substrate is 700 seconds or less, and the mean square value of the surface roughness in the 10 μm square region of the second compound semiconductor layer A compound semiconductor substrate having an Rrms of 3 nm or less cannot be realized.

［実施例５］
まず、Ｓｉ（１１１）基板の表面の有機物、金属等の汚染物質を除去した後、濃度１．０ｗｔ％のフッ化水素水溶液を用いて表面の酸化膜を除去して、水素終端処理を行った。 [Example 5]
First, after removing contaminants such as organic substances and metals on the surface of the Si (111) substrate, the surface oxide film was removed using a hydrogen fluoride aqueous solution having a concentration of 1.0 wt%, and hydrogen termination treatment was performed. .

これを直ちにＭＢＥ装置内に導入し、１×１０-6Ｔｏｒｒ（１．３３３×１０-6Ｐａ）以下の真空中で、基板温度が３００℃になるまで加熱し、温度が一定になったところでＡｓを照射した。 This was immediately introduced into the MBE apparatus, heated in a vacuum of 1 × 10 −6 Torr (1.333 × 10 −6 Pa) or less until the substrate temperature reached 300 ° C., and when the temperature became constant As was irradiated.

引き続き、分子線強度が７×１０-8ＴｏｒｒのＧａと、分子線強度が３×１０-5ＴｏｒｒのＡｓ4分子をクラッキングすなわち加熱して生成したＡｓ2分子とを同時に照射することにより、膜厚２０ｎｍの第１の化合物半導体層であるＧａＡｓ層を、１時間当たり０．１μｍの形成速度で形成した。 Subsequently, the film is irradiated by simultaneously irradiating Ga having a molecular beam intensity of 7 × 10 −8 Torr and As 2 molecules generated by cracking, ie heating, As 4 molecules having a molecular beam intensity of 3 × 10 −5 Torr. A GaAs layer, which is a first compound semiconductor layer having a thickness of 20 nm, was formed at a formation rate of 0.1 μm per hour.

その後、基板温度が６６０℃になるまで加熱し、温度が一定になったところで、分子線強度が１．４×１０-7ＴｏｒｒのＧａと、分子線強度が３×１０-5ＴｏｒｒのＡｓ4分子をクラッキングすなわち加熱して生成したＡｓ2分子と、分子線強度が１．６４×１０-6ＴｏｒｒのＳｂとを同時に照射することにより、膜厚９８０ｎｍの第２の化合物半導体層を、１時間当たり０．２μｍの形成速度で形成した。このとき、換算Ｓｂ／Ｇａ分子線強度比は２．３４である。 Thereafter, the substrate is heated to 660 ° C., and when the temperature becomes constant, Ga having a molecular beam intensity of 1.4 × 10 −7 Torr and As 4 having a molecular beam intensity of 3 × 10 −5 Torr. By simultaneously irradiating As 2 molecules generated by cracking or heating the molecules and Sb having a molecular beam intensity of 1.64 × 10 −6 Torr, the second compound semiconductor layer having a thickness of 980 nm is formed for 1 hour. The film was formed at a formation speed of 0.2 μm per unit. At this time, the converted Sb / Ga molecular beam intensity ratio is 2.34.

第２の化合物半導体層の（１１１）面に対応するＸ線回折ピークを解析したところ、Ｓｂ組成ｙは０．０１３であった。また、第２の化合物半導体層の、（１１１）面に対応するＸ線回折ピークのロッキングカーブの、ＦＷＨＭ値は４３５秒であった。さらに、第２の化合物半導体層の１０μｍ四方の領域における、表面粗さの二乗平均値、Ｒｒｍｓ値を原子間力顕微鏡（ＡＦＭ）で評価したところ、１．８ｎｍであった。   When the X-ray diffraction peak corresponding to the (111) plane of the second compound semiconductor layer was analyzed, the Sb composition y was 0.013. Further, the FWHM value of the rocking curve of the X-ray diffraction peak corresponding to the (111) plane of the second compound semiconductor layer was 435 seconds. Furthermore, when the mean square value of the surface roughness and the Rrms value in the 10 μm square region of the second compound semiconductor layer were evaluated by an atomic force microscope (AFM), it was 1.8 nm.

すなわち、第２の化合物半導体層の、Ｓｉ基板の面方位と同じ面に対応するＸ線回折ピークのロッキングカーブの、ＦＷＨＭ値が５００秒以下であり、且つ、第２の化合物半導体層の１０μｍ四方の領域における、表面粗さの二乗平均値Ｒｒｍｓが２ｎｍ以下である化合物半導体基板を実現した。   That is, the rocking curve of the X-ray diffraction peak corresponding to the same plane as the plane direction of the Si substrate of the second compound semiconductor layer has a FWHM value of 500 seconds or less and the 10 μm square of the second compound semiconductor layer In this region, a compound semiconductor substrate having a surface roughness root mean square value Rrms of 2 nm or less was realized.

上述した実施例１〜５および比較例１，２を以下の表１にまとめた。   Examples 1 to 5 and Comparative Examples 1 and 2 described above are summarized in Table 1 below.

Figure 2013187489
Figure 2013187489

１０ 化合物半導体基板
１０１ Ｓｉ基板
１０２ 第１の化合物半導体層
１０３ 第２の化合物半導体層 10 Compound Semiconductor Substrate 101 Si Substrate 102 First Compound Semiconductor Layer 103 Second Compound Semiconductor Layer

Claims (8)

Ｓｉ基板上に第１の化合物半導体層を形成する工程と、
前記第１の化合物半導体層上に、前記第１の化合物半導体層を形成するときよりも高温で、第２の化合物半導体層を形成する工程と
を備える化合物半導体基板の製造方法であって、
前記第１の化合物半導体層は、ＧａＡｓ1-xＳｂx（０≦ｘ≦０．１）層であり、
前記第２の化合物半導体層は、ＧａＡｓ1-yＳｂy（０＜ｙ≦０．１）層であり、
前記第２の化合物半導体層を形成する工程は、Ｇａ原料とＡｓ原料とＳｂ原料とを同時に照射する工程であり、
前記第２の化合物半導体層を形成する工程において、前記Ｓｂ原料の分子線強度と、前記第２の化合物半導体層の形成速度が１時間当たり１μｍとなるために必要な前記Ｇａ原料の分子線強度との比が１以上であることを特徴とする化合物半導体基板の製造方法。 Forming a first compound semiconductor layer on a Si substrate;
Forming a second compound semiconductor layer on the first compound semiconductor layer at a higher temperature than when forming the first compound semiconductor layer, comprising:
The first compound semiconductor layer is a GaAs 1-x Sb x (0 ≦ x ≦ 0.1) layer,
Said second compound semiconductor layer is GaAs 1-y Sb y (0 <y ≦ 0.1) layer,
The step of forming the second compound semiconductor layer is a step of simultaneously irradiating a Ga raw material, an As raw material, and an Sb raw material,
In the step of forming the second compound semiconductor layer, the molecular beam intensity of the Sb material and the molecular beam intensity of the Ga material necessary for the formation rate of the second compound semiconductor layer to be 1 μm per hour. The method for producing a compound semiconductor substrate, wherein the ratio is 1 or more. 前記第１の化合物半導体層は、ＧａＡｓ層であることを特徴とする請求項１に記載の化合物半導体基板の製造方法。   The method of manufacturing a compound semiconductor substrate according to claim 1, wherein the first compound semiconductor layer is a GaAs layer. 前記第２の化合物半導体層の形成速度は、１時間当たり０．０５μｍ以上０．３μｍ以下
であることを特徴とする請求項１または２に記載の化合物半導体基板の製造方法。 3. The method of manufacturing a compound semiconductor substrate according to claim 1, wherein the formation rate of the second compound semiconductor layer is 0.05 μm or more and 0.3 μm or less per hour. 前記Ａｓ原料は、Ａｓ2分子であることを特徴とする請求項１から３の何れか１項に記載の化合物半導体基板の製造方法。 The method for producing a compound semiconductor substrate according to claim 1, wherein the As raw material is an As 2 molecule. 前記Ａｓ原料は、Ａｓ4分子をクラッキングすることにより生成されることを特徴とする請求項１から４の何れか１項に記載の化合物半導体基板の製造方法。 The method for producing a compound semiconductor substrate according to claim 1, wherein the As raw material is generated by cracking As 4 molecules. Ｓｉ基板と、
前記Ｓｉ基板上に形成された、第１の化合物半導体層と、
前記第１の化合物半導体層上に形成された、第２の化合物半導体層と
を備えた化合物半導体基板であって、
前記第１の化合物半導体層は、ＧａＡｓ1-xＳｂx（０≦ｘ≦０．１）層であり、
前記第２の化合物半導体層は、ＧａＡｓ1-yＳｂy（０＜ｙ≦０．１）層であり、
前記第２の化合物半導体層の、前記Ｓｉ基板の面方位と同じ面に対応するＸ線回折ピークのロッキングカーブの、ＦＷＨＭ値は、７００秒以下であり、且つ
前記第２の化合物半導体層の１０μｍ四方の領域における、表面粗さの二乗平均値Ｒｒｍｓ値は、３ｎｍ以下であることを特徴とする化合物半導体基板。 A Si substrate;
A first compound semiconductor layer formed on the Si substrate;
A compound semiconductor substrate comprising: a second compound semiconductor layer formed on the first compound semiconductor layer;
The first compound semiconductor layer is a GaAs 1-x Sb x (0 ≦ x ≦ 0.1) layer,
Said second compound semiconductor layer is GaAs 1-y Sb y (0 <y ≦ 0.1) layer,
The rocking curve of the X-ray diffraction peak corresponding to the same plane as the plane direction of the Si substrate of the second compound semiconductor layer has a FWHM value of 700 seconds or less, and 10 μm of the second compound semiconductor layer. A compound semiconductor substrate, wherein a root mean square value Rrms value of surface roughness in a four-way region is 3 nm or less. 前記第１の化合物半導体層は、ＧａＡｓ層であり、
前記第２の化合物半導体層の、前記Ｓｉ基板の面方位と同じ面に対応するＸ線回折ピークのロッキングカーブの、ＦＷＨＭ値は、６００秒以下であり、且つ
前記第２の化合物半導体層の１０μｍ四方の領域における、表面粗さの二乗平均値Ｒｒｍｓ値は、３ｎｍ以下であることを特徴とする請求項６に記載の化合物半導体基板。 The first compound semiconductor layer is a GaAs layer;
The rocking curve of the X-ray diffraction peak corresponding to the same plane as the plane direction of the Si substrate of the second compound semiconductor layer has a FWHM value of 600 seconds or less, and 10 μm of the second compound semiconductor layer. The compound semiconductor substrate according to claim 6, wherein a root mean square value Rrms value of the surface roughness in the four regions is 3 nm or less. 前記第１の化合物半導体層は、ＧａＡｓ層であり、
前記第２の化合物半導体層の、前記Ｓｉ基板の面方位と同じ面に対応するＸ線回折ピークのロッキングカーブの、ＦＷＨＭ値は、５００秒以下であり、且つ
前記第２の化合物半導体層の１０μｍ四方の領域における、表面粗さの二乗平均値Ｒｒｍｓ値は、２ｎｍ以下であることを特徴とする請求項６に記載の化合物半導体基板。 The first compound semiconductor layer is a GaAs layer;
The rocking curve of the X-ray diffraction peak corresponding to the same plane as the plane orientation of the Si substrate of the second compound semiconductor layer has a FWHM value of 500 seconds or less, and 10 μm of the second compound semiconductor layer. 7. The compound semiconductor substrate according to claim 6, wherein the root mean square value Rrms value of the surface roughness in the four regions is 2 nm or less.
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