WO2010024411A1 - Procédé de formation de couche épitaxiale composée, couche épitaxiale composée, structure stratifiée à semi-conducteurs, et dispositif électroluminescent à semi-conducteurs - Google Patents

Procédé de formation de couche épitaxiale composée, couche épitaxiale composée, structure stratifiée à semi-conducteurs, et dispositif électroluminescent à semi-conducteurs Download PDF

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WO2010024411A1
WO2010024411A1 PCT/JP2009/065118 JP2009065118W WO2010024411A1 WO 2010024411 A1 WO2010024411 A1 WO 2010024411A1 JP 2009065118 W JP2009065118 W JP 2009065118W WO 2010024411 A1 WO2010024411 A1 WO 2010024411A1
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epitaxial layer
sec
layer
plane
growth
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Japanese (ja)
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洋 藤岡
篤 小林
秀善 堀江
英隆 天内
哲 長尾
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財団法人神奈川科学技術アカデミー
国立大学法人 東京大学
三菱化学株式会社
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Priority claimed from JP2008222151A external-priority patent/JP2010053002A/ja
Priority claimed from JP2008222150A external-priority patent/JP2010056436A/ja
Priority claimed from JP2008222149A external-priority patent/JP2010056435A/ja
Application filed by 財団法人神奈川科学技術アカデミー, 国立大学法人 東京大学, 三菱化学株式会社 filed Critical 財団法人神奈川科学技術アカデミー
Publication of WO2010024411A1 publication Critical patent/WO2010024411A1/fr

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    • C—CHEMISTRY; METALLURGY
    • C30—CRYSTAL GROWTH
    • C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
    • C30B25/00—Single-crystal growth by chemical reaction of reactive gases, e.g. chemical vapour-deposition growth
    • C30B25/02—Epitaxial-layer growth
    • C30B25/06—Epitaxial-layer growth by reactive sputtering
    • C—CHEMISTRY; METALLURGY
    • C30—CRYSTAL GROWTH
    • C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
    • C30B25/00—Single-crystal growth by chemical reaction of reactive gases, e.g. chemical vapour-deposition growth
    • C30B25/02—Epitaxial-layer growth
    • C30B25/14—Feed and outlet means for the gases; Modifying the flow of the reactive gases
    • C—CHEMISTRY; METALLURGY
    • C30—CRYSTAL GROWTH
    • C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
    • C30B29/00—Single crystals or homogeneous polycrystalline material with defined structure characterised by the material or by their shape
    • C30B29/10—Inorganic compounds or compositions
    • C30B29/40—AIIIBV compounds wherein A is B, Al, Ga, In or Tl and B is N, P, As, Sb or Bi
    • C30B29/403—AIII-nitrides
    • C—CHEMISTRY; METALLURGY
    • C30—CRYSTAL GROWTH
    • C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
    • C30B29/00—Single crystals or homogeneous polycrystalline material with defined structure characterised by the material or by their shape
    • C30B29/10—Inorganic compounds or compositions
    • C30B29/40—AIIIBV compounds wherein A is B, Al, Ga, In or Tl and B is N, P, As, Sb or Bi
    • C30B29/403—AIII-nitrides
    • C30B29/406—Gallium nitride
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    • H01L21/02365—Forming inorganic semiconducting materials on a substrate
    • H01L21/02436—Intermediate layers between substrates and deposited layers
    • H01L21/02439—Materials
    • H01L21/02455—Group 13/15 materials
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    • H01L21/02365—Forming inorganic semiconducting materials on a substrate
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    • H01L33/00—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L33/005—Processes
    • H01L33/0062—Processes for devices with an active region comprising only III-V compounds
    • H01L33/0066—Processes for devices with an active region comprising only III-V compounds with a substrate not being a III-V compound
    • H01L33/007—Processes for devices with an active region comprising only III-V compounds with a substrate not being a III-V compound comprising nitride compounds

Definitions

  • the present invention relates to a method for growing a compound epitaxial layer, a compound epitaxial layer, a semiconductor multilayer structure, and a semiconductor light emitting device, and more particularly to a method for producing a group III-V nitride layer having good crystallinity that can be used for a light emitting device or the like. .
  • group III-V nitride semiconductors represented by In x Al y Ga (1-xy) N (0 ⁇ x ⁇ 1, 0 ⁇ y ⁇ 1, 0 ⁇ x + y ⁇ 1) have advanced.
  • the light emission efficiency of light emitting devices such as light emitting diodes and laser diodes has been dramatically improved.
  • In x Al y Ga (1-xy) N including GaN belongs to the hexagonal system and has been formed mainly by epitaxial growth on the c-plane of a substrate such as sapphire.
  • a quantum well layer made of In x Ga (1-x) N (0 ⁇ x ⁇ 1) mixed crystal is stacked as an active layer on a GaN layer.
  • the layer structure for a blue / green LED or next-generation DVD laser is used. Used or promising.
  • a hexagonal group III-V nitride semiconductor has a spontaneous polarization because it is a polarization substance whose c-axis is a polarization axis.
  • a strong internal electric field is induced by piezoelectric polarization in the distorted quantum well on the c-plane, so that electrons and holes are spatially separated in one quantum well layer. That is, the InGaN layer on the GaN layer grown on the c-plane has a problem in that the probability that electrons and holes recombine with each other in luminescence essentially decreases.
  • the emission wavelength is shifted to the longer wavelength side due to piezoelectric polarization and it is difficult to shorten the emission wavelength.
  • the emission wavelength changes depending on the injection current, the wavelength is shortened when the injection current is low, and the wavelength is increased when the injection current is high, and wavelength control is difficult. there were.
  • These phenomena are known as quantum confined Stark effect (QCSE), and strained quantum wells such as InGaN on the c-plane of GaN grown on the c-plane of a sapphire substrate or the like in a hexagonal III-V group nitride semiconductor.
  • QCSE quantum confined Stark effect
  • strained quantum wells such as InGaN on the c-plane of GaN grown on the c-plane of a sapphire substrate or the like in a hexagonal III-V group nitride semiconductor.
  • a polarization electric field due to compressive strain does not occur in the InGaN layer formed on the nonpolar surface of GaN. Therefore, it is considered that the quantum confined Stark effect that causes a wavelength shift due to a decrease in light emission efficiency or an increase in injection current can be avoided. Furthermore, in the semipolar plane where the polarity is lower than that of the polar plane (that is, the c plane) (that is, the polarization in the direction perpendicular to the plane is reduced compared to the c plane), the polarization electric field due to the compressive strain is reduced depending on the degree of polarity. Accordingly, the quantum confined Stark effect is reduced correspondingly.
  • Ga atoms and N atoms are equally contained in the plane as in the a plane and the m plane. Both the a-plane and the m-plane are perpendicular to the c-plane.
  • Ga atoms and N atoms are included in the plane in an unequal number. The appearance of nonpolar planes and semipolar planes has been reported in documents such as Journal of Applied Physics 100, 023522 (2006).
  • III-V nitride layer having a nonpolar plane or a semipolar plane as a growth plane is effective for improving the performance of the light emitting device.
  • conventional attempts to epitaxially grow III-V nitride layers on nonpolar or semipolar surfaces have high threading dislocation density and stacking fault density, and until recently, high-quality III-V nitride semiconductor stacks The structure could not be obtained.
  • Patent Document 1 International Publication WO2005 / 006420 discloses that GaN or In x Ga 1-x N (0 ⁇ x ⁇ 0.4) was grown on a c-plane ZnO substrate by the PLD method. Are listed.
  • Patent Document 2 International Publication WO2007 / 119433
  • a III-V nitride layer having excellent crystallinity was grown for the first time on nonpolar surfaces such as m-plane and a-plane by PLD method. It is disclosed.
  • the PLD method is an effective growth method for obtaining good crystals.
  • minute group III element droplets adhere to the thin film.
  • liquid droplets adhere to the film surface, there are problems in that the manufacturing yield decreases and the usable area in the substrate is limited.
  • Non-Patent Document 1 Preliminary Proceedings of the 68th Japan Society of Applied Physics (Fall 2007) 4a-ZR-8 ⁇ includes an AlN / GaN thin film on a c-plane ZnO substrate with a pulse frequency of 10 kHz and a pulse duty ratio of 5%. It is described that it has grown.
  • Non-Patent Document 2 (Fujioka “Flexible Device” Project Research Summary, issued on March 4, 2008), an AlN thin film was grown on a c-plane ZnO substrate with a pulse frequency of 1 kHz and a pulse duty ratio of 5%. It is described.
  • the thin film crystal obtained under these growth conditions is not suitable for use in a semiconductor device because the crystallinity is likely to deteriorate due to the increase in film thickness and the content of impurities is large.
  • Patent Document 2 discloses that “another layer” can be further formed on the GaN layer grown on the ZnO substrate by the PLD method.
  • a first conductivity type cladding layer for example, a light emitting layer including a superlattice layer and a second conductivity type cladding layer thereon.
  • ZnO has a lattice constant in the a-axis and m-axis directions that is 1.9% larger than that of GaN at room temperature, and has a larger coefficient of thermal expansion, so cracks may occur in the GaN layer when deposited at a relatively high temperature. there were. Even if the GaN layer is formed under conditions that do not cause cracks, there is a problem that the GaN layer is likely to crack when heated when forming a light-emitting device structure on it as a template substrate. . These problems are particularly noticeable when a nonpolar surface such as an m-plane or a-plane is used as a growth surface.
  • Patent Document 3 particularly Claim 1
  • Patent Document 4 particularly Claim 1
  • Patent Document 5 particularly Claim 2
  • a substrate such as ZnO is contacted with In x Al y on the substrate.
  • a semiconductor light emitting device having a buffer layer made of Ga (1-xy) N is described.
  • these documents do not describe a structure that can be used as a template substrate having a GaN layer as the outermost surface, and do not describe a structure that can solve the problem of thermal expansion of ZnO.
  • An object of at least one of the inventions disclosed in the present application is to provide a method for producing a compound epitaxial layer in which there are almost no droplets that lower the production yield, or at least the generation of droplets is sufficiently reduced as compared with the prior art.
  • it is to provide a method capable of producing a hexagonal III-V nitride layer having high quality crystallinity capable of improving the characteristics of a semiconductor device such as a light emitting element as a compound epitaxial layer.
  • Another object of the invention disclosed in the present application is to provide a practical laminated structure as a template substrate capable of forming a light emitting device structure or the like.
  • the present invention can be broadly divided into three modes (hereinafter referred to as a first invention, a second invention, and a third invention). That is, the first invention is a method of forming a compound epitaxial layer on a ZnO substrate, (A) The angle formed between the growth surface of the ZnO substrate and the ⁇ 0001 ⁇ plane is 10 ° or more, (B) All or part of the elements for forming the compound epitaxial layer are intermittently supplied to the growth surface on the substrate, and at that time, an arbitrary supply duration Ton in the intermittent supply sequence (Sec) and the supply stop time Toff (sec) until the next element supply is expressed by the formula (A-1): (A-1) 1 ⁇ 10 ⁇ 6 sec ⁇ Toff ⁇ 1 ⁇ 10 ⁇ 2 sec 1 ⁇ 10 ⁇ 6 sec ⁇ Ton ⁇ 1 ⁇ 10 ⁇ 2 sec
  • the present invention relates to a method for producing a compound epitaxial layer, characterized in that crystal growth is performed by supplying the gas to satisfy the above
  • the second invention is a method of forming a compound epitaxial layer on a ZnO substrate,
  • A) The growth surface of the ZnO substrate is a ⁇ 0001 ⁇ plane;
  • B) All or part of the elements for forming the compound epitaxial layer are intermittently supplied to the growth surface on the substrate, and at that time, an arbitrary supply duration Ton in the intermittent supply sequence (Sec) and the supply stop time Toff (sec) until the next element supply are expressed by the logical formula: (B-1) and ⁇ (B-2) or (B-3) or (B-4) ⁇ ⁇ However, (B-1) to (B-4) are expressed by the following equations.
  • the present invention relates to a method for producing a compound epitaxial layer, characterized in that crystal growth is performed by supplying the gas to satisfy the above condition.
  • the third invention is a semiconductor multilayer structure having a ZnO substrate and a III-V nitride epitaxial layer formed by epitaxial growth directly on the ZnO substrate,
  • the III-V nitride epitaxial layer is composed of a first layer to an nth layer having different compositions, where n is an integer of 3 or more, and the nth layer is a layer substantially composed of GaN.
  • the present invention relates to a semiconductor multilayer structure.
  • a method for manufacturing a compound epitaxial layer in which there are almost no droplets that reduce the manufacturing yield, or at least the generation of droplets is sufficiently reduced as compared with the prior art. be able to.
  • a method capable of manufacturing a hexagonal group III-V nitride layer having high-quality crystallinity capable of improving the characteristics of a semiconductor device such as a light emitting element as a compound epitaxial layer.
  • the third invention of the present application it is possible to provide a semiconductor multilayer structure that has a GaN layer in the surface layer and is less likely to generate cracks due to thermal expansion.
  • This semiconductor laminated structure can be suitably used as a template substrate on which a light emitting device structure or the like is formed.
  • FIG. 10 shows examples of differential interference microscope images of the crystal film surface where droplets were observed as in Comparative Example A-2, Comparative Example A-3, and Comparative Example B-2.
  • FIG. 17 shows an example of a differential interference microscope image of the crystal film surface where cracks were observed in Comparative Example C-1.
  • a method for forming a compound epitaxial layer on a ZnO substrate comprising: (A) The angle formed between the growth surface of the ZnO substrate and the ⁇ 0001 ⁇ plane is 10 ° or more, (B) All or part of the elements for forming the compound epitaxial layer are intermittently supplied to the growth surface on the substrate, and at that time, an arbitrary supply duration Ton in the intermittent supply sequence (Sec) and the supply stop time Toff (sec) until the next element supply is expressed by the formula (A-1): (A-1) 1 ⁇ 10 ⁇ 6 sec ⁇ Toff ⁇ 1 ⁇ 10 ⁇ 2 sec 1 ⁇ 10 ⁇ 6 sec ⁇ Ton ⁇ 1 ⁇ 10 ⁇ 2 sec A method for producing a compound epitaxial layer, characterized in that crystal growth is performed by supplying the material so as to satisfy the above.
  • a method for forming a compound epitaxial layer on a ZnO substrate comprising: (A) a step of preparing a ZnO substrate having a main surface with an angle of 10 ° or more with respect to the c-plane; (B) a step of intermittently exciting a raw material source containing all or part of the elements for forming the compound epitaxial layer by a DC sputtering method and supplying the source to the growth surface on the substrate intermittently;
  • a method for producing a compound epitaxial layer comprising:
  • the supply amount per hour of the element in an arbitrary supply stop time Toff (sec) is 10% or less with respect to the maximum supply amount per hour of the element in the immediately preceding supply continuation time Ton (sec). 6.
  • the compound epitaxial layer includes a material selected from the group consisting of GaN, InN, AlN, InGaN, AlGaN, InAlN, and AlInGaN.
  • 21 A semiconductor multilayer structure comprising the compound epitaxial layer according to any one of 18 to 20 above and a ZnO substrate used for growth.
  • a semiconductor multilayer structure characterized by having another layer on the compound epitaxial layer described in any one of 18 to 20 above.
  • a method for forming a compound epitaxial layer on a ZnO substrate comprising: (A) The growth surface of the ZnO substrate is a ⁇ 0001 ⁇ plane; (B) All or part of the elements for forming the compound epitaxial layer are intermittently supplied to the growth surface on the substrate, and at that time, an arbitrary supply duration Ton in the intermittent supply sequence (Sec) and the supply stop time Toff (sec) until the next element supply are expressed by the logical formula: (B-1) and ⁇ (B-2) or (B-3) or (B-4) ⁇ ⁇ However, (B-1) to (B-4) are expressed by the following equations.
  • the supply amount per hour of the element in an arbitrary supply stop time Toff (sec) is 10% or less with respect to the maximum supply amount per hour of the element in the immediately preceding supply continuation time Ton (sec). 5.
  • the production method according to any one of 4 above.
  • the compound epitaxial layer includes a material selected from the group consisting of GaN, InN, AlN, InGaN, AlGaN, InAlN, and AlInGaN.
  • a compound epitaxial layer formed on a ZnO substrate having a ⁇ 0001 ⁇ plane as a growth plane A compound epitaxial layer characterized in that the number of droplets present in an arbitrary square section having a side of 500 ⁇ m on the surface of the uppermost layer observed with an optical microscope is 0 or more and 50 or less.
  • a semiconductor multilayer structure comprising the compound epitaxial layer according to any one of 12 to 14 above and a ZnO substrate used for growth.
  • a semiconductor multilayer structure comprising another layer on the compound epitaxial layer according to any one of 12 to 14 above.
  • a semiconductor multilayer structure having a ZnO substrate and a III-V nitride epitaxial layer formed by epitaxial growth directly on the ZnO substrate,
  • the III-V nitride epitaxial layer is composed of a first layer to an nth layer having different compositions, where n is an integer of 3 or more, and the nth layer is a layer substantially composed of GaN.
  • a semiconductor laminated structure characterized by that.
  • the number of cracks existing in an arbitrary square section having a side of 500 ⁇ m on the surface of the n layer is 40 or less.
  • a semiconductor multilayer structure wherein another layer is formed on the semiconductor multilayer structure according to any one of 1 to 12 above.
  • a semiconductor light-emitting device wherein another layer including a light-emitting device structure is formed on the semiconductor multilayer structure according to any one of 1 to 12 above.
  • a semiconductor light-emitting device wherein another layer including a light-emitting device structure is formed on the semiconductor multilayer structure according to any one of 1 to 12 above, and a ZnO substrate is removed from the semiconductor multilayer structure.
  • the c-axis orthogonal to these is not equal in length to the a-axis group.
  • the orientation in a completely regular hexagonal plane can be specified by only two of the a 1 axis, the a 2 axis, and the a 3 axis, but another axis is introduced to maintain symmetry. So they are not independent of each other.
  • One parallel plane group is expressed as (ijkl (el)), which is the distance from the origin at the point where the first plane cuts from the origin to the a 1 axis, a 2 axis, a 3 axis, and c axis.
  • ijkl (el) is the distance from the origin at the point where the first plane cuts from the origin to the a 1 axis, a 2 axis, a 3 axis, and c axis.
  • i, j, and k have rotational symmetry, but l (el) is independent.
  • Equivalent plane orientation refers to the plane orientation that can be reached by all symmetry operations that the crystal system allows.
  • ⁇ 1-100 ⁇ is an expression that collectively represents all the planes equivalent to (1-100), and (1-100) is reached by a rotation operation with the c axis as the rotation axis (10-10).
  • (01-10), ( ⁇ 1100), ( ⁇ 1010), and (0-110) are expressed in total.
  • crystal orientation (crystal axis) is expressed by a set of indices that are the same as the indices of the plane perpendicular to it. Individual crystal orientations are expressed in square brackets [], and a set of equivalent orientations uses key brackets ⁇ >.
  • ⁇ 1-100 ⁇ is sometimes referred to as an m-plane
  • ⁇ 1-100> is sometimes referred to as an m-axis.
  • Typical plane orientations of the hexagonal system are expressed as c-plane (0001), a-plane (11-20), m-plane (1-100), r-plane (10-12).
  • the surface is perpendicular to the c-plane ⁇ 0001 ⁇ plane.
  • Typical surfaces include m-plane ⁇ 1-100 ⁇ plane, a-plane ⁇ 11-20 ⁇ plane, ⁇ 12-30 ⁇ plane, ⁇ 13-40 ⁇ plane, and the like.
  • Nitride crystals grown by heteroepitaxial growth with lattice mismatch have a mosaic property, and columnar crystal grains having slightly different crystal orientations gather to form a film.
  • This mosaicism is a reflection of crystal defects such as dislocations and point defects observed at the atomic level. Columnar crystal grains with few dislocations are bonded to each other through a grain boundary, and dislocations exist at the grain boundary.
  • the X-ray diffraction method is widely used as a technique for macroscopically evaluating the mosaic property.
  • a crystal having a mosaic property includes regions having slightly different plane orientations in the crystal.
  • such a crystal has a reciprocal lattice point spreading in a spherical direction centered on the origin. Therefore, if the extent of this spherical direction is measured by X-ray diffraction, the degree of fluctuation of the plane orientation can be evaluated.
  • the angle (2 ⁇ ) between the incident X-ray and the detector is fixed at the diffraction peak position, and the angle ( ⁇ ) between the sample crystal and the incident X-ray is scanned near the diffraction condition.
  • the spread of spherical reciprocal lattice points centered at the origin in the reciprocal lattice space can be evaluated as the distribution of diffraction intensity.
  • Such measurement is called X-ray rocking curve (XRC) or ⁇ mode (scan) measurement, and the width of the measured diffraction peak reflects the degree of fluctuation of the plane orientation, and is used as a quantitative index (half value) Full width).
  • XRC X-ray rocking curve
  • scan ⁇ mode
  • the full width at half maximum measured in this way indicates that the smaller the value, the higher the quality of the sample crystal and the crystallographically superior crystal.
  • the mosaic property of the thin film crystal is related to the growth direction, and can be divided into fluctuation of the crystal axis growth direction called tilt and rotation of the crystal about the crystal growth direction called twist.
  • tilt and rotation of the crystal By appropriately selecting the diffractive surface and the rotation axis of the crystal, it is possible to separate tilt and twist in X-ray rocking curve measurement.
  • the tilt and the twist are not necessarily the same size.
  • the magnitude of the tilt is extremely small, but the magnitude of the twist may be extremely large.
  • Such a nitride layer has remarkably poor light emission characteristics and electrical characteristics, and it is difficult to produce a practical light-emitting device using such a nitride layer.
  • the nitride layer is used for a light emitting device, it is desirable that each of the tilt and the twist is small.
  • the expression of tilt and twist using X-ray rocking curve measurement can be performed in a plurality of ways by selecting the diffraction plane and the X-ray incident direction.
  • ZnO substrate a predetermined ZnO substrate is first prepared.
  • the ZnO substrate to be used is selected as follows in the first to third inventions.
  • the growth surface of the ZnO substrate that is, the substrate surface on which the compound epitaxial layer is crystal-grown is the main surface of the substrate, and the angle formed with the ⁇ 0001 ⁇ plane is 10 ° or more. Is selected so as to have a plane orientation.
  • the main surface of the ZnO substrate is selected so as to coincide with the planned crystal growth plane orientation.
  • the principal surface of the substrate is allowed to deviate from the complete perpendicular to the crystal orientation axis of the crystal to be grown, and the axis perpendicular to the principal surface is within a range of less than 10 ° from the crystal orientation, preferably It may be shifted within a range of up to 5 °.
  • the growth surface of the ZnO substrate that is, the substrate surface on which the compound epitaxial layer is crystal-grown is the main surface of the substrate, and the plane orientation is selected so as to be the ⁇ 0001 ⁇ plane.
  • the main surface of the ZnO substrate is selected so as to coincide with the planned growth plane orientation ⁇ 0001 ⁇ plane.
  • the principal surface of the substrate is allowed to deviate from the complete perpendicular to the crystal orientation axis of the crystal to be grown, and the axis perpendicular to the principal surface is within a range of 15 ° from the crystal orientation, preferably It may be shifted within a range of up to 5 °.
  • the plane orientation of the III-V nitride epitaxial layer (hereinafter sometimes simply referred to as an epitaxial layer) grown on the ZnO substrate.
  • the plane orientation of the main surface of the ZnO substrate is selected so as to have a predetermined growth surface.
  • the main surface of the ZnO substrate is selected so as to coincide with the planned growth plane orientation.
  • the main surface of the substrate is deviated from perfect perpendicular to the crystal orientation axis, and is perpendicular to the main surface.
  • the axis may be offset from the crystal orientation in the range up to 15 °, preferably in the range up to 5 °.
  • the ⁇ 0001 ⁇ plane (c-plane) is a polar plane, which is useful in that the crystal growth is relatively easy and the device is easily manufactured.
  • the planes having an angle of 10 ° or more with respect to the ⁇ 0001 ⁇ plane are a semipolar plane and a nonpolar plane.
  • Representative surfaces include m-plane ⁇ 1-100 ⁇ plane, a-plane ⁇ 11-20 ⁇ plane, ⁇ 12-30 ⁇ , ⁇ 13-40 ⁇ plane, etc., preferably m-plane and a-plane
  • the m-plane is preferable.
  • the a-plane is also preferable from the viewpoint of processability such as surface polishing of the substrate.
  • the growth plane is preferably a plane in which the a-plane ⁇ 11-20 ⁇ plane or the m-plane ⁇ 10-10 ⁇ plane is inclined in the c-axis direction.
  • the ZnO substrate surface is flat.
  • the surface roughness Ra is preferably 3 nm or less, more preferably 2 nm or less, and even more preferably 1.7 nm or less.
  • Ra represents arithmetic average roughness, and is an average value of absolute values of deviations from the arithmetic average value. Since the method for obtaining a flat substrate surface varies depending on the substrate material and the plane orientation, it is preferable to adopt an appropriate method in each case so as to satisfy the above-mentioned surface roughness. In general, it is preferable to first sufficiently flatten by mechanical polishing.
  • a c-plane or m-plane ZnO substrate In an embodiment using a c-plane or m-plane ZnO substrate, it is preferable to anneal at a high temperature of 800 ° C. or higher. In general, the temperature is 1600 ° C. or lower. Specifically, a ZnO substrate having a mechanically polished ⁇ 0001 ⁇ plane or ⁇ 1-100 ⁇ plane as a main surface is surrounded by a ZnO sintered body in a high-temperature oven controlled at a temperature of 800 ° C. or higher. Is heated in a box shape.
  • the ZnO substrate only needs to be surrounded by the ZnO sintered body, and it is not essential to enclose the entire ZnO substrate by the surrounding sintered body.
  • a crucible made of a ZnO sintered body may be prepared and a ZnO substrate may be installed therein. Since the purpose of surrounding ZnO is to suppress the escape of Zn having a relatively high vapor pressure, it may be surrounded by a material containing Zn in addition to the ZnO sintered body.
  • a material containing Zn for example, a ZnO single crystal may be used, or a Zn plate may be used.
  • a flat ZnO substrate By heating the ZnO substrate based on the above conditions, a flat ZnO substrate can be applied as a crystal growth substrate at the atomic layer level where atomic steps are formed, and a good thin film can be grown. It becomes.
  • annealing may not be required.
  • the surface of the ZnO substrate is first mechanically polished (including chemical mechanical polishing), and may be sufficiently flattened so that the surface roughness is within this range. If it is sufficiently planarized, there is no need for subsequent annealing. However, in order to improve the flatness, annealing may be performed in order to reduce fine scratches and the like, and it is usually preferable to anneal within the range where the above smoothness is obtained.
  • a ZnO substrate having a surface roughness Ra of 3 nm or less, preferably 2 nm or less, more preferably 1.7 nm or less is prepared.
  • the surface of the ZnO substrate is first mechanically polished (including chemical mechanical polishing), but it is preferable that the ZnO substrate surface be sufficiently flattened so that the surface roughness is within the above range. If it is sufficiently planarized, there is no need for subsequent annealing. However, in order to improve the flatness, annealing may be performed in order to reduce fine scratches and the like, and it is usually preferable to anneal within the range where the above smoothness is obtained.
  • a temperature of less than 1150 is preferable, more preferably less than 1100 ° C., and particularly preferably 950 ° C. or less.
  • it processes normally at 700 degreeC or more Preferably it is 800 degreeC or more.
  • the annealing method is the same as that for the m-plane ZnO substrate described above.
  • annealing at a high temperature may cause a texture to appear, and rather the planarity may deteriorate.
  • a sufficiently flat substrate is prepared from the beginning, or annealing is performed within a range that does not impair the flatness. Annealing can recover surface scratches and the like, and can be performed as necessary.
  • the r-plane may be annealed at a high temperature, for example, at a temperature exceeding 1300 ° C., even if the r-plane is annealed at a high temperature, since the texture is not easily generated on the surface.
  • annealing is performed at a temperature within a range where the flatness is not impaired.
  • annealing can be performed at a temperature of 1150 ° C. or lower. When annealing, it is generally 700 ° C. or higher, preferably 800 ° C. or higher.
  • the growth plane may be a substantially polar plane having an angle of less than 10 ° with the ⁇ 0001 ⁇ plane (c plane) which is a polar plane and the ⁇ 0001 ⁇ plane.
  • the c-plane has a relatively large lattice mismatch between ZnO and GaN, but is isotropic. Therefore, the difference in thermal expansion is uniformly generated in the plane, so that the GaN layer is hardly cracked.
  • the third invention is significant particularly when the growth surface is a semipolar surface or a nonpolar surface.
  • a more preferable application scene is when the growth surface is a nonpolar surface.
  • Particularly preferred application scenes are the m-plane and the a-plane. In general, the device characteristics are excellent in the m-plane, so that the present invention is most effective in the m-plane.
  • the compound semiconductor for crystal growth is preferably a compound semiconductor belonging to the hexagonal system, and more preferably a group III-V nitride.
  • a particularly suitable compound semiconductor is a group III-V nitride semiconductor represented by In x Al y Ga (1-xy) N (0 ⁇ x ⁇ 1, 0 ⁇ y ⁇ 1, 0 ⁇ x + y ⁇ 1). It is. Specifically, they are GaN, InN, AlN, InGaN, AlGaN, InAlN, and AlInGaN (the composition ratio in the mixed crystal is omitted).
  • All or a part of the elements for forming the compound epitaxial layer are intermittently supplied.
  • it is necessary to supply all of the constituent elements but it may mean that only some elements may be supplied intermittently. More specifically, it means that all or part of the constituent raw materials are intermittently excited.
  • group III-V nitrides it is generally preferred that all group III elements are supplied intermittently.
  • the group III elements may be fed continuously (preferably at a slow feed rate).
  • the group V element when nitrogen is supplied to the apparatus as a gas, it exists in the vicinity of the substrate growth surface in a gaseous state (molecules, radicals, ions), and therefore, it may not be intentionally supplied intermittently.
  • the N element can be supplied intermittently by exciting the raw material containing N, preferably a group III-V nitride, as will be described later.
  • the V group element may be supplied by exciting the raw material intermittently, the V group element raw material may be present in the atmosphere, or another raw material at the same time while the V group element raw material is present in the atmosphere. May be intermittently excited and supplied. Further, when a plurality of elements are intermittently supplied, the timing at which the plurality of elements are supplied may or may not be the same.
  • FIG. 3 shows a set of the k-th supply period, the subsequent k-th suspension period, and the preceding and subsequent supply periods and suspension periods.
  • an arbitrary supply duration Ton (sec) in such an intermittent supply sequence and a supply stop time Toff (sec) until the next element supply are expressed by the following formula (A-1): (A-1) 1 ⁇ 10 ⁇ 6 sec ⁇ Toff ⁇ 1 ⁇ 10 ⁇ 2 sec 1 ⁇ 10 ⁇ 6 sec ⁇ Ton ⁇ 1 ⁇ 10 ⁇ 2 sec Supply to satisfy. In this case, all Ton and all Toff satisfy the relationship (A-1).
  • the element supply rate per hour (ie, supply rate) during any pause in an intermittent supply sequence is the maximum value of the element supply rate (ie, supply rate) per hour during the immediately preceding supply period. (That is, 10% or less of the maximum supply rate), preferably 5% or less, more preferably 3% or less, and preferably 0%.
  • the graph of FIG. 4A is a coordinate in which the horizontal axis represents the supply duration time Ton (sec) and the vertical axis represents the supply stop time Toff (sec) on a logarithmic scale.
  • the formula (A-1) is a range indicated by a solid line square.
  • the growth by the conventional PLD method for example, the PLD method using a KrF excimer laser as an excitation source has a shorter supply continuation time than the first invention as shown in FIG. 4A.
  • the PLD method a large amount of elements are excited by a high-intensity excitation source during a short supply duration, so that the excited elements are easily supplied excessively.
  • the particles scattered in a lump form are mixed, and droplets are generated on the growth surface.
  • the first invention by setting the supply continuation period longer than in the PLD method, a large amount of elements are not excited and supplied instantaneously, but the elements are mildly excited and supplied for a relatively long period. To do. Therefore, only the elements required for growth are supplied during the supply period, and the supplied elements are taken in while migrating to the growth surface without any excess, and it is good that they migrate sufficiently during the next rest period It is estimated that a fresh crystal is growing.
  • the energy required to excite the raw material source is preferably 1 ⁇ 10 5 W or less in terms of average energy per second, preferably 1 ⁇ 10 4 W.
  • the following is more preferable, and 2 ⁇ 10 3 W or less is most preferable.
  • 1 ⁇ 10 2 W or more is preferable.
  • the energy required to excite the raw material source is greater than 1 ⁇ 10 5 W, typically around 2 ⁇ 10 5 W, in terms of average energy per second.
  • Ton If the supply duration Ton (sec) is too short, in order to obtain a practical film forming rate, a large energy must be instantaneously applied to increase the supply rate during the supply period. Droplets are likely to occur as in the PLD method.
  • Ton if Ton is too long, there may be a case where the Toff time that allows sufficient migration cannot be taken. If the rest period Toff (sec) is too short, it will be difficult to obtain a good crystal due to insufficient migration time, and if it is too long, it will be easy to take in impurities. It will be difficult to continue. For example, in DC sputtering described later, there is a problem that the plasma cannot be maintained when the pause time is long.
  • an arbitrary supply duration Ton (sec) and a supply stop time Toff (sec) until the next element supply are expressed by the following relational expression (A-3): (A-3) 1 ⁇ 10 ⁇ 5 sec ⁇ Toff ⁇ 5 ⁇ 10 ⁇ 3 sec 1 ⁇ 10 ⁇ 6 sec ⁇ Ton ⁇ 5 ⁇ 10 ⁇ 3 sec It is preferable to supply the element so as to satisfy the above.
  • the non-polar surface has a lower surface dangling bond density and lower surface energy than the polar surface.
  • the low surface energy means that the element that reaches the surface can move freely, but the bond with the underlying crystal is weak, so the fluctuation of the crystal tends to increase, and it is difficult to grow high-quality crystals.
  • excellent crystallinity is brought about. Therefore, it can be understood that the intermittent supply of the first invention is particularly suitable for the growth of semipolar to nonpolar surfaces.
  • Ton / (Ton + Toff) is called a duty ratio.
  • Ton k / (Ton k + Toff k ) will be described with reference to FIG. Satisfies formula (A-2) and formula (A-4), and Ton (k-1) / (Ton (k-1) + Toff (k-1) ) and Ton (k + 1) / (Ton (k + 1) + Toff (k + 1) ) also means that the expressions (A-2) and (A-4) are satisfied.
  • Ton k , Ton (k ⁇ 1) and Ton (k + 1) may be different, and Toff k , Toff (k ⁇ 1) and Toff (k + 1) may be different.
  • (B-1) to (B-4) are expressed by the following equations.
  • (B-1) 1 ⁇ 10 ⁇ 6 sec ⁇ Toff ⁇ 1 ⁇ 10 ⁇ 2 sec 1 ⁇ 10 ⁇ 6 sec ⁇ Ton ⁇ 1 ⁇ 10 ⁇ 2 sec
  • (B-2) 2 ⁇ 10 ⁇ 3 sec ⁇ Toff ⁇ 1 ⁇ 10 ⁇ 2 sec (B-3) 0.01% ⁇ Ton / (Ton + Toff) ⁇ 5%
  • (B-4) 1 ⁇ 10 ⁇ 6 sec ⁇ Toff ⁇ 5 ⁇ 10 ⁇ 5 sec 1 ⁇ 10 ⁇ 6 sec ⁇ Ton ⁇ 5 ⁇ 10 ⁇ 5 sec
  • the element supply rate per hour (ie, supply rate) during any pause in an intermittent supply sequence is the maximum value of the element supply rate (ie, supply rate) per hour during the immediately preceding supply period. (That is, 10% or less of the maximum supply rate), preferably 5% or less, more preferably 3% or less, and preferably 0%.
  • the graph of FIG. 4B is a coordinate in which the horizontal axis represents the supply duration time Ton (sec) and the vertical axis represents the supply stop time Toff (sec) on a logarithmic scale.
  • a range satisfying the conditions of the second invention is indicated by hatching in FIG. 4B.
  • the growth by the conventional PLD method for example, the PLD method using a KrF excimer laser as an excitation source has a shorter supply continuation time than the second invention, as shown in FIG. 4B.
  • the PLD method a large amount of elements are excited by a high-intensity excitation source during a short supply duration, so that the excited elements are easily supplied excessively.
  • the particles scattered in a lump form are mixed, and droplets are generated on the growth surface.
  • the second invention sets the supply duration longer than that of the PLD method, so that a large amount of elements are not excited and supplied instantaneously, but the elements are mildly excited and supplied for a relatively long period of time. To do. Therefore, only the elements required for growth are supplied during the supply period, and the supplied elements are taken in while migrating to the growth surface without any excess, and it is good that they migrate sufficiently during the next rest period It is estimated that a fresh crystal is growing.
  • the energy required to excite the raw material source is preferably 1 ⁇ 10 5 W or less in terms of average energy per second, preferably 1 ⁇ 10 4 W.
  • the following is more preferable, and 2 ⁇ 10 3 W or less is most preferable.
  • 1 ⁇ 10 2 W or more is preferable.
  • the energy required to excite the raw material source is greater than 1 ⁇ 10 5 W, typically around 2 ⁇ 10 5 W, in terms of average energy per second.
  • Ton If the supply duration Ton (sec) is too short, in order to obtain a practical film forming rate, a large energy must be instantaneously applied to increase the supply rate during the supply period. Droplets are likely to occur as in the PLD method.
  • Ton if Ton is too long, there may be a case where the Toff time that allows sufficient migration cannot be taken. If the rest period Toff (sec) is too short, it will be difficult to obtain a good crystal due to insufficient migration time, and if it is too long, it may be difficult to continue film formation depending on the film formation method. . For example, in DC sputtering described later, there is a problem that the plasma cannot be maintained when the pause time is long. For this reason, at least the formula (B-1) needs to be satisfied.
  • condition (B-1) may be insufficient in terms of crystallinity, impurity content, etc., and the conditions (B-2) to (B-4) At least one of the must be further satisfied.
  • the formula (B-2) (B-2) 2 ⁇ 10 ⁇ 3 sec ⁇ Toff ⁇ 1 ⁇ 10 ⁇ 2 sec
  • the range satisfying the formula (B-1) at the same time is a range (square range) where Toff is particularly large among the ranges satisfying (B-1).
  • the c-plane as a growth plane has a short element migration length, and therefore, good crystallinity may not be obtained within the range satisfying (B-1).
  • the pause time is sufficiently long, so that migration proceeds and a good crystal can be obtained.
  • Formula (B-3) (B-3) 0.01% ⁇ Ton / (Ton + Toff) ⁇ 5% Defines the ratio of time between Ton and Toff. Ton / (Ton + Toff) is called a duty ratio.
  • the range that satisfies the formula (B-3) and the formula (B-1) at the same time is, as shown in FIG. 4B, the upper left triangle range within the square range that satisfies (B-1).
  • Ton k / (Ton k + Toff k ) is expressed by the expression (B ⁇ 3)
  • Ton (k ⁇ 1) / (Ton (k ⁇ 1) + Toff (k ⁇ 1) ) and Ton (k + 1) / (Ton (k + 1) + Toff (k + 1) ) are also expressed by the equation (B ⁇ 3) Satisfies.
  • Ton k , Ton (k ⁇ 1) and Ton (k + 1) may be different
  • Toff k , Toff (k ⁇ 1) and Toff (k + 1) may be different.
  • Ton needs to be shortened according to Toff.
  • the range satisfying (B-4) is a range in which Ton is short and Toff is short. In this range, the impurity concentration in the film is reduced while suppressing the influence of the deterioration of crystallinity due to the short Toff as much as possible. Can do.
  • the above intermittent supply conditions are satisfied for at least the main elements.
  • the supply of at least the element having the largest composition ratio among the plurality of group III elements satisfies the above intermittent supply conditions.
  • the remaining group III elements may be (i) intermittently supplied so as to satisfy the conditions of the present invention, (ii) intermittently supplied under conditions that do not satisfy the conditions of the present invention, or (iii) continuous. May be supplied automatically.
  • the supply of all group III elements satisfies the intermittent supply conditions of the present invention as described above. In this case, intermittent supply conditions such as Ton and Toff may be different for each element.
  • any device may be used as long as intermittent supply of elements as described above can be performed.
  • a method of exciting a target intermittently (hereinafter also referred to as a PSD method) in a DC sputtering method using a DC sputtering apparatus is practically preferable.
  • a group III-V nitride represented by In x Al y Ga (1-xy) N (0 ⁇ x ⁇ 1, 0 ⁇ y ⁇ 1, 0 ⁇ x + y ⁇ 1)
  • the growth by DC sputtering will be described.
  • FIG. 5 is a diagram schematically showing a DC sputtering apparatus.
  • the DC sputtering apparatus 10 includes a chamber 11 that forms a sealed space in order to keep the pressure and temperature of the gas filled inside constant.
  • the pressure in the chamber 11 is controlled to an appropriate pressure reduction by the pressure valve 13 and the vacuum pump 14.
  • the target 21 is preferably a group III metal (including an alloy) or a group III nitride.
  • gallium metal indium metal, aluminum metal, AlGa alloy, InGa alloy, AlInGa alloy, GaN single crystal, InN single crystal, AlN single crystal, GaInN single crystal, AlGaN single crystal, AlInGaN single crystal, GaN sintered Body, InN sintered body, InGaN sintered body, AlGaN sintered body, and AlInGaN sintered body.
  • argon as a sputtering gas and nitrogen as a group V element are introduced from the gas inlet 12.
  • nitrogen gas may not be introduced in some cases, but nitrogen may be introduced.
  • nitrogen as a group V element is supplied to the apparatus by gas and the group III element is a metal or alloy target, only part of the element for forming the compound epitaxial layer is intermittently formed on the growth surface on the substrate. Will be supplied.
  • the substrate holder 15 is grounded in terms of potential.
  • the ZnO substrate 20 is placed on the substrate holder 15 and faces the target 21.
  • the power supply 16 can apply a DC pulse voltage between the substrate holder 15 and the target 21.
  • a magnetron sputtering apparatus in which a permanent magnet is arranged near the target is used.
  • a pulse voltage as shown in FIG. 6 is applied between the target and the substrate holder.
  • the sequence of pulse voltages is matched with the desired supply sequence described above.
  • the element supply sequence can be controlled by the pulse voltage sequence in the DC sputtering method. Therefore, the pulse voltage is preferably periodic.
  • the wave height of the voltage is such that the excitation energy of the raw material source is an average energy per second, usually 1 ⁇ 10 2 W or more and 1 ⁇ 10 5 W or less, more preferably 1 ⁇ 10 4 W or less, Preferably, it is selected to be 2 ⁇ 10 3 W or less.
  • a mixed crystal system such as InGaN
  • a pulse voltage is applied between each target and the substrate.
  • the pulse voltage sequence and wave height are set independently for each target.
  • the element supply rate to the growth surface can also be controlled by restricting the flow of the element from the target to the substrate by the degree of opening and closing of the shutter or the like.
  • the substrate temperature during crystal growth is preferably 800 ° C. or lower (particularly less than 800 ° C.), more preferably 700 ° C. or lower, more preferably 600 ° C. or lower, and most preferably 500 ° C. or lower.
  • the temperature is usually room temperature or higher, preferably 100 ° C. or higher, more preferably 200 ° C. or higher, and most preferably 300 ° C. or higher. Therefore, the range of 300 to 500 ° C. is most preferable.
  • the film formation rate is generally 10 to 500 nm / hour on average, and more preferably 30 to 300 nm / hour.
  • the number of group III element droplets present in an arbitrary square section having a side of 500 ⁇ m is , 50 or less, preferably 30 or less, more preferably 20 or less.
  • the obtained thin film crystal shows good crystallinity, and a clear two-dimensional diffraction streak pattern is observed in the RHEED image as shown in the examples.
  • the X-ray rocking curve measurement of the thin film crystal obtained in the first invention and the second invention is as follows.
  • the first invention for example, in m-plane growth, a thin film crystal in which tilts a 1 , a 2 , and twist b satisfy the following conditions in X-ray rocking curve measurement is obtained.
  • a 1 represents the full width at half maximum (tilt) of the angle dependence of the X-ray diffraction intensity obtained with the (1-100) plane as the measurement plane and the a axis as the rotation axis
  • a 2 represents (1- 100) represents the full width at half maximum (tilt) of the angle dependency of the X-ray diffraction intensity obtained with the measurement surface as the measurement surface and the c-axis as the rotation axis
  • b represents the measurement surface with the (1-102) surface as the measurement surface.
  • a 1 ⁇ 0.15 ° Meet Preferably, a 1 ⁇ 0.15 ° Meet. Also preferably, b ⁇ 0.2 ° And more preferably b ⁇ 0.15 ° Meet.
  • a thin film crystal in which tilt a and twist b satisfy the following conditions is obtained by X-ray rocking curve measurement.
  • a represents the full width at half maximum (tilt) of the angle dependence of the X-ray diffraction intensity obtained with the (0001) plane as the measurement plane and the a axis as the rotation axis
  • b represents the (1-102) plane.
  • the full width at half maximum (twist) of the angle dependency of the X-ray diffraction intensity obtained with the crystal plane in the direction perpendicular to the a-axis as the measurement surface is shown.
  • a ⁇ 0.10 ° Meet Preferably, a ⁇ 0.10 ° Meet.
  • the compound epitaxial layer formed by the manufacturing method of the first invention and the second invention, or the laminated structure of the ZnO substrate and the compound epitaxial layer can be used in various applications, and is provided for forming a device structure thereon.
  • Form as a substrate form as part of a device having a device structure formed thereon, form as part of a device having at least a part of the device structure formed on part of the layer, and other forms Can be taken.
  • the ZnO substrate may be present as it is, or may be removed at an appropriate stage after the layer growth. That is, the final product or intermediate product provided with the compound epitaxial layer grown in the first and second inventions may or may not have the ZnO substrate used in the growth.
  • any “other layer” may be used, and the material may include an insulator. It may have a semiconductor part or a metal part.
  • the formation method includes a hydride vapor phase epitaxy (HVPE) method, a metal organic chemical vapor deposition (MOCVD) method, a plasma chemical vapor deposition (CVD) method, a CVD method such as a thermal CVD method, a molecular beam epitaxy (MBE) method, a sputtering method. Any of a well-known film forming method such as a vapor deposition method and a vapor deposition method, and a PLD method and a PSD method may be used.
  • the formed structure may be a single layer or a multilayer structure, and may be a device structure such as a so-called electronic device or light-emitting device.
  • the layers of the first and second inventions can be used as the underlying layers by using the layers of the first and second inventions as a base.
  • a layer capable of quality is preferred.
  • the compound epitaxial layer is a group III-V nitride layer, and the “other layer” is preferably a group III-V nitride layer having a different composition or formed by a different growth method, for example.
  • the growth method is preferably formed by a film forming method selected from the group consisting of a VPE method, a CVD method, an MBE method, a sputtering method, a vapor deposition method, and a combination of two or more of these methods.
  • the group III-V nitride epitaxial layer grown on the ZnO substrate is composed of n layers having different compositions from the first layer to the nth layer, and the first layer is in direct contact with the ZnO substrate, and adjacent layers are also in contact with each other. It touches.
  • the first to nth layers are formed in substantially the same region on the substrate, and preferably cover the entire main surface of the ZnO substrate. In other words, the (n-1) th layer to the first layer and the ZnO substrate are present below the GaN layer, which is the nth layer.
  • the semiconductor laminated structure of the third invention may be referred to as a III-V nitride epitaxial layer 11 (hereinafter simply referred to as an epitaxial layer 11) on a ZnO substrate having a predetermined plane orientation. )
  • the epitaxial layer 11 includes the first layer 12, the second layer 13,... (The middle layer is omitted), and the n layer of the nth layer 14.
  • n is an integer of 3 or more, and n may theoretically be large, but even if it is larger than necessary, it only takes time.
  • n is generally 3 to 10, preferably 3 to 8, more preferably 3 to 6, and particularly preferably 3 to 5.
  • the nth layer is a layer substantially made of GaN.
  • a GaN layer is preferable, but the range in which lattice mismatch does not substantially affect the epitaxial growth of the GaN layer, and the absolute value of the lattice mismatch rate from GaN is 0.5% or less (preferably 0.3% In the case of In x Ga (1-x) N, x ⁇ 0.044, preferably x ⁇ 0. 026, more preferably x ⁇ 0.008.
  • it is often simply referred to as a “GaN layer”, but precisely, it means a “substantially GaN layer” as defined.
  • the III-V nitride epitaxial layer of the third invention functions as a “buffer layer” in that a light emitting device structure can be formed thereon.
  • the conventional buffer layer is generally provided for relaxing the lattice mismatch, whereas the epitaxial layer of the third invention has a structure for relaxing the stress due to thermal expansion of ZnO having a large thermal expansion coefficient.
  • the epitaxial layer satisfying the configuration of the third invention reduces the occurrence of cracks. Is done.
  • the epitaxial layer 11 is composed of three or more layers, so that the thermal expansion of the ZnO substrate is alleviated.
  • the thickness and composition (lattice constant) of the first to nth layers can be set without particular limitation.
  • the thickness of the epitaxial layer 11 is preferably 0.05 ⁇ m to 1 ⁇ m. This is because if the film thickness is too thin, the lattice mismatch between ZnO and GaN cannot be relaxed and cracks easily occur, and even if the thickness exceeds 1 ⁇ m, there is no difference in the effect of the third invention.
  • the product of a (k ⁇ 1) and Th (k) is (Formula 1): (Formula 1) ⁇ 0.70 ⁇ ⁇ a (k) ⁇ Th (k) ⁇ + 1.20 And more preferably ⁇ 0.50 ⁇ ⁇ a (k) ⁇ Th (k) ⁇ + 1.20.
  • k is an integer of 1 to n
  • a (0) is a lattice constant of the ZnO substrate.
  • the group III-V nitride is selected so that the lattice mismatch rate of the layer becomes small.
  • (Expression 2) 10 nm ⁇ Th (k) ⁇ 200 nm It is preferable to satisfy.
  • Th (k) is too thin, when ⁇ a (k) is large, the lattice mismatch cannot be relaxed, and when the layers are stacked, cracks are likely to occur, and when ⁇ a (k) is small, such Although there is no problem, since ⁇ a (k) ⁇ Th (k) for each layer becomes small, the total number of layers up to the GaN layer and the total film thickness increase, resulting in an increase in material cost and a decrease in manufacturing throughput.
  • the group III-V nitride constituting the first to (n-1) th layers is In x Al y Ga (1-xy) N (0 ⁇ x ⁇ 1, 0 ⁇ y ⁇ 1, 0 ⁇ x + y ⁇ 1).
  • the lattice constant of each layer can be set by changing the composition ratio (values of x and y).
  • the following table shows the lattice constants on the m-plane of GaN, AlN, InN and ZnO.
  • the first to (n ⁇ 1) th layers are preferably formed of In x Ga (1-x) N (0 ⁇ x ⁇ 1), and a desired ⁇ a (k) can be obtained by changing the composition ratio x. Can be set.
  • the In composition ratio of the first layer may be set to less than 0.16, and the In composition ratio x may be decreased sequentially until the (n ⁇ 1) th layer.
  • (Formula 4) (Formula 4) ⁇ a (k)> 0 It is preferable that at least one layer in which is established exists. The existence of this layer, contrary to the concept of lattice mismatch relaxation, means that a (k) of at least one layer is larger than the lattice constant a (k ⁇ 1) of the underlying layer.
  • the semiconductor multilayer structure of the third invention is used as a template substrate, the presence of such a layer when heated can relieve the stress generated even if the ZnO substrate is thermally expanded. As a result, generation of cracks in the nth GaN layer can be prevented.
  • the k-th layer that satisfies the above is preferably the first layer. That is, ⁇ a (1)> 0 Is preferably established. Since the lattice constant of the first layer is larger than that of the ZnO substrate, the stress due to thermal expansion can be most effectively relaxed.
  • the composition of the first layer is selected to be In x Ga (1-x) N (0.16 ⁇ x ⁇ 1).
  • the layer in which (Equation 4) is satisfied is the first layer, and that (Equation 3) is satisfied from the second layer to the n-th layer. That is, the following formula: ⁇ a (1)> 0 ⁇ a (k) ⁇ 0 (where k is an integer from 2 to n) Is preferably established.
  • the semiconductor laminated structure of the third invention is a structure in which the stress of thermal expansion is relaxed, and is used as a template substrate, and withstands the film formation temperature when forming “other layers” such as a light emitting device structure on the substrate. It is expected.
  • the semiconductor multilayer structure of the third invention is the number of cracks existing in an arbitrary square section in which one side of the surface of the n-th layer is 500 ⁇ m after the n-th GaN layer is placed at a temperature of at least 300 ° C. However, it is preferably 40 or less (0 or more), more preferably 20 or less, and particularly preferably 10 or less. Observation can be carried out with a microscope, for example a differential interference microscope.
  • the semiconductor multilayer structure is heated to a temperature condition of at least 300 ° C. to evaluate the occurrence of cracks.
  • the time for which the temperature is left at 300 ° C. is the level required for the entire ZnO substrate to be uniformly heated and sufficiently thermally expanded at that temperature, and is generally about 10 to 20 minutes.
  • a ZnO substrate having a predetermined plane orientation is prepared, and a III-V nitride epitaxial layer is grown on the surface from the first layer to the nth layer.
  • the ZnO substrate has already been described.
  • the growth method of the III-V nitride epitaxial layer from the first layer to the n-th layer is not particularly limited, and any method may be used.
  • each layer from the first layer to the nth layer may be grown by the same method or may be grown by different methods.
  • a growth method that provides a group III-V nitride layer with excellent crystallinity is preferred.
  • a method for providing good crystals a method of intermittently supplying elements constituting the film to the growth surface is preferable.
  • the PLD method pulsesed laser deposition
  • the PSD method pulsed spraying deposition
  • the element supply duration Ton is generally very short compared to the supply stop time Toff until the next element supply.
  • Patent Document 2 International Publication WO2007 / 119433
  • Japanese Patent Application Laid-Open No. 2008-053640 and Japanese Patent Application Laid-Open No. 2008-053703, and is performed according to the description. be able to.
  • the element supply duration Ton can be set longer, so that the excitation of the raw material can be performed mildly, and there is an advantage that the generation of group III element droplets on the growth film surface is small. is there.
  • there are advantages such as being capable of forming a film with a larger area and being industrially easy to implement compared to PLD.
  • the conditions described in the first invention and the second invention can be adopted.
  • the growth plane has a plane orientation in which the angle formed with the ⁇ 0001 ⁇ plane is 10 ° or more
  • the growth plane is preferably grown according to the conditions described in the first invention, and the angle formed by the growth plane with the ⁇ 0001 ⁇ plane. Is preferably in accordance with the conditions described in the second invention.
  • the apparatus described in regard to the first and second inventions can be used.
  • the n layers constituting the III-V nitride epitaxial layer have different compositions.
  • a plurality of targets are set and the target to be excited is selected, or the element supply to the growth surface is controlled by a shutter, so that The composition can be varied.
  • the semiconductor multilayer structure of the third invention is preferably used in a form used as a substrate for forming a device structure thereon, that is, as a template substrate.
  • template substrate includes (i) a laminated structure that is a (semi) finished product that can be stored and / or sold / distributed by itself, and (ii) a laminated structure that appears during a series of manufacturing steps. Both are used to mean.
  • a different aspect of the third invention relates to a semiconductor multilayer structure having “other layers” on the semiconductor multilayer structure configured as described above.
  • the “other layer” may be any material, and the material may include an insulator, a semiconductor portion, or a metal portion.
  • the formation method includes a hydride vapor phase epitaxy (HVPE) method, a metal organic chemical vapor deposition (MOCVD) method, a plasma chemical vapor deposition (CVD) method, a CVD method such as a thermal CVD method, a molecular beam epitaxy (MBE) method, a sputtering method.
  • HVPE hydride vapor phase epitaxy
  • MOCVD metal organic chemical vapor deposition
  • CVD plasma chemical vapor deposition
  • CVD method such as a thermal CVD method
  • MBE molecular beam epitaxy
  • any of a well-known film forming method such as a vapor deposition method and a vapor deposition method, and a PLD method and a PSD method may be used.
  • a vapor deposition method and a vapor deposition method such as a vapor deposition method and a vapor deposition method, and a PLD method and a PSD method may be used.
  • the GaN layer of the surface layer of the semiconductor multilayer structure of the third invention is excellent in crystallinity, even if “other layers” are formed by a highly productive manufacturing method such as VPE method, CVD method, MBE method, etc.
  • VPE method very high productivity method
  • CVD method chemical vapor deposition method
  • MBE method etc.
  • the structure to be formed may be a single layer or a multilayer structure, and may be a device structure such as a so-called electronic device or light-emitting device.
  • the “other layer” directly stacked on the n-th layer (GaN layer) of the semiconductor multilayer structure of the third invention is preferably a layer that lattice matches with GaN or a layer that has a small lattice mismatch.
  • the “other layer” preferably includes at least a part of the light emitting device structure.
  • the light-emitting device structure can adopt a known structure, and is generally a first conductivity type semiconductor layer including at least a first conductivity type cladding layer, an active layer structure, and a second conductivity type semiconductor including a second conductivity type cladding layer. Has a layer.
  • the first conductivity type and the second conductivity type are, for example, n-type and p-type, respectively.
  • the first conductivity type cladding is made of a material having a larger band gap than the light emitting layer such as GaN without forming a special buffer layer.
  • the semiconductor multilayer structure of the third invention can be used as a template substrate suitable for forming a light emitting device structure.
  • the ZnO substrate may exist as it is or may be removed at an appropriate stage after the layer growth. That is, the final product or intermediate product including the III-V nitride epitaxial layer directly epitaxially grown on the ZnO substrate may or may not have the ZnO substrate.
  • Example of First Invention A ZnO substrate having a (1-100) plane (m-plane) having an angle of 90 ° with the (0001) plane as a growth plane was introduced into the deposition apparatus to form a GaN layer.
  • Ga metal was used as a target.
  • a Ga metal target was attached to a magnetron sputter gun and arranged so as to be parallel to the growth surface of the ZnO substrate, and the distance between the ZnO substrate and the Ga metal target was about 6 cm.
  • Ar gas was introduced at 1.0 sccm and nitrogen gas was introduced at 4.0 sccm by a mass flow controller, and the growth pressure was set at 2.0 ⁇ 10 ⁇ 2 Torr.
  • the ZnO substrate is grounded in terms of potential, the voltage of the DC power supply applied between the ZnO substrate and the Ga metal target is ⁇ 607 V, the voltage application time is 5 ⁇ sec, and the voltage application pause time is 95 ⁇ sec.
  • the average energy per second was 668W.
  • Sputtering is performed by temporarily increasing the amount of Ar gas introduced into the growth chamber in a state where the substrate temperature of the ZnO substrate is 320 ° C., and the shutter for blocking the supply of raw materials is arranged in front of the ZnO substrate and on the Ga metal target. After starting the discharge and confirming that the Ar gas amount and the growth pressure were stabilized at the above-mentioned set values, each shutter was opened, and a GaN layer was formed for 30 minutes. The film thickness of the GaN layer was 0.11 ⁇ m.
  • the GaN layer after film formation was observed by RHEED.
  • the observed RHEED image is shown in FIG. 7A. Since a clear two-dimensional diffraction streak pattern was shown, it was found that a single crystal layer having an extremely flat surface state was formed.
  • Ga droplets were not observed and had an excellent surface state.
  • the mosaic property of the crystals of the obtained GaN layer was evaluated by X-ray rocking curve measurement.
  • the measurement is performed by measuring the X-ray rocking curve for evaluating the tilt with the (1-100) plane as the measurement plane and the a-axis and the c-axis as the rotation axes, and the (1-102) plane as the measurement plane and the a-axis.
  • X-ray rocking curve measurement was performed to evaluate twist with the crystal axis in the vertical direction as the rotation axis.
  • Table 3 shows the full width at half maximum of each X-ray rocking curve as a 1 , a 2 , and b.
  • a 1 0.034 °
  • a 2 0.036 °
  • b 0.1.9 °
  • both the tilt and the twist were extremely small and had excellent crystallinity.
  • the impurity concentration of the obtained GaN layer was measured by secondary ion mass spectrometry with the measurement elements H, C, and O.
  • the respective measurement results are shown in Table 4.
  • impurity concentration is low, and quality suitable as a semiconductor Had.
  • Example A-2> The distance between the ZnO substrate and the Ga metal target is ⁇ 10 mm with respect to Example A-1, the introduction amounts of Ar gas and nitrogen gas are 2.0 sccm and 2.5 sccm, respectively, and the growth pressure is 3.7 ⁇ 10 ⁇ 2 Torr.
  • a film was formed in the same manner as in Example A-1, except that the substrate temperature was 357 ° C., the time during which the voltage application was stopped was 900 ⁇ sec, and the average energy per second during the voltage application time was 2200 W.
  • the film thickness of the GaN layer was 0.06 ⁇ m.
  • the RHEED image of the GaN layer after film formation showed a clear two-dimensional streak pattern, indicating that a single crystal layer having an extremely flat surface state was formed.
  • Example A-3> The distance between the ZnO substrate and the Ga metal target is +10 mm with respect to Example A-1, the introduction amounts of Ar gas and nitrogen gas are 0.5 sccm and 3.5 sccm, respectively, and the growth pressure is 2.5 ⁇ 10 ⁇ 2 Torr, The substrate temperature is 317 ° C., the voltage of the DC power source applied between the ZnO substrate and the Ga metal target is ⁇ 455 V, the voltage application pause time is 25 ⁇ sec, and the average energy per second during the voltage application time is 191 W.
  • a film was formed in the same manner as in Example A-1.
  • the film thickness of the GaN layer was 0.11 ⁇ m.
  • the RHEED image of the GaN layer after film formation showed a clear two-dimensional streak pattern, indicating that a single crystal layer having an extremely flat surface state was formed.
  • Ga droplets were not observed and had an excellent surface state.
  • Example A-4> The amounts of Ar gas and nitrogen gas introduced were 2.5 sccm and 2.5 sccm, the growth pressure was 3.6 ⁇ 10 ⁇ 2 Torr, the substrate temperature was 348 ° C., and the DC power source applied between the ZnO substrate and the Ga metal target was used.
  • a film was formed in the same manner as in Example A-1, except that the voltage was ⁇ 592 V, the voltage application time was 50 ⁇ sec, the voltage application suspension time was 950 ⁇ sec, and the average energy per second during the voltage application time was 533 W.
  • the film thickness of the GaN layer was 0.13 ⁇ m.
  • the RHEED image of the GaN layer after film formation showed a clear two-dimensional streak pattern, indicating that a single crystal layer having an extremely flat surface state was formed.
  • Example A-5> A ZnO substrate having a (1-100) plane (m-plane) as a growth plane was introduced into a film forming apparatus to form an InGaN layer.
  • Ga metal and In metal were used as targets.
  • the Ga metal target and the In metal target are each attached to a magnetron sputter gun, the Ga metal target is arranged so as to be parallel to the growth surface of the ZnO substrate, and the In metal target has a normal to the In metal target, which is ZnO. It arrange
  • Ar gas was introduced at 1.0 sccm and nitrogen gas was introduced at 4.0 sccm by a mass flow controller, and the growth pressure was 2.1 ⁇ 10 ⁇ 2 Torr.
  • the ZnO substrate is grounded in terms of potential, the voltage of the DC power supply applied between the ZnO substrate and the Ga metal target is ⁇ 607 V, the voltage application time is 5 ⁇ sec, and the voltage application pause time is 95 ⁇ sec.
  • the average energy per second was 668W.
  • the DC power supply voltage applied between the ZnO substrate and the In metal target is -502 V, the voltage application time is 5 ⁇ sec, the voltage application pause time is 115 ⁇ sec, and the average energy per second during the voltage application time is 120 W. It was.
  • the substrate temperature of the ZnO substrate is set to 330 ° C., and the amount of Ar gas introduced into the growth chamber is temporarily increased in a state where a shutter for blocking the supply of raw materials is arranged in front of the ZnO substrate, the Ga metal target, and the In metal target. Then, sputtering discharge was started, and after confirming that the amount of Ar gas and the growth pressure were stabilized at the above set values, each shutter was opened and an InGaN layer was formed for 30 minutes. The thickness of the InGaN layer was 0.10 ⁇ m.
  • the RHEED image of the GaN layer after film formation showed a clear two-dimensional streak pattern, indicating that a single crystal layer having an extremely flat surface state was formed.
  • Example A-1 Deposition on c-plane Except that the growth surface of the ZnO substrate is the (0001) plane (c-plane), the average energy per second during the voltage application time is 607 W, and the substrate temperature is 316 ° C. A film was formed in the same manner as in Example A-1. The film thickness of the GaN layer was 0.14 ⁇ m.
  • the GaN layer after film formation was observed by RHEED.
  • a two-dimensional diffraction streak pattern similar to that in Example A-1 was also observed, but the portion showing the ring-shaped pattern was also mixed in the growth surface, so that the crystallinity near the surface began to deteriorate. all right.
  • An RHEED image of the observed ring-shaped pattern is shown in FIG.
  • the impurity concentration of the obtained GaN layer was measured by secondary ion mass spectrometry with detection elements as H, C, and O.
  • the respective measurement results are shown in Table 4.
  • a ZnO substrate having a (1-100) plane (m-plane) as a growth surface was introduced into a film formation apparatus to form a GaN layer.
  • Ga metal was used as a target.
  • the Ga metal target was disposed so as to be parallel to the growth surface of the ZnO substrate, and the distance between the ZnO substrate and the Ga metal target was about 7 cm.
  • An RF radical source was used as a nitrogen source at 300 W, and the growth pressure was 3 ⁇ 10 ⁇ 6 Torr.
  • the irradiation time of the pulsed laser light emitted from the KrF excimer laser irradiating the target was repeated as 20 ns, the irradiation pause time was set as 33 ms, and the average energy per second during the irradiation time was set to 6.0 ⁇ 10 5 W.
  • the substrate temperature of the ZnO substrate was 320 ° C., and a GaN layer was formed for 1 hour.
  • the film thickness of the GaN layer was 0.05 ⁇ m.
  • FIG. 9A shows an example of a differential interference microscope image of the crystal film surface where no droplets are observed as in Example A-5.
  • FIG. 10 shows an example of a differential interference microscope image of the crystal film surface where droplets are observed as in Comparative Examples A-2 and A-3.
  • Example of Second Invention A ZnO substrate having a (0001) plane (c-plane) as a growth plane was introduced into the deposition apparatus to form a GaN layer.
  • Ga metal was used as a target.
  • a Ga metal target was attached to a magnetron sputter gun and arranged so as to be parallel to the growth surface of the ZnO substrate, and the distance between the ZnO substrate and the Ga metal target was about 6 cm.
  • As an atmospheric gas 2.0 sccm of Ar gas and 3.0 sccm of nitrogen gas were introduced by a mass flow controller, and the growth pressure was 3.5 ⁇ 10 ⁇ 2 Torr.
  • the voltage of the DC power source applied between the ZnO substrate and the Ga metal target is ⁇ 607 V
  • the voltage application time is 50 ⁇ sec
  • the voltage application pause time is 3000 ⁇ sec.
  • the average energy per second was 1110W.
  • Sputtering is performed by temporarily increasing the amount of Ar gas introduced into the growth chamber while the substrate temperature of the ZnO substrate is set to 330 ° C., and the shutter for blocking the supply of the raw material is disposed in front of the ZnO substrate and on the Ga metal target. After starting the discharge and confirming that the Ar gas amount and the growth pressure were stabilized at the above-described set values, each shutter was opened, and a GaN layer was formed for 30 minutes. The film thickness of the GaN layer was 0.08 ⁇ m.
  • the GaN layer after film formation was observed by RHEED.
  • the observed RHEED image is shown in FIG. 7B. Since a clear two-dimensional diffraction streak pattern was shown, it was found that a single crystal layer having a flat surface state was formed.
  • Ga droplets were not observed and had an excellent surface state.
  • Example B-2> The distance between the ZnO substrate and the Ga metal target was ⁇ 10 mm with respect to Example B-1, the substrate temperature was 360 ° C., the voltage application time was 5 ⁇ sec, the voltage application pause time was 500 ⁇ sec, and the voltage application time was A film was formed in the same manner as in Example B-1, except that the average energy per second was 1840 W.
  • the film thickness of the GaN layer was 0.06 ⁇ m.
  • Table 5 shows the results of evaluating the mosaic properties of the crystals of the obtained GaN layer by X-ray rocking curve measurement in the same manner as in Example B-1.
  • A 0.091 °
  • b 0.401 °
  • both tilt and twist were small, and excellent crystallinity was obtained.
  • Example B-3> The amounts of Ar gas and nitrogen gas introduced were 1.0 sccm and 4.0 sccm, the growth pressure was 2.4 ⁇ 10 ⁇ 2 Torr, the substrate temperature was 341 ° C., and a DC power source applied between the ZnO substrate and the Ga metal target was used.
  • a film was formed in the same manner as in Example B-1, except that the voltage was ⁇ 557 V, the voltage application time was 5 ⁇ sec, the voltage application suspension time was 45 ⁇ sec, and the average energy per second during the voltage application time was 368 W.
  • the film thickness of the GaN layer was 0.12 ⁇ m.
  • the impurity concentration of the obtained GaN layer was measured by secondary ion mass spectrometry with detection elements as H, C, and O. Table 6 shows the measurement results.
  • Example B-1 ⁇ Comparative Example B-1> The growth pressure is 2.0 ⁇ 10 ⁇ 2 Torr, the substrate temperature is 316 ° C., the voltage of the DC power source applied between the ZnO substrate and the Ga metal target is ⁇ 607 V, the voltage application time is 5 ⁇ sec, and the voltage application is stopped. A film was formed in the same manner as in Example B-1, except that the time was 95 ⁇ sec and the average energy per second during the voltage application time was 607 W. The film thickness of the GaN layer was 0.14 ⁇ m.
  • the GaN layer after film formation was observed by RHEED.
  • a two-dimensional diffraction streak pattern similar to that in Example B-1 was also observed, but the portion showing the ring-shaped pattern was also mixed in the growth surface, so that the crystallinity near the surface began to deteriorate. all right.
  • An RHEED image of the observed ring-shaped pattern is shown in FIG.
  • Table 5 shows the results of evaluating the mosaic property of the crystals of the obtained GaN layer by X-ray rocking curve measurement in the same manner as in Example B-1.
  • the impurity concentration of the obtained GaN layer was measured by secondary ion mass spectrometry with detection elements as H, C, and O.
  • Table 6 shows the measurement results.
  • O concentration: 2.9 ⁇ 10 22 unit: atom / cm 3
  • ⁇ Comparative Example B-2> PLD Film Formation A ZnO substrate having a (0001) plane as a growth surface was introduced into a film formation apparatus to form a GaN layer. Ga metal was used as a target. The Ga metal target was disposed so as to be parallel to the growth surface of the ZnO substrate, and the distance between the ZnO substrate and the Ga metal target was about 7 cm. An RF radical source was used as a nitrogen source at 350 W, and the growth pressure was 4.5 ⁇ 10 ⁇ 6 Torr.
  • the irradiation time of the pulsed laser light emitted from the KrF excimer laser irradiating the target was repeated 20 ns, the irradiation pause time was 33 ms, and the average energy per second during the irradiation time was 2.8 ⁇ 10 5 W.
  • the substrate temperature of the ZnO substrate 11 was 331 ° C., and a GaN layer was formed for 1 hour.
  • the film thickness of the GaN layer was 0.04 ⁇ m.
  • FIG. 9B shows an example of a differential interference microscope image of the crystal film surface where no droplets are observed as in Example B-1. Further, as in Comparative Example B-2, an example of a differential interference microscope image of the crystal film surface where droplets are observed is shown in FIG.
  • Example of Third Invention A ZnO substrate having a (1-100) plane (m-plane) as a growth plane was introduced into the PSD apparatus to form an InGaN layer (first layer).
  • Ga metal and In metal were used as targets.
  • the Ga metal target and the In metal target are each attached to a magnetron sputter gun, the Ga metal target is arranged so as to be parallel to the growth surface of the ZnO substrate, and the normal of the In metal target is ZnO. It arrange
  • Ar gas was introduced at 1.0 sccm and nitrogen gas was introduced at 4.0 sccm by a mass flow controller, and the growth pressure was set at 2 ⁇ 10 ⁇ 2 Torr.
  • the ZnO substrate is grounded in terms of potential, the voltage applied between the ZnO substrate and the Ga metal target is ⁇ 600 V, the voltage application time is 5 ⁇ sec, the voltage application pause time is 95 ⁇ sec, and between the ZnO substrate and the In metal target.
  • the applied voltage was ⁇ 500 V, the voltage application time was 5 ⁇ sec, and the voltage application pause time was 95 ⁇ sec.
  • Sputter discharge is started by temporarily increasing the amount of Ar gas introduced into the growth chamber in the state where the shutter for blocking the raw material supply is arranged in front of the ZnO substrate, on the Ga metal target, and on the In metal target, After confirming that the amount of Ar gas and the growth pressure were stabilized at the set values described above, each shutter was opened and an InGaN layer was formed for 10 minutes.
  • the growth temperature was 344 ° C.
  • the InGaN layer formed in the same manner as the InGaN layer (first layer).
  • the In composition was 0.12 and the growth film thickness was 50 nm.
  • an InGaN layer (second layer) was formed on the InGaN layer (first layer).
  • the first layer was the same as the first layer except that the voltage application pause between the ZnO substrate and the In metal target was 115 ⁇ sec and the growth time was 3 minutes.
  • the In composition was 0.10 and the growth film thickness was 15 nm.
  • an InGaN layer (third layer) was formed on the InGaN layer (second layer).
  • the second layer was the same as the second layer except that the shutter opening degree on the In metal target was halved.
  • the In composition was 0.05 and the growth film thickness was 15 nm.
  • a GaN layer (fourth layer) was formed on the InGaN layer (third layer). It was the same as the first layer except that the voltage application between the ZnO substrate and the In metal target was stopped and the growth time was 4 minutes. The growth thickness obtained from the growth rate of the GaN layer formed in the same manner as the GaN layer (fourth layer) except that the growth time was 30 minutes was 20 nm.
  • FIG. 12 shows the layer structure of the semiconductor multilayer structure manufactured in Example C-1.
  • FIG. 13 shows the layer structure of the semiconductor multilayer structure manufactured in Example C-2.
  • a laminated structure was manufactured by growing the third layer in the same manner as the fourth layer of Example C-1, except that the growth time of the third layer was 5 minutes.
  • FIG. 14 shows the layer structure of the semiconductor multilayer structure manufactured in Example C-3.
  • Example C-1 A GaN layer was grown in the same manner as the fourth layer of Example C-1, except that the growth temperature was 340 ° C. and the growth time was 25 minutes.
  • the surface of the obtained laminated structure was observed with a differential interference microscope at a magnification of 200 times, 60 cracks were observed in a square section having a side of 500 ⁇ m, and the semiconductor laminated structure had a difficult-to-use surface state.
  • FIG. 17 shows an example of a differential interference microscope image of the crystal film surface where cracks were observed in Comparative Example C-1.
  • FIG. 15 shows the layer structure of the semiconductor multilayer structure manufactured in Comparative Example C-1.
  • ⁇ Comparative Example C-2> The growth temperature is set to 330 ° C.
  • a laminated structure was manufactured by growing a GaN layer in the same manner as the fourth layer of Example C-1, except that the growth time of the second layer was 5 minutes.
  • the surface of the obtained laminated structure was observed with a differential interference microscope at a magnification of 200 times, 35 cracks were observed in a square section having a side of 500 ⁇ m, and it could be used in a limited manner such as application and in-use area. It was a semiconductor laminated structure having a simple surface state.
  • FIG. 16 shows the layer structure of the semiconductor multilayer structure manufactured in Comparative Example C-2.
  • Japanese Patent Application Japanese Patent Application No. 2008-222149
  • Japanese Patent Application Japanese Patent Application No. 2008-222150
  • Japanese Patent Application Japanese Patent Application No. 2008-222151
  • Japanese Patent Application Japanese Patent Application No. 2008-222151

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Abstract

La présente invention concerne un procédé de formation d’une couche épitaxiale composée, comprenant les étapes suivantes : (a) un substrat ZnO présentant un plan de croissance formant un angle égal ou supérieur à 10° avec un {0001} plan est prévu; (b) la totalité ou une partie des éléments pour la formation de la couche épitaxiale composée sont alimentés de façon intermittente sur la plan de croissance du substrat. Dans ce cas, la couche épitaxiale composée est formée par la croissance de cristaux sur le substrat ZnO par l’alimentation des éléments de sorte que, lors d’une séquence d’alimentation intermittente, un temps de durée arbitraire d’alimentation Ton (sec) et un temps d’arrêt d’alimentation Toff (sec) qui est une période entre la fin de l’alimentation d’éléments et l’alimentation ultérieure d’éléments satisfont les formules suivantes : 1 × 10-6 sec ≤ Toff ≤ 1 × 10-2 sec; 1 × 10-6 sec ≤ Ton ≤ 1 × 10-2 sec. Le procédé peut réduire l’apparition de gouttelettes qui abaisse le rendement de la couche épitaxiale et, en même temps, peut former une couche épitaxiale composée présentant une bonne cristallinité.
PCT/JP2009/065118 2008-08-29 2009-08-28 Procédé de formation de couche épitaxiale composée, couche épitaxiale composée, structure stratifiée à semi-conducteurs, et dispositif électroluminescent à semi-conducteurs WO2010024411A1 (fr)

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JP2008222150A JP2010056436A (ja) 2008-08-29 2008-08-29 化合物エピタキシャル層の製造方法および半導体積層構造
JP2008-222150 2008-08-29
JP2008-222149 2008-08-29
JP2008-222151 2008-08-29
JP2008222149A JP2010056435A (ja) 2008-08-29 2008-08-29 化合物エピタキシャル層の製造方法および半導体積層構造

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Cited By (2)

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Publication number Priority date Publication date Assignee Title
CN109643645A (zh) * 2016-08-31 2019-04-16 国立研究开发法人科学技术振兴机构 化合物半导体及其制造方法以及氮化物半导体
WO2024024267A1 (fr) * 2022-07-25 2024-02-01 株式会社ジャパンディスプレイ Dispositif de formation de film et procédé de formation de film de nitrure de gallium

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