JP6446681B2 - Manufacturing method of laminated structure - Google Patents

Description

  The present invention relates to a stacked structure including a semiconductor layer useful for a semiconductor device and a semiconductor device including the stacked structure.

  The group III nitride semiconductor means AlN, GaN, InN and mixed crystals thereof, and is a semiconductor having a stable wurtzite crystal structure at room temperature and atmospheric pressure, and having a direct transition type energy band structure. Among many semiconductor materials, it is a material with a small effective mass and a high electron saturation drift velocity, and has characteristics that the velocity is saturated in a higher electric field region than typical semiconductors such as Si and GaAs. It is also stable in terms of chemical and chemical properties, and its thermal conductivity is relatively high, so it can operate in harsh environments and conditions. Group III nitride semiconductors are expected to be applied in new industrial fields by taking advantage of their excellent physical properties in addition to optical devices. In particular, by using a nitride semiconductor electronic device in a wireless communication system that handles ultra-high-speed, large-capacity, and multi-function information processing, it is expected to realize a high-output high-frequency device that greatly exceeds the performance of conventional devices. In addition to high-power / high-frequency devices, it is expected to be applied in various fields as environmentally resistant devices.

  Among group III nitride semiconductors, GaN uses a direct transition type device and a wide band gap of 3.4 eV, and has been commercialized as a blue light emitting diode or a blue / blue violet laser diode as an optical device. However, GaN has been spotlighted as a new material, and thin film fabrication technology and device application technology have made remarkable progress in recent years, but there are many problems. One of them is that there is no optimal substrate material for GaN crystal growth. Since GaN has an extremely high equilibrium vapor pressure of nitrogen at the melting point, it is difficult to produce a bulk crystal from the melt, and homoepitaxial growth is difficult. Also, in heteroepitaxial growth, there is no optimal substrate having the same lattice constant and thermal expansion coefficient, and it has been difficult to obtain high quality crystals. Currently, the growth of hexagonal GaN on a sapphire substrate using the MOCVD method has become mainstream, but the lattice constant difference between the sapphire substrate and the hexagonal GaN is about 16% and the difference in thermal expansion coefficient is 25. In order to relieve strain and obtain a high-quality film, the introduction of nitriding, a low-temperature buffer layer, or the like has been studied. Patent Documents 1 and 2 describe a method of forming GaN on a sapphire substrate via a low-temperature buffer layer or the like. Patent Document 3 describes a method of growing a GaN crystal after nitriding a sapphire substrate. However, none of these methods have been satisfactory in terms of the crystallinity and luminescence of GaN.

According to Non-Patent Document 1, Tomas Palacios et al. Of MIT peeled the AlGaN / GaN film grown on Si {111} from the Si {111} substrate and stuck the AlGaN / GaN thin film to the Si {100} substrate. , Si devices and GaN devices are integrated. However, there is a problem that the number of work steps is large and it is difficult to cleanly peel off the entire surface of the substrate.
Patent Document 4 describes crystal growth of gallium nitride using a β gallium oxide substrate as a base material, but the substrate size that can be procured is limited, and mass production of silicon, sapphire, etc. has already progressed. It was difficult to increase the diameter as compared with the material that was in use.

  Also, III nitride semiconductors other than GaN have the same problem. Among group III nitride semiconductors, InN has high electron mobility and a large saturation electron drift velocity, but has been attracting attention since the forbidden band width was confirmed to be 0.65 to 0.7 eV instead of 1.9 eV. It is expected to be applied to high frequency electronic devices. However, InN has a condition that the film forming temperature must be lowered, and crystal growth is difficult. Various film forming methods have been studied for such problems. For example, Patent Document 5 supplies a metal composed of two or more elements incorporated in different amounts and an active nitrogen species. However, it is still unsatisfactory, and there has been a long-awaited method for forming indium nitride with excellent crystallinity.

  Patent Document 6 discloses that at least any one of indium, aluminum, and gallium is formed on an InAlGaO-based semiconductor film grown on a base made of a uniaxially oriented platinum, gold, or palladium metal thin film or metal substrate. A semiconductor device or a substrate is described in which a nitride semiconductor or a combination thereof is formed directly or via another layer. However, the substrate is expensive, and even if a nitride semiconductor on the InAlGaO-based semiconductor layer is produced, the crystal quality is still not satisfactory.

JP-A-10-51074 JP 2005-522889 A JP 2008-53593 A JP2013-58636A JP 2010-267888 A Patent No. 5528612

IEEE EDL, 30, 1015, 2009

  An object of this invention is to provide the laminated structure excellent in the semiconductor characteristic, and the semiconductor device which consists of the said laminated structure.

  As a result of intensive studies to achieve the above object, the present inventors have found that an indium-containing oxide semiconductor layer having a corundum structure is formed on a crystal substrate having a corundum structure on part or all of the surface. Through the stacking of the semiconductor layers having a hexagonal crystal structure, the semiconductor layer has excellent crystallinity, and a multilayer structure having excellent semiconductor characteristics can be obtained. We found that conventional problems can be solved at once.

That is, the present invention relates to the following inventions.
[1] A method for producing a laminated structure by forming a semiconductor layer having a hexagonal crystal structure on a substrate having a corundum structure on part or all of the surface, the hexagonal crystal having the above structure a nitride semiconductor layer semiconductor layer has a structure, the formation of a semiconductor layer having the hexagonal structure, through an indium containing oxide semiconductor layer having a corundum structure, RF -Laminated structure characterized by using MBE method .
[2], wherein the substrate, the production method of [1] stacked structure wherein a is a crystalline substrate containing alpha-Al2 O3 to a part or the whole of its surface.
[3] The method for producing a stacked structure according to [1] or [2], wherein the indium-containing oxide semiconductor layer having the corundum structure contains indium oxide as a main component.
[4] The nitride semiconductor layer according to any one of [1] to [3], wherein the nitride semiconductor layer includes one or more metals selected from aluminum, gallium, and indium as a metal component constituting the semiconductor layer. Manufacturing method of the laminated structure.

  ADVANTAGE OF THE INVENTION According to this invention, the semiconductor device which consists of a laminated structure excellent in the semiconductor characteristic and the said laminated structure can be provided.

It is a figure explaining the mist CVD apparatus used in the Example. It is a figure explaining the RF-MBE apparatus used in the Example. It is a figure which shows the result of the XRD (omega) scan in an Example. It is a figure which shows the result of CL measurement in an Example. It is a figure which shows the result of the XRDomega scan in a comparative example. It is a figure which shows the result of CL measurement in a comparative example. It is a figure which shows the result of the XRD (omega) scan in an Example. It is a figure which shows the result of the XRD (omega) scan in an Example. It is a figure which shows the observation result (SEM image) of SEM in an Example. It is a figure which shows the observation result (SEM image) of SEM in an Example.

  The laminated structure of the present invention has a hexagonal crystal structure on a substrate having a corundum structure on part or all of its surface, with an indium-containing oxide semiconductor layer having a corundum structure. The semiconductor layers are stacked.

(Substrate)
The base is not particularly limited as long as it can support the indium-containing oxide semiconductor layer and the semiconductor layer, and has a corundum structure on part or all of its surface. The material of the substrate is not particularly limited as long as the object of the present invention is not impaired, and may be a known substrate material, which may be an organic compound or an inorganic compound. Examples of the shape of the substrate include plate shapes such as flat plates and disks, fiber shapes, rod shapes, columnar shapes, prismatic shapes, cylindrical shapes, spiral shapes, spherical shapes, ring shapes, and the like. A substrate is preferred. Although the thickness of a board | substrate is not specifically limited in this invention, Preferably, it is 10-2000 micrometers, More preferably, it is 50-800 micrometers.

The substrate may be an insulator substrate or a semiconductor substrate, but the substrate is preferably an insulator substrate. The substrate material is not particularly limited as long as the object of the present invention is not impaired, and may be a known material. Suitable examples of the substrate material include a material having a corundum structure, and examples of the material having the corundum structure include α-Ga ₂ O ₃ , α-Fe ₂ O ₃ , and α-In ₂ O _3. , Α-Al ₂ O ₃ , α-V ₂ O ₃ , α-Ti ₂ O ₃ , α-Cr ₂ O ₃ , α-Rh ₂ O ₃ , α-Ni ₂ O ₃ , α-Co ₂ O _{3 and the} like In the present invention, α-Al ₂ O ₃ or α-Ga ₂ O ₃ is preferable, α-Al ₂ O ₃ is more preferable, and c-plane sapphire is most preferable. The substrate only needs to include a material having the corundum structure on part or all of the surface thereof, and may include other substrate materials, or a metal film or the like may be formed on the surface. Also good.
In the present invention, the substrate is preferably a crystal substrate including a material having a corundum structure containing aluminum or gallium on a part or all of the surface thereof, α-Al ₂ O ₃ or α-Ga ₂ O _3. It is more preferable that the crystal substrate contains α, and it is most preferable that the crystal substrate contains α-Al ₂ O ₃ .

(Indium-containing oxide semiconductor layer)
The indium-containing oxide semiconductor layer has a corundum structure and is not particularly limited as long as it contains at least indium as a constituent material, but preferably contains a constituent material containing indium as a main component. The “main component” means that the constituent material containing indium is preferably 50% or more, more preferably 70% or more, and still more preferably 90% with respect to all components of the indium-containing oxide semiconductor layer in terms of atomic ratio. This means that it is included, and it may be 100%. Examples of the constituent material containing indium include α-In _X Al _Y Ga _Z O ₃ (0 <X ≦ 2, 0 ≦ Y <2, 0 ≦ Z <2, X + Y + Z = 2) and the like. In the present invention, α-In _X1 Al _Y1 Ga _Z1 O ₃ (1 <X1 ≦ 2, 0 ≦ Y1 <1, 0 ≦ Z1 <1, X1 + Y1 + Z1 = 2) is preferable, α-In ₂ O ₃ , α _{-In X2 Ga Z2 O 3 (1} <X2 <2,0 <Z2 <1, X2 + Z2 = 2), α-In X3 Al Y3 O 3 (1 <X3 <2,0 <Y3 <1, X3 + Y3 = 2) or _{α-In X4 Al Y4 Ga Z4} O 3 (1 <X4 <2,0 <Y4 <1,0 <Z4 <1, X4 + Y4 + Z4 = 2) is more preferable. The indium content in the indium-containing oxide semiconductor layer is not particularly limited, but is preferably 30% by mass or more, more preferably 50% by mass or more, and most preferably 70% by mass or more. The thickness of the indium-containing oxide semiconductor layer is not particularly limited, but is preferably 10 nm to 10 mm, and more preferably 50 nm to 500 μm.

(Semiconductor layer with hexagonal structure)
The semiconductor layer is not particularly limited as long as it has a hexagonal crystal structure and contains a semiconductor as a main component. Examples of the semiconductor include silicon carbide (SiC) and AlGaIn-based nitride semiconductor. Examples of the AlGaIn nitride semiconductor include nitride semiconductors containing aluminum, gallium, or indium, and more specifically, gallium nitride (GaN), indium nitride (InN), and the like. In the present invention, the semiconductor is preferably an AlGaIn nitride semiconductor, and more preferably GaN or InN. Further, the metal component constituting the semiconductor layer is not particularly limited, but in the present invention, it preferably contains one or more metals selected from aluminum, gallium and indium, and contains gallium or indium. Is more preferable. The thickness of the semiconductor layer having the hexagonal crystal structure is not particularly limited, but is preferably 10 nm to 10 mm, and more preferably 50 nm to 500 μm.

  The laminated structure of the present invention has a hexagonal crystal structure on an indium-containing oxide semiconductor layer having a corundum structure on a substrate having a corundum structure on part or all of the surface. It is obtained by stacking the semiconductor layers. The laminating means is not particularly limited as long as the object of the present invention is not impaired, and may be a known means. For example, laminating means from the liquid phase (for example, sol-gel method, plating method, coating method, printing method, etc.), laminating means from the gas phase (for example, PVD method, CVD method), adhesive means, and the like can be mentioned. In the present invention, the stacking means is preferably a stacking means by epitaxial growth. Hereafter, the manufacturing method of the preferable laminated structure of this invention is demonstrated.

(Manufacturing method)
In the present invention, the laminated structure can be produced using, for example, a mist CVD method. More specifically, mist generated by atomizing the raw material solution is supplied to the substrate by a carrier gas, and the indium-containing oxide semiconductor layer is formed on the substrate by a thermal reaction. Can be manufactured by stacking semiconductor layers having a hexagonal crystal structure.

(Raw material solution)
The raw material solution is not particularly limited as long as it contains a material capable of forming the indium-containing oxide semiconductor layer, and is not particularly limited as long as it can atomize indium. As the raw material solution, a solution obtained by dissolving or dispersing indium in an organic solvent or water in the form of a complex or salt can be preferably used. Examples of complex forms include acetylacetonate complexes, carbonyl complexes, ammine complexes, hydride complexes, and the like. Examples of the salt form include metal chloride salts, metal bromide salts, metal iodide salts, and the like.

Moreover, you may mix additives, such as a hydrohalic acid and an oxidizing agent, with the said raw material solution. Examples of the hydrohalic acid include hydrobromic acid, hydrochloric acid, hydroiodic acid, etc. Among them, hydrobromic acid or hydroiodic acid is preferable. Examples of the oxidizing agent include hydrogen peroxide (H ₂ O ₂ ), sodium peroxide (Na ₂ O ₂ ), barium peroxide (BaO ₂ ), and benzoyl peroxide (C ₆ H ₅ CO) ₂ O _2. Peroxides, hypochlorous acid (HClO), perchloric acid, nitric acid, ozone water, organic peroxides such as peracetic acid and nitrobenzene.

The raw material solution may contain a dopant. The dopant is not particularly limited as long as the object of the present invention is not impaired. Examples of the dopant include n-type dopants such as tin, germanium, silicon, titanium, zirconium, vanadium or niobium, or p-type dopants. The concentration of the dopant may usually be about 1 × 10 ¹⁶ / cm ³ to 1 × 10 ²² / cm ³ , and the concentration of the dopant is set to a low concentration of about 1 × 10 ¹⁷ / cm ³ or less, for example. May be. Furthermore, according to the present invention, the dopant may be contained at a high concentration of about 1 × 10 ²⁰ / cm ³ or more.

  In the present invention, the indium-containing semiconductor layer is preferably formed using a mist CVD method. In the mist CVD method, the raw material solution is atomized (atomization step), the generated mist is supplied to the substrate by a carrier gas (mist supply step), and a film is formed on the substrate by a thermal reaction. (Film formation process).

  In the atomization step, the raw material solution is adjusted, and the raw material solution is atomized to generate mist. The blending ratio of the metal is not particularly limited, but is preferably 0.01 to 70% by mass, and more preferably 0.1 to 50% by mass with respect to the entire raw material solution.

  In this step, the raw material solution is atomized to generate mist. The atomizing means is not particularly limited as long as it can atomize the raw material solution, and may be a known atomizing means, but in the present invention, it is preferably an atomizing means using ultrasonic waves.

  In the carrier gas supply step, a carrier gas is supplied to the mist. The type of the carrier gas is not particularly limited as long as the object of the present invention is not impaired. For example, an inert gas such as oxygen, ozone, nitrogen or argon, or a reducing gas such as hydrogen gas or forming gas is preferable. As mentioned. Further, the type of carrier gas may be one type, but may be two or more types, and a diluent gas (for example, a 10-fold diluted gas) whose carrier gas concentration is changed is used as the second carrier gas. Further, it may be used. Further, the supply location of the carrier gas is not limited to one location but may be two or more locations.

  In the mist supply step, the mist is supplied to the substrate by the carrier gas. The flow rate of the carrier gas is not particularly limited, but is preferably 0.01 to 20 L / min, and more preferably 1 to 10 L / min.

  In the film forming step, the mist is reacted by heat to form a film on part or all of the substrate surface. The thermal reaction may be performed as long as the mist reacts with heat, and the reaction conditions are not particularly limited as long as the object of the present invention is not impaired. In this step, the thermal reaction is preferably performed at a temperature of 600 ° C. or less, more preferably at a temperature of 500 ° C. or less, and most preferably at 450 ° C. or less. Further, the thermal reaction may be performed under any atmosphere of a vacuum, a non-oxygen atmosphere, a reducing gas atmosphere, and an oxygen atmosphere as long as the object of the present invention is not impaired. An atmosphere is preferred. The film thickness can be set by adjusting the film formation time.

  In the present invention, after the indium-containing oxide semiconductor layer is formed, a semiconductor layer having a hexagonal crystal structure is stacked using a known means. The means for laminating the semiconductor layers is not particularly limited, and examples thereof include known means such as PVD method and CVD method. Preferably, MBE method, laser ablation method, mist CVD method, MOCVD method and the like are used. More preferably, mist CVD method or RF-MBE method is mentioned.

  In the present invention, when the semiconductor layer having a hexagonal crystal structure is a nitride semiconductor layer, the nitridation is performed using a high-frequency molecular beam epitaxial crystal method (RF-MBE method) using a plasma nitrogen source. A physical semiconductor layer is preferably formed. By using a substrate on which an indium-containing semiconductor layer having a corundum structure is formed, a semiconductor layer having a high-quality hexagonal crystal structure can be formed.

  The lamination of the nitride semiconductor layer by the RF-MBE method is not particularly limited as long as the object of the present invention is not hindered. For example, the nitride semiconductor layer can be formed by a known RF-MBE apparatus equipped with an RF plasma cell. The growth temperature is preferably about 300 ° C. to about 1000 ° C. (more preferably about 500 ° C. to about 800 ° C.), and the raw material cell temperature is about 400 ° C. to about 1000 ° C. (more preferably about 500 ° C.). To about 900 ° C.), the plasma power is about 100 W to about 500 W (more preferably about 200 W to about 400 W), and the growth time is about 1 minute to about 10 hours (more preferably about 10 minutes to about 5 hours).

  When the semiconductor layer having a hexagonal crystal structure is a nitride semiconductor layer, the nitride semiconductor layer may be subjected to nitriding treatment. In the present invention, the nitride The semiconductor layer preferably includes a nitrided indium-containing oxide semiconductor layer, and more preferably the nitride semiconductor layer includes indium nitride as a main component. Here, the “main component” includes the indium nitride in an atomic ratio of preferably 50% or more, more preferably 70% or more, and still more preferably 90% or more with respect to all components of the nitride semiconductor layer. Means that it may be 100%.

  In the present invention, the indium-containing oxide semiconductor layer may be stacked on the base via another layer, and another layer may be formed on the indium-containing oxide semiconductor layer. A semiconductor layer having the hexagonal crystal structure may be stacked therethrough. Examples of the other layer include a buffer layer. The method for forming the other layer is not particularly limited, and various means can be used, and such means may be known means. In the present invention, an indium-containing oxide semiconductor layer and a hexagonal crystal structure are formed by growing a semiconductor layer having a hexagonal crystal structure on an indium-containing oxide semiconductor layer having a corundum structure. The shape of the interface with the semiconductor layer can be an uneven structure, and by making the interface an uneven structure, the bonding between each layer can be improved without impairing the crystallinity. .

  Since the laminated structure of the present invention is excellent in semiconductor characteristics, it is useful for semiconductor devices. When the laminated structure is used for a semiconductor device, it may be used as it is for a semiconductor device or may be used after the substrate is peeled off.

  In the present invention, when an insulator substrate such as a sapphire substrate is used as the substrate, for example, after bonding other layers such as a p-type semiconductor layer, the quantum well structure is peeled from the substrate to form a semiconductor device. It is preferable to use it. The peeling means is not particularly limited as long as the object of the present invention is not impaired, and may be a known means. Examples of the peeling means include a means for peeling by applying a mechanical impact, a means for peeling by applying heat and applying thermal stress, a means for peeling by applying vibration such as ultrasonic waves, a means for peeling by etching, etc. Is mentioned.

  The p-type semiconductor layer is not particularly limited as long as it does not hinder the object of the present invention, but is preferably a p-type semiconductor layer containing a metal oxide having a hexagonal crystal structure as a main component. Preferred examples of the metal oxide include Delafossite, rhodium oxide, and oxychalcogenide.

  The semiconductor device can be classified into a horizontal element (horizontal device) in which electrodes are formed on one side of a semiconductor layer and a vertical element (vertical device) having electrodes on both sides of the semiconductor layer. However, the laminated structure of the present invention can be suitably used for both horizontal and vertical devices.

  Examples of the semiconductor device include a semiconductor laser, a diode, or a transistor, and more specifically, a distributed feedback (DFB) laser, a distributed reflection (DBR) laser, an external resonator laser, and a Schottky barrier. Diode (SBD), metal semiconductor field effect transistor (MESFET), high electron mobility transistor (HEMT), metal oxide semiconductor field effect transistor (MOSFET), electrostatic induction transistor (SIT), junction field effect transistor (JFET), Examples thereof include an insulated gate bipolar transistor (IGBT) or a light emitting diode.

  Needless to say, the semiconductor device may include other layers (for example, an insulator layer, a semi-insulator layer, a conductor layer, a semiconductor layer, a buffer layer, or other intermediate layers). Good.

<Example 1>
1. Mist CVD apparatus The mist CVD apparatus 19 used in the present embodiment will be described with reference to FIG. The mist CVD apparatus 19 includes a susceptor 21 on which the substrate 20 is placed, a carrier gas supply means 22 for supplying a carrier gas, and a flow rate adjusting valve 23 for adjusting the flow rate of the carrier gas sent from the carrier gas supply means 22. A mist generating source 24 for storing the raw material solution 24a, a container 25 for containing water 25a, an ultrasonic transducer 26 attached to the bottom surface of the container 25, a supply pipe 27 made of a quartz tube having an inner diameter of 40 mm, A heater 28 is provided around the supply pipe 27. The susceptor 21 is made of quartz, and the surface on which the substrate 20 is placed is inclined from the horizontal plane. Both the supply pipe 27 and the susceptor 21 are made of quartz, so that impurities derived from the apparatus are prevented from being mixed into the film formed on the substrate 20.

2. Preparation of raw material solution and crystal substrate An aqueous solution was prepared so as to be 0.025 mol / L indium bromide. This raw material solution 24 a was accommodated in the mist generating source 24. In addition, a c-plane sapphire substrate (a square with a side of 10 mm and a thickness of 600 μm) was used as the crystal substrate 20.

3. Preparation of Film Formation The crystal substrate 20 was placed on the susceptor 21 and the heater 28 was operated to raise the temperature in the supply pipe 27 to 500 ° C. Next, the flow rate adjusting valve 23 is opened, the carrier gas is supplied from the carrier gas source 22 into the supply pipe 27, the atmosphere in the supply pipe 27 is sufficiently replaced with the carrier gas, and then the flow rate of the carrier gas is set to 5 L / min. Adjusted. Oxygen gas was used as the carrier gas.

4). Film Formation Next, the ultrasonic vibrator 26 was vibrated at 2.4 MHz, and the vibration was propagated to the raw material solution 24a through the water 25a, whereby the raw material solution 24a was atomized to generate raw material fine particles.
The raw material fine particles are introduced into the supply pipe 27 by the carrier gas, react in the supply pipe 27, and a film is laminated on the crystal substrate 20 by the CVD reaction on the film formation surface of the crystal substrate 20. Got. After growing an iron oxide layer as a buffer layer on the sapphire substrate, an indium oxide thin film was formed using the raw material solution 24a.

5. Evaluation The obtained crystal film was not cloudy and was a clean crystal. Moreover, the phase of the obtained crystal film was identified. Identification was performed by performing 2θ / ω scanning at an angle of 15 to 95 degrees using an XRD diffractometer. The measurement was performed using CuKα rays. As a result, the obtained film was α-In ₂ 0 ₃ .

6). RF-MBE Device The RF-MBE device used in this example will be described with reference to FIG. The RF-MBE apparatus shown in FIG. 2 includes two chambers, a sample loading chamber (not shown) and a crystal growth chamber. The sample loading chamber is maintained at an ultra high vacuum by a turbo molecular pump (TMP) and a rotary pump (RP), and the crystal growth chamber is also maintained at an ultra high vacuum by TMP, RP, an ion pump, and a Ti sublimation pump. I'm leaning. The degree of vacuum in the crystal growth chamber is about 10 ⁻¹⁰ torr. The two chambers are shut off by the gate valve 1 and are opened only when the sample is transported. The sample loading chamber is exposed to the atmosphere when the sample is loaded, but since it is blocked by the gate valve 1, the sample can be exchanged without exposing the crystal growth chamber to the atmosphere, and there is no need for redrawing to vacuum or baking. A plurality of samples can be manufactured. Four substrate holders (susceptors) can be loaded into the sample loading chamber at a time. In addition, a pre-baking apparatus is mounted, and moisture and impurity gas can be released before carrying the growth chamber by heat-treating the substrate and the susceptor.

  The crystal growth chamber includes a substrate heating heater and thermocouple 8, a thermal radiation thermometer (pyrometer) 5, a susceptor 9 having a substrate rotation mechanism, an RF radical cell 4 supplied by SVTA Associates, a Group V source supply, a Knudsen cell 12, a beam A flux monitor 7, a quadrupole mass spectrometer 2, a reflection high-energy electron diffraction electron gun 6 and a screen 3, a gate valve 1, and an exhaust valve 11 are provided. There are four Knudsen cells 12, which are Knudsen cells for supplying In, Ga, Al, and Mg. A tantalum wire heater is used for substrate heating, and the substrate rotating mechanism operates at 10 rotations per minute. In the Knudsen cell, a high-purity solid material is heated and evaporated to generate a molecular beam, and a Ta or W heater wire is wound around a cylindrical crucible. In the Ga and Al supply Knudsen cell, the shutter is closed.

7). InN growth by RF-MBE GaN was grown by RF-MBE using α-In ₂ O ₃ deposited by mist CVD on the produced sapphire substrate as a growth substrate. The growth temperature was 700 ° C., the Ga cell temperature was 900 ° C., the nitrogen plasma power was 200 W, and the growth time was 1 hour. About the obtained laminated structure, each phase was identified using the X-ray-diffraction apparatus, and the half value width was investigated then. The obtained laminated structure was a hexagonal GaN / α-In ₂ O ₃ / α-Al ₂ O ₃ laminated structure, and the half-value width of XRDωscanGaN (0002) was 40.218 arcmin. The XRDω scan result is shown in FIG. The CL spectrum was examined using a (cathode luminescence) CL apparatus. The results are shown in FIG. From FIG. 4, light emission can be confirmed.

<Comparative Example 1>
A laminated structure was obtained in the same manner as in Example 1 except that 0.025 mol / L indium bromide was used in place of 0.1 mol / L gallium bromide and an iron oxide buffer layer was not formed. . The obtained multilayer structure was a multilayer structure of hexagonal GaN / α-Ga ₂ O ₃ / α-Al ₂ O ₃ , and the half-value width of XRDωscanGaN (0002) was 132 arcmin. The XRDω scan result is shown in FIG. The CL spectrum was examined using a (cathode luminescence) CL apparatus. The results are shown in FIG. As shown in FIG. 6, no luminescence was confirmed.

<Example 2>
Surface nitridation was performed by RF-MBE using α-In ₂ O ₃ deposited by mist CVD on a sapphire substrate produced in the same manner as in Example 1 as a growth substrate. The nitriding temperature was 500 ° C., the nitrogen plasma power was 200 W, and the nitriding time was 1 hour. After that, InN growth was performed. The growth time was 2 hours and the growth temperature was 825 ° C. Then, at the end of the InN growth, in order to remove In droplets generated in the growth under the metal rich condition, the growth was completed by irradiating only nitrogen plasma. About the obtained laminated structure, each phase was identified using the X-ray-diffraction apparatus, and the half value width was investigated then. The obtained laminated structure was a laminated structure of hexagonal InN / α-In ₂ O ₃ / α-Al ₂ O ₃ , and the half-value width of XRDω-scanned InN (0002) was 12 arcmin. Moreover, the InN surface was observed using SEM. An SEM image is shown in FIG. From FIG. 9, it can be seen that a relatively flat InN thin film having a grain structure was obtained. This grain structure reflects the surface morphology of α-In ₂ O ₃ of the growth substrate, and it can be seen that the shape of the interface between α-In ₂ O ₃ and InN has an uneven structure. .

<Example 3>
InN growth was performed on the α-In ₂ O ₃ / sapphire substrate in the same manner as in Example 2 except that the nitriding treatment was not performed. About the obtained laminated structure, each phase was identified using the X-ray-diffraction apparatus, and the half value width was investigated then. The obtained laminated structure was a laminated structure of hexagonal InN / α-In ₂ O ₃ / α-Al ₂ O ₃ , and the half-value width of XRDω-scanned InN (0002) was 38 armcmin. Moreover, the InN surface was observed using SEM. An SEM image is shown in FIG.

  The laminated structure of the present invention can be used in various fields such as semiconductors (for example, compound semiconductor electronic devices), electronic parts / electric equipment parts, optical / electrophotographic related apparatuses, industrial members, etc., but particularly useful in the semiconductor field. It is.

DESCRIPTION OF SYMBOLS 1 Gate valve 2 Quadrupole mass spectrometer 3 Reflection high-energy electron diffraction screen 4 RF radical cell 5 Pyrometer 6 Reflection high-energy electron diffraction electron gun 7 Beam monitor 8 Heater and thermocouple 9 Susceptor 10 Substrate 11 Exhaust valve 12 Knudsen cell 12a In Knudsen cell for supply 12b Knudsen cell for Ga supply 12c Knudsen cell for Al supply 12d Knudsen cell for Mg supply 19 Mist CVD apparatus 20 Substrate 21 Susceptor 22 Carrier gas supply means 23 Flow control valve 24 Mist generation source 24a Raw material solution 25 Container 25a Water 26 Ultrasonic vibrator 27 Deposition chamber 28 Heater

Claims (4)

A method of manufacturing a laminated structure by forming a semiconductor layer having a hexagonal crystal structure on a substrate having a corundum structure on a part or all of the surface, the method having the hexagonal crystal structure. The semiconductor layer is a nitride semiconductor layer, and the semiconductor layer having the hexagonal crystal structure is formed by an RF-MBE method through an indium-containing oxide semiconductor layer having a corundum structure. A method for producing a laminated structure, which is performed by using _{2. The} method for manufacturing a laminated structure according to claim 1, wherein the substrate is a crystal substrate containing α-Al ₂ O ₃ on a part or all of the surface thereof. The method for manufacturing a laminated structure according to claim 1 or 2, wherein the indium-containing oxide semiconductor layer having the corundum structure contains indium oxide as a main component. The nitride semiconductor layer, aluminum, one or more metals selected from gallium and indium, the production of the laminated structure according to claim 1 comprising a metal component constituting the semiconductor layer Way .