Laminated body, film forming method and film forming device

Abstract

The present invention is a laminate comprising a crystal substrate and a semiconductor film, wherein the semiconductor film is provided on the main surface of the crystal substrate and contains a dopant and an oxide semiconductor having a corundum structure as a main component, wherein the Si concentration contained in the oxide semiconductor is 5.0×10 20 cm ‑3 Hereinafter, the resistivity of the semiconductor film is 150 mΩ·cm or less. Thus, a laminated body including a semiconductor having a corundum structure and having a low resistance suitable for use in semiconductor devices can be provided.

Description

Technical Field

[0001] The present invention relates to a stacked body including a semiconductor film having a corundum structure, a semiconductor film forming method, and a film forming device. Background Art

[0002] As the next-generation switching element that can achieve high withstand voltage, low loss and high heat resistance, semiconductor devices using gallium oxide (Ga2O3) with a large band gap have attracted attention and are expected to be used in power semiconductor devices such as inverters and light-receiving / light-emitting elements.

[0003] In recent years, a mist chemical vapor deposition method (Mist CVD, hereinafter also referred to as "mist CVD method") has been developed, which uses a mist-like raw material to grow crystals on a substrate, and can produce gallium oxide with a corundum structure (also known as α-gallium oxide, α-Ga2O3) (Patent Document 1). In this method, a gallium compound such as gallium acetylacetonate is dissolved in an acid such as hydrochloric acid to form a precursor, and the precursor is atomized to generate raw material particles, and a mixed gas formed by mixing the raw material particles with a carrier gas is supplied to the surface of a corundum structure substrate such as sapphire, and a single-oriented gallium oxide film is epitaxially grown on the substrate by reacting the raw material mist.

[0004] In order to use α-gallium oxide as a device, it is necessary to dope impurities for imparting charge carriers. For doping of α-gallium oxide, it is known that Ge, Si or Sn can be used in imitation of β-Ga2O3, which has a long history. For example, Patent Document 1 records that a conductive α-gallium oxide film doped with Sn is formed on a c-plane sapphire substrate, and a minimum resistivity of 2000mΩ·cm is obtained. In addition, Patent Document 2 records an α-gallium oxide film doped with Ge on a c-plane sapphire substrate. In addition, Non-Patent Document 1 records that an α-gallium oxide film doped with Sn is formed on a c-plane sapphire substrate, and a resistivity of 200mΩ·cm is obtained.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application Publication No. 2013-028480

[0008] Patent Document 2: Japanese Patent Application Publication No. 2015-228495

[0009] Non-patent literature

[0010] Non-patent document 1: Chikoidze, E., et al. "Electrical, optical, and magnetic properties of Sn doped α-Ga2O3 thin films.", Journal of Applied Physics 120.2 (2016): 025109. Summary of the invention

[0011] Technical Problems to be Solved by the Invention

[0012] However, the resistivity of α-gallium oxide described in the above-mentioned patent documents and non-patent documents is not sufficient as a semiconductor property, and it is difficult to form a high-performance semiconductor device.

[0013] The present invention is made to solve the above-mentioned problems, and its purpose is to provide a stacked body including a semiconductor with a low resistance and a corundum structure, to provide a film forming method for obtaining a semiconductor film with a low resistance and a corundum structure, and to provide a film forming device for obtaining a semiconductor film with a low resistance and a corundum structure.

[0014] Technical means to solve technical problems

[0015] The present invention is made to achieve the above-mentioned object. The present invention provides a laminated body comprising a crystalline substrate and a semiconductor film, wherein the semiconductor film is provided on the main surface of the crystalline substrate and contains a dopant and an oxide semiconductor having a corundum structure as a main component, wherein the Si concentration contained in the oxide semiconductor is 5.0×10 20 cm -3 Hereinafter, the resistivity of the semiconductor film is 150 mΩ·cm or less.

[0016] Such a laminate has a low resistivity suitable for use in semiconductor devices.

[0017] In this case, a stacked body having a resistivity of 20 mΩ·cm or less of the semiconductor film can be formed.

[0018] Therefore, it has a low resistivity which is more suitable for use in semiconductor devices.

[0019] In this case, a stacked body in which the main surface of the semiconductor film is a c-plane can be formed.

[0020] Thereby, the electrical characteristics are further improved.

[0021] At this time, a stacked body in which the dopant is at least one selected from Sn, Ge, or Si may be formed, and further a stacked body in which the dopant is Sn may be formed.

[0022] Thereby, the electrical characteristics are further improved.

[0023] At this time, the carrier mobility in the semiconductor film can be 20 cm 2 / Vs or above, carrier density is 1.0×10 18 / cm 3 The above laminated body.

[0024] Thereby, the electrical characteristics are further improved.

[0025] In this case, a stacked body in which the oxide semiconductor includes Ga, In, or Al may be formed, and further, a stacked body in which the oxide semiconductor includes at least Ga may be formed.

[0026] Therefore, it can be applied to semiconductor devices having high performance characteristics such as high withstand voltage, low loss and high heat resistance.

[0027] In this case, a semiconductor device including at least a semiconductor and an electrode can be formed, which includes at least a part of the above-mentioned stacked body as the semiconductor, and further a semiconductor system including the semiconductor device can be formed.

[0028] This results in a semiconductor device or semiconductor system having high performance characteristics such as high withstand voltage, low loss, and high heat resistance.

[0029] In addition, a film forming method is provided, which comprises: a step of forming a mixed gas containing at least an atomized metal oxide precursor, a carrier gas and a dopant; a step of transporting the mixed gas to a film forming section via a transport section; and a step of causing the mixed gas to undergo a thermal reaction in the film forming section, thereby forming a semiconductor film on a substrate, wherein at least the surface of the transport section that is in contact with the mixed gas is made of a non-silicone resin.

[0030] According to the above film forming method, a semiconductor film having a low resistivity suitable for use in semiconductor devices can be formed.

[0031] At this time, the following film-forming method can be used, that is, the non-silicone resin includes any one or more of polyethylene, polypropylene, vinyl chloride, polystyrene, polyvinyl acetate, urethane resin, fluororesin, acrylonitrile butadiene styrene resin, acrylic resin, polyamide, polyimide, polyamideimide, nylon, acetal resin, polycarbonate, polyphenylene ether, polyester, polyethylene terephthalate, polybutylene terephthalate, polyolefin, polyphenylene sulfide, polysulfone, polyethersulfone, polyarylate, and polyetheretherketone.

[0032] This makes it possible to more reliably and stably form a semiconductor film having a low resistivity suitable for use in semiconductor devices.

[0033] At this time, the non-silicone-based resin may be formed into a film including a fluorine-based resin.

[0034] This makes it possible to more reliably and stably form a semiconductor film having a low resistivity suitable for use in semiconductor devices.

[0035] In addition, a film forming device is provided, which comprises: an atomizing section for atomizing a raw material solution to generate mist; a carrier gas supplying section for supplying a carrier gas for conveying the mist; a film forming section for causing the mist to undergo a thermal reaction to form a film on a substrate; and a conveying section for connecting the atomizing section and the film forming section and conveying the mist through the carrier gas, wherein at least the surface of the conveying section that is in contact with the mist is a non-silicone resin.

[0036] According to such a film forming apparatus, a semiconductor film having a low resistivity suitable for use in semiconductor devices can be formed.

[0037] Effects of the Invention

[0038] As described above, according to the present invention, a laminated body having a high-quality corundum structure semiconductor with excellent electrical characteristics can be provided. In addition, according to the present invention, a high-quality corundum structure semiconductor with excellent electrical characteristics can be easily and at low cost produced. In addition, according to the present invention, a film forming device that can easily and at low cost produce a high-quality corundum structure semiconductor with excellent electrical characteristics can be provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 This is a diagram showing one embodiment of the structure of the laminate of the present invention.

[0040] Figure 2 This is a diagram showing another embodiment of the structure of the laminated body of the present invention.

[0041] Figure 3 is a diagram schematically showing an example of a Schottky barrier diode (SBD).

[0042] Figure 4 is a diagram schematically showing an example of a high electron mobility transistor (HEMT).

[0043] Figure 5 FIG. 1 schematically shows an example of a metal oxide semiconductor field effect transistor (MOSFET).

[0044] Figure 6 is a diagram schematically showing an example of an insulated gate bipolar transistor (IGBT).

[0045] Figure 7 The figure schematically shows an example of a light emitting element (LED).

[0046] Figure 8 It is a diagram schematically showing another example of a light emitting element (LED).

[0047] Fig. 9 A diagram schematically showing an example of a power supply system.

[0048] Fig.10 A diagram schematically showing an example of a system device.

[0049] Fig.11 This is a diagram schematically showing an example of a power supply circuit diagram of a power supply device.

[0050] Fig.12 This is a diagram showing one embodiment of an atomization CVD apparatus for producing the laminated body of the present invention. DETAILED DESCRIPTION

[0051] Hereinafter, the present invention will be described in detail, but the present invention is not limited thereto.

[0052] As described above, a stacked body including a semiconductor with a low resistance having a corundum structure suitable for use in semiconductor devices, a film forming method capable of obtaining a semiconductor film with a low resistance having a corundum structure, and a film forming device capable of obtaining a semiconductor film with a low resistance having a corundum structure are sought.

[0053] The inventors of the present application have repeatedly studied the above technical problems and found that a laminated body having a low resistivity suitable for semiconductor device applications can be obtained by the following, thereby completing the present invention. The laminated body includes a crystal substrate and a semiconductor film, the semiconductor film is provided on the main surface of the crystal substrate, contains a dopant and includes an oxide semiconductor having a corundum structure as a main component, and the Si concentration contained in the oxide semiconductor is 5.0×10 20 cm -3 Hereinafter, the resistivity of the semiconductor film is 150 mΩ·cm or less.

[0054] In addition, the inventors of the present application discovered that a low-resistance semiconductor film suitable for use in semiconductor devices can be formed by the following film-forming method, thereby completing the present invention. The film-forming method comprises: a step of forming a mixed gas comprising at least an atomized metal oxide precursor, a carrier gas and a dopant; a step of transporting the mixed gas to a film-forming section via a transport section; and a step of causing the mixed gas to undergo a thermal reaction in the film-forming section to form a semiconductor film on a substrate, wherein at least the surface of the transport section that is in contact with the mixed gas is a non-silicone resin.

[0055] Furthermore, the inventors of the present application discovered that a low-resistance semiconductor film suitable for use in semiconductor devices can be formed by using the following film-forming apparatus, thereby completing the present invention, the film-forming apparatus comprising: an atomizing section that atomizes a raw material solution to generate mist; a carrier gas supplying section that supplies a carrier gas for transporting the mist; a film-forming section that causes the mist to undergo a thermal reaction to form a film on a substrate; and a transporting section that connects the atomizing section and the film-forming section and transports the mist through the carrier gas, wherein at least the surface of the transporting section that is in contact with the mist is a non-silicone resin.

[0056] As described above, even if a semiconductor film having a corundum structure such as α-gallium oxide is formed by a conventional method, a semiconductor film with a low resistivity cannot be obtained. For this reason, the inventors of the present application conducted an intensive investigation and found that Si contained in the semiconductor film hinders the reduction of resistance.

[0057] The inventors first discovered that if the Si concentration in the semiconductor film is greater than 5.0×10 20 cm -3 , the electrical conductivity of the semiconductor decreases significantly, and the resistivity will not be less than 200 mΩ·cm. That is, it was found that: by making the Si concentration in the semiconductor film 5.0×10 20 cm -3 The resistivity of the semiconductor film can be reduced to 150 mΩ·cm or less, and a semiconductor film having a corundum structure suitable for semiconductor applications can be formed. When the resistivity is further reduced, the Si concentration is preferably reduced to 3.0×10 20 cm -3 the following.

[0058] The physical explanation for this phenomenon is not clear at present, but it is believed that due to the large amount of Si mixed in, defects are formed between energy bands, thereby hindering the conduction of charge carriers, or the dopant is deactivated, thereby hindering the generation of charge carriers itself.

[0059] Hereinafter, description will be given with reference to the drawings.

[0060] (Laminated body)

[0061] Figure 1 FIG. 1 is a diagram showing one embodiment of a laminated body of the present invention. A laminated body 100 includes a crystalline substrate 101 and a semiconductor film 102 formed directly on the crystalline substrate 101 .

[0062] (Semiconductor Film)

[0063] The semiconductor film 102 is an oxide semiconductor film including an oxide semiconductor having a corundum structure as a main component and further including a dopant, and the Si concentration is 5.0×10 20 cm -3 Below, more preferably 3.0×10 20cm -3 The resistivity is below 150 m·Ωcm, and more preferably below 20 m·Ωcm. In addition, the expression "containing an oxide semiconductor as a main component" means that in addition to the oxide semiconductor, it may also contain a dopant or unavoidable impurities, for example, it means that it contains about 50% or more of an oxide semiconductor. In addition, the lower limit of the Si concentration is 0, but it can also be 1×10 16 cm -3 In addition, the lower limit of the resistivity is not particularly limited, and can be, for example, 1.0×10 -1 m·Ωcm.

[0064] Furthermore, the mobility of charge carriers in the semiconductor film 102 is preferably 20 cm 2 / Vs or more, more preferably 40cm 2 / Vs or more, preferably 50cm 2 / Vs or more. The mobility is the mobility measured by the Hall effect. In addition, the upper limit of the mobility is not particularly limited, for example, it can be 300cm 2 / Vs.

[0065] Furthermore, in the present invention, it is preferred that the carrier density of the semiconductor film 102 is 1.0×10 18 / cm 3 The carrier density is the carrier density in the semiconductor film 102 measured by the Hall effect. In addition, the upper limit of the carrier density is not particularly limited, and can be, for example, 1.0×10 21 / cm 3 .

[0066] In addition, the main surface of the semiconductor film 102 is preferably a c-plane. This is because the c-plane can relatively easily improve crystallinity, and as a result, the electrical characteristics can be further improved.

[0067] In addition, the semiconductor film 102 preferably contains at least one of In, Ga, Al, Ir, V, Fe, Cr, and Ti as a metal component in the oxide semiconductor, and Ga is most preferably used as the main component. In addition, the so-called "main component" here, for example, when the oxide semiconductor is α-gallium oxide, α-gallium oxide is contained at a ratio of 0.5 or more of the atomic ratio of gallium in the metal element in the film. In the present invention, the atomic ratio of Ga in the metal element in the film is preferably 0.7 or more, and more preferably 0.8 or more.

[0068] In addition, the thickness of the semiconductor film 102 is not particularly limited. In addition, the shape of the main surface of the semiconductor film 102 is not particularly limited, and can be a quadrilateral (including a square shape, a rectangular shape), a circular shape (including a semicircular shape), or a polygonal shape. The surface area of ​​the semiconductor film 102 is not particularly limited, and is preferably equivalent to an area of ​​3 mm square or more, and more preferably equivalent to an area of ​​5 mm square or more. When formed on a circular substrate, it is most preferably a diameter of 50 mm or more. In the observation of the film surface of the semiconductor film 102 based on an optical microscope, it is preferred that there is no crack in the central 3 mm square area, more preferably there is no crack in the central 5 mm square area, and most preferably there is no crack in the central 9.5 mm square area. In addition, the semiconductor film 102 can be a single crystal or a polycrystalline film, but is preferably a single crystal film.

[0069] The semiconductor film 102 includes a dopant, and the dopant is not particularly limited and can be a well-known dopant. Examples of the dopant include n-type dopants such as Sn, Ge, Si, Ti, Zr, V, Nb, and Pb, and p-type dopants such as Cu, Ag, Ir, and Rh. In the present invention, Sn, Ge, or Si can be used as the dopant, more preferably Sn or Ge, and most preferably Sn. When Sn or Ge is used as the dopant, the content in the semiconductor film can be 1×10 16 cm -3 ~1×10 22 cm -3 , preferably 1×10 18 cm -3 ~1×10 21 cm -3 When the thickness is within such a range, a semiconductor film 102 having a low resistance value and excellent electrical characteristics which is more suitable for use in semiconductor devices can be formed.

[0070] The present invention is characterized in that the Si content in the semiconductor film is within a predetermined range. However, as described above, Si may be used as a dopant. The lower limit of the Si content in the semiconductor film when Si is used as a dopant is preferably 1×10 16 cm -3 The Si content is more preferably 1×10 18 cm -3 ~3×10 20 cm -3 When the thickness is within such a range, an increase in resistivity can be suppressed, sufficient electrical characteristics can be obtained, and a semiconductor film 102 having a low resistance value and excellent electrical characteristics that is more suitable for use in semiconductor devices can be formed.

[0071] (Substrate)

[0072] On the other hand, the substrate 101 is not particularly limited as long as it is a crystalline substrate on which an oxide semiconductor film having a corundum structure can be formed. It is preferred to use a substrate having a corundum structure on the entire surface or a portion of the main surface. It is more preferred to use a substrate having a corundum structure on the entire surface or a portion of the main surface on the crystal growth surface side, and it is further preferred as long as it is a substrate having a corundum structure on the entire surface of the main surface on the crystal growth surface side. Specifically, α-Al2O3 (sapphire substrate) or α-gallium oxide is suitable. In addition, in the present invention, as long as the main surface is a c-plane, the electrical characteristics can be further improved, so it is preferred. In addition, the crystal plane of the main surface of the substrate 101 may have an off angle (Off angle). At this time, it is usually better to make the off angle 0.1° to 10.0°.

[0073] Here, the off-angle refers to the smaller angle between the normal vector of the main surface (surface) of the semiconductor film or substrate and the normal vector of the low-index crystal plane. In addition, in the present invention, the off-angle refers to the smaller angle between the normal vector of the main surface (surface) of the semiconductor film or substrate and the normal vector of the low-index crystal plane. Figure 1 The angles formed by the normal vectors of the crystal planes specified in (e.g., c-plane, a-plane, m-plane, r-plane) are compared, and the plane with the smallest angle is called a low-index plane. In the present invention, when the substrate 101 has an off-angle, the c-plane is preferably the main plane.

[0074] The shape of the substrate 101 is not particularly limited as long as it is plate-shaped and can serve as a support for the semiconductor film 102. In addition, it can be an approximately circular shape (e.g., a circle, an ellipse, etc.), or a polygonal shape (e.g., a triangle, a square, a rectangle, a pentagon, a hexagon, a heptagon, an octagon, a pentagon, etc.), and various shapes can be used appropriately. In the present invention, the shape of the semiconductor film 102 can be set by forming the shape of the substrate 101 into a desired shape. In addition, in the present invention, a large-area substrate with a diameter of 50 mm or more, more preferably a diameter of 100 mm, can be used. By using such a large-area substrate, the area of ​​the semiconductor film 102 can be increased. In addition, the thickness of the substrate 101 is not particularly limited, and is preferably 0.3 mm to 3 mm, and more preferably 0.4 to 1 mm. As long as the thickness is within this range, the warping is relatively small, and the temperature drop during the formation of the semiconductor film can be suppressed, and the crystallinity is more stable and high.

[0075] Figure 1 2 shows an example in which the semiconductor film 102 is directly formed on the crystalline substrate 101, but the semiconductor film 102 may be formed on other layers formed on the substrate. Figure 2The stacked body 200 shown is an example in which a stress relief layer 203 as an intermediate layer is provided between the crystalline substrate 201 and the semiconductor film 202. This can alleviate the lattice mismatch between the crystalline substrate 201 and the semiconductor film 202, and since the crystallinity of the semiconductor film 202 is improved, the electrical characteristics can be further improved.

[0076] For example, when an α-gallium oxide film is formed on an α-Al2O3 substrate, as the stress relief layer 203, for example, α-Fe2O3, α-Ga2O3, α-Al2O3 and their mixed crystals are suitable. At this time, it is preferred that the lattice constant of the stress relief layer 203 is changed continuously or in stages from a value close to or the same as the lattice constant of the crystal substrate 201 to a value close to or the same as the lattice constant of the semiconductor film 202 in the growth direction of the stress relief layer 203. That is, with (Al x Ga 1-x )2O3 (0≤x≤1) forms a stress relief layer 203 and preferably reduces the x value from the substrate 201 side to the semiconductor 202 side.

[0077] The method for forming the stress relief layer 203 is not particularly limited, and may be a known method, or may be the same as the method for forming the semiconductor film 202. In addition, the stress relief layer 203 may or may not contain a dopant.

[0078] The semiconductor film of the present invention has not only low resistance but also excellent electrical properties and is useful in industry. Such a semiconductor film can be suitably used in semiconductor devices and the like, and is particularly useful in power devices. For example, the semiconductor film of the present invention can be used in an n-type semiconductor layer (including n + Type semiconductor layer, n - In addition, the laminate of the present invention may be used directly, or the laminate of the present invention may be applied to a semiconductor device or the like after peeling off the semiconductor film from a crystal substrate or the like using a known means.

[0079] In addition, semiconductor devices can be classified into horizontal elements (horizontal devices) in which electrodes are formed on one side of a semiconductor layer, and vertical elements (vertical devices) in which electrodes are respectively formed on both sides of the semiconductor layer. At least a part of the laminate of the present invention can be used for both horizontal devices and vertical devices. It is particularly preferred to use it for vertical devices.

[0080] Examples of the semiconductor device include a Schottky barrier diode (SBD), a metal semiconductor field effect transistor (MESFET), a high electron mobility transistor (HEMT), a metal oxide semiconductor field effect transistor (MOSFET), a junction field effect transistor (JFET), an insulated gate bipolar transistor (IGBT), or a light emitting element (light emitting diode, LED).

[0081] Hereinafter, the laminate or semiconductor film of the present invention will be described using the drawings. + Type semiconductor layer or n - The preferred examples of making a semiconductor device by using a semiconductor layer (such as a semiconductor layer) are described below, but the present invention is not limited to these examples. In addition, the semiconductor device exemplified below may further include other layers (such as an insulator layer or a conductor layer) according to the specifications or purposes, and of course, an intermediate layer or a buffer layer may be appropriately added or omitted.

[0082] Figure 3 The SBD 300 is an example of a Schottky barrier diode (SBD). The SBD 300 has a relatively low concentration of doped n - The n-type semiconductor layer 301a is doped with a relatively high concentration of n + type semiconductor layer 301 b , Schottky electrode 302 and ohmic electrode 303 .

[0083] The materials of the Schottky electrode 302 and the ohmic electrode 303 can be known electrode materials. Examples of the electrode materials include metals such as Al, Mo, Co, Zr, Sn, Nb, Fe, Cr, Ta, Ti, Au, Pt, V, Mn, Ni, Cu, Hf, W, Ir, Zn, In, Pd, Nd or Ag or their alloys, metal oxide conductive films such as tin oxide, zinc oxide, rhenium oxide, indium oxide, indium tin oxide (ITO), indium zinc oxide (IZO), organic conductive compounds such as polyaniline, polythiophene or polypyrrole, or mixtures thereof and stacks thereof.

[0084] The Schottky electrode 302 and the ohmic electrode 303 can be formed by, for example, a known method such as vacuum evaporation or sputtering. More specifically, when the Schottky electrode is formed using two of the electrode materials (the first metal and the second metal), the layer formed by the first metal and the layer formed by the second metal are stacked, and the layer formed by the first metal and the layer formed by the second metal are patterned by photolithography, thereby forming the Schottky electrode.

[0085] When a reverse bias is applied to the SBD 300, the depletion layer (not shown) - The electrons extend in the Schottky type semiconductor layer 301a to form a high withstand voltage SBD 300. In addition, when a forward bias is applied, electrons flow from the ohmic electrode 303 to the Schottky electrode 302. Therefore, the SBD to which the stacked body or semiconductor film of the present invention is applied is excellent in high withstand voltage and large current, has a fast switching speed, and is excellent in withstand voltage and reliability.

[0086] Figure 4The HEMT 400 is an example of a high electron mobility transistor (HEMT). The HEMT 400 includes an n-type semiconductor layer 401 with a wide bandgap, an n-type semiconductor layer 402 with a narrow bandgap, and an n + type semiconductor layer 403, a semi-insulator layer 404, a buffer layer 405, a gate electrode 406, a source electrode 407 and a drain electrode 408.

[0087] Figure 5 is an example of a metal oxide semiconductor field effect transistor (MOSFET). MOSFET500 has n - Type semiconductor layer 501, n + type semiconductor layers 502 and 503, a gate insulating film 504, a gate electrode 505, a source electrode 506 and a drain electrode 507.

[0088] Figure 6 It is an example of an insulated gate bipolar transistor (IGBT). The IGBT 600 includes an n-type semiconductor layer 601, an n - Type semiconductor layer 602, n + type semiconductor layer 603, p-type semiconductor layer 604, gate insulating film 605, gate electrode 606, emitter electrode 607 and collector electrode 608.

[0089] Figure 7 The LED 700 is an example of a light emitting element (light emitting diode, LED). The LED 700 includes a first electrode 701 , an n-type semiconductor layer 702 , a light emitting layer 703 , a p-type semiconductor layer 704 , a light transmissive electrode 705 , and a second electrode 706 .

[0090] As the material of the light-transmitting electrode 705, conductive materials including oxides of In or Ti can be listed. More specifically, for example, In2O3, ZnO, SnO2, Ga2O3, TiO2, CeO2, or mixed crystals of two or more thereof or materials doped therewith can be listed. By setting these materials by known means such as sputtering, the light-transmitting electrode 705 can be formed. In addition, after the light-transmitting electrode 705 is formed, thermal annealing for the purpose of making the light-transmitting electrode 705 transparent can be performed.

[0091] As materials for the first electrode 701 and the second electrode 706, for example, metals such as Al, Mo, Co, Zr, Sn, Nb, Fe, Cr, Ta, Ti, Au, Pt, V, Mn, Ni, Cu, Hf, W, Ir, Zn, In, Pd, Nd or Ag or alloys thereof, metal oxide conductive films such as tin oxide, zinc oxide, rhenium oxide, indium oxide, indium tin oxide (ITO), zinc indium oxide (IZO), organic conductive compounds such as polyaniline, polythiophene or polypyrrole, or mixtures thereof, etc. The film forming method of the electrode is not particularly limited, and the electrode can be formed by a method appropriately selected from wet methods such as printing, spraying, and coating, physical methods such as vacuum evaporation, sputtering, and ion plating, and chemical methods such as CVD and plasma CVD in consideration of the suitability of the material.

[0092] In addition, another form of a light emitting element (light emitting diode, LED) is shown in Figure 8 . Figure 8 The light-emitting element 800 is provided with an n-type semiconductor layer 801, a p-type semiconductor layer 802, a light-emitting layer 803, a translucent electrode 805, and a first electrode 804a on a substrate 806, and a second electrode 804b is provided on a partially exposed surface of the n-type semiconductor layer 801 exposed by cutting a part of the n-type semiconductor layer 801.

[0093] Part of the semiconductor device exemplified above can be used in, for example, a system using a power supply device, etc. The power supply device can be produced by connecting the semiconductor device to a wiring pattern, etc., using a known means.

[0094] Fig. 9 An example of a power supply system is shown in FIG. Fig. 9 Use multiple power supply devices and control circuits to form a power supply system. Fig.10 As shown in FIG. 1 , the power supply system can be combined with an electronic circuit and used in a system device. In addition, an example of a power supply circuit diagram of a power supply device is shown in FIG. Fig.11 . Fig.11 The power circuit of the power supply device composed of the main circuit (Power Circuit) and the control circuit is shown. After the DC voltage is converted into AC by high-frequency switching using an inverter (MOSFET: composed of A~D), it is insulated and transformed by a transformer, rectified by a rectifying MOSFET (A~B), and smoothed by DCL (smoothing coils L1, L2) and a capacitor to output a DC voltage. At this time, the output voltage is compared with the reference voltage by a voltage comparator, and the inverter and rectifying MOSFET are controlled by a PWM control circuit to form the required output voltage.

[0095] Next, refer to Fig.12 right Figure 1The present invention will be described with reference to examples of the manufacturing apparatus and method for the laminated body described in the , and in particular, will be described mainly with reference to the film forming apparatus and method for forming a semiconductor film, but the present invention is not limited thereto.

[0096] (Film forming device)

[0097] Fig.12 An example of an apparatus used in the method for producing a laminated body of the present invention is shown in . In the production of the laminated body of the present invention, an atomization CVD apparatus 900 is used as a film forming apparatus for forming a semiconductor film.

[0098] Here, the mist in the present invention is a general term for liquid particles dispersed in a gas, including substances called mist, liquid droplets, etc.

[0099] The atomizing CVD device 900 comprises: an atomizing section 9A for atomizing a raw material solution to generate mist; a carrier gas supplying section 9B for supplying a carrier gas for transporting the mist; a film forming section 9C for causing a thermal reaction of the mist to form a film on a substrate; and a transporting section 9D for connecting the atomizing section 9B and the film forming section 9C and transporting the mist through the carrier gas.

[0100] (Conveying Department)

[0101] First, the conveying section 9D connecting the atomizing section 9A and the film forming section 9C will be described. The film forming apparatus of the present invention is characterized in that at least the surface of the conveying section that contacts the mist in the mixed gas is a non-silicone resin. As described above, after discovering that Si in the semiconductor film is an obstacle to low resistivity, the inventors of the present application conducted a careful study and found that, in the film forming apparatus, Si is mixed into the semiconductor film due to contact with the components constituting the film forming apparatus during the period before the raw material is atomized and reacts in the film forming section. Therefore, it was found that by making the surface (portion) of the conveying section 9D connecting the atomizing section 9A and the film forming section 9C that contacts the mist in the mixed gas a non-Si-containing material, especially a non-silicone resin, the mixing of Si can be suppressed during the formation of the semiconductor film.

[0102] The structure of the conveying part 9D is not particularly limited, and it is easiest to use a pipeline. At this time, it is sufficient to make the surface that the mist contacts non-silicone resin. It is also possible to use a silicon-containing material such as a silicone resin on the outside and only make the inner surface that the mist contacts non-silicone resin.

[0103] When the delivery pipes 903 and 906 are used as the delivery part 9D, as long as the material of the delivery pipes 903 and 906 is a non-silicone resin, it can be appropriately selected according to the solvent of the precursor or the temperature coordinated with the reactor and the delivery pipe. In the film forming device of the present invention, it is preferred to use a resin pipe. The resin pipe is flexible, and the operability and the overall design of the film forming device become easy.

[0104] As specific materials for the resin pipe, polyethylene, polypropylene, vinyl chloride, polystyrene, polyvinyl acetate, urethane resin, fluororesin, acrylonitrile butadiene styrene resin, acrylic resin, polyamide, polyimide, polyamide-imide, nylon, acetal resin, polycarbonate, polyphenylene ether, polyester, polyethylene terephthalate, polybutylene terephthalate, polyolefin, polyphenylene sulfide, polysulfone, polyether sulfone, polyarylate, polyether ether ketone can be appropriately used. Fluororesin is particularly preferably used. By using these resins on the surface of the conveying part that contacts the mist, it is possible to effectively suppress the mixing of Si in the mist, so that a semiconductor film with excellent electrical properties can be obtained.

[0105] Although Fig.12 The example of the transport section 9D shown shows a structure in which the atomizer 902b and the film forming chamber 909 are connected by the transport pipe 906, and the transport pipe 903 from the atomizer 902a merges with the transport pipe 906 midway, but the transport pipe 903 and the transport pipe 906 may be independently connected to the film forming chamber 909. Moreover, it is not limited to this, and the first mixed gas and the second mixed gas may be introduced into a single buffer tank (not shown), and the mist mixed in the buffer tank may be transported to the film forming chamber 909 via the transport pipe.

[0106] (Atomization part)

[0107] The atomizing section 9A, for example, includes atomizers 902a and 902b, in which the first precursor 912a and the second precursor 912b are stored as raw material solutions, respectively. As the first precursor 912a and the second precursor 912b, for example, an organic metal complex of a metal (such as an acetylacetone complex, etc.) or an acid solution formed by dissolving a metal in an acid or an aqueous solution of a halide (such as a fluoride, chloride, bromide or iodide, etc.) can be cited. The metal is not limited as long as it is a metal that can form a corundum structure as a metal oxide crystal, for example, Al, Ti, V, Cr, Fe, Ga, Rh, In, and Ir can be cited. In addition, the components of the first precursor 912a and the second precursor 912b can be the same or different. Furthermore, the number of atomizers and the type of precursor can be increased or decreased according to the composition or stacked structure of the film formed on the substrate. The content of the metal in the raw material solution is not particularly limited and can be appropriately set according to the purpose or specification, but is preferably 0.001 mol% to 50 mol%, and more preferably 0.01 mol% to 5 mol%.

[0108] The solvent of the raw material solution is not particularly limited and may be an inorganic solvent such as water, an organic solvent such as alcohol, or a mixed solvent of an inorganic solvent and an organic solvent, but water is preferably used.

[0109] In order to impart conductivity to the semiconductor film, doping is performed, and the impurity raw materials used are not particularly limited. For example, when the metal contains at least Ga, a complex or compound containing Si, Ge or Sn can be appropriately used, and tin halide is particularly preferred. These impurity raw materials can be mixed with 0.0001% to 20% relative to the metal element concentration in the raw material solution, and more preferably 0.001% to 10%.

[0110] In the atomizing section 9A, the raw material solution is atomized using an atomizing means (also referred to as "atomizing" or "dropletizing") not shown in the figure. The atomization of the raw material solution is not particularly limited as long as the raw material solution can be atomized, and preferably an ultrasonic atomizing means is used. The initial velocity of the mist obtained using ultrasonic waves is zero and floats in the air, for example, the mist is not blown in the form of a spray but transported in a state of floating in space, so it can suppress damage caused by collision energy, which is particularly suitable.

[0111] (Carrier gas supply unit)

[0112] The carrier gas supply unit 9B is a supply means for supplying a carrier gas 901 for conveying mist. In the carrier gas supply unit 9B, the carrier gas 901 used is not particularly limited. For example, in addition to air, oxygen, and ozone, inert gases such as nitrogen or argon, or reducing gases such as hydrogen and forming gas (forming-gas) can be appropriately used. The type of carrier gas can be one or more than two. In addition, a pipeline connected to the atomizing unit 9A, valves 904, 905, and other airflow adjustment means can be appropriately set in the carrier gas supply unit 9B.

[0113] In addition, although not shown in the figure, a dilution gas may be added to adjust the ratio of the atomized raw material to the carrier gas. The flow rate of the dilution gas may be appropriately set, and may be set to 0.1 to 10 times / minute of the carrier gas. The dilution gas may be supplied, for example, to the downstream side of the atomizers 902a and 902b. The dilution gas may be the same gas as the carrier gas, or a gas different from the carrier gas.

[0114] (Film Forming Department)

[0115] The film forming section 9C includes a film forming chamber 909 having a susceptor 908 therein. The structure of the film forming chamber 909 is not particularly limited, and metals such as aluminum or stainless steel may be used. When film formation is performed at a higher temperature than the heat-resistant temperature of these metals, quartz or silicon carbide may be used. A heating means 910 for heating the crystal substrate 907 is provided inside or outside the film forming chamber 909. In addition, the substrate 907 may be placed on the susceptor 908 provided in the film forming chamber 909.

[0116] Reference Fig.12 , a specific example of the film forming method of the present invention is described.

[0117] (Film Forming Method)

[0118] The film forming method of the present invention is characterized in that it comprises: a step of forming a mixed gas containing at least an atomized metal oxide precursor, a carrier gas and a dopant; a step of transporting the mixed gas to a film forming section via a transport section; and a step of causing the mixed gas to undergo a thermal reaction in the film forming section to form a semiconductor film on a substrate, wherein at least the surface of the transport section that is in contact with the mixed gas is a non-silicone resin.

[0119] (Mixture formation)

[0120] First, the raw material solution is atomized in the atomizing section 9A by using a known means to form mist. The size of the mist is not particularly limited, and may be droplets of about several mm, preferably 50 μm or less, and more preferably 0.1 to 10 μm.

[0121] The carrier gas supplied to the atomizing section 9A by the carrier gas supply section is mixed with the atomized raw material solution (precursor) formed in the atomizers 902 a and 902 b to form a mixed gas.

[0122] The flow rate of the carrier gas can be appropriately set according to the size of the substrate or the size of the film forming chamber, and can be about 0.01 to 40 L / min. In addition, the film formation can be carried out under any conditions of atmospheric pressure, pressurization and reduced pressure. In terms of device cost or productivity, it is preferably carried out under atmospheric pressure.

[0123] (Transportation of mixed gas)

[0124] The mixed gas containing mist is transported by the transport section 9D connecting the atomizing section 9A and the film forming section 9C. At this time, since the surface of the transport section in contact with the mixed gas is a non-silicone resin, mixing of Si into the mist in the mixed gas can be suppressed.

[0125] (Film formation of semiconductor films)

[0126] The mixed gas containing mist supplied to the film forming chamber 909 of the film forming unit 9C reacts on the crystalline substrate 907 heated by the heat source 910 in the film forming chamber 909 to form a semiconductor film having a corundum structure. The substrate temperature at this time should be appropriately determined according to the type of film formed on the substrate. For example, when an α-gallium oxide film is formed, it can be 350° C. to 950° C. If it is within this range, a semiconductor film with high crystallinity can be obtained. In addition, the film thickness can be set by adjusting the film forming time or the spray amount of the precursor and the carrier gas flow rate.

[0127] (Other Examples of Film Formation Methods)

[0128] When a stress relief layer is further formed between the semiconductor layer and the substrate, first, a first mixed gas is formed by mixing the carrier gas 901 and the atomized first precursor formed by the atomizer 902a, and then a second mixed gas is formed by mixing the carrier gas 901 and the atomized second precursor formed by the atomizer 902b.

[0129] Next, the first mixed gas and the second mixed gas are transported to a crystal substrate 907 placed on a base 908 in a film forming chamber 909 and heated by a heating means 910, and the precursor reacts on the surface of the substrate to form a semiconductor with a corundum structure mixed with the components of the first precursor and the components of the second precursor. The carrier gas flow rate of the first mixed gas and the second mixed gas or one of them can be varied discretely or continuously within a specified time. For example, when a stress relief layer is formed between a sapphire substrate and gallium oxide, (Al x Ga 1-x )2O3 (0≤x≤1) forms a stress relief layer, and it is better to reduce the x value from the substrate side to the growth direction side. To this end, when a first mixed gas containing an Al source and a second mixed gas containing a Ga source are supplied to the film forming chamber 909, the concentration of the precursor or the carrier gas flow rate is adjusted in such a way that the Al supply amount is relatively larger than the Ga supply amount. In addition to this, the initial film formation can be performed using a mixed gas of an Al-Ga precursor in which an Al source and a Ga source are mixed in a certain proportion, and then a plurality of Al-Ga precursors with relatively phased reductions in Al concentration are repeatedly stacked to form a phased reduction in the Al composition (Al x Ga 1-x )2O3 multilayer film. In addition, the substrate temperature at this time should be appropriately determined according to the type of film formed on the substrate. For example, when forming (Al x Ga 1-x )2O3 (0≤x≤1) film, the temperature can be between 350°C and 950°C. Within this range, a semiconductor film with higher crystallinity can be obtained. In addition, the film thickness can be set by adjusting the film formation time.

[0130] Example

[0131] Hereinafter, the present invention will be described in detail with reference to Examples, but the present invention is not limited thereto.

[0132] (Example 1)

[0133] Fig.12In a film forming device, only one atomizer was used to form a film of α-gallium oxide according to the following steps. First, gallium acetylacetonate was adjusted to an aqueous solution with a Ga concentration of 0.10 mol / L. Tin (II) chloride was added to the aqueous solution in a manner that the atomic ratio of Sn to Ga concentration was 1:0.005, and 1.0% hydrochloric acid by volume was further added to make it a raw material solution. The raw material solution was filled in the atomizer.

[0134] Next, an α-(Al x Ga 1-x A 2-inch (50 mm) diameter c-plane sapphire substrate with a 220 multilayer film (undoped, 0.02≤x≤0.2) is placed on a quartz base and set in a quartz tubular film-forming chamber, and the substrate temperature is maintained at 430°C by a heater.

[0135] Next, the raw material solution in the atomizer was atomized using a 2.4 MHz ultrasonic oscillator. Then, nitrogen as a carrier gas was introduced into the atomizer at 1.0 L / min, and nitrogen as a dilution gas was further introduced at 0.5 L / min to form a mixed gas, which was supplied to the film forming chamber through a polytetrafluoroethylene delivery pipe (PTFE tube) and film-formed for 60 minutes under atmospheric pressure to form an α-gallium oxide film with a film thickness of 3.5 μm.

[0136] After cooling the substrate to room temperature, the substrate was taken out of the film forming chamber and the carrier concentration, resistivity and mobility were measured by the Van der Pauw method (ACCENT HL5500). In addition, the Si concentration in the film was measured by SIMS (CAMECA IMS-7f). In this measurement, the detection limit of Si was 5×10 14 cm -3 .

[0137] (Example 2)

[0138] A 3.5 μm thick α-gallium oxide film was formed in the same manner as in Example 1, except that the mixed gas delivery pipe was made of vinyl chloride. Then, the substrate was cooled to room temperature and taken out from the film forming chamber, and the carrier concentration, resistivity, mobility, and Si concentration in the film were measured in the same manner as in Example 1.

[0139] (Example 3)

[0140] A 3.5 μm thick α-gallium oxide film was formed in the same manner as in Example 1, except that the mixed gas delivery pipe was made of polyethylene. Then, the substrate was cooled to room temperature and taken out from the film forming chamber, and the carrier concentration, resistivity, mobility, and Si concentration in the film were measured in the same manner as in Example 1.

[0141] (Example 4)

[0142] A 3.5 μm thick α-gallium oxide film was formed in the same manner as in Example 1, except that the mixed gas delivery pipe was made of urethane resin. Then, the substrate was cooled to room temperature and taken out from the film forming chamber, and the carrier concentration, resistivity, mobility, and Si concentration in the film were measured in the same manner as in Example 1.

[0143] (Example 5)

[0144] To an aqueous solution prepared by adjusting gallium chloride so as to have a Ga concentration of 0.10 mol / L, germanium oxide was added so as to have an atomic ratio of Ge as a dopant to the Ga concentration of 1:0.005, and 1.0% by volume of hydrochloric acid was further added, and the resulting solution was used as a raw material solution. Film formation was performed in the same manner as in Example 1 to form an α-gallium oxide film having a film thickness of 2.0 μm. Then, the substrate was cooled to room temperature and taken out from the film forming chamber, and the carrier concentration, resistivity, mobility, and Si concentration in the film were measured in the same manner as in Example 1.

[0145] (Comparative Example 1)

[0146] A 3.5 μm thick α-gallium oxide film was formed in the same manner as in Example 1, except that the mixed gas delivery pipe was made of silicone resin. Then, the substrate was cooled to room temperature and taken out from the film forming chamber, and the carrier concentration, resistivity, mobility, and Si concentration in the film were measured in the same manner as in Example 1.

[0147] (Comparative Example 2)

[0148] A 2.0 μm thick α-gallium oxide film was formed in the same manner as in Example 5, except that the mixed gas delivery pipe was made of silicone resin. Then, the substrate was cooled to room temperature and taken out from the film forming chamber, and the carrier concentration, resistivity, mobility, and Si concentration in the film were measured in the same manner as in Example 1.

[0149] The carrier density, mobility and resistivity of the α-gallium oxide films obtained in Examples 1 to 5 and Comparative Examples 1 to 2 are shown in Table 1. No Si was detected in the semiconductor film of the laminate of the present invention (below the detection limit), and a resistivity of about 4 mΩ·cm was obtained, which was extremely low compared to the comparative example. A semiconductor film with high carrier concentration and high mobility and excellent electrical characteristics was obtained.

[0150] [Table 1]

[0151]

[0152] The present invention is not limited to the above-described embodiments. The above-described embodiments are merely examples, and any technical solution having substantially the same configuration and having the same function and effect as the technical concept described in the claims of the present invention is within the technical scope of the present invention.

Claims

1. A film forming method, comprising: The step of forming a mixed gas comprising at least an atomized metal oxide precursor, a carrier gas and a dopant; The step of conveying the mixed gas to the film forming part via the conveying part; and a step of causing the mixed gas to undergo a thermal reaction in the film forming section to form a semiconductor film on a substrate, The film forming method is characterized in that At least the surface of the conveying portion that contacts the mixed gas is made of a non-silicone resin. The non-silicone resin includes any one or more of polyethylene, polypropylene, vinyl chloride, polystyrene, polyvinyl acetate, urethane resin, acrylonitrile butadiene styrene resin, acrylic resin, polyamide, polyimide, polyamideimide, nylon, acetal resin, polycarbonate, polyphenylene ether, polyester, polyethylene terephthalate, polybutylene terephthalate, polyolefin, polyphenylene sulfide, polysulfone, polyether sulfone, polyarylate, and polyether ether ketone.

2. A film forming device, comprising: An atomizing section for atomizing the raw material solution to generate mist; a carrier gas supply unit for supplying a carrier gas for conveying the mist; a film forming section for causing the mist to undergo a thermal reaction to form a film on a substrate; and a transporting unit that connects the atomizing unit and the film forming unit and transports the mist through the carrier gas, The film forming device is characterized in that At least the surface of the conveying portion in contact with the mist is made of a non-silicone resin. The non-silicone resin includes any one or more of polyethylene, polypropylene, vinyl chloride, polystyrene, polyvinyl acetate, urethane resin, acrylonitrile butadiene styrene resin, acrylic resin, polyamide, polyimide, polyamideimide, nylon, acetal resin, polycarbonate, polyphenylene ether, polyester, polyethylene terephthalate, polybutylene terephthalate, polyolefin, polyphenylene sulfide, polysulfone, polyether sulfone, polyarylate, and polyether ether ketone.

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