Method for producing crystal, crystal, crystal film, semiconductor device, electronic apparatus, and system

Abstract

To provide a method for industrially advantageously producing a crystal excellent in crystallinity and useful for a semiconductor device, etc.SOLUTION: A method for producing a germanium dioxide crystal by crystal growth using a germanium-containing source material, wherein the source material contains antimony and the antimony content is 0.1 mol% or more and 10 mol% or less based on the source material, and the crystal is produced by heating the source material.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for producing germanium dioxide crystals. [Background technology]

[0002] Compared to power semiconductor materials such as silicon carbide and gallium nitride, rutile-structure germanium dioxide (r-GeO2) with a large band gap has attracted attention as a power semiconductor material with high voltage resistance, low loss, and high heat resistance, and is expected to be applied to power devices.

[0003] For example, a laminated structure in which an r-GeO2 crystalline film is laminated on an r-TiO2 (001) substrate has been investigated (Non-Patent Document 1, Patent Document 1, Patent Document 2, and Patent Document 3). However, after the peer review of Non-Patent Document 1, Non-Patent Document 2 was submitted as an erratum (Non-Patent Document 2). It was found that the crystal grains (abnormal grains) described in Non-Patent Document 1 and Patent Document 1 were rutile-type germanium dioxide crystals, and the remaining portions were amorphous. In other words, only the amorphous phase was formed in the majority of the structure, and even if a crystalline phase was formed, crystal grains were only formed in a small area. Therefore, a method for laminating an r-GeO2 crystalline film on the entire surface of a crystal substrate has been eagerly awaited. [Prior art documents] [Non-patent literature]

[0004] [Non-Patent Document 1] H. Takane, K. Kaneko., “Establishment of a growth route of crystallized rutile GeO2 thin film (≧ 1 mm / h) and its structural properties”, Applied Physics Letters Vol.119, pp.062104(1-6) (2021). [Non-patent document 2] H.Takane, K. Kaneko., Erratum: “Establishment of a growth route of crystallized rutile GeO2 thin film (≧1 μm / h) and its structural properties”, Applied Physics Letters Vol.120, 099903(1-3) (2022). [Patent documents]

[0005] [Patent Document 1] International Publication No. 2023 / 008452 [Patent Document 2] International Publication No. 2023 / 008453 [Patent Document 3] International Publication No. 2023 / 008454 Summary of the Invention [Problem to be solved by the invention]

[0006] An object of the present invention is to provide an industrially advantageous method for producing crystals with excellent crystallinity that are useful for semiconductor devices and the like. [Means for solving the problem]

[0007] As a result of extensive research to achieve the above-mentioned object, the present inventors have discovered that a method for producing germanium dioxide crystals by crystal growth using a germanium-containing raw material, characterized in that the raw material also contains antimony, can produce germanium dioxide crystals easily over the entire surface of a crystal substrate at low cost, and the resulting crystal film has excellent crystallinity and is useful for semiconductor devices and the like, and have found that such a production method can solve all of the above-mentioned conventional problems in one fell swoop. Furthermore, after obtaining the above findings, the present inventors conducted further studies and completed the present invention.

[0008] That is, the present invention relates to the following inventions. [1] A method for producing germanium dioxide crystals by crystal growth using a raw material containing germanium, wherein the raw material contains antimony. [2] The method according to [1], wherein the antimony is contained in the raw material at 0.1 mol% or more. [3] The method according to [1], wherein the antimony is contained in the raw material at 10 mol % or less. [4] The method according to [1], wherein the crystal growth is carried out by heating the raw material. [5] The method according to [4], wherein the heating temperature is 500 to 950°C. [6] The method according to [4], wherein the heating is carried out under atmospheric pressure. [7] The method according to [1], wherein the raw material contains a halogen compound. [8] The method according to [1], wherein the raw material contains an antimony-containing halogen compound. [9] The method according to [1], wherein the raw material contains an acid solvent.

[10] The manufacturing method according to [1] above, wherein the crystal growth is carried out on a substrate.

[11] The method according to [1], wherein the crystal growth is carried out after atomizing or dropletizing the raw material.

[12] A crystal obtained by the production method according to any one of [1] to

[11] above.

[13] A laminated structure in which a crystal is laminated on a crystal substrate directly or via another layer, wherein the crystal is the crystal described in

[12] above.

[14] A semiconductor device including a crystal or a laminated structure, wherein the crystal is the crystal described in

[12] above, and the laminated structure is the laminated structure described in

[13] above.

[15] The semiconductor device according to

[14] above, which is a power device.

[16] The semiconductor device according to

[14] , which is a Schottky barrier diode (SBD), a junction barrier Schottky diode (JBS), a metal semiconductor field effect transistor (MESFET), a static induction transistor (SIT), 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 diode (LED).

[17] An electronic device including a semiconductor device, characterized in that the semiconductor device is the semiconductor device described in

[14] above.

[18] A system including an electronic device, characterized in that the electronic device is the electronic device described in

[17] above. [Effects of the Invention]

[0009] The manufacturing method of the present invention can industrially advantageously manufacture crystals with excellent crystallinity that are useful for semiconductor devices and the like. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a schematic diagram illustrating an example of a film-forming apparatus that can be suitably used in the present invention. [Figure 2] 1 is a diagram schematically illustrating an atomization device preferably used in the present invention. [Figure 3] FIG. 1 is a diagram showing the 2θ / ω results of XRD diffraction in Example 1. [Figure 4] FIG. 2 is a diagram showing an AFM image in Example 1. [Figure 5] FIG. 2 is a diagram showing an SEM image in Example 1. [Figure 6] FIG. 1 is a diagram showing an EDS image in Example 1. [Figure 7] FIG. 10 is a diagram showing the 2θ / ω results of XRD diffraction in Example 2. [Figure 8] 1 is a diagram schematically illustrating a preferred example of a Schottky barrier diode (SBD) according to the present invention. [Figure 9]1 is a diagram schematically illustrating a preferred example of a high electron mobility transistor (HEMT) of the present invention. [Figure 10] FIG. 1 is a diagram schematically illustrating a preferred example of a metal oxide semiconductor field effect transistor (MOSFET) of the present invention. [Figure 11] 1 is a diagram schematically illustrating a preferred example of a junction field effect transistor (JFET) of the present invention. [Figure 12] 1 is a diagram schematically illustrating a preferred example of an insulated gate bipolar transistor (IGBT) according to the present invention. [Figure 13] 1 is a diagram schematically illustrating a preferred example of a light-emitting element (LED) of the present invention. [Figure 14] 1 is a diagram schematically illustrating a preferred example of a junction barrier Schottky diode (JBS) of the present invention. [Figure 15] 1 is a schematic cross-sectional side view of an atomization device preferably used in the present invention. FIG. [Figure 16] 1 is a diagram schematically illustrating a preferred example of a metal semiconductor field effect transistor (MESFET) of the present invention. [Figure 17] FIG. 1 is a diagram schematically illustrating a preferred example of a static induction transistor (SIT) of the present invention. [Figure 18] 17A to 17C are schematic diagrams for explaining a part of the manufacturing process of the SIT of FIG. 16. [Figure 20] FIG. 10 is a diagram showing the 2θ / ω results of XRD diffraction in Example 3. [Figure 19] FIG. 10 is a diagram showing the results of an ω scan in the XRD diffraction results in Example 3. [Figure 21] FIG. 10 is a diagram showing an image obtained by EBSD in Example 3. [Figure 22] FIG. 10 is a diagram showing the 2θ / ω results of XRD diffraction in Example 4. [Figure 23] FIG. 1 is a diagram showing the results of 2θ / ω in the XRD diffraction results in Comparative Example 1. DETAILED DESCRIPTION OF THE INVENTION

[0011] The manufacturing method of the present invention is a method for producing germanium dioxide crystals by crystal growth using a germanium-containing raw material, characterized in that the raw material contains antimony. The raw material contains germanium, is a raw material capable of forming germanium dioxide crystals, and contains antimony.

[0012] The germanium dioxide crystal may be a single crystal, a polycrystal, or a mixed crystal. In the present invention, a single crystal is preferred, and a film-like single crystal is more preferred. The germanium dioxide crystal is not particularly limited in terms of crystal structure, and may have a rutile crystal structure or a trigonal crystal structure, but in the present invention, a rutile crystal structure is preferred. The germanium dioxide crystal may be a mixed crystal, but in the present invention, a single crystal containing germanium dioxide as a main component is preferred.

[0013] The antimony content of the raw material is not particularly limited, but in the present invention, the antimony content is preferably 0.1 mol% or more relative to the raw material. It is also preferable in the present invention that the antimony content is 10 mol% or less relative to the raw material. These preferred ranges can result in better quality crystal growth of germanium dioxide crystals.

[0014] In the present invention, the crystal growth is preferably carried out by heating the raw material. The heating temperature is not particularly limited as long as it does not impede the object of the present invention, but is preferably 500 to 950° C. In the present invention, the heating is preferably carried out under atmospheric pressure.

[0015] In the present invention, the raw material preferably contains a halogen compound, and more preferably contains an antimony-containing halogen compound. Furthermore, the raw material is not particularly limited as long as it does not impair the objectives of the present invention, and may contain known solvents such as inorganic solvents such as water, organic solvents such as alcohol, acid solvents, alkaline solvents, or mixtures thereof. However, in the present invention, an acid solvent is preferred. Examples of the inorganic solvent include water, and more specifically, pure water, ultrapure water, tap water, well water, mineral water, hot spring water, spring water, fresh water, and seawater. In the present invention, ultrapure water is preferred. Examples of the acid solvent include hydrofluoric acid, hydrochloric acid, hydrobromic acid, hydroiodic acid, sulfuric acid, phosphoric acid, nitric acid, acetic acid, carbonic acid, formic acid, benzoic acid, hydrogen peroxide, protonic acids such as chlorous acid, hypochlorous acid, sulfurous acid, hyposulfite, nitrous acid, hyponitrous acid, phosphorous acid, and mixtures thereof. Examples of the alkaline solvent include sodium hydroxide, potassium hydroxide, calcium hydroxide, and mixtures thereof. Examples of the organic solvent include ester solvents (e.g., ethyl acetate, propyl acetate, butyl acetate, ethyl propionate, propyl propionate, butyl propionate, etc.), ether solvents (e.g., diethyl ether, tert-butyl methyl ether, diglyme (e.g., diethylene glycol dimethyl ether, diethylene glycol dibutyl ether, diethylene glycol diethyl ether), 1,2-dimethoxyethane, tetrahydrofuran, etc.), amide solvents (e.g., N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpropanol, etc.), and the like. Examples of suitable solvents include methyl isobutyl ketone, methyl ethyl ketone, cyclohexanone, cyclopentanone, nitrile solvents (e.g., acetonitrile, propionitrile, etc.), alcohol solvents (e.g., methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, etc.), halogenated solvents (e.g., methylene chloride, chloroform, etc.), and aromatic solvents (e.g., toluene, xylene, chlorobenzene, nitrobenzene, etc.). Crystals of higher quality and larger area can be easily produced within such a preferred range.

[0016] In the present invention, the crystal growth is preferably carried out on a substrate, and more preferably carried out after atomizing or dropletizing the raw material. By using such a preferable range, it is possible to easily obtain high-quality crystals at lower cost.

[0017] In the present invention, the term "main component" refers to a germanium dioxide content in the crystal of 50% or more in terms of composition ratio in the crystal. In an embodiment of the present invention, the germanium content in the crystal film is preferably 70% or more, more preferably 90% or more, in terms of composition ratio in the crystal film. It is also preferable that the crystal contains germanium dioxide as a main component. In an embodiment of the present invention, the germanium dioxide content in the crystal is preferably 70% or more, more preferably 90% or more, in terms of composition ratio in the crystal. This preferred range results in a better interface, improved thermal conductivity, and improved semiconductor properties. The crystal may also contain a metal or metal oxide other than germanium dioxide. Examples of the other metal include one or more metals selected from Group 14 metals of the periodic table other than germanium (e.g., tin or silicon) and Group 4 metals of the periodic table (e.g., titanium, zirconia, or hafnium). The atomic ratio of germanium dioxide in the crystal is preferably 0.5 or more. By setting the atomic ratio of germanium dioxide in this preferred range, a crystal with better semiconductor properties can be realized. Furthermore, in the present invention, it is preferable that the crystal has a rutile crystal structure. Within this preferred range, the semiconductor properties can be made even better.

[0018] In the present invention, the crystal is not particularly limited as long as it does not impede the object of the present invention, and may be in the form of a film. 2 It is preferable that the area is 100 mm or more. 2It is more preferable that the crystal has an area of ​​1000 nm or more. In the present invention, the crystal is preferably in the form of a film, and is preferably a single crystal. Within these preferable ranges, the crystalline film can have better pressure resistance.

[0019] The laminated structure of the present invention is characterized in that the crystal is laminated on a crystal substrate via another layer. A "laminated structure" is a structure including one or more crystal layers, and may also include layers other than crystal layers (e.g., amorphous layers). The crystal layer is preferably a single crystal layer, but may also be a polycrystalline layer.

[0020] The preferred laminated structure described above can be more easily obtained, for example, by using a film-forming apparatus as shown in FIG. 1. The thickness of the crystal film is not particularly limited as long as it does not impede the object of the present invention, but in the present invention, it is preferably 0.1 μm or more, more preferably 1 μm or more. The surface roughness (RMS) of the crystal film is preferably 10 nm or less. By achieving such a preferred thickness or surface roughness, when the laminated structure is applied to a semiconductor device, the semiconductor device can be endowed with superior electrical properties such as high voltage resistance. The surface roughness (RMS) refers to a value calculated based on JIS B0601 using the surface profile measurement results of a 10 μm square area using an atomic force microscope (AFM).

[0021] The crystal substrate is not particularly limited as long as it does not impede the objectives of the present invention. It may be a known substrate, such as an insulating substrate, a conductive substrate, or a semiconductor substrate. It may be a single crystal substrate or a polycrystalline substrate. The crystal substrate may have a metal film on its surface. When the crystal substrate is a conductive substrate, a vertical device can be fabricated without removing the substrate. The crystal structure of the crystal substrate is also not particularly limited as long as it does not impede the objectives of the present invention. Examples of the crystal structure of the crystal substrate include a hexagonal crystal structure, a cubic crystal structure, and a tetragonal crystal structure. Examples of crystal substrates having a hexagonal crystal structure include a GaN substrate, a SiC substrate, or a sapphire substrate (such as an A-plane sapphire, a c-plane sapphire, an M-plane sapphire, or an R-plane sapphire substrate). Examples of crystal substrates having a tetragonal crystal structure include a GeO2 substrate having a rutile crystal structure, a TiO2 substrate or an MgF2 substrate having a rutile crystal structure, and the like. Examples of crystal substrates having a cubic crystal structure include a Si substrate or a SiC substrate. The crystal substrate may have an off-angle, specifically, for example, from 0.1° to 10°. The present invention also encompasses the laminate structure obtained in this manner.

[0022] In the present invention, a film may be formed directly on the substrate. Alternatively, other layers, such as a layer different from the semiconductor layer (e.g., an n-type semiconductor layer, an n+-type semiconductor layer, an n-type semiconductor layer, etc.), an insulator layer (including a semi-insulator layer), or a buffer layer, may be stacked on the substrate, and then the film may be formed on the substrate via the other layers. In particular, a buffer layer is preferably used to reduce the difference in lattice constant between the crystal substrate and the semiconductor layer. Examples of materials constituting the buffer layer include SnO2, TiO2, VO2, MnO2, RuO2, CsO2, IrO2, GeO2, CuO2, PbO2, AgO2, CrO2, SiO2, SiC, GaN, and mixed crystals thereof.

[0023] The semiconductor layer can be more easily obtained by depositing a crystalline film containing germanium dioxide as a main component or a mixed crystalline film thereof using, for example, the film deposition apparatus shown in Figure 1. Furthermore, doping can also be performed appropriately using the film deposition apparatus. The doped crystal can be suitably used as a semiconductor film or semiconductor layer, and n-type dopants can be applied by conventional doping methods for oxide semiconductors.

[0024] The laminated structure can be used as is or after known processing such as substrate peeling, for example, by known means, for semiconductor devices. Examples of such semiconductor devices include Schottky barrier diodes (SBDs), junction barrier Schottky diodes (JBSs), metal semiconductor field-effect transistors (MESFETs), static induction transistors (SITs), high electron mobility transistors (HEMTs), metal oxide semiconductor field-effect transistors (MOSFETs), junction field-effect transistors (JFETs), insulated gate bipolar transistors (IGBTs), and light-emitting diodes (LEDs). The present invention may also be applied to modules incorporating such semiconductor devices, electronic devices incorporating such semiconductor devices, and components thereof. These semiconductor devices are useful for a variety of applications, particularly power devices. Semiconductor devices can be classified into horizontal devices (horizontal devices) in which an electrode is formed on one side of the semiconductor layer, and vertical devices (vertical devices) in which electrodes are formed on both the front and back sides of the semiconductor layer. In the present invention, the semiconductor device can be used as either a horizontal device or a vertical device.

[0025] Examples of semiconductor devices suitable for use in the present invention will be described in more detail below with reference to the drawings, but the present invention is not limited to these examples. A suitable example in which a crystalline layer containing germanium dioxide as a main component in the crystalline film is used as a semiconductor layer will be shown below.

[0026] 8 shows a preferred example of a Schottky barrier diode (SBD) including an n-type semiconductor layer 101a, an n+ type semiconductor layer 101b, a p-type semiconductor layer 102, a metal layer 103, an insulator layer 104, a Schottky electrode 105a, and an ohmic electrode 105b. The metal layer 103 is made of a metal such as Al, and covers the Schottky electrode 105a.

[0027] FIG. 9 shows a preferred example of a high electron mobility transistor (HEMT) including an n-type semiconductor layer 121a having a wide bandgap, an n-type semiconductor layer 121b having a narrow bandgap, an n+-type semiconductor layer 121c, a p-type semiconductor layer 123, a gate electrode 125a, a source electrode 125b, a drain electrode 125c, and a substrate 129.

[0028] 10 shows a preferred example of a metal oxide semiconductor field effect transistor (MOSFET) including an n-type semiconductor layer 131a, a first n+ type semiconductor layer 131b, a second n+ type semiconductor layer 131c, a p-type semiconductor layer 132, a p+ type semiconductor layer 132a, a gate insulating film 134, a gate electrode 135a, a source electrode 135b, and a drain electrode 135c. Note that the p+ type semiconductor layer 132a may be a p-type semiconductor layer or may be the same as the p-type semiconductor layer 132.

[0029] FIG. 11 shows a preferred example of a junction field effect transistor (JFET) including an n-type semiconductor layer 141a, a first n+ type semiconductor layer 141b, a second n+ type semiconductor layer 141c, a p-type semiconductor layer 142, a gate electrode 145a, a source electrode 145b, and a drain electrode 145c.

[0030] FIG. 12 shows a preferred example of an insulated gate bipolar transistor (IGBT) including an n-type semiconductor layer 151, an n-type semiconductor layer 151a, an n+ type semiconductor layer 151b, a p-type semiconductor layer 152, a gate insulating film 154, a gate electrode 155a, an emitter electrode 155b, and a collector electrode 155c.

[0031] (LED) An example of a case where the semiconductor device of the present invention is a light-emitting diode (LED) is shown in Fig. 13. The semiconductor light-emitting device of Fig. 13 has an n-type semiconductor layer 161 on a second electrode 165b, and a light-emitting layer 163 is laminated on the n-type semiconductor layer 161. A p-type semiconductor layer 162 is laminated on the light-emitting layer 163. A light-transmitting electrode 167 that transmits light generated by the light-emitting layer 163 is provided on the p-type semiconductor layer 162, and a first electrode 165a is laminated on the light-transmitting electrode 167. The semiconductor light-emitting device of Fig. 13 may be covered with a protective layer except for the electrode portion.

[0032] Examples of materials for the translucent electrode include conductive oxide materials containing indium (In) or titanium (Ti). More specifically, examples include In2O3, ZnO, SnO2, Ga2O3, TiO2, CeO2, or mixed crystals of two or more of these, or doped materials thereof. The translucent electrode can be formed by depositing these materials using known means such as sputtering. After the translucent electrode is formed, it may be subjected to thermal annealing to make the translucent electrode transparent.

[0033] In the semiconductor light-emitting device of FIG. 13, the first electrode 165a is a positive electrode and the second electrode 165b is a negative electrode, and current is passed through these electrodes to the p-type semiconductor layer 162, the light-emitting layer 163, and the n-type semiconductor layer 161, causing the light-emitting layer 163 to emit light.

[0034] Examples of materials for the first electrode 165a and the second electrode 165b 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, and Ag, or alloys thereof; conductive metal oxide films such as tin oxide, zinc oxide, indium oxide, indium tin oxide (ITO), and indium zinc oxide (IZO); organic conductive compounds such as polyaniline, polythiophene, and polypyrrole; and mixtures thereof. The method for forming the electrodes is not particularly limited, and they can be formed on the substrate by a method appropriately selected from wet methods such as printing, spraying, and coating; physical methods such as vacuum deposition, sputtering, and ion plating; and chemical methods such as CVD and plasma CVD, taking into consideration their suitability for the material.

[0035] FIG. 14 shows the main components of a junction barrier Schottky diode (JBS) according to a preferred embodiment of the present invention. The JBS shown in FIG. 14 includes an ohmic electrode 1020, an n-type semiconductor layer 1010a, an n+-type semiconductor layer 1010b, a Schottky electrode 1030, and an electric field buffer region 1060. The Schottky electrode 1030 includes metal layers 1030a, 1030b, and 1030c. In the semiconductor device shown in FIG. 14, the outer ends of metal layers 1030a and / or 1030b, which serve as second electrode layers, are located outside the outer end of metal layer 1030c, which serves as a first electrode layer. In the semiconductor device shown in FIG. 14, the electric field buffer region 1060 includes at least two electric field buffer regions 1060 in a plane including at least a portion of the second electrode layer that is located outside the outer end of the first electrode layer and the outer end of the second electrode. In the semiconductor device of FIG. 14, the electric field relaxation region 1060 is made of a p-type semiconductor, and forms a PN junction with the n-type semiconductor layer 1010a.

[0036] 14 may be formed by any known method without particular limitation, as long as it does not impede the object of the present invention, such as forming a film by vacuum deposition, CVD, sputtering, or various coating techniques, followed by patterning by photolithography, or directly patterning by printing or the like.

[0037] (MESFET) Fig. 16 shows an example of a metal semiconductor field effect transistor (MESFET) according to the present invention. The MESFET in Fig. 16 includes an n-type semiconductor layer 111a, an n+ type semiconductor layer 111b, a buffer layer 118, a semi-insulating layer 114, a gate electrode 115a, a source electrode 115b, and a drain electrode 115c.

[0038] The materials for the gate electrode, drain electrode, and source electrode may be known electrode materials, such as 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, and Ag, or alloys thereof; conductive metal oxide films such as tin oxide, zinc oxide, indium oxide, indium tin oxide (ITO), and indium zinc oxide (IZO); organic conductive compounds such as polyaniline, polythiophene, and polypyrrole; or mixtures thereof. The gate electrode, drain electrode, and source electrode can be formed by known means such as vacuum deposition or sputtering.

[0039] The semi-insulating layer 114 may be made of a semi-insulating material, and examples of the semi-insulating material include those containing semi-insulating dopants such as magnesium (Mg), ruthenium (Ru), iron (Fe), beryllium (Be), cesium (Cs), strontium (Sr), and barium (Ba), as well as those that have not been doped.

[0040] In the MESFET of FIG. 16, a good depletion layer is formed under the gate electrode, so that the current flowing from the drain electrode to the source electrode can be efficiently controlled.

[0041] (SIT) Fig. 17 shows an example of the semiconductor device of the present invention as an SIT, which includes an n-type semiconductor layer 241a, n+ type semiconductor layers 241b and 141c, a gate electrode 245a, a source electrode 245b, and a drain electrode 245c.

[0042] An n+ type semiconductor layer 241b having a thickness of, for example, 100 nm to 100 μm is formed on the drain electrode 245c, and an n- type semiconductor layer 241a having a thickness of, for example, 100 nm to 100 μm is formed on the n+ type semiconductor layer 241b. Furthermore, an n+ type semiconductor layer 241c is formed on the n- type semiconductor layer 241a, and a source electrode 145b is formed on the n+ type semiconductor layer 241c.

[0043] Furthermore, a plurality of trenches are formed in the n-type semiconductor layer 241a, penetrating the n+ semiconductor layer 241c and reaching partway through the n-semiconductor layer 241a. Gate electrodes 245a are formed on the n-type semiconductor layer 241a in the trenches.

[0044] 17, when a voltage is applied between the source electrode 245b and the drain electrode 245c and a positive voltage is applied to the gate electrode 245a with respect to the source electrode 245b, a channel layer is formed in the n-type semiconductor layer 241a, electrons are injected into the n-type semiconductor layer 241a, and the SIT is turned on. When the voltage of the gate electrode is set to 0V, no channel layer is formed, and the n-type semiconductor layer is filled with a depletion layer, resulting in the SIT being turned off.

[0045] FIG. 18 illustrates a portion of the manufacturing process of the SIT of FIG. 17. For example, using a stacked structure such as that shown in FIG. 18(a), an etching mask is provided in predetermined regions of the n-type semiconductor layer 241a and the n+-type semiconductor layer 241c. Using the etching mask as a mask, anisotropic etching is performed, for example, by reactive ion etching, to form a trench groove with a depth that extends from the surface of the n+-type semiconductor layer 241c to partway through the n-type semiconductor layer 241a, as shown in FIG. 18(b). Next, a gate electrode material such as polysilicon is formed in the trench groove by a method such as CVD, vacuum deposition, or sputtering, to a thickness equal to or less than the thickness of the n-type semiconductor layer 241a. Furthermore, a source electrode 245b is formed on the n+-type semiconductor layer 241c, and a drain electrode 245c is formed on the n+-type semiconductor layer 241b by a known method such as vacuum deposition, sputtering, or CVD, thereby completing the SIT. The electrode materials of the source electrode and the drain electrode may each be a known electrode material, and examples of the electrode material 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, and Ag, or alloys thereof; conductive metal oxide films such as tin oxide, zinc oxide, indium oxide, indium tin oxide (ITO), and indium zinc oxide (IZO); organic conductive compounds such as polyaniline, polythiophene, and polypyrrole; and mixtures thereof.

[0046] Although the above example shows an example in which a p-type semiconductor is not used, the present invention is not limited to this and a p-type semiconductor may be used. Note that the p-type semiconductor may be the same material as the n-type semiconductor and contain a p-type dopant, or may be a different p-type semiconductor. [Example]

[0047] Example 1 FIG. 1 shows a preferred embodiment of the film-forming apparatus used in this example. The film-forming apparatus 19 comprises a film-forming sample 20, a sample stage 21, a carrier gas source 22a, a carrier gas source 22b, a flow rate control valve 23a, a flow rate control valve 23b, a film-forming chamber 27, a heater 28, and an atomization device 30. The atomization device 30 comprises a raw material partition wall 24, a raw material liquid to be atomized 24a, an ultrasonically-transmitting substrate 24b, a stage 24c, an ultrasonic vibrator 26, a guide partition wall 31, an ultrasonic-transmitting liquid tank 35, and an ultrasonic-transmitting liquid 36. FIG. 2 shows another preferred embodiment of the film-forming apparatus when the atomization device of the present invention is used as a film-forming atomization stage. The atomization device 30 comprises a raw material partition wall 24, a raw material liquid to be atomized 24a, an ultrasonically-transmitting substrate 24b, a stage 24c, an ultrasonic vibrator 26, a guide partition wall 31, an ultrasonic-transmitting liquid tank 35, and an ultrasonic-transmitting liquid 36. The sample stage 21 is made of quartz, and the surface on which the film-forming sample 20 is placed is inclined from the horizontal. By fabricating both the film-forming chamber 27 and the sample stage 21 from quartz, impurities originating from the device are prevented from being mixed into the crystalline film formed on the film-forming sample 20. The atomization raw material liquid 24a was prepared by adding 20% ​​hydrochloric acid by volume, and then adjusting the concentration of antimony chloride relative to the germanium concentration in the atomization raw material liquid 24a to 2 mol%. The atomization raw material liquid 24a was contained in the mist generating source 24. The guide partition 31 is in contact with the ultrasonic-transmitting substrate 38. Figure 15 is a schematic diagram showing a cross-sectional side view of the atomization device used in the present invention. The atomization device 30 in Figure 15 consists of the raw material partition 24, the ultrasonic-transmitting substrate 24b, the base 24c, the ultrasonic vibrator 26, the guide partition 31, and the ultrasonic-transmitting liquid tank 35. The guide partition 31 is in contact with the ultrasonic wave transmission liquid tank 35. By using the guide partition 31, the ultrasonic waves emitted from the ultrasonic vibrator 26 are transmitted to the raw material partition 24 more efficiently.

[0048] Next, a rutile structure TiO2 (001) substrate with a square shape measuring 10 mm on a side and an average thickness of 500 μm was placed on the sample stage 21 as the film formation sample 20, and the heater 28 was operated to raise the temperature inside the film formation chamber 27 to 850°C. Next, the flow rate control valve 23 was opened to supply carrier gas from the carrier gas source 22 into the film formation chamber 27. After the atmosphere inside the film formation chamber 27 was sufficiently replaced with the carrier gas, the flow rate of the carrier gas was adjusted to 3 L / min. Oxygen gas was used as the carrier gas.

[0049] Next, ultrasonic vibrator 26 was vibrated at 3.0 MHz, and the vibration was propagated to atomization liquid 24a through ultrasonic transmitter 25a, thereby atomizing atomization liquid 24a to generate raw material fine particles. These raw material fine particles were introduced into film formation chamber 27 by carrier gas, and reacted in film formation chamber 27, forming a crystalline film of GeO2 having a rutile structure on film formation sample 20 by CVD reaction on the film formation surface of film formation sample 20. The film thickness was 1.1 μm.

[0050] The obtained GeO2 crystalline film was measured using an X-ray diffractometer. Figure 3 shows the XRD diffraction results. As is clear from Figure 3, the obtained crystalline film was a GeO2 single crystal film with a (002) oriented rutile structure. A GeO2 single crystal film with good crystallinity was formed on a TiO2 (001) substrate with a rutile crystalline structure.

[0051] The surface of the obtained GeO2 crystalline film was also observed using an atomic force microscope (AFM). The results are shown in Figure 4. As shown in Figure 4, the surface roughness (RMS) based on JIS B0601 was 1.3 nm, indicating excellent surface smoothness.

[0052] The surface of the obtained GeO2 crystal film was observed using SEM. Figure 5 shows an SEM image. As is clear from Figure 5, GeO2 crystals with excellent surface smoothness and good crystallinity were formed. Furthermore, when the surface of the obtained crystal film was evaluated using EDS, as shown in Figure 6, a crystal film was formed over the entire surface to a thickness of 100 μm. 2It was found that the pores were formed over an area of ​​more than 100m.

[0053] Example 2 In Example 2, a GeO2 crystalline film was produced in the same manner as in Example 1, except that the concentration of antimony chloride was adjusted to 0.2 mol% relative to the concentration of germanium in the atomization raw material liquid 24a. When the obtained GeO2 crystalline film was measured using an X-ray diffraction device, the peak of the obtained rutile structure GeO2 was confirmed as shown in Figure 7, and a single crystal film of GeO2 with good crystallinity was formed on the TiO2 (001) substrate with a rutile crystal structure.

[0054] Example 3 In Example 3, a GeO2 crystalline film was fabricated in the same manner as in Example 1, except that the concentration of antimony chloride relative to the concentration of germanium in the atomization liquid 24a was adjusted to 5 mol % and the temperature inside the film formation chamber 27 was set to 700°C. The resulting GeO2 crystalline film was measured using an X-ray diffractometer, and the peak of the rutile-structured GeO2 was confirmed, as shown in Figure 19. The results of the ω scan in the X-ray diffraction measurement are shown in Figure 20. As shown in Figure 20, the rocking curve half-width at the 002 diffraction peak of r-GeO2 was 936 arcsec. This indicates that a single-crystalline GeO2 film with good crystallinity was formed on a TiO2 (001) substrate with a rutile-structured crystal structure.

[0055] The surface crystalline state of the obtained GeO2 thin film was evaluated by electron backscatter diffraction (EBSD). Figure 21(A) shows the image quality map, and Figure 21(B) shows the inverse pole figure orientation map. The EBSD results in Figure 21 show that the obtained GeO2 thin film has a rutile structure and is a single crystal with excellent orientation.

[0056] Example 4 In Example 4, a GeO2 crystal film was produced in the same manner as in Example 1, except that the concentration of antimony chloride was adjusted to 7 mol% relative to the concentration of germanium in the atomization raw material liquid 24a and the temperature in the film formation chamber 27 was set to 700° C. When the obtained GeO2 crystal film was measured using an X-ray diffraction device, the peak of the obtained rutile structure GeO2 was confirmed as shown in FIG.

[0057] (Comparative Example 1) As Comparative Example 1, a GeO2 crystalline film was produced in the same manner as in Example 1, except that antimony chloride was not added to the atomization raw material liquid 24a. When the obtained GeO2 crystalline film was measured using an X-ray diffraction device, no peak of the obtained rutile structure GeO2 could be confirmed, as shown in Figure 23. From this result, it can be seen that Example 1 of the present invention has superior crystallinity. [Industrial Applicability]

[0058] The manufacturing method of the present invention is used, for example, in manufacturing crystals used in semiconductor devices (such as compound semiconductor electronic devices), electronic components and electrical equipment parts, optical and electrophotographic related devices, industrial materials, and the like. [Explanation of symbols]

[0059] 19 Film forming equipment 20 Film sample 21 Sample stage 22a Carrier gas source 22b Dilution gas source 23a Flow control valve 23b Flow control valve 24 Raw material bulkhead 24a Raw material liquid for atomization 24b Ultrasonic transparent base material 24c units 26 Ultrasonic vibrator 27 Film forming room 28 Heater 30 Atomization device 31 Guide bulkhead 33 Dilution gas supply pipe 34 Carrier gas supply pipe 35 Ultrasonic transmission fluid tank 36 Ultrasonic transmission fluid 37 Film forming room 101a n-type semiconductor layer 101b n+ type semiconductor layer 102 p-type semiconductor layer 103 Metal layer 104 Insulator layer 105a Schottky electrode 105b Ohmic electrode 111a n-type semiconductor layer 111b n+ type semiconductor layer 114 Semi-insulating layer 115a gate electrode 115b Source electrode 115c Drain electrode 118 Buffer layer 121a Wide bandgap n-type semiconductor layer 121b Narrow bandgap n-type semiconductor layer 121c n+ type semiconductor layer 123 p-type semiconductor layer 124 Semi-insulating layer 125a Gate electrode 125b Source electrode 125c drain electrode 128 Buffer layer 129 PCB 131a n-type semiconductor layer 131b First n+ type semiconductor layer 131c second n+ type semiconductor layer 132 p-type semiconductor layer 134 Gate insulating film 135a gate electrode 135b Source electrode 135c Drain electrode 138 Buffer layer 139 Semi-insulating layer 141a n-type semiconductor layer 141b First n+ type semiconductor layer 141c second n+ type semiconductor layer 142 p-type semiconductor layer 145a Gate electrode 145b Source electrode 145c Drain electrode 151 n-type semiconductor layer 151a n-type semiconductor layer 151b n+ type semiconductor layer 152 p-type semiconductor layer 154 Gate insulating film 155a Gate electrode 155b Emitter electrode 155c Collector electrode 161 n-type semiconductor layer 162 p-type semiconductor layer 163 Light-emitting layer 165a first electrode 165b second electrode 167 Translucent electrode 169 PCB 1010a n-type semiconductor 1010b n+ type semiconductor 1020 Ohmic electrode 1030 Schottky electrode 1030a metal layer 1030b metal layer 1030c metal layer 1060 Electrolytic relaxation region

Claims

1. A method for producing germanium dioxide crystals by crystal growth using a raw material containing germanium, wherein the raw material contains antimony.

2. 2. The method according to claim 1, wherein the raw material contains antimony in an amount of 0.1 mol % or more.

3. 2. The method according to claim 1, wherein the content of antimony in the raw material is 10 mol % or less.

4. 2. The method according to claim 1, wherein the crystal growth is carried out by heating the raw material.

5. The method according to claim 4, wherein the heating temperature is 500 to 950°C.

6. The method according to claim 4, wherein the heating is carried out under atmospheric pressure.

7. The method according to claim 1 , wherein the raw material contains a halogen compound.

8. 2. The method according to claim 1, wherein the raw material comprises an antimony-containing halogen compound.

9. The method according to claim 1 , wherein the raw material comprises an acid solvent.

10. 2. The method according to claim 1, wherein the crystal growth is carried out on a substrate.

11. 2. The method according to claim 1, wherein the crystal growth is carried out after the raw material is atomized or converted into droplets.

12. A crystal obtained by the production method according to any one of claims 1 to 11.

13. A layered structure in which a crystal is layered on a crystal substrate directly or via another layer, the crystal being the crystal according to claim 12.

14. A semiconductor device including a crystal or a laminated structure, wherein the crystal is the crystal according to claim 12, and the laminated structure is the laminated structure according to claim 13.

15. 15. The semiconductor device according to claim 14, which is a power device.

16. 15. The semiconductor device according to claim 14, which is a Schottky barrier diode (SBD), a junction barrier Schottky diode (JBS), a metal semiconductor field effect transistor (MESFET), a static induction transistor (SIT), 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 diode (LED).

17. 15. An electronic device including a semiconductor device, wherein the semiconductor device is the semiconductor device according to claim 14.

18. A system including an electronic device, wherein the electronic device is the electronic device according to claim 17.

Images