Method for preparing doping raw material solution for film formation, method for producing laminate, doping raw material solution for film formation, and semiconductor film

Abstract

The present invention relates to a method for preparing a film-forming dopant raw material solution, characterized by comprising the step of preparing a dopant precursor solution separately from the film-forming raw material by first mixing a solute with a first solvent, rather than mixing it with other solvents. The solute comprises a halogen-containing organic dopant compound or a dopant halide, and the preparation method uses an acidic solvent as the first solvent. This method provides a method for preparing a film-forming dopant raw material solution capable of stably forming high-quality thin films with excellent electrical properties.

Description

Technical Field

[0001] The present invention relates to a method for preparing a doping raw material solution for film formation, a method for producing a laminate, a doping raw material solution for film formation, and a semiconductor film. Background Art

[0002] A mist chemical vapor deposition (Mist CVD) method (hereinafter referred to as "Mist-CVD") has been developed to grow crystals on substrates using an atomized, mist-like raw material. This method is capable of producing gallium oxide (α-Ga2O3) with a corundum structure. In this method, a raw material solution, prepared by dissolving a gallium compound such as gallium acetylacetonate in an acid such as hydrochloric acid, is atomized (also called misting) to generate raw material particles. A mixed gas composed of these raw material particles and a carrier gas is then supplied to the surface of a corundum substrate such as sapphire. The reaction between the raw material mist and the substrate allows epitaxial growth of a unidirectional gallium oxide thin film.

[0003] Furthermore, when such a grown film is used as an electronic device, it needs to be doped with impurities to impart conductivity. Doping is typically performed by adding a dopant precursor solution containing a tetravalent dopant to the raw material solution, or by atomizing the precursor solution and mixing them in a mist-like state. Patent Document 1 describes an example in which an aqueous solution is adjusted so that the molar ratio of gallium bromide to tin bromide is 1:0.01. In this case, a raw material solution containing 10% by volume of a 48% hydrobromic acid solution is used to dope α-gallium oxide with Sn. Patent Document 2 also describes an example of Si doping, using a solution prepared by adding hydrochloric acid to an aqueous solution prepared by mixing gallium acetylacetonate and 3-cyanopropyldimethylchlorosilane. Furthermore, Patent Document 3 describes an example in which germanium oxide is used as a dopant source, and gallium bromide and germanium oxide are mixed in ultrapure water to serve as the raw material solution.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Laid-Open No. 2015-196603

[0007] Patent Document 2: International Publication No. WO2018 / 052097

[0008] Patent Document 3: Japanese Patent Application Laid-Open No. 2018-35044 Summary of the Invention

[0009] Technical Problems to be Solved by the Invention

[0010] However, the methods described in Patent Documents 1, 2, and 3 suffer from problems such as unstable dopant precursors in solution, resulting in insufficient doping in the grown film, or by-products introducing defects into the grown film, which degrades the electrical properties of the grown film. Consequently, particularly when forming films over large areas, the electrical properties of the grown film become non-uniform, significantly reducing film productivity.

[0011] The present invention is made to solve the above-mentioned problems, and its purpose is to provide a method for preparing a doping raw material solution for film formation, and a method for manufacturing a laminate using the preparation method, wherein the doping raw material solution for film formation can stably form a high-quality thin film with excellent electrical properties.

[0012] In addition, the present invention also aims to provide a doping raw material solution for film formation and a preparation method thereof, as well as a method for manufacturing a laminate using the doping raw material solution for film formation, wherein the doping raw material solution for film formation can stably form a high-quality and large-area thin film with excellent electrical properties.

[0013] Another object of the present invention is to provide a semiconductor film having a large area and good resistivity distribution.

[0014] Technical means to solve technical problems

[0015] In order to solve the above technical problems, the present invention provides a method for preparing a doping raw material solution for film formation, characterized in that:

[0016] The method comprises the steps of preparing a dopant precursor solution by mixing a solute with a first solvent instead of mixing the solute with other solvents, thereby preparing the dopant precursor solution separately from the film-forming raw material, wherein the solute comprises a halogen-containing organic dopant compound or a dopant halide.

[0017] The preparation method uses an acidic solvent as the first solvent.

[0018] According to this method, by first preparing a doping precursor solution in an acidic solvent separately from the film-forming raw material without mixing a solute containing a halogen-containing organic dopant compound or a dopant halide with other solvents, the chemical state of the dopant precursor can be stably maintained in a state suitable for doping, and the generation of byproducts from the dopant precursor can be suppressed. This allows the preparation of a film-forming doping raw material solution capable of forming high-quality laminates. Specifically, the method for preparing a film-forming doping raw material solution of the present invention makes it possible to prepare a film-forming doping raw material solution capable of stably forming high-quality thin films with excellent electrical properties.

[0019] In this case, a solvent having a pH of 3 or less may be used as the first solvent.

[0020] This allows the dopant precursor to be more stably maintained in a state suitable for doping.

[0021] At this time, a solvent containing hydrochloric acid, hydrobromic acid, hydroiodic acid, nitric acid, sulfuric acid, acetic acid, or formic acid can be used as the first solvent.

[0022] This can more effectively suppress the formation of by-products derived from the dopant.

[0023] At this time, a silane compound may be used as the organic dopant compound.

[0024] This makes it possible to prepare a doping raw material solution for film formation that can realize a laminate with better electrical characteristics.

[0025] At this time, a halide containing tin can be used as the halide.

[0026] This makes it possible to prepare a doping raw material solution for film formation that can realize a laminate with better electrical characteristics.

[0027] At this time, the method may further include mixing the dopant precursor solution with a second solvent to dilute the solution.

[0028] This makes it possible to better control the electrical characteristics of the laminate.

[0029] In addition, the present invention provides a method for preparing a doping raw material solution for film formation, characterized in that:

[0030] The method comprises the steps of preparing a dopant precursor solution separately from a film-forming raw material by mixing a solute containing a dopant compound with a first solvent instead of mixing the solute with the other solvents.

[0031] The preparation method uses an acidic solvent as the first solvent.

[0032] According to this method, by preparing a dopant precursor solution in an acidic solvent separately from the film-forming raw material, without mixing the solute containing the dopant compound with other solvents, the chemical state of the dopant precursor can be stably maintained in a state suitable for doping, and the generation of byproducts from the dopant precursor can be suppressed, thereby enabling the preparation of a film-forming dopant raw material solution capable of forming a high-quality laminate. Specifically, the method for preparing a film-forming dopant raw material solution of the present invention makes it possible to prepare a film-forming dopant raw material solution capable of stably forming a high-quality thin film with excellent electrical properties.

[0033] In this case, a solvent having a pH of 1 or less may be used as the first solvent.

[0034] This allows the dopant precursor to be more stably maintained in a state suitable for doping.

[0035] At this time, a solvent containing hydrochloric acid, hydrobromic acid, hydroiodic acid, nitric acid, sulfuric acid, acetic acid, or formic acid can be used as the first solvent.

[0036] This can more effectively suppress the formation of by-products derived from the dopant.

[0037] In this case, a compound containing any one of silicon, tin, and germanium can be used as the dopant compound.

[0038] This makes it possible to prepare a doping raw material solution for film formation that can realize a laminate with better electrical characteristics.

[0039] At this time, the method may further include mixing the dopant precursor solution with a second solvent to dilute the solution.

[0040] This makes it possible to better control the electrical characteristics of the laminate.

[0041] Furthermore, the present invention provides a method for manufacturing a laminate, characterized in that it comprises:

[0042] The step of preparing a doping raw material solution for film formation using the method for preparing a doping raw material solution for film formation of the present invention;

[0043] The step of preparing a film-forming raw material solution containing a film precursor;

[0044] a step of heating the substrate;

[0045] A step of atomizing the film-forming doping raw material solution and the film-forming raw material solution;

[0046] The step of supplying the atomized film-forming doping raw material solution and the atomized film-forming raw material solution to the heated substrate using a carrier gas to form a film.

[0047] Thus, by using a film-forming dopant raw material solution prepared in an acidic solvent separately from the film-forming raw material, and prepared by the method for preparing a film-forming dopant raw material solution of the present invention, a laminate having excellent electrical properties can be produced. Specifically, the method for producing a laminate of the present invention enables the stable formation of a laminate containing a high-quality thin film having excellent electrical properties.

[0048] Furthermore, the present invention provides a film-forming doping raw material solution, which is a film-forming doping raw material solution for Mist-CVD, characterized in that:

[0049] It contains Group IV elements and halogen elements, and

[0050] The pH is 0.3 or higher and 4 or lower.

[0051] This makes it possible to prepare a doping raw material solution that can uniformly form a high-quality thin film having excellent electrical characteristics even on a large-area substrate.

[0052] At this time, the pH of the raw material solution may be 1 or more and 3 or less.

[0053] This allows the formation of a high-quality thin film having more excellent electrical characteristics.

[0054] In addition, in this case, the Group IV element may be any one of silicon, tin, and germanium.

[0055] This makes it possible to prepare a doping raw material solution that can perform stable doping with higher reproducibility.

[0056] Furthermore, the present invention provides a semiconductor film characterized in that:

[0057] It contains Ga and group IV elements and has a corundum-type crystal structure.

[0058] The resistivity distribution of the semiconductor film is ±25% or less.

[0059] Thus, a high-quality and highly productive semiconductor film can be formed.

[0060] At this time, the area of ​​the semiconductor film can be 50 cm 2 above.

[0061] As a result, a semiconductor film with higher quality and higher productivity can be formed.

[0062] In addition, in this case, the semiconductor film may have a thickness of 1 μm or more.

[0063] As a result, the semiconductor film is of higher quality, a film more suitable for a semiconductor device can be formed, and the design freedom of the semiconductor device can be further improved.

[0064] Effects of the Invention

[0065] As described above, the method for preparing a film-forming dopant raw material solution of the present invention enables the preparation of a film-forming dopant raw material solution that can stably form high-quality thin films with excellent electrical properties. Consequently, the method for preparing a film-forming dopant raw material solution of the present invention enables the preparation of a high-quality dopant raw material solution that can stably produce laminates with excellent electrical properties.

[0066] For example, by using a dopant raw material solution prepared by the method for preparing a film-forming dopant raw material solution of the present invention, excellent conductivity can be imparted to a metal oxide semiconductor film, and as a result, a high-quality metal oxide semiconductor film can be produced.

[0067] Furthermore, according to the method for producing a laminated body of the present invention, a laminated body including a high-quality thin film having excellent electrical characteristics can be stably formed.

[0068] Furthermore, the doping raw material solution of the present invention can form a high-quality thin film having excellent electrical characteristics uniformly and with high reproducibility even on a large-area substrate.

[0069] Furthermore, the semiconductor film of the present invention is a high-quality and highly productive semiconductor film. Consequently, the semiconductor film of the present invention is a high-quality and inexpensive semiconductor film. BRIEF DESCRIPTION OF THE DRAWINGS

[0070] Figure 1 Schematic diagram showing one example of an apparatus used in the method for producing a laminated body of the present invention. DETAILED DESCRIPTION

[0071] As described above, it is sought to develop a film-forming doping raw material solution capable of stably forming a high-quality, large-area thin film having excellent electrical characteristics, a method for preparing the same, and a method for producing a laminate using the same.

[0072] The inventors of this application have conducted careful research on the above-mentioned technical problems and found that by using a solute containing a dopant compound as a dopant precursor, such as an organic dopant compound containing halogen, or a halide or oxide of a dopant, and first mixing the solute with an acidic first solvent instead of mixing it with other solvents, a dopant precursor solution is prepared separately from the film-forming raw materials, thereby making it possible to stably maintain the chemical state of the dopant precursor in a state suitable for doping and suppressing the generation of by-products from the dopant precursor, thereby completing the present invention.

[0073] That is, the present invention is a method for preparing a doping raw material solution for film formation, characterized in that:

[0074] The method comprises the steps of preparing a dopant precursor solution by mixing a solute with a first solvent instead of mixing the solute with other solvents, thereby preparing the dopant precursor solution separately from the film-forming raw material, wherein the solute comprises a halogen-containing organic dopant compound or a dopant halide.

[0075] The preparation method uses an acidic solvent as the first solvent.

[0076] Furthermore, the present invention is a method for preparing a doping raw material solution for film formation, characterized in that:

[0077] The method comprises the steps of preparing a dopant precursor solution separately from a film-forming raw material by mixing a solute containing a dopant compound with a first solvent instead of mixing the solute with the other solvents.

[0078] The preparation method uses an acidic solvent as the first solvent.

[0079] Furthermore, the present invention provides a method for producing a laminate, characterized in that it comprises:

[0080] The step of preparing a doping raw material solution for film formation using the method for preparing a doping raw material solution for film formation of the present invention;

[0081] The step of preparing a film-forming raw material solution containing a film precursor;

[0082] a step of heating the substrate;

[0083] A step of atomizing the film-forming doping raw material solution and the film-forming raw material solution;

[0084] The step of supplying the atomized film-forming doping raw material solution and the atomized film-forming raw material solution to the heated substrate using a carrier gas to form a film.

[0085] Furthermore, the present invention provides a doping raw material solution for film formation, which is a doping raw material solution for film formation used in Mist-CVD, characterized in that:

[0086] It contains Group IV elements and halogen elements, and

[0087] The pH is 0.3 or higher and 4 or lower.

[0088] Furthermore, the present invention is a semiconductor film characterized in that:

[0089] It contains Ga and group IV elements and has a corundum-type crystal structure.

[0090] The resistivity distribution of the semiconductor film is ±25% or less.

[0091] Hereinafter, the present invention will be described in detail, but the present invention is not limited thereto.

[0092] [Method for preparing doping raw material solution for film formation]

[0093] (First Method)

[0094] The method for preparing a film-forming dopant raw material solution according to a first aspect of the present invention is characterized in that it includes the step of preparing a dopant precursor solution separately from the film-forming raw material by first mixing a solute with a first solvent without mixing with other solvents, wherein the solute includes a halogen-containing organic dopant compound or a dopant halide.

[0095] Furthermore, the preparation method uses an acidic solvent as the first solvent.

[0096] First, an acidic first solvent (acid solution) is prepared as a solvent for a dopant precursor solution (hereinafter also referred to as a "dopant solution").

[0097] The first solvent used here preferably contains hydrochloric acid, hydrobromic acid, hydroiodic acid, nitric acid, sulfuric acid, acetic acid, or formic acid, and a solvent containing hydrochloric acid is particularly preferably used.

[0098] The first solvent is not particularly limited as long as it is acidic, and may contain water, methanol, ethanol, acetone, or the like. In particular, when the target laminate is carbon-averse, an aqueous solution may be used.

[0099] Furthermore, the hydrogen ion concentration index of the first solvent is preferably 3 or less, more preferably 2 or less, in terms of pH. Using a solvent having a pH of 3 or less can reliably prevent the dopant precursor from being modified by chemical reactions and thus failing to function as a dopant. Furthermore, the formation of defects in the formed film can be reliably prevented, thereby reliably preventing a decrease in the electrical properties of the film.

[0100] The lower limit of the pH of the first solvent is not particularly limited, and for example, a solvent having a pH of -1.1 or higher can be used as the first solvent.

[0101] Next, a solute is mixed into the first solvent to prepare a dopant precursor solution. Before the solute is mixed into the first solvent, the first solvent is not mixed with other non-acidic solvents.

[0102] As the solute, a solute containing a halogen-containing organic dopant compound or a dopant halide can be used. The halogen-containing organic dopant compound is not particularly limited, but may contain silicon, with dimethylchlorosilane and 3-cyanopropyldimethylchlorosilane being suitable. Furthermore, the dopant halide is not particularly limited, but may contain tin, with anhydrous tin chloride or tin chloride hydrate being suitable.

[0103] On the other hand, in the present invention, the dopant precursor solution is prepared separately from the film-forming raw material, so that the solute does not contain the precursor of the target film (film precursor).

[0104] The amount of the solute added to the first solvent can be appropriately adjusted according to the amount of doping in the target film, and can be, for example, 0.01 mol / L to 0.0000001 mol / L.

[0105] After the solute is added to the first solvent, the mixture may be stirred. For stirring, generally known stirring methods such as stirring with a stirrer, ultrasonic irradiation, and planetary stirring can be widely and appropriately used.

[0106] The atmosphere in which the above series of steps are performed is not limited, but it is more preferable to perform the steps in an inert gas such as nitrogen.

[0107] Thus, the dopant precursor solution obtained separately from the film-forming raw material can be used directly as a film-forming dopant raw material solution for film formation, or it can be further diluted and used. That is, the preparation of the film-forming dopant raw material solution can be completed with the preparation of the dopant precursor solution, or it can further include a step of mixing the dopant precursor solution with a second solvent to dilute it. The second solvent used for dilution is not particularly limited and can include water, methanol, ethanol, acetone, etc.

[0108] Furthermore, when a solute containing a halogen-containing organic dopant compound or a dopant halide is placed in a non-acidic solvent, such as pure water, even if the resulting aqueous solution is made acidic, the dopant precursor may be modified by chemical reactions, rendering it ineffective as a dopant, or defects may form in the resulting film, degrading the film's electrical properties. For details, refer to the comparative examples described below.

[0109] (Second Method)

[0110] The method for preparing a film-forming doping raw material solution according to the second aspect of the present invention is characterized in that:

[0111] The method comprises the steps of preparing a dopant precursor solution separately from a film-forming raw material by mixing a solute containing a dopant compound with a first solvent instead of mixing the solute with the other solvents.

[0112] The preparation method uses an acidic solvent as the first solvent.

[0113] First, an acidic first solvent (acid solution) is prepared as a solvent for the dopant precursor solution in the same manner as in the first embodiment.

[0114] The type of the first solvent used in the second embodiment may be the same as that used in the first embodiment.

[0115] In the second embodiment, the hydrogen ion concentration index of the first solvent is preferably 1 or less, more preferably 0.15 or less, in terms of pH. Using a solvent with a pH of 1 or less can more reliably prevent the dopant precursor from being modified by chemical reactions and thus failing to function as a dopant. It can also more reliably prevent the formation of defects in the formed film, thereby more reliably preventing a decrease in the electrical properties of the film.

[0116] The lower limit of the pH of the first solvent in the second embodiment is not particularly limited, but for example, a solvent having a pH of -1.1 or higher can be used as the first solvent.

[0117] Next, the solute is mixed in the first solvent to prepare a dopant precursor solution. Before the solute is mixed in the first solvent, it is not mixed with other non-acidic solvents.

[0118] The solute used in the second embodiment is not particularly limited as long as it contains a dopant compound, but solutes containing halogen-containing organic dopant compounds, dopant halides, or dopant oxides are particularly suitable. The halogen-containing organic dopant compound and dopant halide are not particularly limited, but for example, the halogen-containing organic dopant compounds and dopant halides listed in the first embodiment can be used. Furthermore, the dopant oxide is not particularly limited and may contain germanium, with germanium dioxide being particularly suitable.

[0119] On the other hand, similarly to the first aspect, in the second aspect of the present invention, the dopant precursor solution is prepared separately from the film-forming raw material. Therefore, the solute does not contain the precursor of the target film (film precursor).

[0120] In the second embodiment, the amount of the solute added to the first solvent can be appropriately adjusted according to the doping amount in the target film, and can be, for example, 0.1 mol / L to 0.0000001 mol / L.

[0121] As in the first embodiment, after the solute is added to the first solvent, the mixture may be stirred. In addition, as in the first embodiment, the atmosphere in which the above series of steps are performed is not limited, but it is more preferable to perform the steps in an inert gas such as nitrogen.

[0122] Thus, the dopant precursor solution obtained separately from the film-forming raw material can be directly used for film formation as a dopant raw material solution for film formation, or can be further diluted and used.

[0123] At this time, the pH of the doping source solution is preferably 0.3 to 4, more preferably 1 to 3. A pH of 0.3 or higher can prevent a decrease in the doping level in the growing film and a decrease in the carrier density relative to the target value. Furthermore, a pH of 4 or lower can prevent a widening of the resistivity distribution.

[0124] That is, the preparation of the film-forming dopant raw material solution may be completed with the preparation of the dopant precursor solution, and may further include a step of diluting the dopant precursor solution by mixing it with a second solvent.

[0125] In this manner, a doping raw material solution can be prepared that can uniformly form a high-quality thin film having excellent electrical characteristics even on a large-area substrate.

[0126] As in the first embodiment, the second solvent used for dilution is not particularly limited and may include water, methanol, ethanol, acetone, or the like.

[0127] Furthermore, even if the resulting aqueous solution is made acidic after a solute containing a dopant compound is placed in a non-acidic solvent, such as pure water, the dopant precursor may be modified by chemical reactions, rendering it ineffective as a dopant, or defects may form in the resulting film, degrading the film's electrical properties. For details, see the comparative examples below.

[0128] [Method for producing laminate]

[0129] The method for producing a laminated body of the present invention is characterized by comprising:

[0130] The step of preparing a doping raw material solution for film formation using the method for preparing a doping raw material solution for film formation of the present invention;

[0131] The step of preparing a film-forming raw material solution containing a film precursor;

[0132] a step of heating the substrate;

[0133] A step of atomizing the film-forming doping raw material solution and the film-forming raw material solution;

[0134] The step of supplying the atomized film-forming doping raw material solution and the atomized film-forming raw material solution to the heated substrate using a carrier gas to form a film.

[0135] Each step is described below.

[0136] [Step of Preparing a Doping Raw Material Solution for Film Formation]

[0137] This step is a step of preparing the film-forming dopant raw material solution used in the method for producing the laminate of the present invention using the method for preparing the film-forming dopant raw material solution of the present invention. For details, refer to the description of the method for preparing the film-forming dopant raw material solution of the present invention.

[0138] [Step of preparing membrane-forming raw material solution]

[0139] The film-forming raw material solution can be prepared by mixing a film precursor in a solvent.

[0140] The film precursor is not particularly limited, and any compound can be used as long as it is a precursor that can form a target film.

[0141] As the solvent, for example, water or an organic solvent can be used. In addition, the membrane-forming raw material solution may contain a small amount of acid or base.

[0142] The concentration of the film precursor in the film-forming raw material solution is not particularly limited and can be appropriately set depending on the purpose and method.

[0143] When forming a gallium oxide film, a gallium precursor solution is prepared as a film-forming raw material solution.

[0144] [Step of heating the substrate]

[0145] The substrate is not particularly limited as long as it can support the formed film. The substrate material may be a known material, i.e., an organic compound or an inorganic compound. Examples include, but are not limited to, polysulfone, polyethersulfone, polyphenylene sulfide, polyetheretherketone, polyimide, polyetherimide, fluororesins, metals such as iron, aluminum, stainless steel, and gold, silicon, sapphire, quartz, glass, calcium carbonate, gallium oxide, SiC, ZnO, and GaN.

[0146] When forming a film by epitaxial growth, a single crystal substrate having a desired crystal structure is used.

[0147] The shape of the substrate may be, for example, a plate such as a flat plate or a circular plate, a fiber, a rod, a cylinder, a prism, a tube, a spiral, a sphere, a ring, or any other shape. In particular, when the substrate is a plate, the area of ​​the surface on which the film is formed is at least 5 square centimeters, preferably 10 square centimeters, and particularly 50 square centimeters, from the perspective of productivity. 2 In the present invention, the thickness is not particularly limited, but is preferably 50 to 2000 μm, more preferably 200 to 800 μm.

[0148] The heating temperature and heating atmosphere of the substrate are not particularly limited and can be appropriately selected according to the components of the film-forming doping raw material solution and the film-forming raw material solution, and the composition of the target film.

[0149] [Steps for atomization]

[0150] In this step, the film-forming dopant raw material solution and the film-forming raw material solution are atomized (also referred to as "atomization"). In the present invention, the term "atomization" refers to liquid particles dispersed in a gas, and also includes substances referred to as mist or droplets, which are sometimes referred to as mist or droplets.

[0151] The atomizing device is not particularly limited as long as it can produce atomization or droplets, and a known method may be used. In the present invention, an atomizing device using ultrasonic waves is preferred.

[0152] The film-forming dopant raw material solution to be atomized can be mixed with a precursor solution (third solution) of a different composition depending on the intended purpose. For example, when forming an oxide containing gallium and aluminum, an aluminum precursor solution and a film-forming dopant raw material solution can be prepared separately, mixed, and then atomized.

[0153] The film-forming dopant raw material solution and the film-forming raw material solution may be atomized using different atomizers, or a separately prepared film-forming dopant raw material solution may be added to the film-forming raw material solution and then atomized using the same atomizer.

[0154] The initial velocity of the mist or droplets obtained using ultrasonic waves is zero and they float in the air, so they are preferred. For example, since they are not blown in the form of a spray, they can float in the air and be transported as a gas, so there is no damage caused by collision energy, so they are very suitable.

[0155] The droplet size is not particularly limited and can be several mm in size, but is preferably 50 μm.

[0156] Below, more preferably 0.1 to 10 μm.

[0157] [Steps for film formation]

[0158] In this step, the atomized film-forming doping raw material solution and the atomized film-forming raw material solution are supplied to the heated substrate by a carrier gas to form a film.

[0159] The carrier gas is not particularly limited, and in addition to air, oxygen, and ozone, for example, inert gases such as nitrogen and argon, or reducing gases such as hydrogen and forming gas can be used as appropriate. The carrier gas may be one type or two or more types.

[0160] The flow rate of the carrier gas may be appropriately set according to the size of the substrate or the size of the film formation chamber, and can be set to, for example, approximately 0.01 to 100 L / min.

[0161] The film formation may be performed under any of atmospheric pressure, increased pressure, and reduced pressure, but is preferably performed under atmospheric pressure in view of equipment cost and productivity.

[0162] Next, a method for producing a stacked body containing gallium oxide is used as an example. Figure 1 The method for producing the laminate of the present invention will be described, but the present invention is not limited thereto.

[0163] Figure 1 An example of an apparatus used in the method for producing a laminated body of the present invention is shown. In this example of the method for producing a laminated body of the present invention, a Mist-CVD apparatus 100 is used. The Mist-CVD apparatus 100 includes a carrier gas 101, an atomizer 102a, an atomizer 102b, a transfer line 103, a valve 104, a valve 105, a transfer line 106, a susceptor 108, a film-forming chamber 109, and a heater 110.

[0164] The structure of the film forming chamber 109 is not particularly limited; metals such as aluminum and 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 device 110 is provided inside or outside the film forming chamber 109 to heat the substrate 107. Furthermore, the substrate 107 is placed on a susceptor 108 provided within the film forming chamber 109.

[0165] A gallium precursor solution 112a, serving as a film-forming raw material solution, is contained within the atomizer 102a. In this embodiment, the gallium precursor solution 112a is preferably a solution prepared by dissolving a gallium halide or gallium organic complex, serving as a film precursor, in water or an organic solvent. Furthermore, the gallium precursor solution 112a may contain a small amount of an acid or base.

[0166] The gallium concentration in the gallium precursor solution 112a is not particularly limited and can be appropriately set according to the purpose or method, but is preferably 0.001 mol / L to 2 mol / L, and more preferably 0.01 mol / L to 0.7 mol / L.

[0167] Atomizer 102b contains a doping source material 112b containing a film-forming doping source solution obtained by the method for preparing a film-forming doping source solution of the present invention described above. Doping source material 112b may consist solely of the film-forming doping source solution described above, or, as described above, may be mixed with precursor solutions of different compositions depending on the intended purpose. For example, when forming a binary oxide composed of gallium and aluminum, a separately prepared aluminum precursor solution may be mixed with the film-forming doping source solution.

[0168] In addition, while the method described herein involves using the gallium precursor solution 112a and the doping source material 112b in separate atomizers, the present invention is not limited thereto. Alternatively, as exemplified above, a solution prepared by adding the doping source material 112b to the gallium precursor solution 112a may be used in the same atomizer. In this case, the doping solution 112b may be added to the separately prepared gallium precursor solution 112a so that the dopant concentration is 0.0001% to 20%, more preferably 0.001% to 10%, relative to the Ga concentration in the gallium precursor solution 112a.

[0169] As described above, the atomizing device for the gallium precursor solution 112a and the doping raw material 112b is not particularly limited as long as it can be atomized or dropletized, and can be a well-known device. In the present invention, an atomizing device using ultrasonic waves is preferred.

[0170] The carrier gas 101 is mixed with the atomized raw materials (precursor solutions) formed in the atomizers 102a and 102b, namely, the atomized gallium precursor solution (film-forming raw material solution) 112a formed in the atomizer 102a and the atomized doping raw material 112b (including the atomized doping raw material solution for film formation) formed in the atomizer 102b, respectively, to form a first mixed gas 113 and a second mixed gas 114, which are mixed to form a mixed gas 123, which is transported to the film-forming chamber 109.

[0171] For example, the carrier gas described above can be used as the carrier gas 101. In addition, the flow rate of the carrier gas 101 can be, for example, the flow rate described above.

[0172] At this time, the supply amount of each mixed gas 113 and 114 can be adjusted according to the target doping level. However, the supply amount of the dopant is 0.0001% to 20% relative to the supply amount of gallium, and more preferably 0.001% to 10%.

[0173] The mixed gas 123 supplied to the film forming chamber 109 reacts on the substrate 107 heated by the heating device 110 in the film forming chamber 109 to form a film.

[0174] exist Figure 1 In the illustrated example, the atomizer 102b is connected to the film forming chamber 109 via the delivery pipe 106, and the delivery pipe 103 from the atomizer 102a merges with the delivery pipe 106. However, the delivery pipe 103 and the delivery pipe 106 may be independently connected to the film forming chamber 109. Furthermore, the structure is not limited thereto, and the first mixed gas 113 and the second mixed gas 114 may be introduced into a separate buffer tank (not shown), and the mist mixed in the buffer tank may be delivered to the film forming chamber 109.

[0175] Although not shown, diluent gas can be added to adjust the mist amount per unit volume of the mixed gas 123. The flow rate of the diluent gas can be appropriately set, for example, 0.1 to 10 times the flow rate of the carrier gas per minute.

[0176] For example, the dilution gas may be supplied to the downstream side of the atomizers 102a and 102b. The dilution gas may be the same as the carrier gas or a different gas from the carrier gas.

[0177] There is no particular limitation on the transport pipes 103 and 106 as long as they have sufficient stability with respect to the solvent of the precursor or the temperature at the connection between the reactor and the transport pipe. Common resin pipes such as quartz or polyethylene, polypropylene, vinyl chloride, silicone resin, polyurethane resin, fluororesin, etc. can be widely used.

[0178] [Dopant raw material solution for film formation]

[0179] The film-forming doping raw material solution of the present invention is a film-forming doping raw material solution used in Mist-CVD, and is characterized in that:

[0180] It contains Group IV elements and halogen elements, and

[0181] The pH is 0.3 or higher and 4 or lower.

[0182] In this case, the pH of the doping source solution can be between 0.3 and 4, more preferably between 1 and 3. A pH of 0.3 or higher prevents a decrease in the doping level in the growing film and a decrease in carrier density relative to the target value. Furthermore, a pH of 4 or lower prevents a widening of the resistivity distribution. This allows for the production of a doping source solution that can uniformly form high-quality thin films with excellent electrical properties, even on large-area substrates.

[0183] If the Group IV element is any one of silicon, tin, and germanium, a doping raw material solution capable of further reproducibly and stably performing doping can be prepared.

[0184] The film-forming dopant raw material solution of the present invention can be prepared by the method for preparing a film-forming dopant raw material solution of the present invention.

[0185] [Semiconductor Film]

[0186] Furthermore, the semiconductor film of the present invention is characterized in that it contains Ga and a Group IV element and has a corundum-type crystal structure.

[0187] The resistivity distribution of the semiconductor film is ±25% or less.

[0188] Thus, a high-quality and highly productive semiconductor film can be formed.

[0189] The smaller the resistivity distribution of the semiconductor film, the better, and it can be ±0% or more.

[0190] The area of ​​the semiconductor film can be 50cm 2 above.

[0191] As a result, a semiconductor film with higher quality and higher productivity can be formed.

[0192] The larger the area of ​​the semiconductor film, the better. Therefore, the upper limit is not particularly limited, but can be, for example, 1000 cm 2 the following.

[0193] In addition, the semiconductor film may have a thickness of 1 μm or more.

[0194] As a result, a semiconductor film of better quality can be formed, and a film more suitable for a semiconductor device can be formed, which can further improve the design freedom of the semiconductor device.

[0195] The upper limit of the film thickness of the semiconductor film is not particularly limited, and can be, for example, 1000 μm or less.

[0196] The semiconductor film of the present invention can be obtained by using a doping raw material solution prepared by the method for preparing a film-forming doping raw material solution of the present invention and a film-forming raw material solution containing Ga.

[0197] Example

[0198] Hereinafter, the present invention will be specifically described using Examples and Comparative Examples, but the present invention is not limited to these Examples and Comparative Examples.

[0199] (Example 1)

[0200] In Example 1, the Figure 1 The Mist-CVD apparatus shown in FIG. 1 forms a film of α-gallium oxide.

[0201] Borosilicate glass raw material containers were used for the atomizers 102a and 102b, and a quartz film-forming chamber 109 was prepared. A gas cylinder filled with pure nitrogen was used to supply the carrier gas 101. Urethane resin tubing was used to connect the gas cylinder to the atomizers 102a and 102b, and quartz delivery pipes 103 and 106 were used to connect the atomizers 102a and 102b to the film-forming chamber 109.

[0202] Next, a raw material solution was prepared according to the following procedure.

[0203] First, in a nitrogen-purged atmosphere, dimethylchlorosilane, the solute of the dopant precursor solution, was added to a hydrochloric acid aqueous solution adjusted to a pH of 0.5, mixed, and stirred for 30 minutes to dissolve. Then, pure water was added to the solution in air for dilution, preparing a film-forming dopant raw material solution 112b with a silicon concentration of 0.02 mmol / L. This prepared film-forming dopant raw material solution 112b was filled into a raw material container 102b.

[0204] Next, in the atmosphere, gallium acetylacetonate, a film precursor, was added to a dilute hydrochloric acid aqueous solution prepared by mixing 1 volume % of 35% hydrochloric acid in pure water. The mixture was stirred with a stirrer for 30 minutes to prepare a gallium precursor solution 112a with a Ga concentration of 0.05 mol / L. The prepared gallium precursor solution 112a was filled in another raw material container 102a.

[0205] Next, a c-plane sapphire substrate 107 having a thickness of 0.6 mm and a diameter of 4 inches was placed on a quartz susceptor 108 provided in a film forming chamber 109 and heated so that the substrate temperature reached 500°C.

[0206] Next, ultrasonic vibrations are transmitted to the raw material solutions 112a and 112b in the raw material containers 102a and 102b through water using an ultrasonic vibrator (frequency of 2.4 MHz), thereby atomizing the raw material solutions 112a and 112b.

[0207] Next, nitrogen gas as carrier gas 101 was added to the two raw material containers 102a and 102b at a flow rate of 3 L / min. A mixed gas 113 of the atomized gallium precursor solution 112a and nitrogen 101, and a mixed gas 114 of the atomized film-forming dopant raw material solution 112b and nitrogen 101 were supplied to the film-forming chamber 109 for 60 minutes to form a film. The supply of nitrogen gas 101 and the mixed gas 123 to the film-forming chamber 109 were then stopped.

[0208] The above series of operations were repeated to prepare 10 samples.

[0209] X-ray diffraction analysis revealed that the crystal layers of the stacked bodies of all samples showed a peak at 2θ=40.3°, thus confirming that they were α-phase Ga2O3.

[0210] Then, Hall measurement was performed on all samples by the van der Pauw method to evaluate the carrier density and carrier mobility.

[0211] (Example 2)

[0212] Film formation was carried out in the same manner as in Example 1, except that the pH of the hydrochloric acid aqueous solution used to dissolve dimethylchlorosilane was set to 2.0, to prepare 10 samples.

[0213] X-ray diffraction analysis revealed that the crystal layers of the stacked bodies of all samples showed a peak at 2θ=40.3°, confirming that they were α-phase Ga2O3.

[0214] Then, in the same manner as in Example 1, film evaluation was performed on all the samples.

[0215] (Example 3)

[0216] Film formation was performed in the same manner as in Example 1, except that 3-cyanopropyldimethylsilyl chloride was used as the solute of the dopant precursor solution, to prepare 10 samples.

[0217] X-ray diffraction analysis revealed that the crystal layers of the stacked bodies of all samples showed a peak at 2θ=40.3°, confirming that they were α-phase Ga2O3.

[0218] Then, in the same manner as in Example 1, film evaluation was performed on all the samples.

[0219] (Example 4)

[0220] Ten samples were prepared by film formation in the same manner as in Example 1, except that a solution of tin (II) chloride dihydrate having a tin concentration of 0.02 mmol / L was used as the dopant precursor solution. In Example 4, an aqueous hydrochloric acid solution adjusted to a pH of 0.5 was used as the solvent for dissolving tin (II) chloride dihydrate.

[0221] X-ray diffraction analysis revealed that the crystal layers of the stacked bodies of all samples showed a peak at 2θ=40.3°, confirming that they were α-phase Ga2O3.

[0222] Then, in the same manner as in Example 1, film evaluation was performed on all the samples.

[0223] (Comparative Example 1)

[0224] Ten samples were prepared by film formation in the same manner as in Example 1, except that dimethylchlorosilane was added to pure water and then hydrochloric acid was added to adjust the pH to 0.5 to prepare a dopant precursor solution.

[0225] X-ray diffraction analysis revealed that the crystal layers of the stacked bodies of all samples showed a peak at 2θ=40.3°, confirming that they were α-phase Ga2O3.

[0226] Then, in the same manner as in Example 1, film evaluation was performed on all the samples.

[0227] (Comparative Example 2)

[0228] Ten samples were prepared by film formation in the same manner as in Example 3 except that 3-cyanopropyldimethylsilyl chloride was added to pure water and then hydrochloric acid was added to adjust the pH to 0.5 to prepare a dopant precursor solution.

[0229] X-ray diffraction analysis revealed that the crystal layers of the stacked bodies of all samples showed a peak at 2θ=40.3°, confirming that they were α-phase Ga2O3.

[0230] Then, in the same manner as in Example 1, film evaluation was performed on all the samples.

[0231] (Comparative Example 3)

[0232] Ten samples were prepared by film formation in the same manner as in Example 4 except that tin (II) chloride dihydrate was added to pure water and then hydrochloric acid was added to adjust the pH to 0.5 to prepare a dopant precursor solution.

[0233] X-ray diffraction analysis revealed that the crystal layers of the stacked bodies of all samples showed a peak at 2θ=40.3°, confirming that they were α-phase Ga2O3.

[0234] Then, in the same manner as in Example 1, film evaluation was performed on all the samples.

[0235] The average values ​​of the carrier density and carrier mobility of the films of ten samples obtained in Examples 1, 2, 3, and 4 and Comparative Examples 1, 2, and 3 are shown in Table 1 below.

[0236] [Table 1]

[0237] <![CDATA[Carrier density [cm -3 > <![CDATA[Mobility [cm 2 / (V·s)]]]> Example 1 <![CDATA[7.13×10 18 ]]> 17.8 Example 2 <![CDATA[6.76×10 18 ]]> 18.3 Example 3 <![CDATA[6.97×10 18 ]]> 18.0 Example 4 <![CDATA[7.02×10 18 ]]> 17.5 Comparative Example 1 <![CDATA[2.11×10 18 ]]> 2.5 Comparative Example 2 <![CDATA[3.45×10 18 ]]> 1.8 Comparative Example 3 <![CDATA[2.88×10 18 ]]> 2.0

[0238] The results of Examples 1, 2, 3, and 4 shown in Table 1 demonstrate that the film-forming doping raw material solutions prepared by the method for preparing a film-forming doping raw material solution of the present invention achieve stable doping and are superior in producing high-quality films with high carrier mobility. On the other hand, in Comparative Examples 1, 2, and 3, which used doping raw material solutions prepared by the conventional method for preparing a doping raw material solution, i.e., by first dissolving a dopant precursor in pure water, the resulting films had low carrier density and significantly decreased mobility.

[0239] (Example 5)

[0240] In Example 5, using Figure 1 The Mist-CVD apparatus shown forms a film of α-gallium oxide.

[0241] In the same manner as in Example 1, a Mist-CVD apparatus was prepared.

[0242] Next, a raw material solution was prepared according to the following procedure.

[0243] First, in a nitrogen-purged atmosphere, dimethylchlorosilane, the solute of the dopant precursor solution, was added to a hydrochloric acid aqueous solution adjusted to a pH of 0.1, mixed, and stirred for 30 minutes to dissolve. Then, pure water was added to the atmosphere for dilution, adjusting the pH to 2.0 to prepare a film-forming dopant raw material solution 112b with a silicon concentration of 0.02 mmol / L. This prepared film-forming dopant raw material solution 112b was filled into a raw material container 102b.

[0244] Next, a gallium precursor solution 112a having a Ga concentration of 0.05 mol / L was prepared using the same procedure as in Example 1. The prepared gallium precursor solution 112a was filled into another raw material container 102a.

[0245] Next, a c-plane sapphire substrate 107 having a thickness of 0.6 mm and a diameter of 4 inches was placed on a quartz susceptor 108 provided in a film forming chamber 109 and heated so that the substrate temperature reached 500°C.

[0246] Next, ultrasonic vibrations are transmitted to the raw material solutions 112a and 112b in the raw material containers 102a and 102b through water using an ultrasonic vibrator (frequency of 2.4 MHz), thereby atomizing the raw material solutions 112a and 112b.

[0247] Next, nitrogen gas as carrier gas 101 was added to the two raw material containers 102a and 102b at a flow rate of 3 L / min. A mixed gas 113 of atomized gallium precursor solution 112a and nitrogen 101, and a mixed gas 114 of atomized film-forming dopant raw material solution 112b and nitrogen 101 were supplied to the film-forming chamber 109 for 60 minutes to form films. The supply of nitrogen gas 101 and the mixed gas 123 to the film-forming chamber 109 were then stopped. Thus, a laminate was produced.

[0248] X-ray diffraction analysis revealed that the crystal layer in the prepared laminate had a peak at 2θ=40.3°, confirming that it was α-phase Ga 2 O 3 .

[0249] Then, the film evaluation of the sample was performed in the same manner as in Example 1.

[0250] (Example 6)

[0251] Film formation was performed in the same manner as in Example 5 except that the pH of the film-forming dopant raw material solution 112 b was set to 0.3.

[0252] X-ray diffraction measurement revealed that the crystal layer of the sample laminate had a peak at 2θ=40.3°, confirming that it was α-phase Ga2O3.

[0253] Then, the film evaluation of the sample was performed in the same manner as in Example 1.

[0254] (Example 7)

[0255] The film formation was performed in the same manner as in Example 5 except that the pH of the film-forming dopant raw material solution 112 b was set to 4.0.

[0256] X-ray diffraction measurement revealed that the crystal layer of the sample laminate had a peak at 2θ=40.3°, confirming that it was α-phase Ga2O3.

[0257] Then, the film evaluation of the sample was performed in the same manner as in Example 1.

[0258] (Comparative Example 4)

[0259] Film formation was carried out in the same manner as in Example 5 except that dimethylchlorosilane was added to pure water and hydrochloric acid was further added to adjust the pH to 0.1 to prepare a dopant precursor solution, which was then diluted with pure water to adjust the pH to 2.

[0260] X-ray diffraction measurement revealed that the crystal layer of the sample laminate had a peak at 2θ=40.3°, confirming that it was α-phase Ga2O3.

[0261] Then, the film evaluation of the sample was performed in the same manner as in Example 1.

[0262] (Example 8)

[0263] Film formation was carried out in the same manner as in Example 5 except that a solution having a silicon concentration of 0.02 mmol / L was prepared as a dopant precursor solution by dissolving 3-cyanopropyldimethylsilyl chloride in a hydrochloric acid aqueous solution adjusted to pH 0.1.

[0264] X-ray diffraction measurement revealed that the crystal layer of the sample laminate had a peak at 2θ=40.3°, confirming that it was α-phase Ga2O3.

[0265] Then, the film evaluation of the sample was performed in the same manner as in Example 1.

[0266] (Example 9)

[0267] Film formation was carried out in the same manner as in Example 5 except that a solution having a tin concentration of 0.02 mmol / L was prepared as a dopant precursor solution by dissolving tin (II) chloride dihydrate in a hydrochloric acid aqueous solution adjusted to pH 0.1.

[0268] X-ray diffraction measurement revealed that the crystal layer of the sample laminate had a peak at 2θ=40.3°, confirming that it was α-phase Ga2O3.

[0269] Then, the film evaluation of the sample was performed in the same manner as in Example 1.

[0270] (Example 10)

[0271] Film formation was carried out in the same manner as in Example 5 except that a solution having a germanium concentration of 0.02 mmol / L was prepared as a dopant precursor solution by dissolving germanium oxide in a hydrochloric acid aqueous solution adjusted to pH 0.1.

[0272] X-ray diffraction measurement revealed that the crystal layer of the sample laminate had a peak at 2θ=40.3°, confirming that it was α-phase Ga2O3.

[0273] Then, the film evaluation of the sample was performed in the same manner as in Example 1.

[0274] The resistivity distribution, carrier density, and carrier mobility of the films obtained in Examples 5, 6, 7, 8, 9, and 10 and Comparative Example 4 are shown in Table 2 below.

[0275] [Table 2]

[0276] Resistivity distribution [±%] <![CDATA[Carrier density [cm -3 > <![CDATA[Mobility [cm 2 / (V·s)]]]> Example 5 10.6 <![CDATA[7.13×10 18 ]]> 10.3 Example 6 15.6 <![CDATA[5.76×10 18 ]]> 9.8 Example 7 23.3 <![CDATA[6.97×10 18 ]]> 9.5 Comparative Example 4 1189.0 <![CDATA[1.10×10 18 ]]> 0.5 Example 8 9.8 <![CDATA[7.63×10 18 ]]> 9.7 Example 9 10.5 <![CDATA[6.99×10 i8 ]]> 10.0 Example 10 10.1 <![CDATA[7.02×10 18 ]]> 9.4

[0277] The results of Examples 5, 6, 7, 8, 9, and 10 shown in Table 2 demonstrate that the film-forming doping raw material solutions prepared using the method for preparing a film-forming doping raw material solution of the present invention achieve stable doping and produce high-quality films with a good resistivity distribution and high carrier mobility, thus being superior. On the other hand, Comparative Example 4, which used a doping raw material solution prepared using a conventional method for preparing a doping raw material solution, i.e., a method in which a dopant precursor was dissolved in pure water, yielded a film with a large resistivity distribution and low carrier density, and furthermore, a significantly reduced mobility.

[0278] 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 exhibiting the same effects as the technical concept described in the claims of the present invention is within the technical scope of the present invention.

Claims

1. A method for producing a laminate, characterized in that: It includes: a step of preparing a dopant raw material solution for film formation, comprising the step of preparing a dopant precursor solution separately from the film-forming raw material by first mixing a solute with a first solvent instead of mixing with other solvents, wherein the solute comprises a halogen-containing organic dopant compound or a dopant halide, wherein a solvent having a pH of 1 or less is used as the first solvent, and a solvent containing hydrochloric acid, hydrobromic acid, hydroiodic acid, nitric acid, sulfuric acid, acetic acid, or formic acid is used as the first solvent; The step of preparing a film-forming raw material solution containing a film precursor; a step of heating the substrate; A step of atomizing the film-forming doping raw material solution and the film-forming raw material solution; The step of supplying the atomized film-forming doping raw material solution and the atomized film-forming raw material solution to the heated substrate using a carrier gas to form a film.

2. The method for manufacturing a laminate according to claim 1, wherein: A silane compound is used as the organic dopant compound.

3. The method for manufacturing a laminate according to claim 1, wherein: As the halide, a halide containing tin is used.

4. The method for producing a laminate according to any one of claims 1 to 3, wherein: The method further comprises the step of diluting the dopant precursor solution by mixing the dopant precursor solution with a second solvent.

5. A method for manufacturing a laminate, characterized in that: It includes: a step of preparing a dopant raw material solution for film formation, comprising the step of first mixing a solute containing a dopant compound with a first solvent without mixing it with other solvents, thereby preparing a dopant precursor solution separately from the film-forming raw material, wherein a solvent having a pH of 1 or less is used as the first solvent, and a solvent containing hydrochloric acid, hydrobromic acid, hydroiodic acid, nitric acid, sulfuric acid, acetic acid, or formic acid is used as the first solvent; The step of preparing a film-forming raw material solution containing a film precursor; a step of heating the substrate; A step of atomizing the film-forming doping raw material solution and the film-forming raw material solution; The step of supplying the atomized film-forming doping raw material solution and the atomized film-forming raw material solution to the heated substrate using a carrier gas to form a film.

6. The method for manufacturing a laminate according to claim 5, wherein: As the dopant compound, a compound containing any one of silicon, tin, and germanium is used.

7. The method for producing a laminate according to claim 5 or 6, wherein: The preparation method further comprises the step of diluting the dopant precursor solution by mixing it with a second solvent.

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