JP2017128492A - Crystalline oxide film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a crystalline oxide film containing a crystalline indium-containing oxide as a main component and a corundum structure.SOLUTION: Mists or liquid droplets 4b obtained from a raw material solution 4a are transported by carrier gases 2a, 2b to a substrate 10 installed in a film deposition chamber and subjected to thermal reaction at 500°C or less in the film deposition chamber, using a cold-wall type mist CVD device 1 to deposit on the substrate 10 a crystalline oxide film containing a crystalline indium-containing oxide as a main component and a corundum structure. The a crystalline oxide film has a half band width of a locking curve of an X-ray diffraction method of 100 arcsec or less, preferably 50 arcsec or less. Preferably, a carrier density is 3.1×10cmor less and a migration rate is 143 cm/Vs or more.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a crystalline oxide film and its use.

The indium oxide film exhibits a metallic electrical resistivity of about 1 × 10 ⁻⁴ Ωcm when doped with tin, and at the same time, transparency is maintained. Therefore, the indium oxide film is suitable as a transparent conductive film. Widely used as a pixel electrode, a solar cell carrier collection electrode, and the like. When used in such applications, a high surface resistance value will cause a decrease in output, so it is generally desirable that the surface resistance value be relatively low. Therefore, an indium oxide film with high crystallinity is required. (Patent Document 1).

In addition, in the field of oxide electronics, indium oxide is a promising semiconductor based on a large band gap of 3.6 to 3.75 eV. In the case where indium oxide is used as a semiconductor, it is necessary to devise a technique for increasing the mobility as much as possible. One method for increasing the mobility is to increase the crystallinity of indium oxide.
Furthermore, in the case of configuring a device, an insulating film is often required in addition to a high mobility semiconductor film. If high mobility indium oxide and insulating indium oxide are obtained in such a case, an electronic device such as an FET transistor can be realized by stacking them together. When indium oxide is used as the insulating film, the electrical resistivity must be increased as much as possible, as opposed to the case of the transparent electrode material. For this purpose, it is necessary to devise a method that removes impurity ions as much as possible and does not create oxygen defects as much as possible. (Patent Document 2).

As an effort to increase the crystallinity of the indium oxide film, as in the invention described in Patent Document 3, the study of the creation of an indium oxide film using a mist CVD method is underway. Further, in Non-Patent Document 1, for example, an In ₂ O ₃ thin film having a corundum structure is grown on a sapphire substrate by using a mist CVD method, and a thin film having high orientation with a rocking curve half-value width of 182 arcsec in an X-ray diffraction method. Have succeeded in getting. However, even if these techniques are used, it is difficult to produce a film having a lower half-value width, and usually only a thin film of about 300 to 1000 arcsec has been obtained. Further, such a film has problems such as generation of pits on the surface, and the surface smoothness is not satisfactory.

JP 2013-193440 A Japanese Patent No. 4480809 JP 2014-234337 A

Norihiro Suzuki, Kentaro Kaneko, Shizuo Fujita, “Growth of corundum-structured In2O3 thin films on sapphire substrates with Fe2O3 buffer layers”, Journal of Crystal Growth 364, 2013

  An object of the present invention is to provide a crystalline oxide film containing a highly crystalline oxide containing indium as a main component and further including a corundum structure.

As a result of intensive studies to achieve the above object, the inventors of the present invention include a highly crystalline indium-containing oxide as a main component when a film is formed using a mist CVD method under specific conditions. It has been found that a crystalline oxide film containing a metastable phase corundum structure can be formed. The present inventors have also found that such a crystalline oxide film can solve the above conventional problems all at once.
In addition, after obtaining the above knowledge, the present inventors have further studied and completed the present invention.

That is, the present invention relates to the following inventions.
[1] A crystalline oxide film containing an oxide containing indium as a main component, including a corundum structure, and having a rocking curve half-value width of 100 arcsec or less in an X-ray diffraction method Oxide film.
[2] The crystalline oxide film according to [1], wherein the oxide is single crystal or polycrystalline.
[3] The crystalline oxide film according to [1] or [2], wherein the oxide is indium oxide.
[4] The crystalline oxide film according to any one of [1] to [3], wherein the oxide has a corundum structure.
[5] The crystalline oxide film according to any one of [1] to [4], including a dopant.
[6] The crystalline oxide film according to any one of [1] to [5], wherein the half width is 50 arcsec or less.
[7] The crystalline oxide film according to any one of [1] to [6], which is a transparent conductive film.
[8] A device including at least one or two or more films selected from an insulating film, a semiconductor film, and a conductive film, and an electrode, wherein the film is any one of [1] to [7]. A device characterized by being a crystalline oxide film.
[9] The device according to [8], wherein the film is the crystalline oxide film according to claim 7.
[10] The device according to [9], which is a solar cell, a display, illumination, electronic paper, a transistor, a printable circuit, or a transparent sheet heating element.
[11] A crystalline oxide film containing an oxide containing indium as a main component, including a corundum structure, having a carrier density of 3.1 × 10 ¹⁸ cm ⁻³ or less, and a mobility of 143 cm / Vs A crystalline oxide film characterized by the above.
[12] A semiconductor device including at least a semiconductor layer and an electrode, wherein the crystalline oxide film according to [11] is used as the semiconductor layer.
[13] A semiconductor device including at least a semiconductor layer and an electrode, wherein the semiconductor layer is formed of a crystalline oxide film having a corundum structure containing an oxide containing indium as a main component, and a field effect A semiconductor device having a mobility of 187 cm ² / Vs or more and an effective mobility of 240 cm ² / Vs or more.
[14] The semiconductor device according to [13], wherein the semiconductor layer is stacked on an α- (Al _x , Ga _x-1 ) ₂ O ₃ film (0 <x <1).
[15] The semiconductor device according to any one of [12] to [14], which is a transistor.

  According to the present invention, it is possible to provide a crystalline oxide film that includes an oxide containing indium that has high crystallinity as a main component and further includes a corundum structure.

It is a schematic block diagram of the film-forming apparatus (mist CVD) used in an Example. It is a schematic block diagram of the film-forming apparatus (mist CVD) used in a comparative example. It is a figure which shows the observation result of AFM in an Example. Is a diagram illustrating a carrier density and the hall mobility of the relationship α-In ₂ O ₃ in Test Example. The typical sectional view of MOSFET in a manufacture example is shown.

  The crystalline oxide film of the present invention is a crystalline oxide film containing indium-containing oxide as a main component, includes a corundum structure, and has a rocking curve half-value width of 100 arcsec or less in the X-ray diffraction method. It is characterized by that.

  The crystalline oxide film of the present invention may be an insulating film, a semiconductor film, or a conductive film, but may be a conductive film or a transparent conductive film.

  The crystal having a corundum structure contained in the crystalline oxide film may be a single crystal, a polycrystal, or a mixture thereof. In the present invention, the crystal having the corundum structure is preferably made of an oxide containing indium. The “main component” refers to a composition ratio (atomic ratio) in the crystalline oxide film that includes 50% or more of the oxide, preferably 70% or more, and more preferably. Contains 90% or more.

  The oxide is not particularly limited as long as it contains indium. Examples of the oxide containing indium include indium oxide, tin-doped indium oxide (ITO), gallium-doped indium oxide, and indium-doped zinc oxide. The oxide is preferably indium oxide or tin-doped indium oxide, and more preferably indium oxide. In the present invention, the oxide preferably has a corundum structure, more preferably indium oxide having a corundum structure or tin-doped indium oxide, and indium oxide having a corundum structure. Most preferably.

  The thickness of the crystalline oxide film is not particularly limited, but in the present invention, the thickness is preferably 1 μm or more, more preferably 1.5 μm or more, and 1.8 μm or more. Is most preferred. The shape or the like of the crystalline oxide film is not particularly limited, and may be a quadrangular shape, a circular shape, or a polygonal shape. The surface area of the crystalline oxide film is not particularly limited, and in the present invention, it is preferably 3 mm square or more, more preferably 5 mm square or more, and most preferably 50 mm square or more.

  The crystalline oxide film may contain a dopant. The dopant is not particularly limited and may be a known one. Examples of the dopant include n-type dopants such as tin, germanium, silicon, titanium, zirconium, vanadium or niobium, or p-type dopants. In the present invention, the dopant is preferably tin. The content of the dopant is preferably 0.00001 atomic% or more in the composition of the crystalline oxide film, more preferably 0.00001 atomic% to 20 atomic%, and 0.00001 atomic% to Most preferred is 10 atomic percent.

  The above-mentioned “half-value width” means a value obtained by measuring the half-value width of a rocking curve by XRD (X-ray diffraction: X-ray diffraction method). Although it does not specifically limit as a surface orientation, For example, [0006] etc. are mentioned. In the present invention, the full width at half maximum is usually 100 arcsec or less, preferably 50 arcsec or less, and more preferably 40 arcsec or less.

  Hereinafter, although the preferable manufacturing method of the said crystalline oxide film is demonstrated, this invention is not limited to these preferable manufacturing methods.

  As a preferred method for producing the crystalline oxide film, for example, a cold wall type mist CVD apparatus such as that shown in FIG. The mist or liquid droplets are transported to a substrate installed in the film formation chamber by a carrier gas (inert gas) (transport process), and then the mist or liquid droplets are thermally reacted at 500 ° C. or less in the film formation chamber. And a method of forming a crystalline oxide film on the substrate (film formation process).

(Atomization / droplet forming process)
In the atomization / droplet forming step, the raw material solution is atomized or dropletized. The atomizing means or droplet forming means of the raw material solution is not particularly limited as long as the raw material solution can be atomized or formed into droplets, and may be a known means. The atomizing means or droplet forming means used is preferred. Mist or droplets obtained using ultrasonic waves have a zero initial velocity and are preferable because they float in the air.For example, instead of spraying like a spray, they can be suspended in a space and transported as a gas. Since it is a possible mist, there is no damage due to collision energy, which is very suitable. The droplet size is not particularly limited, and may be a droplet of about several mm, but is preferably 50 μm or less, more preferably 0.1 to 10 μm.

(Raw material solution)
The raw material solution can be atomized or formed into droplets, and is not particularly limited as long as it contains indium. In the present invention, as the raw material solution, a solution in which the metal is dissolved or dispersed in an organic solvent or water in the form of a complex or a salt can be suitably used. Examples of complex forms include acetylacetonate complexes, carbonyl complexes, ammine complexes, hydride complexes, and the like. Examples of the salt form include organic metal salts (for example, metal acetates, metal oxalates, metal citrates, etc.), sulfide metal salts, nitrate metal salts, phosphorylated metal salts, metal halide salts (for example, metal chlorides). Salt, metal bromide salt, metal iodide salt, etc.). In the present invention, the raw material solution is preferably a metal halide salt of indium. By using such a preferable raw material solution, the surface smoothness of the film can be improved, and the crystallinity of the film can be further improved.

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

  The solvent of the raw material solution is not particularly limited, and may be an inorganic solvent such as water, an organic solvent such as alcohol, or a mixed solvent of an inorganic solvent and an organic solvent. In the present invention, the solvent preferably contains water, more preferably water or a mixed solvent of water and alcohol, and most preferably water. More specifically, examples of the water include pure water, ultrapure water, tap water, well water, mineral spring water, mineral water, hot spring water, spring water, fresh water, seawater, and the like. Ultrapure water is preferred.

(Conveying process)
In the transfer step, the mist or the droplets are transferred into the film forming chamber with a carrier gas. As the carrier gas, an inert gas such as nitrogen or argon is used. Further, the type of carrier gas may be one, but it may be two or more, and a diluent gas with a reduced flow rate (for example, 10-fold diluted gas) is further used as the second carrier gas. Also good. Further, the supply location of the carrier gas is not limited to one location but may be two or more locations. The flow rate of the carrier gas is not particularly limited, but is preferably 0.01 to 20 L / min, and more preferably 1 to 10 L / min. In the case of a dilution gas, the flow rate of the dilution gas is preferably 0.001 to 2 L / min, and more preferably 0.1 to 1 L / min.

(Film formation process)
In the film forming step, a crystalline oxide film is formed on the substrate by thermally reacting the mist or droplets in the film forming chamber. The thermal reaction may be performed as long as the mist or droplet reacts with heat, and the reaction conditions are not particularly limited as long as the object of the present invention is not impaired. In this step, the thermal reaction is usually performed at a temperature of 500 ° C. or lower, preferably 400 ° C. or lower, more preferably 350 ° C. or lower, and most preferably 150 ° C. to 350 ° C. In addition, the thermal reaction may be performed in any atmosphere of a vacuum, a non-oxygen atmosphere, a reducing gas atmosphere, and an oxygen atmosphere as long as the object of the present invention is not impaired. In an atmosphere of an inert gas such as nitrogen or argon, or a reducing gas such as hydrogen gas or forming gas), and more preferably in an inert gas atmosphere. Moreover, although it may be performed under any conditions of atmospheric pressure, increased pressure, and reduced pressure, it is preferably performed under atmospheric pressure in the present invention. The film thickness can be set by adjusting the film formation time.

(Substrate)
The substrate is not particularly limited as long as it can support the crystalline oxide film. The material of the substrate is not particularly limited as long as the object of the present invention is not impaired, and may be a known substrate, an organic compound, or an inorganic compound. The shape of the substrate may be any shape and is effective for all shapes, for example, a plate shape such as a flat plate or a disk, a fiber shape, a rod shape, a columnar shape, a prismatic shape, A cylindrical shape, a spiral shape, a spherical shape, a ring shape, a porous body shape, and the like can be mentioned. In the present invention, a substrate is preferable. The thickness of the substrate is not particularly limited in the present invention.

  The substrate is not particularly limited as long as it is plate-shaped and serves as a support for the crystalline oxide film. An insulator substrate, a semiconductor substrate, a metal substrate or a conductive substrate may be used, but the substrate is preferably an insulator substrate, and a metal is formed on the surface. A substrate having a film is also preferable. The shape of the substrate is not particularly limited, and may be a substantially circular shape (for example, a circle or an ellipse), or a polygonal shape (for example, a triangle, a square, a rectangle, a pentagon, a hexagon, a heptagon). , Octagons, 9-gons, etc.), and various shapes can be suitably used. In the present invention, the shape of the film formed on the substrate can be set by setting the shape of the substrate to a preferable shape. In the present invention, a large-area substrate can also be used. By using such a large-area substrate, the area of the crystalline oxide film can be increased. Examples of the substrate include a base substrate containing a substrate material having a corundum structure as a main component, a base substrate containing a substrate material having a β-gallia structure as a main component, and a substrate material having a hexagonal crystal structure as a main component. Examples thereof include a base substrate. Here, the “main component” means that the substrate material having the specific crystal structure is preferably 50% or more, more preferably 70% or more, and still more preferably 90% by atomic ratio with respect to all components of the substrate material. % Or more, and may be 100%.

The substrate material is not particularly limited as long as the object of the present invention is not impaired, and may be a known material. As the substrate material having the corundum structure, for example, α-Al ₂ O ₃ (sapphire substrate) or α-Ga ₂ O ₃ is preferably exemplified, and an a-plane sapphire substrate, an m-plane sapphire substrate, and an r-plane sapphire substrate. A c-plane sapphire substrate, an α-type gallium oxide substrate (a-plane, m-plane or r-plane) and the like are more preferable examples. As a base substrate mainly composed of a substrate material having a β-gallia structure, for example, a β-Ga ₂ O ₃ substrate, or a Ga ₂ O ₃ and Al ₂ O ₃ containing Al ₂ O ₃ content of more than 0 wt% Examples thereof include a mixed crystal substrate of 60 wt% or less. In addition, examples of the base substrate whose main component is a substrate material having a hexagonal crystal structure include a SiC substrate, a ZnO substrate, and a GaN substrate.

  In the present invention, the substrate preferably has a corundum structure, more preferably a base substrate composed mainly of a substrate material having a corundum structure, and most preferably a sapphire substrate or an α-type gallium oxide substrate. preferable. The substrate preferably contains aluminum, more preferably a base substrate mainly composed of an aluminum-containing substrate material having a corundum structure, and a sapphire substrate (preferably a c-plane sapphire substrate, an a-plane sapphire substrate, Most preferred are m-plane sapphire substrates and r-plane sapphire substrates.

In the present invention, the film may be formed as it is on the substrate, but it is preferable to form a film on the substrate via the buffer layer after laminating the buffer layer on the substrate. Examples of the buffer layer include a semiconductor layer including a corundum structure, an insulator layer, or a conductor layer. Among these, a semiconductor layer including a corundum structure is preferable. Examples of the semiconductor layer including the corundum structure include α-Fe ₂ O ₃ , α-Ga ₂ O ₃ , α-Al ₂ O _{3, and the} like. The means for laminating the buffer layer is not particularly limited, and may be the same as the means for laminating the crystalline oxide film.

  The crystalline oxide film obtained as described above has a rocking curve half-value width of 100 arcsec or less in the X-ray diffraction method and is excellent in crystallinity. Such a crystalline oxide film can be suitably used for a device or the like. Examples of the device include a solar cell, a display, illumination, an electronic paper, a transistor, a printable circuit, or a transparent sheet heating element. In the present invention, the device is preferably a device having at least one or more films selected from an insulating film, a semiconductor film and a conductive film and an electrode.

In the present invention, a crystalline oxide film containing, as a main component, an oxide containing indium by forming a film by a mist CVD method using a buffer layer or a dopant, which includes a corundum structure, a carrier A crystalline oxide film having a density of 3.1 × 10 ¹⁸ cm ⁻³ or less and a mobility of 143 cm / Vs or more can be easily obtained. Since such a crystalline oxide film has excellent semiconductor characteristics, it can be suitably used as the semiconductor layer in a semiconductor device including at least a semiconductor layer and an electrode. The application method and the like are not particularly limited, and known means may be used.

  Examples of the semiconductor device include a diode and a transistor, and more specifically, for example, a Schottky barrier diode (SBD), a metal semiconductor field effect transistor (MESFET), a high electron mobility transistor (HEMT), and a metal. Examples thereof include an oxide semiconductor field effect transistor (MOSFET), a static induction transistor (SIT), a junction field effect transistor (JFET), an insulated gate bipolar transistor (IGBT), and a light emitting diode. In the present invention, the semiconductor device is preferably SBD, MESFET, HEMT, MOSFET, or SIT, and more preferably a MOSFET.

The semiconductor device obtained as described above is excellent in characteristics of the semiconductor device. Specifically, for example, an α- (Al _x , Ga _x-1 ) ₂ O ₃ film (0 <x <1) is used as a buffer layer. ) Is used, a semiconductor device having a field effect mobility of 187 cm ² / Vs or more and an effective mobility of 240 cm ² / Vs or more can be obtained.

  Examples of the present invention will be described below, but the present invention is not limited thereto.

Example 1
1. Film Forming Apparatus A mist CVD apparatus 1 used in this example will be described with reference to FIG. The mist CVD apparatus 1 includes a carrier gas source 2a for supplying a carrier gas, a flow rate adjusting valve 3a for adjusting the flow rate of the carrier gas delivered from the carrier gas source 2a, and a carrier gas for supplying a carrier gas (dilution). (Dilution) source 2b, flow rate adjusting valve 3b for adjusting the flow rate of carrier gas (dilution) sent from carrier gas (dilution) source 2b, mist generation source 4 in which precursor solution 4a is accommodated, and water 5a , An ultrasonic vibrator 6 attached to the bottom surface of the container 5, a film forming chamber 7, a supply pipe 9 connecting the mist generation source 4 to the film forming chamber 7, and the film forming chamber 7. And an exhaust port 11 for discharging mist, droplets and exhaust gas after thermal reaction. A substrate 10 is installed on the hot plate 8.
2. Preparation of Precursor Solution Indium bromide was mixed with ultrapure water, and the aqueous solution was adjusted to 0.025 mol of indium bromide.

3. Preparation of film formation The precursor solution 4a obtained in the above was accommodated in the mist generation source 4. Next, as the substrate 10, a sapphire substrate (diameter 2 inches) having an α-Fe ₂ O ₃ film laminated on the surface as a buffer layer is placed on the hot plate 8, and the hot plate 8 is operated to form a film forming chamber. The temperature in 7 was raised to 350 ° C. Next, the flow rate control valves 3a and 3b are opened, the carrier gas is supplied from the carrier gas supply means 2a and 2b, which are carrier gas sources, into the film forming chamber 7, and the atmosphere in the film forming chamber 7 is sufficiently filled with the carrier gas. After the replacement, the carrier gas flow rate was adjusted to 5.0 L / min, and the carrier gas (dilution) flow rate was adjusted to 0.5 L / min. Nitrogen was used as the carrier gas.

4). Film Formation Next, the ultrasonic vibrator 6 was vibrated at 2.4 MHz, and the vibration was propagated to the precursor solution 4a through the water 5a, whereby the precursor solution 4a was atomized to generate the mist 4b. . The mist 4b is introduced into the film forming chamber 7 by the carrier gas through the supply pipe 9, and the mist thermally reacts in the film forming chamber 7 at 350 ° C. under atmospheric pressure. An indium oxide film was formed thereon. The film thickness was 1.8 μm and the film formation time was 120 minutes.

4. above. The indium oxide film obtained in 1 was a clear crystal without white turbidity. When the film was identified using an X-ray diffraction apparatus, the obtained film was an α-In ₂ O ₃ film. Further, the rocking curve half width measured by the X-ray diffraction method was 36 arcsec, and the film was highly crystalline. Furthermore, when the surface of the film was observed with an atomic force microscope (AFM), as shown in FIG. 3, a film having no pits on the surface and excellent surface smoothness was obtained.

(Comparative Example 1)
The mist CVD apparatus 19 used in Comparative Example 1 will be described with reference to FIG. The mist CVD apparatus 19 includes a susceptor 21 on which the substrate 20 is placed, a carrier gas supply means 22a for supplying a carrier gas, and a flow rate adjusting valve 23a for adjusting the flow rate of the carrier gas sent from the carrier gas supply means 22a. The carrier gas (dilution) supply means 22b for supplying the carrier gas (dilution), the flow rate adjusting valve 23b for adjusting the flow rate of the carrier gas sent from the carrier gas (dilution) supply means 22b, and the raw material solution 24a are accommodated. Mist generating source 24, a container 25 in which water 25a is placed, an ultrasonic vibrator 26 attached to the bottom surface of the container 25, a supply pipe 27 made of a quartz tube having an inner diameter of 40 mm, and a peripheral portion of the supply pipe 27 And a heater 28 installed in the vehicle. The susceptor 21 is made of quartz, and the surface on which the substrate 20 is placed is inclined from the horizontal plane. Both the supply pipe 27 and the susceptor 21 serving as a film formation chamber are made of quartz, so that impurities derived from the apparatus are prevented from being mixed into the film formed on the substrate 20.

Film formation was performed in the same manner as in Example 1 except that the mist CVD apparatus 19 shown in FIG. 4 was used as the film formation apparatus and the film formation time was 40 minutes. When the obtained film was identified using an X-ray diffraction apparatus, it was α-In ₂ O ₃ . Moreover, it was 187 arcsec when the half value width was measured using the X-ray-diffraction apparatus. The film thickness was 250 nm.

  As described above, it can be seen that the crystalline oxide film of the present invention is excellent in crystallinity.

(Test example)
According to the above example, an Fe ₂ O ₃ buffer layer and a Ga ₂ O ₃ buffer layer were used together with ozone to obtain an α-In ₂ O ₃ film. Further, in accordance with the above example, magnesium acetylacetonate and zinc acetylacetonate were mixed as raw materials to obtain an α-In ₂ O ₃ film subjected to Mg doping and Zn doping. About the obtained α-In ₂ O ₃ film, the crystal structure was confirmed with an X-ray diffractometer, and then annealed to measure the Hall effect to evaluate the carrier density and mobility. The results are shown in FIG.
As is apparent from FIG. 4, a carrier density of 3.1 × 10 ¹⁸ cm ⁻³ and a mobility of 143 cm / Vs is well doped, and the relationship between the carrier density and the mobility is also clear. Thus, it was found that when the carrier density is 3.1 × 10 ¹⁸ cm ⁻³ or less by doping, the mobility can be increased to 143 cm / Vs or more.

(Production example)
A MOSFET shown in FIG. 5 was produced. First, in accordance with the above example, magnesium acetylacetonate is mixed as a raw material, and α- (Al _0.1 Ga _0.9 ) ₂ O ₃ buffer layer 36 is used together with ozone to form α- An In ₂ O ₃ film 35 was obtained as a semiconductor layer. The film thickness was set to 60 nm in order to turn off the MOSFET. A source electrode 32 and a drain electrode 33 were provided on the produced α-In ₂ O ₃ film. Specifically, after washing the α-In ₂ O ₃ film with acetone, a resist is formed, the surface is protected with a photomask, then exposure is performed, followed by development to form a pattern, thereby forming gold (Au ) A film (70 nm thick) was formed. After the production of the source / drain electrodes was completed, an amorphous a-Al ₂ O ₃ thin film 34 as an insulating layer was formed using a mist CVD method. After the formation of the insulating layer, the gate electrode 31 (Au film, 100 nm thickness) was produced in the same manner as the source / drain electrodes. The insulating layer on the produced source / drain electrodes was removed by etching to produce a MOSFET.

With respect to the fabricated MOSFET, the S value indicating the performance as the switch characteristic was 1.83 V / dec. An ON / OFF ratio of 10 ⁵ was obtained. This shows that the gate characteristics are good. Further, the field effect mobility μ _FE and the effective mobility μ _eff were calculated using the evaluation of the gate characteristics, the IV measurement results, and the constants in Table 1. As a result, the field effect mobility was 187 cm ² / Vs, and the effective mobility was 240 cm ² / Vs. From this result, it can be seen that a MOSFET having a field effect mobility of 187 cm ² / Vs or more and an effective mobility of 240 cm ² / Vs or more was obtained.

  The crystalline oxide film of the present invention can be used for various devices, but is particularly useful for solar cells, displays, lighting, electronic paper, transistors, printable circuits, transparent sheet heating elements, and the like.

DESCRIPTION OF SYMBOLS 1 Mist CVD apparatus 2a Carrier gas source 2b Carrier gas (dilution) source 3a Flow control valve 3b Flow control valve 4 Mist generation source 4a Raw material solution 4b Mist 5 Container 5a Water 6 Ultrasonic vibrator 7 Deposition chamber 8 Hot plate 9 Supply Tube 10 Substrate 11 Exhaust port 19 Mist CVD apparatus 20 Substrate 21 Susceptor 22a Carrier gas supply means 22b Carrier gas (dilution) supply means 23a Flow control valve 23b Flow control valve 24 Mist generation source 24a Raw material solution 25 Container 25a Water 26 Ultrasonic vibration Child 27 Supply pipe 28 Heater 29 Exhaust port 31 Gate electrode 32 Source electrode 33 Drain electrode 34 Gate insulating film 35 Semiconductor layer 36 Buffer layer 37 Substrate

Claims (15)

  A crystalline oxide film containing an oxide containing indium as a main component, comprising a corundum structure, and having a rocking curve half-width of 100 arcsec or less in an X-ray diffraction method .   The crystalline oxide film according to claim 1, wherein the oxide is single crystal or polycrystalline.   The crystalline oxide film according to claim 1, wherein the oxide is indium oxide.   The crystalline oxide film according to claim 1, wherein the oxide has a corundum structure.   The crystalline oxide film according to claim 1, comprising a dopant.   The crystalline oxide film according to claim 1, wherein the half width is 50 arcsec or less.   The crystalline oxide film according to claim 1, which is a transparent conductive film.   A crystalline oxide film according to any one of claims 1 to 7, wherein the device comprises at least one film selected from an insulating film, a semiconductor film, and a conductive film, and an electrode. A device characterized by being.   The device according to claim 8, wherein the film is a crystalline oxide film according to claim 7.   The device according to claim 9, which is a solar cell, a display, illumination, electronic paper, a transistor, a printable circuit, or a transparent planar heating element. A crystalline oxide film containing an oxide containing indium as a main component, including a corundum structure, having a carrier density of 3.1 × 10 ¹⁸ cm ⁻³ or less, and a mobility of 143 cm / Vs or more A crystalline oxide film characterized by the above.   A semiconductor device comprising at least a semiconductor layer and an electrode, wherein the crystalline oxide film according to claim 11 is used as the semiconductor layer. A semiconductor device comprising at least a semiconductor layer and an electrode, wherein the semiconductor layer is composed of a crystalline oxide film having a corundum structure containing an oxide containing indium as a main component, and has a field effect mobility. 187 cm ² / Vs or higher and effective mobility is 240 cm ² / Vs or higher. The semiconductor device according to claim 13, wherein the semiconductor layer is stacked on an α- (Al _x , Ga _x-1 ) ₂ O ₃ film (0 <x <1). The semiconductor device according to claim 12, which is a transistor.