JPWO2015198857A1 - Metal oxide film manufacturing method, metal oxide film, thin film transistor, and electronic device - Google Patents

Abstract

A metal oxide precursor film forming step of forming a metal oxide precursor film by applying a solution containing at least indium as a solvent and a metal component on a substrate, and metal oxidation in a state where the metal oxide precursor film is heated UV light with a condition satisfying at least one of an illuminance with a wavelength of more than 200 nm and not more than 300 nm being 80 mW / cm 2 or more and an illuminance with a wavelength of not less than 150 nm and not more than 200 nm being 6.5 mW / cm 2 or more. A metal oxide film having a conversion step of converting a metal oxide precursor film into a metal oxide film by irradiating the film, and its application.

Description

  The present invention relates to a method for manufacturing a metal oxide film, a metal oxide film, a thin film transistor, and an electronic device.

  A metal oxide film as an oxide semiconductor film or an oxide conductor film has been put into practical use in production by a vacuum film forming method, and is currently attracting attention.

  On the other hand, research and development have been actively conducted on the production of oxide semiconductor films by a liquid phase process for the purpose of easily forming oxide semiconductor films having high semiconductor characteristics at low temperature and atmospheric pressure. ing.

  Recently, for example, a solution in which a solute such as nitrate or acetate is heated and stirred in a solvent at 75 ° C. for 12 hours to form metal methoxy ethoxide is applied onto a substrate, and ultraviolet rays are used to apply the solute to 150 ° C. A method of manufacturing a thin film transistor (TFT: Thin Film Transistor) having high transport characteristics at the following low temperature has been reported (see Nature, Vol. 489 (2012) p128).

  On the other hand, a method of forming a metal oxide semiconductor precursor film using an inexpensive solution of nitrate, acetate, or the like has been disclosed (for example, see International Publication No. 2009/081862).

  Further, a method is disclosed in which an oxide semiconductor precursor film formed on a substrate is irradiated with ultraviolet light and then subjected to plasma treatment to convert the precursor film into a metal oxide film (Japanese Patent Laid-Open No. 2013-2013). 1975539).

  Nature, Vol. 489 (2012) In the method disclosed in p128, since metal methoxyethoxide is produced, there are problems such as a labor and cost increase in solution synthesis, and in order to form an alkoxide, hydrolysis is performed in the atmosphere. It is easy to wake up and there is a problem with stability.

In addition, International Publication No. 2009/081862 discloses an ultraviolet ozone method as one method for forming a metal oxide semiconductor precursor film using a solution of nitrate, acetate or the like and then converting it to a metal oxide semiconductor film. UV ozone method), and the illuminance of UV light is described as 1 mW / cm ^{2 to} 10 W / cm ² . However, in International Publication No. 2009/081862, the specific effects of the wavelength and illuminance of ultraviolet rays applied to the precursor film on the electrical characteristics of the metal oxide film and the relationship between the processing time and the illuminance of UV light are specifically examined. Has not been made.

  In JP 2013-197539 A, since the precursor film is converted by performing a plasma treatment after the ultraviolet irradiation, the entire conversion process takes time and effort.

  The present invention provides a method for producing a metal oxide film capable of easily producing a metal oxide film having electron transfer characteristics, and a metal oxide film, a thin film transistor, and an electronic device having excellent electric characteristics. Objective.

In order to achieve the above object, the following invention is provided.
<1> a metal oxide precursor film forming step of forming a metal oxide precursor film by applying a solution containing at least indium as a solvent and a metal component on a substrate;
In a state where the metal oxide precursor film is heated, the illuminance having a wavelength of more than 200 nm and not more than 300 nm is 80 mW / cm ² or more, and the illuminance having a wavelength of 150 to 200 nm is 6. A conversion step of converting the metal oxide precursor film into a metal oxide film by irradiating ultraviolet rays under conditions satisfying at least one of 5 mW / cm ² or more;
The manufacturing method of the metal oxide film which has this.
<2> The method for producing a metal oxide film according to <1>, wherein the irradiation with ultraviolet rays is performed under the condition that an illuminance of at least a wavelength of 200 nm to 300 nm or less is 80 mW / cm ² or more.
<3> The ultraviolet irradiation, or less illuminance wavelength 200nm ultra 300nm is 80 mW / cm ² or more, and, 200nm or less illuminance than wavelength 150nm is performed under conditions at 6.5 mW / cm ² or more <1> or The manufacturing method of the metal oxide film as described in <2>.
<4> The method for producing a metal oxide film according to any one of <1> to <3>, wherein an illuminance of an ultraviolet wavelength of 200 nm to 300 nm is 90 mW / cm ² or more.
<5> The method for producing a metal oxide film according to any one of <1> to <4>, wherein the illuminance at an ultraviolet wavelength of 150 nm to 200 nm is 7 mW / cm ² or more.
<6> The method for producing a metal oxide film according to any one of <1> to <5>, wherein the irradiation time of ultraviolet rays is 25 minutes or less.
<7> The method for producing a metal oxide film according to any one of <1> to <6>, wherein the irradiation time of ultraviolet rays is 15 minutes or less.
<8> The method for producing a metal oxide film according to any one of <1> to <7>, wherein an oxygen concentration in an atmosphere irradiated with ultraviolet rays is 80000 ppm or less.
<9> The method for producing a metal oxide film according to any one of <1> to <8>, wherein an oxygen concentration in an atmosphere irradiated with ultraviolet rays is 30000 ppm or less.
<10> The method for producing a metal oxide film according to any one of <1> to <9>, wherein the temperature of the substrate during irradiation with ultraviolet rays is kept below 200 ° C.
<11> The method for producing a metal oxide film according to any one of <1> to <10>, wherein the substrate temperature during irradiation with ultraviolet rays is maintained at over 120 ° C.
<12> The method for producing a metal oxide film according to any one of <1> to <11>, wherein indium contained in the solution is indium ions.
<13> The method for producing a metal oxide film according to any one of <1> to <12>, wherein the solution contains nitrate ions.
<14> The method for producing a metal oxide film according to any one of <1> to <13>, wherein a rate at which the substrate is heated or lowered during irradiation with ultraviolet rays is within ± 0.5 ° C./min. .
<15> The method for producing a metal oxide film according to any one of <1> to <14>, wherein 50 atom% or more of the metal component contained in the solution is indium.
<16> The method for producing a metal oxide film according to any one of <1> to <15>, wherein the solution is a solution in which at least indium nitrate is dissolved in a solvent.
<17> The method for producing a metal oxide film according to any one of <1> to <16>, wherein the solution further contains at least one metal component selected from the group consisting of zinc, tin, gallium, and aluminum. .
<18> The method for producing a metal oxide film according to any one of <1> to <17>, wherein the solvent contains at least one selected from methanol, methoxyethanol, and water.
<19> The method for producing a metal oxide film according to any one of <1> to <18>, wherein the concentration of the metal component in the solution is 0.01 mol / L or more and 1.0 mol / L or less.
<20> The method for producing a metal oxide film according to any one of <1> to <19>, wherein the light source used for ultraviolet irradiation is a low-pressure mercury lamp.
<21> In the metal oxide precursor film forming step, the solution is applied onto the substrate, and the substrate is heated to 35 ° C. or higher and 100 ° C. or lower to be dried to form the metal oxide precursor film <1> to The manufacturing method of the metal oxide film as described in any one of <20>.
<22> In the metal oxide precursor film forming step, the solution is applied onto the substrate by at least one application method selected from an inkjet method, a dispenser method, a relief printing method, and an intaglio printing method <1> to The method for producing a metal oxide film according to any one of <21>.
<23> A metal oxide film produced using the method for producing a metal oxide film according to any one of <1> to <22>.
<24> The metal oxide film according to <23>, wherein 50 atom% or more of the metal component contained in the metal oxide film is indium.
<25> The metal oxide film according to <23> or <24>, which is a semiconductor film.
<26> A thin film transistor having an active layer including the metal oxide film according to <25>, a source electrode, a drain electrode, a gate insulating film, and a gate electrode.
<27> An electronic device comprising the thin film transistor according to <26>.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the metal oxide film which can manufacture the metal oxide film which has an electron transfer characteristic easily, and the metal oxide film, thin film transistor, and electronic device excellent in the electrical property are provided. The

It is the schematic which shows the structure of an example (top gate-top contact type) of the thin-film transistor manufactured by this invention. It is the schematic which shows the structure of an example (top gate-bottom contact type) of the thin-film transistor manufactured by this invention. It is the schematic which shows the structure of an example (bottom gate-top contact type) of the thin-film transistor manufactured by this invention. It is the schematic which shows the structure of an example (bottom gate-bottom contact type) of the thin-film transistor manufactured by this invention. It is a schematic sectional drawing which shows a part of liquid crystal display device of embodiment. It is a schematic block diagram of the electrical wiring of the liquid crystal display device shown in FIG. It is a schematic sectional drawing which shows a part of organic EL display apparatus of embodiment. It is a schematic block diagram of the electrical wiring of the organic electroluminescence display shown in FIG. It is a schematic sectional drawing which shows a part of X-ray sensor array of embodiment. It is a schematic block diagram of the electrical wiring of the X-ray sensor array shown in FIG. It is a diagram showing, _V g -I _d characteristics of the simplified TFT fabricated in Examples 1 and 2. It is a figure which shows the relationship between the illumination intensity and wavelength of wavelength 200nm or more and 300nm or less in the conversion process in Example 1, 2 and Comparative Example 1,2. It is a figure which shows the relationship between the illumination intensity and the mobility of wavelength 150nm or more and 200nm or less in the conversion process in Examples 1, 2 and Comparative Examples 1, 2. It is a figure which shows the relationship between the illumination intensity and wavelength of wavelength 200nm to 300nm or less in the conversion process in Example 3, 4 and Comparative Example 3, 4. It is a figure which shows the relationship between the illumination intensity and the mobility of wavelength 150nm or more and 200nm or less in the conversion process in Examples 3 and 4 and Comparative Examples 3 and 4. It is a figure which shows the ultraviolet light absorption spectrum of the solution which dissolved the indium nitrate used in the Example and the comparative example in 2-methoxyethanol.

Hereinafter, a method for producing a metal oxide film according to the present invention and a metal oxide film, a thin film transistor, and an electronic device produced according to the present invention will be specifically described with reference to the accompanying drawings.
In the drawings, members (components) having the same or corresponding functions are denoted by the same reference numerals and description thereof is omitted as appropriate. Further, in the present specification, when a numerical range is indicated by the symbol “to”, numerical values respectively described as a lower limit value and an upper limit value indicating the range are included in the numerical range.
Further, the present invention can be applied to manufacture of a metal oxide film as a conductive film or a semiconductor film. As a representative example, a method for manufacturing a semiconductor film will be mainly described.

  The inventor applied a solution containing at least indium as a solvent and a metal component on a substrate to form a metal oxide precursor film, and then heated the metal oxide precursor film to a specific wavelength and illuminance. It was found that by irradiating with ultraviolet rays under conditions satisfying the above conditions, it can be easily converted into a metal oxide film having excellent electron transfer characteristics in a short time.

<Method for producing metal oxide film>
A method for producing a metal oxide film according to the present disclosure includes: a metal oxide precursor film forming step of forming a metal oxide precursor film by applying a solution containing at least indium as a solvent and a metal component on a substrate; In a state where the oxide precursor film is heated, the illuminance having a wavelength of more than 200 nm and not more than 300 nm is 80 mW / cm ² or more and the illuminance having a wavelength of 150 to 200 nm is 6.5 mW with respect to the metal oxide precursor film. Conversion step of converting the metal oxide precursor film into a metal oxide film by irradiating with ultraviolet rays under conditions satisfying at least one of / cm ² or more.

  Although the reason why a metal oxide film excellent in electron transfer characteristics can be obtained by the method of the present disclosure is not certain, a solution containing indium for forming the metal oxide precursor film has a wavelength of 150 nm or more and 200 nm or less, and Exhibits high decomposability for ultraviolet light with a wavelength of more than 200 nm and less than 300 nm. By irradiating with ultraviolet light at a specific illuminance or higher, the precursor film is converted into a metal oxide film even in a short time, and indium oxide is easily generated This is probably because of this. Therefore, it is considered that the film density is increased in the metal oxide film containing indium even when ultraviolet irradiation is performed for a short time, the indium-oxygen-indium bond formation is promoted, the carrier concentration is increased, and as a result, the electron transfer characteristics are improved. .

  Hereinafter, each step will be specifically described.

[Metal oxide precursor film forming step]
First, a solution containing at least indium as a solvent and a metal component (hereinafter sometimes referred to as “metal oxide precursor solution” or simply “solution”) is prepared and applied onto a substrate to form a metal oxide precursor film. Form.

(substrate)
There is no restriction | limiting in particular about the shape of a board | substrate, a structure, a magnitude | size, It can select suitably according to the objective. The structure of the substrate may be a single layer structure or a laminated structure.

The material constituting the substrate is not particularly limited, and a substrate made of glass, an inorganic material such as YSZ (Yttria-Stabilized Zirconia), a resin, a resin composite material, or the like can be used. Of these, a resin substrate or a substrate made of a resin composite material (resin composite material substrate) is preferable in terms of light weight and flexibility. Specifically, polybutylene terephthalate, polyethylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polystyrene, polycarbonate, polysulfone, polyethersulfone, polyarylate, allyl diglycol carbonate, polyamide, polyimide, polyamideimide, polyetherimide, Fluorine resin such as polybenzazole, polyphenylene sulfide, polycycloolefin, norbornene resin, polychlorotrifluoroethylene, liquid crystal polymer, acrylic resin, epoxy resin, silicone resin, ionomer resin, cyanate resin, crosslinked fumaric acid diester, cyclic polyolefin, Synthetic resin substrates such as aromatic ether, maleimide / olefin, cellulose, episulfide compounds, etc. .
Inorganic materials contained in the composite material of inorganic material and resin include inorganic particles such as silicon oxide particles, metal nanoparticles, inorganic oxide nanoparticles, and inorganic nitride nanoparticles, carbon fibers such as carbon fibers and carbon nanotubes. Examples thereof include glass materials such as materials, glass flakes, glass fibers, and glass beads.
Also, composite plastic material of resin and clay mineral, composite plastic material of resin and particles having mica-derived crystal structure, laminated plastic material having at least one bonding interface between resin and thin glass, inorganic layer and organic Examples include a composite material having barrier performance having at least one or more bonding interfaces by alternately laminating layers.
In addition, a stainless steel substrate or a metal multilayer substrate in which different metals are laminated with stainless steel, an aluminum substrate, or an aluminum substrate with an oxide film whose surface insulation is improved by subjecting the surface to oxidation treatment (for example, anodization treatment), an oxide film An attached silicon substrate or the like can also be used.
The resin substrate or the resin composite material substrate is preferably excellent in heat resistance, dimensional stability, solvent resistance, electrical insulation, workability, low air permeability, low moisture absorption, and the like. The resin substrate or the resin composite material substrate may include a gas barrier layer for preventing permeation of moisture, oxygen, etc., an undercoat layer for improving the flatness of the resin substrate and the adhesion to the lower electrode, and the like. .

  Although there is no restriction | limiting in particular in the thickness of the board | substrate used by this indication, It is preferable that they are 50 micrometers or more and 500 micrometers or less. When the thickness of the substrate is 50 μm or more, the flatness of the substrate itself is further improved. Further, when the thickness of the substrate is 500 μm or less, the flexibility of the substrate itself is further improved, and the use as a substrate for a flexible device becomes easier.

(solution)
The solution used in the present disclosure contains a solvent and indium as a metal component, and may contain other metal components other than indium as necessary.
Indium contained in the solution is an inexpensive material and is preferably contained as indium ions from the viewpoint of obtaining a metal oxide film with high film thickness uniformity. The indium ion in the present disclosure may be an indium complex ion coordinated with a ligand such as a solvent molecule. Moreover, it is preferable that metal components other than the indium contained in the solution are also contained as ions.

  The solution used in the present disclosure is obtained by weighing a metal atom-containing compound (solute) such as a metal salt as a raw material so as to have a desired concentration in the solution, and stirring and dissolving in a solvent. The stirring time is not particularly limited as long as the solute is sufficiently dissolved.

  The indium content in the solution is preferably 50 atom% or more of the metal component contained in the solution. By using a solution containing indium in the above concentration range, a metal oxide film in which 50 atom% or more of the metal component in the film is indium can be obtained, and a metal oxide film having high electron transfer characteristics can be easily manufactured. it can.

  A metal atom-containing compound is used as a raw material for indium contained in the solution used in the present disclosure and, if necessary, other metal components. Examples of the metal atom-containing compound include metal salts, metal halides, and organometallic compounds. Metal salts include sulfates, phosphates, carbonates, acetates, oxalates, metal halides include chlorides, iodides, bromides, etc. Organic metal compounds include metal alkoxides, organic acid salts, metal β- Examples include diketonates.

  The solution used in the present disclosure preferably contains nitrate ions in addition to indium, and more preferably a solution in which at least indium nitrate is dissolved in a solvent. A metal oxide precursor film obtained by applying a solution in which indium nitrate is dissolved in a solvent can efficiently absorb ultraviolet light, and an oxide film containing indium can be easily formed. Indium nitrate may be a hydrate.

  The solution preferably contains at least one metal component selected from the group consisting of zinc, tin, gallium and aluminum as a metal component other than indium. When the solution used in the present disclosure contains an appropriate amount of any one of the above metal components other than indium, the electrical stability of the resulting metal oxide film can be improved.

In the metal oxide semiconductor film manufactured according to the present disclosure, the threshold voltage can be controlled to a desired value.
As a metal oxide film (conductor film or semiconductor film) containing indium and another metal element, In—Ga—Zn—O, In—Zn—O, In—Ga—O, In—Sn—O, and In—Sn are used. -Zn-O etc. are mentioned.

  In addition, it is preferable that the solution in this indication uses the solution which does not contain insoluble matters, such as a metal oxide semiconductor particle, in a solution. By using a solution that does not contain insoluble materials such as metal oxide semiconductor particles in the solution, the surface roughness when the metal oxide film is formed is reduced, and a metal oxide film having excellent in-plane uniformity is formed. Can do.

  The solvent used in the solution in the present disclosure is not particularly limited as long as the metal atom-containing compound used as a solute is soluble, water, alcohol solvents (methanol, ethanol, propanol, ethylene glycol, etc.), amide solvents (N, N-dimethylformamide etc.), ketone solvent (acetone, N-methylpyrrolidone, sulfolane, N, N-dimethylimidazolidinone etc.), ether solvent (tetrahydrofuran, methoxyethanol etc.), nitrile solvent (acetonitrile etc.), Other examples include hetero atom-containing solvents other than those described above. A solvent may be used individually by 1 type and may be used in mixture of 2 or more types. In particular, the solvent preferably contains at least one selected from methanol, methoxyethanol, and water from the viewpoint of improving solubility and wettability, and reducing cost and environmental burden.

  The concentration of the metal component in the solution can be arbitrarily selected according to the viscosity and the desired film thickness. From the viewpoint of improving the flatness and productivity of the thin film, the concentration of the metal component in the solution is preferably 0.01 mol / L or more and 1.0 mol / L or less, and 0.01 mol / L or more and 0.5 mol / L or less. The following is more preferable.

(Application)
As a method of applying the solution on the substrate, spray coating method, spin coating method, blade coating method, dip coating method, casting method, roll coating method, bar coating method, die coating method, mist method, inkjet method, dispenser method, Examples thereof include screen printing, letterpress printing, and intaglio printing. In particular, from the viewpoint of easily forming a fine pattern, it is preferable to use at least one coating method selected from an inkjet method, a dispenser method, a relief printing method, and an intaglio printing method.

(Dry)
After the solution is applied on the substrate, it may be naturally dried to obtain a metal oxide precursor film. However, the metal oxide precursor film is obtained by drying by a heat treatment in which the substrate temperature is 35 ° C. or more and 100 ° C. or less. Is preferred. By drying, the fluidity of the coating film can be reduced and the flatness of the finally obtained metal oxide film can be improved. Further, by selecting an appropriate drying temperature (35 ° C. or more and 100 ° C. or less), a final denser metal oxide film can be obtained. The method for the heat treatment is not particularly limited, and can be selected from hot plate heating, electric furnace heating, infrared heating, microwave heating, and the like.

Drying is preferably started within 5 minutes after applying the solution on the substrate from the viewpoint of keeping the flatness of the film uniform.
The drying time is not particularly limited, but is preferably 15 seconds or longer and 10 minutes or shorter from the viewpoint of film uniformity and productivity.
The atmosphere in which drying is performed is not particularly limited, but it is preferably performed in the air at atmospheric pressure from the viewpoint of manufacturing cost and the like.

[Conversion process]
Next, in a state where the metal oxide precursor film is heated, the illuminance having a wavelength of more than 200 nm and not more than 300 nm is 80 mW / cm ² or more, and the illuminance having a wavelength of 150 to 200 nm is applied to the metal oxide precursor film. The metal oxide precursor film is converted into a metal oxide film by irradiating ultraviolet rays under conditions that satisfy at least one of 6.5 mW / cm ² or more. By performing ultraviolet irradiation under the above conditions in a state where the metal oxide precursor film is heat-treated, it can be converted into a metal oxide film having high electron transfer characteristics by ultraviolet irradiation for 25 minutes or less, for example.

(Heat treatment)
It is preferable that the substrate temperature in the conversion step is kept above 120 ° C. If the substrate temperature in the conversion step is kept above 120 ° C., a metal oxide film having high electron transfer characteristics can be obtained in a shorter time.
On the other hand, the substrate temperature in the conversion step is preferably kept below 200 ° C. If the substrate temperature in the conversion step is kept below 200 ° C., an increase in thermal energy can be suppressed to reduce the manufacturing cost, and application to a resin substrate with low heat resistance is facilitated.
The heating means for the substrate in the conversion step is not particularly limited, and may be selected from hot plate heating, electric furnace heating, infrared heating, microwave heating, and the like.

It is preferable that the substrate is heated before the ultraviolet irradiation, and the ultraviolet irradiation is performed after the substrate temperature becomes constant. By performing ultraviolet irradiation after the substrate temperature becomes constant, a metal oxide film capable of manufacturing a highly reproducible element can be manufactured.
There is no particular limitation on the heat treatment time before the ultraviolet irradiation, but it is preferably a short time from the viewpoint of productivity, and specifically within 5 minutes.

Also, from the viewpoint of achieving high electron transfer characteristics, it is preferable that the rate of temperature rise or fall of the substrate during ultraviolet irradiation is within ± 0.5 ° C / min, and the substrate temperature during ultraviolet irradiation is constant. Is more preferable. The substrate temperature during ultraviolet irradiation can be controlled by adjusting the output of a heating means such as a hot plate for heating the substrate.
In addition, the substrate temperature can measure the surface temperature of a board | substrate with the Si substrate with a thermocouple.

(UV irradiation)
The ultraviolet rays applied to the metal oxide precursor film heated in the conversion step have an illuminance of more than 200 nm and not more than 300 nm of 80 mW / cm ² or more, and an illuminance of not less than 150 nm and not more than 200 nm is 6.5 mW. Irradiation is performed under conditions satisfying at least one of / cm ² or more.

The ultraviolet rays irradiated to the metal oxide precursor film have a high electron transfer characteristic metal oxide film even when the treatment is performed for a short time because the illuminance at a wavelength of more than 200 nm and not more than 300 nm is 80 mW / cm ² or more. If it is 90 mW / cm ² or more, a metal oxide film having higher electron transfer characteristics can be obtained. In addition, it is preferable that the upper limit of the illuminance having a wavelength of more than 200 nm and not more than 300 nm is 500 mW / cm ² or less from the viewpoint of suppressing device color and discoloration when using a resin substrate.

In addition, the ultraviolet rays applied to the metal oxide precursor film have a high electron transfer property even when the illuminance having a wavelength of 150 nm or more and 200 nm or less is 6.5 mW / cm ² or more even in a short time treatment. A film can be obtained, and if it is 7 mW / cm ² or more, a metal oxide film having higher electron transfer characteristics can be obtained. The upper limit of the illuminance at a wavelength of 150 nm or more and 200 nm or less is preferably 200 mW / cm ² or less from the viewpoint of suppressing device cost and discoloration when a resin substrate is used.
Note that the illuminance in each wavelength region of ultraviolet light can be adjusted by selecting a light source to be used, a light collecting mechanism, a neutral density filter, or the like.

In the conversion step, the heated metal oxide precursor film may be irradiated with ultraviolet rays under the condition that the illuminance with a wavelength of 150 nm or more and 200 nm or less is 6.5 mW / cm ² or more. From the viewpoint of converting the precursor precursor film into a metal oxide film having higher electron transfer characteristics in a short time, it is preferable to irradiate ultraviolet rays under the condition that the illuminance of at least 200 nm and 300 nm or less is 80 mW / cm ² or more. 200nm ultra 300nm following illumination is at 80 mW / cm ² or more and, more preferably 200nm or less of the intensity or wavelength 150nm is irradiated with ultraviolet rays at 6.5 mW / cm ² or more.

The ultraviolet irradiation in the conversion process may be performed until the metal oxide precursor film is converted into the metal oxide film, and is selected according to the illuminance of the ultraviolet light irradiated on the metal oxide precursor film and the target electron transfer characteristics. do it. In the present disclosure, the processing time in the conversion step (the time for irradiating the metal oxide precursor film with ultraviolet rays while the substrate is heated) can be suppressed to, for example, 25 minutes or less. By suppressing the processing time in the conversion process to 25 minutes or less, for example, it becomes easy to produce an electronic device in a roll-to-roll (hereinafter sometimes abbreviated as “RTR”) method, which greatly increases the manufacturing cost. It is possible to lower it.
In addition, from the viewpoint of productivity, the treatment time of the conversion process is more preferably 15 minutes or less. If the processing time in the conversion step is 15 minutes or less, the application to the RTR method can be more easily performed.
On the other hand, the longer the processing time in the conversion process, the more the electron transfer characteristics tend to improve. Therefore, from the viewpoint of sure conversion to a metal oxide film having high electron transfer characteristics, the processing time in the conversion process is 5 minutes or more. Preferably, 10 minutes or more is more preferable.

  Further, the atmosphere during the ultraviolet irradiation in the conversion step is preferably an oxygen concentration (volume ratio) of 80000 ppm or less (8% or less), and more preferably 30000 ppm or less (3% or less). If the oxygen concentration of the atmosphere in which the metal oxide precursor film is irradiated with ultraviolet rays is 80000 ppm or less, a metal oxide film having higher electron transfer characteristics can be obtained, and if it is 30000 ppm or less, metal oxide having higher electron transfer characteristics is obtained. A material film can be obtained.

  As a means for adjusting the oxygen concentration in the atmosphere at the time of ultraviolet irradiation to the above-mentioned concentration range, for example, nitrogen gas supplied to a processing chamber for performing heating and ultraviolet irradiation on the metal oxide precursor film on the substrate or the like Examples include a method for adjusting the flow rate of the inert gas, a method for adjusting the oxygen concentration in the gas supplied to the processing chamber, and a method for evacuating the processing chamber in advance and filling the gas with a desired oxygen concentration therein. .

Examples of the light source for ultraviolet irradiation during the heat treatment in the conversion step include a UV lamp and a UV laser. A UV lamp is preferable from the viewpoint of uniformly irradiating ultraviolet rays with inexpensive equipment uniformly over a large area. Examples of UV lamps include excimer lamps, deuterium lamps, low pressure mercury lamps, high pressure mercury lamps, ultra high pressure mercury lamps, metal halide lamps, helium lamps, carbon arc lamps, cadmium lamps, electrodeless discharge lamps, etc. It is preferable to use a mercury lamp because the metal oxide precursor film can be easily converted into the metal oxide film.
Through the above steps, a metal oxide film having electron transfer characteristics can be easily manufactured.

<Thin film transistor>
Since the metal oxide film manufactured according to the embodiment of the present invention exhibits high electron transfer characteristics, it can be used as a semiconductor film or a conductive film. For example, an electrode (a source electrode, a drain electrode, or a thin film transistor (TFT) electrode) Gate electrode) or an active layer (oxide semiconductor layer). For example, if the present invention is applied to formation of an active layer, a TFT having high mobility can be manufactured in a short time.
Hereinafter, an embodiment in which a metal oxide film produced by the production method of the present invention is used as an active layer of a thin film transistor will be described. In addition, the manufacturing method of the metal oxide film of this invention and the metal oxide film manufactured by it are not limited to the active layer of TFT.

The element structure of the TFT according to the present disclosure is not particularly limited, and may be any of a so-called reverse stagger structure (also referred to as a bottom gate type) and a stagger structure (also referred to as a top gate type) based on the position of the gate electrode. Also good. Further, based on the contact portion between the active layer and the source and drain electrodes (referred to as “source / drain electrodes” as appropriate), either a so-called top contact type or bottom contact type may be used.
The top gate type is a form in which a gate electrode is disposed on the upper side of the gate insulating film and an active layer is formed on the lower side of the gate insulating film when the substrate on which the TFT is formed is the lowermost layer. The bottom gate type is a form in which a gate electrode is disposed below the gate insulating film and an active layer is formed above the gate insulating film. The bottom contact type is a mode in which the source / drain electrodes are formed before the active layer and the lower surface of the active layer is in contact with the source / drain electrodes. The top contact type is the type in which the active layer is the source / drain. In this embodiment, the upper surface of the active layer is in contact with the source / drain electrodes.

  FIG. 1 is a schematic diagram illustrating an example of a top contact type TFT according to the present disclosure having a top gate structure. In the TFT 10 shown in FIG. 1, the above-described oxide semiconductor film is stacked as an active layer 14 on one main surface of the substrate 12. A source electrode 16 and a drain electrode 18 are disposed on the active layer 14 so as to be spaced apart from each other, and a gate insulating film 20 and a gate electrode 22 are sequentially stacked thereon.

  FIG. 2 is a schematic diagram illustrating an example of a TFT according to the present disclosure having a top gate structure and a bottom contact type. In the TFT 30 shown in FIG. 2, the source electrode 16 and the drain electrode 18 are disposed on one main surface of the substrate 12 so as to be separated from each other. Then, the above-described oxide semiconductor film, the gate insulating film 20, and the gate electrode 22 are sequentially stacked as the active layer.

  FIG. 3 is a schematic diagram showing an example of a top contact type TFT according to the present disclosure having a bottom gate structure. In the TFT 40 illustrated in FIG. 3, the gate electrode 22, the gate insulating film 20, and the above-described oxide semiconductor film as the active layer 14 are sequentially stacked on one main surface of the substrate 12. A source electrode 16 and a drain electrode 18 are spaced apart from each other on the surface of the active layer 14.

  FIG. 4 is a schematic diagram illustrating an example of a bottom contact type TFT according to the present disclosure having a bottom gate structure. In the TFT 50 shown in FIG. 4, the gate electrode 22 and the gate insulating film 20 are sequentially stacked on one main surface of the substrate 12. A source electrode 16 and a drain electrode 18 are disposed on the surface of the gate insulating film 20 so as to be spaced apart from each other, and the above-described oxide semiconductor film is stacked thereon as the active layer 14.

  In the following embodiment, the top-gate thin film transistor 10 shown in FIG. 1 will be mainly described. However, the thin film transistor of the present disclosure is not limited to the top-gate type, and may be a bottom-gate type thin film transistor.

(Active layer)
When manufacturing the TFT 10 of the present embodiment, first, a metal oxide semiconductor film is formed on the substrate 12 through the above-described metal oxide precursor film forming process and conversion process, and the metal oxide semiconductor film is formed as an active layer. Pattern into shape.
Patterning may be converted into a metal oxide semiconductor film by forming a metal oxide precursor film having a pattern of an active layer in advance by the above-described inkjet method, dispenser method, relief printing method, intaglio printing method, etc. The metal oxide semiconductor film may be patterned into the shape of the active layer by photolithography and etching. In order to form a pattern by photolithography and etching, for example, a resist pattern is formed on the remaining portion by photolithography, and an acid solution such as hydrochloric acid, nitric acid, dilute sulfuric acid, phosphoric acid, or a mixed solution of nitric acid and acetic acid is used. The pattern of the active layer 14 may be formed by etching.

  The thickness of the active layer 14 is preferably 5 nm or more and 50 nm or less from the viewpoint of flatness and time required for film formation.

  From the viewpoint of obtaining high mobility, the content of indium in the active layer 14 is preferably 50 atom% or more of the metal component contained in the active layer 14, and more preferably 80 atom% or more.

(Protective layer)
A protective layer (not shown) for protecting the active layer 14 is preferably formed on the active layer 14 when the source / drain electrodes 16 and 18 are etched. There is no particular limitation on the method for forming the protective layer, and the protective layer may be formed after the metal oxide semiconductor film or after the patterning of the metal oxide semiconductor film.
The protective layer may be a metal oxide layer or an organic material such as a resin. The protective layer may be removed after the source electrode 16 and the drain electrode 18 (referred to as “source / drain electrodes” as appropriate) are formed.

(Source / drain electrodes)
Source / drain electrodes 16 and 18 are formed on the active layer 14. The source / drain electrodes 16 and 18 have high conductivity so as to function as electrodes, respectively, and metals such as Al, Mo, Cr, Ta, Ti, Ag, Au, Al—Nd, Ag alloy, tin oxide , Zinc oxide, indium oxide, indium tin oxide (ITO), indium zinc oxide (IZO), a metal oxide conductive film such as In—Ga—Zn—O, or the like can be used.

  When the source / drain electrodes 16 and 18 are formed, a wet method such as a printing method and a coating method, a physical method such as a vacuum deposition method, a sputtering method, and an ion plating method, a chemical method such as a CVD method and a plasma CVD method, etc. The film may be formed according to a method appropriately selected in consideration of suitability with the material to be used.

  The film thickness of the source / drain electrodes 16 and 18 is preferably 10 nm or more and 1000 nm or less, preferably 50 nm or more and 100 nm or less in consideration of film forming properties, patterning properties by etching or lift-off methods, conductivity, and the like. More preferred.

  The source / drain electrodes 16 and 18 may be formed by patterning into a predetermined shape by, for example, etching or a lift-off method after forming a conductive film, or may be directly formed by an inkjet method or the like. At this time, it is preferable to pattern the source / drain electrodes 16 and 18 and the wiring (not shown) connected to these electrodes simultaneously.

(Gate insulation film)
After forming the source / drain electrodes 16 and 18 and the wiring (not shown), the gate insulating film 20 is formed. The gate insulating film 20 preferably has a high insulating property. For example, an insulating film such as SiO ₂ , SiN _x , SiON, Al ₂ O ₃ , Y ₂ O ₃ , Ta ₂ O ₅ , HfO ₂ , or a compound thereof is used. An insulating film including two or more kinds may be used.
The gate insulating film 20 can be formed from a printing method, a wet method such as a coating method, a physical method such as a vacuum deposition method, a sputtering method or an ion plating method, or a chemical method such as a CVD or plasma CVD method. The film may be formed according to a method appropriately selected in consideration of suitability with the material to be used.

  Note that the gate insulating film 20 needs to have a thickness for reducing the leakage current and improving the voltage resistance. On the other hand, if the gate insulating film 20 is too thick, the driving voltage is increased. Although the gate insulating film 20 depends on the material, the thickness of the gate insulating film 20 is preferably 10 nm to 10 μm, more preferably 50 nm to 1000 nm, and particularly preferably 100 nm to 400 nm.

(Gate electrode)
After forming the gate insulating film 20, a gate electrode 22 is formed. It is preferable to use a material having high conductivity for the gate electrode 22. For example, metals such as Al, Mo, Cr, Ta, Ti, Ag, Au, Al—Nd, Ag alloy, tin oxide, zinc oxide, indium oxide, indium tin oxide (ITO), indium zinc oxide (IZO), IGZO The gate electrode 22 can be formed using a metal oxide conductive film or the like. As the gate electrode 22, these conductive films can be used as a single layer structure or a stacked structure of two or more layers.

The gate electrode 22 is made of a material used from a wet method such as a printing method or a coating method, a physical method such as a vacuum deposition method, a sputtering method or an ion plating method, or a chemical method such as a CVD or plasma CVD method. The film is formed according to a method appropriately selected in consideration of the suitability of the above.
The film thickness of the metal film for forming the gate electrode 22 is preferably 10 nm or more and 1000 nm or less, preferably 50 nm or more and 200 nm or less in consideration of film forming property, patterning property by etching or lift-off method, conductivity, and the like. More preferably.
After the film formation, the gate electrode 22 may be formed by patterning into a predetermined shape by an etching or lift-off method, or the pattern may be directly formed by an inkjet method or the like. At this time, it is preferable to pattern the gate electrode 22 and the gate wiring (not shown) at the same time.

<Electronic device>
Although there is no limitation in particular in the use of the thin-film transistor 10 of this embodiment demonstrated above, Since it shows a high transport characteristic, it can apply to various electronic devices. Specifically, it is suitable for manufacturing a flexible display using a driving element in a display device such as a liquid crystal display device, an organic EL (Electro Luminescence) display device, and an inorganic EL display device, and a resin substrate having low heat resistance.
Furthermore, the thin film transistor manufactured according to the present disclosure is suitably used as a driving element (driving circuit) in various electronic devices such as various sensors such as an X-ray sensor and an image sensor, and a MEMS (Micro Electro Mechanical System).
By applying the thin film transistor manufactured according to the present disclosure, the manufacturing cost of an electronic device having excellent electrical characteristics can be suppressed.

<Liquid crystal display device>
FIG. 5 shows a schematic sectional view of a part of a liquid crystal display device according to an embodiment of the present invention, and FIG. 6 shows a schematic configuration diagram of electrical wiring.

  As shown in FIG. 5, the liquid crystal display device 100 according to the present embodiment includes a top contact type TFT 10 having the top gate structure shown in FIG. 1 and a pixel lower electrode on the gate electrode 22 protected by the passivation layer 102 of the TFT 10. 104 and a liquid crystal layer 108 sandwiched between the counter upper electrode 106 and an R (red) G (green) B (blue) color filter 110 for developing different colors corresponding to each pixel. The polarizing plate 112a and 112b are provided on the substrate 12 side and the RGB color filter 110, respectively.

  As shown in FIG. 6, the liquid crystal display device 100 according to the present embodiment includes a plurality of gate lines 112 that are parallel to each other and data lines 114 that are parallel to each other and intersect the gate lines 112. Here, the gate wiring 112 and the data wiring 114 are electrically insulated. The TFT 10 is provided in the vicinity of the intersection between the gate wiring 112 and the data wiring 114.

  The gate electrode 22 of the TFT 10 is connected to the gate wiring 112, and the source electrode 16 of the TFT 10 is connected to the data wiring 114. The drain electrode 18 of the TFT 10 is connected to the pixel lower electrode 104 through a contact hole 116 provided in the gate insulating film 20 (a conductor is embedded in the contact hole 116). The pixel lower electrode 104 forms a capacitor 118 together with the grounded counter upper electrode 106.

<Organic EL display device>
FIG. 7 shows a schematic sectional view of a part of an active matrix organic EL display device according to an embodiment of the present invention, and FIG. 8 shows a schematic configuration diagram of electrical wiring.

  The active-matrix organic EL display device 200 of the present embodiment includes the TFT 10 having the top gate structure shown in FIG. 1 as a driving TFT 10a and a switching TFT 10b on a substrate 12 having a passivation layer 202. , 10b is provided with an organic EL light emitting element 214 composed of an organic light emitting layer 212 sandwiched between a lower electrode 208 and an upper electrode 210, and the upper surface is also protected by a passivation layer 216.

  As shown in FIG. 8, the organic EL display device 200 of this embodiment includes a plurality of gate wirings 220 that are parallel to each other, and data wirings 222 and driving wirings 224 that are parallel to each other and intersect the gate wirings 220. ing. Here, the gate wiring 220, the data wiring 222, and the drive wiring 224 are electrically insulated. The gate electrode 22 of the switching TFT 10 b is connected to the gate wiring 220, and the source electrode 16 of the switching TFT 10 b is connected to the data wiring 222. The drain electrode 18 of the switching TFT 10b is connected to the gate electrode 22 of the driving TFT 10a, and the driving TFT 10a is kept on by using the capacitor 226. The source electrode 16 of the driving TFT 10 a is connected to the driving wiring 224, and the drain electrode 18 is connected to the organic EL light emitting element 214.

  In the organic EL display device shown in FIG. 7, the upper electrode 210 may be a top emission type using a transparent electrode, or the lower electrode 208 and each electrode of a TFT may be a bottom emission type using a transparent electrode.

<X-ray sensor>
FIG. 9 shows a schematic sectional view of a part of an X-ray sensor according to an embodiment of the present invention, and FIG. 10 shows a schematic configuration diagram of its electrical wiring.

  The X-ray sensor 300 of this embodiment includes the TFT 10 and the capacitor 310 formed on the substrate 12, the charge collection electrode 302 formed on the capacitor 310, the X-ray conversion layer 304, and the upper electrode 306. Composed. A passivation film 308 is provided on the TFT 10.

  The capacitor 310 has a structure in which an insulating film 316 is sandwiched between a capacitor lower electrode 312 and a capacitor upper electrode 314. The capacitor upper electrode 314 is connected to one of the source electrode 16 and the drain electrode 18 (the drain electrode 18 in FIG. 9) of the TFT 10 through a contact hole 318 provided in the insulating film 316.

The charge collection electrode 302 is provided on the capacitor upper electrode 314 in the capacitor 310 and is in contact with the capacitor upper electrode 314.
The X-ray conversion layer 304 is a layer made of amorphous selenium, and is provided so as to cover the TFT 10 and the capacitor 310.
The upper electrode 306 is provided on the X-ray conversion layer 304 and is in contact with the X-ray conversion layer 304.

  As shown in FIG. 10, the X-ray sensor 300 of this embodiment includes a plurality of gate wirings 320 that are parallel to each other and a plurality of data wirings 322 that intersect with the gate wirings 320 and are parallel to each other. Here, the gate wiring 320 and the data wiring 322 are electrically insulated. The TFT 10 is provided in the vicinity of the intersection between the gate wiring 320 and the data wiring 322.

  The gate electrode 22 of the TFT 10 is connected to the gate wiring 320, and the source electrode 16 of the TFT 10 is connected to the data wiring 322. The drain electrode 18 of the TFT 10 is connected to the charge collecting electrode 302, and the charge collecting electrode 302 is connected to the capacitor 310.

  In the X-ray sensor 300 of this embodiment, X-rays enter from the upper electrode 306 side in FIG. 9 and generate electron-hole pairs in the X-ray conversion layer 304. By applying a high electric field to the X-ray conversion layer 304 by the upper electrode 306, the generated charge is accumulated in the capacitor 310 and read out by sequentially scanning the TFT 10.

  In the liquid crystal display device 100, the organic EL display device 200, and the X-ray sensor 300 of the above embodiment, a TFT having a top gate structure is provided. However, the TFT is not limited to this, and FIGS. A TFT having the structure shown in FIG.

  Examples will be described below, but the present invention is not limited to these examples.

<Example 1>
The following samples were prepared and evaluated.
(Metal oxide precursor film formation process)
Indium nitrate (In (NO ₃ ) ₃ ) · xH ₂ O, purity: 4N, manufactured by High Purity Chemical Laboratory Co., Ltd.) was dissolved in 2-methoxyethanol (special grade reagent, manufactured by Wako Pure Chemical Industries, Ltd.). An indium nitrate solution having a concentration of 1 mol / L was prepared.
A simple TFT using a p-type silicon substrate with a thermal oxide film as a substrate and using the thermal oxide film as a gate insulating film was fabricated. A 2.54 cm (1 inch) square p-type silicon substrate with a thermal oxide film was spin-coated with the prepared indium nitrate solution at a rotation speed of 1500 rpm for 30 seconds, and then on a hot plate heated to 60 ° C. for 5 minutes. Drying was performed.

(Conversion process)
The obtained metal oxide precursor film was converted into a metal oxide film under the following conditions. As a device, a VUV dry processor (VUE-3400-F, manufactured by Oak Manufacturing Co., Ltd.) equipped with a low-pressure mercury lamp was used.

The sample was set on a hot plate heated to a surface temperature of 160 ° C. in the apparatus, and waited for 5 minutes. During this time, the oxygen concentration in the processing chamber was reduced to 50 ppm or less by flowing nitrogen of 50 L / min into the processing chamber. The oxygen concentration in the apparatus treatment chamber was measured using an oxygen concentration meter (Yokogawa Electric Corporation, OX100).
The temperature calibration was performed using a Si wafer with a thermocouple, and the temperature was adjusted so that the substrate surface temperature was accurate. The substrate surface temperature was 160 ° C.

After waiting for 5 minutes, the shutter in the apparatus was opened, and a metal oxide semiconductor film was obtained by performing an ultraviolet irradiation treatment under a heat treatment at 160 ° C. for 15 minutes. During the ultraviolet irradiation treatment under the heat treatment, 50 L / min of nitrogen was always flowed.
Ultraviolet illuminance with a wavelength of 254 nm at the sample position as a peak wavelength is measured using an ultraviolet integrated light meter (manufactured by Hamamatsu Photonics, controller C9536, sensor head H9536-254, having spectral sensitivity in the range of about 200 nm to about 300 nm) And 105 mW / cm ² .
In addition, the ultraviolet illuminance having a wavelength of 185 nm as a peak wavelength is measured using an ultraviolet integrating light meter (manufactured by Hamamatsu Photonics, controller C9536, sensor head H9536-185, having a spectral sensitivity in the range of about 150 nm to 200 nm) It was 8.2 mW / cm ² .

  A source / drain electrode was formed on the metal oxide semiconductor film obtained above by vapor deposition. The source / drain electrodes were formed by pattern deposition using a metal mask, and Ti was deposited to a thickness of 50 nm. The source / drain electrode size was 1 mm square, and the distance between the electrodes was 0.2 mm.

<Example 2, Comparative Examples 1 and 2>
(Example of changing the UV illuminance in the conversion process)
A simple TFT was produced in the same manner as in Example 1 except that the ultraviolet illuminance in the conversion step of Example 1 was changed.
Table 1 shows the ultraviolet illuminance in the conversion steps of Examples 1 and 2 and Comparative Examples 1 and 2. The ultraviolet illuminance was adjusted by introducing a neutral density filter (metal mesh) between the low-pressure mercury lamp and the metal oxide precursor film.

[Evaluation]
(Transistor characteristics)
For simplified TFT obtained above, using a semiconductor parameter analyzer 4156C (manufactured by Agilent Technologies), it was measured transistor characteristics _V g -I _d.
Measurement of V _g -I _d characteristics, the drain voltage _{(V d)} is fixed to + 1V, the gate voltage _{(V g)} is changed within the range of -15V~ + 30V, the drain current at gate voltages _(I d) It was performed by measuring.
Figure 11, a, _V g -I _d characteristics of the Examples 1 and 2, also linear mobility determined from _V g -I _d characteristics in Table 2 (hereinafter, referred to as "mobility" Is).

12 and 13 show the relationship between ultraviolet illuminance and mobility. It can be seen that in the ultraviolet irradiation treatment for 15 minutes under the heat treatment, the illuminance of more than 200 nm to 300 nm or less and the illuminance of 150 nm to 200 nm are increased, and the mobility is rapidly improved when a certain threshold value is exceeded. Specifically in spite of the short-term treatment for 15 minutes, 200 nm ultra 300nm following illuminance 80 mW / cm ² or more, and, 200 nm or less illumination than 150nm is 6.5 mW / cm ² or more (Example 2 ), A high mobility of 0.2 cm ² / Vs is obtained, an illuminance of more than 200 nm and not more than 300 nm is 90 mW / cm ² or more (Example 1), and an illuminance of 150 to 200 nm is 7 mW / cm ² or more. If so, the mobility increases exponentially and high mobility can be obtained in a short time.

<Examples 3 and 4 and Comparative Examples 3 and 4>
(Example in which the conversion process time is 25 minutes)
The processing time in the conversion process of Examples 1 and 2 and Comparative Examples 1 and 2 except that the 25 minutes, respectively to prepare a simplified TFT in the same manner, was measured in the transistor characteristics V _g -I _d. Specifically, Example 3 has the same illumination conditions as Example 1, Example 4 has the same illumination conditions as Example 2, Comparative Example 3 has the same illumination conditions as Comparative Example 1, and Comparative Example 4 has the same characteristics as Comparative Example 2. Illuminance conditions. Table 3 shows the linear mobility of Examples 3 and 4 and Comparative Examples 3 and 4.

14 and 15 show the relationship between the ultraviolet illuminance and the mobility. In the ultraviolet irradiation treatment for 25 minutes under the heat treatment, the illuminance above 200 nm and below 300 nm and the illuminance above 150 nm and below 200 nm become high, and the mobility is further improved compared to the treatment for 15 minutes suddenly when a certain threshold is exceeded. I understand that Specifically spite of the short-term treatment of 25 minutes, 200 nm ultra 300nm following illuminance 80 mW / cm ² or more, and, 200 nm or less illumination than 150nm is 6.5 mW / cm ² or more (Example 4 ), A high mobility of 0.3 cm ² / Vs is obtained, and an illuminance of more than 200 nm to 300 nm or less is 90 mW / cm ² or more, and an illuminance of 150 to 200 nm is 7 mW / cm ² or more (Example 3). If so, the mobility increases exponentially and high mobility can be obtained in a short time.

<Example 5, Comparative Example 5>
(Example of changing the UV illuminance in the conversion process)
Change the ultraviolet illuminance at the converting step in Example 2, except that for 15 minutes under heating to produce a simplified TFT in the same manner as in Example 2, measured the transistor characteristics V _g -I _d It was.
Specifically, by providing a glass window that selectively attenuates light having a wavelength of 200 nm or less and adjusting the distance between the lamp and the sample, in Example 5, the illuminance of more than 200 nm and 300 nm or less is On the other hand, the illuminance between 150 nm and 200 nm or less is greatly reduced, and the shutter in the apparatus is closed. In Comparative Example 5, the illuminance between 150 nm and 200 nm and the illuminance between 200 nm and 300 nm is less than 0. (MW / cm ² ). Table 4 shows the ultraviolet illuminance and linear mobility of Example 5 and Comparative Example 5 together with Example 2.

<Examples 6 and 7>
(Example of changing substrate temperature and processing time in conversion process)
Except for changing the substrate temperature and the treatment time in the converting step in Example 1 to prepare a simplified TFT in the same manner as in Example 1 was measured of the transistors characteristics V _g -I _d. Specifically, in Example 6, the substrate temperature was 125 ° C. and the processing time was 60 minutes, and in Example 7, the substrate temperature was 195 ° C. and the processing time was 15 minutes. Table 5 shows the substrate temperature and linear mobility in the conversion steps of Examples 6 and 7 together with Example 1.

It can be seen that when the substrate temperature in the conversion step is set to 160 ° C., the mobility is greatly improved even if the treatment is performed for a short time of 15 minutes, and the substrate temperature is significantly improved by setting the substrate temperature to 195 ° C.

<Examples 8 and 9>
(Example of changing the oxygen concentration in the conversion process)
Except for changing the oxygen concentration in the atmosphere in the step of conversion Example 3 to produce a simplified TFT in the same manner as in Example 3, was measured transistor characteristics V _g -I _d. Specifically, in Example 8, the oxygen concentration was 2.7% (27000 ppm), and in Example 9, the oxygen concentration was 7.8% (78000 ppm). Note that the oxygen concentration was controlled by adjusting the nitrogen flow into the treatment chamber. Table 6 shows the oxygen concentration and linear mobility in the conversion steps of Examples 8 and 9 together with Example 3.

  It can be seen that the lower the oxygen concentration in the conversion step, the higher the mobility.

<Reference example>
(Measurement of UV absorption spectrum of indium nitrate solution)
The UV absorption spectra of the indium nitrate solutions used in the examples and comparative examples were measured. In the measurement, a double beam spectrophotometer U-2910 manufactured by Hitachi High-Technologies Corporation was used.
FIG. 16 shows an ultraviolet absorption spectrum of a solution in which indium nitrate is dissolved in 2-methoxyethanol. It can be seen that there is an absorption peak in the wavelength range of about 270-280 nm and no absorption in the wavelength range of 350 nm or more. It can be seen that the color of the solution is also colorless and transparent and has no absorption in the visible range.

  The manufacturing method of the metal oxide film of the present disclosure can form a dense metal oxide film with high electron transfer characteristics in a short time using an inexpensive material at a relatively low temperature under atmospheric pressure. Therefore, for example, it can be used for forming a metal oxide film on a resin substrate having low heat resistance. Especially for metal oxide semiconductor films, it is possible to form thin film transistors on an inexpensive resin substrate by using inexpensive materials, exhibiting high semiconductor properties at a relatively low temperature under atmospheric pressure, and in a short time. The present invention can be used for manufacturing a display device such as a liquid crystal display and an organic EL, particularly a flexible display.

The entire disclosure of Japanese Patent Application No. 2014-129571 is incorporated herein by reference.
All documents, patents, patent applications, and technical standards mentioned in this specification are specifically and individually described as individual documents, patents, patent applications, and technical standards are incorporated by reference. To the same extent, it is incorporated herein by reference.

Claims (27)

A metal oxide precursor film forming step of forming a metal oxide precursor film by applying a solution containing at least indium as a solvent and a metal component on a substrate;
With the metal oxide precursor film heated, the metal oxide precursor film has an illuminance of more than 200 nm and not more than 300 nm of 80 mW / cm ² and an illuminance of not less than 150 nm and not more than 200 nm. A conversion step of converting the metal oxide precursor film into a metal oxide film by irradiating ultraviolet rays under conditions satisfying at least one of 6.5 mW / cm ² or more;
The manufacturing method of the metal oxide film which has this. ^{2. The} method for producing a metal oxide film according to claim 1, wherein the ultraviolet irradiation is performed under a condition in which an illuminance of at least the wavelength of 200 nm to 300 nm is at least 80 mW / cm ² . The irradiation of the ultraviolet, the or less of illuminance wavelength 200nm ultra 300nm is 80 mW / cm ² or more, and, according to claim 1 or the wavelength 150nm or more 200nm following illuminance performed under conditions at 6.5 mW / cm ² or more The manufacturing method of the metal oxide film of Claim 2. The method for producing a metal oxide film according to any one of claims 1 to 3, wherein the illuminance of the ultraviolet light having a wavelength of 200 nm to 300 nm is 90 mW / cm ² or more. 5. The method for producing a metal oxide film according to claim 1, wherein an illuminance of the ultraviolet light having a wavelength of 150 nm to 200 nm is 7 mW / cm ² or more.   The method for producing a metal oxide film according to claim 1, wherein the irradiation time of the ultraviolet rays is 25 minutes or less.   The method for producing a metal oxide film according to any one of claims 1 to 6, wherein the irradiation time of the ultraviolet rays is 15 minutes or less.   The method for producing a metal oxide film according to any one of claims 1 to 7, wherein an oxygen concentration in an atmosphere irradiated with the ultraviolet rays is 80,000 ppm or less.   The method for producing a metal oxide film according to any one of claims 1 to 8, wherein an oxygen concentration in an atmosphere irradiated with the ultraviolet rays is 30000 ppm or less.   The method for producing a metal oxide film according to any one of claims 1 to 9, wherein the temperature of the substrate during irradiation with the ultraviolet rays is maintained at less than 200 ° C.   The method for producing a metal oxide film according to any one of claims 1 to 10, wherein the substrate temperature is kept above 120 ° C during irradiation with the ultraviolet rays.   The method for producing a metal oxide film according to claim 1, wherein indium contained in the solution is indium ions.   The method for producing a metal oxide film according to claim 1, wherein the solution contains nitrate ions.   The method for producing a metal oxide film according to any one of claims 1 to 13, wherein a rate at which the temperature of the substrate rises or falls during irradiation of the ultraviolet rays is within ± 0.5 ° C / min.   The method for producing a metal oxide film according to claim 1, wherein 50 atom% or more of the metal component contained in the solution is indium.   The method for producing a metal oxide film according to claim 1, wherein the solution is a solution in which at least indium nitrate is dissolved in the solvent.   The method for producing a metal oxide film according to any one of claims 1 to 16, wherein the solution further contains at least one metal component selected from the group consisting of zinc, tin, gallium, and aluminum.   The method for producing a metal oxide film according to any one of claims 1 to 17, wherein the solvent contains at least one selected from methanol, methoxyethanol, and water.   The method for producing a metal oxide film according to any one of claims 1 to 18, wherein a concentration of a metal component in the solution is 0.01 mol / L or more and 1.0 mol / L or less.   The method for producing a metal oxide film according to any one of claims 1 to 19, wherein a light source used for the irradiation with ultraviolet rays is a low-pressure mercury lamp.   The said metal oxide precursor film | membrane formation process WHEREIN: The said solution is apply | coated on the said board | substrate, The said metal oxide precursor film | membrane is formed by heating and drying the said board | substrate to 35 to 100 degreeC. The manufacturing method of the metal oxide film of any one of Claims 1-20.   In the metal oxide precursor film forming step, the solution is applied onto the substrate by at least one application method selected from an inkjet method, a dispenser method, a relief printing method, and an intaglio printing method. The method for producing a metal oxide film according to claim 21.   The metal oxide film produced using the manufacturing method of the metal oxide film of any one of Claims 1-22.   24. The metal oxide film according to claim 23, wherein 50 atom% or more of a metal component contained in the metal oxide film is indium.   The metal oxide film according to claim 23 or 24, which is a semiconductor film.   A thin film transistor having an active layer including the metal oxide film according to claim 25, a source electrode, a drain electrode, a gate insulating film, and a gate electrode.   An electronic device comprising the thin film transistor according to claim 26.