JP6787386B2 - Coating liquid for forming an insulating film - Google Patents

Description

The present invention relates to a coating liquid for forming an insulating film, a field effect transistor, a display element, an image display device, and a system.

A field effect transistor (FET), which is a type of semiconductor device, has a current flowing between a source and a drain by applying a gate voltage to induce carriers in the semiconductor while an electric field is applied to the channel. It is a transistor that can control.

Since the FET can be switched by applying a gate voltage, it is used as various switching elements and amplification elements. Further, since the FET has a low gate current and a flat structure, it can be easily manufactured as compared with a bipolar transistor, and further, high integration can be easily performed. For this reason, the FET is used in many of the integrated circuits used in current electronic devices.
Among them, the FET is applied as a thin film transistor (TFT) to an active matrix type display or the like.

In recent years, as an active matrix type flat panel display (FPD), a liquid crystal display (Liquid Crystal Display: LCD), an organic EL (electroluminescence) display (OLED), an electronic paper, and the like have been put into practical use.

These FPDs are usually driven by a drive circuit including a TFT using amorphous silicon or polycrystalline silicon as an active layer. Further, the FPD is required to have a larger size, higher definition, and higher speed driveability. Along with this, a TFT having a high carrier mobility, a small change in characteristics with time, and a small variation between elements is required. Has been done.

In recent years, as the semiconductor of the active layer, an oxide semiconductor has attracted attention in addition to silicon. Among them, InGaZnO ₄ (a-IGZO) has the characteristics of being able to form a film at room temperature, being in an amorphous state, and having high mobility characteristics of around 10 cm ² / V · s, and is being actively developed for practical use. (See, for example, Non-Patent Document 1).

The FET usually has a protective layer for the purpose of protecting the semiconductor layer which is the active layer. Various studies have also been made on the protective layer.
For example, as the protective layer of the FET, a SiO ₂ layer (see, for example, Patent Documents 1 and 2), a SiNx layer (for example, see Patent Document 1), a SiON layer (see, for example, Patent Document 3), and Al ₂ O. _Three layers (see, for example, Patent Document 4) have been proposed. Further, as a protective layer for the FET, a composite oxide layer in which SiO ₂ and Al or B are combined has been proposed (see, for example, Patent Document 5).
However, when the SiO ₂ layer and the composite oxide layer are formed on the silicon semiconductor layer, the oxide semiconductor layer, the metal wiring, and the oxide wiring, cracks, peeling, and the like occur in the heating step of the subsequent step. There is a problem that it is easy to do. Further, SiON layer, SiNx layer, and _{the Al} 2 _{O 3} layer has a problem that signal delay due to parasitic capacitance occurs.

It has also been proposed to use an organic material as the protective layer.
For example, as a protective layer for the FET, a polyimide resin layer (see, for example, Patent Document 6) and a fluororesin layer (see, for example, Patent Document 3) have been proposed.
However, general organic materials have a problem that they cause deterioration of TFT characteristics when they come into contact with oxide semiconductors. Further, although the fluororesin layer has a relatively small deterioration in TFT characteristics, it is not sufficient.

Therefore, the current situation is that there is a demand for providing a field effect transistor capable of high-speed operation and exhibiting high reliability.

An object of the present invention is to solve the above-mentioned problems in the past and to achieve the following object. That is, an object of the present invention is to provide a field effect transistor capable of high-speed operation and exhibiting high reliability.

The means for solving the above-mentioned problems are as follows. That is,
The field effect transistor of the present invention
With the base material
With a protective layer,
A gate insulating layer formed between the base material and the protective layer,
A source electrode and a drain electrode formed so as to be in contact with the gate insulating layer,
A semiconductor layer formed between at least the source electrode and the drain electrode and in contact with the gate insulating layer, the source electrode, and the drain electrode.
It has a gate electrode formed on the side opposite to the semiconductor layer with the gate insulating layer interposed therebetween and in contact with the gate insulating layer.
The protective layer is characterized by containing a composite metal oxide containing at least Si and an alkaline earth metal.

According to the present invention, it is possible to provide a field-effect transistor capable of solving the above-mentioned problems in the past, capable of high-speed operation, and exhibiting high reliability.

FIG. 1 is a diagram for explaining an image display device. FIG. 2 is a diagram for explaining an example of the display element of the present invention. FIG. 3A is a diagram showing an example (bottom contact / bottom gate type) of the field effect transistor of the present invention. FIG. 3B is a diagram showing an example (top contact / bottom gate type) of the field effect transistor of the present invention. FIG. 3C is a diagram showing an example (bottom contact / top gate type) of the field effect transistor of the present invention. FIG. 3D is a diagram showing an example (top contact / top gate type) of the field effect transistor of the present invention. FIG. 4 is a schematic configuration diagram showing an example of an organic EL element. FIG. 5 is a schematic configuration diagram showing an example of the display element of the present invention. FIG. 6 is a schematic configuration diagram showing another example of the display element of the present invention. FIG. 7 is a diagram for explaining a display control device. FIG. 8 is a diagram for explaining a liquid crystal display. FIG. 9 is a diagram for explaining the display element in FIG. FIG. 10 is a schematic configuration diagram of a relative permittivity measuring capacitor. FIG. 11 is a graph for evaluating the characteristics of the field effect transistor obtained in Example 1. FIG. 12 is a graph evaluating the characteristics of the field effect transistor obtained in Example 1. FIG. 13 is a graph evaluating the characteristics of the field effect transistor obtained in Comparative Example 1. FIG. 14 is a graph evaluating the characteristics of the field effect transistor obtained in Comparative Example 1. FIG. 15 is a diagram showing an organic EL display device manufactured in Example 19.

(Field effect transistor)
The field-effect transistor of the present invention has at least a base material, a protective layer, a gate insulating layer, a source electrode, a drain electrode, a semiconductor layer, and a gate electrode, and further, if necessary, other Has a member.

<Base material>
The shape, structure, and size of the base material are not particularly limited and may be appropriately selected depending on the intended purpose.
The material of the base material is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include glass and plastic.
The glass is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include non-alkali glass and silica glass.
The material of the plastic is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include polycarbonate (PC), polyimide (PI), polyethylene terephthalate (PET) and polyethylene naphthalate (PEN). Be done.
The base material is preferably subjected to pretreatment such as oxygen plasma, UV ozone, and UV irradiation cleaning from the viewpoint of surface cleaning and improvement of adhesion.

<Protective layer>
The protective layer is not particularly limited as long as it contains a composite metal oxide containing at least Si (silicon) and an alkaline earth metal, and can be appropriately selected depending on the intended purpose.
The protective layer is preferably formed of the composite metal oxide itself.
The protective layer is usually formed above the substrate.
In the composite metal oxide, SiO ₂ formed of Si forms an amorphous structure. Further, the alkaline earth metal has a function of breaking the Si—O bond. Therefore, it is possible to control the relative permittivity and the coefficient of linear expansion of the composite metal oxide formed by the composition ratio.

The composite metal oxide preferably contains at least one of Al (aluminum) and B (boron).
Since Al ₂ O ₃ formed by the Al and B ₂ O ₃ formed by the B form an amorphous structure in the same manner as SiO ₂ , the composite metal oxide has a more stable amorphous structure. As a result, it becomes possible to form a more uniform insulating film. Further, since the alkaline earth metal also breaks the Al—O bond and the BO bond as well as the Si—O bond, the relative permittivity and linear expansion of the composite metal oxide formed according to the composition ratio thereof. It is possible to control the coefficient.

Examples of the alkaline earth metal include Be (beryllium), Mg (magnesium), Ca (calcium), Sr (strontium), and Ba (barium). Among these, magnesium (Mg), calcium (Ca), strontium (Sr), and barium (Ba) are preferable.
These alkaline earth metals may be used alone or in combination of two or more.

The ratio of the Si, the total ratio of Al and B, and the ratio of the alkaline earth metal in the composite metal oxide are not particularly limited and may be appropriately selected depending on the intended purpose. It is preferably in the range.
The ratio of Si in the composite metal oxide is preferably 30.0 mol% to 95.0 mol%, more preferably 50.0 mol% to 90.0 mol% in terms of oxide (SiO ₂ ).
The ratio of the alkaline earth metal oxide in the composite metal oxide is preferably 5.0 mol% to 40.0 mol%, preferably 10.0 mol% to 10.0 mol% in terms of oxides (BeO, MgO, CaO, SrO, BaO). 30.0 mol% is more preferable.
The total ratio of Al and B in the composite metal oxide is preferably 1.0 mol% to 50.0 mol%, preferably 5.0 mol% to 30 in terms of oxides (Al ₂ O ₃ , B ₂ O ₃ ). 0.0 mol% is more preferable.
When the composite metal oxide contains at least one of the Al and the B, the ratio of the alkaline earth metal oxide is 1. In terms of oxide (BeO, MgO, CaO, SrO, BaO). It is preferably 0 mol% to 30.0 mol%, more preferably 5.0 mol% to 20.0 mol%.
The proportion of oxides (SiO ₂ , BeO, MgO, CaO, SrO, BaO, Al ₂ O ₃ , B ₂ O ₃ ) in the composite metal oxide is, for example, fluorescent X-ray analysis, electron beam micro-analysis (EPMA). It can be calculated by analyzing the cation element of the oxide.

The relative permittivity of the protective layer is not particularly limited and may be appropriately selected depending on the intended purpose, but is preferably 7.0 or less from the viewpoint of less likely to cause signal delay and higher speed operation. More preferably 6.0 or less.
The relative permittivity can be measured, for example, by preparing a lower electrode, a dielectric layer (the protective layer), and a capacitor in which the electrodes are laminated, and using an LCR meter (4284A, manufactured by Agilent).

The coefficient of linear expansion of the protective layer is not particularly limited and may be appropriately selected depending on the intended purpose. However, from the viewpoint that peeling is less likely to occur and reliability is higher, 30.0 × ^10-7. The above is preferable, and 30.0 × ^{10-7 to} 60.0 × ^10-7 is more preferable.
The coefficient of linear expansion can be measured using, for example, a thermomechanical analyzer (8310 series, manufactured by Rigaku Co., Ltd.). In this measurement, the coefficient of linear expansion can be measured by separately preparing and measuring a measurement sample having the same composition as that of the protective layer without manufacturing the field-effect transistor.

The average film thickness of the protective layer is not particularly limited and may be appropriately selected depending on the intended purpose, but is preferably 10 nm to 1,000 nm, more preferably 20 nm to 500 nm.

-How to form a protective layer-
The method for forming the protective layer is not particularly limited and may be appropriately selected depending on the intended purpose. For example, a sputtering method, a pulse laser deposit (PLD) method, a CVD (Chemical Vacuum Deposition) method, and an ALD (Atomic) method are used. Examples thereof include a method of patterning by photolithography after film formation by a vacuum process such as the Laser Deposition) method.
Further, a coating liquid containing a precursor of the composite metal oxide (coating liquid for forming a protective layer) is prepared, coated or printed on an object to be coated, and fired under appropriate conditions to form a film. It is possible to do.

--Coating liquid for forming a protective layer (coating liquid for forming an insulating film) ---
The coating liquid for forming a protective layer (also referred to as a coating liquid for forming an insulating film) contains at least a silicon-containing compound, an alkaline earth metal-containing compound, and a solvent, preferably an aluminum-containing compound and a boron-containing compound. It contains at least one and, if necessary, other components.

In recent years, the development of printed electronics using a coating process that can reduce the cost has become active for a vacuum process that requires expensive equipment such as a sputtering method, a CVD method, and a dry etching method. It has been reported that the protective layer of a semiconductor is also formed by coating using polysilazane (see, for example, Japanese Patent Application Laid-Open No. 2010-103203), spin-on glass, or the like.

However, a coating liquid consisting only of SiO ₂ precursors such as polysilazane and spin-on-glass requires firing at 450 ° C. or higher in order to decompose organic substances and obtain a dense insulating film. In order to decompose organic matter at a temperature lower than that, it is different from heating such as microwave treatment (see, for example, Japanese Patent Application Laid-Open No. 2010-103203), use of a catalyst, and firing in a steam atmosphere (Patent No. 3666915). It is indispensable to use the reaction promoting means in combination. Therefore, there are problems that the firing process is complicated, the cost is increased, and the insulating property is lowered due to the residual impurities.
On the other hand, since the coating liquid for forming the protective layer contains a precursor of an alkaline earth metal oxide having a lower decomposition temperature than the SiO ₂ precursor, the temperature is lower than that of the coating liquid consisting of only the SiO ₂ precursor. That is, it is possible to decompose the precursor at a temperature of less than 450 ° C. to form a dense insulating film. Further, like the precursor of the alkaline earth metal oxide, it is dense at low temperature by further containing at least one of the Al ₂ O ₃ precursor and the B ₂ O ₃ precursor, which have a lower decomposition temperature than the SiO ₂ precursor. It is possible to enhance the effect of forming an insulating film.

--- Silicon-containing compound ---
Examples of the silicon-containing compound include an inorganic silicon compound and an organosilicon compound.

Examples of the inorganic silicon compound include tetrachlorosilane, tetrabromosilane, and tetraiodosilane.

The organosilicon compound is not particularly limited as long as it is a compound having silicon and an organic group, and can be appropriately selected depending on the intended purpose. The silicon and the organic group are bonded by, for example, an ionic bond, a covalent bond, or a coordination bond.

The organic group is not particularly limited and may be appropriately selected depending on the intended purpose. For example, an alkyl group which may have a substituent, an alkoxy group which may have a substituent, or a substituent may be used. Examples thereof include an acyloxy group which may have a substituent and a phenyl group which may have a substituent. Examples of the alkyl group include an alkyl group having 1 to 6 carbon atoms. Examples of the alkoxy group include an alkoxy group having 1 to 6 carbon atoms. Examples of the acyloxy group include an acyloxy group having 1 to 10 carbon atoms.

Examples of the organosilicon compound include tetramethoxysilane, tetraethoxysilane, tetraisopropoxysilane, tetrabutoxysilane, 1,1,1,3,3,3-hexamethyldisilazane (HMDS), and bis (trimethylsilyl). Examples thereof include acetylene, triphenylsilane, silicon 2-ethylhexaneate, and tetraacetoxysilane.

The content of the silicon-containing compound in the coating liquid for forming a protective layer is not particularly limited and may be appropriately selected depending on the intended purpose.

--- Alkaline earth metal-containing compounds ---
Examples of the alkaline earth metal-containing compound include an inorganic alkaline earth metal compound and an organic alkaline earth metal compound.
Examples of the alkaline earth metal in the alkaline earth metal-containing compound include Be (beryllium), Mg (magnesium), Ca (calcium), Sr (strontium), and Ba (barium).

Examples of the inorganic alkaline earth metal compound include alkaline earth metal nitrate, alkaline earth metal sulfate, alkaline earth metal chloride, alkaline earth metal fluoride, alkaline earth metal bromide, and alkaline earth metal. Examples include compounds and alkaline earth metal phosphates. Examples of the alkaline earth metal nitrate include magnesium nitrate, calcium nitrate, strontium nitrate, barium nitrate and the like. Examples of the alkaline earth metal sulfate include magnesium sulfate, calcium sulfate, strontium sulfate, barium sulfate and the like. Examples of the alkaline earth metal chloride include magnesium chloride, calcium chloride, strontium chloride, barium chloride and the like. Examples of the alkaline earth metal fluoride include magnesium fluoride, calcium fluoride, strontium fluoride, barium fluoride and the like. Examples of the alkaline earth metal bromide include magnesium bromide, calcium bromide, strontium bromide, and barium bromide. Examples of the alkaline earth metal iodide include magnesium iodide, calcium iodide, strontium iodide, barium iodide and the like. Examples of the alkaline earth metal phosphide include magnesium phosphide and calcium phosphide.

The organic alkaline earth metal compound is not particularly limited as long as it is a compound having an alkaline earth metal and an organic group, and can be appropriately selected depending on the intended purpose. The alkaline earth metal and the organic group are bonded by, for example, an ionic bond, a covalent bond, or a coordination bond.

The organic group is not particularly limited and may be appropriately selected depending on the intended purpose. For example, an alkyl group which may have a substituent, an alkoxy group which may have a substituent, or a substituent may be used. Acyloxy group which may have a substituent, phenyl group which may have a substituent, an acetylacetonate group which may have a substituent, a sulfonic acid group which may have a substituent, and the like. Can be mentioned. Examples of the alkyl group include an alkyl group having 1 to 6 carbon atoms. Examples of the alkoxy group include an alkoxy group having 1 to 6 carbon atoms. Examples of the acyloxy group include an acyloxy group having 1 to 10 carbon atoms, an acyloxy group partially substituted with a benzene ring such as benzoic acid, and an acyloxy group partially substituted with a hydroxy group such as lactic acid. Examples thereof include oxalic acid and an acyloxy group having two or more carbonyl groups such as citric acid.

Examples of the organic alkaline earth metal compound include magnesium methoxydo, magnesium ethoxide, diethyl magnesium, magnesium acetate, magnesium formate, magnesium acetylacetone, magnesium 2-ethylhexanoate, magnesium lactate, magnesium naphthenate, and magnesium citrate. Magnesium salicylate, magnesium benzoate, magnesium oxalate, magnesium trifluoromethanesulfonate, calcium methoxyde, calcium ethoxide, calcium acetate, calcium formate, acetylacetone calcium, calcium dipivaloylmethanate, calcium 2-ethylhexanoate, lactic acid Calcium, calcium naphthenate, calcium citrate, calcium salicylate, calcium neodecanoate, calcium benzoate, calcium oxalate, strontium isopropoxide, strontium acetate, strontium formate, acetylacetone strontium, strontium 2-ethylhexanoate, strontium lactate, naphthen Strontium acid, strontium salicylate, strontium oxalate, barium ethoxydo, barium isopropoxide, barium acetate, barium formate, acetylacetone barium, barium 2-ethylhexanoate, barium lactate, barium naphthenate, barium neodecanoate, barium oxalate, Examples thereof include barium benzoate and barium trifluoromethanesulfonate.

The content of the alkaline earth metal-containing compound in the coating liquid for forming a protective layer is not particularly limited and may be appropriately selected depending on the intended purpose.

--- Aluminum-containing compound ---
Examples of the aluminum-containing compound include inorganic aluminum compounds and organoaluminum compounds.

Examples of the inorganic aluminum compound include aluminum chloride, aluminum nitrate, aluminum bromide, aluminum hydroxide, aluminum borate, aluminum trifluoride, aluminum fluoride, aluminum sulfate, aluminum phosphate, and ammonium aluminum sulfate. ..

The organic aluminum compound is not particularly limited as long as it is a compound having aluminum and an organic group, and can be appropriately selected depending on the intended purpose. The aluminum and the organic group are bonded by, for example, an ionic bond, a covalent bond, or a coordination bond.

The organic group is not particularly limited and may be appropriately selected depending on the intended purpose. For example, an alkyl group which may have a substituent, an alkoxy group which may have a substituent, or a substituent may be used. Examples thereof include an acyloxy group which may have a substituent, an acetylacetonate group which may have a substituent, and a sulfonic acid group which may have a substituent. Examples of the alkyl group include an alkyl group having 1 to 6 carbon atoms. Examples of the alkoxy group include an alkoxy group having 1 to 6 carbon atoms. Examples of the acyloxy group include an acyloxy group having 1 to 10 carbon atoms, an acyloxy group partially substituted with a benzene ring such as benzoic acid, and an acyloxy group partially substituted with a hydroxy group such as lactic acid. Examples thereof include oxalic acid and an acyloxy group having two or more carbonyl groups such as citric acid.

Examples of the organic aluminum compound include aluminum isopropoxide, aluminum-sec-butoxide, triethylaluminum, diethylaluminum ethoxide, aluminum acetate, acetylacetone aluminum, hexafluoroacetylacetone aluminum, 2-ethylhexanoate, aluminum lactate, and the like. Examples thereof include aluminum benzoate, aluminum di (s-butoxide) acetoacetate chelate, and aluminum trifluoromethanesulfonate.

The content of the aluminum-containing compound in the coating liquid for forming a protective layer is not particularly limited and may be appropriately selected depending on the intended purpose.

--- Boron-containing compound ---
Examples of the boron-containing compound include an inorganic boron compound and an organic boron compound.

Examples of the inorganic boron compound include orthoboric acid, boron oxide, boron tribromide, tetrafluoroboric acid, ammonium borate, magnesium borate and the like. Examples of the boron oxide include diboron dioxide, diboron trioxide, tetraboron trioxide, and tetraboron pentoxide.

The organic boron compound is not particularly limited as long as it is a compound having boron and an organic group, and can be appropriately selected depending on the intended purpose. The boron and the organic group are bonded by, for example, an ionic bond, a covalent bond, or a coordination bond.

The organic group is not particularly limited and may be appropriately selected depending on the intended purpose. For example, an alkyl group which may have a substituent, an alkoxy group which may have a substituent, or a substituent may be used. Examples thereof include an acyloxy group which may have a substituent, a phenyl group which may have a substituent, a sulfonic acid group which may have a substituent, and a thiophene group which may have a substituent. .. Examples of the alkyl group include an alkyl group having 1 to 6 carbon atoms. Examples of the alkoxy group include an alkoxy group having 1 to 6 carbon atoms. The alkoxy group has two or more oxygen atoms, and two oxygen atoms of the two or more oxygen atoms are organic to bond with boron and form a ring structure together with boron. Groups are also included. It also includes an alkoxy group in which the alkyl group contained in the alkoxy group is replaced with an organic silyl group. Examples of the acyloxy group include an acyloxy group having 1 to 10 carbon atoms.

Examples of the organoboron compound include triethylborane, (R) -5,5-diphenyl-2-methyl-3,4-propano-1,3,2-oxazaborolidine, triisopropylborate, 2-. Isopropoxy-4,4,5,5-tetramethyl-1,3,2-dioxaborolane, bis (hexyleneglycolato) diboron, 4- (4,5,5-tetramethyl-1,3,2) -Dioxaborolan-2-yl) -1H-pyrazol, tert-butyl-N- [4- (4,5,5-tetramethyl-1,2,3-dioxaborolan-2-yl) phenyl] carbamate, phenyl Examples thereof include boric acid, 3-acetylphenylboronic acid, boron trifluoride acetate complex, boron trifluoride sulfolane complex, 2-thiophenboronic acid, and tris (trimethylsilyl) boronate.

The content of the boron-containing compound in the coating liquid for forming a protective layer is not particularly limited and may be appropriately selected depending on the intended purpose.

--- Solvent ---
The solvent is not particularly limited as long as it is a solvent that stably dissolves or disperses the various compounds, and can be appropriately selected depending on the intended purpose. For example, toluene, xylene, mesitylene, isopropanol, ethyl benzoate, etc. Examples thereof include N, N-dimethylformamide, propylene carbonate, 2-ethylhexanoic acid, mineral spirits, dimethylpropylene urea, 4-butyrolactone, 2-methoxyethanol, water and the like.

The content of the solvent in the coating liquid for forming a protective layer is not particularly limited and may be appropriately selected depending on the intended purpose.

The ratio of the silicon-containing compound to the alkaline earth metal-containing compound in the coating liquid for forming the protective layer (the silicon-containing compound: the alkaline earth metal-containing compound) is not particularly limited and may vary depending on the intended purpose. It can be appropriately selected, but in terms of oxides (SiO ₂ , BeO, MgO, CaO, SrO, BaO), 30.0 mol% to 95.0 mol%: 5.0 mol% to 40.0 mol% is preferable, and 50 More preferably, it is 0.0 mol% to 90.0 mol%: 10.0 mol% to 30.0 mol%.

The ratio of the silicon-containing compound, the alkaline earth metal-containing compound, and the total of the aluminum-containing compound and the boron-containing compound in the coating liquid for forming the protective layer (the silicon-containing compound: the alkaline earth metal-containing compound). : The aluminum-containing compound and the boron-containing compound) are not particularly limited and may be appropriately selected depending on the intended purpose, but oxides (SiO ₂ , BeO, MgO, CaO, SrO, BaO, Al ₂ O). _{3. In} terms of B ₂ O ₃ ), 30.0 mol% to 95.0 mol%: 1.0 mol% to 30.0 mol%: 1.0 mol% to 50.0 mol% is preferable, and 50.0 mol% to 90.0 mol is preferable. %: 5.0 mol% to 20.0 mol%: 5.0 mol% to 30.0 mol% is more preferable.

--- Method of forming a protective layer using a coating liquid for forming a protective layer ---
An example of a method for forming a protective layer using the coating liquid for forming a protective layer will be described.
The method for forming the protective layer includes a coating step and a heat treatment step, and further includes other steps, if necessary.

The coating step is not particularly limited as long as it is a step of applying the protective layer forming coating liquid to the object to be coated, and can be appropriately selected depending on the intended purpose.
The coating method is not particularly limited and may be appropriately selected depending on the intended purpose. For example, a method of patterning by photolithography after film formation by a solution process, a printing method such as an inkjet, a nanoimprint, or a gravure can be used. , A method of directly forming a desired shape, and the like.
Examples of the solution process include dip coating, spin coating, die coating, nozzle printing and the like.

The heat treatment step is not particularly limited as long as it is a step of heat-treating the protective layer forming coating liquid applied to the object to be coated, and can be appropriately selected depending on the intended purpose.
At the time of the heat treatment, the protective layer forming coating liquid applied to the object to be coated may be dried by natural drying or the like.
By the heat treatment, the solvent is dried, the composite metal oxide is produced, and the like.

In the heat treatment step, it is preferable that the drying of the solvent (hereinafter referred to as "drying treatment") and the formation of the composite metal oxide (hereinafter referred to as "formation treatment") are performed at different temperatures. ..
That is, it is preferable that the solvent is dried and then the temperature is raised to produce the composite metal oxide.
During the formation of the composite metal oxide, for example, decomposition of the silicon-containing compound, the alkaline earth metal-containing compound, the aluminum-containing compound, and the boron-containing compound occurs.

The temperature of the drying treatment is not particularly limited and may be appropriately selected depending on the solvent contained therein, and examples thereof include 80 ° C. to 180 ° C. In the drying, it is effective to use a decompression oven or the like for lowering the temperature.
The time of the drying treatment is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include 10 minutes to 1 hour.

The temperature of the production treatment is not particularly limited and may be appropriately selected depending on the intended purpose, but is preferably 100 ° C. or higher and lower than 450 ° C., and more preferably 200 ° C. to 400 ° C.
The time of the generation process is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include 1 hour to 5 hours.

In the heat treatment step, the drying treatment and the production treatment may be continuously carried out, or may be divided into a plurality of steps and carried out.

The heat treatment method is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include a method of heating the object to be coated.
The atmosphere in the heat treatment is not particularly limited and may be appropriately selected depending on the intended purpose, but an oxygen atmosphere is preferable. By performing the heat treatment in the oxygen atmosphere, the decomposition product can be quickly discharged to the outside of the system and the formation of the composite metal oxide can be promoted.

At the time of the heat treatment, it is effective to irradiate the substance after the drying treatment with ultraviolet light having a wavelength of 400 nm or less in order to accelerate the reaction of the production treatment. By irradiating with ultraviolet light having a wavelength of 400 nm or less, chemical bonds such as organic substances contained in the substance after the drying treatment can be cleaved and the organic substances can be decomposed, so that the composite metal oxide can be efficiently formed. Can be done.
The ultraviolet light having a wavelength of 400 nm or less is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include ultraviolet light having a wavelength of 222 nm using an excimer lamp.
It is also preferable to impart ozone in place of or in combination with the irradiation of ultraviolet light. By applying the ozone to the substance after the drying treatment, the formation of oxides is promoted.

<Gate insulating layer>
The gate insulating layer is not particularly limited as long as it is an insulating layer formed between the base material and the protective layer, and can be appropriately selected depending on the intended purpose.
The material of the gate insulating layer is not particularly limited and may be appropriately selected depending on the intended purpose. For example, a material already widely used for mass production such as SiO ₂ , SiN _x , Al ₂ O _{3 and the} like. Examples thereof include high dielectric constant materials such as La ₂ O ₃ and HfO ₂ , and organic materials such as polyimide (PI) and fluororesins.

-How to form a gate insulating layer-
The method for forming the gate insulating layer is not particularly limited and may be appropriately selected depending on the intended purpose. For example, a vacuum film forming method such as sputtering, chemical vapor deposition (CVD), or atomic layer deposition (ALD). , Spin coating, die coating, printing methods such as inkjet, and the like.

The average film thickness of the gate insulating layer is not particularly limited and may be appropriately selected depending on the intended purpose, but is preferably 50 nm to 3 μm, more preferably 100 nm to 1 μm.

<Source electrode and drain electrode>
The source electrode and the drain electrode are not particularly limited as long as they are electrodes for extracting an electric current, and can be appropriately selected depending on the intended purpose.
The source electrode and the drain electrode are formed so as to be in contact with the gate insulating layer.
The material of the source electrode and the drain electrode is not particularly limited and may be appropriately selected depending on the intended purpose. For example, metals such as Mo, Al, Ag and Cu, alloys thereof and ITO (indium oxide). Examples thereof include transparent conductive oxides such as tin) and ATO (antimonated tin oxide), and organic conductors such as polyethylenedioxythiophene (PEDOT) and polyaniline (PANI).

-Method of forming source electrode and drain electrode-
The method for forming the source electrode and the drain electrode is not particularly limited and may be appropriately selected depending on the intended purpose. For example, (i) film formation by a sputtering method, a dip coating method or the like, and then photolithography. Examples thereof include a patterning method, and (ii) a method of directly forming a desired shape by a printing process such as an inkjet, nanoimprint, or gravure.

The average film thickness of the source electrode and the drain electrode is not particularly limited and may be appropriately selected depending on the intended purpose, but is preferably 20 nm to 1 μm, more preferably 50 nm to 300 nm.

<Semiconductor layer>
The semiconductor layer is formed at least between the source electrode and the drain electrode.
The semiconductor layer is in contact with the gate insulating layer, the source electrode, and the drain electrode.
The distance between the source electrode and the drain electrode is not particularly limited as long as the semiconductor layer is at a position where the field effect transistor functions together with the source electrode and the drain electrode, depending on the purpose. Can be selected as appropriate.
The material of the semiconductor layer is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include silicon semiconductors and oxide semiconductors. Examples of the silicon semiconductor include polycrystalline silicon (p-Si) and amorphous silicon (a-Si). Examples of the oxide semiconductor include In-Ga-Zn-O, IZ-O, In-Mg-O and the like. Of these, oxide semiconductors are preferable.

-Method of forming semiconductor layer-
The method for forming the semiconductor layer is not particularly limited and may be appropriately selected depending on the intended purpose. For example, a sputtering method, a pulse laser deposit (PLD) method, a CVD method, an ALD (Atomic Layer Deposition) method, etc. After forming a film by a vacuum process, a solution process such as dip coating, spin coating, or die coating, a method of patterning by photolithography, a method of directly forming a desired shape by a printing method such as inkjet, nanoimprint, or gravure, etc. Can be mentioned.

The average film thickness of the semiconductor layer is not particularly limited and may be appropriately selected depending on the intended purpose, but is preferably 5 nm to 1 μm, more preferably 10 nm to 0.5 μm.

<Gate electrode>
The gate electrode is formed on the side opposite to the semiconductor layer with the gate insulating layer interposed therebetween.
The gate electrode is in contact with the gate insulating layer.
The material of the gate electrode is not particularly limited and may be appropriately selected depending on the intended purpose. For example, metals such as Mo, Al, Ag, Cu and alloys thereof, ITO (indium tin oxide), ATO ( Examples thereof include transparent conductive oxides such as antimony-doped tin oxide, and organic conductors such as polyethylenedioxythiophene (PEDOT) and polyaniline (PANI).

-How to form a gate electrode-
The method for forming the gate electrode is not particularly limited and may be appropriately selected depending on the intended purpose. For example, (i) a method of forming a film by a sputtering method, a dip coating method or the like, and then patterning by photolithography. ii) Examples thereof include a method of directly forming a desired shape by a printing process such as inkjet, nanoimprint, and gravure.

The average film thickness of the gate electrode is not particularly limited and may be appropriately selected depending on the intended purpose, but is preferably 20 nm to 1 μm, more preferably 50 nm to 300 nm.

The field-effect transistor structure is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include field-effect transistors having the following structures.
(1) The base material, the gate electrode formed on the base material, the gate insulating layer formed on the gate electrode, the source electrode formed on the gate insulating layer, and the drain. A field-effect transistor having an electrode, the semiconductor layer formed between the source electrode and the drain electrode, and the protective layer formed on the semiconductor layer.
(2) The base material, the source electrode and the drain electrode formed on the base material, the semiconductor layer formed between the source electrode and the drain electrode, the source electrode, and the drain. An electric field effect transistor having an electrode, the gate insulating layer formed on the semiconductor layer, the gate electrode formed on the gate insulating layer, and the protective layer formed on the gate electrode.

Examples of the field-effect transistor having the structure (1) include a bottom contact / bottom gate type (FIG. 3A) and a top contact / bottom gate type (FIG. 3B).
Examples of the field-effect transistor having the structure (2) include a bottom contact top gate type (FIG. 3C) and a top contact top gate type (FIG. 3D).
Here, in FIGS. 3A to 3D, reference numeral 21 is a base material, 22 is a gate electrode, 23 is a gate insulating layer, 24 is a source electrode, 25 is a drain electrode, 26 is an oxide semiconductor layer, and 27 is a protective layer. Represent.

The field-effect transistor can be suitably used for a display element described later, but is not limited to this, and can be used, for example, for an IC card, an ID tag, or the like.

(Display element)
The display element of the present invention has at least an optical control element and a drive circuit for driving the optical control element, and further includes other members, if necessary.

<Optical control element>
The optical control element is not particularly limited as long as it is an element whose optical output is controlled according to a drive signal, and can be appropriately selected depending on the intended purpose. For example, an electroluminescence (EL) element or an electrochromic element. Examples thereof include (EC) elements, liquid crystal elements, electrophoresis elements, and electrowetting elements.

<Drive circuit>
The drive circuit is not particularly limited as long as it has the field-effect transistor of the present invention and drives the optical control element, and can be appropriately selected depending on the intended purpose.

<Other parts>
The other members are not particularly limited and may be appropriately selected depending on the intended purpose.

Since the display element has the field-effect transistor of the present invention, it is possible to extend the life and operate at high speed.

(Image display device)
The image display device of the present invention has at least a plurality of display elements, a plurality of wirings, a display control device, and, if necessary, other members.
The image display device is a device that displays an image according to image data.

<Display element>
The display element is not particularly limited as long as it is the display element of the present invention arranged in a matrix, and can be appropriately selected depending on the intended purpose.

<Wiring>
The wiring is not particularly limited as long as it is a wiring for individually applying a gate voltage to each field effect transistor in the display element, and can be appropriately selected depending on the intended purpose.

<Display control device>
The display control device is not particularly limited as long as it is a device that individually controls the gate voltage of each field effect transistor via the plurality of wirings according to the image data, and is appropriately used according to the purpose. You can choose.

<Other parts>
The other members are not particularly limited and may be appropriately selected depending on the intended purpose.

Since the image display device has the display element of the present invention, it is possible to extend the life and operate at high speed.
The image display device is used as a display means in a mobile information device such as a mobile phone, a portable music playback device, a portable video playback device, an electronic BOOK, a PDA (Personal Digital Assistant), and an imaging device such as a still camera or a video camera. be able to. It can also be used as a means for displaying various information in a mobile system such as a car, an aircraft, a train, or a ship. Further, it can also be used as a means for displaying various information in measuring devices, analyzers, medical devices, and advertising media.

(system)
The system of the present invention has at least the image display device of the present invention and an image data creation device.
The image data creating device is a device that creates image data based on the image information to be displayed and outputs the image data to the image display device.

Hereinafter, the display element, the image display device, and the system of the present invention will be described with reference to the drawings.
First, a television device as an example of the system of the present invention will be described.
As an example of the system of the present invention, the television apparatus can adopt, for example, the configurations described in paragraphs [0038] to [0058] and FIG. 1 of JP-A-2010-074148.

Next, the image display device of the present invention will be described.
As the image display device of the present invention, for example, the configurations described in paragraphs [0059] to [0060], FIGS. 2 and 3 of JP-A-2010-074148 can be adopted.

Next, the display element of the present invention will be described with reference to the drawings.
FIG. 1 is a diagram showing a display 310 in which display elements are arranged on a matrix. As shown in FIG. 1, the display 310 has n scanning lines (X0, X1, X2, X3, ..., Xn-2, Xn-1) arranged at equal intervals along the X-axis direction. ) And m data lines (Y0, Y1, Y2, Y3, ..., Ym-1) arranged at equal intervals along the Y-axis direction and at equal intervals along the Y-axis direction. It has m current supply lines (Y0i, Y1i, Y2i, Y3i, ..., Ym-1i).
Therefore, the display element can be specified by the scanning line and the data line.

FIG. 2 is a schematic configuration diagram showing an example of the display element of the present invention.
As shown in FIG. 2 as an example, the display element includes an organic EL (electroluminescence) element 350 and a drive circuit 320 for causing the organic EL element 350 to emit light. That is, the display 310 is a so-called active matrix type organic EL display. The display 310 is a color-compatible 32-inch display. The size is not limited to this.

The drive circuit 320 in FIG. 2 will be described.
The drive circuit 320 has two field effect transistors 11 and 12 and a capacitor 13.
The field effect transistor 11 operates as a switch element. The gate electrode G is connected to a predetermined scanning line, and the source electrode S is connected to a predetermined data line. Further, the drain electrode D is connected to one terminal of the capacitor 13.

The capacitor 13 is for storing the state of the field effect transistor 11, that is, data. The other terminal of the capacitor 13 is connected to a predetermined current supply line.

The field effect transistor 12 is for supplying a large current to the organic EL element 350. The gate electrode G is connected to the drain electrode D of the field effect transistor 11. The drain electrode D is connected to the anode of the organic EL element 350, and the source electrode S is connected to a predetermined current supply line.

Therefore, when the field-effect transistor 11 is turned on, the organic EL element 350 is driven by the field-effect transistor 12.

As shown in FIG. 3A as an example, the field effect transistors 11 and 12 include a base material 21, a gate electrode 22, a gate insulating layer 23, a source electrode 24, a drain electrode 25, an oxide semiconductor layer 26, and a protective layer 27. have.
The field-effect transistors 11 and 12 can be formed by the materials, processes, and the like described in the description of the field-effect transistors of the present invention.

FIG. 4 is a schematic configuration diagram showing an example of an organic EL element.
In FIG. 4, the organic EL element 350 has a cathode 312, an anode 314, and an organic EL thin film layer 340.

The material of the cathode 312 is not particularly limited and may be appropriately selected depending on the intended purpose. For example, aluminum (Al), magnesium (Mg) -silver (Ag) alloy, aluminum (Al) -lithium (Li). Examples thereof include alloys and ITO (Indium Tin Oxide). If the magnesium (Mg) -silver (Ag) alloy is sufficiently thick, it becomes a high reflectance electrode, and if it is an ultrathin film (less than about 20 nm), it becomes a translucent electrode. In FIG. 4, light is extracted from the anode side, but light can be extracted from the cathode side by using a transparent or translucent electrode as the cathode.

The material of the anode 314 is not particularly limited and may be appropriately selected depending on the intended purpose. For example, ITO (Indium Tin Oxide), IZO (Indium Zinc Oxide), silver (Ag) -neodymium (Nd) alloy and the like can be selected. Can be mentioned. When a silver alloy is used, it becomes a high reflectance electrode and is suitable for extracting light from the cathode side.

The organic EL thin film layer 340 has an electron transport layer 342, a light emitting layer 344, and a hole transport layer 346. The electron transport layer 342 is connected to the cathode 312, and the hole transport layer 346 is connected to the anode 314. When a predetermined voltage is applied between the anode 314 and the cathode 312, the light emitting layer 344 emits light.

Here, the electron transport layer 342 and the light emitting layer 344 may form one layer, an electron injection layer may be provided between the electron transport layer 342 and the cathode 312, and holes may be further provided. A hole injection layer may be provided between the transport layer 346 and the anode 314.

FIG. 4 has described the case of a so-called “bottom emission” organic EL element that extracts light from the base material side as the optical control element, but the optical control element has a “top” that extracts light from the side opposite to the base material. It may be an "emission" organic EL element.

FIG. 5 shows an example of a display element in which the organic EL element 350 and the drive circuit 320 are combined.

The display elements include the base material 31, the first and second gate electrodes 32 and 33, the gate insulating layer 34, the first and second source electrodes 35 and 36, the first and second drain electrodes 37 and 38, and the first and second. It has first and second oxide semiconductor layers 39 and 40, first and second protective layers 41 and 42, an interlayer insulating film 43, an organic EL layer 44, and a cathode 45. The first drain electrode 37 and the second gate electrode 33 are connected to each other via a through hole formed in the gate insulating layer 34.
In FIG. 5, for convenience, it seems that a capacitor is formed between the second gate electrode 33 and the second drain electrode 38, but in reality, the capacitor forming location is not limited, and a capacitor having an appropriately required capacity is provided. It can be designed where it is needed.
Further, in the display element of FIG. 5, the second drain electrode 38 functions as an anode in the organic EL element 350.
Base material 31, first and second gate electrodes 32 and 33, gate insulating layer 34, first and second source electrodes 35 and 36, first and second drain electrodes 37 and 38, first and second The oxide semiconductor layers 39 and 40 and the first and second protective layers 41 and 42 can be formed by the materials, processes and the like described in the description of the field effect transistor of the present invention.

The material of the interlayer insulating film 43 (flattening film) is not particularly limited and may be appropriately selected depending on the intended purpose. For example, resins such as polyimide, acrylic and fluororesins, and photosensitive resins using them. , SOG (spin on glass) and the like. The interlayer insulating film forming process is not particularly limited and may be appropriately selected depending on the intended purpose. For example, it is desired by spin coating, inkjet printing, slit coating, nozzle printing, gravure printing, dip coating method or the like. The shape may be directly formed, or if it is a photosensitive material, it may be patterned by a photolithography method.

The method for producing the organic EL layer 44 and the cathode 45 is not particularly limited and may be appropriately selected depending on the intended purpose. For example, a vacuum film forming method such as a vacuum vapor deposition method or a sputtering method, an inkjet, a nozzle coating or the like Examples include the solution process.

This makes it possible to manufacture a display element, which is a so-called "bottom emission" organic EL element that extracts light emission from the base material side. In this case, the base material 31, the gate insulating layer 34, and the second drain electrode (anode) 38 are required to be transparent.

Further, in FIG. 5, the configuration in which the organic EL element 350 is arranged next to the drive circuit 320 has been described, but as shown in FIG. 6, the organic EL element 350 may be arranged above the drive circuit 320. Good. Also in this case, it is a so-called "bottom emission" that extracts light emission from the base material side, and the drive circuit 320 is required to have transparency. The source / drain electrodes and anode are transparent and have conductivity such as ITO, In ₂ O ₃ , SnO ₂ , ZnO with Ga added, ZnO with Al added, and SnO ₂ with Sb added. It is preferable to use an oxide.

As an example, the display control device 400 includes an image data processing circuit 402, a scanning line drive circuit 404, and a data line drive circuit 406, as shown in FIG. 7.

The image data processing circuit 402 determines the brightness of the plurality of display elements 302 in the display 310 based on the output signals of the video output circuit.

The scanning line drive circuit 404 individually applies a voltage to the n scanning lines according to the instruction of the image data processing circuit 402.

The data line drive circuit 406 individually applies a voltage to m data lines in response to an instruction from the image data processing circuit 402.

In the above embodiment, the case where the organic EL thin film layer includes an electron transport layer, a light emitting layer, and a hole transport layer has been described, but the present invention is not limited to this. For example, the electron transport layer and the light emitting layer may be one layer. Further, an electron injection layer may be provided between the electron transport layer and the cathode. Further, a hole injection layer may be provided between the hole transport layer and the anode.

Further, in the above embodiment, the case of so-called "bottom emission" in which light emission is extracted from the base material side has been described, but the present invention is not limited to this. For example, the anode 314 is based on a high reflectance electrode such as a silver (Ag) -neodymium (Nd) alloy, and the cathode 312 is based on a translucent electrode such as a magnesium (Mg) -silver (Ag) alloy or a transparent electrode such as ITO. Light may be extracted from the opposite side of the material.

Further, in the above embodiment, the case where the optical control element is an organic EL element has been described, but the present invention is not limited to this, and for example, the optical control element may be an electrochromic element. In this case, the display 310 becomes an electrochromic display.

Further, the optical control element may be a liquid crystal element. In this case, the display 310 becomes a liquid crystal display. Then, as shown in FIG. 8 as an example, the current supply line for the display element 302'is unnecessary.

In this case, as shown in FIG. 9 as an example, the drive circuit 320'consists of one field effect transistor 14 and a capacitor 15 similar to the above-mentioned field effect transistors (11, 12). Can be done. In the field effect transistor 14, the gate electrode G is connected to a predetermined scanning line, and the source electrode S is connected to a predetermined data line. Further, the drain electrode D is connected to the pixel electrode of the liquid crystal element 370 and the capacitor 15. Reference numerals 16 and 372 in FIG. 9 are counter electrodes (common electrodes) of the liquid crystal element 370.

In the above embodiment, the optical control element may be an electrophoresis element. Further, the optical control element may be an electrowetting element.

Further, in the above-described embodiment, the case where the display supports color has been described, but the present invention is not limited to this.

The field-effect transistor according to this embodiment can also be used for objects other than display elements (for example, IC cards and ID tags).

Since the field-effect transistor of the present invention has high-speed operation and high reliability, the same effect can be obtained for a display element, an image display device, and a system using the field-effect transistor.

Hereinafter, examples of the present invention will be described, but the present invention is not limited to the following examples. “%” Represents “mass%” unless otherwise specified.

(Examples 1 to 4)
<Manufacturing of field effect transistor>
-Preparation of coating liquid for forming protective layer-
Tetrabutoxysilane (T5702-100G, manufactured by Aldrich), aluminum di (s-butoxide) acetoacetic ester chelate (Al content 8.4%, Alfa89349, manufactured by Alfa Aesar), boric acid in the amounts shown in Table 1. Triisopropyl (Wako320-41532, manufactured by Wako Chemical Industries, Ltd.), calcium 2-ethylhexanoate mineral spirit solution (Ca content 5%, Wako351-01162, manufactured by Wako Chemical Industries, Ltd.), and strontium toluene 2-ethylhexanoate solution (manufactured by Wako Chemical Industries, Ltd.). Sr content 2%, Wako195-09561, manufactured by Wako Pure Chemical Industries, Ltd.) was diluted with toluene to obtain a coating solution for forming a protective layer. The composite metal oxide formed by the coating liquid for forming a protective layer has the composition shown in Table 2.

Next, a bottom contact bottom gate type field effect transistor as shown in FIG. 3A was manufactured.

-Formation of gate electrode-
First, the gate electrode 22 was formed on the glass substrate (base material 21). Specifically, a Mo (molybdenum) film was formed on a glass substrate (base material 21) by DC sputtering so that the average film thickness was about 100 nm. After that, a photoresist was applied, and a resist pattern similar to the pattern of the gate electrode 22 formed by prebaking, exposure by an exposure apparatus, and development was formed. Furthermore, the Mo film in the region where the resist pattern was not formed was removed by reactive ion etching (RIE). After that, the resist pattern was also removed to form the gate electrode 22 made of Mo film.

-Formation of gate insulating layer-
Next, the gate insulating layer 23 was formed on the gate electrode 22. Specifically, an Al ₂ O ₃ film was formed on the gate electrode 22 and the glass substrate (base material 21) by RF sputtering so that the average film thickness was about 300 nm, and the gate insulating layer 23 was formed.

-Formation of source and drain electrodes-
Next, the source electrode 24 and the drain electrode 25 were formed on the gate insulating layer 23. Specifically, a Mo (molybdenum) film was formed on the gate insulating layer 23 by DC sputtering so that the average film thickness was about 100 nm. After that, a photoresist was applied onto the Mo film, and a resist pattern similar to the pattern of the source electrode 24 and the drain electrode 25 formed by prebaking, exposure with an exposure apparatus, and development was formed. Furthermore, the Mo film in the region where the resist pattern was not formed was removed by RIE. After that, the resist pattern was also removed to form the source electrode 24 and the drain electrode 25 made of the Mo film.

-Formation of oxide semiconductor layer-
Next, 26 layers of oxide semiconductors were formed. Specifically, a Mg—In oxide (In ₂ MgO ₄ ) film was formed by DC sputtering so that the average film thickness was about 100 nm. After that, a photoresist was applied onto the Mg-In oxide film, and a resist pattern similar to the pattern of the oxide semiconductor layer 26 formed by prebaking, exposure with an exposure apparatus, and development was formed. Further, the Mg-In oxide film in the region where the resist pattern was not formed was removed by wet etching. After that, the oxide semiconductor layer 26 was formed by removing the resist pattern as well. As a result, the oxide semiconductor layer 26 was formed so that a channel was formed between the source electrode 24 and the drain electrode 25.

-Formation of protective layer-
Next, 0.4 mL of the coating liquid for forming the protective layer was dropped onto the substrate and spin-coated under predetermined conditions (rotated at 300 rpm for 5 seconds, then rotated at 3,000 rpm for 20 seconds, and in 5 seconds. The rotation was stopped so that it became 0 rpm). Subsequently, after a drying treatment at 120 ° C. for 1 hour in the air, firing is performed at 400 ° C. for 3 hours in an O ₂ atmosphere, and the SiO _2- A ₂ O _3- B ₂ O ₃ -CaO-SrO composite is used as the protective layer 27. A metal oxide insulating film (protective layer) was formed to complete a field effect transistor.
The average film thickness of the protective layer 27 was about 30 nm.
Finally, as a heat treatment in the subsequent step, a heat treatment at 320 ° C. for 30 minutes was performed, and then the appearance of the protective layer 27 of the field-effect transistor was evaluated. The results are shown in Table 2.

<Manufacturing of capacitors for measuring relative permittivity>
A capacitor having the structure shown in FIG. 10 was produced. First, the lower electrode 82 was formed on the glass substrate 81. Specifically, a Mo (molybdenum) film was formed by DC sputtering via a metal mask so that the average film thickness was about 100 nm. Next, the dielectric layer 83 was formed by the same process as the formation of the protective layer of the field effect transistor of each embodiment. Finally, the upper electrode 84 was formed on the dielectric layer 83 by the same material and process as the lower electrode 82 to prepare a capacitor. The average film thickness of the dielectric layer 83 was 30 nm. The relative permittivity of the produced capacitor was measured using an LCR meter (4284A, manufactured by Agilent). The results are shown in Table 2.

<Preparation of sample for measuring coefficient of linear expansion>
1 L of the coating liquid for forming the protective layer of each example was prepared, the solvent was removed, the mixture was placed in a platinum crucible, heated to 1,600 ° C. and melted, and then a columnar product having a diameter of 5 mm and a height of 10 mm was prepared by a float method. did. The average linear expansion coefficient of the produced columnar object in the temperature range of 20 ° C. to 300 ° C. was measured using a thermomechanical analyzer (8310 series, manufactured by Rigaku Co., Ltd.). The produced columnar object has the same composition as the protective layer of the field-effect transistor of each embodiment, and has the same coefficient of linear expansion.

In Table 2, "-" indicates that the ratio is 0%. The same applies to Tables 4, 6, 8, 11, 12, 13, and 15.

(Examples 5 to 7)
In the amounts shown in Table 3, 1,1,1,3,3,3-hexamethyldisilazane (HMDS, manufactured by Tokyo Oka Kogyo Co., Ltd.), aluminum di (s-butoxide) acetoacetic ester chelate (Al content 8). .4%, Alfa89349, manufactured by Alfa Aesar), phenylboronic acid (Wako163-23222, manufactured by Wako Pure Chemical Industries, Ltd.), magnesium toluene 2-ethylhexanoate solution (Mg content 3%, Stream12-1260, Strem Chemicals, Inc.), 2-ethylhexanoate calcium mineral spirit solution (Ca content 5%, Wako351-01162, manufactured by Wako Chemical Industries, Ltd.), 2-ethylhexanoate strontium toluene solution (Sr content 2%, Wako195-09561, sum) A coating solution for forming a protective layer was obtained by diluting a solution of barium toluene 2-ethylhexanoate (Ba content 8%, Wako021-09471, manufactured by Wako Pure Chemical Industries, Ltd.) with toluene. .. The composite metal oxide formed by the coating liquid for forming a protective layer has the composition shown in Table 4.
Using the prepared coating liquid for forming a protective layer, field-effect transistors, capacitors, and columnar objects were prepared and evaluated in the same manner as in Example 1. The results are shown in Table 4.

(Examples 8 and 9)
In the amounts shown in Table 5, 1,1,1,3,3,3-hexamethyldisilazane (HMDS, manufactured by Tokyo Ohka Kogyo Co., Ltd.), aluminum di (s-butoxide) acetoacetic ester chelate (Al content 8). .4%, Alfa89349, manufactured by Alfa Aesar), magnesium 2-ethylhexanoate toluene solution (Mg content 3%, Stream12-1260, Strem Chemicals, Inc.), and strontium 2-ethylhexanoate toluene solution (Sr content). 2%, Wako195-09561, manufactured by Wako Pure Chemical Industries, Ltd.) was diluted with toluene to obtain a coating solution for forming a protective layer. The composite metal oxide formed by the coating liquid for forming a protective layer has the composition shown in Table 6.
Using the prepared coating liquid for forming a protective layer, field-effect transistors, capacitors, and columnar objects were prepared and evaluated in the same manner as in Example 1. The results are shown in Table 6.

(Examples 10 and 11)
1,1,1,3,3,3-hexamethyl disilazane (HMDS, manufactured by Tokyo Ohka Kogyo Co., Ltd.), 2-isopropoxy-4,4,5,5-tetramethyl in the amounts shown in Table 7. -1,3,2-dioxaborolane (Wako 325-41462, manufactured by Wako Chemical Industries, Ltd.), 2-ethylhexanoate calcium mineral spirit solution (Ca content 5%, Wako351-01162, manufactured by Wako Chemical Industries, Ltd.), and 2- A barium toluene ethylhexanoate solution (Ba content 8%, Wako021-09471, manufactured by Wako Pure Chemical Industries, Ltd.) was diluted with toluene to obtain a coating solution for forming a protective layer. The composite metal oxide formed by the coating liquid for forming a protective layer has the composition shown in Table 8.
Using the prepared coating liquid for forming a protective layer, field-effect transistors, capacitors, and columnar objects were prepared and evaluated in the same manner as in Example 1. The results are shown in Table 8.

(Examples 12 to 18)
Tetrabutoxysilane (T5702-100G, manufactured by Aldrich), magnesium 2-ethylhexanoate toluene solution (Mg content 3%, Strem 12-1260, Strem Chemicals, Inc.), 2 in the amounts shown in Tables 9 and 10. -Calcium ethylhexanoate mineral spirit solution (Ca content 5%, Wako351-01162, manufactured by Wako Chemical Co., Ltd.), 2-ethylhexanoate strontium toluene solution (Sr content 2%, Wako195-09561, manufactured by Wako Pure Chemical Industries, Ltd.) ) And a solution of barium toluene 2-ethylhexanoate (Ba content 8%, Wako021-09471, manufactured by Wako Pure Chemical Industries, Ltd.) were diluted with toluene to obtain a coating solution for forming a protective layer. The composite metal oxide formed by the coating liquid for forming a protective layer has the compositions shown in Tables 11 and 12.
Using the prepared coating liquid for forming a protective layer, field-effect transistors, capacitors, and columnar objects were prepared and evaluated in the same manner as in Example 1. The results are shown in Tables 11 and 12.

(Comparative Example 1)
<Manufacturing of field effect transistor>
First, a gate electrode, a gate insulating layer, a source electrode and a drain electrode, and an oxide semiconductor layer were formed on a glass substrate by the same method as in Example 1.

-Formation of protective layer-
Next, a protective layer was formed. Specifically, 0.4 mL of a fluororesin coating solution (Cytop CTL-809A, manufactured by Asahi Glass Co., Ltd.) was spin-coated (rotated at 500 rpm for 10 seconds and then at 2,000 rpm for 30 seconds). Next, a protective layer was formed so as to cover the oxide semiconductor layer by prebaking at 90 ° C. for 30 minutes and then post-baking at 230 ° C. for 60 minutes. The average film thickness of the protective layer thus formed was about 1,500 nm.
Finally, as a heat treatment in the subsequent step, a heat treatment at 320 ° C. for 30 minutes was performed, and then the appearance of the protective layer 27 of the field-effect transistor was evaluated. The results are shown in Table 13.

<Manufacturing of capacitors for measuring relative permittivity>
A capacitor having the structure shown in FIG. 10 was produced. First, the lower electrode 82 was formed on the glass substrate 81. Specifically, a Mo (molybdenum) film was formed by DC sputtering via a metal mask so that the average film thickness was about 100 nm. Next, the dielectric layer 83 was formed by the same process as the formation of the protective layer of the field effect transistor of this comparative example. Finally, the upper electrode 84 was formed on the dielectric layer 83 by the same material and process as the lower electrode 82 to prepare a capacitor. The average film thickness of the dielectric layer 83 was 1,500 nm. The relative permittivity of the produced capacitor was measured with an LCR meter (4284A, manufactured by Agilent). The results are shown in Table 13.

<Preparation of sample for measuring coefficient of linear expansion>
First, a fluororesin coating solution (Cytop CTL-809A, manufactured by Asahi Glass Co., Ltd.) was diluted twice by mass with a fluorine-based solvent (CT-SOLV180, manufactured by Asahi Glass Co., Ltd.) to prepare a coating solution. Next, 0.4 mL of the coating liquid was spin-coated on a single crystal Si substrate (rotated at 500 rpm for 10 seconds and then at 1,000 rpm for 30 seconds). Subsequently, a sample for measuring the coefficient of linear expansion was prepared by prebaking at 90 ° C. for 30 minutes and then post-baking at 230 ° C. for 60 minutes. The average film thickness of the sample was 300 nm. For the prepared sample for measuring the coefficient of linear expansion, the average coefficient of linear expansion in the temperature range of 20 ° C. to 80 ° C. was measured using the X-ray reflectivity method. The results are shown in Table 13.

(Comparative Example 2)
<Manufacturing of field effect transistor>
First, a gate electrode, a gate insulating layer, a source electrode and a drain electrode, and an oxide semiconductor layer were formed on a glass substrate by the same method as in Example 1.

-Formation of protective layer-
Next, a protective layer was formed. Specifically, a SiO ₂ layer was formed as a protective layer by a PECVD (Plasma enhanced chemical vapor deposition) method using SiCl ₄ as a raw material to complete a field effect transistor. The average film thickness of the protective layer thus formed was about 30 nm.
Finally, as a heat treatment in the subsequent step, a heat treatment at 320 ° C. for 30 minutes was performed, and then the appearance of the protective layer 27 of the field-effect transistor was evaluated. The results are shown in Table 13.

<Manufacturing of capacitors for measuring relative permittivity>
A capacitor having the structure shown in FIG. 10 was produced. First, the lower electrode 82 was formed on the glass substrate 81. Specifically, a Mo (molybdenum) film was formed by DC sputtering via a metal mask so that the average film thickness was about 100 nm. Next, the dielectric layer 83 was formed by the same process as the formation of the protective layer of the field effect transistor of this comparative example. Finally, the upper electrode 84 was formed on the dielectric layer 83 by the same material and process as the lower electrode 82 to prepare a capacitor. The average film thickness of the dielectric layer 83 was 30 nm. The relative permittivity of the produced capacitor was measured with an LCR meter (4284A, manufactured by Agilent). The results are shown in Table 13.

<Making a glass plate for measuring the coefficient of linear expansion>
The SiCl ₄ as a raw material, after obtaining the SiO ₂ porous material is hydrolyzed to grow silica powder in an oxyhydrogen flame, that is melted at a high temperature of 1,600 ° C., diameter 5 mm, a height of 10mm Cylindrical SiO ₂ glass was produced. The average linear expansion coefficient of the produced columnar glass in the temperature range of 20 ° C. to 300 ° C. was measured using a thermomechanical analyzer (8310 series, manufactured by Rigaku Co., Ltd.). The produced columnar glass has the same composition as the protective layer of the field-effect transistor of this comparative example, and has the same coefficient of linear expansion.

(Comparative Examples 3 and 4)
In the amounts shown in Table 14, tetrabutoxysilane (T5702-100G, manufactured by Aldrich), aluminum di (s-butoxide) acetoacetic ester chelate (Al content 8.4%, Alfa89349, manufactured by Alfa Aesar), and 2 -Isopropoxy-4,4,5,5-tetramethyl-1,3,2-dioxaborolane (Wako 325-41462, manufactured by Wako Chemical Co., Ltd.) was diluted with toluene to obtain a coating solution for forming a protective layer. The composite metal oxide formed by the coating liquid for forming a protective layer has the composition shown in Table 15.
Using the prepared coating liquid for forming a protective layer, field-effect transistors, capacitors, and columnar objects were prepared and evaluated in the same manner as in Example 1. The results are shown in Table 15.

<Appearance of field effect transistor, relative permittivity of protective layer, coefficient of linear expansion>
The protective layer of the field-effect transistor produced in Comparative Examples 2 to 4 is an oxide composed of an Mg—In-based oxide (In ₂ MgO ₄ ) film on the source electrode 24 and the drain electrode 25 made of a Mo film. Peeling was confirmed on the semiconductor layer 26.
This is because the Mo film and the Mg-In oxide (In ₂ MgO ₄ ) film have a linear expansion coefficient of about 30 × ^10-7 , whereas the field effect transistors manufactured in Comparative Examples 2 to 4 have a linear expansion coefficient of about 30 × ^10-7 . It is probable that the coefficient of linear expansion of the protective layer was as small as 5 × ^{10-7 to} 20 × ^10-7, and stress was generated at the interface.
On the other hand, the protective layer of the field-effect transistor of Examples 1 to 18 has a linear expansion coefficient of 30.0 × ^10-7 or more while having a relative permittivity of 7.0 or less depending on its composition, and peeling is not possible. It was not seen and showed good results. In particular, the protective layers of the field effect transistors of Examples 1, 3, 5 to 14, 16 to 18 have a relative permittivity of 6.0 or less and a linear expansion coefficient of 30.0 × ^{10-7 to} 60. It was 0 × ^10-7 , showing better results.
In addition, no peeling was observed in the protective layer of the field-effect transistor produced in Comparative Example 1.

<Reliability evaluation of transistor characteristics>
To field effect transistor prepared in Examples 1 to 18, and Comparative Example 1, and the DC bias stress test under N ₂ was carried 160 hours.
Specifically, the stress conditions were set to the following two types.
(1) Condition of gate electrode 22-source electrode 24 voltage (Vgs) = + 20V and drain electrode 25-source electrode 24 voltage (Vds) = 0V (2) Condition of Vgs = Vds = + 20V Made in Example 1. The results of setting the stress conditions of the field-effect transistor to Vgs = +20 and Vds = 0V are shown in FIG. 11, and the results of setting the stress condition Vgs = Vds = +20 are shown in FIG. Further, FIG. 13 shows the results when the stress conditions Vgs = +20 and Vds = 0V of the field-effect transistor produced in Comparative Example 1, and FIG. 14 shows the results when the stress condition Vgs = Vds = +20. Here, "E" on the vertical axis of the graphs of FIGS. 11 to 14 represents a power of 10. For example, "1.E-03" represents "1 × ^{10 -3"} and "0.001", "1.E-05" represents "1 × ^{10 -5"} and "0.00001".
Here, the rising voltage Von of the transistor characteristics is defined as the voltage immediately before the Ids exceeds ^10-11 A when Vg is increased from -20 V in steps of 0.5 V.
Focusing on the shift amount ΔVon of the rising voltage Von during the stress test for 160 hours, it is + 1.0 V in FIG. 11 and + 1.5 V in the graph of FIG. 12, whereas it is + 8.0 V in the graph of FIG. In the graph of 14, it is + 7.5V. Here, Table 16 shows the results of ΔVon when the field effect transistors manufactured in Examples 1 to 16 and Comparative Example 1 were subjected to a stress test for 160 hours. From Table 16, a clear superiority difference was confirmed between Examples 1 to 18 and Comparative Example 1. That is, it was found that the field-effect transistor produced in Examples 1 to 18 is more suitable as a protective layer for the semiconductor layer (particularly, the oxide semiconductor layer) than the field-effect transistor produced in Comparative Example 1. ..
In addition, the field effect transistors produced in Examples 1 to 18 showed good reliability even in the atmosphere.

(Example 19)
<Manufacturing of organic EL display device>
An organic EL display device as shown in FIG. 15 was manufactured.

-Formation of gate electrode-
First, the first gate electrode 52 and the second gate electrode 53 were formed on the glass substrate 51. Specifically, an ITO film as a transparent conductive film was formed on the glass substrate 51 by DC sputtering so that the average film thickness was about 100 nm. After that, a photoresist was applied, and a resist pattern similar to the pattern of the first gate electrode 52 and the second gate electrode 53 formed by prebaking, exposure by an exposure apparatus, and development was formed. Further, the ITO film in the region where the resist pattern was not formed was removed by RIE. After that, the resist pattern was also removed to form the first gate electrode 52 and the second gate electrode 53.

-Formation of gate insulating layer-
Next, the gate insulating layer 54 was formed. Specifically, an Al ₂ O ₃ film was formed on the first gate electrode 52, the second gate electrode 53, and the glass substrate 51 by RF sputtering so that the average film thickness was about 300 nm. After that, a photoresist was applied to form a resist pattern similar to the pattern of the gate insulating layer 54 formed by prebaking, exposure with an exposure apparatus, and development. Further, the Al ₂ O ₃ film in the region where the resist pattern was not formed was removed by RIE, and then the resist pattern was also removed to form the gate insulating layer 54.

-Formation of source and drain electrodes-
Next, the first source electrode 55 and the second source electrode 57, and the first drain electrode 56 and the second drain electrode 58 were formed. Specifically, an ITO film as a transparent conductive film is formed on the gate insulating layer 54 by DC sputtering so that the average thickness is about 100 nm, and then a photoresist is applied on the ITO film. A resist pattern similar to that of the first source electrode 55 and the second source electrode 57, and the first drain electrode 56 and the second drain electrode 58 formed by prebaking, exposure by an exposure apparatus, and development is performed. Formed. Further, the ITO film in the region where the resist pattern was not formed was removed by RIE. After that, the resist pattern was also removed to form the first source electrode 55 and the second source electrode 57 made of the ITO film, and the first drain electrode 56 and the second drain electrode 58.

-Formation of oxide semiconductor layer-
Next, the first oxide semiconductor layer 59 and the second oxide semiconductor layer 60 were formed. Specifically, a Mg—In oxide (In ₂ MgO ₄ ) film was formed by DC sputtering so that the average film thickness was about 100 nm. After that, a photoresist is applied onto the Mg-In oxide film, and the first oxide semiconductor layer 59 and the second oxide semiconductor layer 60 are formed by prebaking, exposure with an exposure apparatus, and development. A resist pattern similar to that of the above was formed. Further, the Mg-In oxide film in the region where the resist pattern was not formed was removed by RIE. After that, the resist pattern was also removed to form the first oxide semiconductor layer 59 and the second oxide semiconductor layer 60. As a result, the first oxide semiconductor layer 59 was formed so that a channel was formed between the first source electrode 55 and the first drain electrode 56. Further, the second oxide semiconductor layer 60 was formed so that a channel was formed between the second source electrode 57 and the second drain electrode 58.

-Formation of protective layer-
Next, the first protective layer 61 and the second protective layer 62 were formed.
First, in the amount of Example 1 shown in Table 1, tetrabutoxysilane (T5702-100G, manufactured by Aldrich), aluminum di (s-butoxide) acetoacetic ester chelate (Al content 8.4%, Alfa89349, Alfa Aesar). , Triisopropyl borate (Wako 320-41532, manufactured by Wako Chemical Industries, Ltd.), calcium 2-ethylhexanoate mineral spirit solution (Ca content 5%, 351-01162, manufactured by Wako Chemical Industries, Ltd.), and 2- A strontium toluene ethylhexanoate solution (Sr content 2%, 195-09561, manufactured by Wako Pure Chemical Industries, Ltd.) was diluted in mesitylene to obtain a coating solution for forming a protective layer. The composite metal oxide formed by the coating liquid for forming a protective layer has the composition of Example 1 shown in Table 2.
Using the coating liquid for forming a protective layer, a protective layer was coated and formed so as to cover the first oxide semiconductor layer 59 and the second oxide semiconductor layer 60 by an inkjet method. Subsequently, after a drying treatment at 120 ° C. for 1 hour in the air, firing was performed at 400 ° C. for 3 hours in an O ₂ atmosphere. Then, to obtain a _{SiO 2 -A 2 O 3 -B 2} O 3 -CaO-SrO composite metal oxide insulating film as a first protective layer 61 and second protective layer 62 (protective layer). The average film thickness of the first protective layer 61 and the second protective layer 62 was about 30 nm.

-Formation of interlayer insulating film-
Next, the interlayer insulating film 63 was formed. Specifically, a positive photosensitive organic material (Sumiresin Excel CRC series, manufactured by Sumitomo Bakelite Co., Ltd.) was applied by spin coating, and a desired pattern was obtained by prebaking, exposure with an exposure apparatus, and development. Then, by post-baking at 320 ° C. for 30 minutes, an interlayer insulating film 63 having a through hole was formed on the second drain electrode 58. The average film thickness of the interlayer insulating film 63 formed in this way was about 3 μm. No peeling was observed in the protective layers 61 and 62 even after the post-baking of the interlayer insulating film 63.

-Formation of partition wall-
Next, the partition wall 64 was formed. Specifically, the surface of the interlayer insulating film 63 was modified by UV ozone treatment. Then, a positive photosensitive polyimide resin (DL-1000, manufactured by Toray Industries, Inc.) was applied by spin coating, and a desired pattern was obtained by prebaking, exposure with an exposure apparatus, and development. Then, the partition wall 64 was formed by post-baking at 230 ° C. for 30 minutes.

-Formation of anode-
Next, the anode 65 was formed. Specifically, after the surface of the interlayer insulating film 63 was modified again by UV ozone treatment, an anode 65 having an average film thickness of about 50 nm was formed by inkjet using nanoparticulate ITO ink.

-Formation of organic EL layer-
Next, using a polymer organic light emitting material, an organic EL layer 66 was formed on the anode 65 by an inkjet device.

-Cathode formation-
Next, the cathode 67 was formed. Specifically, the cathode 67 was formed on the organic EL layer 66 and the partition wall 64 by vacuum-depositing MgAg.

-Formation of sealing layer-
Next, the sealing layer 68 was formed. Specifically, by depositing so that SiN _X film average thickness of about 2μm by PECVD, to form a sealing layer 68 on the cathode 67.

-Lasting-
Next, the bonding with the facing substrate 70 was performed. Specifically, an adhesive layer 69 was formed on the sealing layer 68, and an opposing substrate 70 made of a glass substrate was bonded. As a result, a display panel of the organic EL display device having the configuration shown in FIG. 15 was produced.

-Drive circuit connection-
Next, the drive circuit was connected. Specifically, a drive circuit (not shown) is connected to the display panel so that an image can be displayed on the display panel. As a result, an image display system for an organic EL display device was produced.

This organic EL display device is a so-called "bottom emission" type organic EL display device because the field effect transistor is formed of a transparent film in all layers and only the cathode uses a metal layer with high reflectance. ..
This organic EL display device showed high-speed operation and high reliability.

Aspects of the present invention are, for example, as follows.
<1> Base material and
With a protective layer,
A gate insulating layer formed between the base material and the protective layer,
A source electrode and a drain electrode formed so as to be in contact with the gate insulating layer,
A semiconductor layer formed between at least the source electrode and the drain electrode and in contact with the gate insulating layer, the source electrode, and the drain electrode.
It has a gate electrode formed on the side opposite to the semiconductor layer with the gate insulating layer interposed therebetween and in contact with the gate insulating layer.
The protective layer is a field-effect transistor characterized by containing a composite metal oxide containing at least Si and an alkaline earth metal.
<2> The field-effect transistor according to <1>, wherein the composite metal oxide contains at least one of Al and B.
<3> The field-effect transistor according to any one of <1> to <2>, wherein the semiconductor layer is an oxide semiconductor layer.
<4> The field-effect transistor according to any one of <1> to <3>, wherein the alkaline earth metal is at least one of Mg, Ca, Sr, and Ba.
<5> An optical control element whose optical output is controlled according to a drive signal,
The display element is characterized by having the field effect transistor according to any one of <1> to <4> and having a drive circuit for driving the optical control element.
<6> The display element according to <5>, wherein the optical control element has any one of an electroluminescence element, an electrochromic element, a liquid crystal element, an electrophoresis element, and an electrowetting element.
<7> An image display device that displays an image according to image data.
The display element according to any one of <5> to <6> arranged in a matrix, and
A plurality of wirings for individually applying a gate voltage to each field effect transistor in the plurality of display elements, and
The image display device is characterized by having a display control device that individually controls the gate voltage of each field effect transistor according to the image data via the plurality of wirings.
<8> The image display device according to <7> and
The system is characterized by having an image data creation device that creates image data based on the image information to be displayed and outputs the image data to the image display device.

11 Electric field effect transistor 12 Electric field effect transistor 13 Capitol 14 Electric field effect transistor 15 Capsule 16 Opposite electrode 21 Base material 22 Gate electrode 23 Gate insulation layer 24 Source electrode 25 Drain electrode 26 Oxide semiconductor layer 27 Protective layer 31 Base material 32 First Gate Electrode 33 Second Gate Electrode 34 Gate Insulation Layer 35 First Source Electrode 36 Second Source Electrode 37 First Drain Electrode 38 Second Drain Electrode 39 First Oxide Semiconductor Layer 40 Second Oxide semiconductor layer 41 First protective layer 42 Second protective layer 43 Interlayer insulating film 44 Organic EL layer 45 Cone 51 Glass substrate 52 First gate electrode 53 Second gate electrode 54 Gate insulating layer 55 First Source electrode 56 First drain electrode 57 Second source electrode 58 Second drain electrode 59 First oxide semiconductor layer 60 Second oxide semiconductor layer 61 First protective layer 62 First protective layer 63 Interlayer Insulation film 64 partition wall 65 anode 66 organic EL layer 67 cathode 68 sealing layer 69 adhesive layer 70 facing substrate 81 glass substrate 82 lower electrode 83 dielectric layer 84 upper electrode 302, 302'display element 310 display 312 cathode 314 anode 320, 320' Drive circuit (drive circuit)
340 Organic EL thin film layer 342 Electron transport layer 344 Light emitting layer 346 Hole transport layer 350 Organic EL element 370 Liquid crystal element 372 Opposite electrode 400 Display control device 402 Image data processing circuit 404 Scanning line drive circuit 406 Data line drive circuit

Japanese Unexamined Patent Publication No. 2008-205469 JP-A-2010-103203 JP-A-2007-299913 Japanese Unexamined Patent Publication No. 2010-182819 Japanese Unexamined Patent Publication No. 2011-77515 Japanese Unexamined Patent Publication No. 2011-222788

K. Nomura, 5 others, "Room-temperature fabrication of semiconductor flexible thin-film transistor", NATURE, VOL, NATURE, VOL. 25, NOVEMBER, 2004, p. 488-492

Claims (9)

With the base material
With a protective layer,
A gate insulating layer formed between the base material and the protective layer,
A semiconductor layer in contact with the gate insulating layer and
It has a gate electrode formed on the side opposite to the semiconductor layer with the gate insulating layer interposed therebetween and in contact with the gate insulating layer.
The protective layer contains a composite metal oxide containing at least Si, an alkaline earth metal, and Al.
The ratio of the Al in the composite metal oxide is the oxide (Al). ₂ O ₃ ) Converted to 1.0 mol% to 50.0 mol%, a field-effect transistor. The ratio of the Al in the composite metal oxide is the oxide (Al). ₂ O ₃ ). The field effect transistor according to claim 1, which is 5.0 mol% to 30.0 mol% in terms of conversion. With the base material
With a protective layer,
A gate insulating layer formed between the base material and the protective layer,
A semiconductor layer in contact with the gate insulating layer and
It has a gate electrode formed on the side opposite to the semiconductor layer with the gate insulating layer interposed therebetween and in contact with the gate insulating layer.
The protective layer contains a composite metal oxide containing at least Si and an alkaline earth metal.
The alkaline earth metal contains at least one of Ca and Sr.
A field-effect transistor characterized in that the ratio of Ca and Sr in the composite metal oxide is 5.0 mol% to 40.0 mol% in terms of oxides (CaO, SrO). With the base material
With a protective layer,
A gate insulating layer formed between the base material and the protective layer,
A semiconductor layer in contact with the gate insulating layer and
It has a gate electrode formed on the side opposite to the semiconductor layer with the gate insulating layer interposed therebetween and in contact with the gate insulating layer.
The protective layer contains a composite metal oxide containing at least Si and an alkaline earth metal.
A field-effect transistor characterized in that the proportion of the alkaline earth metal in the composite metal oxide is 10.0 mol% to 30.0 mol% in terms of oxide. The field-effect transistor according to any one of claims 1 to 4, wherein the semiconductor layer is an oxide semiconductor layer. An optical control element whose optical output is controlled according to a drive signal,
A display element having the field effect transistor according to any one of claims 1 to 5, and having a drive circuit for driving the optical control element. The display element according to claim 6, wherein the optical control element includes any one of an electroluminescence element, an electrochromic element, a liquid crystal element, an electrophoresis element, and an electrowetting element. An image display device that displays an image according to the image data.
The display element according to any one of claims 6 to 7, which is arranged in a matrix.
A plurality of wirings for individually applying a gate voltage to each field effect transistor in the plurality of display elements, and
An image display device including a display control device that individually controls the gate voltage of each field effect transistor according to the image data via the plurality of wirings. The image display device according to claim 8 and
A system characterized by having an image data creating device that creates image data based on the image information to be displayed and outputs the image data to the image display device.