JP6642657B2 - Field effect transistor, display element, image display device, and system - Google Patents

Description

  The present invention relates to a field effect transistor, a display device, an image display device, and a system.

  2. Description of the Related Art A field effect transistor (FET) is based on the principle that an electric field is applied to a gate electrode and a gate (gate) is formed between electrons and holes by the electric field of a channel. Is a transistor that controls

  The FET is used as a switching element, an amplification element, and the like because of its characteristics. In addition, since the FET has a low gate current and a planar structure, it can be easily manufactured and integrated as compared with a bipolar transistor. Therefore, the FET is an indispensable element in an integrated circuit used in current electronic devices. The FET is applied to, for example, an active matrix display as a thin film transistor (TFT).

  In recent years, liquid crystal displays, organic EL (electroluminescence) displays, electronic papers, and the like have been put to practical use as flat panel displays (Flat Panel Displays: FPDs).

  These FPDs are driven by a drive circuit including a TFT using amorphous silicon, polycrystalline silicon, or the like as an active layer. The FPD is required to have a larger size, a higher definition, a higher image quality, and a high-speed driving property. Accordingly, the FPD has a high carrier mobility, a high on / off ratio, and a characteristic change with time. There is a need for a TFT that is small and has small variations between elements.

However, amorphous silicon and polycrystalline silicon have advantages and disadvantages, and it has been difficult to satisfy all the above requirements. Therefore, in order to meet these demands, active development of TFTs using an oxide semiconductor, which can be expected to have a mobility higher than that of amorphous silicon, as an active layer is being actively conducted. For example, a TFT using InGaZnO ₄ for a semiconductor layer is disclosed (for example, see Non-Patent Document 1).

The TFT is required to have a small variation in threshold voltage.
One of the factors that change the threshold voltage of the TFT is that moisture, hydrogen, oxygen, and the like contained in the air are adsorbed to and desorbed from the semiconductor layer. Therefore, the TFT has a protective layer for the purpose of protecting the semiconductor layer from moisture, hydrogen, oxygen, and the like contained in the air.
Also, the threshold voltage fluctuates even when the TFT repeatedly turns on and off for a long time and many times. A BTS (Bias Stress Temperature) test is widely performed as a method of evaluating the fluctuation of the threshold voltage in such a long-time and many-time driving. In this test, a voltage is applied between the gate electrode and the source electrode of the field-effect transistor for a certain period of time, and a change in the threshold voltage at that time is evaluated. Is a method of continuously applying a voltage for a certain period of time and evaluating a change in the threshold voltage at that time.
Several protective layers have been disclosed to suppress the variation of the threshold voltage of the TFT. For example, a field effect transistor using SiO ₂ , Si ₃ N ₄ , or SiON as a protective layer is disclosed (for example, see Patent Document 1). It is reported that the field-effect transistor having the protective layer formed thereon can operate stably without being affected by the atmosphere such as vacuum and air. However, no data on the BTS test was disclosed.
Further, a field effect transistor using Al ₂ O ₃ , AlN, or AlON as a protective layer is disclosed (for example, see Patent Document 2). It is reported that the field-effect transistor having the protective layer formed thereon can suppress fluctuations in transistor characteristics by preventing impurities such as moisture and oxygen from entering the semiconductor layer. However, no data on the BTS test was disclosed.
Further, a field effect transistor using a laminated film containing Al ₂ O ₃ and SiO ₂ as a protective layer is disclosed (for example, see Patent Document 3). It is reported that in a field-effect transistor using this laminated film as a protective layer, the incorporation and adsorption of moisture into the semiconductor layer is suppressed, and the transistor characteristics do not change even after a storage test in a high-temperature, high-humidity environment. However, no data on the BTS test was disclosed.
Further, a field-effect transistor in which a single-layer film of SiO ₂ , Ta ₂ O ₅ , TiO ₂ , HfO ₂ , ZrO ₂ , Y ₂ O ₃ , or Al ₂ O ₃ or a stacked film thereof is used as a protective layer is disclosed. (For example, see Patent Document 4). It is reported that a field-effect transistor having such a protective layer formed thereon can suppress desorption of oxygen from an oxide semiconductor and can improve reliability. However, no data on the BTS test was disclosed.
Further, a field-effect transistor using Al ₂ O ₃ as a protective layer is disclosed (for example, see Non-Patent Document 2). With respect to the field-effect transistor having the protective layer formed thereon, the results of reliability evaluation by a BTS test have been reported. However, the amount of change in threshold voltage (ΔVth) with respect to the passage of stress time is large, and the reliability of the field-effect transistor is high. Not enough.
Further, in any of the above-mentioned technologies, the reliability evaluation in the BTS test cannot be said to be sufficient.

  Therefore, at present, it is required to provide a field-effect transistor having a small variation in threshold voltage with respect to the BTS test and exhibiting high reliability.

  An object of the present invention is to solve the above-described various problems in the related art and achieve the following objects. That is, an object of the present invention is to provide a field-effect transistor that exhibits a small amount of change in threshold voltage with respect to a BTS (Bias Stress Temperature) test and exhibits high reliability.

The means for solving the above problems are as follows. That is,
The field effect transistor of the present invention,
A substrate,
A protective layer,
The base material, and a gate insulating layer formed between the protective layer,
A source electrode and a drain electrode formed to be in contact with the gate insulating layer;
A semiconductor layer formed at least between the source electrode and the drain electrode and in contact with the gate insulating layer, the source electrode, and the drain electrode;
A gate electrode in contact with the gate insulating layer and facing the semiconductor layer via the gate insulating layer;
The protective layer is formed in contact with the first protective layer containing a first composite metal oxide containing Si and an alkaline earth metal, and the first protective layer. And a second protective layer containing a second composite metal oxide containing a rare earth element.

  According to the present invention, it is possible to solve the above-mentioned various problems in the related art, and to provide a field-effect transistor having small variation in threshold voltage with respect to a BTS test 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 illustrating an example of the organic EL element. FIG. 5 is a schematic configuration diagram illustrating 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 the 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 graph showing an evaluation of transistor characteristics (Vgs-Ids) in a BTS test of the field-effect transistor obtained in Example 12 at Vgs = + 20 V and Vds = 0 V. FIG. 11 is a graph showing an evaluation of transistor characteristics (Vgs-Ids) in a BTS test of Vgs = + 20 V and Vds = + 20 V for the field-effect transistor obtained in Example 12. FIG. 12 is a graph showing an evaluation of transistor characteristics (Vgs-Ids) of the field-effect transistor obtained in Example 12 in a BTS test at Vgs = −20 V and Vds = 0 V. FIG. 13 is a graph showing an evaluation of transistor characteristics (Vgs-Ids) in a BTS test of Vgs = −20 V and Vds = + 20 V of the field-effect transistor obtained in Example 12. FIG. 14 is a graph showing an evaluation of a stress time change of ΔVth in a BTS test of Vgs = + 20 V and Vds = 0 V of the field-effect transistors obtained in Example 12 and Comparative Example 8. FIG. 15 is a schematic diagram of the field-effect transistors manufactured in Examples 1 to 16 and Comparative Examples 4 and 7.

(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. Having.

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

<Protective layer>
The protective layer is usually formed above the substrate.
The protective layer has a first protective layer and a second protective layer formed in contact with the first protective layer.
The arrangement of the first protective layer and the second protective layer in the protective layer is not particularly limited and may be appropriately selected depending on the intended purpose. The second protective layer may be disposed closer to the substrate than the second protective layer, or the second protective layer may be disposed closer to the substrate than the first protective layer. Further, the second protective layer may be disposed so as to cover an upper surface and a side surface of the first protective layer, or the first protective layer may be disposed so as to cover an upper surface and a side surface of the second protective layer. May be arranged.

-First protective layer-
The first protective layer contains a first composite metal oxide.
It is preferable that the first protective layer is formed of the first composite metal oxide itself.

--- First composite metal oxide--
The first composite metal oxide contains Si (silicon) and an alkaline earth metal, and preferably contains at least one of Al (aluminum) and B (boron). , And other components.

In the first composite metal oxide, the SiO ₂ formed by the 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 dielectric constant and the coefficient of linear expansion of the first composite metal oxide to be formed by the composition ratio of the Si and the alkaline earth metal.

It is preferable that the first composite metal oxide contains at least one of Al and B. Since Al ₂ O ₃ formed by Al and B ₂ O ₃ formed by B form an amorphous structure similarly to SiO ₂ , the first composite metal oxide is more stable. Thus, an amorphous structure can be obtained, and a more uniform insulating film can be formed. Further, since the alkaline earth metal changes the coordination structure of Al and B according to the composition ratio, it is possible to control the relative dielectric constant and the coefficient of linear expansion of the first composite metal oxide to be formed. It is possible.

  In the first composite metal oxide, examples of the alkaline earth metal include Be (beryllium), Mg (magnesium), Ca (calcium), Sr (strontium), and Ba (barium). These may be used alone or in combination of two or more.

The composition ratio of the Si and the alkaline earth metal in the first composite metal oxide is not particularly limited and may be appropriately selected depending on the intended purpose, but is preferably within the following range. .
In the first composite metal oxide, the composition ratio of the Si and the alkaline earth metal (the Si: the alkaline earth metal) may be an oxide (SiO ₂ , BeO, MgO, CaO, SrO, In terms of BaO), the content is preferably 50.0 mol% to 90.0 mol%: 10.0 mol% to 50.0 mol%.

The composition ratio of the Si, the alkaline earth metal, and at least one of Al and B in the first composite metal oxide is not particularly limited, and can be appropriately selected depending on the purpose. Is preferably in the following range.
In the first composite metal oxide, a composition ratio of the Si, the alkaline earth metal, and at least one of the Al and the B (the Si: the alkaline earth metal: at least the Al and the B Any) as oxides (SiO ₂ , BeO, MgO, CaO, SrO, BaO, Al ₂ O ₃ , B ₂ O ₃ ) in terms of 50.0 mol% to 90.0 mol%: 5.0 mol% to 20.0 mol%: 5.0 mol% to 30.0 mol% is preferable.

The ratio of the oxides (SiO ₂ , BeO, MgO, CaO, SrO, BaO, Al ₂ O ₃ , B ₂ O ₃ ) in the first composite metal oxide is determined, for example, by fluorescent X-ray analysis and electron beam microanalysis. It can be calculated by analyzing the cation element of the oxide by (EPMA), inductively coupled plasma emission spectroscopy (ICP-AES) or the like.

The relative permittivity of the first protective layer is not particularly limited, and can be appropriately selected depending on the purpose.
The relative dielectric constant can be measured, for example, by preparing a capacitor in which a lower electrode, a dielectric layer (the protective layer), and an upper electrode are stacked, and using an LCR meter or the like.

The linear expansion coefficient of the first protective layer is not particularly limited and can be appropriately selected depending on the purpose.
The linear expansion coefficient can be measured using, for example, a thermomechanical analyzer. In this measurement, the linear expansion coefficient can be measured by separately preparing and measuring a measurement sample having the same composition as the protective layer without manufacturing the field-effect transistor.

-Second protective layer-
The second protective layer contains a second composite metal oxide.
The second protective layer is preferably formed of the second composite metal oxide itself.

--- Second composite metal oxide--
The second composite metal oxide contains at least an alkaline earth metal and a rare earth element, and preferably contains at least one of Zr (zirconium) and Hf (hafnium). Contains other components.

The second composite metal oxide is stable in the air and can form an amorphous structure stably in a wide composition range. This is because the inventors have found that a composite metal oxide system containing an alkaline earth metal and a rare earth element is stable in the air and can form an amorphous structure stably in a wide composition range. Find out what you can do.
In general, simple oxides of alkaline earth metals easily react with atmospheric moisture and carbon dioxide, easily form hydroxides and carbonates, and are not suitable for application to electronic devices by themselves. . Further, a simple oxide of a rare earth element is easily crystallized, and a leak current poses a problem when applied to an electronic device. However, the present inventors have found that the second composite metal oxide containing an alkaline earth metal and a rare earth element stably forms an amorphous film in a wide composition range. Since the second composite metal oxide is stably present in a wide composition range, the composition ratio of the second composite metal oxide controls the relative permittivity and the linear expansion coefficient of the formed second composite metal oxide in a wide range. can do.

  It is preferable that the second composite metal oxide contains at least one of Zr (zirconium) and Hf (hafnium). When the second composite metal oxide contains at least one of Zr and Hf, thermal stability, heat resistance, and denseness can be further improved.

  In the second composite metal oxide, examples of the alkaline earth metal include Be (beryllium), Mg (magnesium), Ca (calcium), Sr (strontium), and Ba (barium). These may be used alone or in combination of two or more.

  In the second composite metal oxide, Sc (scandium), Y (yttrium), La (lanthanum), Ce (cerium), Pr (praseodymium), Nd (neodymium), Pm (promethium), Sm (samarium), Eu (europium), Gd (gadolinium), Tb (terbium), Dy (dysprosium), Ho (holmium), Er (erbium), Tm (thulium), Yb (ytterbium), Lu (lutetium) No.

The composition ratio of the alkaline earth metal and the rare earth element in the second composite metal oxide is not particularly limited and may be appropriately selected depending on the intended purpose. preferable.
In the second composite metal oxide, a composition ratio of the alkaline earth metal and the rare earth element (the alkaline earth metal: the rare earth element) is an oxide (BeO, MgO, CaO, SrO, BaO). , Sc ₂ O ₃ , Y ₂ O ₃ , La ₂ O ₃ , Ce ₂ O ₃ , Pr ₂ O ₃ , Nd ₂ O ₃ , Pm ₂ O ₃ , Sm ₂ O ₃ , Eu ₂ O ₃ , Gd ₂ O ₃ , Tb ₂ O ₃ , Dy ₂ O ₃ , Ho ₂ O ₃ , Er ₂ O ₃ , Tm ₂ O ₃ , Yb ₂ O ₃ , Lu ₂ O ₃ ) in terms of 10.0 mol% to 67.0 mol%: 33 0.0 mol%-90.0 mol% are preferable.

The composition ratio of the alkaline earth metal, the rare earth element, and at least one of Zr and Hf in the second composite metal oxide is not particularly limited and may be appropriately selected depending on the purpose. Although it is possible, it is preferable to be within the following range.
In the second composite metal oxide, a composition ratio of the alkaline earth metal, the rare earth element, and at least one of Zr and Hf (the alkaline earth metal: the rare earth element: the Zr and the Hf At least as one) of oxide _{(BeO, MgO, CaO, SrO} , BaO, Sc 2 O 3, Y 2 O 3, La 2 O 3, Ce 2 O 3, Pr 2 O 3, Nd 2 O 3 _{, Pm 2 O 3, Sm 2} O 3, Eu 2 O 3, Gd 2 O 3, Tb 2 O 3, Dy 2 O 3, Ho 2 O 3, Er 2 O 3, Tm 2 O 3, Yb 2 O 3 , Lu ₂ O ₃ , ZrO ₂ , HfO ₂ ), preferably 5.0 mol% to 22.0 mol%: 33.0 mol% to 90.0 mol: 5.0 mol% to 45.0 mol%.

The second oxide in the composite metal oxide _{(BeO, MgO, CaO, SrO} , BaO, Sc 2 O 3, Y 2 O 3, La 2 O 3, Ce 2 O 3, Pr 2 O 3, Nd 2 O _{3, Pm 2 O 3, Sm} 2 O 3, Eu 2 O 3, Gd 2 O 3, Tb 2 O 3, Dy 2 O 3, Ho 2 O 3, Er 2 O 3, Tm 2 O 3, Yb 2 O ₃ , Lu ₂ O ₃ , ZrO ₂ , HfO ₂ ) can be determined by, for example, X-ray fluorescence analysis, electron beam micro analysis (EPMA), or inductively coupled plasma emission spectroscopy (ICP-AES). It can be calculated by analyzing the elements.

The relative permittivity of the second protective layer is not particularly limited, and can be appropriately selected depending on the purpose.
The relative permittivity of the second protective layer can be measured, for example, by the same method as the relative permittivity of the first protective layer.

The linear expansion coefficient of the second protective layer is not particularly limited and can be appropriately selected depending on the purpose.
The linear expansion coefficient of the second protective layer can be measured, for example, by the same method as the linear expansion coefficient of the first protective layer.

In the present invention, the present inventors laminate the first protective layer containing the first composite metal oxide and the second protective layer containing the second composite metal oxide. As a result, it was found that the formed protective layer exhibited excellent barrier properties against moisture, oxygen and hydrogen in the atmosphere.
Therefore, by using the protective layer, a field-effect transistor exhibiting high reliability can be provided.

-Method of forming first protective layer and second protective layer-
The method for forming the first protective layer and the second protective layer is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include a sputtering method, a pulsed laser deposition (PLD) method, After film formation by a vacuum process such as a chemical vapor deposition (CVD) method or an atomic layer deposition (ALD) method, a method of patterning by photolithography and the like can be given.
In addition, the first protective layer is prepared by preparing a coating solution containing a precursor of the first composite metal oxide (a coating solution for forming a first protective layer) and applying it on an object to be coated. A film can also be formed by printing and firing this under appropriate conditions. Similarly, the second protective layer is prepared by preparing a coating solution containing the precursor of the second composite metal oxide (a coating solution for forming a second protective layer), and applying it on an object to be coated. Alternatively, a film can be formed by printing and baking it under appropriate conditions.

The average thickness of the first protective layer is preferably from 10 nm to 1,000 nm, more preferably from 20 nm to 500 nm.
The average thickness of the second protective layer is preferably from 10 nm to 1,000 nm, more preferably from 20 nm to 500 nm.

--- First protective layer forming coating liquid (first insulating film forming coating liquid) ---
The first protective layer forming coating solution (first insulating film forming coating solution) contains at least a silicon-containing compound, an alkaline earth metal compound, and a solvent, preferably an aluminum-containing compound, and It contains at least one of the boron-containing compounds, and further contains other components as necessary.

  2. Description of the Related Art In recent years, the development of printed electronics using a coating process that can reduce the cost of a vacuum process that requires expensive equipment such as a sputtering method, a CVD method, and a dry etching method has been activated. Regarding the protective layer of a semiconductor, studies have been made to form the protective layer by coating using polysilazane (for example, see JP-A-2010-103203), spin-on-glass, or the like.

However, a coating solution composed of only a SiO ₂ precursor such as polysilazane or spin-on-glass requires baking at 450 ° C. or more in order to decompose organic substances and obtain a dense insulating film. In order to decompose organic substances at a temperature lower than that, other than heating such as microwave treatment (see, for example, JP-A-2010-103203), use of a catalyst, and calcination in a steam atmosphere (Japanese Patent No. 3666915). It is indispensable to use a reaction promoting means in combination. For this reason, there are problems in that the firing process is complicated, the cost is high, and the insulating property is reduced due to the remaining impurities. On the other hand, the first protective layer forming coating solution contains a precursor of an alkaline earth metal oxide having a lower decomposition temperature than that of the SiO ₂ precursor, so that the first protective layer forming coating solution has a lower decomposition temperature than the coating solution containing only the SiO ₂ precursor. The precursor can be decomposed at a low temperature, that is, a temperature lower than 450 ° C., and a dense insulating film can be formed. In addition, as with the precursor of the alkaline earth metal oxide, at least one of an Al ₂ O ₃ precursor and a B ₂ O ₃ precursor having a decomposition temperature lower than that of the SiO ₂ precursor is further included, so that a compact at low temperature can be obtained. The effect of forming an insulating film can be enhanced.

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

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

  The organic silicon 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 purpose. The silicon and the organic group are bonded by, for example, an ionic bond, a covalent bond, or a coordinate bond.

  The organic group is not particularly limited and may be appropriately selected depending on the purpose. Examples thereof include an alkyl group which may have a substituent, an alkoxy group which may have a substituent, and 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), bis (trimethylsilyl) Examples include acetylene, triphenylsilane, silicon 2-ethylhexanoate, and tetraacetoxysilane.

  The content of the silicon-containing compound in the first protective layer forming coating solution is not particularly limited, and can be appropriately selected depending on the purpose.

--- Alkaline earth metal-containing compound ---
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 an alkaline earth metal nitrate, an alkaline earth metal sulfate, an alkaline earth metal chloride, an alkaline earth metal fluoride, an alkaline earth metal bromide, and an alkaline earth metal. And the like.
Examples of the alkaline earth metal nitrate include magnesium nitrate, calcium nitrate, strontium nitrate, and barium nitrate.
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, and barium fluoride.
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, and barium iodide.

  The organic alkaline earth metal compound is not particularly limited as long as it has an alkaline earth metal and an organic group, and can be appropriately selected according to the purpose. The alkaline earth metal and the organic group are bonded by, for example, an ionic bond, a covalent bond, or a coordinate bond.

  The organic group is not particularly limited and may be appropriately selected depending on the purpose. Examples thereof include an alkyl group which may have a substituent, an alkoxy group which may have a substituent, and a substituent. An acyloxy group which may have a 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. No. 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, an acyloxy group partially substituted with a hydroxy group such as lactic acid, Examples include an acyloxy group having two or more carbonyl groups such as oxalic acid and citric acid.

  Examples of the organic alkaline earth metal compound include, for example, magnesium methoxide, magnesium ethoxide, diethyl magnesium, magnesium acetate, magnesium formate, magnesium acetylacetone, magnesium 2-ethylhexanoate, magnesium lactate, magnesium naphthenate, magnesium citrate, Magnesium salicylate, magnesium benzoate, magnesium oxalate, magnesium trifluoromethanesulfonate, calcium methoxide, calcium ethoxide, calcium acetate, calcium formate, calcium acetylacetone, calcium dipivaloyl methanate, 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, strontium naphthenate, strontium salicylate, strontium oxalate, barium ethoxide, barium isoate Propoxide, barium acetate, barium formate, barium acetylacetonate, barium 2-ethylhexanoate, barium lactate, barium naphthenate, barium neodecanoate, barium oxalate, barium benzoate, barium trifluoromethanesulfonate, and the like.

  The content of the alkaline earth metal-containing compound in the first protective layer forming coating solution is not particularly limited and can be appropriately selected depending on the purpose.

--- Aluminum-containing compound ---
Examples of the aluminum-containing compound include an inorganic aluminum compound and an organic aluminum compound.

  Examples of the inorganic aluminum compound include aluminum chloride, aluminum nitrate, aluminum bromide, aluminum hydroxide, aluminum borate, aluminum trifluoride, aluminum iodide, aluminum sulfate, aluminum phosphate, and aluminum ammonium 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 purpose. The aluminum and the organic group are bonded by, for example, an ionic bond, a covalent bond, or a coordinate bond.

  The organic group is not particularly limited and may be appropriately selected depending on the purpose. Examples thereof include an alkyl group which may have a substituent, an alkoxy group which may have a substituent, and a substituent. And an acetylacetonate group which may have a substituent, a sulfonic acid group which may have a substituent, and the like. 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, an acyloxy group partially substituted with a hydroxy group such as lactic acid, Examples include an acyloxy group having two or more carbonyl groups such as oxalic acid and citric acid.

  Examples of the organoaluminum compound include aluminum isopropoxide, aluminum-sec-butoxide, triethylaluminum, diethylaluminum ethoxide, aluminum acetate, aluminum acetylacetone, aluminum hexafluoroacetylacetonate, aluminum 2-ethylhexanoate, aluminum lactate, and aluminum lactate. Aluminum benzoate, aluminum di (s-butoxide) acetoacetate chelate, aluminum trifluoromethanesulfonate and the like can be mentioned.

  The content of the aluminum-containing compound in the first protective layer forming coating solution is not particularly limited and can be appropriately selected depending on the 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, and magnesium borate. 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 purpose. The boron and the organic group are bonded by, for example, an ionic bond, a covalent bond, or a coordinate bond.

  The organic group is not particularly limited and may be appropriately selected depending on the purpose. Examples thereof include an alkyl group which may have a substituent, an alkoxy group which may have a substituent, and a substituent. And an optionally substituted acyloxy group, an optionally substituted phenyl group, an optionally substituted sulfonic acid group, and an optionally substituted thiophene group. . 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 of the two or more oxygen atoms are bonded to boron and form an organic ring structure together with boron. Groups are also included. Further, an alkoxy group in which an alkyl group contained in the alkoxy group is substituted with an organic silyl group is also included. Examples of the acyloxy group include an acyloxy group having 1 to 10 carbon atoms.

  Examples of the organic boron compound include (R) -5,5-diphenyl-2-methyl-3,4-propano-1,3,2-oxazaborolidine, triisopropyl borate, and 2-isopropoxy- 4,4,5,5-tetramethyl-1,3,2-dioxaborolane, bis (hexyleneglycolato) diboron, 4- (4,4,5,5-tetramethyl-1,3,2-dioxaborolane- 2-yl) -1H-pyrazole, (4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl) benzene, tert-butyl-N- [4- (4,4,5 , 5-Tetramethyl-1,2,3-dioxaborolan-2-yl) phenyl] carbamate, phenylboronic acid, 3-acetylphenylboronic acid, boron trifluoride acetic acid complex, boron trifluoride sulfora Complex, 2-thiophene boronic acid, such as tris (trimethylsilyl) borate and the like.

  The content of the boron-containing compound in the first protective layer forming coating solution is not particularly limited, and can be appropriately selected depending on the 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. Benzene, bicyclohexyl, cyclohexylbenzene, decane, undecane, dodecane, tridecane, tetradecane, pentadecane, tetralin, decalin, isopropanol, ethyl benzoate, N, N-dimethylformamide, propylene carbonate, 2-ethylhexanoic acid, mineral spirits, dimethyl Examples include propylene urea, 4-butyrolactone, 2-methoxyethanol, water and the like.

  The content of the solvent in the first protective layer forming coating solution is not particularly limited, and can be appropriately selected depending on the purpose.

The composition ratio of the silicon-containing compound and the alkaline-earth metal-containing compound in the first protective layer forming coating solution (the silicon-containing compound: the alkaline-earth metal-containing compound) is not particularly limited, It can be appropriately selected according to the purpose, but is preferably in the following range.
In the first protective layer forming coating solution, the composition ratio of the Si and the alkaline earth metal (the Si: the alkaline earth metal) may be an oxide (SiO ₂ , BeO, MgO, CaO, (SrO, BaO) conversion is preferably 50.0 mol% to 90.0 mol%: 10.0 mol% to 50.0 mol%.

A composition ratio of the silicon-containing compound, the alkaline-earth metal-containing compound, and at least one of the aluminum-containing compound and the boron-containing compound in the first protective layer forming coating solution (the silicon-containing compound: the alkali The earth metal-containing compound: at least one of the aluminum-containing compound and the boron-containing compound is not particularly limited and may be appropriately selected depending on the intended purpose; however, the following range is preferable.
In the first protective layer forming coating solution, a composition ratio of the Si, the alkaline earth metal, and at least one of the Al and the B (the Si: the alkaline earth metal: the Al and the B At least one of the above) is 50.0 mol% to 90.0 mol%: 5.0 mol in terms of oxide (SiO ₂ , BeO, MgO, CaO, SrO, BaO, Al ₂ O ₃ , B ₂ O ₃ ). % To 20.0 mol%: 5.0 mol% to 30.0 mol% is preferable.

--- Second protective layer forming coating liquid (second insulating film forming coating liquid)-
The second coating liquid for forming a protective layer (second coating liquid for forming an insulating film) contains at least an alkaline earth metal-containing compound, a rare earth element-containing compound, and a solvent, and preferably contains a zirconium-containing compound. And at least one of a hafnium-containing compound and, if necessary, other components.

--- Alkaline earth metal-containing compound ---
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 an alkaline earth metal nitrate, an alkaline earth metal sulfate, an alkaline earth metal chloride, an alkaline earth metal fluoride, an alkaline earth metal bromide, and an alkaline earth metal. And the like.
Examples of the alkaline earth metal nitrate include magnesium nitrate, calcium nitrate, strontium nitrate, and barium nitrate.
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, and barium fluoride.
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, and barium iodide.

  The organic alkaline earth metal compound is not particularly limited as long as it has an alkaline earth metal and an organic group, and can be appropriately selected according to the purpose. The alkaline earth metal and the organic group are bonded by, for example, an ionic bond, a covalent bond, or a coordinate bond.

  The organic group is not particularly limited and may be appropriately selected depending on the purpose. Examples thereof include an alkyl group which may have a substituent, an alkoxy group which may have a substituent, and a substituent. An acyloxy group which may have a 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. No. 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, an acyloxy group partially substituted with a hydroxy group such as lactic acid, Examples include an acyloxy group having two or more carbonyl groups such as oxalic acid and citric acid.

  Examples of the organic alkaline earth metal compound include, for example, magnesium methoxide, magnesium ethoxide, diethyl magnesium, magnesium acetate, magnesium formate, magnesium acetylacetone, magnesium 2-ethylhexanoate, magnesium lactate, magnesium naphthenate, magnesium citrate, Magnesium salicylate, magnesium benzoate, magnesium oxalate, magnesium trifluoromethanesulfonate, calcium methoxide, calcium ethoxide, calcium acetate, calcium formate, calcium acetylacetone, calcium dipivaloyl methanate, 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, strontium naphthenate, strontium salicylate, strontium oxalate, barium ethoxide, barium isoate Propoxide, barium acetate, barium formate, barium acetylacetonate, barium 2-ethylhexanoate, barium lactate, barium naphthenate, barium neodecanoate, barium oxalate, barium benzoate, barium trifluoromethanesulfonate, and the like.

  The content of the alkaline earth metal-containing compound in the second protective layer forming coating solution is not particularly limited, and can be appropriately selected depending on the purpose.

--- Rare earth element-containing compounds ---
The rare earth element in the rare earth element-containing compound includes Sc (scandium), Y (yttrium), La (lanthanum), Ce (cerium), Pr (praseodymium), Nd (neodymium), Pm (promethium), and Sm (samarium). , Eu (europium), Gd (gadolinium), Tb (terbium), Dy (dysprosium), Ho (holmium), Er (erbium), Tm (thulium), Yb (ytterbium), and Lu (lutetium).

  Examples of the rare earth element-containing compound include an inorganic rare earth element compound and an organic rare earth element compound.

Examples of the inorganic rare earth element compound include rare earth element nitrate, rare earth element sulfate, rare earth element fluoride, rare earth element chloride, rare earth element bromide, rare earth element iodide, and the like.
Examples of the rare earth element nitrate include scandium nitrate, yttrium nitrate, lanthanum nitrate, cerium nitrate, praseodymium nitrate, neodymium nitrate, samarium nitrate, europium nitrate, gadolinium nitrate, terbium nitrate, dysprosium nitrate, holmium nitrate, erbium nitrate, thulium nitrate , Ytterbium nitrate, lutetium nitrate and the like.
Examples of the rare earth element sulfates include scandium sulfate, yttrium sulfate, lanthanum sulfate, cerium sulfate, praseodymium sulfate, neodymium sulfate, samarium sulfate, europium sulfate, gadolinium sulfate, terbium sulfate, dysprosium sulfate, holmium sulfate, erbium sulfate, and sulfate. Thulium, ytterbium sulfate, lutetium sulfate and the like.
As the rare earth element fluoride, for example, scandium fluoride, yttrium fluoride, lanthanum fluoride, cerium fluoride, praseodymium fluoride, neodymium fluoride, samarium fluoride, europium fluoride, gadolinium fluoride, terbium fluoride, Dysprosium fluoride, holmium fluoride, erbium fluoride, thulium fluoride, ytterbium fluoride, lutetium fluoride, and the like.
Examples of the rare earth element chloride include scandium chloride, yttrium chloride, lanthanum chloride, cerium chloride, praseodymium chloride, neodymium chloride, samarium chloride, europium chloride, gadolinium chloride, terbium chloride, dysprosium chloride, holmium chloride, erbium chloride, and chloride. Examples include thulium, ytterbium chloride, and lutetium chloride.
Examples of the rare earth element bromide include scandium bromide, yttrium bromide, lanthanum bromide, praseodymium bromide, neodymium bromide, samarium bromide, europium bromide, gadolinium bromide, terbium bromide, dysprosium bromide, Holmium bromide, erbium bromide, thulium bromide, ytterbium bromide, lutetium bromide and the like.
Examples of the rare earth element iodide include scandium iodide, yttrium iodide, lanthanum iodide, cerium iodide, praseodymium iodide, neodymium iodide, samarium iodide, europium iodide, gadolinium iodide, terbium iodide, Dysprosium iodide, holmium iodide, erbium iodide, thulium iodide, ytterbium iodide, lutetium iodide and the like can be mentioned.

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

  The organic group is not particularly limited and may be appropriately selected depending on the purpose. Examples thereof include an alkyl group which may have a substituent, an alkoxy group which may have a substituent, and a substituent. And an acetylacetonate group which may have a substituent, a cyclopentadienyl group which may have a substituent, and the like. 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 organic rare earth element compound include scandium isopropoxide, scandium acetate, tris (cyclopentadienyl) scandium, yttrium isopropoxide, yttrium 2-ethylhexanoate, yttrium tris (acetylacetonato) yttrium, and tris (cyclo). (Pentadienyl) yttrium, lanthanum isopropoxide, lanthanum 2-ethylhexanoate, lanthanum tris (acetylacetonate), lanthanum tris (cyclopentadienyl), cerium 2-ethylhexanoate, cerium tris (acetylacetonate), Tris (cyclopentadienyl) cerium, praseodymium isopropoxide, praseodymium oxalate, tris (acetylacetonato) praseodymium, tris (cyclopentadienyl) praseo System, neodymium isopropoxide, neodymium 2-ethylhexanoate, neodymium trifluoroacetylacetonate, neodymium tris (isopropylcyclopentadienyl), promethium tris (ethylcyclopentadienyl), samarium isopropoxide, 2-ethylhexane Samarium acid, tris (acetylacetonato) samarium, tris (cyclopentadienyl) samarium, europium 2-ethylhexanoate, tris (acetylacetonato) europium, tris (ethylcyclopentadienyl) europium, gadolinium isopropoxide, Gadolinium 2-ethylhexanoate, tris (acetylacetonato) gadolinium, tris (cyclopentadienyl) gadolinium, terbium acetate, tris (acetylacetate) Nate) terbium, tris (cyclopentadienyl) terbium, dysprosium isopropoxide, dysprosium acetate, tris (acetylacetonato) dysprosium, tris (ethylcyclopentadienyl) dysprosium, holmium isopropoxide, holmium acetate, tris (cyclo) (Pentadienyl) holmium, erbium isopropoxide, erbium acetate, tris (acetylacetonato) erbium, tris (cyclopentadienyl) erbium, thulium acetate, tris (acetylacetonato) thulium, tris (cyclopentadienyl) thulium , Ytterbium isopropoxide, ytterbium acetate, tris (acetylacetonato) ytterbium, tris (cyclopentadienyl) ytterbium, Lutetium oxalate, tris (ethylcyclopentadienyl) lutetium and the like.

  The content of the rare earth element-containing compound in the second protective layer forming coating solution is not particularly limited, and can be appropriately selected depending on the purpose.

--- Zirconium-containing compound ---
Examples of the zirconium-containing compound include an inorganic zirconium compound and an organic zirconium compound.

  Examples of the inorganic zirconium compound include zirconium fluoride, zirconium chloride, zirconium bromide, zirconium iodide, zirconium carbonate, and zirconium sulfate.

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

  The organic group is not particularly limited and may be appropriately selected depending on the purpose. Examples thereof include an alkyl group which may have a substituent, an alkoxy group which may have a substituent, and a substituent. And an acetylacetonate group which may have a substituent, a cyclopentadienyl group which may have a substituent, and the like. 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 organic zirconium compound include zirconium butoxide, zirconium isopropoxide, zirconium oxide 2-ethylhexanoate, zirconium di (n-butoxide) bisacetylacetonate, zirconium tetrakis (acetylacetonate), and tetrakis (cyclopentadienyl). ) Zirconium and the like.

  The content of the zirconium-containing compound in the second protective layer forming coating solution is not particularly limited, and can be appropriately selected depending on the purpose.

--- Hafnium-containing compound ---
Examples of the hafnium-containing compound include an inorganic hafnium compound and an organic hafnium compound.

  Examples of the inorganic hafnium compound include hafnium fluoride, hafnium chloride, hafnium bromide, hafnium iodide, hafnium carbonate, and hafnium sulfate.

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

  The organic group is not particularly limited and may be appropriately selected depending on the purpose. Examples thereof include an alkyl group which may have a substituent, an alkoxy group which may have a substituent, and a substituent. And an acetylacetonate group which may have a substituent, a cyclopentadienyl group which may have a substituent, and the like. 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 organic hafnium compound include hafnium butoxide, hafnium isopropoxide, hafnium 2-ethylhexanoate, hafnium di (n-butoxide) bisacetylacetonate, hafnium tetrakis (acetylacetonate), bis (cyclopentadienyl) dimethyl Hafnium and the like.

  The content of the hafnium-containing compound in the second protective layer forming coating solution is not particularly limited and may be appropriately selected depending on the 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. Benzene, bicyclohexyl, cyclohexylbenzene, decane, undecane, dodecane, tridecane, tetradecane, pentadecane, tetralin, decalin, isopropanol, ethyl benzoate, N, N-dimethylformamide, propylene carbonate, 2-ethylhexanoic acid, mineral spirits, dimethyl Examples include propylene urea, 4-butyrolactone, 2-methoxyethanol, water and the like.

  The content of the solvent in the second protective layer forming coating solution is not particularly limited and can be appropriately selected depending on the purpose.

The composition ratio of the alkaline earth metal-containing compound and the rare earth element-containing compound in the second protective layer forming coating liquid (the alkaline earth metal-containing compound: the rare earth element-containing compound) is not particularly limited. And it can be appropriately selected according to the purpose, but is preferably in the following range.
In the second protective layer forming coating solution, the composition ratio of the alkaline earth metal and the rare earth element (the alkaline earth metal: the rare earth element) may be an oxide (BeO, MgO, CaO, SrO). _{, BaO, Sc 2 O 3,} Y 2 O 3, La 2 O 3, Ce 2 O 3, Pr 2 O 3, Nd 2 O 3, Pm 2 O 3, Sm 2 O 3, Eu 2 O 3, Gd 2 O _3, with _{Tb 2 O 3, Dy 2 O} 3, Ho 2 O 3, Er 2 O 3, Tm 2 O 3, Yb 2 O 3, Lu 2 O 3) in terms of, 10.0mol% ~67.0mol% : 33.0 mol% to 90.0 mol% is preferred.

The composition ratio of the alkaline earth metal-containing compound, the rare earth element-containing compound, and at least one of the zirconium-containing compound and the hafnium-containing compound in the second protective layer forming coating solution (the alkaline earth metal-containing compound) Compound: the rare earth element-containing compound: at least one of the zirconium-containing compound and the hafnium-containing compound is not particularly limited and can be appropriately selected depending on the intended purpose, but is preferably in the following range. .
In the second protective layer forming coating solution, a composition ratio of the alkaline earth metal, the rare earth element, and at least one of Zr and Hf (the alkaline earth metal: the rare earth element: the Zr and as at least one) of the Hf is an oxide _{(BeO, MgO, CaO, SrO} , BaO, Sc 2 O 3, Y 2 O 3, La 2 O 3, Ce 2 O 3, Pr 2 O 3, Nd 2 O ₃ , Pm ₂ O ₃ , Sm ₂ O ₃ , Eu ₂ O ₃ , Gd ₂ O ₃ , Tb ₂ O ₃ , Dy ₂ O ₃ , Ho ₂ O ₃ , Er ₂ O ₃ , Tm ₂ O ₃ , Yb ₂ O ₃ , Lu ₂ O ₃ , ZrO ₂ , HfO ₂ ) are preferably 5.0 mol% to 22.0 mol%: 33.0 mol% to 90.0 mol: 5.0 mol% to 45.0 mol%.

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

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

  The heat treatment step is not particularly limited as long as it is a step of heat-treating the first protective layer forming coating liquid applied to the object to be coated, or the second protective layer forming coating liquid. Can be appropriately selected according to the conditions. When the heat treatment is performed, the first protective layer forming coating liquid applied to the object to be coated, or the second protective layer forming coating liquid may be dried by natural drying or the like. Good. By the heat treatment, drying of the solvent, generation of a composite metal oxide (the first composite metal oxide or the second composite metal oxide), and the like are performed.

  In the heat treatment step, drying of the solvent (hereinafter, referred to as “drying process”) and generation of the first composite metal oxide or the second composite metal oxide (hereinafter, “generation process”) ) Are preferably performed at different temperatures. That is, it is preferable that after the solvent is dried, the temperature is raised to generate the first composite metal oxide or the second composite metal oxide. When the first composite metal oxide is formed, for example, at least any one of the silicon-containing compound, the alkaline-earth metal-containing compound, the aluminum-containing compound, and the boron-containing compound is decomposed. During the generation of the second composite metal oxide, for example, decomposition of at least one of the alkaline earth metal-containing compound, the rare earth element-containing compound, the zirconium-containing compound, and the hafnium-containing compound occurs.

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

  The temperature of the generation treatment is not particularly limited and may be appropriately selected depending on the purpose. However, the temperature is preferably from 100 ° C to less than 450 ° C, and more preferably from 200 ° C to 400 ° C. The time of the generation processing is not particularly limited and can be appropriately selected depending on the purpose. For example, 1 hour to 5 hours can be used.

  In the heat treatment process, the drying process and the generation process may be performed continuously, or may be performed in a plurality of steps.

  The method of the heat treatment is not particularly limited and may be appropriately selected depending on the purpose. Examples thereof include a method of heating the object to be coated. The atmosphere in the heat treatment is not particularly limited and can be appropriately selected depending on the intended purpose; however, an oxygen atmosphere is preferable. By performing the heat treatment in the oxygen atmosphere, the decomposition product can be quickly discharged out of the system, and the formation of the first composite metal oxide or the second 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 promote the reaction of the generation treatment. By irradiating ultraviolet light having a wavelength of 400 nm or less, a chemical bond of an organic substance or the like contained in the substance after the drying treatment is cut, and the organic substance can be decomposed. Alternatively, the second composite metal oxide can be formed. The ultraviolet light having a wavelength of 400 nm or less is not particularly limited and can 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 apply ozone instead of or in combination with the irradiation of the ultraviolet light. By applying the ozone to the substance after the drying treatment, generation of an oxide 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 purpose.
The material of the gate insulating layer is not particularly limited and can be appropriately selected depending on the intended purpose. For example, materials that are already widely used for mass production, such as SiO ₂ , SiN _x , and Al ₂ O ₃ , High dielectric constant materials such as La ₂ O ₃ and HfO ₂ , and organic materials such as polyimide (PI) and fluorine-based resin are exemplified.

-Method of forming gate insulating layer-
The method for forming the gate insulating layer is not particularly limited and can be appropriately selected depending on the purpose. For example, a vacuum film forming method such as sputtering, chemical vapor deposition (CVD), or atomic layer deposition (ALD) , Spin coating, die coating, and printing methods such as ink jet.

  The average thickness of the gate insulating layer is not particularly limited and may be appropriately selected depending on the purpose. However, the average thickness is preferably 50 nm to 3 μm, and 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 a current from the field-effect transistor, and can be appropriately selected depending on the purpose.
The source electrode and the drain electrode are formed to be in contact with the gate insulating layer.
The material of the source electrode and the drain electrode is not particularly limited and can be appropriately selected depending on the purpose. For example, metals such as Mo, Al, Au, Ag, and Cu and alloys thereof, and indium oxide Examples include transparent conductive oxides such as tin (ITO) and antimony-doped tin oxide (ATO), and organic conductors such as polyethylene dioxythiophene (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. A method of patterning, (ii) a method of directly forming a film of a desired shape by a printing process such as ink jet, nanoimprint, gravure, and the like can be given.

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

<Semiconductor layer>
The semiconductor layer is formed at least between the source electrode and the drain electrode.
Here, “between” is a position where the semiconductor layer functions as the field-effect transistor together with the source electrode and the drain electrode. Can be appropriately selected according to the conditions.
The semiconductor layer is in contact with the gate insulating layer, the source electrode, and the drain electrode.
The material of the semiconductor layer is not particularly limited and can be appropriately selected depending on the purpose. Examples thereof include a silicon semiconductor and an oxide semiconductor.
Examples of the silicon semiconductor include amorphous silicon and polycrystalline silicon.
Examples of the oxide semiconductor include InGa-Zn-O, In-Zn-O, and In-Mg-O.
Among these, an oxide semiconductor is 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. Examples thereof include a sputtering method, a pulse laser deposition (PLD) method, a chemical vapor deposition (CVD) method, and an atomic layer method. After forming a film by a vacuum process such as vapor deposition (ALD), or a solution process such as dip coating, spin coating, or die coating, a desired shape is directly formed by a method of patterning by photolithography or a printing method such as inkjet, nanoimprint, or gravure. A method of forming a film is given.

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

<Gate electrode>
The gate electrode is not particularly limited as long as it is an electrode for applying a gate voltage to the field effect transistor, and can be appropriately selected depending on the purpose.
The gate electrode is in contact with the gate insulating layer and faces the semiconductor layer via the gate insulating layer.
The material of the gate electrode is not particularly limited and can be appropriately selected depending on the purpose. For example, metals such as Mo, Al, Au, Ag, and Cu and alloys thereof, indium tin oxide (ITO), Examples include transparent conductive oxides such as antimony-doped tin oxide (ATO), and organic conductors such as polyethylene dioxythiophene (PEDOT) and polyaniline (PANI).

-Method of forming gate electrode-
The method for forming the gate electrode is not particularly limited and can be appropriately selected depending on the intended purpose. ii) A method in which a desired shape is directly formed into a film by a printing process such as inkjet, nanoimprint, or gravure.

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

The field-effect transistor structure is not particularly limited and can be appropriately selected depending on the purpose. Examples thereof include a field-effect transistor having the following structure.
(1) The base material, the gate electrode formed on the base material, the gate insulating layer formed on the gate electrode, the source electrode and the drain formed on the gate insulating layer An electrode, the semiconductor layer formed between the source electrode and the drain electrode, the first protective layer formed on the semiconductor layer, and formed on the first protective layer A field-effect transistor having the second protective 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 electrode, the gate insulating layer formed on the semiconductor layer, the gate electrode formed on the gate insulating layer, the first protective layer formed on the gate electrode, And a second protective layer formed on the protective layer.
(3) the base material, the gate electrode formed on the base material, the gate insulating layer formed on the gate electrode, the source electrode and the drain formed on the gate insulating layer An electrode, the semiconductor layer formed between the source electrode and the drain electrode, the second protective layer formed on the semiconductor layer, and formed on the second protective layer A field-effect transistor having the first protective layer.
(4) 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 electrode, the gate insulating layer formed on the semiconductor layer, the gate electrode formed on the gate insulating layer, the second protective layer formed on the gate electrode, the second And a first protective layer formed on the protective layer.

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).
3A to 3D, reference numeral 21 denotes a base material, 22 denotes a gate electrode, 23 denotes a gate insulating layer, 24 denotes a source electrode, 25 denotes a drain electrode, 26 denotes an oxide semiconductor layer, and 27a denotes first protection. Layer 27b represents a second protective layer, respectively.

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

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

<Light control element>
The light control element is not particularly limited as long as the light output is controlled according to a drive signal, and can be appropriately selected according to the purpose. For example, an electroluminescence (EL) element, an electrochromic element, (EC) elements, liquid crystal elements, electrophoretic elements, electrowetting elements, and the like.

<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 light control element, and can be appropriately selected depending on the purpose.

<Other components>
The other members are not particularly limited and can be appropriately selected depending on the purpose.

  Since the display element has the field-effect transistor of the present invention, a long life and high-speed operation can be achieved.

(Image display device)
The image display device of the present invention includes at least a plurality of display elements, a plurality of wirings, and a display control device, and further includes other members as necessary.
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 according to the 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 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 of the field-effect transistors via the plurality of wirings according to the image data, and is appropriately set according to the purpose. You can choose.

<Other components>
The other members are not particularly limited and can be appropriately selected depending on the 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 unit in a portable 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. Further, it can also be used as a display unit for displaying various information in a mobile system such as a car, an aircraft, a train, and a ship. Furthermore, it can be used as a display device for various information in a measuring device, an analyzing device, a medical device, and an advertising medium.

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

Hereinafter, a display element, an image display device, and a system according to 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.
A television device as an example of the system of the present invention can adopt, for example, the configurations described in paragraphs [0038] to [0058] of JP-A-2010-074148 and FIG.

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] of JP-A-2010-074148, and FIGS. 2 and 3 can be employed.

Next, the display element of the present invention will be described with reference to the drawings.
FIG. 1 is a diagram illustrating a display 310 in which display elements are arranged in a matrix.
As shown in FIG. 1, the display 310 has n scanning lines (X0, X1, X2, X3,..., Xn-2, Xn-1) arranged at regular intervals along the X-axis direction. ), And m data lines (Y0, Y1, Y2, Y3,..., Ym-1) arranged at regular intervals along the Y-axis direction and at regular intervals along the Y-axis direction. 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 illustrating 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 32-inch color 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 supplies 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. Then, 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.

  Then, 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, for example, the field effect transistors 11 and 12 each include a base 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 first protective layer. It has a layer 27a and a second protective layer 27b.
The field effect transistors 11 and 12 can be formed by the materials and processes described in the description of the field effect transistor of the present invention.

FIG. 4 is a schematic configuration diagram illustrating an example of the organic EL element.
4, the organic EL element 350 includes 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 can be appropriately selected depending on the purpose. For example, aluminum (Al), magnesium (Mg) -silver (Ag) alloy, aluminum (Al) -lithium (Li) Alloys, ITO (Indium Tin Oxide), and the like. Note that a magnesium (Mg) -silver (Ag) alloy becomes a high-reflectance electrode if it is sufficiently thick, and becomes a translucent electrode if it is extremely thin (less than about 20 nm). Although light is extracted from the anode side in FIG. 4, light can be extracted from the cathode side by using a transparent or translucent electrode for the cathode.

  The material of the anode 314 is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include ITO (Indium Tin Oxide), IZO (Indium Zinc Oxide), and silver (Ag) -neodymium (Nd) alloy. Is mentioned. When a silver alloy is used, the electrode becomes a high-reflectance electrode, which 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, or an electron injection layer may be provided between the electron transport layer 342 and the cathode 312. A hole injection layer may be provided between the transport layer 346 and the anode 314.

  In FIG. 4, the case where the light control element is a so-called “bottom emission” organic EL element that extracts light from the substrate side has been described, but the light control element extracts light from the side opposite to the substrate. An organic EL element of "emission" may be used.

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

The display element includes a base material 31, I- and II-th gate electrodes 32 and 33, a gate insulating layer 34, I- and II-th source electrodes 35 and 36, I- and II-th drain electrodes 37 and 38, I / II oxide semiconductor layers 39/40, I-1 / I-2 / II-1 / II-2 protective layers 41a / 41b / 42a / 42b, interlayer insulating layer 43, organic EL It has a layer 44 and a cathode 45. The first drain electrode 37 and the second gate electrode 33 are connected via a through hole formed in the gate insulating layer 34.
In FIG. 5, for convenience, it appears that a capacitor is formed between the second gate electrode 33 and the second drain electrode 38. However, in actuality, the location where the capacitor is formed is not limited. Can be designed where needed.
In the display element of FIG. 5, the second drain electrode 38 functions as an anode of the organic EL element 350.
Substrate 31, I / II second gate electrode 32/33, gate insulating layer 34, I / II source electrode 35/36, I / II drain electrode 37/38, I / II drain electrode 37/38 The oxide semiconductor layers 39 and 40 of II, and the protective layers 41a, 41b, 42a and 42b of the I-1 / I-2 / II-1 / II-2 are the same as those of the field effect transistor of the present invention. Can be formed by the materials, processes, and the like described in the description.
Note that the (I-1) th protective layer 41a corresponds to the first protective layer of the field effect transistor of the present invention. The (I-2) th protective layer 41b corresponds to the second protective layer of the field-effect transistor of the present invention. The II-1 protective layer 41c corresponds to the first protective layer of the field effect transistor of the present invention. The II-2th protective layer 41d corresponds to the second protective layer of the field-effect transistor of the present invention.

The material of the interlayer insulating layer 43 (flattening film) is not particularly limited and can be appropriately selected depending on the purpose. Examples thereof include an organic material, an inorganic material, and an organic-inorganic composite material.
Examples of the organic material include resins such as polyimide, acrylic resin, fluorine resin, non-fluorine resin, olefin resin, and silicone resin, and photosensitive resins using them.
Examples of the inorganic material include SOG (spin on glass) materials such as Aquamica manufactured by AZ Electronic Materials.
Examples of the organic-inorganic composite material include, for example, an organic-inorganic composite compound composed of a silane compound disclosed in Patent Document (Japanese Patent Application Laid-Open No. 2007-158146).
It is preferable that the interlayer insulating layer has a barrier property against moisture, oxygen, and hydrogen in the air.

The process for forming the interlayer insulating layer is not particularly limited and can be appropriately selected depending on the intended purpose.For example, spin coating, inkjet printing, slit coating, nozzle printing, gravure printing, dip coating, or the like can be used. And a method of patterning a photosensitive material by photolithography.
It is also effective to stabilize the characteristics of the field-effect transistor forming the display element by performing a heat treatment as a post-process after the formation of the interlayer insulating layer.

  The method for producing the organic EL layer 44 and the cathode 45 is not particularly limited and can be appropriately selected depending on the intended purpose. Solution process and the like.

  Thus, a display element, which is a so-called “bottom emission” organic EL element that emits light from the substrate side, can be manufactured. 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 beside the drive circuit 320 has been described. However, as shown in FIG. 6, the organic EL element 350 may be arranged above the drive circuit 320. Good. Also in this case, the so-called “bottom emission” in which light is emitted from the substrate side is required, and the drive circuit 320 is required to have transparency. A transparent conductive material such as ITO, In ₂ O ₃ , SnO ₂ , ZnO, ZnO to which Ga is added, ZnO to which Al is added, and SnO ₂ to which Sb is added is used for the source / drain electrodes and the anode. It is preferable to use an oxide.

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

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

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

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

  In the above embodiment, the case where the organic EL thin film layer includes the electron transport layer, the light emitting layer, and the 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 is emitted from the base material side has been described, but the present invention is not limited to this. For example, a high reflectance electrode such as silver (Ag) -neodymium (Nd) alloy is used for the anode 314, and a semi-transparent electrode such as magnesium (Mg) -silver (Ag) alloy or a transparent electrode such as ITO is used for the cathode 312. Light may be extracted from the side opposite to the material.

  In the above-described embodiment, the case where the light control element is an organic EL element has been described. However, the present invention is not limited to this. For example, the light control element may be an electrochromic element. In this case, the display 310 is an electrochromic display.

  Further, the light control element may be a liquid crystal element. In this case, the display 310 is a liquid crystal display. Then, as shown in FIG. 8 as an example, a 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 ′ includes one field-effect transistor 14 and a capacitor 15 similar to the above-described field-effect transistors (11, 12). Can be. 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. 9 are counter electrodes (common electrodes) of the liquid crystal element 370.

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

  In the above-described embodiment, the case where the display is compatible with color has been described, but the present invention is not limited to this.

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

  The display element, the image display device, and the system using the field-effect transistor of the present invention can operate at high speed and have a long life.

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

(Example 1)
<Production of field effect transistor>
-Preparation of coating liquid for forming first protective layer-
To 1 mL of toluene, 0.10 mL of HMDS (1,1,1,3,3,3-hexamethyldisilazane, manufactured by Tokyo Ohka Kogyo Co., Ltd.) and a toluene solution of calcium 2-ethylhexanoate (Ca content 4.9%) , Strem 93-2014, manufactured by Strem Chemicals) 0.11 mL, and 0.52 mL of a strontium 2-ethylhexanoate toluene solution (Sr content 2%, Wako 195-09561, manufactured by Wako Chemical Co., Ltd.) were mixed. Was obtained. The first composite metal oxide formed by the first protective layer forming coating liquid has a composition shown in Table 1-1.

-Preparation of second protective layer forming coating liquid-
0.99 mL of lanthanum 2-ethylhexanoate toluene solution (La content 7%, Wako 122-033371, manufactured by Wako Chemical Co., Ltd.) and toluene strontium 2-ethylhexanoate solution (Sr content 2%, Wako 195) in 1 mL of toluene -09561, manufactured by Wako Chemical Co., Ltd.) to obtain a second coating liquid for forming a protective layer. The second composite metal oxide formed by the second protective layer forming coating liquid has a composition shown in Table 1-1.

  Next, a bottom-contact / bottom-gate field-effect transistor as shown in FIG. 15 was manufactured.

-Formation of gate electrode-
First, a gate electrode 92 was formed on a glass substrate (base material 91). Specifically, a Mo (molybdenum) film was formed on a glass substrate (base material 91) by DC sputtering so that the average film thickness was about 100 nm. Thereafter, a photoresist was applied, and a resist pattern similar to the pattern of the gate electrode 92 to be formed was formed by pre-baking, exposure by an exposure device, and development. Further, the Mo film in the region where the resist pattern was not formed was removed by reactive ion etching (RIE). Thereafter, the gate electrode 92 made of a Mo film was formed by removing the resist pattern.

-Formation of gate insulating layer-
Next, a gate insulating layer 93 was formed over the gate electrode 92. Specifically, an Al ₂ O ₃ film was formed over the gate electrode 92 and the glass substrate (base material 91) by RF sputtering so that the average film thickness was about 300 nm, so that a gate insulating layer 93 was formed.

-Formation of source electrode and drain electrode-
Next, a source electrode 94 and a drain electrode 95 were formed over the gate insulating layer 93. Specifically, a Mo (molybdenum) film was formed on the gate insulating layer 93 by DC sputtering so that the average film thickness was about 100 nm. Thereafter, a photoresist was applied on the Mo film, and a resist pattern similar to the pattern of the source electrode 94 and the drain electrode 95 to be formed was formed by pre-baking, exposure by an exposure device, and development. Further, the Mo film in the region where the resist pattern was not formed was removed by RIE. Thereafter, by removing the resist pattern, a source electrode 94 and a drain electrode 95 made of a Mo film were formed.

-Formation of oxide semiconductor layer-
Next, 96 oxide semiconductor layers were formed. Specifically, an Mg—In-based oxide (In ₂ MgO ₄ ) film was formed by DC sputtering so that the average thickness was about 100 nm. Thereafter, a photoresist was applied on the Mg-In-based oxide film, and a resist pattern similar to the pattern of the oxide semiconductor layer 96 to be formed was formed by pre-baking, exposure with an exposure device, and development. Further, the Mg-In-based oxide film in the region where the resist pattern was not formed was removed by wet etching. After that, the oxide semiconductor layer 96 was formed by removing the resist pattern. Thus, the oxide semiconductor layer 96 was formed such that a channel was formed between the source electrode 94 and the drain electrode 95.

-Formation of protective layer-
Next, 0.4 mL of the first protective layer forming coating solution was dropped on the substrate, and spin-coated under predetermined conditions (rotated at 3,000 rpm for 20 seconds, and rotated at 0 rpm for 5 seconds). Stopped). Subsequently, after drying at 120 ° C. for 1 hour in the air, baking is performed at 400 ° C. for 3 hours in an O ₂ atmosphere to form a first composite metal oxide film (first protective layer) as a first protective layer 97a. Layer).
Subsequently, 0.4 mL of the second coating liquid for forming a protective layer was dropped on the first protective layer 97a, and spin-coated under predetermined conditions (after rotating at 500 rpm for 5 seconds, and then rotating at 3,000 rpm for 20 seconds). For 2 seconds and stopped at 0 rpm for 5 seconds). Subsequently, after drying at 120 ° C. for 1 hour in the air, baking is performed at 400 ° C. for 3 hours in an O ₂ atmosphere to form a second composite metal oxide film (second protective layer) as a second protective layer 97b. Layer) was formed on the first protective layer 97a. The average thicknesses of the first protective layer 97a and the second protective layer 97b were about 25 nm and about 150 nm, respectively.

-Formation of interlayer insulating layer-
Next, an interlayer insulating layer 98 was formed. Specifically, a positive-type photosensitive organic-inorganic composite material (ADEKA nano-hybrid silicone FX series, manufactured by ADEKA) is applied on the second protective layer 97b by spin coating, and is subjected to pre-baking, exposure using an exposure device, and development. The desired pattern was obtained. Thereafter, post-baking was performed at 150 ° C. for 1 hour and at 200 ° C. for 1 hour.
Finally, a heat treatment was performed at 230 ° C. for one hour as a heat treatment in a later step to complete a field-effect transistor. The average thickness of the interlayer insulating layer was about 1,500 nm.

(Example 2)
<Production of field effect transistor>
-Preparation of coating liquid for forming first protective layer-
To 1 mL of toluene, 0.10 mL of HMDS (1,1,1,3,3,3-hexamethyldisilazane, manufactured by Tokyo Ohka Kogyo Co., Ltd.) and a toluene solution of magnesium 2-ethylhexanoate (Mg content 3%, Strem) 12-1260, manufactured by Strem Chemicals) was added to obtain a first coating liquid for forming a protective layer. The first composite metal oxide formed by the first protective layer forming coating liquid has a composition shown in Table 1-1.

-Preparation of second protective layer forming coating liquid-
0.26 g of yttrium 2-ethylhexanoate (Strem 39-2400, manufactured by Strem Chemicals) and calcium toluene solution of 2-ethylhexanoate (Ca content: 4.9%, Strem 93-2014, manufactured by Strem Chemicals) are added to 1 mL of toluene. 0.05 mL, 0.22 mL of a strontium 2-ethylhexanoate toluene solution (Sr content 2%, Wako 195-09561, manufactured by Wako Chemical Co., Ltd.), and a barium 2-ethylhexanoate toluene solution (Ba content 8%, Wako 021-09471, manufactured by Wako Chemical Co., Ltd.) to obtain a second coating liquid for forming a protective layer. The second composite metal oxide formed by the second protective layer forming coating liquid has a composition shown in Table 1-1.

  A field effect transistor was manufactured in the same manner as in Example 1 using the prepared first protective layer forming coating solution and the second protective layer forming coating solution.

(Example 3)
<Production of field effect transistor>
-Preparation of coating liquid for forming first protective layer-
To 1 mL of toluene, 0.10 mL of HMDS (1,1,1,3,3,3-hexamethyldisilazane, manufactured by Tokyo Ohka Kogyo Co., Ltd.) and a toluene solution of calcium 2-ethylhexanoate (Ca content 4.9%) , Strem 93-2014, manufactured by Strem Chemicals) 0.13 mL, strontium 2-ethylhexanoate toluene solution (Sr content 2%, Wako 195-09561, manufactured by Wako Chemical Co., Ltd.) 0.44 mL, and 2-ethylhexanoic acid 0.11 mL of a barium toluene solution (Ba content 8%, Wako 021-09471, manufactured by Wako Chemical Co., Ltd.) was mixed to obtain a first protective layer forming coating solution. The first composite metal oxide formed by the first protective layer forming coating liquid has a composition shown in Table 1-1.

-Preparation of second protective layer forming coating liquid-
In 1 mL of toluene, 0.29 g of europium 2-ethylhexanoate (Strem 93-6311, manufactured by Strem Chemicals) and a toluene solution of magnesium 2-ethylhexanoate (Mg content: 3%, Strem 12-1260, manufactured by Strem Chemicals) were added. And 23 mL, to obtain a second coating liquid for forming a protective layer. The second composite metal oxide formed by the second protective layer forming coating liquid has a composition shown in Table 1-1.

  A field effect transistor was manufactured in the same manner as in Example 1 using the prepared first protective layer forming coating solution and the second protective layer forming coating solution.

(Example 4)
<Production of field effect transistor>
-Preparation of coating liquid for forming first protective layer-
To 1 mL of toluene, 0.10 mL of HMDS (1,1,1,3,3,3-hexamethyldisilazane, manufactured by Tokyo Ohka Kogyo Co., Ltd.) and a toluene solution of calcium 2-ethylhexanoate (Ca content 4.9%) , Strem 93-2014, manufactured by Strem Chemicals) (0.15 mL) to obtain a first coating solution for forming a protective layer. The first composite metal oxide formed by the first protective layer forming coating liquid has a composition shown in Table 1-1.

-Preparation of second protective layer forming coating liquid-
0.21 g of samarium acetylacetonate trihydrate (Strem 93-6226, manufactured by Strem Chemicals) and 1 g of toluene solution of gadolinium 2-ethylhexanoate (Gd content: 25%, Strem 64-3500, manufactured by Strem Chemicals) are added to 1 mL of toluene. 0.05 mL, 0.06 mL of a 2-ethylhexanoate calcium toluene solution (Ca content: 4.9%, manufactured by Strem 93-2014, manufactured by Strem Chemicals), and a barium 2-ethylhexanoate toluene solution (Ba content: 8%, Wako) 021-09471, manufactured by Wako Chemical Co., Ltd.) to obtain a second coating solution for forming a protective layer. The second composite metal oxide formed by the second protective layer forming coating liquid has a composition shown in Table 1-1.

  A field effect transistor was manufactured in the same manner as in Example 1 using the prepared first protective layer forming coating solution and the second protective layer forming coating solution.

(Example 5)
<Production of field effect transistor>
-Preparation of coating liquid for forming first protective layer-
To 1 mL of toluene, 0.10 mL of HMDS (1,1,1,3,3,3-hexamethyldisilazane, manufactured by Tokyo Ohka Kogyo Co., Ltd.) and a toluene solution of magnesium 2-ethylhexanoate (Mg content 3%, Strem) 0.11 mL of 12-1260, manufactured by Strem Chemicals) and 0.38 mL of a strontium 2-ethylhexanoate toluene solution (Sr content: 2%, Wako 195-09561, manufactured by Wako Chemical Co., Ltd.) for the first protection A coating liquid for forming a layer was obtained. The first composite metal oxide formed by the first protective layer forming coating liquid has a composition shown in Table 1-1.

-Preparation of second protective layer forming coating liquid-
In 1 mL of toluene, 0.18 g of scandium (III) tris (2,2,6,6-tetramethyl-3,5-heptanedionate) hydrate (SIGMA-ALDRICH 517607, manufactured by SIGMA-ALDRICH) and 2 0.26 g of yttrium ethylhexanoate (Strem 39-2400, manufactured by Strem Chemicals), 0.07 g of europium 2-ethylhexanoate (Strem 93-6311, manufactured by Strem Chemicals) and a toluene solution of calcium 2-ethylhexanoate ( 0.06 mL of Ca content 4.9%, Strem 93-2014, manufactured by Strem Chemicals) and a barium 2-ethylhexanoate toluene solution (Ba content 8%, Wako 021-09471, manufactured by Wako Chemical Co., Ltd.) It was mixed and 3 mL, mixed to obtain a second protective layer coating solution. The second composite metal oxide formed by the second protective layer forming coating liquid has a composition shown in Table 1-1.

  A field effect transistor was manufactured in the same manner as in Example 1 using the prepared first protective layer forming coating solution and the second protective layer forming coating solution.

(Example 6)
<Production of field effect transistor>
-Preparation of coating liquid for forming first protective layer-
To 1 mL of toluene, 0.10 mL of HMDS (1,1,1,3,3,3-hexamethyldisilazane, manufactured by Tokyo Ohka Kogyo Co., Ltd.) and aluminum di (s-butoxide) acetoacetate chelate (Al content 8 0.4%, Alfa89349, manufactured by Alfa Aesar) 0.16 mL, magnesium ethyl 2-ethylhexanoate solution (Mg content: 3%, Strem 12-1260, manufactured by Strem Chemicals) 0.05 mL, and barium toluene 2-ethylhexanoate 0.12 mL of a solution (Ba content 8%, Wako 021-09471, manufactured by Wako Chemical Co., Ltd.) was mixed to obtain a first coating solution for forming a protective layer. The second composite metal oxide formed by the first protective layer forming coating liquid has a composition shown in Table 1-2.

-Preparation of second protective layer forming coating liquid-
Neodymium 2-ethylhexanoate 2-ethylhexanoic acid solution (Nd content 12%, Strem 60-2400, manufactured by Strem Chemicals) 0.60 mL and toluene 2-calcium 2-ethylhexanoate solution (Ca content 4.9) are added to 1 mL of toluene. %, Strem 93-2014, 0.31 mL from Strem Chemicals) to obtain a second coating liquid for forming a protective layer. The second composite metal oxide formed by the second protective layer forming coating liquid has the composition shown in Table 1-2.

  A field effect transistor was manufactured in the same manner as in Example 1 using the prepared first protective layer forming coating solution and the second protective layer forming coating solution.

(Example 7)
<Production of field effect transistor>
-Preparation of coating liquid for forming first protective layer-
To 1 mL of toluene, 0.10 mL of HMDS (1,1,1,3,3,3-hexamethyldisilazane, manufactured by Tokyo Ohka Kogyo Co., Ltd.) and 2-isopropoxy-4,4,5,5-tetramethyl 0.11 g of -1,3,2-dioxaborolane (Wako 325-41462, manufactured by Wako Chemical Co., Ltd.) and a toluene solution of magnesium 2-ethylhexanoate (Mg content: 3%, Strem 12-1260, manufactured by Strem Chemicals) 09 mL and 0.25 mL of a strontium 2-ethylhexanoate toluene solution (Sr content 2%, Wako 195-09561, manufactured by Wako Chemical Co., Ltd.) were obtained to obtain a first protective layer forming coating solution. The second composite metal oxide formed by the first protective layer forming coating liquid has a composition shown in Table 1-2.

-Preparation of second protective layer forming coating liquid-
In 1 mL of toluene, 0.29 g of europium 2-ethylhexanoate (Strem 93-6311, manufactured by Strem Chemicals) and a strontium 2-ethylhexanoate toluene solution (Sr content 2%, Wako 195-09561, manufactured by Wako Chemical Co., Ltd.) 0.13 mL and 0.08 mL of a barium 2-ethylhexanoate toluene solution (Ba content 8%, Wako 021-09471, manufactured by Wako Chemical Co., Ltd.) were mixed to obtain a second protective layer forming coating solution. . The second composite metal oxide formed by the second protective layer forming coating liquid has the composition shown in Table 1-2.

  A field effect transistor was manufactured in the same manner as in Example 1 using the prepared first protective layer forming coating solution and the second protective layer forming coating solution.

(Example 8)
<Production of field effect transistor>
-Preparation of coating liquid for forming first protective layer-
To 1 mL of toluene, 0.10 mL of HMDS (1,1,1,3,3,3-hexamethyldisilazane, manufactured by Tokyo Ohka Kogyo Co., Ltd.) and aluminum di (s-butoxide) acetoacetate chelate (Al content 8 0.41%, Alfa89349, manufactured by Alfa Aesar) 0.11 mL, and 2-isopropoxy-4,4,5,5-tetramethyl-1,3,2-dioxaborolane (Wako 325-41462, manufactured by Wako Chemical Co., Ltd.) 0.07 g and 0.27 mL of a 2-ethylhexanoic acid calcium toluene solution (Ca content: 4.9%, manufactured by Strem 93-2014, manufactured by Strem Chemicals) were mixed to obtain a first protective layer forming coating solution. . The first composite metal oxide formed by the first protective layer forming coating liquid has a composition shown in Table 1-2.

-Preparation of second protective layer forming coating liquid-
0.99 mL of a lanthanum 2-ethylhexanoate toluene solution (La content: 7%, Wako 122-033371, manufactured by Wako Chemical Co., Ltd.) and 1-mL toluene solution (magnesium content: 3%, Strem 12) -1260, 0.03 mL of Strem Chemicals), 0.14 mL of a strontium 2-ethylhexanoate toluene solution (Sr content 2%, Wako 195-09561, manufactured by Wako Chemical Co., Ltd.), and a barium 2-ethylhexanoate toluene solution (Ba content 8%, Wako 021-09471, manufactured by Wako Chemical Co., Ltd.) was mixed with 0.11 mL to obtain a second coating solution for forming a protective layer. The second composite metal oxide formed by the second protective layer forming coating liquid has the composition shown in Table 1-2.

  A field effect transistor was manufactured in the same manner as in Example 1 using the prepared first protective layer forming coating solution and the second protective layer forming coating solution.

(Example 9)
<Production of field effect transistor>
-Preparation of coating liquid for forming first protective layer-
To 1 mL of toluene, 0.10 mL of HMDS (1,1,1,3,3,3-hexamethyldisilazane, manufactured by Tokyo Ohka Kogyo Co., Ltd.) and a strontium 2-ethylhexanoate toluene solution (Sr content 2%, Wako) 195-09561 (manufactured by Wako Chemical Co., Ltd.) in an amount of 1.42 mL to obtain a first coating liquid for forming a protective layer. The first composite metal oxide formed by the first protective layer forming coating liquid has a composition shown in Table 1-2.

-Preparation of second protective layer forming coating liquid-
In 1 mL of toluene, 0.22 g of samarium acetylacetonate trihydrate (Strem 93-6226, manufactured by Strem Chemicals) and a toluene solution of calcium 2-ethylhexanoate (Ca content 4.9%, Strem 93-2014, Strem Chemicals) 0.01 mL), 0.18 mL of a strontium 2-ethylhexanoate toluene solution (Sr content 2%, Wako 195-09561, manufactured by Wako Chemical Co., Ltd.) and a zirconium oxide mineral spirit solution of 2-ethylhexanoate (Zr content 12%, Wako 269-01116, manufactured by Wako Chemical Co., Ltd.) 0.03 mL to obtain a second protective layer forming coating solution. The second composite metal oxide formed by the second protective layer forming coating liquid has the composition shown in Table 1-2.

  A field effect transistor was manufactured in the same manner as in Example 1 using the prepared first protective layer forming coating solution and the second protective layer forming coating solution.

(Example 10)
<Production of field effect transistor>
-Preparation of coating liquid for forming first protective layer-
To 1 mL of toluene, 0.10 mL of HMDS (1,1,1,3,3,3-hexamethyldisilazane, manufactured by Tokyo Ohka Kogyo Co., Ltd.) and a toluene solution of magnesium 2-ethylhexanoate (Mg content 3%, Strem) 12-1260, 0.06 mL of Strem Chemicals), 0.10 mL of a calcium solution of 2-ethylhexanoate in toluene (Ca content: 4.9%, Strem 93-2014, Strem Chemicals), and barium toluene 2-ethylhexanoate 0.11 mL of a solution (Ba content 8%, Wako 021-09471, manufactured by Wako Chemical Co., Ltd.) was mixed to obtain a first coating liquid for forming a protective layer. The first composite metal oxide formed by the first protective layer forming coating liquid has a composition shown in Table 1-2.

-Preparation of second protective layer forming coating liquid-
To 1 mL of toluene, 0.31 mL of a gadolinium 2-ethylhexanoate toluene solution (Gd content: 25%, Strem 64-3500, manufactured by Strem Chemicals) and a calcium toluene 2-ethylhexanoate solution (Ca content: 4.9%, Strem 93) -2014, 0.06 mL of Strem Chemicals) and 0.10 mL of hafnium 2-ethylhexanoate 2-ethylhexanoic acid solution (Geest AKH332, Gelest) are obtained to obtain a second protective layer forming coating solution. Was. The second composite metal oxide formed by the second protective layer forming coating liquid has the composition shown in Table 1-2.

  A field effect transistor was manufactured in the same manner as in Example 1 using the prepared first protective layer forming coating solution and the second protective layer forming coating solution.

(Example 11)
<Production of field effect transistor>
-Preparation of coating liquid for forming first protective layer-
To 1 mL of toluene, 0.10 mL of HMDS (1,1,1,3,3,3-hexamethyldisilazane, manufactured by Tokyo Ohka Kogyo Co., Ltd.) and a toluene solution of calcium 2-ethylhexanoate (Ca content 4.9%) , Strem 93-2014, manufactured by Strem Chemicals) and 0.16 mL of a barium 2-ethylhexanoate toluene solution (Ba content: 8%, Wako 021-09471, manufactured by Wako Chemical Co., Ltd.) were mixed. Was obtained. The first composite metal oxide formed by the first protective layer forming coating liquid has a composition shown in Table 1-3.

-Preparation of second protective layer forming coating liquid-
In 1 mL of toluene, 0.26 g of yttrium 2-ethylhexanoate (Strem 39-2400, manufactured by Strem Chemicals), 0.04 g of dysprosium acetylacetonate trihydrate (Strem 66-2002, manufactured by Strem Chemicals), and 2- 0.01 mL of a magnesium ethylhexanoate toluene solution (Mg content 3%, Strem 12-1260, manufactured by Strem Chemicals) and a 2-ethylhexanoate calcium toluene solution (Ca content 4.9%, Strem 93-2014, manufactured by Strem Chemicals) ) 0.01 mL, and 0.08 mL of zirconium oxide mineral spirit solution of 2-ethylhexanoate (Zr content 12%, Wako 269-01116, manufactured by Wako Chemical Co., Ltd.) Chiruhekisan hafnium 2-ethylhexanoic acid solution (Gelest AKH332, Gelest Inc.) was mixed with 0.05 mL, to obtain a second protective layer coating solution. The second composite metal oxide formed by the second protective layer forming coating liquid has a composition shown in Table 1-3.

  A field effect transistor was manufactured in the same manner as in Example 1 using the prepared first protective layer forming coating solution and the second protective layer forming coating solution.

(Example 12)
<Production of field effect transistor>
-Preparation of coating liquid for forming first protective layer-
To 1 mL of toluene, 0.11 mL of HMDS (1,1,1,3,3,3-hexamethyldisilazane, manufactured by Tokyo Ohka Kogyo Co., Ltd.) and aluminum di (s-butoxide) acetoacetate chelate (Al content 8 0.4%, Alfa89349, manufactured by Alfa Aesar) 0.10 mL, and 2-isopropoxy-4,4,5,5-tetramethyl-1,3,2-dioxaborolane (Wako 325-41462, manufactured by Wako Chemical Co., Ltd.) 0.08 g, 0.09 mL of a calcium solution of 2-ethylhexanoate in toluene (Ca content 4.9%, manufactured by Strem 93-2014, manufactured by Strem Chemicals), and a strontium 2-ethylhexanoate solution in toluene (Sr content of 2%, Wako) 195-09561, manufactured by Wako Chemical Co., Ltd.) 0.17 m Mixing the door to obtain a first coating liquid for forming a protective layer. The first composite metal oxide formed by the first protective layer forming coating liquid has a composition shown in Table 1-3.

-Preparation of second protective layer forming coating liquid-
To 1 mL of toluene, 0.99 mL of a lanthanum 2-ethylhexanoate toluene solution (La content: 7%, Wako 122-033371, manufactured by Wako Chemical Co., Ltd.) and a strontium 2-ethylhexanoate toluene solution (Sr content: 2%, Wako 195-09561, manufactured by Wako Chemical Co., Ltd.), 0.27 mL, and 0.05 mL of zirconium oxide mineral spirit solution of 2-ethylhexanoate (Zr content: 12%, Wako 269-01116, manufactured by Wako Chemical Co., Ltd.) A second coating liquid for forming a protective layer was obtained. The second composite metal oxide formed by the second protective layer forming coating liquid has a composition shown in Table 1-3.

  A field effect transistor was manufactured in the same manner as in Example 1 using the prepared first protective layer forming coating solution and the second protective layer forming coating solution.

(Example 13)
<Production of field effect transistor>
-Preparation of coating liquid for forming first protective layer-
To 1 mL of toluene, 0.10 mL of HMDS (1,1,1,3,3,3-hexamethyldisilazane, manufactured by Tokyo Ohka Kogyo Co., Ltd.) and aluminum di (s-butoxide) acetoacetate chelate (Al content 8 0.4%, Alfa89349, manufactured by Alfa Aesar) 0.08 mL, and 0.35 mL of a barium 2-ethylhexanoate toluene solution (Ba content 8%, Wako 021-09471, manufactured by Wako Chemical Co., Ltd.) were mixed. Was obtained. The first composite metal oxide formed by the first protective layer forming coating liquid has a composition shown in Table 1-3.

-Preparation of second protective layer forming coating liquid-
0.2 mL of samarium acetylacetonate trihydrate (Strem 93-6226, manufactured by Strem Chemicals) and a toluene solution of magnesium 2-ethylhexanoate (Mg content: 3%, Strem 12-1260, manufactured by Strem Chemicals) are added to 1 mL of toluene. 0.02 mL and 0.01 mL of hafnium 2-ethylhexanoate 2-ethylhexanoic acid solution (Geest AKH332, manufactured by Gelest) were mixed to obtain a second coating solution for forming a protective layer. The second composite metal oxide formed by the second protective layer forming coating liquid has a composition shown in Table 1-3.

  A field effect transistor was manufactured in the same manner as in Example 1 using the prepared first protective layer forming coating solution and the second protective layer forming coating solution.

(Example 14)
<Production of field effect transistor>
-Preparation of coating liquid for forming first protective layer-
To 1 mL of toluene, 0.10 mL of HMDS (1,1,1,3,3,3-hexamethyldisilazane, manufactured by Tokyo Ohka Kogyo Co., Ltd.) and 2-isopropoxy-4,4,5,5-tetramethyl 0.05 g of -1,3,2-dioxaborolane (Wako 325-41462, manufactured by Wako Chemical Co., Ltd.) and a toluene solution of magnesium 2-ethylhexanoate (Mg content: 3%, Strem 12-1260, manufactured by Strem Chemicals) 05 mL and 0.23 mL of a strontium 2-ethylhexanoate toluene solution (Sr content 2%, Wako 195-09561, manufactured by Wako Chemical Co., Ltd.) were mixed to obtain a first coating solution for forming a protective layer. The first composite metal oxide formed by the first protective layer forming coating liquid has a composition shown in Table 1-3.

-Preparation of second protective layer forming coating liquid-
In 1 mL of toluene, 0.30 g of scandium (III) tris (2,2,6,6-tetramethyl-3,5-heptanedionate) hydrate (SIGMA-ALDRICH 517607, manufactured by SIGMA-ALDRICH) and ytterbium 0.05 g of acetylacetonate trihydrate (Strem 70-2202, manufactured by Strem Chemicals) and 0.04 mL of a calcium toluene solution of 2-ethylhexanoate (Ca content: 4.9%, Strem 93-2014, manufactured by Strem Chemicals) And 0.03 mL of zirconium oxide mineral spirit solution of 2-ethylhexanoic acid (Zr content 12%, Wako 269-01116, manufactured by Wako Chemical Co., Ltd.) and hafnium 2-ethylhexanoate 2-ethylhexanoic acid solution (Geles AKH332, mixed and from Gelest) 0.07 mL, to obtain a second protective layer coating solution. The second composite metal oxide formed by the second protective layer forming coating liquid has a composition shown in Table 1-3.

  A field effect transistor was manufactured in the same manner as in Example 1 using the prepared first protective layer forming coating solution and the second protective layer forming coating solution.

(Example 15)
<Production of field effect transistor>
-Preparation of coating liquid for forming first protective layer-
To 1 mL of toluene, 0.10 mL of HMDS (1,1,1,3,3,3-hexamethyldisilazane, manufactured by Tokyo Ohka Kogyo Co., Ltd.) and aluminum di (s-butoxide) acetoacetate chelate (Al content 8 0.4%, Alfa89349, manufactured by Alfa Aesar) 0.11 mL, and 2-isopropoxy-4,4,5,5-tetramethyl-1,3,2-dioxaborolane (Wako 325-41462, manufactured by Wako Chemical Co., Ltd.) 0.08 g and 0.07 mL of a calcium 2-ethylhexanoate toluene solution (Ca content: 4.9%, manufactured by Strem 93-2014, manufactured by Strem Chemicals) were mixed to obtain a first protective layer forming coating solution. . The first composite metal oxide formed by the first protective layer forming coating liquid has a composition shown in Table 1-3.

-Preparation of second protective layer forming coating liquid-
To 1 mL of toluene, 0.99 mL of a lanthanum 2-ethylhexanoate toluene solution (La content: 7%, Wako 122-033371, manufactured by Wako Chemical Co., Ltd.) and a strontium 2-ethylhexanoate toluene solution (Sr content: 2%, Wako 195-09561, 0.08 mL of a barium 2-ethylhexanoate toluene solution (Ba content 8%, Wako 211-09471, manufactured by Wako Chemical Co., Ltd.) 0.08 mL, and 2-ethylhexanoic acid 0.03 mL of zirconium oxide mineral spirit solution (Zr content 12%, Wako 269-01116, manufactured by Wako Chemical Co., Ltd.) and 0.02 mL of hafnium 2-ethylhexanoate 2-ethylhexanoic acid solution (Gelest AKH332, Gelest) Were mixed to obtain a second protective layer coating solution. The second composite metal oxide formed by the second protective layer forming coating liquid has a composition shown in Table 1-3.

  A field effect transistor was manufactured in the same manner as in Example 1 using the prepared first protective layer forming coating solution and the second protective layer forming coating solution.

(Example 16)
<Production of field effect transistor>
-Preparation of coating liquid for forming first protective layer-
To 1 mL of toluene, 0.11 mL of HMDS (1,1,1,3,3,3-hexamethyldisilazane, manufactured by Tokyo Ohka Kogyo Co., Ltd.) and aluminum di (s-butoxide) acetoacetate ester chelate (Al content 8 0.4%, Alfa89349, manufactured by Alfa Aesar) 0.10 mL, and (4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl) benzene (Wako 325-59912, Wako Chemical Co., Ltd.) 0.11 g), 0.09 mL of calcium 2-ethylhexanoate 2-ethylhexanoic acid solution (Ca content 3% -8%, Alfa36657, manufactured by Alfa Aesar), and strontium 2-ethylhexanoate toluene solution (Sr content 2%, Wako 195-09561, manufactured by Wako Chemical Co., Ltd.) 0.17 mL Were mixed to obtain a first coating liquid for forming a protective layer. The first composite metal oxide formed by the first protective layer forming coating liquid has a composition shown in Table 1-3.

-Preparation of second protective layer forming coating liquid-
To 1 mL of toluene, 0.99 mL of a lanthanum 2-ethylhexanoate toluene solution (La content: 7%, Wako 122-03371, manufactured by Wako Chemical Co., Ltd.) and a strontium 2-ethylhexanoate toluene solution (Sr content: 2%, Wako 195-09561, manufactured by Wako Chemical Co., Ltd.), 0.27 mL, and 0.05 mL of zirconium oxide mineral spirit solution of 2-ethylhexanoate (Zr content: 12%, Wako 269-01116, manufactured by Wako Chemical Co., Ltd.) A second coating liquid for forming a protective layer was obtained. The second composite metal oxide formed by the second protective layer forming coating liquid has a composition shown in Table 1-3.

  A field effect transistor was manufactured in the same manner as in Example 1 using the prepared first protective layer forming coating solution and the second protective layer forming coating solution.

(Comparative Example 1)
<Production of field effect transistor>
-Preparation of coating liquid for forming first protective layer-
0.10 mL of HMDS (1,1,1,3,3,3-hexamethyldisilazane, manufactured by Tokyo Ohka Kogyo Co., Ltd.) was mixed with 1 mL of toluene to obtain a first protective layer forming coating solution. The first metal oxide formed by the first protective layer forming coating solution has a composition shown in Table 2-1.

  A field-effect transistor was manufactured in the same manner as in Example 1, except that the prepared first protective layer forming coating solution was used and the second protective layer forming coating solution was not used.

(Comparative Example 2)
<Production of field effect transistor>
-Preparation of second protective layer forming coating liquid-
0.99 mL of a toluene solution of lanthanum 2-ethylhexanoate (La content: 7%, Wako 122-033371, manufactured by Wako Chemical Co., Ltd.) was mixed with 1 mL of toluene to obtain a second coating solution for forming a protective layer. The second metal oxide formed by the second protective layer forming coating solution has a composition shown in Table 2-1.

  A field-effect transistor was manufactured in the same manner as in Example 1 except that the prepared second protective layer forming coating solution was used and the first protective layer forming coating solution was not used.

(Comparative Example 3)
<Production of field effect transistor>
-Preparation of second protective layer forming coating liquid-
0.43 mL of a toluene solution of magnesium 2-ethylhexanoate (Mg content 3%, Strem 12-1260, manufactured by Strem Chemicals) was mixed with 1 mL of toluene to obtain a second coating solution for forming a protective layer. The second metal oxide formed by the second protective layer forming coating solution has a composition shown in Table 2-1.

  A field-effect transistor was manufactured in the same manner as in Example 1 except that the prepared second protective layer forming coating solution was used and the first protective layer forming coating solution was not used.

(Comparative Example 4)
<Production of field effect transistor>
-Preparation of coating liquid for forming first protective layer-
0.10 mL of HMDS (1,1,1,3,3,3-hexamethyldisilazane, manufactured by Tokyo Ohka Kogyo Co., Ltd.) was mixed with 1 mL of toluene to obtain a first protective layer forming coating solution. The first metal oxide formed by the first protective layer forming coating solution has a composition shown in Table 2-1.

-Preparation of second protective layer forming coating liquid-
0.59 g of scandium (III) tris (2,2,6,6-tetramethyl-3,5-heptanedionate) hydrate (SIGMA-ALDRICH 517607, manufactured by SIGMA-ALDRICH) was mixed with 1 mL of toluene. Thus, a second coating liquid for forming a protective layer was obtained. The second metal oxide formed by the second protective layer forming coating solution has a composition shown in Table 2-1.

  A field effect transistor was manufactured in the same manner as in Example 1 using the prepared first protective layer forming coating solution and the second protective layer forming coating solution.

(Comparative Example 5)
<Production of field effect transistor>
-Preparation of coating liquid for forming first protective layer-
To 1 mL of toluene, 0.11 mL of HMDS (1,1,1,3,3,3-hexamethyldisilazane, manufactured by Tokyo Ohka Kogyo Co., Ltd.) and a barium 2-ethylhexanoate toluene solution (Ba content 8 wt%, Wako) 21-09471 (manufactured by Wako Chemical Co., Ltd.) in an amount of 2.57 mL to obtain a first coating liquid for forming a protective layer. The first composite metal oxide formed by the first protective layer forming coating liquid has the composition shown in Table 2-1.

  A field-effect transistor was manufactured in the same manner as in Example 1, except that the prepared first protective layer forming coating solution was used and the second protective layer forming coating solution was not used.

(Comparative Example 6)
<Production of field effect transistor>
-Preparation of second protective layer forming coating liquid-
To 1 mL of toluene, 0.31 mL of a gadolinium 2-ethylhexanoate toluene solution (Gd content: 25 wt%, manufactured by Strem Chemicals) and a barium 2-ethylhexanoate toluene solution (Ba content: 8 wt%, Wako 021-09471) And Wako Chemical Co., Ltd.) (0.23 mL) to obtain a second protective layer forming coating solution. The second composite metal oxide formed by the second protective layer forming coating liquid has a composition shown in Table 2-2.

  A field-effect transistor was manufactured in the same manner as in Example 1 except that the prepared second protective layer forming coating solution was used and the first protective layer forming coating solution was not used.

(Comparative Example 7)
<Production of field effect transistor>
-Preparation of coating liquid for forming first protective layer-
0.11 mL of HMDS (1,1,1,3,3,3-hexamethyldisilazane, manufactured by Tokyo Ohka Kogyo Co., Ltd.) was mixed with 1 mL of toluene to obtain a first protective layer forming coating solution. The first metal oxide formed by the first protective layer forming coating liquid has a composition shown in Table 2-2.

-Preparation of second protective layer forming coating liquid-
To 1 mL of toluene, 0.22 g of samarium acetylacetonate trihydrate (Strem 93-6226, manufactured by Strem Chemicals) and a strontium 2-ethylhexanoate toluene solution (Sr content: 2 wt%, Wako 195-09561, Wako Chemical Co., Ltd.) And 0.36 mL of each of them were mixed to obtain a second coating solution for forming a protective layer. The second composite metal oxide formed by the second protective layer forming coating liquid has a composition shown in Table 2-2.

  A field effect transistor was manufactured in the same manner as in Example 1 using the prepared first protective layer forming coating solution and the second protective layer forming coating solution.

(Comparative Example 8)
<Production 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 over a glass substrate in the same manner as in Example 1.

-Formation of protective layer-
Using SiCl ₄ as a raw material, a SiO ₂ layer was formed as a protective layer by a PECVD (Plasma enhanced chemical vapor deposition) method. The average thickness of the protective layer thus formed was about 200 nm.

-Formation of interlayer insulating layer-
Finally, an interlayer insulating layer was formed on the protective layer in the same manner as in Example 1 to complete a field effect transistor.

<Evaluation of reliability of field-effect transistor>
The field effect transistors manufactured in Examples 1 to 16 and Comparative Examples 1 to 8 were subjected to a BTS (Bias Temperature Stress) test in the air (at a temperature of 50 ° C. and a relative humidity of 50%) for 400 hours.
The following four types of stress conditions were used.
(1) Voltage between gate electrode 92 and source electrode 94 (Vgs) = + 20 V, and voltage between drain electrode 95 and source electrode 94 (Vds) = 0 V
(2) Vgs = + 20V and Vds = + 20V
(3) Vgs = −20V and Vds = 0V
(4) Vgs = −20V and Vds = + 20V
Further, every time a predetermined time elapses in the BTS test, the relationship (Vgs-Ids) between Vgs and the current Ids between the source electrode 94 and the drain electrode 95 when Vds = + 20 V was measured.

FIG. 10 shows the results of Vgs-Ids in the test where the stress conditions were Vgs = + 20 V and Vds = 0 V in the field-effect transistor manufactured in Example 12. FIG. 11 shows the results of Vgs-Ids of tests in which the stress conditions were Vgs = + 20 V and Vds = + 20 V. FIG. 12 shows the results of Vgs-Ids of the test in which the stress conditions were Vgs = −20 V and Vds = 0 V. FIG. 13 shows the results of Vgs-Ids of tests in which the stress conditions were Vgs = −20 V and Vds = + 20 V.
Here, “e” on the vertical axis of the graphs of FIGS. 10, 11, 12, and 13 and the horizontal axis and the vertical axis of the graph of FIG. 14 represent a power of 10. For example, “1e-03” represents “1 × 10 ⁻³ ” and “0.001”, and “1e-05” represents “1 × 10 ⁻⁵ ” and “0.00001”.

  FIG. 14 shows the change amount (ΔVth) of the threshold voltage with respect to the stress time in the BTS test under the stress conditions of Vgs = + 20 V and Vds = 0 V of the field-effect transistors manufactured in Example 12 and Comparative Example 8. Here, ΔVth indicates a change amount of Vth from a stress time of 0 hours to a certain stress time. From FIG. 14, it was confirmed that the field-effect transistor manufactured in Example 12 had a small ΔVth shift and exhibited excellent reliability. On the other hand, the field effect transistor manufactured in Comparative Example 8 had a large ΔVth shift and was insufficient in reliability.

  Tables 3 and 4 show the values of ΔVth at 400 hours of stress time in the BTS tests of the field-effect transistors of Examples 1 to 16 and Comparative Examples 1 to 8. From Tables 3 and 4, it was confirmed that the field-effect transistors manufactured in Examples 1 to 16 had a small ΔVth shift and exhibited excellent reliability in the BTS test. On the other hand, the field-effect transistors manufactured in Comparative Examples 1, 4, 5, 6, 7, and 8 had a large ΔVth shift and had insufficient reliability. Further, the field-effect transistors manufactured in Comparative Examples 2 and 3 could not maintain the transistor characteristics in the air, and could not perform the BTS test.

Aspects of the present invention are, for example, as follows.
<1> base material,
A protective layer,
The base material, and a gate insulating layer formed between the protective layer,
A source electrode and a drain electrode formed to be in contact with the gate insulating layer;
A semiconductor layer formed at least between the source electrode and the drain electrode and in contact with the gate insulating layer, the source electrode, and the drain electrode;
A gate electrode in contact with the gate insulating layer and facing the semiconductor layer via the gate insulating layer;
The protective layer is formed in contact with the first protective layer containing a first composite metal oxide containing Si and an alkaline earth metal, and the first protective layer. And a second protective layer containing a second composite metal oxide containing a rare earth element.
<2> The field-effect transistor according to <1>, wherein the first 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 second composite metal oxide contains at least one of Zr and Hf.
<4> The field-effect transistor according to any one of <1> to <3>, wherein the semiconductor layer is an oxide semiconductor.
<5> a light control element whose light output is controlled according to a drive signal;
A display element, comprising: the driving circuit that has the field-effect transistor according to any one of <1> to <4> and drives the light control element.
<6> The display element according to <5>, wherein the light control element includes 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 corresponding to image data,
A plurality of display elements according to any one of <5> to <6>, 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,
A display control device that individually controls a gate voltage of each of the field effect transistors via the plurality of wirings according to the image data.
<8> The image display device according to <7>,
An image data creation device for creating image data based on image information to be displayed and outputting the image data to the image display device.

DESCRIPTION OF SYMBOLS 11 Field effect transistor 12 Field effect transistor 13 Capacitor 14 Field effect transistor 15 Capacitor 16 Counter electrode 21 Base material 22 Gate electrode 23 Gate insulating layer 24 Source electrode 25 Drain electrode 26 Oxide semiconductor layer 27a Ith protective layer 27b II protective layer 31 base material 32 I gate electrode 33 II gate electrode 34 gate insulating layer 35 I source electrode 36 II source electrode 37 I drain electrode 38 II drain electrode 39 I oxide semiconductor layer 40 II oxide semiconductor layer 41a I-1 protective layer 41b I-2 protective layer 42a II-1 protective layer 42b II-2 protective layer 43 interlayer insulating layer 44 Organic EL layer 45 Cathode 91 Base material 92 Gate electrode 93 Gate insulating layer 94 Saw Electrode 95 drain electrode 96 the oxide semiconductor layer 97a first protective layer 97b second protective layer 98 interlayer insulating layer 302, 302 'display device 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 Counter electrode 400 Display control device 402 Image data processing circuit 404 Scan line drive circuit 406 Data line drive circuit

JP 2007-073705 A JP 2010-135770 A JP 2010-182819 A JP 2010-135462 A

K. Nomura, 5 others, "Room-temperature fabrication of transparent flexible thinfilm transformers using amorphous oxide semiconductors", NATURE, VOL4. 488-492 T. Arai, et al., “Manufacturing Issues for Oxide TFT Technologies for Large-Size AMOLED Displays”, SID 2012 Digest, 2012, p. 756-759

Claims (9)

A substrate, a protective layer, and a semiconductor layer, a field-effect transistor having a
The semiconductor layer is formed between the base material and the protective layer,
The protective layer includes a first protective layer containing a first composite metal oxide containing Si and an alkaline earth metal, and a second composite metal oxide containing an alkaline earth metal and a rare earth element. And a second protective layer. A field-effect transistor including a semiconductor layer and a stacked oxide layer in contact with the semiconductor layer,
The laminated oxide layer includes a first oxide layer containing a first composite metal oxide containing Si and B, and a second composite metal oxide containing an alkaline earth metal and a rare earth element. And a second oxide layer containing
The average thickness of the first oxide layer is 10 nm to 1,000 nm,
A field-effect transistor, wherein the average thickness of the second oxide layer is 10 nm to 1,000 nm. The field effect transistor according to claim 1, wherein the first composite metal oxide contains at least one of Al and B.   4. The field effect transistor according to claim 1, wherein the second composite metal oxide contains at least one of Zr and Hf.   The field effect transistor according to claim 1, wherein the semiconductor layer is an oxide semiconductor. A light control element whose light output is controlled according to a drive signal;
A display element, comprising: a drive circuit having the field-effect transistor according to claim 1 and driving the light control element.   The display device according to claim 6, wherein the light control device includes any one of an electroluminescence device, an electrochromic device, a liquid crystal device, an electrophoresis device, and an electrowetting device. An image display device that displays an image according to image data,
A plurality of display elements according to any one of claims 6 to 7, which are 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,
An image display device comprising: a display control device that individually controls a gate voltage of each of the field-effect transistors via the plurality of wirings according to the image data. An image display device according to claim 8,
A system for generating image data based on image information to be displayed, and outputting the image data to the image display device.