JP2018186308A - Field-effect transistor, display element, image display device, and system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a field-effect transistor that is small in fluctuation amount of a threshold voltage to a BTS test, and that exhibits high reliability.SOLUTION: A field-effect transistor comprises: a base material; a protection layer; a gate insulating layer formed between the base material and the protection layer; a source electrode and a drain electrode formed so as to be contacted with the gate insulating layer; a semiconductor layer formed at least between the source electrode and the drain electrode, and contacted with the gate insulating layer, the source electrode, and the drain electrode; and a gate electrode contacted with the gate insulating layer, and opposed to the semiconductor layer via the gate insulating layer. The protection layer has: a first protection layer that contains a first composite metal oxide containing Si and an alkali earth metal; and a second protection layer formed so as to be contacted with the first protection layer, and that contains a second composite metal oxide containing an alkali earth metal and a rare-earth element.SELECTED DRAWING: Figure 3A

Description

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

  A field effect transistor (FET) is a principle in which an electric field is applied to a gate electrode, and a gate (gate) is provided for the flow of electrons or holes by the electric field of a channel, and a current between a source electrode and a drain electrode. It is a transistor that controls

  The FET is used as a switching element, an amplifying element or the like because of its characteristics. Since the FET has a low gate current and a planar structure, the FET is easier to manufacture and integrate than a bipolar transistor. For this reason, the FET is an indispensable element in an integrated circuit used in current electronic equipment. The FET is applied to, for example, an active matrix display as a thin film transistor (TFT).

  In recent years, a liquid crystal display, an organic EL (electroluminescence) display, an electronic paper, and the like have been put into practical use as a flat panel display (FPD).

  These FPDs are driven by a drive circuit including a TFT using amorphous silicon, polycrystalline silicon or the like as an active layer. Further, the FPD is required to have a larger size, higher definition, higher image quality, and higher speed driveability. Accordingly, the carrier mobility is high, the on / off ratio is high, and the characteristics change with time. There is a demand for TFTs that are small and have little variation between elements.

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

The TFT is required to have a small threshold voltage variation.
One of the factors that change the threshold voltage of the TFT is that moisture, hydrogen, oxygen, etc. contained in the atmosphere are adsorbed 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, etc. contained in the atmosphere.
Further, the threshold voltage also varies when the TFT is repeatedly turned on and off for a long time and many times. A BTS (Bias Stress Temperature) test is widely performed as a method for evaluating the fluctuation of the threshold voltage in such a long time and many times of driving. In this test, a voltage is applied between the gate electrode and the source electrode of a field effect transistor for a certain period of time, and the threshold voltage fluctuation at that time is evaluated, or between the gate electrode and the source electrode and between the drain electrode and the source electrode. In this method, voltage is continuously applied for a certain period of time, and the fluctuation of the threshold voltage is evaluated.
Several protective layers have been disclosed in order to suppress variations in 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 has been reported that the field effect transistor with this protective layer formed can be operated stably without being influenced by the atmosphere such as vacuum and air. However, data regarding the BTS test is not disclosed.
In addition, 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 has been reported that a field effect transistor having this protective layer can suppress fluctuations in transistor characteristics by preventing impurities such as moisture and oxygen from entering the semiconductor layer. However, data regarding the BTS test is not 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 has been reported that the field effect transistor using the laminated film as a protective layer can prevent moisture from being mixed and adsorbed to the semiconductor layer, and the transistor characteristics do not change even after a storage test in a high temperature and high humidity environment. However, data regarding the BTS test is not disclosed.
Also disclosed is a field effect transistor using 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 laminated film thereof as a protective layer. (For example, see Patent Document 4). It has been reported that a field effect transistor in which these protective layers are formed can suppress desorption of oxygen from an oxide semiconductor and can improve reliability. However, data regarding the BTS test is not disclosed.
Further, a field effect transistor using Al ₂ O ₃ as a protective layer is disclosed (for example, see Non-Patent Document 2). Regarding the field effect transistor with this protective layer formed, the result of reliability evaluation by the BTS test has been reported. However, the amount of fluctuation of the threshold voltage (ΔVth) with respect to the stress time passage is large, and the reliability of the field effect transistor is low. It cannot be said that it is sufficiently secured.
In any of the above-described techniques, the reliability evaluation in the BTS test is not sufficient.

  Therefore, at present, there is a demand for providing a field effect transistor that exhibits a small amount of variation in threshold voltage with respect to the BTS test and exhibits high reliability.

  An object of the present invention is to solve the above-described problems 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 variation in threshold voltage with respect to a BTS (Bias Stress Temperature) test and exhibits high reliability.

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

  According to the present invention, the above-described problems can be solved, and a field effect transistor having a small threshold voltage variation with respect to the BTS test and high reliability can be provided.

FIG. 1 is a diagram for explaining an image display apparatus. 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 an organic EL element. FIG. 5 is a schematic configuration diagram showing an example of the display element of the present invention. FIG. 6 is a schematic configuration diagram showing another example of the display element of the present invention. FIG. 7 is a diagram for explaining 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. 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 with Vgs = + 20 V and Vds = 0 V. FIG. 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 of the field effect transistor obtained in Example 12. 12 is a graph showing an evaluation of transistor characteristics (Vgs−Ids) in a BTS test of the field effect transistor obtained in Example 12 with Vgs = −20 V and Vds = 0 V. FIG. FIG. 13 is a graph showing an evaluation of transistor characteristics (Vgs−Ids) in the BTS test of the field effect transistor obtained in Example 12 with Vgs = −20 V and Vds = + 20 V. FIG. 14 is a graph evaluating the stress time change of ΔVth in the 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 produced 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, and, if necessary, other members. Have

<Base material>
There is no restriction | limiting in particular as a shape, a structure, and a magnitude | size of the said base material, According to the objective, it can select suitably.
There is no restriction | limiting in particular as a material of the said base material, According to the objective, it can select suitably, For example, a glass base material, a plastic base material, etc. are mentioned.
There is no restriction | limiting in particular as said glass base material, According to the objective, it can select suitably, For example, an alkali free glass, silica glass, etc. are mentioned.
There is no restriction | limiting in particular as said plastic base material, According to the objective, it can select suitably, For example, a polycarbonate (PC), a polyimide (PI), a polyethylene terephthalate (PET), a polyethylene naphthalate (PEN) etc. are mentioned. It is done.
The base material is preferably subjected to pretreatment such as oxygen plasma, UV ozone, and UV irradiation cleaning in terms of surface cleaning and adhesion improvement.

<Protective layer>
The protective layer is usually formed above the base material.
The protective layer includes 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 purpose. The first protective layer is the first protective layer. The second protective layer may be disposed closer to the base material, and the second protective layer may be disposed closer to the base material than the first protective layer. The second protective layer may be disposed so as to cover the upper surface and the side surface of the first protective layer, and the first protective layer so as to cover the upper surface and the side surface of the second protective layer. May be arranged.

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

--First mixed metal oxide--
The first composite metal oxide contains Si (silicon) and an alkaline earth metal, preferably contains at least one of Al (aluminum) and B (boron), and further if necessary. Contains other ingredients.

In the first composite metal oxide, SiO ₂ formed of Si forms an amorphous structure. The alkaline earth metal has a function of cutting the Si—O bond. Therefore, it is possible to control the relative dielectric constant and the linear expansion coefficient of the first composite metal oxide formed by the composition ratio of the Si and the alkaline earth metal.

The first composite metal oxide preferably contains at least one of Al and B. Al ₂ O ₃ formed of Al and B ₂ O ₃ formed of B form an amorphous structure in the same manner as SiO _2, and thus are more stable in the first composite metal oxide. Thus, an amorphous structure can be obtained, and a more uniform insulating film can be formed. In addition, since the alkaline earth metal changes the coordination structure of Al and B depending on its composition ratio, the relative permittivity and linear expansion coefficient of the first composite metal oxide to be formed can be controlled. 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 individually by 1 type and may use 2 or more types together.

The composition ratio between 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 in the following range. .
In the first composite metal oxide, the composition ratio between the Si and the alkaline earth metal (Si: the alkaline earth metal) includes oxides (SiO ₂ , BeO, MgO, CaO, SrO, In terms of BaO), 50.0 mol% to 90.0 mol%: 10.0 mol% to 50.0 mol% is preferable.

The composition ratio of the Si, the alkaline earth metal, and at least one of the 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, the composition ratio of Si, the alkaline earth metal, and at least one of Al and B (Si: the alkaline earth metal: at least of Al and B) the one), oxides _{(SiO 2, BeO, MgO,} CaO, SrO, BaO, with _{Al 2 O 3, B 2 O} 3) in terms of, 50.0mol% ~90.0mol%: 5.0mol% ~ 20.0 mol%: 5.0 mol% to 30.0 mol% is preferable.

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

There is no restriction | limiting in particular as a dielectric constant of said 1st protective layer, According to the objective, it can select suitably.
The relative dielectric constant can be measured using, for example, an LCR meter or the like by fabricating a capacitor in which a lower electrode, a dielectric layer (the protective layer), and an upper electrode are stacked.

There is no restriction | limiting in particular as a linear expansion coefficient of said 1st protective layer, According to the objective, it can select suitably.
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 that of the protective layer, without preparing 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 complex metal oxide--
The second composite metal oxide contains at least an alkaline earth metal and a rare earth element, preferably contains at least one of Zr (zirconium) and Hf (hafnium), and if necessary, Contains other ingredients.

The second composite metal oxide is stable in the atmosphere and can stably form an amorphous structure in a wide composition range. This is because the present inventors have found that a complex metal oxide system containing an alkaline earth metal and a rare earth element is stable in the atmosphere and can stably form an amorphous structure in a wide composition range. By finding out what can be done.
In general, simple oxides of alkaline earth metals easily react with moisture and carbon dioxide in the atmosphere, easily form hydroxides and carbonates, and are not suitable for application to electronic devices alone. . Further, simple oxides of rare earth elements are easily crystallized, and leakage current becomes a problem when considering application to electronic devices. 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 exists stably in a wide composition range, the relative dielectric constant and the linear expansion coefficient of the second composite metal oxide to be formed are widely controlled by the composition ratio. can do.

  The second composite metal oxide preferably 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 individually by 1 type and may use 2 or more types together.

  In the second composite metal oxide, the rare earth elements include 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) Can be mentioned.

The composition ratio between 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, the composition ratio of the alkaline earth metal to the rare earth element (the alkaline earth metal: the rare earth element) includes oxides (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% to 90.0 mol% is 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. However, the following range is preferable.
In the second composite metal oxide, the composition ratio of the alkaline earth metal, the rare earth element, and at least one of the Zr and the 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 in _{Lu 2 O 3, ZrO 2,} HfO 2) terms, 5.0mol% ~22.0mol%: 33.0mol% ~90.0mol: 5.0mol% ~45.0mol% is preferred.

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 ), for example, the cation of the oxide by fluorescent X-ray analysis, electron microanalysis (EPMA), dielectric coupled plasma emission spectroscopy (ICP-AES), etc. It can be calculated by analyzing the elements.

There is no restriction | limiting in particular as a dielectric constant of said 2nd protective layer, According to the objective, it can select suitably.
The relative dielectric constant of the second protective layer can be measured, for example, by the same method as the relative dielectric constant of the first protective layer.

There is no restriction | limiting in particular as a linear expansion coefficient of said 2nd protective layer, According to the objective, it can select suitably.
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 inventors laminate the first protective layer containing the first composite metal oxide and the second protective layer containing the second composite metal oxide. Thus, it was found that the formed protective layer exhibits excellent barrier properties against moisture, oxygen, and hydrogen in the atmosphere.
Therefore, a field effect transistor exhibiting high reliability can be provided by using the protective layer.

-Method for forming first protective layer and second protective layer-
There is no restriction | limiting in particular as a formation method of said 1st protective layer and said 2nd protective layer, According to the objective, it can select suitably, For example, a sputtering method, a pulse laser deposition (PLD) method, Examples include a method of patterning by photolithography after film formation by a vacuum process such as chemical vapor deposition (CVD) or atomic layer deposition (ALD).
In addition, the first protective layer is prepared by applying a coating liquid (first protective layer forming coating liquid) containing the first composite metal oxide precursor and applying or coating the coating liquid on the object to be coated. A film can also be formed by printing and baking under appropriate conditions. Similarly, the second protective layer is prepared by coating a coating liquid (second coating liquid for forming a protective layer) containing the precursor of the second composite metal oxide, and coating the coating liquid on the object to be coated. Alternatively, the film can also be formed by printing and baking under appropriate conditions.

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

--First protective layer forming coating solution (first insulating film forming coating solution)-
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 boron-containing compounds, and further contains other components as necessary.

  In recent years, the development of printed electronics using a coating process capable of reducing the cost for a vacuum process that requires expensive equipment such as a sputtering method, a CVD method, and a dry etching method has become active. With regard to the protective layer of the semiconductor, studies have been reported to form it by coating using polysilazane (see, for example, JP 2010-103203 A), spin-on glass, or the like.

However, a coating liquid composed only of a SiO ₂ precursor such as polysilazane and spin-on-glass needs to be baked at 450 ° C. or higher in order to decompose organic substances and obtain a dense insulating film. In order to decompose the organic substance at a temperature lower than that, it is different from heating such as microwave treatment (see, for example, JP-A-2010-103203), use of a catalyst, and firing in a steam atmosphere (Japanese Patent No. 3666915). It is indispensable to use a combination of these means for promoting the reaction. Therefore, the firing process is complicated, the cost is increased, and the insulation is deteriorated due to remaining impurities. On the other hand, since the first coating liquid for forming the protective layer contains a precursor of an alkaline earth metal oxide having a lower decomposition temperature than the SiO ₂ precursor, it is more than the coating liquid consisting only of the SiO ₂ precursor. It is possible to decompose the precursor at a low temperature, that is, a temperature lower than 450 ° C., and form a dense insulating film. Further, like the alkaline earth metal oxide precursor, it further contains 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, so that it is dense at a low temperature. It is possible to enhance the effect of forming an insulating film.

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

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

  The organosilicon compound is not particularly limited as long as it is a compound having silicon and an organic group, and can be appropriately selected according to 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 intended 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 acyloxy group which may have a phenyl group and a phenyl group which may have a substituent. As said alkyl group, a C1-C6 alkyl group etc. are mentioned, for example. As said alkoxy group, a C1-C6 alkoxy group etc. are mentioned, for example. As said acyloxy group, a C1-C10 acyloxy group etc. are mentioned, for example.

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

  There is no restriction | limiting in particular as content of the said silicon containing compound in said 1st coating liquid for protective layer formation, According to the objective, it can select suitably.

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

Examples of the inorganic alkaline earth metal compound include alkaline earth metal nitrates, alkaline earth metal sulfates, alkaline earth metal chlorides, alkaline earth metal fluorides, alkaline earth metal bromides, alkaline earth metal salts, and the like. 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, and barium sulfate.
Examples of the alkaline earth metal chloride include magnesium chloride, calcium chloride, strontium chloride, and barium chloride.
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, barium bromide and the like.
Examples of the alkaline earth metal iodide include magnesium iodide, calcium iodide, strontium iodide, barium iodide and the like.

  The organic alkaline earth metal compound is not particularly limited as long as it is a compound having an alkaline earth metal and an organic group, and can be appropriately selected 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 intended 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 substituent, 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, etc. Can be mentioned. As said alkyl group, a C1-C6 alkyl group etc. are mentioned, for example. As said alkoxy group, a C1-C6 alkoxy group etc. are mentioned, for example. 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 oxalic acid and acyloxy groups having two or more carbonyl groups such as citric acid.

  Examples of the organic alkaline earth metal compound include magnesium methoxide, magnesium ethoxide, diethyl magnesium, magnesium acetate, magnesium formate, acetylacetone magnesium, 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, acetylacetone calcium, calcium dipivaloylmethanate, calcium 2-ethylhexanoate, lactic acid Calcium, calcium naphthenate, calcium citrate, calcium salicylate, calcium neodecanoate, Calcium benzoate, calcium oxalate, strontium isopropoxide, strontium acetate, strontium formate, acetylacetone strontium, strontium 2-ethylhexanoate, strontium lactate, strontium naphthenate, strontium salicylate, strontium oxalate, barium ethoxide, barium iso Examples include propoxide, barium acetate, barium formate, acetylacetone barium, barium 2-ethylhexanoate, barium lactate, barium naphthenate, barium neodecanoate, barium oxalate, barium benzoate, and barium trifluoromethanesulfonate.

  There is no restriction | limiting in particular as content of the said alkaline-earth metal containing compound in said 1st coating liquid for protective layer formation, According to the objective, it can select suitably.

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

  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 ammonium ammonium sulfate. .

  The organoaluminum compound is not particularly limited as long as it is a compound having aluminum and an organic group, and can be appropriately selected according to 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 intended 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 acyloxy 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. As said alkyl group, a C1-C6 alkyl group etc. are mentioned, for example. As said alkoxy group, a C1-C6 alkoxy group etc. are mentioned, for example. 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 oxalic acid and acyloxy groups having two or more carbonyl groups such as citric acid.

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

  There is no restriction | limiting in particular as content of the said aluminum containing compound in said 1st coating liquid for protective layer formation, According to the objective, it can select suitably.

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

  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 according to 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 intended 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 substituent, a phenyl group which may have a substituent, a sulfonic acid group which may have a substituent, a thiophene group which may have a substituent, and the like. . As said alkyl group, a C1-C6 alkyl group etc. are mentioned, for example. As said alkoxy group, a C1-C6 alkoxy group etc. are mentioned, for example. The alkoxy group has two or more oxygen atoms, and two of the two or more oxygen atoms are bonded to boron and form a ring structure together with boron. Groups are also included. Moreover, the alkoxy group by which the alkyl group contained in the said alkoxy group was substituted by the organic silyl group is also included. As said acyloxy group, a C1-C10 acyloxy group etc. are mentioned, for example.

  Examples of the organic boron compound include (R) -5,5-diphenyl-2-methyl-3,4-propano-1,3,2-oxazaborolidine, triisopropyl borate, 2-isopropoxy- 4,4,5,5-tetramethyl-1,3,2-dioxaborolane, bis (hexylene glycolato) 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.

  There is no restriction | limiting in particular as content of the said boron containing compound in said 1st coating liquid for protective layer formation, According to the objective, it can select suitably.

--- 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 according to the purpose. For example, toluene, xylene, mesitylene, cymene, pentylbenzene, dodecyl 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, and water.

  There is no restriction | limiting in particular as content of the said solvent in said 1st coating liquid for protective layer formation, According to the objective, it can select suitably.

The composition ratio of the silicon-containing compound to 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. Although it can select suitably according to the objective, it is preferable that it is the following ranges.
In the first protective layer forming coating solution, the composition ratio of Si to the alkaline earth metal (Si: the alkaline earth metal) includes oxides (SiO ₂ , BeO, MgO, CaO, In terms of (SrO, BaO), 50.0 mol% to 90.0 mol%: 10.0 mol% to 50.0 mol% is preferable.

The composition ratio of the silicon-containing compound, the alkaline earth metal-containing compound, and 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, but is preferably in the following range.
In the first protective layer forming coating solution, the composition ratio of Si, the alkaline earth metal, and at least one of Al and B (Si: alkaline earth metal: Al and B) as at least one), oxide _{(SiO 2, BeO, MgO,} CaO, SrO, BaO, with _{Al 2 O 3, B 2 O} 3) in terms of, 50.0mol% ~90.0mol%: 5.0mol % To 20.0 mol%: 5.0 mol% to 30.0 mol% is preferable.

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

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

Examples of the inorganic alkaline earth metal compound include alkaline earth metal nitrates, alkaline earth metal sulfates, alkaline earth metal chlorides, alkaline earth metal fluorides, alkaline earth metal bromides, alkaline earth metal salts, and the like. 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, and barium sulfate.
Examples of the alkaline earth metal chloride include magnesium chloride, calcium chloride, strontium chloride, and barium chloride.
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, barium bromide and the like.
Examples of the alkaline earth metal iodide include magnesium iodide, calcium iodide, strontium iodide, barium iodide and the like.

  The organic alkaline earth metal compound is not particularly limited as long as it is a compound having an alkaline earth metal and an organic group, and can be appropriately selected 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 intended 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 substituent, 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, etc. Can be mentioned. As said alkyl group, a C1-C6 alkyl group etc. are mentioned, for example. As said alkoxy group, a C1-C6 alkoxy group etc. are mentioned, for example. 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 oxalic acid and acyloxy groups having two or more carbonyl groups such as citric acid.

  Examples of the organic alkaline earth metal compound include magnesium methoxide, magnesium ethoxide, diethyl magnesium, magnesium acetate, magnesium formate, acetylacetone magnesium, 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, acetylacetone calcium, calcium dipivaloylmethanate, calcium 2-ethylhexanoate, lactic acid Calcium, calcium naphthenate, calcium citrate, calcium salicylate, calcium neodecanoate, Calcium benzoate, calcium oxalate, strontium isopropoxide, strontium acetate, strontium formate, acetylacetone strontium, strontium 2-ethylhexanoate, strontium lactate, strontium naphthenate, strontium salicylate, strontium oxalate, barium ethoxide, barium iso Examples include propoxide, barium acetate, barium formate, acetylacetone barium, barium 2-ethylhexanoate, barium lactate, barium naphthenate, barium neodecanoate, barium oxalate, barium benzoate, and barium trifluoromethanesulfonate.

  There is no restriction | limiting in particular as content of the said alkaline-earth metal containing compound in said 2nd coating liquid for protective layer formation, According to the objective, it can select suitably.

---- Rare earth element-containing compound ---
As the rare earth element in the rare earth element-containing compound, 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), and Lu (lutetium).

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

As said inorganic rare earth element compound, rare earth element nitrate, rare earth element sulfate, rare earth element fluoride, rare earth element chloride, rare earth element bromide, rare earth element iodide etc. are mentioned, for example.
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 sulfate 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. Examples include thulium, ytterbium sulfate, and lutetium sulfate.
Examples of the rare earth element fluoride include scandium fluoride, yttrium fluoride, lanthanum fluoride, cerium fluoride, praseodymium fluoride, neodymium fluoride, samarium fluoride, europium fluoride, gadolinium fluoride, terbium fluoride, Examples include dysprosium fluoride, holmium fluoride, erbium fluoride, thulium fluoride, ytterbium fluoride, and lutetium fluoride.
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, odor 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, Examples thereof include dysprosium iodide, holmium iodide, erbium iodide, thulium iodide, ytterbium iodide, lutetium iodide, and the like.

  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 according to 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 intended 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 acyloxy group which may have a substituent, an acetylacetonate group which may have a substituent, a cyclopentadienyl group which may have a substituent, and the like. As said alkyl group, a C1-C6 alkyl group etc. are mentioned, for example. As said alkoxy group, a C1-C6 alkoxy group etc. are mentioned, for example. As said acyloxy group, a C1-C10 acyloxy group etc. are mentioned, for example.

  Examples of the organic rare earth element compound include scandium isopropoxide, scandium acetate, tris (cyclopentadienyl) scandium, yttrium isopropoxide, yttrium 2-ethylhexanoate, tris (acetylacetonato) yttrium, and tris (cyclohexane). Pentadienyl) yttrium, lanthanum isopropoxide, lanthanum 2-ethylhexanoate, tris (acetylacetonato) lanthanum, tris (cyclopentadienyl) lanthanum, cerium 2-ethylhexanoate, tris (acetylacetonato) cerium, Tris (cyclopentadienyl) cerium, praseodymium isopropoxide, praseodymium oxalate, tris (acetylacetonato) praseodymium, tris (cyclopentadienyl) praseo , Neodymium isopropoxide, neodymium 2-ethylhexanoate, neodymium trifluoroacetylacetonate, tris (isopropylcyclopentadienyl) neodymium, tris (ethylcyclopentadienyl) promethium, samarium isopropoxide, 2-ethylhexane Samarium acid, tris (acetylacetonato) samarium, tris (cyclopentadienyl) samarium, europium 2-ethylhexanoate, tris (acetylacetonato) europium, tris (ethylcyclopentadienyl) europium, gadolinium isopropoxide, 2-ethylhexanoate gadolinium, 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, Examples include lutetium oxalate and tris (ethylcyclopentadienyl) lutetium.

  There is no restriction | limiting in particular as content of the said rare earth element containing compound in said 2nd coating liquid for protective layer formation, According to the objective, it can select suitably.

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

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

  The organic zirconium compound is not particularly limited as long as it is a compound having zirconium and an organic group, and can be appropriately selected according to 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 intended 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 acyloxy group which may have a substituent, an acetylacetonate group which may have a substituent, a cyclopentadienyl group which may have a substituent, and the like. As said alkyl group, a C1-C6 alkyl group etc. are mentioned, for example. As said alkoxy group, a C1-C6 alkoxy group etc. are mentioned, for example. As said acyloxy group, a C1-C10 acyloxy group etc. are mentioned, for example.

  Examples of the organic zirconium compound include zirconium butoxide, zirconium isopropoxide, zirconium 2-ethylhexanoate, zirconium di (n-butoxide) bisacetylacetonate, tetrakis (acetylacetonate) zirconium, tetrakis (cyclopentadienyl). ) Zirconium and the like.

  There is no restriction | limiting in particular as content of the said zirconium containing compound in said 2nd coating liquid for protective layer formation, According to the objective, it can select suitably.

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

  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 is a compound having hafnium and an organic group, and can be appropriately selected according to 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 intended 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 acyloxy group which may have a substituent, an acetylacetonate group which may have a substituent, a cyclopentadienyl group which may have a substituent, and the like. As said alkyl group, a C1-C6 alkyl group etc. are mentioned, for example. As said alkoxy group, a C1-C6 alkoxy group etc. are mentioned, for example. As said acyloxy group, a C1-C10 acyloxy group etc. are mentioned, for example.

  Examples of the organic hafnium compounds include hafnium butoxide, hafnium isopropoxide, hafnium 2-ethylhexanoate, hafnium di (n-butoxide) bisacetylacetonate, tetrakis (acetylacetonate) hafnium, and bis (cyclopentadienyl) dimethyl. Examples include hafnium.

  There is no restriction | limiting in particular as content of the said hafnium containing compound in said 2nd coating liquid for protective layer formation, According to the objective, it can select suitably.

--- 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 according to the purpose. For example, toluene, xylene, mesitylene, cymene, pentylbenzene, dodecyl 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, and water.

  There is no restriction | limiting in particular as content of the said solvent in said 2nd coating liquid for protective layer formation, According to the objective, it can select suitably.

The composition ratio of the alkaline earth metal-containing compound and the rare earth element-containing compound in the second protective layer forming coating solution (the alkaline earth metal-containing compound: the rare earth element-containing compound) is particularly limited. However, the following range is preferable.
In the second coating liquid for forming a protective layer, the 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, 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 preferable.

The composition ratio of the alkaline earth metal-containing compound, the rare earth element-containing compound, the zirconium-containing compound, and the hafnium-containing compound in the second protective layer-forming coating solution (containing the alkaline earth metal The 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 may be appropriately selected depending on the intended purpose, but is preferably in the following range. .
In the second protective layer forming coating solution, the composition ratio of the alkaline earth metal, the rare earth element, and at least one of the Zr and the Hf (the alkaline earth metal: the rare earth element: the Zr and The 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 may be used as the oxide of Hf. 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 In terms of O ₃ , Lu ₂ O ₃ , ZrO ₂ , HfO ₂ ), 5.0 mol% to 22.0 mol%: 33.0 mol% to 90.0 mol: 5.0 mol% to 45.0 mol% are preferable.

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

  The coating step is not particularly limited as long as it is a step of applying the first protective layer-forming coating solution or the second protective layer-forming coating solution to an object to be coated. You can choose. The application method is not particularly limited and may be appropriately selected depending on the purpose. For example, the method may be a method of patterning by photolithography after film formation by a solution process, or a printing method such as inkjet, nanoimprint, or gravure. And a method of directly forming 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 solution or the second protective layer forming coating solution applied to the article to be coated. It can be selected as appropriate according to the conditions. When the heat treatment is performed, the first protective layer forming coating solution or the second protective layer forming coating solution applied to the object to be coated 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, the solvent is dried (hereinafter referred to as “drying process”), and the first composite metal oxide or the second composite metal oxide is formed (hereinafter referred to as “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. At the time of producing the first composite metal oxide, for example, at least any decomposition of the silicon-containing compound, the alkaline earth metal-containing compound, the aluminum-containing compound, and the boron-containing compound occurs. When producing 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.

  There is no restriction | limiting in particular as temperature of the said drying process, According to the solvent to contain, it can select suitably, For example, 80 to 180 degreeC is mentioned. In the drying, it is effective to use a vacuum oven or the like for lowering the temperature. There is no restriction | limiting in particular as time of the said drying process, According to the objective, it can select suitably, For example, 10 minutes-1 hour are mentioned.

  There is no restriction | limiting in particular as temperature of the said production | generation process, Although it can select suitably according to the objective, 100 degreeC or more and less than 450 degreeC are preferable, and 200 to 400 degreeC is more preferable. There is no restriction | limiting in particular as time of the said production | generation process, According to the objective, it can select suitably, For example, 1 hour-5 hours are mentioned.

  In the heat treatment step, the drying treatment and the generation treatment may be performed continuously, or may be divided into a plurality of steps.

  There is no restriction | limiting in particular as the method of the said heat processing, According to the objective, it can select suitably, For example, the method etc. which heat the said to-be-coated article are mentioned. There is no restriction | limiting in particular as atmosphere in the said heat processing, Although it can select suitably according to the objective, 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 generation of the first composite metal oxide or the second composite metal oxide can be promoted.

  In the heat treatment, irradiating the material after the drying treatment with ultraviolet light having a wavelength of 400 nm or less is effective in promoting the reaction of the generation treatment. By irradiating ultraviolet light having a wavelength of 400 nm or less, chemical bonds such as organic substances contained in the material after the drying treatment can be broken and the organic substances 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 may be appropriately selected depending on the intended purpose. Examples thereof include ultraviolet light having a wavelength of 222 nm using an excimer lamp. Moreover, it is also preferable to provide ozone instead of or in combination with the irradiation with ultraviolet light. By applying the ozone to the substance after the drying treatment, generation of oxide is promoted.

<Gate insulation 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 according to the purpose.
The material of the gate insulating layer is not particularly limited and can be appropriately selected according to the purpose. For example, SiO ₂ , SiN _x , Al ₂ O _{3 and the} like, which are already widely used in mass production, Examples thereof include high dielectric constant materials such as La ₂ O ₃ and HfO ₂ , and organic materials such as polyimide (PI) and fluorine-based resin.

-Formation method of gate insulating layer-
There is no restriction | limiting in particular as a formation method of the said gate insulating layer, According to the objective, it can select suitably, For example, vacuum film-forming methods, such as sputtering, chemical vapor deposition (CVD), and atomic layer deposition (ALD) , Printing methods such as spin coating, die coating, and inkjet.

  There is no restriction | limiting in particular as an average film thickness of the said gate insulating layer, Although it can select suitably according to the objective, 50 nm-3 micrometers are preferable, and 100 nm-1 micrometer are more preferable.

<Source electrode and drain electrode>
The source electrode and the drain electrode are not particularly limited as long as they are electrodes for taking out current from the field effect transistor, and can be appropriately selected according to the purpose.
The source electrode and the drain electrode are formed 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 according to the purpose. For example, metals such as Mo, Al, Au, Ag, Cu, and alloys thereof, indium oxide Examples thereof include transparent conductive oxides such as tin (ITO) and antimony-doped tin oxide (ATO), and organic conductors such as polyethylenedioxythiophene (PEDOT) and polyaniline (PANI).

-Method for forming source electrode and drain electrode-
A method for forming the source electrode and the drain electrode is not particularly limited and may be appropriately selected depending on the purpose. Examples thereof include a patterning method, and (ii) a method of directly forming a desired shape by a printing process such as inkjet, nanoimprint, and gravure.

  There is no restriction | limiting in particular as an average film thickness of the said source electrode and the said drain electrode, Although it can select suitably according to the objective, 20 nm-1 micrometer are preferable and 50 nm-300 nm are more preferable.

<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 together with the source electrode and the drain electrode so that the field effect transistor functions. It can be selected as appropriate according to the conditions.
The semiconductor layer is in contact with the gate insulating layer, the source electrode, and the drain electrode.
There is no restriction | limiting in particular as a material of the said semiconductor layer, According to the objective, it can select suitably, For example, a silicon semiconductor, an oxide semiconductor etc. are mentioned.
Examples of the silicon semiconductor include amorphous silicon and polycrystalline silicon.
Examples of the oxide semiconductor include InGa—Zn—O, In—Zn—O, In—Mg—O, and the like.
Among these, an oxide semiconductor is preferable.

-Semiconductor layer formation method-
There is no restriction | limiting in particular as a formation method of the said semiconductor layer, According to the objective, it can select suitably, For example, a sputtering method, a pulse laser deposition (PLD) method, a chemical vapor deposition (CVD) method, an atomic layer After forming a film by a vacuum process such as an evaporation (ALD) method or a solution process such as dip coating, spin coating, or die coating, a desired pattern is directly formed by a method such as patterning by photolithography, or a printing method such as inkjet, nanoimprint, or gravure. Examples include a method of forming a film.

  There is no restriction | limiting in particular as an average film thickness of the said semiconductor layer, Although it can select suitably according to the objective, 5 nm-1 micrometer are preferable and 10 nm-0.5 micrometer are more preferable.

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

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

  There is no restriction | limiting in particular as an average film thickness of the said gate electrode, Although it can select suitably according to the objective, 20 nm-1 micrometer are preferable and 50 nm-300 nm are more preferable.

There is no restriction | limiting in particular as said field effect transistor structure, According to the objective, it can select suitably, For example, the field effect transistor of the following structures, etc. are mentioned.
(1) The base material, the gate electrode formed on the base material, the gate insulating layer formed on the gate electrode, and 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 the first 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, and the second A field effect transistor having the 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), a top contact / bottom gate type (FIG. 3B), and the like.
Examples of the field effect transistor having the structure (2) include a bottom contact / top gate type (FIG. 3C), a top contact / top gate type (FIG. 3D), and the like.
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 a first protection. Layer 27b represents the second protective layer.

  The field effect transistor can be suitably used for a display element to be described later, but is not limited thereto, and 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 that drives 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 it is an element whose 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 Examples include (EC) elements, liquid crystal elements, electrophoretic elements, electrowetting elements, and the like.

<Drive circuit>
The driving circuit is not particularly limited as long as it is a circuit that has the field effect transistor of the present invention and drives the light control element, and can be appropriately selected according to the purpose.

<Other members>
There is no restriction | limiting in particular as said other member, According to the objective, it can select suitably.

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

(Image display device)
The image display device of the present invention 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 according to 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 field-effect transistor via the plurality of wirings according to the image data, and is appropriately selected according to the purpose. You can choose.

<Other members>
There is no restriction | limiting in particular as said other member, According to the objective, it can select suitably.

Since the image display device includes 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 display means in portable information devices such as mobile phones, portable music playback devices, portable video playback devices, electronic BOOK and PDA (Personal Digital Assistant), and imaging devices such as still cameras and video cameras. be able to. It can also be used as a display means for various information in a mobile system such as a car, an aircraft, a train, and a ship. Furthermore, it can also be used as a display device for various information in measuring devices, analyzers, medical devices, and advertising media.

(system)
The system of the present invention includes at least the image display device of the present invention and an image data creation 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 of the present invention will be described with reference to the drawings.
First, a television apparatus 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 employ, for example, the configurations described in paragraphs [0038] to [0058] and FIG. 1 of JP 2010-074148.

Next, the image display apparatus 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], FIG. 2, and FIG.

Next, the display element of the present invention will be described with reference to the drawings.
FIG. 1 is a diagram showing a display 310 in which display elements are arranged on a matrix.
As shown in FIG. 1, the display 310 includes n scanning lines (X0, X1, X2, X3,..., Xn-2, Xn-1) arranged at equal intervals along the X-axis direction. ), M data lines (Y0, Y1, Y2, Y3,..., Ym-1) arranged at equal intervals along the Y-axis direction, and arranged at equal 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 showing an example of the display element of the present invention.
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, as shown in FIG. That is, the display 310 is a so-called active matrix organic EL display. The display 310 is a color-compatible 32-inch display. The size is not limited to this.

The drive circuit 320 in FIG. 2 will be described.
The drive circuit 320 includes 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. The drain electrode D is connected to one terminal of the capacitor 13.

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

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

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

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

FIG. 4 is a schematic configuration diagram illustrating an example of an organic EL element.
In FIG. 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 may be appropriately selected depending on the purpose. For example, aluminum (Al), magnesium (Mg) -silver (Ag) alloy, aluminum (Al) -lithium (Li) An alloy, ITO (Indium Tin Oxide), etc. are mentioned. A magnesium (Mg) -silver (Ag) alloy becomes a high reflectance electrode if it is sufficiently thick, and a semitransparent electrode if it is an extremely thin film (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 semi-transparent electrode for the cathode.

  There is no restriction | limiting in particular as a material of the anode 314, According to the objective, it can select suitably, For example, ITO (Indium Tin Oxide), IZO (Indium Zinc Oxide), a silver (Ag) -neodymium (Nd) alloy, etc. Is mentioned. In addition, when a silver alloy is used, it becomes a high reflectance electrode and is suitable when taking out light from the cathode side.

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

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

  In FIG. 4, the case of a so-called “bottom emission” organic EL element that extracts light from the substrate side has been described as the light control element. However, the light control element is a “top” that extracts light from the side opposite to the substrate. It may be an “emission” organic EL element.

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

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

There is no restriction | limiting in particular as a material of the interlayer insulation layer 43 (planarization film | membrane), According to the objective, it can select suitably, For example, an organic material, an inorganic material, an organic inorganic composite material etc. are mentioned.
Examples of the organic material include resins such as polyimide, acrylic resin, fluorine resin, non-fluorine resin, olefin resin, and silicone resin, and photosensitive resin 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 an organic-inorganic composite compound composed of a silane compound disclosed in a patent document (Japanese Patent Laid-Open No. 2007-158146).
The interlayer insulating layer preferably has a barrier property against moisture, oxygen, and hydrogen in the atmosphere.

The process for forming the interlayer insulating layer is not particularly limited and can be appropriately selected depending on the purpose. And a method of patterning by a photolithography method for a photosensitive material.
It is also effective to stabilize the characteristics of the field-effect transistor constituting the display element by performing a heat treatment as a post-process after the formation of the interlayer insulating layer.

  There is no restriction | limiting in particular as a preparation method of the organic EL layer 44 and the cathode 45, According to the objective, it can select suitably, For example, vacuum film-forming methods, such as a vacuum evaporation method and a sputtering method, an inkjet, a nozzle coat, etc. Examples include solution process.

  Thereby, a display element which is a so-called “bottom emission” organic EL element in which light emission is extracted from the substrate side can be produced. In this case, the base material 31, the gate insulating layer 34, and the second drain electrode (anode) 38 are required to be transparent.

Furthermore, in FIG. 5, the configuration in which the organic EL element 350 is disposed beside the drive circuit 320 has been described. However, as illustrated in FIG. 6, the organic EL element 350 may be disposed above the drive circuit 320. Good. Also in this case, so-called “bottom emission” in which light emission is extracted from the substrate side, and the drive circuit 320 is required to be transparent. The source / drain electrodes and the anode are transparent conductive materials such as ITO, In ₂ O ₃ , SnO ₂ , ZnO, ZnO added with Ga, ZnO added with Al, SnO ₂ added with Sb, etc. It is preferable to use an oxide.

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

  The image data processing circuit 402 determines the luminance 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 voltages to the n scanning lines in accordance with an instruction from the image data processing circuit 402.

  The data line driving circuit 406 individually applies voltages to the m data lines in accordance with an instruction from the image data processing circuit 402.

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

  In the above-described embodiment, the case of so-called “bottom emission” in which light emission is extracted from the substrate side has been described, but the present invention is not limited to this. For example, a high reflectivity electrode such as silver (Ag) -neodymium (Nd) alloy is used for the anode 314, and a semitransparent 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 the material.

  Moreover, although the said embodiment demonstrated the case where a light control element was an organic EL element, it is not limited to this, For example, a light control element may be an electrochromic element. In this case, the display 310 is an electrochromic display.

  The light control element may be a liquid crystal element. In this case, the display 310 is a liquid crystal display. As an example, as shown in FIG. 8, a current supply line for the display element 302 ′ is not necessary.

  In this case, as shown in FIG. 9 as an example, the drive circuit 320 ′ is composed of one field effect transistor 14 and a capacitor 15 similar to the field effect transistors (11, 12) described above. Can do. 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. Note that reference numerals 16 and 372 in FIG. 9 denote counter electrodes (common electrodes) of the liquid crystal element 370.

  In the embodiment, the light control element may be an electrophoretic element. The light control element may be an electrowetting element.

  Moreover, although the said embodiment demonstrated the case where a display respond | corresponds to a color, it is not limited to this.

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

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

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

(Example 1)
<Fabrication of field effect transistor>
-Preparation of first protective layer forming coating solution-
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 calcium 2-ethylhexanoate toluene solution (Ca content 4.9%) Strem 93-2014, manufactured by Strem Chemicals) 0.11 mL and 2-ethylhexanoic acid strontium toluene solution (Sr content 2%, Wako 195-09561, manufactured by Wako Chemical Co., Ltd.) 0.52 mL, A protective layer-forming coating solution was obtained. The first composite metal oxide formed by the first protective layer forming coating solution has the composition shown in Table 1-1.

−Preparation of second protective layer forming coating solution−
To 1 mL of toluene, 0.99 mL of 2-ethylhexanoic acid lanthanum toluene solution (La content 7%, Wako 122-033371, manufactured by Wako Chemical Co., Ltd.) and 2-ethylhexanoic acid strontium toluene solution (Sr content 2%, Wako 195) -09561, manufactured by Wako Chemical Co., Ltd.) (0.27 mL) was mixed to obtain a second protective layer forming coating solution. The second composite metal oxide formed by the second protective layer forming coating solution has the composition shown in Table 1-1.

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

-Formation of gate electrode-
First, the gate electrode 92 was formed on the 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 apparatus, 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 resist pattern was also removed to form a gate electrode 92 made of a Mo film.

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

-Formation of source and drain electrodes-
Next, the source electrode 94 and the 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 with an exposure apparatus, and development. Further, the Mo film in the region where the resist pattern was not formed was removed by RIE. Thereafter, the resist pattern was also removed to form a source electrode 94 and a drain electrode 95 made of a Mo film.

-Formation of oxide semiconductor layer-
Next, an oxide semiconductor 96 layer was formed. Specifically, an Mg—In-based oxide (In ₂ MgO ₄ ) film was formed by DC sputtering so that the average film thickness was about 100 nm. Thereafter, a photoresist was applied onto 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 apparatus, 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 so 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 onto the substrate and spin-coated under predetermined conditions (rotated at 3,000 rpm for 20 seconds and rotated to 0 rpm for 5 seconds) Stopped.) Subsequently, after drying at 120 ° C. for 1 hour in the air, firing is performed at 400 ° C. for 3 hours in an O ₂ atmosphere, and a first composite metal oxide film (first protection layer 97a is formed as the first protective layer 97a. Layer).
Subsequently, 0.4 mL of the second protective layer forming coating solution was dropped onto the first protective layer 97a and spin-coated under predetermined conditions (after rotating at 500 rpm for 5 seconds and then at 20 minutes at 3,000 rpm). The rotation was stopped so that the rotation was 0 rpm in 5 seconds). Subsequently, after drying at 120 ° C. for 1 hour in the air, firing is performed at 400 ° C. for 3 hours in an O ₂ atmosphere to form a second composite metal oxide film (second protection layer 97b). Layer) was formed on the first protective layer 97a. The average film 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 insulation layer-
Next, an interlayer insulating layer 98 was formed. Specifically, a positive-type photosensitive organic-inorganic composite material (ADEKA nanohybrid silicone FX series, manufactured by ADEKA) is applied onto the second protective layer 97b by spin coating, prebaked, exposed by an exposure apparatus, and developed. The desired pattern was obtained. Thereafter, post-baking was performed at 150 ° C. for 1 hour and at 200 ° C. for 1 hour.
Finally, as a heat treatment in a subsequent process, a heat treatment was performed at 230 ° C. for 1 hour to complete a field effect transistor. The average film thickness of the interlayer insulating layer was about 1,500 nm.

(Example 2)
<Fabrication of field effect transistor>
-Preparation of first protective layer forming coating solution-
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 magnesium 2-ethylhexanoate toluene solution (Mg content 3%, Strem 12-1260, manufactured by Strem Chemicals) 0.36 mL was mixed to obtain a first protective layer forming coating solution. The first composite metal oxide formed by the first protective layer forming coating solution has the composition shown in Table 1-1.

−Preparation of second protective layer forming coating solution−
To 1 mL of toluene, 0.26 g of yttrium 2-ethylhexanoate (Strem 39-2400, manufactured by Strem Chemicals), calcium toluene solution of 2-ethylhexanoate (Ca content: 4.9%, manufactured by Stream 93-2014, manufactured by Stream Chemicals) 0.05 mL, 2-ethylhexanoate strontium toluene solution (Sr content 2%, Wako 195-09561, manufactured by Wako Chemical Co., Ltd.) 0.22 mL, 2-ethylhexanoate barium toluene solution (Ba content 8%, Wako) (021-09471, manufactured by Wako Chemical Co., Ltd.) and 0.09 mL 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 solution has the composition shown in Table 1-1.

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

Example 3
<Fabrication of field effect transistor>
-Preparation of first protective layer forming coating solution-
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 calcium 2-ethylhexanoate toluene solution (Ca content 4.9%) , Strem 93-2014, manufactured by Strem Chemicals) 0.13 mL, 2-ethylhexanoic acid strontium toluene solution (Sr content 2%, Wako 195-09561, manufactured by Wako Chemical Co., Ltd.) 0.44 mL, 2-ethylhexanoic acid Barium toluene solution (Ba content 8%, Wako 021-0471, manufactured by Wako Chemical Co., Ltd.) 0.11 mL was 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 solution has the composition shown in Table 1-1.

−Preparation of second protective layer forming coating solution−
To 1 mL of toluene, 0.29 g of europium 2-ethylhexanoate (Strem 93-6611, manufactured by Strem Chemicals) and magnesium toluene solution of 2-ethylhexanoate (Mg content 3%, Stream 12-1260, manufactured by Strem Chemicals) 23 mL was mixed and the 2nd coating liquid for protective layer formation was obtained. The second composite metal oxide formed by the second protective layer forming coating solution has the composition shown in Table 1-1.

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

(Example 4)
<Fabrication of field effect transistor>
-Preparation of first protective layer forming coating solution-
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 calcium 2-ethylhexanoate toluene solution (Ca content 4.9%) , Strem 93-2014, manufactured by Strem Chemicals) 0.15 mL was 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 solution has the composition shown in Table 1-1.

−Preparation of second protective layer forming coating solution−
In 1 mL of toluene, 0.22 g of samarium acetylacetonate trihydrate (Strem 93-6226, manufactured by Strem Chemicals), gadolinium 2-ethylhexanoate toluene solution (Gd content 25%, Strem 64-3500, manufactured by Strem Chemicals) 0.05 mL, 2-ethylhexanoate calcium toluene solution (Ca content 4.9%, Strem 93-2014, manufactured by Strem Chemicals) 0.06 mL, 2-ethylhexanoate barium toluene solution (Ba content 8%, Wako) (021-09471, manufactured by Wako Chemical Co., Ltd.) and 0.09 mL 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 solution has the composition shown in Table 1-1.

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

(Example 5)
<Fabrication of field effect transistor>
-Preparation of first protective layer forming coating solution-
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 magnesium 2-ethylhexanoate toluene solution (Mg content 3%, Strem 12-1260, manufactured by Strem Chemicals) 0.10 mL and 2-ethylhexanoic acid strontium toluene solution (Sr content 2%, Wako 195-09561, manufactured by Wako Chemical Co., Ltd.) 0.38 mL are mixed to provide first protection. A layer forming coating solution was obtained. The first composite metal oxide formed by the first protective layer forming coating solution has the composition shown in Table 1-1.

−Preparation of second protective layer forming coating solution−
To 1 mL of toluene, 0.18 g of scandium (III) tris (2,2,6,6-tetramethyl-3,5-hebutanedionate) hydrate (SIGMA-ALDRICH 517607, manufactured by SIGMA-ALDRICH), 2 -0.26 g of yttrium ethylhexanoate (Strem 39-2400, manufactured by Strem Chemicals), 0.07 g of europium 2-ethylhexanoate (Strem 93-6611, manufactured by Strem Chemicals), and a solution of calcium 2-ethylhexanoate in toluene ( 0.06 mL of Ca content 4.9%, Strem 93-2014, manufactured by Strem Chemicals) and 2-ethylhexanoic acid barium toluene solution (Ba content 8%, Wako 021-0471, 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 solution has the composition shown in Table 1-1.

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

(Example 6)
<Fabrication of field effect transistor>
-Preparation of first protective layer forming coating solution-
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) .4%, Alfa 89349, manufactured by Alfa Aesar) 0.16 mL, 2-ethylhexanoic acid magnesium toluene solution (Mg content 3%, Strem 12-1260, manufactured by Strem Chemicals) 0.05 mL, and 2-ethylhexanoic acid barium toluene The solution (Ba content 8%, Wako 021-09471, manufactured by Wako Chemical Co., Ltd.) 0.12 mL was mixed to obtain a first protective layer forming coating solution. The second composite metal oxide formed by the first protective layer forming coating solution has the composition shown in Table 1-2.

−Preparation of second protective layer forming coating solution−
To 1 mL of toluene, neodymium 2-ethylhexanoate 2-ethylhexanoic acid solution (Nd content 12%, Strem 60-2400, manufactured by Strem Chemicals) 0.60 mL and 2-ethylhexanoic acid calcium toluene solution (Ca content 4.9) %, Strem 93-2014, manufactured by Strem Chemicals) 0.31 mL was 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 solution has the composition shown in Table 1-2.

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

(Example 7)
<Fabrication of field effect transistor>
-Preparation of first protective layer forming coating solution-
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 -1,3,2-dioxaborolane (Wako 325-41462, manufactured by Wako Chemical Co., Ltd.) 0.11 g, 2-ethylhexanoic acid magnesium toluene solution (Mg content 3%, Strem 12-1260, manufactured by Strem Chemicals) 09 mL and 0.25 mL of 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 second composite metal oxide formed by the first protective layer forming coating solution has the composition shown in Table 1-2.

−Preparation of second protective layer forming coating solution−
To 1 mL of toluene, 0.29 g of europium 2-ethylhexanoate (Strem 93-6611, 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 2-ethylhexanoate barium toluene solution (Ba content 8%, Wako 021-0471, manufactured by Wako Chemical Co., Ltd.) 0.08 mL 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 solution has the composition shown in Table 1-2.

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

(Example 8)
<Fabrication of field effect transistor>
-Preparation of first protective layer forming coating solution-
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) .4%, Alfa 89349, 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 2-ethyl hexanoic acid calcium toluene solution (Ca content 4.9%, Strem 93-2014, manufactured by Strem Chemicals) 0.27 mL 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 solution has the composition shown in Table 1-2.

−Preparation of second protective layer forming coating solution−
To 1 mL of toluene, 0.99 mL of 2-ethylhexanoic acid lanthanum toluene solution (La content 7%, Wako 122-033371, manufactured by Wako Chemical Co., Ltd.) and 2-ethylhexanoic acid magnesium toluene solution (Mg content 3%, Strem 12 -1260, manufactured by Strem Chemicals) 0.03 mL, strontium 2-ethylhexanoate toluene solution (Sr content 2%, Wako 195-09561, manufactured by Wako Chemical Co., Ltd.) 0.14 mL, and 2-ethylhexanoic acid barium toluene solution (Ba content 8%, Wako 021-0471, manufactured by Wako Chemical Co., Ltd.) 0.11 mL was mixed to obtain a second protective layer forming coating solution. The second composite metal oxide formed by the second protective layer forming coating solution has the composition shown in Table 1-2.

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

Example 9
<Fabrication of field effect transistor>
-Preparation of first protective layer forming coating solution-
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 strontium 2-ethylhexanoate toluene solution (Sr content 2%, Wako) 195-0951, manufactured by Wako Chemical Co., Ltd.) (1.42 mL) was mixed to obtain a first protective layer-forming coating solution. The first composite metal oxide formed by the first protective layer forming coating solution has the composition shown in Table 1-2.

−Preparation of second protective layer forming coating solution−
To 1 mL of toluene, 0.22 g of samarium acetylacetonate trihydrate (Strem 93-6226, manufactured by Strem Chemicals), calcium 2-ethylhexanoate in toluene (Ca content: 4.9%, Strem 93-2014, Stream Chemicals) 0.01 mL), 2-ethylhexanoic acid strontium toluene solution (Sr content 2%, Wako 195-09561, manufactured by Wako Chemical Co., Ltd.) 0.18 mL, 2-ethylhexanoic acid zirconium oxide mineral spirit solution (Zr content) 12%, Wako 269-01116, manufactured by Wako Chemical Co., Ltd.) (0.03 mL) was 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 solution has the composition shown in Table 1-2.

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

(Example 10)
<Fabrication of field effect transistor>
-Preparation of first protective layer forming coating solution-
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 magnesium 2-ethylhexanoate toluene solution (Mg content 3%, Strem 12-1260, manufactured by Strem Chemicals) 0.06 mL, 2-ethylhexanoic acid calcium toluene solution (Ca content 4.9%, Strem 93-2014, manufactured by Strem Chemicals) 0.10 mL, and 2-ethylhexanoic acid barium toluene The solution (Ba content 8%, Wako 021-0471, manufactured by Wako Chemical Co., Ltd.) 0.11 mL was 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 solution has the composition shown in Table 1-2.

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

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

(Example 11)
<Fabrication of field effect transistor>
-Preparation of first protective layer forming coating solution-
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 calcium 2-ethylhexanoate toluene solution (Ca content 4.9%) , Strem 93-2014, manufactured by Strem Chemicals) and 0.16 mL of 2-ethylhexanoic acid barium toluene solution (Ba content 8%, Wako 021-09471, manufactured by Wako Chemical Co., Ltd.) A protective layer-forming coating solution was obtained. The first composite metal oxide formed by the first protective layer forming coating solution has the composition shown in Table 1-3.

−Preparation of second protective layer forming coating solution−
To 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), 2- Magnesium ethylhexanoate toluene solution (Mg content 3%, Strem 12-1260, manufactured by Strem Chemicals) 0.01 mL, 2-ethylhexanoic acid calcium toluene solution (Ca content 4.9%, Stream 93-2014, manufactured by Stream Chemicals) ) 0.01 mL, 2-ethylhexanoic acid zirconium oxide mineral spirit solution (Zr content 12%, Wako 269-01116, manufactured by Wako Chemical Co., Ltd.) 0.08 mL, 2- 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 solution has the composition shown in Table 1-3.

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

(Example 12)
<Fabrication of field effect transistor>
-Preparation of first protective layer forming coating solution-
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) 0.10 mL) and 2-isopropoxy-4,4,5,5-tetramethyl-1,3,2-dioxaborolane (Wako 325-41462, manufactured by Wako Chemical Co., Ltd.), 4%, Alfa 89349, manufactured by Alfa Aesar) 0.08 g, 2-ethylhexanoic acid calcium toluene solution (Ca content 4.9%, Strem 93-2014, manufactured by Strem Chemicals) 0.09 mL and 2-ethylhexanoic acid strontium toluene solution (Sr content 2%, Wako) 195-09561, manufactured by Wako Chemical Co., Ltd.) 0.17m 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 solution has the composition shown in Table 1-3.

−Preparation of second protective layer forming coating solution−
To 1 mL of toluene, 0.99 mL of lanthanum 2-ethylhexanoate toluene solution (La content 7%, Wako 122-033371, manufactured by Wako Chemical Co., Ltd.) and strontium 2-ethylhexanoate toluene solution (Sr content 2%, Wako) 195-0951, manufactured by Wako Chemical Co., Ltd.) 0.27 mL and 2-ethylhexanoic acid zirconium oxide mineral spirit solution (Zr content 12%, Wako 269-01116, manufactured by Wako Chemical Co., Ltd.) 0.05 mL, A second coating solution for forming a protective layer was obtained. The second composite metal oxide formed by the second protective layer forming coating solution has the composition shown in Table 1-3.

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

(Example 13)
<Fabrication of field effect transistor>
-Preparation of first protective layer forming coating solution-
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) .4%, Alfa 89349, manufactured by Alfa Aesar) 0.08 mL and 2-ethylhexanoic acid barium toluene solution (Ba content 8%, Wako 021-09471, manufactured by Wako Chemical Co., Ltd.) 0.35 mL, A protective layer-forming coating solution was obtained. The first composite metal oxide formed by the first protective layer forming coating solution has the composition shown in Table 1-3.

−Preparation of second protective layer forming coating solution−
To 1 mL of toluene, 0.22 g of samarium acetylacetonate trihydrate (Strem 93-6226, manufactured by Strem Chemicals) and magnesium 2-ethylhexanoate toluene solution (Mg content 3%, Strem 12-1260, manufactured by Strem Chemicals) 0.02 mL and 2-ethylhexanoic acid hafnium 2-ethylhexanoic acid solution (Gelest AKH332, manufactured by Gelest) 0.01 mL 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 solution has the composition shown in Table 1-3.

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

(Example 14)
<Fabrication of field effect transistor>
-Preparation of first protective layer forming coating solution-
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 -1,3,2-dioxaborolane (Wako 325-41462, manufactured by Wako Chemical Co., Ltd.) 0.05 g, and 2-ethylhexanoic acid magnesium toluene solution (Mg content 3%, Strem 12-1260, manufactured by Strem Chemicals) 05 mL and 0.23 mL of 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 solution has the composition shown in Table 1-3.

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

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

(Example 15)
<Fabrication of field effect transistor>
-Preparation of first protective layer forming coating solution-
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) .4%, Alfa 89349, 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 2-ethyl hexanoic acid calcium toluene solution (Ca content 4.9%, Strem 93-2014, manufactured by Strem Chemicals) 0.07 mL 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 solution has the composition shown in Table 1-3.

−Preparation of second protective layer forming coating solution−
To 1 mL of toluene, 0.99 mL of lanthanum 2-ethylhexanoate toluene solution (La content 7%, Wako 122-033371, manufactured by Wako Chemical Co., Ltd.) and strontium 2-ethylhexanoate toluene solution (Sr content 2%, Wako) 195-0951, manufactured by Wako Chemical Co., Ltd.) 0.08 mL, 2-ethylhexanoic acid barium toluene solution (Ba content 8%, Wako 021-09471, manufactured by Wako Chemical Co., Ltd.) 0.03 mL, and 2-ethylhexanoic acid Zirconium oxide mineral spirit solution (Zr content 12%, Wako 269-01116, manufactured by Wako Chemical Co., Ltd.) 0.03 mL and 2-ethylhexanoic acid hafnium 2-ethylhexanoic acid solution (Gelest AKH332, manufactured by Gelest) 0.02 mL Were mixed to obtain a second protective layer coating solution. The second composite metal oxide formed by the second protective layer forming coating solution has the composition shown in Table 1-3.

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

(Example 16)
<Fabrication of field effect transistor>
-Preparation of first protective layer forming coating solution-
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) .4%, Alfa 89349, manufactured by Alfa Aesar) 0.10 mL, (4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl) benzene (Wako 325-59912, Wako Chemical Co., Ltd.) 0.11 g, 2-ethylhexanoic acid calcium 2-ethylhexanoic acid solution (Ca content 3% -8%, Alfa 36657, Alfa Aesar) 0.09 mL, 2-ethylhexanoic acid strontium toluene solution (Sr content) 2%, Wako 195-09561, manufactured by Wako Chemical Co., Ltd.) 0.17 mL Were mixed to obtain a first protective layer-forming coating solution. The first composite metal oxide formed by the first protective layer forming coating solution has the composition shown in Table 1-3.

−Preparation of second protective layer forming coating solution−
To 1 mL of toluene, 0.99 mL of 2-ethylhexanoic acid lanthanum toluene solution (La content 7%, Wako 122-03371, manufactured by Wako Chemical Co., Ltd.) and 2-ethylhexanoic acid strontium toluene solution (Sr content 2%, Wako) 195-0951, manufactured by Wako Chemical Co., Ltd.) 0.27 mL and 2-ethylhexanoic acid zirconium oxide mineral spirit solution (Zr content 12%, Wako 269-01116, manufactured by Wako Chemical Co., Ltd.) 0.05 mL, A second coating solution for forming a protective layer was obtained. The second composite metal oxide formed by the second protective layer forming coating solution has the composition shown in Table 1-3.

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

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

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

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

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

(Comparative Example 3)
<Fabrication of field effect transistor>
−Preparation of second protective layer forming coating solution−
0.43 mL of 2-ethyl hexanoic acid magnesium toluene solution (Mg content 3%, Strem 12-1260, made 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 the composition shown in Table 2-1.

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

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

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

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

(Comparative Example 5)
<Fabrication of field effect transistor>
-Preparation of first protective layer forming coating solution-
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 2-ethylhexanoic acid barium toluene solution (Ba content 8 wt%, Wako) 021-09471, manufactured by Wako Chemical Co., Ltd.) 2.57 mL was mixed to obtain a first protective layer forming coating solution. The first composite metal oxide formed by the first protective layer forming coating solution has the composition shown in Table 2-1.

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

(Comparative Example 6)
<Fabrication of field effect transistor>
−Preparation of second protective layer forming coating solution−
To 1 mL of toluene, 0.31 mL of 2-ethylhexanoate gadolinium toluene solution (Gd content 25 wt%, Strem 64-3500, manufactured by Strem Chemicals) and 2-ethylhexanoate barium toluene solution (Ba content 8 wt%, Wako 021-09471) (Manufactured by Wako Chemical Co., Ltd.) and 0.23 mL 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 solution has the composition shown in Table 2-2.

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

(Comparative Example 7)
<Fabrication of field effect transistor>
-Preparation of first protective layer forming coating solution-
HMDS (1,1,1,3,3,3-hexamethyldisilazane, manufactured by Tokyo Ohka Kogyo Co., Ltd.) 0.11 mL 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 the composition shown in Table 2-2.

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

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

(Comparative Example 8)
<Fabrication of field effect transistor>
First, in the same manner as in Example 1, 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.

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

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

<Reliability evaluation of field effect transistor>
A BTS (Bias Temperature Stress) test was performed for 400 hours in the atmosphere (temperature: 50 ° C., relative humidity: 50%) for the field effect transistors manufactured in Examples 1 to 16 and Comparative Examples 1 to 8.
The following four 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
In addition, every time the BTS test passed, a 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 a test in which 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 in a test in which the stress conditions are Vgs = + 20V and Vds = + 20V. FIG. 12 shows the results of Vgs-Ids in a test in which the stress conditions are Vgs = −20V and Vds = 0V. FIG. 13 shows the results of Vgs-Ids in a test in which the stress conditions were Vgs = −20V and Vds = + 20V.
Here, “e” on the vertical axis of the graphs of FIGS. 10, 11, 12, and 13 and the horizontal and vertical axes of the graph of FIG. 14 represents 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 Vgs = + 20 V and Vds = 0 V of the field effect transistors manufactured in Example 12 and Comparative Example 8. Here, ΔVth indicates the amount of change in Vth from the stress time of 0 hour 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 showed excellent reliability. On the other hand, the field effect transistor produced in Comparative Example 8 had a large ΔVth shift and insufficient reliability.

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

Aspects of the present invention are as follows, for example.
<1> a base material;
A protective layer;
A gate insulating layer formed between the substrate and the protective layer;
A source electrode and a drain electrode formed in contact with the gate insulating layer;
A semiconductor layer formed between at least the source electrode and the drain electrode and in contact with the gate insulating layer, the source electrode, and the drain electrode;
A gate electrode in contact with the gate insulating layer and facing the semiconductor layer through the gate insulating layer;
The protective layer is formed in contact with the first protective layer containing the first composite metal oxide containing Si and an alkaline earth metal, and the first protective layer, and the alkaline earth metal A field effect transistor having 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 the drive signal;
A display element comprising the field effect transistor according to any one of <1> to <4> and a drive circuit that 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 electrophoretic element, and an electrowetting element.
<7> An image display device that displays an image according to image data,
A plurality of the 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;
An image display device comprising: a display control device that individually controls a gate voltage of each of the field effect transistors through the plurality of wirings according to the image data.
<8> The image display device according to <7>,
An image data creation device that creates image data based on image information to be displayed and outputs 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 1st protective layer 27b II protective layer 31 base material 32 first gate electrode 33 second gate electrode 34 gate insulating layer 35 first source electrode 36 second source electrode 37 first drain electrode 38 second drain electrode 39 first I oxide semiconductor layer 40 second II oxide semiconductor layer 41a first I-1 protective layer 41b second I-2 protective layer 42a second II-1 protective layer 42b second 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 2007-0773705 A JP 2010-135770 A JP 2010-182819 A JP 2010-135462 A

K. Nomura, 5 others, "Room-temperament fabrication of transparent flexible thin film transformers using amorphous semiconductors", NATURE, VOL4 432B 488-492 T.A. Arai, et al., “Manufacturing Issues for Oxide TFT Technologies for Large-Sized AMOLED Displays”, SID 2012 Digest, 2012, p. 756-759

Claims (8)

A substrate;
A protective layer;
A gate insulating layer formed between the substrate and the protective layer;
A source electrode and a drain electrode formed in contact with the gate insulating layer;
A semiconductor layer formed between at least the source electrode and the drain electrode and in contact with the gate insulating layer, the source electrode, and the drain electrode;
A gate electrode in contact with the gate insulating layer and facing the semiconductor layer through the gate insulating layer;
The protective layer is formed in contact with the first protective layer containing the first composite metal oxide containing Si and an alkaline earth metal, and the first protective layer, and the alkaline earth metal A field effect transistor comprising a second protective layer containing a second composite metal oxide containing a rare earth element.   The field effect transistor according to claim 1, wherein the first composite metal oxide contains at least one of Al and B.   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;
5. A display element comprising: the field effect transistor according to claim 1; and a drive circuit that drives the light control element.   The display element according to claim 5, wherein the light control element includes any one of an electroluminescence element, an electrochromic element, a liquid crystal element, an electrophoretic element, and an electrowetting element. An image display device that displays an image according to image data,
A plurality of display elements according to any one of claims 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;
An image display device comprising: a display control device that individually controls a gate voltage of each field effect transistor through the plurality of wirings according to the image data. An image display device according to claim 7,
A system comprising: an image data creation device that creates image data based on image information to be displayed and outputs the image data to the image display device.