TWI637512B - Field-effect transistor, display element, image display, system, and composition - Google Patents

Abstract

A field effect transistor includes a gate for applying a gate voltage, a source and a drain for outputting current, a semiconductor layer disposed adjacent to the source and the drain, and a gate insulating a layer disposed between the gate and the semiconductor layer, wherein the gate insulating layer comprises a monooxide containing germanium and one or two or more alkaline earth metal elements.

Description

Field effect transistors, display elements, image displays, systems and compositions

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

A field effect transistor (FET) controls the current between the source and the drain by applying an electric field to the gate to provide a gate that resists the flow of electrons or holes due to the electric field of the channel.

Due to this characteristic, the FET is used as a switching element, an amplifying element, and the like. In addition, since the FET has a planar structure and the gate current is low, the fabrication and integration of the FET is easier than that of the bipolar transistor. Therefore, the FET is an indispensable component in the integrated circuit of the current electronic device. For example, FETs are used as thin film transistors (TFTs) for displays in the form of active matrix.

Similarly, flat panel displays (FPDs), liquid crystal displays, organic electroluminescent displays, and electronic papers have been put into practical use.

These FPDs are driven by a driving circuit including TFTs using amorphous germanium, polycrystalline germanium or the like in the active layer. Also, FPDs require further size, finer resolution, higher image quality, and higher drive response. Therefore, TFTs are required to have excellent carrier mobility, high on/off ratio, small time variation characteristics, and small variations between elements.

However, both amorphous and polycrystalline germanium have advantages and disadvantages that make it difficult to meet all of the requirements. In order to meet the demand, TFTs using an oxide semiconductor in an active layer have been actively developed, and it is expected to have better mobility than amorphous germanium.

According to the present invention, there is provided an improved field effect transistor comprising a gate for applying a gate voltage, a source and a drain for outputting a current, and a semiconductor layer disposed adjacent to the source and The drain electrode and a gate insulating layer are disposed between the drain and the semiconductor layer. The gate insulating layer includes a monooxide having tantalum and one or two or more alkaline earth metal elements.

11, 12, 14‧‧‧ field effect transistor

13, 15‧‧‧ capacitors

16‧‧‧ opposite electrode

21‧‧‧Substrate

22‧‧‧ gate

23‧‧‧ gate insulation

24‧‧‧ source

25‧‧‧汲polar

26‧‧‧Oxide semiconductor layer

31‧‧‧Substrate

32‧‧‧First Gate

33‧‧‧second gate

34‧‧‧ gate insulation

35‧‧‧first source

36‧‧‧Second source

37‧‧‧First bungee

38‧‧‧Second bungee

39‧‧‧First oxide semiconductor layer

40‧‧‧Second oxide semiconductor layer

41‧‧‧First passivation layer

42‧‧‧Second passivation layer

43‧‧‧Interlayer insulation

44‧‧‧Organic EL layer

45‧‧‧ cathode

91‧‧‧Substrate

92‧‧‧ gate

93‧‧‧gate insulation

94‧‧‧ source

95‧‧‧汲polar

96‧‧‧Oxide semiconductor layer

101‧‧‧Substrate

102‧‧‧ bottom electrode

103‧‧‧Insulation film

104‧‧‧Upper electrode

302‧‧‧Display components

302'‧‧‧Display components

310‧‧‧ display

312‧‧‧ cathode

314‧‧‧Anode

320‧‧‧ drive circuit

320'‧‧‧ drive circuit

340‧‧‧Organic EL film layer

342‧‧‧Electronic transport layer

344‧‧‧Lighting layer

346‧‧‧ hole transport layer

350‧‧‧Organic Electroluminescent (EL) Components

370‧‧‧Liquid Crystal Components

372‧‧‧ opposite electrode

400‧‧‧Display control device

402‧‧‧Image data processing circuit

404‧‧‧Scan line driver circuit

406‧‧‧Data line driver circuit

G‧‧‧ gate

S‧‧‧ source

D‧‧‧汲

X0, X1, X2, X3, ..., Xn-2, Xn-1‧‧‧ scan lines

Y0, Y1, Y2, Y3, ..., Ym-2, Ym-1‧‧‧ data line

Y0i, Y1i, Y2i, Y3i, ..., Ym-1i‧‧‧ current supply line

The various other objects, features and attendant advantages of the present invention will become more <RTIgt; The same corresponding components, and wherein: FIG. 1 is a schematic view showing an image display device; FIG. 2 is a schematic view showing an example of a display element according to an embodiment of the present invention; and FIG. 3A is an example showing a field effect transistor according to an embodiment of the present invention ( FIG. 3B is a schematic diagram showing an example of a field effect transistor (upper contact lower gate type) according to an embodiment of the present invention; FIG. 3C is a view showing a field effect transistor according to an embodiment of the present invention; Schematic diagram of an example (lower contact upper gate type); FIG. 3D is a schematic diagram showing an example of a field effect transistor (upper contact upper gate type) according to an embodiment of the present invention; FIG. 4 is a diagram showing an organic electroluminescent (EL) element Schematic diagram showing an example of a display element according to an embodiment of the present invention; FIG. 6 is a schematic view showing another example of a display element according to an embodiment of the present invention; A schematic diagram showing a description of the display control device; Fig. 8 is a schematic view showing a description of the liquid crystal display; Fig. 9 is a schematic view showing a description of the display element shown in Fig. 8; Fig. 10 is a view showing an example 1 to be described later. 3 and a schematic diagram of the field effect transistor fabricated in Comparative Examples 1 and 2; FIG. 11 is a schematic view showing the capacitors fabricated in Examples 1 to 3 and Comparative Examples 1 and 2. FIG. 12 is a schematic diagram for evaluating the relationship between the relative dielectric constant ε and the dielectric loss (tan δ) of the capacitor fabricated in Example 13 to be described later, and the frequency of the applied electric field; FIG. 13 is an evaluation example in comparison. Schematic diagram of the relationship between the relative dielectric constant ε and the dielectric loss (tan δ) of the capacitor fabricated in 1 and the frequency of the applied electric field; and FIG. 14 is an evaluation of the field effect transistor fabricated in Example 13 Schematic diagram of characteristics (Vds-Ids).

The drawings are intended to describe example embodiments of the invention and are not intended to The drawings are not to be considered to be drawn to scale unless otherwise indicated. In addition, the same or similar drawing symbols represent the same or similar parts in the various views.

In the illustrative embodiments shown in the drawings, specific terminology is employed for the sake of clarity. However, the disclosure of the present invention is not intended to be limited to the specific terms selected, and it is understood that each specific element includes all technical equivalents that have similar functions, operate in a similar manner, and achieve similar results.

As used herein, the singular forms "", ","

According to the present invention, there is provided a field effect transistor which does not cause peeling between a gate, a source and a drain and a gate insulating layer due to a heating process.

Field effect transistor

The field effect transistor of the present invention includes a gate, a source, a drain, a semiconductor layer, a gate insulating layer (film), and other optional components.

In the field effect transistor of the present invention, the gate insulating layer includes an oxide having cerium and an alkaline earth metal, which will be described in detail below.

The field effect transistor disclosed in Japanese Laid-Open Patent Publication No. 2013-30784 and No. 2011-077515 includes a SiO ₂ gate insulating layer. SiO ₂ has a small coefficient of linear expansion of about 5 x 10 ^-7 /K. Therefore, due to the heat treatment in the manufacturing process of the field effect transistor, thermal stress is generated between, for example, the metal and oxide material constituting the field effect transistor and SiO ₂ , which causes peeling between the gate insulating layer and the gate. Wait.

Further, Japanese Laid-Open Patent Publication No. 2012-191008 discloses a thin film transistor in which the thin film transistor is not peeled off even at room temperature according to the thickness of the gate insulating layer.

As a result of studying the gate insulating layer, the inventors have found that if the gate insulating layer includes an oxide having germanium and one or two or more alkaline earth metal elements, the linear expansion coefficient of the gate insulating layer is compared with that of SiO ₂ . The increase makes it possible to prevent peeling between the gate, the source and the drain of the field effect transistor and the gate insulating layer during the heat treatment.

Gate

The gate is not particularly limited and may be appropriately selected depending on the intended purpose as long as the gate is an electrode configured to apply a gate voltage to the field effect transistor.

The gate is in contact with the gate insulating layer and faces the semiconductor layer via the gate insulating layer.

The material of the gate is not particularly limited and may be appropriately selected depending on the intended purpose. Examples of the material include: metals (for example, Mo, Al, Au, Ag, and Cu) and alloys of these metals; transparent conductive oxides such as indium tin oxide (ITO) and antimony-doped tin oxide (ATO); and organic conductors For example, polyethylene dioxythiophene (PEDOT) and polyaniline (PANI).

Method of forming a gate

The method of forming the gate is not particularly limited and may be appropriately selected depending on the intended purpose. Examples of the formation method include: (i) a method of forming a thin film by sputtering or dip coating and patterning a thin film by photolithography; and (ii) a direct printing process by, for example, inkjet printing, nanoimprinting or gravure printing A method of forming a film having a desired shape.

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

Source and bungee

The source and the drain are not particularly limited and may be appropriately selected depending on the intended purpose as long as the source and the drain are electrodes configured to output a current from the field effect transistor.

The source and drain are formed in contact with the gate insulating layer.

The materials of the source and the drain are not particularly limited and may be appropriately selected depending on the intended purpose. Examples of the material include: metals (for example, Mo, Al, Au, Ag, and Cu) and alloys of these metals; transparent conductive oxides such as indium tin oxide (ITO) and antimony-doped tin oxide (ATO); and organic conductors For example, polyethylene dioxythiophene (PEDOT) and polyaniline (PANI).

Method of forming source and drain

The method of forming the source and the drain is not particularly limited and may be appropriately selected depending on the intended purpose. Examples of the formation method include: (i) a method of forming a film by sputtering or dip coating and patterning a film by photolithography; and (ii) a direct printing process such as inkjet printing, nanoimprinting or gravure printing A method of forming a film having a desired shape.

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

Semiconductor layer

The semiconductor layer is formed at least between the source and the drain.

Here, "between" refers to a position where a semiconductor layer acts together with a source and a drain to cause a field effect transistor to function. The position of the semiconductor layer is not particularly limited and may be appropriately selected depending on the intended purpose as long as the position is the above position.

The semiconductor layer is in contact with the gate insulating layer, the source, and the drain.

The material of the semiconductor layer is not particularly limited and may be appropriately selected depending on the intended purpose. Examples of materials include germanium semiconductors and oxide semiconductors.

Examples of the germanium semiconductor include amorphous germanium and polycrystalline germanium.

Examples of the oxide semiconductor include InGa-Zn-O, In-Zn-O, and In-Mg-O.

In these examples, an oxide semiconductor is preferred.

Method of forming a semiconductor layer

The method of forming the semiconductor layer is not particularly limited and may be appropriately selected depending on the intended purpose. Examples of the formation method include: through a vacuum process (for example, sputtering, pulsed laser deposition (PLD), chemical vapor deposition (CVD) or atomic layer deposition (ALD)) or a solution process (dip coating, spin coating or die coating) a method of forming a thin film and patterning the thin film by photolithography; and A printing method such as inkjet printing, nanoimprinting or gravure printing directly forms a film having a desired shape.

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

Gate insulation

A gate insulating layer is usually disposed between the gate and the semiconductor layer.

The gate insulating layer includes an oxide.

Oxide

The oxide includes at least Si (cerium) and one or two or more alkaline earth metal elements, preferably at least one of Al (aluminum) and B (boron), and further includes other components as needed.

In the oxide, SiO ₂ formed of the above Si has an amorphous structure. Further, the alkaline earth metal has a function of cracking Si-O bonds. Therefore, the relative dielectric constant and the linear expansion coefficient of the formed oxide can be controlled by the composition ratio of Si and alkaline earth metal.

The oxide preferably contains Al, or B or both. Similar to SiO ₂ , Al ₂ O ₃ formed of Al and B ₂ O ₃ formed of B each form an amorphous structure. Therefore, an amorphous structure is formed more stably in the oxide, and a more uniform insulating film can be formed. Since the alkaline earth metal changes the coordination structure of Al and B according to the composition ratio thereof, the relative dielectric constant and the linear expansion coefficient of the oxide can be controlled.

Examples of the alkaline earth metal in the oxide include Be (yttrium), Mg (magnesium), Ca (calcium), Sr (niobium), and Ba (niobium). They can be used alone or in combination.

The composition ratio of Si and alkaline earth metal in the oxide is appropriately selected depending on the intended purpose without any limitation, but the composition ratio thereof is preferably within the following range.

In the oxide, the composition ratio of Si and alkaline earth metal (Si: alkaline earth metal) is preferably 50.0 mol% to 90.0 mol based on the conversion ratio of oxides (SiO ₂ , BeO, MgO, CaO, SrO, BaO). %: 10.0 mol%~50.0 mol%.

The composition ratio of Si, alkaline earth metal, and Al and/or B in the oxide is appropriately selected depending on the intended purpose without any limitation, but the composition ratio thereof is preferably within the following range.

Among oxides, based on the conversion of oxides (SiO ₂ , BeO, MgO, CaO, SrO, BaO, Al ₂ O ₃ , B ₂ O ₃ ), Si, alkaline earth metals, and Al and/or B (Si: The composition ratio of the alkaline earth metal: Al and or B) is preferably from 50.0 mol% to 90.0 mol%: 5.0 mol% to 20.0 mol%: 5.0 mol% to 30.0 mol%.

For example, the cation elements of the oxide are analyzed by fluorescence X-ray spectroscopy, electron probe microanalysis (EPMA), inductively coupled plasma atomic emission spectroscopy (ICP-AES), etc. to calculate the proportion of oxides in the oxide (SiO ₂ , BeO). , MgO, CaO, SrO, BaO, Al ₂ O ₃ and B ₂ O ₃ ).

The coefficient of linear expansion of the gate insulating layer is appropriately selected depending on the intended purpose without any limitation. However, from the viewpoint of preventing peeling between the gate, the source and the drain and the gate insulating layer, the composition ratio thereof is preferably within the following range.

The linear expansion coefficient of the gate insulating layer is preferably 20.0 × 10 ^-7 /K or more, more preferably 20.0 × 10 ^-7 ~ 70.0 × 10 ^-7 /K.

For example, the linear expansion coefficient is measured by using a thermomechanical analyzer. In this measurement, the coefficient of linear expansion can be measured by separately producing a measurement sample having the same composition as the gate insulating layer, without the need to produce a field effect transistor.

The relative dielectric constant of the gate insulating layer is appropriately selected depending on the intended purpose without any limitation.

The relative dielectric constant can be measured, for example, by manufacturing and measuring a laminated structure having a bottom electrode, a dielectric layer (gate insulating layer), and a top electrode using an LCR meter.

Method of forming gate insulating layer

The method of forming the gate insulating layer is not particularly limited and may be appropriately selected depending on the intended purpose. Examples of the formation method include a method of forming a thin film by a vacuum process such as sputtering, pulsed laser deposition (PLD), chemical vapor deposition (CVD), or atomic layer deposition (ALD), and patterning a thin film by photolithography.

Further, by preparing a coating liquid (gate insulating layer coating liquid) containing an oxide precursor, the coating liquid is applied or printed onto an object to be coated, and baked under appropriate conditions. The gate insulating layer is formed.

The average thickness of the gate insulating layer is preferably from 10 nm to 1000 nm, more preferably from 20 nm to 500 nm.

Gate insulating layer coating solution

The gate insulating layer coating liquid includes at least a cerium-containing compound, an alkaline earth metal-containing compound, and a solvent, and preferably includes at least one of an aluminum-containing compound and a boron-containing compound, and further includes other components as needed.

Antimony compound

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

Examples of inorganic cerium compounds include, but are not limited to, trichlorodecane, tribromodecane, and tetraiododecane.

The organic hydrazine compound is appropriately selected depending on the intended purpose without any limitation as long as it is a compound containing hydrazine and an organic group. The hydrazine and the organic group are bonded through, 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. For example, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted anthraceneoxy group, a substituted or unsubstituted phenyl group is preferred. Examples of alkyl groups include, but are not limited to, alkyl groups having from 1 to 6 carbon atoms.

Examples of alkoxy groups include, but are not limited to, alkoxy groups having 1 to 6 carbon atoms.

Examples of the decyloxy group include, but are not limited to, a decyloxy group having 1 to 10 carbon atoms.

Examples of the organic ruthenium compound include, but are not limited to, tetramethoxy decane, tetraethoxy decane, tetraisopropoxy decane, tetrabutoxy decane, 1,1,1,3,3,3-hexamethyl Indoxazane (HMDS), bis(trimethyldecyl)acetylene, triphenyldecane, bismuth 2-ethylhexanoate, and tetraethoxydecane.

The amount of the cerium-containing compound in the gate insulating layer coating liquid is appropriately selected depending on the intended purpose without any limitation.

Alkaline earth metal containing compound

Examples of the alkaline earth metal-containing compound include an inorganic alkaline earth metal compound and an organic alkaline earth metal compound. Examples of the alkaline earth metal in the alkaline earth metal-containing compound include Be (铍), Mg (magnesium), Ca (calcium), Sr (锶), and Ba (钡).

Examples of the inorganic alkaline earth metal compound include alkaline earth metal nitrate, alkaline earth metal sulfate, alkaline earth metal chloride, alkaline earth metal fluoride, alkaline earth metal bromide, and alkaline earth metal iodide.

Examples of the alkaline earth metal nitrates include magnesium nitrate, calcium nitrate, cerium nitrate, and cerium nitrate.

Examples of the alkaline earth metal sulfate include magnesium sulfate, calcium sulfate, barium sulfate, and barium sulfate.

Examples of the alkaline earth metal chloride include magnesium chloride, calcium chloride, barium chloride, and barium chloride.

Examples of alkaline earth metal fluorides include magnesium fluoride, calcium fluoride, barium fluoride, and barium fluoride.

Examples of the alkaline earth metal bromide include magnesium bromide, calcium bromide, barium bromide, and barium bromide.

Examples of the alkaline earth metal iodide include magnesium iodide, calcium iodide, cesium iodide, and cesium iodide.

The organic alkaline earth metal compound is not particularly limited and may be appropriately selected depending on the intended purpose as long as the organic alkaline earth metal compounds are each a compound containing an alkaline earth metal and an organic group. The alkaline earth metal and the organic group are bonded through, 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. For example, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted decyloxy group, a substituted or unsubstituted phenyl group, a substituted or unsubstituted acetoacetone group, and a substitution are preferred. Or an unsubstituted sulfonic acid group.

Examples of alkyl groups include, but are not limited to, alkyl groups having from 1 to 6 carbon atoms.

Examples of alkoxy groups include, but are not limited to, alkoxy groups having 1 to 6 carbon atoms.

Examples of the decyloxy group include, but are not limited to, a decyloxy group having 1 to 10 carbon atoms, a decyloxy group substituted with a benzene ring moiety such as benzoic acid benzoate, a decyloxy group substituted with a hydroxy moiety such as lactic acid, and For example, a decyloxy group of two or more carbonyl groups of oxalic acid and citric acid.

Examples of organic alkaline earth metals include, but are not limited to, magnesium oxide, magnesium sulphate, diethyl magnesium, magnesium acetate, magnesium formate, magnesium acetonate, magnesium 2-ethylhexanoate, magnesium lactate, magnesium naphthenate, lemon Magnesium sulphate, magnesium salicylate, magnesium benzoate, magnesium oxalate, magnesium triflate, calcium sulphate, calcium sulphate, calcium acetate, calcium formate, calcium acetyl acetonate, calcium dipentyl ruthenate, 2- Calcium ethylhexanoate, calcium lactate, calcium naphthenate, calcium citrate, calcium salicylate, calcium neodecanoate, calcium benzoate, calcium oxalate, barium isopropoxide, barium acetate, barium formate, barium acetate , 2-ethylhexanoate, barium lactate, barium naphthenate, barium salicylate, barium oxalate, barium ethoxide, barium isopropoxide, barium acetate, barium formate, barium acetone, 2-ethylhexyl Barium strontium, barium lactate, barium naphthenate, barium naphthenate, barium neodecanoate, barium oxalate, barium benzoate and barium triflate.

The amount of the alkaline earth metal-containing compound in the gate insulator layer coating liquid is appropriately selected depending on the intended purpose without any limitation.

Aluminum-containing compound

Examples of the aluminum-containing compound are an inorganic aluminum compound and an organoaluminum compound.

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

The organoaluminum compound is appropriately selected depending on the intended purpose without any limitation as long as it is a compound containing aluminum and an organic group. The aluminum and the organic group are bonded, for example, via an ionic bond, a covalent bond or a coordinate bond.

The organic group is appropriately selected depending on the intended purpose without any limitation. For example, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted decyloxy group, a substituted or unsubstituted acetoacetone group, and a substituted or unsubstituted sulfonic acid group are preferred.

Examples of alkyl groups include, but are not limited to, alkyl groups having from 1 to 6 carbon atoms.

Examples of alkoxy groups include, but are not limited to, alkoxy groups having 1 to 6 carbon atoms.

Examples of the decyloxy group include, but are not limited to, a decyloxy group having 1 to 10 carbon atoms, a decyloxy group substituted by, for example, a benzene ring portion of benzoic acid benzoate, a decyloxy group substituted with a hydroxy moiety such as lactic acid, and having, for example, oxalic acid And a decyloxy group of two or more carbonyl groups of citric acid.

Examples of the organoaluminum compound include isopropyl alumina, secondary butadiene alumina, triethylaluminum, diethylaluminum ethoxide, aluminum acetate, aluminum acetonate, aluminum hexafluoroacetate, 2-ethylhexyl Aluminum acid, aluminum lactate, aluminum benzoate, aluminum bis(2-butoxy)acetate, and aluminum triflate.

The amount of the aluminum-containing compound in the gate insulating layer coating liquid is appropriately selected depending on the intended purpose without any limitation.

Boron-containing compound

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

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

The organoboron compound is appropriately selected depending on the intended purpose without any limitation as long as it is a compound containing boron and an organic group.

Boron and an organic group are bonded through, for example, an ionic bond, a covalent bond, or a coordinate bond.

The organic group is appropriately selected depending on the intended purpose without any limitation. For example, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted decyloxy group, a substituted or unsubstituted phenyl group, a substituted or unsubstituted sulfonic acid group, a substitution or Unsubstituted thienyl.

Examples of alkyl groups include, but are not limited to, alkyl groups having from 1 to 6 carbon atoms.

Examples of alkoxy groups include, but are not limited to, alkoxy groups having 1 to 6 carbon atoms.

The alkoxy group includes an organic group having two or more oxygen atoms and two of two or more oxygen atoms bonded to boron, and the organic group forms a ring structure. Further, the alkoxy group includes a case where an alkyl group contained in an alkoxy group is substituted with an organodecyl group. Examples of the decyloxy group include, but are not limited to, a decyloxy group having 1 to 10 carbon atoms.

Examples of the organoboron compound include (R)-5,5-diphenyl-2-methyl-3,4-propanol-1,3,2-boraoxazolidine, triisopropyl borate, 2- Isopropoxy-4,4,5,5-tetramethyl-1,3,2-dioxaborolane, bis(hexenyl glycolic acid) diboronate, 4-(4, 4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-1H-pyrazole, (4,4,5,5-tetramethyl-1, 3,2-dioxaborolan-2-yl)benzene, tetra-butyl-N-[4-(4,4,5,5-tetramethyl-1,2,3-dioxo Heteroborolan-2-yl)phenyl]carbamate, phenylboronic acid, 3-ethylphenylphenylboronic acid, boron trifluoride acetate complex, boron trifluoride cyclobutane ruthenium complex , 2-thiopheneboronic acid and tris(trimethyldecyl)borate.

The amount of the boron-containing compound in the gate insulating layer coating liquid is appropriately selected depending on the intended purpose without any limitation.

Solvent

The solvent is appropriately selected depending on the intended purpose without any limitation as long as it is a solvent capable of stably dissolving or dispersing the above various compounds.

Specific examples include, but are not limited to, toluene, xylene, mesitylene, cymene, amylbenzene, dodecylbenzene, dicyclohexane, cyclohexylbenzene, decane, undecane, dodecane, ten Trioxane, tetradecane, pentadecane, tetrahydronaphthalene, decalin, isopropanol, ethyl benzoate, N,N-dimethylformamide, propylene carbonate, 2-ethylhexanoic acid , mineral spirits, dimethyl methene urea, 4-butyrolactone, 2-methoxyethanol and water.

The amount of the solvent in the gate insulating layer coating liquid is appropriately selected depending on the intended purpose without any limitation.

The composition ratio of the cerium-containing compound and the alkaline earth metal-containing compound (the cerium-containing compound: the alkaline earth metal-containing compound) in the gate insulating layer coating liquid is appropriately selected depending on the intended purpose without any limitation, but the composition ratio thereof is preferably the following. Within the scope.

In the gate insulating layer coating liquid, the composition ratio of Si and alkaline earth metal (Si: alkaline earth metal) is preferably 50.0 mol based on the conversion ratio of oxides (SiO ₂ , BeO, MgO, CaO, SrO, BaO). %~90.0 mol%: 10.0 mol%~50.0 mol%.

Composition ratio of cerium-containing compound, alkaline earth metal-containing compound, and aluminum-containing compound and/or boron-containing compound in the gate insulating layer coating liquid (containing cerium compound: alkaline earth metal-containing compound: The composition ratio of the aluminum-containing compound and/or the boron-containing compound is appropriately selected depending on the intended purpose without any limitation, but the composition ratio thereof is preferably within the following range.

In the gate insulating layer coating liquid, based on the conversion ratio of oxides (SiO ₂ , BeO, MgO, CaO, SrO, BaO, Al ₂ O ₃ , B ₂ O ₃ ), Si, alkaline earth metals, and Al and/ Or the composition ratio of B (Si: alkaline earth metal: Al and/or B) is preferably from 50.0 mol% to 90.0 mol%: 5.0 mol% to 20.0 mol%: 5.0 mol% to 30.0 mol%.

Method for forming gate insulating layer using gate insulating layer coating liquid

An example of a method of forming a gate insulating layer using a gate insulating layer coating liquid will be described. The method of forming the gate insulating layer includes a coating step and a heat treatment step, and further includes other steps as needed.

The coating step is not particularly limited and may be appropriately selected depending on the intended purpose as long as the coating step is a step of applying a gate insulating layer coating liquid onto an object to be coated. The coating method is not particularly limited and may be appropriately selected depending on the intended purpose. Examples of the method include a method of forming a film by a solution process and patterning a film by photolithography; and a method of directly forming a film having a desired shape by a printing process such as inkjet printing, nanoimprinting or gravure printing. Examples of solution processes include dip coating, spin coating, die coating, and nozzle printing.

The heat treatment step is not particularly limited, and may be appropriately selected depending on the intended purpose as long as the heat treatment step is a step of heat-treating the gate insulating layer coating liquid coated on the object to be coated. Note that in the heat treatment step, the gate insulating layer coating liquid coated on the object to be coated may be dried by air drying. As a result of the heat treatment, the solvent evaporates and an oxide is produced.

In the heat treatment step, evaporation of a solvent (hereinafter referred to as "evaporation treatment") and formation of an oxide (hereinafter referred to as "production treatment") are preferably carried out at different temperatures. Specifically, it is preferred to raise the temperature to form an oxide after evaporation of the solvent. At the time of forming an oxide, for example, at least one of a ruthenium-containing compound, an alkali-containing metal compound, an aluminum-containing compound, and a boron-containing compound is decomposed.

The temperature of the evaporation treatment is not particularly limited and may be appropriately selected depending on the solvent contained. For example, the temperature of the evaporation treatment is from 80 ° C to 180 ° C. For evaporation, in order to reduce The required temperature is effective using a vacuum oven. The time of the evaporation treatment is not particularly limited and may be appropriately selected depending on the intended purpose. For example, the evaporation treatment time is from 10 minutes to 1 hour.

The temperature at which the treatment is generated is not particularly limited and may be appropriately selected depending on the intended purpose. However, the temperature of the formation treatment is preferably 100 ° C or more but less than 550 ° C, more preferably 200 ° C to 500 ° C. The time at which the processing is generated is not particularly limited, and may be appropriately selected depending on the intended purpose. For example, the generation processing time is from 1 hour to 5 hours.

Note that in the heat treatment step, the evaporation treatment and the generation treatment may be continuously performed, or may be performed in a separate manner of a plurality of steps.

The method of the heat treatment is not particularly limited and may be appropriately selected depending on the intended purpose. An example of the method of heat treatment includes a method of heating an object to be coated. The atmospheric environment in the heat treatment is not particularly limited and may be appropriately selected depending on the intended purpose. However, the atmospheric environment is preferably an oxygen environment. When heat treatment is performed in an oxygen atmosphere, the decomposition products can be quickly discharged outside the system, and the formation of the first composite oxide can be accelerated.

In the heat treatment, in consideration of the acceleration of the reaction for the formation treatment, it is effective to apply ultraviolet rays having a wavelength of 400 nm or less to the material after the evaporation treatment. The application of ultraviolet rays having a wavelength of 400 nm or less can cleave chemical bonds of organic materials contained in the material after the evaporation treatment, and can decompose the organic materials. Therefore, the first composite oxide can be formed efficiently. The ultraviolet ray having a wavelength of 400 nm or less is not particularly limited and may be appropriately selected depending on the purpose. Examples of the ultraviolet rays include ultraviolet rays having a wavelength of 222 nm emitted from an excimer lamp. It is also preferred to use ozone instead of or in combination with ultraviolet light. The application of ozone to the material after the evaporation treatment accelerates the formation of oxides.

The structure of the field effect transistor is not particularly limited and may be appropriately selected depending on the intended purpose. Examples of the structure of the field effect transistor include the following structures.

A field effect transistor comprising a substrate, a gate formed on the substrate, a gate insulating layer formed on the gate, a source and a drain formed on the gate insulating layer, and a source and a drain A semiconductor layer between the poles.

2. A field effect transistor comprising a substrate, a source and a drain formed on the substrate, a semiconductor layer formed between the source and the drain, and a gate insulating formed on the source, the drain and the semiconductor layer a layer and a gate formed on the gate insulating layer.

As the field effect transistor having the structure of the above 1, for example, there are a lower contact lower gate type (see FIG. 3A) and an upper contact lower gate type (see FIG. 3B).

As the field effect transistor having the structure of the above 2, for example, there are a lower contact upper gate type (see FIG. 3C) and an upper contact upper gate type (see FIG. 3D).

In FIGS. 3A to 3D, each field effect transistor includes a substrate 21, a gate 22, a gate insulating layer 23, a source electrode 24, a drain electrode 25, and an oxide semiconductor layer 26. The oxide semiconductor layer 26 can be replaced by, for example, the above-described germanium semiconductor layer.

The field effect transistor can be suitably applied to a display element described later, but is not limited thereto. For example, field effect transistors can be applied to IC cards, ID tags, and the like.

Display component

The display element of the present invention includes at least a light control element and a drive circuit configured to drive the light control element, and further includes other elements as needed.

Light control element

The light control element is not particularly limited and may be appropriately selected depending on the intended purpose as long as the light control element is an element configured to control the light output according to the drive signal. Examples of light control elements include electroluminescent (EL) elements, electrochromic (EC) elements, liquid crystal elements, electrophoretic elements, and electrowetting elements.

Drive circuit

The driving circuit is not particularly limited and may be appropriately selected depending on the intended purpose as long as the driving circuit is a circuit including the field effect transistor of the present invention and configured to drive the light control element.

Other components

The other elements are not particularly limited and may be appropriately selected to suit a specific application.

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

Image display device

The image display device of the present invention includes at least a plurality of display elements, a plurality of lines, and a display control device. The image display device may also include other optional components.

The image display device is a device configured to display an image corresponding to the image data.

Display component

The display elements are not particularly limited, and may be appropriately selected to be suitable for a specific application as long as the display elements of the present invention arranged in a matrix are used.

line

The line is not particularly limited and can be selected to suit a particular application as long as the line is arranged to apply a gate voltage to each of the field effect transistors individually.

Display control device

The display control device is not particularly limited and may be selected to be suitable for a specific application as long as the display control device controls the respective gate voltages of each of the field effect transistors via a plurality of lines in accordance with the image data.

Other components

The other elements are not particularly limited and may be appropriately selected to suit a specific application.

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

The image display device can be applied to portable information devices such as mobile phones, portable audio players, portable video players, electronic books, personal digital assistants (PDAs), and imaging devices such as still cameras and cameras. In addition, the image display can be used for display of various information in mobile systems of vehicles, airplanes, trains, ships, and the like. In addition, the image display device can be applied to display of various information in measurement systems, analysis devices, medical devices, and advertising media.

system

The system of the present invention includes the image display device and image data generating device of the present invention.

The image data generating device generates image data based on the image information to be displayed, and outputs the image data to the image display device.

A display element, an image display device, and a system of the present invention will be described with reference to the drawings.

A television set is illustrated as an embodiment of the system of the present invention.

The television set as an embodiment of the system of the present invention adopts the configuration shown in paragraphs [0038] to [0058] of the Japanese Patent Laid-Open Publication No. 2010-074148 and the configuration shown in FIG.

Next, an image display device of the present invention will be described.

The image display device of the present invention adopts the configurations shown in the paragraphs [0059] and [0060] of the Japanese Patent Laid-Open Publication No. 2010-074148 and the drawings shown in Figs. 1 and 2.

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 in a matrix.

As shown in FIG. 1, the display 310 includes n number of scanning lines (X0, X1, X2, X3, ..., Xn-2, Xn-1) arranged along the X-axis with equal gaps therebetween. The Y-axis sets m number of data lines (Y0, Y1, Y2, Y3, ..., Ym-2, Ym-1) spaced apart from each other with equal gaps, and is disposed with equal gaps along the Y-axis. m number of current supply lines (Y0i, Y1i, Y2i, Y3i, ..., Ym-1i).

Therefore, the display elements can be defined by the scan lines and the data lines.

2 is a schematic view showing an example of a display element of the present invention.

As shown in FIG. 2, the display element includes an organic electroluminescent (EL) element 350 and a driving circuit 320 for causing the organic EL element 350 to emit light. That is, the display 310 is an organic EL display using a so-called active matrix system. In addition, the display 310 is a 32-inch display that supports color. However, the size is not limited to this.

The drive circuit 320 shown in Fig. 2 will be explained.

The drive circuit 320 includes two field effect transistors 11 and 12 and a capacitor 13.

The field effect transistor 11 is used as a switching element. The gate G is connected to a predetermined scan line and the source S is connected to a predetermined data line. In addition, the drain D is connected to one end of the capacitor 13.

The capacitor 13 stores the state of the field effect transistor 11, i.e., data. The other end of the capacitor 13 is connected to a predetermined current supply line.

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

When the field effect transistor 11 is turned on, the field effect transistor 12 drives the organic EL element 350.

As shown in FIG. 3A, each of the field effect transistors 11 and 12 includes, for example, a substrate 21, a gate 22, a gate insulating layer 23, a source electrode 24, a drain electrode 25, and an oxide semiconductor layer 26.

The field effect transistors 11 and 12 can be formed from the materials and processes mentioned in the description of the field effect transistor of the present invention.

4 is a schematic view showing 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 to suit a particular application. For example, an alloy of aluminum (Al), magnesium (Mg), and silver (Ag), an aluminum (Al)-lithium (Li) alloy, and indium tin oxide (ITO) are preferable. An alloy of magnesium (Mg) and silver (Ag) having a sufficient thickness becomes a high reflectance electrode, and an alloy of magnesium (Mg) and silver (Ag) having an extremely thin thickness (about 20 nm) becomes a translucent electrode. In Fig. 4, light is output from the anode side. However, by making the cathode transparent or translucent, light can be output from the cathode.

The material of the anode 314 is not particularly limited and may be appropriately selected to suit a particular application. For example, indium tin oxide (ITO), indium zinc oxide (IZO), and alloys of silver (Ag) and niobium (Nd) are suitable. If an alloy of silver is used, a high reflectivity electrode is obtained which is suitable for outputting light from the negative electrode 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. Electron transport layer 342 is coupled to cathode 312 and hole transport layer 346 is coupled to anode 314. If a predetermined voltage is applied between the anode 314 and the cathode 312, the light-emitting layer 344 emits light.

Preferably, a single layer is formed by the electron transport layer 342 and the light emitting layer 344. Further, it is also preferable to provide an electron injecting layer between the electron transporting layer 342 and the cathode 312. Further, it is preferable to provide a hole injection layer between the hole transport layer 346 and the anode 314.

In FIG. 4, as a light control element, in the case of a so-called "bottom emission" organic EL element, light is output from the substrate side. The light control element may be a "top emission" organic EL element that outputs light from the opposite side of the substrate.

FIG. 5 is a diagram showing an example of a display element in which the organic EL element 350 and the driving circuit 320 are combined.

The display element includes a substrate 31, a first gate 32, a second gate 33, a gate insulating layer 34, a first source 35 and a second source 36, a first drain 37 and a second drain 38, The oxide semiconductor layer 39 and the second oxide semiconductor layer 40, the first passivation layer 41 and the second passivation layer 42, the interlayer insulating layer 43, the organic EL layer 44, and the cathode 45 between the layers. The first drain 37 and the second gate 33 are connected to each other via via holes formed in the gate insulating layer 34. The first oxide semiconductor layer 39 and the second oxide semiconductor layer 40 may be replaced with, for example, the above-described germanium semiconductor layer.

In FIG. 5, a capacitor may be formed between the second gate 33 and the second drain 38 for the sake of convenience. However, the actual position of the capacitor is not limited, and a capacitor having a desired capacity can be appropriately designed at a necessary position.

Further, in the display element shown in FIG. 5, the second drain 38 serves as an anode in the organic EL element 350.

The substrate 31, the first gate 32 and the second gate 33, the gate insulating layer 34, the first source 35, the second source 36, the first drain 37, the second drain 38, and the first oxide semiconductor layer 39. The second oxide semiconductor layer 40 can be formed of the materials and processes mentioned in the description of the field effect transistor of the present invention.

The gate insulating layer 34 corresponds to the gate insulating layer of the field effect transistor of the present invention.

The material of the interlayer insulating layer (planarization layer) 43 is not particularly limited, and may be appropriately selected to suit a specific application. For example, a composite material of an organic material, an inorganic material, an inorganic material, and an organic material is preferred.

Examples of the organic material include resins such as polyimide, acrylic resin, fluororesin, non-fluororesin, olefin resin, oxime resin, and photosensitive resin using these resins.

Specific examples of the inorganic material is a spin-on glass (SOG) material, e.g. AQUAMICA ^TM (manufactured by AZ Electronic Materials plc).

As a composite material of an inorganic material and an organic material, for example, a composite material of an inorganic material and an organic material is formed of a decane compound (disclosed in Japanese Laid-Open Patent Publication No. 2007-158146). The interlayer insulating layer preferably has a barrier property of isolating moisture, oxygen and hydrogen contained in the atmosphere.

The formation process of the interlayer insulating layer is not particularly limited and may be appropriately selected to suit a specific application. For example, it is preferred to directly form a film having a desired shape by a spin coating method, an inkjet printing method, a slit coating method, a nozzle printing method, a gravure printing method, and a dip coating method, or in the case of a photosensitive material. The patterning is performed by photolithography.

After the formation of the interlayer insulating layer, the heat treatment of the interlayer insulating layer is performed as a post-treatment, which is preferable for stabilizing the characteristics of the field effect transistor constituting the display element.

The method of producing the organic EL layer 44 and the cathode 45 is not particularly limited, and may be appropriately selected to suit a particular use. For example, vacuum film forming methods such as vacuum deposition and sputtering, and solution methods such as ink jet and nozzle coating are preferred.

Therefore, it is possible to manufacture a display element as an organic EL element in which so-called "bottom emission" in which light is output from the substrate side is employed. In this case, the substrate 31, the gate insulating layer 34, and the second drain (anode) 38 need to be transparent.

Further, the configuration shown in FIG. 5 has an organic EL element 350 disposed beside the drive circuit 320. However, as shown in FIG. 6, the organic EL element 250 may be disposed on or above the driving circuit 320. Also, this configuration employs "bottom emission" of light output from the substrate side, so that the driving circuit 320 needs to be transparent. For the source, the drain and the anode, conductive transparent oxides such as ITO, In ₂ O ₃ , SnO ₂ , ZnO, Ga-doped ZnO, Al-doped ZnO, and Sb-doped SnO _{2 are} preferably used.

The display control device 400 includes, for example, 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 brightness of the plurality of display elements 302 in the display 310 based on the output signals of the image output.

The scan line driver circuit 404 applies a single voltage to n number of scan lines in accordance with an instruction of the image data processing circuit 402.

The data line drive circuit 406 applies a single voltage to the m number of data lines in accordance with an instruction of the image data processing circuit 402.

In the present embodiment, the organic EL thin film layer includes an electron transport layer, a light emitting layer, and a hole transport layer, but is not limited thereto. For example, the electron transport layer and the light-emitting layer do not have to be separated, but a single layer can be formed. In addition, an electron injection layer may be provided between the electron transport layer and the cathode. Further, a hole injection layer may be provided between the hole transport layer and the anode.

Further, in the present embodiment, the "bottom emission" of the light output from the substrate side will be described, but other possibilities are not excluded. For example, a high reflectance electrode formed of an Ag-Nd alloy may be used as the anode 314, and a translucent electrode formed of an alloy of Mg and Ag or a transparent electrode formed of ITO or the like may be used as the cathode 312 to allow light to pass from the other side of the substrate. Output.

Further, in the present embodiment, the case where the light control element is an organic EL element has been described, but other possibilities are not excluded. For example, the light control element can be an electrochromic element. In this case, display 310 is an electrochromic display.

Additionally, the light control element can be a liquid crystal element. In this case, the display 310 is a liquid crystal display. For example, as shown in Figure 8, the display element 302' does not require a current supply line.

In this case, as shown in FIG. 9, the driving circuit 320' may be composed of a capacitor 15 and a single field effect transistor 14 similar to the field effect transistors 11 and 12 described above. In the field effect transistor 14, the gate G is connected to a predetermined scanning line, and the source S is connected to a predetermined data line. Further, the drain D is connected to the pixel electrode of the liquid crystal element 370 and the capacitor 15.

Fig. 9 also shows the counter electrodes (common electrodes) 16 and 372 of the liquid crystal element 370.

In this embodiment, the light control element can be an electrophoretic element. Additionally, the light management element can be an electrowetting element.

Further, in the present embodiment, a display supporting color is described, but other possibilities are not excluded.

The field effect transistor of the present embodiment can be used for products other than display elements (for example, an IC card and an ID tag).

The display elements, image display devices, and systems using the field effect transistors of the present invention have a long service life under high speed operation.

The preferred embodiments of the present invention have been generally described, and may be further understood by reference to the specific examples provided herein. Not intended to be limiting. In the description of the following examples, numbers indicate weight ratios in some places unless otherwise stated.

Example

Next, the invention will be described in detail with reference to examples, but is not limited thereto. Percentage represents the percentage by mass unless otherwise stated.

Example 1

Manufacture of field effect transistors

Manufacture of gate insulating layer coating liquid

0.16 mL of HMDS (1,1,1,3,3,3-hexamethyldioxane, manufactured by TOKYO OHKA KOGYO CO., LTD.) and 0.28 mL of a toluene solution of magnesium 2-ethylhexanoate (Strem 12-1260, magnesium content: 3% by mass, manufactured by Strem Chemicals, Inc.) was mixed with 1 mL of toluene to obtain a gate insulating layer coating liquid. The oxide formed from the gate insulating layer coating liquid has the components shown in Table 1-1.

A field effect transistor of the lower contact lower gate shown in FIG. 10 was fabricated.

Gate formation

First, a gate 92 is formed on a glass substrate (substrate 91). Specifically, a molybdenum (Mo) film having an average film thickness of about 100 nm was formed on a glass substrate (substrate 91) by DC sputtering. Thereafter, the photoresist is passed through a pre-bake, exposure by an exposure apparatus, and development to form a photoresist pattern of the same pattern as the gate 92. Further, the Mo film in the region where the photoresist pattern is not formed is removed by reactive ion etching (RIE). Then, the photoresist pattern is removed to form a gate 92 made of a Mo film.

Formation of gate insulating layer

Next, 0.4 mL of the gate insulating layer was applied onto the substrate, followed by spin coating (rotation at 3,000 rpm for 20 seconds, and rotation was stopped within 5 seconds). Then, after evaporating at 120 ° C for 1 hour in an atmospheric environment, the obtained material was baked at 400 ° C for 3 hours in an O ₂ atmosphere to form an oxide film as the gate insulating layer 93. The average thickness of the gate insulating layer is approximately 300 nm.

Source and bungee formation

Next, a source electrode 94 and a drain electrode 95 are formed on the gate insulating layer 93.

Specifically, a molybdenum (Mo) film having an average film thickness of about 100 nm is formed on the gate insulating layer 93 by DC sputtering. Thereafter, the photoresist is passed through prebaking, exposure by an exposure apparatus, and development for forming a photoresist pattern of the same pattern as the source 94 and the drain 95 on the Mo film. Further, the Mo film in the region where the photoresist pattern is not formed is removed by reactive ion etching (RIE). Then, the photoresist pattern is removed to form a source 94 and a drain 95 made of a Mo film.

Formation of an oxide semiconductor layer

Next, an oxide semiconductor layer 96 is formed. Specifically, a Mg-In-based oxide (In ₂ MgO ₄ ) film having an average film thickness of about 100 nm was formed by DC sputtering.

Thereafter, the photoresist is passed through prebaking, exposure by an exposure apparatus, and development for forming a photoresist pattern on the Mg-In based oxide film in the same pattern as the oxide semiconductor layer 96. Further, the Mg-In based oxide film located in the region where the photoresist pattern is not formed is removed by wet etching. Thereafter, the photoresist pattern is also removed to form the oxide semiconductor layer 96. Therefore, the oxide semiconductor layer 96 is formed in such a manner that a channel is formed between the source electrode 94 and the drain electrode 95.

Then, as a post-treatment, a field effect transistor was obtained by heating at 300 ° C for 1 hour.

Manufacture of cylindrical objects for measuring linear expansion coefficients

1 L of the gate insulating layer coating liquid of Example 1 was prepared, and the solvent was removed. Then, the obtained product was placed in a platinum crucible, and heated to 1600 ° C to be melted. Then, a cylindrical object having a diameter of 5 mm and a height of 10 mm was produced by a floating method.

Fabrication of capacitors for evaluating relative dielectric constants

Next, a capacitor having the structure shown in Fig. 11 was fabricated.

Specifically, an aluminum (Al) film was formed on the glass substrate (substrate 101) by vacuum vapor deposition using a metal mask having an opening in a region where the bottom electrode 102 was formed, to obtain an average film thickness of about 100 nm. Next, an insulating film 103 having an average film thickness of about 300 nm was formed according to the method described in the gate insulating layer for forming a field effect transistor in Example 1. Then, an aluminum (Al) film having an average film thickness of about 100 nm was formed by vacuum vapor deposition using a metal mask having openings in a region where the upper electrode 104 was formed to complete the fabrication of the capacitor.

Example 2

Manufacture of gate insulating layer coating liquid

0.13 mL of HMDS (1,1,1,3,3,3-hexamethyldioxane, manufactured by TOKYO OHKA KOGYO CO,. LTD.) and 0.47 mL of calcium 2-ethylhexanoate 2- An ethylhexanoic acid solution (Alfa 36657, calcium content: 3 to 8 mass%, manufactured by Alfa Aesar) was mixed with 1 mL of toluene to obtain a gate insulating layer coating liquid. The oxide formed from the gate insulating layer coating liquid has the components shown in Table 1-1.

Using the prepared gate insulating layer coating liquid, a field effect transistor, an object having a columnar shape for measuring a linear expansion coefficient, and a capacitor for evaluating a relative dielectric constant were fabricated according to the same method as in Example 1.

Example 3

Field effect transistor, object with a cylindrical shape for measuring linear expansion coefficient, and capacitor for evaluating relative dielectric constant

Manufacture of gate insulating layer coating liquid

0.14 mL of HMDS (1,1,1,3,3,3-hexamethyldioxane, manufactured by TOKYO OHKA KOGYO CO., LTD.), 0.24 mL of a toluene solution of magnesium 2-ethylhexanoate (Strem 12-1260, magnesium content: 3% by mass, manufactured by Strem Chemicals, Inc.) and 0.95 mL of a toluene solution of bismuth 2-ethylhexanoate (Wako 195-09561, Sr content: 2% by mass, by WAKO) (manufactured by CHEMICAL, LTD.) was mixed with 1 mL of toluene to obtain a gate insulating layer coating liquid. The oxide formed from the gate insulating layer coating liquid has the components shown in Table 1-1.

Using the prepared gate insulating layer coating liquid, a field effect transistor, an object having a columnar shape for measuring a linear expansion coefficient, and a capacitor for evaluating a relative dielectric constant were fabricated according to the same method as in Example 1.

Example 4

Field effect transistor, object with a cylindrical shape for measuring linear expansion coefficient, and capacitor for evaluating relative dielectric constant

Manufacture of gate insulating layer coating liquid

0.17 mL of HMDS (1,1,1,3,3,3-hexamethyldioxane, manufactured by TOKYO OHKA KOGYO CO., LTD.), 0.08 mL of calcium 2-ethylhexanoate 2- Ethylhexanoic acid solution (Alfa 36657, calcium content: 3 to 8 mass%, manufactured by Alfa Aesar) and 0.19 mL of a toluene solution of bismuth 2-ethylhexanoate (Wako 021-09471, Ba content: 8 mass%, manufactured by WAKO CHEMICAL, LTD. ) was mixed with 1 mL of toluene to obtain a gate insulating layer coating liquid. The oxide formed from the gate insulating layer coating liquid has the components shown in Table 1-1.

Using the prepared gate insulating layer coating liquid, a field effect transistor, an object having a columnar shape for measuring a linear expansion coefficient, and a capacitor for evaluating a relative dielectric constant were fabricated according to the same method as in Example 1.

Example 5

Field effect transistor, object with a cylindrical shape for measuring linear expansion coefficient, and capacitor for evaluating relative dielectric constant

Manufacture of gate insulating layer coating liquid

0.13 mL of HMDS (1,1,1,3,3,3-hexamethyldioxane, manufactured by TOKYO OHKA KOGYO CO., LTD.), 0.16 mL of calcium 2-ethylhexanoate 2- Ethylhexanoic acid solution (Alfa 36657, calcium content: 3 to 8 mass%, manufactured by Alfa Aesar), 0.83 mL of a toluene solution of bismuth 2-ethylhexanoate (Wako 195-09561, Sr content: 2% by mass, (manufactured by WAKO CHEMICAL, LTD.) and 0.38 mL of a toluene solution of bismuth 2-ethylhexanoate (Wako 021-09471, Ba content: 8 mass%, manufactured by WAKO CHEMICAL, LTD.) mixed with 1 mL of toluene to A gate insulating layer coating liquid is obtained.

The oxide formed from the gate insulating layer coating liquid has the components shown in Table 1-1.

Using the prepared gate insulating layer coating liquid, a field effect transistor, an object having a columnar shape for measuring a linear expansion coefficient, and a capacitor for evaluating a relative dielectric constant were fabricated according to the same method as in Example 1.

Example 6

Field effect transistor, object with a cylindrical shape for measuring linear expansion coefficient, and capacitor for evaluating relative dielectric constant

Manufacture of gate insulating layer coating liquid

0.14 mL of HMDS (1,1,1,3,3,3-hexamethyldioxane, manufactured by TOKYO OHKA KOGYO CO., LTD.), 0.06 mL of di(2-butoxy)acetamidine Aluminum acetate chelate (Alfa 89349, Al content: 8.4%, manufactured by Alfa Aesar) and 0.51 mL of 2-ethylhexyl A toluene solution of toluic acid (Wako 021-09471, Ba content: 8 mass%, manufactured by WAKO CHEMICAL, LTD.) was mixed with 1 mL of toluene to obtain a gate insulating layer coating liquid.

The oxide formed from the gate insulating layer coating liquid has the components shown in Table 1-2.

Using the prepared gate insulating layer coating liquid, a field effect transistor, an object having a columnar shape for measuring a linear expansion coefficient, and a capacitor for evaluating a relative dielectric constant were fabricated according to the same method as in Example 1.

Example 7

Field effect transistor, object with a cylindrical shape for measuring linear expansion coefficient, and capacitor for evaluating relative dielectric constant

Manufacture of gate insulating layer coating liquid

0.15 mL of HMDS (1,1,1,3,3,3-hexamethyldioxane, manufactured by TOKYO OHKA KOGYO CO., LTD.), 0.06 g (4, 4, 5, 5 - 4) Methyl-1,3,2-dioxaborolan-2-yl)benzene (Wako 325-59912, manufactured by WAKO CHEMICAL, LTD.), 0.07 mL of toluene of magnesium 2-ethylhexanoate Solution (Strem 12-1260, magnesium content: 3% by mass, manufactured by Strem Chemicals, Inc.) and 0.23 mL of a toluene solution of bismuth 2-ethylhexanoate (Wako 195-09561, Sr content: 2% by mass, WAKO CHEMICAL, LTD.) was mixed with 1 mL of toluene to obtain a gate insulating layer coating liquid.

The oxide formed from the gate insulating layer coating liquid has the components shown in Table 1-2.

Using the prepared gate insulating layer coating liquid, a field effect transistor, an object having a columnar shape for measuring a linear expansion coefficient, and a capacitor for evaluating a relative dielectric constant were fabricated according to the same method as in Example 1.

Example 8

Field effect transistor, object with a cylindrical shape for measuring linear expansion coefficient, and capacitor for evaluating relative dielectric constant

Manufacture of gate insulating layer coating liquid

0.13 mL of HMDS (1,1,1,3,3,3-hexamethyldioxane, manufactured by TOKYO OHKA KOGYO CO., LTD.), 0.08 mL of di(2-butoxy)acetamidine Aluminum acetate chelate (Alfa 89349, Al content: 8.4%, manufactured by Alfa Aesar), 0.13 mL of 2-ethyl oxalic acid Calcium 2-ethylhexanoic acid solution (Alfa 36657, Ca content: 3 to 8 mass%, manufactured by Alfa Aesar) and 0.64 mL of toluene solution of bismuth 2-ethylhexanoate (Wako 195-09561, Sr content: 2% by mass, manufactured by WAKO CHEMICAL, LTD.), was mixed with 1 mL of toluene to obtain a gate insulating layer coating liquid.

The oxide formed from the gate insulating layer coating liquid has the components shown in Table 1-2.

Using the prepared gate insulating layer coating liquid, a field effect transistor, an object having a columnar shape for measuring a linear expansion coefficient, and a capacitor for evaluating a relative dielectric constant were fabricated according to the same method as in Example 1.

Example 9

Field effect transistor, cylindrical object for measuring linear expansion coefficient, and capacitor for evaluating relative dielectric constant

Manufacture of gate insulating layer coating liquid

0.11 mL of HMDS (1,1,1,3,3,3-hexamethyldioxane, manufactured by TOKYO OHKA KOGYO CO., LTD.), 0.12 g (4, 4, 5, 5 - 4) Methyl-1,3,2-dioxaborolan-2-yl)benzene (Wako 325-59912, manufactured by WAKO CHEMICAL, LTD.) and 0.18 mL of toluene of 2-ethylhexanoate A solution (Strem 12-1260, magnesium content: 3% by mass, manufactured by Strem Chemicals, Inc.) was mixed with 1 mL of toluene to obtain a gate insulating layer coating liquid.

The oxide formed from the gate insulating layer coating liquid has the components shown in Table 1-2.

Using the prepared gate insulating layer coating liquid, a field effect transistor, an object having a columnar shape for measuring a linear expansion coefficient, and a capacitor for evaluating a relative dielectric constant were fabricated according to the same method as in Example 1.

Example 10

Field effect transistor, object with a cylindrical shape for measuring linear expansion coefficient, and capacitor for evaluating relative dielectric constant

Manufacture of gate insulating layer coating liquid

0.13 mL of HMDS (1,1,1,3,3,3-hexamethyldioxane, manufactured by TOKYO OHKA KOGYO CO., LTD.), 0.06 mL of di(2-butoxy)acetamidine Aluminum acetate chelate (Alfa 89349, Al content: 8.4%, manufactured by Alfa Aesar), 0.07 g (4,4,5,5-tetramethyl-1,3,2-dioxaborolan) Alkan-2-yl)benzene (Wako 325-59912, by WAKO (manufactured by CHEMICAL, LTD.), 0.07 mL of 2-ethylhexanoic acid in 2-ethylhexanoic acid (Alfa 36657, Ca content: 3 to 8 mass%, manufactured by Alfa Aesar) and 0.14 mL of 2-B A toluene solution of bismuth hexanoate (Wako 195-09561, Sr content: 2% by mass, manufactured by WAKO CHEMICAL, LTD.) was mixed with 1 mL of toluene to obtain a gate insulating layer coating liquid.

The oxide formed from the gate insulating layer coating liquid has the components shown in Table 1-2.

Using the prepared gate insulating layer coating liquid, a field effect transistor, an object having a columnar shape for measuring a linear expansion coefficient, and a capacitor for evaluating a relative dielectric constant were fabricated according to the same method as in Example 1.

Example 11

Field effect transistor, object with a cylindrical shape for measuring linear expansion coefficient, and capacitor for evaluating relative dielectric constant

Manufacture of gate insulating layer coating liquid

0.14 mL of HMDS (1,1,1,3,3,3-hexamethyldioxane, manufactured by TOKYO OHKA KOGYO CO., LTD.), 0.07 mL of di(2-butoxy)acetamidine Aluminum acetate (Alfa 89349, Al content: 8.4%, manufactured by Alfa Aesar), 0.02 g of (4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2 -yl)benzene (Wako 325-59912, manufactured by WAKO CHEMICAL, LTD.), and 0.11 mL of a toluene solution of magnesium 2-ethylhexanoate (Strem 12-1260, magnesium content: 3% by mass, from Strem Chemicals, Inc. manufactured by mixing with 1 mL of toluene to obtain a gate insulating layer coating liquid.

The oxide formed from the gate insulating layer coating liquid has the compositions shown in Tables 1-3.

Using the prepared gate insulating layer coating liquid, a field effect transistor, an object having a columnar shape for measuring a linear expansion coefficient, and a capacitor for evaluating a relative dielectric constant were fabricated according to the same method as in Example 1.

Example 12

Field effect transistor, object with a cylindrical shape for measuring linear expansion coefficient, and capacitor for evaluating relative dielectric constant

Manufacture of gate insulating layer coating liquid

0.11 mL of HMDS (1,1,1,3,3,3-hexamethyldioxane, manufactured by TOKYO OHKA KOGYO CO., LTD.), 0.06 mL of di(2-butoxy)acetamidine Aluminum acetate chelate (Alfa 89349, Al content: 8.4%, manufactured by Alfa Aesar), 0.07 g (4,4,5,5-tetramethyl-1,3,2-dioxaborolan) Alkan-2-yl)benzene (Wako 325-59912, manufactured by WAKO CHEMICAL, LTD.), 0.03 mL of 2-ethylhexanoic acid solution of calcium 2-ethylhexanoate (Alfa 36657, Ca content: 3-8) (% by mass, manufactured by Alfa Aesar) and 0.48 mL of a toluene solution of bismuth 2-ethylhexanoate (Wako 021-09471, Ba content: 8 mass%, manufactured by WAKO CHEMICAL, LTD.) mixed with 1 mL of toluene to A gate insulating layer coating liquid is obtained.

The oxide formed from the gate insulating layer coating liquid has the compositions shown in Tables 1-3.

Using the prepared gate insulating layer coating liquid, a field effect transistor, an object having a columnar shape for measuring a linear expansion coefficient, and a capacitor for evaluating a relative dielectric constant were fabricated according to the same method as in Example 1.

Example 13

Field effect transistor, object with a cylindrical shape for measuring linear expansion coefficient, and capacitor for evaluating relative dielectric constant

Manufacture of gate insulating layer coating liquid

0.11 mL of HMDS (1,1,1,3,3,3-hexamethyldioxane, manufactured by TOKYO OHKA KOGYO CO., LTD.), 0.10 mL of di(2-butoxy)acetamidine Aluminum acetate chelate (Alfa 89349, Al content: 8.4%, manufactured by Alfa Aesar), 0.07 g (4,4,5,5-tetramethyl-1,3,2-dioxaborolan) Alkan-2-yl)benzene (Wako 325-59912, manufactured by WAKO CHEMICAL, LTD.), 0.09 mL of 2-ethylhexanoic acid 2-ethylhexanoic acid solution (Alfa 36657, Ca content: 3-8) (% by mass, manufactured by Alfa Aesar) and 0.19 mL of a toluene solution of bismuth 2-ethylhexanoate (Wako 195-09561, Sr content: 2% by mass, manufactured by WAKO CHEMICAL, LTD.) mixed with 1 mL of toluene to A gate insulating layer coating liquid is obtained.

The oxide formed from the gate insulating layer coating liquid has the compositions shown in Tables 1-3.

Using the prepared gate insulating layer coating liquid, a field effect transistor, an object having a columnar shape for measuring a linear expansion coefficient, and a capacitor for evaluating a relative dielectric constant were fabricated according to the same method as in Example 1.

Comparison example 1

Field effect transistor, object with a cylindrical shape for measuring linear expansion coefficient, and capacitor for evaluating relative dielectric constant

Manufacture of gate insulating layer coating liquid

0.19 mL of HMDS (1,1,1,3,3,3-hexamethyldioxane, manufactured by TOKYO OHKA KOGYO CO., LTD.) was mixed with 1 mL of toluene to obtain a gate insulating layer coating. Cloth liquid.

The oxide formed from the gate insulating layer coating liquid has the compositions shown in Tables 1-3.

Using the prepared gate insulating layer coating liquid, a field effect transistor, an object having a columnar shape for measuring a linear expansion coefficient, and a capacitor for evaluating a relative dielectric constant were fabricated according to the same method as in Example 1.

Comparison example 2

Manufacture of field effect transistors

A gate was fabricated on a glass substrate in the same manner as in Example 1. Forming a gate insulating layer

Next, using SiCl ₄ as a raw material, an SiO ₂ layer as a gate insulating layer was formed on the above substrate and gate insulating layer in accordance with a plasma enhanced chemical vapor deposition (PECVD) method. The gate insulating layer has an average thickness of about 300 nm.

Next, a source, a drain, and an oxide semiconductor layer were formed in accordance with the method of Example 1, followed by a heating process to complete the field effect transistor.

Manufacture of cylindrical objects for measuring linear expansion coefficients

As a raw material, SiCl ₄ is hydrolyzed in an oxyhydrogen flame to obtain a cerium oxide powder. The cerium oxide powder thus obtained was grown to obtain a SiO ₂ porous solid. Then, the porous solid of SiO _{2 was} placed in a platinum crucible and heated and melted at 1600 °C. Then, a cylindrical object having a diameter of 5 mm and a height of 10 mm was produced by a suspension method.

Fabrication of capacitors for evaluating relative dielectric constants

In the same manner as in Example 1, an aluminum (Al) film was formed on the glass substrate (substrate 101) by vacuum vapor deposition using a metal mask having an opening in a region where the bottom electrode 102 was formed to obtain about 100 nm. Average film thickness.

Next, using SiCl ₄ as a raw material, the insulating film 103 is formed according to a plasma enhanced chemical vapor deposition (PECVD) method.

Then, an aluminum (Al) film having an average film thickness of about 100 nm was formed by vacuum vapor deposition using a metal mask having openings in a region where the upper electrode 104 was formed, to complete fabrication of the capacitor.

Evaluation of stripping of field effect transistors

The appearance of the field effect transistors fabricated in Examples 1 to 13 and Comparative Examples 1 and 2 was evaluated, and the results are shown in Table 2. As shown in Table 2, regarding the field effect transistors manufactured in Examples 1 to 13, no peeling of the gate, the gate insulating layer, the source, the drain, and the semiconductor layer was observed.

On the other hand, for the field effect transistors fabricated in Comparative Examples 1 and 2, peeling occurred between the gate and the gate insulating layer.

Evaluation of linear expansion coefficient

The average linear expansion coefficients of the cylindrical objects of Examples 1 to 13 and Comparative Examples 1 and 2 were measured by a thermomechanical analyzer (8310 series, manufactured by Rigaku Corporation) in a temperature range of 20 to 300 °C. The results of Examples 1 to 13 and Comparative Examples 1 and 2 are shown in Table 2.

As shown in Table 2, although the cylindrical expansion-like objects manufactured in Examples 1 to 13 have a linear expansion coefficient of 21.7 × 10 ^-7 to 77.9 × 10 ^-7 /K, they were produced in Comparative Examples 1 and 2. The linear expansion coefficient of a cylindrical object is small, that is, 5.2 × 10 ^-7 ~ 5.4 × 10 ^-7 /K.

The reason why the peeling in the field effect transistor of Examples 1 and 2 was compared in the evaluation of the peeling of the field effect transistor was that thermal stress occurred during the heating process because the linear expansion coefficient of the gate insulating layer was 5.2 × 10 ^-7 ~ 5.4. ×10 ^-7 /K, which is very small compared to the linear expansion coefficients of the gate, source and drain. On the other hand, regarding the field effect transistors of Examples 1 to 13, since the difference between the linear expansion coefficient of the gate insulating layer and the linear expansion coefficient of the gate, the source, and the drain was small, peeling did not occur.

Relative dielectric constant evaluation

The capacities of the capacitors fabricated in Examples 1 to 13 and Comparative Examples 1 and 2 were measured by an LCR meter (4284A, manufactured by Agilent Technologies). The relative dielectric constant ε calculated by the value of the capacity and dielectric loss (tan δ) measured at a frequency of 1 kHz is shown in Table 2.

Fig. 12 is a graph showing the relationship between the relative dielectric constant ε and the dielectric loss (tan δ) in Example 13 and the frequency of the applied electric field. According to Fig. 12, it was confirmed that the capacitor fabricated in Example 13 had a relative dielectric constant of 5.1 to 5.3 in the range of 100 Hz to 1 MHz.

Further, it was confirmed that the value of the dielectric loss (tan δ) was small, and was not more than about 1% in the range of 100 Hz to 100 kHz.

Fig. 13 is a graph showing the relationship between the relative dielectric constant ε and the dielectric loss (tan δ) in Comparative Example 1 and the frequency of the applied electric field. According to Fig. 13, it was confirmed that the capacitor fabricated in Comparative Example 1 had a relative dielectric constant of 3.9 to 4.0 in the range of 100 Hz to 1 MHz. Further, it was confirmed that the value of the dielectric loss (tan δ) was small, and was not more than about 1% in the range of 100 Hz to 100 kHz.

Evaluation of the transistor characteristics of field effect transistors

The transistor characteristics of the field effect transistors fabricated in Examples 1 to 13 and Comparative Examples 1 and 2 were evaluated by a semiconductor device parameter analyzer (B1500A, manufactured by Agilent Technologies). As the transistor characteristics, when the voltage (Vds) between the drain 95 and the source 94 is set to +20 V, the voltage (Vgs) between the gate 92 and the source 94 and the drain 95 and the source 94 are measured. The relationship between the currents (Ids) (Vgs-Ids).

Further, the field effect mobility in the saturation region was calculated from the evaluation results of the transistor characteristics (Vgs-Ids). In addition, the ratio (on/off ratio) of the Ids of the on state (for example, Vgs=+10 V) of the transistor and the off state (for example, Vgs=−10 V) is calculated.

In addition, the sub-critical swing (SS) is calculated as the sharpness index of the rise of Ids for the application of Vgs. In addition, the threshold voltage (Vth) is calculated as a voltage value at which Ids rises for applying Vgs.

14 is a graph showing the results of the transistor characteristics (Vgs-Ids) of the field effect transistor fabricated in Example 13. In addition, the mobility, on/off ratio, subcritical swing (SS), and Vth calculated according to the transistor characteristics of the field effect transistors fabricated in Examples 1 to 13 and Comparative Examples 1 and 2 are shown in Table 2. . Hereinafter, in the results of the transistor characteristics, when the mobility is high, the on/off ratio is high, the subcritical swing (SS) is low, and Vth is about 0 V, the transistor characteristics are evaluated to be excellent.

The "e" of the Y-axis in the graph of Fig. 14 indicates "index of 10". For example, "1e-3" means 1.0 × 10 ^-3 or 0.001, and "1e + 5" means 1.0 × 10 ^{+ 5} or 100,000.

As shown in FIG. 14 and Table 2, the field effect transistor fabricated in Example 13 had excellent transistor characteristics. Similarly, as shown in Table 2, each field effect transistor manufactured in Examples 1 to 13 had excellent transistor characteristics.

On the other hand, since the field effect transistors manufactured in Comparative Examples 1 and 2 were peeled off, it was impossible to evaluate the transistor characteristics.

Result table

Examples of the invention are as follows.

A field effect transistor comprising a gate configured to apply a gate voltage; a source and a drain configured to output current; a semiconductor layer disposed adjacent to the source and the drain; and a A gate insulating layer is disposed between the gate and the semiconductor layer, wherein the gate insulating layer comprises an oxide containing germanium and one or two or more alkaline earth metal elements.

2. The field effect transistor according to above 1, wherein the oxide comprises aluminum and/or boron.

3. The field effect transistor according to 1 or 2 above, wherein the semiconductor layer is an oxide semiconductor.

A display element comprising a light control element for controlling light output according to a driving signal; and a driving circuit comprising the field effect transistor according to any one of the above 1 to 3 and configured to drive the light control element .

5. The display element according to the above 4, wherein the light control element comprises an electroluminescent element, an electrochromic element, a liquid crystal element, an electrophoretic element and an electrowetting element.

6. An image display device comprising a plurality of display elements arranged in a matrix form, each of the plurality of display elements being a display element according to the above 4; a plurality of lines, individually gate voltages and signals And applying voltage to the field effect transistors in the plurality of display elements; and a display control device for individually controlling gate voltages and signal voltages of the field effect transistors via the plurality of lines according to the image data.

A system comprising the image display device according to the above 6, and an image data generating device that generates image data based on the image information to be displayed and outputs the image data to the image display device.

8. A composition for a gate insulator (e.g., a gate insulating film) for a field effect transistor, comprising a monooxide comprising cerium and one or two or more alkaline earth metal elements.

As described above, the field effect transistor of the present invention is not peeled off between the gate, the source and the drain and the gate insulating layer due to the heating process.

The embodiments of the present invention have been fully described, and it will be apparent to those skilled in the art that many variations and modifications can be made without departing from the spirit and scope of the embodiments of the invention.

Claims (8)

A field effect transistor comprising: a gate configured to apply a gate voltage; a source and a drain configured to output current; a semiconductor layer disposed adjacent to the source and the drain; and a gate A pole insulating layer is disposed between the gate and the semiconductor layer, wherein the gate insulating layer comprises an oxide containing germanium and one or two or more alkaline earth metal elements. The field effect transistor of claim 1, wherein the oxide comprises aluminum and/or boron. The field effect transistor according to claim 1, wherein the semiconductor layer is an oxide semiconductor. A display element comprising: a light control element configured to control light output according to a driving signal; and a driving circuit comprising the field effect transistor according to claim 1 and configured to drive the light control element. The display element of claim 4, wherein the light control element comprises an electroluminescent element, an electrochromic element, a liquid crystal element, an electrophoretic element, and an electrowetting element. An image display device comprising: a plurality of display elements arranged in a matrix form, each of the plurality of display elements being a display element according to claim 4; a plurality of lines configured to be individually Applying a gate voltage and a signal voltage to the field effect transistors in the plurality of display elements; and a display control device configured to individually control the field effect transistors via the plurality of lines according to the image data The gate voltage and the signal voltage. A system comprising: the image display device according to claim 6; An image data generating device configured to generate image data based on the image information to be displayed and output the image data to the image display device. A composition for a gate insulator of a field effect transistor, comprising: a monooxide comprising cerium and one or more alkaline earth metal elements.