JP2018157210A - Field effect transistor and manufacturing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress etching damage to a gate insulating layer when a conductive film on the gate insulating layer is patterned in a manufacturing method of a field effect transistor having a gate insulating layer formed of a complex metal oxide.SOLUTION: A manufacturing method of a field effect transistor in which a hydrofluoric acid type etching solution is used for wet etching includes a substrate, a source electrode, a drain electrode, and a gate electrode formed on the substrate, an active layer, and a gate insulating layer provided between the gate electrode and the active layer includes a step of forming a composite metal oxide film including an element A and an element B to form a gate insulating layer and a step of forming a conductive film on the gate insulating layer and forming a conductive film in a predetermined shape by wet etching to form a source electrode and a drain electrode or a gate electrode.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a field effect transistor and a method for manufacturing the field effect transistor.

  A field effect transistor (FET) has a low gate current and has a planar structure, and thus can be easily manufactured and integrated as compared with a bipolar transistor. Therefore, the FET is an indispensable element in the integrated circuit used in the current electronic equipment.

  Conventionally, a silicon-based insulating film has been widely used for a gate insulating layer of a field effect transistor. However, in recent years, demands for higher integration and lower power consumption of electronic devices have increased, and a technique using a material having a higher relative dielectric constant than a silicon-based insulating film as a gate insulating layer has been proposed. As insulating materials having a high relative dielectric constant, composite metal oxides of alkaline earth metals and rare earth metals have been disclosed (see, for example, Patent Documents 1 and 2).

  The present invention suppresses etching damage to a gate insulating layer when patterning a conductive film on the gate insulating layer in a method of manufacturing a field effect transistor having a gate insulating layer formed of a composite metal oxide film. For the purpose.

The method for producing a field effect transistor according to the present invention includes:
A channel is formed between the source electrode and the drain electrode by applying a predetermined voltage to the base material, the source electrode, the drain electrode, and the gate electrode formed on the base material, and the gate electrode. A method of manufacturing a field effect transistor, comprising: an active layer to be formed; and a gate insulating layer provided between the gate electrode and the active layer,
Forming a composite metal oxide film containing an element A that is an alkaline earth metal and a B element that is at least one of Ga, Sc, Y, and a lanthanoid, and forming the gate insulating layer; ,
Forming a conductive film on the gate insulating layer, forming the conductive film into a predetermined shape by wet etching, and forming the source electrode and the drain electrode, or the gate electrode,
A hydrofluoric acid etching solution is used for the wet etching.

  According to the disclosed technology, in a method of manufacturing a field effect transistor having a gate insulating layer formed of a composite metal oxide, etching damage to the gate insulating layer is caused when the conductive film on the gate insulating layer is patterned. Can be suppressed.

FIG. 1 is a cross-sectional view illustrating a field effect transistor according to an embodiment. FIG. 2A is a diagram illustrating a manufacturing step of the field-effect transistor according to the embodiment (part 1). FIG. 2B is a diagram illustrating the manufacturing process of the field-effect transistor according to the embodiment (part 2). FIG. 2C is a diagram illustrating a manufacturing step of the field-effect transistor according to the embodiment (part 3). FIG. 2D is a diagram illustrating a manufacturing step of the field effect transistor according to the embodiment (part 4); FIG. 2E is a diagram illustrating the manufacturing process of the field-effect transistor according to the embodiment (No. 5). FIG. 3A is a cross-sectional view illustrating a field effect transistor according to a modification of the embodiment. FIG. 3B is a cross-sectional view illustrating a field effect transistor according to a modification of the embodiment. FIG. 4 is a cross-sectional view illustrating a field effect transistor according to a modification of the embodiment. FIG. 5A is a cross-sectional view illustrating a field effect transistor according to a modification of the embodiment. FIG. 5B is a cross-sectional view illustrating a field effect transistor according to a modification of the embodiment. FIG. 6 is a block diagram illustrating a configuration of a television device according to another embodiment. FIG. 7 is an explanatory diagram (1) of a television device according to another embodiment. FIG. 8 is an explanatory diagram (2) of a television device according to another embodiment. FIG. 9 is an explanatory diagram (3) of a television device according to another embodiment. FIG. 10 is an explanatory diagram of a display element in another embodiment. FIG. 11 is an explanatory diagram of an organic EL according to another embodiment. FIG. 12 is an explanatory diagram (4) of a television device according to another embodiment. FIG. 13 is an explanatory diagram (1) of another display element in another embodiment. FIG. 14 is an explanatory diagram (2) of another display element in another embodiment.

In Japanese Patent Application Laid-Open No. 2015-111653 and Japanese Patent No. 5633346, when a composite metal oxide film is used as the gate insulating layer, the gate insulating layer is damaged in the etching process of the electrode that is an upper layer of the gate insulating layer. There is no disclosure about this.
However, the present inventors have found that when a composite metal oxide film is used as the gate insulating layer, the gate insulating layer is damaged in the etching process of the electrode that is the upper layer of the gate insulating layer.
If the gate insulating layer is damaged such as film loss, a leak current or the like is generated, which adversely affects the electric characteristics of the field effect transistor.
Therefore, the inventors of the present invention, in a method for manufacturing a field effect transistor having a gate insulating layer formed of a composite metal oxide, etch damage to the gate insulating layer when patterning the conductive film on the gate insulating layer. In order to suppress this, intensive studies were conducted and the present invention was completed.

(Field Effect Transistor Manufacturing Method and Field Effect Transistor)
The field effect transistor manufacturing method of the present invention includes a base material, a source electrode, a drain electrode, and a gate electrode formed on the base material, and a predetermined voltage applied to the gate electrode. A method of manufacturing a field effect transistor having an active layer in which a channel is formed between an electrode and the drain electrode, and a gate insulating layer provided between the gate electrode and the active layer.
In the method of manufacturing the field effect transistor, a composite metal oxide film including an element A that is an alkaline earth metal and a element B that is at least one of Ga, Sc, Y, and a lanthanoid is formed. And forming the gate insulating layer.
In the method of manufacturing the field effect transistor, a conductive film is formed on the gate insulating layer, the conductive film is formed into a predetermined shape by wet etching, and the source electrode and the drain electrode or the gate electrode is formed. Process.
A hydrofluoric acid etching solution is used for the wet etching.

  When forming a conductive film on the gate insulating layer, the active layer may be formed on a part of the gate insulating layer. In that case, the conductive film may be formed to cover the active layer.

  The hydrofluoric acid-based etchant preferably contains at least one of hydrogen fluoride, ammonium fluoride, and ammonium hydrogen fluoride.

  The composite metal oxide film preferably contains a paraelectric amorphous oxide or is a paraelectric amorphous oxide itself.

  The composite metal oxide film preferably further includes a C element that is at least one of Al, Ti, Zr, Hf, Nb, and Ta.

  The conductive film preferably contains any one of Al, Ti, Zr, Ta, and Nb, an alloy of these elements, or a mixture thereof.

  The conductive film preferably contains a conductive oxide of any one of indium oxide, zinc oxide, and titanium oxide.

  The active layer is preferably an oxide semiconductor.

<Field effect transistor>
In the field effect transistor of the present invention, a gate electrode or electrodes that are a source electrode and a drain electrode are provided on a gate insulating layer.
The electrode is a conductive film having a predetermined shape dissolved by a hydrofluoric acid-based etching solution.

  In the field effect transistor, for example, the electrode is a conductive film having a predetermined shape (for example, Al, indium oxide, oxidation) formed by dissolving the electrode with a PAN-based etchant (mixed solution of phosphoric acid, acetic acid, and nitric acid). The thickness of the gate insulating layer directly below the electrode and the thickness of the gate insulating layer other than directly below the electrode, the thickness of the gate insulating layer directly below the electrode, The difference with the thickness of the gate insulating layer other than directly under the electrode is small.

  Hereinafter, embodiments for carrying out the invention will be described with reference to the drawings. In the drawings, the same components are denoted by the same reference numerals, and redundant description may be omitted.

FIG. 1 is a cross-sectional view illustrating a field effect transistor manufactured according to the present invention.
Referring to FIG. 1, a field effect transistor 10 includes a base 11, a gate electrode 12, a gate insulating layer 13, an active layer 14, a source electrode 15, and a drain electrode 16. This is a contact-type field effect transistor. The field effect transistor 10 is a typical example of a semiconductor device according to the present invention.

  In the field effect transistor 10, a gate electrode 12 is formed on an insulating substrate 11, and a gate insulating layer 13 is formed so as to cover the gate electrode 12. An active layer 14 is formed on the gate insulating layer 13, and a source electrode 15 and a drain electrode 16 are formed on the active layer 14 so that a channel is formed in the active layer 14. Hereinafter, each component of the field effect transistor 10 will be described in detail.

  In this embodiment, for the sake of convenience, the active layer 14 side is the upper side or one side, and the base material 11 side is the lower side or the other side. Also, the surface on the active layer 14 side of each part is the upper surface or one surface, and the surface on the substrate 11 side is the lower surface or the other surface. However, the field effect transistor 10 can be used upside down, or can be arranged at an arbitrary angle. Moreover, planar view refers to viewing the object from the normal direction of the upper surface of the base material 11, and planar shape refers to the shape of the object viewed from the normal direction of the upper surface of the base material 11. .

<Base material>
There is no restriction | limiting in particular as a shape of the base material 11, a structure, and a magnitude | size, According to the objective, it can select suitably. There is no restriction | limiting in particular as a material of the base material 11, Although it can select suitably according to the objective, For example, a glass base material, a ceramic base material, a plastic base material, a film base material etc. can be used.

  There is no restriction | limiting in particular as a glass base material, According to the objective, it can select suitably, For example, an alkali free glass, silica glass, etc. are mentioned. Moreover, there is no restriction | limiting in particular as a plastic base material or a film base material, Although it can select suitably according to the objective, For example, a polycarbonate (PC), a polyimide (PI), a polyethylene terephthalate (PET), a polyethylene naphthalate (PEN) and the like.

<Gate electrode>
The gate electrode 12 is formed in a predetermined region on the base material 11. The gate electrode 12 is an electrode for applying a gate voltage.

  There is no restriction | limiting in particular as a material of the gate electrode 12, According to the objective, it can select suitably, For example, aluminum (Al), platinum (Pt), palladium (Pd), gold (Au), silver (Ag) , Copper (Cu), zinc (Zn), nickel (Ni), chromium (Cr), tantalum (Ta), molybdenum (Mo), titanium (Ti) and other metals, alloys thereof, mixtures of these metals, etc. be able to. In addition, conductive oxides such as indium oxide, zinc oxide, tin oxide, gallium oxide, and niobium oxide, composite compounds thereof, mixtures thereof, and the like may be used.

  There is no restriction | limiting in particular as an average film thickness of the gate electrode 12, Although it can select suitably according to the objective, 10 nm-1 micrometer are preferable and 50 nm-300 nm are more preferable.

<Gate insulation layer>
The gate insulating layer 13 is provided between the gate electrode 12 and the active layer 14 and is a layer for insulating the gate electrode 12 and the active layer 14. There is no restriction | limiting in particular as an average film thickness of the gate insulating layer 13, Although it can select suitably according to the objective, 50 nm-3 micrometers are preferable, and 100 nm-1 micrometer are more preferable.

The gate insulating layer 13 is a composite metal oxide film.
The composite metal oxide film contains at least an element A that is an alkaline earth metal and a B element that is at least one of gallium (Ga), scandium (Sc), yttrium (Y), and a lanthanoid, Preferably, it contains a C element that is at least one of aluminum (Al), titanium (Ti), zirconium (Zr), hafnium (Hf), niobium (Nb), and tantalum (Ta), and further if necessary And other ingredients.

  The alkaline earth metal contained in the composite metal oxide film may be one type or two or more types. Examples of alkaline earth elements include beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), and radium (Ra).

  Lanthanoids include lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium. (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), and lutetium (Lu).

  The composite metal oxide film preferably contains a paraelectric amorphous oxide or is formed of the paraelectric amorphous oxide itself. The paraelectric amorphous oxide is stable in the atmosphere and can stably form an amorphous structure in a wide composition range. However, crystals may be included in part of the composite metal oxide film.

  Alkaline earth oxides easily react with moisture and carbon dioxide in the atmosphere and easily change to hydroxides and carbonates, and are not suitable for application to electronic devices alone. In addition, simple oxides such as lanthanoids excluding Ga, Sc, Y, and Ce are easily crystallized, and leakage current becomes a problem. However, a complex oxide system of an alkaline earth metal and a lanthanoid excluding Ga, Sc, Y, and Ce is stable in the atmosphere and can form an amorphous film in a wide composition range. Ce is specifically tetravalent among lanthanoids and forms crystals with a perovskite structure with an alkaline earth metal. Therefore, in order to obtain an amorphous phase, lanthanoids other than Ce are preferable.

  A crystal phase such as a spinel structure exists between the alkaline earth metal and the Ga oxide, but these crystals do not precipitate unless the temperature is very high (generally 1000 ° C. or higher) as compared with the perovskite structure crystal. . In addition, the existence of a stable crystal phase has not been reported between alkaline earth metal oxides and oxides composed of lanthanoids excluding Sc, Y, and Ce. Crystal precipitation is rare. Further, when a complex oxide of an alkaline earth metal and a lanthanoid excluding Ga, Sc, Y, and Ce is composed of three or more metal elements, the amorphous phase is further stabilized.

  The content of each element contained in the composite metal oxide film is not particularly limited, but may contain a metal element selected from each element group so as to have a composition capable of taking a stable amorphous state. preferable.

  From the viewpoint of producing a high dielectric constant film, it is preferable to increase the composition ratio of elements such as Ba, Sr, Lu, and La.

Since the composite metal oxide film according to this embodiment can form an amorphous film in a wide composition range, the physical properties can also be controlled widely. For example, although the relative dielectric constant is about 6 to 20 and is sufficiently higher than that of SiO ₂ , it can be adjusted to an appropriate value according to the application by selecting the composition.

Further, the thermal expansion coefficient is equivalent to that of general wiring materials and semiconductor materials having 10 ⁻⁶ to 10 ⁻⁵ , and even if the heating process is repeated as compared with SiO ₂ having a thermal expansion coefficient of 10 ⁻⁷ units, the film There are few troubles such as peeling. In particular, a favorable interface is formed with an oxide semiconductor such as a-IGZO.
Therefore, by using the composite metal oxide film according to the present embodiment for the gate insulating layer 13, a high-performance semiconductor device can be obtained.

  There is no restriction | limiting in particular as a formation method of a gate insulating layer, According to the objective, it can select suitably, For example, the method of forming using the following coating liquid for insulating layer formation is mentioned.

<< Coating liquid for insulating layer formation >>
The coating liquid for forming an insulating layer contains at least an alkaline earth metal-containing compound (A-element-containing compound), a B-element-containing compound, and a solvent, preferably a C-element-containing compound, If necessary, other components are contained.

-Alkaline earth metal-containing compound (element A-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 inorganic alkaline earth metal compounds include alkaline earth metal nitrates, alkaline earth metal sulfates, alkaline earth metal chlorides, alkaline earth metal fluorides, alkaline earth metal bromides, and alkaline earth metal iodides. Etc.
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, barium chloride and the like.
Examples of the alkaline earth metal fluoride include magnesium fluoride, calcium fluoride, strontium fluoride, and barium fluoride.
Examples of the alkaline earth metal bromide include magnesium bromide, calcium bromide, strontium bromide, 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. And an acyloxy group which may have, a phenyl group which may have a substituent, an acetylacetonate group which may have a substituent, a sulfonic acid group which may have a substituent, and the like. It is done. As an alkyl group, a C1-C6 alkyl group etc. are mentioned, for example. As an 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 acids 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, and salicylic acid. Magnesium, magnesium benzoate, magnesium oxalate, magnesium trifluoromethanesulfonate, calcium methoxide, calcium ethoxide, calcium acetate, calcium formate, acetylacetone calcium, calcium dipivaloylmethanate, calcium 2-ethylhexanoate, calcium lactate , Calcium naphthenate, calcium citrate, calcium salicylate, calcium neodecanoate, repose Calcium oxide, calcium oxalate, strontium isopropoxide, strontium acetate, strontium formate, acetylacetone strontium, strontium 2-ethylhexanoate, strontium lactate, strontium naphthenate, strontium salicylate, strontium oxalate, barium ethoxide, barium isopropoxide , Barium acetate, barium formate, barium acetylacetone, barium 2-ethylhexanoate, barium lactate, barium naphthenate, barium neodecanoate, barium oxalate, barium benzoate, barium trifluoromethanesulfonate, bis (acetylacetonate) beryllium, etc. Is mentioned.

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

-Element B-containing compound-
As the B element in the B element-containing compound, Ga (gallium), 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) ).

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

Examples of the inorganic B element compound include nitrate of B element, sulfate of B element, fluoride of B element, chloride of B element, bromide of B element, iodide of B element, etc. Is mentioned.
Examples of the element B nitrate include gallium nitrate, 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, and lutetium nitrate.
Examples of the element B sulfate include gallium sulfate, scandium sulfate, yttrium sulfate, lanthanum sulfate, cerium sulfate, praseodymium sulfate, neodymium sulfate, samarium sulfate, europium sulfate, gadolinium sulfate, terbium sulfate, dysprosium sulfate, holmium sulfate, sulfuric acid Examples include erbium, thulium sulfate, ytterbium sulfate, and lutetium sulfate.
Examples of the element B fluoride include gallium fluoride, scandium fluoride, yttrium fluoride, lanthanum fluoride, cerium fluoride, praseodymium fluoride, neodymium fluoride, samarium fluoride, europium fluoride, gadolinium fluoride, Examples thereof include terbium fluoride, dysprosium fluoride, holmium fluoride, erbium fluoride, thulium fluoride, ytterbium fluoride, and lutetium fluoride.
Examples of the element B chloride include gallium chloride, scandium chloride, yttrium chloride, lanthanum chloride, cerium chloride, praseodymium chloride, neodymium chloride, samarium chloride, europium chloride, gadolinium chloride, terbium chloride, dysprosium chloride, holmium chloride, and chloride. Examples include erbium, thulium chloride, ytterbium chloride, and lutetium chloride.
Examples of the element B bromide include gallium bromide, scandium bromide, yttrium bromide, lanthanum bromide, praseodymium bromide, neodymium bromide, samarium bromide, europium bromide, gadolinium bromide, terbium bromide, and odor. And dysprosium bromide, holmium bromide, erbium bromide, thulium bromide, ytterbium bromide, and lutetium bromide.
Examples of the element B iodide include gallium iodide, scandium iodide, yttrium iodide, lanthanum iodide, cerium iodide, praseodymium iodide, neodymium iodide, samarium iodide, europium iodide, gadolinium iodide, Examples thereof include terbium iodide, dysprosium iodide, holmium iodide, erbium iodide, thulium iodide, ytterbium iodide, and lutetium iodide.

  The organic B element compound is not particularly limited as long as it is a compound having the B element and an organic group, and can be appropriately selected according to the purpose. The element B 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. Examples thereof include an optionally substituted acyloxy group, an optionally substituted acetylacetonate group, and an optionally substituted cyclopentadienyl group. As an alkyl group, a C1-C6 alkyl group etc. are mentioned, for example. As an alkoxy group, a C1-C6 alkoxy group etc. are mentioned, for example. As an acyloxy group, a C1-C10 acyloxy group etc. are mentioned, for example.

  Examples of the organic element B compound include tris (cyclopentadienyl) gallium, scandium isopropoxide, scandium acetate, tris (cyclopentadienyl) scandium, yttrium isopropoxide, yttrium 2-ethylhexanoate, tris ( Acetylacetonato) yttrium, tris (cyclopentadienyl) yttrium, lanthanum isopropoxide, lanthanum 2-ethylhexanoate, lanthanum tris (acetylacetonato) lanthanum, tris (cyclopentadienyl) lanthanum, cerium 2-ethylhexanoate , Tris (acetylacetonato) cerium, tris (cyclopentadienyl) cerium, praseodymium isopropoxide, praseodymium oxalate, tris (acetylacetonato) praseodymium, tri (Cyclopentadienyl) praseodymium, neodymium isopropoxide, neodymium 2-ethylhexanoate, trifluoroacetylacetonate neodymium, tris (isopropylcyclopentadienyl) neodymium, tris (ethylcyclopentadienyl) promethium, samarium isopropoxy Samarium 2-ethylhexanoate, tris (acetylacetonato) samarium, tris (cyclopentadienyl) samarium, europium 2-ethylhexanoate, tris (acetylacetonato) europium, tris (ethylcyclopentadienyl) europium , Gadolinium isopropoxide, gadolinium 2-ethylhexanoate, tris (acetylacetonato) gadolinium, tris (cyclopentadienyl) gadolinium, vinegar Terbium, tris (acetylacetonato) terbium, tris (cyclopentadienyl) terbium, dysprosium isopropoxide, dysprosium acetate, tris (acetylacetonato) dysprosium, tris (ethylcyclopentadienyl) dysprosium, holmium isopropoxide, Holmium acetate, tris (cyclopentadienyl) 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 (cyclo Pentadienyl) ytterbium, lutetium oxalate, tris (ethylcyclopentadienyl) lutetium, and the like.

  There is no restriction | limiting in particular as content of the B element containing compound in the coating liquid for insulating layer formation, According to the objective, it can select suitably.

-Element C-containing compound-
Examples of the C element include Al (aluminum), Ti (titanium), Zr (zirconium), Hf (hafnium), Nb (niobium), and Ta (tantalum).

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

  Examples of inorganic compounds of the C element include aluminum nitrate, aluminum sulfate, aluminum fluoride, aluminum chloride, aluminum bromide, aluminum iodide, aluminum hydroxide, aluminum phosphate, aluminum ammonium sulfate, titanium sulfide, and titanium fluoride. , Titanium chloride, titanium bromide, titanium iodide, zirconium sulfate, zirconium carbonate, zirconium fluoride, zirconium chloride, zirconium bromide, zirconium iodide, hafnium sulfate, hafnium fluoride, hafnium chloride, hafnium bromide, hafnium iodide , Niobium fluoride, niobium chloride, niobium bromide, tantalum fluoride, tantalum chloride, tantalum bromide and the like.

  The organic compound of the C element is not particularly limited as long as it is a compound having the C element and an organic group, and can be appropriately selected according to the purpose. The C 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. Examples thereof include an optionally substituted acyloxy group, an optionally substituted acetylacetonate group, and an optionally substituted cyclopentadienyl group. As an alkyl group, a C1-C6 alkyl group etc. are mentioned, for example. As an alkoxy group, a C1-C6 alkoxy group etc. are mentioned, for example. As an acyloxy group, a C1-C10 acyloxy group etc. are mentioned, for example.

  Examples of the organic compound of element C include aluminum isopropoxide, aluminum-sec-butoxide, triethylaluminum, diethylaluminum ethoxide, aluminum acetate, acetylacetone aluminum, hexafluoroacetylacetonate aluminum, 2-ethylhexanoate aluminum, lactic acid Aluminum, aluminum benzoate, aluminum di (s-butoxide) acetoacetate chelate, aluminum trifluoromethanesulfonate, titanium isopropoxide, bis (cyclopentadienyl) titanium chloride, zirconium butoxide, zirconium isopropoxide, bis (2 -Ethylhexanoic acid) zirconium oxide, zirconium di (n-butoxide) bisacetyl sweat toner tote, tetrakis (acetyl) Acetone acid) zirconium, tetrakis (cyclopentadienyl) zirconium, hafnium butoxide, hafnium isopropoxide, tetrakis (2-ethylhexanoate) hafnium, hafnium di (n-butoxide) bisacetylacetonate, tetrakis (acetylacetonate) hafnium, Examples thereof include bis (cyclopentadienyl) dimethylhafnium, niobium ethoxide, niobium 2-ethylhexanoate, bis (cyclopentadienyl) niobium chloride, tantalum ethoxide, tetraethoxyacetylacetonate tantalum, and the like.

  There is no restriction | limiting in particular as content of the C element containing compound in the coating liquid for insulating 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 various compounds, and can be appropriately selected according to the purpose. For example, toluene, xylene, mesitylene, cymene, pentylbenzene, dodecylbenzene, Bicyclohexyl, cyclohexylbenzene, decane, undecane, dodecane, tridecane, tetradecane, pentadecane, tetralin, decalin, isopropanol, ethyl benzoate, N, N-dimethylformamide, propylene carbonate, 2-ethylhexanoic acid, mineral spirits, dimethylpropylene urea 4-butyrolactone, 2-methoxyethanol, propylene glycol, water and the like.

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

The composition ratio of the A-element-containing compound to the B-element-containing compound (the A-element-containing compound: the B-element-containing compound) in the insulating layer forming coating liquid is not particularly limited and is appropriately selected depending on the purpose. However, the following range is preferable.
In the insulating layer forming coating solution, the composition ratio of the A element to the B element (A element: B element) is an oxide (BeO, MgO, CaO, SrO, BaO, Ga ₂ O ₃ , _{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, in _{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.

As the composition ratio of the A-element-containing compound, the B-element-containing compound, and the C-element-containing compound in the coating solution for forming the insulating layer (A-element-containing compound: B-element-containing compound: C-element-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 insulating layer forming coating solution, the composition ratio of the A element, the B element, and the C element (A element: B element: C element) is an oxide (BeO, MgO, CaO, _{SrO, BaO, Ga 2 O 3} , 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 , Al ₂ O ₃ , TiO ₂ , ZrO ₂ , HfO ₂ , Nb ₂ O ₅ , Ta ₂ O ₅ ), 5.0 mol% to 22.0 mol%: 33.0 mol% to 90.0 mol: 5.0 mol% to 45.0 mol% preferable.

-Method for forming a gate insulating layer using a coating solution for forming an insulating layer-
An example of a method for forming a gate insulating layer using an insulating layer forming coating solution will be described. The method for forming the gate insulating layer includes a coating process and a heat treatment process, and further includes other processes as necessary.

  There is no restriction | limiting in particular as long as it is a process of apply | coating the coating liquid for insulating layer formation to a to-be-coated article as an application | coating process, According to the objective, it can select suitably. The application method is not particularly limited and can be appropriately selected according to the purpose.For example, after film formation by a solution process, a patterning method by photolithography, a printing method such as inkjet, nanoimprint, gravure, Examples include 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 coating liquid for forming an insulating layer applied to the object to be coated, and can be appropriately selected according to the purpose. Note that when the heat treatment is performed, the insulating layer forming coating solution applied to the object to be coated may be dried by natural drying or the like. By the heat treatment, drying of the solvent, generation of a composite metal oxide, and the like are performed.

  In the heat treatment step, it is preferable that the solvent is dried (hereinafter referred to as “drying process”) and the composite metal oxide is formed (hereinafter referred to as “generation process”) at different temperatures. That is, after the solvent is dried, the composite metal oxide is preferably generated by raising the temperature. In the production of the composite metal oxide, for example, decomposition of at least one of an alkaline earth metal-containing compound (A-element-containing compound), a B-element-containing compound, and a C-element-containing compound occurs.

  There is no restriction | limiting in particular as temperature of a drying process, According to the solvent to contain, it can select suitably, For example, 80 to 180 degreeC is mentioned. In 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 a drying process, According to the objective, it can select suitably, For example, 1 minute-1 hour are mentioned.

  There is no restriction | limiting in particular as temperature of a production | generation process, Although it can select suitably according to the objective, 100 degreeC or more and less than 550 degreeC are preferable, and 200 to 500 degreeC is more preferable. There is no restriction | limiting in particular as time of a 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 process and the generation process may be performed continuously, or may be divided into a plurality of processes.

  There is no restriction | limiting in particular as the method of heat processing, According to the objective, it can select suitably, For example, the method etc. which heat a to-be-coated article are mentioned. There is no restriction | limiting in particular as atmosphere in heat processing, Although it can select suitably according to the objective, Oxygen atmosphere is preferable. By performing the heat treatment in an oxygen atmosphere, the decomposition product can be quickly discharged out of the system, and the generation of the composite metal oxide can be promoted.

  In the heat treatment, it is effective to irradiate the material after the drying treatment with ultraviolet light having a wavelength of 400 nm or less in order to accelerate the reaction of the generation treatment. By irradiating with ultraviolet light having a wavelength of 400 nm or less, chemical bonds such as organic substances contained in the substance after the drying treatment can be broken and the organic substances can be decomposed, so that a composite metal oxide can be efficiently 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. It is also preferable to apply ozone instead of or in combination with ultraviolet light irradiation. By applying ozone to the substance after the drying treatment, the generation of the composite metal oxide is promoted.

<Active layer>
There is no restriction | limiting in particular as a material of the active layer 14, Although it can select suitably according to the objective, For example, a polycrystalline silicon (p-Si), an amorphous silicon (a-Si), an oxide semiconductor, a pentacene etc. Organic semiconductors and the like. Among these, it is preferable to use an oxide semiconductor from the viewpoint of the stability of the interface with the gate insulating layer 13.

The active layer 14 can be formed from, for example, an n-type oxide semiconductor.
The n-type oxide semiconductor constituting the active layer 14 is not particularly limited and may be appropriately selected depending on the intended purpose. However, at least one of indium (In), Zn, tin (Sn), and Ti, an alkali It preferably contains an earth element or a rare earth element, and more preferably contains In and an alkaline earth element or a rare earth element.

  Examples of rare earth elements include scandium (Sc), yttrium (Y), lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu), Examples include gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), and lutetium (Lu).

Indium oxide has an electron carrier concentration of about 10 ¹⁸ cm ⁻³ to 10 ²⁰ cm ⁻³ depending on the oxygen deficiency. However, indium oxide has a property of easily causing oxygen vacancies, and there are cases where unintended oxygen vacancies may be formed in a later step after the formation of the oxide semiconductor film. The formation of oxides mainly from two metals of indium and alkaline earth elements and rare earth elements that are more likely to bond with oxygen than indium prevents unintentional oxygen vacancies and facilitates control of the composition. This is particularly preferable in terms of easy control of the concentration.

  The n-type oxide semiconductor constituting the active layer 14 is a divalent cation, a trivalent cation, a tetravalent cation, a pentavalent cation, a hexavalent cation, a heptavalent cation, and an octavalent cation. It is preferable that substitution doping is performed with at least one of the dopants, and the valence of the dopant is greater than the valence of the metal ions (excluding the dopant) constituting the n-type oxide semiconductor. Substitution doping is also referred to as n-type doping.

<Source electrode and drain electrode>
The source electrode 15 and the drain electrode 16 are formed on the gate insulating layer 13.
The source electrode 15 and the drain electrode 16 are formed at a predetermined interval.
The source electrode 15 and the drain electrode 16 are electrodes for taking out current in response to application of a gate voltage to the gate electrode 12.
Note that the wiring connected to the source electrode 15 and the drain electrode 16 may be formed in the same layer together with the source electrode 15 and the drain electrode 16.

  Examples of the material for the source electrode 15 and the drain electrode 16 include a metal, an alloy, a mixture of a plurality of metals, a conductive oxide, a composite compound, and a laminated film of a metal and a conductive oxide that can be etched with a hydrofluoric acid-based etchant. If there is no particular limitation, it can be appropriately selected according to the purpose. For example, metals such as aluminum (Al) and titanium (Ti), alloys thereof, a mixture of these metals, and the like can be used. . In addition, conductive oxides such as indium oxide, zinc oxide, and titanium oxide, composite compounds thereof, mixtures thereof, and the like may be used.

  Conductive oxides, composite compounds, and mixtures of these can be used without distinction between polycrystalline and amorphous. However, since amorphous has less variation in etching rate on the same substrate and can be patterned accurately, hydrofluoric acid. In the patterning process using a system etching solution, it is preferably amorphous. It is known that these materials are subjected to heat treatment in order to increase the conductivity as an electrode. However, it is preferable that the heat treatment is performed after patterning from the viewpoint of patterning accuracy described above.

As conductive oxides containing indium oxide, tin-doped indium oxide (hereinafter referred to as ITO) and In ₂ O ₃ —ZnO composite oxide (IZO) are widely known, but IZO is amorphous. Therefore, it is more preferable when patterning with a hydrofluoric acid-based etching solution.

  When a conductive oxide, a composite compound, or a mixture thereof is used as an electrode, the electrical resistance may increase due to heat treatment in a later step. Therefore, when a conductive oxide, a composite compound, or a mixture thereof is used as the electrode, it is preferable to stack a highly conductive metal in consideration of wiring resistance. Examples of the highly conductive metal include Ag, Al, Au, and Cu.

The conductive film may have a laminated structure. In that case, for example, the lowermost layer of the conductive film covering the composite metal oxide functions as a barrier layer when patterning the upper layer of the conductive film. The upper layer is, for example, one layer of the laminated structure and is a layer immediately above the lowermost layer.
The barrier layer can be etched with, for example, a hydrofluoric acid-based etchant.
The laminated structure may be a two-layer structure or a three-layer structure.
The source electrode 15 and the drain electrode 16 may be any material as long as the material in contact with the gate insulating layer 13 is the above-described material, and a material having higher conductivity or a material that increases resistance as a wiring may be stacked thereover. In the case of using a stacked conductive film, the conductive film on the gate insulating layer may be finally etched with a hydrofluoric acid-based etchant in the etching process, which is different from the upper conductive film. Etching solution may be used. For example, when using an etchant that etches the composite metal oxide to be the gate insulating layer, such as a PAN-based etchant for the metal laminated on the composite metal oxide to be the gate insulating layer, a hydrofluoric acid is used. A material that can be etched with a system etchant functions as a barrier layer.

  Further, since the composite metal oxide serving as the gate insulating layer and the oxide semiconductor used for the active layer are materials having sufficiently high light transmittance in the visible light region, the gate electrode, the source electrode, and the drain The use of a conductive oxide, a composite compound, or a mixture thereof having a sufficiently high light transmittance in the visible light region for the electrode has an advantage that a field effect transistor having a high visible light transmittance can be manufactured. As described above, when there is a concern about an increase in the wiring resistance of the gate electrode, the source electrode, and the drain electrode, the wiring portion other than the channel region may have a laminated structure with a metal.

  There is no restriction | limiting in particular as an average film thickness of the source electrode 15 and the drain electrode 16, Although it can select suitably according to the objective, 10 nm-1 micrometer are preferable and 50 nm-300 nm are more preferable.

  The hydrofluoric acid etching solution can be appropriately selected according to the purpose, and examples thereof include an aqueous solution containing hydrofluoric acid, ammonium fluoride, ammonium hydrogen fluoride, and the like. Further, an additive such as a surfactant or an oxidizing agent may be contained in the etching solution in order to form a favorable pattern.

  Next, a method for manufacturing the field effect transistor shown in FIG. 1 will be described. 2A to 2E are diagrams illustrating a manufacturing process of the field effect transistor according to the embodiment.

  First, in the step shown in FIG. 2A, a substrate 11 made of a glass substrate or the like is prepared. Then, a conductive film made of aluminum (Al) or the like is formed on the substrate 11 by sputtering or the like, and the formed conductive film is patterned by photolithography and etching to form a gate electrode 12 having a predetermined shape. From the viewpoint of cleaning the surface of the substrate 11 and improving the adhesion, it is preferable to perform pretreatment such as oxygen plasma, UV ozone, UV irradiation cleaning and the like before forming the gate electrode 12. The material and thickness of the base material 11 and the gate electrode 12 can be appropriately selected as described above.

  The method for forming the gate electrode 12 is not particularly limited and may be appropriately selected depending on the purpose. For example, after film formation by sputtering, vacuum deposition, dip coating, spin coating, die coating, or the like, There is a method of patterning by photolithography. Another example is a method of directly forming a desired shape by a printing process such as ink jet, nanoimprint, or gravure.

  Next, in the step shown in FIG. 2B, a gate insulating layer 13 that covers the gate electrode 12 is formed on the base material 11. There is no restriction | limiting in particular as a formation method of the gate insulating layer 13, 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 atom The film forming process may be performed by a vacuum process such as layer deposition (ALD) or a solution process such as dip coating, spin coating, or die coating. Other examples include printing processes such as inkjet, nanoimprint, and gravure. The material and thickness of the gate insulating layer 13 can be appropriately selected as described above.

  Next, in the step shown in FIG. 2C, a conductive film 150 to be the source electrode 15 and the drain electrode 16 is formed on the entire surface of the gate insulating layer 13. From the viewpoint of cleaning the surface of the gate insulating layer 13 and improving adhesion, pretreatment such as oxygen plasma, UV ozone, and UV irradiation cleaning is preferably performed before the conductive film 150 is formed.

  The method for forming the conductive film 150 is not particularly limited and may be appropriately selected depending on the purpose. For example, after film formation by sputtering, vacuum deposition, dip coating, spin coating, die coating, or the like, There is a method of patterning by photolithography. Other examples include printing processes such as inkjet, nanoimprint, and gravure. The material and thickness of the conductive film 150 serving as a precursor of the source electrode 15 and the drain electrode 16 can be appropriately selected as described above regarding the source electrode 15 and the drain electrode 16.

Next, in the step shown in FIG. 2D, the conductive film 150 formed on the entire surface of the gate insulating layer 13 is patterned by photolithography and wet etching to have a predetermined shape, and the source electrode 15 and the drain electrode 16 are formed.
When the conductive film 150 is etched, a hydrofluoric acid-based etchant can be used. The hydrofluoric acid etching solution preferably contains at least one of hydrogen fluoride, ammonium fluoride, and ammonium hydrogen fluoride. These concentrations in the hydrofluoric acid-based etching solution can be appropriately adjusted according to the purpose, but from the viewpoint of controlling the etching rate, the concentration of hydrogen fluoride is preferably 0.01% by mass to 20% by mass, 0.1 mass%-10 mass% are more preferable. The concentration of ammonium fluoride is preferably 0.1% by mass to 60% by mass, and more preferably 1% by mass to 30% by mass. The concentration of ammonium hydrogen fluoride is preferably 0.1% by mass to 60% by mass, and more preferably 1% by mass to 30% by mass. Thus, the conductive film 150 can be patterned without damaging the underlying gate insulating layer. In addition, the hydrofluoric acid-based etching solution may be mixed with hydrogen fluoride, ammonium fluoride, and ammonium hydrogen fluoride as appropriate to stabilize the etching rate, and may be used as a buffer solution. An additive such as a surfactant and an oxidizing agent may be included.

  Next, in a step shown in FIG. 2E, an active layer 14 having a predetermined shape is formed on the gate insulating layer 13. There is no restriction | limiting in particular as a formation method of the active layer 14, 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 The film forming process may be performed by a vacuum process such as vapor deposition (ALD) or a solution process such as dip coating, spin coating, or die coating. Other examples include printing processes such as inkjet, nanoimprint, and gravure. The active layer 14 can be formed from, for example, an n-type oxide semiconductor. The formed active layer 14 may be a mixture of crystalline and amorphous.

  Through the above steps, a bottom-gate / bottom-contact field effect transistor 10 can be manufactured.

  Thus, in this embodiment mode, wet etching is performed using a hydrofluoric acid-based etchant when patterning a conductive film over a gate insulating layer formed using a composite metal oxide. Since the hydrofluoric acid-based etchant can selectively etch the conductive film with respect to the composite metal oxide, it is possible to suppress etching damage to the gate insulating layer, and the gate insulating layer does not decrease in thickness and has good insulating properties. Can be maintained. As a result, a field effect transistor with good electrical characteristics can be realized.

<Modification of Embodiment>
In the modification of the embodiment, an example of a bottom-gate / top-contact field effect transistor is shown. Note that in the modification of the embodiment, the description of the same components as those of the embodiment described above may be omitted.

FIG. 3A is a cross-sectional view illustrating a field effect transistor according to a modification of the embodiment.
Referring to FIG. 3A, the field effect transistor 10A is a bottom gate / top contact field effect transistor. The field effect transistor 10A is a typical example of a semiconductor device according to the present invention.
The field effect transistor 10A has a layer structure different from that of the field effect transistor 10 (see FIG. 1). Specifically, the field effect transistor 10A includes a base material 11, a gate electrode 12 formed on the base material 11, a gate insulating layer 13 formed on the gate electrode 12, and a gate insulating layer 13. The source electrode 15 and the drain electrode 16 are formed, and the active layer 14 is formed under the source electrode 15 and the drain electrode 16 and between the source electrode 15 and the drain electrode 16. In this case, the material of the active layer 14 is a material that can obtain a sufficient selectivity with respect to the hydrofluoric acid etching solution used in the process of forming the source electrode 15 and the drain electrode 16.

FIG. 4 is a cross-sectional view illustrating a field effect transistor according to a modification of the embodiment.
Referring to FIG. 4, the field effect transistor 10B is a top gate / bottom contact field effect transistor. The field effect transistor 10B is a typical example of a semiconductor device according to the present invention.
The field effect transistor 10B has a layer structure different from that of the field effect transistor 10 (see FIG. 1). Specifically, the field effect transistor 10 </ b> B includes a base material 11, a source electrode 15 and a drain electrode 16 formed on the base material 11, a source electrode 15 and a drain electrode 16, and a source electrode 15 and a drain electrode 16. And the gate insulating layer 13 and the gate electrode 12 formed on the gate insulating layer 13. In this case, the material of the gate electrode 12 is the material of the source electrode 15 and the drain electrode 16 in the embodiment, and a hydrofluoric acid etching solution is used in the formation process of the gate electrode 12. On the other hand, the material of the gate electrode 12 in the embodiment can be used as the material of the source electrode 15 and the drain electrode 16.

FIG. 5A is a cross-sectional view illustrating a field effect transistor according to a modification of the embodiment.
Referring to FIG. 5A, the field effect transistor 10C is a top gate / top contact field effect transistor. The field effect transistor 10C is a typical example of the semiconductor device according to the present invention.
The field effect transistor 10C has a layer structure different from that of the field effect transistor 10 (see FIG. 1). Specifically, the field effect transistor 10 </ b> C includes a base material 11, a source electrode 15 and a drain electrode 16 formed on the base material 11, a source electrode 15 and a drain electrode 16, and a source electrode 15 and a drain electrode 16. And the gate insulating layer 13 and the gate electrode 12 formed on the gate insulating layer 13. In this case, the material of the gate electrode 12 uses the material of the source electrode 15 and the drain electrode 16 in the above-described embodiment, and a hydrofluoric acid etching solution is used in the step of forming the gate electrode 12. On the contrary, the material of the gate electrode 12 in the above-described embodiment can be used as the material of the source electrode 15 and the drain electrode 16.

In the case of the bottom gate / top contact field effect transistor of FIG. 3A, the structure can be manufactured when the selection ratio of the source electrode, the drain electrode, and the active layer to the hydrofluoric acid-based etching solution is sufficiently obtained. FIG. 3B shows a bottom-gate / top-contact field effect transistor in a case where the selection ratio of the source electrode, the drain electrode and the active layer to the hydrofluoric acid-based etchant is not sufficiently obtained.
The difference between the method of manufacturing the field effect transistor of FIG. 3B and the method of manufacturing the field effect transistor of FIGS. 3A and 5A is that the second gate insulating layer 13B is formed after the active layer 14 is formed. The source electrode 15 and the drain electrode 16 are formed after a through hole is formed in the electrode 14. The gate insulating layer 13 and the second gate insulating layer 13B may be made of the same material or different materials, but the gate insulating layer serving as a base of the layer in which the etching solution used for patterning is a hydrofluoric acid-based etching solution is the composite material. A metal oxide is preferable from the viewpoint of the etching selectivity. Note that the patterning method of the source electrode 15 and the drain electrode 16 is the same for the top gate / top contact field effect transistor in this case as shown in FIG. 5B. In FIG. 5B, reference numeral 21 denotes a conductive part for allowing the source electrode 15 to conduct to the outside, and reference numeral 22 denotes a conductive part for allowing the drain electrode 22 to conduct to the outside.

  The layer structure of the field effect transistor according to the present invention is not particularly limited, and the structures shown in FIGS. 1, 3A, 3B, 4, 5A, and 5B can be appropriately selected depending on the purpose. .

  In another embodiment, an example of a display element, an image display device, and a system using the field effect transistor according to the embodiment will be described. In this embodiment, the description of the same components as those of the embodiment already described may be omitted.

(Display element)
A display element according to another embodiment includes at least a light control element and a drive circuit that drives the light control element, and further includes other members as necessary.

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

  The driving circuit is not particularly limited as long as it has the field-effect transistor according to the embodiment, and can be appropriately selected depending on the purpose. There is no restriction | limiting in particular as another member, According to the objective, it can select suitably.

  Since the display element according to another embodiment includes the field-effect transistor according to the embodiment, the gate insulating layer 13 maintains good insulation, and good electrical characteristics can be obtained. it can. As a result, high quality display can be performed.

(Image display device)
An image display device according to another embodiment includes at least a plurality of display elements according to another embodiment, a plurality of wirings, and a display control device, and further includes other members as necessary. Have.

  The plurality of display elements are not particularly limited as long as they are display elements according to other embodiments arranged in a matrix, and can be appropriately selected according to the purpose.

  The plurality of wirings are not particularly limited and can be appropriately selected depending on the purpose as long as the gate voltage and the image data signal can be individually applied to each field effect transistor in the plurality of display elements.

  The display control device is not particularly limited as long as the gate voltage and signal voltage of each field effect transistor can be individually controlled via a plurality of wirings according to image data, and is appropriately selected according to the purpose. can do.

  There is no restriction | limiting in particular as another member, According to the objective, it can select suitably.

  Since the image display device according to another embodiment includes a display element including the field effect transistor according to the embodiment, a high-quality image can be displayed.

(system)
A system according to another embodiment includes at least an image display device according to another embodiment and an image data creation device.

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

  Since the system includes an image display device according to another embodiment, it is possible to display image information with high definition.

  Hereinafter, display elements, image display apparatuses, and systems according to other embodiments will be described in detail.

  FIG. 6 shows a schematic configuration of a television device 500 as a system according to another embodiment. Note that the connection lines in FIG. 6 represent typical signals and information flows, and do not represent the entire connection relationship of each block.

  A television device 500 according to another embodiment includes a main control device 501, a tuner 503, an AD converter (ADC) 504, a demodulation circuit 505, a TS (Transport Stream) decoder 506, an audio decoder 511, and a DA converter (DAC) 512. , Audio output circuit 513, speaker 514, video decoder 521, video / OSD synthesis circuit 522, video output circuit 523, image display device 524, OSD drawing circuit 525, memory 531, operation device 532, drive interface (drive IF) 541, A hard disk device 542, an optical disk device 543, an IR light receiver 551, a communication control device 552, and the like are provided.

  The main control device 501 controls the entire television device 500 and includes a CPU, a flash ROM, a RAM, and the like. The flash ROM stores a program written in a code readable by the CPU, various data used for processing by the CPU, and the like. The RAM is a working memory.

  The tuner 503 selects a preset channel broadcast from the broadcast waves received by the antenna 610. The ADC 504 converts the output signal (analog information) of the tuner 503 into digital information. The demodulation circuit 505 demodulates the digital information from the ADC 504.

  The TS decoder 506 performs TS decoding on the output signal of the demodulation circuit 505 and separates audio information and video information. The audio decoder 511 decodes the audio information from the TS decoder 506. The DA converter (DAC) 512 converts the output signal of the audio decoder 511 into an analog signal.

  The audio output circuit 513 outputs the output signal of the DA converter (DAC) 512 to the speaker 514. The video decoder 521 decodes the video information from the TS decoder 506. The video / OSD synthesis circuit 522 synthesizes the output signal of the video decoder 521 and the output signal of the OSD drawing circuit 525.

  The video output circuit 523 outputs the output signal of the video / OSD synthesis circuit 522 to the image display device 524. The OSD drawing circuit 525 includes a character generator for displaying characters and figures on the screen of the image display device 524, and a signal including display information in response to an instruction from the operation device 532 or the IR light receiver 551. Generate.

  The memory 531 temporarily stores AV (Audio-Visual) data and the like. The operating device 532 includes an input medium (not shown) such as a control panel, for example, and notifies the main controller 501 of various information input by the user. The drive IF 541 is a bi-directional communication interface, and is compliant with ATAPI (AT Attachment Packet Interface) as an example.

  The hard disk device 542 includes a hard disk and a drive device for driving the hard disk. The drive device records data on the hard disk and reproduces data recorded on the hard disk. The optical disk device 543 records data on an optical disk (for example, DVD) and reproduces data recorded on the optical disk.

  The IR light receiver 551 receives the optical signal from the remote control transmitter 620 and notifies the main controller 501 of it. The communication control device 552 controls communication with the Internet. Various information can be acquired via the Internet.

  The image display device 524 includes a display 700 and a display control device 780 as shown in FIG. 7 as an example. As shown in FIG. 8 as an example, the display 700 includes a display 710 in which a plurality of (here, n × m) display elements 702 are arranged in a matrix.

  In addition, as shown in FIG. 9 as an example, the display 710 includes n scanning lines (X0, X1, X2, X3,..., Xn) arranged at equal intervals along the X-axis direction. -2, Xn-1), m data lines (Y0, Y1, Y2, Y3, ..., Ym-1) arranged at equal intervals along the Y-axis direction, in the Y-axis direction M current supply lines (Y0i, Y1i, Y2i, Y3i,..., Ym-1i) arranged at equal intervals along the line. The display element 702 can be specified by the scan line and the data line.

  As an example, each display element 702 includes an organic EL (electroluminescence) element 750 and a drive circuit 720 for causing the organic EL element 750 to emit light. That is, the display 710 is a so-called active matrix type organic EL display. The display 710 is a color-compatible 32-inch display. The size is not limited to this.

  As an example, the organic EL element 750 includes an organic EL thin film layer 740, a cathode 712, and an anode 714, as shown in FIG.

The organic EL element 750 can be disposed beside a field effect transistor, for example. In this case, the organic EL element 750 and the field effect transistor can be formed on the same substrate. However, it is not limited to this, For example, the organic EL element 750 may be arrange | positioned on a field effect transistor. In this case, since the gate electrode needs to be transparent, the gate electrode was added with ITO (Indium Tin Oxide), In ₂ O ₃ , SnO ₂ , ZnO, Ga added ZnO, Al. A transparent oxide having conductivity such as SnO ₂ to which ZnO or Sb is added is used.

In the organic EL element 750, Al is used for the cathode 712. Note that an Mg—Ag alloy, an Al—Li alloy, ITO, or the like may be used. ITO is used for the anode 714. Note that a conductive oxide such as In ₂ O ₃ , SnO ₂ , or ZnO, an Ag—Nd alloy, or the like may be used.

  The organic EL thin film layer 740 includes an electron transport layer 742, a light emitting layer 744, and a hole transport layer 746. A cathode 712 is connected to the electron transport layer 742, and an anode 714 is connected to the hole transport layer 746. When a predetermined voltage is applied between the anode 714 and the cathode 712, the light emitting layer 744 emits light.

  As shown in FIG. 10, the drive circuit 720 includes two field effect transistors 810 and 820 and a capacitor 830. The field effect transistor 810 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 830.

  The capacitor 830 is for storing the state of the field effect transistor 810, that is, data. The other terminal of the capacitor 830 is connected to a predetermined current supply line.

  The field effect transistor 820 is for supplying a large current to the organic EL element 750. The gate electrode G is connected to the drain electrode D of the field effect transistor 810. The drain electrode D is connected to the anode 714 of the organic EL element 750, and the source electrode S is connected to a predetermined current supply line.

  Therefore, when the field effect transistor 810 is turned on, the organic EL element 750 is driven by the field effect transistor 820.

  As an example, the display control device 780 includes an image data processing circuit 782, a scanning line driving circuit 784, and a data line driving circuit 786, as shown in FIG.

  The image data processing circuit 782 determines the brightness of the plurality of display elements 702 in the display 710 based on the output signal of the video output circuit 523. The scanning line driving circuit 784 individually applies voltages to the n scanning lines in accordance with an instruction from the image data processing circuit 782. The data line driving circuit 786 individually applies voltages to the m data lines in accordance with an instruction from the image data processing circuit 782.

  As is clear from the above description, in the television apparatus 500 according to the present embodiment, the video decoder 521, the video / OSD synthesis circuit 522, the video output circuit 523, and the OSD drawing circuit 525 constitute an image data creation apparatus. ing.

  In the above description, the light control element is an organic EL element. However, the present invention is not limited to this, and a liquid crystal element, an electrochromic element, an electrophoretic element, or an electrowetting element may be used.

  For example, when the light control element is a liquid crystal element, a liquid crystal display is used as the display 710. In this case, as shown in FIG. 13, the current supply line in the display element 703 is not necessary.

  Further, in this case, as shown in FIG. 14 as an example, the drive circuit 730 is configured by only one field effect transistor 840 similar to the field effect transistor (810, 820) shown in FIG. Can do. In the field effect transistor 840, 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 the pixel electrode of the liquid crystal element 770 and the capacitor 760. Note that reference numerals 762 and 772 in FIG. 14 denote a counter electrode (common electrode) of the capacitor 760 and the liquid crystal element 770, respectively.

  In the above embodiment, the case where the system is a television apparatus has been described. However, the present invention is not limited to this. In short, the image display device 524 may be provided as a device for displaying images and information. For example, a computer system in which a computer (including a personal computer) and an image display device 524 are connected may be used.

  In addition, an image display device 524 is provided as a display means in a portable information device such as a mobile phone, a portable music player, a portable video player, an electronic BOOK, a PDA (Personal Digital Assistant), or an imaging device such as a still camera or a video camera. Can be used. Further, the image display device 524 can be used as a display unit for various information in a mobile system such as a car, an aircraft, a train, and a ship. Furthermore, the image display device 524 can be used as a display unit for various information in a measurement device, an analysis device, a medical device, and an advertising medium.

  The preferred embodiments and the like have been described in detail above, but the present invention is not limited to the above-described embodiments and the like, and various modifications can be made to the above-described embodiments and the like without departing from the scope described in the claims. Variations and substitutions can be added.

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

Example 1
In Example 1, the bottom gate / bottom contact type field effect transistor shown in FIG. 1 was fabricated.

<Formation of gate electrode>
An Al film was formed on the substrate 11 by sputtering so as to have a thickness of 100 nm. A resist pattern was formed on the formed Al film by photolithography, and etching was performed to form a gate electrode 12 having a predetermined shape.

<Formation of gate insulating layer>
−Preparation of coating liquid for gate insulating layer formation−
The raw materials shown in Table 2 were mixed with 1.2 mL of cyclohexylbenzene so as to have the composition (mol%) of the oxide shown in Table 1-1 to obtain a coating solution for forming a gate insulating layer.

0.6 mL of the gate insulating layer forming coating solution was dropped onto the gate electrode 12 and spin-coated under predetermined conditions (after rotating at 500 rpm for 5 seconds, rotating at 3,000 rpm for 20 seconds, and then rotating at 0 rpm for 5 seconds. The rotation was stopped so that
Subsequently, after drying at 120 ° C. for 1 hour in the air, firing was performed at 400 ° C. for 3 hours in an O ₂ atmosphere, and then annealing was performed at 500 ° C. for 1 hour in the air atmosphere to obtain a gate insulating layer No. 13, a paraelectric amorphous oxide film having the composition described in Example 1 of Table 3 was formed. The average film thickness of the gate insulating layer 13 was about 110 nm.

<Formation of source electrode and drain electrode>
A source electrode 15 and a drain electrode 16 having a thickness of 100 nm were formed on the gate insulating layer 13 and the active layer 14 by sputtering and photolithography. Specifically, it was formed by the following method.
Al was used for the sputtering target. Next, a resist pattern is formed on the formed Al film by photolithography, and etching is performed using a hydrofluoric acid-based etchant (Pure Etch TE300, Hayashi Junyaku Kogyo Co., Ltd.) to form the source electrode 15 on the gate insulating layer 13. And the drain electrode 16 was formed.

<Formation of active layer>
On the gate insulating layer 13, MgIn ₂ O ₄ doped with W was formed to a thickness of 50 nm by RF magnetron sputtering. A polycrystalline sintered body having a composition of MgIn _1.99 W _0.01 O ₄ was used as a target. Argon gas and oxygen gas were introduced as the sputtering gas. The total pressure was fixed at 1.1 Pa and the oxygen concentration was 20% by volume. Patterning was performed by forming a film through a metal mask.
In the active layer thus obtained, W is substitutionally doped at a concentration of 0.5 mol% with respect to In in MgIn ₂ O ₄ . In addition, temperature control of the base material 11 was not performed. It has been found that the temperature of the substrate 11 naturally rises during sputtering, but is kept below 40 ° C. That is, the deposition temperature of the InMgWO film is 40 ° C. or lower.
Subsequently, annealing was performed at 350 ° C. for 1 hour in the air using an oven. Such annealing treatment is generally performed for the purpose of improving transistor characteristics by reducing the interface defect level density between the active layer and the gate insulating layer.

  Thus, a bottom gate / bottom contact field effect transistor was completed.

(Examples 2 to 7)
In Examples 2 to 7, except that the composition of the gate insulating layer 13 and the material of the conductive film to be the source electrode 15 and the drain electrode 16 were changed as shown in Table 1-1, Table 1-2, and Table 3. In the same manner as in Example 1, a bottom gate / bottom contact field effect transistor was fabricated.

(Example 8)
In Example 8, the top gate / top contact type field effect transistor shown in FIG. 5B was fabricated.

<Formation of active layer>
On the substrate 11, MgIn ₂ O ₄ doped with W was formed to a thickness of 50 nm by RF magnetron sputtering. A polycrystalline sintered body having a composition of MgIn _1.99 W _0.01 O ₄ was used as a target. Argon gas and oxygen gas were introduced as the sputtering gas. The total pressure was fixed at 1.1 Pa and the oxygen concentration was 20% by volume. Patterning was performed by forming a film through a metal mask.
In the active layer thus obtained, W is substitutionally doped at a concentration of 0.5 mol% with respect to In in MgIn ₂ O ₄ . In addition, temperature control of the base material 11 was not performed. It has been found that the temperature of the substrate 11 naturally rises during sputtering, but is kept below 40 ° C. That is, the deposition temperature of the InMgWO film is 40 ° C. or lower.
Subsequently, annealing was performed at 350 ° C. for 1 hour in the air using an oven. Such annealing treatment is generally performed for the purpose of improving transistor characteristics by reducing the interface defect level density between the active layer and the gate insulating layer.

<Formation of gate insulating layer (1)>
−Preparation of coating liquid for gate insulating layer formation−
The raw materials shown in Table 2 were mixed with 1.2 mL of cyclohexylbenzene so that the composition (mol%) of the oxides shown in Table 1-3 was obtained, thereby obtaining a coating solution for forming a gate insulating layer.

0.6 mL of the gate insulating layer forming coating solution was dropped onto the substrate 11 and the active layer 14 and spin-coated under predetermined conditions (after rotating at 500 rpm for 5 seconds, rotating at 3,000 rpm for 20 seconds, 5 Rotation was stopped so that it became 0 rpm per second).
Subsequently, after drying at 120 ° C. for 1 hour in the air, firing was performed at 400 ° C. for 3 hours in an O ₂ atmosphere, and then annealing was performed at 500 ° C. for 1 hour in the air atmosphere to obtain a gate insulating layer As 13A, a paraelectric amorphous oxide film having the composition described in Example 8 of Table 4 was formed. The average film thickness of the gate insulating layer 13 was about 110 nm.
Next, a resist pattern was formed on the formed gate insulating layer 13 by photolithography, and etching was performed to form a through hole having a predetermined shape on the active layer 14.

<Formation of source electrode and drain electrode>
A source electrode 15 and a drain electrode 16 having a thickness of 100 nm were formed on the active layer 14 on the gate insulating layer 13 and through the through holes of the gate insulating layer 13 by a sputtering method and a photolithography method. Specifically, it was formed by the following method.
Ti was used for the sputtering target. Next, a resist pattern is formed on the formed Ti film by photolithography, and etching is performed using a hydrofluoric acid-based etching solution (Pure Etch TE300, Hayashi Junyaku Kogyo Co., Ltd.) to form the source electrode 15 on the gate insulating layer 13. And the drain electrode 16 was formed.

<Formation of gate insulating layer (2)>
−Preparation of coating liquid for gate insulating layer formation−
The same gate insulating layer forming coating solution as that used for forming the gate insulating layer (1) was used.

0.6 mL of the gate insulating layer forming coating solution was dropped onto the substrate 11 and the active layer 14 and spin-coated under predetermined conditions (after rotating at 500 rpm for 5 seconds, rotating at 3,000 rpm for 20 seconds, 5 Rotation was stopped so that it became 0 rpm per second).
Subsequently, after drying at 120 ° C. for 1 hour in the air, firing was performed at 400 ° C. for 3 hours in an O ₂ atmosphere, and then annealing was performed at 500 ° C. for 1 hour in the air atmosphere to obtain a gate insulating layer As 13B, a paraelectric amorphous oxide film having the composition described in Example 8 of Table 4 was formed. The average film thickness of the gate insulating layer 13B was about 110 nm.
Next, a resist pattern was formed on the formed gate insulating layer 13B by photolithography, and etching was performed to form through holes having a predetermined shape on the source electrode 15 and the drain electrode 16.

<Formation of gate electrode>
A gate electrode 12 having a thickness of 100 nm was formed on the gate insulating layer 13B by sputtering and photolithography. Specifically, it was formed by the following method.
Ti was used for the sputtering target. Next, a resist pattern is formed on the formed Ti film by photolithography, and a hydrofluoric acid-based etching solution (Pure Etch TE30) is formed.
0, Hayashi Junyaku Kogyo Co., Ltd.) was used to form the gate electrode 12 on the gate insulating layer 13B.
Thus, a top gate / top contact type field effect transistor was completed.

(Examples 9 to 11)
In Examples 9 to 11, the composition of the gate insulating layers 13 and 13B and the material of the conductive film to be the source electrode 15 and the drain electrode 16 and the gate electrode 12 are changed as shown in Table 1-3 and Table 4. A top gate / top contact field effect transistor was fabricated in the same manner as in Example 8 except that.

  Details of each compound shown in Table 1-1 to Table 1-3 are as follows.

(Inspecting the pattern with a microscope)
Regarding Examples 1 to 11, as an inspection of the source electrode 15 and the drain electrode 16 formed on the gate insulating layer 13, whether or not the thickness of the gate insulating layer 13 is decreased before and after pattern processing of the source electrode 15 and the drain electrode 16, And the insulation was confirmed. The results are shown in Table 3.

  In Table 3 below, the presence or absence of a decrease in the film thickness of the gate insulating layer 13 before and after the etching of the conductive film to be the source electrode 15 and the drain electrode 16 and the insulating property XX (when the good insulating property can be maintained. The case where the good insulating property could not be maintained x), the shape of the pattern of the source electrode 15 and the drain electrode 16 formed on the gate insulating layer 13 was good, and the case where the good pattern could be formed was good. A case where a simple pattern could not be formed is indicated by x).

In Table 3, “hydrofluoric acid type” represents a hydrofluoric acid type etching solution (Pure Etch TE300, Hayashi Pure Chemical Industries, Ltd.). “PAN-based” represents a mixed solution of PAN-based etching solution phosphoric acid, acetic acid, and nitric acid (Pure Etch AS101, Hayashi Junyaku Kogyo Co., Ltd.).
In Example 5, the conductive film had a three-layer structure of Ti (30 nm) / Cu (100 nm) / Ti (30 nm). A hydrofluoric acid based etchant was used for etching Ti, and a hydrogen peroxide based etchant (Pure Etch C200, Hayashi Junyaku Kogyo Co., Ltd.) was used for etching Cu.

  From Table 3, it can be seen that in all of Examples 1 to 11, the gate insulating layer 13 did not decrease in thickness when the source electrode 15 and the drain electrode 16 were formed, and good insulation was maintained.

(Comparative Example 1)
In Comparative Example 1, the conductive film to be the source electrode 15 and the drain electrode 16 on the gate insulating layer 13 is an Al film, and a phosphoric acid, acetic acid, and nitric acid mixed solution (PAN-based, Pure Etch AS101, Jun Hayashi) is used as an etching solution. A bottom gate / bottom contact field effect transistor was fabricated in the same manner as in Example 1 except that Yakugyo Co., Ltd. was used.

(Inspecting the pattern with a microscope)
In Comparative Example 1, as the inspection of the source electrode 15 and the drain electrode 16 formed on the gate insulating layer 13, whether or not the thickness of the gate insulating layer 13 decreased before and after the pattern processing of the source electrode 15 and the drain electrode 16, and the insulation The sex was confirmed. The results are shown in Table 3.

  As a result of forming a pattern using a mixed solution of phosphoric acid, acetic acid, and nitric acid as an etching solution, it was confirmed that the composite metal oxide film constituting the gate insulating layer 13 was reduced. Further, the insulating property could not be maintained. That is, in the etching process according to Comparative Example 1, it was confirmed that the oxide film forming the gate insulating layer 13 was damaged by the etching solution.

Aspects of the present invention are as follows, for example.
<1> A base material, a source electrode, a drain electrode, and a gate electrode formed on the base material, and a predetermined voltage applied between the gate electrode and the source electrode and the drain electrode. A method of manufacturing a field effect transistor having an active layer in which a channel is formed and a gate insulating layer provided between the gate electrode and the active layer,
Forming a composite metal oxide film containing an element A that is an alkaline earth metal and a B element that is at least one of Ga, Sc, Y, and a lanthanoid, and forming the gate insulating layer; ,
Forming a conductive film on the gate insulating layer, forming the conductive film into a predetermined shape by wet etching, and forming the source electrode and the drain electrode, or the gate electrode,
In the method of manufacturing a field effect transistor, a hydrofluoric acid based etchant is used for the wet etching.
<2> The method for producing a field effect transistor according to <1>, wherein the hydrofluoric acid-based etching solution includes at least one of hydrogen fluoride, ammonium fluoride, and ammonium hydrogen fluoride.
<3> The field effect type according to any one of <1> to <2>, wherein the composite metal oxide film contains a paraelectric amorphous oxide or is a paraelectric amorphous oxide itself. This is a method for manufacturing a transistor.
<4> The composite metal oxide film according to any one of <1> to <3>, further including a C element that is at least one of Al, Ti, Zr, Hf, Nb, and Ta. This is a method of manufacturing a field effect transistor.
<5> The field effect according to any one of <1> to <4>, wherein the conductive film includes a metal of any one of Al, Ti, Zr, Ta, and Nb, an alloy of those elements, or a mixture thereof. This is a method for manufacturing a type transistor.
<6> The method for producing a field effect transistor according to any one of <1> to <4>, wherein the conductive film includes a conductive oxide of any one of indium oxide, zinc oxide, and titanium oxide. .
<7> The conductive film has a laminated structure,
The field effect transistor according to any one of <1> to <4>, wherein the lowermost layer of the conductive film covering the composite metal oxide functions as a barrier layer when patterning an upper layer of the conductive film. It is a manufacturing method.
<8> The method for producing a field effect transistor according to <7>, wherein the barrier layer can be etched with a hydrofluoric acid-based etchant.
<9> The method for producing a field effect transistor according to any one of <1> to <8>, wherein the active layer is an oxide semiconductor.
<10> A base material, a source electrode, a drain electrode, and a gate electrode formed on the base material, and a predetermined voltage applied between the gate electrode and the source electrode and the drain electrode. A field effect transistor having an active layer in which a channel is formed, and a gate insulating layer provided between the gate electrode and the active layer,
The gate insulating layer is a complex metal oxide film containing an A element that is an alkaline earth metal and a B element that is at least one of Ga, Sc, Y, and a lanthanoid;
On the gate insulating layer, the gate electrode or an electrode that is the source electrode and the drain electrode is provided,
The field effect transistor according to claim 1, wherein the electrode is a conductive film having a predetermined shape dissolved by a hydrofluoric acid-based etching solution.

  According to the present invention, in the field effect transistor manufacturing method having a gate insulating layer formed of a composite metal oxide, the conventional problems are solved, and when the conductive film on the gate insulating layer is patterned, Etching damage to the gate insulating layer can be suppressed.

DESCRIPTION OF SYMBOLS 10, 10A, 10B, 10C Field effect transistor 11 Base material 12 Gate electrode 13 Gate insulating layer 14 Active layer 15 Source electrode 16 Drain electrode 150 Conductive film

JP 2015-111163 A Japanese Patent No. 5633346

Claims (10)

A channel is formed between the source electrode and the drain electrode by applying a predetermined voltage to the base material, the source electrode, the drain electrode, and the gate electrode formed on the base material, and the gate electrode. A method of manufacturing a field effect transistor, comprising: an active layer to be formed; and a gate insulating layer provided between the gate electrode and the active layer,
Forming a composite metal oxide film containing an element A that is an alkaline earth metal and a B element that is at least one of Ga, Sc, Y, and a lanthanoid, and forming the gate insulating layer; ,
Forming a conductive film on the gate insulating layer, forming the conductive film into a predetermined shape by wet etching, and forming the source electrode and the drain electrode, or the gate electrode,
A method of manufacturing a field effect transistor, characterized in that a hydrofluoric acid-based etchant is used for the wet etching.   The method for manufacturing a field effect transistor according to claim 1, wherein the hydrofluoric acid-based etching solution contains at least one of hydrogen fluoride, ammonium fluoride, and ammonium hydrogen fluoride.   3. The method of manufacturing a field effect transistor according to claim 1, wherein the composite metal oxide film contains a paraelectric amorphous oxide or is a paraelectric amorphous oxide itself.   4. The field effect transistor according to claim 1, wherein the composite metal oxide film further includes a C element that is at least one of Al, Ti, Zr, Hf, Nb, and Ta. 5. Method.   5. The method of manufacturing a field effect transistor according to claim 1, wherein the conductive film contains any one of Al, Ti, Zr, Ta, and Nb, an alloy of these elements, or a mixture thereof.   5. The method of manufacturing a field effect transistor according to claim 1, wherein the conductive film contains a conductive oxide of any one of indium oxide, zinc oxide, and titanium oxide. The conductive film has a laminated structure,
5. The method of manufacturing a field effect transistor according to claim 1, wherein a lowermost layer of the conductive film covering the composite metal oxide functions as a barrier layer when patterning an upper layer of the conductive film.   8. The method of manufacturing a field effect transistor according to claim 7, wherein the barrier layer can be etched with a hydrofluoric acid-based etchant.   The method of manufacturing a field effect transistor according to claim 1, wherein the active layer is an oxide semiconductor. A channel is formed between the source electrode and the drain electrode by applying a predetermined voltage to the base material, the source electrode, the drain electrode, and the gate electrode formed on the base material, and the gate electrode. A field effect transistor comprising: an active layer to be formed; and a gate insulating layer provided between the gate electrode and the active layer,
The gate insulating layer is a complex metal oxide film containing an A element that is an alkaline earth metal and a B element that is at least one of Ga, Sc, Y, and a lanthanoid;
On the gate insulating layer, the gate electrode or an electrode that is the source electrode and the drain electrode is provided,
A field effect transistor, wherein the electrode is a conductive film having a predetermined shape dissolved by a hydrofluoric acid-based etching solution.