WO2011108884A2 - Metal oxide thin film, preparation method thereof, and solution for metal oxide thin film - Google Patents

Abstract

The present invention provides a solution for a metal oxide semiconductor thin film, comprising a metal hydroxide dissolved in an aqueous or nonaqueous solvent and an acid/base titrant for controlling the solubility of the metal hydroxide. In addition, a solution is synthesized for improving the stability of a device through the addition of other metal hydroxides and for additionally improving the semiconductor performance of a device through the addition of other metal hydroxides. The solution is coated on a substrate, and is annealed by using various annealing equipment so as to obtain a high-quality metal oxide thin film at a low temperature. The thin film is optically transparent, and thus can be applied to a thin film for various electronic devices, a solar cell, various sensors, a memory device, and the like.

Description

Metal oxide thin film and method for manufacturing same, solution for metal oxide thin film

The present invention relates to a metal oxide thin film and a method for manufacturing the same, and more particularly, to a metal oxide thin film solution that can implement a transparent electronic device by low temperature heat treatment, a metal oxide thin film formed using the same and a method for manufacturing the same.

As demand and interest in thin-film displays, such as liquid crystal displays and organic light emitting diodes, have increased, in recent years, efforts to obtain high-quality devices have increased rapidly. As a display driving device, semiconductor device materials based on silicon have been mainly studied.

While silicon has advantages in terms of physical properties, lifespan, and performance stability, vacuum deposition and laser annealing processes are required to form a thin film, and expensive equipment for this is increasing display manufacturing costs. In view of this, efforts have recently been made to use metal oxide materials as semiconductor channel layers, which have the potential to be transparent devices.

The thin film transistor element is basically composed of a semiconductor material, an electrode material and a dielectric material, and recently, a component of this representative device is applied to a new concept device such as a transparent transistor, a transparent memory, or a transparent electrode by applying a transparent metal oxide in the visible region. Research is ongoing. As a representative transparent semiconductor material, inorganic zinc oxide (ZnO) has a wide energy band gap and excellent light transmittance, which has attracted much attention as a channel layer of active regions in thin film transistors. Zirconia (ZrO ₂ ), alumina (Al ₂ O) ₃ ), silica (SiO ₂ ), titania (TiO ₂ ) and the like are widely used as insulating materials in thin film transistors due to their high insulating properties. In addition, in the case of an oxide of a metal such as indium or tin, many studies have been conducted with transparent electrode materials such as electrodes of a transistor and a touch screen because they maintain a high conductivity while being transparent.

However, despite the excellent characteristics, there is a disadvantage in that a high cost vacuum process such as sputtering and pulsed laser deposition (PLD) is required to form such an oxide thin film. Therefore, there is a need for a method of manufacturing a thin film transistor using a solution-based technology, which is mass production capable and a low cost manufacturing process, that is, spin coating, inkjet printing, offset printing, and gravure printing. Precursor materials used in such solution processes must have adequate performance for each component of the thin film transistors, for example semiconductor materials, with high mobility and good switching characteristics, and a high flashing ratio ( I _{on / off} ) and insulation. In the case of layers, it has to have high insulation capacity and proper dielectric constant, and in the case of electrode materials, it has to have high conductivity and low resistivity. In addition, if each component can be formed at a low temperature and maintain transparency, the transistor may be manufactured in a solution process on a transparent polymer substrate other than glass to provide a breakthrough method for implementing a flexible transparent transistor.

Particularly, expressing each of the above-described required characteristics even under low temperature heat treatment of 350 ° C. or less is very important for high quality device implementation. However, the manufacture of a thin film transistor using an oxide thin film and a combination thereof, which can express excellent properties by low temperature heat treatment using a solution state material, is very sensitive to the composition of the solution, the heat treatment temperature after coating and the method. Solutions generally consist of precursors (organic metals, metal salts, etc.) that can implement metal oxides, solvents that can dissolve them, stabilizers for improving solubility, and other additives for coating and viscosity control. The chemical decomposition reaction process and reaction temperature differ depending on the type of precursor used, and thus crystallinity and purity of the oxide thin film formed are determined. Is determined. In general, in the sol-gel method and metal-organic compound solution method (MOD) using metal-organic compounds, metal alkoxides, metal salts, etc., decomposition of precursors and oxide formation reactions mainly require high temperatures of 400 ° C or higher. It is difficult to apply to low-temperature flexible substrates, and even in the case of glass substrates that can be used at relatively high temperatures, warpage and lifting occur, resulting in misalignment and cracking during the next process. Therefore, at present, the heat treatment is performed in advance before the semiconductor process through a pre-compaction process, but such a process is an additional process, and there is a problem that it is difficult to apply to a large glass substrate.

Conventionally, a method for fabricating an oxide semiconductor through a low temperature solution process is mostly a technique by vacuum deposition. In recent years, a number of reports on the sol-gel method, colloidal particle method, organic-metal deposition method, etc. have been reported. Heat treatment and post treatment processes were required.

On the other hand, in the case of the oxide semiconductor, the transition metal added to the oxide semiconductor may be reduced to increase the carrier concentration together with oxygen defects in the thin film. As a result, it may be an alternative to overcome the limitations of mobility by increasing the conductivity of the thin film.However, if a positive bias stress is continuously applied, that is, a positive gate voltage is continuously applied or repeatedly When a voltage is applied and driven, a problem arises in that the threshold voltage of the device is greatly changed in the positive direction. In addition, in the case of a display such as a conventional LCD, OLED, etc., when a negative gate voltage is continuously applied, heat is generated, which causes a problem that the threshold voltage is changed in the negative direction.

This unstable characteristic causes a very big problem in terms of stability as a switching transistor, and thus shows properties that are difficult to apply to a real device.

SUMMARY OF THE INVENTION The present invention has been made under the foregoing technical background, and an object of the present invention is to provide a semiconducting oxide thin film having improved stability against bias (field) stress and heat generation stress caused by negative voltage.

An object of the present invention is to provide a metal oxide thin film that can be formed at a low temperature by a simple process.

Another object of the present invention is to produce a semiconductor thin film by a solution process

The present invention provides a solution for a thin metal oxide thin film and a method of manufacturing the same.

It is another object of the present invention to provide a method for manufacturing an optically transparent thin film which can be formed on a flexible substrate.

Still another object of the present invention is to provide a method for manufacturing an electronic device such as a thin film transistor by using a 350 ° C. or lower, for example, 250 ° C. to 350 ° C. low temperature solution process.

Still another object of the present invention is to provide a method for manufacturing an electronic device capable of expressing high performance and high stability at low temperature by a simple process.

Other objects and technical features of the present invention will be presented in more detail in the following detailed description.

Composition for a metal oxide thin film according to an embodiment of the present invention is a metal hydroxide; And, an acid group titrant for controlling the solubility of the metal hydroxide, the concentration of the metal hydroxide is 0.05 to 40 mol / L.

In one embodiment, the acid group titrant may be selected from ammonia, tetra methyl ammonium hydroxide, methylamine, urea, acetic acid, hydrochloric acid, nitric acid, sulfuric acid, hydrogen peroxide and combinations thereof.

In one embodiment, the metal hydroxide may be aluminum hydroxide (Al (OH) ₃ ), zinc hydroxide (Zn (OH) ₂ ), gallium hydroxide (Ga (OH) ₃ ), indium hydroxide (In (OH) ₃ ), tin It may include a first metal hydroxide selected from hydroxide (Sn (OH) ₄ ) and a combination thereof.

In one embodiment, the metal hydroxide may be aluminum hydroxide (Al (OH) ₃ ), zinc hydroxide (Zn (OH) ₂ ), gallium hydroxide (Ga (OH) ₃ ), indium hydroxide (In (OH) ₃ ), tin Yttrium hydroxide (Y (OH) ₃ ), zirconium hydroxide (Zr (OH) ₄ ), hafnium hydroxide (Hf) to improve the bias stability and the first metal hydroxide selected from hydroxide (Sn (OH) ₄ ) and combinations thereof (OH) ₄ ), scandium hydroxide (Sc (OH) ₃ ), gallium hydroxide (Ga (OH) ₃ ), lanthanum hydroxide (La (OH) ₃ ) and a second metal hydroxide selected from combinations thereof can do.

In one embodiment, the first metal hydroxide and the second metal hydroxide may be included in a molar ratio of 1: 0 to 0.2.

In one embodiment, the first metal hydroxide and the second metal hydroxide may be included in a molar ratio of 1: 0 to 0.02.

In one embodiment, the metal hydroxide may be aluminum hydroxide (Al (OH) ₃ ), zinc hydroxide (Zn (OH) ₂ ), gallium hydroxide (Ga (OH) ₃ ), indium hydroxide (In (OH) ₃ ), tin Hydroxide (Sn (OH) ₄ ) and a first metal hydroxide selected from a combination thereof, yttrium hydroxide (Y (OH) ₃ ), zirconium hydroxide (Zr (OH) ₄ ), and hafnium hydroxide (Hf) to improve bias stability Second metal hydroxide selected from (OH) ₄ ), scandium hydroxide (Sc (OH) ₃ ), gallium hydroxide (Ga (OH) ₃ ), lanthanum hydroxide (La (OH) ₃ ) and combinations thereof In order to improve the performance in the lithium hydroxide (Li (OH), titanium oxide (Ti (OH)), it may further include a third metal hydroxide selected from a combination of these materials.

In one embodiment, the first metal hydroxide, the second metal hydroxide and the third metal hydroxide may be included in a molar ratio of 1: 0 to 0.2: 0 to 0.2.

In one embodiment, the first metal hydroxide, the second metal hydroxide and the third metal hydroxide may be included in a molar ratio of 1: 0 to 0.02: 0 to 0.02.

In one embodiment, the metal hydroxide may be aluminum hydroxide (Al (OH) ₃ ), zinc hydroxide (Zn (OH) ₂ ), gallium hydroxide (Ga (OH) ₃ ), indium hydroxide (In (OH) ₃ ), tin Hydroxide (Sn (OH) ₄ ) and a first metal hydroxide selected from the combination thereof and lithium hydroxide (Li (OH), titanium oxide (Ti (OH)), and combinations thereof for improved performance at low temperatures It may include a third metal hydroxide selected from.

In one embodiment, the first metal hydroxide and the third metal hydroxide may be included in a molar ratio of 1: 0 to 0.2.

In one embodiment, the first metal hydroxide and the third metal hydroxide may be included in a molar ratio of 1: 0 to 0.02.

In one embodiment, the metal hydroxide is zirconium hydroxide (Zr (OH) ₄ ), hafnium hydroxide (Hf (OH) ₄ ), aluminum hydroxide (Al (OH) ₃ ), yttrium hydroxide (Y (OH) ₃ ), And a fourth metal hydroxide selected from gadolinium hydroxide (Gd (OH) ₃ ), lanthanum hydroxide (La (OH) ₃ ), and combinations thereof.

Oxide thin film formation method according to an embodiment of the present invention is a metal hydroxide dissolved in an aqueous or non-aqueous solvent; And applying a composition for an oxide thin film comprising an acidic acid titrant for controlling solubility of the metal hydroxide on a substrate; And, the step of heat-treating the substrate to which the composition is applied.

In one embodiment, the heat treatment may be performed in a vacuum or reducing atmosphere in the range of 100 ℃ ~ 350 ℃.

In one embodiment, the substrate may be a flexible substrate, a transparent substrate or a glass substrate.

In one embodiment, the heat treatment may be performed in a hotplate, convection oven, box, or using microwave.

Metal oxide thin film according to an embodiment of the present invention is a metal hydroxide dissolved in an aqueous or non-aqueous solvent; The oxide thin film composition including an acidic acid titrant for controlling the solubility of the metal hydroxide may be formed by applying a heat treatment to a substrate.

In one embodiment, the substrate may be a flexible substrate, a transparent substrate or a glass substrate.

In one embodiment, the metal oxide thin film may be used as an active layer of a thin film transistor.

Composition for the oxide thin film according to an embodiment of the present invention is: aluminum hydroxide (Al (OH) ₃ ), zinc hydroxide (Zn (OH) ₂ ), gallium hydroxide (Ga (OH) ₃ ), Indium hydroxide (In (OH) ₃ ), a first metal hydroxide selected from tin hydroxide (Sn (OH) ₄ ) and a combination thereof; Yttrium hydroxide (Y (OH) ₃ ), zirconium hydroxide (Zr (OH) ₄ ), hafnium hydroxide (Hf (OH) ₄ ), scandium hydroxide (Sc (OH) ₃ ), gallium hydroxide (Ga (OH) ₃ ), Lanthanum hydroxide (La (OH) ₃ ) and a second metal hydroxide selected from combinations thereof; A third metal hydroxide selected from lithium hydroxide (Li (OH), titanium oxide (Ti (OH)), and a combination thereof; and an acid group titrant for controlling solubility of the metal hydroxides. The total concentration of hydroxides is characterized in that from 0.05 to 10 mol / L.

In one embodiment, the first metal hydroxide, the second metal hydroxide and the third metal hydroxide may be included in a molar ratio of 1: 0 to 0.2: 0 to 0.2.

In one embodiment, the first metal hydroxide, the second metal hydroxide and the third metal hydroxide may be included in a molar ratio of 1: 0 to 0.02: 0 to 0.02.

In one embodiment, the acid group titrant may be selected from ammonia, tetra methyl ammonium hydroxide, methylamine, urea, acetic acid, hydrochloric acid, nitric acid, sulfuric acid, hydrogen peroxide and combinations thereof.

The metal oxide thin film according to the embodiment of the present invention includes: a first metal selected from aluminum, zinc, gallium, indium, tin, and combinations thereof; A second metal selected from yttrium, zirconium, hafnium, scandium, gallium, lanthanum, and combinations thereof; And a third metal selected from lithium, titanium, and combinations thereof, wherein the first metal, the second metal, and the third metal are included in a ratio of atoms of 1: 0 to 0.2: 0 to 0.2.

In one embodiment, the first metal, the second metal and the third metal are included in the ratio of the number of atoms of 1: 0 to 0.02: 0 to 0.02.

According to the present invention, a semiconductor, insulator, and conductor thin film constituting an electronic device using a metal hydroxide is formed at a low temperature through a simple process, and printing, spinning, coating, etc. may be used as a thin film forming method.

The present invention can be used to manufacture thin film transistors, solar cells, various sensors and memory devices.

According to the present invention, it is possible to implement various electronic devices only by a solution process, thereby greatly reducing the cost of manufacturing electronic devices, and in particular, the implementation of flexible devices and optically transparent electronic devices.

The semiconducting oxide thin film according to the present invention effectively compensates for the disadvantages of inferior device stability and reproducibility due to an electric field application effect, thereby simultaneously exhibiting operational stability and excellent semiconductor properties.

According to the present invention, when Y, Zr, Hf, Sc, Ga, La, etc. are added, a high stability device is realized by effectively controlling the movement of the threshold voltage due to heat generated when a negative bias field is applied. Complementary excellent semiconductor device performance is possible.

In addition, when the metal (Li, Ti) is added to improve the performance, high performance can be expressed even at low temperatures.

1 is a graph showing the change in solubility according to acidity and basic degree (pH) for various metal elements.

Figure 2 is a process diagram showing the manufacturing step of the metal oxide thin film according to the present invention.

3A to 3C are graphs showing thin film transistor transfer characteristics according to heat treatment temperature of the zinc oxide thin film formed through Example 1 of the present invention.

4a to 7b are IV and CV graphs showing the performance according to the microwave oven heat treatment temperature of the ZrO _x insulation layer formed in Example 1 of the present invention.

8 is a photograph showing a ZnO-based transparent thin film transistor array manufactured according to Example 1 of the present invention.

9A to 9D are graphs showing thin film transistor transfer characteristics according to zirconium concentration of the zirconium zinc oxide thin film formed through Example 4 of the present invention.

10A to 10D are graphs showing a change in performance according to time variation in applying positive bias stress according to the zirconium concentration of the zirconium zinc oxide thin film formed through Example 4 of the present invention.

11a to 11c are graphs showing the thin film transistor transfer characteristics according to the yttrium concentration of the yttrium zinc oxide thin film formed through the fifth embodiment of the present invention.

12A to 12C are graphs showing a change in performance according to a time variation in applying a positive bias stress according to the yttrium concentration of the yttrium zinc oxide thin film formed through Example 5 of the present invention.

13 is a graph comparing the change in the threshold voltage over time for the yttrium zinc oxide thin film formed through Example 5 of the present invention.

FIG. 14 is a graph showing a change in threshold voltage with time of applying negative bias and thermal stress to the yttrium zinc oxide thin film formed through Example 5 of the present invention; FIG.

15A to 15C are graphs showing thin film transistor transfer characteristics according to lithium concentration of a lithium zinc oxide thin film formed through Example 6 of the present invention.

FIG. 16 is a graph showing thin film transistor transfer characteristics of a lithium and zirconium zinc oxide thin film formed through Example 7 of the present invention; FIG.

FIG. 17 is a graph showing a change in performance according to a change in time for applying a positive bias stress of a lithium and zirconium zinc oxide thin film formed through Example 7 of the present invention. FIG.

Embodiments of the present invention can express semiconductor, insulator and conductor characteristics through low temperature process by using metal hydroxide which is close to oxide as a starting material and does not generate residual organic matter when forming thin film by solution method. A transparent oxide thin film and a method of forming the same are proposed.

In order to form an oxide semiconductor thin film, as a metal hydroxide, aluminum hydroxide (Al (OH) ₃ ), zinc hydroxide (Zn (OH) ₂ ), gallium hydroxide (Ga (OH) ₃ ), indium hydroxide (In (OH) ₃ ) ), Tin hydroxide (Sn (OH) ₄ ) or a combination thereof may be used. Such metal hydroxide for semiconductor may be included in a concentration of 0.05 to 40 mol / L, a concentration of 0.05 to 20 mol / L, a concentration of 0.05 to 10 mol / L.

Yttrium, zirconium, hafnium, scandium, gallium, lanthanum, or a combination thereof may be added for bias and / or temperature stability of the semiconductor thin film. Positive bias stress and negative bias of oxide semiconductor thin film, performance instability with temperature (change of threshold voltage according to voltage application and heat) are alleviated by the addition of these elements yttrium, zirconium, hafnium, scandium, gallium, lanthanum It can be removed to express a stable semiconductor characteristics.

In addition, lithium, titanium, or a combination thereof may be added for high performance of the semiconductor thin film. Due to their addition, high performance semiconductor devices can be manufactured.

By adding these two kinds of metal elements (elements for stabilization: Y, Zr, Hf, Sc, Ga, La) and (elements for improving performance: Li, Ti), a semiconductor capable of producing stable and high performance can be produced. . These two kinds of elements are the above-mentioned aluminum hydroxide (Al (OH) ₃ ), zinc hydroxide (Zn (OH) ₂ ), gallium hydroxide (Ga (OH) ₃ ), indium hydroxide (In (OH) ₃ ), tin hydroxide (Sn (OH) ₄ ) may be included as a mole number of 0 to 2, 0 to 20 compared to 100 moles of metal hydroxide for semiconductors. For example, precipitation may occur when the number of moles of zinc is greater than 20, compared to 100 moles of zinc hydroxide.

Yttrium, zirconium, hafnium, scandium, gallium, lanthanum elements may be added in hydroxide form. Yttrium hydroxide (Y (OH) ₃ ), zirconium hydroxide (Zr (OH) ₄ ), hafnium hydroxide (Hf (OH) ₄ ), scandium hydroxide (Sc (OH) ₃ ), gallium hydroxide (Ga ( OH) ₃ ) and lanthanum hydroxide (La (OH) ₃ ) are more effective in the Y, Zr, Hf, Sc, Ga, and La elements, which can cause relatively strong ion defects with oxygen than the Zn, Sn, and In elements. As a result, the semiconductor film is stabilized and is not significantly influenced by positive, negative bias and heat stress, so that the gate voltage is applied for a long time, or the effect of changing the threshold voltage even in the case of repeated application or heat application is greatly reduced.

The inventors also confirmed that lithium hydroxide Li (OH) and titanium hydroxide (Ti (OH)) increase the number of electron carriers when a certain amount of Li and Ti metal elements are added to improve the performance.

Meanwhile, in order to form an insulator thin film, as a metal hydroxide, zirconium hydroxide (Zr (OH) ₄ ), hafnium hydroxide (Hf (OH) ₄ ), aluminum hydroxide (Al (OH) ₃ ), yttrium hydroxide (Y (OH) ₃ ), gadolinium hydroxide (Gd (OH) ₃ ), lanthanum hydroxide (La (OH) ₃ ) or a combination thereof may be used.

Meanwhile, to form a conductor thin film, zinc hydroxide (Zn (OH) ₂ ), indium hydroxide (In (OH) ₃ ), tin hydroxide (Sn (OH) ₄ ), aluminum hydroxide (Al (OH) ₃ ) or Combinations of these can be used.

The inventors of the present invention can dissolve most of the metal hydroxide corresponding to the oxide required in the transparent electronic device without an additional stabilizer under acidic or basic conditions, and the thin film prepared therefrom is, for example, at a low temperature of 200 ° C to 250 ° C. It was confirmed that the change to the corresponding oxide at ℃.

In addition, in order to enable such a change reaction at a cryogenic temperature (about 140 ° C.), in the present invention, by using microwave heat treatment, the metal hydroxide can selectively and effectively absorb microwave energy to promote the change into the oxide. As a result, flexible transparent electronic devices could be implemented on plastic substrates.

In particular, in the present invention, a thin film expressing semiconducting, insulating, and conductive properties can be prepared by directly using a high purity metal hydroxide as a starting material without undergoing a precipitation process from a metal salt.

In the case of an oxide film starting from a complex material such as a metal salt, metal alkoxide, or metal-organic compound used in a solution process, the thin film formation process and steps are complicated. In the case of metals, salts and alkoxides attached thereto, they are reacted through sol-gel reactions through hydrolysis and condensation processes. It may act as an impeding factor or impede the electrical properties, which can be removed only by the high temperature heat treatment, resulting in the formation of an oxide thin film exhibiting device performance only through the high temperature heat treatment.

On the other hand, the metal hydroxide which is a starting material proposed in the present invention can be dissolved at an appropriate pH condition, and can be dissolved in a thin film only through pyrolysis and dehydroxylation at low temperature without complicated multi-step reaction such as desorption and decomposition of additional organic materials. It is possible to form a high quality oxide film without impurities such as organic matter or anion remaining. Appropriate acid group titrants can be used to dissolve metal hydroxides without the need for a separate stabilizer. The acid group titrant may be included, for example, at a concentration of 0.05 to 40 mol / L. As the acid group titrant, ammonia, tetramethyl ammonium hydroxide, methylamine, urea, acetic acid, hydrochloric acid, nitric acid, sulfuric acid, hydrogen peroxide, or a combination thereof can be used.

1 shows solubility changes according to acidity and basicity (pH) of various metal elements. From these results, the pH can be controlled to control the solubility of metal hydroxides. It is possible to determine a group of metal elements applicable to implementing a metal oxide representing.

In addition, in the case of using microwave annealing, these precursors effectively increase the mobility of atoms in the material from the microwave, thereby promoting the dehydration reaction, removing impurities, and improving crystallinity. The reaction completion is more efficient than in the heat treatment method, and improved performance can be achieved at low temperatures.

2 shows a step of manufacturing a metal oxide thin film according to the present invention. The metal hydroxide is dissolved in an aqueous or non-aqueous solvent containing an acid / base titrant and stabilized through stirring to prepare a precursor solution for the metal oxide thin film.

In the present invention, various materials may be used for the metal hydroxide depending on the physical properties required for the final metal oxide. For example, a zinc oxide (ZnO) thin film can be obtained using zinc hydroxide as a starting material of a semiconducting thin film, and an aluminum hydroxide, gallium hydroxide, indium hydroxide, tin hydroxide, or a combination thereof is used as a starting material. Aluminum-zinc oxide (AZO), tin-zinc oxide (ZTO), gallium-tin-zinc oxide (GSZO), indium-zinc oxide (IZO) thin films, and the like can be obtained.

In addition, yttrium hydroxide (Y (OH) ₃ ), zirconium hydroxide (Zr (OH) ₄ ), hafnium hydroxide (Hf (OH) ₄ ), scandium hydroxide (Sc (OH) ₃ ), gallium hydroxide ( Thin films of ZrZnO, YZnO, GaZnO, ScZnO, HfZnO, LaZnO and the like can be obtained using Ga (OH) ₃ ), lanthanum hydroxide (La (OH) ₃ ), or a combination thereof.

In addition, in order to improve the performance such as mobility at low temperature, LiZnO and TiZnO thin films can be obtained using lithium hydroxide Li (OH), titanium hydroxide Ti (OH) or a combination thereof.

In addition, a thin film of LiZrZnO, LiYZnO, LiGaZnO, LiScZnO, LiHfZnO, or LiLaZnO may be obtained using a combination of the above-described metal hydroxide for improving stability and metal hydroxide for improving performance in order to obtain a high performance and high stability thin film. .

For dielectric thin films, zirconia (ZrO ₂ ), hafnia (HfO ₂ ), alumina (Al ₂ O ₃ ) made of zirconium hydroxide, hafnium hydroxide, aluminum hydroxide, lanthanum hydroxide, gadolinium hydroxide, yttrium hydroxide, etc. ), Lanthanum (La ₂ O ₃ ), gadolia (Gd ₂ O ₃ ), yttria (Y ₂ O ₃ ) thin film.

To form a conductor such as an electrode, indium tin oxide (ITO), indium oxide (I ₂ O ₃ ), tin oxide (SnO ₂ ), zinc oxide through indium hydroxide, tin hydroxide, zinc hydroxide, aluminum hydroxide or a combination thereof Aluminum oxide (AlZnO) thin films can be fabricated.

The acid group titrant mixed to improve the solubility of the metal hydroxide may vary depending on the metal hydroxide used. Specifically, ammonia, tetra methyl ammonium hydroxide, methylamine, urea, acetic acid, hydrochloric acid, nitric acid, sulfuric acid, hydrogen peroxide and the like may be used as the acid group titrant, but are not necessarily limited to these materials. A more effective titrant may form a complex with dissolved metal ions to increase the solubility, and the more capable of being decomposed at low temperature, the better properties can be expressed. The acid group titrant may be included, for example, at a concentration of 0.05 to 40 mol / L.

The stirring step can last 12 hours or longer. The stirred solution forms a thin film or patterned film on the substrate through spin coating or inkjet printing or the like. After forming a thin film or a film pattern, a microwave heat treatment is performed to change the metal hydroxide into a metal oxide.

Heat treatment step in the embodiment of the present invention was maintained in the microwave oven heat treatment output 2KW, frequency: 2.45GHz, the heat treatment temperature range of 100 ~ 400 ℃, the heat treatment atmosphere was maintained in a vacuum or reducing atmosphere. Microwave heat treatment can accelerate the phase change reaction through time and selective heating than conventional heat treatment, so it can be processed short time at low temperature, and efficient heat treatment of various methods such as continuous microwave heat treatment and microwave heat treatment by pulse method Can be converted in a manner. The obtained oxide thin film can be subsequently added secondary annealing in various atmosphere conditions at a temperature of 100 ~ 300 ℃ as needed.

In the present invention, the solution in which the metal hydroxide is dissolved may use an aqueous solvent or a non-aqueous solvent.

Aqueous veins may be used alone or in admixture with water, and ammonia, tetramethyl ammonium hydroxide, methylamine, urea, acetic acid, hydrochloric acid, nitric acid, sulfuric acid, aqueous hydrogen peroxide solution, or a combination thereof may be used.

Aqueous solvents do not act as residual organic components because the volatilization temperature is lower than the temperature at which other organic components are decomposed and removed, and lower than the reaction temperature of the metal hydroxide, thereby improving coating properties or forming a thin film interface (semiconductor-dielectric interface). Can be used to form trap sites.

The aqueous solvent may be used alone or in a mixed state with water, and an aqueous ammonia solution, an aqueous hydrogen peroxide solution, or the like, or a combination thereof may be used.

The non-aqueous organic solvent may be used alone or in admixture with water, for example n-butyl acetate. 2-methoxy-1-methylethylacetate (PGMEA), 1-methoxy-2-propanol (PGME), 1-propanol , 1-butanol and the like can be used.

Hereinafter, the characteristics of the oxide thin film and its utility as a semiconductor, an insulator, and a conductor according to the present invention will be described in detail through specific examples.

EXAMPLE  1. Zinc Oxide ( ZnO ) Fabrication of Semiconductor Thin Films

Zinc hydroxide (Zn (OH) ₂ ) was used as a starting material, and the precursor was highly soluble in basic so that the zinc hydroxide was dissolved in an aqueous ammonia solution and then stirred at room temperature for 12 hours to prepare a semiconducting solution. The solution was spin coated onto a substrate to prepare a thin film, which was then heat treated using a conventional heat treatment and microwave oven. Since zinc hydroxide dehydration occurs at about 120 ° C., it is possible to express semiconductor performance at 120 ° C. or higher. The microwave oven has made it possible to realize oxide thin film transistors having excellent semiconductor characteristics at the same temperature than conventional heat treatment methods.

A thin film transistor having a bottom gate / top contact structure was formed using the zinc oxide thin film obtained after the heat treatment.

3A to 3C are thin film transistor transfer characteristics of a zinc oxide (ZnO) thin film formed through Example 1 (FIG. 3A: 140 ° C, FIG. 3B: 220 ° C, and 3C: 320 ° C). This is a graph.

Each graph is spin-coated Zn (OH) ₂ solution dissolved in ammonia water and heat-treated by microwave oven at different heat treatment temperatures, while changing V _g from -40V to 40V while maintaining V _d at a constant value of 20V. It is a measurement of the transmission characteristics. Specific device characteristic values are shown in Table 1 below. The device characteristic values are the best performance at the lowest temperatures based on the results reported in the paper so far.

Table 1

Temperature	140 ℃	220 ℃	320 ℃
Mobility (cm 2 / Vs)	1.75	2.75	5.72
Threshold Voltage (Vth) (V)	8.04	6.7	2.93
Subthreshold slope (V / dec)	0.74	0.55	0.86
On / off ratio	10 7	10 7	10 7

EXAMPLE  2. ZrO _x Fabrication of Dielectric Thin Films

Zirconium hydroxide (Zr (OH) ₄ ) was used as a starting material, and since the precursor has high solubility in basic, the dielectric solution was prepared by dissolving zirconium hydroxide in an aqueous ammonia solution and stirring at room temperature for 12 hours. The solution was spin coated onto a substrate to prepare a thin film, which was then heat treated using a conventional heat treatment and microwave oven. It was found that insulation properties were expressed at 250 ° C or higher. The microwave oven has made it possible to realize an oxide thin film having excellent insulation properties at the same temperature than the conventional heat treatment method.

Dielectric properties of the zirconium oxide thin films obtained after the heat treatment were investigated. 4A-7A and 4B-7B are microwave oven heat treatment temperatures (FIGS. 4A, 4B: 250 ° C, 5A, 5B: 300 ° C, 6A, 6B: 350 ° C, and 7A, 7B: 400 ° C). IV and CV graphs showing the performance of the ZrO _x insulating layer. In addition, the dielectric properties (insulation strength, dielectric constant) of the zirconium oxide thin film according to the heat treatment temperature were measured and shown in Table 2.

TABLE 2

	Dielectric strength (MV / cm)	Dielectric constant: Dielectric constant (K)
250 ℃	0.56	9.97
300 ℃	0.98	9.8
350 ℃	1.39	11.0
400 ℃	1.68	9.2

EXAMPLE  3. Transparent transistor manufacturing through the whole solution process

ITO or AZO electrode material prepared by the solution method using a metal hydroxide starting material on a PES (Polyethersulfone) substrate or a glass substrate by spin coating, and then using a zirconium hydroxide (Zr (OH) ₄ ) as a starting material A dielectric solution was prepared by the method and applied by spin coating to form a ZrO _x dielectric film. Depart Zn (OH) ₂ on it

The solution prepared as a material was applied by spin coating, then heat-treated at 140 ° C., and finally, the ITO or AZO solution was patterned, or the aluminum electrode was deposited by evaporation. A transparent flexible device formed through the above was produced.

FIG. 8 is a photograph showing a ZnO-based transparent thin film transistor array fabricated according to the present embodiment, and it is possible to fabricate a device capable of expressing electrical characteristics comparable to that of a transparent, conventional vacuum deposition crystalline Si-based device on a flexible PES substrate. Confirmed.

EXAMPLE  4. Zirconium Zinc Oxide ( ZrZnO ) Fabrication of Semiconductor Thin Films

Zinc hydroxide (Zn (OH) ₂ ) and zirconium hydroxide (Zr (OH) ₄ ) were used as starting materials. Since this precursor is basic in solubility, in order to further improve stability after dissolving zinc hydroxide in aqueous ammonia solution Zirconium hydroxide was dissolved at varying concentrations. At this time, the molar ratio (atomic ratio) of zinc and zirconium was such that the mole number of the zirconium precursor was 0, 0.5, 1, 2 when the number of moles of the zinc precursor was 100. That is, the ratio of the number of atoms of zinc to zirconium was 1: 0, 1: 0.005, 1: 0.01, 1: 0.02.

Thereafter, the mixture was stirred at room temperature for 12 hours to prepare a semiconducting solution. Before spin-coating the above solution, a 100-nm-thick SiO ₂ substrate (Heavily Doped Silicon Substrate) was cleaned by sonication in a piranha solution (Sulfur Acid: Hydroperoxide = 4: 1) for 5 minutes. , Methyl alchohol, Iso-propyl alcohol (IPA), Ethyl alcohol, DI-Water was washed in the same manner.

The washed substrate was dried with an IR-Lamp for 30 minutes to remove moisture, and then irradiated with UV-Lamp for 1 hour to modify the surface to be hydrophilic. The solution was spin coated onto a substrate to prepare a thin film, and then heat-treated using a hot plate. Dehydration of zinc hydroxide occurs at about 120 ° C., and dehydration of zirconium hydroxide occurs at about 250 ° C., so that semiconductor performance can be expressed above 250 ° C. The addition of zirconium hydroxide has made it possible to realize oxide thin film transistors having superior bias stability at the same temperature than semiconductors manufactured using only pure zinc hydroxide.

A thin film transistor having a bottom gate / top contact structure was formed using a zirconium zinc oxide thin film obtained after the heat treatment.

9A to 9D are added by changing the molar concentration of the zirconium metal element of the zirconium oxide (ZrZnO) thin film formed through Example 4 (Fig. 9A: 0%, Fig. 9B: 0.5%, Fig. 9C: 1%, Fig. 9d: 2%) A graph showing a transfer curve of a thin film transistor.

Each graph spin coated _{Zn (OH) 2, Zr (} OH) 4 were dissolved in aqueous ammonia and by changing a heat treatment for two hours at 350 ℃ using a hot plate, and then, the V _g from -40V to 40V V _d is The transmission characteristics were measured while maintaining a constant value of 20V. Specific device characteristic values are shown in Table 3 below.

TABLE 3

Zirconium Doping Mole Ratio	0%	0.5%	One%	2%
Mobility (cm 2 / Vs)	2.08	1.82	1.74	1.23
Threshold Voltage (Vth) (V)	3.7	4.1	4.5	7.2
On / off ratio	10 7	10 7	10 7	10 6

According to this performance measurement, the pure zinc oxide thin film transistor fabricated at 350 ° C showed very good results with mobility of 2.08 cm ² / Vs, an operating voltage of 4.1 V, and a flashing ratio of 10 ⁷ . . Therefore, it was confirmed that a semiconductor film having excellent operating characteristics can be produced through a solution process. However, the mobility was slightly decreased when zirconium metal ions were added.

In addition, the gate voltage was applied to the ZnO semiconductor film prepared in Example 4 and the ZrZnO composition semiconductor film prepared by adding the Zr element for 500 seconds, and the change in device performance according to the bias stress was shown in 10a to 10d, respectively. In the case of the ZrZnO thin film containing zirconium, the threshold voltage does not increase significantly but shows a stable appearance. In the case of the ZnO thin film containing no zirconium, the threshold voltage increases as the bias stress is applied.

Table 4 below shows a change in threshold voltage. In the case of ZrZnO thin film, unlike ZnO, even when bias stress is applied, the threshold voltage shows little change with little change.

Table 4

Zirconium Doping Mole Ratio	Threshold Voltage Change (ΔV th )
0%	~ 12V
0.5%	~ 8V
One%	~ 4.6 V
2%	~ 4.8 V

In addition, in order to confirm stability improvement at low temperature process, the same change as above to check whether the threshold voltage change decreases even when bias stress is applied by the addition of zirconium ion in the transistor fabricated at 250 ° C, which is the temperature at which ZrZnO thin film can be formed. As a result of the experiment, as can be seen in Table 5, it can be seen that there is a tendency that the amount of change in the threshold voltage decreases and then saturates. That is, it can be seen that the stability of the device is improved due to the addition of zirconium.

Table 5

Zirconium Doping Mole Ratio	Threshold Voltage Change (ΔV th )
0%	~ 13.1 V
0.5%	~ 9.2 V
One%	~ 5.2 V
2%	~ 6.7 V

EXAMPLE  5. High Stability Yttrium Zinc Oxide through Yttrium Doping YZnO Fabrication of Thin Film Semiconductor Thin Films

Zinc hydroxide (Zn (OH) ₂ ), yttrium hydroxide (Y (OH) ₃ ) were used as starting materials. Since the precursor is solubility in basic, to dissolve zinc hydroxide in aqueous ammonia solution to further improve stability Yttrium hydroxide was dissolved. At this time, the molar ratio (atomic ratio) of zinc and yttrium was such that the mole number of the zirconium precursor was 0, 0.5, 1, 2 when the mole number of the zinc precursor was 100. Thereafter, the mixture was stirred at room temperature for 12 hours to prepare a semiconducting solution. The substrate was treated by the same experimental method as described in Example 4, and then the solution was spin coated onto the substrate to prepare a thin film, which was then heat treated using a hot plate. Dehydration of zinc hydroxide occurs at about 120 ° C. and dehydration of yttrium hydroxide occurs at about 280 ° C., so that the semiconductor performance can be expressed above 300 ° C. The addition of yttrium hydroxide has made it possible to realize oxide thin film transistors having an excellent amount of bias stability at the same temperature than semiconductors manufactured using only pure zinc hydroxide. In addition, the oxide thin film transistor has a high stability under negative bias and thermal stress.

A thin film transistor having a bottom gate / top contact structure was formed using the yttrium zinc oxide thin film obtained after the heat treatment.

11A to 11C are thin films added by varying the yttrium metal element molar concentration of the yttrium zinc oxide (YZnO) thin film formed through Example 5 (Fig. 11a: 0.5%, Fig. 11b: 1%, and Fig. 11c: 2%) This graph shows the transfer curve of a transistor.

Each graph by changing the spin of _{Zn (OH) 2, Y (} OH) 3 dissolved in aqueous ammonia, and coating the heat treatment using a hot plate to 350 ℃ Next, the V _g from -40V to 40V V _d is a constant value of 20V The transfer characteristics were measured while maintaining the Specific device characteristic values are shown in Table 6 below.

According to this performance measurement, the mobility of the yttrium zinc (YZnO) thin film having a yttrium elemental molar concentration of 0.5% shows a very good mobility of 1.93 cm ² / Vs, an operating voltage of 3.9 V and a flashing ratio of 10 ⁷ . Very good operating characteristics. Therefore, it was confirmed that a semiconductor film having excellent operating characteristics can be produced through a solution process. However, when yttrium metal ions were added, the mobility was slightly decreased, similar to the case of zirconium addition in Example 4.

Table 6

Yttrium Doping Mole Ratio	0%	0.5%	One%	2%
Mobility (cm 2 / Vs)	2.08	1.93	1.81	1.21
Threshold voltage (V)	3.7	3.9	4.1	8.2

In addition, the gate voltage was applied for 500 seconds to the ZnO semiconductor film prepared in Example 2 and the YZnO-containing semiconductor film prepared by adding the Y element, and the change in device performance according to the bias stress was shown in FIGS. 12A to 12C, respectively. . In the case of the YZnO thin film containing yttrium, it was confirmed that the threshold voltage did not increase significantly and showed a stable state similar to the device to which the zirconium metal element added in Example 4 was added. Table 7 is a table showing the amount of change in the threshold voltage, YZnO thin film, unlike the ZnO can be seen that the low value with little change in the threshold voltage, even if bias stress is applied.

TABLE 7

Yttrium doping mol ratio	Threshold Voltage Change (ΔV th )
0%	~ 12V
0.5%	~ 4.3 V
One%	~ 3.87 V
2%	~ 5.98 V

In addition, in order to confirm the stability improvement in the low temperature process, in the transistor fabricated at 300 ° C. at which the temperature of the YZnO thin film can be formed, the amount of change in the threshold voltage is reduced even when bias stress is applied by the addition of yttrium ions. As a result of the experiment in the same way, as shown in Table 8, it can be seen that the threshold voltage change tends to decrease and then increase again. That is, it can be confirmed that the stability of the device is improved by the addition of yttrium ions.

Table 8

Yttrium doping mol ratio	Threshold Voltage Change (ΔV th )
0%	~ 12.6 V
0.5%	~ 6.3 V
One%	~ 4.87 V
2%	~ 8.1V

FIG. 13 is a table showing the amount of change in the threshold voltage according to the change of time. In the case of YZnO thin film, even if a positive bias is applied for a long time, the value of the threshold voltage remains low with little change in the threshold voltage. In this case, it can be seen that the threshold voltage is increased by applying a positive bias stress.

In addition, the negative bias and thermal stress for the semiconductor films of the two compositions are applied for two hours, and the change is shown in FIGS. 14A to 14B. In the case of YZnO (FIG. 14B) thin film containing yttrium, the threshold voltage is almost unchanged and stable, whereas in the case of Ynn-containing ZnO (FIG. 14A) thin film, the threshold is applied with negative bias and thermal stress. It was confirmed that the voltage dropped.

EXAMPLE  6. Lilium  High performance oxidation through doping Lilium  zinc( LiZnO ) Fabrication of Semiconductor Thin Films

Zinc hydroxide (Zn (OH) ₂ ), Lithium hydroxide (Li (OH)) were used as starting materials. Since this precursor is basic in solubility, it is necessary to dissolve zinc hydroxide in aqueous ammonia solution to further improve mobility. Lithium hydroxide was dissolved. At this time, the molar ratio (atomic ratio) of zinc and lithium was such that the mole number of the zirconium precursor was 0, 0.5, 1, and 2 when the mole number of the zinc precursor was 100. Thereafter, the mixture was stirred at room temperature for 12 hours to prepare a semiconducting solution. After the substrate was treated as in Example 4, the solution was spin coated onto the substrate to prepare a thin film, and then heat-treated using a hot plate. Dehydration of zinc hydroxide occurs at about 120 ° C., and dehydration of lithium hydroxide occurs at about 300 ° C., so that semiconductor performance can be expressed at 300 ° C. or higher. The addition of lithium hydroxide enables the implementation of oxide thin film transistors having superior semiconductor performance at the same temperature than semiconductors manufactured using only pure zinc hydroxide.

A thin film transistor having a bottom gate / top contact structure was formed using a lithium zinc oxide (LiZnO) thin film obtained after the heat treatment.

15A to 15C are thin films added by changing the molar concentration of the elemental lithium element of the lithium zinc oxide (LiZnO) thin film formed through Example 6 (FIG. 15A: 0.5%, FIG. 15B: 1%, and FIG. 15C: 2%) This graph shows the transfer curve of a transistor.

Each graph is spin-coated Zn (OH) ₂ , Li (OH) solution dissolved in ammonia water, heat-treated at 350 ° C using a hot plate, and V _d is constant value of 20V while changing V _g from -40V to 40V. The transfer characteristics were measured while maintaining the Specific device characteristic values are shown in Table 9 below.

Table 9

Lithium doping mol ratio	0%	0.5%	One%	2%
Mobility (cm 2 / Vs)	2.08	4.7	10.5	4.68
Threshold Voltage (Vth) (V)	3.7	2.9	1.2	3.1
On / off ratio	10 7	10 8	10 8	10 8

According to this performance measurement, the mobility of the transistor with 1% lithium metal element molarity of lithium zinc (LiZnO) thin film showed very good results as 10.5 cm ² / Vs, the operating voltage was 1.2 V and the flashing ratio was 10 ⁸ . Very good operating characteristics. Therefore, it was confirmed that a semiconductor film having excellent operating characteristics can be produced through a solution process. In addition, as the lithium ions were added, the mobility and on / off current ratio increased significantly and then decreased again.

In addition, for the purpose of confirming the improvement of mobility in the low temperature process, in order to confirm whether the mobility and on / off current ratio is improved by the addition of lithium ions in the transistor fabricated at a temperature of 300 ℃ which is a temperature capable of forming a LiZnO thin film. As shown in Table 10, as shown in Table 10, the mobility of 3.22 cm ² / Vs, operating voltage 11.28 V, and flashing ratio is 10 ⁷ in a transistor with a 1% molar concentration of lithium metal element in a lithium zinc (LiZnO) thin film. As an excellent result compared to the zinc (ZnO) thin film it can be seen that the effect is lower than 350 ℃.

Table 10

Lithium doping mol ratio	0%	0.5%	One%	2%
Mobility (cm 2 / Vs)	1.87	2.34	3.22	2.94
Threshold Voltage (Vth) (V)	11.41	8.95	11.28	12.09
On / off ratio	10 7	10 7	10 7	10 7

Example: 7. Lilium  And zirconium doping High performance  High Stability Zirconium Oxide, Lithium Zinc ZrLiZnO ) Fabrication of Semiconductor Thin Films

Zinc hydroxide (Zn (OH) ₂ ), zirconium hydroxide (Zr (OH) ₄ , Lithium hydroxide (Li (OH)) were used as starting materials. Since these precursors are basic in solubility, zinc hydroxide was dissolved in aqueous ammonia solution. Afterwards, zirconium hydroxide was dissolved to further improve stability, and lithium hydroxide was dissolved to improve performance.The molar ratios of zinc, zirconium, and lithium (atomic ratios) were determined by the number of moles of zinc precursors of 100. The molar number was 1 and the molar number of the lithium precursor was 0.5, that is, the molar ratio (atomic ratio) of zinc, zirconium, and lithium was set to 1: 0.01: 0.005.

Thereafter, the mixture was stirred at room temperature for 12 hours to prepare a semiconducting solution. The substrate was processed in the same manner as in Example 4. The solution was spin coated onto a substrate to prepare a thin film, and then heat-treated using a hot plate. Dehydration of zinc hydroxide occurs at about 120 ° C, dehydration at about 300 ° C for lithium hydroxide, and dehydration at about 250 ° C for zirconium hydroxide. It is possible. The addition of lithium and zirconium hydroxides makes it possible to realize oxide thin film transistors having superior semiconductor performance and high stability at the same temperature than semiconductors manufactured using only pure zinc hydroxide.

Bottom gate / top contact using a lithium zinc oxide (ZrLiZnO) thin film obtained after heat treatment at 350 ° C, 300 ° C and 250 ° C to confirm the effect of lithium hydroxide and zirconium hydroxide addition at low temperature process A thin film transistor having a structure was formed.

16A through 16B illustrate transfer curves of zirconium oxide and zirconium zinc (ZrLiZnO) thin films formed in Example 7 according to the addition of zirconium and lithium metal elements, according to heat treatment temperature (FIG. 16a: 350 ° C. : 300 ° C. 16C 250 ° C.) Graph. Each graph is spin-coated Zn (OH) ₂ , Li (OH), Zr (OH) ₄ solution dissolved in ammonia water and heat-treated for 2 hours at each temperature using a hot plate, and then V _g from -40V to 40V. While changing, V _d is a measurement of the transfer characteristics while maintaining a constant value of 20 V. Specific device characteristic values are shown in Table 11 below.

Table 11

	Heat treatment temperature	Mobility (cm 2 / Vs)	Threshold Voltage V th (V)	Blink Ratio On / off ratio
ZnO	350 ℃	2.08	3.7	10 7
ZnO	300 ℃	1.87	11.41	10 7
ZnO	250 ℃	0.89	12.4	10 7
ZrLiZnO	350 ℃	5.69	1.7	10 7
ZrLiZnO	300 ℃	3.2	8.7	10 7
ZrLiZnO	250 ℃	2.87	9.8	10 7

According to this performance measurement, the mobility of zirconium and lithium zinc (LiZnO) thin film transistors heat treated at 350 ° C is very good as 10.5 cm ² / Vs, and the operating voltage is 1.2 V and the flashing ratio is 10 ⁸ . Characteristics. Example 4 When the zirconium metal ions described above did not show a slight decrease in mobility, the results showed that the device performance increased as compared with the pure zinc oxide semiconductor as lithium ions were added. In the case of zirconium and lithium zinc (LiZnO) thin film transistors heat-treated at 300 ° C, the deterioration in device performance due to the addition of zirconium metal ions is compensated by the addition of lithium metal ions, so that the device performance is improved compared to pure zinc oxide semiconductors. It can be confirmed that the degree of performance improvement is maintained compared to 350 ℃.

In addition, the gate voltage is applied to the ZnO semiconductor film made in Example 1 and the LiZrZnO composition made by adding Li and Zr elements made in Example 7 for 500 seconds to change the device performance according to the bias stress. 17A (350 ° C), 17B (300 ° C), and 17C (250 ° C), respectively. Table 12 is a table showing the amount of change in the threshold voltage. In the case of the YZnO thin film, unlike ZnO, even when bias stress is applied, it can be seen that the value of the threshold voltage shows little change.

Table 12

	ZnO	ZrLiZnO	ZnO	ZrLiZnO
Heat treatment temperature	350 ℃	350 ℃	300 ℃	300 ℃
Threshold Voltage Change	~ 12V	~ 4.1 V	~ 12.6 V	~ 6.1V

In the case of LiZrZnO thin film heat-treated at 350 ° C containing lithium and zirconium, the threshold voltage change does not increase as much as about 4.1V, but the ZnO thin film containing lithium or zirconium is about 12V due to the bias stress. It can be seen that it shows an unstable state such as a large increase in the threshold voltage. This trend can be seen that maintained even in the case of the LiZrZnO thin film heat-treated at 300 ℃.

The metal oxide thin film according to the present invention is a thin film transistor of various structures, for example, bottom gate-bottom contact, bottom gate-top contact, top gate-top contact It can be applied to the structure of gate-top contact, top gate-bottom contact, etc., and can also be used in various electronic devices, optical devices, sensors, etc. using thin films.

The present invention has been exemplarily described through the embodiments, but the present invention is not limited to the specific embodiments as described above, and the invention is in various forms within the scope of the technical idea presented in the present invention, specifically, the claims. It may be modified, changed or improved.

The present invention relates to a metal oxide thin film and a method for manufacturing the same, and in particular, to realize high mobility by low temperature heat treatment, excellent stability of operation and reproducibility when applying an electric field, and transparent electronic device at 350 ° C. or less to be applicable to a plastic substrate. We propose a solution for a metal oxide thin film, a metal oxide thin film transistor formed using the same, and a method of manufacturing the same.

The present invention can be applied to large area glass substrates, plastic substrates, flexible substrates and the like.

Claims (34)

1. Metal hydroxides; And,

   An acid group titrant for controlling the solubility of the metal hydroxide,

   The concentration of the metal hydroxide is an oxide thin film composition, characterized in that 0.05 to 40 mol / L.
2. The method of claim 1,

   The metal hydroxide may be aluminum hydroxide (Al (OH) ₃ ), zinc hydroxide (Zn (OH) ₂ ), gallium hydroxide (Ga (OH) ₃ ), indium hydroxide (In (OH) ₃ ), tin hydroxide (Sn (OH) ₄ ) and a first metal hydroxide selected from the combination of these materials.
3. The method of claim 2,

   The metal hydroxide may be yttrium hydroxide (Y (OH) ₃ ), zirconium hydroxide (Zr (OH) ₄ ), hafnium hydroxide (Hf (OH) ₄ ), scandium hydroxide (Sc (OH) ₃ ), gallium to improve bias stability. A composition for an oxide thin film, further comprising a second metal hydroxide selected from hydroxide (Ga (OH) ₃ ), lanthanum hydroxide (La (OH) ₃ ), and a combination thereof.
4. The method of claim 3,

   The first metal hydroxide and the second metal hydroxide is an oxide thin film composition, characterized in that it is included in a molar ratio of 1: 0 ~ 0.2.
5. The method of claim 4, wherein

   The first metal hydroxide and the second metal hydroxide is an oxide thin film composition, characterized in that contained in a molar ratio of 1: 0 ~ 0.02.
6. The method of claim 3,

   The acid salt titrant is selected from ammonia, tetramethyl ammonium hydroxide, methylamine, urea, acetic acid, hydrochloric acid, nitric acid, sulfuric acid, hydrogen peroxide and combinations thereof.
7. The method of claim 3,

   The metal hydroxide further comprises a third metal hydroxide selected from lithium hydroxide (Li (OH), titanium oxide (Ti (OH)), and combinations thereof for improved performance at low temperatures. Composition.
8. The method of claim 7, wherein

   The first metal hydroxide, the second metal hydroxide and the third metal hydroxide is a composition for an oxide thin film, characterized in that contained in a molar ratio of 1: 0 to 0.2: 0 to 0.2.
9. The method of claim 8,

   The first metal hydroxide is zinc hydroxide (Zn (OH) ₂ ) composition for the oxide thin film, characterized in that.
10. The method of claim 8,

    The acid salt titrant is selected from ammonia, tetramethyl ammonium hydroxide, methylamine, urea, acetic acid, hydrochloric acid, nitric acid, sulfuric acid, hydrogen peroxide and combinations thereof.
11. The method of claim 2,

    The acid salt titrant is selected from ammonia, tetramethyl ammonium hydroxide, methylamine, urea, acetic acid, hydrochloric acid, nitric acid, sulfuric acid, hydrogen peroxide and combinations thereof.
12. The method of claim 2,

    The metal hydroxide further comprises a third metal hydroxide selected from lithium hydroxide (Li (OH), titanium oxide (Ti (OH)), and combinations thereof for improved performance at low temperatures. Composition.
13. The method of claim 11,

    The first metal hydroxide and the third metal hydroxide is an oxide thin film composition, characterized in that contained in a molar ratio of 1: 0 ~ 0.2.
14. The method of claim 13,

    And the first metal hydroxide and the third metal hydroxide are included in a molar ratio of 1: 0 to 0.02.
15. The method of claim 11,

    The acid salt titrant is selected from ammonia, tetramethyl ammonium hydroxide, methylamine, urea, acetic acid, hydrochloric acid, nitric acid, sulfuric acid, hydrogen peroxide and combinations thereof.
16. The method of claim 1,

    The acid salt titrant is selected from ammonia, tetramethyl ammonium hydroxide, methylamine, urea, acetic acid, hydrochloric acid, nitric acid, sulfuric acid, hydrogen peroxide and combinations thereof.
17. The method of claim 1,

    The metal hydroxide is zirconium hydroxide (Zr (OH) _4), hafnium hydroxide (Hf (OH) _4), aluminum hydroxide (Al (OH) _3), yttrium hydroxide (Y (OH) _3), gadolinium hydroxide (Gd ( OH) ₃ ), lanthanum hydroxide (La (OH) ₃ ) and a composition for an oxide thin film comprising a fourth metal hydroxide selected from a combination thereof.
18. The method of claim 17,

    The acid salt titrant is selected from ammonia, tetramethyl ammonium hydroxide, methylamine, urea, acetic acid, hydrochloric acid, nitric acid, sulfuric acid, hydrogen peroxide and combinations thereof.
19. The method of claim 1,

    The metal hydroxide is selected from zinc hydroxide (Zn (OH) ₂ ), indium hydroxide (In (OH) ₃ ), tin hydroxide (Sn (OH) ₄ ), aluminum hydroxide (Al (OH) ₃ ) and combinations thereof An oxide thin film composition comprising a fifth metal hydroxide.
20. Applying the composition of claim 1 to a substrate; And

    Method of forming an oxide thin film comprising the step of heat-treating the substrate to which the composition is applied.
21. The method of claim 20,

    The heat treatment is a method for forming an oxide thin film, characterized in that carried out in a vacuum or reducing atmosphere in the range of 100 ℃ ~ 350 ℃.
22. The method of claim 20,

    And the substrate is a flexible substrate, a transparent substrate, or a glass substrate.
23. The method of claim 20,

    And the heat treatment is performed by using a hot plate, a convection oven, a box, or a microwave.
24. Metal oxide thin film formed by apply | coating the composition of Claim 1 to a board | substrate, and heat-processing.
25. The method of claim 24,

    The substrate is a metal oxide thin film, characterized in that the flexible substrate, a transparent substrate or a glass substrate.
26. The method of claim 24,

    The metal oxide thin film is used as an active layer of a thin film transistor.
27. Aluminum hydroxide (Al (OH) ₃ ), zinc hydroxide (Zn (OH) ₂ ), gallium hydroxide (Ga (OH) ₃ ), indium hydroxide (In (OH) ₃ ), tin hydroxide (Sn (OH) ₄ ) and A first metal hydroxide selected from materials combining these;

    Yttrium hydroxide (Y (OH) ₃ ), zirconium hydroxide (Zr (OH) ₄ ), hafnium hydroxide (Hf (OH) ₄ ), scandium hydroxide (Sc (OH) ₃ ), gallium hydroxide (Ga (OH) ₃ ), Lanthanum hydroxide (La (OH) ₃ ) and a second metal hydroxide selected from combinations thereof;

    A third metal hydroxide selected from lithium hydroxide (Li (OH), titanium oxide (Ti (OH)), and combinations thereof; and

    An acid group titrant for controlling the solubility of the metal hydroxides,

    The total concentration of the metal hydroxide is an oxide thin film composition, characterized in that 0.05 ~ 10 mol / L.
28. The method of claim 27,

    The first metal hydroxide, the second metal hydroxide and the third metal hydroxide is a composition for an oxide thin film is contained in a molar ratio of 1: 0 to 0.2: 0 to 0.2.
29. The method of claim 28,

    Wherein the first metal hydroxide, the second metal hydroxide, and the third metal hydroxide are included in a molar ratio of 1: 0 to 0.02: 0 to 0.02.
30. The method of claim 27,

    The acid salt titrant is selected from ammonia, tetramethyl ammonium hydroxide, methylamine, urea, acetic acid, hydrochloric acid, nitric acid, sulfuric acid, hydrogen peroxide and combinations thereof.
31. The method of claim 30,

    The acid salt titrant is an oxide thin film composition, characterized in that contained in a concentration of 0.05 to 40 mol / L.
32. A first metal selected from aluminum, zinc, gallium, indium, tin, and combinations thereof;

    A second metal selected from yttrium, zirconium, hafnium, scandium, gallium, lanthanum, and combinations thereof;

    A third metal selected from lithium, titanium, and combinations thereof;

    The first metal, the second metal and the third metal is a metal oxide thin film, characterized in that included in the ratio of the number of atoms of 1: 0 to 0.2: 0 to 0.2.
33. 33. The method of claim 32,

    The first metal, the second metal and the third metal is a metal oxide thin film, characterized in that included in the ratio of the number of atoms of 1: 0 ~ 0.02: 0 ~ 00.2.
34. Applying the composition of claim 7 to a substrate and performing heat treatment to form a semiconductor thin film;

    Applying the composition of claim 17 on the semiconductor thin film to form an insulating thin film; And

    A method of forming a semiconductor device, comprising the step of applying the composition of claim 19 on the insulating film and heat treatment to form a conductive thin film.

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