KR101582942B1 - Solution for forming oxide semiconductor - Google Patents

Abstract

A solution for preparing an oxide thin film according to an embodiment of the present invention is a solution of zinc oxide (ZnO) containing at least one of a first compound containing tin, a second compound containing gallium, and a third compound containing indium, A solution stabilizer for stabilizing the solution, and an additive for adjusting the viscosity of the solution.

 Oxide semiconductor, transistor, precursor solution, zinc oxide

Description

SOLUTION FOR FORMING OXIDE SEMICONDUCTOR [0002]

The present invention relates to a solution for producing an oxide semiconductor.

BACKGROUND ART [0002] Thin film transistors (TFTs) have been used in various fields, and in particular, liquid crystal displays (LCDs), organic light emitting diode displays (OLED displays) and electrophoretic displays display and the like are used as switching and driving elements.

The thin film transistor includes a gate electrode connected to a gate line for transmitting a scan signal, a source electrode connected to a data line for transmitting a signal to be applied to the pixel electrode, a drain electrode facing the source electrode, And includes an electrically connected semiconductor.

Of these, semiconductors are important factors in determining the characteristics of thin film transistors. Silicon (Si) is the most commonly used semiconductor. Silicon is divided into amorphous silicon and polycrystalline silicon depending on the crystal form. Amorphous silicon has a simple manufacturing process and low charge mobility, which limits the fabrication of high performance thin film transistors. Polycrystalline silicon has a high charge mobility, Step is required and the manufacturing cost and process are complicated.

An oxide semiconductor may be used to complement the amorphous silicon and the polycrystalline silicon. The oxide semiconductor does not require a separate process for crystallizing the semiconductor, and when formed by vacuum deposition, it can increase the charge mobility according to the deposition conditions. However, vacuum deposition has a complicated manufacturing process, has a large manufacturing cost, and is limited in application to a large-area display device.

Accordingly, it is an object of the present invention to provide a solution composition for the production of an oxide semiconductor which can simplify the manufacturing process, lower the manufacturing cost, and improve the characteristics of the thin film transistor.

A solution for preparing an oxide thin film according to an embodiment of the present invention is a solution of zinc oxide (ZnO) containing at least one of a first compound containing tin, a second compound containing gallium, and a third compound containing indium, A solution stabilizer for stabilizing the solution, and an additive for adjusting the viscosity of the solution.

The additive may be formamide, and the surface tension of the solution may be 40 mN / m or more and 70 mN / M or less.

The formamide may comprise from 100 to 300% of the combined volume of zinc oxide solution and solution stabilizer.

The contact angle of the droplet and the substrate after dropping the droplet onto the substrate may be 10 ° to 50 °.

The solvent of the solution may be selected from the group consisting of 2-methoxyethanol, isopropanol, ethanol, ethylene glycol, butanediol, 1-betanediol, 2-butanediol).

The zinc oxide solution may be any one of GIZO, ZnSnO, and GaSnZnO.

The GIZO solution may contain a molar concentration of gallium: indium: zinc of 0.3 to 1.1: 1.1: 0.9.

The solution stabilizing agent may be monoethanolamine.

Wherein the first compound comprises at least one selected from the group consisting of gallium salt, zinc hydroxide, gallium alkoxide and hydrates thereof, and the second compound comprises at least one selected from indium salt, indium hydroxide, indium alkoxide and hydrates thereof, The third compound may include at least one selected from tin salts, indium hydroxide, tin alkoxide, and hydrates thereof.

The first compound may comprise zinc acetate hydrate and the second compound may comprise indium acetylacetonate.

The solution may be prepared by a sol-gel method.

The oxide semiconductor according to an embodiment of the present invention can be formed in a solution form, thereby simplifying the manufacturing process and lowering the manufacturing cost. In addition, since a thin film transistor can be formed by an inkjet method using an oxide semiconductor solution, the manufacturing process of the thin film transistor can be simplified.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily carry out the present invention. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein.

In the drawings, the thickness is enlarged to clearly represent the layers and regions. Like parts are designated with like reference numerals throughout the specification. Whenever a portion of a layer, film, region, plate, or the like is referred to as being "on" another portion, it includes not only the case where it is "directly on" another portion, but also the case where there is another portion in between. Conversely, when a part is "directly over" another part, it means that there is no other part in the middle.

Hereinafter, a solution composition according to an embodiment of the present invention will be described.

A solution composition according to an embodiment of the present invention is a precursor solution used for forming an oxide semiconductor thin film.

The precursor solution is a solution containing a compound containing zinc (Zn) (hereinafter referred to as a zinc-containing compound), a compound containing gallium (Ga) (hereinafter referred to as a gallium-containing compound) (Hereinafter referred to as "tin-containing compound") and a compound containing indium (In) (hereinafter referred to as "indium-containing compound").

Various combinations of these compounds can form various precursor solutions. For example, GIZO, ZTO (ZnSnO), and GSZO (GaSnZnO) solutions can be prepared. When a thin film is formed using these precursor solutions, an oxide thin film having semiconductor characteristics can be formed.

The zinc-containing compound may be at least one selected from zinc nitrate, zinc salt, zinc hydroxide, zinc alkoxide and hydrates thereof, but is not limited thereto. The salts may be, for example, acetate, carbonyl, carbonate, nitrate, sulfate, phosphate and halide. Examples of the zinc-containing compound include zinc acetate (Zn (CH ₃ COO) ₂ ), zinc nitrate, zinc acetylacetonate, zinc chloride and their hydrates .

The indium-containing compound may be at least one selected from the group consisting of indium nitride, indium salt, indium hydroxide, indium alkoxide and hydrates thereof, but is not limited thereto. Examples of the indium-containing compound include indium acetyl acetonate, indium acetate, indium chloride, indium isopropoxide and hydrates thereof.

The gallium-containing compound may be at least one selected from gallium nitride, gallium salt, gallium hydroxide, gallium alkoxide and hydrates thereof, but is not limited thereto. Examples of the gallium-containing compound include gallium acetyl acetonate, gallium acetate, gallium chloride, gallium isopropoxide and hydrates thereof. Tin nitride, tin salt, tin hydroxide, tin alkoxide, and hydrates thereof, but is not limited thereto. Examples of tin-containing compounds include tin acetyl acetonate, tin acetate, tin chloride, tin isopropoxide and their hydrates. The precursor solution May further comprise a solution stabilizer.

The solution stabilizer may include at least one selected from the group consisting of an alcohol amine compound, an alkylammonium hydroxide compound, an alkylamine compound, a ketone compound, an acid compound, a base compound and deionized water, and examples thereof include monoethanolamine, di But are not limited to, ethanolamine, triethanolamine, monoisopropylamine, N, N-methylethanolamine, aminoethylethanolamine, diethyleneglycolamine, 2- (aminoethoxy) ethanol, Nt-butylethanolamine, , At least one selected from tetramethylammonium hydroxide, methylamine, ethylamine, acetylacetone, hydrochloric acid, nitric acid, sulfuric acid, acetic acid, ammonium hydroxide, potassium hydroxide and sodium hydroxide.

The solution stabilizer may be included in the precursor solution to increase the solubility of other components and thus form a uniform thin film. The content of the solution stabilizer may vary depending on the kind and content of the other components, but may be about 0.01 to 30% by weight based on the total amount of the precursor solution. When the solution stabilizer is contained in the above range, the solubility and the thin film coating property can be enhanced.

The solution stabilizing agent may be added to each component solution of the zinc-containing compound, the indium-containing compound, the gallium-containing compound and the tin-containing compound, or may be added after mixing each solution.

Further, the precursor solution further includes an additive for adjusting the surface tension of the solution. The additive may be a compound having a surface tension higher than the surface tension of the precursor solution in the absence of the additive and may be selected as a compound that does not inhibit the characteristics of the oxide semiconductor. For example, the surface tension of the precursor solution can be controlled by adding formamide (FA) having a surface tension of 59.1 nM / m. At this time, formamide can be added so as to have a volume ratio of the formamide of 1: 1 to 1: 3 with a semiconductor solution containing a salt containing compound, an indium containing compound, a gallium containing compound and a tin containing compound.

The zinc-containing compound, the indium-containing compound, the gallium-containing compound and the tin-containing compound, the solution stabilizer and the additives described above are mixed together in a solvent.

The solvent is not particularly limited as long as it can dissolve the above-mentioned components, and examples thereof include deionized water, methanol, ethanol, propanol, isopropanol, 2- methoxyethanol, 2- ethoxyethanol, 2- But are not limited to, ethanol, methyl cellosolve, ethyl cellosolve, diethylene glycol methyl ether, diethylene glycol ethyl ether, dipropylene glycol methyl ether, toluene, xylene, hexane, heptane, octane, ethyl acetate, butyl acetate, diethylene glycol dimethyl Propylene glycol methyl ether, propylene glycol propyl ether, methyl cellosolve acetate, ethyl cellosolve acetate, ethyl cellosolve acetate, methyl cellosolve acetate, ethyl cellosolve acetate, ethyl cellosolve acetate, ethyl cellosolve acetate, Diethylene glycol methyl acetate, diethylene glycol ethyl acetate, acetone, methyl isobu N-dimethylacetamide (DMAc), N-methyl-2-pyrrolidone,? -Butyrolactone, diethyl ether, ethylene glycol dimethyl ether, diglycidyl ether, Lime, tetrahydrofuran, acetylacetone, and acetonitrile.

The solvent may be included in the balance of the total content of the precursor solution excluding the components described above.

Hereinafter, a method for producing the GIZO precursor solution in the precursor solution described above will be described in detail.

The GIZO solution can be prepared by a sol-gel method after mixing gallium, indium and gallium at a mole ratio of X: 1.1: 0.9 (X = 0.3-1.1).

FIG. 1 is a flowchart sequentially illustrating a method of producing a precursor solution according to an embodiment of the present invention.

Referring to FIG. 1, a solvent containing a solution stabilizer is prepared (S1). Ethanolamine is used as the stabilizer, and 2-methoxyethanol is used as the solvent. The zinc-containing compound, for example zinc acetate, is added while stirring the prepared solvent (S2). At this time, zinc acetate can be mixed by heating to a certain temperature.

Next, gallium acetate is added (S3) while stirring the solvent, and indium acetate is added sequentially (S4). At this time, stirring can be carried out at room temperature for 10 minutes to 12 hours.

Finally, formamide is added (S5) to complete the precursor solution (S6). The amount of formamide is adjusted so that the surface tension of the precursor solution has a value of 40 to 70 mN / m.

Another embodiment, GSZO, can be prepared by sol-gel method after mixing molar concentration of Ga: Sn: Zn at a ratio of 0.5: 2.5: 7. ZTO can be prepared by sol-gel method after mixing a molar concentration of Zn: Sn of 7: 3 and mixing ZTO and formamide at a volume ratio of 1: 2. And FIGS. 3 to 5 are photographs showing surface contact angles of a precursor solution according to an embodiment of the present invention, wherein formamide was used as an additive.

When the precursor solution according to the prior art is dropped on the substrate, it can be seen that the contact angle between the substrate and the solution droplet is zero as shown in FIG. However, when the precursor solution according to the embodiment of the present invention containing the additive at a ratio of vol. 100%, vol. 200%, vol. 300% is dropped on the substrate, the substrate and the solution droplet It can be seen that the contact angles are 10 °, 18 ° and 27 °, respectively.

As shown in FIG. 2, if the droplet spreads on the substrate, it is effective for spin coating, but is unsuitable for use in an inkjet method. However, by increasing the surface tension of the solution by adding an additive as in the embodiment of the present invention, it is easy to form a uniform pattern without spreading the solution on the substrate, It becomes.

FIG. 6 is a photograph of a linear pattern formed by an inkjet method using a precursor solution according to the prior art, and FIGS. 7 to 9 are photographs of forming a linear pattern by an inkjet method using a precursor solution according to an embodiment of the present invention .

As shown in FIG. 6, when a pattern is formed at intervals of 300 μm with a conventional precursor solution, it is merged with a neighboring pattern, and even when a semiconductor is formed at an interval of 500 μm, it spreads widely on the substrate.

However, as shown in FIGS. 7 to 9, when a precursor solution according to an embodiment of the present invention is used, a good linear pattern can be obtained except for the case where the semiconductor is formed at intervals of 300 μm by including the additive in vol. have.

As described above, the precursor solution of the present invention can easily form a pattern on a substrate by an inkjet printing method by controlling the surface tension with an additive.

The transistor formed using the precursor solution according to the present invention described above will be described.

FIG. 10 is a cross-sectional view of a transistor according to an embodiment of the present invention, and FIGS. 11 and 12 are sectional views sequentially illustrating a method of manufacturing the transistor of FIG.

10, a transistor according to an embodiment of the present invention includes a gate electrode 124 formed on a substrate 110, and a gate insulating layer 140 covering the entire surface of the substrate.

On the gate insulating film 140, a source electrode 173 and a drain electrode 175 are formed. An oxide semiconductor body 154 is formed on the source electrode 173 and the drain electrode 175. The oxide semiconductor 154 is made of GIZO and forms a channel between the source electrode 173 and the drain electrode 175.

Referring to FIG. 11, a conductive layer is deposited on a substrate 110, and then a gate electrode 124 is formed by photolithography.

Next, referring to FIG. 12, a gate insulating film 140 is formed by laminating silicon oxide (SiO ₂ ), silicon nitride (SiN _x ), or an organic insulating film on the gate electrode 124.

Then, a metal is deposited on the gate insulating layer 140 and then patterned to form a source electrode 173 and a drain electrode 175.

Referring to FIG. 10, an oxide semiconductor 154 is formed on the source electrode 173 and the drain electrode 175. The oxide semiconductor 154 is formed by an inkjet method using a GIZO precursor solution. In the embodiment of the present invention, the precursor solution is directly dropped onto the substrate, but the precursor solution can be formed by dropping the precursor solution after forming the partition on the substrate.

13 and 14 are graphs showing the electrical characteristics of the transistor of FIG.

Referring to FIG. 13, when Vd is 20 V, Id increases as Vg increases, and the transistor turns on. 14, when the voltage Vg is constant at 0V, 10V, 20V, 30V, and 40V, the voltage Vd increases with time and is stabilized at a constant Id.

At this time, the mobility of the transistor is 1.7 × 10 ^-2 cm 2 / Vs, the Vth is 2.88 V, the on current is 1.0 × 10 ^-6 A and the off current is <1.0 × 10 ^-12 A, and the on / off ratio is 2.1 x 10 &lt; ⁶ &gt;.

As described above, since the oxide semiconductor according to the embodiment of the present invention can be formed in a solution form and can have a constant surface tension, a semiconductor can be formed by an inkjet printing method, thereby simplifying the manufacturing process of the thin film transistor and lowering the manufacturing cost .

In the above embodiments, application of an oxide semiconductor to a transistor has been exemplarily described, but the present invention is not limited to this, and the present invention can be similarly applied to any device requiring a semiconductor thin film. Although the transistors of the bottom gate structure have been exemplarily described in the above embodiments, the present invention is not limited thereto, and the present invention can be similarly applied to transistors of any structure such as top gate structure transistors.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, And falls within the scope of the invention.

FIG. 1 is a flowchart sequentially illustrating a method of producing a precursor solution according to an embodiment of the present invention.

FIG. 2 is a photograph showing the surface contact angle of the precursor solution according to the prior art, and FIGS. 3 to 5 are photographs showing the surface contact angle of the precursor solution according to an embodiment of the present invention.

6 is a photograph showing a linear pattern formed by an inkjet method using a precursor solution according to the prior art.

7 to 9 are photographs showing a linear pattern formed by an inkjet method using a precursor solution according to an embodiment of the present invention.

10 is a cross-sectional view of a transistor according to an embodiment of the present invention.

11 and 12 are sectional views sequentially showing a method of manufacturing the transistor of FIG.

13 and 14 are graphs showing the electrical characteristics of the transistor of FIG.

<Reference numerals of main components>

110: substrate 124: gate electrode

140: gate insulating film 154: semiconductor

173: source electrode 175: drain electrode

Claims (12)

A zinc oxide (ZnO) solution containing at least one of a first compound containing tin, a second compound containing gallium, and a third compound containing indium, A solution stabilizer for stabilizing the solution, And formamides for controlling the viscosity of the solution, Wherein the formamide comprises 100 to 300% of the sum of the zinc oxide solution and the solution stabilizer. delete The method of claim 1, Wherein the solution has a surface tension of 40 mN / m or more and 70 mN / M or less. delete The method of claim 1, Wherein the droplet of the solution is dropped onto the substrate and the contact angle of the droplet and the substrate is 10 ° to 50 °. The method of claim 1, The solvent of the solution may be selected from the group consisting of 2-methoxyethanol, isopropanol, ethanol, ethylene glycol, butanediol, 1-betanediol, (2-butanediol). The method of claim 1, The zinc oxide solution is any one of GIZO, ZnSnO, and GaSnZnO. 8. The method of claim 7, Wherein the GIZO solution contains a molar concentration of gallium: indium: zinc in a ratio of 0.3 to 1.1: 1.1: 0.9. The method of claim 1, Wherein the solution stabilizer is MonoEthaolamine. The method of claim 1, Wherein the first compound comprises at least one selected from a gallium salt, zinc hydroxide, gallium alkoxide and hydrates thereof, Wherein the second compound comprises at least one selected from an indium salt, indium hydroxide, indium alkoxide and hydrates thereof, Wherein the third compound comprises at least one selected from tin salts, indium hydroxide, tin alkoxide and hydrates thereof. 11. The method of claim 10, Wherein the first compound comprises zinc acetate hydrate, Wherein the second compound comprises indium acetylacetonate Solution for preparing oxide thin film. The method of claim 1, The solution is prepared by a sol-gel method.

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