KR100663714B1 - Method of forming a composition for synthesizing ito and method of patterning ito synthesized from said composition - Google Patents

Abstract

A preparation method of ITO(indium tin oxide) synthesis composition is provided to apply the composition to ITO synthesis and ITO patterning processes and to derive formation of nano-scale structure through the ITO patterning and use of electron beam by using indium tert-butoxide and tin tert-butoxide as a precursor of the composition. The composition is produced by the steps of: forming first solution by mixing indium tert-butoxide, 1-benzoylacetone and methanol; forming second solution by mixing tin tert-butoxide, 1-benzolacetone and methanol; and blending the first solution and the second solution together. The first solution is obtained by admixing indium tert-butoxide and 1-benzoylacetone in 1:1 ratio, then adding methanol to the admixture. The second solution is obtained by admixing tin tert-butoxide and 1-benzoylacetone in 1:1 ration, then adding methanol to the admixture. All of the steps are conducted in a glove box with relative moisture of less than 5%.

Description

Method of forming a composition for synthesizing ITO and method of patterning ITO synthesized from said composition}

1 to 3 schematically illustrate an ITO patterning method according to an embodiment of the present invention.

* Description of symbols on the main parts of the drawings *

1: substrate 2: ITO film

3: electron beam

The present invention relates to a method for forming a composition for synthesizing indium tin oxide (ITO) and a method for patterning synthesized ITO from the composition. In particular, the present invention relates to a method of patterning ITO synthesized from the composition using an electron beam.

Transparent electrodes are required in applications such as liquid crystal display devices, plasma display panels, field emission display devices, flat panel display devices such as electroluminescent devices, solar cells, and transparent hot wires. Tin oxide (SnO ₂ ), zinc oxide (ZnO) and the like are also used as the transparent electrode material, but the most representative material is Indium Tin Oxide (ITO). This is because it is large and its electrical conductivity is relatively large.

In the prior art, ITO having SnO ₂ added to In ₂ O ₃ (for example, In ₂ O ₃ : SnO ₂ = 90: 10 to 95: 5) is widely used, but ITO synthesized in this manner Since the sensitivity of the electron beam is relatively low, it takes a long time to pattern a conventional ITO film with the electron beam, and there is a limit to forming a nanoscale pattern.

Meanwhile, in the conventional ITO patterning method according to the related art, after depositing an ITO film on a transparent quartz substrate, a photoresist is applied on the ITO film and a photoresist pattern is formed by using photolithography. Subsequently, the ITO pattern is patterned by a wet etching method using the photoresist pattern as an etching mask, and the ITO pattern is completed by removing the photoresist pattern on the patterned ITO film.

In such a patterning method, since the adhesion between the photoresist and the ITO film is not good, the photoresist film is etched together during the wet etching process on the ITO film, so that the interface between the photoresist and the ITO becomes unstable, thereby forming a desired ITO film pattern. A portion of the photoresist is stripped off before it is. This phenomenon occurs because the acid-based ITO etching solution etches the organic photoresist film, and thus, the desired ITO pattern formation cannot be obtained, and the peeled photoresist contaminates the etching bath.

Commonly used methods of etching an ITO film include wet etching, dry etching, etching by laser irradiation, and the like. Wet etching has advantages such as simplicity of process and high through-put. However, as described above, the problem of adhesion between photoresist and ITO film, electrochemical corrosion by wet etching solution and developer, etc. As a result, there is a problem in that the formation of nanoscale fine patterns is limited. In the case of dry etching, it is possible to form a fine pattern of 5 μm or less, but there is a problem in that the through-put is low and a polymer is formed. In addition, in the case of etching by laser irradiation, through-put has been improved enough to be applied to a recent production process, and a pattern having a fine scale of about 1 μm can be formed, but the ITO pattern has a simple matrix type stripe. It has the disadvantage of being effective only for STN.

Several ITO pattern methods have been developed to address these shortcomings.

According to one of the methods, the step of applying a photoresist over the entire surface of the substrate glass; Exposing the photoresist using a mask having a desired pattern; Developing the exposed photoresist; Coating an ITO film on the photoresist having the desired pattern by the developing step; There is provided a method of forming an ITO electrode pattern comprising a stripping step of forming a predetermined pattern of an ITO film on the substrate glass by removing the photoresist having the desired pattern and an ITO film coated thereon. Such an ITO film pattern forming method has an advantage in that an etching process that is difficult to work is excluded, but a relatively large number of process steps are required to form an ITO film pattern, and there is a problem in that there is a certain limit in forming a nanoscale pattern.

According to another method, an ITO pattern is formed on a substrate glass by placing a substrate glass and a mask having a desired pattern inside a chamber kept in vacuum and depositing ITO on the substrate glass by sputtering. According to the above method, the existing photoresist coating process, exposure process, etching process, etc. can be removed, thereby shortening the process. However, there is a limit in depositing an ITO film on a large-area substrate, and there is a problem in that a high cost is required for manufacturing a target. In addition, there is still a problem that a relatively large number of process steps are required for the ITO film pattern and microscale pattern is possible, but there is a limit in forming a nanoscale pattern.

Accordingly, an object of the present invention is to provide a composition for synthesizing ITO, and a method of forming the same, having improved sensitivity to an electron beam.

It is also an object of the present invention to solve the limitations of the conventional ITO pattern forming method described above, and to provide an ITO pattern forming method capable of reducing the process steps required for patterning ITO and patterning on a nano scale. .

In order to achieve this object, the composition forming method for synthesizing ITO according to the present invention is a mixture of indium tert-butoxide, 1-benzoylacetone (benzoylacetone) and methanol to prepare a first solution Forming; Mixing tin tert-butoxide, 1-benzoylacetone and methanol to form a second solution; And mixing the first solution and the second solution. In the final mixture of the first solution and the second solution, the molar ratio of tin tert-butoxide: indium tert butoxide: 1-benzoylacetone is preferably 1: 1: 2. Suitable amounts may be used for preparing the methanol used in the first solution and the second solution in a sol state.

The ITO synthetic composition formed according to the present invention is improved sensitivity to the electron beam, when through the patterning using the electron beam is improved through-put and can form a nanoscale fine pattern.

According to an embodiment of the present invention, the first solution forming step includes mixing a 1: 1 molar ratio of indium tert butoxide and 1-benzoylacetone, and 2 ml of methanol, wherein the second solution The forming step is characterized by mixing the tin tert-butoxide and 1-benzoylacetone in a molar ratio of 1: 1, and 2 ml of methanol.

In addition, according to another embodiment of the present invention, the first solution mixing step, the second solution mixing step, and the first solution and the second solution mixing step is a glove box (glove) of 5% or less relative humidity box).

On the other hand, ITO patterning method according to the invention comprises the steps of providing a substrate; Indium tert-butoxide, 1-benzoylacetone and methanol are mixed to form a first solution, tin tert-butoxide, 1-benzoylacetone and methanol are mixed to form a second solution, and the first solution And mixing the second solution to form an ITO synthetic composition. Synthesizing an ITO film on the substrate from the ITO synthesis composition; Heat-treating the substrate on which the ITO film is synthesized; Exposing a pattern region of the surface region of the ITO film to an electron beam; And developing the substrate on which the ITO film is formed so that the pattern region of the surface region of the ITO film exposed to the electron beam remains.

According to the ITO patterning method according to the present invention, the etching step, the lift-off step, etc., which are essential in the conventional ITO patterning method, become unnecessary, so that the problems caused by the process step can be eliminated and the process required for patterning the ITO film Through-put can be improved by reducing the level.

According to an embodiment of the present invention, an ITO film is formed on the substrate by spin coating the ITO synthetic composition.

Further, according to another embodiment of the present invention, the thickness of the ITO film is controlled by adding 1-pentanol to the ITO synthetic composition or by changing at least one of the time of spin coating and the speed of spin coating. It is characterized by.

Hereinafter, the present invention will be described in detail with reference to the accompanying examples, but the following examples are merely illustrative and the scope of the present invention is not limited only to the following examples.

Example

The method for forming an ITO pattern according to the present invention is largely divided into a step of forming an ITO synthetic composition and a step of synthesizing and patterning ITO using the composition.

First: ITO synthetic composition formation step

To form the ITO synthetic composition, indium tert butoxide and tin tert-butoxide, 1-benzoylacetone, and methanol were added to a glove box (<5%) with a relative humidity of 5% or less. Put in. Next, indium tert-butoxide and 1-benzoylacetone were mixed in a 1: 1 ratio, and the mixture was mixed with 2 ml of methanol to prepare a first solution. Tin tert-butoxide was also mixed 1: 1 with 1-benzoylacetone and mixed in 2 ml of methanol to prepare a second solution. Finally, the first solution and the second solution were uniformly mixed using a magnetic stirrer for 2 hours, so that the final mixture of the obtained first solution and the second solution was tin tert-butoxide: indium ter The molar ratio of tbutoxide: 1-benzoylacetone was 1: 1: 2. .

Second: ITO formation and patterning step

The silicon substrate 1 was placed in a container containing acetone and cleaned for about 5 minutes by an ultrasonic cleaner. Next, the silicon substrate 1 was cleaned in the order of IPA and ethanol. Next, as shown in FIG. 1, the ITO film 2 was formed by coating the ITO synthetic composition onto the silicon substrate 1 using, for example, a spin coater. The thickness of the coated ITO membrane 2 can be controlled in two ways, the first method being controlled by mixing an appropriate amount of diluent, for example 1-pentanol, and the other method spin coating. The thickness of the ITO film 2 coated on the silicon substrate 1 can be controlled by adjusting the time and speed (RPM). The thickness of the ITO film 2 was measured using an ellipsometer. There is a device called alpha-step, which is a thickness measuring device, but it is not suitable for measurement because the use of this device may damage the ITO film 2 in the sol-gel state. Next, a pattern of the ITO film 2 was directly formed using an electron-beam writer. First, the silicon substrate 1 coated with the ITO film 2 was placed on a heating plate and heat-treated by setting the temperature and time. Subsequently, as shown in FIG. 2, the silicon substrate 1 is placed in an electron beam recorder chamber, a vacuum is extracted, and a desired pattern is designed in a program, and the corresponding pattern of the surface area of the ITO film 2 corresponds to the desired pattern. Only the pattern region was exposed to the electron beam 3. The pattern region of the ITO film 2 exposed to the electron beam 3 becomes structurally stable relative to other regions. After the electron beam exposure step was completed, the silicon substrate 1 was removed from the chamber and developed. The development is much easier compared to commercialized e-beam lithography techniques. As shown in FIG. 3, after dipping the silicon substrate 1 in a container containing acetone and shaking it for a predetermined time, the portion of the ITO film 2 which is not exposed to the electron beam 3 is rinsed with IPA and blown with an inert gas. Only the pattern region of the removed and exposed ITO film 2 remains on the silicon substrate 1.

According to the conventional electron beam lithography technique, a metal deposition process and a lift-off step are additionally required after the developing step, but according to the ITO pattern forming method according to an embodiment of the present invention, the metal deposition process and the lift There is an advantage that the desired ITO film 2 pattern can be formed only by the process up to the developing step without the off step. The thickness and line width of the ITO film 2 pattern are defined from the rotational speed during spin coating and the pattern design during electron beam recording.

Although the present invention has been described with reference to the above embodiments, it is merely illustrative, and those skilled in the art will understand that various modifications and equivalent other embodiments are possible therefrom. . Therefore, the true technical protection scope of the present invention will be defined by the technical spirit of the appended claims.

Since the composition for synthesizing ITO according to the present invention has excellent sensitivity to the electron beam compared to the conventional ITO synthetic composition, when patterning the ITO with the electron beam, the time required for patterning is shortened, thereby increasing through-put and improving sensitivity. This achieves the effect that a finer nanoscale pattern can be formed.

In addition, according to the ITO pattern forming method of the present invention, the etching step and the lift-off step become unnecessary, and problems caused by the steps, for example, adhesion problems between the photoresist and the ITO film can be solved. The effect that the process steps required for patterning can be reduced so that the through-put can be improved.

In particular, ITO is a material that is already widely used as a commercially transparent electrode, the present invention can greatly contribute to the fabrication and application of optoelectronic devices.

Claims (12)

A composition for synthesizing indium tin oxide (ITO), the composition comprising Mixing indium tert-butoxide, 1-benzoylacetone and methanol to form a first solution; Mixing tin tert-butoxide, 1-benzoylacetone and methanol to form a second solution; And Indium tin oxide synthetic composition prepared by a process comprising the step of mixing the first solution and the second solution. The method of claim 1, The first solution forming step includes mixing indium tert butoxide and 1-benzoylacetone in a ratio of 1: 1, and methanol, The second solution forming step comprises mixing tin tert-butoxide and 1-benzoylacetone, and methanol in a ratio of 1: 1, indium tin oxide synthetic composition. The method according to claim 1 or 2, Indium tin oxide synthesis, characterized in that the first solution mixing step, the second solution mixing step, and the first solution and the second solution mixing step is made in a glove box with a relative humidity of 5% or less. Composition. A method of forming a composition for synthesizing indium tin oxide (ITO), the method comprising Mixing indium tert-butoxide, 1-benzoylacetone and methanol to form a first solution; Mixing tin tert-butoxide, 1-benzoylacetone and methanol to form a second solution; And A method of forming an indium tin oxide composite composition, comprising mixing the first solution and the second solution. The method of claim 4, wherein The first solution forming step includes mixing indium tert butoxide and 1-benzoylacetone in a ratio of 1: 1, and 2 ml of methanol, The second solution forming step comprises mixing tin tert-butoxide and 1-benzoylacetone in a ratio of 1: 1, and 2 ml of methanol, indium tin oxide composite composition forming method. The method according to claim 4 or 5, The first solution mixing step, the second solution mixing step, and the first solution and the second solution mixing step, characterized in that in the glove box (glove box) of 5% relative humidity, indium tin oxide synthetic composition Forming method. A method of patterning indium tin oxide, the method comprising Providing a substrate; Indium tert-butoxide, 1-benzoylacetone and methanol are mixed to form a first solution, tin tert-butoxide, 1-benzoylacetone and methanol are mixed to form a second solution, and the first solution And mixing the second solution to form an indium tin oxide synthetic composition. Synthesizing an indium tin oxide film on the substrate from the indium tin oxide synthesis composition; Heat-treating the substrate on which the indium tin oxide film is synthesized; Exposing a pattern region of the surface region of the indium tin oxide film to an electron beam; And Developing the substrate on which the indium tin oxide film is formed, so that the pattern region remains in the surface region of the indium tin oxide film exposed to the electron beam. The method of claim 7, wherein Preparing the indium tin oxide synthetic composition Mixing the indium tert butoxide and 1-benzoylacetone and 2 ml of methanol in a ratio of 1: 1 to form the first solution; And A method of indium tin oxide patterning, comprising mixing tin tert-butoxide and 1-benzoylacetone and 2 ml of methanol in a ratio of 1: 1 to form the second solution. The method according to claim 7 or 8, The indium tin oxide synthetic composition preparation step is characterized in that the glove box (glove box) of 5% or less relative humidity, indium tin oxide patterning method. The method of claim 7, wherein And said indium tin oxide synthesis step comprises spin coating said indium tin oxide synthesis composition to synthesize an indium tin oxide film on said substrate. The method of claim 10, The indium tin oxide film synthesizing step may further include adding 1-pentanol to the indium tin oxide synthetic composition, The thickness of the indium tin oxide film is adjusted according to the amount of 1-pentanol, indium team oxide patterning method. The method of claim 10, Wherein the thickness of the indium tin oxide film is controlled by varying at least one of the time of spin coating and the spin coating rate.

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