KR100865540B1 - Manufacturing method of alignment layer and liquid crystal display including the same - Google Patents

Abstract

A method for manufacturing an alignment layer and a liquid crystal display including the same are provided to form readily the inorganic alignment layer without using a vacuum evaporation for large size liquid crystal display. An orientation film formation method consists of following steps. An electrode is formed on a substrate.(S100) An organic film including the siloxane(Si-O-) is formed on the electrode potential.(S102) The organic film is oxidized and the oxidized organic film forms an inorganic alignment layer.(S104) If UVO is irradiated in the organic film, the organic film can be easily diversified to the inorganic film. A plasma processing, a thermal process, an UO processing, and etc. can be used for a mineralization process.

Description

Method of forming an alignment layer and a liquid crystal display including the same {manufacturing METHOD OF ALIGNMENT LAYER AND LIQUID CRYSTAL DISPLAY INCLUDING THE SAME}

1 is a schematic cross-sectional view of a liquid crystal display according to an exemplary embodiment of the present invention.

FIG. 2 is a schematic layout view of a thin film transistor array panel for the liquid crystal display of FIG. 1.

3 is a flowchart illustrating a method of forming an alignment layer for a liquid crystal display according to an exemplary embodiment of the present invention.

4 is a graph showing the xylocon peak of the X-ray photoelectron analysis according to the present invention.

5 is a graph showing the contact characteristics of the water droplets according to the UVO irradiation time according to an embodiment of the present invention.

6 is a photograph showing a polarization microscope observation result of the liquid crystal cell according to the UVO irradiation time according to an embodiment of the present invention.

<Explanation of symbols for the main parts of the drawings>

10: thin film transistor display panel 20: common electrode display panel

30: liquid crystal layer 31: liquid crystal molecules

100, 200: insulated substrate

102: gate line 104: data line

106: pixel electrode 108, 208: alignment film

202: color filter 204: overcoat

206: common electrode Q: thin film transistor

The present invention relates to a method for producing an alignment film for a liquid crystal display device and a liquid crystal display device including the same.

Liquid crystal displays (LCDs) are one of the most widely used flat panel displays.

The liquid crystal display includes two display panels on which an electric field generating electrode is formed and a liquid crystal layer interposed therebetween, and determines a direction of liquid crystal molecules of the liquid crystal layer by generating an electric field in the liquid crystal layer by applying a voltage to the electric field generating electrode. And transmittance of light passing through the liquid crystal layer.

Among the liquid crystal display devices, which are currently mainly used are structures in which electric field generating electrodes are provided on two display panels, respectively. Among them, a structure in which a plurality of pixel electrodes are arranged in a matrix form on one display panel, and one common electrode on the entire display panel covers the other display panel.

An alignment layer for aligning liquid crystal molecules is formed on the field generating electrode of the liquid crystal display. The alignment film may be formed of an inorganic alignment film such as SiOx or an organic alignment film such as polyimide.

The organic alignment film can be formed by a method such as spin coating, so that the alignment film can be easily formed in a large area liquid crystal display device.

In addition, the inorganic alignment film can be formed by a vacuum vapor deposition method, and compared to the organic alignment film has excellent light resistance and heat resistance, many studies have been conducted.

However, vacuum deposition, which requires high vacuum, is more complicated and time consuming than spin coating. In addition, as the size of the deposition apparatus is increased due to the large area of the liquid crystal display, a manufacturing cost increases.

Accordingly, the technical problem to be achieved by the present invention is to easily form an inorganic alignment layer without using vacuum deposition in a large-area liquid crystal display device.

According to an aspect of the present invention, there is provided a method of manufacturing an alignment layer, including forming an electrode on a substrate, forming an organic layer including a siloxane (Si-O-) group on the electrode, and oxidizing the organic layer to form an inorganic alignment layer. Forming a step.

The organic film may be made of polydimethylsiloxane.

Polydimethylsiloxane can be formed by any of spin coating, printing, and chemical reactions.

The chemical reaction may include introducing a hydroxyl group onto the substrate, dropping the monoglycidyl ether-terminated poly (dimethylsiloxane) on the substrate on which the hydroxyl group is formed, and then performing a heat treatment.

The hydroxyl group can be introduced by oxygen plasma treatment or UVO treatment.

Oxygen plasma treatment may proceed for about 20 seconds at an intensity of 25 W at 0.2 Torr pressure.

Heat treatment may be performed for 1 to 5 hours at 60 ~ 90 ℃.

After introducing the hydroxyl group, the method may further include introducing an amino group by adding a silane having an NH ₂ group to the surface of the substrate.

The introduction of the amino group may be performed by immersing the substrate into which the hydroxyl group is introduced in pure water in which 0.5 wt% of 3-aminopropyltriethoxysilane is dissolved for 5 to 20 minutes.

The inorganic alignment layer may be SiO _X through oxidation of the organic layer, and the inorganic alignment layer may include CH ₃ .

SiO _x may be SiO ₂ , and the oxidation may be any one of UVO treatment, plasma treatment, and heat treatment.

UVO treatment may oxidize the organic film by irradiating the organic film with UVO for 20 to 60 minutes.

The thickness of the inorganic alignment layer may be 160 nm or more.

According to another aspect of the present invention, there is provided a liquid crystal display device including: first and second substrates facing each other, first electrodes formed on the first substrate, second electrodes formed on the second substrate, and first and second substrates. the respectively formed on the liquid crystal layer, a first electrode and a second electrode that is formed between the second electrode and includes an alignment film made of SiO _X containing a small amount of CH _3.

The liquid crystal molecules of the liquid crystal layer may be oriented perpendicular to the first and second substrates.

Carbon of the alignment layer may be less than 20%, and SiO _x may be SiO ₂ .

DETAILED DESCRIPTION Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention.

In the drawings, the thickness of layers, films, panels, regions, etc., are exaggerated for clarity. Like parts are designated by like reference numerals throughout the specification. When a part of a layer, film, area, plate, etc. is said to be "on top" of another part, this includes not only when the other part is "right over" but also another part in the middle. On the contrary, when a part is "just above" another part, there is no other part in the middle.

A liquid crystal display according to an exemplary embodiment of the present invention will now be described in detail with reference to FIGS. 1 and 2.

1 is a schematic cross-sectional view of a liquid crystal display according to an exemplary embodiment of the present invention, and FIG. 2 is a schematic layout view of a thin film transistor array panel for the liquid crystal display of FIG. 1.

As shown in FIG. 1, a liquid crystal display according to an exemplary embodiment of the present invention includes a liquid crystal layer 30 filled between an opposing thin film transistor array panel 10, a common electrode display panel 20, and two display panels 10 and 20. ).

The liquid crystal layer 30 is sealed by a sealing material (not shown). The liquid crystal display may further include a backlight unit (not shown) positioned at the front or side of the thin film transistor array panel 10.

First, the thin film transistor array panel 100 will be described.

Referring to FIG. 2, a plurality of gate lines 102 and a plurality of data lines 104 that are insulated from and cross the gate lines 102 are formed on an insulating substrate 100 made of a transparent insulating material such as glass. The gate line 102 carries a scan signal and the data line 104 carries an image signal.

The plurality of pixel areas P defined by the gate line 102 and the data line 104 collectively form a display area D for displaying an image of the liquid crystal display.

Thin film transistors Q, which are switching elements connected to the gate line 102 and the data line 104, are respectively connected to the plurality of pixel regions P. FIG. The thin film transistor Q turns the image signal ON and OFF in accordance with the scan signal.

Referring back to FIGS. 1 and 2, each thin film transistor Q is connected to a pixel electrode 106 that receives an image signal transmitted from the data line 104.

The pixel electrode 106 is made of a transparent conductive material such as indium tin oxide (ITO) or indium zinc oxide (IZO). The pixel electrode 106 may include a cutout (not shown) patterned in a predetermined shape, and a protrusion (not shown) may be formed on the pixel electrode 106 in a predetermined shape.

Next, the common electrode display panel 20 will be described.

Referring to FIG. 1, a plurality of color filters 202 are formed on an insulating substrate 200 made of a transparent insulating material such as glass. The color filter 202 may have a band shape extending along the pixel column or the pixel row, and display one of primary colors such as red, green, and blue.

A light bloking member (not shown) called a black matrix may be formed on the substrate 202 to prevent light leakage. The light blocking member may be formed to overlap the gate line 102, the data line 104, and the thin film transistor Q, but may be omitted as necessary.

An over coat layer 204 may be formed on the color filter 202. The overcoat film 204 is used to planarize the substrate 200 and may be omitted as necessary.

The common electrode 206 facing the pixel electrode 106 is formed on the overcoat 204. The common electrode 206 may be made of a transparent conductive material such as ITO or IZO, and may include a cutout (not shown), such as the pixel electrode 106, or a protrusion (not shown) on the common electrode 206. Can be formed. The cutouts or protrusions of the common electrode 206 are alternately disposed so as not to overlap with the cutouts or protrusions of the pixel electrode 106.

Alignment layers 108 and 208 are coated on inner surfaces of the display panels 10 and 20, and they may be vertical alignment layers.

Polarizers (not shown) are provided on the outer surfaces of the display panels 10 and 20, and polarization axes of the two polarizers are parallel or orthogonal to each other. In the case of a reflective liquid crystal display, one of two polarizers may be omitted.

The liquid crystal molecules 31 of the liquid crystal layer 30 are aligned such that their major axes are substantially perpendicular to the surfaces of the two display panels 10 and 20 in the absence of an electric field. However, when the electric field is formed by the pixel electrode 106 and the common electrode 206, the cutouts and protrusions distort the electric field between the pixel electrode 106 and the common electrode 206 so that the liquid crystal molecules 31 may have various directions. To be arranged. As described above, when the alignment direction of the liquid crystal molecules 31 is varied, the viewing angle may be improved.

Next, a method of forming an alignment layer will be described in detail with reference to the flowchart of FIG. 3.

3 is a flowchart illustrating a method of forming an alignment layer for a liquid crystal display according to an exemplary embodiment of the present invention.

Referring to FIG. 3, first, a substrate on which a transparent electrode is formed is prepared (S100), and an organic film made of poly (dimethylsiloxane) is formed on the prepared substrate (S102).

The method of forming the organic film which consists of polydimethylsiloxane can be formed by methods, such as a chemical reaction, spin coating, and printing. Among these, the chemical reaction may form a thin film, so in the embodiment of the present invention, an organic film made of polydimethylsiloxane is formed using the chemical reaction.

In order to form an organic film by chemical reaction, the substrate is first washed. The substrate can be cleaned ultrasonically in trichloroethylene (TCE), acetone, alcohol solution. It is then rinsed with ultrapure water to remove the remaining wash solution.

Hydroxide (OH) is then introduced to the substrate surface. The hydroxyl group can be introduced by oxygen plasma treatment or UV with oxygen (UVO) treatment. Oxygen plasma treatment proceeds for about 20 seconds at an intensity of 25 W at a pressure of 0.2 Torr.

Thereafter, amino groups are introduced to the substrate surface. Introduction of the amino group can be carried out by addition of a silane with NH ₂ groups. For example, 3-aminopropyltriethoxysilane (APTES) may be used. In this case, deionized water (deionized water) in which 0.5 wt% of APTES is dissolved on the substrate surface on which the hydroxyl group is introduced is used. Immerse in Immersion time may be about 5-20 minutes. Through immersion, the silane group and the hydroxyl group of APTES react to introduce an amino group on the substrate surface.

Then, monoglycidyl ether-terminated poly (dimethylsiloxane) is dropped on the substrate and heat-treated to form an organic film composed of polydimethylsiloxane only. Heat treatment is carried out at 60 ~ 90 ℃ for 1 to 5 hours.

When the heat treatment temperature is increased, the step of introducing the amino group may be omitted and the monoglycidyl ether-terminated poly (dimethylsiloxane) may be directly reacted with the hydroxyl group.

Next, the organic layer is inorganicized to form an inorganic alignment layer (S104). Mineralization can utilize oxidation reactions, such as a plasma treatment, heat processing, and UVO treatment. In the embodiment of the present invention used an oxidation reaction using UVO, specifically as follows.

When the organic film made of polydimethylsiloxane is irradiated with UV of 254 nm, UV decomposes oxygen (O ₂ ) in the air to generate ozone (O ₃ ). At this time, UVO is irradiated with an intensity of about 100MW / cm ² .

The generated ozone combines with carbon of polydimethylsiloxane to produce CO ₂ , H ₂ . These are volatilized in gaseous form to form a SiO _x film made of SiO ₂ or the like, mostly leaving only Si—O bonds in the film of polydimethylsiloxane.

This process can be represented by the following scheme.

Oxidation proceeds from the surface of the organic film and moves into the film. In the beginning, oxidation proceeds rapidly at the surface, and after a certain time, the oxidation rate is gradually slowed down due to the SiO ₂ of the already formed surface. Therefore, since the oxidation does not proceed any more after a certain time, the UVO is irradiated for 20 minutes or more until the film thickness of SiO ₂ is 160nm or more.

This can be seen in Table 1 below.

Table 1 is a table showing the component changes of the film according to the UVO irradiation time according to an embodiment of the present invention.

As shown in Table 1, the longer the UVO irradiation time, the less the carbon content in the organic film, the mineralization proceeds. At this time, when the UVO irradiation time is 60 minutes or more, the content of carbon is 20% or less to become an inorganic film.

Mineralization of the organic film according to the embodiment of the present invention can be confirmed through FIGS. 4 to 6.

4 is a graph showing a change in binding energy of molecules according to the present invention, Figure 5 is a graph showing the contact characteristics of water droplets according to the UVO irradiation time according to an embodiment of the present invention, Figure 6 is an embodiment of the present invention It is a photograph showing the polarization microscope observation results of the liquid crystal cell according to the UVO irradiation time.

Referring to FIG. 4, since the binding energy peak is shifted at 102.7 eV as the UVO irradiation time increases, the binding energy peak is confirmed at 103.5 eV, which is the binding energy of Si-O. .

5, it can be seen that the longer the UVO irradiation time, the smaller the contact angle of the water droplets. Through this, it can be seen that the characteristics of the alignment layer are changed from the hydrophobic organic layer to the hydrophilic inorganic layer.

In addition, referring to FIG. 6, the degree of polarization of the liquid crystal display according to the UVO irradiation time is shown. As the irradiation time increases, the liquid crystal molecules are more vertically aligned. Therefore, when the irradiation time is 20 minutes or more, it can be confirmed that normally black in both 45 degree and 90 degree polarizers.

The alignment layer according to an exemplary embodiment of the present invention may be applied to a liquid crystal display device having a horizontal alignment mode by horizontally aligning liquid crystal molecules using a rubbing or ion beam irradiation method.

As in the embodiment of the present invention, when the organic film is irradiated with UVO, it can be easily changed to an inorganic film. Therefore, a large-area liquid crystal display device can be easily manufactured without using expensive deposition equipment for forming an inorganic film.

Although preferred embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements of those skilled in the art using the basic concepts of the present invention defined in the following claims are also provided. It belongs to the scope of the invention.

Claims (19)

Forming an electrode on the substrate, Forming an organic film including a siloxane (Si-O-) group on the electrode, and Oxidizing the organic layer to form an alignment layer An alignment film formation method of the liquid crystal display device containing. In claim 1, The organic film is an alignment film forming method of a liquid crystal display device made of polydimethylsiloxane. In claim 2, Wherein the polydimethylsiloxane is formed by any one of spin coating, printing, and chemical reaction. In claim 3, The chemical reaction comprises introducing a hydroxyl group onto the substrate, And dropping monoglycidyl ether-terminated poly (dimethylsiloxane) on the substrate on which the hydroxyl group is formed, and then heat-treating the liquid crystal display device. In claim 4, And the hydroxyl group is introduced by an oxygen plasma treatment or an oxygen treatment using UV. In claim 5, Wherein the oxygen plasma treatment is performed for 20 seconds at an intensity of 25 W at a pressure of 0.2 Torr. In claim 4, The heat treatment is a method of forming an alignment film of a liquid crystal display device performed for 1 to 5 hours at 60 ~ 90 ℃. In claim 4, After introducing the hydroxyl group, And introducing an amino group by adding a silane having an NH ₂ group to the surface of the substrate. In claim 8, And wherein the amino group is immersed in pure water in which 0.5 wt% of 3-aminopropyltriethoxysilane is dissolved for 5 to 20 minutes to introduce the substrate into which the hydroxyl group is introduced. In claim 2, And the alignment layer is SiO _x . In claim 10, The SiO _x is a method of forming an alignment film of a liquid crystal display device of SiO _2. In claim 10, The alignment film is a method of forming an alignment film of the liquid crystal display device containing CH ₃ . In claim 1, And the oxidation is performed by any one of oxygen treatment, plasma treatment, and heat treatment using UV. In claim 13, The oxygen treatment using UV proceeds to the organic layer for 20 to 60 minutes to oxidize the organic layer. The method of claim 14, The alignment film forming method of the liquid crystal display device whose thickness of the said alignment film is 160 nm or more. delete delete delete delete

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