KR20070063184A - Method of manufacturing display substrate and method for manufacturing display panel using the method - Google Patents

Abstract

A method for manufacturing a display substrate and a method for manufacturing a display panel by using the same are provided to improve the display quality, by processing a surface of an alignment layer through plasma so as to remove impurities from the surface of the alignment layer. An alignment layer is formed on a transparent substrate(S20). A surface of the alignment layer is processed by using plasma, thereby removing impurities from the alignment layer(S50). The surface of the alignment layer contains carbon of more than 20% after processing the alignment layer. The alignment layer has a surface energy of 62mJ/m^2 after processing the alignment layer. The alignment layer is a vertical inorganic alignment layer.

Description

Manufacturing method of display substrate and manufacturing method of display panel using same {METHOD OF MANUFACTURING DISPLAY SUBSTRATE AND METHOD FOR MANUFACTURING DISPLAY PANEL USING THE METHOD}

1 is a flowchart illustrating a method of manufacturing a display substrate in a method of manufacturing a display panel according to an exemplary embodiment of the present invention.

FIG. 2 is a cross-sectional view illustrating a step of manufacturing a substrate on which a thin film transistor is formed in FIG. 1.

3 is a cross-sectional view illustrating a step of forming an alignment layer in FIG. 1.

4 is a cross-sectional view showing a step of performing a plasma treatment on the surface of the alignment layer in FIG.

5 is a cross-sectional view illustrating a step of manufacturing a display panel by dropping a liquid crystal in FIG. 1.

6 is a cross-sectional view conceptually illustrating a plasma processing apparatus for performing the plasma processing of FIG. 4.

7 is a cross-sectional view conceptually illustrating a reaction mechanism of the plasma treatment in FIG. 4.

FIG. 8A is a graph illustrating a change in the amount of carbon in the alignment layer according to the plasma treatment time of FIG. 4.

FIG. 8B is a graph showing a change in surface energy of the surface of the alignment film after the plasma treatment of FIG. 4.

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

100: array substrate TFT: thin film transistor

150: first alignment layer 200: color filter substrate

230: color filter 250: second alignment layer

400: plasma processing apparatus 410: chamber

420: gas inlet 430: lower electrode

440: upper electrode 450: lower dielectric

460: upper dielectric 470: power generation unit

The present invention relates to a method of manufacturing a substrate and a method of manufacturing a display panel using the same, and more particularly, to a method of manufacturing a substrate for improving display quality of an image and a method of manufacturing a display panel using the same.

A liquid crystal display, which is a typical flat panel display, displays an image using liquid crystals. The liquid crystal display device has advantages of thinner, lighter weight, lower power consumption, and lower driving voltage than other display devices.

The liquid crystal display includes a liquid crystal display panel for displaying an image using a light transmittance of liquid crystal, and a backlight disposed under the liquid crystal display panel to provide light to the liquid crystal display panel. It includes an assembly (back-light assembly).

The liquid crystal display panel includes an array substrate on which a thin film transistor as a switching element is formed, a color filter substrate disposed to face the array substrate and having a color filter, and between the array substrate and the color filter substrate. And a liquid crystal layer interposed therebetween. In this case, first and second alignment layers for arranging liquid crystals in the liquid crystal layer in a predetermined direction are formed in each of the array substrate and the color filter substrate.

In general, a method of forming the liquid crystal layer includes a liquid crystal injection method and a liquid crystal dropping method. The liquid crystal injection method refers to a method of injecting the liquid crystal between the two substrates by a capillary phenomenon in a vacuum state. The liquid crystal dropping method refers to a method of dropping the liquid crystal between the array substrate and the color filter substrate and then assembling the two substrates in a vacuum state. Since the liquid crystal dropping method has an advantage of being made within a very short process time compared to the liquid crystal injection method, it is mainly used recently as a method of forming the liquid crystal layer.

The manufacturing method of the liquid crystal display panel using the liquid crystal dropping method will be described in more detail. First, an array substrate on which the thin film transistor is formed and a color filter substrate on which the color filter is formed are prepared. Subsequently, the first alignment layer is formed on the array substrate, and the second alignment layer is formed on the color filter substrate. After the first and second alignment layers are formed, the liquid crystals are dropped on the surface of any one of the first and second alignment layers. After the liquid crystals are dropped, the liquid crystal display panel is manufactured by combining the array substrate and the color filter substrate with each other.

In this case, the liquid crystal dropping process of dropping the liquid crystals is generally performed immediately after the first and second alignment layers are formed. However, due to process line congestion or the like, the two substrates on which the first and second alignment layers are formed may be left in the clean room for a predetermined time.

As such, when the two substrates on which the first and second alignment layers are formed are left in the clean room, impurities such as carbon and OH groups may be adsorbed on the surfaces of the first and second alignment layers to form fine particles. The formation of such fine particles has a problem of reducing the display quality of the image by lowering the alignment characteristics of the first and second alignment layers.

Therefore, the technical problem of the present invention is to solve such a conventional problem, an object of the present invention is to provide a method for manufacturing a display substrate to improve the display quality of the image by removing the fine particles on the surface of the alignment layer.

Another object of the present invention is to provide a method for manufacturing a display panel using the above-described method for manufacturing a display substrate.

A method of manufacturing a display substrate according to an exemplary embodiment of the present invention includes forming an alignment layer on a transparent substrate and removing impurities by plasma treating the surface of the alignment layer.

In this case, the plasma treatment may be performed at any one of atmospheric pressure and vacuum, and the gas for the plasma treatment may include an oxygen gas and an inert gas.

The carbon content on the surface of the alignment film after the plasma treatment is preferably 20% or less, and the surface energy of the alignment film after the plasma treatment is preferably 62 mJ / m ² or more.

Optionally, the alignment layer may be a vertical inorganic alignment layer that vertically aligns the liquid crystal with respect to the surface of the alignment layer, and the vertical inorganic alignment layer is preferably made of silicon oxide (SiOx).

In addition, a method of manufacturing a display panel according to an exemplary embodiment of the present invention provides an array substrate having a first alignment layer from which impurities are removed by plasma processing and impurities removed by plasma processing. Preparing a color filter substrate having a second alignment layer, forming a seal line on one of the array substrate and the color filter substrate, and dropping a liquid crystal onto the other substrate; Coupling a substrate and the color filter substrate to each other.

According to the present invention, by removing the impurities formed on the surface of the alignment film by the plasma treatment, it is possible to prevent the degradation of the alignment characteristics of the alignment film to further improve the display quality of the display panel.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a flowchart illustrating a method of manufacturing a display substrate in a method of manufacturing a display panel according to an embodiment of the present invention, FIG. 2 is a cross-sectional view illustrating a step of manufacturing a substrate on which a thin film transistor is formed in FIG. 1, and FIG. 1 is a cross-sectional view showing a step of forming an alignment film, FIG. 4 is a cross-sectional view showing a step of performing a plasma treatment on the surface of the alignment film in FIG. 1, FIG. It is sectional drawing shown.

1, 2 and 3, in order to manufacture the display panel 300 according to the present exemplary embodiment, an array substrate 100 or a color filter substrate 200 is first prepared (S10). At this time, after briefly explaining the prepared array substrate 100 and the color filter substrate 200, and proceeds to the manufacturing method of the next step.

The array substrate 100 may include a first transparent substrate 110, a gate wiring (not shown), a data wiring (not shown), a gate insulating layer 120, a thin film transistor (TFT), a protective layer 130, and a pixel electrode 140. It includes.

A plurality of gate lines are formed in a first direction on the first transparent substrate 110, and a plurality of data lines are formed in a second direction crossing the first direction. As the gate lines and the data lines cross each other, a plurality of pixel units are defined, and a thin film transistor TFT and a pixel electrode 140 are formed in each unit pixel.

The gate insulating layer 120 is formed on the first transparent substrate 110 to cover the gate lines. The gate insulating layer 120 is made of, for example, a transparent insulating material such as silicon oxide or silicon nitride.

The thin film transistor TFT is formed in each unit pixel and includes a gate electrode, a source electrode, a drain electrode, an active layer, and an ohmic contact layer. In this case, the drain electrode is electrically connected to the pixel electrode 140 through a contact hole formed in the passivation layer 130.

The pixel electrode 140 is formed in each unit pixel, and is a transparent and conductive material, for example, indium tin oxide (ITO), indium zinc oxide (IZO), or amorphous tin oxide thin film (ITO). amorphous Indium Tin Oxide, a-ITO). The pixel electrode 140 is electrically connected to the thin film transistor TFT by the contact hole, and is charged by receiving a driving voltage from the thin film transistor TFT.

The second substrate 200 includes a second transparent substrate 210, a light blocking film 220, a color filter 230, and a common electrode 250.

The second transparent substrate 210 has a plate shape and is made of a transparent material, that is, the same material as the first transparent substrate 110.

The light blocking film 220 is formed on the second transparent substrate 210 to block the movement of light. For example, the first substrate 100 may be formed on the second transparent substrate 210 to correspond to the gate wiring, the data wiring, the thin film transistor TFT, and the like.

The color filter 230 is formed on the second transparent substrate 210 to cover the light blocking film 220. Examples of the color filter 230 include a red color filter, a green color filter, a blue color filter, and the like.

The common electrode 240 is formed on the color filter 230. The common electrode 240 is made of a transparent conductive material. For example, the common electrode 240 is made of indium tin oxide (ITO), zinc indium oxide (IZO), or amorphous tin indium oxide (a-ITO). The common electrode 240 is applied with a common voltage from the outside to generate an electric field between the pixel electrode 140 and the pixel electrode 140.

1 and 3, a first alignment layer 150 is formed on the prepared array substrate 100 and a second alignment layer 250 is formed on the prepared color filter substrate 200 (S20). . In this case, the forming of the first alignment layer 150 and the second alignment layer 250 may be performed at the same time, and may be performed at different time periods. In this embodiment, as an example, a process of forming the first alignment layer 150 on the array substrate 100 will be described.

The first alignment layer 140 arranges the liquid crystals 310 in a predetermined direction. For example, the first alignment layer 140 is a vertical inorganic alignment layer that vertically aligns the liquid crystals 310 with respect to the surface of the first alignment layer 140. The vertical inorganic alignment layer is preferably made of silicon oxide (SiOx). In this case, the liquid crystals have negative dielectric anisotropy lying perpendicular to the electric field direction.

The first alignment layer 140 may be formed by deposition by sputtering, deposition by plasma (PECVD), thermal evaporation, or the like.

After depositing the first alignment layer 150, the surface of the first alignment layer 150 is cleaned using distilled water (S30). Through such distilled water cleaning, impurities formed on the surface of the first alignment layer 150 are primarily removed. After washing the distilled water, distilled water remaining on the surface of the first alignment layer 150 is dried by infrared rays (S40).

1 and 4, after the ultraviolet ray drying, the surface of the first alignment layer 150 is plasma treated (S50). Through the plasma treatment, impurities formed on the surface of the first alignment layer 150 may be secondarily removed. Specifically, the carbon adsorbate formed on the surface of the first alignment layer 150 is removed by the plasma treatment.

The plasma treatment is preferably performed in a vacuum state, but since it takes a lot of equipment and time to form the vacuum state, it is more preferable to perform at atmospheric pressure. In general, the plasma processing is performed by a plasma processing apparatus, and the plasma processing apparatus includes a vacuum plasma processing apparatus and an atmospheric pressure plasma processing apparatus.

The carbon content of the surface of the first alignment layer 150 after the plasma treatment is preferably 20% or less, and the surface energy of the alignment layer after the plasma treatment is preferably 62 mJ / m ² or more.

The gas used for the plasma treatment includes, for example, oxygen gas, and inert gas is preferably used together.

1 and 5, after performing plasma treatment on the surfaces of the first and second alignment layers 150 and 250, a seal line may be formed on one of the array substrate 100 and the color filter substrate 200. (Not shown), and the liquid crystals 310 are dropped on the other substrate. In this case, the liquid crystals 310 are dropped on the display area where an image is displayed, and the seal line is formed on a peripheral area surrounding the outer edge of the display area.

Finally, the display panel 300 is manufactured by combining the array substrate 100 and the color filter substrate 200 with each other. After the array substrate 100 and the color filter substrate 200 are combined with each other, the dropped liquid crystals 310 spread in all directions to form the liquid crystal layer 300 between the array substrate 100 and the color filter substrate 200.

Hereinafter, the plasma processing apparatus for performing the plasma processing, the reaction mechanism, and the change after the plasma processing will be described in detail.

6 is a cross-sectional view conceptually illustrating a plasma processing apparatus for performing the plasma processing of FIG. 4.

Referring to FIG. 6, a plasma processing apparatus 400 for plasma processing includes a vacuum plasma processing apparatus and an atmospheric pressure plasma processing apparatus.

The vacuum plasma processing apparatus generally generates plasma through glow discharge. For example, the vacuum plasma processing apparatus generates a plasma by applying a voltage of about 300 V / mm at a pressure of 10 Torr, and the generated plasma is generated on the surface of the first alignment layer of the array substrate or the second alignment layer of the color filter substrate. Remove impurities such as carbon adsorbate.

The atmospheric pressure plasma processing apparatus generally generates plasma through corona discharge. For example, the atmospheric pressure plasma processing apparatus generates a plasma by applying a voltage of about 5 kV / mm at a pressure of 760 Torr, which is 1 atmosphere, to remove impurities on the surfaces of the first and second alignment layers 100 and 200.

The atmospheric pressure plasma processing apparatus may include a dielectric barrier discharge (DBD) method and an atmospheric pressure RF frequency discharge in parallel plates.

The plasma processing apparatus 400 illustrated in FIG. 6 is, for example, an atmospheric pressure plasma processing apparatus using a method using a dielectric barrier discharge (DBD). The plasma processing apparatus 400 includes a chamber 410, a gas injection hole 420, a lower electrode 430, an upper electrode 440, a lower dielectric 450, an upper dielectric 460, and a voltage generator 470. Include.

The lower electrode 430, the upper electrode 440, the lower dielectric 450, and the upper dielectric 460 are disposed in the interior space of the chamber 410. The gas injection port 420 is connected to the chamber 410 to inject the reaction gas into the interior space of the chamber 410. The injected reaction gas may include, for example, an oxygen gas, and may also include an inert gas such as argon gas (Ar), xenon gas (Xe), and the like.

The lower electrode 430 and the upper electrode 440 are disposed to face each other at a predetermined distance, and are electrically connected to the voltage generator 470, respectively. The lower dielectric 450 is disposed on the upper surface of the lower electrode 430, and the upper dielectric 460 is disposed on the lower surface of the upper electrode 440. The array substrate 100 for plasma processing is disposed on the upper surface of the lower dielectric 450.

The voltage generator 470 may, for example, apply a high voltage of several kV / mm to several tens of kV / mm to the lower electrode 430 and the upper electrode 440 to form the first alignment layer 150 of the array substrate 100. The surface is plasma treated.

The plasma processing apparatus 400 preferably uses a remote type atmospheric pressure plasma processing apparatus having a large separation distance between the lower electrode 430 and the upper electrode 440. This is because the remote type atmospheric pressure plasma processing apparatus does not generate charges on the surface of the array substrate 100 or the color filter substrate 200, thereby preventing defects of the array substrate 100 or the color filter substrate 200 due to the application of a high voltage. You can prevent it. In particular, the remote type atmospheric pressure plasma processing apparatus can suppress destruction of the thin film transistor TFT of the array substrate 100 by the high voltage application.

7 is a cross-sectional view conceptually illustrating a reaction mechanism of the plasma treatment in FIG. 4.

Referring to FIG. 7, impurities formed on the surfaces of the first and second alignment layers 150 and 250 are removed through the plasma treatment. In this case, the impurities include, for example, carbon adsorbate and hydrogen adsorbate.

By the plasma treatment, a method of removing the impurities includes a physical removal method and a chemical removal method. First, the physical removal method will be described. As an example of an inert gas, argon gas (Ar) collides strongly with impurity particles by a strong electric field, and as a result, the impurity particles are formed in the first and second alignment layers 150 and 250. Removed from the surface.

On the other hand, when describing the chemical removal method, the highly reactive oxygen atom (O) excited by the high voltage reacts with the carbon adsorbate and hydrogen adsorbate formed on the surface of the first and second alignment layers (150, 250), In one example, water vapor (H ₂ O) or carbon dioxide (CO ₂ ) is generated. As a result, the carbon adsorbate and the hydrogen adsorbate are removed from the surfaces of the first and second alignment layers 150 and 250.

8A is a graph showing a change in the amount of carbon in the alignment layer according to the plasma treatment time of FIG. 4.

Referring to FIG. 8A, as the time for performing the plasma treatment increases, the carbon content in the surfaces of the first and second alignment layers 150 and 250 decreases. Specifically, for example, before the plasma treatment, the carbon content is about 19%, but after the plasma treatment is performed for 30 seconds, the carbon content is about 16%, and the plasma treatment is performed for 60 seconds. After that the carbon content has about 14%.

In this case, the carbon content is preferably about 20% or less, but more preferably about 15% or less, in order to prevent degradation of the alignment characteristics of the first and second alignment films 150 and 250.

FIG. 8B is a graph showing a change in surface energy of the surface of the alignment film after the plasma treatment of FIG. 4.

Referring to FIG. 8B, the surface energy of the first and second alignment layers 150 and 250 increases with the plasma treatment. Specifically, for example, before the plasma treatment, the surface energy has about 60 (mJ / m ² ), but after the plasma treatment, the surface energy is about 68 (mJ / m ² ) or about 67 ( mJ / m ² ).

In this case, in order to improve the alignment characteristics of the first and second alignment layers 150 and 250, the surface energy is preferably about 62 (mJ / m ² ) or more.

As described above, according to the present exemplary embodiment, the first and second alignment layers 150 and 250 are aligned by removing impurities formed on the surfaces of the first and second alignment layers 150 and 250 by a process delay or the like by plasma treatment. The fall of a characteristic can be prevented.

According to the present invention, by removing the impurities formed on the surface of the alignment film of the array substrate or the color filter substrate by plasma treatment, it is possible to prevent the degradation of the alignment characteristics of the alignment film and to further improve the display quality of the display panel.

In the detailed description of the present invention described above with reference to a preferred embodiment of the present invention, those skilled in the art or those skilled in the art having ordinary knowledge in the scope of the invention described in the claims to be described later It will be understood that various modifications and variations can be made in the present invention without departing from the scope of the present invention.

Claims (11)

Forming an alignment layer on the transparent substrate; And And removing impurities by performing plasma treatment on the surface of the alignment layer. The method of manufacturing a display substrate according to claim 1, wherein the carbon content on the surface of the alignment film after the plasma treatment is 20% or less. The method of claim 1, wherein the surface energy of the alignment layer after the plasma treatment is 62 mJ / m ² or more. The method of claim 1, wherein the alignment layer is a vertical inorganic alignment layer for arranging liquid crystals perpendicularly to the surface of the alignment layer. The method of claim 4, wherein the vertical inorganic alignment layer is made of silicon oxide (SiOx). The method of claim 1, wherein the plasma processing is performed in one of atmospheric pressure and vacuum. The method of claim 1, wherein the gas for plasma processing comprises oxygen gas. The method of claim 7, wherein the gas for plasma processing further comprises an inert gas. The method of claim 1, wherein forming the alignment layer Forming the alignment layer on the transparent substrate; Washing the surface of the alignment layer with distilled water; And And drying the surface of the alignment layer. The method of claim 9, wherein the surface of the alignment layer is dried by infrared rays. Preparing an array substrate having a first alignment layer from which impurities are removed by plasma processing and a color filter substrate having a second alignment layer from which impurities are removed by plasma processing; Forming a seal line on one of the array substrate and the color filter substrate, and dropping liquid crystal on the other substrate; And And coupling the array substrate and the color filter substrate to each other.

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