KR100774566B1 - Glass substrate for liquid crystal display device and method for manufacturing the same - Google Patents

Abstract

A low cost glass substrate for a liquid crystal display device and a method of manufacturing the same, which are suitable for forming a thin film transistor at a low temperature, are disclosed. The disiloxane monomer is surface-treated on a soda lime glass substrate using a chemical vapor deposition method, or spin-coated silsestuoxane oligomer, followed by curing and surface-treating to form a barrier layer. The barrier layer may prevent an alkali component such as sodium from diffusing into the organic substrate or preventing oxygen or water molecules from being transmitted from the outside of the display device.

Description

Glass substrate for liquid crystal display device and manufacturing method thereof {GLASS SUBSTRATE FOR LIQUID CRYSTAL DISPLAY DEVICE AND METHOD FOR MANUFACTURING THE SAME}

1 is a cross-sectional view showing a glass substrate according to an embodiment of the present invention.

FIG. 2 shows a reaction scheme for forming the first and second barrier layers of tetramethyldisiloxane in an oxygen atmosphere by plasma chemical vapor deposition.

3 is a scheme illustrating a process of curing by the reaction of the oligoorganosilsesquioxane resin and a curing agent.

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

100: glass substrate 110: substrate

102: first barrier layer 104: second barrier layer

The present invention relates to a glass substrate for a liquid crystal display device and a manufacturing method thereof. More particularly, the present invention relates to a glass substrate used to form a thin film transistor in a liquid crystal display device and a manufacturing method thereof.

A liquid crystal display device applies a voltage to a specific molecular arrangement of a liquid crystal to convert it into another molecular arrangement, and visually changes optical properties such as birefringence, photoreactivity, dichroism, and light scattering characteristics of the liquid crystal cell that emit light by the molecular arrangement. It is a display apparatus using the modulation of the light by a liquid crystal cell as an apparatus which converts into a change. The liquid crystal display may be broadly classified into a twisted nematic (TN) method and a super-twisted nematic (STN) method, and an active matrix display method using a switching element and a TN liquid crystal according to a difference in driving method. It can be divided into a passive matrix display method using an STN liquid crystal. BACKGROUND ART A thin film transistor-liquid crystal display device (TFT-LCD), which is a method of driving a liquid crystal using a thin film transistor (TFT) as a switching element, has a relatively simple circuit configuration and is widely used in a computer monitor and the like.

Generally, a liquid crystal display device includes a liquid crystal panel having a liquid crystal configured to determine whether light is transmitted through an electric signal. Since the liquid crystal panel is a passive optical device that does not emit light by itself, a back light assembly for providing light to the liquid crystal display device is mounted on the rear side of the liquid crystal panel.

The liquid crystal panel includes a source portion including a source driving circuit (IC) for applying screen data to display a screen, and a gate driving circuit (IC) for applying a gate signal for driving a gate element of a thin film transistor of the liquid crystal panel. A gate portion including a is formed. The image signal applied from the outside is converted into a data signal for driving the liquid crystal panel and a gate signal for driving the thin film transistor in the printed circuit board. These data signals and gate signals are applied to the transistors of the liquid crystal panel via the source and gate portions. Through this, the liquid crystal of the liquid crystal panel receives an electrical signal, thereby adjusting the light beam from the backlight assembly to configure the screen.

The liquid crystal display panel is composed of a thin film transistor substrate, a color filter substrate, and liquid crystal injected between these substrates. The thin film transistor substrate is a transparent glass substrate on which a matrix thin film transistor is formed. A data line is connected to a source terminal of the thin film transistors, and a gate line is connected to a gate terminal. In addition, a pixel electrode made of indium tin oxide (ITO), which is a transparent conductive material, is formed in the drain terminal. When electrical signals are input to the data lines and the gate lines, electrical signals are input to the source and gate terminals of the respective thin film transistors, and the thin film transistors are turned on or turned off according to the input of the electrical signals, thereby draining the drain terminals. The furnace outputs an electrical signal necessary for pixel formation.

The color filter substrate is provided to face the thin film transistor substrate. The color filter substrate is a substrate in which RGB pixels, which are color pixels in which a predetermined color is expressed while light passes, are formed by a thin film process. The front surface of the color filter substrate is coated with a common electrode made of ITO.

When power is applied to the gate terminal and the source terminal of the transistor of the thin film transistor substrate described above and the thin film transistor is turned on, an electric field is formed between the pixel electrode and the common electrode of the color filter substrate. Such an electric field changes the arrangement angle of the liquid crystal injected between the thin film transistor substrate and the color filter substrate, and changes the light transmittance according to the changed arrangement angle to obtain a desired pixel.

Transparent glass is used as a board | substrate for manufacturing such a liquid crystal display panel. As a characteristic of the board | substrate which is requested | required, alkali resistance, heat resistance, chemical resistance, etc. are mentioned. Specifically, since the alkali component is eluted from the glass substrate, the characteristics of the thin film element formed on the substrate are deteriorated. Therefore, the active matrix glass substrate should have less alkali component. In addition, the glass may vary in dimensions before and after heating, and the active matrix is formed on the substrate through a plurality of semiconductor processes. Since the substrate is repeatedly heated and cooled during many semiconductor processes, the substrate must be stable to thermal changes. In addition, in order to form an active matrix, a metal or an oxide is etched. In this case, the substrate must be stable against the etchant of the metal or oxide.

Since the simple matrix liquid crystal display device can be manufactured at a relatively low temperature of 300 ° C. or lower, a liquid crystal display panel is manufactured using inexpensive soda lime glass. Is being used. However, in order to form a liquid crystal panel composed of an active matrix including an amorphous silicon thin film transistor, a high temperature process of 300 ° C. or more is required. Therefore, alumino-silicate glass having high resistance to thermal shock and sudden temperature change and excellent etching resistance is used. . However, such alumino-silicate glass is expensive and occupies a large part of the material ratio of the liquid crystal display panel.

Recently, as a process for forming a thin film transistor at a low temperature of 200 ° C. or lower has been developed, the demand for resistance to thermal shock and temperature change at high temperatures has been alleviated. Therefore, it has been thought that it is preferable to use inexpensive soda lime glass as a liquid crystal panel substrate if it only satisfies other characteristics than heat resistance. Conventionally, when soda lime glass is used as a liquid crystal panel substrate, a silicon oxide film is coated on the substrate to increase resistance to alkali components such as sodium ions. U.S. Patent No. 5,830,252 also proposes a method of coating a metal oxide layer on glass to prevent diffusion of alkali ions. However, such an oxide-coated soda lime glass is suitable for manufacturing a simple matrix liquid crystal display device, but the oxide film is poor in chemical resistance because it is etched by many etchant. Therefore, it is not suitable for the board | substrate for forming the amorphous thin film transistor formed at low temperature.

Accordingly, the present invention has been proposed to solve the above problems, and a first object of the present invention is to provide a glass substrate for a liquid crystal display device, which is suitable for forming a thin film transistor at a low temperature.

 A second object of the present invention is to provide a method suitable for producing the glass substrate of the liquid crystal display device described above.

In order to achieve the first object of the present invention described above, the present invention, a substrate made of soda-lime glass; And a barrier coating layer formed on at least one surface of the substrate and formed of an organic silicon-based material.                     

In order to achieve the second object of the present invention described above, the present invention provides a method comprising the steps of providing a substrate made of soda-lime glass; And coating a barrier layer made of an organic silicon-based material on at least one surface of the substrate.

According to the present invention, a disiloxane monomer is surface-treated on a soda lime glass substrate using a chemical vapor deposition method or spin-coated with a silsestuoxane oligomer, followed by curing to form a barrier layer. The barrier layer may prevent an alkali component such as sodium from diffusing into the organic substrate or preventing oxygen or water molecules from being transmitted from the outside of the display device.

Hereinafter, the glass substrate for liquid crystal display devices and its manufacturing method which concern on the preferable Example of this invention are demonstrated in detail.

1 is a cross-sectional view of a glass substrate 100 according to an embodiment of the present invention.

Referring to FIG. 1, the glass substrate 100 for a liquid crystal display device includes a substrate 110 made of soda lime glass. The first barrier layer 102 is formed on the upper surface of the substrate 110, and the second barrier layer 104 is formed on the lower surface 110 of the substrate.

As described above, the substrate 110 is made of soda lime glass. Soda lime glass is known to contain a large amount of alkaline components therein. The alkali elution amount is calculated from Na ₂ O and is about 0.8 to 1.1 µg per cm ³ . The thickness of the substrate 110 may be 1.1 mm, 0.7 mm, 0.55 mm, 0.4 mm, or the like.

Such an alkali component has a bad influence on a liquid crystal material or a seal material. Accordingly, the first barrier layer 102 and the second barrier layer 104 are formed to prevent the diffusion of these alkaline components into the device formed on the substrate 110. These first and second barrier layers 102 and 104 also prevent oxygen or water molecules from being transmitted from the outside of the display device.

According to the present exemplary embodiment, the first and second barrier layers 102 and 104 are formed on both surfaces of the substrate. However, if necessary, the first and second barrier layers 102 and 104 may be formed on one surface of the substrate 110 on which the device is formed. The thickness of the first and second barrier layers 102, 104 is 2000 to 3000 kPa, preferably 2500 kPa.

Examples of the method for forming the first and second barrier layers 102 and 104 include a chemical vapor deposition method using a plasma, a sol-gel method, anodization method, a spin coating method, a microemulsion method, and the like. Especially, it is preferable to use the chemical vapor deposition method using a plasma, and the method by a spin coating method.

According to the plasma chemical vapor deposition method, a plasma is applied under an oxygen atmosphere using a disiloxane monomer. Examples of the disiloxane monomers used at this time include monomethyldisiloxane, dimethyldisiloxane, trimethyldisiloxane, tetramethyldisiloxane, monoethyldisiloxane, diethyldisiloxane, triethyldisiloxane, tetraethyldisiloxane, and the like. Can be. Plasma chemical vapor deposition is performed under conventional conditions.

FIG. 2 shows a reaction scheme for forming the first and second barrier layers 102 and 104 from tetramethyldisiloxane in an oxygen atmosphere by plasma chemical vapor deposition. The reaction of tetaramethyldisiloxane with oxygen is carried out at 40 to 60 ° C, preferably at 50 ° C. The deposition rate is 10 to 30 ms / sec, preferably 20 ms / sec.

According to another embodiment of the present invention, the first and second barrier coating layers 102 and 104 are organic resin layers formed by spin coating an organosiloxane resin and then thermally curing the organosiloxane resin. As an example of the said organic resin, the oligoorgano silsesquioxane resin formed by superposing | polymerizing the alkylsilane triol is mentioned. The oligoorganosilsesquioxane resin is mixed in a solvent using a resin having a molecular weight of several hundred thousand to several million as a curing agent, then coated at a speed of 500 to 1000 RPM in a spin coater and then cured.

3 is a scheme illustrating a process of producing the oligoorganosilsesquioxane resin using an alkylsilane triol. In FIG. 3, R represents hydrogen, a methyl group, an ethyl group, or other alkyl group, Me represents a methyl group, and n represents a positive integer.

Diffusion Test of Sodium Ion

It was evaluated whether the first and second barrier layers according to the present invention can prevent the diffusion of sodium ions generated in soda lime glass toward the liquid crystal or thin film transistor. Sample Samples were prepared as follows.

Samples 1 to 4 were prepared by the method according to an embodiment of the present invention. That is, the first and second barrier layers 102 and 104 were formed of tetramethyldisiloxane in an oxygen atmosphere by plasma chemical vapor deposition. The reaction of tetramethyldisiloxane with oxygen was carried out at 50 ° C., and the deposition rate was 20 μs / sec. At this time, the components of the organic silicon-based coating film formed was SiO _1.8-2.4 C _0.3-1.0 H _0.7-4.0 , as shown in FIG.

In addition, conventionally used alumino-silicate glass (Corning 1737, trade name of Corning) was prepared as Comparative Sample 1.

Amorphous silicon was deposited on samples 1-5 and then annealed for 2 hours. Table 1 shows the deposition temperature, deposition thickness, and annealing temperature of amorphous silicon of Samples 1 to 5.

Amorphous Silicon Deposition Temperature (℃)  Silicon deposition thickness Annealing temperature (℃) Sample 1 250 2500 200 Sample 2 250 2500 300 Sample 3 250 2500 350 Sample 4 200 2500 Do not anneal Comparison sample 1 275 1850 350

The amounts of sodium ions were measured by the Secondary Ion-Mass Spectrometer (SIM) for Samples 1 to 4 and Comparative Sample 1. The measurement was performed on an amorphous silicon layer, a barrier coating layer and a glass substrate.

The analysis results are shown in Table 2 below.

(Unit cps: water absorption) Amorphous silicon layer  Barrier coating Glass substrate Sample 1 <10 cps 2-10 cps 100000 cps Sample 2 <10 cps 2-20 cps 100000 cps Sample 3 <10 cps 5-100 cps 100000 cps Sample 4 <10 cps 5-500 cps 100000 cps Comparison sample 1 <10 cps - 1000 cps

As can be seen from Table 2 above, the amount of sodium ions in the barrier layer increased with increasing annealing temperature, but the sodium concentration of the amorphous silicon layer was measured to be 10 cps or less as a result of the absorption analysis. Thus, it was shown that the movement of sodium ions to the amorphous silicon layer was not blocked so that the barrier layer prevented the diffusion of sodium ions. From this, it can be seen that the soda lime organic substrate coated with the barrier layer according to the present invention can be applied as a substrate for LCD.

According to the present invention, a disiloxane monomer is surface-treated on a soda lime glass substrate using a chemical vapor deposition method or spin-coated with a silsestuoxane oligomer, followed by curing to form a barrier layer. Penetration of ions by alkaline components such as sodium is suppressed as in conventional aluminosilicate glasses. Therefore, even when the liquid crystal display device is manufactured using the glass substrate provided with the barrier coating layer according to the present invention, good device characteristics can be obtained.

Although the above has been described with reference to a preferred embodiment of the present invention, those skilled in the art will be variously modified and changed within the scope of the present invention without departing from the spirit and scope of the invention described in the claims below. I can understand that you can.

Claims (11)

A substrate made of soda-lime glass; A first barrier layer formed on one surface of the substrate and made of an organic silicon-based material; And A glass substrate for a liquid crystal display device comprising a second barrier layer formed on the other surface of the substrate facing the one surface and made of the organic silicon-based material. The glass substrate of claim 1, wherein the first and second barrier layers are formed by a chemical vapor deposition method under an oxygen plasma atmosphere using disiloxane monomers. 3. The disiloxane monomers according to claim 2, wherein the disiloxane monomers are monomethyldisiloxane, dimethyldisiloxane, trimethyldisiloxane, tetramethyldisiloxane, monoethyldisiloxane, diethyldisiloxane, triethyldisiloxane and tetraethyldisiloxane. Glass substrate, characterized in that at least one made from the group consisting of. The glass substrate according to claim 1, wherein the first and second barrier layers are organic resin layers formed by spin coating an organosiloxane resin and then thermally curing the organosiloxane resin. The glass substrate according to claim 4, wherein the organic resin layer is an oligoorganosilsesquioxane resin. Providing a substrate made of soda-lime glass; And Coating a first barrier layer made of an organic silicon-based material on one surface of the substrate; And And coating a second barrier layer made of the organic silicon-based material on the other surface of the substrate facing the one surface. The method of claim 6, wherein the first and second barrier layers are performed by plasma chemical vapor deposition. The method of claim 7, wherein the plasma chemical vapor deposition method is performed under an oxygen atmosphere using a disiloxane monomer. The method of claim 8, wherein the disiloxane monomers are monomethyldisiloxane, dimethyldisiloxane, trimethyldisiloxane, tetramethyldisiloxane, monoethyldisiloxane, diethyldisiloxane, triethyldisiloxane, and tetraethyldisiloxane. At least one made from the group consisting of a method for producing a glass substrate. The method of claim 6, wherein each of the first and second barrier layers comprises spin coating an organosiloxane resin; And And performing the step of heating and curing the spin-coated organic siloxane resin. The said organic resin layer is oligoorgano silsesquioxane resin, The manufacturing method of the glass substrate of Claim 10 characterized by the above-mentioned.

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