KR100510717B1 - liquid crystal display device and method for manufacturing the same - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device and a method for manufacturing the same, which reduce wiring resistance by mixing carbon nanotubes with metal pastes to form metal wirings. The present invention relates to a metal paste and carbon nanotubes in one direction at regular intervals on a substrate. A plurality of gate wirings formed by mixing, a plurality of data wirings formed of the same material as the gate wiring and having a predetermined interval in a direction perpendicular to the gate wiring, and defining a pixel region; and the gate wiring and the data wiring crossing each other. And the pixel region formed in a matrix form and a plurality of thin film transistors which are switched by signals of the gate wirings and transfer the signals of the data wirings to the pixel electrodes, respectively. .

Description

Liquid crystal display device and method for manufacturing the same

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device, and more particularly, to a liquid crystal display device suitable for lowering the resistance of a wiring and a manufacturing method thereof.

In general, in the liquid crystal display, since wiring is used as a means for transmitting signals, it is required to minimize signal delay.

In this case, in order to prevent signal delay, the wiring uses a metal material having a low resistance, in particular, an aluminum-based metal material such as aluminum (Al) or aluminum alloy (Al alloy).

However, since the aluminum-based wiring has weak physical or chemical properties, corrosion occurs when the contact portion is connected to other conductive materials, thereby deteriorating the characteristics of the liquid crystal display.

In order to improve such contact characteristics, different metals may be formed together when the wirings are formed of aluminum series, but in order to form a multilayer wiring, not only different etching solutions are required but also multiple etching processes are required, which makes the manufacturing process complicated. Become.

On the other hand, the liquid crystal display is one of the flat panel display devices most widely used at present, the liquid crystal layer between the two substrates and the two substrates, the plurality of substrates formed with a plurality of electrodes for generating an electric field, the light attached to the outer surface of each substrate The display device is composed of two polarizing plates for polarizing the light emitting device, and adjusts the amount of light transmitted by rearranging the liquid crystal molecules of the liquid crystal layer by applying a voltage to the electrode.

A thin film transistor is formed on one substrate of the liquid crystal display, which serves to switch a voltage applied to the electrode. On the substrate on which the thin film transistor is formed, a plurality of wirings, that is, a plurality of gate wirings and data wirings are formed in row and column directions, respectively.

A pixel electrode is formed in a pixel region defined by the intersection of the gate wiring and the data wiring, and the thin film transistor controls the image signal transmitted through the data wiring according to the scan signal transmitted through the gate wiring and sends it out to the pixel electrode.

In such a liquid crystal display, the larger the screen, the longer the wiring and the delay of a signal transmitted through the wiring occurs.

Therefore, it is desirable to reduce the resistance of the wiring in order to reduce the delay of the signal. For this purpose, a low resistance material such as aluminum or an aluminum alloy is used as the material of the wiring.

Meanwhile, as the degree of integration of the liquid crystal display device is improved, the line width of the metal wiring becomes narrower, and the current density flowing through the metal wiring having the narrow line width increases.

Such increase in current density causes electromigration in the metal wiring, which adversely affects the reliability of the metal wiring.

In general, a conductive material having low resistivity and excellent device reliability has emerged as a metallization material because reliability is lowered due to electro migration (EM) or stress migration (SM).

EM is a defect caused by an increase in the current density in the metal wiring. As the wiring width becomes smaller, the current density in the wiring becomes higher due to the high speed operation of the device.

On the other hand, SM is a creep fracture mode generated by applying mechanical stress applied to a wiring. This stress causes a difference in thermal expansion coefficient between the insulating film and the metal wiring in order to protect the wiring, and tends to increase as the wiring width becomes smaller.

The main path of diffusion of the metal atoms when electrical material movement occurs in the metal wiring is diffusion through grain boundaries.

Therefore, the layout technology of the metal wiring having no grain boundary is very important in order to improve the electrical material movement characteristics of the metal wiring.

1 is a schematic configuration diagram showing a general sputtering apparatus.

As shown in FIG. 1, a cathode 3 is installed in the vacuum chamber 1, a target 2 is attached to the lower portion of the cathode 3, and is coaxial with the target 2. An anode 4 is provided, and the substrate 5 is mounted on the anode 4.

Here, the target 2 is made of a ceramic material, a metal compound, an insulating material, or the like.

In addition, a plasma power source 6 is installed to generate a plasma by using gases such as oxygen (O ₂ ) and argon (Ar) inside the vacuum chamber 1, and a vacuum inside the vacuum chamber 1. A vacuum system 7 is installed for generation.

When performing sputtering deposition using the above-described sputtering apparatus, the positively generated plasma gas collided with the target 2 to which the negative bias voltage was applied due to the plasma power source 6. To sputter the material of the target 2.

The atoms or molecules separated from the target 2 are deposited on the substrate 5 which is disposed facing each other.

On the other hand, without using the sputtering apparatus configured as described above, the method of forming the metal wiring may be formed using printing techniques such as screen printing and offset printing.

Hereinafter, a conventional metal wiring and a method of forming the same will be described with reference to the accompanying drawings.

2 shows the grain boundaries of a conventional Ag metal wiring.

As shown in FIG. 2, a metal wiring 10 having a wide wiring width is formed on an insulating substrate (not shown) for high current driving.

At this time, the surface of the metal wiring 10 has a grain boundary (Grain Boundary) 20 in the form of a diffusion path that prevents the movement of metal atoms by the electro-migration (Electro migration).

In the conventional metal wiring forming method configured as described above, as shown in FIG. 2, the metal wiring 10 is formed on the insulating substrate by screen printing.

In more detail, the metal wiring 10 is formed on an insulating substrate by an extrusion method using a squeeze.

Here, the extrusion method for forming the metal wiring 10 is a silver paste method (including screen printing method) is a method that can simply coat Ag without a deposition process.

The silver paste is a material in which Ag is mixed in a solution.

Meanwhile, silver, aluminum, zinc, copper, nickel, and the like, which are excellent in low melting point and electrical conductivity, may be used as the material of the metal wire 10.

That is, the metal paste 10 is formed on the insulating substrate by extruding the previously prepared silver paste using a squeeze.

However, in the conventional metal wiring and the formation method as described above has the following problems.

In other words, due to the large number of grain boundaries present in the metal wiring, the wiring resistance increases during high current driving, causing a signal delay.

Disclosure of Invention The present invention has been made to solve the above-mentioned problems, and an object thereof is to provide a liquid crystal display device and a method of manufacturing the same, which reduce wiring resistance by forming carbon interconnections by mixing carbon nanotubes with metal pastes. .

The liquid crystal display device according to the present invention for achieving the above object is formed of a plurality of gate wirings formed by mixing a metal paste and carbon nanotubes in one direction at regular intervals on the substrate, and formed of the same material as the gate wirings And a plurality of data wires defining pixel areas at regular intervals in a direction perpendicular to the gate wires, pixel electrodes formed in a matrix form in each pixel area defined by crossing the gate wires and the data wires; And a plurality of thin film transistors which are switched by a signal of a wire and transfer the signal of the data wire to each pixel electrode.

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Hereinafter, a liquid crystal display and a manufacturing method thereof according to the present invention will be described in detail with reference to the accompanying drawings.

In the present invention, carbon nanotubes are mixed with metal pastes to form metal wires.

In general, Dr. Lijima, who was an electron microscope analyst at Nippon Electric in 1991, said, Found.

The carbon atom has an atomic number of 6 and has an electron arrangement of 1s ² 2s ² 2p ² structure in the ground state, but in order to covalently bond with other atoms, the electron arrangement is rearranged.

This relocation occurs after a single electron of the 2s orbital transitions to a 2p orbital and then has a mixed orbital function that appears to be a mixture of the s and p orbitals.

When the electrons of one s orbital and the electrons of one p orbital are mixed to form two hybrid orbital functions, it is called an sp structure. when forming the electron of the sp ² structure, one s orbital and three p-electron orbital of a mixture of sp ³ and gujora the case forming the four hybrid orbitals.

The hybrid orbitals that carbon atoms can have to form crystals are sp ³ and sp ² structures.

Since the sp ³ structure has four hybrid orbitals, strong bonds with four other atoms form diamonds. The sp ² structure, on the other hand, combines three different carbon atoms in plan with three hybrid orbitals to form a graphite plane of hexagonal plate-like structure.

At this time, the electrons of the remaining p orbitals form weak bonds with the electrons of the p orbitals of other atoms. These weakly bonded electrons allow the graphite surface not only to have a relatively large electrical conductivity, but also to be associated with the bond and have a stronger bond energy than diamond.

On the other hand, the reason why graphite breaks down very easily in everyday life is because the layers of graphite are laminated by van der Waals bonds of very weak bonds, so the interplanetary breaks easily, but the graphite plane itself is not broken.

Carbon nanotube is a structure in which a single graphite surface made of sp ² bonds is rolled roundly. In this case, the structure and the diameter of determining the characteristics of the carbon nanotubes are determined according to the "side angle" of the graphite surface and "how much the diameter of the tube" is determined.

The characteristics of carbon nanotubes have a very large aspect ratio (~ 1000) in shape, and show the characteristics of a conductor or a semiconductor depending on the diameter and structure of the tube. Has very good electrical conductivity.

In addition, it has very strong mechanical strength, Young's modules in tera units, and excellent thermal conductivity. Applications include electron emitters of various devices such as field emission displays (FEDs), white light sources, lithium ion secondary battery electrodes, transport storage media of fuel cells, nano-wires, AFM / Probes such as STM, Field Effect Transistors (FETs), and high-performance composites are available, and their use as electron emission sources has been studied until the commercialization stage.

3 is a SEM of a metal interconnection formed by mixing carbon nanotubes with TiO ₂ particles.

As shown in FIG. 3, when the carbon nanotubes 40 were mixed with the TiO ₂ particles 31 as the insulator, the current efficiency was confirmed to be increased. It can provide a passage through which current can flow without being affected.

That is, Table 1 compares the resistance of before (A) and after (B) applying carbon nanotubes to TiO ₂ particles.

Resistance of A Specific resistance of B (Ωcm) 273511104 57437 148818176 28275 82378784 16476

As shown in the above table, it can be seen that the carbon nanotubes are a medium through which electricity is applied, and when the carbon nanotubes are applied to the TiO ₂ particles, the resistance is very low.

In the present invention, the carbon nanotubes having the above characteristics are mixed with the metal paste to form metal wiring.

Figure 4 shows the grain boundaries of the metal wiring according to the present invention.

As shown in FIG. 4, the carbon nanotubes 40 and the metal paste (the material in which the metal is mixed in a solution such as a solvent) 30 are mixed with a predetermined width on an insulating substrate (not shown). A metal wiring 50 is formed.

Here, the carbon nanotube 40 is used as a current movement path that can pass through grain boundaries 60 existing in the metal paste 30 during high current driving.

On the other hand, the metal wiring forming method according to the present invention will be described.

First, the conductive paste in which the metal paste 30 and the carbon nanotubes 40 are mixed on the insulating substrate is pattern-printed by screen printing to form the metal wiring 50.

Here, the screen printing method is carried out by a method of covering a mask having an opening in a desired pattern shape, supplying a conductor paste on it, and squeezing and extending it.

As said printing mask, the thing in which the pattern was formed in the mesh of polyester generally used by emulsion, and a metal mask, etc. can use various things according to a use.

Subsequently, the insulating substrate is conveyed to a furnace for heating and drying with infrared rays, a furnace for drying with hot air, and the like, and the metal wiring 50 is dried and cured.

Here, it is common to cure the printed metal wiring 50 by drying. However, when it selects as an infrared curing type metal paste as mentioned above, it can harden | cure in a short time by irradiating infrared rays of the wavelength suitable for a material.

Meanwhile, as a metal material of the metal paste 30 in which the carbon nanotubes 40 are mixed, Ni, Al, Au, Ag, Al, Pd / Ag, Cr, Ta, Cu, Ba, LaB ₆ , Ca _0.2 La _0.8 CrO ₃ , ITO (Indium Tin Oxide) and SnO ₂ may be used alone or in combination as appropriate.

On the other hand, although the screen printing method has been described in the present invention as a method for forming the metal wiring 50, the vapor deposition method, the sputtering method, the screen printing method and the lift-off method can be appropriately selected according to the conductive material to be used.

That is, the metal wiring 50 having a predetermined pattern may be formed using a suitable mask or screen, or after the conductive material layer is formed on the entire surface, the conductive material layer is patterned to form the metal wiring 50. It can also be formed.

5 is a plan view showing a liquid crystal display device using a metal wiring according to the present invention.

As shown in FIG. 5, a plurality of gate lines 62 are formed on the lower substrate 61 by mixing a metal paste and carbon nanotubes in one direction at regular intervals to define pixel regions. A plurality of data lines 63 formed by mixing the metal paste and the carbon nanotubes at regular intervals in a direction perpendicular to the gate lines 62 are arranged.

In the pixel region P defined by crossing the gate line 62 and the data line 63, a pixel electrode (reflective electrode) 64 formed in a matrix form and a signal of the gate line 62 are applied. The plurality of thin film transistors T are switched to transfer the signal of the data line 63 to the pixel electrodes (reflective electrodes) 64.

Here, the thin film transistor T may include a gate electrode 65 protruding from the gate line 62, a gate insulating film (not shown) formed on the front surface, and a gate insulating film above the gate electrode 65. The semiconductor layer 66 formed thereon, the source electrode 67 protruding from the data line 63, and the drain electrode 68 are disposed to face the source electrode 67.

The drain electrode 68 is electrically connected to the pixel electrode 64 through the contact hole 69.

Meanwhile, the lower substrate 61 configured as described above has a predetermined space and is bonded to the upper substrate (not shown).

Here, the upper substrate has an opening corresponding to the pixel region P formed in the lower substrate 61 and has a black matrix layer that serves as a light blocking function, and red / green / In addition to the blue (R / G / B) color filter layer and the pixel electrode (reflection electrode) 16, a common electrode for driving a liquid crystal is included.

The lower substrate 61 and the upper substrate as described above have a predetermined space by a spacer and liquid crystal is injected between two substrates bonded by a seal material having a liquid crystal injection hole.

In this case, in the liquid crystal injection method, the liquid crystal is injected between the two substrates by osmotic pressure when the liquid crystal injection hole is immersed in the liquid crystal container by maintaining the vacuum state between the two substrates bonded by the real material. When the liquid crystal is injected as described above, the liquid crystal injection hole is sealed with a sealing material.

On the other hand, the present invention described above is to form a metal wiring by mixing the carbon nanotubes in the conductive material, is not limited to the accompanying drawings, and various substitutions, modifications and changes within the scope of the technical spirit of the present invention It will be apparent to those skilled in the art that modifications are possible.

As described above, the liquid crystal display and the manufacturing method thereof according to the present invention have the following effects.

That is, by mixing carbon-nanotubes with a metal paste (for example, silver paste) to form metal wiring through screen printing, the current resistance path may be formed in the grain boundaries of the metal paste to reduce wiring resistance.

1 is a schematic configuration diagram showing a general sputtering apparatus

2 is a view showing grain boundaries of a conventional metal wiring;

3 is a SEM of a metal wiring formed by mixing carbon nanotubes with TiO ₂ particles.

Figure 4 is a plan view showing the grain boundaries of the metal wiring according to the present invention

5 is a plan view showing a liquid crystal display using a metal wiring according to the present invention.

Explanation of symbols for the main parts of the drawings

30 metal paste 40 carbon nanotube

50: metal wiring 60: grain boundary

Claims (11)

delete delete delete delete delete delete A plurality of gate wirings formed by mixing a metal paste and carbon nanotubes in one direction at regular intervals on a substrate; A plurality of data lines formed of the same material as the gate lines and having a predetermined interval in a direction perpendicular to the gate lines to define a pixel area; A pixel electrode formed in a matrix form in each pixel region defined by crossing the gate line and the data line; And a plurality of thin film transistors which are switched by signals of the gate lines to transfer the signals of the data lines to the pixel electrodes. The method of claim 7, wherein the metal material of the metal paste is Ni, Al, Au, Ag, Al, Pd / Ag, Cr, Ta, Cu, Ba, LaB ₆ , Ca _0.2 La _0.8 CrO ₃ , ITO and SnO ₂ A liquid crystal display device comprising a single material or a combination of these materials. Mixing the metal paste with the carbon nanotubes to form a conductor paste; Forming a plurality of gate wires and data wires crossing each other to define pixel regions on the substrate using the conductor pastes; Irradiating infrared rays to the gate wiring and the data wiring to dry and cure the wiring; Forming a thin film transistor at an intersection point of the gate line and the data line; And forming a matrix pixel electrode in each pixel region defined by being connected to the thin film transistor and crossing the gate wiring and the data wiring. The metal material of claim 9, wherein the metal material of the metal paste is Ni, Al, Au, Ag, Al, Pd / Ag, Cr, Ta, Cu, Ba, LaB ₆ , Ca _0.2 La _0.8 CrO ₃ , ITO, and SnO ₂ . A method of manufacturing a liquid crystal display device, characterized by using a material such as single or in combination. 10. The method of claim 9, wherein the gate line or the data line is formed using any one of a deposition method, a sputtering method, a screen printing method, a plating method, and a lift-off method according to a metal material.