KR19980085147A - Transverse electric field liquid crystal display device and manufacturing method thereof - Google Patents

Abstract

The transverse electric field liquid crystal display device of the present invention comprises a substrate, a gate wiring and a data wiring arranged on the substrate, a thin film transistor formed at an intersection of the gate wiring and the data wiring, and formed on the same layer in the pixel region, The common electrode and data electrode which apply a parallel electric field, and the oriented film apply | coated throughout the board | substrate are comprised. The passivation film and the gate insulating film are stacked only in the thin film transistor region to further increase the intensity of the electric field applied to the liquid crystal layer.

Description

Transverse electric field liquid crystal display device and manufacturing method thereof

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transverse electric field type liquid crystal display device. In particular, the gate insulating film and the protective film of a pixel are etched to form a common electrode and a data electrode on the same layer, thereby applying a strong transverse electric field to the liquid crystal layer, thereby improving the reaction speed of the liquid crystal. It relates to a transverse electric field type liquid crystal display device.

The twisted nematic mode liquid crystal display device, which is mainly used as a flat panel display device of high quality and low power, has a disadvantage of having a narrow viewing angle. This is due to the refractive anisotropy of the liquid crystal molecules, because the liquid crystal molecules oriented horizontally with the substrate are oriented almost perpendicular to the substrate when a voltage is applied to the liquid crystal panel.

Therefore, in-plane switching mode LCDs have been actively studied in recent years to solve the viewing angle problem by aligning liquid crystal molecules in a substantially horizontal direction with a substrate.

1 is a view showing the transverse electric field type liquid crystal display device. As shown in the figure, the gate wiring 1 and the data wiring 2 are vertically and horizontally arranged on the transparent first substrate 10. The pixel region is defined by the gate wiring 1 and the data wiring 2. The actual liquid crystal panel is composed of many pixel regions, but in the drawing, only one pixel is shown for convenience of description. The common line 16 parallel to the gate line 1 is arranged in the pixel area, and a thin film transistor is formed at the intersection of the gate line 1 and the data line 2. As shown in FIG. 2, the TFT is composed of a gate electrode 3, a gate insulating film 19, a source electrode 104a, a drain electrode 4b, a semiconductor layer 12, and an ohmic contact layer 13. One gate electrode 3 and the source electrode 4a are connected to the gate wiring 1 and the data wiring 2, respectively. The gate insulating film 12 is stacked over the entire substrate.

In the pixel region, a common electrode 7 and a data electrode 8 arranged in parallel with each other to apply a transverse electric field are formed. The common electrode 7 is formed on the first substrate 10 at the same time as the gate electrode 3 and connected to the common wiring 16. The data electrode 8 is disposed on the gate insulating film 19 and the source electrode 4a and the drain. It is formed simultaneously with the electrode 4b and connected to the drain electrode 4b of the TFT. The protective film 22 and the first alignment film 20a are applied over the entire first substrate 10.

The second substrate 11 is formed with a black matrix 15 and a color filter layer 25 for preventing light from leaking near the TFT, the gate wiring 1 and the data wiring 2. The second alignment film 20b is applied thereon. In addition, the liquid crystal layer 30 is formed between the first substrate 10 and the second substrate 11.

When no voltage is applied in the liquid crystal display device having the above-described structure, the liquid crystal molecules in the liquid crystal layer 30 are aligned in the alignment directions of the first alignment layer 20a and the second alignment layer 20b, but the common electrode 7 When a voltage is applied between the data electrode 8 and the data electrode 8, a transverse electric field parallel to the surface of the substrate 10 is applied between the common electrode 7 and the data electrode 8 to form a liquid crystal molecule in the liquid crystal layer 30. It is switched by the transverse electric field and is oriented in a direction substantially perpendicular to the extending direction of the common electrode 7 and the data electrode 8. As described above, since the liquid crystal molecules in the liquid crystal layer 30 are always switched on the same plane, gray level inversion does not occur in the vertical and horizontal viewing angle directions.

However, in the above-described liquid crystal display device, since the common electrode 7 is formed on the substrate 10 and the data electrode 8 is formed on the gate insulating film 19, between the positive electrodes 7 and 8, The applied electric field is not exactly parallel to the surface of the substrate 10. Therefore, the liquid crystal molecules in the liquid crystal layer 30 do not switch completely in parallel with the surface of the substrate 10, which causes a problem that the viewing angle is narrowed. In addition, the gate insulating film 19 between the common electrode 7 and the data electrode 8 causes the transverse electric field to be weakened, leading to a decrease in the switching speed of the liquid crystal molecules, that is, the reaction speed of the liquid crystal molecules. In addition, a protective film 22 having a thickness of about 0.2 μm is stacked on the data electrode 8, which is a very large amount, which is a major factor in decreasing the strength of the electric field between the electrodes 7 and 8. Therefore, the reaction rate of the liquid crystal molecules in the liquid crystal layer 30 is lowered, causing the screen to break when the moving image is implemented.

SUMMARY OF THE INVENTION An object of the present invention is to provide a transverse electric field type liquid crystal display device and a method of manufacturing the same, by forming a common electrode and a data electrode on the same layer and applying an electric field parallel to the surface of the substrate to the liquid crystal layer.

Another object of the present invention is to provide a transverse electric field type liquid crystal display device and a method of manufacturing the same, by improving the switching speed of the liquid crystal molecules by etching the gate insulating film and the protective film of the pixel region where the common electrode and the data electrode are formed. It is.

In order to achieve the above object, a transverse electric field type liquid crystal display device according to the present invention includes a first wiring and a second substrate, a gate wiring and a data wiring arranged vertically and horizontally on the first substrate to define a pixel region; A common wiring arranged substantially parallel to the gate wiring in one pixel region, a thin film transistor formed at an intersection of the gate wiring and the data wiring, a common electrode and a data electrode formed on the same layer in the pixel, and the thin film A protective film stacked on the transistor, a first alignment film coated over the entire first substrate and oriented, and a light shielding layer formed on the second substrate to prevent light leakage near the gate wiring, the data wiring, and the thin film transistor. Layer, the color filter layer formed on the light shielding layer, the second alignment film coated on the color filter layer and oriented, the first substrate and the second group. It is configured with a liquid crystal layer formed between the.

Since the gate insulating film and the protective film in the pixel region are etched, the common electrode and the data electrode are formed on the first substrate, and only the first alignment film is coated thereon. Therefore, the intensity of the electric field parallel to the surface of the substrate is further stronger than before. The semiconductor layer and the gate insulating layer of the thin film transistor are stacked along the gate line and the common line to prevent a short circuit between the gate line and the data line, between the common line and the data electrode, and between the gate line and the common electrode and the data electrode.

The method of manufacturing the transverse electric field type liquid crystal display device includes the steps of forming a gate wiring, a gate electrode, a common wiring, and a common electrode by laminating and etching a metal on a first substrate, and continuously forming inorganic materials and amorphous silicon over the entire substrate. Laminating, etching the inorganic material and amorphous silicon to form a gate insulating film and a semiconductor layer, laminating impurity amorphous silicon and a metal, and etching the metal to form a source / drain electrode and a data electrode. And etching the impurity amorphous silicon using the source / drain electrodes as a mask to form an ohmic contact layer, stacking and etching an organic material or an inorganic material to form a protective film in the thin film transistor region, and covering the entire first substrate. Coating and orienting the first alignment layer, forming a light blocking layer on the second substrate, and forming the light blocking layer. A second step of forming a color filter layer on a substrate, comprising the steps of: processing the coating and orienting the second alignment film on the above-described color filter layer, is composed of forming a liquid crystal layer between the above-described first and second substrates. The semiconductor layer and the gate insulating film are successively stacked and then etched at once.

1 is a plan view of a conventional liquid crystal display device.

FIG. 2 is a cross-sectional view taken along the line AA ′ of FIG. 1. FIG.

3 is a plan view of a liquid crystal display device according to the present invention;

FIG. 4A is a cross-sectional view taken along the line BB ′ of FIG. 3.

4B is a cross-sectional view taken along the line CC 'of FIG. 3.

5 is a view showing a method for manufacturing a liquid crystal display device according to the present invention.

-Explanation of symbols for the main parts of the drawing-

101: gate wiring 102: data wiring

103: gate electrode 104a: source electrode

104b: drain electrode 107: common electrode

108: data electrode 110: first substrate

111: second substrate 112: semiconductor layer

113: ohmic contact layer 116: common wiring

119: gate insulating layer 120: alignment layer

122: protective film 125: color filter layer

130: liquid crystal layer

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

3 and 4 are views showing a transverse electric field type liquid crystal display device according to the present invention. As shown in FIG. 3, the gate wiring 101 and the data wiring 102 are vertically and horizontally arranged on the first substrate 110 to define a pixel area. In the pixel area, the common wiring 116 parallel to the gate wiring 101 is arranged. A thin film transistor is formed at the intersection of the gate wiring 101 and the data wiring 102, so that the gate electrode 103 of the thin film transistor is connected to the gate wiring 101 and the source electrode 104a is connected to the data wiring 102. do. The common electrode 107 and the data electrode 108 which are substantially parallel to each other are formed in the pixel area. The common electrode 107 is connected to the common wiring 116 and the data electrode 108 is connected to the drain electrode 104b. do.

As shown in FIG. 4A, the common electrode 107 and the data electrode 108 are formed on the same layer as in the prior art. That is, in the present invention, the gate insulating film 119 and the protective film 122 are laminated only in the TFT region, whereas the gate insulating film 119 and the protective film 122 are stacked over the entire substrate 110. 107 and a protective film 108 are formed on the first substrate 110. In addition, the gate insulating film 119 is stacked along the gate wiring 101 and between the common wiring 116 and the data electrode 108 to form the gate wiring 101 and the data wiring 102 and the common wiring ( A short circuit between the 116 and the data electrode 108 is prevented. In this case, the gate insulating film 119 stacked along the gate wiring 101 is formed to completely cover the gate wiring 101, as shown in FIG. 4B, so that the common electrode 107 and the data electrode (in the pixel region) are formed. 108) and short circuit to prevent occurrence.

As described above, when the common electrode 107 and the data electrode 108 are disposed on the same layer, a complete transverse electric field is applied to the liquid crystal layer 130. In addition, since the electric field is directly applied to the liquid crystal layer 130 without passing through the gate insulating film 119 and the passivation film 122, the strength of the electric field is not weakened by the films 119 and 122 so that the reaction of the liquid crystal molecules. It's faster.

Although the common electrode 107 and the data electrode 108 are formed on the first substrate 110 in the drawing, other configurations in which the above-described electrodes 107 and 108 are formed on the same layer are also possible. In other words, the gate insulating film 119 may be stacked on the entire first substrate 110, and both electrodes 107 and 108 may be formed thereon, and the passivation layer 122 may be formed on the entire first substrate 110. It is also possible, of course, to be formed thereon after being laminated over. In this case, the common wiring 116 and the common electrode 107 may be connected to each other by being arranged on the gate insulating film 119 or the protective film 122, or may be connected to each other through holes formed in the gate insulating film 119 or the protective film 122. have.

A semiconductor layer 112 is formed on the gate insulating film 119 of the TFT as shown in Fig. 4A. In addition, as shown in FIG. 3, the semiconductor layer 112 is laminated between the gate line 101 and the data line 102 and between the common line 116 and the data electrode 108 to prevent a short circuit. .

Then, the first alignment layer 122a is coated and aligned on the entire first substrate 110 to determine the alignment direction.

The second substrate 111 is provided with a black matrix 115, which is a light blocking layer that prevents light leakage around the gate wiring 101, the data wiring 102, and the TFT, and the color filter layer 125 is stacked thereon. R, G, and B are repeated in each pixel. On the color filter layer 125, a second alignment layer 122b is applied and oriented to determine the alignment direction. An overcoat layer may be formed between the color filter layer 125 and the second alignment layer 122b to improve flatness.

As described above, in the liquid crystal display device of the present invention, since the common electrode 107 and the data electrode 108 are formed on the same layer, when a voltage is applied between the two electrodes 107 and 108, An electric field is applied that is completely parallel to the surface of the substrate. Accordingly, the liquid crystal molecules in the liquid crystal layer 130 are completely parallel to the surface of the substrate, thereby improving viewing angle characteristics. In addition, since an electric field generated between the common electrode 107 and the data electrode 108 does not pass through the gate insulating film 119 and the passivation film 122, a strong electric field is applied to the liquid crystal layer 130. Therefore, the switching speed of the liquid crystal molecules in the liquid crystal layer 130 is improved, which means that the reaction speed of the liquid crystal is improved.

5 is a view showing a method of manufacturing a transverse electric field type liquid crystal display device according to the present invention. First, as shown in FIG. 5A, metals such as Ta, Cr, Mo, Al, and Al alloys are stacked and etched on the first substrate 110 by a sputtering method to etch the gate electrode 103 and the common substrate. An electrode 107 is formed. In this case, although not shown in the drawing, the gate wiring 101 and the common wiring 116 are simultaneously formed when the gate electrode 103 and the common electrode 107 are formed. In addition, in order to improve insulation, the gate electrode 103 and the common electrode 107 may be anodized to form an anodization layer. Subsequently, as shown in FIG. 5 (b), inorganic materials such as SiOx or SiNx and amorphous silicon (a-Si) are successively laminated by PECVD (Plasma Enhanced Chemical Vapor Deposition) method, and then the inorganic materials and a-Si are simultaneously stacked. By etching, the gate insulating film 119 and the semiconductor layer 112 are formed. 3 and 5 (b), the gate insulating film 119 and the semiconductor layer 112 are formed along the gate wiring 101 and the common wiring 116. Subsequently, as shown in FIG. 5 (c), n ⁺ a-Si is deposited by PECVD, and metals such as Cr, Ti, Al, and Al alloys are deposited on the sputtering method, and then etched to form a source electrode 104a. And a drain electrode 104b and a data electrode 108. The n ⁺ a-Si is etched using the source electrode 104a and the drain electrode 104b as a mask to form an ohmic contact layer. And form 113. An etching stopper layer may be formed on the semiconductor layer 112 of the TFT to prevent the semiconductor layer 112 from being etched when the n ⁺ layer is etched.

Thereafter, as shown in FIG. 5 (d), an inorganic material such as SiOx or SiNx or an organic material such as benzocyclobutane (BCB) is laminated and etched to form a protective film 122 in the TFT region, and then over the entire substrate 110. The first alignment film 122a is applied. Polyimide or photoreactive material is used as the alignment layer. In the case of using the polyimide as an alignment layer, a mechanical method such as rubbing is used to determine the alignment direction of the alignment layer, but in the case of using a photoreactive substance such as polyvinylcinnamate (PVCN) or polysiloxane (polysiloxane) The alignment direction is determined by irradiating the alignment film with light such as ultraviolet rays. In particular, since the orientation direction determined by the photoreactive alignment layer varies depending on the inherent properties of the light, such as the polarization direction of the irradiated light, it is possible to solve the problem of dust or static electricity generated in the alignment layer when mechanical rubbing is used. do.

Thereafter, after forming the black matrix 115, the color filter layer 125, and the second alignment layer 122b made of Cr or CrO on the second substrate, the first substrate 110 and the second substrate 111 in a vacuum state. The liquid crystal is injected between the two to complete the transverse electric field type liquid crystal display device.

In the present invention, as described above, since the common electrode and the data electrode are formed on the same layer, the electric field applied in the liquid crystal is completely parallel to the surface of the substrate. Therefore, when the voltage is applied, the liquid crystal molecules in the liquid crystal layer are switched in a state parallel to the surface of the substrate, so that the viewing angle is improved compared with the prior art. In addition, since the gate insulating film and the protective film are stacked only in the TFT region excluding the pixel region, the intensity of the electric field applied in the liquid crystal becomes stronger than before. Accordingly, the switching speed of the liquid crystal molecules is improved, thereby preventing the screen from being broken when the moving image is implemented.

Claims (21)

A first substrate and a second substrate; Gate wiring and data wiring arranged on the first substrate to define a pixel region; A common wiring arranged in parallel with the gate wiring in the pixel region; A thin film transistor formed at an intersection point of the gate line and the data line; At least one pair of parallel first and second electrodes formed on the same layer of the pixel region; A transverse electric field liquid crystal display device comprising a passivation layer stacked on the thin film transistor. The transverse electric field liquid crystal display device according to claim 1, wherein the first electrode and the second electrode are a common electrode and a data electrode, respectively. According to claim 1, wherein the thin film transistor, A gate electrode connected to the gate wiring and the common electrode; An insulating film stacked on the gate electrode; A semiconductor layer laminated on the insulating film; An ohmic contact layer stacked on the semiconductor layer; And a source electrode and a drain electrode formed on the ohmic contact layer and connected to the data wiring and the data electrode. The transverse electric field liquid crystal display device according to claim 3, wherein the insulating film is formed on the thin film transistor region, the gate wiring and the common wiring. The transverse electric field liquid crystal display device according to claim 1, wherein the first electrode and the second electrode are formed on a first substrate. 4. The transverse electric field liquid crystal display device according to claim 3, wherein the insulating film is stacked over the entire first substrate. The transverse electric field liquid crystal display device according to claim 6, wherein the first electrode and the second electrode are formed on an insulating film. The transverse electric field liquid crystal display device according to claim 1, wherein the alignment film is polyimide. The transverse electric field liquid crystal display device according to claim 1, wherein the alignment layer is a photoreactive material. 10. The transverse electric field liquid crystal display device according to claim 9, wherein the photoreactive material is selected from the group consisting of a polyvinylcinnamate (PVCN) material and a polysiloxane material. The transverse electric field liquid crystal display device of claim 1, further comprising a light blocking layer formed on the second substrate to prevent light from leaking near the thin film transistor, the gate wiring, and the data wiring. The method of claim 1, A color filter layer laminated on the second substrate; An alignment film coated on at least one substrate of the first substrate and the second substrate; The transverse electric field liquid crystal display device further comprising a liquid crystal layer formed between the first substrate and the second substrate. Providing a first substrate and a second substrate; Stacking and etching a metal on the first substrate to form a gate wiring, a gate electrode, a common wiring, and a common electrode; Forming an insulating film and a semiconductor layer on the gate electrode; Forming an ohmic contact layer on the semiconductor layer; Stacking and etching metal to form a source electrode and a drain electrode on the ohmic contact layer, and forming a data electrode on the first substrate; A method of manufacturing a transverse electric field type liquid crystal display device comprising the step of laminating a protective film on the source / drain electrodes and the semiconductor layer. The method of claim 13, wherein the forming of the insulating film and the semiconductor layer, Stacking an insulating material and a semiconductor material over the substrate; And etching the insulating material and the semiconductor material to form an insulating film and a semiconductor layer on the gate electrode, the gate wiring, and the common wiring. The method of manufacturing a transverse electric field type liquid crystal display device according to claim 14, wherein the insulating material and the semiconductor material are sequentially stacked. The method of manufacturing a transverse electric field type liquid crystal display device according to claim 14, wherein the insulating material and the semiconductor material are etched at once. The method of claim 13, further comprising forming a light shielding layer on the second substrate. The method of claim 13, wherein the forming of the source electrode, the drain electrode, and the ohmic contact layer includes: Stacking an impurity semiconductor material on the semiconductor layer; Depositing a metal on the impurity semiconductor material; Etching the metal to form a source electrode and a drain electrode; And etching the impurity semiconductor material using the source electrode and the drain electrode as a mask to form an ohmic contact layer. The method of claim 13, Applying an alignment layer to the first substrate; A method of manufacturing a transverse electric field type liquid crystal display device, characterized in that the step of aligning the alignment film is further configured. The method of claim 13, Applying an alignment layer on the color filter layer, A method of manufacturing a transverse electric field type liquid crystal display device, characterized in that the step of aligning the alignment film is further configured. The method of claim 13, Forming a color filter layer on the second substrate; And forming a liquid crystal layer by injecting a liquid crystal between the first substrate and the second substrate to form a liquid crystal layer.