KR20110072310A - Liquid crystal display device and method of fabricating thereof - Google Patents

Abstract

PURPOSE: A liquid crystal display device and a method for fabricating the same are provided to reduce driving power by placing a common electrode and a pixel electrode perpendicularly and forming a mesh shape. CONSTITUTION: A plurality of pixels are defined by a plurality of gate lines(103) formed on a first substrate and data lines(104). TFTs(Thin Film Transistors) are arranged in each pixel. One or more common electrode(105) is arranged in the pixels in parallel with the data lines. One or more pixel electrode(107) is perpendicularly arranged in the pixel in parallel with the common electrode. The pixel electrode forms an electric field with the common electrode.

Description

Transverse electric field mode liquid crystal display device and its manufacturing method {LIQUID CRYSTAL DISPLAY DEVICE AND METHOD OF FABRICATING THEREOF}

The present invention relates to a transverse electric field mode liquid crystal display device and a method of manufacturing the same, and more particularly, to a transverse electric field mode liquid crystal display device having a minimum power consumption and improved transmittance.

Recently, with the development of various portable electronic devices such as mobile phones, PDAs, and notebook computers, there is a growing demand for flat panel display devices for light and thin applications. Such flat panel displays are being actively researched, such as LCD (Liquid Crystal Display), PDP (Plasma Display Panel), FED (Field Emission Display), VFD (Vacuum Fluorescent Display), but mass production technology, ease of driving means, Liquid crystal display devices (LCDs) are in the spotlight for reasons of implementation.

The liquid crystal display device has various display modes according to the arrangement of the liquid crystal molecules. However, the liquid crystal display device of the TN mode is mainly used because of the advantages of easy monochrome display, fast response speed, and low driving voltage. In such a TN mode liquid crystal display, liquid crystal molecules oriented horizontally with the substrate are almost perpendicular to the substrate when a voltage is applied. Therefore, there is a problem that the viewing angle is narrowed upon application of voltage due to the refractive anisotropy of the liquid crystal molecules.

In order to solve this viewing angle problem, liquid crystal display devices of various modes having wide viewing angle characteristics have recently been proposed, but among them, the liquid crystal display device of the lateral field mode (In Plane Switching Mode) is applied to actual production. It is produced. The IPS mode liquid crystal display device aligns liquid crystal molecules in a plane by forming at least one pair of electrodes arranged in parallel in a pixel to form a transverse electric field substantially parallel to the substrate.

1 is a view showing the structure of a conventional IPS mode liquid crystal display device. FIG. 1A is a plan view and FIG. 1B is a sectional view taken along the line II ′ of FIG. 1A. As shown in FIG. 1A, pixels of the liquid crystal panel 1 are defined by gate lines 3 and data lines 4 arranged vertically and horizontally. Although only the (n, m) th pixels are shown in the drawing, in the liquid crystal panel 1, n and m gate lines 3 and data lines 4 are disposed, respectively, and thus the liquid crystal panel 1 is disposed. N x m pixels are formed throughout. The thin film transistor 10 is formed at the intersection of the gate line 3 and the data line 4 in the pixel. The thin film transistor 10 includes a gate electrode 11 to which a scan signal is applied from the gate line 3, and a semiconductor layer formed on the gate electrode 11 and activated as a scan signal is applied to form a channel layer. 12 and a source electrode 13 and a drain electrode 14 formed on the semiconductor layer 12 and to which an image signal is applied through the data line 4. The image signal input from the outside is applied to the liquid crystal layer. do.

In the pixel, a plurality of common electrodes 5 and a pixel electrode 7 are arranged substantially parallel to the data line 4. In addition, a common line 16 connected to the common electrode 5 is disposed in an upper region of the pixel, and a pixel electrode line 18 connected to the pixel electrode 7 is disposed on the common line 16. It overlaps with the common line 16. Storage capacitance is formed in the transverse electric field mode liquid crystal display by overlapping the common line 16 and the pixel electrode line 18.

In the IPS mode liquid crystal display device configured as described above, the liquid crystal molecules are aligned substantially in parallel with the common electrode 5 and the pixel electrode 7. When the thin film transistor 10 is operated to apply a signal to the pixel electrode 7, a transverse electric field substantially parallel to the liquid crystal panel 1 is generated between the common electrode 5 and the pixel electrode 7. Since the liquid crystal molecules rotate on the same plane along the transverse electric field, gray level inversion due to the refractive anisotropy of the liquid crystal molecules can be prevented.

The conventional IPS mode liquid crystal display device having the above structure will be described in more detail with reference to the cross-sectional view of FIG. 1B.

As shown in FIG. 1B, a gate electrode 11 is formed on the first substrate 20, and a gate insulating layer 22 is stacked over the entire first substrate 20. The semiconductor layer 12 is formed on the gate insulating layer 22, and the source electrode 13 and the drain electrode 14 are formed thereon. In addition, a passivation layer 24 is formed on the entire first substrate 20.

In addition, a plurality of common electrodes 5 are formed on the first substrate 20, and a pixel electrode 7 and a data line 4 are formed on the gate insulating layer 22 to form the common electrode 5. The transverse electric field E is generated between the pixel electrodes 7.

The black matrix 32 and the color filter layer 34 are formed on the second substrate 30. The black matrix 32 is to prevent light leakage into an area where the liquid crystal molecules do not operate. As shown in the drawing, the black matrix 32 is formed between the region of the thin film transistor 10 and between the pixel and the pixel (ie, the gate line and the data line). Area). The color filter layer 34 is composed of R (Red), B (Blue), and G (Green) to realize actual colors.

The liquid crystal layer 40 is formed between the first substrate 20 and the second substrate 30 to complete the liquid crystal panel 1.

As described above, in the IPS mode liquid crystal display device, the transverse electric field E is formed inside the liquid crystal layer 40 by the common electrode 5 and the pixel electrode 7 formed on the substrate 20 and the gate insulating layer 22, respectively. Is generated to drive the liquid crystal molecules inside the liquid crystal layer 40.

In the IPS mode liquid crystal display device having the above structure, since the liquid crystal molecules are oriented by rotating along the transverse electric field, gray scale inversion due to the refractive index anisotropy of the liquid crystal molecules can be prevented. Therefore, a wider viewing angle can be obtained than in a twisted nematic (TN) mode liquid crystal display device, and as a result, a wide viewing angle can be realized.

Meanwhile, in the TN mode liquid crystal display device, a transparent metal such as ITO (Indium Tin Oxide) is mainly used as the common electrode and the pixel electrode, while in the IPS mode liquid crystal display device, an opaque metal is mainly used as the common electrode and the pixel electrode. do. Therefore, the IPS mode liquid crystal display device has a problem that the transmittance is lower than that of the TN mode liquid crystal display device.

In addition, in the IPS mode liquid crystal display device, the common electrode 5 and the pixel electrode 7 should be disposed more than a predetermined interval in order to secure the transmittance and the aperture ratio. However, in this case, in order to switch the liquid crystal molecules, the set voltage is the common electrode ( 5) and the pixel electrode 7, the power consumption is large.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and the transverse electric field mode liquid crystal display device and its manufacturing method which can reduce driving power and improve transmittance by forming a common electrode and a pixel electrode perpendicular to each other to form a mesh shape. It aims to provide.

In order to achieve the above object, the transverse electric field mode liquid crystal display device according to the present invention comprises a plurality of pixels defined by a plurality of gate lines and data lines formed on the first substrate; A thin film transistor disposed in each pixel; At least one common electrode arranged in parallel with the data line in a pixel; At least one pixel electrode arranged vertically with the common electrode in the pixel to form a common electrode and an electric field, wherein the common electrode and the pixel electrode cross each other with an insulating layer therebetween.

The thin film transistor includes a gate electrode formed on a first substrate, a gate insulating layer formed on the gate electrode, a semiconductor layer formed on the gate insulating layer, a source electrode and a drain formed on the semiconductor layer and connected to a data line of the corresponding pixel. An electrode, and a protective layer formed on the source electrode and the drain electrode,

The gate electrode includes a first gate electrode made of a transparent conductive material formed on a first substrate and a second gate electrode formed of a metal on the first gate electrode. In this case, the common electrode is formed on the first substrate and the pixel electrode is formed on the protective layer.

In addition, the method of manufacturing a transverse electric field mode liquid crystal display device according to the present invention comprises the steps of: laminating a transparent conductive material, a metal and a first photoresist layer on a first substrate; After the first photoresist layer is developed by a first diffraction mask to form a first photoresist pattern and a second photoresist pattern having a different thickness, the transparent conductive layer is formed by the first photoresist pattern and the second photoresist pattern. Forming a gate electrode, a common electrode, and a metal layer disposed on the common electrode, the gate electrode including a transparent conductive layer and a metal layer for etching a material and a metal; Acing the first photoresist pattern and the second photoresist pattern to remove the second photoresist pattern; Etching the metal layer on the common electrode by means of an aced first photoresist pattern; Depositing a semiconductor material, a metal, and a second photoresist layer on the first substrate; Developing and etching the second photoresist layer by a second diffraction mask to form a semiconductor layer, a source electrode and a drain electrode on the gate electrode; And forming a protective layer on the first substrate and forming a pixel electrode thereon.

The forming of the semiconductor layer, the source electrode and the drain electrode may include developing third photoresist patterns having different thicknesses by developing the second photoresist layer, and forming a semiconductor material and a metal by the third photoresist pattern. Etching to form a semiconductor layer and a metal layer, acing the third photoresist pattern to expose a central region of the metal layer, and blocking the metal layer by the aced third photoresist pattern. Etching the metal layer to form a source electrode and a drain electrode.

The forming of the pixel electrode may include forming a protective layer on a first substrate, forming a contact hole in the protective layer, laminating a transparent conductive material on the protective layer, and forming the transparent conductive material. Etching the material.

In the present invention, the common electrode and the pixel electrode are disposed perpendicular to each other to form a mesh shape, thereby reducing driving power and improving transmittance.

Further, in the present invention, since the gate electrode made of the transparent conductive material and the metal and the common electrode and the pixel electrode made of the transparent conductive material are formed by the four masks, the manufacturing process can be simplified and the manufacturing cost can be reduced.

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

2 is a plan view showing the structure of a transverse electric field mode liquid crystal display device according to the present invention.

As illustrated in FIG. 2, pixels of the liquid crystal panel 101 are defined by gate lines 103 and data lines 104 arranged vertically and horizontally. Although only the (n, m) th pixels are shown in the figure, n and m gate lines 103 and data lines 104 are arranged in the liquid crystal panel 101, respectively, so that the liquid crystal panel 101 is disposed. N x m pixels are formed throughout. The thin film transistor 110 is formed at the intersection of the gate line 103 and the data line 104 in the pixel.

The thin film transistor 110 is formed on the gate line 103 and is activated as a scan signal is applied to the gate line 103 to form a channel layer, and is formed on the semiconductor layer 112. And a source electrode 113 and a drain electrode 114 for applying an image signal applied from an external driving circuit through the data line 104 to the liquid crystal layer (not shown).

In this case, the region of the gate line 103 on which the semiconductor layer 112 is formed substantially serves as a gate electrode of the thin film transistor 110, and thus, the region of the gate line 103 serves as the gate electrode 111 of the thin film transistor 110. In the following description, this region will be described as the gate electrode 111.

The common electrode 105 and the pixel electrode 107 are disposed in the pixel. The common electrode 105 is formed in parallel with the data line 104 and the pixel electrode 107 is disposed in parallel with the gate line 103. In addition, the common electrode 105 is connected in the pixel, and the first common line 115a and the second common line 115b for applying a scan signal to the common electrode 105 are disposed in the lower region and the upper region of the pixel. It is disposed parallel to the gate line 103. In the pixel, pixel electrode lines 117a, 117b, and 117c connected to the pixel electrode 107 to apply a data signal to the pixel electrode 107 are disposed. In this case, the first pixel electrode line 117a is disposed in the lower region of the pixel in parallel with the gate line 103, and the second pixel electrode line 117b and the second pixel electrode line 117c have data in the left and right regions of the pixel. Disposed parallel to line 104.

The first common line 115a and the first pixel electrode line 117a are disposed to overlap each other in the lower region of the pixel to form a storage capacitor.

As the common electrode 105 is disposed in parallel with the data line 104 and the pixel electrode 107 is disposed in parallel with the gate line 103, the common electrode 105 and the pixel electrode 107 are perpendicular to each other. Are arranged to intersect. Although not shown in the drawing, an insulating layer is formed between the common electrode 105 and the pixel electrode 107, so that the common electrode 105 and the pixel electrode 107 are electrically insulated from each other.

Since the common electrode 105 and the pixel electrode 107 cross each other and the crossing region overlaps with the insulating layer interposed therebetween, the storage capacitor is formed by the crossing region. As described above, the storage capacitance can be formed not only by the overlap region of the first common line 115a and the first pixel electrode line 117a but also by the overlap region of the common electrode 105 and the pixel electrode 107. Even if the widths of the first common line 115a and the first pixel electrode line 117a are reduced, a desired sufficient accumulation capacity can be ensured.

3 is a cross-sectional view taken along line II ′ of FIG. 2, and the present invention will be described in more detail with reference to this. In this case, for convenience of explanation, the cross section is cut in the width direction of the common electrode 105 and the pixel electrode 107 of FIG. 2.

As shown in FIG. 3, a gate electrode 111 and a common electrode 105 are formed on a first substrate 120 made of a transparent insulating material such as glass, and a gate is formed over the entire first substrate 120. The insulating layer 122 is laminated | stacked.

In this case, the gate electrode 111 is formed of a double layer of the first gate electrode 111a and the second gate electrode 111b, and the first gate electrode 111 is formed of indium tin oxide (ITO) or IZO (ITO). It is formed of a transparent conductive material such as Indium Zin Oxide and the second gate electrode 111b is made of a metal such as copper. In addition, the common electrode 105 is made of a transparent conductive material such as ITO or IZO.

The semiconductor layer 112 is formed on the gate insulating layer 122, and a source electrode 113 and a drain electrode 114 are formed thereon, respectively. In addition, a passivation layer 124 is formed on the entire first substrate 120.

In addition, the pixel electrode 107 is formed on the passivation layer 124. In this case, the pixel electrode 107 is made of a transparent conductive material such as ITO or IZO, and is electrically connected to the drain electrode 114 of the thin film transistor through a contact hole 125 formed in the protective layer 124. do.

The common electrode 105 extends in parallel with the data line 104 and the pixel electrode 107 extends in parallel with the gate line 103 so that the common electrode 105 and the pixel electrode 107 mesh with each other. ) Is shaped.

The black matrix 132 and the color filter layer 134 are formed on the second substrate 130, and the liquid crystal layer 140 is formed between the first substrate 120 and the second substrate 130 to form a liquid crystal panel ( 101) is completed.

As described above, in the present invention, since the common electrode 105 and the pixel electrode 107 cross each other vertically and have a mesh shape, the common electrode 105 and the pixel electrode 107 are applied to the liquid crystal layer as compared to the structure in which the common electrode and the pixel electrode are arranged in parallel with each other. The electric field is distributed differently, and as a result, the switching of the liquid crystal molecules is different.

4A to 4C are diagrams illustrating an electric field generated by the common electrode 105 and the pixel electrode 107 arranged in a mesh shape in the liquid crystal display according to the present invention and switching of the liquid crystal molecules 144 by the electric field. to be.

First, as shown in FIG. 4A, the common electrode 105 and the pixel electrode 107 are arranged in a mesh shape, and the alignment direction of the alignment layer formed in the liquid crystal display is 0 °, that is, horizontally with the data line 104. In this case, since no electric field is formed in the liquid crystal layer 140 unless a signal is applied to the common electrode 105 and the pixel electrode 107, the liquid crystal molecules 144 are in a direction of 0 °, that is, the data line 104. It is arranged horizontally.

As shown in FIG. 4B, when a signal is applied to the common electrode 105 and the pixel electrode 107, since the first electric field E1 is formed along the diagonal direction of the mesh shape, the liquid crystal molecules are formed in the first electric field. Arranged along E1. In this case, since the common electrode 105 and the pixel electrode 107 have a rectangular shape, the distance between the common electrode 105 and the pixel electrode 107 is the longest in the diagonal direction and the length becomes smaller toward the left and right in the diagonal direction. Lose. That is, the width of the common electrode 105 and the pixel electrode 107 and the distance between the electrode and the electrode in the transverse electric field mode liquid crystal display device according to the present invention are the same as those of the common electrode and the pixel electrode in the conventional transverse electric field mode liquid crystal display device. Assuming that the width is equal to the distance between the electrode and the electrode, the width of the horizontal electrode according to the present invention is compared with the distance between the common electrode and the pixel electrode in the conventional horizontal field mode liquid crystal display device in which the common electrode and the pixel electrode are disposed in parallel with each other. In the field mode liquid crystal display device, the average distance between the common electrode 105 and the pixel electrode 107 (average distance of the entire rectangular shape) becomes shorter.

Therefore, under the same conditions (i.e., the width of the same electrode and the distance between electrodes), the intensity of the electric field E1 in the transverse electric field mode liquid crystal display device according to the present invention is larger than that of the conventional transverse electric field mode liquid crystal display device. As a result, even when the driving voltage is lowered in the transverse electric field mode liquid crystal display device according to the present invention, the same effects as in the related art can be obtained.

FIG. 4C is a cross-sectional view taken along the line II-II 'of FIG. 4B and shows the electric field E2 of the common electrode 105 and the pixel electrode 107. As shown in FIG. 4C, the common electrode 105 is formed on the first substrate 120, and the pixel electrode 107 is formed on the passivation layer 124. In this case, the common electrode 105 and the pixel electrode 107 are insulated by the gate insulating layer 122 and the protective layer 124.

4C is a plane cut along the longitudinal direction of the common electrode 105. In the drawing, the common electrode 105 is disposed on the entire first substrate 120, and the pixel electrode 107 has a predetermined width. It is arranged in a band shape. Therefore, in the overlapping region of the common electrode 105 and the pixel electrode 107 with the gate insulating layer 122 and the protective layer 124 interposed therebetween, the upper surface of the common electrode 105 and both sides of the pixel electrode 107. The second electric field E2 is formed in between. The electric field is a kind of fringe field, and the second electric field E2 is present not only between the common electrode 105 and the pixel electrode 107 but also on a part of the upper surface of the pixel electrode 107. Accordingly, since the liquid crystal molecules of the liquid crystal layer 140 corresponding to the upper portion of the upper portion of the pixel electrode 107 are switched by the second electric field E2, light is transmitted to the region, and as a result, the transmittance is improved. do.

As described above, in the transverse electric field mode liquid crystal display device according to the present invention, since the strong electric field is formed between the common electrode 105 and the pixel electrode 107 as compared to the conventional transverse electric field mode liquid crystal display device, the liquid crystal display is performed. The driving voltage of the device can be reduced, and since the second electric field E2, which is a fringe field, is formed between the overlapping common electrode 105 and the pixel electrode 107, the upper surface of the pixel electrode 107 operates as a transmission region. It is possible to improve the transmittance.

Hereinafter, a method of manufacturing a transverse electric field mode liquid crystal display device having the above structure will be described in detail with reference to the accompanying drawings.

5A to 5K are views showing an example of a method of manufacturing a liquid crystal display device according to the present invention. For convenience of description, the drawing is divided into a pixel region in which a thin film transistor and an electrode are formed, and a pad region in which a gate pad and a data pad are formed.

First, as illustrated in FIG. 5A, a first transparent conductive layer 211a and a first metal layer 211b are successively stacked on a first substrate 120 made of a transparent material such as glass and including a pixel region and a pad region. After the formation, the photoresist is applied thereon to form the first photoresist layer 181. In this case, the first transparent conductive layer 211a is formed by depositing a transparent conductive material such as ITO or IZO by sputtering, and the first metal layer 211b is formed by depositing a metal such as copper by sputtering. .

As described above, after the first mask 190 is positioned on the first substrate 120 on which the first photoresist layer 181 is formed, the first photoresist layer 181 is irradiated with light such as ultraviolet rays. Develop. In this case, the first mask 190 is a diffraction mask or a half tone mask, and includes a transmission region 190a, a diffraction region 190b (or a semi-transmission region), and a blocking region 190c.

As shown in FIG. 5B, as light is irradiated and developed through the first mask 190, the light is irradiated onto the first photoresist layer 181 and a developer is applied to the first photoresist layer. Reference numeral 181 is developed to form a first photoresist pattern 181a, a second photoresist pattern 181b, and a third photoresist pattern 181c.

The first photoresist pattern 181a, the second photoresist pattern 181b, and the third photoresist pattern 181c may be formed by blocking an area of the first metal layer 211b with an etchant to operate the first solution. When the transparent conductive layer 211a is etched, as shown in FIG. 5C, the first gate electrode 111a, the second gate electrode 111b, and the common electrode in the pixel area on the first substrate 120 are disposed. 105 and the upper metal layer 105a are formed, and the first gate pad 165a and the second gate pad 165b are formed in the pad region.

Subsequently, the developed first photoresist pattern 181a, the second photoresist pattern 181b, and the third photoresist pattern 181c are ashed, and then the first photoresist is ashed as shown in FIG. 5D. The metal layer 105a of the pixel area is etched by blocking the pattern 181a, the second photoresist pattern 181b, and the third photoresist pattern 181c to form a common electrode (not shown) on the first substrate 120 of the pixel area. Only 105) remains.

Thereafter, as shown in FIG. 5E, the gate insulating layer 122, the semiconductor layer 112a, and the second metal layer 113a are successively stacked on the first substrate 120, and the second photoresist layer ( 182).

The gate insulating layer 122 is formed by stacking an inorganic material such as SiO ₂ or SiN ₂ by PECVD (Plasma Enhanced Chemical Vapor Deposition), and the semiconductor layer 113a is formed of amorphous silicon (a-Si) by PECVD. It is formed by laminating the back. The second metal layer 113a is formed by stacking a metal such as Mo by the sputtering method.

After the second mask 191 is disposed on the second photoresist layer 182, the second photoresist layer 182 is developed by irradiating light such as ultraviolet rays and applying a developer to form a photoresist pattern. .

In this case, the second mask 191 is a diffraction mask or a half tone mask, and includes a transmission region 191a, a diffraction region 191b (or a semitransmissive region), and a blocking region 191c.

Subsequently, as shown in FIG. 5F, the second metal layer 113a and the semiconductor are blocked while the second metal layer 113a is blocked by the first photoresist pattern 182a and the second photoresist pattern 182b. The layer 112a is etched to form the semiconductor layer 112 and the metal layer 113b on the gate electrodes 111a and 111b of the pixel region, and the semiconductor layer 112b and the source pad 167 are formed in the pad region.

In this case, the first photoresist pattern 182a is formed to have a thickness smaller than that of the side surface corresponding to the gate electrodes 111a and 111b.

Subsequently, as illustrated in FIG. 5G, the first photoresist pattern 182a and the second photoresist pattern 182b are ashed to expose the metal layer 113b in the region corresponding to the gate electrodes 111a and 111b. In this state, as shown in FIG. 5H, the exposed metal layer 113b is etched to form the source electrode 113 and the drain electrode 114.

Thereafter, as shown in FIG. 5I, an inorganic material such as SiO ₂ or SiN ₂ or an organic material such as photo acryl is coated on the entire first substrate 120 to form a protective layer 124. And etching to form a first contact hole 125 exposing the drain electrode 114 of the thin film transistor in the pixel region, and a second contact exposing the second gate pad 165b and the data pad 167 of the pad region, respectively. The hole 127 and the third contact hole 128 are formed. Subsequently, a transparent conductive material such as ITO or IZO is coated on the protective layer 124 and then etched to form a pixel electrode 107 in the pixel region as shown in FIG. 5J, and a second gate pad ( A first transparent metal layer 166 connected to 165a and a second transparent metal layer 168 connected to the data pad 167 are formed.

Subsequently, as shown in FIG. 5K, after forming the black matrix 132 and the color filter layer 134 on the second substrate 130, the first substrate 120 and the second substrate 130 are bonded to each other. By forming the liquid crystal layer 140 in between, the liquid crystal display device is completed. The black matrix 132 is formed by stacking and etching a metal oxide such as CrO or CrO ₂ or by applying and etching black resin or the like.

The liquid crystal layer 140 may be formed by bonding the first substrate 120 and the second substrate 130 and then injecting a liquid crystal therebetween, and forming the first substrate 120 or the second substrate ( After dispensing the liquid crystal onto the 130, the first substrate 120 and the second substrate 130 are bonded to each other to form the liquid crystal evenly distributed throughout the first substrate 120 and the second substrate 130. You could do it.

As described above, in the transverse electric field mode liquid crystal display device according to the present invention, four masks are used to form the transverse electric field mode liquid crystal display device. That is, a mask for forming the gate electrodes 111a and 111b and the common electrode 105 and the gate pads 165a and 165b, a mask for forming the semiconductor layer 112 and the source electrode 113 and the data pad 167, and a contact hole. (125, 127, 128) forming mask and pixel electrode 107 forming mask are used. Thus, minimizing the number of masks can simplify the process and reduce the manufacturing cost. Furthermore, in the present invention, since the gate electrodes 111a and 111b having two layers and the common electrode 105 having one layer can be formed by using a single mask of a diffraction mask or a halftone mask, the process is further simplified. The manufacturing cost can be further reduced.

6A to 6J illustrate another example of a method of manufacturing a liquid crystal display device according to the present invention. For convenience of description, the drawing is divided into a pixel region in which a thin film transistor and an electrode are formed, and a pad region in which a gate pad and a data pad are formed.

First, as shown in FIG. 6A, a first gate electrode 211a and a second gate electrode 211b are common to a first substrate 220 made of a transparent material such as glass and including a pixel region and a pad region. The electrode 205 and the metal layer 205, the first gate pad 265a and the second gate pad 265b are formed.

The first gate electrode 211a, the second gate electrode 211b, the common electrode 205, the metal layer 205, the first gate pad 265a, and the second gate pad 265b are formed of a first substrate 220. It is formed by depositing a transparent conductive material such as ITO or IZO by sputtering, depositing a metal such as copper by sputtering, and then etching the transparent conductive layer and the metal layer at once.

Thereafter, the insulating layer 222a, the semiconductor layer 212a, and the first metal layer 113a are sequentially stacked on the first substrate 220, and the photoresist layer 280 is formed thereon, and then a mask ( 290) on it and irradiates light such as ultraviolet light.

The insulating layer 222a is formed by laminating inorganic materials such as SiO ₂ or SiN ₂ by PECVD, and the semiconductor layer 213a is formed by laminating amorphous silicon (a-Si) or the like by PECVD. The second metal layer 213a is formed by laminating a metal such as Mo by the sputtering method.

The first mask 290 is a multi-tone mask, and includes a transmission region 290a for transmitting light, a first partial transmission region 290b and a second partial transmission region 290c for transmitting only part of the light. ), And a blocking area 290d for blocking light. In this case, the first partial transmission region 290b transmits more light than the second partial transmission region 290c.

As shown in FIG. 6B, ultraviolet rays are irradiated and developed on the photoresist layer 280 by the mask 290, and thus, the first photoresist pattern 281a and the second photoresist pattern are respectively applied to the pixel region and the pad region. 281b and a third photoresist pattern 281c are formed. At this time, in the first photoresist pattern 281a, the thickness t2 of the center region (regions corresponding to the gate electrodes 211a and 211b) is formed to be smaller than the thickness t1 of both sides, and the second photoresist pattern 281b is formed. ) Is formed to a thickness of t1 and the third photoresist pattern 281c is formed to a thickness of t3. At this time, the thickness t3 of the third photoresist pattern 281c is smaller than the thickness t2 of the central region of the first photoresist pattern 281a (that is, t3 <t2).

As shown in FIG. 6C, the first metal layer 213a is blocked by the first photoresist pattern 281a, the second photoresist pattern 281b, and the third photoresist pattern 281c. The first metal layer 213a, the insulating layer 222a, and the semiconductor layer 212a are etched to form a gate insulating layer 222 on the first gate electrodes 211a and 211b in the pixel region, and the semiconductor layer 212 and The metal pattern 213b is formed. In addition, a gate insulating layer 222, a semiconductor layer 212b, and a metal layer 213c are formed on the first gate pad 265a and the second gate pad 265b of the pad region, and the gate insulating layer is formed on the first substrate 220. The layer 222, the semiconductor layer 212c and the data pad 267 are formed.

After that, the etching process is performed once again to etch the metal layer 205a on the common electrode 205.

Subsequently, as shown in FIG. 6D, when the first photoresist pattern 281a, the second photoresist pattern 281b and the third photoresist pattern 281c are ashed, the first gate pad 265a and All of the third photoresist pattern 281c on the second gate pad 265b is removed so that the metal layer 213c on the first gate pad 265a and the second gate pad 265b is exposed to the outside and the first photo The thickness of the resist pattern 281a and the second photoresist pattern 281b is reduced.

Subsequently, as illustrated in FIG. 6E, the metal layer 213c and the semiconductor layer 212b on the exposed first gate pad 265a and the second gate pad 265b are etched to etch the metal layer 213c and the semiconductor layer. Remove 212b.

Thereafter, as illustrated in FIG. 6F, the first photoresist pattern 281a and the second photoresist pattern 281b are ashed to form a central region of the first photoresist pattern 281a, that is, a first gate electrode. After exposing the upper metal layer 213b to the outside, the exposed metal layer 213b is etched to form a source electrode 213 and a drain electrode 214 as shown in FIG. 6G.

Subsequently, as shown in FIG. 6H, the protective layer 224 is formed by applying an inorganic material such as SiO ₂ or SiN ₂ or an organic material such as photo acryl over the entire first substrate 220. Etching to form a first contact hole 225 exposing the drain electrode 214 of the thin film transistor in the pixel region, and a second contact hole exposing the second gate pad 265b and the data pad 267 of the pad region, respectively. 227 and a third contact hole 228 are formed. Subsequently, a transparent conductive material 207a such as ITO or IZO is coated on the protective layer 224 and then etched to form a pixel electrode 207 in the pixel region as shown in FIG. A first transparent metal layer 266 connected to the gate pad 265a and a second transparent metal layer 268 connected to the data pad 267 are formed.

Subsequently, as shown in FIG. 6J, after forming the black matrix 232 and the color filter layer 234 on the second substrate 230, the first substrate 220 and the second substrate 230 are bonded to each other. A liquid crystal display device is completed by forming the liquid crystal layer 240 therebetween. The black matrix 232 is formed by stacking and etching a metal oxide such as CrO or CrO ₂ or by applying and etching black resin or the like.

The liquid crystal layer 240 may be formed by bonding the first substrate 220 and the second substrate 230, and then injecting liquid crystal therebetween, and forming the first substrate 220 or the second substrate ( After dispensing the liquid crystal onto the 230, the first substrate 220 and the second substrate 230 are bonded to each other so that the liquid crystal is uniformly distributed throughout the first substrate 220 and the second substrate 230. You could do it.

As described above, the transverse electric field mode liquid crystal display element is also formed using the four masks in the transverse electric field mode liquid crystal display element of this embodiment. That is, a mask for forming the gate electrodes 211a and 211b, the common electrode 205 and the gate pads 265a and 265b, the semiconductor layer 212 and the source electrode 213, the data pad 267 and the common electrode 205 ) The mask for etching the metal layer on the upper side, the mask for forming the contact holes 225, 227, 228, and the mask for forming the pixel electrode 207 are used. Thus, minimizing the number of masks can simplify the process and reduce the manufacturing cost. Furthermore, in the present invention, since the gate electrodes 211a and 211b composed of two layers and the common electrode 205 composed of one layer can be formed by using a single mask of a multi-tone mask, the process is further simplified and the manufacturing cost can be reduced. You can save even more.

As described above, in the present invention, by arranging the common electrode and the pixel electrode perpendicularly to each other with the insulating layer interposed therebetween, the driving power can be reduced and the transmittance can be improved. In addition, since the transverse electric field mode liquid crystal display device of the present invention can be manufactured by four masks, manufacturing cost can be reduced.

On the other hand, in the above description, only the specific structure of the present invention is shown, but the present invention is not limited to this structure. Other examples or modifications of the present invention can be easily created by anyone who is engaged in the technical field to which the liquid crystal display device using the basic concept of the present invention belongs.

1A is a plan view showing the structure of a conventional transverse electric field mode liquid crystal display device.

FIG. 1B is a cross-sectional view taken along line II ′ of FIG. 1A.

2 is a plan view showing the structure of a transverse electric field mode liquid crystal display device according to the present invention.

3 is a cross-sectional view taken along the line II-II ′ of FIG. 2.

4A and 4B illustrate switching of liquid crystal molecules in an on-off state in a transverse electric field mode liquid crystal display device according to the present invention.

4C is a view showing an electric field in an overlap region of a common electrode and a pixel electrode in a transverse electric field mode liquid crystal display device according to the present invention;

5A-5K illustrate an example of a method of manufacturing a transverse electric field mode liquid crystal display device according to the present invention.

6A to 6J are views showing another example of the manufacturing method of the transverse electric field mode liquid crystal display device according to the present invention.

Claims (16)

A plurality of pixels defined by a plurality of gate lines and data lines formed on the first substrate; A thin film transistor disposed in each pixel; At least one common electrode arranged in parallel with the data line in a pixel; At least one pixel electrode arranged in the pixel perpendicular to the common electrode to form a common electrode and an electric field, And the common electrode and the pixel electrode cross each other with an insulating layer interposed therebetween. The method of claim 1, wherein the thin film transistor, A gate electrode formed on the first substrate; A gate insulating layer formed on the gate electrode; A semiconductor layer formed on the gate insulating layer; A source electrode and a drain electrode formed on the semiconductor layer and connected to the data line of the pixel; And And a protective layer formed on the source electrode and the drain electrode. The method of claim 2, wherein the gate electrode, A first gate electrode made of a transparent conductive material formed on the first substrate; And The transverse electric field mode liquid crystal display device comprising a second gate electrode formed of a metal and formed on the first gate electrode. The transverse electric field mode liquid crystal display device of claim 2, wherein the common electrode and the pixel electrode are made of a transparent conductive material. The transverse electric field mode liquid crystal display of claim 3 or 4, wherein the transparent conductive material comprises indium tin oxide (ITO) and indium zinc oxide (IZO). The transverse electric field mode liquid crystal display device of claim 2, wherein a common electrode is formed on the first substrate, and a pixel electrode is formed on the passivation layer. The method of claim 1, Second substrate; A black matrix and a color filter formed on the second substrate; The transverse electric field mode liquid crystal display device further comprising a liquid crystal layer formed between the first substrate and the second substrate. Stacking a transparent conductive material, a metal, and a first photoresist layer on the first substrate; After the first photoresist layer is developed by a first diffraction mask to form a first photoresist pattern and a second photoresist pattern having a different thickness, the transparent conductive layer is formed by the first photoresist pattern and the second photoresist pattern. Forming a gate electrode, a common electrode, and a metal layer disposed on the common electrode, the gate electrode including a transparent conductive layer and a metal layer for etching a material and a metal; Acing the first photoresist pattern and the second photoresist pattern to remove the second photoresist pattern; Etching the metal layer on the common electrode by means of an aced first photoresist pattern; Depositing a semiconductor material, a metal, and a second photoresist layer on the first substrate; Developing and etching the second photoresist layer by a second diffraction mask to form a semiconductor layer, a source electrode and a drain electrode on the gate electrode; And A method of manufacturing a transverse electric field mode liquid crystal display device comprising the step of forming a protective layer on a first substrate and forming a pixel electrode thereon. The method of claim 8, wherein the forming of the semiconductor layer, the source electrode, and the drain electrode includes: Developing the second photoresist layer to form third photoresist patterns having different thicknesses; Etching the semiconductor material and the metal by the third photoresist pattern to form a semiconductor layer and a metal layer; Acing the third photoresist pattern to expose a central region of the metal layer; And And etching the metal layer to form a source electrode and a drain electrode in a state in which the metal layer is blocked by a third aceted photoresist pattern. The method of claim 8, wherein the forming of the pixel electrode comprises: Forming a protective layer on the first substrate; Forming a contact hole in the protective layer; Stacking a transparent conductive material on the protective layer; And A method of manufacturing a transverse electric field mode liquid crystal display device comprising the step of etching the transparent conductive material. The method of claim 8, Forming a black matrix and a color filter layer on the second substrate; Bonding the first substrate and the second substrate to each other; And And forming a liquid crystal layer between the first substrate and the second substrate. 10. The method of claim 8, wherein the forming of the gate electrode comprises forming a gate pad including a transparent conductive layer and a metal layer. 10. The method of claim 8, wherein the forming of the semiconductor layer, the source electrode, and the drain electrode comprises forming a data pad. Providing a first substrate comprising a pixel region and a pad region; Forming a gate electrode made of a transparent conductive material and a metal in the pixel region of the first substrate, a common electrode and a metal layer thereon, and forming a gate pad made of the transparent conductive material and a metal in the pad region; Stacking an insulating material, a semiconductor material, a metal, and a photoresist layer on the first substrate; Developing the photoresist layer using a multitone mask having three blocking regions and three transmission regions having different light transmittances to form a first photoresist pattern, a second photoresist pattern, and a third photoresist pattern; The insulating material, the semiconductor material, and the metal are etched using the first photoresist pattern, the second photoresist pattern, and the third photoresist pattern to form a gate insulating layer and a semiconductor layer on the gate electrode in the pixel area, and Forming a semiconductor layer and a metal layer over the gate pad, a data pad and a semiconductor layer under the gate pad in the region; The first photoresist pattern, the second photoresist pattern, and the third photoresist pattern are ashed to expose a metal layer on the gate pad, and then the gate is formed using the aced first photoresist pattern and the second photoresist pattern. Etching to remove the metal layer and the semiconductor layer over the pad; Acing the first photoresist pattern and the second photoresist pattern again to expose a portion of the metal layer on the gate electrode, and then etching the exposed metal layer to form a source electrode and a drain electrode; And A method of manufacturing a transverse electric field mode liquid crystal display device comprising the step of forming a protective layer on a first substrate and forming a pixel electrode thereon. The method of claim 14, wherein the forming of the pixel electrode comprises: Forming a protective layer on the first substrate; Forming a contact hole in the protective layer; Stacking a transparent conductive material on the protective layer; And A method of manufacturing a transverse electric field mode liquid crystal display device comprising the step of etching the transparent conductive material. The method of claim 14, Forming a black matrix and a color filter layer on the second substrate; Bonding the first substrate and the second substrate to each other; And And forming a liquid crystal layer between the first substrate and the second substrate.

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