KR20110018246A - Fringe field switching mode liquid crystal display and manufacturing method thereof - Google Patents

Abstract

PURPOSE: A fringe field switching mode liquid crystal display and a manufacturing method thereof are provided to have a new lamination structure and a design. CONSTITUTION: A transparent common electrode(170) is formed on an entire upper portion including data lines and gate lines in order to adjust the light transmittance amount through the application of voltage to a liquid crystal layer. A conductive reflection structure(180) has a structure connected to the transparent common electrode, and is formed on the upper portion of the gate line including some of switching elements and the data line. A transparent pixel electrode(200) is formed within each pixel region by having a gap between at least second inter-insulation layers on the upper portion of the conductive reflection structure and the transparent common electrode.

Description

FFS mode liquid crystal display and its manufacturing method {FRINGE FIELD SWITCHING MODE LIQUID CRYSTAL DISPLAY AND MANUFACTURING METHOD THEREOF}

The present invention relates to an FFS mode liquid crystal display device and a method of manufacturing the same having improved aperture ratio and increased internal reflectance to improve outdoor visibility.

In general, the FFS mode liquid crystal display is proposed to improve the low aperture ratio and transmittance of the In-Plane Switching Mode (IPS mode) liquid crystal display.

In the FFS mode liquid crystal display, the common electrode (relative electrode) and the pixel electrode are formed of a transparent conductor, and the gap between the common electrode and the pixel electrode is increased by the upper and lower glass substrates while increasing the aperture ratio and the transmittance compared with the IPS mode liquid crystal display. By forming a fringe field between the common electrode and the pixel electrode by forming a narrower than the gap between them, even the liquid crystal molecules existing on the electrodes are operated to obtain a more improved transmittance.

The prior art of the FFS mode liquid crystal display is disclosed in, for example, Korean Patent Nos. 341123, 855782, 849599, and the like, filed and registered by the present applicant.

Looking at some of the patents, first, Korean Patent No. 855782 has a transparent pixel electrode spaced apart from each other with an insulating layer interposed therebetween, and a rubbing direction for arranging the liquid crystal layer. Is within 5 ㅀ of the direction of the gate line, and one end of the transparent common electrode is disposed between the data line and the transparent pixel electrode, and the aperture ratio near the data line is adjusted by adjusting the distance between the transparent common electrode and the transparent pixel electrode based on the data line. And an invention capable of improving light transmittance.

In addition, Korean Patent No. 849,599 discloses liquid crystal driving near the data line and liquid crystal at the center of the pixel region by adjusting the electrode width, electrode arrangement relationship, etc. of each of the data line, the transparent common electrode, and the transparent pixel electrode near the data line. Disclosed is an FFS mode liquid crystal display device in which driving is driven in different liquid crystal driving modes, thereby eliminating light blocking films formed on the data lines, and preventing light leakage.

However, the above-mentioned Korean Patent No. 855,782 and Korean Patent No. 849,599 are effective inventions in many parts, such as increasing outdoor visibility, increasing aperture ratio, and enabling low power, but still have problems to be improved.

First, there is a problem in that the upper and lower plate bonding margin is reduced due to the reduction and removal of the light shielding film, which may cause color mixing, and thus, a problem of increasing the defective rate is caused. In the step on the opposite side, rubbing is not made completely, and there is a problem that light leakage may occur at the opposite side of the data line in the direction of the transparent electrode and the rubbing direction.

Therefore, there is still a need for a new FFS mode liquid crystal display device to solve the above problems.

As a means for solving the above problems, it is an object of the present invention to provide an FFS mode liquid crystal display device having a novel laminated structure, design.

Another object of the present invention is to provide an FFS mode liquid crystal display device which improves the aperture ratio and enables low power by reducing the data light shielding film as much as possible or not using the light shielding film at all.

Another object of the present invention is to improve the outdoor visibility by forming a conductive reflective region so that the regions other than the transmissive region such as gate lines and data lines can be utilized as reflective regions as much as possible.

Another object of the present invention is to provide an FFS mode liquid crystal display device which can improve screen quality by minimizing light leakage, mixing, and the like.

As a technical means for solving the above-described problems, the first aspect of the present invention includes a lower substrate, an upper substrate, and a liquid crystal layer interposed between the substrates, the gate line formed in the direction crossing each other on the lower substrate In a FFS mode liquid crystal display in which each pixel region is defined by a data line and a switching element is disposed at an intersection of the lines, the gate line is configured to adjust a light transmission amount by applying a voltage to the liquid crystal layer. And a transparent common electrode formed over at least a first interlayer insulating layer over the entire area including the data lines. A conductive reflective structure formed over the gate line including the data line and the switching element in a structure connected to the transparent common electrode; And a transparent pixel electrode formed in each pixel region having at least a second interlayer insulating layer therebetween on the transparent common electrode and the conductive reflective structure and formed of a slit type having a plurality of slits therein. A liquid crystal display device is provided.

Preferably, an edge portion of the transparent pixel electrode overlaps at least a portion of the conductive reflective structure.

Preferably, the plurality of slits of the transparent pixel electrode form an angle with the gate line, and the rubbing direction for arranging the liquid crystal layer is kept substantially parallel to the direction of the gate line.

Preferably, the conductive reflective structure may be formed except for a portion of the drain electrode for connecting the transparent pixel electrode and the drain electrode of the switching element.

Further, preferably, the conductive reflective structure may be formed except for some regions and channel regions of the drain electrode of the switching element.

A second aspect of the present invention includes a lower substrate, an upper substrate, and a liquid crystal layer interposed between the substrates, and each pixel region is defined by a gate line and data lines formed in a direction crossing each other on the lower substrate. A method of manufacturing a FFS mode liquid crystal display device having a switching element disposed at an intersection of the lines, the method comprising: forming a gate line on the lower substrate; Forming a gate insulating film on the substrate including the gate line; Forming an active layer and a data line in a predetermined region over the gate insulating film; Forming a transparent common electrode as a whole with at least a first insulating layer interposed therebetween on the resultant including the data line; Forming a conductive reflecting structure connected to the transparent common electrode and in a portion of the data line, the gate line, and the switching element; Forming a slit type transparent pixel electrode formed in each pixel region with at least a second insulating layer interposed therebetween on a resultant including the conductive reflective structure and having a plurality of slits therein; A method of manufacturing a display device is provided.

According to the present invention, it is possible to provide a structure capable of optimizing the aperture ratio and reflectivity by optimizing the arrangement of the transparent common electrode, the transparent pixel electrode, and the conductive reflective structure with the data line, the gate line, and the drain electrode.

In addition, according to the present invention, by reducing the light shielding film of the upper substrate as much as possible or even not using the light shielding film at all, the aperture ratio can be improved and low power can be achieved.

In addition, the present invention can improve outdoor visibility by forming a reflective region with a conductive reflective structure so that the regions other than the transmissive region such as gate lines and data lines can be utilized as reflective regions as much as possible.

In addition, according to the present invention, it is possible to minimize the light leakage phenomenon, mixed color phenomenon, etc. to improve the screen quality.

DETAILED DESCRIPTION Hereinafter, exemplary embodiments of the present invention will be described with reference to the accompanying drawings so that those skilled in the art can easily implement the technical idea of the present invention.

The liquid crystal display according to the exemplary embodiment of the present invention includes a lower substrate, an upper substrate, and a liquid crystal layer interposed between the lower substrate and the upper substrate, and the lower substrate is formed in a direction crossing each other to apply a voltage to the liquid crystal layer. Each pixel region is defined by gate lines and data lines.

1 is a partial plan view of a pixel area formed on a lower substrate of a liquid crystal display according to an exemplary embodiment of the present invention. 2A to 2C are cross-sectional views taken along line A-A ', line B-B', and C-C 'of FIG. 1, respectively.

1 and 2A to 2C, the FFS mode liquid crystal display according to the present exemplary embodiment is arranged such that the gate line 120 and the data line 150 intersect on the lower substrate 100 and the gate line 120 crosses the gate line 120. A thin film transistor, which is a switching element, is disposed at an intersection of the data line 150 and the data line 150.

In the unit pixel region defined by the gate line 120 and the data line 150, a direction toward the transparent common electrode 170 and the data line 150 is applied to control the light transmission amount by applying a voltage to the liquid crystal layer. The slit type transparent pixel electrode 200 having a plurality of slits is spaced apart from each other with the interlayer insulating layer 190 interposed therebetween. The transparent common electrode 170 may have a shape that is not particularly limited, but preferably has a plate shape.

In addition, the conductive reflective structure 180 is disposed on the transparent common electrode 170 to be connected to the transparent common electrode 170 to improve reflectance and aperture ratio.

An upper substrate (not shown) is formed on the lower substrate 100 to be spaced apart by a predetermined distance, and the upper substrate (not shown) includes a color filter and an overcoat, and includes a lower substrate 100 and a plurality of liquid crystal molecules. They are bonded to each other with a layer (not shown) in between.

In this embodiment, one of the main features of the arrangement structure of the transparent common electrode 170, the transparent pixel electrode 200, and the conductive reflective structure 180 is included. In addition to the shape of the gate line 120, the data line 150, and the structure and arrangement of the stacked structure and the interlayer insulating layer (160, 190) is properly optimized by maximizing the object of the present invention.

In particular, the transparent common electrode 170 is not formed in an isolated shape in each unit pixel region, except for a portion of the switching element (or the drain electrode 150a) (see FIG. 3D), the data line 150 and the gate line ( It has a structure formed in the entire region including the top of the 120. That is, an unformed region of the transparent common electrode 170 is present in a portion of the switching element (or drain electrode 150a) (see FIG. 3D), which is then the drain electrode 150a and the transparent pixel electrode 200 of the switching element. ) Is a portion to which the transparent common electrode 170 is excluded.

According to this structure, when a voltage is applied from the outside through the transparent common electrode 170 and transferred to each unit pixel region, the resistance is reduced, which may be advantageous for the large screen liquid crystal display. In this embodiment, the transparent common electrode 170, the transparent pixel electrode 200, the gate line 120, the data line 150, and the like may have a structure in which the structure of the transparent common electrode 170 is connected to the entire substrate. The arrangement structure and stacking position of each interlayer insulating layer 160, 190 are adjusted.

In the present exemplary embodiment, the gate line 120, the gate insulating layer 130, the active layer 140, and the data line 150 are formed on the substrate 100, and the interlayer insulating layer 160 is interposed therebetween. A transparent common electrode 170 formed on the entire substrate, a conductive reflective structure 180 formed by being connected to the transparent common electrode 170, an interlayer insulating layer 190, and a transparent pixel electrode 200 formed thereon. Has

Such a structure has an effect that can significantly widen the aperture ratio of the entire liquid crystal display device.

On the other hand, the plurality of slits of the transparent pixel electrode 200 may avoid light leakage around the data line when the plurality of slits form a predetermined angle θ with the gate line 120. When the rubbing direction for arranging the liquid crystal layer is kept substantially parallel to the direction of the gate line, the predetermined angle θ is preferably maintained at 1 to 15 degrees.

In particular, the angle θ may be adjustable in consideration of the maximum transmittance and the inclination of the V-T curve when driving the liquid crystal, and preferably maintains about 7 degrees.

On the other hand, the conductive reflective structure 180 formed of a structure connected to the transparent common electrode 170 has a relatively high reflectance of aluminum (Al), aluminum alloy (AlNd), molybdenum (Mo), molybdenum alloy (MoW), silver ( Ag), a silver alloy, tungsten (W), and an alloy including at least one of these, and may be formed in a manner of directly contacting the upper portion of the transparent common electrode 170. It serves to reduce the resistance and prevent light leakage and mixing, and at the same time serves as a reflective structure.

In the present embodiment, not only the shape of the conductive reflective structure 180 itself, but also a structure different from the conductive reflective structure 180 (transparent common electrode 170, transparent pixel electrode 200, data line 150, gate line 120). ), And means for optimizing the aperture ratio and the reflectivity by optimizing the arrangement with the drain electrode 150a and the like.

When the substrate is viewed from the top of the liquid crystal display, the conductive reflective structure 180 is formed to increase the internal reflection of the light incident on the data line 150, the gate line 120, and the like. Increasing the aperture ratio plays a role to improve outdoor readability. Meanwhile, it is preferable that a light blocking area is not formed in the upper substrate corresponding to the gate line 120 and the data line 150. That is, the light blocking region of the upper substrate may not be formed at all or may be formed only in a partial region corresponding to the switching element.

Preferably, the conductive reflective structure 180 has a structure in which each unit pixel region is connected to each other. That is, the conductive reflective structure 180 has a structure that is connected through the entire substrate, except for the upper portion and the partial region of the gate line 120 and the data line 150 (not forming only the conductive reflective structure in a portion of the switching element). The region exists.) The upper portion of the switching element region is connected to the transparent common electrode 170. The region in which the conductive reflective structure 180 is formed is directly related to the external reflection amount, the resistance reduction, and the like. In particular, in the stacked structure according to the present embodiment, other structures (transparent common electrode 170, transparent pixel electrode 200, and data lines) are formed. (150), the gate line 120, the drain electrode 150a, etc.), the aperture ratio, the amount of reflection, the resistance, etc. are changed, and it is necessary to find an appropriate range.

On the other hand, such an arrangement relationship of the conductive reflective structure 180 is preferably applicable to the specific stacked structure of the present embodiment. Specifically, the transparent common electrode is formed in the entire pixel region (not formed region in the switching element partial region). And a conductive reflective structure formed in such a manner as to be connected to the transparent common electrode, and a transparent pixel electrode having a plurality of slits for each unit pixel with an insulating film interposed therebetween. Preferably, the conductive reflective structure 180 is formed in a lattice structure on the data line 150 and the gate line 120 except for a portion of the drain electrode 150a of the switching element (see FIG. 4). In addition, the drain electrode 150a of the switching element and a portion of the channel region are excluded, and are formed in a lattice structure on the data line 150 and the gate line 120 (see FIG. 1). Another example of such a structure is disclosed in FIGS. 6 and 7.

Looking at the relationship between the conductive reflective structure 180 and the data line 150, the gate line 120 and the drain electrode 150a in more detail, the conductive reflective structure 180 is the data line 150 and the gate line 120 It is preferable to have a structure (D4, D5) formed in the form including the inside and partially overlap with the transparent pixel electrode (see Fig. 2b, 2c). D4, D5 is adjacent to the two pixel electrode 200. In order to prevent light leakage due to the transverse electric field generated between), it is preferable to form in a range of 0.1 to 5.0 micrometers, more preferably 0.5 to 2 micrometers in consideration of process capability.

On the other hand, forming the conductive reflecting structure 180 in a form (covering structure) including the data line 150 and the gate line 120 therein is appropriate to adjust the reflectance and transmittance and the data line 150 in accordance with the rubbing direction Due to the step difference between the gate line 120 and to prevent light leakage and color mixing that may occur in the periphery of the line.

On the other hand, the conductive reflective structure 180 preferably overlaps at least a portion of the edge region of the drain electrode 150a. In the inset of FIG. 1, D1, D2, and D3 show the distances at which the conductive reflective structure 180 overlaps the edge region of the drain electrode 150a. D1, D2, and D3 are preferably maintained at 0.5 to 5.0 micrometers in consideration of process capability. The overlapping of D1, D2, and D3 as shown in FIG. 1 is to prevent light leakage that may occur due to a step in the process, such an overlap is not necessary, and other modifications are possible. Modifications thereof are disclosed in the descriptions of FIGS. 6 and 7.

The inventors have found that light leakage occurs due to an unstable rubbing process in a portion of the gate line 120 (including the region R overlapping with the drain region of the switching element) during rubbing performed in a direction parallel to the gate line 120. This problem was solved by partially overlapping the edge region of the conductive reflective structure 180 and the gate line 120.

Hereinafter, a method of manufacturing the liquid crystal display device of the present invention will be described with reference to FIGS. 1, 2A to 2C, and 3A to 3G.

First, the gate line 120 is formed by depositing and patterning an opaque metal having excellent conductivity on the lower substrate 100 (FIG. 3A).

After the gate insulating layer 130 is deposited to cover the gate line 120, the a-Si layer and the n + a-Si layer are sequentially deposited on the gate insulating layer 130, and then the active layer 140 is formed through patterning. (FIG. 3B).

In addition, after depositing a metal layer on the active layer 140 to form a data line 150, source 150, drain 150a electrode by patterning, and depositing a first interlayer insulating layer 160 thereon ( 3c).

Next, a transparent conductive layer is deposited and patterned to form a transparent common electrode 170. In this case, the transparent common electrode 170 is not formed in an isolated shape in each unit pixel region, but has a structure in which the whole is connected when viewed through the entire substrate (FIG. 3D).

Thereafter, a metal having a relatively high reflectance is deposited, and then the conductive reflective structure 180 is formed through patterning. The conductive reflective structure 180 has a structure in which each unit pixel region is connected to each other, and may be formed by depositing and patterning a thickness of 100 μs to 7000 μs depending on the resistance of the metal (FIG. 3E).

Next, a second interlayer insulating layer 190 is formed on the transparent common electrode 170 and the conductive reflective structure 180, and a contact hole CN is formed to expose a portion of the drain electrode 150a. A transparent conductive layer is deposited on the insulating layer 190 (FIG. 3F).

Thereafter, the transparent conductive layer is patterned to form a slit transparent pixel electrode 200 (FIG. 3G). In this case, the drain electrode 150a and the transparent pixel electrode 200 are connected to each other by a transparent conductive layer deposited in the contact hole CN.

On the other hand, a light shielding area (not shown) is formed in the upper substrate. According to the present embodiment, the light shielding region may be provided only in the upper substrate corresponding to the switching element or may not be formed at all. According to the related art, a light blocking region is formed on the gate line 120 and the data line 150, but in the present exemplary embodiment, the light blocking region is also formed on the upper substrate 200 corresponding to the data line 150 and / or the gate line 120. No light shielding area is formed. It is obvious that the opening ratio is relatively increased when the area of shading region is reduced.

4 is a partial plan view of a pixel area formed on a lower substrate of a liquid crystal display according to another exemplary embodiment of the present invention. 5A is a cross-sectional view taken along the line A-A 'of FIG. 4, and FIG. 5B is a plan view of a process of forming a conductive reflective structure during a manufacturing process of a liquid crystal display according to another exemplary embodiment of the present invention.

For convenience of explanation, the difference from the embodiment of FIG. 1 will be mainly described. The main difference is in the region of the conductive reflective structure 180.

4, 5A, and 5B, the conductive reflective structure 180 includes a region of the channel 140 except for the region of the drain electrode 150a of the switching element, and includes a data line 150 and a gate line ( 120 is formed in a lattice structure on the top.

According to the present exemplary embodiment, the conductive reflective structure 180 may be formed on the upper portion of the channel 140 to further enlarge the reflective region and to not form the light blocking film formed on the upper substrate. That is, in the case of the embodiment of FIG. 1, the portion to be formed as the light shielding film becomes narrower, and of course, in the case of FIG. 4, the light shielding film is not formed at all.

6 and 7 are partial plan views of a pixel area formed on a lower substrate of a liquid crystal display according to another exemplary embodiment of the present invention.

For convenience of explanation, the difference from the embodiment of FIGS. 1 and 4 will be mainly described. The main difference is in the region of the conductive reflective structure 180.

The main difference between FIG. 6 and FIG. 1 is that in the basic structure of FIG. 1, the conductive reflective structure 180 of FIG. 6 is formed only in a part of the edge of the drain electrode 150a.

In addition, the main difference between FIG. 7 and FIG. 4 is that the conductive reflective structure 180 of FIG. 7 is formed only in a part of the edge of the electrode 150a in the basic structure of FIG. 4.

6 and 7 is an effective structure to improve the aperture ratio than the case of FIGS. 1 and 4. This is because the aperture ratio will be improved as the area of the conductive reflective structure 180 is reduced. However, even in this case, the drain region adjacent to the gate line in the switching device may overlap by the conductive reflective structure 180, and light leakage blocking may be effective by such a structure. This is as described above.

1 is a plan view of some pixel regions formed on a lower substrate of a liquid crystal display according to an exemplary embodiment of the present invention.

2A to 2C are cross-sectional views cut along the lines A-A ', B-B', and C-C 'of FIG. 1, respectively.

3A to 3G are views for explaining a manufacturing process of a liquid crystal display according to an exemplary embodiment of the present invention.

4 is a plan view of some pixel areas formed on a lower substrate of a liquid crystal display according to another exemplary embodiment of the present invention.

5A is a cross-sectional view taken along the line A-A 'of FIG. 4, and FIG. 5B is a plan view of a process of forming a conductive reflective structure during a manufacturing process of a liquid crystal display according to another exemplary embodiment of the present invention.

6 and 7 are partial plan views of a pixel area formed on a lower substrate of a liquid crystal display according to another exemplary embodiment of the present invention.

Claims (16)

Each pixel region is defined by a gate line and data lines including a lower substrate, an upper substrate, and a liquid crystal layer interposed between the substrates, and the lower substrate has a gate line and data lines formed in an intersecting direction. In the FFS mode liquid crystal display device in which a switching element including a drain electrode, a source electrode and a channel region is disposed, A transparent common electrode formed with an at least a first interlayer insulating layer interposed between the gate line and the data line to control light transmission by applying a voltage to the liquid crystal layer; A conductive reflective structure formed over the gate line including a portion of the data line and the switching element in a structure connected to the transparent common electrode; And A transparent pixel formed in each pixel area with at least a second interlayer insulating layer interposed between the transparent common electrode and the conductive reflective structure and having a plurality of slits therein and connected to the drain electrode of the switching element; An FFS mode liquid crystal display device having an electrode. According to claim 1, And the conductive reflective structure is formed to cover the gate line and the data line. According to claim 1, And the conductive reflective structure includes the switching element except for a portion of the drain electrode of the switching element, and is formed in a lattice structure on the data line and the gate line. According to claim 1, The conductive reflective structure is formed in a lattice structure on top of the data line and the gate line covering the switching element except a portion of the drain electrode region and the channel region of the switching element. . According to claim 1, And the conductive reflective structure overlaps at least a portion of an edge region of the drain electrode. According to claim 1, And the conductive reflective structure overlaps at least a portion of the transparent pixel electrode adjacent to the gate line. According to claim 1, And the conductive reflecting structure overlaps at least a portion of the transparent pixel electrode adjacent to the data line. According to claim 1, And the plurality of slits of the transparent pixel electrode form an angle with the gate line, and a rubbing direction for arranging the liquid crystal layer is parallel to the direction of the gate line. Each pixel region is defined by a gate line and a data line including a lower substrate, an upper substrate, and a liquid crystal layer interposed between the substrates, and formed in a direction crossing each other on the lower substrate. In the manufacturing method of the FFS mode liquid crystal display device in which a switching element including a drain electrode, a source electrode and a channel region is disposed, Forming a gate line and a gate electrode on the lower substrate; Forming a gate insulating film on the substrate including the gate line and the gate electrode; Forming a switching element and a data line including a drain electrode, a source electrode, and a channel region on the gate insulating layer; Forming a transparent common electrode as a whole except at least a portion of the switching device with at least a first insulating layer interposed between the switching device and the resultant including the data line; Forming a conductive reflective structure on the data line, the gate line, and a portion of the switching element, the conductive common structure being connected to the transparent common electrode; And forming a transparent pixel electrode formed in each pixel area with at least a second insulating layer interposed therebetween on the resultant including the conductive reflective structure and including a plurality of slits therein and connected to the drain electrode. Method of manufacturing a mode liquid crystal display device. The method of claim 9, And the conductive reflecting structure is formed in a structure covering the gate line and the data line. The method of claim 9, The conductive reflective structure includes the switching element excluding a portion of the drain electrode of the switching element and is formed in a lattice structure on the data line and the gate line, the manufacturing method of the FFS mode liquid crystal display device. . The method of claim 9, The conductive reflective structure includes the switching element excluding a drain electrode and a portion of the channel region of the switching element, and is formed in a lattice structure on the data line and the gate line. Manufacturing method. The method of claim 9, And the conductive reflective structure overlaps at least a portion of an edge region of the drain electrode. The method of claim 9, And the conductive reflective structure overlaps at least a portion of the transparent pixel electrode adjacent to the gate line. The method of claim 9, And the conductive reflective structure overlaps at least a portion of the transparent pixel electrode adjacent to the data line. The method of claim 9, The plurality of slits of the transparent pixel electrode form an angle with the gate line, and a rubbing direction for arranging the liquid crystal layer is maintained at an angle with respect to the direction of the gate line. Method of manufacturing the device.

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