KR102398551B1 - Thin film transistor substrate and liquid crystal display panel with the same - Google Patents

Abstract

The present invention relates to a thin film transistor substrate capable of improving productivity while maintaining a constant cell gap, and a liquid crystal display panel having the same, and the color filter of the liquid crystal display panel according to the present invention includes red, green, and It is disposed on the upper substrate of the blue sub-pixel area, and the step compensation layer is disposed on the organic passivation layer of the white sub-pixel area except for the red, green, and blue sub-pixel areas to compensate for the step difference generated by the color filter.

Description

A thin film transistor substrate and a liquid crystal display panel having the same

The present invention relates to a thin film transistor substrate, and more particularly, to a thin film transistor substrate capable of improving productivity while maintaining a constant cell gap, and a liquid crystal display panel having the same.

A video display device that implements various information on a screen is a key technology in the information and communication era, and is developing in the direction of thinner, lighter, portable and high-performance. Accordingly, flat panel display devices capable of reducing weight and volume, which are disadvantages of cathode ray tubes (CRTs), are in the spotlight.

Among the flat panel display devices, the liquid crystal display displays an image by adjusting the light transmittance of the liquid crystal by an electric field formed in a pixel electrode and a common electrode. To this end, the liquid crystal display displays images of various colors by configuring red, green, blue, and white sub-pixels as one unit pixel. Here, each sub-pixel includes a liquid crystal cell and a thin film transistor independently driving the liquid crystal cell.

Color filters of corresponding colors are formed in the red, green, blue, and white sub-pixels of the liquid crystal display. In this case, since each mask process for forming the red, green, blue, and white color filters is required, there is a problem in that productivity is lowered.

In order to solve this problem, the red, green, and blue sub-pixels have color filters of the corresponding colors, and the white sub-pixels use an overcoat layer formed all over the red, green, blue, and white sub-pixels without a white color filter. Thus, a structure for realizing white was proposed.

In this case, the cell gap of the white sub-pixel in which the white color filter is not formed is different from the cell gap of the red, green, and blue sub-pixels in which the color filter of the corresponding color is formed. Accordingly, since the cell gap between the white sub-pixel and the non-white sub-pixel is different, the transmittance characteristics according to the voltage applied to each sub-pixel are different, so there is a problem in that a luminance difference occurs due to a grayscale shift.

An object of the present invention is to provide a thin film transistor substrate capable of improving productivity while maintaining a constant cell gap, and a liquid crystal display panel having the same.

In order to achieve the above object, the color filter of the liquid crystal display panel of the present invention is disposed on the upper substrate of the red, green, and blue sub-pixel areas except for the white sub-pixel area, and the step compensation layer is the red, green, and blue sub-pixel area. It is disposed on the organic passivation layer of the white sub-pixel region except for , and compensates for a step difference generated by the color filter.

A thin film transistor substrate and a liquid crystal display panel having the same according to the present invention include an organic passivation layer integrated with a column spacer and a step difference compensation layer formed at the same time. Since the step difference formed in the overcoat layer on the color filter substrate is compensated for by the step compensation layer, the cell gaps of the red, green, and blue sub-pixel areas can be maintained to be the same as the cell gaps of the white sub-pixel areas where the step compensation layer is disposed. In addition, in the liquid crystal display panel according to the present invention, since the step compensation layer is formed at the same time as the organic passivation layer integrated with the column spacer, an additional mask process is unnecessary, so that productivity can be improved by 20% or more.

1 is a cross-sectional view illustrating a liquid crystal display panel according to the present invention.
2 is a cross-sectional view illustrating another exemplary embodiment of a liquid crystal display panel according to the present invention.
3A to 3C are cross-sectional views illustrating a method of manufacturing the thin film transistor substrate shown in FIG. 1 .

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

1 is a cross-sectional view illustrating a liquid crystal display panel according to the present invention.

1 , each unit pixel of the liquid crystal display panel according to the present invention includes red, green, blue, and white sub-pixels SPR, SPG, and SPB.

The red, green, blue, and white sub-pixels SPR, SPG, SPB, and SPW are arranged in a quad-type 2x2 structure, a 3x1 structure, or a stripe type. The liquid crystal display panel in which a plurality of unit pixels composed of red, green, blue and white sub-pixels (SPR, SPG, SPB, SPW) is formed has a thin film transistor substrate 120 facing with the liquid crystal layer 110 interposed therebetween. and a color filter substrate 130 .

The color filter substrate 130 includes a black matrix 132 , a color filter 134 , and an overcoat layer 136 sequentially formed on an upper substrate 111 .

The black matrix 132 is formed on the upper substrate 111 to overlap at least one of the gate line 102 , the data line 104 , and the thin film transistor (not shown). The black matrix 132 serves to separate each sub-pixel area and prevent optical interference and light leakage between adjacent sub-pixel areas. Meanwhile, as shown in FIG. 2 without a separate black matrix 132 , at least two color filters 134 of the red (R), green (G), and blue (B) color filters 134 are overlapped to form a black The matrix 132 may also serve as a substitute. For example, the black matrix 132 may be replaced by overlapping the red (R) and blue (B) color filters 134 in the area where the black matrix 132 is formed.

The red (R), green (G), and blue (B) color filters 134 are formed on the upper substrate 111 of the corresponding sub-pixels SPR, SPG, and SPB except for the white sub-pixel SPW. implement color. That is, the color filter 134 is formed in the red (R), green (G), and blue (B) sub-pixels SPR, SPG, and SPB, while the color filter 134 is formed in the white sub-pixel SPW. not formed

The overcoat layer 136 is formed of a transparent organic insulating material such as an acrylic resin on the color filter 134 and the black matrix 132 . The overcoat layer 136 compensates for the step difference between the color filter 134 and the black matrix 132 . In addition, the overcoat layer 138 serves as a white color filter in the white sub-pixel (SPW) region where the white color filter 134 is not formed.

The color filter substrate 130 includes a white sub-pixel (SPW) region in which the white color filter 134 is not formed; A first step H1 is generated between the red (R), green (G), and blue (B) sub-pixels SPR, SPG, and SPB in which the color filter 134 of the corresponding color is formed. That is, the upper surface of the overcoat layer 136, which is the uppermost layer of the white sub-pixel (SPW) region, is the uppermost layer of the adjacent red (R), green (G), and blue (B) sub-pixels (SPR, SPG, SPB). A first step H1 having a groove shape is formed with the upper surface of the overcoat layer 136 . In order to compensate for the first step H1, the thin film transistor substrate 120 is a white sub-pixel (SPW) except for the red (R), green (G), and blue (B) sub-pixels (SPR, SPG, and SPB) regions. A step compensation layer 160 selectively formed in the region is provided.

Specifically, the thin film transistor substrate 120 includes a gate line 102 formed on the lower substrate 101 , a data line 104 , a thin film transistor (not shown), a pixel electrode 122 , and a common element. An electrode 124 and a step compensation layer 160 are provided.

The thin film transistor supplies the data signal from the data line 104 to the pixel electrode 122 in response to the gate signal from the gate line 102 . To this end, the thin film transistor has a gate electrode connected to the gate line 102, a source electrode connected to the data line 104 crossing the gate line 102 and the gate insulating layer 112 interposed therebetween, and a pixel electrode ( 122), and a semiconductor layer forming a channel between the source and drain electrodes.

The common electrode 124 is connected to a common line (not shown) for supplying a common voltage. The common electrode 124 is formed in parallel with the pixel electrode 122 and alternately with the pixel electrode 122 .

The pixel electrode 122 is connected to the drain electrode of the thin film transistor formed at the intersection of the gate line 102 and the data line 104 . When a video signal is supplied to the pixel electrode 122 through a thin film transistor (not shown), the pixel electrode 122 forms a horizontal electric field with the common electrode 124 to which a common voltage is supplied. Accordingly, the liquid crystal molecules of the liquid crystal layer 110 arranged in the horizontal direction between the thin film transistor substrate 120 and the color filter substrate 130 rotate due to dielectric anisotropy. In addition, the light transmittance through the pixel region varies according to the degree of rotation of the liquid crystal molecules, thereby realizing grayscale.

On the other hand, at least one of the pixel electrode 122 and the common electrode 124 in the red (R), green (G), and blue (B) sub-pixels (SPR, SPG, SPB) is an organic passivation layer 128 . at least one of the pixel electrode 122 and the common electrode 124 of the white sub-pixel region is formed on the step compensation layer 160 closer to the color filter substrate 130 than the organic passivation layer 128 . is formed

The inorganic passivation layer 118 is formed to cover the thin film transistor to protect the channel of the thin film transistor.

The organic passivation layer 128 is formed on the inorganic passivation layer 118 using an organic insulating material, for example, photo acrylic, to cover the inorganic passivation layer 118 . The organic passivation layer 128 is formed in the red, green, blue, and white sub-pixels (SPR, SPG, SPB, SPW) to compensate for the step difference of the thin film transistor.

The lower column spacer 150 is made of the same material as the organic passivation layer 128 and is integrally formed with the organic passivation layer 128 . The lower column spacer 150 is formed to have a higher height than the step compensation layer 160 .

The lower column spacer 150 is formed to overlap the black matrix 132 on the lower substrate 101 to maintain a cell gap. On the other hand, when the cell gap is large, it is difficult to form a desired cell gap with only one lower column spacer 150. .

For example, the upper column spacer 152 is formed of the same material as the overcoat layer 136 at the same time, or as shown in FIG. 2 , the red (R), green (G), and blue (B) color filters 134 . may be formed by overlapping.

Meanwhile, in addition to the lower column spacer 150 , the thin film transistor substrate may further include a push spacer 140 overlapping the black matrix 132 . The pressed spacer 140 has a height lower than that of the lower column spacer 150 and is formed at the same height as the step difference compensation layer 160 . The pressed spacer 140 is used as a passage through which liquid crystal can be smoothly filled during liquid crystal injection, and allows the upper substrate 111 to be easily restored to its original state when pressure is applied to the upper substrate 111 . To this end, the pressed spacer 140 is formed to have a higher density than that of the lower column spacer 150 .

The step compensation layer 160 is an organic passivation layer on the organic passivation layer 128 of the white sub-pixel (SPW) region except for the red (R), green (G), and blue (B) sub-pixels (SPR, SPG, SPB). (128) is formed integrally with the organic passivation layer (128) of the same material. Here, since the step compensation layer 160 has an area similar to that of the white sub-pixel SPW region, the area is larger than that of the lower column spacer 150 . This step compensation layer 160 has a shape opposite to that of the first step H1 in the groove shape on the thin film transistor substrate 120 to compensate for the first step H1 in the groove shape formed in the color filter substrate 130 . A second step H2 having a protrusion shape is formed. That is, the upper surface of the step compensation layer 160, which is the uppermost layer of the white sub-pixel (SPW) region, is the uppermost layer of the adjacent red (R), green (G), and blue (B) sub-pixels (SPR, SPG, SPB). A second step H2 having a protrusion shape is formed with the upper surface of the organic passivation layer 128 . In this case, the first and second steps H1 and H2 have the same height.

As described above, the color filter (R), green (G), and blue (B) sub-pixels of each of the red (R), green (G), and blue (B) sub-pixels through the step compensation layer 160 that induces the second step H2 having a shape opposite to the first step H1 The first step H1 between the upper surface of the overcoat layer 136 formed on the 134 and the upper surface of the overcoat layer 136 formed on the upper substrate 111 of the white sub-pixel SPW may be compensated. . That is, the distance G1 between the overcoat layer 136 and the organic passivation layer 128 in the red (R), green (G), and blue (B) sub-pixels (SPR, SPG, SPB) is the white sub-pixel (SPW). ) region, the distance G2 between the overcoat layer 136 and the step difference compensation layer 160 becomes the same. Accordingly, the cell gap of the red (R), green (G), and blue (B) sub-pixels (SPR, SPG, and SPB) is the same as the cell gap of the white sub-pixel (SPW) in which the step compensation layer 160 is disposed. Therefore, color coordinates can be kept constant, thereby preventing deterioration of image quality.

In the liquid crystal display panel according to the present invention, the thin film transistor substrate 120 manufactured through the manufacturing method shown in FIGS. 3A to 3C and the color filter substrate 130 manufactured separately are interposed between the liquid crystal layer 110 . It is completed by attaching and bonding.

3A to 3C are cross-sectional views for explaining a method of manufacturing a thin film transistor substrate according to the present invention.

As shown in FIG. 3A , a gate line 102 , a data line 104 , and a thin film transistor are formed on the lower substrate 101 .

Specifically, a gate metal layer is formed on the lower substrate 101 by a deposition method such as a sputtering method. As the gate metal layer, a metal material such as Mo, Ti, Cu, AlNd, Al, Cr, Mo alloy, Cu alloy, Al alloy, etc. is used as a single layer, or a structure in which two or more layers are stacked using the metal. Subsequently, a gate electrode and a gate line 102 of the thin film transistor are formed by patterning the gate metal layer through a photolithography process and an etching process.

A gate insulating film 112 formed of SiNx or SiOx, an amorphous silicon layer, and an amorphous silicon layer doped with impurities (n+ or p+) are sequentially formed on the lower substrate 101 on which the gate electrode and the gate line 102 are formed. Then, the amorphous silicon layer and the amorphous silicon layer doped with impurities are patterned by a photolithography process and an etching process to form a semiconductor pattern including an active layer and an ohmic contact layer.

A data metal layer is formed on the lower substrate 101 on which the semiconductor pattern is formed. As the data metal layer, a metal material such as Mo, Ti, Cu, AlNd, Al, Cr, Mo alloy, Cu alloy, Al alloy, etc. is used as a single layer, or a structure in which two or more layers are stacked using the metal. Subsequently, the data metal layer is patterned by a photolithography process and an etching process to form the data line 104 and source and drain electrodes of the thin film transistor. Then, the active layer is exposed by removing the ohmic contact layer positioned between the source and drain electrodes as a mask. Meanwhile, the semiconductor pattern, the data line, and the source and drain electrodes can be formed through a single mask process using a diffraction mask or a transflective mask, that is, simultaneously.

Referring to FIG. 3B , an inorganic passivation film 118 formed of SiNx or SiOx and a photosensitive film such as photoacrylic are coated on the gate insulating film 112 on which the data line 104 and the source and drain electrodes are formed. Then, the organic passivation layer 128 having a contact hole exposing the drain electrode, the lower column spacer 150, the depressed spacer 140 and the step compensation film ( 160) are formed at the same time.

In this case, the contact hole corresponds to the transmissive part of the transflective mask, the lower column spacer 150 corresponds to the blocking part of the transflective mask, and the pressed spacer 140 and the step compensation layer 160 are formed to correspond to the first transflective part and the first transmissive part. Correspondingly, the remaining organic passivation layer 128 corresponds to the second semi-transmissive portion having a higher transmittance than the first semi-transmissive portion.

Accordingly, the organic passivation layer 128 is formed on the inorganic passivation layer 118 to a first thickness, the step compensation layer 160 and the pressed spacer 140 are formed to a second thickness thicker than the first thickness, and the lower column The spacer 150 is formed to have a third thickness greater than the second thickness.

Referring to FIG. 3C , the organic passivation layer 128 , the lower column spacer 150 , the depressed spacer 140 , and the step compensation layer 160 are integrally formed on the lower substrate 101 through a deposition method such as a sputtering method. A transparent conductive film is formed. As the transparent conductive film, indium tin oxide (ITO), tin oxide (TO), indium zinc oxide (IZO), SnO ₂ , amorphous-indium tin oxide (a-ITO), etc. this is used Then, the pixel electrode 122 and the common electrode 124 are formed by patterning the transparent conductive layer through a photolithography process and an etching process.

As described above, in the liquid crystal display panel according to the present invention, since the step compensation layer 160 is formed at the same time as the organic passivation layer 128 integrated with the column spacer 150, an additional mask process is unnecessary, so that productivity can be improved by 20% or more. can

Meanwhile, in the present invention, a horizontal electric field structure in which the pixel electrode 122 and the common electrode 124 are formed in a slit shape has been described as an example. In addition, any one of the pixel electrode 122 and the common electrode 124 has a slit shape. It is also applicable to a fringe electric field structure in which the other one is formed in the form of a plate, or a vertical electric field structure in which the pixel electrode 122 and the common electrode 124 are formed in a plate form on different substrates.

The above description is merely illustrative of the present invention, and various modifications may be made by those of ordinary skill in the art to which the present invention pertains without departing from the technical spirit of the present invention. Therefore, the embodiments disclosed in the specification of the present invention do not limit the present invention. The scope of the present invention should be construed by the following claims, and all technologies within the scope equivalent thereto should be construed as being included in the scope of the present invention.

102: gate line 104: data line
110: liquid crystal layer 112: gate insulating film
120: thin film transistor substrate 122: pixel electrode
124: common electrode 128: organic protective film
130: color filter substrate 136: overcoat layer
150,152: column spacer 160: step compensation film

Claims (12)

A liquid crystal display panel having red, green, blue and white sub-pixels per unit pixel, the liquid crystal display panel comprising:
a color filter substrate in which the uppermost layer of the white sub-pixel area has a first step difference from the uppermost layer of the adjacent sub-pixel area;
and a thin film transistor substrate in which the uppermost layer of the white sub-pixel area forms a second step with the uppermost layer of the adjacent sub-pixel area;
The color filter substrate is
a color filter disposed on an upper substrate of the red, green, and blue sub-pixel areas except for the white sub-pixel area;
an overcoat layer disposed on the red, green, blue and white sub-pixel regions;
an upper surface of the overcoat layer in the white sub-pixel area forms the first step in a groove shape with an upper surface of the overcoat layer in the adjacent sub-pixel area;
The thin film transistor substrate is
an organic passivation layer disposed on the red, green, blue, and white sub-pixel regions of the lower substrate facing the upper substrate;
a step compensation layer disposed on the organic passivation layer of the white sub-pixel area except for the red, green, and blue sub-pixel areas;
an upper surface of the step difference compensating layer in the white sub-pixel area forms the second step in a protrusion shape with an upper surface of the organic passivation layer in the adjacent sub-pixel area;
The first and second steps have opposite shapes,
Further comprising a column spacer disposed between the thin film transistor substrate and the color filter substrate,
The column spacer is made of the same material as the organic passivation layer and the step difference compensating layer, and is integrated with the organic passivation layer and the step difference compensating layer;
An area of the step compensation layer is larger than an area of the column spacer,
The color filter substrate includes a black matrix implemented based on the color filter overlapped with at least two layers, and an upper column spacer. delete delete The method of claim 1,
A cell gap of the red, green, and blue sub-pixel regions is the same as a cell gap of the white sub-pixel region in which the step difference compensation layer is disposed. 5. The method of claim 4,
A distance between the overcoat layer and the organic passivation layer in the red, green and blue sub-pixel regions is the same as a distance between the overcoat layer and the step difference compensation layer in the white sub-pixel region. delete delete a thin film transistor substrate having red, green, blue, and white sub-pixel regions;
an organic passivation layer formed on the red, green, blue and white sub-pixel regions of the thin film transistor substrate;
a protrusion-shaped step compensation layer disposed on the organic passivation layer of the white sub-pixel area except for the red, green, and blue sub-pixel areas;
a color filter substrate having color filters disposed on the red, green, and blue sub-pixel areas except for the white sub-pixel area;
an overcoat layer disposed on the red, green, blue and white sub-pixel regions on the color filter substrate;
the overcoat layer of the white sub-pixel region has a groove shape opposite to the protrusion shape disposed on the step difference compensation layer;
Further comprising a column spacer disposed between the thin film transistor substrate and the color filter substrate,
The column spacer is made of the same material as the organic passivation layer and the step difference compensating layer, and is integrated with the organic passivation layer and the step difference compensating layer;
An area of the step compensation layer is larger than an area of the column spacer,
The color filter substrate is a thin film transistor substrate including a black matrix implemented based on the color filter overlapped with at least two layers, and an upper column spacer. delete delete The method of claim 1,
The black matrix is implemented based on the color filter superimposed in two layers,
The upper column spacer is a liquid crystal display panel implemented based on the color filter overlapped in three layers. The method of claim 1,
The upper column spacer is positioned to correspond to the column spacer.

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