KR100244450B1 - Substrate manufacturing method of liquid crystal display device and substrate - Google Patents

Abstract

In the present invention, a switching element is formed on a first substrate, a non-insulating layer 123 is deposited to a predetermined thickness to cover the switching element, a BM 110 is formed to cover the switching element on the inorganic insulating layer 123 An inorganic insulating film 123 and an organic insulating film 156, which are covered on the drain electrode portion of the switching element, are formed on the first substrate on which the BM and the like are formed, A pixel electrode 140 connected to the drain electrode 115b is formed through the contact hole 131. The pixel electrode 140 is connected to the drain electrode 115b through the contact hole 131, And a step of forming an alignment layer (100) on the first substrate so as to solve the problem of light leakage around the BM, thereby improving the aperture ratio and contrast of the liquid crystal display device, Contamination of So as not to be contaminated with the liquid crystal was to provide a liquid crystal display of the picture clarity.

Description

A method of manufacturing a substrate of a liquid crystal display and a structure of a substrate manufactured by the method

An object of the present invention is to provide a liquid crystal display device having a cell gap more uniform than a conventional liquid crystal display device and a method of manufacturing the liquid crystal display device.

It is still another object of the present invention to provide a liquid crystal display device having a structure for preventing liquid crystal from being contaminated by impurities from BM itself and a method for manufacturing the liquid crystal display device.

It is still another object of the present invention to provide a liquid crystal display device and a method of manufacturing the liquid crystal display device that prevent light leakage due to rubbing failure around the BM.

It is still another object of the present invention to provide a liquid crystal display device having an aperture ratio larger than that of a conventional liquid crystal display device and a method of manufacturing the liquid crystal display device.

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a liquid crystal display device incorporating a switching element for driving or controlling liquid crystal. (First substrate) on which a TFT and a pixel electrode are formed in a liquid crystal display device using a thin film transistor (TFT) as a switching element, and a structure of a first substrate manufactured by the manufacturing method.

One example of the structure of a general liquid crystal display will be described with reference to FIG.

The liquid crystal display of FIG. 1 has a first substrate 3 on which a plurality of pixels are arranged in a matrix. Each pixel electrode 4 of the liquid crystal display part of the first substrate 3 is disposed at a portion where the adjacent gate bus line 17 and the adjacent data bus line 15 are crossed. The gate bus line 17 is formed horizontally and a gate electrode 17a branched from the gate bus line 17 is formed. The data bus line 15 is formed as a seed and a source electrode 15a branched from the data bus line 15 is formed. A TFT 8 is formed at a portion where the source electrode 15a and the gate electrode 17a intersect and a drain electrode 15b is formed to be in electrical contact with the pixel electrode 4. [ A BM is formed on the TFT 8 of the first substrate 3, the gate bus line 17 and the data bus line 15, and an alignment film is formed on the entire surface of the first substrate 3 on which the BM is formed.

The BM and the orientation film are not shown on the first substrate 3 in Fig. 1 in order to avoid complicating the drawing.

On the other hand, the second substrate 2 on which the color filter layer 37 and the like are formed is formed opposite to the first substrate 3.

A liquid crystal 40 is sandwiched between the first substrate 3 and the second substrate 2.

On the outer surfaces of the first substrate 3 and the second substrate 2, a funnel plate 1, 1a is formed.

The above-described various components are combined to complete a liquid crystal display device.

The structure of a conventional first substrate 3, which is related to the object of the present invention, will be described in detail with reference to FIGS. 2A and 2B showing a cross-sectional view taken along line II-II of FIG.

2A showing the conventional first substrate 3 is as follows.

On the transparent substrate 11, a gate electrode 17a which branches off from the gate bus line is formed. An anodic oxide film 35 is formed on the gate electrode 17 in order to improve insulation and prevent hillock. A gate insulating film 23 made of an inorganic insulating film such as SiNx or SiOx is formed on the transparent substrate 11 on which the gate electrode 17a is formed.

A semiconductor layer 22 made of amorphous silicon (hereinafter referred to as a-Si) or the like is formed on the gate insulating film 23 of the gate electrode 17a. An ohmic contact layer 25 is formed on the semiconductor layer 22. A source electrode 15a and a drain electrode 15b which are branched from the data bus line 15 to be in contact with the ohmic contact layer 25 are formed with a predetermined gap therebetween.

A protective film 26 made of an inorganic insulating film such as SiNx is formed to cover the source / drain electrodes 15a and 15b. A pixel electrode 4 is formed on the protective film 26 to contact the drain electrode 15b through the contact hole 31 of the drain electrode portion. The BM 110 is formed in a predetermined pattern on the substrate on which the pixel electrode 4 is formed. The BM 110 is formed so as to cover the TFT 8, the gate bus line 17, the data bus line 15, and the like in the pattern of FIG. On the substrate on which the BM 110 is formed, a migration membrane 100 made of a polyimide membrane or the like is formed. Numeral 40 in Fig. 2A is a liquid crystal.

The structure of FIG. 2B showing another conventional first substrate 3 is similar to that of FIG. 2A. However, in order to solve the rubbing defect of the alignment film 100, the alignment film 100 is first formed and the alignment film is rubbed 2A in that the BM 110 is formed.

The numbers in FIG. 2B are the same as those in FIG. 2A.

However, the liquid crystal display device constructed by fabricating the first substrate 3 with the above-described conventional manufacturing methods causes various problems as follows.

2A, when the alignment layer 100 is formed after the pixel electrode 4 and the BM 110 are formed, the portion of the BM 110 may be positioned closer to the pixel electrode 4 than the pixel electrode 4, The rubbing failure occurs in the stepped portion 133 of the alignment film, light leakage occurs along the region where the rubbing failure occurs, and the liquid crystal display device Resulting in deterioration of display quality and contrast.

For the sake of understanding, the process of forming the alignment layer and the rubbing will be described with reference to the structure of FIG. 2A.

The alignment film of FIG. 2A is formed by forming an alignment film (not shown) of polyimide, polyamide, or silicon oxide (SiO ₂ ) on the alignment film printing roller 150 shown in FIG. 5, 100 are printed to a predetermined thickness and then transferred to the first substrate 3 on which the BM 110 is formed. The thickness of the BM is generally 1 to 2.5 占 퐉. After the alignment film 100 transferred to the first substrate 3 is cured, a rubbing process is performed to align the liquid crystal in a predetermined direction. 6, the rubbing drum 130 is attached to the rubbing drum 131, the rubbing drum 130 is pressed at a constant pressure in the B direction, and the rubbing drum 131 rotating in the A direction is moved in the C direction, A straight groove in a certain direction is formed on the surface of the substrate.

In FIG. 4, D1 (the portion 133 in FIG. 6) is a region where the BM 110 is not rubbed even when the alignment film 100 is printed, and becomes a region where light is emitted when the liquid crystal display device is completed.

A region where light is leaked around the pattern of the BM 110 when the alignment film 100 is applied on the substrate on which the BM 110 is formed and rubbed is well shown in FIG.

FIG. 4 shows a state in which light leaks along the periphery of the BM pattern. When the thickness of the BM is 1 to 2.5 占 퐉, the width of D1 is about 1 to 2 占 퐉.

As described above, it has been understood that the leakage of light occurs at the stepped portion of the alignment film, and the display quality and the contrast of the liquid crystal display device are lowered.

Of course, by orienting the alignment film of the liquid crystal display device by using polyvinyl cinnamate (PVCN), polyvinyl fluoride nordinimate (PVCN-F), polysiloxane series or polyvinyl chloride (PVC) It is possible to prevent the light leakage from occurring in the liquid crystal display device, but the unevenness of the cell gap of the liquid crystal display device described below still remains as a problem to be solved.

Second, in the structure of the first base plate 3 as shown in FIG. 2A and FIG. 2B in which the film formed on the substrate is not flat, the cell gap of the liquid crystal display device is uniformly formed The display quality and yield of the liquid crystal display device due to poor liquid crystal injection are reduced.

Particularly, the BM is generally a pigment-dispersed black material having no conductivity due to the dispersion of organic pigments in a high-sensitivity negative photosensitive resin, and a material having heat resistance up to 260 DEG C is used. In the same structure, since the liquid crystal is contaminated by impurities of BM and coloring matter of BM generated when the BM 110 is coated and patterned, the display quality of the liquid crystal display device is deteriorated.

Thirdly, in the structure of the first substrate of the conventional liquid crystal display device, the pixel electrodes can not be formed by superimposing the pixel electrodes on the ITA bus line or the like due to the step difference of the film constituting the element, the rubbing defect of the orientation film, or the high dielectric constant of the inorganic film.

If the pixel electrodes are overlapped on the data bus line or the like in the conventional first substrate structure with the inorganic insulating film interposed therebetween, the voltage of the data bus line and the voltage of the pixel electrode in the overlapped portion cause a distortion phenomenon, And light leakage due to rubbing failure occurs.

Therefore, in order to form a pixel electrode which does not cause leakage of light or flicker of a screen, conventionally, a pixel electrode is formed at a position spaced a predetermined distance from a step of a data bus line or the like.

This causes a decrease in the aperture ratio of the liquid crystal display device. The cross-sectional structure thereof is shown in Fig. 7 as one example.

7 is a cross-sectional view taken along line VII-VII of FIG. 3, which is a plan view of a conventional liquid crystal display device.

In FIG. 7, reference numeral 13 denotes a substrate, 115 denotes a data bus line, 126 denotes a gate insulating film, 140 denotes a pixel electrode, 100 denotes an alignment film, and 110 denotes a BM.

7, the monolithic data bus line 115 and the gate insulating film 123 made of an inorganic insulating film such as SiNx or SiOx cover the stepped data bus line 115 and are spaced apart from the data bus line 115 by D2 And the pixel electrode 140 is formed at a position where the pixel electrode 140 is formed. D1 is a region in which the width of the BM 110 is wide in consideration of the adhesion error between the first substrate and the second substrate in the subsequent modulating process.

Therefore, it can be easily understood that an aperture ratio loss as much as D3 is obtained by adding D1 and D2.

As described above in detail, a conventional method of manufacturing a liquid crystal display device in which a BM or the like is formed on a first substrate has a problem that a portion where an alignment film is not applied due to a step difference in the BM occurs and a rubbing defect occurs in the alignment film, It happens.

In order to prevent light leakage around the BM, an alignment film may be formed first and rubbed to form a BM. However, there is a problem that a liquid crystal is contaminated by BM impurities, and a cell gap cell gap defects still remain to be solved.

In addition, there has been a limit to the improvement of the aperture ratio of the liquid crystal display device due to the step difference of the film and the high relative dielectric constant of the inorganic insulating film.

In order to solve the above problems, the present invention has focused on a film (hereinafter referred to as a flattening film) capable of flattening a surface while completely covering the surface of the BM formed substrate.

When the flattening film is applied on the substrate on which the BM is formed, and the alignment film is coated on the flattening film and the rubbing is performed, no rubbing defect occurs because there is no step portion in the alignment film.

Further, since the planarizing film completely covers the BM, the contamination of the liquid crystal due to impurities of the BM can be suppressed.

Furthermore, even if the pixel electrode is formed so as to overlap with the data bus line or the like by using the planarizing film having a dielectric constant higher than that of the inorganic insulating film, the insulating property is maintained, thereby maximizing the aperture ratio.

The manufacturing method of the present invention using the planarizing film will be briefly summarized as follows. Forming a switching element on the transparent substrate; depositing an inorganic insulating film to a predetermined thickness to cover the switching element; forming BM on the inorganic insulating film so as to cover the switching element; A planarization film having a good leveling characteristic over the step difference is applied, and an inorganic insulating film and a part of the planarization film covered on the drain electrode portion of the switching element are removed by etching or the like to form a contact hole, And forming an alignment film on the first substrate 3 on which the pixel electrodes are formed.

As the planarizing film, an organic insulating film such as benzocyclobutene (BCB) or SOG (Spin On Glass) is used. The characteristics and the manufacturing method of the present invention will be described in detail in embodiments.

FIG. 1 is a perspective view of a basic structure of a general liquid crystal display device.

2 is a cross-sectional view of a first substrate of a conventional liquid crystal display device.

FIG. 3 is a plan view showing a pattern shape of a conventional black matrix. FIG.

FIG. 4 is a perspective view showing a mode in which light is leaked around the black matrix pattern in the conventional liquid crystal display device.

FIG. 5 is a view for explaining a general alignment film application process.

FIG. 6 is a view for explaining a general rubbing process of an orientation film.

7 is a cross-sectional view taken along line VII-VII of FIG. 3;

FIG. 8 is a process diagram for manufacturing a first substrate of a liquid crystal display device according to the present invention.

FIG. 9 is a plan view of the liquid crystal display device of the present invention. FIG.

10 is a cross-sectional view taken along the line X-X of FIG. 9;

11 is a sectional view showing still another example of the first substrate of the liquid crystal display device of the present invention.

A method of manufacturing the first substrate 3 of the liquid crystal display device of the present invention will be described with reference to the process sectional view of FIG.

[Example 1]

An aluminum (Al) metal film or the like is deposited on the transparent substrate 11, a photoresist is coated on the metal film, the photoresist is developed to have a predetermined pattern, and the metal film is wet ) Etching or the like to form the gate electrode 117a which branches off from the gate bus line. It is preferable that the gate electrode 117a is formed in a tapered shape in order to improve the step (Fig. 8A)

Next, an anodic oxide film 135 is formed on the gate electrode 117a or the like to improve insulation and prevent hillock (FIG. 8B).

An a-Si layer serving as the semiconductor layer 122 and an n ⁺ a-Si layer serving as the ohmic contact layer 125 are successively deposited on the inorganic insulating film such as SiNx and SiOx to be the gate insulating film 123, (FIG. 8C).

Subsequently, a photoresist is applied on the n ⁺ -type a-Si layer, the photoresist is developed to have a predetermined pattern, and the n ⁺ -type a-Si layer and the a-Si layer are simultaneously etched according to the developed pattern, The semiconductor layer 125 and the semiconductor layer 122 are formed (FIG. 8D).

Then, a Cr or Al metal film or the like is deposited on the entire surface of the substrate by sputtering or the like, a photoresist is coated on the metal film, the photoresist is developed to have a predetermined pattern, The source electrode 115a and the drain electrode 115b which are branched from the data bus line are etched to form the source electrode 115a and the drain electrode 115b formed by the etching as an etching mask to form an ohmic contact layer The ohmic contact layer 125 is etched at the central portion thereof so as to separate the ohmic contact layer 125 and the ohmic contact layer 125 (FIG. 8E).

Next, an inorganic insulating film such as SiNx, SiOx, or the like to be the protective film 126 is deposited to a thickness of about 200-500 Å (FIG. 8F).

Although the protective layer 126 may not be formed, BM formed in the subsequent process is formed to prevent the TFT characteristics from becoming unstable due to the influence of the semiconductor layer.

Then, a black pigment made of a pigment-dispersed black material having no conductivity by dispersing an organic pigment in a high-sensitivity negative photosensitive resin and a black polyimide resin having heat resistance up to 260 DEG C, The photoresist is coated on the BM film, the photoresist is developed to have a predetermined pattern, and the black resin is etched according to the developed pattern to form the BM 110 8g).

Subsequently, a BCB, a PFCB (Pefluorocyclobutane), an F-doped Bahrain, a Teflon, a Cytop, a fluorinated polyarylether and the like having an Si bonding structure and an SOG On Glass) or the like. (Fig. 8H). The organic insulating film 156, which is a planarizing film formed on the BM, has a leveling characteristic exceeding a level difference, so that the level difference of the BM film can be flattened.

It is possible to prevent the rubbing failure of the alignment film which proceeds in the subsequent steps from the advantages obtained by the planarization of the film, so that light leakage can be prevented and the cell gap can be maintained uniformly as the film is flattened, The image quality is improved.

In addition, since the organic insulating film has a lower relative dielectric constant than the inorganic insulating film, even if the pixel electrode formed on the organic insulating film is superimposed on the data bus line or the like to maximize the pixel electrode, a voltage distortion phenomenon The flicker of the screen of the liquid crystal display device does not occur.

A structure in which a pixel electrode is overlapped on a data bus line or the like in a first substrate having an organic insulating film formed on a BM and a pixel electrode is formed larger than a conventional one will be described with reference to Figs.

9 shows an example of a top view of a liquid crystal display device having a structure in which BM 110 is formed to have consistency with data bus line 115 or the like and pixel electrode 140 is superimposed on data bus line 115 to increase the aperture ratio to be.

9, the BM 110 may not be formed when the data bus line 115 is opaque. However, in the present invention, in order to reliably prevent light leakage, a BM (110). 9A is a plan view of a first substrate provided with a TFT 8 having an I-shaped channel, and Fig. 9B is a plan view of a first substrate provided with a TFT 8 having an L- The present invention can be applied regardless of the above.

9, the data bus line 115 and the BM 110 are formed to be in conformity with each other. In this case, the pixel electrode 140 is formed to overlap the data bus line And the rubbing failure of the alignment film does not occur in the region functioning as the pixel electrode.

13, reference numeral 13 denotes a transparent substrate, reference numeral 100 denotes an alignment film, reference numeral 126 denotes a gate insulating film, and reference numeral 156 denotes an organic insulating film.

10 for illustrating the structure of the present invention and FIG. 7 for illustrating the conventional structure will be described in order to facilitate understanding.

Here, it is assumed that the data bus lines 115 of FIGS. 10 and 7 are formed to have the same width.

10 and FIG. 7, it can be seen that the pixel electrode 140 is larger by D3 than the pixel electrode 140 of FIG. 7 in FIG.

10D, since the light is blocked by the BM, even if the pixel electrode is formed, the pixel electrode 140 is not included in the opening region of the pixel. By thus forming the pixel electrode 140 on the BM 110, the aperture ratio can be maximized have.

In addition to the data bus lines, TFTs, gate bus lines, and BMs may be formed to have conformity, and a detailed process description thereof will be omitted.

As can be seen from the above description, the organic insulating film or the like, which is a planarization film, is formed on the BM to increase the aperture ratio of the liquid crystal display device.

Another advantage obtained by forming the organic insulating film on the BM is that since the BM is completely blocked by the organic insulating film and contaminants such as pigment coming from the BM material itself do not come into contact with the liquid crystal, Can be provided.

Subsequently, a photoresist is coated on the organic insulating film 156, the photoresist is developed to have a predetermined pattern, and the organic insulating film 156 is etched according to the developed pattern to form a contact hole 131, ITO (Indium Tin Oxide) is deposited on the gate insulating layer 156 and the ITO layer is patterned by a photolithography process to form a pixel electrode 140 (FIG. 8I).

After the pixel electrode 140 is formed, one of polyimide, poly amide, or silicon oxide (SiO ₂ ) is selected to form an alignment layer 100, and then rubbed to form a microwave. (Fig. 8J). Another method for forming a microwave in an alignment layer is polyvinyl cinnamate (PVCN), polyvinylfluorouxiniminate (FVCN-F), polysiloxane-based or polyvinyl chloride (PVC) And so on.

Although the embodiment of the present invention has been described as an example of the first substrate 3 having an IOP (on-passivation) structure, the pixel electrode 140 may be formed as shown in FIG.

In the method of manufacturing a liquid crystal display device in which a BM is formed on a first substrate 3, an inorganic insulating film such as SiNx is deposited on a substrate having a switching element formed thereon to a predetermined thickness, a BM is formed to cover the switching elements, An organic insulating film such as benzocyclobutene (BCB) is coated thereon and an alignment film is formed thereon. As a result, as shown in FIG. 4, the problem of light leakage around the BM is fundamentally solved to provide a clearer image quality by improving contrast than conventional liquid crystal display devices. Further, the aperture ratio can be improved, and a bright screen can be provided. Furthermore, since the surface of the substrate of the liquid crystal display device is planarized, the cell gap can be uniformly maintained, thereby solving the problem caused by poor liquid crystal injection.

In addition, since the BM is completely blocked by the organic insulating film, contaminants such as pigments coming from the BM material itself do not come into contact with the liquid crystal, so that a clean image quality liquid crystal display device free from unevenness can be provided.

Claims (18)

Forming a data bus line and a gate bus line on a transparent substrate; forming a switching element on the transparent substrate so as to be connected to the data bus line and the gate bus line; forming a black matrix A step of forming a planarization film covering the data bus line, the gate bus line and the black matrix on the transparent substrate, and a step of forming an alignment film on the planarization film, The method of claim 1, Wherein the black matrix is formed so as to cover the gate bus line and the data bus line. The method of claim 1, Further comprising the step of applying an inorganic insulating film so as to cover the switching element before forming the black matrix. The method of claim 3, Wherein the inorganic insulating film is any one selected from the group consisting of SiNx and SiOx. The method according to any one of claims 1 to 4, Wherein a step of forming a pixel electrode on the planarizing film before forming the alignment film is further added. The method of claim 5, further comprising: Wherein the pixel electrode is formed by selectively overlapping the data bus line and the gate bus line. The method according to any one of claims 1 to 4, Wherein the planarizing film is an organic insulating film. The method of claim 7, Wherein the organic insulating film is a BCB. The method according to any one of claims 1 to 4, Wherein the planarization film is SOG. A switching element connected to a data bus line and a gate bus line formed on a transparent substrate; a black matrix for covering the switching element; and a black matrix for covering the black matrix, the data bus line, the gate bus line, A planarizing film, and an alignment film formed on the planarizing film. The method of claim 10, Wherein said black matrix also covers gate bus lines and data bus lines. The method of claim 10, Wherein an inorganic insulating film is further added between the switching element and the black matrix. The method of claim 12, Wherein the inorganic insulating film is any one selected from the group consisting of SiNx and SiOx. The method according to any one of claims 10 to 13, And a pixel electrode is further added between the planarization film and the alignment film. 15. The method of claim 14, Wherein the pixel electrode is formed by selectively overlapping the data bus line and the gate bus line. The method according to any one of claims 10 to 13, Wherein the planarizing film is an organic insulating film. The system of claim 16, Wherein the organic insulating film is a BCB. The method according to any one of claims 10 to 13, Wherein the planarizing film is SOG.