JPH1096963A - Liquid crystal display device and manufacturing method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid crystal display device which has a uniform cell gap, prevents liquid crystal from being contaminated by black matrix or its pigment, and also prevents optical leakage from occurring at a step part of the black matrix. SOLUTION: This manufacturing method has a process for forming a switching element on a first substrate 103, a process for vapor-depositing a fixed thickness of inorganic insulation layer 123 to cover the switching element, a process for forming a black matrix 110 to cover the switching element on the inorganic insulation layer 123, a process for coating an organic insulation layer 156, etc., to reduce a step on the first substrate where the black matrix is formed, removing a part of the inorganic insulation layer 123 and organic insulation layer 156 covering a drain electrode 115b of the switching element by means of etching, etc., and forming a contact hole 131, a stage for forming a picture element electrode 104 connected with a drain electrode 115b through the contact hole 131, and a stage for forming an orientation film 100 on the first substrate on which the picture element electrode 104 was formed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a liquid crystal display device and a method for manufacturing the same. In particular, the present invention relates to a substrate of a liquid crystal display device having a thin film transistor and a method of manufacturing the same.

[0002]

2. Description of the Related Art The structure of a conventional liquid crystal display device will be described with reference to FIG. The liquid crystal display device has a first substrate 3 on which pixels are arranged in a matrix. The first substrate 3
On the pixel electrodes 4 are formed, and each of the pixel electrodes 4 is formed.
Are surrounded by the gate bus wiring 17 and the data bus wiring 15. Further, a gate electrode 17a branched from the gate bus wiring 17 and a source electrode 15a branched from the data bus wiring 15 are formed. The thin film transistor 8 is formed at an intersection of the gate bus line 17 and the data bus line 15. The drain electrode 15b of the thin film transistor is formed so as to be in electrical contact with the pixel electrode 4. Black matrix (light blocking layer)
Are formed so as to cover the thin film transistor 8, the gate bus wiring 17, and the data bus wiring 15. An alignment film (alignment layer) is formed on the entire surface of the substrate including the black matrix.

The second substrate 2 having the color filter layer 37
Are arranged so as to face the first substrate 3 with a gap. A liquid crystal material 40 is sealed in a gap between the first substrate and the second substrate. By attaching the polarizing plates 1 and 1a to the outer surfaces of the first and second substrates, a panel of a conventional liquid crystal display device is completed.

A structure of a first substrate of a conventional liquid crystal display device will be described in detail with reference to FIGS. 2 and 3 are cross-sectional views taken along the line II ′ of FIG. The manufacturing method and structure of the first substrate 3 of the conventional liquid crystal display will be described with reference to FIG.

Gate electrode branched from gate bus line 17
17a is formed on the transparent substrate 3. Anodized film 35
Is formed on the gate electrode 17a in order to improve insulation properties and prevent hillocks. A gate insulating film 23 made of an inorganic substance such as SiNx or SiO ₂ is formed on the entire surface of the substrate including the gate electrode 17a. A semiconductor layer 22 made of amorphous silicon (a-Si) is formed on a gate insulating film 23 on the gate electrode 17a. Amorphous silicon (n ⁺ a
-Si) is formed. The source electrode 15a and the drain electrode 15b branched from the data bus line 15 are formed on the impurity semiconductor layer 25 at a constant interval. Thus, the source electrode 15a and the drain electrode 15b are in ohmic contact with the impurity semiconductor layer 25. The inorganic protective film 26 such as SiNx includes the source electrode 15a and the drain electrode 15b.
The substrate is formed so as to cover the entire surface of the substrate. The pixel electrode 4 is connected to the drain electrode 15b through a contact hole formed in the protective film 26 on the drain electrode 15b.
An electrical contact is made to b and is formed on the protective film 26. The black matrix 10 is formed so as to cover the thin film transistor 8, the gate bus wiring 17, and the data bus wiring 15 (FIGS. 4 and 5). Subsequently, an alignment film 11 made of, for example, polyimide is formed thereon by coating.

Further, another structure of the first substrate 3 of the conventional liquid crystal display device will be described with reference to FIG. 3, which is the same as the component of FIG. In this case, the alignment film 11 is formed before the formation of the black matrix 10 in order to prevent rubbing defects from occurring in the alignment film 11 near the black matrix.

However, the liquid crystal display device having the structure shown in FIG. 2 or FIG. 3 has the following problems. First, as shown in FIG. 2, in the structure of the first substrate, the alignment film has a step formed by the pixel electrode 4 and the black matrix 10. As a result, rubbing failure occurs at a step portion of the alignment film, and light leaks. Therefore, the contrast characteristics of the liquid crystal display device deteriorate. In order to understand the rubbing process and the structure of the alignment film, a detailed description will be given below with reference to FIGS.

FIG. 6 is a sectional view taken along the line III-III 'of FIG. The alignment film 11 shown in FIG. 2 is formed by printing an alignment film material such as polyamide, polyimide and silicon oxide on a print roller and transferring the printed material onto the entire surface of the first substrate 3 including the black matrix 10. It is formed. After the alignment film is solidified, a rubbing process is performed so that the liquid crystal is aligned in a certain direction. In the rubbing step, as shown in FIG.
1 is used to form a groove in a certain direction (portion like a waveform in the figure) on the alignment film. The rubbing drum 131
Is covered with a rubbing cloth 130, rotates in the direction A while being pressed at a constant pressure in the direction B, and moves in the direction C. D ₀ portion indicated by hatching in FIG. 5 (133 parts of FIG. 7)
In the case, a rubbing defect occurs due to a step caused by the black matrix 10. When the thickness of the black matrix is 1 to 2.5 μm, the width of D ₀ in FIG.
２2 μm. Such regions include polyvinylcinnamate (PVCN), polyvinylfluorocinnamate (PVCN-
F)), polysiloxanes, or polyvinylchloride (PVC) can be used in the alignment film and removed by photoalignment. However, the problem of the defective cell gap cannot be solved.

Second, as shown in FIGS. 2 and 3, in the conventional liquid crystal display device, the first substrate 3 has a step on the surface due to a multilayer structure including a black matrix 10.
This causes a non-uniform cell gap in the liquid crystal display device. Therefore, the non-uniform cell gap destabilizes the injection of liquid crystal, thereby lowering the display quality and yield of the liquid crystal display device. Further, as shown in FIG. 3, when the liquid crystal directly contacts the black matrix, the image quality characteristics of the liquid crystal display device are not maintained. The black matrix or pigment contaminates the liquid crystal. Generally, the black matrix consists of a negative photoresist containing a black pigment.

Third, in the conventional liquid crystal display device, a step is formed on the surface of the first substrate, rubbing failure of the alignment film occurs, and the dielectric constant of the inorganic insulating film (protective film 26) is low. It was impossible to form the pixel electrode so as to overlap the data and the gate bus wiring. If the pixel electrode is formed so as to overlap with the data bus line located below the inorganic insulating film, a screen display flickers due to interference between the voltage of the data bus line and the voltage of the pixel electrode. Further, in the overlapping portion, light leakage occurs due to rubbing failure. Therefore, the pixel electrode is generally located at a certain distance from the data bus line. In this case, as shown in FIG. 8, it is impossible to obtain a high aperture ratio. In FIG. 8, an inorganic insulating film 26 such as SiNx or SiO ₂ covers the data bus line 15 having a step, and the pixel electrode 4 is formed at a position separated from the data bus line 15 by D ₂ . D ₁ is the first substrate and the second substrate
This is a region formed in consideration of a bonding margin with the substrate. Therefore, in the conventional liquid crystal display device, the aperture ratio has a loss of D ₃ = (D ₁ + D ₂ ).

As described above, the first substrate has a step formed on the surface by the black matrix, and the black matrix is in direct contact with the liquid crystal material. Therefore, light leakage occurs near the black matrix,
This results in non-uniform failure of the cell gap, contamination of the liquid crystal, and a low aperture ratio.

[0012]

SUMMARY OF THE INVENTION An object of the present invention is to provide a liquid crystal display having a uniform cell gap. Another object of the present invention is to prevent liquid crystal contamination of a liquid crystal display device with a black matrix or a pigment thereof. It is another object of the present invention to prevent light leakage at a step portion of a black matrix due to a rubbing defect of an alignment film in a liquid crystal display device.
Another object of the present invention is to provide a liquid crystal display device having an improved aperture ratio.

[0013]

According to the present invention, there is provided a method of manufacturing a first substrate of a liquid crystal display device, comprising the steps of: forming a data bus line and a gate bus line on a transparent substrate; Forming a switching device connected to the data bus line and the gate bus line;
Forming a black matrix covering the switching element, forming a flattening film covering the data bus wiring, the gate bus wiring and the black matrix, and forming an alignment film on the flattening film. including.

The structure of the first substrate of the liquid crystal display device according to the present invention comprises a substrate, switching elements connected to gate bus lines and data bus lines formed on the transparent substrate, and a black matrix covering the switching elements. And a flattening film covering the black matrix, the data bus wiring, the gate bus wiring and the transparent substrate,
An alignment film that covers the flattening film.

Further, another structure of the first substrate of the liquid crystal display device according to the present invention includes a substrate, a transistor having a gate electrode, a source electrode, and a drain electrode on the substrate, a protective layer on the transistor, A light blocking layer formed on a part of the protection layer on the transistor, and a planarization film formed on the light blocking layer and the protection layer and having a contact hole on the source electrode or the drain electrode; A pixel electrode contacting the source electrode or the drain electrode through the contact hole of the planarization film, and an alignment film on the pixel electrode.

According to another method of manufacturing a first substrate of a liquid crystal display device according to the present invention, a transistor having a gate electrode, a drain electrode and a source electrode is formed on a substrate, and a light blocking layer is formed on the transistor. And a step of forming a planarization film on the entire surface of the substrate including the light blocking layer, and a step of forming an alignment film on the planarization film.

Another structure of the first substrate of the liquid crystal display device according to the present invention includes a substrate, a transistor having a gate electrode, a source electrode, and a drain electrode on the substrate, and a pixel contacting the source electrode or the drain electrode. An electrode, a protective layer on the transistor and the pixel electrode,
The transistor includes a light blocking layer on a part of the protective layer of the transistor, a planarizing film on the light blocking layer and the protective layer, and an alignment layer on the planarizing film.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1 A method for manufacturing a first substrate of a liquid crystal display according to Embodiment 1 of the present invention will be described with reference to FIGS.
Aluminum metal is deposited on the first transparent substrate 103. A photoresist is coated thereon and patterned. As shown in FIG. 9, the aluminum film
Etching is performed by, for example, a wet etching method to form the gate electrode 117a and the gate bus wiring. The gate electrode 117a is desirably formed in a tapered shape in order to eliminate a step. Further, as shown in FIG. 10, the gate electrode 117a is anodized to prevent hillocks and to improve insulation, so that an anodic oxide film 135 is formed. The gate insulating film 123 made SiNx, or of SiO ₂ thereon, a-Si 122
And n ⁺ a-Si 125 are continuously deposited. A photoresist is coated and patterned on the surface. As shown in FIG. 12, the semiconductor layer 122 and the impurity semiconductor layer 125 are formed by etching the a-Si and the n ⁺ a-Si according to the patterned photoresist.

Subsequently, a metal made of Cr or Al is deposited on the entire surface of the substrate to form a metal film. A source electrode 115a, a data bus wiring, and a drain electrode 115b are formed by the same method as the method of forming the gate electrode. Using the source electrode 115a and the drain electrode 115b as an etching mask, the central portion of the impurity semiconductor layer 125 is removed by etching (FIG. 13). The impurity semiconductor layer 125 includes the source electrode 115a and the drain electrode 115b, respectively.
To form two separate portions that are in ohmic contact. Then, as shown in FIG.
(Thickness 200 to 500 Å) is formed by vapor deposition of an inorganic material such as SiNx or SiO _2. Generally, the semiconductor layer 122
This insulating film formed on the upper part
And to prevent contamination from the black matrix 110. However, when the contamination of the black matrix is not so problematic,
The protective film 126 may be omitted.

The surface of the protective film 126 is coated with a black resin (1 μm thick).
m or more) is deposited. A negative photoresist containing a black pigment in polyimide is used as the black resin.
The processing temperature of this material is about 260 ° C. As shown in FIG. 15, the black resin is patterned to form a black matrix 110 (light blocking layer). Then, as shown in FIG. 16, benzocyclobutene (BC
B), PFCB, fluorinated parylene
parylene), teflon, cytop (cyto
p) or fluoropolyaryl ether (fluoropolya
A flattening film 156 made of an organic material having a Si group such as (rylether) or a material (spin on glass (SOG)) spin-coated on a glass substrate is formed. The flattening film 156 has a flat surface by eliminating a step in the lower multilayer structure. The flattening layer makes the cell gap between the two substrates uniform and improves the quality of the liquid crystal display by reducing instability when injecting liquid crystal into the cell gap. Further, the flattening film of the present invention can prevent light leakage from near the step of the black matrix by providing uniform rubbing of the alignment film.

Subsequently, a contact hole is formed on the drain electrode through the planarization film 156 and the protection film 126. Then, as shown in FIG. 17, ITO (indiu
m tin oxide) is deposited on the entire surface of the substrate and patterned to become the pixel electrode 104.

Finally, as shown in FIG. 18, an alignment film 111 made of polyimide, polyamide, or silicon oxide is used.
(Orientation layer) is formed and rubbed so as to have a groove (pattern like a waveform) on its surface. The pattern such as the waveform is, for example, polyvinylcinnamate (polyvinylcinnamate (PVCN)), polyvinylfluorocinnamate (polyvinylfluorocinnamate (PVCN-F)), polysiloxane (polysiloxanes), or polyvinyl chloride (polyvinylchloride (PVC)). It can also be obtained by photoaligning (photo-aligning) the film.

Generally, the planarization film 156 of the present invention uses a material having a lower dielectric constant than a conventional inorganic insulating film. Therefore, the pixel electrode 104 can be formed so as to be enlarged so as to overlap data or a gate bus line. The structure of the enlarged pixel electrode 104 will be described with reference to FIGS. 19, 20 and 21. The black matrix 110 may be omitted when the data bus line 115 is made of an opaque material. However, in order to completely eliminate light leakage, it is preferable to form the black matrix 110 on the data bus wiring 115. FIG. 19 is a plan view of a first substrate showing a thin film transistor 108 having an I-type channel, and FIG. 20 is a plan view of a first substrate showing a thin film transistor 108 having an L-type channel. FIG. 21 is a sectional view taken along the line IV-IV ′ of FIG. As can be seen from this figure, the black matrix 110 is formed so as to coincide with the data bus wiring 115. Then, the pixel electrode 104
Are formed so as to overlap the data bus wiring 115. Therefore, the area of the effective pixel electrode (excluding the d width in FIG. 21) increases. Also, there is no rubbing defect in the effective pixel area.

In order to explain the present invention in more detail, FIG. 21 of the present invention is compared with FIG. 7 of the related art. The data bus wiring 15 of FIG. 7 and the data bus wiring 115 of FIG.
Assume they have the same width. Here, the pixel electrode 104 in FIG. 21 is connected to the pixel electrode 4 in FIG.
More D ₃ just wide. In FIG. 21, a region d, which is a part of the pixel electrode 104, is not an effective pixel electrode region because light is blocked by the black matrix 110.

The size of the pixel electrode 104 can be further increased by forming the black matrix 110 so as to match the thin film transistor 108 and the gate bus line 117. Therefore, the application of the planarizing film 156 on the black matrix 110 improves the aperture ratio of the liquid crystal display. In addition, since the flattening film separates the liquid crystal from the black matrix 110, the black matrix 110,
Alternatively, it is possible to prevent contamination of the liquid crystal substance by the color pigment.

(Embodiment 2) FIG. 22 shows Embodiment 2 of the present invention.
Is shown. Embodiment 1 shows a case where the pixel electrode 104 is formed on the protective film 126 (ITO on passivation film: IOP). Embodiment 2 shows that the pixel electrode 104 is protected as shown in FIG. A planarization film 156 is formed on the structure formed under the film 126.
Is applied.

The advantages of the present invention according to the second embodiment are the same as those of the first embodiment. A detailed description of the second embodiment will be omitted because it is the same as that of the first embodiment. The method for manufacturing a first substrate of a liquid crystal display device according to the present invention relates to forming a flattening film on a surface having a step formed by a black matrix or the like. The flattening film provides a uniform cell gap required for improving an aperture ratio, suppressing light leakage in a region near the black matrix, and stably injecting liquid crystal. Further, a high-quality liquid crystal display device can be obtained by preventing contamination of the liquid crystal substance from the black matrix or its pigment. This is because the planarizing film separates the liquid crystal material from the black matrix.

[0028]

According to the present invention, a flattening film is used in a method for manufacturing a first substrate, and the flattening film uniformly and uniformly forms a step of a multilayer structure including a black matrix before forming an alignment film. Let Therefore, since the flattening film has a flat surface, the alignment film to be subsequently formed also has a flat surface.
As a result, a uniform cell gap between the substrates of the liquid crystal display device can be obtained. Further, a uniform groove can be formed on the entire surface of the alignment film, and light leakage can be prevented. Since the flattening film separates the liquid crystal from the black matrix,
Liquid crystal contamination can also be prevented. Further, since the dielectric constant of the flattening film of the present invention is lower than that of the conventional inorganic insulating film, the pixel electrode can be formed so as to overlap the data bus wiring. Therefore, the aperture ratio is improved.

[Brief description of the drawings]

FIG. 1 is a perspective view showing the structure of a conventional liquid crystal display device.

FIG. 2 is a cross-sectional view showing a first substrate in a conventional liquid crystal display device.

FIG. 3 is a cross-sectional view showing a first substrate in a conventional liquid crystal display device.

FIG. 4 is a plan view showing a pattern of a conventional black matrix.

FIG. 5 is a plan view showing light leakage near a black matrix in a conventional liquid crystal display device.

FIG. 6 is a cross-sectional view showing a process of coating an alignment film in a conventional liquid crystal display device.

FIG. 7 is a cross-sectional view illustrating a rubbing step of an alignment film in a conventional liquid crystal display device.

FIG. 8 is a sectional view taken along the line II-II ′ of FIG. 3;

FIG. 9 is a cross-sectional view for explaining a manufacturing process of the first substrate of the liquid crystal display device according to the first embodiment of the present invention.

FIG. 10 shows a first example of the liquid crystal display device according to the first embodiment of the present invention.
Sectional drawing for demonstrating the manufacturing process of a board | substrate.

FIG. 11 illustrates a first example of the liquid crystal display device according to the first embodiment of the present invention.
Sectional drawing for demonstrating the manufacturing process of a board | substrate.

FIG. 12 shows a first example of the liquid crystal display device according to the first embodiment of the present invention.
Sectional drawing for demonstrating the manufacturing process of a board | substrate.

FIG. 13 illustrates a first example of the liquid crystal display device according to the first embodiment of the present invention.
Sectional drawing for demonstrating the manufacturing process of a board | substrate.

FIG. 14 illustrates a first example of the liquid crystal display device according to the first embodiment of the present invention.
Sectional drawing for demonstrating the manufacturing process of a board | substrate.

FIG. 15 shows a first example of the liquid crystal display device according to the first embodiment of the present invention.
Sectional drawing for demonstrating the manufacturing process of a board | substrate.

FIG. 16 illustrates a first example of the liquid crystal display device according to the first embodiment of the present invention.
Sectional drawing for demonstrating the manufacturing process of a board | substrate.

FIG. 17 illustrates a first example of the liquid crystal display device according to the first embodiment of the present invention.
Sectional drawing for demonstrating the manufacturing process of a board | substrate.

FIG. 18 illustrates a first example of the liquid crystal display device according to the first embodiment of the present invention.
Sectional drawing for demonstrating the manufacturing process of a board | substrate.

FIG. 19 is a plan view showing a liquid crystal display device of Embodiment 1 according to the present invention.

FIG. 20 is a plan view showing the liquid crystal display device according to the first embodiment of the present invention.

FIG. 21 is a sectional view taken along the line IV-IV ′ of FIG. 19;

FIG. 22 is a sectional view showing a liquid crystal display device according to a second embodiment of the present invention.

[Explanation of symbols]

 2 Second substrate 3, 103 First substrate 4, 104 Pixel electrode 8, 108 Thin film transistor 10, 110 Black matrix 11, 111 Alignment film 15, 115 Data bus wiring 15a, 115a Source electrode 15b, 115b Drain electrode 17, 117 Gate bus Wiring 17a, 117b Gate electrode 15, 115 Data bus wiring 15a, 115a Source electrode 15b, 115b Drain electrode 22, 122 Semiconductor layer 23, 123 Gate insulating layer 25, 125 Impurity semiconductor layer 26, 126 Inorganic protective film 37 Color filter layer 40 Liquid crystal material 156 Polarizing plate

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Kim, Jeon Hyun 533, Hugye-dong, Dong'an-gu, Anyang-si, Gyeonggi-do, Republic of Korea Inside LCD Research Lab. 533 Lou-dong, Donggye-gu, Dongyang-gu, Gyeonggi-do, Korea

Claims (31)

[Claims] A substrate having a gate electrode, a source electrode, and a drain electrode on the substrate; a protective layer on the transistor; a light blocking layer on a portion of the protective layer on the transistor; A flattening layer formed on the light blocking layer and the protective layer and having a contact hole on the source electrode or the drain electrode; and the source electrode formed on the flattening layer and through the contact hole, or A liquid crystal display device comprising: a pixel electrode that is in contact with the drain electrode; and an alignment layer on the pixel electrode. 2. A gate bus line and a data bus line are additionally provided on the substrate, wherein the gate bus line is connected to the gate electrode of the transistor, and the data bus line is the source electrode or the drain electrode. 2. The liquid crystal display device according to claim 1, wherein the light blocking layer covers the gate bus line and the data bus line. 3. The liquid crystal display device according to claim 2, wherein a part of the pixel electrode is selectively overlapped with the data bus line and the gate bus line. 4. The liquid crystal display device according to claim 1, wherein the flattening film is made of an organic insulating material. 5. The liquid crystal display according to claim 4, wherein the organic insulating material includes benzocyclobutene. 6. The liquid crystal display device according to claim 1, wherein the flattening film includes a substance spin-coated on a glass substrate. 7. The liquid crystal display device according to claim 1, wherein the protective layer includes an inorganic insulating layer. 8. The liquid crystal display device according to claim 7, wherein the inorganic insulating layer is made of SiNx or SiO ₂ . 9. The liquid crystal display device according to claim 7, wherein the flattening film includes a substance spin-coated on a glass substrate. 10. The liquid crystal display of claim 7, wherein the flattening film includes an organic insulating material. 11. The liquid crystal display of claim 10, wherein the organic insulating material includes benzocyclobutene. 12. Forming a transistor having a gate electrode, a drain electrode and a source electrode on a substrate; forming a light blocking layer on the transistor; and forming a light blocking layer on the entire surface of the substrate including the light blocking layer. Forming a flattening layer on the substrate, and forming an alignment layer on the flattening layer. 13. The method according to claim 12, wherein a protective layer is formed on the transistor before the step of forming the light blocking layer. 14. The method according to claim 13, wherein the protective layer is made of SiNx or SiO ₂ . 15. The method according to claim 12, wherein the flattening layer includes an organic insulating material. 16. The method according to claim 15, wherein the organic insulating material includes benzocyclobutene. 17. The method according to claim 12, wherein the flattening layer includes a substance spin-coated on a glass substrate. 18. A step of forming a gate bus line connected to the gate electrode of the transistor on the substrate, and forming a data bus line connected to the source electrode and the drain electrode on the substrate. The method of claim 1, wherein the light blocking layer is formed to cover the gate bus line and the data bus line.
3. The method for manufacturing a liquid crystal display device according to item 2. 19. The liquid crystal according to claim 18, wherein a pixel electrode connected to the source electrode or the drain electrode is formed on the planarization layer before forming the alignment layer. A method for manufacturing a display device. 20. The method according to claim 19, wherein a part of the pixel electrode is formed so as to be selectively overlapped with the data bus line and the gate bus line. 21. A substrate; a transistor having a gate electrode, a source electrode, and a drain electrode on the substrate; a pixel electrode in contact with the source electrode or the drain electrode; and a protective layer on the transistor and the pixel electrode. A light blocking layer on a portion of the protection layer on the transistor; a planarization layer on the light blocking layer and the protection layer; and an alignment layer on the planarization layer. Liquid crystal display device. 22. A gate bus line and a data bus line are additionally provided on the substrate, wherein the gate bus line is connected to the gate electrode of the transistor, and wherein the data bus line is the source electrode or the drain electrode. 22. The liquid crystal display of claim 21, wherein the light blocking layer covers the gate bus line and the data bus line. 23. The liquid crystal display device according to claim 22, wherein a part of the pixel electrode is selectively overlapped with the data bus line and the gate bus line. 24. The liquid crystal display according to claim 21, wherein the flattening film is made of an organic insulating material. 25. The liquid crystal display of claim 24, wherein the organic insulating material includes benzocyclobutene. 26. The liquid crystal display device according to claim 21, wherein the flattening layer includes a substance spin-coated on a glass substrate. 27. The liquid crystal display device according to claim 21, wherein the protective layer includes an inorganic insulating layer. 28. The liquid crystal display device according to claim 27, wherein the inorganic insulating layer is made of SiNx or SiO ₂ . 29. The liquid crystal display device according to claim 27, wherein the flattening layer includes a substance spin-coated on a glass substrate. 30. The liquid crystal display of claim 27, wherein the flattening layer includes an organic insulating material. 31. The liquid crystal display of claim 30, wherein the organic insulating material includes benzocyclobutene.