JP2004233683A - Manufacturing method of liquid crystal display - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of a liquid crystal display capable of forming a thin film of a transparent electrode while preventing the occurrence of a crack at the peripheral part of a contact hole. <P>SOLUTION: The manufacturing method of the liquid crystal display includes a step for forming the contact hole 5 facing a lower electrode 3 for connecting with a TFT (thin film transistor) 2 on a substrate 1 in an interlayer insulating layer 4, a step for film-depositing a transparent electrode 6 of the first layer on the contact hole, a step for removing the transparent electrode 6 of the first layer except the transparent electrode 6 at the inner part and the peripheral part of the contact hole 5 and a step for film-depositing thereon a transparent electrode 7 of the second layer having the material identical with that of the first transparent electrode 6. The occurrence of a crack at the peripheral part of the contact hole 5 is prevented, since the thickness obtained by adding the thickness of the transparent electrode 6 of the first layer to the thickness of the transparent electrode 7 of the second layer can be secured at the peripheral part of the contact hole 5 in the interlayer insulating film 4. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for manufacturing a liquid crystal display device using a switching element such as a TFT (Thin Film Transistor).
[0002]
[Prior art]
11 is a plan view showing two pixels (pixels) of the liquid crystal display device, and FIG. 12A is a cross-sectional view of a conventional liquid crystal display device corresponding to a cross section taken along line AA of FIG.
[0003]
2. Description of the Related Art Conventionally, in a liquid crystal display device using a switching element such as a TFT, as shown in FIG. A contact hole 5 is formed in the interlayer insulating film 4 of the wiring portion 22 in order to connect the transparent electrode 30 such as an object) to the TFT 2 formed on the substrate 1, and the TFT 2 is connected to the TFT 2 via the contact hole 5. The connection with the lower electrode 3 is performed (for example, see Patent Document 1).
[0004]
[Patent Document 1]
JP-A-2000-284326 (Paragraph Nos. 0061 and 0069; FIGS. 1 and 4)
[0005]
[Problems to be solved by the invention]
By the way, as a means for improving the transmittance and the orientation of such a liquid crystal display device, it is effective to make the transparent electrode 30 thinner. However, the interlayer insulating film 4 is generally planarized by a CMP (Chemical Mechanical Polishing) apparatus or the like for the purpose of improving processing accuracy and the like. Therefore, when trying to make the transparent electrode 30 thinner, there is a problem that the crack 31 enters the transparent electrode 30 at the corner of the periphery of the contact hole 5 of the interlayer insulating film 4 as shown in FIG. Occurs.
[0006]
Accordingly, an object of the present invention is to provide a method of manufacturing a liquid crystal display device capable of reducing the thickness of a transparent electrode while preventing the occurrence of cracks at the periphery of a contact hole.
[0007]
[Means for Solving the Problems]
In the method for manufacturing a liquid crystal display device according to the present invention, a step of forming a contact hole facing a lower electrode for connecting to a switching element on a substrate in an interlayer insulating film, and a step of forming a first transparent electrode thereon And a step of removing the first transparent electrode in the contact hole and other than the peripheral portion of the contact hole, and a step of forming a second transparent electrode on the first transparent electrode using the same material as the first transparent electrode.
[0008]
According to the manufacturing method of the present invention, the first transparent electrode is formed on the peripheral portion of the contact hole of the interlayer insulating film, and then the second transparent electrode is formed of the same material as the first transparent electrode. Even if the second transparent electrode is formed to be thin to a desired thickness, the peripheral portion of the contact hole of the interlayer insulating film has a thickness obtained by adding the thickness of the first transparent electrode to the thickness of the second transparent electrode. Therefore, the occurrence of cracks in the peripheral portion of the contact hole is prevented.
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
1 to 7 are views corresponding to the AA cross section of FIG. 11 showing the manufacturing process of the liquid crystal display device according to the embodiment of the present invention. Hereinafter, a method for manufacturing the liquid crystal display device according to the present embodiment will be described with reference to FIGS. 11 and 12 are denoted by the same reference numerals, and description thereof will be omitted.
[0010]
(First step)
As shown in FIG. 1, a state in which a contact hole 5 facing the lower electrode 3 is formed in an interlayer insulating film 4 planarized by using a CMP apparatus or the like, as shown in FIG. The first-layer transparent electrode 6 is formed to have a thickness of about 50 to 200 nm in order to prevent cracks at the periphery of the contact hole 5.
[0011]
(2nd process)
After the annealing process, in order to make contact with a second-layer transparent electrode 7 described later, as shown in FIG. 3, the first-layer transparent electrode 6 has a contact hole 5a (inside the contact hole 5 and the periphery of the contact hole 5). Only in (1), resist patterning is performed in a photoresist process to form a resist mask 11.
[0012]
(3rd step)
As shown in FIG. 4, the first-layer transparent electrode 6 other than the contact hole 5a is removed in the etching step.
[0013]
(4th process)
As shown in FIG. 5, a second-layer transparent electrode 7 having a thickness of about 10 to 30 nm is thinly formed on this using the same material as the first-layer transparent electrode 6.
[0014]
(Fifth step)
After the annealing, as shown in FIG. 6, in a photoresist process, resist patterning is performed to leave the transparent electrodes 6 and 7 only on the display unit 21, and a resist mask 12 is formed.
[0015]
(Sixth step)
As shown in FIG. 7, the transparent electrode 7 other than the display unit 21 is removed in the etching step.
[0016]
As described above, in the manufacturing method of the liquid crystal display device according to the present embodiment, in the first step, the first-layer transparent electrode 6 is formed to have a thickness of about 50 to 200 nm in order to prevent cracks at the peripheral portion of the contact hole 5. To form a thick film. Therefore, in the fourth step, the second-layer transparent electrode 7 can be formed as a thin film having a thickness of about 10 nm to 30 nm, ignoring the risk of cracks at the periphery of the contact hole 5.
[0017]
As described above, in the liquid crystal display device in which the transparent electrode 7 of the display unit 21 is thinned, the transmittance of the display unit 21 is improved. FIG. 8 shows the relationship between the film thicknesses A, B, C, and D (A <B <C <D) of the transparent electrode 7 of the display unit 21 and the transmittance. The horizontal axis in FIG. 8 is the wavelength (nm) of light, and the vertical axis is the transmittance (%). As shown in FIG. 8, the thinner the film thickness, the higher the transmittance over the entire visible light range.
[0018]
Further, when the transparent electrode 7 of the display unit 21 is thinned, as shown in the cross-sectional view of FIG. 9 corresponding to the BB cross section of FIG. 11, the processing when the transparent electrode 7 is separated between adjacent pixels. The accuracy is improved. That is, the gap between the transparent electrodes 7 of the adjacent pixels is formed by wet etching. However, since the transparent electrode 7 is thinned, the amount of side etching is reduced. Can be formed.
[0019]
FIG. 10 shows the relationship between the thickness (nm) of the transparent electrode 7 and the amount of side etching (μm). In this figure, a plurality of samples are measured for each of the four types of film thicknesses A, B, C, and D, and the respective side etch amounts are measured and plotted. Note that the curve shown in the figure is obtained by approximating the result of this plot with a polynomial.
[0020]
That is, a metal film 8 as a signal line is formed on the substrate 1 between adjacent pixels, a flat layer 9 is formed thereon, and the transparent electrode 7 of each adjacent pixel overlaps the metal film 8. To form the respective domain regions 7a. Since the width of the domain regions 7a can be processed with high precision, the contrast of each pixel can be improved.
[0021]
In addition, since the transparent electrode 7 of the display unit 21 is thinned, the step on the surface of the interlayer insulating film 4 is reduced, and the orientation is improved.
[0022]
The thickness of the first transparent electrode 6 is not limited to about 50 to 200 nm, but is preferably in this range. If the first-layer transparent electrode 6 is formed to have a thickness in this range, even if the second-layer transparent electrode 7 is formed as thin as possible, it is possible to reliably prevent the occurrence of cracks in the peripheral portion of the contact hole 5. Becomes possible. When the thickness of the first-layer transparent electrode 6 is less than 50 nm, the thickness may be such that cracks can be prevented in a state where the thickness of the second-layer transparent electrode 7 is added. If the thickness of the first transparent electrode 6 is more than 200 nm, it is not preferable because the thickness is more than necessary for preventing cracks.
[0023]
【The invention's effect】
According to the present invention, a contact hole facing a lower electrode for connecting to a switching element on a substrate is formed in an interlayer insulating film, a first transparent electrode is formed thereon, and a portion other than the inside of the contact hole and the periphery of the contact hole is formed. The first transparent electrode is removed, and a second transparent electrode is formed on the second transparent electrode using the same material as the first transparent electrode. Can be realized. Thereby, the transmittance, processing accuracy, and orientation of the liquid crystal display device can be improved.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view illustrating a manufacturing process of a liquid crystal display device according to an embodiment of the present invention and corresponding to a cross section taken along line AA of FIG.
FIG. 2 is a cross-sectional view illustrating a manufacturing process of the liquid crystal display device according to the embodiment of the present invention, corresponding to a cross section taken along the line AA of FIG.
FIG. 3 is a cross-sectional view illustrating a manufacturing process of the liquid crystal display device according to the embodiment of the present invention, corresponding to a cross section taken along line AA of FIG. 11;
FIG. 4 is a cross-sectional view showing a manufacturing step of the liquid crystal display device according to the embodiment of the present invention and corresponding to a cross section AA of FIG. 11;
FIG. 5 is a cross-sectional view illustrating a manufacturing step of the liquid crystal display device according to the embodiment of the present invention and corresponding to a cross section AA of FIG. 11;
FIG. 6 is a cross-sectional view showing a manufacturing step of the liquid crystal display device according to the embodiment of the present invention and corresponding to a cross section AA of FIG. 11;
FIG. 7 is a cross-sectional view showing a manufacturing step of the liquid crystal display device according to the embodiment of the present invention and corresponding to a cross section taken along line AA of FIG. 11;
FIG. 8 is a diagram showing a relationship between a film thickness of a transparent electrode of a display unit and transmittance.
FIG. 9 is a cross-sectional view corresponding to the BB cross section in FIG. 11;
FIG. 10 is a diagram showing the relationship between the thickness of a transparent electrode 7 and the amount of side etching.
FIG. 11 is a plan view showing two pixels of the liquid crystal display device.
12A is a cross-sectional view of a conventional liquid crystal display device corresponding to a cross section taken along line AA of FIG. 11, and FIG. 12B is a cross-sectional view showing how cracks occur when FIG. 11A is made thinner. .
[Explanation of symbols]
1 Substrate 2 TFT
Reference Signs List 3 Lower electrode 4 Interlayer insulating film 5 Contact hole 6, 7 Transparent electrode 8 Metal film 9 Flat layer 11, 12 Resist mask 21 Display unit 22 Wiring unit

Claims (2)

Forming a contact hole facing the lower electrode for connecting to the switching element on the substrate in the interlayer insulating film;
Forming a first transparent electrode thereon,
Removing the first transparent electrode in the contact hole and other than the contact hole peripheral portion;
Forming a second transparent electrode on the first transparent electrode using the same material as the first transparent electrode. The method according to claim 1, wherein the first transparent electrode has a thickness of 50 to 200 nm.

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