JPH10253991A - Liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the uniformity in thickness of a TFT substrate and to prevent occurrence of a gap unevenness fault by removing at least one between a gate insulation film and an upper part insulation film in a part where the thickness of the TFT substrate is necessary to be more uniform. SOLUTION: Terminals 2 and a first metallic film 5 are formed on a first transparent substrate 4. Further, the gate insulation film 6 is formed excepting the part that a transfer pad 7 is to be formed and its periphery. Then, the transfer pad 7 is formed on the first metallic film 5, and further, a second metallic film 8 is formed on at least a part on the first metallic film 5 and transfer pad 7 for reducing resistance. Finally, an upper part insulation film 9 covering the TFT substrate surface is formed. In such a manner, by partially removing the gate insulation film 6, the thickness of the part being in contact with the seal material 1 of the TFT substrate is uniformized, and as a result, the matter that the gap unevenness fault occurs is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an active liquid crystal display device in which a plurality of thin film transistors (hereinafter, referred to as "TFTs") are arranged together with pixel electrodes.

[0002]

2. Description of the Related Art A conventional liquid crystal display device will be described.
Generally, a liquid crystal display device includes a thin film transistor substrate (hereinafter, referred to as a “TFT substrate”), a color filter substrate, and a liquid crystal material sealed between the TFT substrate and the color filter substrate. The TFT substrate includes a plurality of gate electrode lines parallel to each other, a gate insulating film covering the plurality of gate electrode lines, and a plurality of source electrode lines orthogonal to the plurality of gate electrode lines, on a first transparent substrate surface. When,
A plurality of TFTs formed at respective intersections of the plurality of gate electrode lines and the plurality of source electrode lines;
A plurality of pixel electrodes made of a transparent conductive film connected to each drain electrode of T are formed. In the color filter substrate, after a color filter composed of three primary colors corresponding to the plurality of pixel electrodes is formed on the surface of the second transparent substrate, a transparent electrode is formed on the surface of the second transparent substrate. It becomes. The liquid crystal material is sealed between the TFT substrate and the color filter substrate after the TFT substrate and the color filter substrate are adhered to each other with a sealant at a predetermined interval. The sealing material is provided around the display area of the TFT substrate, that is, near the end of the TFT substrate.

The TFT includes a gate electrode connected to one of the plurality of gate electrode lines,
A gate insulating film covering the gate electrode; a semiconductor layer formed over the gate electrode with the gate insulating film interposed therebetween; and a source electrode and a drain electrode formed in a region including part of the semiconductor layer. . The source electrode is connected to one of the plurality of source electrode lines, and the drain electrode is connected to one of the plurality of pixel electrodes.

FIG. 4 is a partial explanatory view showing an example of a TFT substrate of a conventional liquid crystal display device. FIG. 4 shows a part of a portion of the TFT substrate that is in contact with the sealant together with the sealant. FIG. 5 is an explanatory cross-sectional view showing a cross section taken along line BB shown in FIG. 4 and 5, 1
Is a sealing material, 2 is a metal used for forming a gate electrode line, a terminal connected to the gate electrode line or the source electrode line, 4 is a first transparent substrate having an insulating property,
5 is a first metal film formed at the same time as forming a gate electrode line, 6 is a gate insulating film, 7 is a transfer pad formed at the same time as forming a pixel electrode, 8
Denotes a second metal film formed simultaneously when the source electrode line and the drain electrode are formed, and 9 denotes an upper insulating film covering the surface of the TFT substrate. In FIG. 4, the first transparent substrate 4, the gate insulating film 6, and the upper insulating film 9 are not shown. The terminal 2 is covered with the gate insulating film 6 so as to avoid a portion to be exposed to input a control signal from a driving unit provided outside the liquid crystal display device to the gate electrode line or the source electrode line. FIG. 4 shows a portion covered with the gate insulating film 6. The upper insulating film 9 is not formed on a part of the surface of the transfer pad 7, but is formed by bonding a TFT substrate and a color filter substrate and then injecting a conductive resin into an exposed portion of the transfer pad 7. The transfer pad 7 is electrically connected to the transparent electrode of the color filter substrate. FIG.
, The display area is above the sealing material 1.

The transfer pad 7 is provided on the upper insulating film 9 in order to apply a constant potential to a transparent electrode formed on the surface of the color filter substrate. Even if the lead-in wiring is formed in either the first metal film 5 or the second metal film 8, the role of the lead-in wiring can be fulfilled, but in order to realize a lower resistance, the lead-in wiring is formed by the first lead. A laminated structure is obtained by laminating a metal film and a second metal film in multiple layers. In addition, the first metal film 5 and the transfer pad 7 are electrically connected by the contact hole formed in the gate insulating film 6. A control signal from a drive unit provided outside the liquid crystal display device is input to the transfer pad 7 via a lead-in line.

The laminated structure is indispensable for realizing low resistance, but on the other hand, the thickness of the TFT substrate is partially increased. Therefore, as shown in FIG.
The thickness of the TFT substrate is different between the portion where the transfer pad 7 is formed and the portion where the terminal 2 is formed, and a difference indicated by reference numeral “d2” occurs. As a result, the distance between the TFT substrate and the color filter substrate changes depending on the location, causing a gap unevenness defect in the liquid crystal display device, which has a problem of adversely affecting the display characteristics of the liquid crystal display device. Means for solving such a problem include (1) increasing the thickness of the film or layer formed in the thin portion of the TFT substrate so that the TF
To improve the uniformity of the thickness of the entire T substrate, (2) to reduce the resistance of the metallic film serving as the transfer pad and to eliminate the need for a laminated structure, or (3) to form a laminated structure. A similar laminated structure is formed around the
There are three points to improve the uniformity of the thickness of the entire FT substrate. However, regarding (1), the processing capacity of the device used in the manufacturing process is reduced. Also,
(2) is not easy because it is necessary to realize a low resistance by developing a new material or a new manufacturing technique. Further, in the case of (3), by forming a structure unnecessary for driving the liquid crystal display device, the possibility of forming a short-circuit pattern which causes a decrease in yield when manufacturing the liquid crystal display device is increased. This is undesirable.

[0007]

As described above, in the conventional liquid crystal display device, gap uniformity occurs in the liquid crystal display device due to the low uniformity of the thickness of the TFT substrate, and the display characteristics of the liquid crystal display device are reduced. There is a problem of lowering.

The present invention solves the above-mentioned problem, so that the liquid crystal display device does not suffer from gap unevenness, and furthermore, means which does not impose a load on the processing capability and yield of the device used in the manufacturing process. The purpose is to improve the uniformity of the thickness of the TFT substrate.

[0009]

According to the present invention, there is provided a liquid crystal display device comprising: a plurality of gate electrode lines parallel to each other; a gate insulating film covering the plurality of gate electrode lines; A plurality of source electrode lines orthogonal to the gate electrode lines, a plurality of thin film transistors formed at each intersection of the plurality of gate electrode lines and the plurality of source electrode lines, and a connection to each drain electrode of the plurality of thin film transistors. A plurality of pixel electrodes made of a transparent conductive film are formed, and the surface is covered with an upper insulating film. A thin film transistor substrate is formed on the surface of the second transparent substrate, and three primary colors corresponding to the plurality of pixel electrodes are formed. After a color filter is formed, a color filter substrate having a transparent electrode formed on the surface of the second transparent substrate, and the thin film transistor substrate and the color filter substrate A liquid crystal display device comprising a liquid crystal material sealed between the thin film transistor substrate and the color filter substrate after a filter substrate is bonded with a sealing material at a predetermined interval, wherein the thin film transistor substrate is Wherein at least one of the gate insulating film and the upper insulating film is removed at locations where the thickness of the gate insulating film needs to be more uniform.

[0010] Further, a portion where the thickness of the thin film transistor substrate is required to be more uniform is a portion where the thin film transistor substrate and the sealing material are in contact with each other.

The difference between the thickness of the thickest portion and the thickness of the thinnest portion among the portions in contact with the sealing material of the thin film transistor substrate is at most 2000 °.

Further, the upper insulating film of the gate insulating film and the upper insulating film is removed.

Further, a portion where the thickness of the thin film transistor substrate is required to be more uniform is a portion where the thin film transistor substrate and the sealing material are in contact with each other.
The difference between the thickness of the thickest part and the thickness of the thinnest part is at most 1000 °.

Further, the sealing material is made of an epoxy resin.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, a liquid crystal display of the present invention will be described with reference to the drawings.

Embodiment 1 FIG. 1 is a partial explanatory view showing one embodiment of the TFT substrate of the liquid crystal display device of the present invention. FIG. 1 shows a part of a portion of the TFT substrate which is in contact with the sealant together with the sealant. FIG. 2 is an explanatory cross-sectional view showing a cross section taken along line AA shown in FIG. 1 and 2, the same or corresponding parts as those in FIGS. 4 and 5 are denoted by the same reference numerals. 1 and 2
Are formed according to a process for forming a display region of a TFT substrate. First, the terminal 2 and the first metal film 5 are formed on the first transparent substrate 4.
Further, the gate insulating film 6 is formed except for a portion where the transfer pad 7 is to be formed and the periphery thereof (or the entirety of the first transparent substrate 4 on which the terminal 2 and the first metal film 5 are formed). After the gate insulating film 6 is formed on the surface, the portion where the transfer pad 7 is to be formed and the peripheral gate insulating film 6 are removed.
Next, a transfer pad 7 is formed on the first metal film 5, and a second metal film 8 is formed on at least a part of the first metal 5 and the transfer pad 7 for lowering resistance. . Finally, an upper insulating film 9 covering the surface of the TFT substrate is formed. After the TFT substrate and the color filter substrate are bonded together, an upper insulating film 9 is formed on a part of the surface of the transfer pad 7 so that the transfer pad 7 and the transparent electrode of the color filter substrate can be electrically connected. Is not formed.

Next, effects obtained by the liquid crystal display device of the present embodiment will be described. For example, the thickness of the terminal 2 and the first metal film 5 is 4000
Assuming that the thickness of the TFT is 4000 °, the thickness of the transfer pad 7 is 1000 °, the thickness of the second metal film 8 is 5000 °, and the thickness of the upper insulating film 9 is 5000 °, the TFT
The difference between the thickness of the portion where the transfer pad 7 is formed on the substrate and the thickness of the portion where the terminal 2 is formed is d2 = (4000 + 4000 + 1000 + 5000 + 5) in the case of the conventional liquid crystal display device shown in FIG.
000)-(4000 + 4000 + 5000) = 600
In contrast, in the case of the liquid crystal display device of the present embodiment shown in FIG. 2, d1 = (4000 + 1000 + 5000 + 5000) −
(4000 + 4000 + 5000) = 2000 °, and the difference d1 is １ ／ of the difference d2. Therefore, the thickness of the portion of the TFT substrate in contact with the sealing material is made more uniform.

In this embodiment, the thickness of the portion of the TFT substrate in contact with the sealing material is made uniform by partially removing the gate insulating film. The same effect can be obtained even when the film is partially removed. In such a case, the TF
The difference between the thickness of the thickest part and the thickness of the thinnest part among the parts in contact with the sealing material of the T substrate is at most 1000.
Å.

Embodiment 2 FIG. 3 is an explanatory sectional view showing another embodiment of the TFT substrate of the liquid crystal display device of the present invention. 3, the same or corresponding parts as those in FIG. 2 are denoted by the same reference numerals. The difference between the first embodiment and the present embodiment is that in the first embodiment, the lead-in wiring is formed using the first metal film and the second metal film, and the thickness of the lead-in wiring is made uniform. In the present embodiment, the thickness of the first metal film (that is, the terminal) is smaller than the thickness of the second metal film. The point is that it is formed using only a metal film.

For example, the thickness of the terminal 2 is 2000 mm, the thickness of the gate insulating film 6 is 4000 mm, the thickness of the transfer pad 7 is 1000 mm, and the thickness of the second metal film 8 is 50 mm.
Assuming that the thickness of the upper insulating film 9 is 5000 °, the difference between the thickness of the portion of the TFT substrate where the transfer pad 7 is formed and the thickness of the portion where the terminal 2 is formed is:
In the case of the conventional liquid crystal display device shown in FIG. 5, d2 = (4000 + 1000 + 5000 + 5000)-
(2000 + 4000 + 5000) = 4000 °, whereas in the case of the liquid crystal display device of the present embodiment shown in FIG. 3, (the thickness of the portion where the transfer pad 7 is formed) −
(Thickness of portion where terminal 2 is formed) = (1000 + 50)
00 + 5000)-(2000 + 4000 + 5000)
= 0, and the thickness of the portion of the TFT substrate in contact with the sealing material is made uniform.

In the first and second embodiments, the position where the sealing material of the TFT substrate contacts is described. However, if there is no electrical problem, the thickness of the TFT substrate in the TFT substrate is reduced. It is possible to apply the invention elsewhere where more uniformity is required.

[0022]

According to the present invention, according to the present invention, the T
It is possible to easily improve the uniformity of the thickness of the TFT substrate in a place where the thickness of the FT substrate needs to be more uniform. Therefore, it is possible to prevent gap unevenness from occurring in the liquid crystal display device.

[Brief description of the drawings]

FIG. 1 is a partial explanatory view showing one embodiment of a TFT substrate of a liquid crystal display device of the present invention.

FIG. 2 is an explanatory sectional view showing a section taken along line AA shown in FIG. 1;

FIG. 3 is an explanatory sectional view showing another embodiment of the TFT substrate of the liquid crystal display device of the present invention.

FIG. 4 is a partial explanatory view showing an example of a TFT substrate of a conventional liquid crystal display device.

FIG. 5 is an explanatory sectional view showing a section taken along line BB shown in FIG. 4;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Seal material 2 Terminal 4 1st transparent substrate 5 1st metal film 6 Gate insulating film 7 Transfer pad 8 2nd metal film 9 Upper insulating film

Claims (6)

[Claims] 1. A plurality of gate electrode lines parallel to each other, a gate insulating film covering the plurality of gate electrode lines, and a plurality of source electrode lines orthogonal to the plurality of gate electrode lines on a surface of a first transparent substrate. And a plurality of thin film transistors formed at each intersection of the plurality of gate electrode lines and the plurality of source electrode lines, and a plurality of pixel electrodes made of a transparent conductive film connected to each drain electrode of the plurality of thin film transistors. A color filter composed of three primary colors corresponding to the plurality of pixel electrodes is formed on a thin film transistor substrate formed and covered with an upper insulating film, and a second transparent substrate. A color filter substrate in which a transparent electrode is formed on the surface of a transparent substrate, and the thin film transistor substrate and the color filter substrate are sealed at a predetermined interval. A liquid crystal display device comprising a liquid crystal material sealed between the thin film transistor substrate and the color filter substrate after being bonded by a material, wherein the thickness of the thin film transistor substrate among the thin film transistor substrates is more uniform. A liquid crystal display device, wherein at least one of the gate insulating film and the upper insulating film is removed where necessary. 2. The liquid crystal display device according to claim 1, wherein the portion where the thickness of the thin film transistor substrate is required to be more uniform is a portion where the thin film transistor substrate and the sealing material are in contact with each other. 3. The liquid crystal display device according to claim 2, wherein a difference between a thickness of the thickest portion and a thickness of the thinnest portion among the portions in contact with the sealing material of the thin film transistor substrate is at most 2000 °. 4. The liquid crystal display device according to claim 1, wherein an upper insulating film of said gate insulating film and said upper insulating film is removed. 5. A portion where the thickness of the thin film transistor substrate is required to be more uniform is a portion where the thin film transistor substrate and the sealing material are in contact, and among the portions where the thin film transistor substrate is in contact with the sealing material, 5. The liquid crystal display device according to claim 4, wherein the difference between the thickness of the thickest portion and the thickness of the thinnest portion is at most 1000 [deg.]. 6. The liquid crystal display device according to claim 1, wherein the sealing material is made of an epoxy resin.