JPH10123563A - Liquid crystal display device and its fault correction method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make possible respectively correcting plural pixel faults on signal wiring by forming auxiliary capacity lines to a grid shape intersecting in respective pixels. SOLUTION: The auxiliary capacity lines 2 are formed on a glass substrate 1 in the grid shape, and a first insulation film layer 3 is formed on them so as to cover the whole glass substrate 1 surface, and further, gate signal wiring 4 and gate electrodes 4a in the shape branching from the gate signal wiring 4 in a branch shape are provided. A second insulation film layer 5 is provided on the gate signal wiring 4, and source signal wiring 6 are arranged in the shape orthogonally intersecting with the gate signal wiring 4 through the insulation film layer 5, and source electrodes 6a are branched from the source signal wiring 6 in the branch shape, and TFTs 9 are provided in the vicinity of crossing parts between the gate signal wiring 4 and the source signal wiring 6.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transmission type or reflection type active matrix type liquid crystal display device and a method for repairing defects thereof.

[0002]

2. Description of the Related Art A liquid crystal display device sandwiches liquid crystal molecules between two opposing transparent electrodes, applies an electric signal to the liquid crystal molecules between the electrodes, and controls the polarization component of incident light from the outside. The transmission amount is controlled to display information. A liquid crystal display device that transmits light in a normal state, that is, when no voltage is applied, and blocks light when a voltage is applied, is called a normally white liquid crystal display device.
Liquid crystal display devices have the advantages of very low power consumption, thinness and light weight compared to CRTs. With these advantages being accepted in many areas,
Its production is increasing year by year.

On the other hand, with the recent increase in the number of multimedia computers, the amount of information to be represented by a display device has increased dramatically, and a higher resolution liquid crystal display device has been required. As a result, in a liquid crystal display device having a certain size, the number of picture elements constituting the liquid crystal display device increases while the size of the liquid crystal display device keeps decreasing.

[0004] However, by simultaneously increasing the number of picture elements and reducing the size of the picture elements, the defect occurrence rate in the manufacturing process of the liquid crystal display device is dramatically increased.

For example, a TFT (Thin Film Transistor), which is a switching element for driving a picture element, has an abnormal operation due to a defect in forming a thin film, and a gate wiring and a source wiring for supplying a signal to each picture element. The frequency of occurrence of defects such as disconnection and short circuit increases, and these are direct causes of lowering the yield.

Therefore, a method for correcting a defect generated during the manufacture of a liquid crystal display device by some method is usually prepared. Generally, a wiring dedicated to defect correction is provided in advance in a liquid crystal display device.

FIGS. 9 (a), 9 (b) and 10 are views for explaining a conventional liquid crystal display device and a method of correcting a defect thereof. FIG. 9 is a diagram showing a configuration of a display area of a conventional liquid crystal display device, and FIG. 9B is a cross-sectional view taken along a line BB of FIG. 9A. FIG. 10 simply shows the relationship between each layer in the entire structure of a conventional liquid crystal display device having a spare wiring for correction.

In FIG. 9 and FIG.
01 on the source signal wiring 106 and the gate signal wiring 1
04 are formed so as to be orthogonal to each other with the insulating film layer 103 interposed therebetween, and a TFT 109 is formed near the intersection. The TFT 109 has at least the gate signal wiring 1
The gate electrode 104a is branched from the gate electrode 104, the source electrode 106a is branched from the source signal line 106, the semiconductor layer 107, and the drain electrode 108. The pixel electrode 110 is connected to the drain electrode 108.

On the same layer as the gate signal wiring 104, an auxiliary capacitance line 102 for forming an auxiliary capacitance contributing to holding of liquid crystal is provided. Further, on the same layer as the gate signal wiring 104 and the auxiliary capacitance line 102 and outside the display region, a spare auxiliary wiring 200 for correcting a defect is provided.

In this liquid crystal panel, when a disconnection portion 220 is found in the source signal wiring 106 in the panel, as shown in FIG. And the auxiliary wiring 200 for correction is connected outside the panel substrate using tabs.

[0011]

According to the above-mentioned conventional method, the liquid crystal panel is provided with a spare wiring for repair, which is a dedicated wiring for repair. However, the number of spare spare wires for repair is limited. For this reason, many defects cannot be corrected, and when two or more disconnections are simultaneously present in the same signal wiring, it is impossible to correct all the defects.

[0012]

According to the liquid crystal display device of the present invention, a gate signal line and a source signal line are formed orthogonally on an insulating substrate, and an intersection of the gate signal line and the source signal line. A thin film transistor is formed in the vicinity,
In a liquid crystal display device in which picture element electrodes connected to the thin film transistors are arranged in a matrix and storage capacitance lines are provided, the storage capacitance lines are formed in a lattice shape, and intersections of the storage capacitance lines are provided. Is located in each picture element, thereby achieving the above object.

It is preferable that the auxiliary capacitance line also serves as a defect correction wiring.

The defect repair method for a liquid crystal display device according to the present invention comprises:
A gate signal wiring, a source signal wiring orthogonal to the gate signal wiring, a thin film transistor formed near an intersection of the gate signal wiring and the source signal wiring, and a matrix connected to the thin film transistor on the insulating substrate. In a method for correcting a defect of a liquid crystal display device comprising a picture element electrode arranged in a pixel and an auxiliary capacity line, the auxiliary capacity line is formed in a grid shape crossing in each picture element, and the gate signal When a defective portion exists in any of the wiring and the source signal wiring, the U-shaped wiring surrounding the defective portion is used as a bypass wiring among the auxiliary capacitance lines, so that the defective portion exists. It is characterized by propagating a normal signal to the signal wiring, thereby achieving the above object.

It is preferable that the U-shaped wiring overlaps a picture element electrode connected to the signal wiring having the defective portion.

The operation of the above configuration will be described below.

According to the first aspect of the present invention, the auxiliary capacitance line is
Since it is formed in a grid pattern in which wirings parallel to the gate signal wiring and source signal wiring cross each other, when this is used as a wiring for defect repair, there is a limit to the formation of extra wiring outside the panel. Can be greatly increased. At this time, since the intersection of the defect correction wiring can be provided for each picture element, it is possible to perform the defect correction for each picture element. For example, in the same signal wiring, two or more disconnections exist simultaneously. In this case, all the defects can be corrected. In addition, since the intersection is located at the center of the picture element, a parasitic capacitance is hardly generated between the signal wiring and each of the signal wirings, so that the electric characteristics of the picture element are not disturbed.

According to the second aspect of the present invention, the auxiliary capacitance line also serves as a defect repair wiring, so that even if the defect repair is not performed, the wiring formation is not wasted.

According to the third aspect of the present invention, a defect on the signal wiring is controlled by the auxiliary capacitance line formed in a grid shape by crossing the wiring parallel to the gate signal wiring and the source signal wiring for each picture element. Since the wiring surrounding the shape of a square is separated and used as a bypass wiring, the number of limited defect corrections can be greatly increased, and it becomes possible to perform defect correction on a picture element basis. Even when two or more disconnections are present simultaneously in the same signal wiring, all the defects can be corrected.

According to the fourth aspect of the present invention, the wiring surrounding the defect on the signal wiring in a U-shape is overlapped with the picture element electrode connected to the signal wiring having the defect. This allows
Originally, a connection path that does not easily overlap with a normally operating picture element electrode is selected, so that the electrical characteristics of a normal picture element electrode are not disturbed.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION

(Embodiment 1) A liquid crystal display device of Embodiment 1 and a method for correcting the same will be described below with reference to the drawings.

FIGS. 1A and 1B show the first embodiment.
1 shows a configuration of a liquid crystal display device. FIG. 1A is a top view of the liquid crystal display device according to the first embodiment, and FIG.
It is an AA sectional view of (a).

In FIGS. 1A and 1B, an auxiliary matrix line 2 is formed on an active matrix substrate on a glass substrate 1 in a lattice pattern. A first insulating film layer 3 is formed on the auxiliary capacitance line 2 so as to cover the entire surface of the glass substrate 1, and a gate signal line 4 and a branch from the gate signal line 4 are formed thereon. The gate electrode 4a is provided in such a shape. Further, the second insulating film layer 5 is provided on the gate signal wiring 4, and
Is perpendicular to the source signal wiring 6 via the insulating film layer 5.
Are provided, and a source electrode 6
a is branched in a branch shape, and a known TFT 9 including at least the gate electrode 4a and the source electrode 6a, the semiconductor layer 7, and the drain electrode 8 is provided near the intersection of the gate signal line 4 and the source signal line 6. Are provided, and the pixel electrode 10 connected to the drain electrode 8 is driven by the TFT 9. Further, an alignment film 11 is formed so as to cover the entire substrate. The active matrix substrate 50 and the counter substrate 51 having the alignment film 11 and the counter electrode 12 formed on the glass substrate 1 are attached to each other, and liquid crystal is sealed between the two substrates to form a liquid crystal display device.

Here, the auxiliary capacitance line 2 will be described below. The auxiliary capacitance lines 2 are provided in a grid pattern on the glass substrate 1, and more specifically, wiring lines parallel to the gate signal lines 4 and the source signal lines 5 intersect at the center of each picture element. It is provided so that it may become a suitable shape. In the first embodiment, the auxiliary capacitance line 2 is connected to the IT
Since it is formed of a transparent conductive film such as O, it is more advantageous in terms of aperture ratio than using an opaque metal material.

In the liquid crystal display device having the above-described structure, the auxiliary capacitance line 2 and the picture element electrodes 10 adjacent in the height direction via the first insulating film layer 3 and the second insulating film layer 5 are used. A storage capacitor is formed, and this storage capacitor contributes to holding the liquid crystal. Further, in order to obtain an auxiliary capacitance required for holding, the line width of the auxiliary capacitance line 2, the first insulating film layer 3 and the second
It is necessary to appropriately adjust various parameters such as the thickness of the material forming the insulating film layer 5 or the dielectric constant thereof.

FIG. 2 shows another embodiment. The top view of FIG. 2 is the same as FIG.
FIG. 2 is a sectional view taken along the line AA in FIG. The reference numerals in FIG. 2 are common to those in FIG. In another embodiment, as shown in FIG. 2, a configuration in which the layer of the auxiliary capacitance line 2 is formed between two signal wiring layers (the gate signal wiring 4 and the source signal wiring 6). However, in this case, if an attempt is made to use a manufacturing process similar to that of the above-described liquid crystal display device, T
In the FT 9, two insulating film layers including the first and second insulating film layers 3 and 5 are formed between the gate electrode 4 a and the source electrode 6 a and the drain electrode 8. In order to prevent an abnormal operation of the TFT 9 depending on the dielectric constant and the thickness of the insulating film layers 3 and 5,
In some cases, processing such as increasing the gate voltage or reducing the thickness of at least one of the insulating film layers (either 3 or 5) only in the portion overlapping the TFT 9 may be required.

Next, a method of correcting a defect of the liquid crystal display device shown in FIG. 1 will be described below with reference to the drawings.

FIGS. 3A and 3B show the first embodiment.
FIG. 4 is a diagram for describing a defect repair method of the liquid crystal display device of FIG. FIG. 3A shows a liquid crystal display device according to the first embodiment in which a disconnection defect has occurred, and FIG.
FIG. 3A is a diagram illustrating a defect repair method of the liquid crystal display device.
In FIG. 3A, in a gate signal line 4 running in the center of the drawing, a broken portion 2
0 exists. The reason for such a disconnection is that
For example, when the electrode layer is deposited or sputtered in the manufacturing process, the layer is not formed correctly due to contamination of dust, dust, or the like, or when exposure is performed using a mask in photolithography, dust, dust, etc. It is possible that the pattern was not properly patterned as a mask.

If any correction is not made to such a disconnection defect, the following phenomenon occurs, causing an observational defect. For example, when a power supply for supplying a signal to the gate signal wiring 4 is mounted on the left side in the drawing, a voltage is supplied to the TFT 9a on the same gate signal wiring 4 on the power supply side (left side in the drawing) from the disconnection portion 20. Therefore, this picture element is driven normally. On the other hand, the disconnection portion 20
TFT9 located on the opposite side of the power supply (right side on the paper)
Since no voltage is supplied to b, the picture element is not driven at all. In this case, in the normally white liquid crystal, the picture element connected to the TFT 9b is always in a lighting state (light transmitting state) and appears as a bright line on the screen.

In order to solve such a problem, in the present invention, the disconnection portion 20 is connected by using the auxiliary capacitance line 2 formed in a lattice shape as a bypass wiring.
Correction is made so that a voltage is normally supplied to the gate signal wiring 4. Specifically, a method described below is used.

To connect the above-described disconnection section 20, FIG.
As shown in (b), first, the minimum auxiliary capacitance line 2 necessary for connection (U-shaped wiring surrounding a defective portion)
Is separated from the surrounding auxiliary capacitance line 2 by laser irradiation. In the first embodiment, cutting is performed at six cutting portions 16 (indicated by crosses). Subsequently, the laser beam is irradiated to the intersection 17 between the separated auxiliary capacitance line 2 and the gate signal line 4 to connect them to complete the correction.

In order to connect the disconnection portion 20 with the auxiliary capacitance line 2, two types of connection paths are conceivable as shown in FIGS. 3B and 4, but a normally operating picture element electrode is used. Since running the wiring under 10a slightly changes the electrical characteristics of a normal picture element, it is preferable to select a connection path as shown in FIG. That is, the picture element electrode 10 connected to the defective signal wiring
It is better to take a connection path on the b side.

Here, the structure of a system for performing correction using laser light will be described with reference to FIG. Normally, a single mode YAG (Yttrium-Aluminum)
-Garnet) laser or excimer laser is used. FIG.
In, the shape and power of the laser light 61 output from the laser oscillator 60 are adjusted by passing the laser light 61 through the slit 62 and the ND filter 63, and the liquid crystal panel 64 is irradiated. In order to cut the wiring on the substrate, for example, a YAG laser may be irradiated at a laser power of 10 ⁻⁹ to 10 ⁻⁶ J / μm ² .

Further, in the liquid crystal display device of the present invention, a defect which cannot be corrected conventionally, for example, as shown in FIG.
In the case where two or more disconnections occur on the same signal wiring (on the source signal wiring 6 in FIG. 6),
Alternatively, even when the number of line defects is larger than the number of spare wirings for repair, the repair can be performed. As the correction method, only the above-described correction method is applied to each disconnection point. Also, as shown in FIG. 6, even if the disconnection occurs in the source signal wiring 6, the defect can be corrected by employing the same method as that in the case where the disconnection occurs in the gate signal wiring 4 as described above. . That is, the auxiliary capacitance line 2 is cut off only at a connection path necessary for connecting the disconnection portion 20 (cut at six cutting portions 16 for each disconnection portion 20), and the separated storage capacitance line 2 and the source signal wiring Laser irradiation is performed on the intersection 17 between the storage capacitor line 6 and the storage capacitor line 2 and the source signal wiring 6.

As described above, the transmission type liquid crystal display device has been described in the first embodiment. However, the present invention is not limited to this, and the same configuration and the same defect correction method can be applied to a reflection type liquid crystal display device.

(Embodiment 2) In Embodiment 2, a description will be given of a method of correcting a failure caused by a leak (short circuit) between wirings in the liquid crystal display device described in Embodiment 1 above.

FIGS. 7A and 7B show the second embodiment.
FIG. 3 is a diagram for explaining a defect repair method for a liquid crystal display device according to the present invention. FIG. 7A is a diagram showing a state in which a short circuit failure has occurred in the liquid crystal display device of the present invention, and FIG. 7B is a diagram showing a defect repair method of the liquid crystal display device of FIG. It is.

In FIG. 7A, at the short-circuit portion 30, the source signal wiring 6 and the gate signal wiring 4 leak. To correct such a leak, FIG.
First, the source signal line 6 is cut at two cut portions 36 sandwiching the short-circuit portion 30. In the second embodiment, the cutting is performed at the cutting portion 36 on the gate signal wiring 4. However, the cutting is not limited to this, and the source signal wiring 6 may be cut. In addition, each of the two cut portions 36 is shorter than the storage capacitor line 2 closest to the short-circuit portion 30.
The position was closer.

Thereafter, similarly to the disconnection defect repairing method of the first embodiment, the U-shaped wiring (connection path) surrounding the leak portion is cut off from the auxiliary capacitance line 2 by laser irradiation (at six locations indicated by crosses). Cutting at the cutting section 16). In the second embodiment, the connection that overlaps the pixel electrode 10b connected to the cut signal wiring (here, the gate signal wiring 4) so as not to disturb the electrical characteristics of the normally operating pixel electrode 10a. The auxiliary capacitance line 2 is cut off as a path, and the intersection of the separated auxiliary capacitance line 2 and the gate signal wiring 4 is irradiated with a laser beam to connect the two, thereby completing defect repair.

Further, a defect which cannot be completely corrected by the conventional method, for example, when two or more short-circuits occur on the same signal wiring as shown in FIG. Even when the number is larger than the number of spare wirings for correction, the correction can be performed. As the correction method, the above-described correction method is only applied to each short-circuited portion. That is, the source signal wiring 6 is cut at two cut portions 36 sandwiching the short-circuit portion 30, and the auxiliary capacitance line 2 necessary for connecting the cut portions 36 is cut off (6 cuts per disconnection portion 20). Laser cutting is performed on the intersection 17 between the separated auxiliary capacitance line 2 and the source signal wiring 6 to connect the auxiliary capacitance line 2 and the source signal wiring 6 to complete the defect correction. .

[0041]

According to the first aspect of the present invention, the auxiliary capacitance line is formed in a lattice shape in which wirings parallel to the gate signal wiring and the source signal wiring are crossed. In the case of using as a wiring, the number of spare wirings which has conventionally been limited to be formed outside the panel can be greatly increased. At this time, since the intersection of the defect correction wiring can be provided for each picture element, it is possible to perform the defect correction for each picture element. For example, in the same signal wiring, two or more disconnections exist simultaneously. In this case, all the defects can be corrected. Also, since the intersection is located at the center of the picture element, parasitic capacitance is unlikely to occur between each signal wiring.
It does not disturb the electrical characteristics of the picture element.

According to the second aspect of the present invention, the auxiliary capacitance line also serves as a defect repair wiring, so that even if the defect repair is not performed, the wiring formation is not wasted.

According to the third aspect of the present invention, a defect on the signal wiring is controlled by the auxiliary capacitance line formed in a grid shape by crossing the wiring parallel to the gate signal wiring and the source signal wiring for each picture element. Since the wiring surrounding the shape of a square is separated and used as a bypass wiring, the number of defect corrections that had been limited in the past can be greatly increased, and it becomes possible to perform defect correction in pixel units. For example, even when two or more disconnections exist in the same signal wiring at the same time, all the defects can be corrected.

According to the fourth aspect of the present invention, the wiring surrounding the defect on the signal wiring in a U-shape is overlapped with the picture element electrode connected to the signal wiring having the defect. This allows
Originally, a connection path that does not easily overlap with a normally operating picture element electrode is selected, so that the electrical characteristics of a normal picture element electrode are not disturbed.

[Brief description of the drawings]

FIGS. 1A and 1B are diagrams illustrating a configuration of a liquid crystal display device according to a first embodiment. FIG. FIG. 1A is a top view of the liquid crystal display device according to the first embodiment, and FIG.
It is A sectional drawing.

FIG. 2 is a cross-sectional view illustrating another embodiment of the liquid crystal display device according to the first embodiment.

FIGS. 3A and 3B are diagrams for explaining a defect correcting method of the liquid crystal display device according to the first embodiment.
FIG. 3A is a diagram illustrating the liquid crystal display device according to the first embodiment in which a disconnection failure has occurred, and FIG. 3B is a diagram illustrating a defect repair method of the liquid crystal display device in FIG.

FIG. 4 is a diagram showing a defect repair method of the liquid crystal display device different from that of FIG. 3 (b).

FIG. 5 is a structural diagram of a defect repair system using laser light.

FIG. 6 is a diagram showing a defect correction method in a state where a plurality of disconnection defects exist on the same signal wiring in the liquid crystal display device of the present invention.

FIGS. 7A and 7B are diagrams for explaining a defect repair method according to the second embodiment. (A)
7A is a diagram showing a state in which a short-circuit failure has occurred on a signal wiring of the liquid crystal display device of the present invention, and FIG. 7B is a diagram showing a defect repair method of the liquid crystal display device of FIG.

FIG. 8 is a diagram showing a defect repair method when a plurality of short-circuit defects exist on the same signal wiring in the liquid crystal display device of the present invention.

FIGS. 9A and 9B are diagrams showing a configuration of a display area of a conventional liquid crystal display device. FIG. 9A is a top view illustrating a configuration of a conventional liquid crystal display device, and FIG.
It is a BB sectional view of (a).

FIG. 10 is a diagram showing a configuration of a conventional liquid crystal display device having a spare wiring for correction.

FIG. 11 is a diagram for explaining an example of a defect repair method for a liquid crystal display device using a repair spare line.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1, 101 Glass substrate 2, 102 Storage capacitance line 3, 103, 5 Insulating film layer 4, 104 Gate signal wiring 4a, 104a Gate electrode 6, 106 Source signal wiring 6a, 106a Source electrode 7, 107 Semiconductor layer 8, 108 Drain Electrode 9, 109, 9a, 9b TFT 10, 110 Picture element electrode 11 Alignment film 12 Counter electrode 16 Cut section 17 Intersection section 20 Disconnection section 50 Active matrix substrate 51 Counter substrate 60 Laser oscillator 61 Laser beam 62 Slit 63 ND filter 64 Liquid crystal Panel 200 Preliminary wiring for repair 220 Disconnection 230 Connection

Claims (4)

[Claims] 1. A gate signal line and a source signal line are formed orthogonally on an insulating substrate, and a thin film transistor is formed near an intersection of the gate signal line and the source signal line, and is connected to the thin film transistor. In the liquid crystal display device, in which the picture element electrodes are arranged in a matrix and the auxiliary capacity lines are provided, the auxiliary capacity lines are in a grid shape, and the intersections of the auxiliary capacity lines are formed in each picture element. A liquid crystal display device characterized by being located at: 2. The liquid crystal display device according to claim 1, wherein the auxiliary capacitance line also serves as a defect repair wiring. 3. A gate signal wiring, a source signal wiring orthogonal to the gate signal wiring, a thin film transistor formed near an intersection of the gate signal wiring and the source signal wiring on the insulating substrate, and the thin film transistor In the method for correcting a defect of a liquid crystal display device comprising a picture element electrode connected in a matrix and a storage capacity line, the storage capacity line is formed in a grid shape crossing in each picture element. In the case where a defect is present in any of the gate signal wiring and the source signal wiring, the U-shaped wiring surrounding the defect in the auxiliary capacitance line is used as a bypass wiring, A defect correcting method for a liquid crystal display device, wherein a normal signal is propagated to a signal wiring having a defective portion. 4. The defect correcting method for a liquid crystal display device according to claim 3, wherein the U-shaped wiring overlaps a picture element electrode connected to the signal wiring having the defective portion. .