JP3480155B2 - Active matrix display device and manufacturing method thereof - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an active matrix display device in which pixels each having a pixel electrode and a thin film transistor for driving the pixel electrode are integrated and formed, and a manufacturing method thereof. More specifically, it relates to a repair technique for repairing pixel defects by laser processing.

[0002]

2. Description of the Related Art An active matrix display device has a panel structure in which a drive substrate made of glass or the like and an opposite substrate made of glass or the like are bonded to each other and an electro-optical material such as liquid crystal is held in a gap between the two. Pixels composed of pixel electrodes and thin film transistors for writing a signal voltage to the pixel electrodes are integrally formed on the inner surface of the driving substrate. A counter electrode is entirely formed on the counter substrate. The transmittance of the liquid crystal held in the gap between the two changes for each pixel according to the signal voltage. This active matrix display device has a normally white mode and a normally black mode. In normally white mode, pixels are white spots (bright spots) when no voltage is applied.
And changes to a black dot (dark spot) when a voltage is applied. On the contrary, in the normally black mode, the pixel becomes a black dot when no voltage is applied, and the pixel changes to a white dot when a voltage is applied. Of course, there may be cases where a gray color of halftone is exhibited depending on the level of the applied signal voltage.

[0003]

The number of pixels has increased remarkably as the definition of the active matrix display device has become higher, and for example, the number of pixels may exceed one million. In such a high-definition active matrix display device, it is practically difficult to form a myriad of pixels completely without defects.
As a method of coping with such a pixel defect, a method of providing redundancy for a pixel defect and a method of repairing a defective pixel have been proposed. To have redundancy, for example, 1
2 switching thin film transistors for each pixel
It is conceivable that there are one or more units. However, if a plurality of switching elements are provided, the aperture ratio of the pixel is sacrificed by that amount, and the contrast of the active matrix display device is reduced. On the other hand, as a repair technique for repairing defective pixels, a method using laser processing has been attracting attention. For example, the wiring of the defective pixel is cut by laser processing without contact, and the thin film transistor is separated from the wiring side. This method is effective in repairing a pixel defect in the normally black mode. That is, the white spot defect that occurs when a voltage is applied can be converted to a black spot defect by applying a voltage to the white spot defect by cutting with laser processing. Generally, a black dot defect is less noticeable than a white dot defect, so that the active matrix display device can be repaired to a level where there is practically no problem in quality. However, this cannot repair the normally white mode active matrix display device. In this case, a metal wiring called a short bar is installed between the pixel electrode and the gate wiring to convert the white dot defect into a black dot defect. That is, the white spot defect that occurs when no voltage is applied can be converted into a black spot defect by providing the gate voltage at all times by providing the short bar. However, it is necessary to install the short bar from the inner surface side of the drive substrate. Therefore, there is a problem that repair work cannot be performed after the panel is assembled by joining the drive substrate and the counter substrate. Further, in the cutting by the laser processing described above, the laser irradiation is conventionally performed from the inner surface side of the driving substrate. Therefore, if the repair process is attempted after the drive substrate and the counter substrate are bonded to each other and the liquid crystal is injected between them, the laser light passes through the liquid crystal and is damaged. Therefore, in reality, only the repair work before assembling was possible. However, before assembly, the inspection and identification of defective pixels must rely on electrical measurements. Therefore, there is a problem that the repair work is extremely complicated.

[0004]

Means for Solving the Problems The following means have been taken in order to solve the above-mentioned problems of the conventional technology. That is, the active matrix display device according to the present invention includes a transparent driving substrate, a counter substrate, and an electro-optical material as a basic structure. Pixels composed of pixel electrodes and thin film transistors for writing a signal voltage to the pixel electrodes are integrally formed on the transparent driving substrate. The counter substrate has a counter electrode and is bonded to the transparent drive substrate via a predetermined gap. The electro-optical material is held in the gap between both substrates and changes from white dots to black dots in each pixel according to the signal voltage. Therefore, the active matrix display device is in the normally white mode. On the inner surface of the transparent drive substrate, a gate wiring, a gate insulating film that covers the gate wiring, a semiconductor thin film that is located on the gate insulating film and becomes an active layer of the thin film transistor, and an interlayer insulating film on the thin film A connected pixel electrode and a laser-processable repair region are provided. As a feature, the repair region is short between melted and pixel electrode and the gate wiring by laser processing from the back surface of the transparent driving substrate, a defective pixel of the white spot be those converted into black spots, the repair area is provided for each pixel, possess at least a portion of the gate wiring, and the gate insulating film, a laminated structure in which a part of the pixel electrode overlap each other outside the opening of the pixel, the repair region pixel A part of the metal film formed for light shielding of the thin film transistor is interposed between a part of the electrode and a part of the gate wiring.

The present invention includes a method of manufacturing an active matrix display device. That is, according to the present invention, the active matrix display device is manufactured by the following steps. First, a pixel including a pixel electrode and a thin film transistor is formed on the inner surface of one transparent insulating substrate, and a repair region in which a part of the pixel electrode and a part of a gate wiring connected to the thin film transistor overlap each other through an insulating film. Form an integrated structure. Next, a counter electrode is formed on the inner surface of the other transparent insulating substrate. Then, both transparent insulating substrates are bonded to each other through a predetermined gap and the electro-optical material is held in the gap. After that, each pixel is driven through the thin film transistor to detect a white spot defect. Finally, the repair region corresponding to the pixel having the white spot defect is irradiated with a laser beam from the back surface of the one transparent insulating substrate to melt and short-circuit the pixel electrode and the gate wiring to convert the white spot defect into the black spot defect. Where the repair area is integrated
In the process of forming, a repair area is provided for each pixel, and at least
Part of the gate wiring, the gate insulating film, and the pixel electrode.
A laminated structure in which a part of the poles overlaps other than the pixel opening
However, the repair area is a part of the pixel electrode and the gate wiring.
Formed to shield the thin film transistor between a part of
A part of the metal film is interposed.

According to the present invention, in the normally white mode active matrix display device, a repair area is provided for each pixel. This repair region is melted by laser processing from the back surface of the transparent driving substrate and short-circuits between the pixel electrode and the gate wiring, and the defective pixel with white dots is converted into black dots. As a result, the pixel defect becomes inconspicuous and the yield of the active matrix display device can be improved at a considerable rate. When the pixel electrode and the gate wiring are short-circuited, the gate voltage is constantly applied to the pixel, and the pixel becomes a black dot regardless of the signal voltage. In particular, the active matrix display device employs a bottom-gate thin film transistor, and the repair region has a laminated structure in which a part of the lower gate wiring and a part of the upper pixel electrode overlap. Therefore, laser processing can be performed from the back surface side of the transparent drive substrate, and there is no fear that the laser beam will pass through an electro-optical material such as liquid crystal. Therefore, the repair work can be performed at a stage after the panel is assembled, and it is possible to search for the defective pixel and repair it while performing a normal image inspection.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The best mode for carrying out the present invention will be described in detail below with reference to the drawings. FIG. 1 is a schematic partial sectional view showing the configuration of an active matrix display device according to the present invention. As shown in the figure, this active matrix display device has a panel structure in which a transparent drive substrate 1 made of glass or the like and a counter substrate 2 made of glass or the like are joined together. An electro-optical material 3 such as liquid crystal is held in the space between the substrates 1 and 2. The transparent drive substrate 1 is integrally formed with pixels each including a pixel electrode 4 and a thin film transistor 5 for writing a signal voltage thereto. Note that only one pixel is shown for ease of illustration. In addition, the signal voltage is transmitted through the signal wiring 6 to the thin film transistor 5 which is in a conductive state.
Is written to the pixel electrode 4. The counter substrate 2 includes a counter electrode 7 formed on the entire surface. The electro-optical material 3 held between the substrates 1 and 2 changes from a white dot to a black dot for each pixel according to the signal voltage. Therefore, this active matrix display device is in the normally white mode, and each pixel becomes a white dot when no voltage is applied, and becomes a black dot when a voltage is applied.

As a concrete structure, the gate wiring 9 is provided on the inner surface 8 of the transparent driving substrate 1, the gate insulating film 10 covering the same is provided, and the semiconductor thin film 11 which is located thereon and serves as an active layer of the thin film transistor 5. And are formed. Further, a channel stopper 12 is formed on the semiconductor thin film 11. Directly below the channel stopper 12 is the semiconductor thin film 1.
The gate electrode G is provided via the gate insulating film 1 and the gate insulating film 10. The gate electrode G extends from a part of the gate wiring 9. Impurities are implanted into the semiconductor thin film 11 using the channel stopper 12 as a mask, and a source region S and a drain region D are formed. The bottom gate type thin film transistor 5 having such a configuration is covered with an interlayer insulating film 13 made of PSG or the like. The interlayer insulating film 13 has contact holes 14, 1
5 is formed by etching. Interlayer insulating film 13
A signal wiring 6 made of aluminum, chrome, titanium, or the like is patterned on the upper surface of the wiring, and is electrically connected to the source region S through the contact hole 14. or,
The metal film 16 in the same layer as the signal wiring 6 is also patterned and electrically connected to the drain region D through the contact hole 15. The metal film 16 has a light shielding function and shields the thin film transistor 5 from incident light to suppress light leakage. The signal wiring 6 and the metal film 16 are covered with a flattening film 17 made of acrylic resin or the like, and the above-mentioned pixel electrode 4 is patterned on the surface thereof. A contact hole is opened in the flattening film 17, and the pixel electrode 4
Is electrically connected to the drain region D of the thin film transistor 5 via the metal film 16.

As a feature of the present invention, the transparent drive substrate 1
A repair region 18 is provided on the inner surface 8 of the. The repair region 18 is provided for each pixel, and has a laminated structure in which at least a part R of the gate wiring 9, the gate insulating film 10, and a part of the pixel electrode 4 overlap each other except the opening of the pixel. Further, the repair region 18 is formed between the pixel electrode 4 and the gate line 9 by a part R.
A part of the metal film 16 formed for shading is interposed. The repair region 18 having such a configuration is melted by laser processing from the back surface 19 of the transparent driving substrate 1, short-circuits the pixel electrode 4 and the gate wiring 9, and converts a defective pixel of a white dot into a black dot. That is, before the laser processing, the part R of the gate wiring 9 in the repair region 18 and the pixel electrode 4 are insulated from each other at least by the gate insulating film 10. When the repair region 18 is irradiated with a laser beam having a predetermined energy, local melting occurs and a part R of the gate wiring 9 and a part of the pixel electrode 4 are short-circuited to each other via a part of the metal film 16. To do. As a result, the gate voltage is always applied to the pixel electrode 4, and the white spot defect (bright spot defect) can be changed to the black spot defect (dark spot defect).

The manufacturing method of the active matrix display device according to the present invention will be described in detail with reference to FIG. First, pixels and repair regions 18 are integrated and formed on the inner surface of one transparent insulating substrate (transparent driving substrate 1). As described above, the pixel includes the pixel electrode 4 and the thin film transistor 5. The repair region 18 has a laminated structure in which a part of the pixel electrode 4 and a part R of the gate wiring 9 connected to the thin film transistor 5 overlap each other through an insulating film. Next, the counter electrode 7 is formed on the inner surface of the other transparent insulating substrate (counter substrate 2).
To form. After that, the transparent driving substrate 1 and the counter substrate 2 are bonded to each other through a predetermined gap, and the electro-optical substance 3 such as liquid crystal is injected into the gap. Subsequently, each pixel is driven through the thin film transistor 5 to detect a white spot defect.
The so-called picture inspection is performed to detect defects in each pixel.
Finally, the repair area 1 corresponding to the pixel having the white spot defect
8 is irradiated with a laser beam from the rear surface of the transparent drive substrate 1,
The pixel electrode 4 and the gate wiring 9 are melted and short-circuited to convert the white spot defect into the black spot defect. As a result, an active matrix display device having practically no image quality problem is completed. In the repair region 18, the gate insulating film 1 is formed on the gate wiring 9.
The metal film 16 and the pixel electrode 4 overlap with each other with the semiconductor thin film 11 made of 0 and polycrystalline silicon interposed therebetween. A part R of the gate wiring 9 is irradiated with a laser beam to destroy the insulating film and short-circuit the part R of the gate wiring 9 and the metal film 16 and the pixel electrode 4 which are melted. As a result, the gate potential far exceeding the threshold value of the electro-optical material 3 is constantly applied to the pixel electrode 4, and the bright spot changes to the dark spot in the normally white mode.

FIG. 2 is a schematic plan view showing one pixel of the active matrix display device according to the present invention. As shown, pixels are arranged at the intersections of the row-shaped gate wirings 9 and the column-shaped signal wirings 6. This pixel has a pixel electrode 4
And a thin film transistor 5 for switching and driving the same. The thin film transistor 5 has a semiconductor thin film 11 such as polycrystalline silicon as an element region. This semiconductor thin film 11
Are patterned into long islands. A gate electrode G is extended from the gate wiring 9 and overlaps with the semiconductor thin film 11 via the gate insulating film to form the bottom gate type thin film transistor 5 described above. The source region S of the thin film transistor 5 has one contact hole 14
It is electrically connected to the signal wiring 6 via. Further, the drain region D is connected to the pixel electrode 4 through the other contact hole 15.
Connected to. A part R of the gate wiring 9 is extended to form a repair region 18. A part R of the gate wiring is formed on the pixel electrode 4 which is located on the gate insulating film, the semiconductor thin film 11 and a metal film (not shown).
Overlaps with. Although the repair region 18 and the contact hole 15 in the drain region D are provided separately in this example, they may be shared in some cases. As understood from the figure, the repair region 18 is provided for each pixel, and has a laminated structure in which a part R of the gate wiring 9 and a part of the pixel electrode 4 overlap each other except the opening of the pixel. The size of the repair region 18 may be about 5 μm × 5 μm. Therefore, the pixel aperture ratio is not sacrificed.

Finally, with reference to FIG. 3, a specific configuration example of the active matrix display device according to the present invention will be described. As shown in the figure, the liquid crystal display device includes a transparent driving substrate 101.
And a transparent counter substrate 102 and an electro-optic material 103 held between the two, and is a so-called direct-view type. A pixel array section 104 and a drive circuit section are integrally formed on the transparent drive substrate 101. The drive circuit unit is the vertical drive circuit 1
05 and the horizontal drive circuit 106. Also, a terminal portion 1 for external connection is provided on the upper edge of the peripheral portion of the transparent driving substrate 101.
07 are formed. The terminal portion 107 is connected to the vertical drive circuit 105 and the horizontal drive circuit 106 via the wiring 108. The pixel array section 104 includes a gate wiring 109 and a signal wiring 110 that intersect each other. Both wiring 10
A pixel electrode 111 and a bottom gate type thin film transistor 112 that drives the pixel electrode 111 are integrated and formed at the intersection of 9, 110, and form a pixel. A repair area 113 is provided corresponding to each pixel. This repair area 1
Laser processing 13 is possible by irradiating a laser beam from the back surface of the transparent drive substrate 101. On the other hand, on the inner surface of the transparent counter substrate 102, although not shown, a counter electrode and, in some cases, a color filter are formed.

[0013]

As described above, according to the present invention, the repair area is provided corresponding to each pixel. This repair region is melted by laser processing from the back surface of the transparent driving substrate, and the pixel electrode and the gate wiring are short-circuited, and the defective pixel with white dots can be converted into black dots. As a result, the manufacturing yield of the active matrix display device can be improved.
In addition, since laser processing can be performed at the stage of assembling the active matrix display device, the process of inspecting and repairing pixel defects becomes easy.

[Brief description of drawings]

FIG. 1 is a schematic partial cross-sectional view showing the structure of an active matrix display device according to the present invention.

FIG. 2 is also a schematic partial plan view showing the configuration of the active matrix display device according to the present invention.

FIG. 3 is a schematic perspective view showing a specific configuration of an active matrix display device according to the present invention.

[Explanation of symbols]

1 Transparent drive board 2 Counter substrate 3 Electro-optical material 4 pixel electrodes 5 thin film transistor 6 signal wiring 7 Counter electrode 8 inner surface 9 Gate wiring 10 Gate insulating film 11 Semiconductor thin film 13 Interlayer insulation film 16 Metal film 17 Flattening film 18 repair area 19 back side

Claims (2)

(57) [Claims] 1. A transparent driving substrate on which a pixel composed of a pixel electrode and a thin film transistor for writing a signal voltage is integrally formed, a counter substrate having a counter electrode and bonded to the transparent driving substrate through a predetermined gap, A normally white mode active matrix display device comprising an electro-optical material which is held in a gap and changes from a white dot to a black dot for each pixel according to a signal voltage, wherein a gate is formed on an inner surface of the transparent driving substrate. A wiring, a gate insulating film that covers the wiring, a semiconductor thin film that is located on the gate insulating film and serves as an active layer of a thin film transistor, a pixel electrode that is connected to the thin film transistor through an interlayer insulating film, and a laser-processable repair. The repair area is melted by laser processing from the back surface of the transparent driving substrate to short-circuit between the pixel electrode and the gate wiring to form a white dot. The defective pixel be those converted into black spots, the repair area is provided for each pixel, at least the gate
Part of the wiring, the gate insulating film, and part of the pixel electrode
Has a laminated structure in which a portion other than the opening portion of the pixel is overlapped, and the repair region is a part of the pixel electrode and a portion of the gate wiring.
Formed for shielding the thin film transistor between the
An active matrix display device characterized in that a part of the film is interposed . 2. A repair in which a pixel including a pixel electrode and a thin film transistor is formed on the inner surface of one transparent insulating substrate, and a part of the pixel electrode and a part of a gate wiring connected to the thin film transistor are overlapped with each other through an insulating film. A step of integrally forming a region, a step of forming a counter electrode on the inner surface of the other transparent insulating substrate, and a step of bonding both transparent insulating substrates to each other with a predetermined gap and holding an electro-optical substance in the gap. A step of driving each pixel through the thin film transistor to detect a white spot defect, and irradiating a laser beam from the back surface of the transparent insulating substrate on the repair region corresponding to the pixel having the white spot defect and the white point defects by melting shorting the gate wiring a method for manufacturing an active matrix display device which performs the step of converting the black spot defect, to integrated form said repair area Process, viewing the repair area
It is provided for each element, and at least a part of the gate wiring and the gate
The insulating film and a part of the pixel electrode except for the opening of the pixel.
The repair region has an overlapping laminated structure, and the repair region is
A thin film transistor is provided between a part of the gate wiring and a part of the gate wiring.
A part of the metal film formed for light shielding is interposed.
Of active matrix display device characterized by
Law.