JPH05134261A - Liquid crystal display device - Google Patents

Abstract

PURPOSE:To provide the liquid crystal display device of an active matrix type which does not generate the disconnection of signal lines and shorted line defects by the influence from the outside, such as sticking of foreign matter, and has high reliability. CONSTITUTION:Plural pieces of gate lines 13 and data lines 18 are respectively disposed so as to intersect with each other via insulating films 15 on an insulating substrate 12. The parts of the gate lines 13 disposed nearer the liquid crystal 19 side than the insulating films 15, which part correspond to the sealing materials 25 of a 1st substrate 11 and a 2nd substrate 21 or the parts outer than these parts are formed of the same material to the same layer as the layer of the gate lines 13 disposed nearer the insulating substrate 12 side than the insulating films 15. The ends 31 of the gate lines, etc., are protected by the sufficiently secure insulating films 15. The disconnection of signal lines by corrosive foreign matter, the generation of the shorting by the conductive foreign matter intruding into the sealing material, etc., which are external factors are prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an active matrix type liquid crystal display device using thin film transistors as switch elements.

[0002]

2. Description of the Related Art Liquid crystal display devices have come to be widely used in televisions, graphic displays and the like. The development and development of large-capacity, high-definition active matrix type liquid crystal display devices suitable for these televisions and graphic displays, etc. Practical use is becoming popular. In addition, in this type of liquid crystal display device, a thin film transistor (TFT) that can perform transmissive display and is easy to increase in area is used as a semiconductor switch that drives and controls each pixel so that high-contrast display without crosstalk can be performed. ) Is often used.

The structure of a conventional active matrix type liquid crystal display device using this thin film transistor array will be described with reference to FIGS. 4, 5 and 6. Here, FIG.
4 is a cross-sectional view of the peripheral portion of this active matrix type liquid crystal display device, and FIG. 4 is the first substrate 11 shown in FIG.
FIG. 6 is a plan view of FIG. 6, and FIG. 6 shows an equivalent circuit of the active matrix type liquid crystal display device. The cross-sectional shape shown in FIG. 5 is a portion along line AA in FIG.

First, a specific configuration will be described with reference to FIGS. 4 and 5. In FIG. 5, a first substrate 11 has a plurality of gate lines 13 and a gate electrode 14G of a thin film transistor 14 which is a field effect transistor integrally formed with the gate lines 13 on a transparent insulating substrate 12 such as glass. It was formed. An insulating film 15 is formed so as to cover the gate line 13 and the gate electrode 14G entirely.

A semiconductor layer 16 made of, for example, amorphous silicon is formed at a predetermined position on the insulating film 15, that is, at a position above the gate electrode 14G. further,
A transparent pixel electrode 17 is formed on the insulating film 15. Furthermore, a plurality of data lines 18 are arranged on the insulating film 15 in a positional relationship intersecting with the plurality of gate lines 13. These data lines 18 are made of aluminum, for example, and the semiconductor layer 16
The drain electrode 14D joined to a part of the upper surface of the is integrally formed. A drain electrode is formed on the upper surface of the semiconductor layer 16.
A source electrode 14S is formed so as to face 14D. The source electrode 14S is also made of, for example, aluminum, and the other end is connected to the pixel electrode 17 via the upper surface of the insulating film 15.

Further, at the end of each data line 18, the data shown in FIG.
As shown in FIG. 5, pads 18a for inspecting disconnection and pads 18b for OLB (Outer Lead Bonding) are formed in an end portion on the power feeding side in an alternating arrangement relationship. Note that the pad 18 is provided on the opposite side (not shown) of the first substrate 11.
The relationship between a and 18b is the opposite of the above.

A liquid crystal alignment film 20 is formed on a portion of the insulating substrate 12 on which these elements are arranged, which faces the liquid crystal 19.

On the first substrate 11 thus constructed, a plurality of gate lines 13 and data lines 18 are arranged so as to intersect each other with an insulating film 15 interposed therebetween, and the respective gate lines 13 are provided. And a gate electrode 14G, a drain electrode 14D, and a source electrode 14 which are arranged at respective intersections of the data line 18 and the data line 18.
A thin film transistor 14 composed of S and the semiconductor layer 16, a pixel electrode 17 connected to the source electrode 14S, and a liquid crystal alignment film 20.
And are configured respectively.

In addition, the second substrate 21 with respect to the first substrate 11
The second substrate 21 is formed by sequentially forming a transparent counter electrode 23 and a liquid crystal alignment film 24 on a transparent insulating substrate 22 made of glass or the like, as shown in FIG. This second substrate 21 is 6 μm thicker than the first substrate 11.
It is integrally supported by a sealing material 25 that seals the peripheral portion so as to maintain a gap of about m. And the liquid crystal in the gap
19 are enclosed and sandwiched.

Since the area of the first substrate 11 is larger than that of the second substrate 21, the portion outside the line B shown in the drawing is exposed to the outside.

Next, the overall structure of the active matrix type liquid crystal display device will be outlined with reference to the equivalent circuit of FIG. In this type of liquid crystal display device, a plurality of signal lines, that is, a gate line 13 and a data line 18, are arranged on an insulating substrate 12 so as to intersect each other with an insulating film 15 interposed therebetween. A thin film transistor 14 is provided at each intersection of the data line 18 and the data line 18. And the gate electrode 14
G is connected row by row to gate line 13 and drain electrode 14
D is connected to the data line 18 column by column. Further, the source electrode 14S is connected to the corresponding pixel electrode 17.

In the liquid crystal display device, the gate line 13 is sequentially scanned and driven by the address signal, and the thin film transistor
14 sequentially becomes conductive for each row. Also, this gate line 13
Pixel signals are supplied to the data lines 18 in parallel to the selected several lines in synchronization with the scanning of. Therefore, the signal voltage is sequentially guided to the transparent pixel electrode 17 for each row, excites the liquid crystal 19 sandwiched between the pixel electrode 17 and the counter electrode 23, and becomes an image signal for image display.

In such an active matrix type liquid crystal display device, there are the following problems regarding the reliability of the device.

In FIG. 4, the portion where the power supply side C portion of the data line 18 and the inspection pad 18a at the end portion are adjacent to each other is located outside the end side B of the second substrate 21. Exposed to the external environment. Therefore, when a foreign substance adheres across the adjacent portion D and contains a trace amount of an element such as chlorine having the property of corroding the material of the data line 18, when the device is driven, Due to the electrolytic corrosion, the material of the data line 18 is corroded and broken.

The above phenomenon similarly occurs through the pinholes and cracks of the protective film even when the first substrate 11 having the protective film on its surface is used.

In particular, when the driving method in which the adjacent data lines 18 are in an alternating potential state with each other is adopted, the electrocatalytic phenomenon progresses at a considerably high speed, which causes a line defect fatal to the device. ..

Further, in the case where a conductive foreign substance is mixed in the sealing material 25 shown in FIG. 5 or a conductive foreign substance is adhered during the sealing process, the foreign substance is removed during the pressure bonding in the sealing process. , The data line 18 of the first substrate 11 and the second substrate 21
There may be a short circuit with the counter electrode 23 of. First
Even if the substrate 11 and the second substrate 21 are provided with a protective film of silicon nitride (SiN) or the like on their surfaces,
The conductive foreign matter penetrates through this protective film during pressure bonding, resulting in a short circuit. When this short circuit occurs, a so-called short line defect, that is, a linear defect in image quality will occur.

[0018]

As described above, the signal line 13 formed on the insulating film 15 of the first substrate 11 is easily affected by the outside, and the foreign matter attached to the adjacent portion causes a disconnection. In addition, there is a problem that a short-circuit line defect occurs due to the conductive foreign matter in the seal portion.

It is an object of the present invention to provide a highly reliable active matrix type liquid crystal display device which does not cause signal line disconnection or short line defect due to external influences such as foreign matter adhesion. ..

[0020]

According to the present invention, a signal line group consisting of an address signal input wiring and a data signal input wiring is arranged on a transparent insulating substrate so as to cross each other with an insulating film interposed therebetween. At each intersection of each signal line, a gate electrode is integrally formed with one of the signal lines, a drain electrode is integrally formed with the other signal line, and a source electrode is connected to the pixel electrode. A first substrate provided with each thin film transistor and a second substrate having a counter electrode formed on one surface facing the first substrate are arranged with a gap therebetween while sealing the peripheral portion with a sealing material, In a liquid crystal display device in which liquid crystal is sealed in the gap, an end portion of the signal line group corresponds to any one of the sealing members of the signal lines arranged on the liquid crystal side of the insulating film. Part or The outer portion than the liquid crystal holding portions including the serial seal portion, wherein is obtained by forming the same material in the same layer as the other one of the signal lines wherein disposed on the insulating substrate side of the insulating film.

[0021]

In the present invention, of the signal line group consisting of the address signal input wiring and the data signal input wiring, a portion corresponding to the sealing material of one of the signal lines arranged on the liquid crystal side of the insulating film or the seal. Since the part outside the liquid crystal sandwiching part including the part is formed of the same material in the same layer as one of the other signal lines arranged on the insulating substrate side of the insulating film, the signal line in this part has strong insulation. It is protected by the film, is not affected by foreign substances adhering from the outside, and is free from disconnection or short-circuit defects.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the liquid crystal display device of the present invention will be described below with reference to the drawings.

The equivalent circuit of the liquid crystal display device is the same as the conventional structure shown in FIG. 6, and the specific structure has many similarities to the conventional structure examples shown in FIGS. 4 to 6. Therefore, corresponding parts are designated by the same reference numerals, and the structure thereof will be described in relation to the manufacturing process.

FIG. 2 is a plan view showing the structure of the first substrate, FIG. 1 is a sectional view of the liquid crystal display device, and FIG.
2B shows a sectional shape of a portion along line A, and FIG.
The cross-sectional shape of the portion along E is shown.

2 and 1, molybdenum (Mo) is sputtered on the first substrate 11 on the transparent insulating substrate 12 made of glass or the like to have a thickness of 150 n as in the conventional case.
Then, the gate line 13 and the gate electrode 14G integral with the gate line 13 are patterned.

At this time, a part of the data line 18 that intersects with the gate line 13 through the insulating film 15, that is, the second line shown in FIG.
The data line end portions 31 extending from the inside to the outside of the seal portion with the substrate 21 are also patterned in the same number as the data lines 18 as the signal lines together with the gate lines 13 and the gate electrodes 14G. The data line ends 31 as the signal line ends are the data lines 18
2 and the end on the power supply side. The end of the data line 18 has an inspection pad 31a for disconnection inspection as shown in FIG. 2 and the end on the power supply side. Is OLB
The pads 31b for (Outer Lead Bonding) are formed in advance.

Next, an insulating film 15 made of, for example, silicon oxide (SiO _x ) is deposited with a thickness of 330 nm by plasma CVD so as to cover these upper surfaces, and the inspection pad 31a and the OLB pad 31b are formed. Through holes 31c and 31d are formed so that only the portions are exposed to the outside.

Next, at a predetermined position on the insulating film 15, that is,
In order to form the semiconductor layer 16 above the gate electrode 14G, for example, amorphous silicon is deposited by plasma CVD to a thickness of 300 nm and patterned into the shape shown. Further, for example, ITO (Indium Tin Oxicide) is deposited to a thickness of 150 nm by sputtering on the insulating film 15 at positions corresponding to the respective intersections shown in FIG. 6 in order to form transparent pixel electrodes 17, respectively. , A pattern is formed in the shape shown in FIG.

Next, contact holes 32 are formed in the insulating film 15 corresponding to the inner ends of the respective data line ends 31 to expose the upper surfaces of the inner ends of the respective data line ends 31. After that, a plurality of data lines 18 and a plurality of gate lines 13 are formed on the insulating film 15.
It is installed so as to intersect with. These data lines 18 are made of aluminum, for example, and are formed integrally with the drain electrode 14D that is joined to a part of the upper surface of the semiconductor layer 16. At this time, the drain electrode 14 is formed on the upper surface of the semiconductor layer 16.
The source electrode 14S is also formed so as to face D. The source electrode 14S is also made of, for example, aluminum and has an insulating film.
The other end is connected to the pixel electrode 17 via the upper surface of 15.

Here, the end of each data line 18 is set so as to overlap the inner end of the data line end 31, and as shown in FIG. 1, it corresponds through the contact hole 32. Connected to the data line ends 31 respectively.

Next, a liquid crystal alignment film 20 made of polyimide is formed by coating on a region facing the liquid crystal 19 on the insulating substrate 12 on which each element is arranged as described above.

On the first substrate 11 thus constructed, a plurality of gate lines 13 and a plurality of data lines 18, which are arranged so as to intersect each other with an insulating film 15 interposed therebetween, as in the conventional case, The gate electrode 14G and the drain electrode 14D are provided at the intersections of the gate lines 13 and the data lines 18, respectively.
, The thin film transistor 14 including the source electrode 14S and the semiconductor layer 16, and the pixel electrode 17 connected to the source electrode 14S.
, And a liquid crystal alignment film 20, respectively, each of the end portions 31 of the plurality of data lines 18 in the same layer as the gate line 13,
Sufficiently strong gate insulating film made of the same material
It is covered by 15.

The second substrate 21 is the same as the conventional one, and a 100 nm thick IT is formed on a transparent insulating substrate 22 made of glass or the like.
A transparent counter electrode 23 and a liquid crystal alignment film 24 made of O are sequentially formed. Then, the second substrate 21 is integrally supported by a sealing material 25 that seals the peripheral portion so as to maintain a gap of about 6 μm with respect to the first substrate 11, and the liquid crystal 19 is enclosed in the gap. , Sandwiched.

In the above structure, the ends of the gate line 13 and the data line 18 are led to the outside so as to receive signals from the outside, but the gate line 13 is originally arranged in a sufficiently strong insulating film 15. It has been done and there is no problem. Data line 18
For the data line end 31 that is led to the outside,
Since it will be installed in 15, there will be no problem. That is, outside the outer edge of the second substrate 21, as shown in FIG. 2, it straddles the adjacent portion E between the inspection pad 31a exposed to the external environment and the power supply side data line end 31. Pad for OLB even if foreign matter adheres in the form of a trace element and has a property of corroding the material of the data line 18
Most of the data line end 31 on the power supply side except for 31b is an insulating film
Since it is confined within 15, the data line
There is no galvanic corrosion on 18 and therefore no disconnection.

Further, even if a conductive foreign substance is mixed in the sealing material 25, or if a conductive foreign substance is adhered during the sealing process and pressure is applied in the sealing process, the first substrate 11
The data line end 31 of the data line 18 of the
Conductive foreign matter is covered by this insulating film 15
There is no breakthrough. Therefore, a short circuit is not made between the counter electrode 23 of the second substrate 21 and a so-called short-circuit line defect, that is, a linear defect due to this short circuit can be prevented.

If there is almost no adhesion of foreign matter at the exposed portion and only the short circuit at the seal portion poses a problem, only the portion corresponding to the sealing material 25 is removed as shown in FIG. It may be arranged in the insulating film 15. That is, the data line end portion 31 is formed by patterning only the portion reaching from the inside to the outside of the sealing material 25 in the same layer and with the same material when forming the gate line 13 not shown. In addition, the insulating film 15 covering them has a sealing material 25 at the end 31 of the data line.
The contact holes 32a and 32b are provided at the portions corresponding to the inner end portion and the outer end portion, respectively. When forming the data line 18 on the insulating film 15, the data line 18 made of aluminum is formed until it reaches the inner contact hole 32a, and on the outside of the sealing material 25, from the outer contact hole 32b to the outer side. Form so as to extend to. As a result, the data line 18 has a data line end 31.
It is led to the outside through the and is further connected to the inspection pad 18a outside.

With this configuration, the data line
Since 18 is covered and protected by a sufficiently strong insulating film 15 in the seal portion, conductive foreign matter is mixed in the seal material 25, or conductive foreign matter adheres during the sealing step, and the sealing step Even if a pressing force is applied to the conductive film, the conductive foreign matter does not break through the insulating film 15.
There is no short circuit between the counter electrode 21 and the counter electrode 23.

In the example of FIG. 3, the surface of the first substrate 11 is covered with the SiN protective film 36, and the data line
The protection function for 18 mag is improved.

[0039]

As described above, according to the present invention, among a plurality of signal lines arranged on an insulating substrate so as to intersect each other with an insulating film interposed therebetween, the signal lines are arranged closer to the liquid crystal than the insulating film. At least the part of the signal line that corresponds to the sealing material,
Since it is formed of the same material in the same layer as the signal line arranged on the insulating substrate side of the insulating film, it can be protected by a sufficiently strong insulating film. Therefore, it is possible to prevent disconnection of the signal line due to corrosive foreign substances, which is an external factor, and occurrence of a short circuit due to conductive foreign substances mixed in the sealing material. That is, the yield is improved without changing the manufacturing process,
The reliability as a liquid crystal display device can be improved.

[Brief description of drawings]

FIG. 1A is a cross-sectional view taken along the line AA shown in FIG. 2 of an embodiment of the liquid crystal display device of the present invention. (B) It is an EE sectional view shown in FIG. 2 of an embodiment of the liquid crystal display device of the present invention.

FIG. 2 is a partial plan view of the same.

FIG. 3 is a sectional view showing another embodiment of the same.

FIG. 4 is a partial plan view showing a conventional liquid crystal display device.

5 is a cross-sectional view taken along the line AA of FIG.

FIG. 6 is an equivalent circuit diagram of a general liquid crystal display device.

[Explanation of symbols]

 11 First substrate 12 Insulating substrate 13 Gate line as signal line 14 Thin film transistor 14D Drain electrode 14G Gate electrode 14S Source electrode 15 Insulating film 17 Pixel electrode 18 Signal line 19 Liquid crystal 21 Second substrate 23 Counter electrode 25 Sealing material 31 Signal Line end

Claims (1)

[Claims] 1. A signal line group consisting of an address signal input line and a data signal input line is arranged on a transparent insulating substrate so as to cross each other through an insulating film, and at each intersection of these signal lines. , A gate electrode is integrally formed with one of the signal lines, a drain electrode is integrally formed with the other signal line, and a source electrode is provided with a thin film transistor connected to the pixel electrode. A substrate and a second substrate having a counter electrode formed on one surface facing the first substrate are arranged with a gap kept in a state where a peripheral portion is sealed with a sealing material, and a liquid crystal is sealed in the gap. In the liquid crystal display device, an end portion of the signal line group includes a portion corresponding to one of the seal members or the seal portion among the signal lines arranged on the liquid crystal side of the insulating film. The above The liquid crystal display device characterized by the outer portion than Akirakyo lifting unit, formed by the same material in the same layer as the other one of the disposed in the insulating substrate side of the insulating film was the signal line.