JPH11109409A - Liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the fusion of the extension wiring existing between a terminal and a driving circuit by adopting a crossover structure consisting of a gate material formed in the layer lower than the extension wiring intersecting with a power source line and a ground line for this extension wiring. SOLUTION: The first line intersecting with the power source line and the ground line is formed of the crossover structure of the gate material formed in the layer lower than this first line. The first wiring extended between the two intersected parts is formed of an Al electrode and the electrode disposed integrally to project from the first wiring is formed as the common electrode of a first bottom gate type TFT and a second bottom gate type TFT. Then, the extension wiring 104 extended from the terminal 100 to the driving circuit is not crossed over with the lower layer and in turn a Vss line and a VDD line are crossed over with the lower layer. Consequently, the resistance value may be further lowered as compared with the upper extension wiring 104 to 104" and since Si resistors are not adopted, the dissolution of the extension wiring is averted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device, and more particularly to a device for protecting a surge invading a terminal in a liquid crystal display device including TFTs including a driving circuit. is there.

[0002]

2. Description of the Related Art In recent years, attention has been paid to low power consumption, thin and lightweight, high-definition images, etc. of liquid crystal display devices, and liquid crystal display devices employing TFTs have been actively studied. In particular, a-S
i and poly Si are mainly used, but poly Si has attracted attention from the viewpoints of mobility, aperture ratio, number of process steps and the like, and has been put to practical use.

For example, FIG. 4 is a schematic plan view of a liquid crystal display device. A plurality of wirings extending left and right are gate lines 10, and a plurality of wirings extending vertically are drain lines 11. is there. The gate lines and the drain lines form intersections in a matrix, and the display electrodes 12 and the TFTs 13 electrically connected to the display electrodes 12 form a pair to form a display area.

On the other hand, the glass substrate 14 on which these are formed is
The terminals 15 are arranged in groups on one side, and a driving circuit for driving the liquid crystal display device, here the precharge driver 1 is provided between the terminal groups 15... And the display area.
6 are formed, and a drain driver 1 is provided on the opposite side.
7 are formed. Further, gate drivers 18 are formed on the left and right sides.

The gate driver 18 has wirings 19, 2 for inputting a vertical clock signal and a vertical start signal.
0 is a line to which a horizontal clock signal, a horizontal start signal and a video signal are inputted to the drain driver 17, a line to which a precharge signal and a gate control signal are inputted to the precharge driver 16. 24 and 25 extend around the substrate 14 and are connected to the terminals 15.

When the vicinity of the terminal 15 of the substrate 14 having such a configuration is enlarged, the configuration becomes as shown in FIG. 5, and a protection transistor for absorbing surge is formed at the terminal, and FIG. It is. Here, the solid line is the drain electrode of the TFT constituting the display area, that is, Al.
The alternate long and short dash line is made of poly-Si which is to be a semiconductor layer of a TFT constituting a display region and is formed under Al. Also,
The two-dot chain line is a Cr constituting the gate of the TFT and is disposed below the poly-Si. The portions indicated by the crosses are contacts.

First, a wiring 30 is formed by extending the terminal 15 of FIG. 4 and is made of Al.
1, in order to avoid intersection with the ground line Vss, a crossover is performed using a Cr wiring 32 extending in a lower layer. In addition, a Cr gate 35 is formed which returns from an area of the Vss line to the Al wiring 34 of the upper layer through the poly-Si resistor 33 and then extends to the lower layer. On the upper layer of the Cr gate 35, a semiconductor layer 37 of the surge absorbing transistor 36, that is, poly-Si is formed. The drain electrode 3 of the transistor 36
8, a transistor 40 is formed via a poly-Si resistor 39, and a gate 44 of the transistor 40 is connected to an extended wiring 30 'from a terminal. This extended wiring 30' is connected to a semiconductor layer 45 made of poly-Si. I'm in contact. The extension wiring 30 'has a poly-Si resistor 42, is extended in a lower layer by a Cr wiring 43 in order to avoid intersection with the power supply line VDD, cross-overs, and extends by an extension wiring 30''.
For example, it extends to a precharge driver.

[0008]

In this configuration, when the abnormal pulse (surge) is applied, the poly-Si resistors 31 and 42 are provided to blunt the waveform. If it is too large, the poly-Si resistance is melted, and the extended wirings 30 and 30 'or the extended wirings 30 and 30''are disconnected, and the terminal provided before the extended wiring 30 is provided. Is not transmitted to the wiring 30 '', and the liquid crystal display device does not function.

[0009]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and firstly, the first line which intersects a power supply line and a ground line is formed below the first line. A first wiring extending between the two intersections with a crossover structure using a gate material to be formed,
The problem is solved by using an electrode formed of an Al electrode and integrally provided so as to protrude from the first wiring, as a common electrode of the first bottom gate TFT and the second bottom gate TFT. is there.

Since the active element connected to the display electrode, here the bottom gate, is used, it is possible to reduce the resistance of the wiring extending from the terminal by using a gate material having a lower resistance than poly Si. Yes, and contacts C1, C
2 can be used as a common electrode immediately after taking up only the space for the poly-Si 10 layer constituting the semiconductor layer of the transistor.
Fusing can be performed on the 9, 112 side.

Second, the wiring which crosses the power supply line and the ground line has a crossover structure with a gate material formed below the wiring, and the power supply line is used for the wiring to which the video signal is inputted. The problem is solved by forming the ground line in a crossover structure with a gate material formed in a lower layer. As a gate material, generally, Cr, tantalum, or the like is used.
However, since the resistance value is smaller than that of Al, the most important video signal for display is distorted. However, if the power supply line VDD and the ground line Vss are formed in a cross-over structure using a gate material while the wiring remains Al, the extended wiring can further reduce the resistance value, and at the same time, the video signal Bluntness can also be suppressed.

Third, Cr is excellent in terms of corrosion resistance and the like, and is excellent as a gate material because it has a relatively small resistance value. If this is used as a crossover material, it can be realized without increasing the number of steps. Fourth, extended wiring and V
By forming a non-doped semiconductor layer at the intersection of the DD line, the extended wiring and the Vss line, it is possible to prevent the surge from entering the drive circuit without passing through the transistor.

[0013]

Embodiments of the present invention will be described below. First, a planar arrangement will be described with reference to FIG. A plurality of wirings extending left and right are gate lines 10 made of Cr, and a plurality of wirings extending vertically are drain lines 11 made of Al. And the two lines 10, 1
1, the intersections are formed in a matrix, and display electrodes 12 made of ITO and TFTs 13 electrically connected to the display electrodes 12 form a pair to form a display area.

On the other hand, the glass substrate 14 on which these are formed
The terminals 15 are arranged in groups on one side, and a driving circuit for driving the liquid crystal display device, here the precharge driver 1 is provided between the terminal groups 15... And the display area.
6 are formed, and a drain driver 1 is provided on the opposite side.
7 are formed. Further, gate drivers 18 are formed on the left and right sides. However, the positions of the drain driver and the precharge driver may be exchanged, or the gate driver may be formed on one side.

The gate driver 18 has an Al wiring 1 to which a vertical clock signal and a vertical start signal are input.
9 and 20, a drain driver 17 receives a horizontal clock signal, a horizontal start signal, and a video signal. Al wirings 21, 22, and 23 receive a precharge signal and a gate control signal. Al wirings 24 and 25 are connected to the terminal 15 while rotating around the substrate 14.

Before explaining the pattern of FIG. 1, the sectional structure of the liquid crystal display device will be described. Alkali-free glass 50 is used as a first transparent substrate, on which a transistor gate 51 and a gate line integrated therewith are formed, and an auxiliary capacitance electrode 52 of the same material is formed. Here, Cr is adopted in consideration of corrosion resistance and resistance value, and a tapered structure is adopted in consideration of film breakage on this.

On the entire surface, Si is formed by plasma CVD.
An oxide film 53 and a Si nitride film 54 are formed, and a poly-Si 55 patterned to extend to the transistor region and the auxiliary capacitance region is provided. Here, the impurity P is introduced into the poly-Si, and the low concentration N− type source / drain regions 57 and 58 and the high concentration N + type contact region 5 are formed.
9, 60 are formed. The channel region 56 of the transistor is provided with a mask 61 made of a Si oxide film in order to prevent this impurity.

The auxiliary capacitance is a poly-Si N + type contact region 6 extending to the auxiliary capacitance electrode 52.
0, an auxiliary capacitance electrode 52 made of Cr and an insulating layer 53,
54. Furthermore, plasma CVD is performed on the entire surface.
The Si oxide film 62 and the Si nitride film 63 are covered by the method,
A contact hole is formed by partially opening the contact region 59, and an Al drain electrode 64 is provided.
A flattening film 65 is formed on the entire surface to fill the unevenness of the conventional structure, and a display electrode 66 made of ITO is formed through a contact hole in which a part of the contact region 60 is exposed.
Is provided.

On the other hand, on the second transparent substrate 70, the IT
A counter electrode 67 made of O is provided. In addition, here, for color display, an RGB color filter 6 is used.
8 is provided in a region corresponding to the display electrode 66, and a light shielding film 69 is provided therearound. If necessary, it may be provided before the counter electrode 67 is provided to flatten the unevenness.

The transparent substrates 50 and 70 having the above-described structure are provided with alignment films 71 and 72, and the transparent substrates are disposed to face each other, and a sealing material is provided therebetween, and is formed as a part of the sealing material. Liquid crystal is injected through the injection hole to complete the liquid crystal display. The point of the present invention is how to use the materials used in the configuration of FIG. 3 to configure a transistor for surge absorption. A specific example is shown in FIG.
Will be described with reference to FIG.

First, the relationship between the transistor 101 connected to the terminal 100 and the extended wiring 104 ″ will be described. Similar to the conventional example, it is manufactured using the components shown in FIG. 3, the solid line is Al, the dashed line is poly-Si, and the two-dot chain line is C.
r. The terminal 100 is made of an Al electrode, and may be configured by laminating Cr on the lower layer or ITO on the upper layer. The Al extension wiring 104 electrically connected to the terminal 100 is connected via a lower layer extension wiring 105 made of Cr.
This is connected to the extension wiring 104 ′ of Al.
4 'is again connected to the Al extension wiring 104''via the Cr lower layer extension wiring 106.

The insulating layers 53 and 54 shown in FIG. 3 are provided on the lower layer extending wirings 105 and 106, and the Vss line of Al and the Al extending from the top to the bottom of FIG.
VDD line is provided. When the Vss line crosses the lower extension wiring 105, the gate of the transistor 107, here, a Cr gate 108 is connected, and the Cr gate 108 is covered with a semiconductor layer 109 made of poly-Si. . Here, the transistor is N
Since it is a channel, N-type impurities are introduced except for a region corresponding to the gate 108. And poly Si
The insulating layers 62 and 63 shown in FIG. An Al Vss line is provided as a source electrode, and a part of the extended wiring 104 'is provided so as to protrude in parallel with the VDD line. An Al electrode 110 is in contact with the semiconductor layer via a contact hole as a drain electrode. Also V
When the DD line crosses the lower extension wiring 106, the gate of the transistor 101, here, a Cr gate 111 is connected. On this Cr gate 111, poly S
The semiconductor layer 112 made of i is covered. Here, since the transistor is a P-channel type, the gate 11
Except for the region corresponding to 1, P-type impurities are introduced. Then, the insulating layer 6 shown in FIG.
2 and 63 are covered, an Al VDD line is formed as a source electrode, and an Al electrode 110 in which a part of the extended wiring 104 'is extended is formed as a drain electrode, which is in contact with a semiconductor layer through a contact hole. I have.

The present invention is characterized in that the extended wirings 104 to 10
At 4 ″, the transistor 1 is used without using the poly-Si resistor.
01, 107 is to absorb noise. Instead of using poly-Si as a resistor, a gate material is used where a crossover is required. Al electrode 1
10 extends in parallel with the VDD line and has a contact hole C
1, after passing the length of C2, 10
Since the common electrodes 1 and 107 are formed, they do not melt at the extended wirings 104 to 104 ″, and the surge can be absorbed by the transistor. In addition, even if a surge that blows the poly-Si resistor as in the prior art enters, the fuse is blown in the semiconductor layer (poly-Si) of the transistor, so that the signal applied to the terminal is applied to the extended wiring. Is transmitted to the drive circuit. Therefore, it is possible to extend the normal operation period that can be displayed.

On the other hand, a transistor connected to the terminal 102 and its structure will be described. The Al extending wiring 120 extending to the driving circuit extends to the driving circuit integrally with the common electrode 121 without providing a lower wiring. Conversely, the Vss line of Al and the VDD line of Al are connected via lower wirings 122 and 123 of Cr. The Cr gate of the transistor 124 is formed after the lower wiring 122 of Cr contacts the upper Vss line. On the Cr gate, insulating layers 53 and 54 are provided.
And a poly-Si layer 125 serving as a semiconductor layer of the transistor is formed thereon. Then, again, the insulating layer 6
The Vss line provided in the upper layer through the layers 2 and 63 serves as a source electrode, and the common electrode 121 serves as a drain electrode and contacts the semiconductor layer through a contact hole. The VDD line also crosses over via the lower layer wiring 123, and the VDD line that has risen again to the upper layer is C
It is in contact with the r gate 126. Similarly, insulating layers 53 and 54 are formed over the gate of the transistor 124, and insulating layers 62 and 63 are formed over the semiconductor layer 127.

In this configuration, the extension wiring 120 extending from the terminal 102 to the drive circuit does not cross over to the lower layer, but instead crosses the Vss line and the VDD line to the lower layer. Therefore, the upper extension wirings 104-1
The resistance value can be further reduced as compared with 04 ″. Therefore, since the poly-Si resistor is not employed unlike the conventional structure, the extended wiring is not easily blown, and even if a surge which blows the poly-Si resistor as in the conventional case enters, the transistor of the transistor is not damaged. Only the semiconductor layer is destroyed, and the signal applied to the terminal is transmitted to the drive circuit through the extended wiring. Therefore, it is possible to extend the normal operation period that can be displayed.

In the present invention, since the fluctuations of Vss and VDD and the fluctuations of the video signal are the most important, the terminal to which the video signal enters adopts the structure described for the terminal 102 below, and substantially the other terminals. Adopts the structure described for the terminal 100 above. In fact, it is designed such that when an abnormal pulse enters the protection transistor, the semiconductor layer of poly-Si is melted. However, since the wiring between the terminal and the driving circuit extends around the panel as shown in FIG. 4, the waveform becomes dull before reaching the driving circuit, and the driving circuit is hardly destroyed.

The intersection of the Cr and Al wirings in FIG.
Poly Si is formed. By providing the poly-Si, spark at the intersection can be prevented.

[0028]

As is clear from the above description, the first
In addition, by forming the extended wiring crossing the power supply line and the ground line with a crossover structure using a gate material formed below this extended wiring, the resistance value can be reduced, and the common electrode can be formed. Since it is in the immediate vicinity, it is possible to prevent fusing of the extended wiring between the terminal and the drive circuit.

In particular, the active element connected to the display electrode is
Since the gate is a bottom gate, by using a gate material having a lower resistance value than poly Si, it is possible to prevent the extension wiring extending from the terminal from being blown. Second, the extended wiring crossing the power supply line and the ground line has a crossover structure with a gate material formed below the extended wiring, and the extended wiring is connected to a terminal to which a video signal is input. In the wiring, the power supply line and the ground line have a crossover structure using a gate material formed in a lower layer, so that the video signal can be protected without dulling.

As a gate material, Cr, tantalum, or the like is generally used. Although its resistance is smaller than that of poly-Si, it is higher than that of Al. Although there is a problem, the power supply line VDD and the ground line V
If ss has a crossover structure using a gate material, the extended wiring does not melt and the video signal does not need to be dull.

Third, Cr is excellent in terms of corrosion resistance and the like, and is excellent as a gate material because it has a relatively small resistance value. If this is used as a crossover material, it can be realized without increasing the number of steps. Fourth, extended wiring and V
By forming a non-doped semiconductor layer at the intersection of the DD line, the extended wiring and the Vss line, it is possible to prevent the surge from entering the drive circuit without passing through the transistor.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a protection element used in a liquid crystal display device of the present invention.

FIG. 2 is a diagram illustrating an equivalent circuit of FIG. 1;

FIG. 3 is a cross-sectional view illustrating a liquid crystal display device.

FIG. 4 is a diagram illustrating a substrate of a liquid crystal display device on which a transistor is formed.

FIG. 5 is a diagram illustrating a conventional protection element.

FIG. 6 is a diagram illustrating an equivalent circuit of FIG. 5;

Claims (4)

[Claims] A first transparent substrate; a display region provided on the first transparent substrate, the display region including a plurality of bottom gate type TFTs and a plurality of display electrodes connected thereto; A plurality of terminals formed on side edges; a driving circuit provided between the plurality of terminals and the display area; a wiring electrically connecting the terminal and the driving circuit; A power supply line of the same layer and a ground line of the same layer, a first bottom-gate type TFT for absorbing surge connected between the wiring and the power supply line, and a power supply line between the wiring and the ground line. The connected second bottom gate type TFT for absorbing surge, the second transparent substrate, the counter electrode provided on the second transparent substrate, and the first transparent substrate and the second transparent substrate. An alignment film provided; In a liquid crystal display device having a liquid crystal sealed between a transparent substrate and the second transparent substrate with a sealing material interposed therebetween, the wiring corresponding to an intersection of the power supply line and the ground line includes: A first wiring made of a gate material below this wiring and extending between a first intersection with the power supply line and a second intersection with the ground line is made of an Al electrode, An electrode provided integrally and protruding from the first wiring is provided between the first bottom gate type TFT and the second bottom gate type TFT.
A liquid crystal display device serving as a common electrode of the bottom gate type TFT. 2. The liquid crystal display device according to claim 1, wherein the power supply line and the ground line in the terminal to which the video signal is input have a crossover structure using a gate material formed in a lower layer. 3. The liquid crystal display device according to claim 1, wherein said gate is made of Cr. 4. The liquid crystal display device according to claim 1, wherein a non-doped semiconductor layer is formed at the intersection.