JP2001142092A - Liquid crystal display device and method of producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To decrease the contact resistance of a semiconductor layer with a source electrode and a drain electrode, to improve the adhesion property and to prevent cutting in lines due to intrusion of a chemical liquid during etching a transparent conductive film. SOLUTION: A gate electrode 4, gate insulating film GI, A-Si layer 7 as a semiconductor layer, N(+)a-Si layer 8 as a contact layer and transparent conductive layer 11 are formed in this order on the inner face of an insulating substrate 1 (SUB1) which constitutes an active matrix substrate where a thin film transistor is formed, and a silicide layer 10 is inserted between the N(+)a-Si layer 8 and the transparent conductive layer 11.

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 an active matrix type liquid crystal display device such as a thin film transistor (TFT) type, which can simplify a manufacturing process and drive efficiently an in-plane switching method. And a method of manufacturing the same.

[0002]

2. Description of the Related Art Liquid crystal displays are widely used as devices for displaying various images including still images and moving images. A liquid crystal display device basically sandwiches a liquid crystal layer between two substrates at least one of which is made of transparent glass or the like,
A type in which predetermined pixels are turned on and off by selectively applying voltages to various electrodes for pixel formation formed on the substrate (so-called,
A liquid crystal panel using a simple matrix type, and a type in which a switching element is formed for each pixel and a predetermined pixel is turned on and off by selecting the switching element (a so-called switching element such as a thin film transistor (TFT)). (Active matrix type liquid crystal panel used as a liquid crystal panel).

In particular, the latter active matrix type liquid crystal display device has become the mainstream of the liquid crystal display device because of its contrast performance, high-speed display performance and the like. Active matrix liquid crystal display devices generally employ a vertical electric field method in which an electric field for changing the orientation of a liquid crystal layer is applied between an electrode formed on one substrate and an electrode formed on the other substrate. Recently, an in-plane electric field method (In-Plane Swi) in which the direction of an electric field applied to a liquid crystal is made substantially parallel to the substrate surface.
(Tching Mode: IPS mode) liquid crystal display devices have been put to practical use. In this method, since the liquid crystal molecules rotate in the plane of the substrate, the viewing angle dependence of the contrast is greatly improved in principle, and this method is suitable for a display in which a plurality of persons view from different directions.

In an active matrix type liquid crystal display device, a thin film transistor as a switching element is
Forming a semiconductor layer on the gate electrode via an insulating layer,
A drain electrode and a source electrode are formed on this semiconductor layer.

Further, in a lateral electric field type liquid crystal display device, an electric field is applied between electrodes formed in parallel with the substrate, and thus, in principle, a transparent electrode becomes unnecessary. However, on the other hand, in order to ensure the reliability of the terminal part, that is, the wiring material may be oxidized and corroded or dissolved by energization,
It was necessary to cover the terminal portion with a transparent conductive film that was a chemically stable oxide.

[0006]

As described above, in an active matrix type liquid crystal display device, a thin film transistor as a switching element has a semiconductor layer formed above a gate electrode with an insulating layer interposed therebetween. A drain electrode and a source electrode are formed thereon. The semiconductor layer, the drain electrode, and the source electrode are configured to obtain a required contact with a semiconductor contact layer formed on the semiconductor layer.

However, the drain electrode and the source electrode are
It is made of an oxide transparent electrode such as TO, and cannot be said to have good adhesion to the underlying semiconductor contact layer, and there is a limit to reducing the contact resistance. Further, if the adhesion is insufficient, a chemical solution may permeate during etching of the transparent conductive film formed on the upper layer, and the characteristics may be deteriorated.

In a horizontal electric field type liquid crystal display device, since a liquid crystal molecule is rotated by applying a voltage between comb-shaped electrodes, light is not transmitted through the electrode portion, and therefore, the liquid crystal display device is different from the vertical electric field type. Also, there is a problem that the light transmittance is reduced.

Also, as described in Japanese Patent Application No. 7-211742, a pixel electrode formed of a transparent conductive film separately from conductive wiring has been proposed for the purpose of improving light transmittance. ing. However, the structure described in this publication has a problem that the manufacturing process is complicated and the manufacturing cost is increased.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems of the prior art, and to reduce the contact property and the resistance of a semiconductor layer constituting a thin film transistor and a transparent electrode of an oxide serving as a drain electrode and a source electrode. In addition to suppressing the penetration of chemicals during the etching process, improving the aperture ratio in the horizontal electric field type liquid crystal display device, and ensuring the connection stability at the terminal of the wiring, the horizontal electric field type with high product reliability And a method of manufacturing the same.

The liquid crystal display device according to the present invention is not only applicable to a general-purpose liquid crystal display device, but is particularly suitable for an in-vehicle display and a small personal television that are small but require a wide viewing angle.

[0012]

In order to achieve the above object, the present invention utilizes a difference in corrosion rate due to a difference in corrosion potential between different metals, and the structure of a liquid crystal display device according to the present invention is as follows. 1) to (6).

(1) A liquid crystal panel having an active matrix substrate in which a thin film transistor is formed on an inner surface of an insulating substrate, and a drive circuit for applying a drive signal voltage for lighting a pixel by driving the thin film transistor, wherein the thin film transistor A gate electrode, a gate insulating film, an A-Si layer as a semiconductor layer, an N (+) a-Si layer as a contact layer, and a transparent conductive layer formed in this order on the inner surface of the insulating substrate. +) A silicide layer was interposed between the a-Si layer and the transparent conductive layer.

(2) A gate wiring and a gate electrode, a common wiring and a common electrode, a pixel electrode, a semiconductor layer, a drain wiring and a source electrode, a drain electrode, a pixel electrode, and a gate insulating layer are formed on the inner surface of one of the insulating substrates. An active matrix substrate having a thin film transistor formed with a semiconductor layer, a contact layer, and a passivation layer,
A black matrix on the inner surface of the other insulating substrate, a color filter layer, a liquid crystal panel in which a liquid crystal composition is sealed in a facing gap between the color filter substrate on which the smooth layer is formed, and the gate wiring, the drain wiring, and the common wiring. A driving circuit for applying a driving signal voltage for lighting a pixel by driving the thin film transistor, wherein the gate wiring and the gate electrode and the common wiring and the common electrode are formed in the same layer with a laminated film of a transparent conductive film and a metal film. Formed.

(3) A gate wiring and a gate electrode, a common wiring and a common electrode, a pixel electrode, a semiconductor layer, a drain wiring and a source electrode, a drain electrode, a pixel electrode, and a gate insulating layer are formed on the inner surface of one insulating substrate. An active matrix substrate having a thin film transistor formed with a semiconductor layer, a contact layer, and a passivation layer,
A black matrix on the inner surface of the other insulating substrate, a color filter layer, a liquid crystal panel in which a liquid crystal composition is sealed in a facing gap between the color filter substrate on which the smooth layer is formed, and the gate wiring, the drain wiring, and the common wiring. A drive circuit for applying a drive signal voltage for lighting a pixel by driving the thin film transistor; wherein the gate wiring, the gate electrode, and the common wiring are formed of a laminated film of a transparent conductive film and a metal film; Was formed in a single layer of a transparent conductive film, and the gate wiring and the gate electrode and the common wiring and the common electrode were formed in the same layer.

The pixel electrodes in (4), (2) or (3) are formed of a transparent conductive film, and are alternately arranged in a comb shape with the common electrodes.

(5) The transparent conductive film in (1) to (4) is an amorphous transparent conductive film.

(6) In each of (2) to (5), a silicide layer was formed between the semiconductor layer and the transparent conductive layer.

Further, the method of manufacturing a liquid crystal display device according to the present invention is characterized in having the following constitutions (7) to (9).

(7) A gate wiring and a gate electrode, a common wiring and a common electrode, a drain wiring and a drain electrode, a source wiring and a source electrode are formed on one substrate constituting a liquid crystal panel of a liquid crystal display device by a transparent conductive film. A method for manufacturing a liquid crystal display device formed by patterning a laminated structure film having a metal film as a lower layer with an upper layer, wherein a gate wiring and a gate electrode, a common wiring and a common electrode are formed on the substrate, and then these are formed. A gate insulating film is formed so as to cover the amorphous silicon semiconductor layer, and an amorphous silicon semiconductor layer is formed on the drain wiring and the drain electrode and a required portion of the gate wiring and the gate electrode, and N (+) is formed on the amorphous silicon semiconductor layer as a contact layer. A) forming an amorphous silicon semiconductor layer and forming said N (+) amorphous silicon On the body layer, a large metal thin silicide formation tends to deposition, is etched to form a silicide layer, a transparent conductive film on said silicide layer,
Patterning to form drain and source electrodes,
Finally, a passivation layer as a protective film is formed to obtain an active matrix substrate.

(8) A gate wiring and a gate electrode, a common wiring, a drain wiring and a drain electrode, a source wiring and a source electrode, and a transparent conductive film as an upper layer on one substrate constituting a liquid crystal panel of a liquid crystal display device. A method of manufacturing a liquid crystal display device, wherein the substrate is formed by patterning a laminated structure film having a metal film as a lower layer, and the common electrode is formed by patterning the same transparent conductive film single layer as an upper layer of the laminated structure film. On top, gate wiring and gate electrode,
After forming a common wiring and a common electrode, a gate insulating film is formed to cover them, and an amorphous silicon semiconductor layer is formed on a required layer of the drain wiring and the drain electrode and the gate wiring and the gate electrode. Forming an N (+) amorphous silicon semiconductor layer as a contact layer on the amorphous silicon semiconductor layer,
A metal thin film having a high tendency to form silicide is formed on the N (+) amorphous silicon semiconductor layer, and a silicide layer is formed by etching. A transparent conductive film is formed on the silicide layer and patterned. A drain electrode and a source electrode are formed, and finally, a passivation layer as a protective film is formed to obtain an active matrix substrate.

The metal film constituting the lower layer of the laminated structure film in (9), (7) or (8) is any one of chromium, molybdenum, chromium-molybdenum alloy or a laminated film thereof, and the silicide layer is The metal layer to be formed was one of molybdenum, tungsten, titanium, chromium, tantalum, or the like, or an alloy thereof.

The reason why the above-described object of the present invention is achieved by each of the above structures will be described.

When forming an active matrix element on one substrate of a liquid crystal panel constituting a liquid crystal display device of a horizontal electric field type, a gate wiring and a gate electrode, a drain wiring and a drain electrode, a source electrode, a common wiring and a common electrode are formed. Form.

Of these wirings and electrodes, the gate wiring and the common wiring, which require low wiring resistance, are composed of a transparent conductive film made of an oxide on the upper layer and a laminated structure of two or more layers made of a metal film on the lower layer.

On the other hand, in the case of a small-sized display device, by forming the source wiring and the drain wiring, which do not need to be reduced so much, by a single layer of a transparent conductive film, a comb-shaped electrode is formed in a horizontal electric field type liquid crystal panel. In the vicinity of the source electrode to be configured, the light wrap around the inside of the transparent electrode can improve the light transmittance in the pixel.

Since the surfaces of the gate electrode, common electrode, and drain electrode constituting the terminal portion are all made of a transparent conductive film, the connection reliability of the wiring terminal portion with the printed circuit board or the drive circuit wiring due to oxidation of the terminal at the wiring terminal portion. Can be secured.
Thus, it is not necessary to increase the number of photolithography steps only for protecting terminals.

Further, the thin film transistor has a semiconductor layer on the gate electrode via an insulating layer. In order for the transparent conductive film made of oxide to contact the semiconductor layer with a single-layer film, it is effective to form a silicide that is stable against oxidation during the contact.

Since oxygen in the transparent conductive film made of oxide contacts silicide and does not contact the semiconductor layer, the contact resistance between the semiconductor layer and the source and drain electrodes does not increase.

Further, by forming the semiconductor layer and the silicide layer continuously along the drain wiring, the wiring resistance of the single layer of the transparent conductive film can be reduced as compared with the case of the single layer. Further, by improving the adhesion, disconnection due to penetration of a chemical solution during etching of the transparent conductive film can be prevented.

The manufacturing process can be simplified by patterning the gate wiring, the gate electrode, the common wiring, and the common electrode in the same layer as the transparent conductive film and the metal film at the same time. When the transparent conductive layer and the metal layer are processed in different steps, the number of steps increases. However, the common electrode forming the comb-shaped electrode in the pixel portion is formed only of the transparent conductive layer, and the gate wiring and the gate electrode and the common wiring (common bus line) are formed of a laminated structure film of the transparent conductive layer and the metal layer. With this configuration, the common electrode can be made transparent while ensuring low wiring resistance, and an improvement in light transmittance can be realized.

It should be noted that the present invention is not limited to the above configuration and the configuration of the embodiment described later, and various modifications can be made without departing from the technical idea of the present invention.

[0033]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 is a sectional view of a principal part for explaining a first embodiment of the liquid crystal display device according to the present invention. FIG. 2 is a plan view illustrating a configuration near one pixel of the liquid crystal display device according to the present invention. In the following description, for the sake of easy understanding, the main components are indicated with symbols indicating their functions, and the structure is described in the description of the manufacturing process.

Any one of chromium (Cr), molybdenum (Mo), and a chromium-molybdenum alloy (Cr-Mo) is formed as the metal film 2 on the glass substrate SUB1. In this embodiment, chromium (Cr) is used.

On this film, indium tin oxide ITO (In—Sn—O) or indium zinc oxide IZO (In—Zn—O) is continuously formed as a transparent conductive film 3. In this embodiment, IZO is used.

Next, the gate wiring 4 (GL) and the common wiring (CL) 5 are simultaneously processed by etching using the photosensitive resist formed on the transparent conductive film 3 in the photolithography step as a mask. In FIG. 1, the gate wiring 4 (GL) forms the gate electrode GT, and the common wiring (CT) 5 is connected to the common electrode CT.
The pixel electrode 2 connected to the source electrode 11 (SD2)
6 (PX) is formed of a single layer of the transparent electrode IZO.
Although not shown, the terminal portion of the gate wiring 4 (GL) is IZO
In a single layer.

This etching process is performed by dry etching when a crystalline transparent conductive film is used, and wet etching is used when an amorphous (amorphous) transparent conductive film is used. When an IZO film is used for the transparent conductive film 3,
Batch etching can be performed with the same etchant as the lower metal film 2.

A silicon nitride (SiN) film as a gate insulating layer 6 (GI), an a-Si layer 7 (AS) as a semiconductor layer 7 and phosphine-doped N (+) a-Si ( A film (hereinafter, referred to as n ⁺ a-Si) (N ⁺ AS) is continuously formed by a CVD method.

Next, in order to form the silicide layer 10 (SSD), molybdenum Mo, which is a silicide forming element,
At least one of chromium Cr, tungsten W, titanium Ti and the like is formed by a sputtering method. In this example, molybdenum was used.

During the sputtering of the silicide forming element, the metal film and the metal element combine with the Si element at the interface between the metal film (molybdenum) on the semiconductor film (a-Si film) 7 (AS) and the a-Si film 7. Then, a silicide layer 10 (SSD) is formed. Thereafter, when this metal film is entirely etched, the metal portion is removed by etching, and only the thin silicide layer SSD formed at the interface remains on the a-Si film 7 (AS).

Next, the a-Si island pattern 9 (A
SL). Dry etching using HCl gas is used for the etching.

Then, a polycrystalline (amorphous) IZO film is formed as the transparent conductive film 11 by a sputtering method.
Drain electrode 12 (SD1) in photolithography process
And a source electrode 13 (SD2). A wet etching method is used for this etching, and hydrobromic acid (HBr) or aqua regia is used as an etchant.

Since the source electrode 13 (SD2) needs to be processed with high dimensional accuracy as a comb-shaped electrode, HBr having a small amount of etching retreat is more suitable for the present invention.

The interface between the transparent conductive layer 11 (IZO) and the contact layer 8 (n ⁺ a-Si film (N ⁺ AS)) has a silicide layer 10 (SSD) against diffusion of oxygen from oxide.
Works as a blocking layer, so that the contact resistance does not increase.

The contact layer 8 (n ⁺ a-Si film (N ⁺ A
S)) A silicide layer 10 (S
SD), an n ⁺ a-Si film (N ⁺ AS)
The contact resistance of the contact layer 8 may be significantly reduced, and a large margin of the contact resistance may be secured. For this purpose, the material of the contact layer is changed to amorphous n ⁺ a-S
i-film 8 (N ⁺ AS) to microcrystalline silicon film (μc-S
It may be changed to i).

When the μc-Si film is used as a contact layer, its specific resistance is 10 ⁻² S / cm compared to amorphous Si (10 ² S / cm) added at the same phosphine concentration.
cm and its specific resistance is reduced by about four orders of magnitude. At this low contact resistance, the contact characteristics at the source and drain electrodes are low. Furthermore, even if oxygen diffuses from the transparent conductive film, no increase in contact characteristics that affects image quality is observed.

Finally, the passivation layer 14 (PA
As S), a SiN film is formed by a plasma CVD method.

FIGS. 3A and 3B are schematic diagrams for explaining the gate terminal portion and the common terminal portion in the present embodiment. FIG. 3A is a plan view of a main portion, and FIG. 3B is a view along the line AA in FIG. FIG.

The gate terminal GTM (and the common terminal CTM) are connected to the gate line GL (common line C).
L), and a gate insulating layer G is formed on a laminated structure film having a transparent conductive film IZO as an upper layer and a metal film Cr as a lower layer.
I and a protective film PAS. SUB2 indicates a color filter substrate.

A through hole 15 is formed in the gate insulating layer GI of the gate terminal GTM (common terminal CTM) and the protective film PAS to expose the gate line GL (common line CL). The gate terminal GTM (common terminal CTM) includes the gate insulating layer 6 (GI) and the passivation layer 14 serving as a protective film.
(PAS), when forming the through hole 15, both are etched at once.

For this etching, a dry etching method using SF ₆ gas is used. At the end of dry etching, the transparent conductive layer (IZO
Layer), but there is no plasma damage because the IZO layer is an oxide and is stable to an etching gas.

By forming the through-holes 15 so that the transparent conductive film IZO is present in all of the exposed portions of the terminal portions, the metal layer (the lower Cr layer) of the terminal portions is maintained even after plasma and through-hole formation. Since it is not exposed to air, stable terminal connection is possible.

FIGS. 4A and 4B are schematic views for explaining the drain terminal portion in the present embodiment. FIG. 4A is a plan view of a main part, and FIG.
3A is a cross-sectional view along the line BB in FIG. Since the drain terminal DTM is a single layer of a transparent conductive layer, the terminal portion is covered with a passivation layer PAS which is a protective film. Therefore, the passivation layer PAS only at the drain terminal DTM may be removed. The entire passivation layer PAS may be removed by etching. This example illustrates the latter.

Since the drain terminal is formed of IZO, the terminal is not exposed to air even after the plasma and the through hole are formed, so that a stable terminal connection is possible.

According to this embodiment, since the pixel electrode 26 (PX), which is a comb-tooth electrode connected to the source electrode, is formed of a transparent conductive film, the active matrix substrate (SUB1) constituting the in-plane switching mode liquid crystal panel is formed four times. In the photolithography process.

The active matrix substrate thus produced and a color filter substrate (SUB) produced separately.
2) was adhered, and a liquid crystal composition was sealed in the gap to form a liquid crystal panel, and the light transmittance was measured. As a result, as compared with a liquid crystal panel using an active matrix substrate in which both the pixel electrode and the common electrode are formed of a metal film, the light transmittance is improved by about 10% corresponding to the area of the pixel electrode PX in the pixel. Was.

According to this embodiment, the manufacturing process is simplified.
A bright liquid crystal display device having high light transmittance can be obtained.

FIG. 5 is a sectional view of a principal part for explaining a second embodiment of the liquid crystal display device according to the present invention. FIG. 6 is a plan view illustrating a configuration near one pixel of the liquid crystal display device according to the present invention. In the following description, similar to the first embodiment, the main components are shown in the drawings together with symbols indicating their functions for easy understanding.

First, a chromium film 2 (Cr) is formed as a metal film on the glass substrate SUB1, and the gate wiring 4 (GL / gate electrode GT) and the common wiring CL are processed by photoetching. Next, an ITO film is formed as the transparent conductive film 3, and the gate wiring 4 (GL /
The transparent conductive film ITO is processed so as to cover the surfaces of the gate electrode GT) and the common wiring 5 (CL) and to form a single layer at the common electrode 5 (CT) portion.

That is, in this embodiment, the gate wiring 4
(GL) constitutes the gate electrode GT, and the common wiring (C
L) 5 is a laminated structure film similar to the gate wiring 4 (GL) and the gate electrode GT, and the common electrode CT connected to the common wiring 5 (CL) is formed of a single ITO layer.

The pixel electrode 26 (PX) connected to the source electrode 11 (SD2) is formed as a single layer of the transparent electrode IZO. Although not shown, the terminal portion of the gate wiring 4 (GL) is formed of a single layer of IZO.

This etching process is performed by dry etching when a crystalline transparent conductive film is used, and wet etching when an amorphous (amorphous) transparent conductive film is used.

A silicon nitride (SiN) film as the gate insulating layer 6 (GI), an a-Si layer 7 (AS) as the semiconductor layer 7, and phosphine-doped N (+) a-Si ( A film (hereinafter, referred to as n ⁺ a-Si) (N ⁺ AS) is continuously formed by a CVD method.

Next, in order to form the silicide layer 10 (SSD), molybdenum Mo which is a silicide forming element,
At least one of chromium Cr, tungsten W, titanium Ti and the like is formed by a sputtering method. In this example, molybdenum was used.

The formation of the silicide layer 10 (SSD) is performed in the same manner as in the first embodiment, and the silicide layer 10 (SSD) is formed on the a-Si film 7 (AS).

Next, an a-Si island pattern 9 (ASL) is formed on the a-Si layer 7 (AS) by dry etching using HCl gas.

Then, a polycrystalline (amorphous) IZO film is formed as the transparent conductive film 11 by a sputtering method, and the drain electrode 12 (SD1) and the source electrode 13 (SD1) are etched by using hydrobromic acid (HBr) or aqua regia. SD2)
To form

Also in this configuration, the transparent conductive layer 11 (ITO)
The contact resistance increases due to the silicide layer 10 (SSD) acting as a blocking layer against the diffusion of oxygen from the oxide at the interface between the contact layer 8 and the contact layer 8 (n ⁺ a-Si film (N ⁺ AS)). Never do.

The contact layer 8 (n ⁺ a-Si film (N ⁺ A
S)) A silicide layer 10 (S
For SD), a microcrystalline silicon film (μc-Si) may be used instead of the n ⁺ a-Si film (N ⁺ AS). μc-Si
Amorphous Si (10 ² S / c) doped at the same phosphine concentration has the same specific resistance when the film is used as a contact layer.
m) and 10 ^-2 S / cm, and the specific resistance is about 4
Order of magnitude smaller. With this low contact resistance, the source electrode,
The contact characteristics at the drain electrode are low. Furthermore, even if oxygen diffuses from the transparent conductive film, no increase in contact characteristics that affects image quality is observed.

Finally, the passivation layer 14 (PA
As S), a SiN film is formed by a plasma CVD method.

According to the configuration of this embodiment, as a result, in the lateral electric field type comb-teeth electrode, both the common electrode CT and the pixel electrode PX can be made transparent electrodes. As a result, light is transmitted through the common electrode CT as well, which is increased by about 10% corresponding to the area of the common electrode occupying in the pixel as compared with the case where the pixel electrode PX and the common electrode CT are metal electrodes.

As described above, in this embodiment, by combining with the formation of the transparent conductive film of the pixel electrode, the light transmittance can be improved by a total of about 20% as compared with the metal comb electrode in the five photolithography steps. Is obtained. Further, the configuration of the terminal portion in the present embodiment is the same as that described with reference to FIGS.

According to this embodiment, the manufacturing process is simplified, and a liquid crystal display device having a high light transmittance and a high brightness can be obtained.

Next, a driving circuit, a driving method, and an entire configuration of the liquid crystal display device of the present invention will be described with reference to FIGS.

FIG. 7 is a conceptual diagram of a driving circuit of a liquid crystal display device according to the present invention, wherein CONT / PWS is a control circuit / power supply circuit, GDR is a gate electrode driving circuit (scanning electrode driving circuit), and DDR is a drain electrode driving circuit. A circuit (signal electrode drive circuit), CDR is a common electrode drive circuit (common electrode drive circuit), and PNL is a liquid crystal panel (effective display area). Incidentally, C _LC is the capacitance component of the liquid crystal, the C _S indicates a holding capacitance.

A thin film transistor TFT for switching each pixel of the liquid crystal panel PNL includes a gate electrode driving circuit G
It is selectively turned on / off by the DR, the drain electrode drive circuit DDR, and the common electrode drive circuit CDR. This on / off is controlled by the control circuit CONT.

FIG. 8 is an explanatory diagram of an example of a driving waveform of the liquid crystal display device according to the present invention. In the figure, the opposite voltage is VCH
And a VCL and a binary AC rectangular wave, and in synchronism therewith, the non-selection voltages of the scanning signals VG (i-1) and VG (i) are changed by the binary values of VCH and VCL every scanning period. The amplitude width of the counter voltage and the amplitude value of the non-selection voltage are the same.

The video signal voltage is a voltage obtained by subtracting 振幅 of the amplitude of the counter voltage from the voltage to be applied to the liquid crystal layer.

The counter voltage may be DC, but by converting it to AC, the maximum amplitude of the video signal voltage can be reduced, and a video signal drive circuit (signal-side driver) having a low withstand voltage can be used.

FIG. 9 is an exploded perspective view for explaining the overall structure of the liquid crystal display device according to the present invention.
A liquid crystal display module in which two substrates SUB1 and SUB2 are bonded to each other, a driving unit, a backlight, and a liquid crystal display module (hereinafter, referred to as an MDL) in which other components are integrated is described.

SHD is a shield case (also called a metal frame) made of a metal plate, WD is a display window, INS1
3 to 3 are insulating sheets, PCB1 to 3 are circuit boards constituting a driving means (PCB1 is a drain side circuit board (drain line driving circuit: circuit board for video signal line driving), PCB2 is a gate side circuit board (gate line driving circuit) : Scanning line drive circuit), PCB3 is an interface circuit board (control circuit board), JN1 to 3 are joiners for electrically connecting the circuit boards PCB1 to 3, TCP1 and TCP2 are tape carrier packages, PNL is a liquid crystal panel, GC
Is a rubber cushion, ILS is a light shielding spacer, PRS is a prism sheet, SPS is a diffusion sheet, GLB is a light guide plate,
RFS is a reflection sheet, MCA is a lower case (mold frame) formed by integral molding, MO is an opening of the MCA, LP is a fluorescent tube, LPC is a lamp cable, GB is a rubber bush supporting the fluorescent tube LP, BAT Denotes a double-sided adhesive tape, BL denotes a backlight composed of a fluorescent tube, a light guide plate and the like, and a liquid crystal display module MDL is assembled by stacking diffusion plate members in the arrangement shown in the figure.

The liquid crystal display module MDL has two kinds of storage / holding members of a lower case MCA and a shield case SHD, and includes insulating sheets INS1 to INS3 and circuit boards PCB1 to PCB1.
3. A metal shield case SHD in which a liquid crystal panel PNL is stored and fixed, and a lower case MCA in which a backlight BL including a fluorescent tube LP, a light guide plate GLB, a prism sheet PRS, and the like are stored are combined.

An integrated circuit chip for driving each pixel of the liquid crystal panel PNL is mounted on the drain side circuit board PCB1, and a control signal such as a reception of a video signal from an external host and a timing signal is mounted on the control circuit board PCB3. , And a timing converter TCON for processing the timing to generate a clock signal.

The clock signal generated by the timing converter is supplied to the integrated circuit chip mounted on the drain-side circuit board PCB1 via the clock signal line CLL laid on the interface circuit board PCB3 and the drain-side circuit board PCB1. .

The control circuit board PCB3 and the drain side circuit board PCB1 are multilayer wiring boards, and the clock signal line CLL is connected to the control circuit board PCB.
3 and the inner wiring of the drain-side circuit board PCB1.

The liquid crystal panel PNL, the drain-side circuit board PCB1, the gate-side circuit board PCB2 and the control circuit board PCB3 are formed of a tape carrier package T.
The circuit boards are connected by CP1 and TCP2, and the circuit boards are connected by joiners JN1, JN2, JN3. In addition, a configuration may be adopted in which each drive circuit is directly formed in a peripheral portion of one substrate (normally, the active matrix substrate SUB1) of the liquid crystal panel PNL.

A thin film transistor is formed by applying the structure and the manufacturing method of each embodiment of the present invention to the thin film transistor, various wirings and electrodes formed on the active matrix substrate constituting such a liquid crystal display device. The contact property and low resistance of the semiconductor layer and the transparent electrode of the oxide serving as the drain electrode and the source electrode are reduced, and the penetration of the chemical solution during the etching of the transparent electrode is suppressed. As a result, the connection stability at the terminal portion of the wiring can be secured, and a highly reliable liquid crystal display device can be obtained.

[0089]

As described above, according to the present invention,
By forming the gate wiring and the gate electrode, the common wiring and the common electrode or the common wiring into a laminated structure of a transparent conductive film and a metal film, and forming the source electrode and the pixel electrode connected to the source electrode and the drain wiring into a single transparent conductive layer,
The light transmittance of a liquid crystal display device with a high viewing angle can be improved, the reliability of the terminal portion can be improved, and the manufacturing process can be simplified to provide a liquid crystal display device with low manufacturing cost.

[Brief description of the drawings]

FIG. 1 is a sectional view of a principal part for explaining a first embodiment of a liquid crystal display device according to the present invention.

FIG. 2 is a plan view illustrating a configuration near one pixel of the liquid crystal display device according to the present invention.

FIG. 3 is a schematic diagram illustrating a gate terminal portion and a common terminal portion in the first embodiment of the liquid crystal display device according to the present invention.

FIG. 4 is a schematic diagram illustrating a drain terminal portion in the first embodiment of the liquid crystal display device according to the present invention.

FIG. 5 is a cross-sectional view illustrating a main part of a liquid crystal display device according to a second embodiment of the present invention.

FIG. 6 is a plan view illustrating a configuration near one pixel of the liquid crystal display device according to the present invention.

FIG. 7 is a conceptual diagram of a driving circuit of a liquid crystal display device according to the present invention.

FIG. 8 is an explanatory diagram of an example of a driving waveform of the liquid crystal display device according to the present invention.

FIG. 9 is an exploded perspective view illustrating the overall configuration of the liquid crystal display device according to the present invention.

[Explanation of symbols]

 Reference Signs List 1 one substrate (glass substrate) 2 metal wiring layer 3 transparent conductive layer 4 gate wiring / gate electrode 5 common wiring / common electrode 6 gate insulating layer 7 a-Si semiconductor layer 8 contact layer 9 a-Si island 10 silicide layer 11 Transparent conductive layer 12 Drain electrode 13 Source electrode 14 Passivation layer 15 Through hole 20 The other substrate (glass substrate) 21 Black matrix 22 Color filter 23 Overcoat layer 25 Drain wiring 26 Pixel electrode.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H092 GA14 JA26 JA29 JA33 JA35 JA38 JA39 JA42 JA44 JA46 JB13 JB23 JB27 JB32 JB33 JB51 JB57 JB63 JB69 KA05 KA07 MA05 MA14 MA15 MA16 MA18 MA19 MA20 MA27 MA33 MA35 MA37 NA27 NA25 NA25 NA29 PA05 PA08

Claims (9)

[Claims] 1. A liquid crystal display device comprising: a liquid crystal panel having an active matrix substrate in which a thin film transistor is formed on an inner surface of an insulating substrate; and a driving circuit for applying a driving signal voltage for lighting a pixel by driving the thin film transistor. The thin film transistor comprises a gate electrode, a gate insulating film, an A-Si layer as a semiconductor layer, an N (+) a-Si layer as a contact layer, and a transparent conductive layer formed in this order on the inner surface of the insulating substrate. And a silicide layer interposed between the N (+) a-Si layer and the transparent conductive layer. 2. A gate wiring and a gate electrode, a common wiring and a common electrode, a pixel electrode, a semiconductor layer, a drain wiring and a source electrode and a drain electrode, a pixel electrode, a gate insulating layer, and a semiconductor on an inner surface of one of the insulating substrates. An active matrix substrate having a thin film transistor on which a layer, a contact layer, and a passivation layer are formed; and a black matrix, a color filter layer, and a liquid crystal composition in a facing gap between the color filter substrate on which the smooth layer is formed on the inner surface of the other insulating substrate. And a driving circuit for applying a driving signal voltage for lighting a pixel by driving a thin film transistor to the gate wiring, the drain wiring, and the common wiring, and the common wiring and the gate wiring. And the common electrode is the same as the laminated film of the transparent conductive film and the metal film. A liquid crystal display device formed in a layer. 3. An insulated substrate having a gate wiring and a gate electrode, a common wiring and a common electrode, a pixel electrode, a semiconductor layer, a drain wiring and a source electrode and a drain electrode, a pixel electrode, a gate insulating layer, and a semiconductor on an inner surface thereof. An active matrix substrate having a thin film transistor on which a layer, a contact layer and a passivation layer are formed, a black matrix on the inner surface of the other insulating substrate, a color filter layer, and a liquid crystal composition in a facing gap between the color filter substrate on which a smooth layer is formed. And a driving circuit for applying a driving signal voltage for lighting a pixel by driving a thin film transistor to the gate wiring, the drain wiring, and the common wiring, and the common wiring and the gate wiring. Is formed of a laminated film of a transparent conductive film and a metal film, A liquid crystal display device, wherein a gate electrode is formed of a single layer of a transparent conductive film, and each of the gate wiring and the gate electrode and each of the common wiring and the common electrode are formed in the same layer. 4. The liquid crystal display device according to claim 2, wherein said pixel electrodes are formed of a transparent conductive film, and are alternately arranged in a comb shape with said common electrodes. 5. The liquid crystal display device according to claim 1, wherein said transparent conductive film is an amorphous transparent conductive film. 6. The liquid crystal display device according to claim 2, further comprising a silicide layer between said semiconductor layer and said transparent conductive layer. 7. A gate wiring and a gate electrode, a common wiring and a common electrode, a drain wiring and a drain electrode, on one substrate constituting a liquid crystal panel of a liquid crystal display device.
A method for manufacturing a liquid crystal display device, wherein a source wiring and a source electrode are formed by patterning a laminated structure film having a transparent conductive film as an upper layer and a metal film as a lower layer, wherein a gate wiring, a gate electrode, and a common wiring are formed on the substrate. Forming a gate insulating film covering the drain electrode and the common electrode, forming an amorphous silicon semiconductor layer on the drain wiring and the drain electrode, and a required portion of the gate wiring and the gate electrode, Forming an N (+) amorphous silicon semiconductor layer as a contact layer on the semiconductor layer; forming a metal thin film having a high tendency to form silicide on the N (+) amorphous silicon semiconductor layer; and etching to form a silicide layer Forming a transparent conductive film on the silicide layer, patterning and conducting A method for manufacturing a liquid crystal display device, comprising: forming a source electrode and a source electrode; and finally forming a passivation layer as a protective film to obtain an active matrix substrate. 8. A metal film having a gate wiring and a gate electrode, a common wiring, a drain wiring and a drain electrode, a source wiring and a source electrode, a transparent conductive film as an upper layer, and a metal film on one substrate constituting a liquid crystal panel of a liquid crystal display device. Is formed by patterning a laminated structure film having a lower layer, and the common electrode is formed by patterning the same transparent conductive film single layer as the upper layer of the laminated structure film, the method for manufacturing a liquid crystal display device, comprising: After forming a gate wiring and a gate electrode, a common wiring and a common electrode, a gate insulating film is formed so as to cover them, and an amorphous layer is formed on a required layer of the drain wiring and the drain electrode and the gate wiring and the gate electrode. A silicon semiconductor layer is formed, and N (+) amorphous is formed as a contact layer on the amorphous silicon semiconductor layer. Forming a silicon thin film on the N (+) amorphous silicon semiconductor layer, forming a silicide layer by etching, and forming a transparent conductive film on the silicide layer; A method for manufacturing a liquid crystal display device, comprising: forming a film and patterning to form a drain electrode and a source electrode; and finally forming a passivation layer as a protective film to obtain an active matrix substrate. 9. A metal film constituting a lower layer of the laminated structure film is any one of chromium, molybdenum, and chromium-molybdenum alloy or a laminated film thereof, and the metal layer forming the silicide layer is molybdenum, tungsten 9. The method for manufacturing a liquid crystal display device according to claim 7, wherein the material is one of titanium, chromium, tantalum and the like or an alloy thereof.