JP3317909B2 - Liquid crystal display - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a liquid crystal display device and a method of manufacturing the same, and more particularly, to a liquid crystal display device having a pixel electrode and a switching element on at least one of a pair of substrates facing each other. is there.

[0002]

2. Description of the Related Art A liquid crystal display device is widely used as a small display device. Here, a configuration of a conventional liquid crystal display device will be described with reference to FIG. FIG. 1 is a sectional view showing a configuration of a conventional liquid crystal display device. On a substrate 1 such as glass,
As shown in FIG. 1, a metal film, an insulating film, and the like are formed, and these films are subjected to a photolithography (PR) process and an etching process, and are patterned to form a gate electrode 11, a gate insulating layer 12, an amorphous silicon layer. 13, source electrode 14, drain electrode 15, pixel electrode 1
6, a transfer pad 17, a signal input terminal 18, and the like.

On the substrate 2 facing the substrate 1, a transparent conductive film 19 made of ITO or the like is used to apply a voltage to the liquid crystal.
When the liquid crystal display device is assembled, the transparent electrode 19 and the transfer pad are formed by forming the conductive adhesive layer 20 such as a silver paste as a transfer on the transfer pad 17 of the substrate. 17 are electrically connected.

Conventionally, a transfer pad 17 of a liquid crystal display device is formed of the same metal layer as a wiring or the like, and a transfer pad 17 is formed on the surface thereof.
By sputtering and patterning the TO, oxidation or the like of the surface of the metal wiring material is prevented, contact resistance with the transfer 20 made of silver paste formed thereon is reduced, and delay of an input signal is suppressed.

As another example of the liquid crystal display device shown in FIG. 1, as shown in FIG. 2, a pixel electrode 16 is formed on an insulating layer 21 and is electrically connected to a drain electrode 15 through a contact hole 22. There is also a liquid crystal display device having such a structure. In this structure, disconnection occurs at the edge of the contact hole 22 due to poor coverage of the pixel electrode 16. FIG. 2 is a sectional view showing the configuration of another conventional liquid crystal display device.

Further, as shown in FIG. 3, a wiring 25 formed so as to intersect the lower storage capacitor wiring 24 via the insulating film 21 is a stepped portion reflecting the shape of the storage capacitor wiring 24 and is abrupt. Since it is bent at an angle, there is a possibility that the wire will break there. FIG. 3 is a cross-sectional view showing a configuration of a wiring of a conventional liquid crystal display device.

Therefore, in the conventional liquid crystal display device, the edge portion of the contact hole 22 is formed to have an inclined angle, or the thickness of a metal layer formed on the insulating layer is increased to increase the insulation. The coverage characteristics of the film formed above the layer are improved, and disconnection at the step is prevented.

[0008]

However, in the liquid crystal display device having the structure as shown in FIG.
In order to form the surface ITO layer of No. 7, a PR step and an etching step are required after the step of forming the surface ITO layer. This has led to an increase in manufacturing costs.

In addition, in the liquid crystal display device having the structure as shown in FIG. 2, it is difficult to give an inclination angle to an edge portion due to the size of a contact hole formed in an insulating layer or the like. If it is difficult to increase the thickness of the metal layer formed on the upper part in the wiring structure shown in the above, the coverage characteristics of the metal layer formed on the edge part and the metal layer at the intersection of the wiring become poor, Disconnection or a reduction in the film thickness causes a problem in that the resistance of the wiring increases and the applied signal is delayed.

Accordingly, an object of the present invention is to provide a liquid crystal display device having a structure for suppressing contact resistance with a conductive adhesive at a transfer pad portion and a method of manufacturing the same in order to solve the above-mentioned problems. ,Also,
An object of the present invention is to provide a liquid crystal display device having a structure capable of improving coverage characteristics of a wiring layer in a contact hole portion or a step portion where wirings intersect and preventing disconnection, and a method for manufacturing the liquid crystal display device. .

[0011]

In order to achieve the above object, a liquid crystal display device according to the present invention (hereinafter referred to as a first invention) comprises a pair of substrates opposed to each other and each having an electrode, A liquid crystal sealed between the pair of substrates; a pixel electrode provided on at least one of the pair of substrates, for applying a voltage to the liquid crystal; a switching element for controlling the applied voltage; And a conductive adhesive layer for conducting the electrodes on the substrate, wherein the electrodes formed on the pair of substrates have conductive surfaces made of a polymer resin containing conductive particles. It is characterized by being covered with a conductive layer.

[0012] In the first invention, the electrode is formed by a conductive layer made of a polymer resin agent containing conductive particles.
Coated. The transfer pad at the lower end of the transfer, which is formed of a conductive paste and electrically connects between the substrates, also includes a metal electrode layer and an ITO as a part of the electrode.
And a polymer resin layer containing conductive particles. This prevents oxidation or the like of the transfer pad surface and suppresses the increase in resistance, thereby suppressing a delay of a signal voltage applied to the opposite-side transparent electrode via the transfer pad and the transfer. The polymer resin layer containing conductive particles such as ITO formed on the transfer pad portion of the liquid crystal display device can be selectively formed on the exposed surface of the metal electrode.

[0013] In a preferred method of manufacturing a liquid crystal display device according to the first invention, the substrate on which the electrodes are formed is immersed in an electrolytic solution containing the material for forming the conductive layer, and a voltage is applied to the substrate. The method is characterized by having a step of coating the electrode with a conductive layer by applying the voltage.

More specifically, the present manufacturing method comprises the steps of:
Immerse in a solution such as an electrolytic solution in which TO particles are dispersed or an electrolytic solution in which ITO and a polymer resin are dispersed, and connect a metal layer that is in conduction with the transfer pad to one pole of a DC power supply, A conductive electrode immersed in the solution is connected to the other side of the DC power supply, and a polymer resin layer containing ITO is formed on the transfer pad surface. According to the manufacturing method of the present invention, the polymer resin layer containing ITO can be formed only on the portion of the transfer pad where the metal layer is exposed. Steps and etching steps are not required.

Another liquid crystal display device according to the present invention (hereinafter, referred to as a second invention) comprises a pair of substrates facing each other, a liquid crystal sealed between the pair of substrates, and the pair of substrates. A pixel electrode for applying a voltage to the liquid crystal, and a switching element for controlling the applied voltage, wherein the pixel electrode is a switching element via a contact hole formed in an insulating layer. In the liquid crystal display device, the surface of the pixel electrode is coated with a conductive layer made of a polymer resin material containing conductive particles.

Still another liquid crystal display device according to the present invention (hereinafter, referred to as a third invention) comprises a pair of substrates facing each other, a liquid crystal sealed between the pair of substrates, and the pair of substrates. In a liquid crystal display device provided on at least one of the substrates and including a pixel electrode for applying a voltage to the liquid crystal and a switching element for controlling the applied voltage, the connection wiring formed on the substrate is The surface is coated with a conductive layer made of a polymer resin agent containing conductive particles.

The liquid crystal display device according to the second and third inventions is a liquid crystal display device having a wiring structure having a specified structure,
To prevent disconnection at the edge of the contact hole,
The polymer resin layer containing the conductive particles, by electrodeposition, electrolysis, plating, etc., to precipitate the substance present in the solution,
By depositing on the surface of the substrate, a uniform film is formed also at the edge portion of the contact hole and the portion where the wirings cross each other and have a step. As a result, a liquid crystal display device capable of improving the coverage characteristics of the wiring layer and performing good display without wiring defects such as disconnection is realized. According to the second and third aspects of the present invention, a structure in which an electrode for applying a voltage to a pixel electrode is conductive through a contact hole formed in an insulating layer, a wiring and other electrode layers are formed by an insulating layer A liquid crystal display device having a structure in which electrical continuity is provided through a contact hole formed in a liquid crystal display device, and a structure in which wirings and electrodes, electrodes and wirings and electrodes intersect with an insulating layer interposed therebetween. Applicable.

According to a second aspect of the present invention, there is provided a method of manufacturing a liquid crystal display device, wherein the substrate on which the pixel electrode is formed is immersed in an electrolytic solution containing the material for forming the conductive layer. Is applied to cover the pixel electrode with a conductive layer.

According to a third aspect of the invention, there is provided a method of manufacturing a liquid crystal display device, the method comprising immersing a substrate on which wirings are formed in an electrolytic solution containing a material for forming the conductive layer, and applying a voltage to the substrate. The method is characterized in that a step of covering the wiring with a conductive layer by applying the voltage is provided.

[0020]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. Embodiment 1 of the liquid crystal display device This embodiment is an example of the embodiment of the liquid crystal display device according to the present invention, and FIG. 4 is a schematic cross-sectional view showing the configuration of the liquid crystal display device of this embodiment. is there. A gate electrode 11 is formed by forming a conductive film such as a metal formed on the substrate 1 and performing a PR process and an etching process.
Next, a gate insulating film 12 and a semiconductor layer 13 are formed by forming a laminated film of an insulating layer such as SiN and a semiconductor layer such as amorphous silicon, and performing a PR process and an etching process. Further, a conductive film is formed on the gate insulating film 12 and the semiconductor layer 13 and subjected to a PR process and an etching process, so that the source electrode 14 and the drain electrode 15 are formed.
To form a thin film transistor (TFT) as a switching element.

On this substrate 1, transfer pads 17 and signal input terminals 18 are formed of the same metal layer as the pixel electrode 16, the gate electrode 12, or the drain electrode 15. In the case of a transmissive liquid crystal display device, the pixel electrode 16 is formed of a transparent conductive film such as ITO. In the case of a reflective liquid crystal display device,
It is formed of a metal thin film that reflects light such as aluminum. Each of the signal input terminals 18 is for inputting a signal to the gate electrode 12, the source electrode 14, or the transfer pad 17 to drive the switching element.

The substrate 2 facing the substrate 1 has an IT
A transparent electrode 19 such as O is formed, and is electrically connected to a transfer pad 17 formed on the substrate 1 by a transfer 20 made of a conductive adhesive, and a voltage is applied from the signal input terminal 18 to the transparent electrode 19. Can be applied.

On the surface of the transfer pad 17, I
A conductive polymer resin layer 30 containing TO is formed. In the case of a transmission type liquid crystal display device, the polymer resin layer 30
In most cases, it is formed of the same film as the pixel electrode 16 such as ITO.

In the case where ITO is not used for electrodes or wirings as in a reflection type liquid crystal display device, it is necessary to newly add a forming step of forming a conductive layer on the surface of the transfer pad. In this case, according to the conventional method, an ITO layer is formed by performing film formation, a PR process, and an etching process. However, adding such a patterning process leads to an increase in manufacturing cost. Then, the substrate 1 is immersed in a solution containing a polymer resin such as ITO and PVA, and a DC voltage is applied between the substrate 1 and a conductor immersed in the solution, whereby the substance such as ITO present in the solution is present. Is used only in the exposed portion of the transfer pad. Therefore, according to the present invention, it is not necessary to perform a PR process for performing surface patterning.

According to the present invention, as the switching element,
It is also possible to use an MIM element or the like instead of the thin film transistor. Further, the substrate 1 is not limited to a transparent material such as glass, but may be an opaque substrate such as a silicon wafer.

Embodiment 2 of the liquid crystal display device This embodiment is an example of the embodiment of the liquid crystal display device according to the second invention, and FIG. 5A shows the liquid crystal display device of this embodiment. It is sectional drawing which shows a structure. As in the first embodiment, on the substrate 1, as shown in FIG. 5A, a gate electrode 11, a gate insulating film 12, a semiconductor layer 13, a source electrode 14, a drain electrode 15, and a transfer pad 17 are provided. , A signal input terminal 18 and an insulating layer 21 are formed on these elements. In the insulating layer 21,
The contact hole 22 is formed, and the pixel electrode 16 is formed on the contact hole 22.

As a method for manufacturing the liquid crystal display device of this embodiment, there is a method in which a substance existing in a solution is formed as a film in a contact hole portion by an electrodeposition method, an electrolytic method, a plating method, or the like. For example, the substrate 1 is immersed in a solution in which a conductive substance such as ITO or a metal exists, and
Is used as an anode, and when a direct current is passed between the anode and the cathode, a conductive layer 31 of ITO or a metal in the solution is formed as a uniform film on the surface of the pixel electrode 16, so that an edge portion of the contact hole is formed. Can improve the coverage characteristics and prevent disconnection and the like, so that good display can be performed.

Furthermore, as shown in FIG. 5B, the gate electrode 11 may be disconnected at the edge of the contact hole where the pixel electrode 16 may be disconnected or actually disconnected.
Is turned on, the source electrode 14 is connected to the anode, and the above-described manufacturing method is applied. Then, the conductive layer 3 made of ITO or metal in the solution is formed on the exposed portion of the drain electrode 15.
1 is formed so as to fill the inside of the contact hole, so that the drain electrode 15 is in contact with the pixel electrode 16 on the insulating layer and the disconnected film can be connected to prevent pixel defects and the like. be able to.

Third Embodiment of the Liquid Crystal Display Device The third embodiment is an example of the embodiment of the liquid crystal display device according to the third invention, and FIG. 6 shows the configuration of the liquid crystal display device of the present embodiment. It is sectional drawing. As in the first and second embodiments, a switching element such as a thin film transistor 26 and a wiring 24 are formed on the substrate 1 as shown in FIG. The wiring 25 is formed so as to intersect the storage capacitor wiring 24 with the upper insulating layer 21 interposed therebetween. The substrate 1 is immersed in an electrolytic solution in which a conductive substance such as ITO or a metal is present, and a uniform conductive layer is formed on the surface of the wiring 25 by passing a direct current between the wiring 25 and the cathode. It is formed. Therefore, the coverage of the step portion is improved, and disconnection of the wiring can be prevented.

Embodiment 1 of the Method for Manufacturing a Liquid Crystal Display Device This embodiment is an example of an embodiment of a method for manufacturing a liquid crystal display device according to the present invention, and FIGS. It is sectional drawing which shows the structure of the board | substrate for every process at the time of manufacturing a liquid crystal display device according to the embodiment. First, as shown in FIG. 7A, chromium (C
A metal layer such as r) is formed by sputtering, a resist is applied to the metal layer, and exposure and development are performed to form a gate electrode, a transfer pad, and a signal input terminal pattern. Further, using the patterned resist layer as a mask, the Cr film is etched to form the gate electrode 11, the transfer pad 17, and the signal input terminal 18.

Next, as shown in FIG. 7B, a laminated film of a silicon nitride film and an amorphous silicon layer is formed by a CVD method or the like. By subjecting this laminated film to a PR process and an etching process, the gate insulating film 1 is formed.
2, and an island pattern of the amorphous silicon layer 13 is formed.

Next, a metal layer of Cr or the like is formed by sputtering, and the film is subjected to a PR process and an etching process, thereby forming the source electrode 14 and the drain electrode 15 as shown in FIG. Formed into a switching element.

Further, an insulating layer 21 such as a silicon nitride film or a silicon oxide film is formed on the electrodes and the like by a CVD method or the like, and this film is subjected to a PR process and an etching process to obtain a structure shown in FIG. 2), a contact hole 22 is formed, and then a pixel electrode 16 is formed.

The substrate 1 on which the switching elements and the like are formed as described above is subjected to the following processing using a conductive film coating apparatus as shown in FIG. This conductive film coating apparatus is connected to a tank 40 containing an electrolytic solution containing particulate ITO 42, which is formed into micelles with a surfactant 41 or the like, an electrode 51 immersed in the electrolytic solution, and an electrode 51. DC power supply 52 is provided. For example, the substrate 1 is immersed in an electrolytic solution containing ITO in the form of micelles formed by the surfactant 41 or the like. The conductive electrode 51 immersed in the electrolytic solution is connected to the cathode side of the DC power supply 52, the metal layer electrically connected to the transfer pad 17 is connected to the anode side, and a DC voltage is applied. At this time, on the transfer pad 17 immersed in the electrolytic solution,
ITO 42 in the electrolytic solution is deposited to form a layer 30 containing ITO for protecting the surface of the transfer pad, as shown in FIG.

Next, as shown in FIG. 7F, a conductive layer 31 is formed on the pixel electrode 16. Subsequently, FIG.
As shown in (g), the contact hole 22 is filled by performing a PR process and an etching process.

Embodiment 2 of the manufacturing method of the liquid crystal display device This embodiment is another example of the embodiment of the manufacturing method of the liquid crystal display device according to the present invention, and FIG. FIG. 3 is a schematic cross-sectional view illustrating a configuration of a conductive film coating device used when manufacturing a display device. As in the first embodiment, as shown in FIGS.
Gate electrode 11, transfer pad 1
7, the signal input terminal 18 is formed, and the gate insulating film 12,
Then, an island pattern of the amorphous silicon layer 13 is formed, and a source electrode 14 and a drain electrode 15 are formed to form a switching element. Further, a contact hole 22 is formed, and then a pixel electrode 16 is formed.

Next, the substrate 1 on which the switching elements, the pixel electrodes, etc. are formed is immersed in the conductive layer coating apparatus shown in FIG. 9 and subjected to the following processing. This conductive film coating apparatus is composed of a particulate ITO formed into micelles by a surfactant 41 or the like.
A tank 40 containing an electrolytic solution containing a metal 43 such as 42 or silver; an electrode 51 immersed in the electrolytic solution;
Is provided with a DC power supply 52 connected to the power supply. When the conductive electrode 51 immersed in the electrolytic solution is connected to the cathode side of the DC power supply 52, and the source electrode 14 is connected to the anode side of the DC power supply 52 with the gate electrode turned on, FIG. As shown in the figure, the surface of the pixel electrode 16
O42 or conductive layer 31 made of metal 43 such as silver
Is formed. Thereby, the edge portion of the contact hole of the pixel electrode 16 is coated with the conductive layer, and the coverage characteristics can be improved.

Third Embodiment of the Method of Manufacturing a Liquid Crystal Display The third embodiment is still another example of the embodiment of the method of manufacturing a liquid crystal display according to the present invention. 3) is a cross-sectional view showing the configuration of the substrate for each step when manufacturing the liquid crystal display device according to the embodiment. First, a metal layer such as Cr is formed on the surface of the substrate 1 such as glass by sputtering, a resist is applied to the metal layer, and an exposure and development step is performed to form a gate wiring and a gate electrode pattern. Further, using the patterned resist layer as a mask, the Cr film is etched to form the gate wiring 27 and the gate electrode 11 as shown in FIG.

Next, a gate insulating layer 12 and an amorphous silicon layer are formed by a silicon nitride film, a silicon oxide film or the like by using the CVD method, and the TFT island 28 is formed as shown in FIG. Form.

Next, as shown in FIG. 10C, a Cr layer 29 is formed by sputtering.

The substrate 1 formed as described above is used in FIG.
Was immersed in the conductive film coating apparatus shown in (1), and the following treatment was applied. The conductive film coating apparatus is filled with an electrolytic solution in which ITO 42 is present. The conductive electrode 51 immersed in the electrolytic solution is connected to the cathode side of the DC power supply 52, and the Cr layer 29 is connected to the DC power supply 52. When connected to the anode side of FIG.
As shown in (d), a conductive layer 31 made of ITO 42 in the electrolytic solution can be formed on the surface of the Cr layer 29. Thereby, the lower gate wiring 2 of the Cr layer 29 is formed.
7 and a step portion formed by the TFT island 28 can be coated with a conductive layer to improve coverage characteristics.

The substrate 1 formed by the method shown in the first to third embodiments of the method for manufacturing a liquid crystal display device is overlapped with the substrate 2 on which the transparent electrode 19 is formed.
The liquid crystal display device according to the present invention can be manufactured.

[0043]

According to the structure of the liquid crystal display device of the present invention,
Good by preventing an increase in contact resistance at the transfer pad at the lower end of the conductive adhesive layer and preventing disconnection of the metal film at the contact hole portion, or at the area where the wiring or electrode crosses and forms a step. A liquid crystal display device capable of performing various displays is realized. The method for manufacturing a liquid crystal display device according to the present invention realizes a preferable method for manufacturing the liquid crystal display device according to the present invention.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a configuration of a conventional liquid crystal display device.

FIG. 2 is a cross-sectional view illustrating a configuration of another conventional liquid crystal display device.

FIG. 3 is a cross-sectional view showing a configuration of still another conventional liquid crystal display device.

FIG. 4 is a schematic cross-sectional view illustrating a configuration of a liquid crystal display device according to a first embodiment.

FIGS. 5A and 5B are schematic cross-sectional views each showing a configuration of a liquid crystal display device according to a second embodiment.

FIG. 6 is a schematic cross-sectional view illustrating a configuration of a liquid crystal display device according to a third embodiment.

FIGS. 7A to 7G are cross-sectional views each showing a configuration of a substrate in each step when manufacturing a liquid crystal display device according to the method of the first embodiment.

FIG. 8 is a cross-sectional view illustrating a configuration of a conductive layer coating device.

FIG. 9 is a cross-sectional view illustrating a configuration of another conductive layer coating device.

FIGS. 10A to 10D are cross-sectional views each showing a configuration of a substrate for each step when manufacturing a liquid crystal display device according to the method of Embodiment 3. FIGS.

[Explanation of symbols]

 Reference Signs List 1 substrate 2 transparent substrate 3 liquid crystal 11 gate electrode 12 gate insulating layer 13 amorphous silicon layer 14 source electrode 15 drain electrode 16 pixel electrode 17 transfer pad 18 signal input terminal 19 transparent electrode 20 conductive adhesive 21 insulating layer 22 contact hole 24 Storage capacitor wiring 25 Wiring 26 Thin film transistor 27 Gate wiring 28 TFT island 29 Cr layer 30 Conductive material layer 31 Conductive material layer 41 Surfactant 42 ITO 43 Metal particle 51 Electrode 52 DC power supply

Continuation of the front page (56) References JP-A-10-301129 (JP, A) JP-A-64-78228 (JP, A) JP-A-62-159125 (JP, A) Jpn. , U)

Claims (1)

(57) [Claims] A pair of substrates opposed to each other and each having an electrode; a liquid crystal sealed between the pair of substrates;
A pixel electrode provided on at least one of the pair of substrates, for applying a voltage to the liquid crystal, a switching element for controlling the applied voltage, and a conductive adhesive for conducting the electrodes on the pair of substrates. And a metal layer provided for connection at the lower end of the conductive adhesive layer.
The liquid crystal display device in which the surface of the head is a conductive layer made of a polymer resin material containing conductive particles, characterized in that it is coated.