JPH07168208A - Active matrix system liquid crystal display - Google Patents

Abstract

PURPOSE:To obtain a liquid crystal display which is free from unequal display generated by a difference in voltages by distances from input electrodes and unequal display by a difference in capacitances between respective wiring electrodes and has excellent display quality. CONSTITUTION:Plural pixel electrodes 10 and plural wiring electrodes 5 connected to plural switching elements 12 for driving these pixel electrodes on a substrate are connected to input electrodes 11 to which driving signals are supplied via coupling capacitances. The values of the respective coupling capacitances of the active matrix type liquid crystal display are nearly the same values.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of an active matrix type liquid crystal display, and more particularly to an active matrix type liquid crystal display having a thin film diode element as a liquid crystal switching element.

[0002]

2. Description of the Related Art Thin film diode (Thin Film)
In an active matrix type liquid crystal display device having an element, a signal input from the input electrode passes through the wiring electrode and passes through the element.
Generally, it has a structure for applying to the pixel electrode.

According to this structure, a difference in resistance between the wiring electrodes causes a voltage difference between a pixel near the input electrode and a pixel far from the input electrode.
This may cause uneven display on the liquid crystal display.

Therefore, for example, Japanese Patent Laid-Open No. 2-302734.
As described in Japanese Patent Laid-Open Publication No. 2003-242242, a configuration has been proposed in which a coupling capacitance is provided between an input electrode and a wiring electrode.

That is, a dielectric film for forming an element is formed at the same time including a wiring electrode, then an input electrode is formed, and the input electrode, the coupling capacitance and the wiring electrode are electrically arranged in series.

As a result, display unevenness due to the distance from the input electrode due to the difference in wiring resistance of the wiring electrodes is improved.

[0007]

However, in the active matrix liquid crystal display, the number of wiring electrodes cannot be one, and a plurality of wiring electrodes are present.

The input electrode for supplying the drive signal to the wiring electrode is limited to the minimum connection pitch dimension of the anisotropic conductive film for external connection, and has the same dimension as the wiring electrode pitch. However, the areas of the wiring electrode and the input electrode are rarely the same.

As a result, the coupling capacitance obtained by the means described in the above publication changes for each wiring electrode.

Therefore, even if the display unevenness in one wiring electrode is eliminated, the display unevenness between the wiring electrodes appears, which is a fatal drawback for use as an active matrix type liquid crystal display. ing.

An object of the present invention is to provide a high quality active matrix type liquid crystal display body by eliminating display unevenness between wiring electrodes.

[0012]

In order to achieve this object, the active matrix type liquid crystal display of the present invention adopts the constitution described below.

The active matrix type liquid crystal display of the present invention is driven through a plurality of pixel electrodes provided on a substrate, a plurality of wiring electrodes connected to a plurality of switching elements for driving the pixel electrodes, and a coupling capacitance. An input electrode for supplying a signal to the switching element is provided, and the coupling capacitances are characterized in that the respective coupling capacitances have substantially the same value.

[0014]

In the active matrix type liquid crystal display of the present invention, a slit or a dummy region is provided in order to make the value of the coupling capacitance provided between the input electrode and the wiring electrode uniform.

As a result, the voltage difference due to the distance from the input electrode can be eliminated, and the display unevenness is eliminated.

As a result, it is possible to suppress the difference in coupling capacitance between the wiring electrodes, and it is possible to realize a high-quality active matrix type liquid crystal display without display unevenness over the entire screen.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The structure of an active matrix type liquid crystal display in an embodiment of the present invention will be described below with reference to the drawings.

First, a first embodiment of the present invention will be described. FIG. 5 is a plan view showing the structure of the TFD element according to the first embodiment of the present invention.

The common electrode 4, the wiring electrode 5, and the lining electrode 6 of the input electrode are provided by tantalum (Ta) of the first metal which constitutes the lower layer electrode of the TFD element.

Then, a slit 7 which is a region where tantalum of the first metal is not formed is provided at a position where the wiring electrode 5a and the wiring electrode 5b have substantially the same area.

Here, the wiring electrode 5 refers to a region of the wiring electrode 5 up to the slit, excluding the common electrode 4. The wiring electrode 5a and the wiring electrode 5b are commonly connected by the common electrode 4 and serve as an electrode at the time of anodizing treatment, and a dielectric film is provided on the surface of the wiring electrode 5.

A pixel electrode 10 for display is provided by using indium tin oxide (ITO) as a second metal which constitutes the upper metal layer of the TFD element.

The pattern of the pixel electrode 10 made of ITO is
The input electrode 11 is formed by connecting the wiring electrode 5 separated by the slit 7 and the lining electrode 6 of the input electrode, which is also formed on the wiring electrode 5 excluding the TFD element 12.

The coupling capacitance is IT which is the first electrode.
O, the dielectric film, and the second electrode of the coupling capacitance, and also tantalum that is the first metal of the TFD element, form the coupling capacitance.

The dielectric film obtained by the anodic oxidation treatment is extremely uniform in thickness and quality. Therefore, if the area of the wiring electrode 5a corresponding to the second electrode of the coupling capacitance and the area of the wiring electrode 5b are made constant, the value of the coupling capacitance will be different even if the area of the input electrode 11 corresponding to the first electrode of the coupling capacitance is different. Will be the same.

After forming the dielectric film, the common electrode 4 is cut at the boundary between the common electrode 4 and the wiring electrode 5, and then the TFD element 12 is driven by supplying power from the side of the backing electrode 6 of the input electrode. The present invention is constant regardless of the distance from the input electrode and the difference between the wiring electrodes, and exhibits a characteristic without display unevenness.

Next, a manufacturing method for obtaining the structure shown in FIG. 5 will be described with reference to FIGS.

First, as shown in FIG. 1, tantalum (Ta) as a first metal 2 is formed on a transparent and insulating substrate 1.
To a thickness of 200 nm.

This Ta is formed, for example, at a substrate temperature of approximately 250 to 350 ° C. and a total pressure of 1 to 3 × 10 −3 torr.
It is formed by the sputtering method under the conditions of.

After that, a resist 3 made of a positive type photoresist having a thickness of about 1 μm is formed by a spin coating method, exposed and developed, and the resist 3 is patterned.

As shown in the plan view of FIG. 2, the planar pattern shape of the resist 3 which has been exposed and developed is the common electrode 4 as shown in FIG.
The plurality of wiring electrodes 5 connected with each other are provided with slits 7 at positions where all wiring electrodes 5 have the same area.

Since the area of the wiring electrode 5 controlled by the slit 7 acts as a coupling capacitance, the line width dimension is preferably as wide as possible in order to increase the capacitance ratio with the TFD element.

After that, the first metal 2 is etched by the reactive ion etching (hereinafter referred to as RIE) method.

In the etching treatment by the RIE method used here, the flow rate of carbon tetrafluoride (CF4) as an etching gas is mixed in the range of 200 to 240 sccm, and the flow rate of oxygen (O2) is mixed in the range of 10 to 40 sccm, and 4 to 12 × 10 −2 torr is mixed.
Under the pressure of r, the power is 0.5 W / cm 2.

Then, the resist 3 is peeled off, and as shown in FIG. 3, the first metal 2 is subjected to a chemical conversion treatment in a 0.01 to 0.1 wt% citric acid bath to form a dielectric film made of a tantalum oxide film. The body film 8 is formed.

The dielectric film 8 is formed only on the surface of the wiring electrode 5 connected by the common electrode 4, and the dielectric film 8 is not formed on the backing electrode 6 of the input electrode separated by the slit 7.

Next, as shown in FIG. 4, the second metal 9
Indium tin oxide (ITO) that doubles as a pixel electrode
Is formed with a thickness of 200 nm.

The formation of this ITO is carried out at a substrate temperature of 150 ° C. or lower using a mixed gas of Ar gas and oxygen at a total pressure of 2 to 8 ×.
10-3 torr, oxygen partial pressure 2-3 × 10 −5 torr
Is formed by a reactive sputtering method.

After that, a resist made of a positive type photoresist having a thickness of about 1 μm is formed by a coating method, and exposed and developed to pattern the resist.

As shown in FIG. 5, the planar pattern shape of the resist subjected to this exposure and development treatment is, as shown in FIG.
A second metal pattern forming an upper electrode of the element 12,
It is composed of a pattern on the wiring electrode 5 and an input electrode 11 connecting the backing electrode 6 of the input electrode which is separated from the wiring electrode 5.

This resist was heat-treated at a temperature of 100 to 170 ° C., and then hydrochloric acid was used as an etching solution for ITO.
The second metal 9 consisting of is etched.

TFD formed by such processing steps
The substrate provided with the element, the process of manufacturing a normal liquid crystal display, the alignment film coating process, the alignment treatment process by rubbing is performed, further bonding process with the counter substrate and the same treatment, After the injection process and the liquid crystal injection port sealing process, the common electrode is cut to complete the liquid crystal display.

It is not necessary to form tantalum in the region where the dielectric film 8 is not formed on the surface by the chemical conversion treatment, but I
As a lining electrode 6 of the input electrode 11 made of a TO film, it contributes to the reduction of disconnection defects of the input electrode 11, and in the region where the dielectric film is formed by the chemical conversion treatment, every wiring electrode 5 functions as a capacitor having the same capacitance, which is excellent. A liquid crystal display with high image quality can be obtained.

Next, a second embodiment of the present invention will be described with reference to FIG. FIG. 7 shows T in the second embodiment of the present invention.
It is a top view which shows the structure of an FD element.

The Ta pattern, which is the first metal constituting the lower layer metal of the TFD element, is composed of the common electrode 4 and the wiring electrode 5 as in the first embodiment. However, the slit for separating the Ta pattern of the first embodiment is not provided, and the dielectric film is provided over the entire pattern of the first metal.

The pattern shape of ITO, which is the second metal 9 composing the upper layer metal of the TFD element 12, is similar to that of the first embodiment, except for the pixel electrode 10 and the wiring electrode 5 excluding the TFD element 12 and the input electrode. 11 and above.

The ITO pattern has a slit 7 at a position where the area of the input electrode 11 is constant.

The coupling capacitance is IT which is the first electrode.
O, the dielectric film, and the second electrode of the coupling capacitance, and moreover, the coupling capacitance is composed of tantalum which is the first metal of the TFD element.

Next, a manufacturing method for obtaining the structure shown in FIG. 7 will be described with reference to FIGS. 6 to 7.

By a method similar to that of the first embodiment described with reference to FIGS. 1 to 5, a Ta film which is the first metal 2 is formed, and then patterning is performed.

In the first embodiment, a slit is provided in a part of the Ta pattern wiring electrode 5 to separate the wiring electrode 5, but in the second embodiment, as shown in FIG. The metal 2 is formed in a continuous pattern, the chemical conversion treatment is performed on the entire first metal 2, and a dielectric film is formed on the entire surface.

Thereafter, the second condition is applied under the same conditions as in the first embodiment.
An ITO film is formed as the metal 9 and a resist pattern is formed on the ITO film.

The resist pattern is, as shown in FIG.
The slit 7 is provided at a position where the area of the input electrode 11 is constant.

In the second embodiment of the present invention, since the coupling capacitance is controlled only in the area of the input electrode 11, the ratio with the capacitance of the TFD element is set to be large as in the first embodiment, and therefore, as much as possible. The line width dimension of the input electrode 11 is preferably wide.

Further, the wiring electrode 5 separated by the slit
The second metal 9 made of ITO on the side can reduce the wiring resistance and reduce disconnection defects, as in the first embodiment.

After that, the liquid crystal display is formed by performing the same processing steps as those described in the first embodiment.

Next, a third embodiment of the present invention will be described with reference to FIG. With the same structure as the first embodiment described with reference to FIGS. 1 to 5, adjustment of the area difference of the wiring electrodes 5 and TF are performed.
In order to increase the capacitance ratio with the D element 12, as shown in FIG. 8, power is supplied from one input electrode 11 of the pixel electrode 10 connected to the wiring electrode 5 via the TFD element 12.

Then, the dummy region 13 is provided in the wiring electrode opposite to the input electrode 11. Then, the line width dimension of the dummy region 13 is made thick and a coupling capacitance is provided in the dummy region 13. The subsequent manufacturing method may be the same as the first embodiment, and a liquid crystal display can be formed.

Next, a fourth embodiment of the present invention will be described with reference to FIG. When the line width of the wiring electrode 5 is sufficiently thick and the possibility of disconnection is low, a structure similar to that of the second embodiment described with reference to FIGS. 6 and 7 is adopted, and as shown in FIG. The ITO pattern, which is the second metal, is provided only on the input electrode portion 11.

With the structure as shown in FIG. 9, the formation of the ITO pattern on the wiring electrode 5 can be omitted, there is no need for a complicated pattern, and the precision of the pattern superposition can be kept to a sufficient degree so that the liquid crystal can be formed. It is possible to create a display body.

FIG. 10 is a plan view showing an example in which a chip-on-glass (COG) mounting structure is applied to the active matrix type liquid crystal display of the present invention.

When the input electrode 11 and the terminal of the semiconductor chip that drives the liquid crystal display are directly connected using the COG mounting structure, as shown in FIG. 10, the position of the connection portion 14 of the input electrode 11 is changed. Needs to be aligned with the positions of the terminals of the semiconductor chip, and wiring is often concentrated at the mounting position.

At this time, the area of each wiring electrode 5, which serves as the second electrode of the coupling capacitance, is different.

Therefore, in order to obtain the same capacitance value, the first
The structures of the first to fourth embodiments may be adopted. As a result, it becomes possible to obtain a compact and highly reliable active matrix liquid crystal display.

[0065]

As is clear from the above description, the active matrix type liquid crystal display of the present invention is caused by the display unevenness caused by the voltage difference due to the distance from the input electrode and the difference in the coupling capacitance between the wiring electrodes. No display unevenness occurs. Therefore, it is possible to provide a liquid crystal display body having very good display quality.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an active matrix type liquid crystal display according to an embodiment of the present invention.

FIG. 2 is a plan view showing an active matrix type liquid crystal display according to an embodiment of the present invention.

FIG. 3 is a cross-sectional view showing an active matrix type liquid crystal display body in an example of the present invention.

FIG. 4 is a cross-sectional view showing an active matrix type liquid crystal display body in an example of the present invention.

FIG. 5 is a plan view showing an active matrix type liquid crystal display according to an embodiment of the present invention.

FIG. 6 is a plan view showing an active matrix type liquid crystal display according to an embodiment of the present invention.

FIG. 7 is a plan view showing an active matrix type liquid crystal display according to an embodiment of the present invention.

FIG. 8 is a plan view showing an active matrix type liquid crystal display according to an embodiment of the present invention.

FIG. 9 is a plan view showing an active matrix type liquid crystal display according to an embodiment of the present invention.

FIG. 10 is a plan view showing an active matrix type liquid crystal display according to an embodiment of the present invention.

[Explanation of symbols]

 2 First metal 4 Common electrode 5 Wiring electrode 6 Backing electrode 7 Slit 8 Dielectric film 9 Second metal 11 Input electrode 12 TFD element 13 Dummy area

Claims (4)

[Claims] 1. A plurality of pixel electrodes provided on a substrate, a plurality of wiring electrodes connected to a plurality of switching elements for driving the pixel electrodes, and an input electrode for supplying a drive signal to the switching elements via a coupling capacitance. An active matrix type liquid crystal display body, characterized in that the coupling capacitances have approximately the same value. 2. A plurality of pixel electrodes provided on a substrate, a plurality of wiring electrodes connected to a plurality of switching elements for driving the pixel electrodes, and an input electrode for supplying a drive signal to the switching elements via a coupling capacitance. An active matrix liquid crystal display body, characterized in that the input electrode is directly connected to a terminal of a semiconductor chip that drives the liquid crystal display body by a chip-on-glass structure. 3. A plurality of pixel electrodes provided on a substrate, a plurality of wiring electrodes connected to a plurality of switching elements for driving the pixel electrodes, and an input electrode for supplying a drive signal to the switching elements via a coupling capacitance. And the coupling capacitance is provided between the first electrode and the second electrode, and is controlled by a slit provided in the first electrode or the second electrode to make the area of the coupling capacitance approximately the same. An active matrix type liquid crystal display body characterized by the above. 4. A plurality of pixel electrodes provided on a substrate, a plurality of wiring electrodes connected to a plurality of switching elements for driving the pixel electrodes, and an input electrode for supplying a drive signal to the switching elements via a coupling capacitance. And a drive signal is supplied from one of the pixel electrodes connected to the wiring electrode through a switching element, and a coupling capacitance is provided to the other of the pixel electrodes.