JPH07159812A - Liquid crystal display device and its production - Google Patents

Abstract

PURPOSE:To obtain a device having good display quality by providing row electrodes, anodically oxidized layer on the row electrode, pixel electrode on the anodically oxidized layer, intermediate protective film on the pixel electrode, and protective film on the intermediate protective film, and further an IC connecting electrode connected to the row electrode. CONSTITUTION:A row electrode 13, anodically oxidized layer 14, and pixel electrode 15 are successively formed on a glass substrate 12 to obtain an MIM (metal layer-insulating layer-metal layer) element 32. Further, an intermediate protective film 25 is formed as a diffusion preventing layer under a protective film 16. Further, an IC connecting electrode 17 which is connected with the row electrode 13 is formed. The intermediate protective film 25 consists of silicon dioxide, aluminum oxide, silicon nitride or mixture of these. By forming the intermediate protective film 25 between the transparent electrode film and the protective film 16, the resistance of the output terminal of the MIM element 32 can be decreased and variation in resistance of the output terminal is decreased.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of a liquid crystal display device and a manufacturing method thereof, and more particularly to a semiconductor integrated circuit device (I
C) Controls a MIM (metal layer-insulator layer-metal layer) element that is a non-linear element provided in each pixel arranged in a matrix using a chip-on-glass (COG) directly connected to a liquid crystal display device. The present invention relates to a structure of a liquid crystal display device that drives liquid crystals and a manufacturing method thereof.

[0002]

2. Description of the Related Art A conventional MIM device structure is shown in a plan view of FIG. 14, sectional views of FIGS. 9 to 13, and an equivalent circuit diagram of FIG.
This will be described with reference to the graph showing the IC connection resistance value frequency distribution data in FIG. The sectional views of FIGS. 9 to 13 are sectional views taken along the line AA of FIG.

As shown in FIGS. 13, 14 and 15, a row electrode 13 on one substrate 12, an anodized layer 14 on the row electrode 13, and a pixel electrode 1 on the anodized layer 14.
5 and the IC connecting portion 17 is formed in the end region of the row electrode 13.
To form.

Further, a substrate on which a protective film 16 is formed on the entire surface other than the IC connection portion 17 and a plurality of MIM elements 32 each including a row electrode 13, an anodized layer 14 and a pixel electrode 15 are formed,
Liquid crystal 33 is injected between the other substrate on which the plurality of data electrodes 31 are formed, and the MIM element 32 is controlled to display an image.

A method of manufacturing the MIM element in this conventional technique will be described with reference to the sectional views of FIGS. 9 to 13 and the plan view of FIG.

As shown in FIG. 9, a substrate 1 made of glass is used.
A row electrode material 20 made of a tantalum film is formed on the second electrode 2 by sputtering to have a film thickness of 200 nm. After that, using the first photoresist 21 as an etching mask,
The tantalum film is etched by a dry etching method to form the row electrode 13. The plane pattern shape of the row electrode 13 is shown by a solid line 43 in FIG.

Then, as shown in FIG. 10, an anodic oxidation layer 14 of 80 n is formed on the surface of the row electrode 13 by an anodic oxidation method.
It is formed with a film thickness of m.

Further, a transparent electrode film 42 made of, for example, indium tin oxide (ITO) is formed by a sputtering method.
Is formed with a film thickness of 100 to 200 nm. Then the second
The photoresist 22 is used to etch the transparent electrode film 42.

As a result, the pixel electrode 15 shown in FIG.
An IC connection electrode 17 for connecting an IC chip is formed. As shown in FIG. 14, the planar pattern shape of the pixel electrode 15 is shown by the alternate long and short dash line 19 and is also formed on the row electrode 13. Further, the plane pattern shape of the IC connection electrode 17 is shown by a dashed-dotted line portion 47.

Next, as shown in FIG. 12, a protective film 16 made of tantalum oxide was formed by sputtering to 200
It is formed with a film thickness of 300 nm. After that, only the portion of the IC connection hole 24 is etched by the dry etching method using the third photoresist 23 to form the protective film 16 having an opening. The plane pattern shape of the third photoresist 23 is shown by a chain double-dashed line 18.

In this way, the MIM element 3 shown in FIG.
2 is formed by three photomasks to form an MIM element. Then, the electrodes of the IC chip are connected to the IC connection electrodes 17 using a conductive paste.

At this time, as shown in the plan view of FIG. 14, a voltage is applied to the MIM element from the IC connecting electrode 17 through the IC to drive the liquid crystal.

If the connection resistance of the IC connection electrode 17 after the IC connection is extremely high, a sufficient voltage is not applied to the row electrode 13 and a linear display defect occurs in the liquid crystal display device.

[0014]

In recent years, active matrix liquid crystal panels are required to have a large screen and high image quality, and further spread to viewfinders and projection televisions using liquid crystal panels, and with higher definition patterns. , High reliability is required.

The applied voltage for driving the liquid crystal drops due to the output terminal resistance. If the voltage drop is large, a sufficient voltage is not applied to the liquid crystal. Therefore, writing cannot be performed and the display quality of the liquid crystal display device is significantly deteriorated.

The output terminal resistance is the IC connection resistance value and the row electrode 1
The resistance value of the row electrode 13 is determined by the row electrode width, length, tantalum film thickness and specific resistance, and the IC connection resistance value is the connection resistance value of the IC connection paste and the IC connection electrode 17. Is determined by.

For example, the size is 1 inch and the number of pixels is 10
In the case of a viewfinder LCD panel with 10 million pixels,
The output terminal resistance value that can sufficiently drive the liquid crystal is required to be 1 KΩ or less.

However, in the conventional manufacturing method, FIG.
As shown in, the ITO of the IC connection electrode 17 and the protective film 1
Due to the mutual diffusion of 6 with tantalum oxide, a diffusion layer 44 having a high resistance value is formed at the interface between the IC connection electrode 17 and the protective film 16. Then, even after the dry etching of the protective film 16, the diffusion layer 24 cannot be completely removed, and the IC connection resistance increases to about 2 to 3 KΩ.

Thus, it is very difficult to form the output terminal resistance at 1 KΩ or less with good reproducibility, and there is a problem in display quality.

FIG. 16 shows an example of the frequency distribution of the connection resistance value after mounting the IC connection electrode 17 and the IC formed by the conventional manufacturing method. In the graph of FIG. 16, the horizontal axis represents the connection resistance value and the vertical axis represents the number of occurrences.

As is apparent from the graph of FIG. 16, in the conventional manufacturing method, four terminals have a connection resistance value of 1 KΩ or more.
There are 11 locations in the 00 terminal.

This is a protective film 16 made of tantalum oxide.
Then, the diffusion layer 44 is formed at the interface between the IC connection electrode 17 and the protective film 16 by mutual diffusion with the IC connection electrode 17 formed of the transparent electrode film. The reason is that the diffusion layer 24 cannot be completely removed in the etching process of the protective film 16.

Therefore, in the conventional method of manufacturing a liquid crystal display device, the output terminal resistance value is greatly increased, and the display quality of the liquid crystal display device is significantly deteriorated.

An object of the present invention is to solve the above problems and to provide a method of manufacturing a liquid crystal display device having good display quality.

[0025]

In order to achieve the above object, the present invention adopts the structure of a liquid crystal display device and the manufacturing method thereof described below.

The liquid crystal display device of the present invention includes a row electrode provided on the substrate, an anodized layer provided on the row electrode, a pixel electrode provided on the anodized layer, an intermediate protective film provided on the pixel electrode, and an intermediate layer. It has a protective film provided on the protective film, and further has an IC connecting electrode connected to the row electrode.

According to the method of manufacturing a liquid crystal display device of the present invention, a row electrode material is formed on the entire surface of a substrate, a first photoresist is formed on the row electrode material, and the first photoresist is used as a mask. A step of etching the electrode material to form a row electrode, a step of removing the first photoresist, anodizing the row electrode to form an anodized layer, and a step of forming a transparent electrode film on the entire surface, Forming a second photoresist,
A step of etching the transparent electrode film using the second photoresist as a mask to form a pixel electrode and an IC connection electrode, a step of removing the second photoresist, an intermediate protective film on the entire surface, and a protective film. Are sequentially formed, a third photoresist is formed, the intermediate protective film and the protective film on the IC connection electrode are etched using the third photoresist as a mask, and the third photoresist is removed. And a step of performing.

The intermediate protective film of the present invention is made of silicon dioxide, aluminum oxide, silicon nitride, or a compound compound thereof.

[0029]

Embodiments of the structure of a liquid crystal display device according to the present invention and a method of manufacturing the same will be described below with reference to the drawings. 1 to 6 are cross-sectional views showing a structure of a liquid crystal display device according to the present invention and a manufacturing method thereof, and FIG. 7 is a plan view illustrating the structure of a liquid crystal display device according to the present invention and a manufacturing method thereof. . 1 to 6 show cross sections taken along the line BB in FIG. 7.

As shown in FIG. 6, the structure of the liquid crystal display device according to the embodiment of the present invention is as follows.
The row electrode 13, the anodic oxide layer 14, and the pixel electrode 15 are sequentially provided to form the MIM element 32. Further, an intermediate protective film 25 that functions as a diffusion prevention layer is provided below the protective film 16. Furthermore, the IC connection electrode 1 connected to the row electrode 13
7 is provided.

The intermediate protective film 25 is made of silicon dioxide, aluminum oxide, silicon nitride, or a composite compound thereof. Next, a method of manufacturing the MIM element having the structure shown in FIG. 6 will be described.

First, as shown in FIG. 1, a tantalum film is formed as a row electrode material 20 on the glass substrate 12 by sputtering to have a film thickness of 100 to 300 nm.

After that, a positive photoresist is formed on the entire surface of the row electrode material 20 by a spin coating method, and exposure and development are performed using the first photomask to pattern the photoresist. 1 photoresist 2
1 is formed.

After that, as shown in FIG. 2, the tantalum film which is the row electrode material 20 is patterned by dry etching using the first photoresist 21 as an etching mask to form the row electrode 13. The plane pattern shape of the row electrode 13 is shown by a solid line hatched portion 41 in FIG.

Thereafter, as shown in FIG. 2, 0.01 wt%
The row electrode 13 is anodized in a couenoic acid solution,
The anodic oxide layer 14 having a film thickness of 70 nm is formed.

Next, an argon gas containing 0.5 to 1% oxygen is introduced into the chamber of the sputtering apparatus, and the pressure is controlled to 10 mTorr by a sputtering method.
A transparent electrode film 42 made of indium tin oxide (ITO) is formed on the entire surface to a thickness of 100 to 200 nm.

After that, a photoresist is formed on the entire surface by a spin coating method, exposure and development are performed using a second photomask, patterning of the photoresist is performed, and a second photoresist 22 is formed.

After that, as shown in FIG. 3, the second photoresist 22 is used as a mask to etch the transparent electrode film 42 by a dry etching method or a wet etching method, and the pixel electrode 15 and the IC connection electrode 17 are etched. To form. Then, the second photoresist 22 is removed.

The plane pattern shape of the pixel electrode 15 is shown by the alternate long and short dash line 19 in FIG. 7, and the plane pattern shape of the IC connection electrode 17 is shown by the alternate long and short dashed line portion 47 in FIG.

Next, as shown in FIG.
An intermediate protective film 25 is formed by a sputtering method in which argon gas containing ˜1% is introduced into the chamber of the sputtering apparatus at a flow rate of 100 cc / min, the substrate 12 is heated to a temperature of 200 ° C., and the sputtering pressure is controlled to 5 mTorr. A silicon nitride film is formed on the entire surface with a film thickness of 20 to 50 nm.

Further, an argon gas containing tantalum oxide as the protective film 16 containing 1 to 2% of oxygen is introduced into the chamber of the sputtering apparatus at a flow rate of 100 cc / min.
Is heated to a temperature of 200 ° C. and the sputtering pressure is set to 5 mTorr.
It is formed on the entire surface by a sputtering method controlled to. The intermediate protective film 25 and the protective film 16 are continuously formed in the same sputtering apparatus.

Thereafter, as shown in FIG. 5, a photoresist is formed on the entire surface by a spin coating method, exposed and developed using a third photomask, and the photoresist is patterned to form a third photoresist 23. To form.

Next, as shown in FIG. 6, the protective film 16 and the intermediate protective film 25 on the IC connection electrode 17 are etched by a dry etching method using the third photoresist 23 as a mask to etch the IC connection hole. 24 is formed. The plane pattern shape of the third photoresist 23 at this time is shown by the chain double-dashed line 18 in FIG.

As the intermediate protective film 25, in addition to silicon nitride, silicon dioxide, aluminum oxide, titanium oxide, or a compound compound thereof can be applied.

After that, the third photoresist 23 is removed. In this way, the MIM element 32 is formed by the three photomasks.

FIG. 8 shows frequency distribution data of the IC connection electrode 17 and the IC mounting portion connection resistance value of the MIM element formed by the manufacturing method of the present invention.

The horizontal axis of the graph in FIG. 8 represents the connection resistance value, and the vertical axis represents the frequency. As is clear from the graph of FIG. 8, the IC connection resistance value of the MIM element of the present invention is smaller than that of the conventional one.
It is possible to provide a liquid crystal display device having a connection resistance value in which a resistance value of KΩ or more does not occur and which has a very small variation in resistance value.

The reason for this is that the MIM element of the present invention is provided with the intermediate protective film 25, so that there is little variation in order to prevent mutual diffusion between the IC connection electrode 17 and the protective film 16.
This is because a low connection resistance value can be obtained.

According to the MIM element structure and the manufacturing method thereof of the present invention, an MIM element having an output terminal resistance value of 1 KΩ or less and a very small variation can be formed with good reproducibility.

In the above description, the IC connection electrode 17 is made of the transparent electrode film which is the same material as the pixel electrode 15, but the IC connection electrode 17 is made of gold (Au) other than the transparent electrode film. You may comprise with a metal film, such as nickel (Ni).

[0051]

As is apparent from the above description, in the structure of the liquid crystal display device of the present invention and the manufacturing method thereof, the intermediate protective film is formed between the transparent electrode film and the protective film. This makes it possible to reduce the resistance of the output terminal resistance of the MIM element, and further reduce the variation in the resistance of the output terminal resistance value. Therefore, the present invention improves the display quality of the liquid crystal display device and significantly improves the reliability.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a liquid crystal display device and a manufacturing method thereof according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a liquid crystal display device and a method of manufacturing the same according to an embodiment of the present invention.

FIG. 3 is a cross-sectional view showing a liquid crystal display device and a method of manufacturing the same according to an embodiment of the present invention.

FIG. 4 is a cross-sectional view showing a liquid crystal display device and a manufacturing method thereof according to an embodiment of the present invention.

FIG. 5 is a cross-sectional view showing a liquid crystal display device and a method of manufacturing the same according to an embodiment of the present invention.

FIG. 6 is a cross-sectional view showing a liquid crystal display device and a method of manufacturing the same according to an embodiment of the present invention.

FIG. 7 is a plan view showing a liquid crystal display device and a manufacturing method thereof according to an embodiment of the present invention.

FIG. 8 is a graph showing a frequency distribution of IC connection resistance values of a liquid crystal display device according to an example of the present invention.

FIG. 9 is a cross-sectional view showing a method of manufacturing a conventional liquid crystal display device.

FIG. 10 is a cross-sectional view showing a method of manufacturing a conventional liquid crystal display device.

FIG. 11 is a cross-sectional view showing a method of manufacturing a conventional liquid crystal display device.

FIG. 12 is a cross-sectional view showing a method of manufacturing a conventional liquid crystal display device.

FIG. 13 is a cross-sectional view showing a method of manufacturing a conventional liquid crystal display device.

FIG. 14 is a plan view showing a conventional liquid crystal display device.

FIG. 15 is a circuit diagram showing an equivalent circuit of a liquid crystal display device using MIM elements.

FIG. 16 is a graph showing a frequency distribution of IC connection resistance values of a conventional liquid crystal display device.

[Explanation of symbols]

 12 substrate 13 row electrode 14 anodized layer 15 pixel electrode 16 protective film 17 IC connection electrode 25 intermediate protective film

Claims (11)

[Claims] 1. A row electrode provided on a substrate, an anodized layer provided on the row electrode, and a pixel electrode provided on the anodized layer,
A liquid crystal display device comprising: an intermediate protective film provided on a pixel electrode; a protective film provided on the intermediate protective film; and an IC connecting electrode connected to a row electrode. 2. A row electrode provided on a substrate, an anodized layer provided on the row electrode, a pixel electrode and an IC connection electrode made of a transparent electrode film provided on the anodized layer, and an intermediate protective film provided on the pixel electrode. And a protective film provided on the intermediate protective film. 3. The liquid crystal display device according to claim 1, wherein the row electrode is made of tantalum. 4. The liquid crystal display device according to claim 1, wherein the anodized layer is formed by anodizing tantalum. 5. The liquid crystal display device according to claim 1, wherein the pixel electrode is made of indium tin oxide. 6. The liquid crystal display device according to claim 1, wherein the IC connection electrode is made of indium tin oxide. 7. The liquid crystal display device according to claim 1, wherein the intermediate protective film is made of silicon dioxide, aluminum oxide, silicon nitride, or a compound compound thereof. 8. The liquid crystal display device according to claim 1, wherein the protective film is made of tantalum oxide. 9. The liquid crystal display device according to claim 1, wherein the IC connection electrode is made of a transparent electrode film or a metal film. 10. A row electrode material is formed on the entire surface of the substrate,
Forming a row electrode by forming a first photoresist on the row electrode material and etching the row electrode material using the first photoresist as an etching mask; and removing the first photoresist to form the row electrode A step of anodizing to form an anodized layer, a step of forming a transparent electrode film on the entire surface,
Forming a second photoresist, etching the transparent electrode film using the second photoresist as an etching mask to form pixel electrodes and IC connection electrodes, and removing the second photoresist, An intermediate protective film on the entire surface,
A step of sequentially forming a protective film, a step of forming a third photoresist, and a step of etching the intermediate protective film and the protective film on the IC connection electrode using the third photoresist as an etching mask; And a step of removing the photoresist. 11. The method of manufacturing a liquid crystal display device according to claim 10, wherein the intermediate protective film is made of silicon dioxide, aluminum oxide, silicon nitride or a compound compound thereof and is formed on the entire surface of the substrate.