JP2001216843A - Transparent conductive film and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable to improve etching property and to greatly reduce distribution of MIM device area by uniformizing a transparent conductive film amorphous with a stability, and improve displaying quality of a liquid crystal display and is advantageous in mass productivity with this manufacturing method. SOLUTION: The conductive film 15 composing a liquid crystal display made on a substrate consists of composite compound, containing indium-tin oxide and one or more, from among titanium oxide, zirconium oxide, zinc oxide, aluminum oxide, and antimony oxide, and its manufacturing method is also provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transparent conductive film used in a liquid crystal display device and a method of manufacturing the same, and more particularly, to a MIM (metal layer-insulator layer- The present invention relates to a transparent electrode film used for a liquid crystal display device which controls a device and drives a liquid crystal, and a method for manufacturing the same.

[0002]

2. Description of the Related Art The structure and manufacturing method of a conventional MIM element are described in a plan view of FIG. 6 and sectional views of FIGS.
This will be described using the equivalent circuit diagram of FIG. 7 and the pattern shape of the conventional MIM element of FIG. The cross-sectional views of FIGS. 1 to 5 show cross sections taken along line AA of FIG.

As shown in FIGS. 5, 6 and 7, on one substrate 12, a row electrode 13 as a lower metal layer, an insulator layer 14 on the row electrode 13, and an insulator layer The pixel electrode 1 made of a transparent conductive film 15 as an upper metal layer on the pixel electrode 1
6 is formed.

Further, a protective film 17 is formed on the entire surface, a substrate 12 on which a plurality of MIM elements 32 each including a row electrode 13, an insulator layer 14 and a pixel electrode 16 are formed, and a plurality of data electrodes 3.
Liquid crystal 33 is injected between the other substrate on which 1 is formed, and
The MIM element 32 is controlled to display a predetermined image.

A method of manufacturing an MIM element according to the prior art will be described with reference to cross-sectional views of FIGS. 1 to 5 and a plan view of FIG.

First, as shown in FIG. 1, a row electrode material 20 made of a tantalum film is formed to a thickness of 200 nm on a substrate 12 made of glass by a sputtering method.

Thereafter, the tantalum film is etched by the dry etching method using the first photoresist 21 to form the row electrodes 13. The plane pattern shape of the row electrode 13 is shown by a solid line 41 in FIG.

[0008] Thereafter, as shown in FIG.
An insulator layer 14 having a thickness of 80 nm is formed on the surface of No. 3 by anodic oxidation.

Further, a transparent conductive film 15 made of indium tin oxide (ITO) is
It is formed with a thickness of 200 nm.

Thereafter, the transparent conductive film 15 is etched using the second photoresist 22. As a result, the pixel electrode 16 shown in FIG. 3 is formed. As shown in FIG. 6, the planar pattern shape of the pixel electrode 16 is indicated by a dashed line 18.

Next, as shown in FIG. 4, a protective film made of tantalum pentoxide is formed by sputtering to a thickness of 200-3.
It is formed with a thickness of 00 nm.

Thereafter, only unnecessary portions are removed by dry etching using the third photoresist 23 to form a protective film 17 on the MIM element 32 and the pixel electrode 16.

In this manner, the MIM element 32 as shown in FIG. 5 is formed by using three photomasks to form the MIM element. As shown in FIG. 6, the planar pattern shape of the protective film 17 is indicated by a two-dot chain line 43.

At this time, the current characteristic of the MIM element 32 can be expressed by the following equation. I = AI0 (A) (1) where I is the current value of the MIM element, A is the area of the MIM element, and I0 is the current density per unit area. Further, A is the line width L1 of the row electrode 13 as shown in FIG.
And the line width L2 of the pixel electrode 16, that is, A = L1 × L2
Indicated by Therefore, equation (1) is expressed as follows: I = (L1 × L2) I0 (A) (2)

As is apparent from the above equation (2), the row electrode 13 is not formed in the photomask process or the etching process.
When the line width L1 of the pixel electrode 16 or the line width L2 of the pixel electrode 16 varies, the current value of the MIM element varies.
This causes display unevenness of the liquid crystal display device, and significantly degrades display quality.

[0016]

In recent years, an active matrix liquid crystal panel has been required to have a large screen and high image quality, and further has been applied to a viewfinder or a projection television using the liquid crystal panel. In addition, high reliability is required.

In particular, in the case of a liquid crystal panel having a size of 1 inch and 100,000 pixels used in a viewfinder or a projection television, the area of the MIM element is determined by the line width L1 of the row electrode 13 and the pixel electrode 16 Both the line width L2 is 1.5 μm or less, that is, 1.5 × 1.5 μm
² or less are required.

Further, when the size of the substrate 12 is 300 mm × 300 mm or more and a large number of 1-inch panels are formed for the purpose of mass production and cost reduction,
MIM with an element area of 1.5 × 1.5 μm ² or less over the entire surface of
The elements must be formed uniformly and without variation.

The element area of the MIM element is 1.5 × 1.5 μm
In the case of m ² , MI in which display unevenness of the liquid crystal display device can be ignored
The variation range of the M element area requires that the line widths L1 and L2 both be within a dimensional accuracy range of 1.5 μm ± 0.1 μm or less.

In particular, according to the study results of the present inventor, the variation in the area of the MIM element is most likely caused by the variation in the line width L2 generated in the etching step of the pixel electrode 16 using the transparent conductive film 15. It is known.

However, in the conventional structure and manufacturing method, the pixel electrode 16 is formed using the transparent conductive film 15 made of indium tin oxide (ITO).
5 shows a crystallized columnar structure.

For this reason, as shown in FIG. 10, the planar pattern shape of the pixel electrode 16 after the etching of the transparent conductive film 15 is uneven due to the influence of the crystallized columnar structure. Furthermore, the pattern dimension is reduced at the center of the MIM element due to the columnar structure, and the line width L2 is 1 μm.
When the distance is about m, the transparent conductive film 15 in the central portion of the element often disappears.

Therefore, even if the resist pattern and the etching conditions are stabilized, the variation in the MIM element area due to the unevenness of the transparent conductive film 15 described above cannot be avoided.

Furthermore, in the crystallized columnar structure of the transparent conductive film 15 made of indium tin oxide, the film quality is not uniform, and there is a region where the etching rate is partially low. It often happens.

[0025] Particularly if the device area of the MIM element as described above is 1.5 × 1.5μm ^2, putting the dimensional accuracy ± 0.1 [mu] m ² is very difficult.

Therefore, in view of the display quality of the liquid crystal display device,
Also, there is a big problem in the yield in mass production.

The above-mentioned problem is caused by the fact that the transparent conductive film 15 made of indium tin oxide is crystallized and has a columnar structure. An improvement in accuracy can be expected.

At present, when a transparent conductive film 15 made of indium tin oxide is formed by a sputtering method, water (H2
There has been proposed a method of doping with O) or the like to make the film amorphous and uniformity including film quality.

However, in this method, it is difficult to stably dope water into the transparent conductive film 15 made of indium tin oxide with good reproducibility.

This is because even if a certain amount of water is supplied into the sputtering apparatus, the residual water in the sputtering apparatus,
This is because the amount of water brought in from the substrate 12 and the tray holding the substrate 12 is large, and the controllability of supplying water stably and with good reproducibility is extremely poor.

An object of the present invention is to solve the above problems and to provide a transparent electrode film having improved display characteristics, improved variation in the MIM element area, good display quality, and a method of manufacturing the same.

[0032]

Means for Solving the Problems In order to achieve the above object, the following means are employed in the transparent electrode film and the method of manufacturing the same according to the present invention.

The transparent conductive film provided on the substrate constituting the liquid crystal display device of the present invention is composed of a composite compound containing at least one of indium tin oxide, titanium oxide, zirconium oxide, zinc oxide, aluminum oxide and antimony oxide. It is characterized by the following.

The method for producing a transparent conductive film of the present invention is formed by a sputtering method using a target comprising a composite compound containing at least one of indium tin oxide, titanium oxide, zirconium oxide, zinc oxide, aluminum oxide and antimony oxide. It is characterized by doing.

[Operation] By using the production method of the present invention, a transparent conductive film made of indium tin oxide is coated with titanium oxide,
By adding at least one of zirconium oxide, zinc oxide, aluminum oxide and antimony oxide,
The transparent conductive film can be made amorphous stably.

As a result, the etching property of the transparent conductive film can be improved, the variation in the area of the MIM element can be reduced, and a method of manufacturing a liquid crystal display device having good display quality can be provided.

[0037]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The structure of a liquid crystal display device according to an embodiment of the present invention and a method of manufacturing the same will be described below with reference to the drawings. 1 to 6 are sectional views showing the structure of the liquid crystal display device of the present invention and a manufacturing method for forming the structure in the order of steps. FIG. 7 shows the structure of the liquid crystal display device and the manufacturing method of the present invention. FIG. 8 is a plan view showing a pattern shape of the MIM element according to the present invention, FIG. 9 is an X-ray diffraction pattern of the transparent conductive film according to the present invention, and the horizontal axis is the diffraction angle (2θ). ), The vertical axis is the diffraction intensity (arbitrary unit), and the number in parentheses shown above the arrow is the surface index of the mirror of indium tin oxide.

In the description of the following embodiments, the structure of the transparent conductive film will be described together with the description of the manufacturing method.

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

Thereafter, a positive photoresist is formed on the entire surface of the row electrode material 20 by a spin coating method, and an exposure process and a development process are performed using a first photomask to pattern the photoresist. Then, a first photoresist 21 is formed.

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

Thereafter, as shown in FIG.
The row electrode 13 is anodized in a solution of
An insulator layer 14 having a thickness of 0 to 70 nm is formed.

Next, a transparent conductive film 15 was formed using a target composed of a composite compound of indium tin oxide and zinc oxide.
Is introduced into a sputtering chamber containing 0.5 to 1% of oxygen, and the substrate 12 is heated to 200 ° C.
1 m by sputtering method controlled to mTorr
It is formed with a thickness of 00 to 200 nm.

Here, the mixing ratio of zinc oxide to indium tin oxide is desirably 0.5 atm% to 10 atm%, and amorphousization is possible without impairing the transparency and conductivity of indium tin oxide.

According to the study of the present inventor, the transparent conductive film 15
Can be considered as a factor that can be made amorphous because a small amount of zinc atoms added to the transparent conductive film 15 enter lattice voids in the indium tin oxide and hinder crystallization of the indium tin oxide. .

Therefore, when the mixing ratio of zinc oxide to indium oxide is increased, the transparent conductive film 15 becomes a mixed crystal state of zinc oxide and indium oxide and is crystallized.

Further, the present inventor has tried composite oxides of indium tin oxide and titanium oxide, indium tin oxide and zirconium oxide, indium tin oxide and aluminum oxide, and indium tin oxide and antimony oxide. Similarly, the transparent conductive film 15 formed by the sputtering method could be made amorphous. Further, a similar effect is obtained with a mixture of titanium oxide, zirconium oxide, zinc oxide, aluminum oxide, and antimony oxide.

Thereafter, a photoresist is formed on the entire surface by a spin coating method, exposed and developed using a second photomask, and the photoresist is patterned to form a second photoresist 22.

After that, as shown in FIG. 3, the transparent conductive film is etched by dry etching or wet etching using the second photoresist 22 as an etching mask to form the pixel electrode 16. The dash-dot line 18 in FIG. 6 shows the planar pattern shape of the pixel electrode 16.

As shown in FIG. 8, the MIM after etching is
The planar pattern shape of the element is as follows.
8 becomes smooth.

Further, as shown in FIG. 9, from the X-ray diffraction pattern, the peaks of the (222) plane and the (400) plane of the indium tin oxide crystal were slightly visible, and almost broad curves were obtained. It can be seen that the transparent electrode film 15 according to the embodiment of the present invention is substantially in an amorphous state. Further, the uniformity of the etching was also very good, and a part of the transparent conductive film 15 which remained in the conventional manufacturing method did not remain.

Further, regarding the transmittance and conductivity required for the transparent conductive film 15, the transmittance was about 90% and the sheet resistance was 15 Ω to 20 Ω in the case of using only indium tin oxide according to the conventional manufacturing method. On the other hand, in the embodiment of the present invention, the transmittance is 90%, the sheet resistance is 17Ω to 23, and has almost the same characteristics as Ω, which sufficiently satisfies the characteristics as the transparent conductive film 15.

Next, as shown in FIG.
% To 2% argon gas into the sputtering chamber
At a flow rate of 00 cc / min, the sputter pressure is 5 mTorr.
Tantalum pentoxide, which is the protective film 17, is formed on the substrate 12 by a sputtering method controlled to r.

Thereafter, as shown in FIG. 4, a photoresist is formed on the entire surface by a spin coating method, and a third photoresist 23 is formed using the third photomask as a mask.

Next, as shown in FIG. 5, an etching process is performed on the protective film 17 by a dry etching method using the third photoresist 23 as an etching mask.

After that, the third photoresist 23 is removed. Thus, the MIM element can be formed using three photomasks.

According to the present invention, 300 mm ×
As a result of forming a liquid crystal panel having a size of 300 mm, 1 inch, 100,000 pixels, and a MIM element area of 1.5 × 1.5 μm ² by 64 chamfers, the problem was a problem over the entire surface of the substrate 12. The dimensional accuracy of the line width L2 of the pixel electrode 16 made of the transparent electrode film 15 is within 1.5 .mu.m. +-. 0.1 .mu.m, and the variation distribution of the MIM element characteristics can be extremely reduced.

This is because the MIM element of the present invention is a transparent conductive film 1
5 is a composite compound containing at least one of indium tin oxide and titanium oxide, titanium oxide, zirconium oxide, zinc oxide, aluminum oxide, and antimony oxide. However, this is because the variation distribution of the line width L2 of the pixel electrode 16 is improved.

Therefore, the device characteristics of the MIM device according to the present invention are very uniform and can be formed with good reproducibility.

In the above description, the example in which the protective film 17 is provided has been described, but a configuration without the protective film 17 may be employed.

Further, as described in the embodiment in which the insulator layer 14 is formed by the anodic oxidation treatment, the insulator layer 14 is formed by a chemical vapor deposition (CV) method.
D) and an insulating film formed by physical vapor deposition (PVD) are also applicable. At this time, in addition to tantalum pentoxide, silicon oxide, silicon nitride, aluminum oxide, or the like can be used as the insulating film.

[0062]

As is apparent from the above description, according to the transparent conductive film and the method of manufacturing the same of the present invention, indium tin oxide, titanium oxide, zirconium oxide, zinc oxide, aluminum oxide, antimony oxide are used as the transparent conductive film. By using a composite compound containing at least one of the following to stably and uniformly amorphize, the etching property can be improved and the distribution of the MIM element area can be extremely reduced.

Therefore, the display quality of the liquid crystal display device is improved by the manufacturing method of the present invention, and it is very advantageous in mass production.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a structure of a transparent conductive film and a method of manufacturing the same according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view illustrating a structure of a transparent conductive film and a method of manufacturing the same in an embodiment of the present invention.

FIG. 3 is a cross-sectional view illustrating a structure of a transparent conductive film and a method of manufacturing the same in an embodiment of the present invention.

FIG. 4 is a cross-sectional view showing a structure of a transparent conductive film and a method for manufacturing the same in an embodiment of the present invention.

FIG. 5 is a cross-sectional view illustrating a structure of a transparent conductive film and a method of manufacturing the same in an embodiment of the present invention.

FIG. 6 is a plan view showing a structure of a transparent conductive film and a method of manufacturing the same in an embodiment of the present invention.

FIG. 7 is a circuit diagram showing an equivalent circuit of a liquid crystal display device using an MIM element.

FIG. 8 shows an MI of a liquid crystal display device according to an embodiment of the present invention.
It is a top view which shows the plane pattern shape of M element.

FIG. 9 is a drawing showing an X-ray diffraction pattern of the transparent conductive film in the embodiment of the present invention.

FIG. 10 illustrates a liquid crystal display device according to an embodiment of the present invention.
This is the pattern shape of the IM element.

[Explanation of symbols]

 12 Substrate 13 Row electrode 14 Insulator layer 15 Transparent conductive film 16 Pixel electrode 17 Protective film

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) G02F 1/1365 G09F 9/30 339Z G09F 9/30 339 H01B 13/00 503B H01B 13/00 503 G02F 1/136 510

Claims (3)

[Claims] 1. A transparent conductive film provided on a substrate constituting a liquid crystal display device is made of a composite compound containing at least one of indium tin oxide, titanium oxide, zirconium oxide, zinc oxide, aluminum oxide, and antimony oxide. A transparent conductive film, characterized in that: 2. The transparent conductive film according to claim 1, wherein the transparent conductive film is an amorphous film. 3. The method for producing a transparent conductive film according to claim 1, wherein the target is made of a composite compound containing at least one of the indium tin oxide, titanium oxide, zirconium oxide, zinc oxide, aluminum oxide, and antimony oxide. A method for producing a transparent conductive film, which is formed by a sputtering method used.