JPH06235934A - Translucent insulating substrate with uneven oxide film, method of manufacturing the same, and TFT liquid crystal display device using the same - Google Patents

Abstract

(57) [Summary] [Object] To provide a flat TFT liquid crystal display device having a wide pixel area and a low wiring resistance, using a translucent insulating substrate with an uneven oxide film. [Structure] An uneven oxide film 12 is formed on a translucent insulating substrate 1 by an anodic oxidation method, a wiring electrode is formed in the recess pattern 12b, and an intersection of a gate bus electrode and a source bus electrode is not projected on the surface. To do so. As a result, the line width of the electrode can be reduced without increasing the electric resistance.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a translucent insulating substrate with an uneven oxide film, a method for producing the same, and a TFT using the same.
(Thin film transistor) The present invention relates to a liquid crystal display device.

[0002]

2. Description of the Related Art Conventionally, Al, Cr, Ta or the like is used for a gate electrode of a TFT liquid crystal display device, and a metal conductive film of Al, Ti, Mo or the like is used for source / drain electrodes. . On the other hand, TF as a computer terminal
The T liquid crystal display device is required to have high definition, high speed response, and high visibility, and in particular, high luminance without flicker of an image is required. To meet this demand, the pixel area must be increased, the line width of the gate electrode must be narrowed, and the electrode line resistance must be reduced.

FIG. 5 shows an example of an in-plane wiring pattern of a TFT liquid crystal display device produced by a conventional technique. FIG. 6 is a sectional view taken along line XX of FIG. 5, and FIG. 7 is YY of FIG. It is a line sectional view. In these figures, 1 is a transparent insulating substrate, 2
Is a gate bus electrode, 2a is a gate electrode, 3 is an insulating film, 4
Is a semiconductor layer, 4a is a semiconductor protective layer, 5 is an ohmic contact layer, 6 is a source bus electrode, 7 is a drain electrode, 8
Is a pixel electrode. That is, the gate bus electrode 2 and the source bus electrode 6 have a structure intersecting with each other with the insulating film 3 interposed therebetween. If the line width of the gate bus electrode 2 is narrowed, the film thickness of the metal conductive film must be increased in order to secure the same electrode line resistance. If this is done, the pattern edge becomes steeper. Electrical shorts easily occur at the intersections of the source bus electrodes 6. Therefore, as the insulating film 3 on the gate bus electrode 2, an anodic oxide film in which an insulating film is formed on the side surface of the electrode pattern, a silicon nitride film or a silicon oxide film formed by a chemical vapor deposition method is used. There is.

[0004]

However, if an ultra-high-definition, high-speed response color display terminal that requires a display of 3 million pixels or more, such as a work station, is made with the TFT liquid crystal display device using the conventional technique, the gate is The line width of the bus electrodes cannot be reduced, and the auxiliary capacitance that prevents image flicker cannot be increased. Furthermore, when the line width of the gate bus electrode is narrowed to increase the film thickness, the gap with the counter electrode is locally narrowed at the portion intersecting with the source bus electrode,
The mechanical strength is insufficient, which increases the probability that an electrical short circuit will occur between the gate bus electrode and the source bus electrode at this intersection.

The present invention is intended to solve such a conventional problem, and is capable of narrowing the line width without increasing the electric resistances of the gate bus electrode and the source bus electrode, and the translucency with an uneven oxide film. An object is to provide an insulating substrate, a method for manufacturing the insulating substrate, and a TFT liquid crystal display device using the same.

[0006]

In order to achieve the above object, the present invention provides a transparent insulating substrate on which a conductive thin film for forming a gate bus electrode and a source bus electrode is formed. An uneven oxide film is formed on the anodic oxidation method and thermal oxidation method, and a bus electrode is formed on the concave pattern to form a TFT.
A liquid crystal display device is produced.

[0007]

According to the present invention, with the above structure, the electric resistance of the gate bus electrode can be reduced, high-speed responsiveness can be ensured, and the step at the pattern edge at the intersection of the gate bus electrode and the source bus electrode can be formed in the concave pattern. By forming it, the electrical short circuit is unlikely to occur and the performance is stable. Further, since the area of the pixel electrode can be increased, the performance of the display device can be improved.

[0008]

Embodiment 1 An embodiment of the present invention will be described below with reference to the drawings. For convenience of description, the reference numerals used in the description of the conventional example are used for similar elements. FIG. 1 shows a manufacturing process of a translucent insulating substrate with an uneven oxide film in the first embodiment of the present invention. In FIG. 1, 1 is a translucent insulating substrate, 9 is a metal film, 10 is a mask for forming irregularities, 11 is a metal oxide film formed by anodizing the metal film 9, and 12 is a metal oxide film. It is a completed uneven oxide film.

Next, a specific method for manufacturing the translucent insulating substrate with the uneven oxide film will be described. As the translucent insulating substrate 1, a 7059 glass substrate manufactured by Corning Incorporated was used. A metal film 9 is formed on the translucent insulating substrate 1 by a DC sputtering method as shown in FIG.
l target, sputtering gas Ar, gas pressure 0.3 Pa
And a mask for forming an Al thin film with a film thickness (100 to 2000 nm) according to a desired step difference under conditions of a sputtering power of 10 W / cm ² and further forming a predetermined uneven portion as shown in FIG. 10 was formed with a resist mask by photolithography. Then, a part of the metal film 9 is used as an anode electrode, tartaric acid is used as a chemical conversion liquid, and the exposed portion is converted into a metal oxide by an anodic oxidation method. As shown in FIG.
Was used as the metal oxide film 11 formed by the anodic oxidation method. After that, the resist mask 10 was stripped with an organic stripping solution, the unformed portion of the metal film 9 was dissolved and removed with an alkaline aqueous solution, and processed into a predetermined recess pattern. Further, heat treatment is performed in a gas atmosphere containing water in order to promote the oxidation of the insufficiently formed portion, and thermal oxidation is performed on the translucent insulating substrate 1 as shown in FIG. 150 nm of the uneven oxide film 12 having an electrically insulating uneven portion 12a.
To 3000 nm in height. Convex portions 12a and 12
The recess pattern 1 from which the metal oxide film 11 between
The width of 2b could be formed with high accuracy of 3 microns or more.

In this embodiment, the method of forming unevenness by using aluminum as an anodizing method has been shown. However, even if tantalum metal is used for the metal film 9, anodization is performed to form with good patterning property. We were able to. In the case of tantalum metal, it was possible to easily convert the insufficient chemical conversion to oxide by heat treatment in air.

[0011]

Second Embodiment Next, a TFT which is a second embodiment of the present invention.
The liquid crystal display device will be described. 2 shows an in-plane wiring pattern of the TFT liquid crystal display device, and FIG. 3 shows A of FIG.
-A line sectional view, FIG. 4 is a BB line sectional view of FIG. In these figures, 1 is a translucent insulating substrate, 2 is a gate bus electrode, 2a is a gate electrode, 3 is an insulating film, 4 is a semiconductor layer, 4a is a semiconductor protective layer, 5 is an ohmic contact layer, and 6 is a source. A bus electrode, 7 is a drain electrode, and 8 is a pixel electrode. Reference numeral 12 is an uneven oxide film formed on the surface of the translucent insulating substrate 1 by the anodic oxidation method by the above-mentioned method.

Next, a specific method of manufacturing the TFT liquid crystal display device will be described. The concave-convex oxide film 12 having the concave pattern 12b for forming the gate bus electrode 2 and the source bus electrode 6 was formed on the 7059 glass substrate of Corning Inc. used as the translucent insulating substrate 1 in advance in Example 1. Formed by the method. Next, by the DC sputtering method, the target is an Al target and the sputtering gas is A.
r, gas pressure 0.3 Pa, and sputtering power 10 W / cm
^An Al thin film was formed to a film thickness of 500 nm under the condition ² and a predetermined pattern was formed by a wet etching method to form the gate bus electrode 2 and the gate electrode 2a. Then, as the insulating film 3, the substrate temperature is set to 350 by the plasma CVD method.
A silicon nitride film of 400 nm at a temperature of
A silicon nitride film having a thickness of 100 nm and a silicon nitride film having a thickness of 100 nm were continuously formed as the semiconductor protective layer 4a. Then, the semiconductor protective layer 4a was processed into a predetermined pattern. After forming an n ⁺ -type a-Si film with a thickness of 30 nm as the ohmic contact layer 5, an island-shaped pattern was formed simultaneously with the semiconductor layer 4. Then, the gate bus electrode 2 and the gate electrode 2
The Al thin film having the same film thickness as that of a, 500 nm, was formed and processed into a predetermined pattern to form the source bus electrode 6 and the drain electrode 7. After that, an ITO film is used as the pixel electrode 8
It was formed by film forming patterning with a thickness of 00 nm. When the TFT liquid crystal display device configured as described above was operated, good results could be obtained.

In this embodiment, since the anodic oxidation method is used as the method for forming the uneven oxide film 12, the gate bus electrode 2 and the source bus electrode 6 can be formed as electrodes having a narrow line width and low electric resistance, and the pixel element The area of the electrode 8 could be increased.

[0014]

As described above, according to the present invention, the uneven oxide film is provided on the translucent insulating substrate of the TFT liquid crystal display device, and the gate bus electrode and the source bus electrode are formed in the concave pattern. Therefore, the line width can be narrowed and the area of the pixel electrode can be increased without increasing the electric resistance of the gate bus electrode and the source bus electrode.
In addition, it is possible to prevent an electrical short circuit due to mechanical pressure in the gap between the counter electrode and the intersection of the gate bus electrode and the source bus electrode, and to provide a flat, highly reliable and high performance TFT.
A liquid crystal display device can be realized.

[Brief description of drawings]

FIG. 1 is a schematic sectional view showing a manufacturing process of a translucent insulating substrate with an uneven oxide film in a first example of the present invention.

FIG. 2 is an in-plane wiring pattern diagram of a TFT liquid crystal display device according to a second embodiment of the present invention.

3 is a cross-sectional view taken along the line AA of FIG.

FIG. 4 is a sectional view taken along line BB in FIG.

FIG. 5 is an in-plane wiring pattern diagram of a conventional TFT liquid crystal display device.

6 is a cross-sectional view taken along line XX of FIG.

7 is a cross-sectional view taken along line YY of FIG.

[Explanation of symbols]

 1 translucent insulating substrate 2 gate bus electrode 2a gate electrode 3 insulating film 4 semiconductor layer 4a semiconductor protective layer 5 ohmic contact layer 6 source bus electrode 7 drain electrode 8 picture element electrode 9 metal film 10 mask 11 metal oxide film 12 unevenness Oxide film 12a Convex portion 12b Recessed pattern

Claims (3)

[Claims] 1. A translucent insulating substrate with an uneven oxide film having an oxide film having a concave pattern capable of forming a gate bus electrode and a source bus electrode on the surface. 2. A metal film is formed on a translucent insulating substrate, a desired concave pattern is masked so as not to oxidize, and a convex portion is formed by anodization to form an oxide film,
After that, the mask is removed to dissolve and remove the metal film, and a thermal oxidation process is further performed, which is a method for manufacturing a translucent insulating substrate with an uneven oxide film. 3. A TFT liquid crystal display device comprising the translucent insulating substrate with an uneven oxide film according to claim 1, wherein a gate bus electrode and a source bus electrode are formed in a pattern of the recess.