JPH05333372A - Tft liquid crystal display device and its production - Google Patents

Abstract

PURPOSE:To obviate the generation of a short circuit at the intersected parts of gate bus electrodes and source bus electrodes and to expand a picture element electrode area by forming ruggedness in the prescribed parts on a light transparent insulating substrate and forming the gate bus electrodes on the substrate formed with the ruggedness. CONSTITUTION:The striped rugged parts 9 are formed on the surface of the light transparent insulating substrate 1. The gate bus electrodes 2 and the gate electrodes 2a are formed thereon. An insulating film 3, a semiconductor layer and an ohomic contact layer are formed and are patterned to island shapes. The source bus electrodes 6 and drain electrodes are thereafter formed. The electric resistance is lowered and the high-speed responsiveness are assured without increasing the film thickness of the gate bus electrodes 2 by this constitution. In addition, the level differences at the pattern edges of the intersected parts of the gate bus electrodes 2 and the source bus electrodes 6 are smoothed and the electrical short circuit is hardly generated. Further, the area of the picture element electrodes is expanded.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a TFT liquid crystal display device having a characteristic of a gate electrode and a gate bus electrode structure and a method for manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, a gate electrode of a TFT liquid crystal display device is made of Al, Cr, Ta or the like, and a source or drain electrode is made of a metal conductive film of Al, Ti, Mo or the like. On the other hand, a TFT liquid crystal display device as a terminal of a computer is required to have high definition, high speed response and high visibility, and in particular, high brightness without flicker of an image is required. In order 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. 7 shows an in-plane wiring pattern diagram of a TFT liquid crystal display device prepared by a conventional technique, and FIG.
BB sectional views are shown in FIGS. 5 and 6, respectively.

In FIGS. 5 and 6, 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, and 5 is an ohmic contact. A layer, 6 is a source bus electrode, 7 is a drain electrode, and 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 same electrode line resistance is ensured. If the film thickness of the metal conductive film is increased, the pattern edge becomes steeper. Therefore, at the intersection of the gate bus electrode 2 and the source bus electrode 6. It becomes easy to electrically short-circuit. 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.

[0005]

In such a conventional structure, an ultra-high-definition, high-speed response color display terminal, which requires a display of 3 million pixels or more, such as a work station, has been manufactured by using the conventional technology for TFT liquid crystal display. When a display device is manufactured, the width of the gate bus electrode line cannot be narrowed and the auxiliary capacitance that prevents image flicker cannot be increased. Furthermore, if the line width of the gate bus electrode is made narrower and the film thickness is made thicker, the gap between the source bus electrode and the counter electrode becomes narrower locally, and the mechanical strength becomes insufficient. The probability that an electrical short circuit will occur between the gate bus electrode and the source bus electrode will be increased.

The present invention solves the above problems, and provides a TFT liquid crystal display device in which an electrical short circuit does not occur at the intersection of a gate bus electrode and a source bus electrode and the area of a pixel electrode is enlarged. With the goal.

[0007]

In order to achieve the above-mentioned object, the present invention is to provide at least a gate bus on a translucent insulating substrate on which irregularities are formed in a predetermined portion on the translucent insulating substrate. It is composed of electrodes.

[0008]

With the above structure, the electrode resistance can be reduced without increasing the film thickness of the gate bus electrode, high-speed response can be ensured, and a step at the pattern edge at the intersection with the gate bus electrode and the source bus electrode can be ensured. And makes it difficult for an electrical short circuit to occur, and further, the area of the pixel electrode can be increased.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIGS. 1, 2 and 3 are views corresponding to FIGS. 5, 6 and 7 of a conventional example of a TFT liquid crystal device which is an embodiment of the present invention. 1 and 2, the description of the same parts as those of FIGS. 5 and 6 of the conventional example will be omitted. That is, a feature of the present invention is that the uneven portion 9 is provided on the surface of the translucent insulating substrate 1 as shown in FIG.

A specific embodiment will be described. As the translucent insulating substrate 1, a 7059 glass substrate manufactured by Corning Incorporated was used. Dry etching was performed on the surface of the glass substrate to form stripe-shaped irregularities. After that, the pattern edge was smoothed by wet etching.
Next, the target is an Al target, the sputtering gas is Ar, the gas pressure is 0.3 Pa, and the sputtering power is 10 W / cm ² on the translucent insulating substrate 1 on which the stripe-shaped uneven portion 9 is formed by DC sputtering. An aluminum (Al) thin film with a film thickness of 200 nm under the conditions,
Form a predetermined pattern by wet etching,
The gate bus electrode 2 and the gate electrode 2a were used. Then, as the insulating film 3, the temperature of the insulating substrate 1 is 350 ° C. and the silicon nitride film is 400 nm by plasma CVD.
An a-Si film of 100 nm as the semiconductor layer 4 and a silicon nitride film of 100 nm as the semiconductor protective layer 4a were continuously formed. Then, the semiconductor protective layer 4a was processed into a predetermined pattern. N ⁺ type a-as ohmic contact layer 5
After forming a Si film to a thickness of 30 nm, an island pattern was formed simultaneously with the semiconductor layer 4. After that, an Al thin film having the same film thickness of 300 nm as the gate bus electrode 2 and the gate electrode 2a is formed and processed into a predetermined pattern to form the source bus electrode
The drain electrode 7 was formed. After that, the pixel electrode 8
An O film was formed by film forming with a thickness of 200 nm. When the TFT liquid crystal display device configured as described above was operated, good results were obtained.

In the present embodiment, the shape of the uneven portion is shown as a stripe shape, but in addition to this, the uneven portion may have a hole shape. For example, in the present embodiment, a similar effect can be obtained by forming a conductive film for a gate bus electrode after forming a circular hole by irradiating a laser beam to melt the base. Here, the effect of how much the electrode line width can be widened by this unevenness will be roughly estimated. When the height of the unevenness is t, the line width is W, and the number of the unevenness is n, the apparent line width of the stripe is 2nt + W. For example, W is 50 μm and t is 1 μm
And unevenness is formed at a pitch of 5 μm, n = 1
Since 0,2nt = 20 μm, the width of 5/7 can be reduced.
Actually, the apparent line width is close to 2 ((W / 2n) ² + t ² ) ^1/2 n because it is formed in a slope shape as shown in FIG. 4, which is 53. About 8 μm,
The reduction is just under 7%. However, when t is 2 μm, it becomes 64 μm, which is about 12% reduction. From this, it is understood that the effect of the present invention is greater as the depth of the groove t is deeper. Further, when the unevenness of the base is formed in a hole shape and the gate electrode film is further formed, the effect is inferior to the stripe-shaped groove, but it is effective as compared to the case without treatment. The unevenness forming method of the present invention may be selected according to the pattern shape.

[0012]

As is apparent from the above-described embodiments, the present invention forms irregularities on a predetermined portion of a translucent insulating substrate, and at least a gate bus electrode is provided on the translucent insulating substrate on which the irregularities are formed. As a result of the formed structure, the area of the pixel electrode can be expanded as a result, and moreover, the electrical short circuit due to the mechanical pressure of the gap between the counter electrode at the intersection of the gate bus electrode and the source bus electrode can be prevented. TFT that can
A liquid crystal display device can be provided.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional view of a TFT liquid crystal display device according to an embodiment of the present invention.

FIG. 2 is a sectional view of a portion different from FIG.

FIG. 3 is a plan view of a TFT liquid crystal display device including the cross-sectional portions of FIGS.

FIG. 4 is a partial cross-sectional view of a TFT liquid crystal display device according to another embodiment of the present invention.

FIG. 5 is a partial sectional view of a conventional TFT liquid crystal display device.

FIG. 6 is a sectional view of a portion different from FIG.

FIG. 7 is a plan view of a TFT liquid crystal display device including the cross-sectional portions of FIGS.

[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 uneven portion

Claims (2)

[Claims] 1. A TFT liquid crystal display device having at least a translucent insulating substrate and a gate bus electrode, a gate electrode, an insulating film, a semiconductor layer and an ohmic electrode which are sequentially patterned on the translucent insulating substrate, A TFT liquid crystal display device characterized in that irregularities are formed on a predetermined portion of the translucent insulating substrate, and at least a gate bus electrode is formed on the irregular translucent insulating substrate. 2. An uneven portion is formed on a predetermined portion of the transparent insulating substrate using at least one of a physical etching method and a chemical etching method, and the uneven insulating portion includes the uneven portion. A method for manufacturing a TFT liquid crystal display device, which further comprises at least a step of forming a gate bus electrode.