JP3111568B2 - Active matrix substrate and manufacturing method thereof - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a manufacturing method of the active matrix base plate used in a liquid crystal display device.

[0002]

2. Description of the Related Art In recent years, wall-mounted TVs, projection-type TVs,
Various display devices using a liquid crystal panel as a display for the A device are being developed. Among active liquid crystal panels, an active matrix liquid crystal display device in which a thin film transistor, which is an active element, is incorporated in a liquid crystal display device has advantages such as a reduction in contrast and response speed even when the number of scanning lines is increased. For realizing a display device for electronic devices.

As an example of an active matrix substrate, FIG. 3A shows a planar structure, and FIG. 3B shows a sectional structure.

[0004] As shown in FIG.
0, a thin film transistor 2, a scanning line 21, a signal line 2
2. The pixel electrode 3 is formed. In this case, as shown in FIG. 3B, the upper end of the region where the thin film transistor 2 and the scanning line 21 and the signal line 22 are formed is higher than the region of the pixel electrode 3 as shown in FIG. ing.

[0005]

However, in the above-described structure of the active matrix substrate, since the area occupied by the thin film transistor 2 and the area constituted by the scanning electrodes 21 and the signal electrodes 22 is small, the active matrix substrate cannot be viewed as a whole. In this case, the convex portion is partially formed on the flat substrate. Therefore,
For example, even if planarization is performed using a reflow method, an etch-back method, or the like, there is a problem that even if local planarization can be performed, it is difficult to perform uniform planarization over the entire substrate. Was.

Further, as schematically shown in FIG. 4, a glass substrate 1 on which a thin film transistor 2, a pixel electrode 3 and the like are formed.
When an active matrix liquid crystal display device is formed by bonding an opposing substrate 5 to the opposing substrate 5 using a small ball 4 of, for example, 5 μm as a spacer, and sealing liquid crystal therebetween, a thin film transistor 4 is disposed between the thin film transistor and the opposing substrate. When small balls are interposed, there is a problem that gap unevenness occurs. Therefore, the conventional active matrix substrate has a drawback that it is essentially unsuitable for a liquid crystal display.

An object of the present invention is to provide an active matrix substrate which has solved the above-mentioned drawbacks and has improved planarization, and a method of manufacturing the same.

[0008]

Means for Solving the Problems To achieve the above object,
Therefore, in the active matrix substrate of the present invention,
Thin film transistors, scanning lines and signals on a glass substrate
A line and a pixel electrode, and a region for forming the pixel electrode.
The upper end has at least the thin film transistor and the scan line.
The same height as the top of the area consisting of the scanning line and the signal line
Or more than that.

Further , in the present invention, a transparent insulating layer is formed.
Wiring and pixels connected to the TFT element provided in the recessed portion
The electrode is connected inside the recess.

[0010]

[0011]

By making the upper end of the pixel electrode in the wide area formed on the glass substrate higher than the upper end of the area composed of the thin film transistor, the scanning line and the signal line, the apparently flat area is partially narrow in the substrate. , The flatness is improved as a whole of the active matrix substrate.

[0012]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIGS. 1A to 1D are cross-sectional views showing a first embodiment of the present invention in the order of steps.

First, as shown in FIG. 1A, a SiO ₂ film 11 is formed on a glass substrate 10 by, for example, a CVD method.
After the growth of 0 nm, a photoresist 6 is formed in a predetermined region.

[0015] Next, as shown in FIG. 1 (b), SiO ₂
The film 11 is subjected to, for example, dry etching to obtain the transparent insulating layer 1.
Form 2

Next, as shown in FIG. 1C, a gate electrode is formed after forming a gate oxide film on an island-like Si film on the glass substrate 10, and a source region and a drain region are formed by ion implantation or the like. Then, after growing an interlayer insulating film, a contact hole is opened, and an Al electrode is formed to form a thin film transistor 2.

Subsequently, as shown in FIG. 1D, after growing an indium tin oxide film on the transparent insulating layer 12,
The pixel electrode 3 is formed by using the photo-etching technique, and the active matrix substrate is created.

FIGS. 2A to 2D are sectional views showing a reference example in the order of steps.

First, as shown in FIG. 2A, a photoresist 6 is formed in a predetermined region of a glass substrate 10.

Next, as shown in FIG. 2C, a gate electrode is formed after forming a gate oxide film on the island-shaped Si film in the dug portion 13, and a source region and a drain region are formed by ion implantation or the like. Then, after growing an interlayer insulating film, a contact hole is opened to form a thin film transistor 2 having an Al electrode formed thereon.

Subsequently, as shown in FIG. 2D, after growing an indium tin oxide film on the glass substrate 10,
The pixel electrode 3 is formed by using the photo-etching technique, and the active matrix substrate is created.

In the active matrix substrate manufactured as described above, the upper end of the pixel electrode 3 in a wide area formed on the glass substrate 10 is positioned at the upper end of the area including the thin film transistor 2, the scanning line 21 and the signal line 22. Higher than. Therefore, since only a narrow portion of the recess is present in the apparently flat active matrix substrate, the flatness of the entire active matrix substrate is improved.

In the embodiment, the thin film transistor is shown as a planar type, but is not limited thereto.
It may be staggered or another structure.

[0024]

As described above in detail, according to the present invention, the upper end of the pixel electrode in a wide area formed on the glass substrate is higher than the upper ends of the thin film transistor area and the wiring area. Therefore, since only a narrow portion of the recess is present in the apparently flat active matrix substrate, the flatness of the entire active matrix substrate is improved.

By combining the flattening technique of the present invention with the active matrix substrate etch-back method or the like, almost complete flattening can be realized.

Further, when the liquid crystal display is formed, the gap is determined by the spacer on the pixel electrode when bonding to the opposing substrate, so that gap unevenness can be reduced.

Further, since no pressure is applied to the thin film transistor, the scanning line, and the signal line through the spacer as in the related art, it is possible to prevent a decrease in transistor characteristics due to the pressure, a disconnection of the wiring, and the like, and to improve a yield and reliability. Can be achieved.

[Brief description of the drawings]

FIG. 1 is a sectional view showing the structure of each step of a first embodiment of the present invention.

FIG. 2 is a sectional view showing the structure of each step of a reference example .

FIG. 3 is a plan view and a cross-sectional view of a conventional active matrix substrate.

FIG. 4 is a cross-sectional view illustrating a configuration of a liquid crystal display using a conventional active matrix substrate.

[Explanation of symbols]

 Reference Signs List 2 thin film transistor 3 pixel electrode 4 spacer 5 counter substrate 6 photoresist 10 glass substrate 11 SiO2 film 12 transparent insulating layer 13 dug portion 21 scanning line 22 signal line

Claims (3)

(57) [Claims] An upper end of a region including a thin film transistor , a scanning line and a signal line on a transparent insulating substrate having a flat surface.
A step of forming a transparent insulating layer only in a region where a pixel electrode is formed by depositing and patterning a transparent insulating layer having the same height or a thickness greater than or equal to the thickness of the transparent insulating layer; and A thin film transistor is formed on the transparent insulating substrate in a region other than the transparent insulating layer corresponding to the lower part of the step.
Forming a scan line, a signal line and the pixel electrode
The wiring connecting the thin film transistor is connected to the low step portion.
Has only forming on, and forming the pixel electrode, connecting the said pixel electrode TFT said
Wiring should be connected only at the lower part of the step
A method for manufacturing an active matrix substrate, comprising: 2. A thin film is formed on a transparent insulating substrate having a smooth surface.
Of the region consisting of transistors and scanning lines and signal lines
Equal to or higher than the top
Having a thicker transparent insulating layer, the thin film transistor
Is the transparent insulating substrate in the concave portion formed in the transparent insulating layer
The thin film transistor and the pixel electrode are formed on
In the recess, the thin film transistor and the pixel electrode
Characterized by being connected by wiring that connects
Active matrix substrate. (3) The pixel electrode portion on the transparent electrode has a flat surface
The activator according to claim 2, wherein the activator is formed.
Matrix substrate.