JPH0812539B2 - Display device and manufacturing method thereof - Google Patents

Description

TECHNICAL FIELD OF THE INVENTION The present invention relates to a display device using a thin film transistor (TFT) array.

[Technical background of the invention and its problems]

In recent years, a liquid crystal display device in which a TFT array using a polycrystalline or amorphous semiconductor thin film is integrally formed and used as a drive circuit substrate has attracted attention. In particular, this type of display device can use a glass substrate because the semiconductor thin film can be formed at a low temperature, and therefore can reduce the cost, and can increase the area by directly applying the conventional exposure technology, etching technology, etc. Has the advantage that

FIG. 3 shows the structure of one pixel portion of a conventional drive circuit board. (A) is a plan view and (b) is an AA 'sectional view thereof. Reference numeral (1) is a glass substrate, on which a gate electrode (2) is formed, and an amorphous silicon (a-Si) film, for example, is formed on the glass substrate via a gate insulating film (3) such as a plasma SiO ₂ film. (4) is formed. a-Si film (4)
A drain electrode (5) and a source electrode (6) are formed on the substrate, and the source electrode (6) is connected to the display pixel electrode (7) made of a transparent conductive film. The gate electrode (2) is integrally formed with the address line Xi arranged in the row direction of the matrix, whereby the gate electrodes of the TFTs in the row direction are all commonly connected. Further, the drain electrode (5) is integrally formed with the data line Yj arranged in the column direction of the matrix, and the drain electrodes of the TFTs in the column direction thereby are all commonly connected.

Although not shown in the figure, this drive circuit substrate is actually covered with a protective film such as SiO ₂ except for the display pixel electrode (7). Then, a matrix type liquid crystal display device is constructed by sandwiching liquid crystal between the drive circuit substrate and a counter substrate having a counter electrode formed on the entire surface.

By the way, as the area of this type of liquid crystal display device becomes large, short-circuiting between the address line and the data line increases due to a poor withstand voltage of the insulating film in the gate electrode step portion, a pinhole or the like.

A line defect is generated due to this type of cause, and the display quality is significantly deteriorated.

[Object of the Invention] The present invention has been made by paying attention to the above points. By eliminating the step caused by the thickness of the address line, the insulating film formed thereon has a sufficient film thickness, and the withstand voltage defect is caused. It is an object of the present invention to provide a display device which prevents the deterioration of display quality. It is another object of the present invention to provide a method of manufacturing a display device, which can easily form a display device that prevents such deterioration of display quality.

SUMMARY OF THE INVENTION The present invention is a thin film transistor in which a substrate, an insulating film formed in two layers on the substrate, a source and a drain are formed on the insulating film, and a gate electrode is formed through the insulating film. An address line formed integrally with the gate electrode and a data line formed integrally with one of the source and the drain, which are vertically arranged in a direction orthogonal to each other through the insulating film, In a display device having a display electrode formed on a film and connected to the other of the source and the drain, the display device has a hole formed in the lower insulating film, and the address line is embedded in the hole. The present invention provides a display device having a thickness substantially the same as that of an underlying insulating film.

Further, the present invention provides a substrate, an insulating film formed on the substrate in upper and lower two layers, a thin film transistor in which a source and a drain are formed on the insulating film, and a gate electrode is formed through the insulating film, An address line which is arranged above and below and in a direction orthogonal to each other through a film, and which is integrally formed with the gate electrode, and a data line which is integrally formed with one of the source or the drain, and the data line which is formed on the insulating film above. In a method of manufacturing an address line in a display device having a display electrode connected to the other of a source and a drain, a step of forming the lower insulating film on the substrate, and forming a mask on the lower insulating film. A step of etching and removing the lower insulating film from the mask to form a hole, and a step of forming the hole on the lower insulating film and on the entire surface of the mask with the lower insulating film. Forming a thick metal layer,
A step of removing the unnecessary metal layer other than the holes together with the mask to form the address line; and a step of forming the upper insulating film on the entire surface of the lower insulating film and the address line. The present invention provides a method for manufacturing a display device.

[Effect of the Invention] According to the first aspect of the present invention, by burying the address line in the recess of the insulating film of the substrate, it is possible to reduce the step difference of the base of the interlayer insulating film formed on the substrate. Therefore, it is possible to provide a display device with high display quality by preventing occurrence of short circuit or leak current between the address line and the data line due to poor withstand voltage or pinhole or the like caused by thinning of a part of the interlayer insulating film. . Also, since it is possible to prevent the occurrence of short circuit or leakage current regardless of the thickness of the address line, the degree of freedom in designing the thickness of the wiring is increased, and the thickness of the address line is made thicker than usual to lower the line resistance and increase the resistance. It is possible to provide a display device that is most suitable for increasing the area.

Further, according to the second aspect of the invention, since the step of forming the recess in the insulating film on the substrate and then burying the address line in the recess is performed, the mask in which the recess is formed is used as it is as the mask for burying the address line. (Lift-off method) is possible, and it is possible to easily form a display device which is flattened by the address line self-aligned with the concave portion and has excellent display quality without complicated steps.

[Embodiment of the Invention] FIG. 1 is a sectional view showing a part of a TFT array portion of an embodiment of the present invention in the order of manufacturing steps. FIG. 2 is a cross-sectional view of a TFT array portion formed through a manufacturing process subsequent to the manufacturing process shown in FIG. 2 is a cross-sectional view of the TFT array section shown in FIG. 1 corresponding to the AA ′ cross section of FIG. 3 (a). Is attached.

First, the manufacturing method will be described with reference to FIG. A first insulating film SiO ₂ (31) is deposited on the glass substrate (1) at 3000 Å (hereinafter, abbreviated as A) (FIG. 1A).

After that, a resist is coated and the desired pattern is exposed and etched to form a resist mask (101).
Are formed (FIG. 1 (b)).

Then, SiO ₂ (3
1) is etched to form a recess. Further, from above the resist mask (101), Al (2) 2000A, Mo (21) 1200A
Are continuously sputtered (FIG. 1 (c)).

After that, by removing the resist mask (101), unnecessary Al and Mo on the mask are removed by a lift-off method, and Al (2) and Mo (21) embedded in the recess are left as a gate electrode (first). Figure 1 (d)).

Then, SiO ₂ (31) and the gate electrode are covered with 2000 A of SiO ₂ and 3000 A of a-Si film (4) on the entire surface of the gate electrode.
Continuous film formation, a-Si film (4) is etched into an island shape,
Furthermore, after forming a transparent conductive film for display by 1200 A by sputtering, the shape is processed by etching, and the display electrode (7)
Was formed. Further, Al is vapor-deposited with a thickness of 1 μm and patterned to form a source electrode (6) and a drain electrode (5). The source electrode (6) is connected to the display electrode (7), and the drain electrode is integrally formed with the data line. At this point, the manufacturing process of the thin film transistor and the display electrode is completed (FIG. 2). As described above, only the portion corresponding to the AA 'cross section of FIG. 3 has been described with reference to FIGS. 1 and 2, so that only the gate electrode embedded in the recess is shown in FIG. Actually, the address line formed of the same wiring material layer (Al / Mo laminated film) as the gate electrode is also embedded and formed in the recess through the same manufacturing process as the gate electrode.

Since the address line of the device manufactured by such a manufacturing process is thick as Mo / Al3000A, the line resistance is reduced, which is most suitable for increasing the area. In addition, the step difference of the gate electrode was improved and the breakdown voltage was improved, and the interlayer short between the address line and the data line was as small as several lines as compared with the conventional method. The cause of the short circuit in the conventional method is considered to be a poor withstand voltage at the stepped portion of the gate electrode or a pinhole at the stepped portion.

As described above, by using the structure of the present invention, the breakdown voltage is improved, the cause of the short circuit between the address line and the data line is reduced, and since the gate electrode can be thickened, it is easy to reduce the line resistance, and the large area display device Optimal, yet significantly improves the display quality.

[Brief description of drawings]

FIG. 1 is a sectional view showing a gate electrode formation by lift-off according to an embodiment of the present invention, FIG. 2 is a sectional view showing a TFT array portion and a pixel portion according to an embodiment of the present invention, and FIG. 3 is a plan view of a conventional example. It is a figure which shows and sectional drawing. 1 …… Glass substrate 2 …… Gate electrode (Al) 21 …… Gate electrode (MO) 3 …… Gate insulating film (SiO ₂ ) 31 …… First insulating film (SiO ₂ ) 4 …… a-Si film 5 , 6 …… Source / drain electrode (Al) 7 …… Display electrode (ITφ) 101 …… Resist

Claims (4)

[Claims] 1. A substrate, an insulating film formed in two layers above and below the substrate, a thin film transistor in which a source and a drain are formed on the insulating film and a gate electrode is formed through the insulating film, and the insulating film. An address line integrally formed with the gate electrode and a data line integrally formed with one of the source and the drain, which are vertically arranged through a film and are orthogonal to each other, and formed on the insulating film above. And a display electrode connected to the other of the source and the drain, the display device having a hole formed in the lower insulating film, and the address line embedded in the hole, the lower insulating film. And a display device having substantially the same thickness as the display device. 2. The display device according to claim 1, wherein the insulating film is made of at least one of silicon dioxide, silicon nitride and polyimide. 3. The display device according to claim 1, wherein the address line is formed by laminating at least one metal layer. 4. A substrate, an insulating film formed on the substrate in upper and lower two layers, a thin film transistor in which a source and a drain are formed on the insulating film, and a gate electrode is formed through the insulating film, and the insulating film. An address line which is arranged above and below and in a direction orthogonal to each other through a film, and which is integrally formed with the gate electrode, and a data line which is integrally formed with one of the source or the drain, and the data line which is formed on the insulating film above. In a method of manufacturing an address line in a display device having a display electrode connected to the other of a source and a drain, a step of forming the lower insulating film on the substrate, and forming a mask on the lower insulating film. A step of forming a hole by etching and removing the lower insulating film from above the mask, and substantially the same as the lower insulating film above the lower insulating film and on the entire surface of the mask Forming an address line by removing the unnecessary metal layer other than the hole together with the mask, and forming the address line on the entire surface of the lower insulating film and the address line. And a step of forming an insulating film.