JPH079518B2 - Display device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a display device using a thin film transistor array, in which the resistance of wiring is reduced when the area and the resolution are increased, and the characteristics of the array are improved. The present invention relates to a display device intended to be improved.

[Conventional technology]

The above-mentioned display device is usually constructed by sandwiching a display medium such as a liquid crystal or an electrochromic (hereinafter referred to as EC) material between two opposing substrates and applying a voltage to the display medium.

At this time, pixel electrodes arranged in a matrix are provided on at least one substrate, and a non-linear switching element such as FET (field effect transistor) and diode is provided for each pixel in order to selectively operate these pixels. ing.

Conventionally, a thin film transistor array forming this type of display device is as shown in FIGS. FIG. 4 is a partial plan view of a thin film transistor array formed by a conventional method, and FIGS. 5 and 6 are A of FIG.
It is a sectional view of the -A line and the BB line.

In FIG. 4 to FIG. 6, the transparent insulating substrate 1
A light-shielding film 2, a passivation film 3, a source electrode / wiring 4 and a drain / pixel electrode 5 are sequentially formed thereon.

A semiconductor film 6, a gate insulating film 7, and a gate electrode 8 are sequentially formed on the passivation film 3.

When forming a transmissive display such as a liquid crystal display device, there is a method in which the source electrode, the wiring 4 and the drain / pixel electrode 5 are simultaneously formed by a transparent conductive film such as ITO (Indium Tin Oxide). In order to form the upper semiconductor layer without cutting at the step of the source and drain electrodes, the ITO film of the source and drain electrodes should be thin, usually around 1000Å. .

[Problems to be solved by the invention]

Therefore, the display area becomes large and the resistance of the source electrode / wiring 4 becomes high when a high-resolution display is formed. For example, the source wiring is 10 cm long and 30 μm wide
When it is formed in, the resistance is 100 KΩ or more, and when a signal is input here, the signal is greatly attenuated, and the time constant, which is the product of the resistance and the input capacitance (for example, 50 pF or more), is 10
There was a shortcoming when it became difficult to operate at high frequency for more than μsec.

Further, since the interlayer insulation at the intersection of the source electrode wiring 4 and the wiring of the gate electrode 8 is performed by both the semiconductor layer 6 and the gate insulating film 7, the semiconductor layer 6 and the gate insulating layer 7 are formed below the wiring of the gate electrode 8. Both remain, and accordingly, the source electrode wiring 4
In addition to the fact that the interlayer insulation between the wiring of the gate electrode 8 and the gate electrode 8 is not reliable and causes a short circuit, a field transistor is generated, which cannot be ignored when the pixel size is reduced due to the increase in resolution. Was a cause of deterioration of the characteristics of.

The present invention has been made in order to solve such a problem, and reduces a signal attenuation due to a reduction in resistance of a source wiring, enables a high speed operation, and has a high display quality in which a field transistor is not formed. Aim to get.

[Means for solving problems]

In the display device according to the present invention, the source wiring is formed by using the low resistance metal at the same time as the formation of the light shielding film, and the source electrode wiring not having the function of the source wiring is formed at the same time as the drain electrode in the passivation film. is there.

[Work]

In this invention, since the original source electrode wiring does not have the function of the source wiring, the passivation film also serves as the gate electrode and the interlayer insulating film between the wiring and the source wiring, and the semiconductor layer is formed below the wiring of the gate electrode. The field transistor is not formed without leaving the field transistor.

〔Example〕

An embodiment of a display device of the present invention will be described below with reference to the drawings. FIG. 1 is a plan view of a thin film transistor array used in the embodiment, and FIGS. 2 and 3 are sectional views taken along the lines CC and DD of FIG. 1, respectively.

In FIGS. 1 to 3, the same parts as those of FIGS. 4 to 6 are designated by the same reference numerals. 9 is a source wiring, 10 is a contact hole, 11 is a contact film,
These parts are the parts newly formed by the present invention.

The manufacturing process of the specific constitution of the present invention will be described below. First, the transparent and highly insulating substrate 1 such as glass is mirror-polished to clean the surface.

Next, a low resistance metal such as Al, a metal compound or a metal alloy is deposited by a vacuum deposition method or the like.

After that, the line-shaped source wiring 9 is formed simultaneously with the island-shaped light-shielding film 2 by a method such as photolithography.

Next, as the passivation film 3, a transparent insulating film such as Si ₃ N ₄ or SiO ₂ is deposited by the CVD method or the like.

Next, the source electrode wiring 4 and the drain / pixel electrode 5 are
It is formed using a transparent conductive film such as ITO.

The source electrode wiring 4 formed here is independent for each pixel and does not function as a source wiring.

Next, a semiconductor layer 6 of a-Si, p-Si, CdSe or the like is formed in an island shape, and a gate insulating film 7 is formed of an insulating film of Si ₃ N ₄ , SiO ₂ , Al ₂ O ₃ or the like.

Here, a contact hole 10 for connecting the source electrode wiring 4 formed of a transparent conductive film to the passivation film 3 and the source wiring 9 simultaneously formed with the light shielding film 2 is formed.

Finally, the gate electrode 8 and its wiring are formed of a metal such as Al, a metal compound or a metal alloy. At this time, at the same time, the source electrode wiring 4 and the light shielding film 3 formed of transparent electrodes
A contact film 11 for connecting the source wiring 9 formed simultaneously with is formed.

The thin film transistor array substrate thus formed and a substrate having other transparent electrodes and color filters are kept at a predetermined distance, and a display medium such as liquid crystal or EC material is placed between these two substrates. The display device is completed by inserting.

The thin film transistor array and the display device having the above configuration,
Since the source wiring 9 is made of a metal, a metal compound or a metal alloy, it is possible to reduce the resistance. For example,
When Al is used for the source wiring 9, the length is 10 cm and the width is 20
The resistance is 2KΩ or less when μm and the thickness is 3000Å, which can be reduced by two digits or more compared with the case of ITO alone. Therefore, there is no signal attenuation due to resistance loss.

Also, the time constant, which is the product of the resistance and the input capacitance, is reduced by two digits or more, and high-frequency operation becomes possible.

Further, since the passivation film 3 serves as the interlayer insulation between the source wiring and the gate wiring, the reliability of the interlayer insulation is improved and the short circuit between the gate wiring and the source wiring can be extremely reduced by increasing the thickness of the passivation film. .

Further, since there is no semiconductor layer below the wiring of the gate electrode 8, no field transistor is generated and the characteristics of the entire thin film transistor array are improved.

Moreover, the number of steps is only one more than the conventional method of forming contact holes.

Therefore, when a large-area, high-resolution display device is formed by using the present invention, a display device with extremely high display quality can be obtained by a simple process.

〔The invention's effect〕

As described above, according to the present invention, the source wiring having a low resistance is formed simultaneously with the light-shielding film on the substrate to reduce the resistance of the source wiring, the signal is not attenuated, the time constant is reduced, and the high speed operation can be performed.

In addition, the source electrode wiring formed at the same time as the drain / pixel electrode is not provided with the function of the source wiring, so that the passivation film also serves as the interlayer insulation between the gate wiring and the source wiring, and the semiconductor layer is not left under the gate wiring. Therefore, the field transistor is not formed, and the performance as an array is improved. Along with this, there is an effect that a display device with high display quality can be obtained.

[Brief description of drawings]

FIG. 1 is a partial plan view of a thin film transistor array which constitutes an embodiment of the display device of the present invention, FIG. 2 is a sectional view taken along the line CC of FIG. 1, and FIG. FIG. 4 is a sectional view taken along line D, FIG. 4 is a partial plan view of a thin film transistor array constituting a conventional display device, FIG. 5 is a sectional view taken along line AA of FIG. 4, and FIG. 6 is B- of FIG. It is sectional drawing of a B line. 1 ... Substrate, 2 ... Shading film, 3 ... Passivation film, 4 ... Source electrode wiring, 5 ... Drain / pixel electrode, 6 ... Semiconductor film, 7 ... Gate insulating film, 8 ... Gate electrode, 9: Source wiring, 10: Contact hole, 11
…… Contact film. The same reference numerals in the drawings indicate the same or corresponding parts.

Claims (2)

[Claims] 1. A thin film transistor array having a light-shielding film, a passivation layer, a drain / pixel electrode and a source electrode wiring formed at the same time, a semiconductor film, a gate insulating film, and a gate electrode on the uppermost layer on a transparent insulating substrate. , And a display device having a display material such as a liquid crystal or an electrochromic material between the substrate of the thin film transistor array and a counter electrode substrate having a transparent electrode, a color filter, etc., at the same time when the source wiring is formed of the light shielding film, A display device formed using a low resistance metal, a metal compound or an alloy. 2. The thin film transistor array comprises a drain
The source electrode wiring formed at the same time as the pixel electrode functions only as a so-called source electrode and does not function as a source wiring. The source wiring formed simultaneously with the formation of the light-shielding film is opened in the passivation layer. The display device according to claim 1, wherein the display device is connected through a contact hole and the field effect transistor is not formed by forming the semiconductor film into an island shape.