JPH0850302A - Production of thin film transistor panel - Google Patents

Abstract

PURPOSE:To form an electrode for a capacitor consisting of a transparent electrically conductive film at a low cost without using an exposure mask to expose a photoresist film to a specified pattern and moreover, without using an expensive high-accuracy exposing device. CONSTITUTION:After a gate line 2 consisting of a metal film is formed on a substrate 1, a transparent electrically conductive film 11a is formed on the substrate 1 and a negative photoresist film 12 is formed on the transparent electrically conductive film 11a. The resist film 12 is exposed from the lower surface side of the substrate 1 by using the gate line 2 as a light-shielding film and then developed to remove the resist film on the gate line 2. Then, the transparent electrically conductive film 11a is etched till the part deposited on the side faces of the gate line 2 is completely removed. Thus, the transparent electrically conductive film 11a remaining under the resist film 12 is used as the electrode 11 for a capacitor.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thin film transistor panel (hereinafter referred to as a TFT panel) used for an active matrix liquid crystal display device.

[0002]

2. Description of the Related Art A TFT panel used for an active matrix liquid crystal display device has a plurality of transparent pixel electrodes arranged side by side in a row direction and a column direction on a transparent substrate made of glass or the like. A plurality of thin film transistors (TFTs) are arranged corresponding to each other, and a gate line for supplying a gate signal to each thin film transistor of each pixel electrode row is provided, and for each pixel electrode column, each thin film transistor of that column is provided. The data line for supplying the data signal is provided.

As this TFT panel, it is generally known that the gate line is wired on a substrate and the data line is wired on an insulating film provided on the substrate, and the thin film transistor is the gate line. A gate electrode integrally formed with the gate electrode, a gate insulating film covering the gate electrode, an i-type semiconductor film formed on the gate insulating film, and an n-type semiconductor film on the i-type semiconductor film. It is composed of a source electrode and a drain electrode formed as described above.

The gate insulating film is a transparent insulating film made of Si N (silicon nitride) or the like. The gate insulating film is provided on almost the entire surface of the substrate, and the pixel electrode is formed on the gate insulating film. It is formed and is connected to the source electrode of the thin film transistor at its edge.

On the other hand, the data line is laid on an interlayer insulating film formed on the gate insulating film so as to correspond to the data line wiring region, and the data line is formed on the contact formed on the interlayer insulating film. The hole is connected to the drain electrode of the thin film transistor.

And, the active matrix liquid crystal display device comprises the above-mentioned TFT panel and the above-mentioned TFT on a transparent substrate.
It is configured by joining a counter panel provided with a counter electrode facing all pixel electrodes of the panel via a frame-shaped sealing material, and enclosing a liquid crystal in a region surrounded by the sealing material of both panels. There is.

This active matrix liquid crystal display device is driven for display by supplying a gate signal to the thin film transistors in each row during the selection period of the pixels in each row and applying a data signal to the thin film transistors in each column in synchronization with it. When the thin film transistor is turned on by applying the gate signal during the selection period, a voltage corresponding to the data signal is applied between the pixel electrode and the counter electrode through the thin film transistor, and the charge is applied to the pixel electrode and the counter electrode and the liquid crystal between them. And is stored in the pixel capacity configured by.

In the non-selection period, the charge accumulated in the pixel capacitor is held in the pixel capacitor by turning off the thin film transistor, and the voltage corresponding to the amount of charge becomes the holding voltage of the pixel capacitor. The liquid crystal rises in response to the holding voltage of.

In the active matrix liquid crystal display element, when the thin film transistor is turned off during the non-selection period, the voltage accumulated in the pixel capacitance during the selection period is the same as that of the pixel capacitance and the thin film transistor in the voltage change of the gate signal. The voltage is reduced by a voltage corresponding to the capacitance ratio between the gate-source capacitance (the capacitance between the gate electrode and the source electrode). This voltage drop is larger as the gate-source capacitance is larger than the pixel capacitance.

Therefore, in the above-mentioned active matrix liquid crystal display element, the TFT panel is provided with an additional capacitor for compensating for a drop in the voltage held in the pixel capacitor.
A sufficient holding voltage for the pixel electrode capacitance is ensured.

This additional capacitance is obtained by providing a capacitance forming electrode facing the pixel electrode across the gate insulating film on the substrate so that the capacitance forming electrode and the pixel electrode and the gate insulating film between them are provided. It is composed of.

By the way, the capacitance forming electrode constituting the additional capacitance is generally formed of the same metal film as the gate line, but when the capacitance forming electrode is formed of a metal film,
Since the area of the light transmission region of each pixel is reduced by the area where the capacitance forming electrode and the pixel electrode face each other, the aperture ratio of the liquid crystal display element is reduced.

For this reason, it has been conventionally considered that the capacitance forming electrode is formed of a transparent conductive film such as an ITO film. If the capacitance forming electrode is formed of a transparent conductive film as described above, a liquid crystal display is formed. The aperture ratio of the device can be increased, and the area of the capacitance forming electrode can be increased to increase the capacitance value of the additional capacitance.

In the conventional capacitor forming electrode made of a transparent conductive film, after a gate line made of a metal film is formed on a substrate, a transparent conductive film such as an ITO film is formed on the substrate by a sputtering device or the like. The transparent conductive film is patterned by photolithography.

[0015]

However, conventionally, a capacitor forming electrode made of a transparent conductive film is formed on a substrate, and then a photoresist film is formed on the transparent conductive film. Since the resist film is formed by a method of exposing the resist film using an exposure mask having a predetermined pattern, developing the resist film, patterning the resist film, and then etching the transparent conductive film. An exposure mask for exposing the photoresist film to a predetermined pattern is indispensable for forming the electrodes, and therefore the manufacturing cost of the exposure mask is high, and the exposure mask is aligned with high accuracy to form a resist film. Since it has to be exposed to light, it is necessary to use an expensive high precision exposure processing device for exposure processing of the resist film,
There is a problem that the formation cost of the capacitance forming electrode becomes high.

The present invention does not use an exposure mask for exposing a capacitance forming electrode made of a transparent conductive film to a predetermined pattern on a photoresist film, and does not use an expensive high precision exposure processing apparatus. It is an object of the present invention to provide a method for manufacturing a TFT panel that can be formed at low cost.

[0017]

According to the method of manufacturing a TFT panel of the present invention, a gate line made of a metal film is formed on a substrate, a transparent conductive film is formed on the substrate, and the transparent conductive film is formed. A negative photoresist film is formed on the resist film, and the resist film is exposed from the lower surface of the substrate using the gate line as a light-shielding film and then developed to remove the resist film on the gate line. After that, the transparent conductive film is etched until all the portions attached to the side surfaces of the gate line are removed, and the transparent conductive film left under the resist film is used as a capacitance forming electrode. It is what

[0018]

In the method of manufacturing the TFT panel of the present invention,
A transparent conductive film is formed on the substrate on which the gate line is formed,
Since a photoresist film is formed on this and the resist film is exposed from the lower surface side of the substrate, a gate line made of a metal film is formed in the light irradiated from the lower surface side of the substrate. The irradiation light to the exposed portion is blocked by the gate line, and the resist film is exposed except the portion above the gate line.

Since the resist film is a negative type photoresist film, when the exposed resist film is developed, the unexposed resist film on the gate line is removed. When the film is etched, the portion of the transparent conductive film above the gate line is etched, and the portion adhered to the side surface of the gate line is also etched.

Therefore, if the transparent conductive film is etched until the entire portion of the side surface of the gate line is removed, the transparent conductive film is separated from the gate line and left under the resist film. The transparent conductive film serves as a capacitance-forming electrode that is electrically separated from the gate line.

The manufacturing method of this TFT panel is as follows.
A transparent conductive film is formed on the substrate on which the gate line is formed,
After the photoresist film is formed on the transparent conductive film, the exposure process of the resist film is performed from the lower surface side of the substrate by using the gate line as a light-shielding film. Since it is not necessary to use an exposure mask for performing an exposure process on a pattern, and therefore, it is not necessary to use an expensive high-precision exposure processing device unlike the exposure process using an exposure mask, and therefore a capacitance forming electrode made of a transparent conductive film is used. Can be formed at low cost.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a sectional view in each step showing a step of forming a capacitance forming electrode, and FIG. 2 is a plan view of a part of the manufactured TFT panel.

First, the manufactured TFT panel will be described. In this TFT panel, a gate line 2 made of a metal film and a gate electrode 4 are integrally formed on the gate line 2 on a transparent substrate 1 made of glass or the like. A thin film transistor 3, a pixel electrode 9 formed on the gate insulating film 5 of the thin film transistor 3 and connected to the source electrode 7 of the thin film transistor 3, and a data line 10 connected to the drain electrode 8 of the thin film transistor 3. A capacitance forming electrode 11 is provided on the substrate 1 so as to face the pixel electrode 9 across the gate insulating film 5, and the capacitance forming electrode 11 and the pixel electrode 9 and the space between them are provided. The additional capacitance is configured with the gate insulating film 5.

The thin film transistor 3 has a gate electrode 4 formed integrally with the gate line 2, a gate insulating film 5 covering the gate electrode 4, and a-Si (aSi (i) formed on the gate insulating film 5. An i-type semiconductor film 6 made of amorphous silicon or the like, and a source electrode 7 formed on the i-type semiconductor film 6 via an n-type semiconductor film (not shown) made of impurity-doped a-Si or the like. And the drain electrode 8.

The gate insulating film 5 is a transparent insulating film made of SiN or the like, and the gate insulating film 5 is provided on almost the entire surface of the substrate 1. Although not shown, the terminal portion of the gate line 2 is exposed by forming an opening in the gate insulating film 5.

The pixel electrode 9 is formed of a transparent conductive film such as an ITO film on the gate insulating film 5 and is connected to the source electrode 7 of the thin film transistor 3 at its edge.

Although the data line 10 is shown integrally with the drain electrode 8 of the thin film transistor 3 in FIG.
The data line 10 is wired on an interlayer insulating film (not shown) formed on the gate insulating film 5 so as to correspond to the data line wiring region, and in the contact hole provided in the interlayer insulating film. It is connected to the drain electrode 8 of the thin film transistor 3.

Further, the capacitance forming electrode 11 constituting the additional capacitance is made of a transparent conductive film such as an ITO film, and the capacitance forming electrode 11 extends along substantially the entire length of each gate line 2. The width is formed to be slightly smaller than the distance between the adjacent gate lines 2 and 2.

Next, a method of manufacturing the above TFT panel will be described with reference to FIG.
Will be described with reference to. First, as shown in FIG. 1A, the gate line (including the gate electrode 4 of the thin film transistor 3) 2 is formed on the substrate 1. This gate line 2 is formed of Al (aluminum) or Al on the substrate 1.
A metal film of a system alloy or the like is formed by a sputtering device or the like, and the metal film is patterned by photolithography.

Next, as shown in FIG. 1B, a transparent conductive film 11a such as an ITO film is formed on the substrate 1 on which the gate line 2 is formed by a sputtering device or the like. The transparent conductive film 11a is formed to be much thinner than the gate line 2.

Then, as shown in FIG. 1C, a negative photoresist film 12 is formed on the transparent conductive film 11a.
And the resist film 12 is exposed from the lower surface side of the substrate 1.

The resist film 12 is formed by applying a negative photoresist on the transparent conductive film 11a by a spin coater to a uniform thickness and drying the applied film. The exposure processing of the resist film 12 is performed by irradiating the entire substrate 1 with light (ultraviolet rays) from the lower surface side.

Thus, the resist film 12 is applied to the substrate 1
When the exposure process is performed from the lower surface side of the substrate 1, among the light irradiated from the lower surface side of the substrate 1, the light irradiated to the portion of the substrate 1 where the gate line 2 is formed is the gate line 2 formed of the metal film. The resist film 12 is exposed to light, and the resist film 12 is exposed except for the portion above the gate line 2.

Then, the exposed resist film 12 is developed to remove the resist film on the gate line 2.
As shown in FIG. 1D, a portion of the transparent conductive film 11a above the gate line 2 is exposed.

Since the resist film 12 is a negative type photoresist film, the exposed resist film 12
Is developed, the unexposed resist film on the gate line 2 is removed.

Next, the transparent conductive film 11a is etched by a wet etching apparatus until all the portions deposited on the side surfaces of the gate line 2 are removed, and the transparent conductive film left under the resist film 12 is etched. The film 11a is used as the capacitance forming electrode 11, the resist film 12 is then peeled off, and the formation process of the capacitance forming electrode 11 is completed. FIG. 1E shows a state when the formation process of the capacitance forming electrode 11 is completed.

In this way, the transparent conductive film 11a is removed with the portion of the resist film 12 above the gate line 2 removed.
When the etching is performed, the portion of the transparent conductive film 11a above the gate line 2 is etched, and the portion attached to the side surface of the gate line 2 is also etched. The portion adhered to the side surface is removed.

Incidentally, the etching of the transparent conductive film 11a may be carried out only for the etching time by grasping in advance the etching time required to completely remove the portion adhered to the side surface of the gate line 2.

Then, when all the portions of the transparent conductive film 11a attached to the side surfaces of the gate line 2 are removed, the transparent conductive film 11a is separated from the gate line 2 as shown in FIG. 1 (e). Then, the transparent conductive film 11a left under the resist film 12 becomes the capacitance forming electrode 11 electrically separated from the gate line 2.

In this way, the transparent conductive film 11 is formed on the substrate 1.
After forming the capacitance forming electrode 11 made of a, a gate insulating film 5 is formed on the substrate 1, and an i-type semiconductor film, an n-type semiconductor film, a source and drain electrode metal film are sequentially formed on the gate insulating film 5. A thin film transistor 3 is formed by film-forming and patterning these, and further a pixel electrode 9 and a data line 10 are formed to complete the TFT panel shown in FIG. Since the formation of the thin film transistor 3, the formation of the pixel electrode 9 and the formation of the data line 10 are performed by a known method, the description thereof will be omitted.

That is, in the above-mentioned method for manufacturing a TFT panel, after forming the gate line 2 made of a metal film on the substrate 1, the transparent conductive film 11a is formed on the substrate 1 and the transparent conductive film 11a is formed. A negative photoresist film 12 is formed on the resist film 12, and the resist film 12 is exposed from the lower surface side of the substrate 1 and then developed to remove the resist film on the gate line 2 and then the transparent conductive film. The film 11a is etched until the entire portion of the side surface of the gate line 2 is removed to remove the resist film 12
The transparent conductive film 11a left under is used as a capacitance forming electrode.

Then, this manufacturing method uses the gate line 2
After the transparent conductive film 11a is formed on the substrate 1 on which the photoresist film 12 is formed, and the photoresist film 12 is formed on the transparent conductive film 11a, the exposure process of the resist film 12 is performed from the lower surface side of the substrate 1. Since the gate line 2 is used as a light-shielding film, it is not necessary to use an exposure mask for exposing the photoresist film 12 to a predetermined pattern. Therefore, it is expensive and expensive like the exposure process using an exposure mask. There is no need to use precision exposure processing equipment,
The capacitance forming electrode 11 made of the transparent conductive film 11a can be formed at low cost.

[0043]

According to the method of manufacturing a TFT panel of the present invention, after a gate line made of a metal film is formed on a substrate, a transparent conductive film is formed on the substrate and a negative film is formed on the transparent conductive film. Type photoresist film is formed, and the resist film is exposed from the lower surface side of the substrate using the gate line as a light-shielding film and then developed to remove the resist film on the gate line, and then the transparent conductive film is formed. The membrane
Since the transparent conductive film left under the resist film is used as a capacitance-forming electrode by etching until all the parts deposited on the side surfaces of the gate line are removed, the photoresist film is formed into a predetermined pattern. Therefore, it is not necessary to use an exposure mask for performing the exposure process, and therefore it is not necessary to use an expensive high-precision exposure processing apparatus unlike the exposure process using the exposure mask. It can be formed at low cost.

[Brief description of drawings]

FIG. 1 is a sectional view of each step showing a step of forming a capacitance forming electrode according to an embodiment of the present invention.

FIG. 2 is a plan view of a part of the manufactured TFT panel.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Substrate 2 ... Gate line 3 ... Thin film transistor 4 ... Gate electrode 5 ... Gate insulating film 6 ... i-type semiconductor film 7 ... Source electrode 8 ... Drain electrode 9 ... Pixel electrode 10 ... Data line 11 ... Capacitance formation electrode 11a ... Transparent Conductive film 12 ... Resist film

Claims (1)

[Claims] 1. A thin film transistor having a gate line and a gate electrode integrally formed on the gate line on a transparent substrate, and a thin film transistor formed on a gate insulating film of the thin film transistor and connected to a source electrode of the thin film transistor. A pixel electrode and a data line connected to the drain electrode of the thin film transistor are provided, and a capacitance forming electrode facing the pixel electrode across the gate insulating film is provided on the substrate to form the capacitance. A method of manufacturing a thin film transistor panel in which an additional capacitance is constituted by a working electrode, the pixel electrode, and the gate insulating film between the electrodes, wherein after forming a gate line made of a metal film on the substrate, a transparent conductive film is formed on the substrate. A film is formed and a negative photoresist film is formed on this transparent conductive film.
The resist film is exposed from the lower surface side of the substrate using the gate line as a light-shielding film and then developed to remove the resist film on the gate line, and then the transparent conductive film is formed on the side surface of the gate line. A method for manufacturing a thin film transistor panel, characterized in that the transparent conductive film left under the resist film is used as a capacitance-forming electrode by etching until all the portions adhered to are removed.